DE4319023C1 - Pressure-sensitive, unsupported, double-sided adhesive tape, and use of a polyacrylic ester contact adhesive for its preparation - Google Patents

Abstract

The invention relates to a pressure-sensitive, unsupported, double-sided adhesive tape consisting of a pressure-sensitive adhesive which is covered on both sides with siliconised film, which is characterised in that - it consists of a pressure-sensitive, colourless, glass-clear contact adhesive based on polyacrylic ester, which is covered on both sides with film which is siliconised to different degrees, - the siliconisation on the film is selected such that the force required to separate the contact adhesive from the siliconised film is, on the one side, in the range from 30 to 80 mN/cm and, on the other side, in the range from 5 to 30 mN/cm, and - the polyacrylic ester contact adhesive comprises the following component A) or a mixture of component A) with B) and/or component C) with or without conventional additives: A) 20-100 % by weight of an acrylic ester-acrylic acid copolymer having 2 to 8 carbon atoms in the alcohol component of the acrylic ester and, based on the copolymer, from 1 to 10 % by weight of acrylic acid (K value according to Fikentscher in the range from 70 to 130 (measured according to DIN 51562 in tetrahydrofuran)), B) 10-40 % by weight of an acrylic ester-vinyl acetate-acrylic acid copolymer having 2 to 8 carbon atoms in the alcohol component of the acrylic ester and, based on the copolymer, 10-50 % by weight of vinyl acetate and 1-10 % of acrylic acid (K value according to Fikentscher in the range from 40 to 90 (measured according to DIN 51562 in tetrahydrofuran)), and C) 10-40... Original abstract incomplete.

Description

The invention relates to a pressure-sensitive strapless both self-adhesive tape on both sides, with adhesive on both sides material is covered. The word "band" is meant together hang with the present invention also sheet-like Denote structures such as arches and leaves.

Pressure-sensitive, strapless, self-adhesive tapes on both sides have been used in practice as so-called transfer belts for many Years for temporary fixation as an assembly aid and for permanent bonds for connecting and fixing any Items used. Well-known applications are for example Sealing tapes for envelopes, plastic sleeves and Textiles and tapes for making paper and foils endless sheets, laminating photos and posters on plates, fixing of signs and fixing of electronic components.

Self-adhesive tapes on both sides and their manufacturing processes have been described repeatedly. From U.S. Patent 3,121,021 and DE-OS 17 19 152 are double-sided adhesive tapes  known that stick on both sides when applying adhesive on one side, because the glue, applied from solutions or aqueous dispersion, before drying, partly with a thin fleece backing hiked.

DE-PS 28 21 606 relates to a self-adhesive tape with a through UV light photopolymerized acrylic pressure sensitive adhesive in which glass microfiber balls are dispersed. DE-OS 32 13 246 relates a pressure sensitive adhesive tape with a backing sheet thermoplastic resin. In the carrier sheet are on one side parallel to the longitudinal direction at least up to half of theirs Cross-section of a number of artificial filament yarns (glass fibers) embedded for reinforcement.

In U.S. Patent 4,260,659 a transmission band is described on which two different adhesives one after the other on an abhesive Carrier material have been applied as a coating. Analogue DE-OS 22 06 916 discloses a self-adhesive tape, the adhesive is applied in two separate layers.

DE-OS 39 18 616 discusses a transfer adhesive without Carrier made of a reversible and an irreversible adhesive Side exists. Both adhesive layers contain styrene-isoprene Styrene block copolymers and resins. In reversible adhesive there are also polymeric hollow microspheres and irreversible adhesive contains styrene-ethylene-butylene-styrene Rubber. The transfer adhesive is applied to a silicone on both sides coated release paper and rolled up into rolls.

In DE-OS 40 29 896 are pressure sensitive adhesives, the glass microspheres included, specified in several layers on siliconized paper and laminated together.

DE-PS 38 32 662 relates to a transferable, pressure sensitive Chen adhesive film based on styrene-isoprene rubber, carbon hydrogen resins and α-pinene resins. The adhesive is covered  with a differently siliconized polypropy on both sides len film.

EP 0 141 504 describes an acrylic pressure-sensitive adhesive dispersion for Making paper webs endless. In EP 0 109 177 and 0 147 093 reversible acrylic pressure sensitive adhesives and transfer adhesives are described, that are cross-linked with UV radiation.

