DE19805672A1 - Completely biologically degradable multilayer wall covering assembly - Google Patents

Abstract

A completely biologically degradable multilayer wall covering assembly comprises, from adjacent the wall to the visible outer layer, (a) at least 1 wallpaper layer, with (b) an attached loading layer of workable thermoplastic polymer, and if required one or more printing layers (c) on the (b) layer. The loading layer (b) consists of a biologically degradable material, which, in accordance with OECD 301 B, undergoes more than 25% degradation after 28 days. An Independent claim is included for a process for production of the completely biologically degradable assembly in which one or more biologically degradable polymers are used.

Description

The invention relates to a fully compostable multilayer Wall covering composite showing from the side near the wall to the visible side Hin a) at least one layer of wallpaper made of paper, b) then one Coating layer made of thermoplastically processable polymers and optionally on b) c) one or more printing layers.

Furthermore, the present invention relates to a method for manufacturing such composite wallcoverings.

In general, wallcovering composites must have an adequate Permeability to water vapor and sufficient dimensional stability have when fastening.

Show wallpapers used in the prior art for wallcovering purposes usually contain PVC impregnations and are therefore not readily biodegradable. Only so-called woodchip wallpapers are available without plastic impregnation, but as soon as a texture of wallpaper or printing is desired for reasons dimensional stability, stabilization with PVC-containing materials indispensable.

It is therefore very desirable to include printable wallcovering assemblies Not to provide non-biodegradable materials, where, however, the paper wallpaper layer is sufficiently supported without the permeability of the overall network to an unacceptable level to let it sink down. Furthermore, the wallcovering composite to be created meet all the requirements for wallpapers and at the same time are excellent organic be degradable (compostable). A process for the production of fully compostable multi-layer composite wallcoverings specified  will.

These tasks are solved by a wall covering association of initially mentioned type with the characteristics of the characterizing part of Claim 1. Preferred embodiments are in the of claim 1 dependent subordinate claims under protection, while in procedurally, the subject of claim 7 a solution of presented problems underlying the invention.

Surprisingly, it works with a multi-layer Wall covering composite, in which the coating layer b) which with at least one layer of wallpaper made of paper a) is connected and which optionally has one or more printing layers c), characterized in that the coating layer b) made of a thermoplastically processable polymer which is degraded after 28 days in the degradation test according to OECD 301 B produced by <25% to provide a wallpaper which is a exhibits excellent biodegradability (compostability). Here Particularly surprising that the compostability of the multilayer Wallcovering composite is better than the compostability of the structure of the wallcovering association involved materials individually seen. I.e. within the multi-layer composite of wallcovering rots the worst compostable component (e.g. the Layer of plastic) faster than the comparable single layer below corresponding composting conditions. This quasi synergistic effect was not predictable and can therefore be classified as completely surprising.

In the context of the invention, "compostability" is understood to mean a property of the individual materials used and of the entire composite - that is to say the multi-layer wall covering composite - the compostability being in a specific connection to the biodegradability. In particular, compostability means biodegradability in the soil under composting conditions. Biodegradable polymers and plastics are materials that are quantitatively converted into either CO ₂ and H ₂ O or CH ₄ and H ₂ O by microorganisms under aerobic or anaerobic conditions.

A number of tests exist to investigate compostability, such as for example tests with isolated enzymes, plastic or Film composting tests in which plastic coatings or plastic films buried in mature compost at 58 ° C and biodegradation is visually rated or degradation tests in composting tests or Earth burial attempts.

In the sense of the invention, completely or easily compostable means that a Material in the biodegradation test according to OECD 301 B after 28 days Degradation of <25% generated. This is preferred by both the individual Layers or layers of the multilayer according to the invention Wallcovering composite fulfilled, as well as from the composite as a whole or even still surpassed. The measurement method is explained in more detail in the example section.

It is also particularly noteworthy in the invention that provided that or more printing layers are present, these printing layers also consist of biodegradable materials. The used upcoming color pigments will be compostable selected and blend with their inherently good biodegradability (Compostability) excellent in the overall concept of a complete compostable wallpaper. The invention thus represents a universal Wallcovering replacement usable for a variety of purposes Composite wallcovering available.

The paper wallpaper layer a)

The basic structure of the wallcovering assembly according to the invention looks like Base a) at least one layer of wallpaper made of paper. This is considered close to the wall referred to, which clarifies that the at least one layer of wallpaper When used as intended, paper in contact with the clad wall part. The structure of the base layer a) is made of paper variable and therefore versatile, especially a plurality of paper layers, which may also be provided with Intermediate layers of adhesion promoters or other materials with one another can be connected. However, in the simplest case it is preferred that it the base layer a) is a single layer of wallpaper made of paper. In principle, any paper material familiar to a person skilled in the art is for the Base layer a) of the multilayer wall covering composite according to the invention applicable. In a particularly expedient embodiment, the Wallpaper layer a) around wood-containing base paper, making a particularly good one Permeability of the base layer a) is achieved. However, it can also trade wood-free paper. Furthermore, the paper can be used Reduction in paper yellowing are treated. Procedures for this are in the patents DE 36 30 772 and EP 0 261 316. Of such Natural materials are known to the person skilled in the art that they are biodegradable are and have a useful compostability.

