DE4040158A1 - Coated flat articles useful in pharmaceutical and foodstuff industries - obtd. by coating carrier sheet with aq. dispersion of poly:hydroxy-alkanoate, drying, and opt. heating to sinter or melt coating - Google Patents

Abstract

Articles are obtainable by coating on one or both faces flat carrier sheet(s) with aq. dispersion of a polyhydroxyalkanoate (I) opt. with other thermoplast (II) and drying to remove dispersion agent opt. with heating, during or after drying to temp. at which coating sinters or melts with film formation. USE/ADVANTAGE - Used in pharmaceutical and foodstuff industries, partic. for packaging also medicinal and hygiene applications e.g. wound dressings. (I) are biologically degradable and articles are readily disposed of, articles contain no solvent residues and can be formed as porous, gas- and air-permeable coatin

Description

The invention relates to a sheet-like object, in For example, a web or a plate by coating a sheet-like carrier layer with an aqueous Disper sion of polyhydroxyalkanoates (PHA), optionally together with other thermoplastics.

PHA can be biotechnologically by means of special Bak For example, in EP-A-00 52 459 or EP-A-01 44 017 is described. They are biological degradable and can therefore be disposed of easily and environmentally friendly become. One application for PHA is in the scriptures US-43 72 311 and EP-A-01 42 950 shown, in which films water-soluble polymers are described with a solution of PHA in methylene chloride or chloroform and coated Production of incontinence bags are used. In the WO 90/01 043 films of hydrophilic polymers, such as. B. Starch or gelatin, with a solution of PHA in chloroform or trichlorobenzene coated and to remove the solution dried by means of. The PHA film provides protection to the darun underlying starch or gelatin layer before dissolution at Kon time with water. These coatings have the disadvantage that the organic solvents used in the preparation are harmful to health and that in the finished coating always residues of these solvents are included, which is mainly their use in the food or pharmaceutical industry strie, in particular as packaging material, as well as for materia makes it impossible for wound care.

Another disadvantage of the known coatings is that that they are only available as dense films. This is true necessary for those applications where an impermeable and dense coating is required. For many applications, for example, in medical bandages or in in of medicine or hygiene materials used for the  Absorbing body fluids, however, is a porous, especially special gas and air permeable coating required, the not obtained with the help of these solvent coatings that can.

The object of the invention was to provide a coated article to provide with improved properties. This could with Coatings are achieved by the use of aqueous PHA dispersions were obtained.

The subject of the present invention is accordingly a be Layered sheet-like object, by the one or two-sided coating of one or more sheet-like Carrier layers with an aqueous dispersion of polyhydroxyal kanoaten (PHA) or a mixture of PHA and other thermo plastic and subsequent drying to remove the dispersion onsmittels, optionally during or after the drying is heated to temperatures at which the Be layering sintered or melts under film formation.

As PHA, for example, such as in forum Microbiology 1989 (4) page 191 are described such. B. Po lyhydroxybutyrate (PHB) or polyhydroxyvalerate (PHV) or de ren copolymers. Preference is given to polyhydroxybutyrates and co polymers of hydroxybutyric acid and hydroxyvaleric acid, such as they z. As described in EP-A-01 42 950 are used.

As further thermoplastics, which optionally together with the PHA are used in the dispersion are, for example, Po lyolefins, such as. As polyethylene or polypropylene, polyamides, Paraffins, PE waxes, polystyrene, cellulose acetate, polyurethanes, Polyester, polycarbonates, polymethyl methacrylate and ethylene vi nylacetat possible. Preference is given as further thermoplastics Po lyolefins, polyesters and polyamides used.

The dispersions are obtained, for example, by stirring in PHA powder and optionally other thermoplastic powders in water and then homogenizing. In a particularly economical method, PHA dispersions can be obtained directly during the workup of the PHA-storing microorganisms during their biotechnological production. The PHA powder advantageously has an average particle size (D _50% value) of less than 25 μm (Cilas 715 laser granulometer). The type powder can z. B. by wet milling of the PHA. The D _50% value of the optionally used other thermoplastics is preferably less than 25 microns. For the production of uniform, well filmed coatings, the smaller the melt flow index (MFI), the smaller the poly mer particles must be.

Advantageously, the dispersion further conventional addition substances, such as B. dispersants, stabilizers, plasticizers, Wetting agents, thickeners, antioxidants, sunscreen tel, antistatic agents, preservatives, dyes, fillers, Pigments, but also other finely divided polymers or polymer added dispersions. With the help of such additives it is possible, the properties of the coating on the respective Application to vote.

