MULTILAYER BIODEGRADABLE FILM

Abstract

This invention relates to a multilayer biodegradable film which is particularly suitable for the manufacture of packaging and is also characterised by appreciable optical transparency properties in addition to high level mechanical properties.

Claims

1. A multilayer film comprising at least one first layer A and at least one second layer B, in which layers A and B have a mutual A/B/A arrangement, wherein the layer A and layer B are different from each other, in which layer A comprises an aliphatic and/or aliphatic-aromatic biodegradable polyester or a polyvinyl alcohol or copolymers thereof and in which layer B comprises: i) 30-95% by weight, with respect to the sum of components i-v, of at least one polyester comprising: a) a dicarboxylic component containing with respect to the total dicarboxylic component: a1) 35-70% by moles of units deriving from at least one aromatic dicarboxylic acid, a2) 65-30% by moles of units deriving from at least one saturated aliphatic dicarboxylic acid, and a3) 0-5% by moles of units deriving from at least one unsaturated aliphatic dicarboxylic acid; and 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, and b2) 0-5% by moles of units deriving from at least one unsaturated aliphatic diol; ii) 0.1-50% by weight, with respect to the sum of components i-v, of at least one polymer of natural origin; iii) 1-40% by weight, with respect to the sum of components i-v, of at least one polyhydroxy alkanoate; iv) 0-15% by weight, with respect to the sum of components i-v, of at least one inorganic filler; and 0-5% by weight, with respect to the sum of components i.-v., of at least one cross-linking agent and/or chain extender comprising at least one compound having two and/or multiple functional groups including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride divinylether groups and mixtures thereof.

2. The multilayer film according to claim 1, in which the aliphatic-aromatic polyester in layer A comprises: c) a dicarboxylic component comprising with respect to the total dicarboxylic component: c1) 35-70% by moles of units deriving from at least one aromatic dicarboxylic acid, c2) 65-30% by moles of units deriving from at least one saturated aliphatic dicarboxylic acid, and c3) 0-5% by moles of units deriving from at least one unsaturated aliphatic dicarboxylic acid; and 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, and d2) 0-5% by moles of units deriving from at least one unsaturated aliphatic diol.

3. The multilayer film according to claim 2, in which the saturated aliphatic dicarboxylic acids in component c2 comprise mixtures comprising at least 50% by moles of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, their C.sub.1-C.sub.24 esters and mixtures thereof.

4. The multilayer film according to claim 3, in which the saturated aliphatic dicarboxylic acids in component c2 are selected from adipic acid and azelaic acid or mixtures thereof.

5. The multilayer film according to claim 1, in which in addition to the said aliphatic and/or aliphatic-aromatic polyester in layer A the said layer A comprises 1-40% by weight with respect to the total for layer A of at least one polyhydroxy alkanoate.

6. The multilayer film according to claim 1, in which the saturated aliphatic dicarboxylic acid of component a2 of the polyester in layer B comprise mixtures comprising at least 50% by moles of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, their C.sub.1-C.sub.24 esters and mixtures thereof.

7. The multilayer film according to claim 6, in which the saturated aliphatic dicarboxylic acids in said component a2 are selected from adipic acid and azelaic acid or mixtures thereof.

8. The multilayer film according to claim 1, characterized by transmittance values of more than 90%, Haze values of less than 65%, and clarity over 20%, measured according to standard ASTM D1003.

9. The multilayer film according to claim 1, said film being biodegradable under home composting conditions according to UNI 11355.

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

11. The packaging according to claim 10, being selected from bags for the carrying of goods and bags for food packaging.

12. A bag for fruit and vegetables according to claim 11.

13. A mulch film comprising the multilayer film according to claim 1.

14. The multilayer film according to claim 2, in which in addition to the aliphatic and/or aliphatic-aromatic polyester in layer A the said layer A comprises 1-40% by weight with respect to the total for layer A of at least one polyhydroxy alkanoate.

15. The multilayer film according to claim 3, in which in addition to the aliphatic and/or aliphatic-aromatic polyester in layer A the said layer A comprises 1-40% by weight with respect to the total for layer A of at least one polyhydroxy alkanoate.

