LOW-DENSITY ABS COMPOSITES

Abstract

The invention relates to a thermoplastic molding composition comprising 5.0 to 57 wt.-% ABS graft copolymer (A); 30.5 to 80 wt.-% SAN copolymer (B) 1.5 to 9.5 wt.-% copolymer (C) with epoxy, maleic anhydride or maleic imide functions; 5 to 29 wt.-% of hollow glass microspheres (D); 6 to 12 wt.-% of glass fibers (E); 0 to 5 wt.-% additives and/or processing aids (F), having a low density and high strength, and a process for its preparation, shaped arti-cles thereof, and its use in the electronics sector.

Claims

1-15. (canceled)

16. A thermoplastic molding composition comprising components A, B, C, D, E, and, if present, F: (A) 5.0 to 57.0 wt.-% of at least one graft copolymer (A) consisting of 15 to 60 wt.-% of a graft sheath (A2) and 40 to 85 wt.-% of a graft substrate (A1), wherein the graft substrate (A1) is an agglomerated butadiene rubber latex and wherein (A1) and (A2) sum up to 100 wt.-%, obtained by emulsion polymerization of styrene and acrylonitrile in a weight ratio of 95:5 to 50:50 to obtain the graft sheath (A2), wherein the styrene and/or the acrylonitrile is optionally partially replaced by alpha-methylstyrene, methyl methacrylate, maleic anhydride, or mixtures thereof, in the presence of at least one agglomerated butadiene rubber latex (A1) with a median weight particle diameter D50 of 200 to 800 nm; wherein the agglomerated butadiene rubber latex (A1) is obtained by agglomeration of at least one starting butadiene rubber latex (S-A1) having a median weight particle diameter D.sub.50 of equal to or less than 120 nm; (B) 30.5 to 80 wt.-% of at least one copolymer (B) of styrene and acrylonitrile in a weight ratio of from 81:19 to 65:35, wherein the styrene and/or the acrylonitrile is optionally partially replaced by methyl methacrylate, alpha-methyl styrene, and/or 4-phenylstyrene; wherein copolymer (B) has a weight average molar mass M.sub.w of 90,000 to 145,000 g/mol; (C) 1.5 to 9.5 wt.-% of at least one copolymer (C) with at least one functional group selected from epoxy, maleic anhydride, and maleic imide as a compatibilizing agent; (D) 5 to 29 wt.-% of hollow glass microspheres (D); (E) 6 to 12 wt.-% of glass fibers (E); and (F) 0 to 5 wt.-% of at least one additive and/or processing aid (F) which is different from (D) and (E); wherein the components A, B, C, D, E, and, if present F, sum to 100 wt.-%.

17. The thermoplastic molding composition of claim 16 comprising components A, B, C, D, E, and F in the following amounts: (A): 5.99 to 50.99 wt.-%; (B): 35 to 80 wt.-%; (C): 2 to 8 wt.-%; (D): 5 to 25 wt.-%; (E): 7 to 11.5 wt.-%; and (F): 0.01 to 5 wt.-%.

18. The thermoplastic molding composition of claim 16 comprising components A, B, C, D, E, and F in the following amounts: (A): 11.95 to 41.95 wt.-%; (B): 40 to 70 wt.-%; (C): 3 to 6 wt.-%; (D): 8 to 22 wt.-%; (E): 7 to 11.5 wt.-%; and (F): 0.05 to 4 wt.-%.

19. The thermoplastic molding composition of claim 16, wherein component (C) comprises structural units derived from maleic imide and/or maleic anhydride in an amount of from 6 to 12 wt.-%.

20. The thermoplastic molding composition of claim 16, wherein component (C) is selected from the group consisting of: styrene-maleic anhydride copolymers, styrene-acrylonitrile-maleic anhydride-terpolymers, styrene-N-phenyl maleic imide-copolymers, and styrene-acrylonitrile-N-phenyl maleic imide-terpolymers.

21. The thermoplastic molding composition of claim 16, wherein the hollow glass microspheres (D) have a particle size (D.sub.50) in the range of 25 to 45 μm.

22. The thermoplastic molding composition of claim 16, wherein the glass fibers (E) are chopped glass fibers.

23. The thermoplastic molding composition of claim 16, wherein the agglomerated butadiene rubber latex (A1) has a median weight particle diameter D.sub.50 of 280 to 350 nm.