With water as a dispersant be for PHA dispersions be especially good results. In principle, however, it is possible, as dispersing agent mixtures of water with alcohol for example, ethanol, isopropanol, n-propanol, n-butanol, iso-butanol, t-butanol or longer-chain alcohols. This is especially advantageous where in the course of PHA manufacture ment the PHA is obtained in such dispersant mixtures.

As sheet-like carrier layers are all web or plate-shaped materials, preferably nonwovens, fabrics, Fo lien or sheets of plastic, cellulose, starch, Kohlenhy draten, gelatin, proteins or other hydrophilic polymers, Textile fiber, metal or glass. Particularly preferred as a carrier layer are paper or board webs which may be ge painted or with plastic or with metals, such. B. Aluminum, coated or laminated.

Another object of the invention is a method for Her position of coated sheet-like objects. He  According coated according to the invention coated sheet-like objects produced by one or more sheet-like Trä gerschichten with an aqueous dispersion of PHA or a Mixture of PHA with other thermoplastics, one or both coated on the side and then to remove the Dispersing agent are dried. A significant advantage The invention is that, depending on the drying conditions either a more or less porous coating or a dense and closed coating film is obtained. By the choice of drying conditions and grain size of the poly Merpe particles, the degree of porosity controlled specifically become. In the event that one, closed and denser Coating film is desired, either already during drying or subsequent to drying to temperatures heated, in which the coating melts with film formation.

For certain applications, however, is a porous, not ver film coating advantageous, for example, where a Gas and air permeability is necessary or desired, such as for example, in medical dressing materials for wound care. A porous coating is obtained by treating the PHA-Be coating is not heated until it melts, causing no completely closed film is formed. In certain cases A sintering in the range of the melting point is favorable to To produce coatings with defined porosity, the z. B. for absorbing body fluids in medicine and Hy can be used. Another is a non-filming wherever appropriate for processing reasons only at a later date a filming or a hot sealing is required.

The necessary temperatures and residence times depend on the type and purity of the PHA (temperature range of the ref cens, thermal stability, melt viscosity, grain size ver division in the dispersion), of the layer thickness, of the ther mix stability and thermal conductivity of the carrier material, from the moisture content of the carrier and the coating, from the type of thermoplastics and additives added and of Heat transfer.  

The aqueous PHA dispersion can be mixed with those described in the paper and tex usual tilindustrie methods, for example by means of doctoring, Blades, air brushes, brush or glue presses, reversed gravure Rolls, printing units, spray nozzles, or by means of dipping, Pflat rule, spraying be applied to a carrier layer. because at the dispersion may be one or both sides, or between several carrier layers are applied.

The removal of the dispersant and the filming of the Coating can z. B. by means of drying chambers, heated whale zen, hot air ducts, infrared or microwave dryers, Schwe dry or with heated calenders. The distance of the dispersant and the film can also be in two be carried out separate stages, for. B. over two different the heavily heated zones in the drying channel. After the coating or filming the object is cooled.

The drying and filming conditions must be in the manner of be matched to the PHA and the carrier material. For example For example, PHB / PHV copolymers have one with increasing hydroxyva lauric acid content decreasing melting point. Under too high ther Mixer load partial degradation of PHA occurs by discoloration can occur and it can settle for cleavage molecular compounds come.

In the following examples, those listed below were Materials used:

