WO2000055240A1

WO2000055240A1 - Semi-finished products consisting of biodegradable polymers with improved hydrolytic stability and stress-cracking resistance

Info

Publication number: WO2000055240A1
Application number: PCT/EP2000/001665
Authority: WO
Inventors: Michael Kleemiss; Lutz Hoppe; Gunter Weber
Original assignee: Wolff Walsrode Ag
Priority date: 1999-03-13
Filing date: 2000-02-28
Publication date: 2000-09-21
Also published as: AU3553100A; DE19911209A1

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

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

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

It is known that certain polymeric materials can undergo biodegradation. The main materials to be mentioned here are those that are obtained directly or after modification from naturally occurring polymers, 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 is desirable on the part of the polymer application, is due to the natural

Synthesis process is difficult and often only possible to a very limited extent. For the purposes of this invention, the terms "biodegradable and compostable polymers or semi-finished products" are understood to mean goods which have been tested for "biodegradability" in accordance with the test according to DIN V 54 900 from 1998.

However, many of the synthetic polymers are not attacked by microorganisms, or only very slowly. Mainly synthetic polymers that contain heteroatoms in the main chain are considered to be potentially biodegradable. The polyesters represent an important class within these materials. Synthetic raw materials which only contain aliphatic monomers have a relatively good biodegradability, and because of their material properties they can be used only 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 a significantly deteriorated biodegradability with good material properties. From DE-A-44 32 161 and EP-A-641 817, various biodegradable polymers based on polyester or polyester amide have become known. These have the property that they are easy to process thermoplastically and on the other hand are biodegradable, ie their entire polymer chain is broken down by microorganisms (bacteria and fungi) by means of enzymes and completely broken down to carbon dioxide, water and biomass, for example by the action of microorganisms, as they occur in compost, in a test according to DIN V 54 900. Due to the thermoplastic behavior, these biodegradable materials can be processed into semi-finished products such as cast or blown films. Nevertheless, the use of these semi-finished products is very limited, since the biodegradable polymers are sometimes very susceptible to hydrolysis and stress cracking. This vulnerability can also manifest itself in a biodegradation that is too rapid for many applications. Particularly in the case of foil bags produced from semi-finished products in the form of foils, which are used in the field of waste disposal of organic substances, it should be possible to achieve hydrolysis stability and stress crack resistance of 1 to 3 weeks, preferably 1 to 2 weeks, in order to enable problem-free transport. During the later composting of the organic waste, the hydrolysis and cracking of the polymers at the same time cause the foil pouch to disintegrate, and the foil pouch is biodegraded and composted together with the contents of the foil pouch.

It was therefore an object of the present invention to produce semi-finished products made of biodegradable polymers, preferably moldings produced by extrusion or injection molding, and in particular films with improved resistance to hydrolysis and

To provide stress crack resistance. Hydrolysis is understood to mean the decomposition by aqueous media, which may also have an acidic or alkaline pH due to additional constituents. 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 varnishing 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 Nitrocellulose Varnishes, Part 3, Plasticizers, 1961, West Berlin publishing house Heenemann KG, pages 394-448, if necessary with the addition of conventional paint resins, waxes and additives, the hydrolysis stability and stress crack resistance of the semi-finished products made of biodegradable polymers, for example, extended to 4 to 8 times. The order quantity of the

Coating (coating) 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 the coated surface of the semi-finished product to become hydrophobic. Since, as a rule, every biodegradation is also associated with hydrolysis of the material, the biodegradation can also be delayed or controlled by the coating.

It is also achieved by the coating that the diffusion of the permeable surrounding medium into the structure of the molded body under tension occurs so slowly that failure of the molded body due to chain breakage, if not prevented, is delayed.

A corresponding control can also be achieved in that a semi-finished product made of a biodegradable polymer or mixtures of biodegradable polymers is completely or only partially coated with cellulose esters, in particular 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 which are completely or partially coated, in particular printed or painted, with cellulose esters on at least one surface, in a preferred form the coated, printed or painted surface being exposed to the hydrolyzing medium.