24. The thermoplastic molding composition of claim 16, wherein the graft sheath (A2) is obtained by emulsion polymerization of styrene and acrylonitrile solely; and copolymer (B) is a copolymer of styrene and acrylonitrile solely.

25. The thermoplastic molding composition of o claim 16, wherein copolymer (B) is a copolymer of styrene and acrylonitrile in a weight ratio of from 76:24 to 70:30.

26. The thermoplastic molding composition of claim 16, wherein copolymer (B) has a melt flow index (MFI) of more than 60 g/10 min (ASTM D1238).

27. A process for the preparation of the thermoplastic molding composition of claim 16 comprising the following steps: i) optionally premixing of components A, B, C, D, and, if present, F, ii) melt mixing and kneading or rolling of components A, B, C, D, and, if present, F, or of the mixture obtained in step i), to obtain a molten uniform mixture at a temperature in the range of from 160° C. to 300° C., and iii) addition of component E) in the molten uniform mixture obtained in step ii).

28. A shaped article comprising the thermoplastic molding composition of claim 16.

29. An electronic application comprising the thermoplastic molding composition of claim 16.

30. An electronic application comprising the shaped article of claim 28.

31. An electronic device requiring a high endurance and fatigue resistance comprising the thermoplastic molding composition of claim 16.

32. An electronic device requiring a high endurance and fatigue resistance comprising the shaped article of claim 28.

33. The thermoplastic molding composition of claim 16, wherein: (A) the at least one graft copolymer (A) consists of 20 to 50 wt.-% of the graft sheath (A2) and 50 to 80 wt.-% of the graft substrate (A1), wherein the agglomerated butadiene rubber latex (A1) is obtained by agglomeration of at least one starting butadiene rubber latex (S-A1) having a median weight particle diameter D.sub.50 of equal to or less than 110 nm.

34. The thermoplastic molding composition of claim 16, wherein the hollow glass microspheres (D) have a particle size (D.sub.50) in the range of 30 to 40 μm.

35. The thermoplastic molding composition of claim 16, wherein the agglomerated butadiene rubber latex (A1) has a median weight particle diameter D.sub.50 of 300 to 350 nm.

Description

EXAMPLES

Test Methods

[0124] Particle Size Dw/D50

[0125] For measuring the weight average particle size Dw (in particular the median weight particle diameter D50) with the disc centrifuge DC 24000 by CPS Instruments Inc. equipped with a low density disc, an aqueous sugar solution of 17.1 mL with a density gradient of 8 to 20% by wt. of saccharose in the centrifuge disc was used, in order to achieve a stable flotation behavior of the particles. A polybutadiene latex with a narrow distribution and a mean particle size of 405 nm was used for calibration. The measurements were carried out at a rotational speed of the disc of 24,000 r.p.m. by injecting 0.1 mL of a diluted rubber dispersion into an aqueous 24% by wt. saccharose solution. The calculation of the weight average particle size Dw was performed by means of the formula

D.sub.w=sum (n.sub.i*d.sub.i.sup.4)/sum(n.sub.i*d.sub.i.sup.3)

n.sub.i: number of particles of diameter di.

[0126] Molar Mass M.sub.w: The weight average molar mass M.sub.w is determined by GPC (solvent:

[0127] tetrahydrofuran, polystyrene as polymer standard) with UV detection according to DIN 55672-1:2016-03.

[0128] Melt Flow Index (MFI) or Melt Volume Flow Rate (MFR): MFI/MFR test was performed on pellets (ASTM D 1238) using a MFI-machine of CEAST, Italy.

[0129] Impact test: Izod impact tests were performed on notched specimens (ASTM D 256 standard) using an instrument of CEAST (part of Instron's product line), Italy.

[0130] Tensile test: Tensile test was carried out at 23° C. using a Universal testing Machine (UTM) of Lloyd Instruments, UK.

[0131] Flexural test: Flexural test was carried out at 23° C. (ASTM D 790 standard) using a UTM of Lloyd Instruments, UK.

[0132] Heat deflection temperature (HDT): Heat deflection temperature test was performed on injection molded specimen (ASTMD 648 standard) using a CEAST, Italy instrument.

[0133] VICAT Softening Temperature (VST): VST test was performed on injection molded test specimen (ASTM D 1525-09 standard) using a Zwick Roell machine, Germany. Test was carried out at a heating rate of 120° C./hr (Method B) at 50 N loads.

