Thermoplastic molding composition and articles made thereof having improved surface quality

Abstract

The present invention relates to a process for producing a thermoplastic molding composition and articles made thereof having improved surface quality, in particular improved surface quality after exposure to warm-humid environmental conditions. The thermoplastic molding composition comprises a thermoplastic polymer A, a graft copolymer B obtained by emulsion graft polymerization and optionally a further polymer component P, as well as optional further components/additives K, wherein at least one crystallization additive C, selected from phosphate compounds having 1 to 25 phosphate units, organic acids and salts thereof, is added during or after the preparation of the graft copolymer B.

Claims

1. A process for the preparation of a thermoplastic molding composition comprising: A: 5 to 95% by weight, based on the total molding composition, at least on thermoplastic polymer A, which comprises at least one vinylaromatic monomer A1 and optionally at least one further ethylenically unsaturated monomer A2; B: 5 to 95% by weight, based on the total molding composition, at least one graft copolymer B comprising: B1: 5 to 95% by weight, based on the graft copolymer B, at least one graft base B1, obtained by emulsion polymerization of: B11: 70 to 100% by weight, based on the graft base B1, at least one ethylenically unsaturated monomer B11; B12: 0 to 10% by weight, based on the graft base B1, at least on polyfunctional cross-linking monomer B12, different from B11; and B13 0 to 30% by weight, based on the graft base B1, at least one further copolymerizable monoethylenically unsaturated monomer B13 different from B11 and B12; and optional addition of B14: 0 to 5% by weight, based on the graft base B1, at least one agglomerating component B14, wherein the sum of B11, B12, B13, and B14 is 100% by weight; and B2: 5 to 95% by weight, based on the graft copolymer B, at least one graft shell B2, which is obtained by emulsion polymerization in the presence of the at least one graft base B1 of: B21 50 to 100% by weight, based on the graft shell B2, at least one vinylaromatic monomer B21; and B22 0 to 50% by weight, based on the graft shell B2, at least one ethylenically unsaturated monomer B22, wherein the total sum of graft base B1 and graft shell B2 is 100% by weight; P: 0 to 90% by weight, based on the total molding composition, at least one further polymer component P; and K: 0 to 40% by weight, based on the total molding composition, at least one additive K; wherein the process comprises the steps: a) preparation of the at least one graft base B1 via emulsion polymerization of the at least one monomer B11, and optional B12 and/or B13, and optional addition of the at least one agglomerating component B14; b) preparation of the at least one graft copolymer B via emulsion polymerization of the at least one monomer B21 and optional B22 in the presence of the at least one graft base B1; c) precipitation of the graft copolymer B by mixing the graft copolymer B latex obtained in step b) with a precipitation solution S comprising at least one multivalent cation; d) addition of crystallization additive C during and/or after any of steps a), b), and/or c), wherein the crystallization additive C is a mixture comprising disodium dihydrogen diphosphate (Na.sub.2H.sub.2P.sub.2O.sub.7) and tetrasodium diphosphate (Na.sub.4P.sub.2O.sub.7) and the crystallization additive C is added in an amount of 0.005 to 1.6% by weight, based on the solid content of the at least one graft copolymer B; e) mechanical dewatering, optional washing, and optional drying of the precipitated graft copolymer B obtained in step d); and f) mixing of the precipitated graft copolymer B obtained in step e) with component A and optional components P and/or K, wherein the thermoplastic molding composition is obtained.

2. The process of claim 1, wherein the at least one thermoplastic polymer A comprises: A1: 60 to 90% by weight, based on A, at least one vinyl aromatic monomer A1, selected from styrene, a(alpha)-methylstyrene, and para-methylstyrene; and A2: 10 to 40% by weight, based on A, at least one vinyl cyanide monomer as monomer A2, selected from acrylonitrile and/or methacrylonitrile.

3. The process of claim 1, wherein the at least one graft copolymer B comprises: B1: 5 to 95% by weight, based on the graft copolymer B, of at least one graft base B1, which is obtained by emulsion polymerization of: B11: 50 to 100% by weight, based on the graft base B1, butadiene and/or isoprene as monomer B11; and B13: 0 to 50% by weight, based on the graft base B1, at least one further monomer B13 selected from styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, isoprene, chloroprene, C.sub.1-C.sub.4 alkyl styrene, (meth)acrylic acid C.sub.1-C.sub.8-alkyl esters, alkylenglykol-di(meth)acrylate, and divinylbenzene, wherein the sum of B11+B13 is 100% by weight; and B2: 5 to 95% by weight, based on the graft copolymer B, of at least one graft shell B2, which is obtained by emulsion polymerization in the presence of the at least one graft base B1 of: B21 50 to 95% by weight, based on the graft shell B2, of a monomer B21, selected from styrene, a-methylstyrene, and mixtures of styrene and at least one more monomer selected from a-methyl-styrene, p-methylstyrene, and (meth)acrylic acid C.sub.1-C.sub.8-alkyl esters; and B22 5 to 50% by weight, based on the graft shell B2, of a monomer B22, selected from acrylonitrile and mixtures of acrylonitrile and at least one more monomer selected from methacrylonitrile, anhydrides of unsaturated carbon acids, and imides of unsaturated carbon acids, wherein the sum of graft base B1 and graft shell B2 is 100% by weight.

