WO2014009176A1

WO2014009176A1 - Method for complete anaerobic degradation of polymer mixtures

Info

Publication number: WO2014009176A1
Application number: PCT/EP2013/063647
Authority: WO
Inventors: Carsten SINKEL; Robert Loos; Karlheinz JOCHEM; Kai Oliver SIEGENTHALER; Xin Yang; Ulf KÜPER; Mathias ZIMMERMANN
Original assignee: Basf Se; Basf Schweiz Ag
Priority date: 2012-07-10
Filing date: 2013-06-28
Publication date: 2014-01-16

Abstract

The invention relates to a method for complete anaerobic degradation of polymer mixtures containing : a) 25 - 95 wt. % of a polyhydroxyalcanoate selected from the group consisting of poly-4-hydroxybutyrates, poly-3-hydroxybutyrates, poly(3-hydroxybutyrate-co-3-hydroxyvalerates), poly(3-hydroxybutyrate-co-3-hydroxyhexanoates and poly(3-hydroxybutyrate-co-4-hydroxybutyratea) and b) 5 - 75 wt. % of an aliphatic-aromatic polyester containing i) 65 - 95 mol %, in relation to the components i - ii, one or more C₅-C₃₆-dicarboxylic acid derivatives or C₅-C₃₆-dicarboxylic acids; ii) 35 - 5 mol %, in relation to the components i - ii, of a terephthalic acid derivative or a terephthalic acid; iii) 98 - 100 mol %, in relation to the components i - ii, of a C₂-C₈-alkylene diol or C₂-C₆-oxyalkylene diol; iv) 0 - 2 wt.-%, in relation to the components i - iii, of at least one polyfunctional compound containing at least two isocyanate-, isocyanurate-, oxazoline- or epoxide-groups or at least three alcohol- or carboxylic acid groups.

Description

Process for the complete anaerobic degradation of polymer mixtures

The present invention relates to a process for the complete anaerobic degradation of polymer mixtures comprising:

From 25 to 95% by weight of a polyhydroxyalkanoate selected from the group consisting of poly-4-hydroxybutyrate, poly-3-hydroxybutyrate, poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3-) hydroxyhexanoates) and poly (3-hydroxybutyrate-co-4-hydroxybutyrate); and b) 5 to 75% by weight of an aliphatic-aromatic polyester containing:

65 to 95 mol%, based on the components i to ii, of one or more C5-C36 dicarboxylic acid derivatives or C5-C36 dicarboxylic acids;

From 35 to 5 mol%, based on the components i to ii, of a terephthalic acid derivative or a terephthalic acid;

98 to 100 mol%, based on the components i to ii, of a C 2 -C 8 -alkylenediol or C 2 -C 6 -oxyalkylenediol;

0 to 2 wt .-%, based on the components i to iii, of at least one polyfunctional compound containing at least two isocyanate, isocyanurate, oxazoline or epoxide groups or at least three alcohol or carboxylic acid groups.

WO-A 92/09654 describes linear aliphatic-aromatic polyesters which are biodegradable. Crosslinked, biodegradable polyesters are described in WO-A

96/15173 described. However, the polyesters described in WO-A 92/09654 and WO-A 96/15173 do not have an anaerobic degradation rate in mixtures with polyhydroxyalkanoates, which is significantly greater than the polyhydroxyalkanoate content.

US 5,281,691 and US 2004/0225269 describe mixtures of polyhydroxyalkanoates and aliphatic-aromatic polyesters having a very unspecific terephthalic acid content. Anaerobic degradation rates of these mixtures are not described, in particular, no indication can be found in these documents that the aliphatic-aromatic polyester itself can also be anaerobically degraded if the terephthalic acid content is selected to be correspondingly small and the correct mixing ratio with polyhydroxyalkanoate. Although films consisting exclusively of polymer component a (polyhydroxyalkanoate) are anaerobically degradable, they can not be convincing in terms of their mechanical properties and their processability. The aim of the present invention was therefore to provide a method for the production of mechanically loadable films, which also have a good anaerobic biodegradability and good processability.

Interestingly, the inventive mixtures whose polymer component b has a lower terephthalic acid content have an increased anaerobic degradation rate, which clearly exceeds the calculated value of the polyhydroxyalkanoate content. This is surprising and indicates that the polymer mixtures according to the invention have a synergy with respect to anaerobic degradation.

By using the polyesters described at the outset, which have a narrowly defined terephthalic acid content and a narrowly defined content of a polyfunctional component iv, it was possible, surprisingly, to prepare mechanically loadable films having a high anaerobic degradation rate.

The invention will be described in more detail below.

Polyhydroxyalkanoates (polymer component a) are primarily poly-4-hydroxybutyrates and poly-3-hydroxybutyrates or poly-3-hydroxybutyrate-co-4-hydroxybutyrates and copolyesters of the abovementioned polyhydroxybutyrates with 3-hydroxyvalerate, 3-hydroxyhexanoate and / or 3-hydroxyoctanoate. Poly-3-hydroxybutyrates are sold, for example, by PHB Industrial under the brand name Biocycle® and by Tianan under the name Enmat®. Poly-3-hydroxybutyrate-co-4-hydroxybutyrates are known in particular from Metabolix. They are sold under the trade name Mirel®.

Poly-3-hydroxybutyrate-co-3-hydroxyhexanoates are known, for example, from Kaneka. Poly-3-hydroxybutyrate-co-3-hydroxyhexanoates generally have a 3-hydroxyhexanoate content of 1 to 20 and preferably from 3 to 15 mol%, based on the butyrate fraction.

