Polymer preparations for films have a polyether-polyol plasticizing system.

Abstract

The invention relates to a polymer composition comprising aliphatic-aromatic polyesters of high starch or starch derivative content and an improved linear or branched polyether-polyol plasticizer system, particularly suitable for use in the manufacture of films that may be used to make products such as garbage bags, shopping bags, and food packaging.

Description

[0001] POLYMER COMPOSITION FOR FILMS WITH POLYETHER-POLYOL

[0002] PLASTICISATION SYSTEM

[0003] DESCRIPTION

[0004] The present invention relates to a polymer composition with a high starch content or derivatives thereof with an improved plasticisation system particularly suitable for use in the manufacture of films that can be used for the production of products such as waste bags, shopping bags and food packaging.

[0005] Said applications require the use of films characterised by good mechanical properties and high disintegration at low temperatures, which are therefore able to degrade without leading to an accumulation of waste in the environment once their primary use has ended.

[0006] Polymer compositions containing biodegradable polymers, starch and plasticisers are well known in the art, see for example EP2296644.

[0007] Compositions containing biodegradable polyesters, starch and plasticisers such as polyethylene glycols, where the starch contains at least 25% pea starch by weight based on the total dry weight of the starch, are described in WO 2022 / 157380.

[0008] It is well known that starch-containing compositions have a characteristic odour that must be minimised to safeguard possible organoleptic inertness and also because the market demands products that are as 'neutral' as possible with regard to odour.

[0009] It is also known that polymer compositions with a high starch content have a high viscosity, resulting in high pressures during industrial processing and thus reducing productivity.

[0010] CN10899771 describes a masterbatch containing a modified plastic comprising polyetherpolyols that contains a mixture of low-boiling organics to reduce odour.

[0011] Starting from the need to find a balance between processability (understood as a reduction in shear viscosity), mechanical properties and a low odour intensity for the polymer composition, it has now surprisingly been found that it is possible to solve this problem without the use of additional odour-removing agents by means of a polymer composition made of aliphatic- aromatic polyesters and starch and its derivatives, having at least one plasticiser chosen from: linear polyether-polyols with a number of OH terminals of between 200 and 600 mgKOH / g and branched polyether-polyols with a number of OH terminals of between 40 and 1000 mgKOH / g.

[0012] The present invention relates in particular to a polymer composition comprising, in relation to the total dry weight of the composition: i. 40 - 75% by weight, preferably between 40 - 72% by weight and even more preferably between 55 - 70% by weight relative to the sum of components i.-v., of at least one aliphatic -aromatic polyester comprising:

[0013] (a) a dicarboxylic component comprising, in relation to the total dicarboxylic component:

[0014] (al) 30-60% in moles of units derived from at least one aromatic dicarboxylic acid;

[0015] (a2) 70-40% in moles of units derived from at least one saturated aliphatic dicarboxylic acid;

[0016] (a3) 0-5% in moles of units derived from at least one unsaturated aliphatic dicarboxylic acid;

[0017] (b) a diol component comprising, in relation to the total diol component:

[0018] (bl) 95-100% in moles of units derived from at least one saturated aliphatic diol;

[0019] (b2) 0-5% in moles of units derived from at least one unsaturated aliphatic diol; ii. 25 - 60% by weight, preferably between 28-50% by weight and even more preferably between 30-45% by weight relative to the sum of components i.-v., of at least one starch or starch derivatives and at least one plasticiser chosen from among: c. linear polyether-polyols having a number of OH terminals of between 200 and 600 mgKOH / g and d. branched polyether-polyethers having a number of OH terminals of between 40 and 1000 mgKOH / g; iii. 0 - 15% by weight of the sum of components i.-v. of at least one polyhydroxyalkanoate; iv. 0 - 1% by weight, preferably 0 - 0.5% by weight, relative to the sum of components i.-v. of at least one cross-linking agent and / or chain extender and / or stabiliser against hydrolysis; v. 0 - 15% by weight of at least one inorganic filling agent in relation to the sum of components i.-v.

[0020] The term 'total dry weight' in the present invention means the total weight of the respective component without water. This means that the water content of the starch is not taken into account when determining the total dry weight and the respective weight proportions. Shear viscosity is measured at 180°C and flow gradient y =103 ,7s-l with a capillary having a diameter of 1 mm and L / D=30 according to ASTM standard D3835-90; while MFR is measured at 160°C; 5 kg according to ISO standard 1133-1 'Plastics - determination of the melt massflow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method'). Both measurements are carried out on a polymer composition with a water content, measured via Karl-Fischer, of less than 0.6% by weight of the total composition.

[0021] The composition according to the present invention is readily biodegradable under industrial composting conditions according to EN 13432.

[0022] The composition according to the present invention comprises 40 - 75% by weight, preferably 50 - 72% by weight, more preferably 55 - 75% by weight of the total dry weight of the sum of components i.-v., of at least one aliphatic-aromatic polyester i.

