WO2005099960A2 - A polyethylene product and a method of providing a product, such as a laser welded polyethylene product - Google Patents

A polyethylene product and a method of providing a product, such as a laser welded polyethylene product Download PDF

Info

Publication number
WO2005099960A2
WO2005099960A2 PCT/DK2005/000251 DK2005000251W WO2005099960A2 WO 2005099960 A2 WO2005099960 A2 WO 2005099960A2 DK 2005000251 W DK2005000251 W DK 2005000251W WO 2005099960 A2 WO2005099960 A2 WO 2005099960A2
Authority
WO
WIPO (PCT)
Prior art keywords
providing
radiation
interface
predetermined
predetermined wavelength
Prior art date
Application number
PCT/DK2005/000251
Other languages
French (fr)
Other versions
WO2005099960A3 (en
Inventor
Frank Berg Rasmussen
Ingrid Læsøe FINK
Kim Bager
Carsten Thirstrup
Original Assignee
Coloplast A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/822,861 external-priority patent/US20050224472A1/en
Application filed by Coloplast A/S filed Critical Coloplast A/S
Priority to CN2005800164744A priority Critical patent/CN1956817B/en
Priority to US11/578,367 priority patent/US8084138B2/en
Priority to EP20050715168 priority patent/EP1737606B1/en
Priority to DE200560012937 priority patent/DE602005012937D1/en
Priority to DK05715168T priority patent/DK1737606T3/en
Publication of WO2005099960A2 publication Critical patent/WO2005099960A2/en
Publication of WO2005099960A3 publication Critical patent/WO2005099960A3/en

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/50General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/53Joining single elements to tubular articles, hollow articles or bars
    • B29C66/532Joining single elements to the wall of tubular articles, hollow articles or bars
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/18Working by laser beam, e.g. welding, cutting or boring using absorbing layers on the workpiece, e.g. for marking or protecting purposes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/16Laser beams
    • B29C65/1629Laser beams characterised by the way of heating the interface
    • B29C65/1635Laser beams characterised by the way of heating the interface at least passing through one of the parts to be joined, i.e. laser transmission welding
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/16Laser beams
    • B29C65/1677Laser beams making use of an absorber or impact modifier
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/004Preventing sticking together, e.g. of some areas of the parts to be joined
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/01General aspects dealing with the joint area or with the area to be joined
    • B29C66/05Particular design of joint configurations
    • B29C66/10Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/11Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/112Single lapped joints
    • B29C66/1122Single lap to lap joints, i.e. overlap joints
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/70General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/71General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/70General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/73General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
    • B29C66/739General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset
    • B29C66/7392General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic
    • B29C66/73921General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic characterised by the materials of both parts being thermoplastics
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/90Measuring or controlling the joining process
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/16Laser beams
    • B29C65/1603Laser beams characterised by the type of electromagnetic radiation
    • B29C65/1612Infrared [IR] radiation, e.g. by infrared lasers
    • B29C65/1616Near infrared radiation [NIR], e.g. by YAG lasers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/16Laser beams
    • B29C65/1629Laser beams characterised by the way of heating the interface
    • B29C65/1635Laser beams characterised by the way of heating the interface at least passing through one of the parts to be joined, i.e. laser transmission welding
    • B29C65/1641Laser beams characterised by the way of heating the interface at least passing through one of the parts to be joined, i.e. laser transmission welding making use of a reflector on the opposite side, e.g. a polished mandrel or a mirror
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/70General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/73General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
    • B29C66/731General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the intensive physical properties of the material of the parts to be joined
    • B29C66/7316Surface properties
    • B29C66/73161Roughness or rugosity
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/90Measuring or controlling the joining process
    • B29C66/95Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94
    • B29C66/959Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94 characterised by specific values or ranges of said specific variables
    • B29C66/9592Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94 characterised by specific values or ranges of said specific variables in explicit relation to another variable, e.g. X-Y diagrams
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29LINDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00Other particular articles
    • B29L2031/712Containers; Packaging elements or accessories, Packages
    • B29L2031/7148Blood bags, medical bags
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/13Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1334Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/24Structurally defined web or sheet [e.g., overall dimension, etc.]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31855Of addition polymer from unsaturated monomers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31855Of addition polymer from unsaturated monomers
    • Y10T428/31938Polymer of monoethylenically unsaturated hydrocarbon

