Polyolefin polylactic acid polymer blends

Abstract

The invention relates to a process of preparing a polyolefin polylactic acid polymer blend comprising the steps of i) providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof, ii) providing polylactic acid, iii) providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof grafted with at least one epoxide-functional monomer, iv) providing a polylactic acid grafted with at least one carboxylic acid or carboxylic anhydride functional monomer, v) mixing the components i) to iv) at elevated temperature in a range from 150° C. to 260° C., and wherein component i) is provided in an amount of 5.0 to 50.0% by weight, component ii) is provided in an amount of 40.0 to 90.0% by weight, component iii) is provided in an amount of 1.0 to 20.0% by weight, and component iv) is provided in an amount of 1.0 to 15.0% by weight, calculated on the sum of components i) to iv).

Claims

1. A process of preparing a polyolefin polylactic acid polymer blend comprising: providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof, providing a polylactic acid, providing a grafted polyolefin including a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof grafted with at least one epoxide-functional monomer, providing a grafted polylactic acid including a polylactic acid grafted with at least one selected from a carboxylic acid functional monomer and a carboxylic anhydride functional monomer, mixing the polyolefin, the polylactic acid, the grafted polyolefin, and the grafted polylactic acid at elevated temperature in a range from 150° C. to 260° C., and wherein the polyolefin is provided in an amount of 5.0 to 50.0% by weight, the polylactic acid is provided in an amount of 40.0 to 90.0% by weight, the grafted polyolefin is provided in an amount of 1.0 to 20.0% by weight, and the grafted polylactic acid is provided in an amount of 1.0 to 15.0% by weight, calculated on the sum of the polyolefin, the polylactic acid, the grafted polyolefin, and the grafted polylactic acid.

2. The process according to claim 1, wherein the mixing is carried out in an extruder.

3. The process according to claim 1, wherein the grafted polyolefin and the grafted polylactic acid are provided as a pre-compounded masterbatch.

4. The process according to claim 3, wherein the grafted polyolefin and the grafted polylactic acid are provided for the pre-compounded masterbatch in a weight ratio of 2:1 to 1:3.

5. The process according to claim 4, wherein the pre-compounded masterbatch is provided in an amount of 5.0 to 20.0% by weight, calculated on the sum of the polyolefin, the polylactic acid, and the pre-compounded masterbatch.

6. The process according to claim 1, wherein the polyolefin has a melt flow rate in the range of 0.1 to 100.0 g/10 min at a temperature of 230° C./2.16 kg, determined in accordance with ISO standard 1133.

7. The process according to claim 1, wherein the grafted polyolefin contains 0.5 to 6.0% by weight of grafted epoxide-functional monomer, calculated on the weight of the grafted polyolefin.

8. The process according to claim 1, wherein the polylactic acid has a melt flow rate in the range of 0.1 to 15.0 g/10 min at a temperature of 190° C./2.16 kg, determined in accordance with ISO standard 1133.

9. The process according to claim 3, wherein the pre-compounded masterbatch is prepared by mixing the grafted polyolefin and the grafted polylactic acid at elevated temperature in a range from 150° C. to 260° C.

10. The process according to claim 1, wherein one or both the grafted polyolefin and the grafted polylactic acid are prepared by solid phase grafting.

11. A pre-compounded masterbatch composition obtainable by mixing at elevated temperature in the range of from 150 to 260° C. 25.0 to 66.0% by weight of a grafted polypropylene including polypropylene grafted with at least one epoxide-functional monomer, and 37.0 to 75.0% by weight of a grafted polylactic acid including polylactic acid grafted with at least one selected from a carboxylic acid functional monomer and a carboxylic anhydride functional monomer, wherein the weight % are calculated on the total weight of the grafted polypropylene and the grafted polylactic acid.

12. The composition according to claim 11, wherein the grafted polypropylene includes polypropylene grafted with glycidyl methacrylate in an amount in the range of 1.0 to 3.0% by weight, calculated on the weight of the grafted polypropylene.

13. The composition according to claim 11, wherein the grafted polylactic acid incudes 0.1 to 8.0% by weight of the grafted at least one selected from a carboxylic acid functional monomer and a carboxylic anhydride functional monomer, calculated on the weight of the grafted polylactic acid.

14. The composition according to claim 11, wherein the grafted polypropylene and the grafted polylactic acid are present as two continuous phases.

15. The composition according to claim 11, wherein the composition comprises 80.0 to 100.0% by weight of the grafted polypropylene and the grafted polylactic acid, calculated on the weight of the composition.

