HIGH-DISINTEGRATION MULTILAYER BIODEGRADABLE FILM

Abstract

Multilayer biodegradable film particularly suitable for use in the manufacture of packaging, comprising at least one layer (A) comprising at least one aliphatic-aromatic biodegradable polyester blended with an aliphatic polyester having at least 70% in moles of succinic acid, and at least one layer (B) comprising a polymer composition comprising an aliphatic-aromatic polymer. The film has high mechanical properties, in particular a high elastic modulus, and appreciable optical transparency properties.

Claims

1. A multilayer film comprising at least a first layer A and at least a second layer B, wherein the layer A comprises: i) 97-60% by weight, with respect to the sum of the i.-v. components, of at least one aliphatic-aromatic polyester which comprises: a) a dicarboxylic component comprising, with respect to the total of the dicarboxylic component: a1) 30-70% by moles of units deriving from at least one aromatic dicarboxylic acid; a2) 70-30% by moles of units deriving from at least one saturated aliphatic dicarboxylic acid; a3) 0-5% by moles of units deriving from at least one unsaturated aliphatic dicarboxylic acid; b) a diol component comprising, with respect to the total diol component: b1) 95-100% by moles of units deriving from at least one saturated aliphatic diol; b2) 0-5% by moles of units deriving from at least one unsaturated aliphatic diol. ii) 3-40% by weight, with respect to the sum of the i.-v. components, of at least one aliphatic polyester which includes: c) a dicarboxylic component comprising with respect to the total of the dicarboxylic component: c1) 70-97% by moles of units deriving from succinic acid; c2) 3-30% by moles of units deriving from at least one saturated dicarboxylic acid other than succinic acid; d) a diol component comprising, with respect to the total diol component: d1) 95-100% by moles of units deriving from at least one saturated aliphatic diol; d2) 0-5% by moles of units deriving from at least one unsaturated aliphatic diol; iii)0-37% by weight, with respect to the sum of the i.-v. components, of at least one polyhydroxyalkanoate; iv)0-10% by weight, with respect to the sum of the i.-v. components, of at least one inorganic filling agent. v) 0-5% by weight, with respect to the sum of the i.-v. components, of at least one crosslinking agent and/or a chain extender comprising at least one di- and/or polyfunctional compound bearing groups selected from isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride, divinylether and mixtures thereof, with the proviso that if component iii. is 0 the component iv must be greater than 0 and component (i) must be between 96.9% and 60% with respect to the i.-v. components; and in which layer B comprises: vi)99.9-50% by weight, with respect to the sum of the components vi.-x., of at least one aliphatic-aromatic polyester comprising: e) a dicarboxylic component comprising, with respect to the total of the dicarboxylic component: e1)30-70% by moles of units deriving from at least one aromatic dicarboxylic acid; e2)70-30% by moles of units deriving from at least one saturated aliphatic dicarboxylic acid; e3)0-5% by moles of units deriving from at least one unsaturated aliphatic dicarboxylic acid; f) a diol component comprising, with respect to the total diol component: f1)95-100% by moles of units deriving from at least one saturated aliphatic diol; f2) 0-5% by moles of units deriving from at least one unsaturated aliphatic diol; vii) 0.1-50% by weight with respect to the sum of the components vi.-x., of at least one polymer of natural origin; viii)0-40% by weight with respect to the sum of the components vi.-x., of at least one polyhydroxyalkanoate; ix) 0-15% by weight with respect to the sum of the components vi.-x., of at least one inorganic filling agent; x) 0-5% by weight, with respect to the sum of the components vi.-x., of at least one crosslinking agent and/or a chain extender comprising at least one di- and/or polyfunctional compound bearing groups selected from isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride, divinyl ether and mixtures thereof.

2. The multilayer film according to claim 1 wherein the aromatic dicarboxylic acids in component a1 are selected from aromatic dicarboxylic acids of the phthalic acid type, and heterocyclic dicarboxylic aromatic compounds, their esters, salts and mixtures.

3. The multilayer film according to claim 2 wherein the aromatic dicarboxylic acids comprise: from 1 to 99% by moles of terephthalic acid, its esters or salts; from 99 to 1% by moles of the 2,5-furandicarboxylic acid, its esters or salts.