4. The process according to claim 1, wherein the at least one graft copolymer B comprises: B1: 50 to 90% by weight, based on the graft copolymer B, at least one graft base B1 obtained by emulsion polymerization of: B11: 70 to 99.9% by weight, based on the graft base B1, of at least one C.sub.1-C.sub.8 alkyl(meth)acrylate as monomer B11; B12: 0.1 to 10% by weight, based on the graft base B1, of at least on polyfunctional, cross-linking monomer B12; and B13 0 to 29.9% by weight, based on the graft base B1, at least one further copolymerizable monoethylenically unsaturated monomer B13 different from B11 and B12, wherein the sum of B11, B12, and optional B13 is 100% by weight; and B2: 10 to 50% by weight, based on the graft copolymer B, at least one graft shell B2, wherein the at least one graft shell B2 is obtained by emulsion polymerization in the presence of the at least one graft base B1 of: B21: 50 to 95% by weight, based on the graft shell B2, at least one monomer B21, selected from styrene, a(alpha)-methylstyrene, or mixtures of styrene and one further monomer selected from a(alpha)-methylstyrene, p-methylstyrene, and C.sub.1-C.sub.4-alkyl(meth)acrylate; and B22: 5 to 50% by weight, based on the graft shell B2, at least one ethylenically unsaturated monomer B22, selected from acrylonitrile or mixtures of acrylonitrile and at least one further monomer selected from methacrylonitrile, acrylamide, vinylmethylether, anhydrides of unsaturated carboxylic acids, and imides of unsaturated carboxylic acids, wherein the total sum of graft base B1 and graft shell(s) B2 is 100% by weight.

5. The process of claim 1, wherein the thermoplastic molding composition comprises 5 to 60% by weight, based on the total molding composition, at least one further polymer component P selected from polycarbonates, polyamides, and polyesters.

6. The process of claim 1, wherein in step c) the graft copolymer B latex obtained in step b) is mixed with a precipitation solution S comprising at least one salt of multivalent cation selected from alkaline earth metal salts and aluminum salts, wherein the precipitation solution S is used in an amount of 0.5 to 6% by weight, based on the ratio of solids of salt to solids of graft copolymer B latex to be precipitated.

7. The process of claim 1, wherein the crystallization additive C is added in an amount of 0.01 to 1.2% by weight, based on the solid content of the at least one graft copolymer B.

8. The process of claim 1, wherein the crystallization additive C is added to the graft copolymer B latex before or parallel to the precipitation solution S during step c).

9. The process of claim 1, wherein the crystallization additive C is added to the graft copolymer B latex parallel to the precipitation solution S during step c), wherein the crystallization additive C is added in an amount of 0.01 to 1.2% by weight, based on the solid content of the at least one graft copolymer B.

10. The process of claim 1, wherein the crystallization additive C is added to the graft copolymer B during and/or at the end of the dewatering of the precipitated graft copolymer B in step e).

11. The process of claim 1, wherein an aqueous solution of the at least one crystallization additive C is added to the graft copolymer B during and/or at the end of the dewatering of the precipitated graft copolymer B in step e).

12. The process of claim 1, wherein the steps e) and f) comprise mechanical dewatering, drying, and mixing of the precipitated graft copolymer B obtained in step d) with component A and optional components P and/or K, wherein the precipitated and dewatered graft copolymer B is extruded including addition of component A and optional components P and/or K, wherein residual water of dewatered graft copolymer is removed from the extruder as vapor and/or in liquid form.

13. A thermoplastic molding composition obtained by the process of claim 1.

14. The thermoplastic molding composition of claim 13, wherein the graft copolymer B included in the thermoplastic molding composition comprises sodium in an amount from 100 to 3,000 ppm; and phosphor in an amount from 200 to 5,000 ppm, based on the dried graft copolymer B.