The coating layer b)

In the case of the invention, the base layer a) forms with a coating layer b) a composite of thermoplastically processable polymers. The serves Coating layer made of thermoplastically processable polymers b) especially to maintain the structure of the multilayer Wallcovering association.  

According to the invention, only such structure maintenance layers are used b) used, which has a good biodegradability in the OECD 301 B test and at the same time with a sufficiently high permeability a certain layer thickness. Among those in question In a preferred embodiment, materials have in particular layers made of biodegradable polycaprolactone, polyesters, polyester amides, Proven polylactides and / or starch.

b1) poly (ε-caprolactone) (PCL)

Poly (ε-caprolactones) are a preferred plastic material for the Coating layer made of thermoplastically processable polymers b) des wall covering composite according to the invention. Are poly (ε-caprolactones) by polymerization of ε-caprolactone in the presence of Aluminum isopropoxide available. The polymer obtained is similar in many Features an LLDPE (linear low density poly ethylene) that feels wax-like and is completely biodegradable. Poly (ε-caprolactone) is already commercially available for more than 20 years, but has not been Stabilizing layer used for wallpaper, neither as a coating layer in Form of sprayed-on masses still as a film layer.

A particularly suitable PCL is under the product name TONE® Po lymers available. TONE® polymers have a sharp melting point 60 ° C. They show excellent adhesion and good mechanical Properties. They are well compatible with many other polymers and Fillers and can essentially be mixed and matched using conventional methods to edit.

TONE® polymers are in suitable environments such as compost, soil and Sewage sludge biodegradable, whereby both according to the mushroom growth  ASTM G-21-70, for laboratory burial, for burial in Field test, with the test method "composting test" and in aerobic Biometer test according to ASTM D 5209-92 obtained significantly good biodegradation results will.

b2) polyester amides

Polyester amide materials which are suitable for coatings which are used in Composite with paper layers are suitable in the context of the invention, have in generally relatively high molecular weights with ester contents between 30 and 70% by weight, are easy and reproducible to produce and have good mechanical properties also for the production of transparent films as well as good biodegradability or compostability. Such Materials are, for example, from the EP 0 641 817 A2 known. The aliphatic polyester amides have aliphatic ones Ester and aliphatic amide structures and have melting points of at least 75 ° C. The weight fraction of the ester structures is between 30 and 70%, the proportion of amide structures between 70 and 30%. The one for manufacturing The copolymers suitable for the films have an average molecular weight (MW determined by gel chromotography in m-cresol against standard polystyrene) from 10,000 to 300,000, preferably 20 to 150,000.

Such polyester amides are preferably synthesized by mixing the Amides or ester-forming starting components and polymerization elevated temperature under autogenous pressure and then distilling off the Water of reaction and excess monomers in vacuo and at elevated Temperature. The arrangement of the ester or amide segments is carried out by the Purely statistical synthesis conditions, d. H. these connections are not as thermoplastic elastomers rather than thermoplastics. The Structure of thermoplastic elastomers is used in the specialist literature "the simultaneous presence of soft and elastic segments with high  Ductility and low glass transition temperature (to Tg value) as well as hard and Crystallizable segments with low ductility, high Tg and Tendency to form an association. "This segment arrangement is not given. However, block copolymers with ester and Amide structures which have the composition according to the invention, compostable. However, their synthesis is generally significantly more complex.

The monomers used to prepare the copolymers b2) can come from the following groups:
Dialcohols such as ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,6-hexanediol, diethylene glycol and others, and / or dicarboxylic acids such as oxalic acid, succinic acid, adipic acid and others also in the form of their respective esters (methyl, ethyl, etc .) and / or hydroxycarboxylic acids and lactones such as caprolactone and others and / or amino alcohols such as ethanolamine, propanolamine etc. and / or cyclic lactams such as epsilon-caprolactam or laurolactam etc. and / or omega-aminocarboxylic acid such as aminocaproic acid etc. and / or mixtures ( 1: 1 salts) from dicarboxylic acid such as adipic acid, succinic acid etc. and diamines such as hexamethylene diamine, diaminobutane etc.

Likewise, both hydroxyl- or acid-terminated polyesters can also be used Molecular weights between 200 and 10,000 as an ester-forming component be used. The synthesis can be carried out using either the polyamide method stoichiometric mixing of the starting components, if necessary Add water and then remove water from the Reaction mixture as well as by the polyester method by adding a Excess diol with esterification of the acid groups and subsequent ones Transesterification or transamidation of these esters take place. In this second case In addition to water, the excess glycol is distilled off again.  

Of the monomers mentioned are preferred for the purposes of the invention Manufacture of polyester amides for biodegradable wall coverings Caprolactam, diol and dicarboxylic acid in the desired stoichiometry mixed.