16. A polyolefin polylactic acid polymer blend obtainable by mixing at elevated temperature in a range from 150° C. to 260° C.: 5.0 to 50.0% by weight of a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof, 40.0 to 90.0% by weight of a polylactic acid, 1.0 to 20.0% by weight of a grafted polyolefin including a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof grafted with at least one epoxide-functional monomer, and 1.0 to 15.0% by weight of a grafted polylactic acid including a polylactic acid grafted with at least one selected from a carboxylic acid functional monomer and a carboxylic anhydride functional monomer, wherein the % by weight are calculated on the sum of the polyolefin, the polylactic acid, the grafted polyolefin, and the grafted polylactic acid.

17. The polymer blend according to claim 16, wherein the polylactic acid forms a continuous phase.

18. The polymer blend according to claim 16, wherein the polymer blend is present as a 3-dimensional shaped object obtained by injection molding or extrusion.

19. A process of preparing a polyolefin polylactic acid polymer blend, the process comprising combining the masterbatch composition of claim 11 with a polylactic acid and a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof.

20. The process according to claim 9, wherein the pre-compounded masterbatch is prepared by mixing the grafted polyolefin and the grafted polylactic acid in an extruder.

Description

EXAMPLES

Synthesis Example 1: Polypropylene Grafted with an Epoxide-Functional Monomer (Component iii)

(1) 100 parts by weight of a polypropylene homopolymer powder with an average particle size of 1.5 mm, a weight average molecular weight Mw of 460000 g/mol, a melt flow rate of 10.5 g/10 min (230° C./10 kg), and a melting temperature of 162° C., were placed in a reactor with stirrer. 4 parts by weight of glycidyl methacrylate (GMA) and 0.3 parts by weight of 2,5-dimethyl-2,5-di(tert.-butylperoxy)-hexane were added and the reactor was purged with nitrogen to remove oxygen. The mixture was stirred for a period of 20 minutes at 60° C. Subsequently, the temperature was increased to 146° C. at a heating rate of 1.9° C./min and held at 146° C. for a period of 1 hour, while stirred at 800 rotations/minute. Next, the reactor was purged with nitrogen for one hour. The nitrogen flow rate was 40 parts by volume of nitrogen per reactor volume per hour. After further cooling to 50° C., the reaction product was removed from the reactor.

Synthesis Example 2: Polylactic Acid Grafted with Maleic Anhydride (Component iv)

(2) 100 parts by weight of a polylactic acid powder having a melt flow rate of 38 g/10 min (190° C./2.16 kg) were placed in a reactor with stirrer. 2.5 parts by weight of maleic anhydride (MA), 1.0 parts by weight of styrene, and 1.5 parts by weight of dilauryl peroxide were added and the reactor was purged with nitrogen to remove oxygen. The mixture was stirred for a period of 20 minutes at 60° C. Subsequently, the temperature was increased to 105° C. at a heating rate of 1.9° C./min and held at 105° C. for a period of 1 hour, while stirred at 800 rotations/minute. Next, the reactor was purged with nitrogen for one hour. The nitrogen flow rate was 40 parts by volume of nitrogen per reactor volume per hour. After further cooling to 50° C., the reaction product was removed from the reactor.

Synthesis Example 3: Polylactic Acid Grafted with Maleic Anhydride (Component iv)

(3) The procedure was similar to synthesis Example 2. However, the starting material was polylactic acid powder having a melt flow rate of 4.5 g/10 min at 190° C./2.16 kg.

Synthesis Example 4: Polylactic Acid Grafted with Acrylic Acid (Component iv)

(4) The procedure was similar to synthesis Example 3. However, the grafting monomer was acrylic acid (AA) in an amount of 4 parts by weight.

Synthesis Example 5: Polyethylene Grafted with an Epoxide-Functional Monomer (Component iii)

(5) The procedure was similar to synthesis Example 1. However, the grafting was carried out on 100 parts by weight of a high density polyethylene (HDPE) powder with an average particle size of 0.5 mm, a melt flow rate of 19 g/10 min (190° C./2.16 kg), and a melting temperature of 136° C. The polymer was grafted with 3.5 parts by weight of glycidyl methacrylate and 0.5 parts by weight of dilauroylperoxide. The grafting reaction temperature was 100° C. for 45 minutes.

