USE OF STYRENE METHYL METHACRYLATE COPOLYMERS (SMMA) AS COMPATIBILIZING AGENTS

Abstract

Polymer blends comprising (A) at least one polystyrene (co)polymer other than styrene methyl methacrylate copolymer (SMMA), (B) at least one poly(lactic acid) (PLA) and (C) at least one styrene methyl methacrylate copolymer (SMMA) have advantageous properties.

Claims

1-15. (canceled)

16. A polymer blend comprising: (A) 25-89.5% (w/w) of at least one polystyrene (co)polymer, other than styrene methyl methacrylate copolymer (SMMA); (B) 10-50% (w/w) of at least one poly(lactic acid) (PLA); (C) 0.5-20% (w/w) of at least one styrene methyl methacrylate copolymer (SMMA); and optionally (D) 0-5% (w/w) of one or more additive(s).

17. The polymer blend according claim 16, wherein the at least one polystyrene (co)polymer (A) is 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.

18. The polymer blend according to claim 16, wherein the at least one polystyrene (co)polymer (A) comprises at least one rubber modified high impact polystyrene (HIPS).

19. The polymer blend according to claim 16, 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).

20. The polymer blend according to claim 16, wherein the at least one SMMA (C) contains at least 50% (w/w) styrene.

21. The polymer blend according to claim 16, wherein the at least one styrene methyl methacrylate copolymer (SMMA) (C) is a random polymer.

22. The polymer blend according to claim 16, wherein said polymer blend comprises 40-88% (w/w) of at least one polystyrene (co)polymer (A) other than SMMA.

23. The polymer blend according to claim 16, wherein said polymer blend comprises 10-40% (w/w) of at least one PLA (B).

24. The polymer blend according to claim 16, wherein said polymer blend comprises 1-15% (w/w) of at least one SMMA (C).

25. The polymer blend according to claim 16, said blend comprising: (A) 55-87.5% (w/w) of at least one polystyrene (co)polymer; (B) 10-30% (w/w) of at least one PLA; (C) 2-10% (w/w) of at least one SMMA; and, (D) 0.5-5% (w/w) of one or more additive(s).

26. The polymer blend according to claim 18, wherein at least a part of the HIPS is a styrene butadiene block copolymer (SBC).

27. The polymer blend according to claim 18, wherein at least a part of the HIPS is a styrene butadiene block copolymer (SBC) and the SBC has a dendrimer structure.

28. The polymer blend according to claim 16, wherein said polymer blend comprises 10-30% (w/w) of at least one PLA (B).

29. The polymer blend according to claim 16, wherein said polymer blend comprises 12-30% (w/w) of at least one PLA (B).

30. A method of producing a polymer blend according to claim 16 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).

31. The method according to claim 30, 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.

32. A product, comprising the polymer blend according to claim 16, 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.

33. The product according to claim 32, wherein said polymer blend constitutes for more than 50% (w/w) of said product.

Description

EXAMPLES

Preparing of the PS-PLA-Blends

[0151] The PLA material was obtained from NatureWorks® LLC (Minnetonka, USA) as general purpose extrusion grade product Ingeo Biopolymer 2002D (specific gravity 1.24; tensile strength at break of 53 MPa; Melt Flow Rate (ASTM D1238) of 5-7).

[0152] The HIPS and GPPS were provided by Styrolution, LLC (USA) as:

[0153] PS 6200 (polystyrene with Mw of 207,000 g/Mol; Melt Flow Rate (ASTM D1238, 200° C. and 5 kg) of 3.1) and

[0154] PS 1600 (polystyrene with Mw of 240,000 g/Mol; Melt Flow Rate (ASTM D1238) of 6), respectively.

[0155] The SMMA used was a random copolymer of 70% styrene and 30% methyl methacrylate (NAS30 with Mw of 187,000 g/Mol; Melt Flow Rate (ASTM D1238) of 2.2).

[0156] Mixtures of HIPS (diluted with GPPS), PLA, and SMMA were compounded using a single screw 0.75 inch extruder with zone temperatures set from 160 to 200° C. The melt was passed through a die plate to form strands roughly 3 mm in diameter. Polymer strands were passed through a water bath to cool them and then the cooled polymer was cut into pellets roughly 3 mm in length. The pellets were then passed through the same extruder a second time to insure thorough compounding.

[0157] Pellets of the compounded blend were injection molded at from 160 to 180° C. into Type I tensile bar specimen. The specimens were tested for ductility and toughness by stressing the specimen in tension according to ASTM procedure D638. Specimen were also tested for impact resistance according to ASTM D256 for notched Izod impact strength and D5420 for Gardner impact strength. The ASTM procedures D638, D256 and D5420 were used in the versions which were up-to-date end of 2013.

[0158] Table 1 illustrates the beneficial effect of the SMMA on mechanical properties of the polystyrene/PLA blend. At low PLA content, the SMMA has neutral to a slight negative effect on mechanical properties. However, at higher PLA contents (15% and 25%), the mechanical properties are clearly benefited by the SMMA. This illustrates that the SMMA itself has no inherit benefit in this case, except for its significant improvement in the compatibilization of the HIPS and PLA.

[0159] Notably, the polymer blends shown in Table 1 with and without SMMA each contain the same amounts of rubber (from the HIPS) and PLA. Therefore, the demonstrated effect does not result from different amounts of rubber or PLA. It has been demonstrated that admixing SMMA has a beneficial effect on the properties of polystyrene (co)polymer/PLA blends.

[0160] It has been demonstrated that at PLA contents above 5% (w/w), the admixing of SMMA to the composition bears beneficial technical effects, such as an improvement in notched Izod impact strength, in ultimate elongation, in tensile energy to break and Gardner impact strength.

TABLE-US-00001 TABLE 1 Improvement in energy to break with addition of SBC (Styroflex 2G66) to polylactic acid biopolymer (Ingeo 2002D). Without SMMA HIPS 6200 % 65 65 65 65 SMMA % 0 0 0 0 PLA 2002D % 0 5 15 25 GPPS 1600 % 35 30 20 10 Total % 100 100 100 100 Notch Izod impact strength ft-lb/in 3.0 2.2 0.9 0.7 Gardner impact strength in-lb 30 29 7 3 Tensile strain at break % 31 32 29 34 Tensile modulus kpsi 394 392 384 384 Tensile stress at break psi 3807 3684 3104 3198 Tensile stress at yield psi 3849 3858 3739 3737 Energy to break in-lbf 133 133 114 127 Ultimate elongation % 40 37 31 27 Energy to break (rounded) In-lbf 360 330 240 200 With SMMA HIPS 6200 % 65 65 65 65 SMMA % 5 5 5 5 PLA 2002D % 0 5 15 25 GPPS 1600 % 30 25 15 5 Total % 100 100 100 100 Notch Izod impact strength ft-lb/in 2.8 1.9 1.2 1.2 Gardner impact strength in-lb 34 21 16 6 Tensile strain at break % 30 27 33 37 Tensile modulus kpsi 392 405 398 390 Tensile stress at break psi 3842 3408 3496 3324 Tensile stress at yield Psi 3870 3846 3859 3810 Energy to break in-lbf 137 125 132 143 Ultimate elongation % 38 38 34 31 Energy to break (rounded) In-lbf 340 320 280 250