In a particularly preferred form, the cellulose esters used for the coating 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 N2 content <12.6%).

The cellulose esters are available in different viscosity grades, and the selection of the appropriate viscosity grade depends on the processing conditions.

The cellulose esters can also be used in the plasticized form (e.g. nitrocellulose chips). Plasticizers are plasticizing resins or polymeric plasticizers.

In the preferred embodiment of painting the semi-finished product with cellulose ester paints based on organic solvents, consisting of the cellulose ester as binder and the suitable plasticizer, customary paint resins, such as preferably alkyd resins, ketone resins, urea resins,

Melamine formaldehyde resins, polyurethane resins or acrylate polymers are added in amounts of up to 30% by weight, preferably up to 25% by weight (based on the solids content of the paints).

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 paints, part 1, solvent, 1955, Wilhelm Pansegrau Verlag, Dept. of the West Berlin publishing company Heenemann KG).

The following are suitable as biodegradable polymers, from which semi-finished products are produced 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, based on all acids, preferably formed from

a) aliphatic bifunctional alcohols, preferably linear C ₂ - to Ci _Q 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 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 C3-Ci2-alkyldiols , in particular neopentyl glycol, and in addition, if appropriate, 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 C2-Ci2-alkyldicarboxylic acids, particularly preferably succinic acid or adipic acid and optionally aromatic bifunctional acids such as preferably terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally, if appropriate, small

Amounts of higher functional acids, preferably 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 hydroxybutyric acid, hydroxy- valeric acid, lactic acid, or their derivatives, for example ε-caprolactone or dilactide,

or a mixture of several of the stated polyesters and / or one or more copolymers from the 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 ester groups preferably formed from building blocks a) and / or b), contain urethane groups, which were preferably formed from

c) aliphatic and / or cycloaliphatic bifunctional or additionally optionally higher functional isocyanates, preferably having 1 to 12 C atoms or 5 to 8 C 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 C3-Ci2-alkyldi- or polyols or cycloaliphatic alcohols with 5 to 8 carbon 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, in particular ethylenediaminoethanesulfonic acid, as the free acid or as the salt,

the ester fraction preferably formed from a) and b) being 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 the building blocks a) and / or b), which are preferably formed from:

d) a carbonate fraction which is produced from aromatic bifunctional phenols, preferably bisphenol-A, and carbonate donors, in particular phosgene, or a carbonate fraction which consists of aliphatic carbonic acid esters or their

Derivatives such as preferably chlorocarbonic acid esters or aliphatic carboxylic acids or their derivatives such as salts and carbonate donors, in particular phosgene, is produced, where

the ester fraction preferably formed from a) and / or b) is at least 70% by weight, based on 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 in addition to the building blocks a) and / or b) contain amide groups, which were preferably formed from

e) aliphatic and / or cycloaliphatic bifunctional amines, preferably linear aliphatic C2 to CiQ 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 Cg ring in the case of cycloaliphatic acids, preferably adipic acid, and optionally small

Amounts of branched bifunctional and / or optionally aromatic 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

f) 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), the ester fraction preferably formed from a) and / or b) being at least 20% by weight, based on the total weight, preferably the ester fraction 20 to 80% by weight, and the fraction the amide structures is 80 to 20% by weight.

The polymers used to produce the semifinished products according to the invention can be either pure polymers or mixtures of different polymers, in the case of mixtures preferably polymers from only one of the abovementioned classes of compound (polyester, polyester urethane, polyester carbonate, polyester amide) are used. Polyester amides or mixtures of different polyester amides are particularly preferably used.

In a special embodiment of the invention, mixtures of biodegradable polymers, preferably one or more polymers from the aforementioned compound classes polyester, polyester urethanes, polyester carbonates or in particular polyester amides with other biodegradable polymers, in particular mixtures of thermoplastic starch (for example MaterBi , Novamont) or polylactide (eg Eco Pia, Dow Cargill) or polycaprolactone (TONE, Union Carbide Corporation). The polymers or polymer mixtures used to produce the semifinished products according to the invention can additionally contain customary additives and auxiliaries in customary amounts, for example nucleating agents, stabilizers, neutralizing agents, lubricants, release agents, antiblocking agents and / or pigments.