The polyester amides b2) which can be used can also contain 0.1 to 5% by weight, preferably contain 0.1 to 2% by weight of branching agents. These branchers can e.g. B. trifunctional alcohols such as trimethylolpropane or glycerol, tetrafunctional alcohols such as pentaerythritol, trifunctional carboxylic acids such as Citric acid. The branching agents increase the melt viscosity of the Polyester amides according to the invention to the extent that, among other things Extrusion blow molding of these polymers becomes possible. Biodegradation these materials are not hindered.

Aliphatic polyesteramides b2) which can be used in the context of the invention have ester fractions between 35 and 80% by weight, contain aliphatic dialcohols with a chain length of C ₂ to C ₁₂ , preferably C ₂ to C ₅ , aliphatic dicarboxylic acids or their esters with a chain length of C. ₂ to C ₁₂ , preferably C ₂ to C ₆ , omega-aminocarboxylic acids with a chain length of C ₁ to C ₁₂ , preferably C ₄ to C ₆ , or cyclic lactams with a ring size of C ₅ to C ₁₂ , preferably C ₅ to C ₁₁ , or a 1: 1 salt of aliphatic dicarboxylic acid and aliphatic diamine with a chain length of C ₄ to C ₁₂ , preferably C ₄ to C ₆ , with optionally 0.01 to 5% by weight, preferably 0.01 to 3% by weight of branching. They have a melting point of more than 75 ° C and a molecular weight MW <30,000.

The aliphatic suitable for film production or as layer b2) Polyester amides can be used as additives from 0 to 50 wt .-% inorganic or organic filler or reinforcing materials, mineral fillers, UV stabilizers, antioxidants, pigments, dyes, nucleating agents,  Crystallization accelerators or retarders, flow aids, lubricants, Mold release agents, flame retardants and modified or non-modified decorated rubbers included. In the case of the additional and Auxiliaries to ensure that the compostability of the polyester amides in is not significantly adversely affected.

b3) polyester

In addition to these polyester amides, biodegradable goods (film or Coating) especially polyester, especially biodegradable Copolyester and their blends with starch are suitable. The basic structure of Biodegradable polyesters form copolyesters from known per se aliphatic diols, aliphatic and aromatic dicarboxylic acids. All Monomers used are biodegradable and ecotoxicological harmless. The statistical integration of the aromatic dicarboxylic acid units, since in the presence of longer aromatic blocks are difficult to achieve complete degradability becomes.

The basic structure of the copolyester systems valuable according to the invention is based on precursors to those on the α, ω-diol side u. a. 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol and on the part of Dicarboxylic acids in the aliphatic compounds adipic acid, sebacic acid etc. and in the aromatic compounds u. a. Belong to terephthalic acid.

Additional ones are important for practical application Modifications to this basic structure. This will improve Obtained copolyester. It can, for example, by incorporating hydrophilic Components, branching monomers and / or of Connections that lead to a chain extension and thus increase the Molecular weight, target biodegradable copolyesters for  Film applications are obtained that are elastic and high Have tensile strength and elongation.

For the statistical copolymer systems, there exists with regard to Composition of the monomer shares an optimal range between Degradability on the one hand and material properties on the other hand, which at aromatic acid components (based on the total acid component) of approx. 35-55 mol% is. In particular, copolymers of 1,4-butanediol, adipic acid and terephthalic acid show very good application properties (e.g. Melting points up to 150 ° C, tensile strength and elongation at break comparable to Polyethylene). The copolyesters can be made using conventional Polycondensation techniques are made. You can usually be with edit and edit conventional techniques. In addition to a good one Biodegradability, whether in an earth digging test according to DIN 53 739 or in the compost simulation test, it should be further emphasized that the Copolyesters open up the favorable possibility of degradability in certain Control borders.

Depending on the composition of the copolyesters, however, certain Limit different degradation speeds in natural media such as Soil or compost.

Copolyester and starch blends are also suitable. From native wheat, Corn or potato starch and a plasticizer like glycerin are all in one Extruder first made thermoplastic starch and then "on line" with processed the copolyester into a blend. Important parameters are a complete digestion of the native starch in the extruder (i.e. destruction of the crystalline superstructures in the starch grain, but none Molecular weight reduction) and the setting of the desired Blend morphology. The copolyester is present as a continuous phase, in which the thermoplastic starch is finely dispersed. Through this  Targeted hydrophobization of the starch is used for many areas of application necessary water resistance of the starch blend achieved. Made from it Coatings or foils show good mechanical properties such as high ones Tear strength and elongation are antistatic, permeable to oxygen and Water vapor, printable, sealable and are characterized by a extremely pleasant grip.

b4) polylactide (PLA)

Within the scope of the invention, polylactides are also suitable as coating layer b) Composite according to the invention suitable and preferred. Are polylactides (PLA's) by polymerization of lactic acid, which can be obtained, for example, by Fermentation of carbohydrates with lactobacillus is accessible. The Polymerization to polylactide takes place via an intermediate cyclic dimers. For example, polylactides have an ECO-PLA input in found the state of the art. Polylactides are renewable Bioplastics, which are biodegradable and compostable. Made of polylactide fibers, foils and moldings can be produced, the mechanical properties often by copolymerization with glycolides or ε-caprolactone can be improved.