16. The multilayer film according to claim 4, in which in addition to the aliphatic and/or aliphatic-aromatic polyester in layer A the said layer A comprises 1-40% by weight with respect to the total for layer A of at least one polyhydroxy alkanoate.

17. The multilayer film according to claim 2, in which the saturated aliphatic dicarboxylic acid of component a2 of the polyester in layer B comprise mixtures comprising at least 50% by moles of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, their C.sub.1-C.sub.24 esters and mixtures thereof.

18. The multilayer film according to claim 3, in which the saturated aliphatic dicarboxylic acid of component a2 of the polyester in layer B comprise mixtures comprising at least 50% by moles of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, their C.sub.1-C.sub.24 esters and mixtures thereof.

19. The multilayer film according to claim 4, in which the saturated aliphatic dicarboxylic acid of component a2 of the polyester in layer B comprise mixtures comprising at least 50% by moles of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, their C.sub.1-C.sub.24 esters and mixtures thereof.

20. The multilayer film according to claim 5, in which the saturated aliphatic dicarboxylic acid of component a2 of the polyester in layer B comprise mixtures comprising at least 50% by moles of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassylic acid, their C.sub.1-C.sub.24 esters and mixtures thereof.

21. The multilayer film according to claim 7, in which the saturated aliphatic dicarboxylic acid of component a2 of the polyester i. comprises a mixture of adipic acid and azelaic acid.

22. The multilayer film according to claim 21, wherein the mixture comprises azelaic acid in a quantity of between 5 and 40% by moles with respect to the sum of the adipic acid and the azelaic acid.

23. The multilayer film according to claim 1, in which the polymer of natural origin of point ii. is in a quantity of between 5-40% by weight, with respect to the sum of components i.-v.

24. The multilayer film according to claim 1, in which the layer A and layer B are different from each other.

25. The multilayer film according to claim 1, in which the composition of layer A does not contain starch.

Description

EXAMPLE 1—TWO-LAYER FILM HAVING AN A/B ARRANGEMENT

[0210] Preparation of Composition A (layer A): 29.7 kg/h poly(butylene adipate-co-butylene terephthalate), having a terephthalic acid content of 47.5% by moles with respect to the total dicarboxylic component, MFR 11 g/10 min (at 190° C., 2.16 kg) and acidity 50 meq/kg, 9.1 kg/h of Ingeo 3251D polylactic acid (“PLA”), MFR 58 g/10 min (at 190° C., 2.16 kg), 1.0 kg/h of masterbatch comprising 10% by weight of Joncryl ADR4368CS (styrene-glycidylether-methylmethacrylate copolymer) and 90% of Ingeo 4043D polylactic acid (“PLA”), 0.2 kg/h of masterbatch comprising 10% Crodamide SR Bead manufactured by Croda and 90% of poly(butylene adipate-co-butylene terephthalate) were fed to an OMC EBV60/36 twin screw extruder operating under the following conditions: [0211] Screw diameter (D)=58 mm; [0212] L/D=36; [0213] Screw rotation speed=140 rpm; [0214] Thermal profile=60-150-180-210×4-150×2° C.; [0215] Throughput: 40 kg/h; [0216] Vacuum degassing in zone 8 out of 10.

[0217] The granules so obtained had an MFR (190° C., 2.16 kg in accordance with standard ISO 1133-1 “Plastics-determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics—Part 1: Standard method”) of 7 g/10 minutes. Preparation of Composition B (layer B): 28.3 kg/h of poly(butylene adipate-co-butylene azelate-co-butylene terephthalate) having an azelaic acid content of 30% by moles with respect to the sum of adipic acid and azelaic acid, and a terephthalic acid content of 48.3% by moles with respect to the total for the dicarboxylic component, MFR 5 g/10 min (at 190° C., 2.16 kg) and acidity 47 meq/kg, 1.4 kg/h of Ingeo 4043D polylactic acid (“PLA”), MFR 2.7 g/10 min (at 190° C., 2.16 kg), 16 kg/h of thermoplastic maize starch, 0.1 kg/h of Almatex PD-4440 produced by the Anderson Development Company, 0.1 kg/h of Crodamide ER microbead manufactured by Croda and 0.1 kg/h of Carbodilite HMV15CA manufactured by Nisshinbo Chemical Inc. were fed to an OMC EBV60/36 model twin screw extruder operating under the following conditions: [0218] Screw diameter (D)=58 mm; [0219] L/D=36; [0220] Screw rotation speed=160 rpm; [0221] Thermal profile=60-150-180-210×4-150×2° C.; [0222] Throughput: 46.1 kg/h; [0223] Vacuum degassing in zone 8 out of 10.