• a) polymers
  PHB:
  Polyhydroxybutyrate biopolymer granules (Goodfellow, GB, technical grade, catalog no. BU 396 310/2)
  MFI (DIN 53 735-2.16 kg / 190 ° C) 39.25 g / 10 min
  Melting point (DSC maximum) 173.3 ° C (heating rate: 20 ° C / min)
  Max. Granule size: approx. 5 mm PHB / PHV:
  Polyhydroxybutyrate-co-hydroxyvalerate 80 mol%: 20 mol% (Goodfellow, GB, Flocculent, technical grade, Catalog No. BU 376 420/1)
  MFI (DIN 53 735) 8.83 g / 10 min
  Melting point (DSC maximum) 126.6 ° C
  Grain size: approx. 1 mmPE:
  Polyethylene, Coathylene Type HA-1681 (Plastlabor, Hoechst-Celanese, Bull Switzerland)
  MFI (DIN 53 735) 70 g / 10 min
  Melting point (DSC maximum) 103.3 ° CPP:
  Polypropylene, Type Coathylene PB 0580 (Plastlabor, Hoechst-Celanese)
  Melting point: (DSC maximum) 159.8 ° C
• b) surfactants
  Polyoxyethylene glycerol monolaurate, HLB = 15.7 (Tagat L2, Goldschmidt, FRG)
  Fatty alcohol polyglycol ethers (Marlipal 1618/40, Hüls, FRG)
  Alkylphenol ethoxylate (Nekanil LN, BASF)
  Dioctyl sodium sulfosuccinate, Merck
• c) thickener
  Acrylic copolymer dispersion (30% by weight) (Viscalex HV30, Allied Colloids, UK) Polyethylene oxide (Polyox WSR 301, Union Carbide, CH) A 5% aqueous solution was used. Maleic anhydride-methyl vinyl ether copolymer (Gantrez AN-169, GAF, USA). A 10% hydrolyzed aqueous solution was used, which was adjusted to pH 6-7 with ammonia.
  Sarpifan HP75 (42% by weight), Stockhausen, FRG
• d) Defoamer DNE (Bayer)
• e) Polymer dispersion:
  Ehaflex 507, (35% polyamide dispersion), Akzo (NL) Mobil Cer-c, (46% paraffin disperison), Mobil (FRG)
  Polyethylene dispersion:
  The polyethylene dispersion used was prepared in the following order with stirring: (Coathylene Dispersions, Technical Information, Plast Labor SA, 1982, Bulle, Switzerland) 57.45% by weight of water
  1.50% by weight Viscalex HV 30
  0.40% by weight defoamer DNE
  0.50% by weight of Nekanil LN
  40.00% by weight Coathylene HA 1681
  0.15 wt .-% ammonia (26gew.-ige solution) The pH of the dispersion was about 8. The viscosity was about 60 s flow time measured in the Ford cup (4 mm / 25 ° C).
  Polypropylene dispersion:
  The polypropylene dispersion used was prepared analogously to the PE dispersion: 69.45% by weight of dist. water
  1.20% by weight Viscalex HV-30
  0.30% by weight defoamer DNE
  0.50% by weight of Nekanil LN
  28.40% by weight Coathylene PB 0580
  0.15% by weight of ammonia (26% by weight solution) The pH of the dispersion was about 8.
  The viscosity measured as the flow time with a 4 mm Ford flow cup was about 60 s (25 ° C).
• f) carrier layers
  Paper:
  Japan Post 70 gsm (Neusiedler AG, Austria)
  Carton:
  Recycled cardboard DP-450, 450 g / m² (Mayr-Melnhof, Austria)
  al:
  Aluminum foil 140 g / m²
  Tissue:
  Cotton fabric, seamless tubular gauze, type Sanigauz 56, approx. 90 g / m² (Fa. Ständig, Vienna, Austria)
  Kraft paper:
  KS SCL 80 G natural, kraft sack, semiclupac, 80 g / m 2 (Patria Papier und Zellstoff AG, Austria)

analysis methods Particle size analysis

The particle sizes of the polyhydroxyalkanoate (after grinding on the corundum disk mill) were determined by means of Cilas 715 laser granulometer, Pabisch, FRG (water as dispersing agent, stirred for 2 minutes, 1 minute of ultrasound) and the associated evaluation program (according to DIN 66141) as characteristic parameters the D _50% (median) and specific surface area were determined. The calculation of the volume-related specific surface S _V in m ² / cm ³ (assuming spherical particles) was carried out with the evaluation program of the company Pabisch:

Differential scanning calorimetry

Device: DSC 2, Perkin-Elmer.
Temperature range: 0-210 ° C
Heating rate: 20 ° C / min

viscosity determination

The viscosity of the dispersions is determined by means of Ford outlet cup (DIN 53211), nozzle diameter: 4 mm, Temperature: 25 ° C.  

example 1 1.1. Grinding of the polyhydroxyalkanoate

PHB granules were wet-ground on a laboratory corundum disk mill (type Ko ruma, Maschinenbau Neuburg, Baden, FRG). For this purpose, 200 g of PHB were slurried in 2 liters of water and initially ground at a rough gap setting. Subsequently, the fineness of the mill was gradually reduced until the smallest still possible grinding gap limit (grinding limit) was reached. The ground PHB slurry was filtered off (Blauband filter, Schleicher & Schull, FRG). The resulting wet filter cake had a dry matter content of 60%. This wet cake was tested for grain size properties on the Cilas-715 laser granulometer.
D _50% value = 1.9 μm
Specific surface area (volume-related) = 4.25 m ² / cm ³
The water-moist ground PHB prepared in this way was not dried but immediately further processed to an aqueous dispersion as described below.