The synergy in anaerobic degradation is found in all of the aforementioned polyhydroxyalkanoates. It is particularly pronounced for the copolymers: poly-3-hydroxybutyrate-co-3-hydroxyvalerate and especially for poly-3-hydroxybutyrate-co-4-hydroxybutyrate and poly-3-hydroxybutyrate-co-3-hydroxyhexanoate. The abovementioned copolymers are particularly preferred for the novel polymer blends. The polyhydroxyalkanoates generally have a molecular weight Mw of from 100,000 to 1,000,000, and preferably from 300,000 to 600,000.

The polyhydroxyalkanoates are preferably prepared by fermentation, as described, for example, in WO-A 2008010296 or WO-A 1999064498.

The synthesis of the polyester component b) is generally carried out in a two-stage reaction cascade (see WO09 / 127555 and WO09 / 127556). First, the dicarboxylic acid derivatives, as in the synthesis examples, are reacted together with the diol (for example 1,4-butanediol) in the presence of a transesterification catalyst to give a prepolyester. Subsequently, the melt of the prepolyester thus obtained is usually condensed at an internal temperature of 200 to 250 ° C within 3 to 6 hours at reduced pressure while distilling off released diol to the desired viscosity. The catalysts used are usually zinc, aluminum and in particular titanium catalysts. Titanium catalysts such as tetra (isopropyl) orthotitanate and in particular tetrabutyl orthotitanate (TBOT) have the advantage over the tin, antimony, cobalt and lead catalysts frequently used in the literature, such as, for example, tin dioctanoate, that residual amounts of catalyst or secondary product of the catalyst remaining in the product are less toxic. This fact is particularly important in the case of biodegradable polyesters, since they enter the environment directly, for example as composting bags or mulch films.

The polyesters according to the invention are optionally subsequently chain-extended according to the processes described in WO 96/15173 and EP-A 488 617. The prepolyester is reacted, for example, with chain extenders vib), such as with diisocyanates or with epoxy-containing polymethacrylates, in a chain extension reaction to give a polyester having a viscosity of 60 to 450 ml / g, preferably 80 to 250 ml / g. Particularly preferably, the polyester component b) is prepared by the continuous process described in WO2009127556. The abovementioned ranges of viscosity numbers merely serve as indications for preferred process variants, but are not intended to be limiting for the present application subject. In addition to the continuous process described above, the polyesters according to the invention can also be prepared in a batch process. For this purpose, the aliphatic and the aromatic dicarboxylic acid derivative, the diol and a branching agent iva are mixed in any metering order and condensed to form a prepolyester. Optionally, with the aid of a chain extender, a polyester having the desired viscosity number can be prepared. Examples of polybutylene terephthalate succinates, azelates, brassates and, in particular, adipates and sebacates having an acid number, measured in accordance with DIN EN 12634, of less than 1.0 mg KOH / g and a viscosity number greater than 130 ml / g can be obtained by the abovementioned processes and a MVR according to ISO 1133 of less than 6 cm ^3/10 min (190 ° C, 2.16 kg weight).

For other applications, polyester according to the invention with higher MVR can be interesting to ISO 1133 of up to 30 cm ^3/10 min (190 ° C, 2.16 kg weight). The polyesters generally have an MVR according to ISO 1133 1-30 cm ^3/10 min and preferably 2 to 20 cm ^3/10 min (190 ° C, 2, 16 kg weight).

Sebacic acid, azelaic acid and brassylic acid (i) are derived from renewable resources, in particular from vegetable oils such as e.g. Castor oil accessible.

The terephthalic acid ii is used in 5 to 35 mol% and preferably 10 to 25 mol% based on the diacid components i and ii.

Terephthalic acid and the aliphatic dicarboxylic acid can be used either as the free acid or in the form of ester-forming derivatives. Particularly suitable ester-forming derivatives are the di-C 1 - to C 6 -alkyl esters, such as dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-t-butyl, Di-n-pentyl, di-iso-pentyl or di-n-hexyl esters to name. Anhydrides of dicarboxylic acids can also be used.

The dicarboxylic acids or their ester-forming derivatives can be used individually or as a mixture.

1, 4-butanediol is also available from renewable raw materials. WHERE

09/024294 discloses a biotechnological process for the production of 1,4-butanediol from different carbohydrates with microorganisms from the class of Pasteurellaceae. Succinic acid is also accessible by biotechnological methods.

As a rule, at the beginning of the polymerization, the diol (component iii) is added to the acids (components i and ii) in a ratio of diol to diacids of from 1.0 to 2.5: 1 and preferably from 1.3 to 2.2: 1 used. Excess diol are withdrawn during the polymerization, so that sets an approximately equimolar ratio at the end of the polymerization. By approximately equimolar is meant a diol / diacid ratio of 0.98 to 1: 1. The said polyesters may have hydroxyl and / or carboxyl end groups in any ratio. The abovementioned partially aromatic polyesters can also be end-group-modified. Thus, for example, OH end groups by Reaction with phthalic acid, phthalic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid or pyromellitic anhydride are acid-modified. Preference is given to polyesters having acid numbers of less than 1.5 mg KOH / g. As a rule, a branching agent iva and optionally additionally a chain extender ivb selected from the group consisting of: a polyfunctional isocyanate, isocyanurate, oxazoline, epoxide, carboxylic anhydride, an at least trifunctional alcohol or an at least trifunctional carboxylic acid are used. Suitable chain extenders ivb are polyfunctional and in particular difunctional isocyanates, isocyanurates, oxazolines, carboxylic anhydride or epoxides. The crosslinkers iva) are generally obtainable in a concentration of 0 to 2% by weight, preferably 0.07 to 1% by weight and more preferably 0.1 to 0.5% by weight, based on the polymer the components i to iii used. The chain extenders ivb) are generally used in a concentration of 0 to 2 wt .-%, preferably 0.1 to 1 wt .-% and particularly preferably 0.35 to 1 wt .-% based on the total weight of the components i used to iii.