[0023] Said aliphatic-aromatic polyesters (component i.) comprise a dicarboxylic component comprising, in relation to the total dicarboxylic component, 30 - 60% in moles, preferably 40 - 55% in moles, even more preferably 44 - 48% in moles of units derived from at least one aromatic dicarboxylic acid (component al), and 70 - 40% in moles, preferably 60 - 45% in moles, even more preferably 56 - 52% in moles of units derived from at least one saturated aliphatic dicarboxylic acid (component a2).

[0024] The aromatic dicarboxylic acids (component al) of the aliphatic -aromatic polyesters i. in the composition according to the present invention are preferably selected from aromatic dicarboxylic acids of the phthalic acid type, preferably terephthalic acid or isophthalic acid, more preferably terephthalic acid, its esters and salts.

[0025] The saturated aliphatic dicarboxylic acids (component a2) of the aliphatic -aromatic polyesters i. are preferably selected from saturated C2-C24, preferably C4-C13, more preferably C4-C11, dicarboxylic acids, their C1-C24, more preferably C1-C4, alkyl esters, their salts and mixtures thereof. Preferably, the saturated aliphatic dicarboxylic acids are selected from: succinic acid, 2-ethylsuccinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, brassilic acid and their C1-C24 alkyl esters.

[0026] Preferably, the saturated dicarboxylic acids are selected from the group consisting of succinic acid, adipic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, brassylic acid and mixtures thereof.

[0027] The dicarboxylic component of the aliphatic -aromatic polyesters of the composition according to the present invention may comprise up to 5% unsaturated aliphatic dicarboxylic acids (component a3), preferably selected from itaconic acid, fumaric acid, 4-methylene-pimelic acid, 3,4-bis (methylene) nonandioic acid, 5-methylene-nonandioic acid, their C1-C24, preferably C1-C4, alkyl esters, their salts and mixtures thereof. In a preferred embodiment of the present invention, the unsaturated aliphatic dicarboxylic acids comprise mixtures comprising at least 50% in moles, preferably more than 60% in moles, more preferably more than 65% in moles of itaconic acid and / or its C1-C24, preferably C1-C4, esters. More preferably, the unsaturated aliphatic dicarboxylic acids comprise itaconic acid.

[0028] The diol component of aliphatic-aromatic polyesters i. in the composition according to the present invention comprises, in relation to the total diol component, 95 - 100% in moles, preferably 97 - 100% in moles, of units derived from at least one saturated aliphatic diol (component bl) and 0 - 5% in moles, preferably 0 - 3% in moles, in relation to the total diol component, of units derived from at least one unsaturated aliphatic diol (component b2).

[0029] The saturated aliphatic diols (component bl) of the aliphatic -aromatic polyesters i. in the composition according to the present invention are preferably selected from 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7- heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11 -undecanediol, 1,12- dodecanediol, 1,13 -tridecanediol, 1,4-cyclohexanedimethanol, neopentylglycol, 2-methyl-l,3- propanediol, dianhydro sorbitol, dianhydromannitol, dianhydroiditol, cyclohexanediol, cyclohexanmethanediol, dialkylene glycols and polyalkylene glycols with molecular weights of 100-4000 such as polyethylene glycol, polypropylene glycol and mixtures thereof. Preferably, the diol component comprises at least 50% in moles of one or more diols chosen from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol. In a preferred embodiment of the present invention the saturated aliphatic diol is 1,4-butanediol.

[0030] The unsaturated aliphatic diols (component b2) of the aliphatic-aromatic polyesters i. in the composition according to the present invention are preferably selected from cis 2-buten-l,4- diol, trans 2-buten-l,4-diol, 2-butyn-l,4-diol, cis 2-penten-l,5-diol, trans 2-penten-l,5-diol, 2- pentyn-1.5-diol, cis 2-hexen-l,6-diol, trans 2-hexen-l,6-diol, 2-hexyn-l,6-diol, cis 3-hexen- 1,6-diol, trans 3-hexen-l,6-diol, 3-hexen-l,6 diol.

[0031] In a preferred embodiment, the aliphatic-aromatic polyesters i. are preferably selected from: poly(l,4-butylene adipate-co-l,4-butylene terephthalate), poly(l,4-butylene succinate-co-1,4- butylene terephthalate), poly(l,4-butylene sebacate-co-l,4-butylene terephthalate), poly(l,4- butylene azelate-co-l,4-butylene terephthalate), poly(l,4-butylene brassylate-co-l,4-butylene terephthalate), poly(l,4-butylene adipate-co-l,4-butylene brassylate-co-l,4-butylene terephthalate), poly(l,4-butylene adipate-co-l,4-butylene sebacate-co-l,4-butylene terephthalate), poly(l,4-butylene undecanoate-co-l,4-butylene terephthalate), poly(l,4- butylene dodecanoate-co-l,4-butylene terephthalate), poly(l,4-butylene azelate-co- 1,4- butylene sebacate-co-l,4-butylene terephthalate), poly(l,4-butylene adipate-co-l,4-butylene azelate-co-l,4-butylene terephthalate), poly(l,4-butylene succinate-co-l,4-butylene sebacate- co-l,4-butylene terephthalate), poly(l,4-butylene adipate-co-l,4-butylene succinate-co-1,4- butylene terephthalate), poly(l,4-butylene azelate-co-l,4-butylene succinate-co-l,4-butylene terephthalate), poly(l,4-butylene azelate-co-l,4-butylene succinate-co-l,4-butylene adipic-co- 1 ,4-butylene terephthalate) , poly( 1 ,4-butylene azelate-co- 1 ,4-butylene succinate-co- 1 ,4- butylene sebacate-co-l,4-butylene adipic-co-l,4-butylene terephthalate).