Pressure-sensitive transfer tapes, such as those in the trade available and described in the above publications have defects that make them unsuitable for lamination of Photos and color prints on plates affect theirs Restrict possible uses. Many of the self-adhesive Transfer adhesives are not colorless and crystal clear, but have a faint, yellowish tint that matches the Aging increases, and / or a slight haze on it, so that it after laminating photos with the image side on glass panes or reduce color quality from color slides.

Another shortcoming is the formation of a structure in the Adhesive surface, which is due to the fact that finest structures of the covering material in the adhesive surface to mark. This shortage is particularly disadvantageous when high high-quality glossy color photos are laminated on plates, because the Structures through the photo Imprints in the form of a kind Orange peel surface cause that on the picture surface disrupt optically. For this reason, known, double-sided self-adhesive tapes covered with silicone paper, not the requirements that arise with this use. Even high-quality silicone papers made with special Grundie stanchions have been satined and supercalendered as well as with poly Silicon papers laminated with ethylene or polypropylene show more or less embossed surface structures that the Use of adhesive tapes equipped with it for photo lamination affect.  

The pressure sensitive adhesive for photo lamination should not only be colorless and be crystal clear transparent, but in addition to good adhesion and Cohesion have a low cold flow, so unevenness tiny dust particles and other foreign bodies from the adhesive mass are embedded and no markings in the photo to step. Transparent filler particles and glass beads of all kinds in thin adhesive layers often lead to orange peel embossing Photo surfaces if the photos with this core on hard, flat Plates such as B. glass panes and aluminum sheets with strong Contact pressure are laminated on.

For photo laminations where transparency is important a transfer adhesive is usually more suitable than a double-sided one self-adhesive tape, because even crystal-clear film carrier through Streaks, streaks and coagulate particles in the optical Properties can be impaired. High quality, crystal clear Polyester films have excellent transparency but little elastic and deform under roll winding and Photo lamination printing if there are coagulate inclusions or hard in the adhesive Dust particles are present.

With regard to photo lamination, it is important that the Trans adhesive on both sides of the adhesive with abhesive material is covered. Because usually only the photo is first equipped with adhesive, and the lamination on the plate takes place at a later date. Depending on the application, this is The reverse procedure is also possible. The Ab Cover material must not form wrinkles because of such places after the lamination, annoying markings can be seen in the photo.

The object of the invention it is therefore a volume mentioned in the introduction to create ten kind that does not show the disadvantages mentioned. On the one hand, the colorless, crystal-clear, transparent adhesive layer after peeling off the adhesive covering material be smooth on both sides, i.e. no disruptive surface structure exhibit. On the other hand, the cover must be from the first side  the transfer adhesive for laminating photos and plates something easier to peel off than from the second side to one Exclude rewinding of the adhesive on the first side. After Lamination of the tape is said to cover the second Also have the adhesive side easily removed so that a perfect transferability of the adhesive is guaranteed.

This task is accomplished through a pressure sensitive, strapless, self-adhesive tape on both sides made of a pressure sensitive Adhesive covered on both sides with siliconized film is solved, which is characterized in that it consists of

• - a pressure-sensitive, colorless, crystal-clear adhesive adhesive based on polyacrylic acid, which is based on both sides with different siliconized film is covered
• - The film siliconizations are selected so that the release force of the pressure sensitive adhesive compared to the sili butted film on one side of the adhesive in the Range from 30 to 80 mN / cm and on the other hand of the adhesive is in the range from 5 to 30 mN / cm, and
• - The polyacrylic ester pressure sensitive adhesive comprises the following component A) or a mixture of component A) with component B) and / or component C) and, if appropriate, conventional additives:
  • A) 20-100% by weight of acrylic acid ester / acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, based on the copolymer, 1 to 10% by weight of acrylic acid (K value according to Fikentscher in the range from 70 to 130 (measured according to DIN 51562 in tetrahydrofuran)),
  • B) 10-40 wt .-% acrylic acid-vinyl acetate-acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and based on the copoly merisat 10-50 wt .-% vinyl acetate and 1-10 wt .-% acrylic acid (K value according to Fikentscher in the range from 40 to 90 (measured according to DIN 51562 in tetrahydrofuran)) and
  • C) 10-40% by weight of polyvinyl alkyl ether with 1 to 4 carbon atoms in the alkyl group (K value according to Fikentscher in the range from 60 to 130 (measured according to DIN 51562 in tetrahydro furan)).

