Tokyo Sheet Co., Ltd.

Tokyo Seat Co., Ltd.

Kimio Yoshimura

Hirokazu Ohmura

A process for producing a urethane foam having a high density outer surface layer, of the type wherein a plastic liquid containing aromatic isocyanates, polyols, a catalyst, low-molecular polyols used as a crosslinker or a chain extender, a blowing agent consisting of water, and an assistant is poured into a closed mold through a one-shot molding process, a certain type of catalyst is added to create a difference in gas evolving reaction between an inner part and an outer part of the plastic liquid within the mold so as to form a high density layer on the outer surface of a urethane form. The catalyst includes a piperazine compound, a morpholine compound, or a mixture thereof. An imidazole compound, a triazine compound, an amidine compound or an organic acid salt of the amidine compound, or a mixture resulting from any combination thereof may be used in combination with the piperazine compound or a morpholine compound.

Process for producing urethane foam with high density skin

In a method of preparing a urethane foam article having a high density outer surface layer, of the type wherein a plastic liquid containing isocyanates, polyols, a catalyst, a blowing agent, an assistant and other additives is poured into a mold through a one-shot molding process, a certain type of catalyst is added for causing the isocyanates and the blowing agent to create a difference in gas evolving reaction between an inner part and an outer part of the plastic liquid in the mold so as to form a high density layer on the outer surface of a urethane foam article.

Method of preparing urethane foam articles

In a method of preparing a urethane foam article having a high density outer surface layer, of the type wherein a plastic liquid containing isocyanates, polyols, a catalyst, a blowing agent, an assistant and other additives is poured into a mold through a one-shot molding process, while maintaining the mold at a temperature in the range of from 15.degree. to 40.degree. C., a temperature sensitive catalyst is added for causing the isocyanates and the blowing agent to create a difference in chemical reaction between an outer portion of the plastic liquid contacting the mold surface and an inner portion of the plastic liquid held out of contact with the mold surface, thereby retarding the foaming of the outer portion than that of the outer portion. Subsequently, a evolved gas is allowed to expand under exothermic heat of the inner portion of the plastic liquid while at the same time the evolved gas is taken up by gelation of the plastic liquid, thereby increasing the blowing pressure rapidly until the mold is over-packed with a foaming plastic mass. Finally, an outer portion of the foaming plastic mass extending along the mold surface is gelled while inhibiting the foaming of the last-mentioned outer portion, thus forming a high density layer on the outer surface of a urethane foam article.

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Urawa, Japan

Kimio Yoshimura