[0032] In a preferred embodiment, aliphatic-aromatic polyesters i. are preferably selected from: poly(l,4-butylene adipate-co-l,4-butylene terephthalate), poly(l,4-butylene sebacate-co- 1,4- butylene terephthalate) and poly(l,4-butylene azelate-co- 1,4-butylene terephthalate).

[0033] In another preferred embodiment of the invention poly( 1,4-butylene adipate-co- 1,4-butylene azelate-co- 1,4-butylene terephthalate) is mixed with poly( 1,4-butylene adipate-co- 1,4- butylene terephthalate), poly( 1,4-butylene sebacate-co- 1,4-butylene terephthalate) and poly( 1,4-butylene azelate-co- 1,4-butylene terephthalate).

[0034] In an even more preferred embodiment of the invention, poly( 1,4-butylene adipate-co- 1,4- butylene terephthalate) is mixed with poly( 1,4-butylene sebacate-co- 1,4-butylene terephthalate) and poly( 1,4-butylene azelate-co- 1,4-butylene terephthalate).

[0035] In an even more preferred embodiment, aliphatic-aromatic polyester i. is poly( 1,4-butylene adipate-co- 1 ,4-butylene terephthalate) .

[0036] Aliphatic-aromatic polyesters i. may also advantageously comprise repetitive units derived from at least one hydroxy acid in an amount between 0 - 49% preferably between 0 - 30% in moles in relation to the total moles of the dicarboxylic component.

[0037] Examples of convenient hydroxyacids are glycolic acid, hydroxybutyric acid, hydroxycaproic acid, hydroxyvaleric acid, 7 -hydroxy heptanoic acid, 8-hydroxycaproic acid, 9- hydroxynonanoic acid, lactic acid or lactide. The hydroxy acids may be inserted into the chain as such or as prepolymers / oligomers, or they may also be pre-reacted with diacids or diols.

[0038] Long molecules with two functional groups that may also have non-terminal functional groups may also be added, in quantities not exceeding 10% in moles to the total moles of the dicarboxylic component. Examples are dimer acids, ricinoleic acid and acids with epoxy functional groups, and also polyoxyethylenes having molecular weights of between 200 and 10000.

[0039] Diamines, amino acids, and amino-alcohols may also be present in percentages of up to 30% in moles in relation to the total moles of the dicarboxylic component. In the process of preparing the aliphatic -aromatic polyesters i. in the composition according to the present invention, one or more molecules with multiple functional groups may also be advantageously added, in amounts of between 0.1 and 3 moles, to the total moles of the dicarboxylic component (as well as any hydroxy acids), in order to obtain branched products. Examples of these molecules are glycerol, pentaerythritol, trimethylolpropane, citric acid, dipentaerythritol, monoanhydrosorbitol, monohydromannitol, acid triglycerides, poly glycerols, etc. With reference to aliphatic-aromatic polyesters i., Mn and Mw are the number average molecular weight and the weight average molecular weight respectively.

[0040] The molecular weight Mn of aliphatic-aromatic polyester i. is preferably > 20000, more preferably > 40000. As for the poly dispersity index of the molecular weights, Mw / Mn, this is preferably between 1.5 and 10, more preferably between 1.6 and 5 and even more preferably between 1.8 and 2.7.

[0041] Molecular weights Mnand Mwmay be measured by Gel Permeation Chromatography (GPC). The determination may be conducted with the chromatographic system maintained at 40 °C, using a set of two columns in series (particle diameter 5 pm and 3 pm with mixed porosity), a refractive index detector, chloroform as eluent (flow rate 0.5 ml / min) and using polystyrene as reference standard.

[0042] The Melt Flow Rate (MFR) of aliphatic -aromatic polyesters i. is preferably between 500 and 1 g / 10 min, more preferably between 100 and 3 g / 10 min, even more preferably between 15 and 3 g / 10 min (measured at 190°C / 2.16 kg according to ISO 1133-1 'Plastics - determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method').