In the context of the invention, this is particularly preferred under the name ®Lacea polylactide available from Mitsui Toatsu. ®LACEA polymers are based on renewable raw materials, are versatile and processable extremely biodegradable. Of particular interest are a. obtainable by a new method by direct polycondensation higher molecular weight PLAs. In contrast to PLA's, which are based on conventional ones Obtained by ring opening polymerization, have by Direct condensation products polymerized excellent mechanical Properties, especially for processing as films or molding compounds.  

Products with average molecular weights M _w between 1 × 10 ⁶ and 1 × 10 ⁷ give particularly favorable properties. Above all, M _w ranges between 2 and 5 × 10 ⁶ are preferred. In addition, it has been shown that copolymers of D-lactic acid and L-lactic acid have particularly useful properties. After a copolymer obtainable by direct condensation of L-lactic acid and D-lactic acid contains the L- and D-lactic acid units in random distribution - in contrast to ring opening polymerization - the biodegradability of copolymer PLAs is also very excellent.

b5) Strengths

According to the invention, starches are also a preferred plastic material for the Coating layer b) of the wall cladding composite. Strength consists of two Macromolecules, amylose (linear starch chain) and amylopectin (branched Starch chain), which in its natural composition for the production of biodegradable plastic material are suitable.

Starches based on renewable raw materials are particularly suitable thermoplastic starches. The process of making thermoplastic Strengths are based on compounding extrusion technology and Reaction compounding extrusion. This is the dried agricultural product Starch by compounding in the extruder using a swelling or Plasticizer (e.g. glycerin, sorbitol) without adding water in thermoplastic starch converted. By melting one Temperature of 100-300 ° C, preferably 120-220 ° C becomes permanent Rearrangement of the molecular structure of starch achieved. Thermoplastic In contrast to destructured starch, starches do not recrystallize. Destructured starch occurs if starch has a moisture content of more than 5% is plasticized under pressure and temperature. Hence the  commercially available native starch containing 14% water, potato starch even 18% Contains water, first dried by degassing.

The crystalline fraction of thermoplastic starch is generally less than 5% and does not increase due to storage. The crystalline part destructurized starch is also low after melting, but increases with time. This characteristic is reflected in the Glass transition point reflected that at thermoplastic starch at -40 ° C remains while comparatively strengthened again with destructured strength rises above 0 ° C. For these reasons, destructive strength and Materials based on which gradually become brittle during storage. Therefore exist serious differences in plastics processing technology between the two types of strength.

Polymer mixtures with other degradable ones can also be used Polymer components based on the thermoplastic starches for manufacturing the coating layer b) are used. Known degradable Polymer components are, for example, aliphatic polyesters include, for example, polylactic acid, polycaprolactone and tailor-made copolyesters from aliphatic diols and aliphatic and / or aromatic dicarboxylic acids, degradable polyester amides, Polyester urethanes, polyvinyl alcohols, cellulose esters or ethers, Polyethylene oxide polymers and mixtures thereof. Form these components with thermoplastic starch in anhydrous melt by ester reaction and / or as polymer combinations, new degradable materials that comply with DIN 54900 are compostable. Other additives are, for example, natural ones Aggregates and plasticizers such as glycerin and their derivatives as well hexavalent sugar alcohols, such as sorbitol and their derivatives.

In the production of the polymer mixtures, phase mediators for the Homogenization of the hydrophilic or polar starch phase and the  hydrophobic or non-polar polymer phase used. These phase brokers can either be added or in a preferred embodiment arise in situ. Block copolymers are used as phase mediators u. a. in WO 91/16375, EP 0 539 544, US 5 280 055 and EP 0 596 437 are described in detail.

The intermolecular compounding of these different polymers takes place under defined temperature and shear conditions by coupling the Phase interfaces, so that the distribution structure of the disperse phase at Processing is achieved.

In a preferred embodiment, the rearrangement of the Molecular structure of native starch in an optimal processing window (Temperature and shear conditions) by polymers described below are generated. There is therefore no need for the Manufacture of polymer blends based on thermoplastic starches based, not first the native starch with a plasticizer must be converted before the further polymer is added. In the polymer blend is melted in a dry and dry process Conditions by mixing native starch or derivatives thereof and Degradable hydrophobic polymer made with native starch too thermoplastic starch is converted.

Suitable hydrophobic, degradable polymers include without this should result in a restriction, aliphatic polyesters, Polyester copolymers, polyester amides, polyester urethanes and / or mixtures from that. Polyester copolymers and polyester amides are particularly suitable Mixtures of these. Through the intermolecular coupling of these polymers the starch phase and the homogeneous distribution of the polymer particles become the influenced physical properties. Especially the hydrophobic Properties of the starch plastics are significantly increased, the  Moisture resistance is improved and the embrittlement tendencies of the thermoplastic starch is significantly reduced.