Definitions

  • a POLYETHYLENE PRODUCT AND A METHOD OF PROVIDING A PRODUCT SUCH AS A LASER WELDED POLYETHYLENE PRODUCT
  • the present invention relates, in general, to the use of radiation for initiating or providing an effect and in particular to a manner and a polyethylene element which facilitates the concentration of a radiation intensity to a predetermined volume or at an interface or surface.
  • absorbers Normally, if absorption is desired in a material or an element in order to generate heat or other changes, an absorber is added to facilitate the absorption.
  • absorbers have a tendency, in addition to their main function of absorption, to change other physical or chemical parameters of the material in a non-desired manner.
  • One such parameter may be the colour of the means or material, and another may be the mechanical strength, which may both be adversely affected by the presence of the absorber.
  • the normally used absorbers can be relatively costly.
  • absorber In order to reduce these "side effects", less absorber may be used. This may, however, reduce the overall absorption to a level where the desired effect is not seen.
  • One particular application is laser welding, where radiation is transmitted to an interface between two abutting materials having different absorption of the radiation used.
  • the radiation is transmitted through the material having the lower absorption of the radiation so that, due to its higher absorption of the radiation, the other material is heated at the interface to a degree where melting and welding occurs.
  • the present invention relates to a solution to this problem in that it has been found that if a means or a material in addition to showing absorption at the wavelength in question also shows a not insignificant scattering, radiation transmitted away from the area/surface/- interface where the effect of the radiation is desired is not merely absorbed in other parts of the material (or output there from), but part of the transmitted radiation is scattered back toward the area/surface/interface in question. Consequently, a higher radiation intensity and a higher radiation absorption are experienced at that area/surface/interface.
  • the overall effect of the scattering is a limitation or reduction in the penetration depth or distance of the radiation into the means.
  • the scattering will act to scatter the radiation also back toward the volume where the radiation is desired.
  • the scattering may be selected (also inside the means) in order to provide the reflection at the desired positions in order to actually tai lor the means to the application in question.
  • the invention in a first aspect, relates to a method of providing a product, the method comprising: providing a PE element having an absorption coefficient, ⁇ a, and a scattering coefficient, ⁇ s, at a predetermined wavelength, wherein ⁇ s> (l/10)* ⁇ a, providing radiation comprising radiation at the predetermined wavelength to a predetermined volume at or near an interface or surface of the PE element.
  • the radiation may be monochromatic radiation, such as laser radiation, having the predetermined wavelength, or it may be polychromatic radiation. There need be no direct demands as to the radiation source.
  • the wavelength may be any wavelength. In fact, radiation may be used having a plurality of wavelengths in that most materials have absorptions at multiple wavelengths, so that the overall radiation intensity, heating, or other effect, may be obtained a lso using multiple wavelengths.
  • An interface may be an external surface of the PE element or may be an internal interface, such as between two parts of the PE element.
  • the predetermined volume receiving the radiation is present at the interface where the radiation is desired. The predetermined volume will be at the interface but may just as well be at an outer surface of the PE element as inside it.
  • the volume is normally defined by the radiation a nd the intensity thereof as a volume where the desired effect takes place, such as where the radiation intensity is large enough. However, a number of other manners exist of defining this volume.
  • the effect desired will then take place at the volume/interface. Depending on the situation (see below), the effect may be a surface-related effect or a bulk-related effect.
  • the absorption coefficient, ⁇ a, and the scattering coefficient, ⁇ s are two of the fundamental optical properties describing radiative transport in any medium. They are defined in standard textbooks such as C. F. Bohren and D. R. Huffman/ Absorption and Scattering of Light by Small Particle', John Wiley 8. Sons, Inc. 1983, ISBN 0-471-05772-X.
  • the absorption and scattering coefficients can be measured experimentally e.g. using the so- called integrating sphere method described e.g. by B. C. Wilson in Optical-Thermal
  • the absorption coefficient is determined by measuring all the light intensity transmitted or scattered by the material, so that the only loss is due to absorption.
  • the absorption coefficient is given by light intensity and I the measured light intensity.
  • the overall effect of the scattering of the PE element is that at least part of the radiation is absorbed in the predetermined volume, whereas another part of the radiation is transmitted further into the PE element (away from the volume). Part of this radiation transmitted further into the PE element is then scattered in a direction toward the predetermined volume. Naturally, this increases the intensity at the predetermined volume and at the interface.
  • Laser welding 2. Laser welding of foils with little absorption where a third medium in the form of a scattering plate is placed beneath the foils to be welded.
  • a surface property including: adhesion (tack, peel), absorption capacity of fluids (water), permeability for gases or fluids (porosity), cohesion, colour, appearance, odour, hydrophobicity, surface energy (contact angle), surface roughness, mechanical properties (elasticity, hardness, shear resistance, strength), friction coefficient, heat resistance, electrical conductivity, sound propagation (damping), optical properties, crystallinity, molecular orientation, molecular structure (cross linking, curing) etc.
  • Optical recording media such as a CD-R or a DVD-R usually are multi layer structures comprising a (laser) transparent substrate, a recording layer, an interlayer (metallic), a pressure sensitive adhesive layer and a cover film.
  • the recording layer typically contains an organic dye capable of absorbing light at the laser wavelength.
  • Information is recorded on the media using a laser to locally heat the recording layer causing a physical or chemical change that alters the optical properties of the layer (a pattern is formed). Irradiating the media with a laser of the sa me wavelength used to write the information and measuring the specular reflectivity reproduces the information.
  • UV-light induced processes such as cross-li nking or photochemistry.
  • Laser surface treatment of polymers with the aim of modifying the surface properties such as Chemical modification, Structural modification, Surface roughening and/or reducing hydrophobicity.
  • Surface roughening of a substrate is the major reason for the improved sticking of adhesives to a laser treated polymer surface.
  • UV curing of acrylic adhesives where the polymerisation is initiated by UV light.
  • hot melt bonding where heat is used to melt an adhesive (e.g. a thermoplastic) producing a low viscosity fluid that wets the surfaces of the pieces to be bonded.
  • a typical photo resist comprises a photosensitive material combined with a polymer and possibly organic solvents. More recent developments used higher energy radiation (X-rays) for enhanced resolution or UV/Excimer lasers.
  • the scattering provides a mirroring/reflecting effect providing a confinement of the radiation at the volume/interface.
  • This may be used for providing a number of types of products and effects. Also, naturally, it may be used for providing, from the same basic product, different versions of the product in that the radiation may be provided to a larger or smaller area/volume, to different areas/vol umes, may be provided or not, whereby the effects, cuts, releases, weldings, debondings or the like (any of the above processes) may be provided in some versions and not in others. This is known in normal production.
  • the step of providing the PE element comprises providing the PE element with a predetermined substance at the interface and/or in the predetermined volume and wherein the step of providing the radiation comprises the su bstance absorbing radiation at the predetermined wavelength and converting the radiation to heat in the PE element.
  • a further step may be provided of providing a second element adjacent to and abutting the interface, the second element having an absorption coefficient ⁇ a2 and a scattering coefficient ⁇ s2 at the predetermined wavelength.
  • the interface is an external surface of the PE element.
  • a first such application is one wherein the step of providing the second element comprises providing a second element with ⁇ a2 ⁇ a and wherein the step of providing the radiation comprises providing the radiation to the predetermined volume through the second element. In this manner, the radiation is provided though the second element and to the volume or interface in order to provide the effect desired. This providing of the radiation through the second element is desirable due to the lower absorption coefficient therein.
  • An alternative to the first application is one wherein the step of providing the second element comprises providing a second element with ⁇ s2> (l/10)* ⁇ a and wherein the step of providing the radiation comprises providing the radiation to the predetermined volume along a plane of the interface.
  • a third application is one wherein the step of providing the radiation comprises melting the PE element in the predetermined volume so as to weld the PE element and the second element to each other. Thus, subsequently, the two abutted elements wi ll be welded together.
  • the interface/external surface of the PE element and the second element may have any shape.
  • the interface between the two elements may have any three-dimensional shape, and the weld may be provided anywhere desired in or at that three-di ensional shape.
  • a fourth application further comprises the step of providing a heat activatable adhesive (glue) at the interface between the PE element and the second element, and wherein the step of providing the radiation comprises heating the adhesive so as to attach the PE element to the second element.
  • a heat activatable adhesive glue
  • the step of providing the radiation comprises heating the adhesive so as to attach the PE element to the second element.
  • a fifth application is one wherein the step of providing the second element comprises providing the second element attached to the PE element (at the interface), and wherein the step of providing the radiation comprises heating the predetermined volume so as to melt material in the predetermined volume and at the interface in order to facilitate detachment of the PE element from the second element.
  • the step of providi ng the radiation comprises evaporating and removing part of the PE element.
  • the PE element may be shaped by ablation/cutting due to the heating of the material. This heating may bring the material of the PE element to fluid or gas form and thereby facilitate removal of the heated material.
  • the scattering may be used for delimiting the material to be removed in that it prevents absorption further into the material. This deli miting may be in three dimensions defining volumes to be removed.
  • the step of providing the PE element comprises providing the PE element with a substance in the predetermined area and/or on the interface thereof, the substance being adapted to perform an endothermic reaction during the step of providing the radiation.
  • This may be any endothermic reaction which may be desired on the surface of the PE element, inside or outside a wall/container holding the PE element or of which the PE element forms a part, or in the bulk of the PE element or a product of which the PE element forms a part.
  • the step of providing the PE element comprises providing the PE element with a substance in the predetermined area and/or on the interface thereof, and wherein the step of providing the radiation comprises the substance absorbing the radiation at the predetermined wavelength and cha nging a colour (such as the absorption/reflection at visible wavelength(s)) thereof.
  • the substance(s) may be a substance added to the PE element for this purpose or may be a substance normally forming part of the PE element for another purpose (colour, mechanical properties etc).
  • the step of providing the radiation comprises the PE element absorbing radiation and changing a surface characteristic thereof at the interface.
  • this surface characteristic may be used for controlling e.g. adhesive properties and a large number of other parameters of the material.
  • the use of radiation for providing these properties renders it possible to actually provide these properties at predetermined areas of the PE element — in a pattern, randomly or any manner desired.
  • An interesting a plication is one wherein the step of providing the radiation comprises a polymer of the PE element absorbing the radiation at the predetermined wavelength and changing a characteristic thereof.
  • Items 11 and 13 above describe a number of characteristics of polymers which are controllable using radiation. Any known altering of a characteristic of a polymer (using radiation) is possible also using the PE element of the invention.
  • the PE element is a homogeneous material having at least substantially the same ⁇ a and ⁇ s throughout the PE element.
  • the material of the PE element may be provided in bulk and subsequently shaped.
  • the step of providing the PE element comprises providing a PE element comprising an upper layer having the absorption coefficient ⁇ a and a lower l ayer having the scattering coefficient, ⁇ s.
  • the lower layer has an absorption coefficient lower than that of the upper layer
  • the upper layer may have a scattering coefficient which is lower than or higher than ⁇ s.
  • these layers may have any thickness and shape.
  • the layers may be attached to each other or be detachable or unattached and be freely movable in relation to each other.
  • the upper layer may comprise or constitute any element or material which may be altered by radiation.
  • This layer may be a thin sheet changing colour, a layer of adhesive, a layer of a radiation activated substance, a th icker layer of a material having in its bulk a radiation activatable substance, or the like. In fact, most or all of the above processes may be supported by this set-up.
  • One embodiment where the unattached assembly is interesting is one where the lower part is reusable for a number of upper pa rts.
  • an upper part is positioned on the lower part and the radiation is provided in order to provide the desired radiation induced effect.
  • the lower part provides the reflection of radiation transmitted through the upper part.
  • the u pper part may be removed and another one provided and subsequently processed.
  • the step of provid ing the PE element comprises providing the PE element with the upper layer comprising a substance adapted to convert absorbed radiation to heat. This is useful for the above-mentioned welding, remelting, ablation, endothermic reactions, colour changes, alternations of polymers etc.
