DE19911209A1 - Semi-finished products made of biodegradable polymers with improved hydrolysis stability and stress crack resistance - Google Patents

Abstract

The invention relates to semi-finished products consisting of biodegradable, compostable polymers with improved hydrolytic stability and stress-cracking resistance, and to the use thereof. Susceptibility in relation to hydrolysis is reduced by coating the semi-finished product completely or partially on at least one surface with cellulose esters.

Description

The present invention relates to semi-finished products made from biodegradable polymers with improved hydrolysis stability and stress crack resistance and their ver turn.

It is known that certain polymeric materials undergo biodegradation may be subject to. Mainly materials that are made of natural occurring polymers can be obtained directly or after modification for example polyhydroxyalkanoates such as polyhydroxybutyrate, plastic celluloses, Cellulose esters, cellulose ether esters, plastic starches, chitosan and pullulan. A targeted variation of the polymer composition or the structures, as of side of the polymer application is desirable because of the natural Synthesis process is difficult and often only possible to a very limited extent. Among the Terms "biodegradable and compostable polymers or semi-finished products" goods are understood in the sense of this invention, which according to the test get the "biodegradability" tested according to DIN V 54 900 from 1998.

However, many of the synthetic polymers are not affected by microorganisms or attacked very slowly. Mainly synthetic polymers that Heteroatoms contained in the main chain are said to be potentially biodegradable viewed. Polyesters represent an important class within these materials Synthetic raw materials that contain only aliphatic monomers have a relatively good biodegradability due to their material properties can only be used to a very limited extent; see. Witt et al. in Macrom. Chem. Phys., 195 (1994) pp. 793-802. Aromatic polyesters, on the other hand, show good ones Material properties significantly deteriorated, biodegradability.  

From DE-A-44 32 161 and EP-A-641 817 there have been several recently Biodegradable polymers based on polyester or polyester amide are known been. These have the property that they are easy to process and thermoplastic on the other hand are biodegradable, d. H. their entire polymer chain from Microorganisms (bacteria and fungi) are broken down completely by enzymes is broken down to carbon dioxide, water and biomass, for example by action microorganisms, such as those found in compost, in a test according to the DIN V 54 900. These biodegradable materials can due to the thermoplastic behavior to semi-finished products such. B. Cast or blown films be prepared. Nevertheless, the use of these semi-finished products is very limited, because the bio Logically degradable polymers are sometimes susceptible to hydrolysis and show stress cracking. This vulnerability can also be felt in a express many applications for rapid biodegradation. Especially with out Semi-finished products in the form of foils are manufactured in the field of Waste disposal of organic substances should be used, hydrolysis stability and resistance to stress cracking from 1 to 3 weeks, preferably 1 to 2 Weeks can be reached to allow easy transportation. In the later composting of the organic waste then occurs through the Hydrolysis and crack formation of the polymers at the same time break the foil bag, and the foil pouch becomes biological together with the contents of the foil pouch mined and composted.

The object of the present invention was therefore to produce semi-finished products from biological buildable polymers, preferably produced by extrusion or injection molding Moldings and in particular films with improved hydrolysis resistance and To provide stress crack resistance. The decomposition becomes hydrolysis understood by aqueous media, possibly by additional components can also have an acidic or alkaline pH. The term Stress cracking is described in the literature (E. J. Kramer, Environmental Cracking of Polymers, in Developments in Polymer Fracture-1, Edited by E. H. Andrews, Science Publishers LTD London, 55-120 (1979).  