Particularly suitable polymer mixtures for use in the wallpaper area Basis of the renewable raw material starch as well as manufacturing process and processing of films containing starch may include a. in the patents and Patent applications DE 43 17 696.8, DE 432 28 016.8, EP 0 479 964, EP-A-0 537 675, DE 43 17 692, EP 0 656 830, DE 196 16 500.8, EP 539 544, EP 542 155, PCT / EP 93/117 666, WO 95/04104, WO 96/19599, WO 96/31561, DE 196 24 641 discloses.

Particularly suitable thermoplastic starches are among the Product designation BIOFLEX® (foils based on thermoplastic starch) and BIOPLAST® (granules based on thermoplastic starch) from BIOTEC® available. These polymers are made from plant starch and other fully biodegradable additives. You can on are processed conventionally and are thanks to their composition extremely biodegradable.

The granulate, which can be obtained by the process described above, can be used for the production of wallpapers with a coating based on the previously described bioplastics from modified thermoplastic starch. In a second step, this granulate is processed into a blown or flat film using a process known in the plastics processing industry. In a preferred embodiment, the film is produced directly from the raw materials in a continuous, one-step process (see DE 42 28 016.8). The starch film is connected to the wallpaper paper in a sealing process, in each case by using the paper used in a weight fraction of 80-130 g / m ² and the starch film also in a weight fraction of 80-130 g / m ² from the roll through a laminating system with heated rollers a temperature of 40-150 ° C, preferably at about 70 ° C, and then made according to the known methods to a relief wallpaper.

The printing layer c)

A composite wall covering according to the invention can optionally one or have several printing layers c). This is to achieve the overall concept according to the invention prefers the choice of the Printing colors used so that it is biological degradable color pigments that are not built into the body, so are also non-toxic. In a preferred modification of the invention Wall covering is layer c) a print that predominantly has anionic gravure color pigments.

If colors or pigments are used for aesthetic or optical reasons should be that the requirement is not fully biodegradable suffice, this is not particularly harmful since the share of Color pigments based on the total mass of a wall covering composite is negligible. In particular, is in such a case assume that the proportion by weight of the color pigments in the total weight of the Composite wallcovering is <1% by weight.

The adhesive or bonding agent layer d)

In a further expedient embodiment, between layers a) and b) of the composite according to the invention a layer d) is arranged, wherein it is layer d) around a biodegradable adhesive based on Polyurethane prepolymer d1) or an adhesion promoter based on Polyether epoxides d2). The glue or adhesion promoter is used  in particular to improve the bond between layers a) and b), if the adhesion between the two layers a) and b) due to the Manufacturing process is not sufficient in itself from the outset.

d1) Polyurethane prepolymer adhesive

In the context of the invention, a polyurethane prepolymer is used as the adhesive Isocyanate end groups based on different diisocyanates Reactivity can be used. Such compounds with isocyanate groups have been Known for a long time and can with suitable hardeners - mostly multi-functional Alcohols - easily converted to high polymers. So is their use as a sealant, as a varnish or adhesive known. As Adhesives are particularly suitable in the context of the invention Polyurethane prepolymers with different terminal isocyanate groups Reactivity and polyfunctional alcohols, which are obtainable in that in a first reaction step with 2,4-tolylene diisocyanate polyfunctional alcohols in the ratio OH: NCO between 4 and 0.55 implemented and after reaction of virtually all fast NCO groups with one Part of the OH groups present in a second reaction step Comparison to the less reactive NCO groups of 2,4-tolylene diisocyanate from reaction step one more reactive diisocyanate equimolar or in excess, based on OH groups still free, is added, if desired customary Catalysts and / or elevated temperatures are used.

In the first stage of this process according to that of the invention Applicable glue is available, can be a variety of multifunctional Alcohols are used. Aliphatic are suitable at this stage Alcohols with 2 to 4 hydroxyl groups per molecule. Although primary like secondary alcohols can also be used are the secondary ones prefers. In particular, the reaction products can be of low molecular weight polyfunctional alcohols with alkylene oxides with up to 4 carbon atoms  will. For example, the reaction products of ethylene are suitable glycol, propylene glycol, from the isomeric butane or hexane with Ethylene oxide, propylene oxide and / or butene oxide. Furthermore, the Reaction products of trifunctional alcohols such as glycerin, trimethylolethane and / or trimethylpropane or higher functional alcohols such as, for example Pentaerythritol or sugar alcohols used with the alkene oxides mentioned will. Polyether polyols with a molecular weight are particularly suitable from 100 to 10,000, preferably 1,000 to 5,000 and in particular Polypropylene glycol.

Depending on the desired molecular weight, addition products of a few moles of ethylene oxide and / or propylene oxide per mole or more than 100 moles of ethylene oxide and / or propylene oxide per mole of low molecular weight polyfunctional alcohols are used. Other polyether polyols are by condensation of, for example, glycerol or pentaerythritol under Dehydration can be produced. Polyols commonly used in polyurethane chemistry continue to arise through the polymerization of tetrahydrofuran. Among the The polyether polyols mentioned are the reaction products of polyfunctional len low molecular weight alcohols such as propylene oxide under conditions which are at least partially secondary hydroxyl groups, especially suitable. Other suitable polyether polyols are e.g. B. in DE 25 59 759 described.

