Plastics moulding compositions, and mouldings and production processes

1. A plastics molding composition, comprising:

A) a poly(meth)acrylate and

B) an impact-modified poly(meth)acrylate,

wherein a die swell of the plastics molding composition is at least 15%, measured at 5 MPa and 220° C. to DIN 54811 (1984),

a melt flow rate of the poly(meth)acrylate A) is at least 10 mL per 10 minutes, measured to ISO 1133 at 230° C. with a load of 3.8 kg,

a melt flow rate of the impact-modified poly(meth)acrylate B) is from 0.1 to 5 mL per 10 minutes, measured to ISO 1133 at 230° C. with a load of 10 kg, and

a melt flow rate of the plastics molding composition is from 1 to 7 mL per 10 minutes, measured to ISO 1133 at 230° C. with a load of 3.8 kg.

2. The composition of claim 1 , wherein the impact-modified poly(meth)acrylate B) is obtained in a process comprising polymerizing in a suspension polymerization.

3. The composition of claim 1 , wherein the impact-modified poly(meth)acrylate B) is obtained in a process comprising:

polymerizing a hard phase monomer to produce a hard phase comprising at least 70% by weight of methyl methacrylate, with a glass transition temperature Tg >25° C., then,

adding a tough phase monomer, a polymer of which has a glass transition temperature Tg of <25° C., and

polymerizing the tough phase monomer to produce the tough phase

wherein polymerizing to produce the hard phase is in the presence of:

an oil-soluble free-radical initiator and

an organic sulfur chain transfer agent comprising at least two thiol groups per molecule.

4. The composition of claim 3 , wherein a ratio by weight of the hard phase monomer to the tough phase monomer is from 1:0.15 to 1:3.

5. The composition of claim 3 , wherein a proportion of the oil-soluble free-radical initiators initiator is from 0.01 to 5% by weight, based on the weight of the hard phase monomer.

6. The composition of claim 1 , wherein a proportion of organic sulfur chain transfer agent is from 0.05 to 5% by weight, based on the weight of the hard phase monomer.

7. The composition of claim 1 , wherein the melt flow rate of the poly(meth)acrylate A) is at least 15 mL per 10 minutes, measured to ISO 1133 at 230° C. with a load of 3.8 kg.

8. The composition of claim 1 , wherein a ratio by weight of the poly(meth)acrylate A) to impact-modified poly(meth)acrylate B) is from 10:1 to 1:10.

9. The composition of claim 1 , wherein the polymers of the plastics molding composition have a molecular-weight distribution with at least two maxima, measured by means of GPC.

10. The composition of claim 1 , wherein the plastics molding composition comprises:

from 10 to 50% by weight of the poly(meth)acrylate A) and

from 40 to 90% by weight of the impact-modified poly(meth)acrylate B).

11. The composition of claim 10 , wherein the plastics molding composition comprises:

from 10 to 50% by weight of the poly(meth)acrylate A),

from 40 to 90% by weight of the impact-modified poly(meth)acrylate B), and

from 0 to 30% by weight of additives.

12. The composition of claim 1 , wherein the melt flow rate of the plastics molding composition is from 1 to 6 mL per 10 minutes, measured to ISO 1133 at 230° C. with a load of 3.8 kg.

13. The composition of claim 1 , wherein an impact resistance of the plastics molding composition measured at 23° C. to ISO 179 is at least 60 kJ/m 2 .

14. A molding, comprising the plastics molding composition of claim 1 .

15. The molding of claim 14 , wherein a thickness of the molding is from 0.5 to 1.5 mm.

16. The molding of claim 14 , wherein a haze of the molding, for a thickness of 1 mm, is at most 1% measured to ASTM D 1003 at 23° C.

17. The composition of claim 1 , wherein the poly(meth)acrylate A) is obtained by polymerizing a mixture, the mixture comprising at least 20% by weight of methyl methacrylate, based on a total weight of monomer in the mixture.