Composition Comprising A Grafted Polylactic Acid

Abstract

A composition is provided comprising an epoxide functional polymer comprising epoxide functional groups, wherein the epoxide functional polymer has a number average molecular weight of 1000 to 10.000 g/mol and a grafted polylactic acid, wherein the polylactic acid is grafted with an acid-functional ethylenically unsaturated polymerizable monomer and/or an acid anhydride-functional ethylenically unsaturated polymerizable monomer and has a total amount of carboxylic acid groups and carboxylic acid anhydride groups between 10.0 and 60.0 mg KOH/g.

Claims

1. A composition comprising an epoxide functional polymer comprising epoxide functional groups, wherein the epoxide functional polymer has a number average molecular weight of 1000 to 10,000 g/mol, determined according to DIN 55672 part 2 (year: 2008), and a grafted polylactic acid, wherein the polylactic acid is grafted with an acid-functional ethylenically unsaturated polymerizable monomer and/or an acid anhydride-functional ethylenically unsaturated polymerizable monomer and has a total amount of carboxylic acid groups and carboxylic acid anhydride groups between 10.0 and 60.0 mg KOH/g, determined according to DIN EN ISO 2114.

2. The composition according to claim 1, wherein the epoxide functional polymer is a copolymer being a polymerization product of an epoxide functional ethylenically unsaturated polymerizable monomer and another ethylenically unsaturated polymerizable monomer.

3. The composition according to claim 1, wherein the grafted polylactic acid is grafted by a mixture of monomers comprising the acid-functional ethylenically unsaturated polymerizable monomer and/or the acid anhydride-functional ethylenically unsaturated polymerizable monomer and at least one ethylenically unsaturated polymerizable comonomer containing no acid-functional groups and no acid anhydride functional groups.

4. The composition according to claim 1, wherein the composition comprises particles comprising cores and a first coating covering at least a part of the surface of the cores, wherein the cores comprise the epoxide functional polymer and the first coating comprises the grafted polylactic acid.

5. The composition according to claim 4, wherein the first coating additionally comprises another polylactic acid containing carboxylic acid groups in an amount from 1.0 to at most 10.0 mg KOH/g.

6. The composition according to claim 1, wherein the composition comprises a blend comprising particles containing the epoxide functional polymer and particles containing the grafted polylactic acid.

7. The composition according to claim 1, wherein the weight ratio between the epoxide functional polymer and the grafted polylactic acid is from 2:1 to 1:2.

8. A method for processing a polylactic acid blend, the method comprising: providing components comprising: a polylactic acid containing carboxylic acid groups in an amount from 1.0 to at most 10.0 mg KOH/g, an epoxide functional polymer comprising epoxide functional groups, wherein the epoxide functional polymer has a number average molecular weight of 1000 to 10.000 g/mol, and a grafted polylactic acid, wherein the polylactic acid is grafted with an acid-functional ethylenically unsaturated polymerizable monomer and/or an acid anhydride-functional ethylenically unsaturated polymerizable monomer and has a total amount of carboxylic acid groups and carboxylic acid anhydride groups between 10.0 and 60.0 mg KOH/g; mixing the components; and melt processing the mixture.

9. The method according to claim 8, wherein providing the components comprises providing a composition comprising the epoxide functional polymer and the grafted polylactic acid.

10. The method according to claim 9, wherein the composition comprises: particles comprising cores and a first coating covering at least a part of the surface of the cores, wherein the cores comprise the epoxide functional polymer and the first coating comprises the grafted polylactic acid.

11. The method according to claim 8, wherein the grafted polylactic acid is provided in an amount of 0.1 to 2.0% by weight, based on a sum of the weights of the polylactic acid, the epoxide functional polymer, and the grafted polylactic acid.

12. The method according to claim 8, wherein the epoxide functional polymer is a copolymer being a polymerization product of an epoxide functional ethylenically unsaturated polymerizable monomer and another ethylenically unsaturated polymerizable monomer.

13. The method according to claim 8, wherein the epoxide functional polymer is provided in an amount of 0.1 to 2.0% by weight, based on a sum of the weights of the polylactic acid, the epoxide functional polymer, and the grafted polylactic acid.

14. The method according to claim 8, wherein the melt processing is performed from 30 seconds to 120 seconds at a temperature between 150° C. and 250° C.

15. The method according to claim 8, wherein the melt processing comprises forming a film that comprises the melt processed mixture.