Description

EXAMPLES

I. Test Methods

(1) The test methods, which were used for characterization of polymers, are described in the following: a) Izod impact strength b) Melt flowability (MVR) c) Thermal stability (MVR after thermal treatment) d) Hydrolytic stability (MVR after hydrolysis) e) Yellowness Index (YI) f) Gloss g) Hardness h) Vicat temperature i) Particle size by disc centrifuge j) Swelling index and gel content k) pH value I) Thermal stability of graft copolymer B (Scorch Test) m) Number of visible surface defects before and after warm-humid storage n) Determination of solid content o) Sodium, magnesium and phosphor content

(2) a) Izod-impact strength was tested at 23° C. (if not stated otherwise) according to ISO 180/1U (un-notched) or ISO 180/1A (notched), respectively, on bars mold at a mass temperature of 240° C. and a mold temperature of 80° C. If not stated otherwise, the unit is kJ/m.sup.2.

(3) b) Melt flowability or melt flow rate (MVR) was determined on a polymer melt at 220° C. with a load of 10 kg or at 260° C. with load of 5 kg according to DIN EN ISO 1133-2:2011. If not stated otherwise, the unit is ml/10 min.

(4) c) Thermal stability was tested as the MVR (see under b) except that the polymer is held exactly before the MVR test for 15 min at the temperature of measurement which is in this case 300° C. The higher the melt flow the higher the chain degradation by elevated temperature.

(5) d) MVR after hydrolysis was tested as the MVR (see under b) except that the granules kept before the MVR measurement in a humid atmosphere (relative humidity >95%) for seven days at 95° C. Afterwards the polymer is dried as usually. The granules should have the same size and shape in order to compare polymers or polymer blends. The higher the melt flow the higher the chain degradation by hydrolysis.

(6) e) Yellowness Index (YI) was tested according to ASTM E313 on plaques molded at a mass temperature of 240° C. and a mold temperature of 80° C.

(7) f) Gloss was tested according to ISO 2813/DIN 67530 on plaques molded at a mass temperature of 240° C. and a mold temperature of 80° C. with a high quality mold to give smooth high quality surface. If not stated otherwise gloss is measured at 20° which is the preferred angel to compare high gloss plastics.

(8) g) Hardness was tested according to DIN ISO 2039-1:2003-06 on specimen molded at a mass temperature of 240° C. and a mold temperature of 80° C. according to DIN ISO 2039-1:2003-06.

(9) h) Vicat temperature was measured as Vicat B/120 according to DIN ISO 306 on specimen molded at a mass temperature of 240° C. and a mold temperature of 80° C.

(10) i) For particle size, the weight median particle size D.sub.50 is the diameter which divides the population exactly into two equal parts. 50% by weight of the particles are larger than the weight median particle size D.sub.50 and 50% by weight are smaller. Analogously, other D.sub.x values can be defined. Broadness of particle size distribution U is defined by:
U=(D.sub.90−D.sub.10)/D.sub.50.

(11) The particle sizes stated here were measured by a disk centrifuge (CPS, DC24000 UHR). Particle size is given in nm if not stated otherwise.

(12) j) The values indicated for the gel content and swelling index are based on the determination according to the wire cage method in toluene (see Houben-Weyl, Methoden der Organischen Chemie, Makromolekulare Stoffe, part 1, page 307 (1961) Thieme Verlag Stuttgart).

(13) k) pH was measured electronically with a 4 point calibration.

(14) l) Thermal stability of graft copolymer B was tested in Scorch Test as follows:

(15) 3 g of substance to be tested are placed in an aluminum bowl (diameter 5 cm). Said bowl is placed in a pre-heated oven (precision of temperature ±0.5 K) with weak active ventilation. The temperature of the test is 180° C. if not stated otherwise. The sample is monitored and the time until a color change towards brown is noted.

(16) m) Number of visible surface defects before and after warm-humid storage: Testing plaques are produced by injection molding with 240° C. melt temperature and 80° C. mold temperature. For visual inspection, the surface of the plaques needs to be very smooth. This is achieved by using a mold finely polished as is known by those skilled in the art.

(17) Prior to test plaques are inspected visually. Defect visible before warm-humid storage (if any) are marked. These are the visible surface defects before warm-humid storage. Four plates of 50×75 mm are tested. If not stated otherwise the number of defects refers to 150 cm.sup.2 surface area. The sample plaques are stored in water for eight hours at 80° C. The surface to be tested has to be under water the whole time. The number of defects is counted from this. The number of visible defects before warm-humid storage is subtracted to give the final result of visible surface defects after warm-humid storage. Surface defects are all visible disturbances e.g. a hard spot visible under the surface or a blister that can be detected by the human eye without tools, e.g. magnifying glasses, under good illumination. The sample plates are beheld at different angels. The person examining the surface has 120% eyesight at close distance if necessary by wearing glasses to correct e.g. farsightness.