Preferred embodiments are the subject of the dependent claims.

Component A) in the pressure-sensitive adhesive preferably has a K value according to Fikentscher in the range from 80 to 120 (measured according to DIN 51562 in tetrahydrofuran), component B) preferably a K Fikentscher value in the range of 50 to 80 (measured according to DIN 51562 in tetrahydrofuran) and component C) preferred a K value according to Fikentscher in the range from 70 to 120 (measured according to DIN 51562 in tetrahydrofuran). The acrylic acid content in Component A) is preferably 2 to 8% by weight.

In the copolymers of components A) and B) above, small amounts of other monomers such as methacrylic acid esters, Methacrylic acid, methacrylonitrile, acrylonitrile and styrene are polymerized, the further monomers in amounts of Polymerized 0.5 to 30 wt .-%, preferably 1 to 20 wt .-% could be. For the acrylic acid ester component in the copolymers saten is preferably n-butyl acrylate and / or 2- Ethyl hexyl acrylate.

The acrylic acid ester copolymers and polyvinyl alkyl ethers are preferably processed in the form of dispersions which contain anionic emulsifiers customary in the literature, such as they z. B. in the book "Methods of Organic Chemistry" by Houben-Weyl, Volume 14/1, Macromolecular Substances, Georg-Thieme Verlag, Stuttgart 1972, pages 192 to 208 are described.  

The adhesive according to the invention, in particular a mixture of components A), B) and C), is preferably in the form of an aqueous dispersion adjusted to pH 7 to 8, preferably 7 to 7.5, with ammonia water. This dispersion is coated on a carrier film siliconized on one or both sides, dried to form a self-adhesive, crystal-clear, colorless film and covered or wound up with a siliconized film if the adhesive film was produced on a film siliconized on both sides. The amount of adhesive used (dry) is in the range from 5 to 80, preferably 10 to 60 g / m ² .

Plastic films, preferably polyester and Polypropylene films with reactive silicone resins based on Methyl polysiloxanes or modified derivatives of methyl poly siloxanes. They are made out of dilute organic solution aqueous dispersion or solvent-free on the films on getra gene and cross-linked by condensation or addition. Silicone resins and siliconized films are described in the literature, e.g. B. in the Journal Adhäsion, year 1984, volume 9, pages 18 to 19, and in patents, e.g. B. DE-PS 21 31 740 and DE-PS 30 18 674, be wrote and are commercially available.

The adhesive mixture is adjusted so that the dried one Adhesive film on the siliconized film with separation forces in a range of 30 to 80 mN / cm, in particular 35 to 55 mN / cm is liable. The uncovered transfer adhesive side is with the Wind up the web with the siliconized back of one siliconized cover film on both sides or a second, covered with siliconized film on one side. The separation force level these cover materials are all in one compared to the adhesive Range from 5 to 30 mN / cm, in particular 12 to 25 mN / cm.

The adhesive force on the silicone is under the separating force understood covering material. It is based on the Test specification FINAT FTM3 in a peel test in a tensile force measure  machine with a pull-off speed of 300 mm / min from test strips determined, with the transfer adhesive on one side with a 23 µm thick polyester film is fixed. The trigger win between transfer adhesive with 23 µm polyester carrier film and the siliconized cover film is approximately 90 °, that is Measuring climate 23 ± 2 ° C at 50 ± 6% relative humidity.

Both sides are suitable as a cover film for the transfer adhesive siliconized polyester and polyolefin films on both Sides are siliconized so differently that they face each other the transfer adhesive sets the desired release force level. Siliconized polyester films in thicknesses from 23 to 50 µm are hard and have a relatively high bending stiffness because they are used for Achieving good dimensional stability, stretched and biaxially are usually heat set.

Polyolefin films preferred according to the invention are polyethylene and Polypropylene films. For siliconized polyethylene films from preferably 30 to 100 microns thick, polyethylene is both coagulated low density (LDPE = Low Density Polyethylene) as well as high density (HDPE = High Density Polyethylene). Also come unstretched and monoaxially or biaxially stretched, siliconized Polypropylene films in preferably 30 to 100 microns thick Cover for the transfer adhesive in question. This siliconized Films are a bit harder and not as soft-elastic as that Low density polyethylene film made of LDPE.