[0043] The terminal acid group content of aliphatic-aromatic polyester i. is preferably less than 100 meq / kg, preferably less than 60 meq / kg and even more preferably less than 40 meq / kg. The terminal acid groups content may be measured as follows: 1.5-3 g of the polyester is placed in a 100 ml conical flask together with 60 ml of chloroform. After complete dissolution of the polyester, 25 ml of 2-propanol is added and, immediately before analysis, 1 ml of deionised water. The resulting solution is titrated with a previously standardised solution of NaOH in ethanol. An appropriate indicator, such as a glass electrode for acid-base titrations in non-aqueous solvents, is used to determine the equivalence point of the titration. The content of terminal acid groups is calculated on the basis of the consumption of NaOH solution in ethanol according to the following equation: Terminal acid groups content (meq / kg of polymer) = (Vea- 14).71, 1000 P where: Veq = ml of NaOH solution in ethanol at the equivalence point of the sample titration; Vb = ml of NaOH solution in ethanol required to achieve pH = 9.5 during a blank titration;

[0044] T = concentration of NaOH solution in ethanol expressed in moles / litre;

[0045] P = weight of sample in grams.

[0046] Preferably, aliphatic -aromatic polyester i. has an inherent viscosity (measured with a Ubbelohde viscometer for solutions in CHC13 of concentration 0.2 g / dl at 25 °C) greater than 0.3 dl / g, preferably between 0.3 and 2 dl / g, more preferably between 0.4 and 1.1 dl / g.

[0047] Preferably the aliphatic-aromatic polyester i. is biodegradable. For the purposes of the present invention, a biodegradable polymer is understood to be a polymer that is biodegradable according to EN 13432.

[0048] Said aliphatic -aromatic polyester i. may be synthesised according to any of the processes known in the state of the art. In particular, it may be advantageously obtained by a polycondensation reaction.

[0049] Advantageously, the process of synthesis may be conducted in the presence of a suitable catalyst. Examples of suitable catalysts include organometallic tin compounds, for example stannic acid derivatives, titanium compounds, for example ortho-butyl titanate, aluminium compounds, for example triisopropyl aluminium, antimony and zinc and zirconium compounds and mixtures thereof.

[0050] Examples of processes of synthesis that may advantageously be used for the preparation of polyesters are described in international patent application WO 2016 / 050963.

[0051] The expression “high starch content” in the present invention means that the composition comprises 25 - 60% by weight, preferably 28 - 50% by weight, more preferably 30 - 45% by weight of the total dry weight of the sum of components i.-v., at least one starch or starch derivatives and at least one plasticiser (component ii.).

[0052] The term “starch or starch derivatives” is understood here to mean all types of starch, i.e. flour, native starch, hydrolysed starch, destructured starch, gelatinised starch, plasticised starch, thermoplastic starch, biofillers comprising complexed starch or mixtures thereof. Particularly suitable according to the invention are starches such as potato, maize, tapioca and pea starch. Particularly advantageous are starches that can be easily deconstructed and have high initial molecular weights, such as maize starch, pea starch or mixtures thereof. The starch may be present both as such and in a chemically modified form, such as in the form of starch esters with a degree of substitution between 0.2 and 2.5, hydroxypropyl starch, and starch modified with fat chains.

[0053] By unstructured starch we refer here to the teachings in EP-0 118240 and EP-0 327 505, meaning starch processed in such a way that it does not substantially show the so-called “Maltese crosses” under the optical microscope in polarised light and the so-called “ghosts” under the optical microscope in phase contrast.

[0054] Advantageously, the destructuring of starch is carried out by an extrusion process at temperatures between 110-250°C, preferably 130-180°C, pressures between 0.1-7 MPa, preferably 0.3-6 MPa, preferably providing a specific energy of more than 0.1 kWh / kg during said extrusion.

[0055] Component (ii) comprises, in addition to starch or its derivatives, at least one plasticiser, which is chosen from among: c. linear polyether-polyols having a number of terminal OH groups of between 200 and 600 mgKOH / g and d. branched polyether-polyols having a number of OH terminals between 40 and 1000 mgKOH / g

[0056] In a particularly preferred aspect of the invention, linear polyether-polyols having a number of OH terminals of between 200 and 600 mgKOH / g are used.

[0057] The number of OH terminals is determined using the ASTM El 899 standard.

[0058] By branched polyethers are meant products characterised by the presence of at least three units in the chain:

[0059] (-Rl-CHR2-O-)n H where

[0060] R1 is an aliphatic chain consisting of one or two methylene groups (-CH2 -) or CH2 -CH2);

[0061] R2 is selected from H and CH3 and n >l; in which said units are joined via an ether bond to a polyol having three or more hydroxyl -OH functional groups.

[0062] Preferably n is an integer between 1 and 30, even more preferably between 1 and 10.

[0063] Examples of preferred linear polyether-polyols are polyethylene glycol having a molecular weight of 300 (PEG300), poly tetramethylether having a molecular weight of 250 (PolyTHF250) and trimethylpropane ethoxylate 1000 (TMPE1000).