Furthermore, can be used in the context of the invention for the production of usable adhesive polyester polyols with a molecular weight of 200 to 10,000. According to a first embodiment, polyester polyols can be used be by the implementation of low molecular weight alcohols, in particular of ethylene glycol, propylene glycol, glycerin or trimethylolpropane with 1 to 50 moles of caprolactone are formed. Other suitable polyester polyols are Polycondensation can be produced. So difunctional and / or trifunctional Alcohols with a deficit of dicarboxylic acids and / or tricarboxylic acids  or their reactive derivatives are condensed to polyester polyols.

Suitable dicarboxylic acids here are succinic acid and its higher homologues with up to 12 carbon atoms, also unsaturated dicarboxylic acids such as maleic acid or fumaric acid and aromatic dicarboxylic acids, especially the isomers Phthalic acids. As tricarboxylic acids are citric acid or trimellitic acid suitable. Polyester polyols made of are particularly suitable for the purposes of the invention the dicarboxylic acids mentioned and Glycerin, which have a residual content of secondary OH groups.

To reaction products of 2,4-tolylene diisocyanate with multifunctional Obtaining alcohols, which according to the invention in the second reaction stage can be used as a solvent or reactive diluent, it is important a certain ratio between hydroxyl groups and Comply with isocyanate groups. This is how suitable products are created that follow Abreaction of the more reactive NCO groups still contain OH groups, if the number of OH groups divided by the number of isocyanate groups is set between 4 and 0.55, preferably between 1 and 0.6.

In the second stage for the production of the adhesive in the OH and NCO-functional reaction products of the first reaction stage as Reactive diluents symmetrical, dicyclic diisocyanates with the rest OH groups reacted. The amount of dicyclic diisocyanates, based on the total amount of diisocyanates in stages 1 and 2, is 5 to 80% by weight, preferably 5 to 60% by weight and in particular 10 to 40% by weight. For the second stage reaction, the molar ratio is OH groups: NCO groups, expressed as the quotient of the OH groups divided by isocyanate groups, preferably 0.5 to 1.0, in particular 0.6 to 0.8, based on remaining OH groups.  

When choosing dicyclic diisocyanates, it is important that the reactivity their isocyanate groups compared to hydroxyl groups is higher than that of terminal isocyanate groups of the reactive diluent. Thus, in the first place Line the diaryl diisocyanates suitable. 4,4'-Di are preferred phenylmethane diisocyanate and / or substituted 4,4'-diphenylmethane diisocyanate.

The preferred products available at temperatures between 40 and 100 ° C have a substantially reduced proportion of free, monomeric Toluene diisocyanate but also on free, monomeric dicyclic diisocyanates on. Thus, when the prepolymers are used over a large area, the Temperatures about 80 to 100 ° C so no annoyance from volatile Toluene diisocyanate. Another advantage of the process products is theirs relatively low viscosity that they z. B. for solvent-free adhesive makes turns suitable.

Such prepolymers were known to be in bulk or as Solution in organic solvents for bonding plastics, are particularly suitable for laminating plastic films, customary Harder, such as polyfunctional higher molecular alcohols are added can (2 component systems) or that surfaces with defined Moisture content can be glued directly with such available products can, where film composites with high processing reliability Heat sealing can be obtained. Given the otherwise, it doesn't have to satisfactory biodegradability of polyurethane prepolymer adhesives all the more surprising that the polyurethane prepolymer adhesive one multilayer film composite according to the invention is just as good and have excellent biodegradability and compostability, such as this for the biodegradable goods consisting of polyester amides and / or polyesters and the barrier layer made of polyvinyl alcohol is the case.  

d2) Polyether epoxy adhesion promoter layer

In a special embodiment according to the invention, the multilayer biodegradable wallcovering composite in that the paper wallpaper and a film from one of the biodegradable Plastic materials, preferably made of polyester and / or polyester amide With the help of an adhesion promoter based on polyether epoxides coextruded are. Although the adhesion between layers a) and b) for many Applications may be sufficient, this can be done by a corresponding adhesion promoter can be increased significantly. To the usable Adhesion promoters include those based on polyether epoxides. All materials familiar to the expert come on the basis of Polyether epoxides in question, provided they meet the criterion of biological Meet degradability.

The invention also relates to a method for producing fully compostable multi-layer wallcovering composite of Art.

In the process of producing fully compostable multilayer Composite wallcoverings is at least one according to the invention Wallpaper layer provided on paper, on which one or more Coating layers made from biodegradable, thermoplastically processable Polymers are applied, the plastic layers optionally printed again.

The layer made of biodegradable, thermoplastically processable polymers can in different ways on the paper wallpaper layer a) be applied. So it is possible, for example, on the plastic suitable way to spray onto the paper wallpaper layer.  

In an expedient modification, however, it is far preferred that Coating layer b) in the form of a film on the paper wallpaper layer a) bring.

In a particularly advantageous modification of this method, the Coating layer b) as a film with an adhesive based on a Laminated polyurethane prepolymers on the paper wallpaper layer a). Hereby succeeds in combining a very simple production with a product, which all put on a standard composite wall covering It can satisfy a requirement just as much as it can a complete one biodegradability, especially rot and compostability having.