[0134] Rockwell Hardness: Hardness of the injection molded test specimen (ISO—2039/211) was carried out on FIE, India.

[0135] Specific gravity: The measurement was done on a specific gravity (ASTM D 792) balance from Mettler Toledo.

[0136] Strength to weight ratio: measured as the ratio of tensile strength to the specific gravity of the material.

[0137] Yellowness Index: testing as per ASTM E313 at D65/10

[0138] Materials used in the experiments:

Component (A)

Fine-Particle Butadiene Rubber Latex (S-A1)

[0139] The fine-particle butadiene rubber latex (S-A1) which is used for the agglomeration step was produced by emulsion polymerization using tert-dodecylmercaptan as chain transfer agent and potassium persulfate as initiator at temperatures from 60° to 80° C. The addition of potassium persulfate marked the beginning of the polymerization. Finally the fine-particle butadiene rubber latex (S-A1) was cooled below 50° C. and the non reacted monomers were removed partially under vacuum (200 to 500 mbar) at temperatures below 50° C. which defines the end of the polymerization. Then the latex solids (in % per weight) were determined by evaporation of a sample at 180° C. for 25 min. in a drying cabinet. The monomer conversion is calculated from the measured latex solids.

[0140] The butadiene rubber latex (S-A1) is characterized by the following parameters, see table 1.

[0141] Latex S-A1-1

[0142] No seed latex is used. As emulsifier the potassium salt of a disproportionated rosin (amount of potassium dehydroabietate: 52 wt.-%, potassium abietate: 0 wt.-%) and as salt tetrasodium pyrophosphate is used.

TABLE-US-00001 TABLE 1 Composition of the butadiene rubber latex S-A1 Latex S-A1-1 Monomer butadiene/styrene 90/10 Seed Latex (wt.-% based on monomers) ./. Emulsifier (wt.-% based on monomers) 2.80 Potassium Persulfate (wt.-% based on monomers) 0.10 Decomposed Potassium Persulfate (parts per 0.068 100 parts latex solids) Salt (wt.-% based on monomers) 0.559 Salt amount relative to the weight of solids of the 0.598 rubber latex Monomer conversion (%) 89.3 Dw (nm) 87 pH 10.6 Latex solids content (wt-%) 42.6 K 0.91 K = W * (1-1.4 * S ) * Dw W = decomposed potassium persulfate [parts per 100 parts rubber] S = salt amount in percent relative to the weight of solids of the rubber latex Dw = weight average particle size (=median particle diameter D.sub.50) of the fine-particle butadiene rubber latex (S-A1)

Production of the Coarse-Article, Agglomerated Butadiene Rubber Latices (A1)

[0143] The production of the coarse-particle, agglomerated butadiene rubber latices (A1) was performed with the specified amounts mentioned in table 2. The fine-particle butadiene rubber latex (S-A1) was provided first at 25° C. and was adjusted if necessary with deionized water to a certain concentration and stirred. To this dispersion an amount of acetic anhydride based on 100 parts of the solids from the fine-particle butadiene rubber latex (S-A1) as fresh produced aqueous mixture with a concentration of 4.58 wt.-% was added and the total mixture was stirred for 60 seconds.

[0144] After this the agglomeration was carried out for 30 minutes without stirring. Subsequently KOH was added as a 3 to 5 wt.-% aqueous solution to the agglomerated latex and mixed by stirring. After filtration through a 50 μm filter the amount of coagulate as solid mass based on 100 parts solids of the fine-particle butadiene rubber latex (B) was determined. The solid content of the agglomerated butadiene rubber latex (A), the pH value and the median weight particle diameter D.sub.50 was determined.

TABLE-US-00002 TABLE 2 Production of the coarse-particle, agglomerated butadiene rubber latices (A1) latex A1 A1-1 A1-2 used latex S-A1 S-A1-1 S-A1-1 concentration latex S-A1 before wt.-% 37.4 37.4 agglomeration amount acetic anhydride parts 0.90 0.91 amount KOH parts 0.81 0.82 concentration KOH solution wt-% 3 3 solid content latex A1 wt-% 32.5 32.5 coagulate parts 0.01 0.00 PH 9.0 9.0 D.sub.50 nm 315 328

Production of Graft Copolymer (A)