[0064] The linear and / or branched polyether-polyols are in concentrations of between 0.5% and 10.0%, preferably between 3.0% and 8.5% in relation to the starch or its derivatives. The plasticiser containing linear or branched polyether-polyols may also comprise an additional plasticiser chosen from glycerol, diglycerol, poly glycerol, pentaerythritol, 1,4- butanediol, neopentylglycol, sorbitol, sorbitol monoethoxylate, sorbitol diethoxylate. Preferably the additional plasticiser is chosen from sorbitol, sorbitol monoethoxylate and sorbitol diethoxylate.

[0065] The concentration of the plasticiser in the composition according to the invention is determined by HPLC.

[0066] An accurately weighed sample of approximately 500 mg is extracted with 50 ml of water in an oven at 70°C for 12 hours. The resulting solution is subsequently diluted with 83% / 17% ACN / H2O and filtered through filters having a porosity of 0.2 pm.

[0067] The analysis is performed by HPLC using an Agilent 1260 instrument equipped with a universal ELSD (evaporative light scattering detector) and a HILIC-type HPLC column with amine functionality (for example Asahipak NH2P-50 2D). Chromatographic conditions: column thermostatted at 30°C, mobile phase 83% / 17% ACN / H2O, isocratic mode, flow rate of 0.2 ml / min, injection valve loop set at 20pl.

[0068] Quantification is by means of the peak area attributable to the plasticiser and the calibration line constructed for each individual plasticiser. This calibration line is constructed by analysing solutions of the plasticiser in the mixture 83% / 17% v / v ACN / H2O in a dynamic range indicatively between 5 pg / ml and 50 pg / ml.

[0069] In addition to components i. and ii., the composition according to the present invention comprises 0 - 15% by weight, preferably 0.1-8% by weight, more preferably 0.1-6% by weight of the total dry weight of the sum of components i.-v., of at least one polyhydroxyalkanoate (component iii.)

[0070] Said polyhydroxyalkanoate is preferably selected from the group consisting of polyesters of lactic acid, poly-s-caprolactone, polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate -propanoate polyhydroxybutyrate-hexanoate, polyhydroxybutyratedecanoate, polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-hexadecanoate, polyhydroxybutyrate-octadecanoate, poly 3-hydroxybutyrate-4-hydroxybutyrate.

[0071] In a preferred embodiment component iii. is formed from one or more lactic acid polyesters. The lactic acid polyesters are selected from the group consisting of poly L-lactic acid, poly D- lactic acid, poly D-L lactic acid stereo complex, copolymers comprising more than 50% in moles of said lactic acid polyesters or mixtures thereof.

[0072] In the composition according to the present invention there may also be present 0 - 1%, more preferably 0 - 0.5% by weight in relation to the total dry weight of the sum of components i.- v., of at least one cross-linking agent and / or chain extender and / or stabiliser (component iv.) to improve the stability to hydrolysis.

[0073] This crosslinking agent and / or chain extender is selected from di- and / or polyfunctional compounds bearing isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride, divinyl ether groups and mixtures thereof.

[0074] Especially preferred are mixtures of di- and / or polyfunctional compounds bearing isocyanate groups with di- and / or polyfunctional compounds bearing epoxide groups, even more preferably comprising at least 75% by weight of di- and / or polyfunctional compounds bearing isocyanate groups.

[0075] Preferably, the di- and polyfunctional compounds bearing isocyanate groups are selected from p-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4- diphenylmethane diisocyanate, l,3-phenylene-4-chloro diisocyanate, 1,5 -naphthalene diisocyanate, 4,4-diphenylene diisocyanate, 3,3'-dimethyl-4,4-diphenylmethane diisocyanate, 3-methyl-4,4'-diphenylmethane diisocyanate, diphenylether diisocyanate, 2,4-cyclohexane diisocyanate, 2,3 -cyclohexane diisocyanate 1 -methyl 2,4-cyclohexyl diisocyanate, 2,6- cyclohexyl diisocyanate, bis(isocyanate cyclohexyl) methane, 2,4,6-toluene triisocyanate, 2,4,4-diphenylether triisocyanate, polymethylene -polyphenyl-polyisocyanates, methylene diphenyl diisocyanate triphenylmethane triisocyanate, 3,3'dithiolylene-4,4-diisocyanate, 4,4'- methylenebis(2-methylphenyl isocyanate), hexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate and mixtures thereof.

[0076] In a preferred embodiment, the compound bearing isocyanate groups is 4,4-diphenylmethane- diisocyanate.

[0077] With regard to di- and polyfunctional compounds bearing peroxide groups, these are preferably selected from benzoyl peroxide, lauroyl peroxide, isononanoyl peroxide, di(t- butylperoxyisopropyl)benzene, t-butyl peroxide, dicumyl peroxide, alpha, alpha'-di(t- butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butyl cumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hex-3-yne, di(4-t- butylcyclohexyl)peroxy dicarbonate, dicetyl peroxydicarbonate, dimirystyl peroxydicarbonate, 3,6,9-triethyl-3,6,9-trimethyl-l,4,7-triperoxonane, di(2-ethylhexyl) peroxydicarbonate and mixtures thereof.