(6) Table 1 summarizes the preparation of grafted polymers:

(7) TABLE-US-00001 grafted reactive Prep. graft MFR 190° C., monomer content Example monomer 2.16 kg in weight - % 1 GMA 84 g/10 min 2.3 2 MA 26 g/10 min 1.3 3 MA 3.7 g/10 min  1.5 4 AA 3.7 g/10 min  3.2 5 GMA 16 g/10 min 2.7

(8) Preparation of Pre-Compounded Masterbatches

(9) The pre-compounded masterbatches were prepared in a ZSK 25 Werner & Pfleiderer twin-screw extruder. The components were fed via dosing balances into the intake of the extruder with the following settings:

(10) Temperature in the Extruder

(11) TABLE-US-00002 temperature 1 2 3 4 5 6 7 8 zone temperature 140 180 220 230 230 230 230 220 ° C.

(12) number of revolutions 300 rpm

(13) throughput 20 kg/h

(14) strand pelletizing

(15) Table 2 summarizes the preparation of pre-compounded masterbatches of Examples 6 to 9. The table provides the parts by weight of starting materials for pre-compounded masterbatches. Example 6 is a comparative Example.

(16) TABLE-US-00003 TABLE 2 Example Synth Ex. 1 PLA* Synth Ex. 3 Synth Ex. 4 Synth Ex 5  6* 67 33 7 67 33 8 50 50 9 33 67 *Comparative Example with unmodified polylactic acid

(17) Preparation of Polymer Blends

(18) The polymer blends were prepared as described above for the pre-compounded masterbatches. Table 3 summarizes the preparation of polymer blends of polypropylene and polylactic acid. The table provides the parts by weight of starting materials for polymer blends. Examples 10 to 12 are comparative Examples.

(19) TABLE-US-00004 TABLE 3 component Pre- ii iii iv compounded Ingeo Ingeo i Synth Synth masterbatch Example 2003 3251 PP Ex. 1 Ex. 3 6 7 8 10 70 0 20 10 0 0 0 0 11 0 70 30 0 0 0 0 0 12 65 0 20 0 0 15 0 0 13 65 0 20 10 5 0 0 0 14 65 0 20 0 0 0 0 15 15 0 65 20 10 5 0 0 0 16 0 65 20 0 0 0 15 0 17 65 0 20 0 0 0 15 0

(20) Table 4 summarizes the preparation of polymer blends of polyethylene and polylactic acid. The table provides the parts by weight of starting materials for polymer blends. Examples 18 and 19 are comparative Examples. Ingeo 2003 and Ingeo 3251 are commercial polylactic acid grades available from NatureWorks LLC

(21) TABLE-US-00005 component Pre- ii iii iv compounded Ingeo i Synth Synth masterbatch Example 3251 PE Ex. 5 Ex. 3 9 18 70 30 0 0 0 19 70 20 10 0 0 20 65 20 10 5 0 21 65 20 0 0 15

(22) Table 5 summarizes the test results of mechanical properties of polymer blends. The properties measured on test specimen having dimensions of 80×10×4 mm, prepared by injection molding.

(23) TABLE-US-00006 TABLE 5 Flexural Flexural Charpy Impact Modulus Strength Strength in Mpa in MPa in kJ/m.sup.2 MVR (190° C., ISO 178 2 ISO 178 2 ISO 179/ Example 2.16 kg) mm/min mm/min 1U, 23° C. 10  0.5 ml/10 min 2090 39.1 5.0 11 22.2 ml/10 min 2660 53.6 8.1 12  1.2 ml/10 min 2320 51.5 6.9 13  3.5 ml/10 min 2520 69.9 14.8 14  4.2 ml/10 min 2390 70.0 17.2 15   17 ml/10 min 2480 73.5 21.1 16   18 ml/10 min 2520 76.4 22.6 17  5.0 ml/10 min 2380 68.6 18.5 18 18.8 ml/10 min 1900 41.2 4.3 19  2.1 ml/10 min 2140 61.5 15.1 20  4.3 ml/10 min 2220 63.2 16.5 21  8.2 ml 10/min 2110 68.2 18.7

(24) The Examples demonstrate the beneficial effects of the invention. The blends of polypropylene and polylactic acid 13 to 17 all exhibit better mechanical properties than comparative compositions 10 to 12. The same conclusion can be drawn for polyethylene polylactic acid blends. The inventive blends 20 and 21 have higher flexural strength and impact strength than their comparative blends 18 and 19.

(25) The results of Examples 14, 16, 17, and 21 demonstrate a good effect of using the pre-compounded masterbatches.