(18) n) A small sample of ca. 5 g is placed in an oven at 180° C. for 25 min. Solid content in % by weight is weight after oven drying divided by weight before oven drying.

(19) o) Sodium, magnesium and phosphor content in the graft copolymers B after drying was determined by atom emission spectroscopy with inductive coupled plasma (ICP-AES) after chemical digestion. The dewatered graft copolymers B were dried in a lab oven at 70° C. for 2 days. Afterwards 200 mg of the polymer sample was dissolved in 5 ml nitric acid (microwave assisted at about 200 bar (total pressure of the digestion mixture) and about 220° C.). This method is described in DIN-ISO 17025.

II. Preparation of ABS Polymer Composition

Example 1 (Comparative)

(20) 1.1 Preparation of Graft Base B1 Latex

(21) Emulsion polymerizations of 0.18 kg styrene monomer and 2.4 kg of butadiene with 5.7 g sodium persulfate, 9.2 g of sodium hydrogencarbonate, 19.5 g potassium stearate/palmitate (technical mixture) and 21 g tert-dodecyl mercaptane (technical mixture) was carried out in a pressurized vessel; styrene was dosed before butadiene and the tert-dodecyl mercaptane was given in three shots (at the beginning, in the middle and at the end of the butadiene feed) to yield latex with 44% by weight total solid content. Particles had a monomodal particle size distribution, an average size D.sub.50 of 100 nm, a gel content of 75% and a swelling degree of 24.

(22) 1.2 Preparation of Agglomerating Component B14 and Agglomeration

(23) Emulsion polymerizations of 2.3 kg of water, 6 g sodium persulfate, 1 g sodium hydrogen carbonate, 2 g sodium hydroxide (60% of salts were dosed in pre-charge), 22 g surfactant (technical mixture of primary and secondary alkane sulfonates with an averaged chain length of 15 carbon atoms) was done in two steps, wherein 10% of surfactant were dosed in pre-charge and the rest was dosed parallel to the second monomer feed. In first step 0.17 kg ethyl acrylate was polymerized. In second step 71 g methacrylamide and 1.3 kg ethyl acrylate were polymerized. Final solids content of agglomerating latex B14 (agglomerating component B14) was 40%. Broadness of particle size distribution U of agglomerating latex B14 was below 0.2 and particle size D.sub.50 was 109 nm.

(24) Graft base B1 latex of example 1.1. was partly agglomerated with 3% by weight of a agglomerating latex B14 (solids of agglomerating latex B14 based on solids of rubber B1) at 60° C. to give a bimodal particle size distribution with small fraction having D.sub.50 value of 134 nm and large fraction having D.sub.50 value of 482 nm.

(25) 1.3 Grafting to form graft copolymer B latex (ABS) 3.3 kg of the resulting agglomerated rubber latex B1 obtained in 1.2 was grafted with 0.79 kg styrene monomer and 0.19 kg acrylonitrile under addition of 14 g potassium stearate/palmitate (technical mixture) and 3 g sodium persulfate. Furthermore, 1.6 kg water was added to give a final solid content of 40% by weight. The resulting graft copolymer dispersion (latex) had a bimodal particle size distribution. The graft copolymer B latex was stabilized with an emulsion of a hindered phenol antioxidant.

(26) 1.4 Workup of Graft Copolymer B Latex

(27) The graft copolymer B latex as obtained in 1.3 was added to an aqueous solution of magnesium sulfate (0.80% by weight, referring to mass of pre-charge) at 88° C. over a period of 3 minutes. Graft copolymer B latex solids content was 20.6% by weight (referring to overall mass) and magnesium sulfate content in overall aqueous phase was 0.40% by weight. Afterwards, the precipitation mixture (slurry) was heated to 112° C. and then cooled to room temperature.

(28) The precipitation mixture (slurry) was mechanically dewatered by a centrifuge (forces of about 600 g for 60 s) and the so-obtained ABS-graft copolymer B was dried slowly in a drying rack over two days at 80° C. The graft copolymer B was obtained as fine, dry powder with a residual moisture content of 0.2% by weight.

(29) 1.5 Compounding of graft copolymer B powder with thermoplastic polymer A and additives K to form thermoplastic molding composition

(30) 47 parts of resulting graft copolymer B powder were compounded with 53 parts thermoplastic polymer A-I, 0.06 parts phenol based stabilizer, 0.12 parts sulfur based stabilizer, and 0.03 parts silicone oil (polydimethylsiloxane) in a twin-screw extruder.