  • the step of providing the radiation comprises photo activating a substance in the upper part. This may be suitable for activating biological components and parts of the surface changes described above.
  • One manner of providing the reflecting properties of the PE element is to have the step of providing the PE element comprise providing the PE element with a predetermined concentration or percentage of a particulate matter having a mean particle size of e.g . less than 10 times the predetermined wavelength, such as less than the predetermined wavelength, preferably less than h alf the predetermined wavelength.
  • the presence of such particles in itself provides the scattering.
  • the scattering properties may be controlled.
  • the desired penetration depth of the radiation into the PE element depends on the applicatio n. In general, if radiation penetrates the PE element and exits it, this is a waste of energy. In addition, this radiation should be handled as it may be dangerous to e.g. an operator.
  • the penetration depth is no more than e.g. 80%, such as no more then 50% of the thickness of the PE element in the direction of the radiation. If the PE element is divided into an upper, absorbing part and a lower, scattering part, it is desired that radiation does, in fact penetrate the upper part in order for the scattering part to have an effect. Then, however, it is desired that the scattering part has a penetration depth of no more than e.g. 80% of the thickness in the direction of the radiation in order to ensure that (at least substantially) no radiation is lost by transmission or forward scattering.
  • a second aspect of the invention re lates to a radiation welded product comprising a first part and a second part welded together, wherein: the first part has a high transmission at the predetermined wavelength and the second part is a PE element and has an absorption coefficient, ⁇ a, and a scattering coefficient, ⁇ s, at the predetermined wavelength,
  • a high transmission is a relative measure depending on a number of parameters, such as the thickness of the first part. Normally, as high a transmission as possible is desired in order to prevent heating and corresponding effects (such as a resulting deformation, decolouration etc) of the first part. However, some absorption is allowed and accepted in laser welding.
  • a third aspect relates to a radiation welded product comprising a first part and a second part welded together, wherein:
  • the first part has a high transmission at the predetermined wavelength
  • the second part is a PE element and has an absorption coefficient, ⁇ a, at the predetermined wavelength
  • the second part has a scattering coefficient, ⁇ s, at the predetermined wavelength
  • the first part further has a fi rst scattering coefficient , ⁇ sl, at the predetermined wavelength
  • the second part has an upper part adjacent to the first part and a lower part, wherein: the upper part has the absorption coefficient, ⁇ a, and the lower part has a third, respectively, absorption coefficient, ⁇ a3, at the predetermined wavelength ,. the absorption coefficient, ⁇ a, being larger than the first and third absorption coefficients, ⁇ al and ⁇ a3, respectively, and the lower part has the scattering coefficient, ⁇ s, at the predetermined wavelength, the scattering coefficient, ⁇ s, being higher than the first scattering coefficient, ⁇ sl.
  • the second part is actually two parts where the upper part has the primary object of providing the absorption and the lower part provides scattering. In that situation, all the advantages and preferences illustrated further above are valid.
  • the upper part may, as described, be provided as is with the desired absorption or an absorbing substance may be added.
  • - ⁇ s3 is at least 1.5, such as at least 2, preferably at least 4, such as at least 5 times ⁇ sl, ⁇ a is at least 1.5, such as at least 2, preferably at least 4, such as at least 5 times ⁇ al, and/or ⁇ a is at least 1.5, such as at least 2, preferably at least 4, such as at least 5 times ⁇ a3.
  • the u pper part may have a thickness being lower than ⁇ a to the power of minus 1, such as lower than 0.8 times ⁇ a to the power of minus 1, preferably lower than 0.5 times ⁇ a to the power of minus 1. In that situation, it is ensured that radiation is, in fact, transmitted through the upper part in order for the lower part to provide its function.
  • the second part comprises a predetermined concentration of a material having a mean particle size of at the most the predetermined wavelength. All materials scatter radiation, such as due to impurities or imperfections therein. However, in order to both obtain a sufficient and controllable reflection, addition of e.g. a powder is possible.
  • a fourth aspect relates to an ostomy product provided by any of the above-mentioned methods, and a sixth aspect relates to an ostomy roduct comprising any of the above products.
  • FIG. 1 illustrates laser welding of two parts
  • Figure 2 illustrates laser welding of two parts having there between an absorbing layer
  • Figure 3 illustrates peeling strength obtained in laser welding according to a preferred embodiment.
  • Figure 4 illustrates another manner of e.g. welding where the two elements have a high scattering coefficient.
  • Figure 1 illustrates laser transmission welding of a transparent part 20 to an absorbing part 30.
  • Laser light penetrates the upper transparent pa rt 20 and is absorbed in the lower absorbing part 30 at an interface 10 between the two parts 20 and 30.
  • the absorption coefficient of the part 20 is preferably not too high in that this will cause absorption of radiation before reaching the interface where the radiation is desired. However, as long as the absorption of the part 20 does not damage this part, it may very well have both some absorption and scattering of the radiation.
  • Two lines, 11 and 12 are illustrated. These lines describe the penetration depth - or melted volume - of the radiation in two instances.
  • the absorbing part 30 does not scatter laser light to any substantial degree, the light will penetrate to the depth illustrated by line 1_L .
  • the absorbing part 30 also scatters laser light, the light penetration is reduced as illustrated by the line 12. This effect, naturally, is a gradual decrease of the penetration depth with the increase of scattering in the material 30.
  • This effect may be used for decreasing the amount of absorber in the material 30. This may be desired in a number of applications where the colour of the materials 20 and 30 is of importance. It is difficult to find and incorporate absorbers in e.g. polymers, which absorbers have a sufficient absorption in e.g. the infrared region but only minor influence on absorption or reflection (colour) in the visible range.
  • the function of the material 20 is the same, but the main absorption is now provided in the material 30, and two lines, 11 and 12, illustrate the penetration depth (melted volume) of the radiation when the material 40 has a sufficiently high scattering coefficient at the pertaining wavelength - or not.
  • the material or part 40 need not have any absorption coefficient at the wavelength.
  • the parts 30 and 40 may be combined/attached into one part before welding or may form separate parts.
  • Laser light penetrates the transparent part 20 and a part is absorbed in the absorbing part 30. If the lower part 40 does not scatter laser light, the light will penetrate to the depth illustrated by line 11. If the lower part 40 also scatters laser light, the light penetration in 40 is reduced as illustrated by the line 12.
  • the material 30, in figure 2 may be used for attaching the materials 20 and 40 due to the even intensity distribution therein - and therefo re the even temperature distribution which provides a good welding between the material 30 and each of the materials 20 and 40.
  • the material 20 is again the transparent material of the example below and the material 30 is the absorbing and scattering material of the below example with a final Ti02 concentration of 2 wt. %.
  • the fat line in figure 3 illustrates these tests.
  • the material 30 contains an amount of Ti02 with a mean particle size of 300 nm that scatters the radiation.
  • the line energy (radiation intensity per distance - J/mm) was varied in order to see the effect on the intensity on the difference in scattering.
  • the material 30, in the first set of materials is normally decolorized or damaged due to the large intensity absorbed through the material.
  • Transparent piece Low-density polyethylene (LDPE, Engage 8401 from DuPont-Dow) or other types of polyethylene or polyethylene/ethylene-vinyl acetate co-polymers.
  • LDPE Low-density polyethylene
  • Engage 8401 from DuPont-Dow
  • Absorbing piece An amount of infrared absorber (PRO-JET 830 NP from Avecia) corresponding to a total final concentration of 0.02 wt. % was dissolved in a small amount of mineral oil and mixed with Engage 8401.
  • the PRO-JET 830 NP has a maximum absorption at a wavelength of 800 nm with a spectral full-width-half-maximum of ⁇ 110 nm and it can be readily mixed with polyethylene.
  • the absorption coefficient ( ⁇ a ) and scattering coefficient ( ⁇ s ) at 800 nm are ⁇ 0.9 mm "1 and ⁇ 0.3 mm "1 , respectively.
  • Infrared absorbers for laser welding of polymers should be mixable with the polymers and with a concentration resulting in sufficient absorption and scattering at the laser-welding wavelength.
  • Commercial laser diodes for laser welding typically have emission wavelengths in the range from 800 nm to 980 nm.
  • Infrared absorbers with sufficient absorption in this wavelength range can be selected from groups of nitroso, cyanine, nigrosine, triphenylmethane, imminium and diimminium, squauriliurn and croconium, nickel dithiolenes and related compounds, quinone, phtalocyanine, azo, indoaniline, and others. The structural formulas of such compounds can be found e.g.
  • dyes may be modified in order to be mixable with the polymers to be welded or they may be produced in a pigmented form, which subsequently is mixed with the polymers.
  • Methods of mixing dyes with polymers include coprecipitation of the dye with the polymers in a solvent or in high vacuum [see e.g. T. Hiraga et al. "Properties and application of organic dye associates in polymer matrices", Thin Solid Films 273 (1996) 190-194], Alternatively, dye molecules may be covalently linked to the polymeric chains [see e.g. A.
  • Laser welding experiments were performed using a diode laser with a wavelength of 808 nm, a beam diameter of 2 mm and various combinations of power and speed.
  • Figure 3 shows the load at failure as a function of line energy defined as power/speed.
  • the measured data were converted to absorption and scatterin g coefficients using the adding-doubling algorithm assuming isotropic scattering and an index of refraction of 1.5 (S. A. Prahl: "Optical property measurements using the inverse adding-doubling algorithm", Oregon Medical Laser Center, Portland OR, Jan 1999 http://omlc.ogi.edu/software/iad/index.html)
  • the table shows absorption and scattering coefficients measured on a number of different samples with and without absorber (PRO-JET 830 NP) and containing various amounts of Ti02.
  • the effect of the scattering in the material 30/40 of Figs 1 and 2 may, naturally, be used for any of a large number of other purposes where a heating or a higher radiation intensity is desired:
  • a scattering support (ceramics) may be used to reflect/backscatter the light that passed through. In this way the optical path length within the foils are increased and so is the absorption/heating.
  • Marking of the adhesive change of colour an d appearance.
  • Change of surface properties surface energies, hydrophobicity, roughness, optical properties (reflection coefficient)).
  • surface energies, hydrophobicity, roughness, optical properties reflection coefficient
  • One type of application relates to photo-chemistry, photo indu ced cross-linking and curing. This is usually done with UV (Excimer) lasers but sometimes a Iso with heat generated by IR/NIR lasers. If light penetration is reduced this may effectively increase the efficiency of a 3.8
  • Curing (of hot melt a dhesives) is used for bonding of pieces and is an alternative to welding widely used in the medical device industry.
  • circuits can be "printed” by laser writing of conducting polymers. Otherwise an unconducting polymer surface may be rendered conducting by graphitisation (heating) by a laser beam. This also provides a method to produce prints.
  • Electronic ci rcuits may be relevant in connection with e.g. sensor applications for medical devices.
  • Bond breaking is also the crucial process in laser debonding, where e.g. two glued components can be separated (recycling) by laser induced destruction of the glue. If the glue does not have sufficient absorption in it self then adding scatterers may help.
  • Active substances may be immobilised in different kinds of chemical complexes or physically separated from the surface. Using heat it is then possible either to mobilise the substance or allow diffusion towards the surface. This concept provides two features. First, if a laser is used then the dose can be determined by the area heated, this is an easy way to produce products with many dose levels. Second, for use in hospitals or otherwise the active substance may be activated just prior to applicati on of e.g. a plaster.
  • Photo activation of an active component (photo chemistry, substance is not immobilized but plainly inactive before irradiation) follows along the same lines. Backscattering
  • Backscattering of the light may be obtained from a highly scattering part of the material placed at a certain depth from the surface.
  • the buried interface acts like a mirror.
  • This configuration is useful for welding as described above. It can also be used e.g. for drilling/cutting/ablation purposes (IR/NIR/VIS and UV lasers) where the 'mirror-interface' effectively determines the depth of the hole drilled or the cut made.
  • IR/NIR/VIS and UV lasers IR/NIR/VIS and UV lasers
  • the scattering and absorption coefficients may be chosen in a way that the highest temperatures are actually achieved at the buried "mirror interface" and not at the surface. This may be useful for activation of active substances and laser debonding (se above).
  • the metal layer may be replaced by a scattering layer (which is cheaper and easier to apply).
  • a particular embodiment is one where radiation is desired in a thin layer or at an interface.
  • two reflecting members may be positioned adjacent to the interface, as is illustrated in Figure 4.
  • the two scattering elements 40 are positioned on either side of the absorbing element 30.
  • the elements 40 have a scattering coefficient which is so high that it is not desired to launch the required amount of radiation there through in order to have the desired intensity at the element 30. Therefore, the radiation is provided to the element 30 as illustrated by the arrow.
  • the two scattering elements 40 now act to ma intain a "high" radiation intensity at the element 30 also a given distance away from the interface at which the radiation enters the system in that the scattering of the radiation will tend to keep a relatively high radiation intensity at the material 30.
  • This type of system may be used for most of the aspects mentioned above, such as for welding, debonding, changing properties of the material 30, the bulk thereof or the surface thereof, sustained release of agents therein, changes of a polymer of the material 30 or the like.

