Use of styrene methyl methacrylate copolymers (SMMA) as compatibilizing agents

1. A polymer blend comprising:

(A) 60-88% (w/w) of at least one polystyrene (co)polymer, other than styrene methyl methacrylate copolymer (SMMA), wherein said at least one polystyrene (co)polymer comprises:

(A1) more than 50% (w/w) high impact polystyrene (HIPS), and

(A2) general purpose polystyrene (GPPS),

wherein the HIPS:GPPS mass ratio is in the range of to 95:5;

(B) 10-30% (w/w) of at least one poly(lactic acid) (PLA);

(C) 2-10% (w/w) of at least one styrene methyl methacrylate copolymer (SMMA) comprising at least 50% (w/w) styrene; and optionally

(D) 0-5% (w/w) of one or more additive(s).

2. The polymer blend according claim 1 , wherein the at least one polystyrene (co)polymer (A) further comprises a polystyrene (co)polymer selected from the group consisting of polystyrene, styrene acrylonitrile copolymer (SAN), acrylonitrile butadiene styrene copolymer (ABS), styrene butadiene copolymer (SB), styrene maleimide copolymer (SMC), styrene alpha-methylstyrene copolymer and mixtures of two or more thereof.

3. The polymer blend according to claim 1 , wherein the at least one poly(lactic acid) (PLA) (B) has a melt flow index (MFI) of between 4 and 10 g/10 min (determined at a temperature of 210° C. and at a load of 2.16 kg according to ASTM procedure D1238).

4. The polymer blend according to claim 1 , wherein the at least one styrene methyl methacrylate copolymer (SMMA) (C) is a random polymer.

5. The polymer blend according to claim 1 , wherein said polymer blend comprises about 5% (w/w) of at least one SMMA (C).

6. The polymer blend according to claim 1 , said blend comprising:

(A) 60-82.5% (w/w) of at least one polystyrene (co)polymer (A);

(B) 12-30% (w/w) of at least one PLA (B);

(C) about 5% (w/w) of at least one SMMA (C); and

(D) 0.5-5% (w/w) of one or more additive(s) (D).

7. The polymer blend according to claim 1 , wherein at least a part of the HIPS is a styrene butadiene block copolymer (SBC).

8. The polymer blend according to claim 1 , wherein at least a part of the HIPS is a styrene butadiene block copolymer (SBC) and the SBC has a dendrimer structure.

9. The polymer blend according to claim 1 , wherein said polymer blend comprises 12-30% (w/w) of at least one PLA (B).

10. The polymer blend according claim 1 , wherein the HIPS:GPPS mass ratio is in the range of 60:40 to 95:5.

11. The polymer blend according claim 1 , wherein the HIPS:GPPS mass ratio is in the range of 70:30 to 95:5.

12. The polymer blend according claim 1 , wherein the HIPS:GPPS mass ratio is in the range of 75:25 to 95:5.

13. A method of producing a polymer blend according to claim 1 comprising the steps of:

(i) blending the following components

(A) at least one polystyrene (co)polymer;

(B) at least one poly(lactic acid) PLA;

(C) at least one styrene methyl methacrylate copolymer SMMA; and optionally

(D) one or more additive(s),

under conditions allowing said components to form an essentially homogeneous molding composition; and

(ii) hardening the polymer blend obtained from step (i).

14. The method according to claim 13 , wherein:

step (i) comprises the heating of the components or the molding composition above the glass transition temperature (Tg); and

step (ii) comprises cooling the polymer blend below the glass transition temperature (Tg) of the polymer blend.

15. A product, comprising the polymer blend according to claim 1 , wherein said product is selected from the group consisting of:

(i) film material,

(ii) packing material,

(iii) a plastics molding,

(iv) fiber or yarn,

(v) foam,

(vi) a fabric or tissue,

(vii) a composite,

(viii) micro- or nanobeads, and

(ix) an implant.

16. The product according to claim 15 , wherein said polymer blend constitutes for more than 50% (w/w) of said product.