The invention also relates to the use of the hydrolysis-stabilized, biodegradable and compostable semi-finished products according to the invention. In a particularly preferred form, the semifinished product is a single-layer or multi-layer, biodegradable and compostable film which is coated on one or both sides with cellulose esters, in particular printed or painted. Semi-finished products in the form of such films can advantageously be used in pretreated or untreated as well as in printed, unprinted form for packaging in the food and non-food sectors or as hydrolysis-stabilized, single or multilayer film in pretreated or untreated form for protective and separating functions in connection with Cosmetics and hygiene articles, for example for baby diapers or sanitary napkins or as a refined film, which are used in pretreated or untreated as well as printed or unprinted form and provided with adhesive as a label or adhesive strip or as hydrolysis-stabilized, single or multi-layer film in pretreated or untreated form for greenhouse covers , Mulch foils or for lining plant growing boxes (eg for mushroom cultivation) in the fields of horticulture or agriculture or refined into sacks for the storage and transport of goods, for example organic waste find their application, the control of the stress crack resistance and the hydrolytic and biological degradation rate being possible by the application amount of the cellulose esters being particularly advantageous.

The invention furthermore relates to the particularly preferred use of the semi-finished products according to the invention coated on one or both sides with cellulose esters in the form of printed or lacquered multilayer film for the production of a bag which, after disintegration, is caused by the biodegradation process releases its content. The bag can be produced by gluing and sealing the film and can both be closed and have an opening with a corresponding closure or connection.

The following examples are intended to explain the invention in more detail without restricting it thereto.

Examples of the film variants

Slide 1

From the polyester amides A: BAK 403-004 built up from the monomers

23% by weight adipic acid, 17% by weight 1,4-butanediol, 60% by weight ε-caprolactam (Bayer AG, MFR M. 7 g / 10 min at 190 ° C; 2.16 kg; measured after DIN 53 735; melting point 125 ° C, measured according to ISO 3146 / C2; content of lubricant 1% by weight, content of antiblocking agent 0.1% by weight) and B: BAK 404-002 made up of 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 according to DIN 53 735; melting point 140 ° C, measured according to ISO 3146 / C2; content of lubricant 0.4% by weight , Antiblocking agent content 0.1% by weight), semi-finished coextruded blown films were produced in a total thickness of 40 μm with an ABA structure (10 μm / 20 μm / 10 μm). The maximum extrusion temperature was 175 ° C. The melt was discharged through an annular die and cooled by air. The maximum nozzle temperature was 170 ° C.

Slide 2

A single-layer blown film with a thickness of 40 μm was produced from material A of film 1. 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:

* according to DIN 53 179

! ⁾ Centroplast FU 112 from Vianova Resins

²⁾ Alkydal F 251 from Bayer AG The films were then printed and overcoated on one side over the entire surface with the cellulose ester lacquers of formulations 1 to 5. After the lacquer had dried, bags were made from the foils, the lacquered surface being 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). The waste was obtained from a composting plant and mixed to ensure that the variations in the composition of the waste remained as small as possible. Five bags of each film variant and lacquer formulation were filled in order to minimize statistical fluctuations.

- The filled bags were stored at an average outside temperature of 13 ° C and checked daily for damage or feeding or degradation holes. The maximum durability was determined when the holes exceeded a size of 2 cm.

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

Claims

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 one on at least one surface

Have plasticizers or plasticizer mixtures.

2. Semi-finished products made of biodegradable and compostable polymers according to claim 1, characterized in that the application amount of the coating is 1 to 15 g / m ² , preferably 1 to 10 g / m ² .

3. Semi-finished products made of biodegradable and compostable polymers according to claim 1 or 2, characterized in that the semi-finished products are molded articles produced by extrusion or injection molding or in particular films.

4. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 3, characterized in that the semi-finished products are unstretched, monoaxially stretched or biaxially stretched, single or multi-layer, pretreated or untreated blown films or

Flat films.

5. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 4, characterized in that the semi-finished products are completely or only partially coated, in particular printed or painted.

6. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 5, characterized in that the cellulose esters are cellulose acetate, cellulose acetobutyrate or propionate and in particular cellulose nitrate.

. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 6, characterized in that the coating is a cellulose ester plasticizer or plasticizer mixture based on organic solvents, the solvent and, if appropriate, customary coating resins in amounts of up to 30% by weight. -%, preferably up to 25% by weight (based on the solids content of the lacquer).

8. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 7, characterized in that as biodegradable polymers biodegradable aliphatic polyesters or partially aromatic polyesters with a proportion of aromatic acids of not more than 60% by weight, based on all acids or functional derivatives derived from these polyesters in the form of polyester urethanes with a

Ester content of at least 75 wt .-%, or polyester carbonates with an ester content of at least 70 wt .-% or polyester amides with an ester content of at least 20 wt .-% or their mixtures or copolymers of the monomers forming these polymers are used.

9. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 8, characterized in that the biodegradable polymers are 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 on monomeric or oligomeric polyols

Based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers therefrom with molecular weights of up to 4000, preferably up to 1000, and optionally small amounts of branched bifunctional alcohols, preferably C ₁₂ -C ₁₂ -alkyldiols, in particular neopentyglycol, and additionally optionally 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 ₂ -alkyldicarboxylic acids, particularly preferably succinic acid or adipic acid and optionally aromatic bifunctional acids such as preferably terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid such as trimellitic acid and additional small amounts, if appropriate 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, hydroxyvaleric acid, lactic acid, or their derivatives, for example ε-caprolactone or dilactide,

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

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

c) aliphatic and / or cycloaliphatic bifunctional and additionally optionally higher functional isocyanates, preferably with

1 to 12 carbon atoms or 5 to 8 carbon atoms in the case of cycloaliphatic cal 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 cycloaliphatic alcohols

5 to 8 carbon 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

Ethylene diamine or aminoethanol, and / or optionally further modified amines or alcohols, such as, in particular, ethylene diaminoethanesulfonic acid, can be used as the 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

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

12. Semi-finished products made of biodegradable polymers according to one of the claims

1 to 8, characterized in that as biodegradable polymers aliphatic or partially aromatic polyester amides with amide groups formed from

e) aliphatic and / or cycloaliphatic bifunctional amines, preferably linear aliphatic C ₂ to C ₁₀ diamines, in particular

Isophorone diamine and very particularly preferably hexamethylene diamine, where these amines can optionally contain small amounts of branched bifunctional amines and / or higher functional amines, as well as 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 C atoms, optionally small amounts of branched bifunctional and / or optionally aromatic bifunctional acids such as, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids, preferably with 2 to 10 carbon atoms, or

f) acid- and amine-functionalized building blocks, preferably having 4 to 20 carbon 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 of biodegradable and compostable polymers according to one of claims 1 to 8 or 12, characterized in that the biodegradable polymers can be both pure polymers and mixtures of various of the polymers mentioned.

14. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 8 or 12, characterized in that it is the biodegradable polymers are polyester amide or a mixture of different polyester amides.

15. Semi-finished products made of biodegradable and compostable polymers according to one of claims 1 to 7, characterized in that the biodegradable polymers are a mixture in which a

Mixing partner consists of polycaprolactone or polylactide or a blend of thermoplastic starch and polycaprolactone.

16. Use of a semi-finished product made of biodegradable and compostable polymers according to one of claims 1 to 15, characterized in that it is in the form of a single or multi-layer, biodegradable and compostable film in pretreated or untreated, printed or unprinted form for the packaging in the areas of food and non-food or for protective and separating functions in connection with cosmetics and hygiene articles, provided with adhesive as a label or adhesive strip or for greenhouse covers, mulch films or for lining plant growing boxes in the areas of horticulture or agriculture or for sacks for storage and transport of goods.

17. Use of a semi-finished product made of biodegradable polymers according to 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 painted on one or both sides the production of a bag that after decay by the biological

Degradation process releases its contents, the bag can be produced by gluing and sealing the film and can both be closed and have an opening with a corresponding closure or connection.