Chain extenders as well as alcohols or carboxylic acid derivatives having at least three functional groups can also be regarded as branching agents. Especially preferred compounds have three to six functional groups. Examples include: tartaric acid, citric acid, malic acid; Trimethylolpropane, trimethylolethane; pentaerythritol; Polyether triols and glycerol, trimesic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid and pyromellitic dianhydride. Preference is given to polyols such as trimethylolpropane, pentaerythritol and in particular glycerol. By means of components iv, biodegradable polyesters with a structural viscosity can be built up. The rheological behavior of the melts improves; The biodegradable polyesters are easier to process, for example, better by melt consolidation to remove films. In general, it is useful to add the crosslinking (at least trifunctional) compounds at an earlier stage of the polymerization.

Suitable bifunctional chain extenders are the following compounds: Under an aromatic diisocyanate ivb are mainly toluylene-2,4-diisocyanate, toluylene-2,6-diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4 , 4'-diphenylmethane diisocyanate, naphthylene-1, 5-diisocyanate or xylylene diisocyanate understood. Of these, 2,2'-, 2,4'- and 4,4'-diphenylmethanediisocyanate are particularly preferred. In general, the latter diisocyanates are used as a mixture. In minor amounts, for example up to 5% by weight, based on the total weight, the diisocyanates may also contain uretdione groups, for example for capping the isocyanate groups. In the context of the present invention, an aliphatic diisocyanate is primarily linear or branched alkylene diisocyanates or cycloalkylene diisocyanates having 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, for example 1, 6-hexamethylene diisocyanate, isophorone diisocyanate or methylene bis (4-isocyanatocyclohexane ), Understood. Particularly preferred aliphatic diisocyanates are isophorone diisocyanate and in particular 1,6-hexamethylene diisocyanate.

The polyesters of the invention generally have a number average molecular weight (Mn) in the range of 5000 to 100,000, in particular in the range of 10,000 to 60,000 g / mol, preferably in the range of 15,000 to 38,000 g / mol, a weight-average molecular weight (Mw) of 30,000 to 300,000, preferably 35,000 to 200,000 g / mol and a Mw / Mn ratio of 1 to 6, preferably 2 to 4. The viscosity number is between 30 and 450, preferably from 50 to 400 ml / g and particularly preferably from 80 to 250 ml / g (measured in o-dichlorobenzene / phenol (weight ratio 50/50)). The melting point is in the range of 30 to 100, preferably in the range of 35 to 80 ° C.

Preference is given to biodegradable polyesters having the following constituents: component i), the aliphatic dicarboxylic acid is preferably adipic acid and / or sebacic acid.

Component iii), the diol, is preferably 1,4-butanediol. Komponete iv), the branching agent iva, is preferably glycerol.

The novel polymer blends contain from 25 to 95% by weight, preferably from 30 to 90% by weight and particularly preferably from 35 to 85% by weight, of polyhydroxyalkanoate (a) and accordingly from 5 to 75% by weight, preferably from 10 to 70 Wt .-% and particularly preferably 15 to 65 wt .-% polyester component b.

In a preferred embodiment, from 1 to 50% by weight, based on the total weight of the film (components a to c), of an organic filler c) is selected from the group consisting of: native or plasticized starch, natural fibers, wood flour, crushed cork, ground bark, nut shells, ground press cakes (vegetable oil refinery), dried production residues from fermentation or distillation of beverages such as beer, brewed sodas (eg bionade), wine or sake and / or an inorganic filler selected from the group consisting of: chalk, graphite , Gypsum, carbon black, iron oxide, calcium chloride, dolomite, kaolin, silica (quartz), sodium carbonate, titanium dioxide, silicate, wollastonite, mica, montmorillonite, talc, glass fibers and mineral fibers. Starch and amylose may be native, ie non-thermoplasticized or thermoplasticized with plasticizers such as glycerol or sorbitol (EP-A 539 541, EP-A 575 349, EP 652 910). Thermoplastified starch is particularly preferred because it itself is likewise degraded anaerobically and films which, in addition to starch, contain the polymer components a and b, provide good mechanical properties. Surprisingly, mixtures of starch and polymer component b (without polymer component a) show no synergy with respect to anaerobic degradability. If one adds strength of the polymer mixture a and b, in addition to the degradation of the starch and the previously described synergistic anaerobic degradation behavior is found. The thermoplasticized starch is added to the polymer blends containing the components a and b, usually in a ratio of 0 to 50, preferably 5 to 50 and particularly preferably 10 to 35 wt .-%. Sheets produced from this have excellent tear resistance and at the same time complete anaerobic degradation. They are particularly suitable for the production of very thin, tear-resistant films.

Among natural fibers are, for example, cellulose fibers, hemp fibers, sisal, kenaf, jute, flax, abaca, coconut fiber or even regenerated cellulose fibers (rayon) such. B. Cordenkafasern understood. By adding mineral fillers such as chalk, graphite, gypsum, Leitruß, iron oxide, calcium chloride, dolomite, kaolin, silica (quartz), sodium carbonate, titanium dioxide, silicate, wollastonite, mica, montmorillonite or talc, the mechanical properties of the films such as Significantly improve tear propagation resistance. As a rule, the mineral fillers are used in a concentration of 1 to 50, preferably 4 to 30 and particularly preferably 8 to 25% by weight, based on the polymer components i to iv.