Abstract

A method of decreasing the penetration depth of radiation provided to an interface, such as a surface, or a predetermined volume in a polyethylene element, where the PE element has a scattering coefficient larger than one tenth of an absorption coefficient thereof so that the radiation not absorbed at the interface or in the volume but transmitted further into the PE element is at least partly reflected toward the interface/volume. The radiation intensity is higher in the volume and the absorption coefficient may be reduced while retaining the total absorption in the volume. This may be used for all known techniques where radiation is desired absorbed, such as in welding, surface preparation, polymer chemistry, the activation of photo activatable substances etc.

Description

A POLYETHYLENE PRODUCT AND A METHOD OF PROVIDING A PRODUCT, SUCH AS A LASER WELDED POLYETHYLENE PRODUCT
The present invention relates, in general, to the use of radiation for initiating or providing an effect and in particular to a manner and a polyethylene element which facilitates the concentration of a radiation intensity to a predetermined volume or at an interface or surface.
Normally, if absorption is desired in a material or an element in order to generate heat or other changes, an absorber is added to facilitate the absorption. However, absorbers have a tendency, in addition to their main function of absorption, to change other physical or chemical parameters of the material in a non-desired manner. One such parameter may be the colour of the means or material, and another may be the mechanical strength, which may both be adversely affected by the presence of the absorber. Also, the normally used absorbers can be relatively costly.
In order to reduce these "side effects", less absorber may be used. This may, however, reduce the overall absorption to a level where the desired effect is not seen.
The use of radiation for performing or triggering different processes may e.g. be seen in: GB 1528452, US 5 702 771, US 6 326 450, US 6 492 019, US 6 248 974, US 6 229 114, WO 02/23962, EP 1331635, EP 0476865, EP 0126787, WO 00/20157, WO 03/007080, and DE 101 58 016 as well as in Russek U A et al: "laser beam welding of thermoplastics, Proc. SPIE - the international society for optical engineering: photon processing in microelectronics and photonics II: San jose, CA, USA, Jan 27-30 2003, vol. 4977, 2003, pages 458-472,
Bachmann F G: "laser welding of polymers using high-power diode lasers", Proc of SPIE, vol. 4637, 2002, p: 505-518, and "laserstrahlschweissen von Thermoplasten in Durchstrahl- verfahren" 1 February 2000, BASF AG, AWETA THERMOPLASTE, Ludwigshafen, DE.
One particular application is laser welding, where radiation is transmitted to an interface between two abutting materials having different absorption of the radiation used. The radiation is transmitted through the material having the lower absorption of the radiation so that, due to its higher absorption of the radiation, the other material is heated at the interface to a degree where melting and welding occurs.
It has been found, however, that problems may occur in laser welding due to the relation between the absorption required to obtain the heating and the effects of the radiation in areas away from the interface. In fact, weakening or decolouration of the material may be the result of the welding due to radiation not absorbed close to the interface heating the material further into the highly absorbing material. Thus, a number of situations exist where the absorption desired/obtainable is not sufficient to obtain the desired effect (such as heat, damping of the radiation or the like) at/in the interface/volume desired and especially for soft thermoplastic materials such as polyethylene (PE), low density polyethylene (LDPE), high density polyethylene (HDPE) and the like.
In a number of other applications, where a photo- or heat-induced process is desired, the same problem may occur. Radiation not absorbed at the desired positions may damage materials at other positions.
The present invention relates to a solution to this problem in that it has been found that if a means or a material in addition to showing absorption at the wavelength in question also shows a not insignificant scattering, radiation transmitted away from the area/surface/- interface where the effect of the radiation is desired is not merely absorbed in other parts of the material (or output there from), but part of the transmitted radiation is scattered back toward the area/surface/interface in question. Consequently, a higher radiation intensity and a higher radiation absorption are experienced at that area/surface/interface.
The overall effect of the scattering is a limitation or reduction in the penetration depth or distance of the radiation into the means. The scattering will act to scatter the radiation also back toward the volume where the radiation is desired. Naturally, as will also be seen below, the scattering may be selected (also inside the means) in order to provide the reflection at the desired positions in order to actually tai lor the means to the application in question.
In a first aspect, the invention relates to a method of providing a product, the method comprising: providing a PE element having an absorption coefficient, μa, and a scattering coefficient, μs, at a predetermined wavelength, wherein μs> (l/10)*μa, providing radiation comprising radiation at the predetermined wavelength to a predetermined volume at or near an interface or surface of the PE element.
In the present context, the radiation may be monochromatic radiation, such as laser radiation, having the predetermined wavelength, or it may be polychromatic radiation. There need be no direct demands as to the radiation source. The wavelength may be any wavelength. In fact, radiation may be used having a plurality of wavelengths in that most materials have absorptions at multiple wavelengths, so that the overall radiation intensity, heating, or other effect, may be obtained a lso using multiple wavelengths. An interface may be an external surface of the PE element or may be an internal interface, such as between two parts of the PE element. The predetermined volume receiving the radiation is present at the interface where the radiation is desired. The predetermined volume will be at the interface but may just as well be at an outer surface of the PE element as inside it. The volume is normally defined by the radiation a nd the intensity thereof as a volume where the desired effect takes place, such as where the radiation intensity is large enough. However, a number of other manners exist of defining this volume. The effect desired will then take place at the volume/interface. Depending on the situation (see below), the effect may be a surface-related effect or a bulk-related effect.
Naturally, the absorption coefficient, μa, and the scattering coefficient, μs, are two of the fundamental optical properties describing radiative transport in any medium. They are defined in standard textbooks such as C. F. Bohren and D. R. Huffman/ Absorption and Scattering of Light by Small Particle', John Wiley 8. Sons, Inc. 1983, ISBN 0-471-05772-X. The absorption and scattering coefficients can be measured experimentally e.g. using the so- called integrating sphere method described e.g. by B. C. Wilson in Optical-Thermal
Response of Laser-Irradiated Tissue1, ed. A. J. Welch and M. J. C. van Gemert, Plenum Press NY 1995 chapter 8.
For an (optically) thin homogenous material of thickness d the absorption coefficient is determined by measuring all the light intensity transmitted or scattered by the material, so that the only loss is due to absorption. In this case the absorption coefficient is given by light intensity and I the measured light intensity.
Figure imgf000004_0001
The scattering coefficient is similarly given by μs = l I.n r 1_ — I '-Λ where Is is the intensity of d scattered light. The overall effect of the scattering of the PE element is that at least part of the radiation is absorbed in the predetermined volume, whereas another part of the radiation is transmitted further into the PE element (away from the volume). Part of this radiation transmitted further into the PE element is then scattered in a direction toward the predetermined volume. Naturally, this increases the intensity at the predetermined volume and at the interface.
This means that having this intensity increasing feature can be used in almost any process where e.g. laser irradiance is used, such as in:
1. Laser welding. 2. Laser welding of foils with little absorption where a third medium in the form of a scattering plate is placed beneath the foils to be welded.
3. Changing a surface property including: adhesion (tack, peel), absorption capacity of fluids (water), permeability for gases or fluids (porosity), cohesion, colour, appearance, odour, hydrophobicity, surface energy (contact angle), surface roughness, mechanical properties (elasticity, hardness, shear resistance, strength), friction coefficient, heat resistance, electrical conductivity, sound propagation (damping), optical properties, crystallinity, molecular orientation, molecular structure (cross linking, curing) etc.
4. Traditional laser marking.
5. Laser cutting and drilling, see e.g. US6248974 disclosing a method where an aerodynamic pattern is imparted to a golf ball by laser removal of excess material and US6229114 disclosing a process for precision patterning of an adhesive and cutting to a controlled depth.
6. Initiating any endothermic chemical reaction (at the surface or within the bulk).
7. Controlled release of initially bonded active substances into a transporting medium (e.g. adhesive). In this way the dose may be varied by means of laser radiation.
8. Photo activation of a biological component.
9. Laser debonding of glued/welded/bonded components (e.g. recycling of automotive parts).
10. Laser remelting to change mechanical properties or crystallinity somewhere in a surface region or within the bulk.
11. Laser patterning of polymers. One such method is seen in WO 02/23962 which discloses a method of forming a pattern on an insulating substrate made of organic polymer using a laser to irradiate and modify selected areas of the polymer. The application specifically describes that carbonisation and/or graphitisation of the polymer may make the polymer conductive, hence the method can be used to manufacture print boards (PCBs).
12. Optical recording media such as a CD-R or a DVD-R usually are multi layer structures comprising a (laser) transparent substrate, a recording layer, an interlayer (metallic), a pressure sensitive adhesive layer and a cover film. The recording layer typically contains an organic dye capable of absorbing light at the laser wavelength. Information is recorded on the media using a laser to locally heat the recording layer causing a physical or chemical change that alters the optical properties of the layer (a pattern is formed). Irradiating the media with a laser of the sa me wavelength used to write the information and measuring the specular reflectivity reproduces the information. These procedures are described in numerous patents, e.g. EP1331635.
13. UV-light induced processes such as cross-li nking or photochemistry.
14. Laser surface treatment of polymers with the aim of modifying the surface properties such as Chemical modification, Structural modification, Surface roughening and/or reducing hydrophobicity. Surface roughening of a substrate is the major reason for the improved sticking of adhesives to a laser treated polymer surface. In addition, there is a large literature describing treatment of polymer pieces with electromagnetic radiation more generally before joining with an adhesive. This is usually referred to as a surface preparation technique and allows the bond strength of the joint to be varied.
15. Light activation of an adhesive by heat or electromagnetic radiation. One example is UV curing of acrylic adhesives, where the polymerisation is initiated by UV light. Another example is hot melt bonding, where heat is used to melt an adhesive (e.g. a thermoplastic) producing a low viscosity fluid that wets the surfaces of the pieces to be bonded.
16. Traditional optical lithography as used in the semiconductor industry where a UV-light source illuminates a substrate covered by photo resist through a mask defining a pattern. The exposure to UV-light changes the solubility of the resists in the developer allowing development of the pattern. A typical photo resist comprises a photosensitive material combined with a polymer and possibly organic solvents. More recent developments used higher energy radiation (X-rays) for enhanced resolution or UV/Excimer lasers.
Thus, it may be used for defining an area, a maximum depth, an intensity, or the like in or at which a predetermined effect takes place. The scattering provides a mirroring/reflecting effect providing a confinement of the radiation at the volume/interface.
This may be used for providing a number of types of products and effects. Also, naturally, it may be used for providing, from the same basic product, different versions of the product in that the radiation may be provided to a larger or smaller area/volume, to different areas/vol umes, may be provided or not, whereby the effects, cuts, releases, weldings, debondings or the like (any of the above processes) may be provided in some versions and not in others. This is known in normal production.
In a preferred embodiment, the step of providing the PE element comprises providing the PE element with a predetermined substance at the interface and/or in the predetermined volume and wherein the step of providing the radiation comprises the su bstance absorbing radiation at the predetermined wavelength and converting the radiation to heat in the PE element.
In this embodiment, a further step may be provided of providing a second element adjacent to and abutting the interface, the second element having an absorption coefficient μa2 and a scattering coefficient μs2 at the predetermined wavelength. In this situation, the interface is an external surface of the PE element. This setup is basic and common to a number of specific a pplications.