[0145] 59.5 wt.-parts of mixtures of the coarse-particle, agglomerated butadiene rubber latices A1-1 and A1-2 (ratio 50:50, calculated as solids of the rubber latices (A1)) were diluted with water to a solid content of 27.5 wt.-% and heated to 55° C. 40.5 wt.-parts of a mixture consisting of 72 wt.-parts styrene, 28 wt.-parts acrylonitrile and 0.4 wt.-parts tert-dodecylmercaptan were added in 3 hours 30 minutes. At the same time when the monomer feed started the polymerization was started by feeding 0.15 wt.-parts cumene hydroperoxide together with 0.57 wt.-parts of a potassium salt of disproportionated rosin (amount of potassium dehydroabietate: 52 wt.-%, potassium abietate: 0 wt.-%) as aqueous solution and separately an aqueous solution of 0.22 wt.-parts of glucose, 0.36 wt.-% of tetrasodium pyrophosphate and 0.005 wt.-% of iron-(II)-sulfate within 3 hours 30 minutes. The temperature was increased from 55 to 75° C. within 3 hours 30 minutes after start feeding the monomers. The polymerization was carried out for further 2 hours at 75° C. and then the graft rubber latex (=graft copolymer A) was cooled to ambient temperature. The graft rubber latex was stabilized with ca. 0.6 wt.-parts of a phenolic antioxidant and precipitated with sulfuric acid, washed with water and the wet graft powder was dried at 70° C. (residual humidity less than 0.5 wt.-%).

Component (B)

[0146] Statistical copolymer (B-1) from styrene and acrylonitrile with a ratio of polymerized styrene to acrylonitrile of 72:28 with a weight average molecular weight Mw of 110,000 g/mol, and a MFI at 220° C./10kg of 61 g/10 minutes, produced by free radical solution polymerization.

[0147] Statistical copolymer (B-2) from styrene and acrylonitrile with a ratio of polymerized styrene to acrylonitrile of 78:22 with a weight average molecular weight Mw of 165,000 g/mol, and a MFI at 220° C./10kg of 36 g/10 minutes, produced by free radical solution polymerization.

Component (C)

[0148] Fine-Blend® SAM-010 (terpolymer of styrene, acrylonitrile and maleic anhydride, with 8±2 wt.-% maleic anhydride, Mw 90,000 to 100,000 g/mol) from Fine-blend Compatilizer Jiangsu Co., LTD, China.

Component (D)

[0149] Hollow glass beads having a true density of 0.58 to 0.62 g/cm.sup.3, a bulk density of 0.33 to 0.36 g/cm.sup.3 and a compressive strength of 125 MPa, particle diameter (D50) 35 μm.

TABLE-US-00003 Material Name Hollow glass microspheres HK60 - 18000 Chemical Name Soda Lime Borosilicate Glass CAS No.(65997-17-3) Trade Name HK60- 18000 Supplier Zhengzhou Hollowlite Materials Co., Ltd

Component (E)

[0150] Chopped glass fibers—composed of Aluminium borosilicate (E-glass) with less than 1% alkali oxides—having a diameter and length of 13 μm and 3 mm, respectively and a density of 2.6 g/cm.sup.3. The surface of the glass fibers is given a Silane treatment. Said glass fibers are commercially available from Nippon Electric glass, Japan.

Component (F)

[0151]

TABLE-US-00004 F1 Ethylene bis stearamide (EBS) ‘Palmowax’ from Palmamide Sdn Bhd, Malaysia F3 Magnesium oxide (MgO) from Kyowa Chemicals F4 Distearyl pentaeritritol diphosphite (SPEP) from Addivant, Switzerland F5 Silicon oil having a kinematic viscosity of 1000 centiStokes from KK Chempro India Pvt Ltd

Thermoplastic Compositions

[0152] All components were weighed and used in amounts according to the compositions given in Tables 3 and 4.

[0153] The batch size for all the compounding and extrusion trials was 10 kg. Components (A), (B), (C) and (F) were mixed for 2 to 3 minutes at an average speed of 2200 rpm in a high speed mixer to obtain a uniform premix and then the hollow glass beads (HGB, component (D))—mixed with 1% water—were added to the premix and then mixed for only 20-30 seconds at 2200 rpm to attain good dispersion and create uniform premix for compounding. Minimum time is kept for mixing after adding HGB to avoid the undesired breakage of the HGB. The premix prepared was then extruded through a twin-screw extruder. The extruder has co-rotating screws and has a separating feeding hopper (side feeder) after mixing zones, for feeding glass fibres (component (E)). The premix was melt blended in said twin-screw extruder at a screw speed of 350 rpm and using an incremental temperature profile from 215° C. to 250° C. for the different barrel zones. The glass fibres were separately fed during compounding through said side feeder of the extruder. The extruded reinforced polymer blend strands were water cooled, air-dried and pelletized.

