Process for producing transparent graft polymer compositions

Claim 2

A PROCESS FOR PREPARING A TRANSPARENT GRAFT POLYMER COMPOSITION COMPRISING: A. PREPARING A PREGRAFT REACTION PRODUCT IN EMULSION AND IN THE ABSENCE OF ADDED SUSPENDING AGENT BY REACTING A BUTADIENE BASED RUBBER LATEX CONTAINING FROM 0 TO 40% BY WEIGHT OF BOUND STYRENE (SB) AND HAVING AN AVERAGE RUBBER PARTICLE SIZE IN THE RANGE OF 0.01 TO 0.8 MICRON WITH A FIRST MONOMER MIXTURE OF STYRENE AND METHYL METHACRYLATE HAVING A WEIGHT RATIO IN THE RANGE OF 5/95 TO 80/20, THE WEIGHT RATIO OF TOTAL MONOMERS TO TOTAL RUBBER SOLIDS BEING IN THE RANGE OF 5/95 TO 60/40 UNDER CONDITIONS SUCH THAT ESSENTIALLY ALL OF THE MONOMER MIXTURE IS REACTED, EMPLOYING SOLELY A WATER SOLUBLE EMULSION POLYMERIZATION CATALYST IN SAID PREPARATION; B. FORMING AN AQUEOUS SUSPENSION OF A SECOND MONOMER MIXTURE OF STYRENE AND METHYL METHACRYLATE, THE EMULSION OF PREGRAFT REACTION PRODUCT FROM STEP (A) AND AN OIL SOULBLE INITIATOR THE AMOUNT OF EMULSION BEING SUFFICIENT TO PROVIDE A TOTAL RUBBER CONTENT IN THE FINAL GRAFT POLYMER COMPOSITION IN THE RANGE OF 3 TO 60 PERCENT BY WEIGHT AND THE WEIGHT RATIO OF STYRENE TO METHYL METHACRYLATE IN THE SECOND MONOMERMIXTURE BEING SUCH THAT THE CONCENTRATION OF TOTAL STYRENE (SA) BASIS THE TOTAL AMOUNT OF STYRENE AND METHYL METHACRYLATE IN THE FIRST AND SECOND MONOMER MIXTURE IS WITHIN THE LIMITS DEFINED BY THE RELATIONSHIP WT%SA=23.4+0.766 (SB)+10. C. INCREASING THE TEMPERATURE OF THE SUSPENSION CONTAINING THE EMULSION OF PREGRAFT REACTION PRODUCT TO AN INITIAL POLYMERIZATION TEMPERATURE IN THE RANGE OF 80*C TO 150*C DURING WHICH TIME THE EMULSION IS SUBSTANTIALLYU CONVERTED TO A SUSPENSION D. POLYMERIZING THEMONOMERS IN THE PRESENCE OF THE PREGRAFT REACTION PRODUCT IN SUSPENSION AT TEMPERATURES IN THE RANGE OF 80*C TO 150*C; AND E. RECOVERING THE GRAFT POLYMER COMPOSITION PRODUCT IN BEAD FROM DIRECTLY FROM SUSPENSION.

Claim 3

A process for preparing a transparent graft polymer composition comprising: a. preparing a pregrafT reaction product in emulsion and in the absence of added suspending agent by reacting a butadiene based rubber latex containing from 0 to 40% by weight of bound styrene (Sb) and having an average rubber particle size in the range of 0.01 to 0.8 micron with a first monomer mixture of styrene and methyl methacrylate having a weight ratio in the range of 5/95 to 80/20, the weight ratio of total monomers to total rubber solids being in the range of 5/95 to 60/40 under conditions such that essentially all of the monomer mixture is reacted, employing solely a water soluble emulsion polymerization catalyst in said preparation; b. forming an aqueous suspension of a second monomer mixture of styrene and methyl methacrylate, the emulsion of pregraft reaction product from step (a) and an oil soluble initiator, the amount of emulsion being sufficient to provide a total rubber content in the final graft polymer composition in the range of 3 to 60 percent by weight and the weight ratio of styrene to methyl methacrylate in the second monomer mixture being such that the concentration of total styrene (Sa) basis the total amount of styrene and methyl methacrylate in the first and second monomer mixture is within the limits defined by the relationship wt%Sa 23.4 + 0.766 (Sb) + or - 10. c. increasing the temperature of the suspension containing the emulsion of pregraft reaction product to an initial polymerization temperature in the range of 80*C to 150*C during which time the emulsion is substantially converted to a suspension; d. polymerizing the monomers in the presence of the pregraft reaction product in suspension at temperatures in the range of 80*C to 150*C; and e. recovering the graft polymer composition product in bead form directly from suspension.