If, in addition to roll goods, sheet goods from the transfer adhesive is required is a one-sided siliconized polyester film with the higher separation forces of 30 to 80 mN / cm compared to the Use transfer glue. The second side of the adhesive is then with a siliconized film on one side on polyester or poly olefin base covered with separation forces of 5 to 30 mN / cm. At the winding of 2 polyester films can because of the rigidity of the materials in the bond tension and folds occur arise. In any case, the film composite can be used without problems  wrap when using two polyolefin films or a polyester film be combined with a polyolefin film. The polyolefin material balances tension through the soft, elastic behavior, so that no cross folds in the roll and when unwinding and Production of blanks can be observed.

Polyolefin films occasionally show due to siliconization a very small groove structure. The generated by it extremely weak marking in the surface of the adhesive can the photo lamination by the lamination printing and the minimal cold flow of glue can be balanced. The cover foils can be opaque and / or colored. However, according to the invention colorless, crystal-clear, siliconized cover foils prefers. Such cover films allow a better assessment of the adhesive layers and the rejection of defects. Of the User can avoid coating defects and contamination before Recognize processing.

The invention will be explained in more detail below using an example explained.

example

A siliconized, biaxially stretched, heat-set, colorless, crystal clear polyester film of about 38 microns thick using a roller application process with a pressure sensitive adhesive dispersion based on polyacrylic acid esters on the siliconized side coated. After drying in the drying tunnel, the approx 40 µm thick PSA layer with an approx. 80 µm thick, color loose, transparent, unstretched, siliconized on one side Polyethylene film (LDPE) covered with the siliconized side and the composite is wound into a roll.

The pressure sensitive adhesive used in this example consisted of 80 % By weight of acrylic acid ester / acrylic acid copolymer (K value according to Fikentscher: 100-110) and 20% by weight acrylic acid ester vinyl acetate  Acrylic acid copolymer (K value according to Fikentscher: 50-70). Of the Acrylic acid ester in the copolymers was n-butyl acrylate Acrylic acid content was 2 to 8 wt .-%.

The colorless, crystal-clear transfer adhesive faced the sili butted polyester film separation forces from 40 to 48 mN / cm, ge separation forces of 15 compared to the siliconized polyethylene film up to 22 mN / cm. After storage for one month at 70 ° C the adhesive did not discolour and the release forces remained constant. The adhesive coating could be easily applied to plates Plexiglas, aluminum, polystyrene and PVC as well as photos, slides and Transfer image prints.

Measured according to AFERA 4001, the bond strength of V2A steel was 10 minutes bonding time 5.9 N / cm, after 24 hours bonding time 7.4 N / cm, being on the non-glued side of the transfer a 23 µm thick polyester film was laminated.

Claims (17)

1. Pressure-sensitive, strapless, double-sided self-adhesive tape made of a pressure-sensitive adhesive which is covered on both sides with siliconized film on one or both sides, characterized in that it consists of

• - there is a pressure-sensitive, colorless, crystal-clear pressure-sensitive adhesive based on polyacrylic acid ester, which is covered on both sides with differently siliconized film,
• - The film siliconizations are selected so that the release force of the pressure sensitive adhesive compared to the siliconized film is on the one hand in the range from 30 to 80 mN / cm and on the other hand in the range from 5 to 30 mN / cm, and
• - The polyacrylic ester pressure sensitive adhesive comprises the following component A) or a mixture of component A) with component B) and / or component C) and, if appropriate, conventional additives:
  • A) 20-100% by weight of acrylic acid ester-acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, based on the copolymer, 1 to 10% by weight of acrylic acid (K value according to Fikentscher in the range from 70 to 130 ( measured according to DIN 51562 in tetrahydrofuran)),
  • B) 10-40 wt .-% acrylic acid-vinyl acetate-acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and based on the copoly merisat 10-50 wt .-% vinyl acetate and 1-10 wt .-% acrylic acid (K value according to Fikentscher in the range from 40 to 90 (measured according to DIN 51562 in tetrahydrofuran)) and
  • C) 10-40% by weight of polyvinyl alkyl ether with 1 to 4 carbon atoms in the alkyl group (K value according to Fikentscher in the range from 60 to 130 (measured according to DIN 51562 in tetrahydro furan)).