Surprisingly, it was found that a coating, in particular a printing or coating of the semi-finished products made of biodegradable polymers with at least one cellulose ester with the addition of suitable plasticizers or plasticizer mixtures, as described, for example, in Kraus, Handbook of Nitro Cellulose Varnishes, Part 3, Plasticizers, 1961, West Berlin publishing company Heenemann KG, pages 394-448 is described, optionally also with the addition of conventional coating resins, waxes and additives, the hydrolysis stability and stress crack resistance of the semi-finished products from biodegradable polymers such. B. extended to 4 to 8 times. The application amount of the coating (paint application) should preferably be in the range from 1 to 15 g / m ² , in particular from 1 to 10 g / m ^2, on the surface of the semi-finished product. An increase in the application quantity is associated with an extension of the hydrolysis stability and stress crack resistance. The surface coating with cellulose esters delays the hydrolytic degradation and causes hydrophobicization of the coated surface of the semi-finished product. Since, as a rule, every biodegradation is also associated with hydrolysis of the material, the coating can also delay or control the biodegradation.

It is also achieved by the coating that the diffusion of the permeating surrounding medium into the structure of the molded body under tension occurs so slowly that a failure of the molded body due to chain break when not prevented, so it is delayed.

A corresponding control can also be achieved in that a semi-finished product from a biodegradable polymer or mixtures of biodegradable Polymers completely or only partially coated with cellulose esters, esp special printed or varnished.

The invention relates to semi-finished products, preferably by extrusion or Injection molded articles or in particular films, from a biological  degradable polymer or a mixture of biodegradable polymers that fully or partially with cellulose esters on at least one surface layers, in particular printed or painted, in a preferred form the coated, printed or painted surface to the hydrolyzing medium is exposed.

The ones used for the coating are in a particularly preferred form Cellulose esters are also biodegradable and compostable.

According to the invention, the following are preferably used as cellulose esters: cellulose acetate, cellulose acetobutyrate and propionate and particularly preferably cellulose nitrate (nitrocellulose with an N ₂ content ≦ 12.6%).

The cellulose esters are available in different viscosity grades, and the Selection of the appropriate viscosity level depends on the processing conditions from.

The cellulose esters can also be in the plasticized form (e.g. Nitrocellulose chips) are used. Plasticizers are used as plasticizers Resins or polymeric plasticizers understood.

In the preferred embodiment of painting the semi-finished product with organic solvent-based cellulose ester paints, consisting of the Cellulose esters as binders and suitable plasticizers can also be used customary coating resins, such as preferably alkyd resins, ketone resins, urea resins, Melamine formaldehyde resins, polyurethane resins or acrylate polymers in quantities up to 30% by weight, preferably up to 25% by weight (based on the Solids content of the paints) are added.

Typical solvents for such cellulose ester paints are, in particular, acetates, Ketones, possibly with the addition of alcohols and aromatics (see Kraus: Hand  book of nitrocellulose varnishes, part 1, solvent, 1955, Wilhelm Pansegrau Ver , Dept. of the Western Berlin Publishing Company Heenemann KG).

The following are suitable as biodegradable polymers, from which semifinished products are manufactured and then coated, in particular printed or painted, with cellulose esters: biodegradable aliphatic or partially aromatic polyesters in which the aromatic acids have a proportion of not more than 60% by weight, refer to all acids, make up, preferably formed from

• a) aliphatic bifunctional alcohols, preferably linear C ₂ - to C ₁₀ -di alcohols such as in particular ethanediol, hexanediol or very particularly preferably butanediol and / or cycloaliphatic bifunctional alcohols, preferably having 5 or 6 carbon atoms in the cycloaliphatic ring, such as in particular special Cyclohexanedimethanol, and / or partially or completely instead of the diols, monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights up to 4000, preferably up to 1000, and optionally small amounts of branched bifunctional alcohols, preferably C ₃ -C ₁₂ -Alkyldiolen, in particular special neopentylglycol, and in addition, if necessary, small amounts of higher-functional alcohols such as preferably 1,2,3-propanetriol or trimethylolpropane as an alcohol-functionalized building block and from aliphatic bifunctional acids, preferably C ₂ -C ₁₂ -alkyldicarboxylic acids, particularly preferably succinic acid o adipic acid and optionally aromatic bifunctional acids such as preferably terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids, preferably trimellitic acid as an acid-functionalized building block or
• b) from acid and alcohol functionalized building blocks, preferably with 2 to 12 carbon atoms in the alkyl chain, preferably hydroxybutyric acid, hydroxy  valeric acid, lactic acid, or their derivatives, for example ε-capro lactone or dilactide,

or a mixture of several of the polyesters mentioned and / or one or several copolymers from building blocks a) and b).

