Porous synthetic resin molded part and method of producing the same

Abstract

A method of producing a porous molded part includes a mixing process for mixing a granular porous organizer composed of a water-soluble compound, a porous forming assistant agent composed of a polyhydric alcohol, and a cross-linking agent composed of an organic peroxide with a thermoplastic resin composition having a glass transition temperature below 0° C. to obtain a molding material; a cross-linking and forming process for placing the molding material in a molding die and performing a heat press molding thereby progressing coincidentally a cross-linking reaction and a shape forming of a seal face to obtain a molded material; an extracting process for extracting the granular porous organizer from the molded material obtained in the cross-linking and forming process to obtain a porous molded part; and a drying process for drying the porous molded part obtained in the extracting process.

What is claimed is: 
     
         1 . A method of producing a porous synthetic resin molded part, comprising the steps of:
 mixing a granular porous organizer composed of a water-soluble compound, a porous forming assistant agent composed of a polyhydric alcohol, and a cross-linking agent composed of an organic peroxide with a thermoplastic resin composition to obtain a molding material, said thermoplastic resin composition having a glass transition temperature below 0° C.;   placing the molding material in a molding die and performing a direct pressure molding for performing a cross-linking reaction between the thermoplastic resin composition and the cross-linking agent and forming a seal face coincidentally to obtain a molded material;   extracting the granular porous organizer and the porous forming assistant agent from the molded material to obtain a porous molded part; and   drying the porous molded part to obtain the porous synthetic resin molded part.   
     
     
         2 . The method of producing the porous synthetic resin molded part according to  claim 1 , wherein, in the step of mixing, said thermoplastic resin composition is composed of at least one of an ethylene-vinyl acetate copolymer, a thermoplastic elastomer, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and an ethylene alpha-olefin copolymer. 
     
     
         3 . The method of producing the porous synthetic resin molded part according to  claim 1 , wherein, in the step of mixing, 150 to 500 parts by weight of the granular porous organizer and the porous forming assistant agent and 1 to 5 parts by weight of the cross-linking agent are mixed into 100 parts by weight of the thermoplastic resin composition according to a porosity of the porous synthetic resin molded part. 
     
     
         4 . The method of producing the porous synthetic resin molded part according to  claim 1 , wherein, in the step of mixing, said cross-linking agent is composed of a peroxy ketal. 
     
     
         5 . The method of producing the porous synthetic resin molded part according to  claim 1 , wherein in the step of mixing, said porous organizer is composed of pentaerythritol and said porous forming assistant agent is composed of a mixture of polyethylene glycol and glycerin. 
     
     
         6 . The method of producing the porous synthetic resin molded part according to  claim 1 , wherein in the step of extracting the granular porous organizer, the molded material is immersed in heated water at 70° C. to 100° C.