4. The multilayer film according to claim 1 in which the saturated aliphatic dicarboxylic acids in component a2 are selected from saturated C2-C24 dicarboxylic acids, their C1-C24 alkyl esters, their salts and their mixtures.

5. The multilayer film according to claim 4 wherein 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, undecanedioic acid, dodecanedioic acid, brassylic acid, acid, octadecanedium acid and their C1-C24 alkyl esters.

6. The multilayer film according to claim 5 wherein the saturated aliphatic dicarboxylic acid comprises mixtures comprising at least 50% in moles of succinic acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, their C1-C24 alkyl esters, their salts and mixtures thereof.

7. The multilayer film according to claim 1 wherein component ii. of layer A comprises from 3 to 30% by weight with respect to the sum of the i.-v. components, of an aliphatic polyester comprising a dicarboxylic component comprising, with respect to the total of the dicarboxylic component, from 70-97% by moles of units deriving from succinic acid.

8. The multilayer film according to claim 1 in which the saturated aliphatic dicarboxylic acids other than succinic acid in component c2 are selected from the saturated dicarboxylic acids C5-C24, their C1-C24 alkyl esters, their salts and mixtures thereof.

9. The multilayer film according to claim 8 wherein the saturated aliphatic dicarboxylic acids are selected from 2-ethylsuccinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanandioic acid, dodecanedioic acid, brassylic acid, and their C1-24 alkyl esters.

10. The multilayer film according to claim 8 in which the component c2 is azelaic acid.

11. The multilayer film according to claim 1 wherein component iii. of layer A comprises a polyhydroxyalkanoate between 5 and 37%, with respect to the sum of the components i.-v.

12. The multilayer film according to claim 1 wherein component iv. of layer A is present between 0.1 and 80% with respect to the sum of the i.-v. components.

13. The multilayer film according to claim 12 wherein component iv. is preferably selected from kaolin, barite, clay, talc, calcium and magnesium, iron and lead carbonates, aluminum hydroxide, diatomaceous earth, aluminum sulfate, barium sulfate, silica, mica, titanium dioxide and wollastonite.

14. The multilayer film according to claim 1 wherein component v. is present between 0.1 and 0.5 with respect to the sum of the i.-v. components.

15. The multilayer film according to claim 1, in which in layer B the aromatic dicarboxylic acids in component e1 are selected from aromatic dicarboxylic acids of the phthalic acid type and heterocyclic dicarboxylic aromatic compounds, their esters, salts and mixtures.

16. The multilayer film according to claim 15 wherein said aromatic dicarboxylic acids comprise: from 1 to 99% by moles of terephthalic acid, its esters or salts; from 99 to 1% by moles of the 2,5-furandicarboxylic acid, its esters or salts.

17. The multilayer film according to claim 1, wherein in layer B the saturated aliphatic dicarboxylic acids in component e2 are selected from saturated C2-C24 dicarboxylic acids, their C1-C24 alkyl esters, their salts and their mixtures.

18. The multilayer film according to claim 17 wherein 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, undecanedioic acid, dodecanedioic acid, brassylic acid, octadecanedioic acid and their C1-24 alkyl esters, their salts and their mixtures.

19. The multilayer film according to claim 18 wherein said mixtures consist of adipic acid and azelaic acid and contain azelaic acid in an amount comprised between 5 and 70% by moles with respect to the sum of adipic acid and azelaic acid.

20. The multilayer film according to claim 1 wherein in the layer B the component vii. is present between 5 and 35% by weight, with respect to the sum of the components vi.-x.

21. The multilayer film according to claim 1 in which the layers A and B have an arrangement of the layers of type A/B and/or A/B/A.

22. The multilayer film according to claim 1 characterized in that it can be disintegrated under domestic composting conditions according to UNI 1135 in less than 180 days.

23. A packaging comprising the multilayer film according to claim 1.

24. The packaging according to claim 23 selected from bags for the transport of goods and bags for food packaging.

Description

EXAMPLES

[0186] Component i: poly(butylene adipate-co-butylene terephthalate) having a content of 47.3% in moles of terephthalic acid in relation to the sum of the total dicarboxylic acids, MFR 4.8 g/10 min (@ 190 C., 2.16 kg) and acidity 37 meq/kg.