1.2. Preparation of the PHB dispersion

To a solution consisting of 22.3 g dist. Water, 1.0 g of Tagat L2 and 0.3 g defoamer DNE were added to 75 g of the water-moist PHB filter cake prepared according to 1.1. This mixture was stirred for 5 minutes at room temperature (paddle stirrer, stirrer diameter = 65 mm, rotational speed = 600 rpm). Subsequently, 1.2 g of Viscalex HV-30 were added. The resulting dispersion was thixotropic. After stirring for a further 5 minutes, 0.20 g of a 26% strength by weight aqueous ammonia solution were added and the pH was adjusted to 7.8, whereupon the thixotropic effect disappeared again. This mixture was stirred for about 3 minutes while maintaining a stable dispersion. The viscosity of this dispersion was measured after 24 hours in 4 mm Ford Auslaufbe cher according to DIN 53 211 at 25 ° C. The flow time of this dispersion was 74 seconds, the PHB content 45% by weight, the density measured with the densitometer DMA-35 (Paar KG, Graz, Austria), 1.072 g / cm ³ at 25 ° C. The stability of the thus prepared PHB dispersion was at room temperature under non-aseptic conditions for at least 1 year, no sedimentation occurred.

Example 2

Analogously to Example 1 were added to a solution of 33.9 g of dist. Water and 0.40 g of Tagat-L2 41.67 g of ground water-wet PHB-Filkerkuchen (60 wt.% Dry matter, D _50% = 1.9 microns, specific surface = 4.40 m ² / cm ³ ) and under Stirred for 5 minutes at room temperature. Thereafter, 24 g of a 5 wt.% Aqueous solution of Polyox WSR 301 were added as a thickener and further stirred for about 10 minutes, with a stable Di spersion was obtained.

Example 3

A dispersion was prepared analogously to Example 2, but instead of PHB a PHB / PHV copolymer (dry substance: 60% by weight, D _50% = 3.7 μm, specific surface area = 2.40 m ² / cm ³ ) was used.

Example 4

Analogously to Example 1 were added to a solution of 0.5 g of Tagat L2 in 46.1 g of dist. Water with stirring 46 g of a wet-milled PHB filter cake (60% dry matter, D _50% = 1.9 microns, specific surface = 4.40 m ² / cm ³ ) was added. After 5 minutes, 7 g of a hydrolyzed aqueous 10 wt.% Solution of Gantrez AN-169 was added as a thickener with stirring and after further 5 minü tigem stirring with 0.4 g of a 26 wt.% Ammonia solution to a pH set by 6.0. The dispersion was stirred for a further 10 minutes. The viscosity measured after 24 hours in the 4 mm Ford-Auslaufbecher (DIN 53211) at 25 ° C was 50 seconds.

Example 5

Analogously to Example 1, an aqueous solution consisting of 0.4 g of Marlipal 1618/40 and 39.5 g of dist. Water, 37.1 g of a wet-milled water-moist filter cake of PHB / PHV Copolyme ren (dry matter: 62 wt.%, D _50% 3.4 microns, spec. Surface 2.43 m ² / cm ³ ) was added with stirring and while a stirring time of 7 minutes homogeneously dispersed. Subsequently, 23.0 g of a 5 wt.% Aqueous solution of Polyox WSR-301 was added and stirred for a further 10 minutes.

Example 6

Analogously to Example 1, PHB granules were wet-ground with the corundum disk mill. Subsequently, however, the PHB was not filtered, but centrifuged. 130 g of this concentrated aqueous PHB cake (dry matter 29.0% by weight, D _50% = 0.69 μm, specific surface area = 10.96 m ² / cm ³ ) were added with stirring (paddle stirrer, stirrer diameter = 65 mm Stirrer speed = 600 rpm) at room temperature, 0.55 g defoamer DNE and 0.28 g Nekanil LN are added successively. After stirring for 7 minutes, 1.93 g of Viscalex HV-30 (30% by weight acrylic copolymer dispersate) was added and stirred for about 5 minutes. It was then adjusted to a pH of 8 with 0.62 g of 26% ammonia and stirred for a further 3 minutes. The aqueous PHB dispersion thus prepared was stable at room temperature under nonaesthetic conditions for at least one month.