[0078] The di- and polyfunctional compounds bearing carbodiimide groups which are preferably used in the composition according to the present invention are chosen from poly(cyclooctylene carbodiimide), poly(l,4-dimethylenecyclohexylene carbodiimide), poly(cyclohexylene carbodiimide), poly(ethylene carbodiimide) poly(butylene carbodiimide), poly(isobutylene carbodiimide), poly(nonylene carbodiimide), poly(dodecylene carbodiimide), poly(neopentylene carbodiimide), poly(l,4-dimethylene phenylene carbodiimide), poly(2, 2', 6, 6', tetraisopropyldiphenylene carbodiimide) (Stabaxol® D), poly(2,4,6- triisolpropyl-l,3-phenylene carbodiimide) (Stabaxol® P-100), poly(2,6-diisopropyl-l,3- phenylene carbodiimide) (Stabaxol® P), poly(tolyl carbodiimide), poly(4,4'- diphenylmethane carbodiimide), poly(3,3'-dimethyl-4,4'biphenylene carbodiimide), poly(p-phenylene carbodiimide), poly(m-phenylene carbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethane carbodiimide), poly(naphthylene carbodiimide), poly(isophorone carbodiimide), poly(cumene carbodiimide), p-phenylene bis(ethylcarbodiimide), 1,6-hexamethylene bis(ethylcarbodiimide), 1,8-octamethylene bis(ethylcarbodiimide), 1,10-decamethylene bis(ethylcarbodiimide), 1,12 dodecamethylene bis(ethylcarbodiimide) and mixtures thereof. Examples of di- and polyfunctional compounds bearing epoxide groups which may be advantageously used in the composition according to the present invention are all polyepoxides from epoxidised oils and / or styrene - glycidyl ether-methyl methacrylate, glycidyl ethermethyl methacrylate, included in a molecular weight range between 1000 and 20000 and with a number of epoxides per molecule in the range from 1 to 40 and preferably between 5 and 35, and epoxides selected from the group comprising: diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, poly glycerol poly glycidyl ether, 1,2-epoxybutane, poly glycerol poly glycidyl ether, isoprene diepoxide, and cycloaliphatic diepoxides, 1,4- cyclohexanedimethanol diglycidyl ether, glycidyl 2-methylphenyl ether, glycerol propoxylatotriglycidyl ether, 1,4-butanediol diglycidyl ether, sorbitol poly glycidyl ether, glycerol diglycidyl ether, tetraglycidyl ether of meta-xylenediamine and diglycidyl ether of bisphenol A and mixtures thereof.

[0079] Along with the di- and polyfunctional compounds bearing isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride, divinyl ether groups such as those described above, catalysts may also be used to increase the reactivity of the reactive groups. In the case of polyepoxides, fatty acid salts are preferably used, even more preferably calcium and zinc stearates.

[0080] In a particularly preferred embodiment of the invention, the crosslinking agent and / or chain extender comprises compounds bearing isocyanate groups, preferably 4,4-diphenylmethane- diisocyanate, and / or those bearing carbodiimide groups, and / or bearing epoxide groups, preferably of the styrene - glycidylether methylmethacrylate type.

[0081] In addition to components i-iv. of the composition according to the invention, there is present 0 - 15% by weight in relation to the total dry weight of the sum of components i.-v. of at least one inorganic filler (component v.), which is preferably selected from kaolin, barytes, clay, talc, calcium and magnesium carbonates, iron and lead carbonates, aluminium hydroxide, diatomaceous earth, aluminium sulfate, barium sulfate, silica, mica, titanium dioxide, wollastonite. In a preferred embodiment of the present invention, the inorganic filler comprises talc, calcium carbonate or mixtures thereof, present in the form of particles having an arithmetic mean diameter, measured taking the major axis of the particle into account, of less than 10 microns.

[0082] In addition to the above-mentioned components, the composition according to the present invention preferably also contains at least one further component selected from the group consisting of UV-stabilisers, lubricants, nucleating agents, surfactants, antistatic agents, pigments, flame-retardant agents, compatibilising agents, lignin, organic acids, antioxidants, anti-mould agents, waxes and process aids.

[0083] Preferably, the lubricants are chosen from esters and metal salts of fatty acids such as, for example, zinc stearate, calcium stearate, aluminium stearate and acetyl stearate. Preferably, the composition according to the present invention comprises up to 1% by weight of lubricants, more preferably up to 0.5% by weight, relative to the total weight of the composition.

[0084] Examples of nucleating agents include saccharin sodium salt, calcium silicate, sodium benzoate, calcium titanate, boron nitride, isotactic polypropylene, low molecular weight PLA. Process aids are, for example, biodegradable fatty acid amides such as oleamide, erucamide, ethylene-bis-stearylamide, fatty acid esters such as glycerol oleates or glycerol stearates, saponified fatty acids such as stearates.