In a modification of the manufacturing process according to the invention, it can also be preferred that the film without adhesive only by heat sealing the paper base is applied. This very simple method of application is suitable for all wallpaper combinations, to which no special requirements regarding liability between the individual layers.

Finally, the coating layer b) can also pass through with the wallpaper layer a) Coextrusion can be connected. Here is the coextrusion of paper and Plastic layers familiar to the expert per se and without further problems possible. However, due to the materials used the coextrusion per se leads to only a slight adhesion between the individual involved locations, so it is particularly useful in modified Modification of the method of the invention possible, films made of biological degradable plastic, especially polyester and / or polyester amide with the paper base layer with the help of an adhesion promoter based to coextrude polyether epoxides. Here the adhesion promoter is only in very small amounts are used and beyond  Polyether epoxy compounds biodegradable, rot and compostable, so that either a small proportion of polyether epoxy is ecologically harmless or is easily compostable and rotten.

The following examples serve to explain the subject in detail the invention. First, various embodiments Compostable wallpaper composites according to the invention with reference to the attached figures described in more detail.

The figures show:

Fig. 1 shows a schematic cross section through a first embodiment of a compostable composite wall covering according to the invention, wherein the closely spaced se individual layers are shown at a certain distance to improve clarity;

Fig. 2 is a schematic cross section through a second embodiment of the compostable composite wall covering according to the invention, being shown here for simplicity of illustration to improve the clarity the fixedly-connected with each other in the finished wallpaper individual layers and layers spaced from one another; and

. 1 is plotted composite of paper and strength against time in days: shows a graph in which the rates of degradation of paper strength and a ≈1. 3

In Fig. 1, reference numeral 1 according to the invention refers to a fully compostable multilayer composite wall covering. This has a base paper layer 2 of preferably wood-containing paper as the base layer. In the example shown, the side near the wall is understood to mean the side of the base paper layer 2 that is not facing the composite. On the visible side, a plastic layer 3 made of biodegradable goods is shown in direct contact with the base paper layer 2 . The biodegradable goods (layer 3 ) are connected to the base paper layer 2 in the example shown by heat sealing. The layer made of biodegradable goods is, for example, the polyester amide BAK 1095 from Bayer, the polylactide ®Lacea from Mitsui Toatsu or a starch material ®Bioflex from Biotec. Furthermore, a color layer 4 can be seen in FIG. 1, which as a printing layer on the visible side of the composite 1 is in direct contact with the coating layer 3 . Together, base paper layer 2 , plastic layer 3 and printing layer 4 form an embodiment of the biodegradable wallpaper composite 1 according to the invention.

A modification of this first embodiment according to the invention is shown in FIG. 2. Here, too, the reference number 1 designates a biodegradable wallpaper composite, which, however, has a layer 5 in addition to the base paper layer 2 , the plastic coating 3 and the printing 4 . Layer 5 is an adhesive material based on polyurethane prepolymer, which serves to laminate the plastic film layer 3 onto the paper base layer 2 .

Test method

The biodegradability property of the invention is defined as follows:
In a modified storm test (OEDC guideline 301 B), the polymers, foils, layers and composites to be tested are examined for their degradability. The test duration is 28 days. The breakdown is measured according to predetermined time periods on the basis of the amount of CO ₂ formed.

rehearse

The degradability of the following substances was examined:
A1: paper (Kyro PVC C90 g / m ² from METSÄ-SERLA),
A2: starch (Bioplast GF 102/14 from BIOTEC),
A3: ≈1: 1 composite of paper and starch.

The composite was made by coextruding the paper with the starch. For this purpose, a Raiffenhäuser chill-roll system is used, which has a 50 mm Has extruder with a 3-zone screw. The speed is 56 rpm, the web speed 11 m / min and the roller temperature 40 ° C, so that the Starch layer measures about 100 microns.

The concentration of the substances was chosen according to their carbon content. This was determined by elemental analysis. The carbon content of the test substances is:
Paper (A1): 39%, correspondingly 30 mg / l, a total of 90 mg are used as test substance A1 (= 11.7 mg carbon / l);
Starch (A2): 54.4%, correspondingly 20 mg / l, a total of 60 mg is used as test substance A2 (= 10.88 mg carbon / l);
Paper-starch composite: 49%, correspondingly 25 mg / l, a total of 75 mg is used as test substance A3 (= 12.25 mg carbon / l).

The test substances are pulverized in preparation for the test and homogenized. The crushing takes place in a low temperature blow rotor mill using liquid nitrogen.

In addition, a reference test is carried out to check the test system as well carried out a control test. In the reference experiment, 35 mg / l (corresponds to 10.2 mg carbon / l) sodium acetate (sodium acetate puriss., Fluka, Batch 346574/1 1095) used as test substance in the control test only becomes a mineral nutrient solution according to OECD 301 B and the inoculum Water added.