Also suitable as biodegradable polymers are biodegradable, aliphatic or partially aromatic polyester urethanes derived from the above biodegradable aliphatic or partially aromatic polyesters, which, in addition to the esters formed preferably from building blocks a) and / or b), contain urethane groups, which were preferably formed out

• a) aliphatic and / or cycloaliphatic bifunctional or additionally optionally higher-functional isocyanates, preferably having 1 to 12 carbon atoms or 5 to 8 carbon atoms in the case of cycloaliphatic isocyanates, preferably tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, optionally additionally with linear and / or branched and / or cycloaliphatic bifunctional and / or higher functional alcohols, preferably C ₃ -C ₁₂ alkyldi- or polyols or cyclo aliphatic alcohols having 5 to 8 C atoms, preferably ethanediol, hexanediol, butanediol, cyclohexanedimethanol, and / or optionally additionally with linear and / or branched and / or cycloaliphatic bifunctional and / or higher functional amines and / or amino alcohols with preferably 2 to 12 carbon atoms in the alkyl chain, preferably ethylenediamine or aminoethanol, and / or optionally further modified amines or alcohols, especially ethylenediamine inoethanesulfonic acid as free acid or as salt,

the ester fraction preferably formed from a) and b) at least 75% by weight, based on the total weight.  

Also suitable as biodegradable polymers are aliphatic or partially aromatic polyester carbonates derived from the above aliphatic or partially aromatic polyesters, which contain carbonate groups in addition to building blocks a) and / or b), which are preferably formed from:

• a) a carbonate portion, which is made from aromatic bifunctional phenols, before bisphenol-A, and carbonate donors, especially phosgene, or
  a carbonate portion which donates from aliphatic carbonic acid esters or their derivatives such as preferably chlorocarbonic acid esters or aliphatic car acids or their derivatives such as salts and carbonate, in particular phosgene, where

the ester fraction preferably formed from a) and / or b) be at least 70% by weight pulled to the total weight.

Particularly suitable as biodegradable polymers are aliphatic or partially aromatic polyester amides derived from the above aliphatic or partially aromatic polyesters, which contain amide groups in addition to the building blocks a) and / or b), which were preferably formed from

• a) aliphatic and / or cycloaliphatic bifunctional amines, preferably linear aliphatic C ₂ - to C ₁₀ -diamines, in particular isophoronediamine and very particularly preferably hexamethylenediamine, where these amines can optionally contain small amounts of branched bifunctional amines and / or higher-functional amines and from linear ones and / or cycloaliphatic bifunctional acids, preferably having 2 to 12 carbon atoms in the alkyl chain or C ₅ or C ₆ ring in the case of cycloaliphatic acids, preferably adipic acid, and optionally small amounts of branched bifunctional and / or optionally aroma tables bifunctional acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids, preferably with 2 to 10 carbon atoms, or
• b) acid- and amine-functionalized building blocks, preferably with 4 to 20 Carbon atoms in the cycloaliphatic chain, preferably ω-laurolactam, particularly preferably ε-caprolactam,

or a mixture of e) and f), the preferably of a) and / or b) Ester fraction formed at least 20 wt .-%, based on the total weight is preferably the ester fraction 20 to 80 wt .-%, and the proportion of the amide structures is 80 to 20 wt .-%.

In the polymers used to produce the semifinished products according to the invention can be both pure polymers and mixtures of different Act polymers, in the case of mixtures preferably polymers of only one of the aforementioned classes of compounds (polyester, polyester urethane, polyester carbonates, polyester amides) can be used. Poly are particularly preferred ester amides or mixtures of different polyester amides are used.