Example 7

A dispersion based on PHB and PE was prepared by Mi from

• a) 100 g of a PHB dispersion according to Example 1 and
• b) 100 g of a PE dispersion of 57.45% by weight of water, 1.50% by weight Viscalex HV 30, 0.40% by weight defoamer DNE, 0.50% by weight Nekanil LN, 40 wt% Coathylenes HA 1681 and 0.15 wt% Ammonia (26% by weight solution). The pH of the dispersion was about 8, the viscosity (4 mm Ford cup / 25 ° C)  was 60 sec flow time.

Example 8

A dispersion based on PHB and PP was prepared by Mi from

• a) 100 g of a PHB dispersion according to Example 1 and
• b) 100 g of a PP dispersion of 69.45% by weight of water, 1.20% by weight Viscalex HV 30, 0.30% by weight of defoamer DNE, 0.50% by weight Nekanil LN, 28.40 wt% Coathylene PS 0580 and 0.15 wt% Ammonia (26% by weight solution). The pH of the dispersion was about 8, the viscosity (4 mm Ford cup / 25 ° C) was 60 sec flow time.

Example 9

A dispersion based on PHB and polyamide (PA) was herge provides by mixing

• a) 100 g of a PHB dispersion according to Example 1 and
• b) 100 g of a 35 wt.% Polyamide dispersion (Ehaflex 507, Akzo, NL)

Example 10

A dispersion based on PHB and paraffin was prepared by mixing

• a) 100 g of a PHB dispersion according to Example 1 and
• b) 100 g of a 46 wt.% Paraffin wax dispersion (Mobile Cer-C, Mobil, FRG)

Example 11-15

Dispersions were prepared according to Example 1, the zu additionally contained the additives listed in Table 1:

Additives to the PHB dispersion according to Example 1 example 11 8.51 g sodium lauryl sulfate (Fluka) 2.60 g of amyl alcohol (mixture of isomers, Merck) 12 11.1 g of dioctyl sodium sulfosuccinate (Merck) 13 5.26 g of ethanol 14 5.26 g of propanol-2 (Baker, NL) 15 5.26 g pentanol-2 (Merck)

Examples 16-37 Coating of the carrier layers

The dispersions prepared according to Examples 1-15 wur by means of KCC doctor blade applicator (Gockel, Munich) on un applied different carrier materials. The coated ones Carriers were then thermally treated in a drying oven delt, with the exception of Examples 18 and 35 uniform, dense and flexible coatings were obtained. At the Bei Play 18 and 35 have been uniform, well-fitting, flexible and permeable coatings. The ver used carriers, the temperatures in the drying cabinet with the da associated times, and the basis weights of Be Coatings are summarized in Table 2.  

Table 2

coatings

Claims (8)

1. Coated sheet article obtainable by one or two-sided coating of one or more fl chenförmiger carrier layers with an aqueous dispersion of polyhydroxyalkanoates (PHA) or a mixture of PHA and other thermoplastics and then drying for Removal of the dispersant, whereupon if desired heated to temperatures or after drying, where the coating is sintered or filming melts. 2. Coated sheet-like article according to claim 1, since characterized in that the PHA is a polyhydroxybutyrate or a copolymer of hydroxybutyric acid and hydroxyvale is rianic acid. 3. A coated sheet-like article according to claim 1 or 2, characterized in that the further thermoplastic poly olefin, polyester or polyamide. 4. Coated sheet-like article according to one of the An Claims 1 to 3, characterized in that the carrier Layer of fleece, fabric or foil made of art fabric, cellulose, wood pulp, textile fiber, metal or glass consists. 5. A coated sheet-like article according to claim 4, since characterized in that the carrier layer consists of a Pa pier or board web, if necessary with a Metal coated or laminated. 6. A method for producing a coated sheet-like Article, characterized in that one or more sheet-like carrier layers with an aqueous dispersion polyhydroxyalkanoates (PHA) or a mixture of PHA coated with other thermoplastics on one or both sides and then ge to remove the dispersant ge be dried, wherein during or after drying gege  if necessary heated to temperatures at which the Be layering sintered or melts under film formation. 7. Aqueous dispersion of PHA and optionally further Ther moplastics for coating sheet-like carriers Layers according to one of claims 1 to 6. 8. Use of an aqueous dispersion of PHA and given if other thermoplastics for coating surfaces shaped carrier layers according to one of claims 1 to 6.