Process for producing expandable beads of polymethyl methacrylate
OwnerYoshinari Takano, Keiji Fujita +4inventors
InventorsYoshinari Takano, Keiji Fujita, Yasuo Teraoka, Masahiro Nishida, Ryoichi Fujitani, Yaichi Kuratomo
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Abstract
A process for improving the production of polymethyl methacrylate beads or copolymeric methyl methacrylate and vinyl beads wherein the monomer is polymerized in the presence of a foaming agent and foaming agent stabilizer and within an atmosphere of inert gas, such as nitrogen, at a pressure of at least 4 kg/cm.sup.2.G. The polymerizatin is pressurized after the reaction has proceeded to a conversion ratio of from 30 to 70%. The process essentially eliminates aggregation and "sticking together" of the beads produced thereby.
Claims9
In a process for the production of expandable beads of polymerized methacrylates and methacrylate-vinyl mixtures from monomers thereof, by the process of dissolving a foaming agent preservant in the selected monomer, adding a polymerization initiator, polymerization regulator and a foaming agent to the solution, and then adding the thus obtained mixture to an aqueous solution of a suspension agent;
- the improvement comprising the steps of heating the suspended reaction mixture to a temperature of from about 60-90.degree. C in an autoclave to commence the polymerization reaction, thereafter pressurizing the reaction mixture with an inert gas to a pressure of at least 4 kg/cm.sup.2.G when the conversion ratio reaches about 30-70%, and then continuing the polymerization reaction at a temperature of from about 65.degree.-90.degree. C for a period from about 4-10 hours.
Dependencies are inferred from the claim text.