(31) The thermoplastic polymer A-I was a statistical copolymer from styrene and acrylonitrile with a ratio of polymerized styrene to acrylonitrile of 76:24 with a MVR (220° C./10 kg) of 65 mL/10 min. and produced by continuous radical solution polymerization.

(32) The resulting material was tested and results are given in table 2 below.

1.6 Examples 2 to 16

(33) All steps were carried out as in example 1 except that different amounts of the following additives C are added parallel to the magnesium sulfate solution in precipitation step (step 1.4 Workup): C1 orthophosphoric acid H.sub.3PO.sub.4; C2 oxalic acid C.sub.2H.sub.2O.sub.4; C3 citric acid C.sub.6H.sub.8O.sub.7; C4 tetrasodium diphosphate Na.sub.4P.sub.2O.sub.7 and orthophosphoric acid (mass ratio 2:1); C5 tetrasodium diphosphate and oxalic acid (mass ratio 1.8:1); C6 disodium dihydrogen diphosphate, Na.sub.2H.sub.2P.sub.2O.sub.7; C7 sodium hexametaphosphate, Na.sub.6P.sub.6O.sub.18; C8 tetrasodium diphosphate, Na.sub.4P.sub.2O.sub.7; C9 neutralized polyphosphate of medium chain-length (technical mixture, commercially available as Calgon® N from BK Giulini GmbH); C10 sodium hydrogen carbonate, NaHCO.sub.3; C11 disodium hydrogen phosphate, Na.sub.2HPO.sub.4.

(34) The examples 1 to 16 are summarized in the following table 1, wherein the amount of additives C given in % by weight referring to solids (solid content) of graft copolymer B. Further, the amount of additives C given in % by weight is based on the solids of additive C.

(35) TABLE-US-00001 TABLE 1 Examples 1 to 16 Crystallization Amount C Example Comment additive C [% by weight] 1 Comparative No — 2 Inventive C1 0.142 3 Inventive C2 0.142 4 Inventive C3 0.142 5 Inventive C4 0.142 6 Inventive C5 0.142 7 Inventive C6 0.142 8 Inventive C7 0.142 9 Inventive C8 0.142 10 Comparative C9 0.142 11 Comparative C10 0.142 12 Comparative C11 1.70 13 Inventive C11 0.568 14 Inventive C11 0.142 15 Inventive C11 0.0355 16 Comparative C11 0.00444

(36) The resulting ABS material according to examples 1 to 16 was tested and the results are given in table 2 below.

(37) TABLE-US-00002 TABLE 2 Test results for ABS polymer compositions, Ex. 1-Ex.16 Defects Defects before after warm- warm- Scorch Un- humid humid test Notched notched Gloss storage storage (powder) Izod RT Izod RT 20° YI Test method m) m) l) a) a) f) e) Unit number/ number/ Ex. 150 cm.sup.2 150 cm.sup.2 min [kJ/m.sup.2] [kJ/m.sup.2] 1 Com 12 386 105 36.5 192 89.9 25.2 2 Inv 0 72 245 36.0 201 90.2 25.5 3 Inv 0 114 98 36.8 199 90.2 24.9 4 Inv 0 70 115 36.4 199 89.7 25.0 5 Inv 1 87 301 36.0 200 91.0 25.7 6 Inv 0 66 316 35.9 198 90.4 25.8 7 Inv 0 69 297 36.5 199 90.9 25.4 8 Inv 1 80 309 37.1 200 91.2 25.2 9 Inv 0 83 314 36.0 198 89.8 25.8 10 Com 12 564 245 36.1 193 90.1 25.8 11 Com 7 374 108 35.9 195 89.9 25.3 12 Com — 349 307 33.2 196 89.7 26.1 13 Inv — 108 293 35.5 200 90.4 25.4 14 Inv — 59 312 36.5 199 90.3 25.2 15 Inv — 65 269 36.3 199 90.9 25.6 16 Com — 363 132 36.6 201 91.1 25.0 (Com = comparative example, Inv = inventive example)

(38) Comparison of results for comparative example 1 (no crystallization additive C) with the results of inventive examples 2 to 9 (0.142% by weight of one of inventive additives C1 to C8) demonstrates the strong reduction of the number of visible surface defects after warm-humid storage by specific additives C. The different additives C1 to C8 based on organic acids, e.g. oxalic acid, citric acid, or phosphate compounds, e.g. disodium dihydrogen diphosphate, sodium hexametaphosphate, tetrasodium diphosphate, phosphoric acid, or combinations thereof are almost equally effective. The number of visible surface defects before warm-humid storage is much smaller and in most cases zero.