[0224] The granules so obtained had an MFR (160° C., 5 kg in accordance with standard ISO 1133-1 “Plastics—determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics—Part 1: Standard method”) of 2.4 g/10 minutes.

[0225] Composition A and Composition B were then fed simultaneously to a coextruder to form a two-layer blown film having an A/B arrangement. For this purpose Composition A was fed at a throughput of 3.3 kg/h to an extruder with a screw diameter of 35 mm and an L/D of 30 operating at 13 rpm with a 100-170×4 thermal profile. In parallel Composition B was fed through two extruders, the first characterised by a screw diameter of 35 mm with an L/D of 30 operating at 12 rpm with a 80-154×4 thermal profile operating at 3.3 kg/h and a second characterised by a screw diameter of 40 mm with an L/D of 30 operating at 74 rpm with an 80-145×4 thermal profile and a throughput of 28.3 kg/h. Once molten the two compositions were merged in the coextrusion-blowing head having a gap of 0.9 mm and an 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 20.2.

[0226] The film so obtained (total 10 microns, 10% layer A, 90% layer B) was then characterised in terms of mechanical and optical properties (Table 1).

EXAMPLE 2—TWO-LAYER FILM HAVING AN A/B/ARRANGEMENT

[0227] Composition A and Composition B according to Example 1 was simultaneously fed to a coextruder to form a three-layer blown film having an A/B/A arrangement. With this object Composition A was fed with a throughput of 3.3 kg/h to a first extruder having a screw diameter of 35 mm with an L/D of 30 operating at 14 rpm with a 100-170×4 thermal profile and with a throughput of 3.3 kg/h to a second extruder characterised by a screw diameter of 35 mm with an L/D of 30 operating at 13 rpm with a 100-170×4 thermal profile. Composition B was fed at 28.3 kg/h to an extruder having a screw diameter of 40 mm with an L/D of 30 operating at 74 rpm with a 80-154×4 thermal profile. Once molten the two compositions were merged in a coextrusion-blowing head with a gap of 0.9 mm and an L/D of 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 20.2.

[0228] The film so obtained (total 10 microns, 20% layer A, evenly distributed between the two layers, 80% layer B) was then characterised in terms of mechanical and optical properties (Table 1).

EXAMPLE 3 (COMPARATIVE) PREPARATION OF A MONOLAYER FILM COMPRISING COMPOSITION B

[0229] Composition B according to Example 1 was simultaneously fed to a coextruder to form a monolayer blown film having an B/B/B arrangement. With this object Composition B was fed with a throughput of 2.8 kg/h to a first extruder having a screw diameter of 35 mm with an L/D of 30 operating at 18 rpm with a 100-145×4 thermal profile and with a throughput of 24.3 kg/h to a second extruder characterised by a screw diameter of 40 mm with an L/D of 30 operating at 63 rpm with a 80-145×4 thermal profile and with a throughput of 2.8 kg/h to a third extruder characterised by a screw diameter of 35 mm with an L/D of 30 operating at 18 rpm with a 100-145×4. The coextrusion-blowing head has a gap of 0.9 mm and an L/D of 9 set at 145° C., feeding the monolayer structure to a film-forming process operating with a blowing ratio of 4.5 and a stretch ratio of 20.2.

[0230] The film so obtained (total 10 microns, 100% composition B) was then characterised in terms of mechanical and optical properties (Table 1).

