摘要:
A process for producing a fluoropolymer reduced in the content of branches and in weight change at high temperatures. It is a novel process substantially free from compositional distribution. It is a batch copolymerization process conducted under such conditions that the reduced temperature and reduced pressure obtained from the critical constants calculated with the Peng-Robinson equation from the critical temperature, critical pressure, and proportion of each monomer present in the vapor phase inside the reaction vessel are 0.95 or higher and 0.80 or higher, respectively. In the process, the proportions by weight of the additional monomers, i.e., ingredients A1, A2, ... An, are calculated using the equation (a1 - a'1 x B):(a2 - a'2 x B) ... (an - a'n x B) [wherein n is the number of kinds of monomer units in the target polymer; a1, a2, ... an (%) are the percentages by weight of the respective kinds of monomer units in the target polymer composition; a'1, a'2, ... a'n (%) are the percentages by weight of the respective monomer ingredients in the initial monomer composition; and B is the ratio of the specific gravity of vapor-phase monomers during polymerization to that of the target polymer]. Additional monomers comprising the additional monomers in those proportions by weight are added to produce a fluoropolymer.
摘要:
Disclosed is a method for producing a fluorine-containing polymer wherein an aqueous dispersion of a fluorine-containing polymer can be separated into the fluorine-containing polymer and the moisture content easily and efficiently. Also disclosed is a fluorine-containing polymer obtained by such a production method. Further disclosed is a molded article obtained by crosslinking a curable composition which contains such a fluorine-containing polymer and a crosslinking agent. Specifically disclosed is a method for producing a fluorine-containing polymer including a step wherein a fluorine-containing polymer having a moisture content of not more than 1% by weight is obtained by heating an aqueous dispersion of the fluorine-containing polymer having a concentration of 3-70% by weight.
摘要:
To provide a crosslinkable elastomer composition which is excellent in mechanical properties, ensures a small amount of outgas such as DOP and is suitable as a very clean material for molded article for semiconductor production apparatuses. The composition comprises a crosslinkable elastomer component and ultra fine powders of silicon oxide, in which the ultra fine powders of silicon oxide have 100 x 10 or less hydroxyl groups per gram on surfaces thereof, dioctylphthalate adsorption of not more than 8 mu g per 1 g of silicon oxide and an average particle size of not more than 0.5 mu m.