Maleimide copolymer and a process for producing the same

Claim 2

A maleimide copolymer which consists essentially of greater than 28% by weight and less than or equal to 65% by weight of a maleimide monomer unit (hereinafter referred to as an (a) monomer unit), greater than or equal to 16% by weight and less than 72% by weight of at least one monomer unit selected from the group consisting of aromatic vinyl compound monomer units and methacrylate monomer units (hereinafter referred to as a (b) monomer unit), 0-25% by weight of another vinyl compound monomer unit (hereinafter referred to as a (c) monomer unit) and which contains 0.1% by weight or less of the residual maleimide monomer and 0.5% by weight or less of volatile components other than the maleimide monomer and which has a ratio (Mw/Mn) of a weight average molecular weight Mw to a number average molecular weight Mn of 3 or less, a yellowness index of 30 or less and an intrinsic viscosity of from 0.3 to 1.5.

Claim 3

A maleimide copolymer according to Claim 1, wherein the monomer of the maleimide monomer unit is represented by the formula (I): where R represents a hydrogen atom, an alkyl group having 1-4 carbon atoms, a cyclohexyl group, an aryl group or a substituted aryl group.

Claim 4

A maleimide copolymer according to Claim 2, wherein the monomer of the maleimide monomer unit is N-­phenylmaleimide.

Claim 5

A maleimide copolymer according to Claim 2, wherein the monomer of the maleimide monomer unit is N-­cyclohexylmaleimide.

Claim 6

A maleimide copolymer according to Claim 1, wherein the monomer of the aromatic vinyl compound monomer unit is styrene or α-methylstyrene.

Claim 7

A maleimide copolymer according to Claim 1, wherein the monomer of the methacrylate monomer unit is methyl methacrylate.

Claim 8

A maleimide copolymer according to Claim 1, wherein the monomer of the another vinyl compound monomer unit is vinyl cyanide monomer.

Claim 9

A maleimide copolymer according to Claim 1, wherein the monomer of the another vinyl compound monomer unit is acrylonitrile.

Claim 10

A maleimide copolymer according to Claim 7, wherein the proportion by weight of the (a) monomer unit, the (b) monomer unit and the (c) monomer unit lies in a region encompassed with a quadrilateral having the vertex A where (a):(b):(c) = 28:64:8, the vertex B where (a):(b):(c) = 65:16:19, the vertex C where (a):(b):(c) = 28:72:0 and the vertex D where (a):(b):(c): = 65:35:0 in a triangular coordinate.

Claim 11

A maleimide copolymer according to Claim 8, wherein the proportion by weight of the (a) monomer unit, the (b) monomer unit and the (c) monomer unit lies in a region encompassed with a quadrilateral having the vertex A where (a):(b):(c): = 28:64:8, the vertex B where (a):(b):(c) = 65:16:19, the vertex C where (a):(b):(c) = 28:72:0 and the vertex D where (a):(b):(c) = 65:35:0 in a triangular coordinate.

Claim 12

A maleimide copolymer according to Claim 1, wherein the content of the residual maleimide monomer is 0.05% by weight of less and the content of the volatile components other than the maleimide monomer is 0.4% by weight of less.

Claim 13

A maleimide copolymer according to Claim 1, wherein the yellowish index is 25 or less.

Claim 14

The process for producing a maleimide copolymer which contains 0.1% by weight or less of the residual maleimide monomer and 0.5% by weight or less of volatile components other than the maleimide monomer and which has a ratio (Mw/Mn) of the weight average molecular weight Mw to a number average molecular weight Mn of 3 or less, a yellowish index of 30 or less and an intrinsic viscosity of from 0.3 to 1.5, comprising dropping continuously a maleimide monomer, at least one monomer selected from the group consisting of aromatic vinyl compound monomers and methacrylate monomers and, if necessary, another vinyl compound monomer, and an organic solvent in a ratio by weight of these monomers to the organic solvent between 3:2 - 9:1 and a polymerization initiator, if necessary, to a stirred tank reactor thereby continuing a copolymerization reaction, and taking out polymerization products containing unreacted monomers and the organic solvent continuously from the stirred tank reactor so as to maintain a constant composition of the monomers, a constant concentration of the polymerization products and a constant concentration of the polymerization initiator added if necessary thereby maintaining a continuous polymerization in a stationary state and thereafter, if necessary, polymerizing the unreacted maleimide monomer in the second polymerization reactor and transferring the obtained polymerization products to a devolatilizer and removing the unreacted monomers and the organic solvent at a reduced pressure, in the production of a maleimide copolymer which consists essentially of greater than 28% by weight and less than or equal to 65% by weight of a maleimide monomer unit, greater than or equal to 16% by weight and less than 72% by weight of at least one monomer unit selected from the group consisting of aromatic vinyl compound monomer units and methacrylate monomer units, 0 - 25% by weight of another vinyl compound monomer unit.

Claim 15

The process for producing a maleimide copolymer which contains 0.1% by weight or less of the residual maleimide monomer and 0.5% by weight or less of volatile components other than the maleimide monomer and which has a ratio (Mw/Mn) of the weight average molecular weight Mw to a number average molecular weight Mn of 3 or less, a yellowish index of 30 or less and an intrinsic viscosity of from 0.3 to 1.5, comprising dropping continuously a maleimide monomer, at least one monomer selected from the group consisting of aromatic vinyl compound monomers and methacrylate monomers and, if necessary, another vinyl compound monomer, and an organic solvent in a ratio by weight of these monomers to the organic solvent between 3:2 - 9:1 and a polymerization initiator, if necessary, to a stirred tank reactor thereby continuing a copolymerization reaction, and taking out polymerization products containing unreacted monomers and the organic solvent continuously from the stirred tank reactor so as to maintain a constant composition of the monomers, a constant concentration of the polymerization products and a constant concentration of the polymerization initiator added if necessary thereby maintaining a continuous polymerization in a stationary state and thereafter, if necessary, polymerizing the unreacted maleimide monomer in the second polymerization reactor and transferring the obtained polymerization products to a devolatilizer and removing the unreacted monomers and the organic solvent at a reduced pressure, in the production of a maleimide copolymer which consists essentially of greater than 28% by weight and less than or equal to 65% by weight of a maleimide monomer unit, greater than or equal to 16% by weight and less than 72% by weight of at least one monomer unit selected from the group consisting of aromatic vinyl compound monomer units and methacrylate monomer units, 0 - 25% by weight of another vinyl compound monomer unit.

Claim 16

A process for producing a maleimide copolymer according to Claim 13, wherein the maleimide monomer is represented by the formula (I): where R represents a hydrogen atom, an alkyl group having 1-4 carbon atoms, a cyclohexyl group, an aryl group or a substituted aryl group.

Claim 17

A process for producing a maleimide copolymer according to Claim 14, wherein the maleimide monomer is N-phenylmaleimide.

Claim 18

A process for producing a maleimide copolymer according to Claim 14, wherein the maleimide monomer is N-cyclohexylmaleimide.

Claim 19

A process for producing a maleimide copolymer according to Claim 13, wherein the aromatic vinyl compound monomer is styrene or α-methylstyrene.

Claim 20

A process for producing a maleimide copolymer according to Claim 13, wherein the methacrylate monomer is methyl methacrylate.

Claim 21

A process for producing a maleimide copolymer according to Claim 13, wherein the another vinyl compound monomer is acrylonitrile.