IMPACT MODIFIED STYRENE COPOLYMER COMPOSITION COMPRISING POLYSILOXANE ADDITIVE HAVING IMPROVED ABRASION CHARACTERISTICS

Abstract

Thermoplastic polymer compositions (P) comprising at least one styrene-based polymer composition (A) comprising at least one graft copolymer (A-1), at least one organopolysiloxane compound, and optionally at least one colorant, dye or pigment, and/or at least one further additive, shows improved properties with respect to residual gloss after abrasion combined with improved melt flow characteristics while heat resistance is not affected.

Claims

1-15. (canceled)

16. A thermoplastic polymer composition (P) comprising: (A) 82 to 99.75 wt.-% of at least one styrene-based polymer composition (A) comprising at least one graft copolymer (A-1); (B) 0.25 to 18 wt.-% of at least one organopolysiloxane compound; (C) 0 to 10 wt.-% of at least one colorant, dye, or pigment; and (D) 0 to 3 wt.-% of at least one further additive, wherein the constituents (A) to (D) sum up to 100 wt.-% of the thermoplastic polymer composition (P).

17. The thermoplastic polymer composition (P) according to claim 16 comprising: (A) 89 to 98.5 wt.-% of a styrene-based polymer composition (A) comprising at least one graft copolymer (A-1); (B) 0.5 to 10 wt.-% of at least one organopolysiloxane compound; (C) 0.5 to 5 wt.-% of at least one colorant, dye, or pigment; and (D) 0.5 to 3 wt.-% of at least one further additive, wherein the constituents (A) to (D) sum up to 100 wt.-% of the thermoplastic polymer composition (P).

18. The thermoplastic polymer composition (P) according to claim 16, wherein the at least one graft copolymer (A-1) is selected from poly(acrylonitrile-butadiene-styrene) (ABS), poly(acrylonitrile-styrene-acrylic ester) (ASA), and mixtures thereof.

19. The thermoplastic polymer composition (P) according to claim 18, wherein the average particle size D.sub.50 of the rubber particles in the ABS copolymer is from 50 to 750 nm and the average particle size D.sub.50 of the rubber particles in the ASA copolymer is from 50 to 1000 nm, wherein the average particle size is determined using an ultracentrifuge.

20. The thermoplastic polymer composition (P) according to claim 16, wherein the styrene-based polymer composition (A) further comprises at least one additional thermoplastic polymer selected from polycarbonate (PC), polyamide (PA), poly(styrene-acrylonitrile) (SAN), poly(-methyl styrene-acrylonitrile) (AMSAN), and mixtures thereof.

21. The thermoplastic polymer composition (P) according to claim 16, wherein the at least one organopolysiloxane compound (B) has a weight average molecular weight Mw of 100,000 g/mol to 1,000,000 g/mol, determined by gel permeation chromatography (GPC) relative to polystyrene as standard and THF as solvent.

22. The thermoplastic polymer composition (P) according to claim 16, wherein the at least one organopolysiloxane compound (B) is selected from a poly(dialkylsiloxane) compound with each alkyl group independently comprising 1 to 10 carbon atoms.

23. The thermoplastic polymer composition (P) according to claim 16, wherein the organopolysiloxane compound (B) is selected from poly(dimethylsiloxane), poly(diethylsiloxane), poly(dipropylsiloxane), poly(dibutylsiloxane), and mixtures thereof.

24. The thermoplastic polymer composition (P) according to claim 16, wherein the surface of the thermoplastic polymer composition (P) has a residual gloss of more than 30% after abrasion was effected according to norm PV3975 compared to the surface of the non-abraded thermoplastic polymer composition (P).

25. The thermoplastic polymer composition (P) according to claim 16, wherein the melt volume-flow rate (MVR, 220 ml/10 min according to ISO 1133) of the thermoplastic polymer composition (P) is increased by a factor of at least 1.5 compared to the melt volume-flow rate of a thermoplastic polymer composition which does not comprise the at least one organopolysiloxane compound (B).