16. A polylactic acid product obtained by the method according to claim 8.

17. The polylactic acid product according to claim 16, having the shape of a film.

18. The method according to claim 8, wherein the grafted polylactic acid is provided in an amount of 0.1 to 1.0% by weight, based on a sum of the weights of the polylactic acid, the epoxide functional polymer, and the grafted polylactic acid.

19. The method according to claim 8, wherein the epoxide functional polymer is provided in an amount of 0.1 to 1.0% by weight, based on a sum of the weights of the polylactic acid, the epoxide functional polymer, and the grafted polylactic acid.

20. The method according to claim 8, wherein the melt processing is performed from 30 seconds to 60 seconds at a temperature between 150° C. and 250° C.

21. The method according to claim 9, wherein the composition comprises: a blend comprising particles containing the epoxide functional polymer and particles containing grafted polylactic acid.

Description

DETAILED DESCRIPTION

[0086] Measurement of Acid Numbers

[0087] The acid number is the KOH quantity in mg that is required for neutralizing 1 g of substance under the defined conditions. The acid numbers were determined by a neutralization reaction with a 0.1 N KOH in Ethanol according to DIN EN ISO 2114.

##STR00001##

[0088] Die Swell

[0089] During the extrusion of the polymer melt through a die restriction the polymer melt is deformed by the die. Due to the viscoelastic properties of the polymer melt a part of the deformation is reversible. The retardation of the polymer molecules, which are oriented due to the passing through the die restriction, is described as entropic elasticity. The extruded polymer melt obtains a cross section diameter di outside the die, which cross section diameter is enlarged due to this effect compared to the cross section diameter d.sub.0 of the restriction of the die.

[0090] As the amount of die swell is a.o. dependent on the branching and on the molecular weight of the polymer, a determination of die swell during a measurement of melt flow rate index according to ISO 1133 is an easy way to combine the determination of both properties at the same time.

[0091] The measurements were performed by the following steps: [0092] Drying the granulate of the grafted polylactic acid during 4 hours at 80° C.; [0093] Determining the melt flow rate for 10 min at 210° C./2.16 kg; [0094] During the melt flow rate measurement cut of 2 cm long strands of the polymer melt; [0095] Allowing the polymer strands to cool to room temperature; [0096] Measuring a cross section diameter D of the polymer strands (D unrelaxed); [0097] Tempering the polymer strands during 15 minutes in a warm silicon oil bath (at temperature T); [0098] Cleaning the polymer strands with ethanol, and [0099] Determining a cross section diameter D of the polymer strands (D relaxed).

[0100] The strand widening is calculated according to:

SA(unrelaxed)=(D unrelaxed/2.095)−1

SA(relaxed)=(D relaxed/2.095)−1

[0101] wherein D unrelaxed and D relaxed are expressed in [mm].

[0102] Melt Strength

[0103] The determination of the melt strength of a polymer melt by a rheology measurement is described a.o. in Meissner, J, Dehnungsverhalten von Polyathylen-schmelzen, Rheologica Acta, 10 (1971), 230-242.

[0104] The measurements were performed on a Rheotens 71.97 Feeder—HCV Rheograph. The following parameters of were used:

[0105] Parameter HCV:

[0106] Die: round capillary 30.0/2.0/180

[0107] Temperature: 180° C.

[0108] Soak time: 10 min

[0109] Piston speed: 0.265 mm/s

[0110] Parameter Rheotens:

[0111] Acceleration: 24 mm/s.sup.2

[0112] Gap between die and wheels: 100 mm

[0113] Gap between wheels: Dial 3

[0114] Standard wheels

[0115] Samples have been dried @80° C. for 3 hours

[0116] The value of F max (in cN) is taken as measure for the melt strength of the polymer melt.

[0117] Closed End Pellets

[0118] A process is known for making closed end pellets, which comprises a core material, which comprises at least the epoxide functional polymer, and an outer layer having a polymeric material comprising the grafted polylactic acid. The outer layer encapsulates the core material substantially completely. The process comprises co-forming a tube comprised of an outer polymeric layer and forming a core material, which comprises the epoxide functional polymer, by simultaneously feeding the polymer for the outer layer in one part of an extruder, and feeding the core material into another part of the same extruder and co-extruding the outer layer and the core, thereby forming a polymeric tube filled with the core material. The filled tube is cooled first and then passed into a closing device (e.g., a gearwheel) for sealing, whereby the gearwheel simultaneous seals/welds and cuts the polymeric tube filled with the core material into multiple discrete segments. The formed segments are then cooled further and excess moisture will be removed before going through a separator to be packaged.