The anaerobically degradable polyester mixtures a, b may further contain polymers such as polylactic acid, polycaprolactone, aliphatic polyesters, polyglycolic acid and polypropylene propylene carbonate in an amount of 0 to 30% by weight, preferably 5 to 20% by weight. Aliphatic polyesters include polyesters of aliphatic C ₂ -C 12 alkanediols and C ₄ -C ₃₆ aliphatic alkanedicarboxylic acids such as polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate adipate (PBSA), polybutylene succein sebacate (PBSSe), polybutylene sebacate adipate (PBSeA), polybutylene sebacate (PBSe) or corresponding polyesteramides understood. The aliphatic polyesters are marketed by Showa Highpolymers under the name Bionolle® and by Mitsubishi under the name GSPIa®. Newer developments are in the WO

2010/03471 1 described. The biodegradable polyester mixtures may contain further ingredients known to the person skilled in the art but not essential to the invention. For example, the usual additives in plastics technology such as stabilizers; nucleating agents; Neutralizing agents; Lubricants and release agents such as stearates (in particular calcium stearate) or erucic acid amide or behenamide; Plasticizers such as citric acid esters (especially acetyl tributyl citrate), glyceric acid esters such as triacetylglycerol or ethylene glycol derivatives, surfactants such as polysorbates, palmitates or laurates; Waxes such as beeswax or beeswax esters; Antistatic, UV absorber; UV stabilizers; Antifog agents or dyes. The additives are used in concentrations of 0 to 5 wt .-%, in particular 0.1 to 2 wt .-% based on the polyesters of the invention. Plasticizers may be present in 0.1 to 10% by weight in the polyesters of the invention.

The production of the biodegradable polyester mixtures according to the invention from the individual components can be carried out by known processes (EP 792 309 and US Pat. No. 5,883,199). For example, all mixing partners can be mixed and reacted at elevated temperatures, for example from 120 ° C. to 250 ° C., in mixing apparatuses known in the art, for example kneaders or extruders, in one process step.

The polymer blends may in turn contain from 0.05 to 2% by weight of a compatibilizer. Preferred compatibilizers are carboxylic acid anhydrides such as maleic anhydride and in particular the previously described epoxide group-containing copolymers based on styrene, acrylic ester and / or methacrylic acid ester. The epoxy groups bearing units are preferably glycidyl (meth) acrylates. The epoxy-containing copolymers of the above type are sold for example by BASF Resins BV under the trademark Joncryl ^® ADR. As tolerability keitsvermittler particularly suitable Joncryl ^® ADR, for example, the 4368th

Component iv, the aforementioned fillers or the other auxiliaries mentioned above are preferably added by previously prepared masterbatches of the auxiliaries in polymer component a or b.

In the following, the process of degradation of polymers is explained in more detail and the differences between abiotic, aerobic and anaerobic degradation are discussed in more detail. In general, polymers or polymer mixtures can undergo a degradation process in two fundamentally different ways. First, the polymeric structure of a macromolecule can be resolved solely under the influence of abiotic factors (physico-chemical parameters, such as: UV radiation, temperature, pH, moisture, influence of oxygen radicals), which ultimately leads to a transfer of the polymer in Oligomers, monomers or from the degradation resulting reaction products leads. In contrast, the biodegradation of polymers is primarily due to the biochemical interaction of microorganisms (bacteria rien, archaea, fungi) with the polymer. The breakage of the chemical bonds in the polymer is achieved by specific interactions with the enzymes of the microorganisms. The interplay of different microorganisms and their enzymes eventually leads to mineralization of the polymer. During mineralization, the polymer is not only recycled into monomers or oligomers, but rather is converted enzymatically into the microbial metabolic end products water, carbon dioxide and methane (under anaerobic conditions). Abiotic and biological degradation often occur in parallel - but it is crucial that the mineralization is at the end of biodegradation.

Both the biological and the physico-chemical degradation of polymers lead to a loss of the characteristic polymer properties.

The biological degradation of macromolecules per se is a very diverse process that results in different rates of degradation in terms of habitat and the abiotic parameters prevailing there. In addition to the abiotic framework, a correspondingly high compatibility between polymer and enzyme is necessary for efficient biodegradation. Consequently, a high degradation rate can be achieved if the conditions prevailing in the habitat are optimal for the microorganisms involved and a specific interaction between the polymer chain and the enzyme is ensured. Decisive factors here are the temperature, the pH value, the presence or absence of oxygen and the availability of nutrients, minerals and trace elements. Depending on the combination of these factors, the respective habitat will dominate different consortia with a very variable number of microorganisms (total cell count: cells per volume, biodiversity: number of microbial species in the habitat) and lead to the described different rates of degradation.