[0085] These additives are preferably added in quantities of up to 3% by weight and more preferably between 0.1 and 1% by weight, relative to the total weight of the composition.

[0086] Pigments may also be added if necessary, for example titanium dioxide, clays, copper phthalocyanine, titanium dioxide, silicates, iron oxides and hydroxides, carbon black, and magnesium oxide. These additives are preferably added up to 2-3% by weight.

[0087] The film made with the composition according to the present invention advantageously has a thickness of less than 40 pm, preferably less than 30 pm, even more preferably less than 15 pm. EXAMPLES:

[0088] Example 1 - Preparation of biodegradable polyesters and table of compositions used i-1: Poly(l,4-butylene adipate-co-l,4-butylene terephthalate) ["PBAT"], with a content of 47% in moles of terephthalic acid in relation to the total bicarboxylic component. Said PBAT is characterised by an MFR of 4.1 g / lOmin (at 190°C, 2.16 kg), a shear viscosity at 180°C of 1298 Pas, a melt strength of 1.1 g and a terminal acid group content of 38 meq / kg. i-2: Poly(l,4-butylene adipate-co-butylene azelaic acid-co-l,4-butylene terephthalate ["PBATAz"], with a molar content of azelaic acid of 40% with respect to the sum of azelaic acid and adipic acid, and with a content of 47% in moles of terephthalic acid in relation to the total bicarboxylic component. Said PBATAz is characterised by an MFR of 4.1 g / lOmin (at 190°C, 2.16 kg), a shear viscosity at 180°C of 1298 Pas, a melt strength of 1.1 g and a terminal acid group content of 38 meq / kg. ii: native maize starch (water content 12.1%). ii-al: Polyethylene glycol with an average molecular weight of 200 g / mol, and number of OH terminals of 565 mg KOH / g ["PEG200"]. ii-a2: Polyethylene glycol with an average molecular weight of 300 g / mol and number of OH terminals of 365 mg KOH / g ["PEG300"]. ii-a3: Polyethylene glycol with an average molecular weight of 400 g / mol, number of OH terminals of 287 mg KOH / g ["PEG400"]. ii-a4: Polytetrahydrofuran with a number of OH terminals of 492 mg KOH / g ["PolyTHF250"]. ii-bl: Trimethylolpropane ethoxylate 1000 with a number of OH terminals of 161 mg KOH / g ["TMPE1000"]. cl: Sorbitol solution with 30% water by weight. c2: Polyglycerol solution with 10% water by weight. c3: Polyethylene glycol with an average molecular weight of 600 g / mol and a number of OH terminals of 188 mg KOH / mg ["PEG600"]. c4: Polytetrahydrofuran with a number of OH terminals of 167 mg KOH / g ["PolyTHF650"]. A: Water added in recipe ['H2O']. iii-1 : polylactic acid ['PLA'] Luminy LX175, MFR (190°C and 2.16Kg) = 3.5 / 10min . iv-1: a polyfunctional compound containing epoxide groups, containing styrene units and glycidyl methacrylate with a molecular weight Mw of approximately 14000 and a number of 33 epoxides per molecule. iv-2: HMV-15CA Carbodilite manufactured by Nisshinbo Chemical Inc.

[0089] Table 1.1 Compositions (1)

[0090]

[0091] Table 1.2 Compositions (2)

[0092] Table 1.3 Compositions (3)

[0093] Table 1.4 Compositions (4)

[0094] In all compositions, 0.25 per cent by weight of a process aid (erucamide Chromamide ER) was added to the sum of all components

[0095] The different compositions were fed to a OMC EBV60 / 36 model twin-screw extruder operating under the following conditions:

[0096] Screw diameter (D) = 58 mm;

[0097] L / D = 36;

[0098] Screw rotation = 160 rpm;

[0099] Temperature profile = 60-150-180-210x4-150x2 °C;

[0100] Capacity: 46 kg / h;

[0101] Vacuum degassing in zone 8 out of 10

[0102] The resulting materials taken at the exit from the extruder were characterised by a water content of less than 1% by weight measured by Karl-Fischer.

[0103] The resulting granules were fed to a Ghioldi model blown film machine with a 40mm diameter screw and L / D 30 operating at 64 rpm with a 120- 145x3- 145°C thermal profile. The filmforming head with a 0.9mm air gap and L / D 12 was set at 170°C.

[0104] Films from compositions 3, 8, 9, 10, 3 conf and 4 conf were formed using a blowing ratio of 3.2 and a stretching ratio of 12.4. This resulted in a fdm thickness of 23 pm.

[0105] Films from composition 11, 12, 13 and 14 conf were formed using a blowing ratio of 3.2 and a stretching ratio of 20.4. This resulted in a film thickness of 14 pm.

[0106] Shear viscosity was determined at 180 °C and flow gradient y =103.7s- 1 with a capillary of diameter 1 mm and L / D=30 according to ASTM standard D3835-90. The MFR was determined at 160°C; 5 kg according to ISO 1133-1 “Plastics - determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method”). Both measurements were carried out on granules characterised by a water content of less than 0.6% by weight of the total composition, measured via Karl-Fischer.