[0187] Component ii-1: poly(butylene succinate-co-butylene azelate) containing 25% moles of azelaic acid in relation to the sum of succinic acid and azelaic acid, MFR 5.9 g/10 min (@ 90 C., 2.16 kg) and acidity 46 meq/kg.

[0188] Component ii-2: poly(butylene succinate-co-butylene azelate) containing 20% moles of azelaic acid in relation to the sum of succinic acid and azelaic acid, MFR 5.0 g/10 min (@ 190 C., 2.16 kg) and acidity 50 meq/kg.

[0189] Component iii: polylactic acid (PLA) Ingeo 3251D, MFR 41 g/10 min (@ 190 C., 2.16 kg).

[0190] Component v: styrene-alkylacrylate-glycidylmethacrylate-based random copolymer with Mw 6800 and epoxy number per molecule of 10.

[0191] Component vi: poly(butylene adipate-co-butylene azelate-co-butylene terephthalate), containing 15% moles of azelaic acid in relation to the sum of adipic acid and azelaic acid, containing 47.6% moles of terephthalic acid in relation to the sum of total dicarboxylic acids, MFR 4.4 g/10 min (@ 190 C., 2.16 kg) and acidity 39 meq/kg.

[0192] Component vii: native corn starch and plasticiser (76.4% by weight native corn starch, 13.9% by weight polyglycerol and 9.7% added water).

[0193] Component viii: polylactic acid (PLA) Ingeo 4043D, MFR 2.5 g/10 min (@ 190 C., 2.16 kg).

[0194] Component x: styrene-alkylacrylate-glycidylmethacrylate-based random copolymer with Mw 1400 and epoxy number per molecule equal to 33.

Example 1Three Layer Film with Arrangement A/B/A

[0195] Preparation of Composition A (layer A): the compositions described in Table 1 were fed to a twin-screw extruder mod. OMC EBV60/36, operating under the following conditions: [0196] Screw diameter (D)=58 mm; [0197] L/D=36; [0198] Screw rotation speed=140 rpm; [0199] Temperature profile=60-150-180-2104-1502 C.; [0200] Capacity: 40 kg/h; [0201] Vacuum degassing in zone 8 of 10.

[0202] Preparation of Composition B (layer B): the compositions described in Table 1 were fed to a twin-screw extruder mod. OMC EBV60/36, operating under the following conditions: [0203] Screw diameter (D)=58 mm; [0204] L/D=36; [0205] Screw rotation speed=160 rpm; [0206] Temperature profile=60-150-180-2104-1502 C.; [0207] Capacity: 46 kg/h; [0208] Vacuum degassing in zone 8 out of 10

[0209] Composition A and Composition B (Table 1) were then fed simultaneously to a co-extruder to form a three-layer blown film having an A/B/A arrangement. For this purpose, Composition A was fed at a flow rate of 3 kg/h to a first extruder having a screw diameter of 35 mm with an L/D of 30 operating at 10 rpm with a thermal profile of 100-1704 and at a flow rate of 3 kg/h to a second extruder characterised by a screw diameter of 35 mm with an L/D of 30 operating at 10 rpm with a thermal profile of 100-1704. Composition B was fed at 24 kg/h to an extruder with a 40 mm screw diameter with an L/D of 30 operating at 72 rpm with a thermal profile 80-1454. Both compositions, once melted, were coupled in a coextrusion-blowing head with an air gap of 0.9 mm and L/D 9 set at 170 C., feeding the multilayer structure to a film-forming process operating with a blowing ratio of 4.5 and a stretch ratio of 16.8.

[0210] The resulting film (total 12 microns, 20% layer A, equally divided between the two layers, 80% layer B) was then characterised in terms of disintegration properties (Table 2), mechanical properties (Table 3) and optical properties (Table 4).

Example 2Three Layer Film with Arrangement A/B/A

[0211] Preparation of composition A (layer A) and composition B (layer B): were fed to a twin-screw extruder mod. OMC EBV60/36, operating under the operating conditions reported for composition A and composition B in example 1.