A first such application is one wherein the step of providing the second element comprises providing a second element with μa2<μa and wherein the step of providing the radiation comprises providing the radiation to the predetermined volume through the second element. In this manner, the radiation is provided though the second element and to the volume or interface in order to provide the effect desired. This providing of the radiation through the second element is desirable due to the lower absorption coefficient therein. An alternative to the first application is one wherein the step of providing the second element comprises providing a second element with μs2> (l/10)*μa and wherein the step of providing the radiation comprises providing the radiation to the predetermined volume along a plane of the interface. Thus, a relatively high scattering makes it less desirable to launch the radiation through the second element due to the radiation loss or attenuation in the second element. The same would be the case for the PE element. Thus, the radiation is transported to the volume/interface along a plane of the external surface of the PE element and thereby not through the bulk of any of the PE element and the second element. A third application is one wherein the step of providing the radiation comprises melting the PE element in the predetermined volume so as to weld the PE element and the second element to each other. Thus, subsequently, the two abutted elements wi ll be welded together.
It is clear that the interface/external surface of the PE element and the second element may have any shape. I n particular in the third application, the interface between the two elements may have any three-dimensional shape, and the weld may be provided anywhere desired in or at that three-di ensional shape.
A fourth application further comprises the step of providing a heat activatable adhesive (glue) at the interface between the PE element and the second element, and wherein the step of providing the radiation comprises heating the adhesive so as to attach the PE element to the second element. Thus, instead of welding (third application), an adhesive may be used for attaching the two elements to each other.
A fifth application is one wherein the step of providing the second element comprises providing the second element attached to the PE element (at the interface), and wherein the step of providing the radiation comprises heating the predetermined volume so as to melt material in the predetermined volume and at the interface in order to facilitate detachment of the PE element from the second element.
In addition, a number of more general applications exist, one being an application wherein the step of providi ng the radiation comprises evaporating and removing part of the PE element. In this manner, the PE element may be shaped by ablation/cutting due to the heating of the material. This heating may bring the material of the PE element to fluid or gas form and thereby facilitate removal of the heated material. In fact, the scattering may be used for delimiting the material to be removed in that it prevents absorption further into the material. This deli miting may be in three dimensions defining volumes to be removed.
Another general a pplication is one wherein the step of providing the PE element comprises providing the PE element with a substance in the predetermined area and/or on the interface thereof, the substance being adapted to perform an endothermic reaction during the step of providing the radiation. This may be any endothermic reaction which may be desired on the surface of the PE element, inside or outside a wall/container holding the PE element or of which the PE element forms a part, or in the bulk of the PE element or a product of which the PE element forms a part. Yet another general application is one wherein the step of providing the PE element comprises providing the PE element with a substance in the predetermined area and/or on the interface thereof, and wherein the step of providing the radiation comprises the substance absorbing the radiation at the predetermined wavelength and cha nging a colour (such as the absorption/reflection at visible wavelength(s)) thereof.
Again, the substance(s) may be a substance added to the PE element for this purpose or may be a substance normally forming part of the PE element for another purpose (colour, mechanical properties etc).
Another general application also mentioned above is one wherein the step of providing the radiation comprises the PE element absorbing radiation and changing a surface characteristic thereof at the interface. As mentioned above (items 3 and 14), this surface characteristic may be used for controlling e.g. adhesive properties and a large number of other parameters of the material. The use of radiation for providing these properties renders it possible to actually provide these properties at predetermined areas of the PE element — in a pattern, randomly or any manner desired.
An interesting a plication is one wherein the step of providing the radiation comprises a polymer of the PE element absorbing the radiation at the predetermined wavelength and changing a characteristic thereof. Items 11 and 13 above describe a number of characteristics of polymers which are controllable using radiation. Any known altering of a characteristic of a polymer (using radiation) is possible also using the PE element of the invention.
In one embodiment, the PE element is a homogeneous material having at least substantially the same μa and μs throughout the PE element. Thus, there are no great variations in the absorption and scattering of the PE element, and these properties are experienced at all parts thereof. This makes manufacture easy in that the material of the PE element may be provided in bulk and subsequently shaped.
An alternative to that embodiment is one wherein the step of providing the PE element comprises providing a PE element comprising an upper layer having the absorption coefficient μa and a lower l ayer having the scattering coefficient, μs. Preferably, the lower layer has an absorption coefficient lower than that of the upper layer, and the upper layer may have a scattering coefficient which is lower than or higher than μs. In this manner, the different characteristics may be separated in the two layers. It should be noted that these layers may have any thickness and shape. The layers may be attached to each other or be detachable or unattached and be freely movable in relation to each other.
The upper layer may comprise or constitute any element or material which may be altered by radiation. This layer may be a thin sheet changing colour, a layer of adhesive, a layer of a radiation activated substance, a th icker layer of a material having in its bulk a radiation activatable substance, or the like. In fact, most or all of the above processes may be supported by this set-up.
One embodiment where the unattached assembly is interesting is one where the lower part is reusable for a number of upper pa rts. Thus, an upper part is positioned on the lower part and the radiation is provided in order to provide the desired radiation induced effect. The lower part provides the reflection of radiation transmitted through the upper part. When the radiation has been provided, the u pper part may be removed and another one provided and subsequently processed.
In one instance, the step of provid ing the PE element comprises providing the PE element with the upper layer comprising a substance adapted to convert absorbed radiation to heat. This is useful for the above-mentioned welding, remelting, ablation, endothermic reactions, colour changes, alternations of polymers etc.
In another instance, the step of providing the radiation comprises photo activating a substance in the upper part. This may be suitable for activating biological components and parts of the surface changes described above.
One manner of providing the reflecting properties of the PE element is to have the step of providing the PE element comprise providing the PE element with a predetermined concentration or percentage of a particulate matter having a mean particle size of e.g . less than 10 times the predetermined wavelength, such as less than the predetermined wavelength, preferably less than h alf the predetermined wavelength. The presence of such particles in itself provides the scattering. Merely by controlling the particle size the scattering properties may be controlled. The desired penetration depth of the radiation into the PE element depends on the applicatio n. In general, if radiation penetrates the PE element and exits it, this is a waste of energy. In addition, this radiation should be handled as it may be dangerous to e.g. an operator. If the PE element is homogeneous, it is desired that the penetration depth is no more than e.g. 80%, such as no more then 50% of the thickness of the PE element in the direction of the radiation. If the PE element is divided into an upper, absorbing part and a lower, scattering part, it is desired that radiation does, in fact penetrate the upper part in order for the scattering part to have an effect. Then, however, it is desired that the scattering part has a penetration depth of no more than e.g. 80% of the thickness in the direction of the radiation in order to ensure that (at least substantially) no radiation is lost by transmission or forward scattering.
A second aspect of the invention re lates to a radiation welded product comprising a first part and a second part welded together, wherein: the first part has a high transmission at the predetermined wavelength and the second part is a PE element and has an absorption coefficient, μa, and a scattering coefficient, μs, at the predetermined wavelength,
wherein μs>(l/10)*μa.
Thus, as is mentioned above, this combination of absorption and scattering has many advantages in e.g. welding.
Presently, a high transmission is a relative measure depending on a number of parameters, such as the thickness of the first part. Normally, as high a transmission as possible is desired in order to prevent heating and corresponding effects (such as a resulting deformation, decolouration etc) of the first part. However, some absorption is allowed and accepted in laser welding.
A third aspect relates to a radiation welded product comprising a first part and a second part welded together, wherein:
- the first part has a high transmission at the predetermined wavelength, the second part is a PE element and has an absorption coefficient, μa, at the predetermined wavelength, and the second part has a scattering coefficient, μs, at the predetermined wavelength,
wherein μs>0.4 mm"1 and μa<4 m m"1.
Naturally, the larger the scattering of the second part the better an energy concentration at the interface between the first and second parts. In that situation, the absorption coefficient in the second part may be lower while still obtaining the desired energy absorption due to the reflecting properties. In fact, μs>l mm"1 and μa<l mm"1 may be desired in a number of situations.
In any of the second and third aspects, preferably: the first part further has a fi rst scattering coefficient , μsl, at the predetermined wavelength, and - the second part has an upper part adjacent to the first part and a lower part, wherein: the upper part has the absorption coefficient, μa, and the lower part has a third, respectively, absorption coefficient, μa3, at the predetermined wavelength ,. the absorption coefficient, μa, being larger than the first and third absorption coefficients, μal and μa3, respectively, and the lower part has the scattering coefficient, μs, at the predetermined wavelength, the scattering coefficient, μs, being higher than the first scattering coefficient, μsl.
In this manner, the second part is actually two parts where the upper part has the primary object of providing the absorption and the lower part provides scattering. In that situation, all the advantages and preferences illustrated further above are valid.
A large number of manners exist of providing a two-part PE element of this type, such as two-component moulding, injection moulding, the painting of the upper layer/part on the lower part, the providing of the upper layer/part as a foil or sheet on the lower part and possibly fixing the two parts to each other (such as by laser welding simply heating the upper layer until it melts, the lower layer reflecting as described).
The upper part may, as described, be provided as is with the desired absorption or an absorbing substance may be added.
Preferably:
- μs3 is at least 1.5, such as at least 2, preferably at least 4, such as at least 5 times μsl, μa is at least 1.5, such as at least 2, preferably at least 4, such as at least 5 times μal, and/or μa is at least 1.5, such as at least 2, preferably at least 4, such as at least 5 times μa3.
Also, in each of the second and third aspects, the u pper part may have a thickness being lower than μa to the power of minus 1, such as lower than 0.8 times μa to the power of minus 1, preferably lower than 0.5 times μa to the power of minus 1. In that situation, it is ensured that radiation is, in fact, transmitted through the upper part in order for the lower part to provide its function.
In one embodiment, the second part comprises a predetermined concentration of a material having a mean particle size of at the most the predetermined wavelength. All materials scatter radiation, such as due to impurities or imperfections therein. However, in order to both obtain a sufficient and controllable reflection, addition of e.g. a powder is possible.
A fourth aspect relates to an ostomy product provided by any of the above-mentioned methods, and a sixth aspect relates to an ostomy roduct comprising any of the above products.
A number of demands are put to ostomy devices both to colour, prize, durability, adhesive properties, etc. The above products and methods a re very well suited for use in ostomy products.
In the following, preferred embodiments of the invention will be described with reference to the drawing, wherein:
Figure 1 illustrates laser welding of two parts,
Figure 2 illustrates laser welding of two parts having there between an absorbing layer,
Figure 3 illustrates peeling strength obtained in laser welding according to a preferred embodiment.
Figure 4 illustrates another manner of e.g. welding where the two elements have a high scattering coefficient.