[0107] The hydroxyl number of the polyether-polyols was determined according to ASTM DI 899- 16 by performing the potentiometric titration with a Metrohm 855 robo sampler.

[0108] Water vapour permeability was determined at 38 °C and 90% relative humidity according to ASTM F1249.

[0109] Example 2 Comparison of experimental data for the compositions described above

[0110] Table 2.1 Comparison of the shear viscosity of the composition.

[0111] The results from Table 2.1 show that compositions comprising linear and branched polyetherpolymers according to the invention improve processability in that they reduce viscosity.

[0112] Table 2.2 Water vapour permeability comparison.

[0113] The increase in WVTR confirms the positive reduction in weight (water content) of the organic fraction present in the bag with both economic and sensory advantages (waste with less water, therefore more stable and with less odour). Table 2.3 Comparison of plasticisation effect and mechanical properties

[0114] It can be seen from Table 2.3 that the use of PEG 600 (composition 3conf) makes the sample tear readily.

[0115] Table 2.4 Comparison of plasticisation effect and mechanical properties It can be seen from Table 2.4 that the fluidising effect works even without the addition of a lactic acid polyester in the composition.

[0116] Example 3 - Film smell test

[0117] Smell tests were conducted on the compositions in Table 1.4. Composition 13 contained component ii-al (PEG200) and is characterised by a viscosity of 1842 Pas and an MFR of 3.3 g / lOmin, while composition 5 conf, characterised by a viscosity of 1780 Pas and an MFR of 3.1 g / lOmin, contained an aqueous solution of polyglycerol (c2) as plasticiser.

[0118] The smell test was conducted according to UNI 10192:2000: “Procedures for the evaluation of any organoleptic defect arising to food from contact with packaging - olfactory tests, method C (scoring test)”.

[0119] The results are shown in Table 5.

[0120] Table 3.1 Organoleptic test results (smell test).

[0121] As may be seen, the product containing a linear polyether-polyol achieved an average value of half that of the comparison composition.

Claims

CLAIMS1) Polymer composition comprising, in relation to the total dry weight of the composition: i. 40 - 75% by weight, preferably between 50 and 72% by weight, more preferably between 55 and 70% by weight with respect to the sum of components i.-v., of at least one aliphatic-aromatic polyester comprising:(a) a dicarboxylic component comprising, in relation to the total dicarboxylic component:(al) 30-60% in moles of units derived from at least one aromatic dicarboxylic acid;(a2) 70-40% in moles of units derived from at least one saturated aliphatic dicarboxylic acid;(a3) 0-5% in moles of units derived from at least one unsaturated aliphatic dicarboxylic acid;(b) a diol component comprising, in relation to the total diol component:(bl) 95-100% in moles of units derived from at least one saturated aliphatic diol;(b2) 0-5% in moles of units derived from at least one unsaturated aliphatic diol; ii. 25 - 60% by weight, preferably between 28 and 50% by weight, more preferably between 30 and 45% by weight of the sum of components i.-v., of at least one starch or starch derivative and at least one plasticiser chosen from: a. linear polyether-polyols with a number of OH terminals between 200 and 600 mgKOH / g and b. branched polyether-polyols with a number of OH terminals between 40 and 1000 mgKOH / g; iii. 0 - 15% by weight of the sum of components i.-v. of at least one polyhydroxyalkanoate; iv. 0 - 1% by weight, preferably 0 - 0.5% by weight, of the sum of components i.-v. of at least one cross-linking agent and / or chain extender; v. 0 - 15% by weight of at least one inorganic filler in relation to the sum of components i.-v.2) Polymer composition according to claim 1 in which the branched polyether-polyols are characterised by the presence in the chain of at least three(-Rl-CHR2-O-)nH units, where: R1 is an aliphatic chain consisting of one or two methylene groups (-CH2-) or (CH2-CH2); R2 is selected from H and CH3, andn >l; in which these units are joined via an ether bond to a polyol having 3 or more hydroxyl -OH functional groups.3) Polymer composition according to claim 2, characterised in that said initiator monomers are selected from the group consisting of glycerine, trimethylpropane, sorbitol.4) Polymer composition according to claim 1 , in which the linear and / or branched polyetherpolyols are in a concentration of between 0.5% and 10.0%, preferably between 3.0% and 8.5% with respect to the starch or its derivatives.5) Polymer composition according to any one of the preceding claims, in which the plasticiser containing linear or branched polyether-polyols also comprises an additional plasticiser selected from glycerol, diglycerol, poly glycerol, pentaerythritol, 1,4- butanediol, neopentylglycol, sorbitol, sorbitol monoethoxylate, sorbitol diethoxylate.6) Polymer composition according to any of the preceding claims, in which the starch of component (ii) is starch from maize, pea or mixtures thereof.