IMPACT-RESISTANT MOLDING MATERIAL HAVING AN IMPROVED CHARACTERISTICS PROFILE

Abstract

The invention relates to an impact-modified moulding composition, especially impact-modified PMMA, having an improved profile of properties, especially also at elevated temperatures, to moulded articles obtainable therefrom and to the use of the moulding composition and the moulded article.

Claims

1. A moulding composition comprising, based in each case on the total weight thereof: I. 10.0% to ≦35.0% by weight, of at least one core-shell-shell particle produced or producible by a process in which a) water and emulsifier are initially charged, b) 20.0 to 45.0 parts by weight of a first composition comprising: A) 50.0 to 99.9 parts by weight, of alkyl methacrylates having 1 to 20 carbon atoms in the alkyl radical, B) 0.0 to 40.0 parts by weight, of alkyl acrylates having 1 to 20 carbon atoms in the alkyl radical, C) 0.1 to 10.0 parts by weight of crosslinking monomers and D) 0.0 to 8.0 parts by weight of styrenic monomers of the general formula (I) ##STR00006## where the R.sup.1 to R.sup.5 radicals each independently denote hydrogen, a halogen, a C.sub.1-6-alkyl group or a C.sub.2-6-alkenyl group and the R.sup.6 radical is hydrogen or an alkyl group having 1 to 6 carbon atoms, are added and polymerized up to a conversion of at least 85.0% by weight, based on the total weight of components A), B), C) and D), c) 35.0 to 55.0 parts by weight of a second composition comprising: E) 80.0 to 100.0 parts by weight of (meth)acrylates, F) 0.05 to 5.0 parts by weight of crosslinking monomers and G) 0.0 to 25.0 parts by weight of styrenic monomers of the general formula (I) are added and polymerized up to a conversion of at least 85.0% by weight, based on the total weight of components E), F) and G), d) 10.0 to 30.0 parts by weight of a third composition comprising: H) 50.0 to 100.0 parts by weight of alkyl methacrylates having 1 to 20 carbon atoms in the alkyl radical, I) 0.0 to 40.0 parts by weight of alkyl acrylates having 1 to 20 carbon atoms in the alkyl radical and J) 0.0 to 10.0 parts by weight of styrenic monomers of the general formula (I) are added and polymerized up to a conversion of at least 85.0% by weight, based on the total weight of components H), I) and J), where the stated proportions by weight of compositions b), c) and d) add up to 100.0 parts by weight, where the relative proportions of all substances A) to J) are chosen so as to obtain core-shell-shell particles having a total radius, measured by the Coulter method, in the range of >125.0 nm and <180 nm, preferably in the range of >128.0 nm and <160 nm, more preferably in the range of >135.0 nm and <150 nm, and where each polymerization in the process according to I. is conducted at a temperature in the range of >60 to <95° C.; II. 1.0% to 90.0% by weight, of at least one (meth)acrylic polymer, III. 0.0% to 45% by weight, of styrene-acrylonitrile copolymers, and IV. 0.0% to 10.0% by weight of further additives, where the percentages by weight of components I) to IV) add up to 100.0% by weight and where II., or the mixture of II., III. and/or IV., is chosen such that it has a refractive index which, when measured according to ISO 489 (Method A), differs by not more than 0.01 unit from the refractive index of I.

2. The moulding composition according to claim 1, wherein the second composition of the core-shell-shell particle according to I. comprises, as G), more than 8.0 and up to 19.95 parts by weight, of styrenic monomers of the general formula (I).

3. The moulding composition according to claim 1, wherein the second composition of the core-shell-shell particle according to I. has a Tg of <−10° C.

4. The moulding composition according to claim 1, wherein, in the process for obtaining I., the polymerization in steps b) to d) is initiated using a peroxodisulphate, preferably using ammonium peroxodisulphate and/or alkali metal peroxodisulphate.

