BIODEGRADABLE FILM WITH A LACTIC ACID POLYESTER FLUIDIZED WITH A NITROGEN COMPONENT

Abstract

A highly transparent film comprising a diacid and diol polyester and a lactic acid polyester fluidised using a nitrogen component as a fluidising additive selected from: a nitrogen compound of formula (I)

##STR00001## or a linear amine NHR4-R5, and optionally a cross-linking agent and/or a chain extender.

Claims

1. A film consisting of a polymer composition comprising: i) 65-89% by weight, compared to the sum of components i.-iv., of at least one polyester comprising: a. a dicarboxylic component containing with respect to the total dicarboxylic component: a1) 0-60% in moles of units derived from at least one aromatic dicarboxylic acid; a2) 40-100% 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 with respect to the total diol component: b1) 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; and ii) 10-34.995% by weight, relative to the sum of components i.-iv, of one or more fluidised lactic acid polyesters. iii) 0.005-1% by weight of the sum of the components i.-iv. of at least one nitrogen component selected from: a nitrogen compound of formula (I) ##STR00006## where each of R1 and R2 individually is OH or NH.sub.2, and R3 is OH, NH.sub.2, C1-C4 alkyl or a halogen, with the condition that if R1 and R2 are OH, then R3 is also OH; or a linear amine NHR4-R5 where R4 is C1-C4 alkyl and R5 is NH.sub.2 or C1-C4 alkyl. (iv) 0-1% by weight, compared to the sum of components i.-iv, of at least one cross-linking agent and/or chain extender.

2. The film according to claim 1, in which the at least one aromatic dicarboxylic acid in component a1) is selected from aromatic dicarboxylic acids of the phthalic acid type, their esters, salts and mixtures.

3. The film according to claim 1, in which the at least one saturated aliphatic dicarboxylic acid in component a2) is selected from saturated C2-C24 dicarboxylic acids, their C1-C24 alkyl esters, their salts and mixtures thereof.

4. The film according to claim 3, in which the at least one saturated aliphatic dicarboxylic acid in component a2) is 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 and their C1-24 alkyl esters.

5. The film according to claim 3, in which the at least one 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.

6. The film according to claim 3, in which the at least one saturated carboxylic acid comprises or consists of adipic acid and azelaic acid and contains the azelaic acid in an amount of between 5 and 65% in moles in moles of azelaic acid relative to the sum of the adipic acid and azelaic acid.

7. The film according to claim 3, in which when component a1) is equal to 0, and the dicarboxylic acid a2) is succinic acid.

8. The film according to claim 1, in which the nitrogen component (iii) is the product of general formula (I) in which R1, R2, R3 are NH.sub.2 or a derivative thereof.

9. The film according to claim 1, in which component iv comprises at least one di- and/or polyfunctional compound bearing isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride, divinyl ether groups and mixtures thereof.

10. Packaging comprising the film according to claim 1.

11. The packaging according to claim 10 selected from bags for transporting goods and bags for food packaging.

12. A process for preparing a polymer composition suitable for obtaining the film of claim 1 comprising the steps of 1) mixing: a) 85-99.9% by weight of one or more lactic acid polyesters characterised by a shear viscosity of between 600 and 1700 Pa.Math.s (measured on dried material containing less than 400 ppm water according to ASTM standard D3835 at T=190 C., shear rate=141.6 s-1, D=1 mm, L/D=10) and b) 15-0.1% by weight of at least one nitrogen component iii selected from: a nitrogen compound of formula (I) ##STR00007## where each of R1 and R2 individually is OH or NH2, and R3 is OH, NH2, C1-C4 alkyl or a halogen, with the condition that if R1 and R2 are OH, then R3 is also OH; or a linear amine NHR4-R5 where R4 is C1-C4 alkyl and R5 is NH2 or C1-C4 alkyl, obtaining a fluidised lactic acid polyester; 2) mixing said polyester of fluidised lactic acid with at least one polyester i.

13. The process according to claim 12, further characterised in that in step 1 the content of nitrogen component iii. is between 1 and 15% by weight, and the mixture in step 2 further comprises one or more lactic acid polyesters characterised by a shear viscosity between 600 and 1700 Pa.Math.s, (measured on dried material containing less than 400 ppm water according to ASTM standard D3835 at T=190 C., shear strain rate=141.6 s-1, D=1 mm, L/D=10).

14. The film according to claim 2, in which the at least one saturated aliphatic dicarboxylic acid in component a2) is selected from saturated C2-C24 dicarboxylic acids, their C1-C24 alkyl esters, their salts and mixtures thereof.