EXAMPLE 4—TWO-LAYER FILM HAVING AN A/B/A ARRANGEMENT

[0231] Preparation of Composition A (layer A): 31.4 kg/h of poly(butylene adipate-co-butylene terephthalate) having a terephthalic acid content of 47.5% by moles with respect to the total dicarboxylic component, MFR 11 g/10 min (at 190° C., 2.16 kg) and acidity 50 meq/kg, 7.6 kg/h of Ingeo 3251D polylactic acid (“PLA”), MFR 58 g/10 min (at 190° C., 2.16 kg), 0.8 kg/h of masterbatch comprising 10% by weight of Joncryl ADR4368CS (styrene-glycidylether-methylmethacrylate copolymer) and 90% of Ingeo 4043D polylactic acid (“PLA”), 0.2 kg/h of masterbatch comprising 10% Crodamide SR Bead manufactured by Croda and 90% of poly(butylene adipate-co-butylene terephthalate) were fed to an OMC EBV60/36 model twin screw extruder operating under the conditions specified for layer A in Example 1.

[0232] The granules so obtained had an MFR (190° C., 2.16 kg in accordance with standard ISO 1133-1) of 7.5 g/10 minutes.

[0233] Composition A according to Example 4 and Composition B according to Example 1 were simultaneously fed to a coextruder to form a three-layer blown film having an A/B/A arrangement. With this object Composition A was fed with a throughput of 2.9 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 60-170×4 thermal profile and with a throughput of 2.9 kg/h to a second extruder characterised by a screw diameter of 35 mm with an L/D of 30 operating at 11 rpm with a 60-170×4 thermal profile. Composition B was fed at 24.2 kg/h to an extruder having a screw diameter of 40 mm with an L/D of 30 operating at 64 rpm with a 80-145×4 thermal profile. Once molten the two compositions were merged in a coextrusion-blowing head with a gap of 0.9 mm and an L/D 9 set to 170° C., feeding the multilayer structure to a film-forming process operating with a blowing ratio of 4.5 and a stretch ratio of 20.2.

[0234] The film so obtained (total 10 microns, 20% layer A evenly distributed between the two layers, 80% layer B) was then characterised in terms of mechanical and optical properties (Table 1).

EXAMPLE 5—TWO-LAYER FILM HAVING AN A/B/A ARRANGEMENT

[0235] Preparation of Composition A (layer A): 16 Kg/h poly(butylene sebacate), MFR 3.7 g/10 min (at 150° C., 2.16 kg) and acidity 25 meq/Kg, 20 kg/h poly(butylene adipate-co-butylene terephthalate), having a terephthalic acid content of 47.5% by moles with respect to the total dicarboxylic component, MFR 5.1 g/10 min (at 190° C., 2.16 kg) and acidity 37 meq/Kg, 4 kg/h of Ingeo 4043D polylactic acid (“PLA”), MFR 2.5 g/10 min (at 190° C., 2.16 kg), 0.1 kg/h of Crodamide ER microbead manufactured by Croda were fed to an OMC EBV60/36 twin screw extruder operating under the following conditions: [0236] Screw diameter (D)=58 mm; [0237] L/D=36; [0238] Screw rotation speed=160 rpm; [0239] Thermal profile=60-120-160×5-150×2° C.; [0240] Throughput: 40.1 kg/h; [0241] Vacuum degassing in zone 8 out of 10.

[0242] The granules so obtained had an MFR (190° C., 2.16 kg in accordance with standard ISO 1133-1 “Plastics—determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics—Part 1: Standard method”) of 6 g/10 minutes.

[0243] Composition A according to Example 5 and Composition B according to Example 1 were then fed simultaneously to a coextruder to form a three-layer blown film having an A/B/A arrangement. For this purpose Composition A was fed at a throughput of 2.8 kg/h to an extruder with a screw diameter of 35 mm and an L/D of 30 operating at 11 rpm with a 60-125×4 thermal profile. Composition B was fed through an extruder characterised by a screw diameter of 40 mm with an L/D of 30 operating at 66 rpm with a 80-145×4 thermal profile. Once molten the two compositions were merged in the coextrusion-blowing head having a gap of 0.9 mm and an L/D 9 set at 145° C., feeding the multilayer structure to a film-forming process operating with a blowing ratio of 4.5 and a stretch ratio of 20.2.