5. The moulding composition according to claim 1, wherein the moulding composition has a. a Charpy impact resistance to ISO 179 of at least 40.0 kJ/m.sup.2 at 23° C. and b. a haze to ASTM D 1003 (1997) of ≦3% at 23° C. and a haze to ASTM D 1003 (1997) of ≦21% at 80° C., and c. a Vicat softening temperature to DIN ISO 306 (August 1994) of ≧98° C. and d. a melt volume flow rate MVR to ISO 1133 (230° C.; 3.8 kg) of ≧1.5 cm.sup.3/10 min.

6. The moulding composition according to claim 1, wherein the at least one (meth)acrylic polymer according to II. comprises, based in each case on the total weight thereof: a) 52.0% to 100.0% by weight of repeat alkyl methacrylate units having 1 to 20 carbon atoms in the alkyl radical, b) 0.0% to 40.0% by weight of repeat alkyl acrylate units having 1 to 20 carbon atoms in the alkyl radical and c) 0.0% to 8.0% by weight of repeat styrenic units of the general formula (I), where the percentages by weight add up to 100.0% by weight.

7. The moulding composition according to claim 1, wherein the at least one (meth)acrylic polymer according to II., based in each case on the total weight thereof, contains ≦8% by weight of repeat alkyl acrylate units having 1 to 20 carbon atoms in the alkyl radical.

8. The moulding composition according to claim 1, wherein the moulding composition comprises styrene-acrylonitrile copolymers according to III., the styrene-acrylonitrile copolymers having been obtained by polymerizing a mixture consisting of 70% to 92% by weight of styrene, 8% to 30% by weight of acrylonitrile and 0% to 22% by weight of further comonomers, based in each case on the total weight of the mixture.

9. The moulding composition according to claim 1, wherein the moulding composition, based on the total weight thereof, comprises 0.1% to 10.0% by weight of a further polymer as additive according to IV., having a weight-average molecular weight at least 10% higher compared to the at least one (meth)acrylic polymer according to II.

10. A moulding article obtainable from a moulding composition according to claim 1.

11. The moulding article according to claim 10, wherein the moulded article has a. a Charpy impact resistance to ISO 179 of at least 40.0 kJ/m.sup.2 at 23° C. and b. a haze to ASTM D 1003 (1997) of ≦3% at 23° C., and a haze to ASTM D 1003 (1997) of ≦21% at 80° C., and c. a Vicat softening temperature to DIN ISO 306 (August 1994) of ≧98° C., and d. a melt volume flow rate MVR to ISO 1133 (230° C.; 3.8 kg) of ≧1.5 cm.sup.3/10 min, preferably of ≧2.0 cm.sup.3/10 min, further preferably of ≧2.5 cm.sup.3/10 min.

12. The article according to claim 10 which is selected from the group consisting of large and/or thin-walled impact-resistant components; glass panes/glazing displays for communication devices; tablet PCs; TV devices; kitchen appliances and other electronic devices; building interior lighting and exterior lighting.

13. The article according to claim 10 which is selected from the group consisting of an impact-modified and large and/or thin-walled injection-moulded component; glass panes/glazing; coloured glass covers for automobile lights; a display for a communication device; a TV device; a tablet PC; a kitchen appliance another electronic device; building interior lighting and exterior lighting.

Description

EXAMPLES

Core-Shell-Shell Particles I. (CE1-3 and IE1-3)

Production of the Seed Latex

[0171] A seed latex was produced by means of emulsion polymerization of a monomer composition containing 98% by weight of ethyl acrylate and 2% by weight of allyl methacrylate. These particles having a diameter of about 20 nm were present in a concentration of about 10% by weight in water.

Production of the Core-Shell-Shell Particles

[0172] All the core-shell-shell particles described hereinafter were produced by means of emulsion polymerization according to Preparation Method A below (Inventive Examples IE1, IE2, IE3 and Comparative Example CE1) or Preparation Method B below (Comparative Examples CE2 and CE3). This was done using the emulsions (i) to (iii) specified in Table 1.

Inventive Examples IE1, IE2, IE3 and Comparative Example CE1

Production of the Core-Shell-Shell Particles by Preparation Method A

[0173] At 83° C. (internal tank temperature), 1.711 kg of water were initially charged in a stirred polymerization tank. 1.37 g of sodium carbonate and seed latex were added. Subsequently, emulsion (i) was metered in over the course of 1 h. 10 min after the feeding of emulsion (i) had ended, emulsion (ii) was metered in over a period of about 2 h. Subsequently, about 60 min after the feeding of emulsion (ii) had ended, emulsion (iii) was metered in over a period of about 1 h. 30 min after the feeding of emulsion (iii) had ended, the mixture was cooled to 30° C.