Claim 4

A process for preparing a transparent graft polymer composition comprising: a. preparing a pregrafT reaction product in emulsion and in the absence of added suspending agent by reacting a butadiene based rubber latex containing from 0 to 40% by weight of bound styrene (Sb) and having an average rubber particle size in the range of 0.01 to 0.8 micron with a first monomer mixture of styrene and methyl methacrylate having a weight ratio in the range of 5/95 to 80/20, the weight ratio of total monomers to total rubber solids being in the range of 5/95 to 60/40 under conditions such that essentially all of the monomer mixture is reacted, employing solely a water soluble emulsion polymerization catalyst in said preparation; b. forming an aqueous suspension of a second monomer mixture of styrene and methyl methacrylate, the emulsion of pregraft reaction product from step (a) and an oil soluble initiator, the amount of emulsion being sufficient to provide a total rubber content in the final graft polymer composition in the range of 3 to 60 percent by weight and the weight ratio of styrene to methyl methacrylate in the second monomer mixture being such that the concentration of total styrene (Sa) basis the total amount of styrene and methyl methacrylate in the first and second monomer mixture is within the limits defined by the relationship wt%Sa 23.4 + 0.766 (Sb) + or - 10. c. increasing the temperature of the suspension containing the emulsion of pregraft reaction product to an initial polymerization temperature in the range of 80*C to 150*C during which time the emulsion is substantially converted to a suspension; d. polymerizing the monomers in the presence of the pregraft reaction product in suspension at temperatures in the range of 80*C to 150*C; and e. recovering the graft polymer composition product in bead form directly from suspension.

Claim 5

A process according to claim 1 wherein the butadiene based rubber latex is polybutadiene.

Claim 6

A process according to claim 1 wherein the butadiene based rubber latex is an elastomeric polymer of butadiene with 20 to 35 percent by weight styrene.

Claim 7

A process according to claim 1 wherein the butadiene based rubber latex has an average rubber particle size in the range of 0.05 to 0.2 micron.

Claim 8

A process according to claim 1 wherein the butadiene based rubber latex has an average rubber particle size which is larger than 0.2 micron and the concentration of total styrene Sa is maintained whithin the limits defined by the relationship wt% Sa 23.4 + 0.766(Sb) + or - 5.

Claim 9

A process according to claim 1 wherein a chain regulating agent is employed in step (a) or step (b) or both steps (a) and (b).

Claim 10

A process according to claim 1 wherein a minor amount of an additional monomer is employed in step (a) or step (b) or both steps (a) and (b), said monomer being acrylonitrile, ethyl acrylate, alpha-methyl styrene, butyl acrylate, methacrylonitrile, or mixtures thereof.

Claim 11

A process according to claim 1 wherein the aqueous suspension includes a compound selected from the group consisting of ethylenediamine tetraacetic acid, methylene disaliclic acid, salicylic acid, citric acid, tartaric acid, ascorbic acid, phosphoric acid and partial alkali metal salts thereof containing at least one free carboxylic acid group per molecule.

Claim 12

A process according to claim 1 wherein the weight ratio of total monomers to total rubber solids in step (a) is in the range of 15/85 to 50/50.