26. The thermoplastic polymer composition (P) according to claim 16, wherein the Vicat softening temperature (VST B50, according to DIN EN ISO 306) of the thermoplastic polymer composition (P) is reduced by less than 5 C. compared to the Vicat softening temperature of a thermoplastic polymer composition which does not comprise the at least one organopolysiloxane compound (B).

27. The thermoplastic polymer composition (P) according to claim 16, wherein the Charpy notched impact strength of the thermoplastic polymer composition (P) is reduced by less than 4 kJ/m.sup.2, compared to the Charpy notched impact strength of a thermoplastic polymer composition which does not comprise the at least one organopolysiloxane compound (B).

28. A process for preparing a thermoplastic polymer composition (P) according to claim 16, wherein the process comprises at least the following steps: a) providing the components (A) to (D) in the predetermined amounts to an optionally heatable mixing device; and b) blending the components (A) to (D) in the optionally heatable mixing device at temperatures above the glass transition point of the components (A) to (D) to obtain the thermoplastic polymer composition (P).

29. A molded article, prepared from the thermoplastic polymer composition (P) according to claim 16.

30. A method of making components or articles for electronic devices, household goods, and automotive parts, comprising the thermoplastic polymer composition (P) according to claim 16.

31. The method of making components or articles for electronic devices, household goods, and automotive parts, comprising the molded article according to claim 29.

32. The molded article according to claim 29, wherein the molded article is a component or article for electronic devices, household goods, and automotive parts.

33. The thermoplastic polymer composition (P) according to claim 16, wherein the thermoplastic polymer composition (P) comprises as constituent (B) 0.25 to 12 wt.-% of at least one organopolysiloxane compound.

34. The thermoplastic polymer composition (P) according to claim 16, wherein the thermoplastic polymer composition (P) comprises as constituent (B) 0.25 to 5 wt.-% of at least one organopolysiloxane compound.

35. The thermoplastic polymer composition (P) according to claim 17, wherein the thermoplastic polymer composition (P) comprises as constituent (B) 0.25 to 6 wt.-% of at least one organopolysiloxane compound.

36. The thermoplastic polymer composition (P) according to claim 17, wherein the thermoplastic polymer composition (P) comprises as constituent (B) 0.25 to 3 wt.-% of at least one organopolysiloxane compound.

Description

EXAMPLES

[0174] Materials

[0175] Constituents A, C and D:

[0176] The styrene-based polymer constituent (A) was provided in form of a blend having the following composition A*:

[0177] 23.64 wt.-% AMSAN having an acrylonitrile content of 30 wt.-%;

[0178] 33.14 wt.-% SAN having an acrylonitrile content of 35 wt.-%;

[0179] 19.32 wt.-% ASA graft rubber having a mean particle diameter D.sub.50 of 90 nm; and

[0180] 12.75 wt.-% ASA graft rubber having a mean particle diameter D.sub.50 of about 550 nm.

[0181] The constituent (A) consisted to 88.85 wt.-% of the above described polymer composition A* and further comprised 9.70 wt.-% of a colorant constituent (C) in form of a colorant master batch comprising 20 wt.-% carbon black in a SAN copolymer matrix. Furthermore, 1.45 wt.-% of additive constituents (D) were present in constituent (A) in form of lubricants (polyethylene wax), plasticizers (DPHP IBC), light stabilizers (Tinuvin 770, BASF) and further stabilizers (Cyasorb 3853). Constituent (A) is commercial available from INEOS Styrolution Group GmbH, Germany.

[0182] Constituent B:

[0183] The polysiloxane constituent (B) was provided in form of a master batch comprising 50 wt.-% of a ultra high molecular weight siloxane polymer dispersed in a poly(styrene-acrylonitrile) (SAN) carrier. The master batch is commercially available (Dow Corning MB50-008 Masterbatch).

[0184] Sample Preparation

[0185] The samples according to Examples 1 to 3 were prepared by compounding constituents A, C, D and B using a twin screw extruder (model ZSK26MC, Coperion GmbH, length: 1035 mm) at T.sub.m=240 C. according to the specific ratios given in Table 1 below. DIN A5 size samples have been prepared via injection molding (T.sub.m: 242 C.).