(39) Comparative example 10 (neutralized polyphosphate of medium chain-length, Calgon N®) demonstrates that polyphosphates with too long chains, i.e. chains having more than 25 phosphate units do not show a positive effect on number of visible surface defects after warm-humid storage. In fact, the number of defects is even higher than for the comparative example 1 which was carried out without additive.

(40) Comparative example 11 (addition of sodium hydrogen carbonate) demonstrates that hydrogen carbonate does not have a positive effect on surface quality after warm-humid storage.

(41) Furthermore, unnotched Izod impact strength is lower for the comparative examples 1 and 10 compared with the inventive examples 2 to 9.

(42) Furthermore, the examples to which a phosphate compound was added show an increased thermal stability of ABS powder (see results of Scorch test in table 1 and 2 above). This additional positive effect is observed already at low phosphate content, whereas high amounts do not give additional advantage. Interestingly, a better thermal stabilization of ABS/PC blend was found for all inventive examples (see thermal stability according to test method c) given in table 3 below). The thermal stability of ABS/PC blends is mainly based on reduced chain degradation at high temperature, and not on the oxidation of double bonds as in case of ABS powder.

1.7 Examples 16a and 16b

(43) All steps were carried out as in example 1 except that different amounts of additive C12 C12 mixture of disodium dihydrogen diphosphate, Na.sub.2H.sub.2P.sub.2O.sub.7 and tetrasodium diphosphate, Na.sub.4P.sub.2O.sub.7 (mass ratio 0.75:1)
are added during the dewatering step at the end of the centrifugation (step 1.4 workup). The crystallization additive C12 was dissolved in water and the resulting aqueous solution (0.06 g/mL C12 in water) was added at the end of the centrifugation to the wet powder. The additive solution applied to the dewatered graft copolymer remained on the polymer and the polymer was dried as described under step 1.4 (workup). The crystallization additive C12 was added in an amount of 0.3% by weight (example 2a) or 0.6% by weight (example 2b), based on the solid content of the additive C12 and regarding to the total solid content of the polymer.

(44) The resulting ABS copolymers were compounded as described in example 1.5 with the thermoplastic polymer A-I and tested regarding the surface properties (defects after warm and humid storage and the yellowness index YI as described under I. Test Methods). The content of Na, Mg, and P in the dried graft copolymer B was determined as described above. The results are given in Table 2a. The comparative sample 1 (without the inventive addition of additive C) is the same as in Table 2 above.

(45) TABLE-US-00003 TABLE 2a Test results for ABS polymer compositions, Ex. 1, Ex. 16a and Ex. 16b Defects after Amount warm-humid Na Mg P C12 storage YI content content content Test method m) e) o) o) o) Unit [% by number/ Ex. weight]* 150 cm.sup.2 ppm** ppm** ppm** 1 Com 0 386 25.2 165 960 <1 16a Inv 0.3 30 25.7 770 950 560 16b Inv 0.6 15 27.4 1400 930 1000 (Com = comparative example, Inv = inventive example) *calculated on solid content C12 and based on solid content of ABS **based on the dried graft copolymer B

III. Preparation of Polymer Blends ABS/PC

Example 17 (Comparative)

(46) The ABS copolymer obtained according to example 1 was compounded with polycarbonate P1 as further polymer component P, an thermoplastic polymer A-II and additives K, wherein the following polymers were used:

(47) Further Polymer Component P1:

(48) Linear polycarbonate based on bisphenol-A with weight average molar mass of 27500 (size exclusion chromatography in methylene chloride at 25° C.)

(49) Additional Thermoplastic Polymer A-II:

(50) Statistical copolymer from styrene and acrylonitrile with a ratio of polymerized styrene to acrylonitrile of 76.5:23.5 with a MVR (220° C./10 kg) of 30 mL/10 min. and produced by continuous radical solution polymerization

(51) 48.40 parts ABS copolymer from example 1 were compounded with 44.65 parts P1, as further polymer component P; 5.90 parts A-II, 0.75 parts pentaerythrityl tetrastearate, 0.15 parts of a blend of 20% octadecyl-3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate] and 80% tris (2,4-ditert-butylphenyl) phosphite, 0.2 parts octadecyl-3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate] and 0.1 parts citric acid to yield a thermoplastic polymer blend. The resulting material was tested and results are given in table 3.