[0244] The film so obtained (total 10 microns, 20% layer A, 80% layer B) was then characterised in terms of mechanical and optical properties (Table 1).

EXAMPLE 6—TWO-LAYER FILM HAVING AN A/B/A ARRANGEMENT

[0245] Preparation of Composition A (layer A): poly(butylene succinate-co-butylene azelate) having an azelaic acid content of 25% by moles with respect to the total dicarboxylic component, MFR 6 g/10 min (at 190° C., 2.16 kg) and acidity 46 meq/kg.

[0246] Composition A according to Example 6 and Composition B according to Example 1 were simultaneously fed to a coextruder to form a three-layer blown film having an A/B/A arrangement. With this object Composition A was fed with a throughput of 2.8 kg/h to a first extruder having a screw diameter of 35 mm with an L/D of 30 operating at 12 rpm with a 60-120×4 thermal profile and with a throughput of 2.8 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 60-120×4 thermal profile. Composition B was fed at 24.3 kg/h to an extruder having a screw diameter of 40 mm with an L/D of 30 operating at 63 rpm with a 80-145×4 thermal profile. Once molten the two compositions were merged in a coextrusion-blowing head with a gap of 0.9 mm and an L/D 9 set to 145° 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.

[0247] The film so obtained (total 12 microns, 20% layer A evenly distributed between the two layers, 80% layer B) was then characterised in terms of mechanical and optical properties (Table 1).

EXAMPLE 7—TWO-LAYER FILM HAVING AN A/B/A ARRANGEMENT

[0248] Preparation of Composition A (layer A): poly(butylene adipate-co-butylene terephthalate) having a terephthalic acid content of 47.5% by moles with respect to the total dicarboxylic component, MFR 3.9 g/10 min (at 190° C., 2.16 kg) and acidity 33 meq/kg.

[0249] Composition A according to Example 7 and Composition B according to Example 1 were simultaneously fed to a coextruder to form a three-layer blown film having an A/B/A arrangement. With this object Composition A was fed with a throughput of 2.8 kg/h to a first extruder having a screw diameter of 35 mm with an L/D of 30 operating at 16 rpm with a 60-145×4 thermal profile and with a throughput of 2.8 kg/h to a second extruder characterised by a screw diameter of 35 mm with an L/D of 30 operating at 16 rpm with a 60-145×4 thermal profile. Composition B was fed at 24.3 kg/h to an extruder having a screw diameter of 40 mm with an L/D of 30 operating at 63 rpm with a 80-145×4 thermal profile. Once molten the two compositions were merged in a coextrusion-blowing head with a gap of 0.9 mm and an L/D 9 set to 145° C., feeding the multilayer structure to a film-forming process operating with a blowing ratio of 3.6 and a stretch ratio of 25.2.

[0250] The film so obtained (total 10 microns, 20% layer A evenly distributed between the two layers, 80% layer B) was then characterised in terms of mechanical and optical properties (Table 1).

TABLE-US-00001 TABLE 1 FILM TENSILE STRENGTH ASTM D882 Elmendorf tear (23° C. 55% RH-Vo ASTM D1922 OPTICAL PROPERTIES 50 mm/min) (23° C.-55% RH) ASTM D1003 .Math..sub.b .Math..sub.b E En.sub.b Force TRASM HAZE CLARITY (MPa) (%) (MPa) (Kj/m.sup.2) Direction (N/mm) % % % Example 1 24 874 334 2559 MD 107 92 88 27 (10 micron) TD 40 Example 2 25 320 355 3003 MD 112 92 38 60 (10 micron) TD 40 Example 3 30 315 243 3547 MD 161 92 98 8 comparative TD 309 (10 micron) Example 4 32 351 386 4182 MD 127 92 31 61 (10 micron) TD 78 Example 5 30 291 332 3425 MD 157 93 61 31 (10 micron) TD 214 Example 6 28 335 243 3550 MD 173 93 46 34 (12 micron) TD 203 Example 7 44 331 298 5254 MD 98 92 46 41 (10 micron) TD 258