In a special embodiment of the invention, moreover for the mixtures of biodegradable polymers according to the invention, preferably one or more polymers from the aforementioned classes of compounds Polyesters, polyester urethanes, polyester carbonates or especially polyester amides with other biodegradable polymers, especially mixtures thermoplastic starch (e.g. MaterBi, Novamont) or polylactide (e.g. Eco Pla, Dow Cargill) or polycaprolactone (TONE, Union Carbide Corporation) be used.  

The polymers or used to produce the semi-finished products according to the invention Polymer mixtures can additionally contain customary additives and auxiliaries Amounts contain such as nucleating agents, stabilizers, neutralizers tion agents, lubricants, release agents, antiblocking agents and / or pigments.

The invention also relates to the use of the invention according to hydrolysis-stabilized, biodegradable and compostable Semi-finished products. The semi-finished product is in a particularly preferred form a single or multi-layer, biodegradable and compostable film, which are coated on one or both sides with cellulose esters, in particular printed or is painted. Semi-finished products in the form of such foils can advantageously be used in front treated or untreated as well as in printed, unprinted form for the Packaging in the fields of food and non-food or as hydrolysis-stabilized, single or multi-layer film in pretreated or unprepared treated form for protective and separating functions in connection with cosmetics and hygiene articles, for example for baby diapers or sanitary napkins or as refined film that is in pretreated or untreated as well as printed or unprinted form and provided with adhesive as a label or adhesive strip are used or as a hydrolysis-stabilized, single or multilayer film in pretreated or untreated form for greenhouse covers, mulch films or for lining plant growing boxes (e.g. for mushroom cultivation) in in the fields of horticulture or agriculture or refined into bags for storage and transportation of goods, for example organic waste, are used, whereby the control of the voltage possible through the application amount of the cellulose esters crack resistance and the hydrolytic and biodegradation rate is particularly advantageous.

The invention also relates to the particularly preferred use half of the invention coated on one or both sides with cellulose esters witness in the form of printed or varnished multilayer film for the manufacturer position of a bag that after decay by the biodegradation process  releases its content. The pouch can be glued as well as sealed the film are produced and both closed and an opening with have an appropriate lock or connector.

The following examples are intended to explain the invention in more detail without going into it restrict.

Examples of the film variants Slide 1

From the polyester amides A: BAK 403-004 built up from the monomers 23% by weight of adipic acid, 17% by weight of 1,4-butanediol, 60% by weight of ε-caprolactam (Bayer AG, MFR ≅ 7 g / 10 min at 190 ° C; 2.16 kg; measured according to DIN 53 735; Melting point 125 ° C, measured according to ISO 3146 / C2; Lubricant content 1% by weight, Antiblocking agent content 0.1% by weight) and B: BAK 404-002 constructed from the Monomers 20% by weight adipic acid, 15% by weight 1,3-butanediol, 65% by weight ε- Caprolactam (Bayer AG, MFI ≅ 10 g / 10 min at 190 ° C; 2.16 kg; measured after DIN 53 735; Melting point 140 ° C, measured according to ISO 3146 / C2; Content of Lubricant 0.4 wt .-%, content of antiblocking agent 0.1 wt .-%) were half produce coextruded blown films in a total thickness of 40 µm with an ABA Structure (10 µm / 20 µm / 10 µm) manufactured. The maximum extrusion temperature was 175 ° C. The melt was discharged through an annular nozzle and through air cooled down. The maximum nozzle temperature was 170 ° C.

Slide 2

Material A of film 1 became a single-layer blown film with a thickness of 40 µm. The maximum extrusion temperature was also 175 ° C. The melt was discharged through an annular die and cooled by air. The maximum nozzle temperature was 170 ° C.  

Examples of paint formulations

The following cellulose lacquers were produced by way of example:

The films were then printed and with the cellulose ester varnishes Recipes 1 to 5 fully coated on one side. After the paint has dried bags were made from the foils, with the painted surface on the inside. The bags made of unpainted film 1 and 2 served as comparative tests.