Examples 18 to 20

(52) Polymer was compounded as in example 17 with exception of the ABS polymer which was taken from example 4, 5 and 7 instead of example 1. The resulting material was tested and results are given in table 3.

(53) TABLE-US-00004 TABLE 3 ABS/PC blend and test results Example 17 18 19 20 ABS copolymer Ex. 1 Ex. 4 Ex. 5 Ex. 7 Test Unit Com Inv Inv Inv Defects after warm-humid m) number/ 386 70 87 69 storage in corresponding 150 cm.sup.2 ABS (as in table 2) Defects after warm-humid m) number/ 57 13 15 16 storage 150 cm.sup.2 Notched Izod (RT) a) kJ/m.sup.2 45.7 46.1 45.4 46.3 Notched Izod (−30° C.) a) kJ/m.sup.2 30.2 41.2 40.9 41.2 MVR (260° C./5 kg) b) ml/10 10.9 9.8 9.4 9.9 min Thermal stability c) ml/10 59.6 42.6 41.8 34.1 min Hydrolytic stability d) ml/10 20.0 18.1 17.0 20.1 min Hardness g) 102.0 102.3 101.6 101.5 Gloss (20°) f) 88.8 88.3 88.4 88.8 YI e) 26.6 25.9 26.9 26.4 Vicat B/120 h) ° C. 110.5 110.4 109.6 110.0 (Com = comparative example, Inv = inventive example)

VI. Preparation of ASA Polymer Composition

Example 21

(54) 1. Preparation of Graft Base B1′ Latex

(55) A reaction vessel was charged with 90 parts of demineralized water, 0.5 parts of the sodium salt of a C.sub.12-to C.sub.18-paraffin sulfonic acid and 0.25 parts sodium bicarbonate. When the temperature in the reaction vessel reached 59° C., 0.2 parts of sodium persulfate, dissolved in 5 parts of demineralized water, were added. A mixture of 60 parts butyl acrylate and 1.5 part tricyclodecenylacrylate was added within a period of 210 min. Afterwards the reaction was continued for 60 min. Finally the polymer dispersion had a total solid content of 40% by weight and the latex particles had a particle diameter of 75 nm (average size D.sub.50).

(56) 2. Grafting to Form Graft Copolymer Latex B′ (ASA)

(57) An amount of 150 parts of the graft base latex B1′ was added to the reaction vessel together with 90 parts of demineralized water and 0.1 parts of sodium persulfate, dissolved in 5 parts of demineralized water. Within a period of 190 min a mixture of 30 parts of styrene and 10 parts of acrylonitrile was added at a temperature of 61° C., followed by a post polymerization time of 60 min at 65° C. A polymer dispersion with a total solid content of 35% by weight was obtained. The latex particles had a diameter 90 nm (average size D.sub.50).

(58) 3. Workup of Graft Copolymer Latex B′

(59) 0.1 parts of a MgSO.sub.4 solution (20% by weight) were mixed with 6.67 parts demineralized water. An amount of 20% of this solution was used as pre-charge and heated to 60° C. 1 part of a polymer latex B′ and the remaining diluted MgSO.sub.4 solution were added separately within 10 min, while the temperature was kept at 60° C. Then the resulting mixture was heated to 92° C. for 5 min. The resulting slurry was transferred to a centrifuge, having a diameter of 400 mm, and centrifuged at 1500-2000 rpm for 60 s and washed during this process with 0.3 parts demineralized water.

(60) The resulting material was dried in an oven at 70° C. for 2 days, wherein the dried ASA-copolymer B′ powder was obtained.

(61) 4. Compounding of Graft Polymer B′ with Thermoplastic Polymer A-III to Form Thermoplastic Molding Compositions

(62) The dried ASA-copolymer B′ powder was compounded using a twin screw extruder with the thermoplastic polymer (SAN-Copolymers) A-III: Component A-III (thermoplastic polymer A): Statistical copolymer from styrene and acrylonitrile with a ratio of polymerized styrene to acrylonitrile of 67:33 with a MVR (220° C./10 kg) of 16 mL/10 min and produced by continuous radical solution polymerization.

(63) The composition of the blend was 60% by weight of A-III and 40% by weight ASA-copolymer B″.

(64) The resulting material was tested against the surface quality and the results are given in Table 4 (comparative example 21).

