Nok Corporation

Denso Corporation

Freudenberg-nok General Partnership

Kenji Mikuni

Kenichi Fujimoto

Norio Tanaka

Shingo Kawano

Hisayuki Nagaoka

A method for preparing a rubber seal product of a type which contacts a metal surface for sealing thereof, comprising the steps of: preparing a rubber composition comprising acrylonitrile butadiene rubber (NBR), (A) a carbocyclic phosphite compound represented by the general formula ##STR1## where R is an alkyl group having 8 to 24 carbon atoms, or a phenyl group having a mono-, di- or tri-substituted alkyl group having 1 to 10 carbon atoms, and (B) an acid phosphate compound represented by the general formula ##STR2## where R' is a hydrogen atom, or an alkyl group having 1 to 13 carbon atoms, and R' is an alkyl group having 1 to 13 carbon atoms, the phosphate compound having an acid number of about 150 to 800 KOH mg/g; wherein a total of about 5 to 20 parts by weight of compound (A) and compound (B) are present in the composition based on 100 parts by weight of NBR, vulcanizing the rubber composition to obtain a vulcanized rubber composition; and compressing the vulcanized rubber composition toward a metal surface.

Preparing NBR rubber seal products with phosphite and phosphate additives

An acrylic rubber composition comprising 100 parts by weight of acrylic rubber containing cross-linkable groups and 2 to 40 parts by weight of tri(2-ethylhexyl) phosphate has quite an unexpected effect on prevention of fixation of its vulcanized rubber moldings to metallic materials or resin moldings when brought into direct contact with the latter due to the presence of tri(2-ethylhexyl) phosphate in the acrylic rubber containing cross-linkable groups.

Acrylic rubber composition

An active halogen-containing acrylic rubber composition for molding oil filter-gaskets, which comprises an active halogen-containing acrylic rubber and a metal phosphonate represented by the following general formula:

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Fujisawa, Japan

Kenji Mikuni