For the biodegradation of synthetically produced polymers, the main focus is on the "ecological systems" that are used in the context of biological waste treatment: In addition to composting, the biological treatment of wastewater is biogas-forming degradation under anaerobic conditions In addition to the metabolic end products of aerobic degradation (H2O and CO2), methane is also formed, which can then be used to generate electrical energy or fed into the natural gas grid as biomethane.The process of anaerobic degradation (AD = anaerobic Digestion) is a complex multistage microbial cascade reaction (hydrolysis - »· Acidogene- se -» · acetogenesis - »· methanogenesis), the conversion of the polymers into monomers and the following metabolic reactions of the intermediates to H2O, CO2 and _CH4 in It is important to mention that this process is not by a a single, independent microorganism, but by a variety of microorganisms is performed, each responsible for a corresponding sub-step of the reaction cascade. On an industrial scale, the process takes place either in plants for dry fermentation (dry matter> 20 - 40% (w / w)) or for wet fermentation (dry matter <12 - 15% (w / w)) instead. While wet plants in Germany are currently mainly used by farmers for biogas production from liquid manure or renewable raw materials, systems for dry fermentation are also used for the elimination of organic waste in waste management. Dry fermentation can again be carried out between continuously operated plug flow systems (continuous process, dry substance> 20-30% (w / w)) and the batchwise operated vessel fermenters (batch process, dry matter> 30-40% (w / w)). w)). This is just a selection of the technologies available. The efficiency of the respective process is related to how much biogas (volume CO2 and CH4) can be obtained from the amount of substrate (carbon source) and how high the quality of the biogas produced is (proportion CH4). The methane formation potential of a substrate can thus be determined by measuring the methane formed in a defined time unit and compared quantitatively with other substrates. For simplification and reproducibility of the method, a simple volume determination of the biogas formed is often carried out, in which the CO2 is washed out in advance by means of sodium hydroxide solution. Thus, the volume of methane formed can be determined directly. Alternatively, the total volume of the biogas can be determined first and the quantitative analysis of the biogas composition is subsequently followed by gas chromatography. Considering later technical application and better comparability, anaerobic degradation is usually taken into account for a maximum of 2 months in all test procedures.

Already described methods for determining the biodegradability of polymers and other chemical substances can be found for example in the ISO test methods: · ISO 1 1734

Water quality - Determination of the complete anaerobic degradability of organic compounds in digested sludge - Method by measuring biogas production · ISO 15985

Plastics - Determination of complete anaerobic biodegradability and decomposition under conditions of high-strength anaerobic digestion - Method by analysis of released biogas

ISO 14853

Plastics - Determination of complete anaerobic degradability Plastic materials in an aqueous medium - Method by analysis of the released biogas in the VDI guideline

VDI 4630

Fermentation of organic substances Substrate characterization, sampling, substance data collection, fermentation tests - the guideline VDI provides uniform rules and guidelines for the practice of fermentation tests, this guideline can be used for the first time to achieve comparable, representative test results. The fermentation tests listed in the experimental part were therefore prepared in analogy to VDI 4630.

The proof of the complete anaerobic fermentation of the polymer mixtures according to the invention succeeded in particular with the methods according to ISO 15985 and VDI

4630. The present method is also intended to include test methods other than the

Derive principle, the underlying microorganisms and the concentrations of the microorganisms used in the two above-mentioned test methods.

Due to the simple reproducibility and the significance of the results, the method according to VDI 4630 is particularly preferred. The in the present

The term anaerobic degradability used in the application thus refers primarily to VDI 4630.

The present invention accordingly relates in particular to a process for the complete anaerobic degradation of polymer mixtures of the composition:

From 25 to 95% by weight, based on the components a and b, of a polyhydroxyalkanoate selected from the group consisting of poly-4-hydroxybutyrates, poly-3-hydroxybutyrates, poly (3-hydroxybutyrates-co-3-hydroxyvalerates) , Poly (3-hydoxybutyrate-co-3-hydroxyhexanoate and poly (3-hydroxybutyrate-co-4-hydroxybutyrate) and

From 5 to 75% by weight, based on the components a and b, of an aliphatic-aromatic polyester comprising: i) from 65 to 95 mol%, based on the components i to ii, of one or more C5-C36 dicarboxylic acid derivatives or C5- C36-dicarboxylic acids; ii) from 35 to 5 mol%, based on the components i to ii, of a terephthalic acid derivative or a terephthalic acid; iii) from 98 to 100 mol%, based on components i to ii, of a C 2 -C 8 -alkylenediol or C 2 -C 6 -oxyalkylenediol; iv) from 0 to 2% by weight, based on the components i to iii, of at least one polyfunctional compound containing at least two isocyanate, isocyanurate, oxazoline or epoxide groups or at least three alcohol or carboxylic acid groups;

wherein the anaerobic degradation can be determined by means of one of the methods according to VDI 4630 or ISO 15985. The method according to VDI 4630 is particularly preferred as mentioned above.

The inoculum used in the VDI 4630 was an LUFA sludge. The content of dry matter was 3.7% of the fresh substance, with the ash 1, 8% of the fresh substance (49.5% of the dry matter) and the organic substance (loss on ignition) 1, 9% of the fresh substance (50.5% of Dry matter); the pH was about 7.4 to 7.8.

Under the aforementioned complete anaerobic degradation of the polymer mixtures mentioned is understood that not only the mixture component a (polyhydroxyalkanoate) is degraded, which is already known from the literature, but also the aliphatic-aromatic polyester b.

Under a complete anaerobic degradation, a degradation rate (biogas development measured according to VDI 4630 in 42 days) of the polymer mixture a + b, based on the polymer component a, understood by greater than 70%. Examples of these are listed in Table 1.

The complete anaerobic degradation of polymer blends with a high content of polymer component a greater than 70% and in particular greater than 90%, is determined as follows. It is assumed that the proportion of the polymer component a is degraded to 100%. The experimentally determined amount of biogas is deducted from the amount of biogas formed and the excess attributed to the degradation of the polymer component b. From this value, it is possible to check, based on the above tabulated values, whether component b has degraded to greater than 90%.