Example 22

(65) 1. Preparation of Graft Base B1″ Latex

(66) The reaction vessel was charged with 70 parts of demineralized water, 0.5 parts of latex B1′ (see Example 21) and 0.25 parts of sodium bicarbonate. After heating the reaction vessel to 60° C., 0.15 parts of sodium persulfate, dissolved in 5 parts demineralized water, were added to the reaction mixture. A mixture of 60 parts butyl acrylate and 1 part tricyclodecenylacrylate was added within a period of 210 min. In parallel to the first feed a solution of 0.5 parts of the sodium salt of a C.sub.12-to C.sub.18-paraffin sulfonic acid in 15 parts demineralized water was also added over a period of 210 min. After 200 min, from starting the feed, the temperature was ramped to 65° C. Afterwards the reaction was continued for 60 min at 65° C. Finally the polymer dispersion has a total solid content of 40% by weight and the latex particles had a particle diameter of 450 nm (average size D.sub.50).

(67) 2. Grafting to Form Graft Copolymer Latex B″ (ASA)

(68) An amount of 155 parts of the graft base B1″ was added to the reaction vessel together with 90 parts of demineralized water, 0.1 parts of the sodium salt of a C.sub.12-to C.sub.18-paraffin sulfonic acid and 0.15 parts of sodium persulfate, dissolved in 5 parts of demineralized water. The reaction mixture was heated to 61° C. Within a period of 60 min 15 parts of styrene were added at a temperature of 61° C., followed by a post polymerization time of 90 min, where the temperature was increased from 61 to 65° C. Then a mixture of 20 parts of styrene and 5 parts of acrylonitrile was added to the reaction over a period of 150 min. The reaction was continued at 65° C. for another 60 min. A polymer dispersion with a total solid content of 35% by weight was obtained. The latex particles had a diameter of 500 nm (average size D.sub.50).

(69) 3. Workup of Graft Copolymer Latex B″

(70) 0.1 parts of a MgSO.sub.4 solution (20% by weight) was mixed with 6.67 parts demineralized water. An amount of 20% of this solution was used as pre-charge and heated to 88° C. 1 part of a polymer latex B″ and the remaining diluted MgSO4 solution were added separately within 10 min, while the temperature was kept at 88° C. Then the resulting mixture was heated to 99° C. for 5 min. The resulting slurry was transferred to a centrifuge, having a diameter of 400 mm, and centrifuged at 1500-2000 rpm for 60 s and washed with 0.35 parts of demineralized water.

(71) The resulting material was dried in an oven at 70° C. for 2 days, wherein the dried ASA-copolymer B″ powder was obtained.

(72) 4. Compounding of Graft Polymer B″ with Thermoplastic Polymer A-III to Form Thermoplastic Molding Compositions

(73) The dried ASA-copolymer B″ powder was compounded using a twin screw extruder with the thermoplastic polymer (SAN-Copolymer) A-Ill. The composition of the blend was 60% by weight of A-III and 40% by weight ASA-copolymer B″.

(74) The resulting material was tested against the surface quality and the results are given in Table 4 (comparative example 22).

Examples 23a-23c

(75) All steps of examples 23 were carried out as described in example 21 except the addition of different amounts of the crystallization additive C12 mixture of disodium dihydrogen diphosphate, Na.sub.2H.sub.2P.sub.2O.sub.7 and tetrasodium diphosphate, Na.sub.4P.sub.2O.sub.7 (mass ratio 0.75:1)

(76) The additive 012 were added during the dewatering step at the end of the centrifugation (steps 3 workup in example 21). The additive C12 was dissolved in demineralized water (0.06 g/mL 012 in water) and the aqueous solution was added at the end of the centrifugation to the wet powder. The additive solution applied to the dewatered graft copolymer remained on the polymer and the polymer was dried as described under step 1.4 (workup). The additive C12 was added in an amount of 0.4% by weight (23a), 0.8% by weight (23b) or 1.2% by weight (23c) based on solid content of 012 and regarding the total solid content of the graft copolymer B.

(77) The resulting materials were tested in view of the defects after warm and humid storage and the yellowness index YI. The content of Na, Mg, and P in the dried graft copolymer B was determined as described above. The results are given in Table 4.

(78) TABLE-US-00005 TABLE 4 Test results for ASA polymer compositions, examples 21, 22 and 23a-23c Defects after warm- Amount humid Na Mg P C12 storage YI content content content Test method m) e) o) o) o) Unit [% by number/ Ex. weight]* 150 cm.sup.2 ppm** ppm** Ppm** 21 Com 0 240 22.5 150 1000 <1 22 Com 0 280 23.2 150 1000 <1 23a Inv 0.4 75 23.4 780 900 660 23b Inv 0.8 15 22.8 1400 990 1200 23c Inv 1.2 3 26.6 2100 1000 2100 (Com = comparative example, Inv = inventive example) *calculated on solid content of C12 and based on solid content of ABS **based on the dried graft copolymer B