[0174] To separate the core-shell-shell particles, the dispersion was frozen at −20° C. for 2 days, then thawed again, and the coagulated dispersion was separated by means of a filter fabric. The solids were dried at 50° C. in a drying cabinet (for about 3 days). The particle size of the core-shell-shell particles (see Table 2) was determined by means of a Coulter Nano-Sizer© N5, by analysing the particles in dispersion.

Comparative Examples CE2 and CE3

Production of the Core-Shell-Shell Particles by Preparation Method B

[0175] At 52° C. (internal tank temperature), 1.711 kg of water were initially charged in a stirred polymerization tank, and 0.10 g of acetic acid, 0.0034 g of iron(II) sulphate, 0.69 g of sodium disulphite and the seed latex were added. Subsequently, emulsion (i) was metered in over the course of 1.5 h. 10 min after the feeding of emulsion (i) had ended, 7.46 g of sodium disulphite dissolved in 100 g of water were added and emulsion (ii) was metered in over a period of about 2.5 h. Subsequently, about 30 min after the feeding of emulsion (ii) had ended, 0.62 g of sodium disulphite dissolved in 50 g of water were added and emulsion (iii) was metered in over a period of about 1.5 h. 30 min after the feeding of emulsion (iii) had ended, the mixture was cooled to 30° C.

[0176] To separate the core-shell-shell particles, the dispersion was frozen at −20° C. for 2 days, then thawed again, and the coagulated dispersion was separated by means of a filter fabric. The solids were dried at 50° C. in a drying cabinet (for about 3 days). The particle size of the core-shell-shell particles (see Table 2) was determined by means of a Coulter Nano-Sizer© N5, by analysing the particles in dispersion.

TABLE-US-00001 TABLE 1 Summary of the individual emulsions (all figures in [g]) IE1 IE2 IE3 CE1 CE2 CE3 Seed latex 15.00 12.00 5.00 28.00 5.00 13.00 Emulsion (i) Water 878.70 878.70 878.70 878.70 732.69 732.69 Sodium 0.70 0.70 0.70 0.70 0.51 0.51 persulphate Aerosol OT75 5.60 5.60 5.60 5.60 4.67 4.67 Methyl 1071.62 1071.62 1071.62 1071.62 703.47 703.47 methacrylate Ethyl acrylate 44.74 44.74 44.74 44.74 29.40 29.40 Allyl 2.24 2.24 2.24 2.24 2.21 2.21 methacrylate Emulsion (ii) Water 606.90 606.90 606.90 606.90 628.65 628.65 Sodium 1.58 1.58 1.58 1.58 1.44 1.44 persulphate Aerosol OT75 7.20 7.20 7.20 7.20 7.46 7.46 Butyl acrylate 1160.63 1160.63 1160.63 1160.63 1219.72 1219.72 Styrene 256.00 256.00 256.00 256.00 262.87 262.87 Allyl 21.57 21.57 21.57 21.57 19.53 19.53 methacrylate Emulsion (iii) Water 404.30 404.30 404.30 404.30 381.56 381.56 Sodium 0.70 0.70 0.70 0.70 0.44 0.44 persulphate Aerosol OT75 1.08 1.08 1.08 1.08 1.34 1.34 Methyl 614.27 614.27 614.27 614.27 920.45 920.45 methacrylate Ethyl acrylate 24.93 24.93 24.93 24.93 38.35 38.35

Blending of the Moulding Compositions

Inventive Examples 4, 5, 7, 8 and 10 and Comparative Examples 1, 2, 3, 6, 9, 11, 12 and 13

[0177] A base moulding composition based on polymethylmethacrylate, PLEXIGLAS® 7N or PLEXIGLAS® 8N (from Evonik Industries AG, Darmstadt), was blended with one of the particular core-shell-shell particles IE1-IE3 or CE1-CE3 by means of an extruder in different ratios in the melt, the base moulding composition used corresponding in each case to the (meth)acrylic polymer II.