The bags were subjected to the following degradation conditions:

• - The bags were filled with fresh organic household waste (organic waste) filled. The waste was obtained from a composting plant and mixed to ensure that the fluctuations in the together wastage remained as low as possible. From each film variant and The paint formulation was filled with five bags each, including the statistical ones To minimize fluctuations.
• - The filled bags were at an average outside temperature of 13 ° C stored and examined daily for damage or feeding or degradation holes. The maximum durability was determined when the holes exceeded a size of 2 cm.

The lacquered foil bags, their product parameters and the dismantling time are summarized in the following table:

Claims (17)

1. Semi-finished products made of biodegradable and compostable polymers, characterized in that the semi-finished products have a coating of at least one cellulose ester and a suitable plasticizer or plasticizer mixture on at least one surface. 2. Semi-finished products made of biodegradable and compostable polymers according to claim 1, characterized in that the application amount of the coating device is 1 to 15 g / m ² , preferably 1 to 10 g / m ² . 3. Semi-finished products made from biodegradable and compostable polymers Claim 1 or 2, characterized in that it is in the semi-finished products to molded articles produced by extrusion or injection molding or in particular special is foils. 4. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to 3, characterized in that it is in the Semi-finished products around unstretched, monoaxially stretched or biaxially stretched, single or multilayer, pretreated or untreated blown films or Flat films. 5. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to 4, characterized in that the semi-finished products fully or only partially coated, especially printed or painted are. 6. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to S. characterized in that it is in the Cellulose esters around cellulose acetate, cellulose acetobutyrate or propionate and especially cellulose nitrate.   7. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to 6, characterized in that it is in the Coating around an organic solvent based Cellulose ester plasticizer or plasticizer mixture, the solvent and optionally customary coating resins in amounts of up to 30% by weight, preferably up to 25% by weight (based on the solids content of the Lackes) acts. 8. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to 7, characterized in that as biological degradable polymers biodegradable aliphatic polyester or partially aromatic polyester with a proportion of aromatic acids of not more than 60 wt .-%, based on all acids or from these polyesters derived functional derivatives in the form of polyester urethanes with a Ester content of at least 75 wt .-%, or polyester carbonates with a Ester content of at least 70 wt .-% or polyester amides with a Ester content of at least 20 wt .-% or their mixtures or Co polymers are used from the monomers forming these polymers. 9. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 8, characterized in that as biodegradable polymers polyester

• a) aliphatic bifunctional alcohols, preferably linear C ₂ - to C ₁₀ -dial alcohols, in particular ethanediol, hexanediol or very particularly preferably butanediol and / or cycloaliphatic bifunctional alcohols, preferably having 5 or 6 carbon atoms in the cycloaliphatic ring, such as in particular cyclohexanedimethanol, and / or partially or completely instead of the diols, monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights of up to 4,000, preferably up to 1,000, and possibly small amounts of branched bifunctional alcohols, preferably C ₃ -C ₂ alkyldiols , in particular neopentyglycol, and in addition, if appropriate, small amounts of higher-functionality alcohols, such as preferably 1,2,3-propanetriol or trimethylolpropane as an alcohol-functionalized building block, and of aliphatic bifunctional acids, preferably C ₂ -C ₁₂ -alkyl dicarboxylic acids, particularly preferably succinic acid or ad ipinic acid and optionally aromatic bifunctional acids such as preferably terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and, if appropriate, small amounts of higher-functional acids such as trimellitic acid as acid-functionalized building block or
• b) from acid- and alcohol-functionalized building blocks, preferably with 2 to 12 carbon atoms in the alkyl chain, preferably hydroxybutter acid, hydroxyvaleric acid, lactic acid, or their derivatives, for example ε-caprolactone or dilactide,
  or a mixture of several of the said polyesters and / or one or more copolymers from the building blocks a) and b).

10. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 8, characterized in that aliphatic or partially aromatic polyester urethanes with a urethane group are formed as biodegradable polymers

• a) aliphatic and / or cycloaliphatic bifunctional and additionally optionally higher functional isocyanates, preferably having 1 to 12 carbon atoms or 5 to 8 carbon atoms in the case of cycloaliphatic isocyanates, preferably tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, optionally additionally with linear ones and / or branched and / or cycloaliphatic bi-functional and / or higher-functional alcohols, preferably C ₃ -C ₁₂ -alkyl di- or polyols or cycloaliphatic alcohols having 5 to 8 C atoms, preferably ethanediol, hexanediol, butanediol, cyclohexanedimethanol, and / or optionally additionally with linear and / or branched and / or cycloaliphatic bifunctional and / or higher functional amines and / or amino alcohols with preferably 2 to 12 carbon atoms in the alkyl chain, preferably ethylenediamine or aminoethanol, and / or optionally further modified amines or alcohols such as especially ethylene di aminoethanesulfonic acid, used as a free acid or as a salt.

11. Semi-finished products made of biodegradable polymers according to one of claims 1 to 8, characterized in that as biodegradable polymers with aliphatic or aliphatic-aromatic polyester carbonates

• a) a carbonate fraction which is produced from aromatic bifunctional phenols, preferably bisphenol A, and carbonate donors, in particular phos gene, or
  a carbonate fraction which is prepared from aliphatic carbonic acid esters or their derivatives such as, for example, chlorocarbonic acid esters or aliphatic carboxylic acids or their derivatives such as, for example, salts and carbonate donors, for example phosgene.

12. Semi-finished products made of biodegradable polymers according to one of claims 1 to 8, characterized in that as biodegradable polymers formed from aliphatic or partially aromatic polyester amides with amide groups

• a) aliphatic and / or cycloaliphatic bifunctional amines, preferably linear aliphatic C ₂ - to C ₁₀ -diamines, in particular isophoronediamine and very particularly preferably hexamethylenediamine, where these amines can optionally contain small amounts of branched bifunctional amines and / or higher-functional amines, and from linear and / or cycloaliphatic bifunctional acids, preferably with 2 to 12 carbon atoms in the alkyl chain or C ₅ - or C ₆ ring in the case of cycloaliphatic acids, preferably adipic acid, and 5 to 8 carbon atoms, if appropriate, low Amounts of branched bifunctional and / or optionally aromatic bifunctional acids such as, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and, if appropriate, small amounts of higher-functional acids, preferably with 2 to 10 carbon atoms, or
• b) acid- and amine-functionalized building blocks, preferably with 4 to 20 C atoms in the cycloaliphatic chain, preferably ω-laurolactam, particularly preferably ε-caprolactam,

or a mixture of e) and f) can be used. 13. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to 8 or 12, characterized in that it is the biodegradable polymers both pure polymers and Mixtures of various of the polymers mentioned can act. 14. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to 8 or 12, characterized in that it is  the biodegradable polymers around polyester amide or a mixture is made of different polyester amides. 15. Semi-finished products made from biodegradable and compostable polymers one of claims 1 to 7, characterized in that it is in the biodegradable polymers is a mixture in which a Mix partners from polycaprolactone or polylactide or a blend thermoplastic starch and polycaprolactone. 16. Use of a semi-finished product made of biodegradable and composted baren polymers according to any one of claims 1 to 15, characterized records that it is in the form of a single or multilayer, biodegradable removable and compostable film in pretreated or untreated, printed or unprinted form for packaging in the areas Food and non-food or for protection and separation functions in connection with cosmetics and hygiene articles, provided with adhesive as a label or adhesive tape or for greenhouse covers, mulch films or for lining plant growing boxes in the horticultural sector or agriculture or for sacks for the storage and transport of goods. 17. Use of a semi-finished product made of biodegradable polymers one of claims 1 to 15, characterized in that it is in the form of a single or multi-layer, biodegradable and compostable film, which can be coated, printed or varnished on one or both sides, for the production of a bag that after decay by the biological Degradation process releases its contents, the bag being glued and can be made by sealing the film and both be closed as well as an opening with a corresponding closure or can have connection.