Degradability tests

In a 5,000 ml brown glass bottle, 2970 ml of a mineral nutrient solution according to OECD 301 B are 30 ml of an aqueous mixture of microorganisms (inoculum: 4.2 × 10 ⁴ nucleating colonies per ml), which was obtained from a non-adapted activated sludge (sewage treatment plant Hildesheim ). The concentration of colony-forming microorganisms is 4.2 × 10 ² per ml in the resulting solution.

The vessel is then flushed with CO ₂ -free air for 24 h. Then 3 gas wash bottles are connected to the air outlets of the incubation vessels and the respective test substance (A1, A2, A3 or sodium acetate) is added to the incubation vessels. The following is incubated at 22 ± 2 ° C, the system being connected to CO ₂ -free air. The amount of CO ₂ formed is determined on the days given in Table 1, 2, 3 and 4 respectively. After 28 days, 1 ml of concentrated HCl is added to the mixture. It is then ventilated for a further 24 h in order to finally determine the amount of CO ₂ released.

The pH of the solution is measured at the beginning and end of each experiment certainly. In the control experiments it was 7.59 and 7.56 in which Reference test (sodium acetate) 7.90 and in the test tests (A1, A2 or A3) 7.53 ± 0.05 (pH meter: Corning pH 240).

The determination of the amount of CO ₂ by titration after complete absorption of the released CO ₂ in basic Ba (OH) ₂ solution. The back-titration of the remaining Ba (OH) ₂ with 0.05 N hydrochloric acid is carried out three times in the first 10 days, then twice a week. The difference between the initial value and the value at the time of determination gives the amount of carbon dioxide formed. For the calculation of the gross CO ₂ production, the reduced titration of 1 ml of a 0.05 N HCl solution corresponds to 1.1 mg CO ₂ . It is titrated to the neutral point in each case (pH meter: Corning pH 240). When calculating the net CO ₂ production, the CO ₂ production of control approaches is taken into account.

The tests with the test substances A1, A2 and A3 as well as the control test were carried out twice.

evaluation

The theoretical CO ₂ production (ThCO ₂ ) of the test substance (sodium acetate) is calculated from equation (1):

In cases where the molecular weight cannot be determined, the theoretical CO ₂ production (ThCO ₂ ) is determined by measuring the carbon content of the test substance (substances A1, A2 or A3):

Biodegradation is calculated from the ratio of theoretical CO ₂ production to net CO ₂ production according to equation (2):

Results

The measurement results are shown individually in Tables 1, 2, 3 and 4, while in FIG. 3 the degradation rates of paper, starch and a ≈1: 1 composite of paper and starch are plotted against the time in days.

Table 1

CO ₂ production and biodegradation for all times of determination in the control and reference approaches

Table 2

CO ₂ production and biodegradation for all times in which the paper degradation was tested

Table 3

CO ₂ production and biodegradation for all times of determination in the approaches in which the starch degradation was tested

Table 4

CO ₂ production and biodegradation at all times when the degradation of the starch-paper composite was tested

The biodegradability of the test substances is graphically shown in Figure (3) shown. It turns out that the combination of ≈1: 1 starch and paper is somewhat more biodegradable than pure starch. This association therefore surprisingly composts much better than pure paper.

Claims (13)

1. Fully compostable multi-layer wallcovering composite comprising from the wall to the visible side

• a) at least one layer of wallpaper made of paper,
• b) then a coating layer of thermoplastically processable polymers and optionally on b),
• c) one or more printing layers,
  characterized by
  that the coating layer consists of a biodegradable material which, in the degradation test according to OECD 301 B, produces a degradation of <25% after 28 days.

2. Wall covering according to claim 1, characterized in that the Wallpaper layer a) is wood-containing base paper. 3. Wall covering according to claim 1 or 2, characterized in that the coating layer b) biodegradable polycaprolactone, Is polyester, polyester amide, polylactide and / or starch. 4. Wall covering according to one or more of the preceding Claims, characterized in that the printing layers predominantly have anionic rotogravure color pigments. 5. Wall covering according to one or more of the preceding Claims, characterized in that between layers a) and b) a layer d) is arranged, where d) is a biodegradable adhesive based on polyurethane prepolymer or an adhesion promoter based  of polyether epoxides. 6. Wallcovering according to one or more of the preceding Claims, characterized in that the multilayer composite in modified storm test rots in a shorter time than that on slowest compostable single layer. 7. Process for the production of fully compostable multilayer Composite wallcoverings according to claims 1 to 6, in which at least one layer of wallpaper made of paper is provided, on which one or more coating layers made of biodegradable Polymers are applied, which are optionally printed. 8. The method according to claim 7, characterized in that the Coating layer b) is applied as a film. 9. The method according to claim 8, characterized in that the film with an adhesive based on a polyurethane prepolymer is laminated on. 10. The method according to claim 8, characterized in that the film is applied by heat sealing. 11. The method according to claim 8, characterized in that the Coating layer b) and the wallpaper layer a) were coextruded. 12. The method according to claim 7, characterized in that the Coating layer b) is applied by spraying layer a). 13. The method according to claim 11, characterized in that the layers a) and b) using an adhesion promoter based on Polyether epoxides are co-extruded.