For polymer blends containing 80 wt .-% or more polymer component b, based on the components a and b, are not completely degraded according to the above criteria. As already mentioned, the polymer component b as a pure substance is not degraded at all anaerobically.

The abovementioned biodegradable polyester mixtures are suitable for the production of films and film tapes for nets and fabrics, tubular films, chill-roll Films with and without orientation in a further process step, with and without metallization or SiOx coating suitable. With regard to the degradation behavior, layer thicknesses of the films of 5 to 45 μm and in particular of 10 to 30 μm are advantageous.

In particular, the films containing the polymer components a) and b) are suitable for tubular films and stretch films. Possible applications here are bottom folding bags, side seam bags, carrying bags with handle holes, shrink labels or shirt carrier bags, inliners, heavy bags, freezer bags, composting bags, agricultural films (mulch films), film bags for food packaging, removable sealing film - transparent or opaque - weldable sealing film - transparent or opaque -, sausage casing, salad foil, plastic wrap (stretch film) for fruit and vegetables, meat and fish, stretch wrap for wrapping pallets, foil for nets, packaging foils for snacks, chocolate and muesli bars, peelable lid foils for dairy packs (yoghurt, cream, etc.) ), Fruits and vegetables, semi-hard packaging for smoked sausage and cheese.

Due to their barrier properties against oxygen and aromas, which are outstanding for biodegradable films, the films mentioned are predestined for packaging meat, poultry, meat products, processed meat, sausages, smoked sausages, seafood, fish, crabmeat, cheese, cheese products, desserts, patties, etc. , With meat, fish, poultry, tomato stuffing, pastes and spreads; Bread, cakes, other baked goods; Fruit, fruit juices, vegetables, tomato paste, salads; Pet food; pharmaceutical products; Coffee, coffee-based products; Milk or cocoa powder, coffee whitener, baby food; dried foods; Jams and jellies; Spreads, chocolate cream; Ready meals. For more information, see reference in "Food Processing Handbook," James G. Brennan, Wiley-VCH, 2005. The films also have very good adhesion properties, making them ideal for paper coating, such as paper cups and paper plates A combination of these methods or a coating by spraying, knife coating or dipping is conceivable.

In many countries biogood, which includes biowaste, green waste, expired and inedible food, trays, stalks, etc. of so-called domestic waste, as well as waste, residues in the cultivation of food and in the production of food, disposed of in landfills. When rotting in landfills, significant amounts of methane, a harmful greenhouse gas, enter the atmosphere unhindered. Combustion of the biogas is also a problem due to its high water content and the associated poor energy balance. burning is not a good alternative. Disposal of the biogas in composting facilities, and biogas plants in particular (additional biogas that can be used as an energy source), is the best solution of total eco-balance. So far, the biogood has often been collected using paper bags or newsprint that are easily soaked, collected, or collected Hygienic and breathable packaging such as garbage bags or packaging for food are used, but are not degraded in biogas plants under the prevailing anaerobic conditions there. With the present polymer blends packaging (for food and waste bags for organic waste) can be provided for the first time, which allow the disposal together with the biogood collected in a biogas plant. In municipalities that dispose of a biogas plant, the following process is an extremely interesting alternative:

A method of disposing of biogas in a biogas plant, comprising, in a first step, the biogas in a package containing polymer blends of the composition: a) from 25 to 95% by weight of a polyhydroxyalkanoate selected from the group consisting of poly-4-hydroxybutyrate, Poly-3-hydroxybutyrate, poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3-hydroxyhexanoate and poly (3-hydroxybutyrate-co-4-hydroxybutyrate) and b) 5 to 75 wt % of an aliphatic polyester containing:

Iii) 98 to 100 mol%, based on the components i to ii, of a C 2 -C 8 -alkylenediol or C 2 -C 6 -oxyalkylenediol; iv) from 0 to 2% by weight, based on the components i to iii, of at least one polyfunctional compound containing at least two isocyanate, isocyanurate, oxazoline or epoxide groups or at least three alcohol or carboxylic acid groups; is collected or bottled, in a second step, the biogas is collected in this packaging by a disposal company and in a third Step the biogas is supplied in this packaging of anaerobic fermentation in a biogas plant.

Application-technical measurements:

The molecular weights Mn and Mw of the partially aromatic polyesters were determined in accordance with DIN 55672-1. Eluent hexafluoroisopropanol (HFIP) + 0.05% by weight of trifluoroacetic acid Ka salt; The calibration was carried out with narrowly distributed polymethyl methacrylate standards. The determination of the viscosity numbers was carried out according to DIN 53728 Part 3, January 3, 1985, capillary viscometry. A micro Ubbelohde viscometer, type M-II, was used. The solvent used was the mixture: phenol / o-dichlorobenzene in a weight ratio of 50/50. Modulus of elasticity and elongation at break were determined by means of a tensile test according to ISO 527-3: 2003.

The tear strength was determined by an Elmendorf test according to

EN ISO 6383-2: 2004 determined on specimens of constant radius (43 mm crack length).

In a puncture resistance test, the maximum force and the breaking strength of the polyester were measured: The test machine used is a Zwick 1 120 equipped with a spherical punch with a diameter of 2.5 mm. The sample, a circular piece of film to be measured, was clamped perpendicular to the test die and passed through it at a constant test speed of 50 mm / min. Through the plane defined by the jig. During the test, both the force as well as the elongation recorded, thus determining the puncture work.