[0186] Comparative Example 1 was prepared by producing DIN A5 size samples of the constituents A, C and D (see Table 1) prior to the addition of with Dow Corning MB50-008 Masterbatch via injection molding (T.sub.m: 242 C.).

[0187] Comparative Example 2 was prepared by producing DIN A5 size samples of poly(methyl methacrylate) (Plexiglas 7N, available from Evonik Performance Materials GmbH, Germany) via injection molding (T.sub.m: 242 C.).

[0188] The composition of the samples according to Example 1 to 3 and Comparative Example 1 are given in Table 1.

TABLE-US-00001 TABLE 1 Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 1 Constituent (wt.-%) (wt.-%) (wt.-%) (wt.-%) Constituent A Composition described 98.0 97.0 96.0 100 above including (A), (C) and (D) Constituent B poly(siloxane) 1 1.5 2 SAN 1 1.5 2

[0189] Testing Methods

[0190] The properties of the thermoplastic polymer compositions (P) were evaluated by the following testing methods. The same methods were applied to determine the properties of the constituents (A) to (D), where necessary.

[0191] Residual Gloss

[0192] Abrasion was effected according to testing Norm PV3975. A Martindale abrasion tester was used with 281Q WOD abrasive paper (9mic, 215.9 mm*279 mm, 3M). All samples have been conditioned at 18-28 C./50% relative humidity for 7 days. The number of cycles during testing was 10 with a load of 12 kPa. After abrasion, gloss was measured at 20 using a Multigloss 268 (Konica Minolta). Gloss retention (residual gloss) is calculated as follows:

[00001]$\mathrm{residual}.Math..Math.\mathrm{gloss}=\frac{\mathrm{gloss}.Math..Math.\mathrm{after}.Math..Math.\mathrm{testing}}{\mathrm{initial}.Math..Math.\mathrm{gloss}}$

[0193] Melt volume-flow rate (MVR 220 C./10 kg) was measured according to ISO 1133.

[0194] Charpy notched impact strength was measured according to DIN EN ISO 179-1/1eA. Heat resistance (VST B50) was measured according to DIN EN ISO 306.

[0195] The mean particle diameter D.sub.50 may be determined by ultracentrifuge measurements (see W. Scholtan, H. Lange: Kolloid Z. & Z. Polymere 250, p. 782 to 796 (1972)). The weight average molecular weight Mw was determined by gel permeation chromatography using UV-detection. Polystyrene was used as standard. Typically, tetrahydrofuran was used as solvent. The test results are summarized in Table 2.

TABLE-US-00002 TABLE 2 Charpy Vicat notched softening impact point Residual gloss MVR 220/10 strength (VST B50) Example [%] [ml/10 min] [kJ/m.sup.2] [ C.] Ex. 1 23.9 13.68 14.86 104 Ex. 2 22.3 14.35 14.75 103 Ex. 3 32.5 14.65 13.56 102 Comp. Ex. 1 8.9 4.3 14.9 103 Comp. Ex. 2 35.9

[0196] The experimental data summarized in Table 2 show that the addition of small amounts of the polysiloxane compound (B) according to the invention to the styrene-based polymer composition is able to have a dramatic improvement with respect to the residual gloss of the test samples of Examples 1 to 3 compared to Comparative Example 1, whereas the melt volume-flow rate (MVR) is also substantially improved by a factor of about 3.

[0197] Moreover, Charpy notched impact strength as well as heat resistance (determined as Vicat softening point) of the test samples prepared in accordance to the invention are not adversely affected by the addition of polysiloxane compound (B). The thus obtained improved characteristics of the thermoplastic polymer composition (P) according to the present invention turn the copolymer composition to a convenient and inexpensive alternative to poly(methyl-methacrylate) compositions and/or UV-cured surfaces in applications such as housings of household goods and electronic devices as well as interior parts in the automotive industry.