15. Packaging comprising the film according to claim 2.

16. Packaging comprising the film according to claim 3.

17. Packaging comprising the film according to claim 4.

18. Packaging comprising the film according to claim 5.

19. Packaging comprising the film according to claim 6.

20. Packaging comprising the film according to claim 7.

Description

EXAMPLE 1FILM PREPARATION

[0112] In Example 1, the lactic acid polyester was previously blended with component iii in a 99.70% by weight composition of lactic acid polyester PLA-1 with 0.3% of iv under the same conditions as the blends shown in Table 3. The resulting fluidised lactic acid polyester (mixture 1a) was characterised by a shear viscosity of 241 Pa.Math.s measured on dried material containing less than 400 ppm water according to ASTM standard D3835 at T=190 C., shear strain rate=141.6 s-1, D=1 mm, L/D=10.

[0113] In Example 2, the lactic acid polyester was previously blended with component iii in a 90% by weight composition of lactic acid polyester PLA-1 with 10% of iv under the same conditions as the blends shown in Table 3, except for the thermal profile, set at 60-150-1605-1502 C. The fluidised lactic acid polyester obtained (mixture 1b) was characterised by a shear viscosity of 88 Pa.Math.s. measured on dried material containing less than 400 ppm water according to ASTM standard D3835 at T=190 C., shear strain rate=141.6 s-1, D=1 mm, L/D=10.

[0114] Composition Preparation: The compositions described in Table 4 were fed to a twin-screw extruder mod. OMC EBV60/36 (L/D=36; diameter 58 mm), operating under the following conditions:

[00003]$\mathrm{Screw}\mathrm{diameter}\left(D\right)=58\mathrm{mm};$$L/D=36;$$\mathrm{Screw}\mathrm{rotation}=140\mathrm{rpm};$$\mathrm{Temperature}\mathrm{profile}=60-150-180-2104-1502C.$$\mathrm{Capacity}:40\mathrm{kg}/h;$

[0115] Vacuum degassing in zone 8 out of 10.

[0116] Film preparation: The resulting compositions were fed to a Ghioldi model blown film machine with a 40 mm diameter screw and L/D 30 operating at 64 rpm with a 120-170-1707 C. thermal profile. The film-forming head with a 0.9 mm air gap and L/D 12 was set at 170 C. Film forming was carried out with a blowing ratio of 4.5 and a stretching ratio of 14.5. This resulted in a film thickness of 14 m.

TABLE-US-00004 TABLE 4 Composition of mixtures (% by weight) Mixture Mixture i PLA-1 PLA-2 1a 1b iv Example 1 79.60 20 0.25 Example 2 79.60 18.45 0.55 0.25 Comparison 1 79.75 20 0.25 Comparison 2 79.75 20 0.25

[0117] In Table 4 we show a viscous lactic acid polyester (PLA-1) and a fluid lactic acid polyester (PLA-2). The viscous lactic acid polyester is combined with two different mixtures containing a nitrogen compound of formula (I).

TABLE-US-00005 TABLE 5 Results of optical properties OPTICAL PROPERTIES ASTM D1003 TRANSM. % HAZE % CLARITY % Example 1 92 9 96 Example 2 91 12 93 Comparison 1 90 73 14 Comparison 2 91 11 93

[0118] As can be seen in Table 5 the viscous acid lactic polyester without the presence of a nitrogen compound of formula (I) (PLA-1, Comparison 1) gives very poor optical results. Instead, the viscous acid lactic polyester PLA-1 can give good optical results only if combined with a nitrogen compound of formula (I) (Example 1 and Example 2). The Comparison 2 with a fluid acid lactic polyester without a nitrogen compound of formula (I) represents the result to be achieved.

[0119] HPLC analysis by the method specified in the description showed a 1,3,5-triazine-2,4,6-triamine concentration of 0.007% w/w in the film corresponding to Example 1 and 0.022% w/w in the film corresponding to Example 2.

EXAMPLE 3 (COMPARISON)

[0120] An amide wax, such as erucamide (C.sub.22H.sub.43NO, a primary fatty amide resulting from the formal condensation of the carboxy group of erucic acid with ammonia) does not enable to obtain a fluidised lactic acid polyester starting from a lactic acid polyester characterized by a shear viscosity between 600 and 1700 Pa.Math.s. In particular, starting from a lactic acid polyester characterized by a shear viscosity of 1239 Pa.Math.s, by adding by extrusion 0.5% w/w of erucammide results in a lactic acid polyester with a shear viscosity of 1044 Pas, while adding by extrusion 1% w/w of erucammide results in a lactic acid polyester with a shear viscosity of 948 Pas. The shear viscosity values obtained are far above 600 Pa.Math.s, so the lactic acid polyester cannot be considered fluidised. The shear viscosity is measured on dried material containing less than 400 ppm water according to ASTM standard D3835 at T=190 C., shear strain rate=141.6 s-1, D=1 mm, L/D=10. The twin-screw operating conditions correspond to those reported in the compounds described in Table 3.