The anaerobic degradation rates of the biodegradable polyester blends and the blends prepared for comparison were determined as follows:

The experimental set-up and the procedure were carried out analogously to the corresponding method "4.1 .1 Determination of the biogas and methane yield in fermentation tests" from the VDLUFA method book VII (environmental analysis) The reaction vessels (fermenters) used for the determination of the biogas formation potential (anaerobic degradation) 5 l glass container, which could be closed in a gas-tight manner with a butyl septum and a screw cap, and the process temperature was determined by means of a water bath and a thermostat, corresponding to the experimental conditions (meso). phil: 38 ± 1 ° C; thermophilic: 55 ± 1 ° C), kept constant. The mixing of the test mixtures was carried out discontinuously once a day. The contents of the fermenter were inoculum derived from measurements of biogas yields in a batch process and prepared under defined conditions (according to VDI 4630). Deviating from the chosen specifications (VDI 4630), however, the material had an increased dry matter content (TS) of approx. 4.5% (w / v) and an increased proportion of organic dry substance (oTS) of approx. 50% (w / w ). The microorganisms contained were conditioned under anaerobic conditions for a period of 5 weeks before the start of the test without substrate feed. The fermenters were initially filled with 4.5 l of conditioned seed material, 30 g of the corresponding test substance were added (corresponds to a ratio of oTS inoculum to oTS test substance of 3.375: 1 (v / w)), the fermenter sealed gas-tight and the gas phase of the Fermenter substituted with nitrogen. At the start of the test, the resulting biogas was collected in a gas collection bag, which was connected to the gas compartment of the fermenter via gastight hose connections. The volume measurement of the biogas formed was discontinuous, the determination of the gas composition was carried out by IR measurement (CFU, CO2, O2) and by means of electrochemical sensors (H2S) in the gas chromatograph. Starting Materials:

Polymer component a (polyhydroxyalkanoate)

Polyester A1

Poly-3-hydroxybutyrate from PHB-Isa (trade name Biocycle 1000).

Polymer component b (aliphatic-aromatic polyester) Polyester B1 (comparative)

Polybutylene terephthalate adipate (adipic acid: terephthalic acid = 50: 50).

In a 2L four-necked flask, 398.1 g of dimethyl terephthalate (50 mol%), 480.3 g

1, 4-butanediol (130 mol%) and 0.92 g of tetrabutyl orthotitanate (TBOT) and heated under an atmosphere of nitrogen at 190 ° C internal temperature and melted. The melt is constantly stirred. Methanol is split off and distilled off. After about 90 minutes 299.6 g of adipic acid (50 mol%) are added to the melt. The temperature is carefully raised to 200 ° C and the resulting water distilled off. After no more water transfer is observed, the temperature is reduced to 190 ° C. An additional 0.92 g of tetrabutyl orthotitanate (TBOT) is added. Vacuum is applied to the apparatus and the temperature is gradually increased to 220 ° C. In this case, the excess 1, 4-butanediol is distilled off. After reaching the desired final viscosity, the vacuum is broken and the polyester is poured out on a Teflon film.

The polyester B1 thus obtained has a viscosity number of 84 ml / g and a

Melting point of about 129 ° C. The molecular weight (Mn) was 16500, the molecular weight (Mw) was 40500.

Polyester B2 (comparative)

Polybutylene terephthalate adipate (adipic acid: terephthalic acid = 60: 40), prepared analogously to polyester B1

Mp .: 104 ° C

Polyester B3 polybutylene terephthalate adipate (adipic acid: terephthalic acid = 70:30), prepared analogously to polyester B1

Mp .: 73 ° C

Polyester B4

Polybutylene terephthalate adipate (adipic acid: terephthalic acid = 80:20), prepared analogously to polyester B1

Mp .: 35 ° C polyester B5

Polybutylene terephthalate adipate (adipic acid: terephthalic acid = 90:10), prepared analogously to polyester B1

Mp: 44 ° C; 50 ° C

Polyester B6

Polybutylene adipate (adipic acid 100), prepared analogously to polyester B1

Mp .: 60 ° C

Examples:

Comparative Examples 1, 2, 6 to 8 and Examples 3 to 5

The proportions of PHB A1 and polyesters B1 to B6 given in Table 1 were determined on a co-rotating twin-screw extruder FTS 16 (l / d = 25) at a Melting temperature (head zone) of about 170 ° C, a speed of 200 min ^-1 and a throughput of 1, 5 kg / h compounded and extended as extruded granules.

All of the samples listed in Table 1 (Comparative Examples 1, 2, 6 to 8 and Examples 3 to 5) were comminuted for the anaerobic degradation tests with the aid of a baffle plate mill (Pallmann, type PPL 18).

The particle size distribution of the powders was determined randomly with a Mastersizer 2000 from Malvern. For example, for the mixture V1 (50% polybutylene terephthalate adipate (adipic acid: terephthalic acid = 50:50) and 50% PHB), the measured characteristics (d 10/50/90) were 88 μηη / 245 μηη / 538 μηη. For all measured samples the dgo value was below 1000 μηη. This means that 90% by volume of the powder has a particle size of less than 1000 μm.