2. Adhesive tape according to claim 1, characterized in that at the adhesive component A) has a K value according to Fikentscher in the range from 80 to 120 (measured according to DIN 51562 in Tetrahydrofuran), component B) has a K value Fikentscher in the range from 50 to 80 (measured according to DIN 51562 in tetrahydrofuran) and component C) one K value according to Fikentscher in the range from 70 to 120 (measured according to DIN 51562 in tetrahydrofuran). 3. Adhesive tape according to one of claims 1 or 2, characterized records that the acrylic acid ester compo nents in the copolymers n-butyl acrylate and / or 2- Contain ethyl ethyl acrylate. 4. Adhesive tape according to one of claims 1 to 3, characterized records that in the pressure sensitive adhesive in the polyacrylic acid ester copolymers of other monomers, preferably methacrylic acid esters, methacrylic acid, methacrylonitrile, acrylonitrile and styrene are polymerized. 5. Adhesive tape according to claim 4, characterized in that the other monomers in amounts of 0.5 to 30 wt .-%, in particular copolymerized 1 to 20 wt .-% in the copolymers are.   6. Adhesive tape according to one of claims 1 to 5, characterized records that the release force of the pressure sensitive adhesive compared to the siliconized film on the one hand in the range of 35 up to 55 mN / cm and on the other hand in the range from 12 to 25 mN / cm. 7. Adhesive tape according to one of claims 1 to 6, characterized records that the adhesive sides with one and the same, but different siliconized film on both sides or with two different sili that are different on one side butted foils are covered. 8. Adhesive tape according to one of claims 1 to 7, characterized records that the siliconized on one or both sides Cover films made of polyester or polyolefin, in particular Polyethylene or polypropylene exist. 9. Adhesive tape according to one of claims 1 to 8, characterized records that in the case of cover with two siliconized Films two polyolefin films or one polyester and one Polyolefin film are combined. 10. Adhesive tape according to one of claims 1 to 9, characterized records that the siliconized polyester films a Have a thickness of 23 to 50 µm. 11. Adhesive tape according to one of claims 1 to 9, characterized records that the siliconized polyolefin films a Have a thickness of 30 to 100 µm. 12. Adhesive tape according to one of claims 1 to 11, characterized records that the siliconized films colorless and are crystal clear transparent. 13. Adhesive tape according to one of claims 1 to 12, characterized records that it is wound into a roll.   14. Use of a pressure-sensitive polyacrylic ester pressure-sensitive adhesive which comprises the following component A) or a mixture of component A) with component B) and / or component C) and, if appropriate, customary additives:

• A) 20-100% by weight of acrylic acid ester-acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, based on the copolymer, 1 to 10% by weight of acrylic acid (K value according to Fikentscher in the range from 70 to 130 ( measured according to DIN 51562 in tetrahydrofuran)),
• B) 10-40% by weight of acrylic acid ester / vinyl acetate / acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, based on the copolymer, 10-50% by weight of vinyl acetate and 1-10% by weight of acrylic acid (K. -Value according to Fikentscher in the range from 40 to 90 (measured according to DIN 51562 in tetrahydro furan)) and
• C) 10-40% by weight of polyvinyl alkyl ether with 1 to 4 carbon atoms in the alkyl group (Fikentscher K value in the range from 60 to 130 (measured in accordance with DIN 51562 in tetrahydrofuran)),

and siliconized differently on one or both sides Cover foils, the foil siliconizations so out are chosen that the release force of the pressure sensitive adhesive compared to the siliconized film on one side of the adhesive in the Range from 30 to 80 mN / cm and on the other side of the Adhesive is in the range of 5 to 30 mN / cm, for the production of strapless, self-adhesive on both sides Pressure-sensitive adhesive tapes according to one of claims 1 to 13. 15. Use according to claim 14, characterized records that the pressure sensitive adhesive is used in the manufacture of the adhesive tape is present in the form of an aqueous dispersion. 16. Use according to claim 15, characterized in that that the pH of the aqueous dispersion with ammonia water is set to 7 to 8, preferably 7 to 7.5.