[0154] This was followed by injection moulding to mould the standard test specimens. The temperature profile of the injection moulding machine barrel was 220 to 240° C. incremental. The test data of the obtained ABS compositions are shown on Table 5 and 6.

TABLE-US-00005 TABLE 3 Reinforced ABS compositions Compound set 1 (amounts in wt.-%) Comparative Comparative Comparative Comparative Components Example 1 Example 2 Example 3 Example 4 A 19.57 19.57 19.57 19.57 B1 63.60 53.82 78.28 B2 68.49 C 4.89 4.89 D 9.78 19.57 E 9.78 F 1 1.47 1.47 1.47 1.47 F 2 0.29 0.29 0.29 0.29 F 3 0.10 0.10 0.10 0.10 F 4 0.15 0.15 0.15 0.15 F 5 0.15 0.15 0.15 0.15

TABLE-US-00006 TABLE 4 Reinforced ABS compositions Compound set 2 (amounts in wt.-%) Comparative Comparative Components Example 1 Example 2 Example 3 Example 5 A 19.57 19.57 19.57 19.57 B1 53.82 44.03 58.71 B2 68.49 C 4.89 4.89 D 9.78 19.57 E 9.78 9.78 9.78 19.57 F 1 1.47 1.47 1.47 1.47 F 2 0.29 0.29 0.29 0.29 F 3 0.10 0.10 0.10 0.10 F 4 0.15 0.15 0.15 0.15 F 5 0.15 0.15 0.15 0.15

TABLE-US-00007 TABLE 5 Properties - Compound set 1 Compound set 1 Comparative Comparative Comparative Comparative Properties Unit Example 1 Example 2 Example 3 Example 4 Melt Flow Rate g/10 min 21.5 14 9 47.5 NIIS, 6.4 mm kg .Math. cm/cm 2.1 1.8 5.0 8.0 Tensile Strength kg/cm.sup.2 410 365 575 495 Tensile Modulus kg/cm.sup.2 32950 34600 45000 29200 Elongation at Break % 5 3 4 17 Flexural Strength kg/cm.sup.2 860 780 900 935 Flexural Modulus kg/cm.sup.2 35200 36350 34000 32550 Rockwell Hardness R-Scale 110 HDT, Annealed ° C. 97.5 97 99 98.0 VST ° C. 100 101.5 105 100.5 Specific gravity — 1.015 ~0.9 1.1 1.055 Strength to weight — 403.9 405.6 522.7 469.2 ratio Yellowness Index — 23.03 17.15 28.69

TABLE-US-00008 TABLE 6 Properties - Compound set 2 Comparative Comparative Properties Unit Example 1 Example 2 Example 3 Example 5 Melt Flow Rate g/10 min 13.0 6.0 9 20.5 NIIS, 6.4 mm kg .Math. cm/cm 6.0 4.5 5.0 5.5 Tensile Strength kg/cm.sup.2 650 550 575 810 Tensile Modulus kg/cm.sup.2 58400 55900 45000 67550 Elongation at Break % 2.4 1.9 4 1.7 Flexural Strength kg/cm.sup.2 1205 1030 900 1260 Flexural Modulus kg/cm.sup.2 54650 52800 34000 66950 Rockwell Hardness R-Scale 108 107 110 111 HDT, Annealed °C 101 99.5 99 101 VST °C 106 105 105 103.5 Specific gravity — 1.094 1.023 1.1 1.198 Strength to weight ratio — 594 537.6 522.7 676.1 Yellowness Index — 22.71 19.38 32.38

[0155] The data according to Table 6 prove that the inventive reinforced ABS compositions (Examples 1 and 2) have a reduced specific gravity without compromising the mechanical properties in comparison to non-inventive or prior art reinforced ABS compositions.

[0156] Even with a load of only 9.78 wt.-% glass fiber good mechanical properties—close to mechanical properties obtained for 19.57 wt.-% glass fiber filled ABS compositions (cp. comparative Example 5)—are achieved with a lower specific gravity.

[0157] Thus, the reinforced ABS compositions according to the invention combine lightweight and good mechanical properties with a better cost efficiency (in comparison to expensive fibers like carbon/nanotube).