The present invention relates to the preparation of a thermoplastic fluoropolymer blend composition exhibiting improved mechanical properties upon fabrication. The fluoropolymer blend composite on is produced by blending an emulsion latex of fluoropolymer (A) with an emulsion latex of fluorinated copolymer (B). Copolymer (B) emulsion has a small particle size, super high MW, and a low degree of crystallinity. The blending of the latex emulsions results in a morphology with small particles of copolymer (B) uniformly distributed within a matrix of fluoropolymer (A) in a manner that could not be achieved by a mere melt blending of the tow components.

A seal can include a body including a thermoplastic material and a filler material including a fluoropolymer. The fluoropolymer can include a modified fluoropolymer. The body can include an elongation-at-break of at least 3%. In an embodiment, the seal can include a seal ring, wherein the body of the seal ring can include a weld.

To provide a prepreg excellent in storage stability and capable of obtaining a fiber-reinforced molded product excellent in impact resistance, and a method for its production, as well as a fiber-reinforced molded product excellent in impact resistance. The prepreg comprises reinforcing fibers and a matrix resin, wherein the matrix resin comprises a thermoplastic resin (but excluding the following fluororesin) and a melt-formable fluororesin having a melting point of from 100 to 325 C. and having functional groups of at least one type selected from the group consisting of carbonyl group-containing groups, hydroxy groups, epoxy groups and isocyanate groups, and in 100 mass % of the total of the thermoplastic resin and the fluororesin, the proportion of the thermoplastic resin is from more than 30 to 99 mass % and the proportion of the fluororesin is from 1 to less than 70 mass %.

A method for producing a molded product in which the resin F is dispersed in the resin P, the method comprising: melting a composition comprising a polyimide-type thermoplastic resin P and a fluorine-type thermoplastic resin F having a glass transition temperature lower than that of the resin P, the composition having a difference Tg between a glass transition temperature Tgp of the resin P and a glass transition temperature Tgf of resin F of 75 to 175 C. at a temperature equal to or higher than the melting point of the resin P or the melting point of resin F, whichever is higher, to obtain a molten product; and starting to cool the molten product at a cooling rate of 10 C./min or more to obtain a molded product.

To provide a prepreg excellent in storage stability and capable of obtaining a fiber-reinforced molded product excellent in impact resistance, and a method for its production, as well as a fiber-reinforced molded product excellent in impact resistance. The prepreg comprises reinforcing fibers and a matrix resin, wherein the matrix resin comprises a thermoplastic resin (but excluding the following fluororesin) and a melt-formable fluororesin having a melting point of from 100 to 325 C. and having functional groups of at least one type selected from the group consisting of carbonyl group-containing groups, hydroxy groups, epoxy groups and isocyanate groups, and in 100 mass % of the total of the thermoplastic resin and the fluororesin, the proportion of the thermoplastic resin is from more than 30 to 99 mass % and the proportion of the fluororesin is from 1 to less than 70 mass %.