Figure 1 illustrates laser transmission welding of a transparent part 20 to an absorbing part 30. Laser light penetrates the upper transparent pa rt 20 and is absorbed in the lower absorbing part 30 at an interface 10 between the two parts 20 and 30. The absorption coefficient of the part 20 is preferably not too high in that this will cause absorption of radiation before reaching the interface where the radiation is desired. However, as long as the absorption of the part 20 does not damage this part, it may very well have both some absorption and scattering of the radiation.
Two lines, 11 and 12 are illustrated. These lines describe the penetration depth - or melted volume - of the radiation in two instances.
If the absorbing part 30 does not scatter laser light to any substantial degree, the light will penetrate to the depth illustrated by line 1_L .
If the absorbing part 30 also scatters laser light, the light penetration is reduced as illustrated by the line 12. This effect, naturally, is a gradual decrease of the penetration depth with the increase of scattering in the material 30.
The same total amount of energy is absorbed in the two cases implying that more energy is absorbed close to the interface 10 and hence a higher interface temperature is reached when scattering of laser light takes place in the material 30.
This effect may be used for decreasing the amount of absorber in the material 30. This may be desired in a number of applications where the colour of the materials 20 and 30 is of importance. It is difficult to find and incorporate absorbers in e.g. polymers, which absorbers have a sufficient absorption in e.g. the infrared region but only minor influence on absorption or reflection (colour) in the visible range.
In figure 1, the absorption and the scattering are both performed in the material 30 which may be homogeneous. These effects may, however, be separated. This is illustrated in figure 2, which illustrates laser transmission weldi ng of three parts 20, 30 and 40.
In this situation, the function of the material 20 is the same, but the main absorption is now provided in the material 30, and two lines, 11 and 12, illustrate the penetration depth (melted volume) of the radiation when the material 40 has a sufficiently high scattering coefficient at the pertaining wavelength - or not. The material or part 40 need not have any absorption coefficient at the wavelength.
The parts 30 and 40 may be combined/attached into one part before welding or may form separate parts. Laser light penetrates the transparent part 20 and a part is absorbed in the absorbing part 30. If the lower part 40 does not scatter laser light, the light will penetrate to the depth illustrated by line 11. If the lower part 40 also scatters laser light, the light penetration in 40 is reduced as illustrated by the line 12.
The same total amount of energy is absorbed in the two cases implying that more energy is absorbed in 30 and hence a higher interface temperature is reached at the interfaces 10, 50 when scattering of laser light takes place in 40.
It is seen that the material 30, in figure 2, may be used for attaching the materials 20 and 40 due to the even intensity distribution therein - and therefo re the even temperature distribution which provides a good welding between the material 30 and each of the materials 20 and 40.
A test has been made with a set-up as seen in Figure 1, and where the tensile strength of the weldings is tested.
Two types of materials are tested, where a first set of tests was made with a material 20 being the transparent material of the example below and the material 30 being the absorbing material of the below example. The thin line in Figure 3 illustrates these tests.
In the second set of materials, the material 20 is again the transparent material of the example below and the material 30 is the absorbing and scattering material of the below example with a final Ti02 concentration of 2 wt. %. The fat line in figure 3 illustrates these tests. Thus, compared to the first set of materials, the material 30 contains an amount of Ti02 with a mean particle size of 300 nm that scatters the radiation.
The line energy (radiation intensity per distance - J/mm) was varied in order to see the effect on the intensity on the difference in scattering.
The results of Figure 3 are quite clear in that it is seen that strong weldings are obtained at lower line energies when the material 30 comprises a higher scattering coefficient. This indicates that the scattering increases the radiation intensity at the interface so as to improve the weldings at lower energies.
At higher energies, it is seen by visual inspection of the samples that weldings with the first set of materials break due to breaking of the materials, where the weldings with the second set of materials peel, which indicates that the welds are th weak part and may have been made with a too high temperature. Also, at high line energies, the material 30, in the first set of materials, is normally decolorized or damaged due to the large intensity absorbed through the material.
EXAMPLE
Three types of work pieces (49 X 49 X 1 mmΛ3) were made by injection moulding. Transparent piece: Low-density polyethylene (LDPE, Engage 8401 from DuPont-Dow) or other types of polyethylene or polyethylene/ethylene-vinyl acetate co-polymers.
Absorbing piece: An amount of infrared absorber (PRO-JET 830 NP from Avecia) corresponding to a total final concentration of 0.02 wt. % was dissolved in a small amount of mineral oil and mixed with Engage 8401.
The PRO-JET 830 NP has a maximum absorption at a wavelength of 800 nm with a spectral full-width-half-maximum of ~110 nm and it can be readily mixed with polyethylene. At a concentration of 0.02 wt. % in polyethylene, the absorption coefficient ( μa ) and scattering coefficient ( μs ) at 800 nm are ~0.9 mm"1 and ~0.3 mm"1 , respectively.
Infrared absorbers for laser welding of polymers should be mixable with the polymers and with a concentration resulting in sufficient absorption and scattering at the laser-welding wavelength. Commercial laser diodes for laser welding typically have emission wavelengths in the range from 800 nm to 980 nm. Infrared absorbers with sufficient absorption in this wavelength range can be selected from groups of nitroso, cyanine, nigrosine, triphenylmethane, imminium and diimminium, squauriliurn and croconium, nickel dithiolenes and related compounds, quinone, phtalocyanine, azo, indoaniline, and others. The structural formulas of such compounds can be found e.g. in Infrared Absorbing Dyes" (Topics in applied chemistry), ed. M. Matsuoka, Plenum Press, New York, 1990. Such dyes may be modified in order to be mixable with the polymers to be welded or they may be produced in a pigmented form, which subsequently is mixed with the polymers. Methods of mixing dyes with polymers include coprecipitation of the dye with the polymers in a solvent or in high vacuum [see e.g. T. Hiraga et al. "Properties and application of organic dye associates in polymer matrices", Thin Solid Films 273 (1996) 190-194], Alternatively, dye molecules may be covalently linked to the polymeric chains [see e.g. A. Costela et al. "Efficient and highly photostable solid-state dye lasers based on modified dipyrromethene.BF2 complexes incorporated into solid matrices of poly (methyl methacrylate), Appl. Phys. B 76 (2003) 363-369]. Absorbing and scattering piece: A master batch containing 10 wt. % Pigment White 6 (untreated rutile Ti02 with a mean crystallite size of 300 nm such as PRETIOX R-200 M from PRECOLOR a.s.) in Engage 8401 was made by compounding. Various amounts of master batch were mixed with Engage 8401 and an amount of PROJE 830 NP dissolved in mineral oil corresponding to a total final concentration of 0.02 wt. %.
Laser welding experiments were performed using a diode laser with a wavelength of 808 nm, a beam diameter of 2 mm and various combinations of power and speed.
Tensile testing was performed on welded pieces. Figure 3 shows the load at failure as a function of line energy defined as power/speed.
Measurement of the diffuse reflectance and total transmittance were made using an integrated sphere set-up as described e.g. by B. C. Wilson in 'Optical-Thermal Respons of Laser-Irradiated Tissue', ed. A. J. Welch and M. J. C. van Gemert, Plenum Press NY 1995 chapter 8
The measured data were converted to absorption and scatterin g coefficients using the adding-doubling algorithm assuming isotropic scattering and an index of refraction of 1.5 (S. A. Prahl: "Optical property measurements using the inverse adding-doubling algorithm", Oregon Medical Laser Center, Portland OR, Jan 1999 http://omlc.ogi.edu/software/iad/index.html)
Figure imgf000017_0001
The table shows absorption and scattering coefficients measured on a number of different samples with and without absorber (PRO-JET 830 NP) and containing various amounts of Ti02.
OTHER USES OF THE INVENTION
The effect of the scattering in the material 30/40 of Figs 1 and 2 may, naturally, be used for any of a large number of other purposes where a heating or a higher radiation intensity is desired:
Laser welding:
For welding of partially absorbing foils where light penetrates through all foils, a scattering support (ceramics) may be used to reflect/backscatter the light that passed through. In this way the optical path length within the foils are increased and so is the absorption/heating.
Laser surface modification
In a recently submitted PCT application PCT/EP2005/050328, a number of applications of heat treatment of adhesive surfaces were discussed. All these processes may be mediated by the use of absorbers as described in the application , the use of scattering particles may be used to optimise the process. Laser heat treatment may be used for e.g.
Changing adhesive properties (peel adhesion, tack absorption of water and body fluids).
Marking of the adhesive (change of colour an d appearance). - Change of surface properties (surface energies, hydrophobicity, roughness, optical properties (reflection coefficient)). Very often a surface is heat treated with a laser prior to application of gl e.
Laser induced chemistry
One type of application relates to photo-chemistry, photo indu ced cross-linking and curing. This is usually done with UV (Excimer) lasers but sometimes a Iso with heat generated by IR/NIR lasers. If light penetration is reduced this may effectively increase the efficiency of a 3.8
given light induced process. Curing (of hot melt a dhesives) is used for bonding of pieces and is an alternative to welding widely used in the medical device industry.
Another type of application is bond-breaking and change of molecular orientation and conformation. For conducting polymers it is known that the molecular orientation and the presence of side groups determine the conductivity. One may envisage that circuits can be "printed" by laser writing of conducting polymers. Otherwise an unconducting polymer surface may be rendered conducting by graphitisation (heating) by a laser beam. This also provides a method to produce prints. Electronic ci rcuits may be relevant in connection with e.g. sensor applications for medical devices.
Bond breaking is also the crucial process in laser debonding, where e.g. two glued components can be separated (recycling) by laser induced destruction of the glue. If the glue does not have sufficient absorption in it self then adding scatterers may help.
Laser induced physics
By laser remelting it is possible to change the mechanical properties of foils and polymer surfaces. This may be used e.g. as a substitute to perforation (to induce flexibility in e.g. an adhesive wafer construction where the strength is given by a foil). Another application is to change the crystallinity of a foil/surface region by heating/melting. This could influence the visual appearance or improve the process ability of a following process such as welding (heat, laser or otherwise)
Laser induced activation of active substances
Active substances may be immobilised in different kinds of chemical complexes or physically separated from the surface. Using heat it is then possible either to mobilise the substance or allow diffusion towards the surface. This concept provides two features. First, if a laser is used then the dose can be determined by the area heated, this is an easy way to produce products with many dose levels. Second, for use in hospitals or otherwise the active substance may be activated just prior to applicati on of e.g. a plaster.
Photo activation of an active component (photo chemistry, substance is not immobilized but plainly inactive before irradiation) follows along the same lines. Backscattering
Backscattering of the light may be obtained from a highly scattering part of the material placed at a certain depth from the surface. One may say that the buried interface acts like a mirror.
This configuration is useful for welding as described above. It can also be used e.g. for drilling/cutting/ablation purposes (IR/NIR/VIS and UV lasers) where the 'mirror-interface' effectively determines the depth of the hole drilled or the cut made.
The scattering and absorption coefficients may be chosen in a way that the highest temperatures are actually achieved at the buried "mirror interface" and not at the surface. This may be useful for activation of active substances and laser debonding (se above).
In CD or DVD technology a reflective metallic layer is actually used. According to this invention the metal layer may be replaced by a scattering layer (which is cheaper and easier to apply).
Side illumination
A particular embodiment is one where radiation is desired in a thin layer or at an interface. In this manner, two reflecting members may be positioned adjacent to the interface, as is illustrated in Figure 4. The two scattering elements 40 are positioned on either side of the absorbing element 30.
The elements 40 have a scattering coefficient which is so high that it is not desired to launch the required amount of radiation there through in order to have the desired intensity at the element 30. Therefore, the radiation is provided to the element 30 as illustrated by the arrow.
The two scattering elements 40 now act to ma intain a "high" radiation intensity at the element 30 also a given distance away from the interface at which the radiation enters the system in that the scattering of the radiation will tend to keep a relatively high radiation intensity at the material 30. This type of system may be used for most of the aspects mentioned above, such as for welding, debonding, changing properties of the material 30, the bulk thereof or the surface thereof, sustained release of agents therein, changes of a polymer of the material 30 or the like.