[0212] Composition A and Composition B (Table 1) were then fed simultaneously to a co-extruder to form a three-layer blown film having an A/B/A arrangement. For this purpose, Composition A was fed at a flow rate of 3.2 kg/h to a first extruder having a screw diameter of 35 mm with an L/D of 30 operating at 11 rpm with a thermal profile of 100-1704 and at a flow rate of 3.1 kg/h to a second extruder characterised by a screw diameter of 35 mm with an L/D of 30 operating at 10 rpm with a thermal profile of 100-1704. Composition B was fed at 23.7 kg/h to an extruder with a 40 mm screw diameter with an L/D of 30 operating at 70 rpm with a thermal profile 80-1454. Both compositions, once melted, were coupled in a coextrusion-blowing head with an air gap of 0.9 mm and L/D 9 set at 170 C., feeding the multilayer structure to a film-forming process operating with a blowing ratio of 4.5 and a stretch ratio of 15.6.

[0213] The resulting film (total 13 microns, 20% layer A, equally divided between the two layers, 80% layer B) was then characterised in terms of disintegration properties (Table 2), mechanical properties (Table 3) and optical properties (Table 4).

Example 3 (Comparative) Three-Layer Film with Arrangement A/B/A

[0214] Preparation of composition A (layer A) and composition B (layer B): these were fed to a twin-screw extruder mod. OMC EBV60/36, operating under the operating conditions reported for composition A and composition B in example 1.

[0215] Composition A and Composition B (Table 1) were then fed simultaneously to a co-extruder to form a three-layer blown film having an A/B/A arrangement. For this purpose, Composition A was fed at a flow rate of 3 kg/h to a first extruder having a screw diameter of 35 mm with an L/D of 30 operating at 10 rpm with a thermal profile 100-1704 and at a flow rate of 3.2 kg/h to a second extruder characterised by a screw diameter of 35 mm with an L/D of 30 operating at 12 rpm with a thermal profile 100-1704. Composition B was fed at 23.8 kg/h to an extruder with a 40 mm screw diameter with a L/D of 30 operating at 73 rpm with a thermal profile 80-1454. Both compositions, once melted, were coupled in a coextrusion-blowing head with an air gap of 0.9 mm and L/D 9 set at 170 C., feeding the multilayer structure to a film-forming process operating with a blowing ratio of 4.5 and a stretch ratio of 16.8.

[0216] The resulting film (total 12 microns, 20% layer A, equally divided between the two layers, 80% layer B) was then characterised in terms of disintegration properties (Table 2), mechanical properties (Table 3) and optical properties (Table 4).

TABLE-US-00001 TABLE 1 Composition of mixtures (% by weight) Layer A i ii-1 ii-2 iii v Example 1 76.0 4.8 19.0 0.2 Example 2 72.6 9.1 18.1 0.2 Comparison 1 79.8 20.0 0.2

TABLE-US-00002 TABLE 2 Results for disintegration characteristics under home composting conditions (UNI 11355) Layer B vii viii x Example 1 60.9 36.0 2.9 0.2 Example 2 60.9 36.0 2.9 0.2 Comparison 1 60.9 36.0 2.9 0.2

[0217] Disintegration under home composting conditions was conducted according to standard UNI 11355 App. A Biodegradable plastic articles in home compostingRequirements and test methods.

[0218] The degree of disintegration of the films was determined by placing the samples in slides of size approximately 5050 mm. The slides were placed on top of a first layer of waste of about 4 cm and then covered by a second layer of waste of about 2 cm. The waste consisted of 98% compost, 1% starch and 1% feed. Disintegration was followed qualitatively (visual observation and photos).

TABLE-US-00003 TABLE 3 Results for mechanical properties and tear strength Test days in which complete disintegration occurred Example 1 153 Example 2 154 Comparison 1 179

TABLE-US-00004 TABLE 4 Results for optical properties Elmendorf tear FILM TRACTION ASTM D1922 ASTM D822 (23 C.-55% RH) (23 C. 55% RH-Vo 50 mm/min) MD force TD force b (MPa) .sub.b (%) E (MPa) (N/mm) (N/mm) Example 1 26 423 361 103 103 Example 2 25 425 340 144 60 Comparison 1 27 445 346 93 83

TABLE-US-00005 OPTICAL PROPERTIES ASTM D1003 TRANSM. % HAZE % CLARITY % Example 1 92 23 74 Example 2 89 53 47 Comparison 1 92 24 74