Thermostable microporous polymethacrylimide foams

1. A process for producing a foamable crosslinked polymer, comprising:

polymerizing a mixture comprising

(A) 30-70 parts by weight of methacrylic acid,

 30-60 parts by weight of methacrylonitrile,

 0-30 parts by weight of other monomers having vinyl unsaturation,

(B) 0.01-4.99 parts by weight of tert-butyl methacrylate,

(C) 0.01-10 parts by weight of a blowing agent,

(D) 0.01-10 parts by weight of a crosslinking agent,

(E) 0.01 to 2 parts by weight of a polymerization initiator, and

(F) 0 to 20 parts by weight of a conventional additive, in bulk to give a polymer in the form of a sheet;

wherein said sheet is optionally subjected to the following treatment:

heat-conditioning and then foaming at temperatures of from 150 to 250° C.;

foaming to obtain a foam having extremely fine and uniform pore structure having a pore size of 10-35 μm.

2. A poly(meth)acrylimide foam which is obtained via foaming of a foamable polymer obtained according to the process of claim 1 .

3. A laminated material comprising a layer of a poly(meth)acrylimide foam according to claim 2 .

4. A vehicle, comprising:

the poly(meth)acrylimide foam according to claim 2 ;

wherein said vehicle is selected from the group consisting of a motor vehicle, a rail vehicle, a watercraft, an aircraft or a spacecraft.

5. A machine component comprising the poly(meth)acrylimide foam according to claim 2 .

6. An antenna comprising the poly(meth)acrylimide foam according to claim 2 .

7. An X-ray table comprising the poly(meth)acrylimide foam according to claim 2 .

8. A loudspeaker comprising the poly(meth)acrylimide foam according to claim 2 .

9. A pipe comprising the poly(meth)acrylimide foam according to claim 2 .

10. The poly(meth)acrylimide foam according to claim 2 , wherein said foamable polymer has a molar mass of >600 kDa.

11. The poly(meth)acrylimide foam according to claim 2 , wherein said foam is a fine-pore foam having a density in the range from 30 to 300 kg/m 3 .

12. The process for producing the foamable crosslinked polymer according to claim 1 , wherein said sheet is heat-conditioned and foamed.

13. The process for producing the foamable crosslinked polymer according to claim 1 , wherein said foamable polymer has a molar mass of >600 kDa.

14. The process for producing the foamable crosslinked polymer according to claim 1 , wherein said foam is a fine-pore foam having a density in the range from 30 to 300 kg/m 3 .

15. The process for producing the foamable crosslinked polymer according to claim 1 , wherein said mixture comprises (B) 1 to 2 parts by weight of tert-butyl methacrylate.

16. A foamable crosslinked polymer, comprising in polymerized form:

(A) 30-70 parts by weight of methacrylic acid,

 30-60 parts by weight of methacrylonitrile,

 0-30 parts by weight of other monomers having vinyl unsaturation,

(B) 0.01-4.99 parts by weight of tert-butyl methacrylate,

(C) 0.01-10 parts by weight of a blowing agent,

(D) 0.01-10 parts by weight of a crosslinking agent,

(E) 0.01 to 2 parts by weight of a polymerization initiator, and

(F) 0 to 20 parts by weight of a conventional additive; and

wherein said foamable crosslinked polymer is capable of being foaming to obtain a foam having extremely fine and uniform pore structure having a pore size of 10-35 μm.

17. The foamable crosslinked polymer according to claim 16 , having a molar mass of >600 kDa.

18. The foamable crosslinked polymer according to claim 16 , comprising (B) 1 to 2 parts by weight of tert-butyl methacrylate.

19. A process for producing a foamable crosslinked polymer, comprising:

polymerizing a mixture comprising

(A) 30-70 parts by weight of methacrylic acid,

 30-60 parts by weight of methacrylonitrile,

 0-30 parts by weight of other monomers having vinyl unsaturation,

(B) 0.01-4.99 parts by weight of tert-butyl methacrylate,

(C) 0.01-10 parts by weight of a blowing agent,

(D) 0.01-10 parts by weight of a crosslinking agent,

(E) 0.01 to 2 parts by weight of a polymerization initiator, and

(F) 0 to 20 parts by weight of a conventional additive, in bulk to give a polymer in the form of a sheet;

wherein said sheet is subjected to the following treatment:

heat-conditioning and then foaming at temperatures of from 150 to 250° C. to obtain a foam having extremely fine and uniform pore structure having a pore size of 10-35 μm.

20. The process for producing the foamable crosslinked polymer according to claim 19 , wherein said mixture comprises (B) 1 to 2 parts by weight of tert-butyl methacrylate.

21. A foamable crosslinked polymer, comprising in polymerized form:

(A) 30-70 parts by weight of methacrylic acid,

 30-60 parts by weight of methacrylonitrile,

 0-30 parts by weight of other monomers having vinyl unsaturation,

(B) 0.01-4.99 parts by weight of tert-butyl methacrylate,

(C) 0.01-10 parts by weight of a blowing agent,

(D) 0.01-10 parts by weight of a crosslinking agent,

(E) 0.01 to 2 parts by weight of a polymerization initiator, and

(F) 0 to 20 parts by weight of a conventional additive;

wherein when said polymer is subjected to heat-conditioning and then foaming at temperatures of from 150 to 250° C., a foam having extremely fine and uniform pore structure having a pore size of 10-35 μm is obtained.

22. The foamable crosslinked polymer according to claim 21 , comprising (B) 1 to 2 parts by weight of tert-butyl methacrylate.