Claims

1. A method of providing a product, the method comprising: providing a PE element having an absorption coefficient, μa, and a scattering coefficient, μs, at a predetermined wavelength, wherein μs>(l/10)*μa,
- providing radiation comprising radiation at the predetermined wavelength to a predetermined volume at or near an interface or surface of the PE element.
2. A method according to claim 1, wherein the step of providing the PE element comprises providing the PE element with a predetermined substance at the interface and/or in the predetermined volume and wherein the step of providing the radiation comprises the substance absorbing radiation at the predetermined wavelength and converting the radiation to heat in the PE element.
3. A method according to claim 2, further comprising the step of providing a second element adjacent to and abutting the interface, the second element having an absorption coefficient μa2 and a scattering coefficient μs2 at the predetermined wavelength.
4. A method according to claim 3, wherein the step of providing the second element comprises providing a second element with μa2<μa and wherein the step of providing the radiation comprises providing the radiation to the predetermined volume through the second element.
5. A method according to claim 3, wherein the step of providing the second element comprises providing a second element with μs2> (l/10)*μa and wherein the step of providing the radiation comprises providing the radiation to the predetermined volume along a plane of the interface.
6. A method according to any of claims 3-5, wherein the step of providing the radiation comprises melting th e PE element in the predetermined volume so as to weld the PE element and the second element to each other.
7. A method according to any of claims 3-5, the method comprising the further step of providing a heat activatable adhesive at the interface between the PE element and the second element, and wherein the step of providing the radiation comprises heating the adhesive so as to attach the PE element to the second element.
8. A method according to any of claims 3-5, wherein the step of providing the second element comprises providing the second element attached to the PE element, and wherein the step of providing the radiation comprises heating the predetermined volume so as to melt material in the predetermined volume and at the interface in order to facilitate detachment of the PE element from the second element.
9. A method according to claim 2, wherein the step of providing the ra iation comprises evaporating and re moving part of the PE element.
10. A method according to claim 2, wherein the step of providing the PE element comprises providing the PE element with a substance in the predetermined area and/or on the interface thereof, the substa nce being adapted to perform an endothermic reaction during the step of providing the radiation.
11. A method according to any of the preceding claims, wherein the step of providing the PE element comprises providing the PE element with a substance in the predetermined area and/or on the interface thereof, and wherein the step of providing the radiation comprises the substance absorbing the radiation at the predetermined wavelength and changing a colour of the substance or PE element.
12. A method according to any of the preceding claims, wherein the step of providing the radiation comprises the PE element absorbing radiation and changing a surface characteristic thereof at the interface.
13. A method according to any of claims 1-12, wherein the step of providing the PE element comprises providing a PE element comprising an upper layer having the absorption coefficient μa and a lower layer having the scattering coefficient, μs.
14. A method according to claim 13, wherein the step of providing the PE element comprises providing the PE element with the upper layer comprising a substance adapted to convert absorbed radiation to heat.
15. A method according to claim 13, wherein the step of providing the radiation comprises photo activating a substance in the upper layer.
16. A method according to any of the preceding claims, wherein the step of providing the PE element comprises providing the PE element with a predetermined concentration or percentage of a particulate matter having a mean particle size of less than 10 times the predetermined wavelength.
17. A radiation welded product comprising a first part and a second part welded together, wherein: the first part has a high transmission at the predetermined wavelength and the second part is a PE element and has an absorption coefficient, μa, and a scattering coefficient, μs, at the predetermined wavelength,
wherein μs>(l/10)*μa.
18. A radiation welded product comprising a first part and a second part welded together, wherein: the first part has a high transmission at the predetermined wavelength, - the second part is a PE element and has an absorption coefficient, μa, at the predetermined wavelength, and the second part has a scattering coefficient, μs, at the predetermined wavelength,
wherein μs>0.4 mm"1 and μa<4 mm"1.
19. A radiation welded product according to any of claims 17 or 18, wherein: the first part further has a first scattering coefficient , μsl, at the predetermined wavelength, and the second part has an upper part adjacent to the first part and a lower part, wherein: - the upper part having the absorption coefficient, μa, and the lower part having a third, respectively, absorption coefficient, μa3, at the predetermined wavelength, the absorption coefficient , μa, being larger than the first and third absorption coefficients, μal and μa3, respectively, and the lower part has the scattering coefficient, μs, at the predetermined wavelength, the scattering coefficient, μs, being higher than the first scattering coefficient, μsl.
20. A product according to any of claims 17-19, wherein the second part comprises a predetermined concentration of a material having a mean particle size of at the most 10 times the predetermined wavelength.
21. An ostomy product provided by the method of any of claims 1-16.
22. An ostomy product comprising the product according to any of claims 17-20.
PCT/DK2005/000251 2004-04-13 2005-04-13 A polyethylene product and a method of providing a product, such as a laser welded polyethylene product WO2005099960A2 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
CN2005800164744A CN1956817B (en) 2004-04-13 2005-04-13 A polyethylene product and a method of providing a product, such as a laser welded polyethylene product
US11/578,367 US8084138B2 (en) 2004-04-13 2005-04-13 Polyethylene product and a method of providing a product, such as a laser welded polyethylene product
EP20050715168 EP1737606B1 (en) 2004-04-13 2005-04-13 A method of providing a laser welded polyethylene product and laser welded polyethylene product
DE200560012937 DE602005012937D1 (en) 2004-04-13 2005-04-13 METHOD FOR PROVIDING A PRODUCT OF A LASER WELDED POLYETHYLENE PRODUCT AND LASER WELDED POLYETHYLENE PRODUCT
DK05715168T DK1737606T3 (en) 2004-04-13 2005-04-13 Process for providing a laser welded polyethylene product and laser welded ethylene product

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US10/822,861 US20050224472A1 (en) 2004-04-13 2004-04-13 Product and a method of providing a product, such as a laser welded product
DKPA200400585 2004-04-13
DKPA200400585 2004-04-13
US10/822,861 2004-04-13

Publications (2)

Publication Number Publication Date
WO2005099960A2 true WO2005099960A2 (en) 2005-10-27
WO2005099960A3 WO2005099960A3 (en) 2005-12-15

Family

ID=34965524

Family Applications (2)

Application Number Title Priority Date Filing Date
PCT/DK2005/000252 WO2005100000A1 (en) 2004-04-13 2005-04-13 A method of providing a laser welded product and a laser welded product
PCT/DK2005/000251 WO2005099960A2 (en) 2004-04-13 2005-04-13 A polyethylene product and a method of providing a product, such as a laser welded polyethylene product

Family Applications Before (1)

Application Number Title Priority Date Filing Date
PCT/DK2005/000252 WO2005100000A1 (en) 2004-04-13 2005-04-13 A method of providing a laser welded product and a laser welded product

Country Status (9)