[0178] The constituents of each mixture were mixed vigorously by means of a tumble mixer for 3 minutes and then introduced into the funnel of a Stork single-screw extruder having screw diameter 35 mm. The components were extruded at a melt temperature of 235° C., and extrudates were drawn off from the extruder die, cooled in a water bath and chopped to give pellets of uniform grain size.

[0179] Specimens according to ISO 294 were injection-moulded using the pellets obtained in a Battenfeld BA 500 injection moulding machine. To determine the impact resistance, ISO specimens of dimensions 80 mm×10 mm×4 mm were injection-moulded at 250° C. To determine optical properties, plaques of dimensions 65 mm×40 mm×3 mm were injection-moulded at 250° C. (above melting temperature).

[0180] The compositions of the individual examples and comparative examples are documented in Table 2.

Testing of the Moulding Compositions and Specimens Produced Therefrom

[0181] The moulding compositions, i.e. the corresponding test specimens, were tested by the following test methods: [0182] Vicat softening temperature (B50, 16 h/80° C.): DIN ISO 306 (August 1994) [0183] Charpy impact resistance: ISO 179 (1993) [0184] Modulus of elasticity: ISO 527-2 [0185] Transmission (D) 65/10°: DIN 5033/5036 [0186] Haze (Hazemeter BYK Gardner Hazegard-plus): ASTM D 1003 (1997) [0187] MVR (230° C., 3.8 kg): ISO 1133

[0188] The results of the tests are shown in Table 2. The advantages of the blends according to the invention over the conventionally impact-modified moulding compositions of the comparative examples are clearly apparent. The blends according to the invention have, for example, low haze values even at relatively high temperature (80° C.), determined to ASTM D1003. The moulding compositions according to the invention also give a high impact resistance compared to the comparative examples, without any deterioration in other important properties of the moulding compositions, especially the Vicat softening temperature, the melt volume flow rate and the modulus of elasticity. Some of the values obtained in this regard are even improved over the known moulding compositions.

TABLE-US-00002 TABLE 2 Test results for the impact-modified moulding compositions (the moulding composition utilized except in IE4 was Plexiglas ® 7N; the moulding composition utilized in IE4 was Plexiglas ® 8N) Comp. Comp. Inv. Inv. Comp. Inv. Inv. Comp. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Inv. Ex. 10 Ex. 11 Ex. 12 Ex. 13 Core-shell- CE1 CE1 IE1 IE1 IE1 IE2 IE2 IE2 IE3 IE3 CE2 CE2 CE3 shell particles Proportion of 38% 20% 38% 33% 20% 38% 27% 20% 38% 20% 38% 20% 20% CSS particles in moulding composition [% by wt.] Particle radius 101 101 129 129 129 145 145 145 165 165 165 165 134 [nm] Moulding 7N 7N 7N 8N 7N 7N 7N 7N 7N 7N 7N 7N 7N composition Vicat [° C.] 97.9 103.1 96.5 102 102.9 96.2 100.9 102.4 97 101.8 99.6 100.6 102.5 Charpy IR at 91.5 28.4 114.5 103.9 63.2 123.6 105.3 85.3 130.1 90.9 95.9 57.4 34.8 23° C. [kJ/m.sup.2] Light 91.5 90.1 91.4 90.5 90.9 91.5 90.8 91.5 89.7 91.5 91 90.8 91.2 transmission [%] Haze at 23° C. 0.68 1.6 1 0.9 0.6 1.1 1 0.9 2.2 1.2 1.9 1.5 0.69 [%] Haze at 80° C. 3.71 6.2 10.2 9.6 7.8 12.5 14.3 11.7 22.1 17.6 22.4 19.2 8.7 [%] Modulus of 1943 2664 1898 2071 2560 1610 2257 2610 1819 2412 1828 2384 2616 elasticity [MPa] MVR 1.59 3.28 1.34 1.57 3.21 1.4 2.95 3.58 1.67 3.39 1.83 3.47 3.24 [cm.sup.3/10 min]