Table 1 :

Example V1 V2 3 4 5 V6 V7 V8

Comp. A1 50 50 50 50 50 50 - 100

[Wt .-%]

Comp. B1 50

[Wt .-%]

Comp. B2 50

[Wt .-%]

Comp. B3 50

[Wt .-%]

Comp. B4 50

[Wt .-%]

Comp. B5 50

[Wt .-%]

Comp. B6 50 100

[Wt .-%]

Biogas Dev. ^* 484 520 559 653 642 536 18 1004

[L / kg]

Biogas 495 553 620 782 713 583 22 1005

Development ^**

[L / kg]

Biogas 499 571 645 832 733 605 19 1005

Development ^***

[L / kg]

Methane content 58.3 58.7 58.6 58.7 58.8 58.9 - 56.2 in biogas at

trying

[%] ^* Biogas development after 21 days

* ^* Biogas development after 42 days

* ^Biogas development after 56 days The data presented in Table 1 show the biogas yields (CO2 + CH4) of the different polymer mixtures after an incubation period of 21, 42 and 56 days under mesophilic conditions at 38 ° C. In comparative experiments V7 and V8, two individual components of the polymer blends were used in the degradation test. For component A1 (PHB, see V8), biogas development of 1005 L / kg results in complete anaerobic biodegradation already after 14 days. Component B6 (polybutylene adipate, V7) shows no appreciable degradation even after 56 days.

In mixtures with poly-3-hydroxybutyrate, especially under mesophilic conditions in examples 3 to 5, biogas production is significantly above the theoretically expected value (50% PHB in the mixture corresponds to a maximum of 503 L / kg biogas) : + 28%, 4: + 65%, 5: + 45%). This synergistic effect is surprising. The biodegradability of the polymer mixture, which was used in the experiments V1, V2 and V6, is significantly lower in the considered time interval.

Claims

claims

A process for the complete anaerobic degradation of polymer blends of the composition: a) from 25 to 95 weight percent of a polyhydroxyalkanoate selected from the group consisting of poly-4-hydroxybutyrate, poly-3-hydroxybutyrate, poly (3-hydroxybutyrate-co-3-hydroxyvalerate ), Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate and poly (3-hydroxybutyrate-co-4-hydroxybutyrate) and b) 5 to 75 wt% of an aliphatic-aromatic polyester containing: i) 65 to 95 mol% , based on the components i to ii, of one or more C5 to C36 dicarboxylic acid derivatives or C5 to C36 dicarboxylic acids; ii) 35 to 5 mol%, based on the components i to ii, of a terephthalic acid derivative or a terephthalic acid; iii) from 98 to 100 mol%, based on components i to ii, of a C 2 -C 8 -alkylenediol or C 2 -C 6 -oxyalkylenediol; iv) 0 to 2 wt .-%, based on the polymer obtainable from the components i to iii, at least one polyfunctional compound containing at least two isocyanate, isocyanurate, oxazoline or epoxide groups or at least three alcohol or carboxylic acid - Groups.

A method according to claim 1, characterized in that the polymer mixture contains: a) 25 to 50 wt .-% of the polyhydroxyalkanoate and b) 50 to 75 wt .-% of the aliphatic-aromatic polyester. 3. Process according to claim 1, characterized in that the polyhydroxyalkanoate (polymer component a)) is a poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) or a poly (3-hydroxybutyrate) ly (3-hydroxybutyrate-co-4-hydroxybutyrate) is used. A method according to claim 1, characterized in that the polymer mixture as further component c) 5 to 50 wt .-% thermoplasticized starch, based on the total weight of components A to c, are added.

Process for the complete anaerobic degradation of packaging for biogas containing polymer blends of the composition: a) from 25 to 95% by weight of a polyhydroxyalkanoate selected from the group consisting of poly-4-hydroxybutyrate, poly-3-hydroxybutyrate, poly (3-hydroxybutyrate) co-3-hydroxyvalerates), poly (3-hydroxybutyrate-co-3-hydroxyhexanoates and poly (3-hydroxybutyrate-co-4-hydroxybutyrates), and b) 5 to 75 wt% of an aliphatic-aromatic polyester containing: i) 65 to 95 mol%, based on the components i to ii, of one or more C5-C36 dicarboxylic acid derivatives or C5-C36 dicarboxylic acids; ii) 35 to 5 mol%, based on the components i to ii, of a terephthalic acid derivative or a terephthalic acid; iii) from 98 to 100 mol%, based on components i to ii, of a C 2 -C 8 -alkylenediol or C 2 -C 6 -oxyalkylenediol; iv) 0 to 2 wt .-%, based on the polymer obtainable from the components i to iii, at least one polyfunctional compound containing at least two isocyanate, isocyanurate, oxazoline or epoxide groups or at least three alcohol or carboxylic acid - Groups.

A method for disposing of biogas in a biogas plant, comprising, in a first step, the biogas in a packaging containing polymer mixtures of the composition: a) 25 to 95 wt .-% of a polyhydroxyalkanoate selected from the group consisting of poly-4-hydroxybutyrate, poly 3-hydroxybutyrate, poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3-hydroxyhexanoate and poly (3-hydroxybutyrate-co-4-hydroxybutyrate), and b) 5 to 75 wt. % of an aliphatic-aromatic polyester containing: i) 65 to 95 mol%, based on the components i to ii, of one or more C5-C36 dicarboxylic acid derivatives or C5-C36 dicarboxylic acids; ii) 35 to 5 mol%, based on the components i to ii, of a terephthalic acid derivative or a terephthalic acid; iii) from 98 to 100 mol%, based on components i to ii, of a C 2 -C 8 -alkylenediol or C 2 -C 6 -oxyalkylenediol; iv) 0 to 2 wt .-%, based on the polymer obtainable from the components i to iii, at least one polyfunctional compound containing at least two isocyanate, isocyanurate, oxazoline or epoxide groups or at least three alcohol or carboxylic acid -

Groups;

is collected or bottled, in a second step, the biogas is collected in this packaging by a disposal company and in a third step, the biogas is supplied in this packaging of the anaerobic fermentation in a biogas plant.