Country Link
US (2) US8872069B2 (en)
EP (3) EP1737606B1 (en)
CN (2) CN100528540C (en)
AT (2) ATE417727T1 (en)
DE (2) DE602005012937D1 (en)
DK (2) DK1737606T3 (en)
ES (1) ES2319914T3 (en)
PL (1) PL1744870T3 (en)
WO (2) WO2005100000A1 (en)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100301022A1 (en) * 2009-06-01 2010-12-02 Gentex Corporation Method of laser-welding using thermal transfer deposition of a laser-absorbing dye
JP6046329B2 (en) * 2010-01-08 2016-12-14 早川ゴム株式会社 Joining method using laser light
US8968508B2 (en) 2011-01-17 2015-03-03 Nike, Inc. Joining polymeric materials
US9642751B2 (en) 2012-05-16 2017-05-09 Kao Corporation Method for manufacturing fused sheets
CN104755249B (en) * 2012-10-23 2017-08-15 科洛普拉斯特公司 The blown-moulding of ostomy bag
JP6025629B2 (en) 2013-03-21 2016-11-16 本田技研工業株式会社 Method of welding resin parts
JP6161029B2 (en) 2013-06-28 2017-07-12 花王株式会社 Pants-type wearing article and manufacturing method thereof
DK3024424T3 (en) * 2013-07-23 2022-10-24 Convatec Technologies Inc Formable adhesive discs
JP5766252B2 (en) 2013-11-01 2015-08-19 花王株式会社 Pants-type wearing article and manufacturing method thereof
JP6323013B2 (en) * 2014-01-10 2018-05-16 船井電機株式会社 Resin bonded body and resin member bonding method
EP3144127B1 (en) 2015-09-15 2018-01-31 SCHOTT Schweiz AG Medical packaging, in particular pharmaceutical packaging as well as a method for connecting plastic parts of medical packaging
US20220410499A1 (en) * 2021-06-23 2022-12-29 Great Lakes IP Holdings LLC Systems and methods for mating components
CN115101709A (en) * 2022-06-29 2022-09-23 江苏正力新能电池技术有限公司 Glue for battery tab, preparation method of glue and multi-tab battery cell

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0126787A1 (en) * 1983-05-26 1984-12-05 Jan Tjaden Method of laser welding and plastics optimized therefor
WO2000020157A1 (en) * 1998-10-01 2000-04-13 The Welding Institute Welding method
WO2002000144A1 (en) * 2000-06-28 2002-01-03 Coloplast A/S Method for welding components of a multi-layer construction

Family Cites Families (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1528452A (en) 1975-09-26 1978-10-11 Atomic Energy Authority Uk Apparatus for cutting and/or welding thermoplastics sheet
DK145173C (en) * 1980-08-01 1983-02-28 Squibb & Sons Inc PROCEDURE FOR THE PREPARATION OF STOMI POSES
FR2624041A1 (en) 1987-12-02 1989-06-09 Otic Fischer & Porter WELDING METHOD USING A LASER BEAM, ESPECIALLY APPLICABLE TO WELDING GLASS PARTS
DE3813570A1 (en) 1988-04-22 1989-11-09 Fraunhofer Ges Forschung METHOD FOR JOINING WORKPIECES FROM REFLOWABLE MATERIAL WITH LASER RADIATION
GB9009582D0 (en) * 1990-04-27 1990-06-20 Crosfield Electronics Ltd Method of shaping and bonding plastics materials
EP0476865A1 (en) 1990-08-31 1992-03-25 Wako Pure Chemical Industries Ltd Resist material and process for forming pattern using the same
US5495089A (en) * 1993-06-04 1996-02-27 Digital Equipment Corporation Laser soldering surface mount components of a printed circuit board
US5702771A (en) 1994-02-22 1997-12-30 Shipston; Adele C. Activated adhesive system
DE4432081A1 (en) 1994-09-09 1996-03-14 Basf Ag Radiation welding of thermoplastics and non melting materials using laser light
US5729834A (en) * 1995-01-05 1998-03-24 Sloot; Alexander Manufacture of an inflatable applique and its method of manufacture
US5840147A (en) * 1995-06-07 1998-11-24 Edison Welding Institute Plastic joining method
GB2340398C (en) * 1998-08-13 2007-03-16 Bristol Myers Squibb Co Improvements relating to ostomy pouches
US20040056006A1 (en) 1998-10-01 2004-03-25 The Welding Institute Welding method
US6229114B1 (en) 1999-09-30 2001-05-08 Xerox Corporation Precision laser cutting of adhesive members
DE19960104A1 (en) 1999-12-14 2001-06-21 Bayer Ag Laser-weldable thermoplastic molding compounds
DE10003423A1 (en) * 2000-01-26 2001-08-02 Hoechst Trespaphan Gmbh Packaging made of biaxially oriented polyolefin film
US6248974B1 (en) 2000-03-16 2001-06-19 Callaway Golf Company Method and apparatus for laser treatment of a golf ball
IL138530A0 (en) 2000-09-18 2003-02-12 T L M Advanced Laser Technolog Method for the formation of a pattern on an insulating substrate
AU2002225716A1 (en) 2000-11-10 2002-05-21 Gentex Corporation Visibly transparent dyes for through-transmission laser welding
DK174694B1 (en) 2001-05-21 2003-09-15 Coloplast As Stoma bag with a cover of porous material
EP1413927A4 (en) 2001-07-12 2006-06-21 Semiconductor Leading Edge Tec Method for forming fine pattern
ATE383937T1 (en) * 2001-09-29 2008-02-15 Inst Angewandte Biotechnik Und METHOD FOR LASER BEAM WELDING OF PLASTIC PARTS
DE10158016C1 (en) 2001-11-27 2003-01-09 Ploucquet C F Gmbh Creating water-tight connection between layers of textiles, involves use of laser ray to melt adhesive layer
US7201963B2 (en) 2002-01-15 2007-04-10 Gentex Corporation Pre-processed workpiece having a surface deposition of absorber dye rendering the workpiece weld-enabled
EP1331635A3 (en) 2002-01-23 2003-12-17 Fuji Photo Film Co., Ltd. Optical information recording medium
US7255770B2 (en) 2002-08-12 2007-08-14 Mentor Corporation Method for laser welding flexible polymers
US6841024B2 (en) * 2002-10-24 2005-01-11 Lexmark International, Inc. Compensation plates and compliant members for laser welding a non-uniformly thick work piece including inkjet printheads with non-uniformly thick printhead lids
GB0228651D0 (en) * 2002-12-09 2003-01-15 Elopak Systems Improvements in or relating to laminates, methods and products
US20040150688A1 (en) 2003-01-30 2004-08-05 Kin-Ming Kwan Measuring laser light transmissivity in a to-be-welded region of a work piece
DK176243B1 (en) * 2003-10-24 2007-04-16 Coloplast As An ostomy coating plate and a method of making it
WO2005070360A2 (en) 2004-01-27 2005-08-04 Coloplast A/S An absorbing article with zones of different surface properties
WO2007026808A1 (en) * 2005-08-31 2007-03-08 Japan Science And Technology Agency Novel fluorescent labeling compound

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0126787A1 (en) * 1983-05-26 1984-12-05 Jan Tjaden Method of laser welding and plastics optimized therefor
WO2000020157A1 (en) * 1998-10-01 2000-04-13 The Welding Institute Welding method
WO2002000144A1 (en) * 2000-06-28 2002-01-03 Coloplast A/S Method for welding components of a multi-layer construction

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"Laserstrahlschweissen von Thermoplasten im Durchstrahlverfahren" 1 February 2000 (2000-02-01), BASF AG, AWETA THERMOPLASTE , LUDWIGSHAFEN , XP002312668 the whole document *
BACHMANN F G; RUSSEK U A: "Laser welding of polymers using high-power diode lasers" PROCEEDINGS OF SPIE, vol. 4637, 2002, pages 505-518, XP002312667 USA *

Also Published As

Publication number Publication date
DK1744870T3 (en) 2009-04-20
CN1956817A (en) 2007-05-02
WO2005100000A1 (en) 2005-10-27
US8872069B2 (en) 2014-10-28
DE602005011785D1 (en) 2009-01-29
US20080176023A1 (en) 2008-07-24
EP2052804A3 (en) 2009-08-05
US8084138B2 (en) 2011-12-27
EP1737606A2 (en) 2007-01-03
CN1956817B (en) 2011-04-20
US20080145682A1 (en) 2008-06-19
EP1744870B1 (en) 2008-12-17
PL1744870T3 (en) 2009-07-31
CN100528540C (en) 2009-08-19
EP1737606B1 (en) 2009-02-25
DE602005012937D1 (en) 2009-04-09
CN1956836A (en) 2007-05-02
WO2005099960A3 (en) 2005-12-15
DK1737606T3 (en) 2009-06-29
ATE417727T1 (en) 2009-01-15
EP2052804A2 (en) 2009-04-29
ES2319914T3 (en) 2009-05-14
ATE423652T1 (en) 2009-03-15
EP1744870A1 (en) 2007-01-24

Similar Documents

Publication Publication Date Title
EP1737606B1 (en) A method of providing a laser welded polyethylene product and laser welded polyethylene product
JP3682620B2 (en) Welding method
Acherjee Laser transmission welding of polymers–A review on process fundamentals, material attributes, weldability, and welding techniques
US20050224472A1 (en) Product and a method of providing a product, such as a laser welded product
Gonçalves et al. Laser welding of thermoplastics: An overview on lasers, materials, processes and quality
Rodríguez-Vidal et al. Laser transmission welding of ABS: Effect of CNTs concentration and process parameters on material integrity and weld formation
JP5481049B2 (en) Method of joining members using laser
JP4805906B2 (en) Method for sealing fiber-based materials
TWI492807B (en) Method for laser welding resin members and laser welded body of resin members
JP4805049B2 (en) Transparent resin welding method
JP4267286B2 (en) Resin material welding method and resin material welding apparatus
JP2008203186A (en) Substrate laminating method, manufacturing method of microchip, and the microchip
US20150050507A1 (en) Joining of polymer and surface-modified metal by laser welding
JP4192859B2 (en) Dissimilar resin member joining method
KR20160094483A (en) Laser welding Method and apparatus for automobile lamp
Mekaru Thermal and ultrasonic bonding between planar polyethylene terephthalate, acrylonitrile butadiene styrene, and polycarbonate substrates
JP4492784B2 (en) Laser welding member manufacturing method
JP2005305906A (en) Laser welding method for resin materials
Wimpenny et al. Selective Infrared Sintering of Polymeric Powders using Radiant IR Heating & Ink Jet Printing
Tolias et al. Fabrication of glass to PLA joints with an intermediate aluminum layer by using low-cost industrial nanosecond IR fiber lasers
Doe et al. Transmission laser welding of polymers using laser additives
JP4465242B2 (en) Laser welding method and laser welding apparatus
JP2004322335A (en) Method for joining resin materials

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2005715168

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

WWW Wipo information: withdrawn in national office

Country of ref document: DE

WWE Wipo information: entry into national phase

Ref document number: 200580016474.4

Country of ref document: CN

WWP Wipo information: published in national office

Ref document number: 2005715168

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 11578367

Country of ref document: US