[0119] A known example of such a process is called SKIN TECHNOLOGY from BYK Netherlands B.V.

EXAMPLES

[0120]

TABLE-US-00001 TABLE 1 Materials used (Reference, supplier and description) Reference Material name Supplier Description PLA 1 Ingeo 2003 Nature- Transparent general purpose works Polylactic acid (PLA) LLC extrusion grade. MFR: 6 g/10 min [210° C., 2.16 kg]) Joncryl Joncryl BASF Acrylate copolymer, solid ADR 4368 Resins oligomeric chain extender; B.V. M.sub.n = 3000 g/mol PLA-g-AS PLA-g-AS Polylactic acid (PLA) grafted with Acrylic acid. The acid number is 40 mg KOH/g (after grafting).

[0121] In several melt processing experiments A-F a polylactic acid (Ingeo 2003) was mixed and melt processed together with additives as indicated in Table 2 in an extruder during a melt processing time indicated in the Table. In comparative experiment A no additive is used. In comparative experiment B and D only additive i), which is Joncryl ADR 4368, is used. In experiments C, E and F, component i) Joncryl and component ii) PLA-g-AS are both used as additives. In these experiments C, E and F, the weight ratio between the component i) Joncryl and component ii) PLA-g-AS In the melt is 1:1.

[0122] In the experiments C and E the additives i) and ii) may be added seperately into the feed stream of the extruder or the additives i) and ii) may be added as a pre-mix composition into the feed stream at once. In a particular example, the additives i) and ii) may be added as compacted particles, each containing particles of additive i) and particles of additive ii). The additives i) and ii) used for experiment F were processed, prior to addition into the extrudate, according to the closed end pellet process (known as SKIN TECHNOLOGY from BYK Netherlands B.V.) to prepare closed end pellets thereof. The core material of the closed end pellets contains the additive i), Joncryl ADR 4368, and the outer layer of the closed end pellets contains the additive ii), the grafted polylactic acid PLA-g-AS, wherein the outer layer encapsulates the core material substantially completely. In experiment F the prepared closed end pellets were added to the main feed in the extruder.

[0123] Table 2 shows the amount of polylactic acid (Ingeo 2003) and the amount of additives used in the melt processing experiments.

TABLE-US-00002 TABLE 2 melt processing compositions and melt processing time Additive Melt PLA 1 Additive Additive Additive ii) processing Example [wt %] i) i) [wt %] ii) [wt %] time [s] A*  100% — — — — 180 B* 99.5% Joncryl 0.5% — — 180 C 99.0% Joncryl 0.5% PLA-g- 0.5% 180 AS D* 99.5% Joncryl 0.5% — — 45 E 99.0% Joncryl 0.5% PLA-g- 0.5% 45 AS F 99.0% Joncryl 0.5% PLA-g- 0.5% 45 AS

[0124] The examples marked with “*” are not part of the invention, but are used as comparison examples.

[0125] The resulting extrudates of the experiments A-F were tested on die swell properties and melt strength properties in accordance with the measurement methods described above. The die swell number SA (relaxed) and the melt strength are indicated in Table 3.

TABLE-US-00003 TABLE 3 die swell number SA (relaxed) and melt strength of extrudate A-F Die swell SA F max Example relaxed [cN] A* 0.07 0.5 B* 1.08 40.6 C 1.25 55.8 D* 0.52 12.7 E 1.05 35.8 F 1.20 51.8

[0126] The results indicate that the addition of a mixture of PLA-g-AS and the Joncryl to the polylactic acid main component Ingeo 2003 raises the dies swell number SA (relaxed) and the melt strength considerably when maintaining the same melt processing time, see experiments B*versus C (at 180 seconds) and experiments D*versus E (at 45 seconds). Additionally, it is possible to obtain a reasonable die swell level and melt strength in a shorter time, when adding the combination of PLA-g-AS and the Joncryl instead of adding the Joncryl additive only, see experiments B*versus E.

[0127] Additionally, the experiment F demonstrates that skin-core particles containing the component Joncryl in the core of the particles and the component PLA-g-AS in the outer layer of the particles even further raises the die swell number SA (relaxed) and the melt strength when maintaining the same melt processing time and the same amounts of components in the melt process. See the experiment E versus F.