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Grease compatible mineral oil extended polyurethane

  • US 4,231,986 A
  • Filed: 04/06/1979
  • Issued: 11/04/1980
  • Est. Priority Date: 04/06/1979
  • Status: Expired due to Term
First Claim
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1. A process for sealing an insulated electrical device comprising the steps of introducing into said device a composition comprising mineral oil, polyurethane precursor and coupling agent,(a) said polyurethane precursor comprising the reaction product of(i) a polyisocyanate compound or a polyisocyanate prepolymer prepared by the reaction of a polyisocyanate compound with a polyol selected from the group consisting of castor oil, polyether polyols, hydroxyl bearing homopolymers of dienes, hydroxyl bearing copolymers of dienes, and combinations thereof, wherein at least about 0.25 equivalents of the polyisocyanate compound per 1.0 equivalents of the polyisocyanate compound used is a liquid long chain aliphatic polyisocyanate, and(ii) a polyol selected from the group consisting of castor oil, polyether polyols, hydroxyl bearing homopolymers of dienes, hydroxyl bearing copolymers of dienes, and combinations thereof,(b) said mineral oil being characterized by having from about 1.0 to about 30% aromatic carbon atoms, based on the total number of carbon atoms present in the mineral oil, and(c) said coupling agent being characterized by(i) being miscible in all proportions with said mineral oil,(ii) having a total solubility parameter from about 7.0 to about 9.5,(iii) having a hydrogen bonding index number from about 6.0 to about 12.0, and(iv) being substantially non-reactive with said polyisocyanate prepolymer and said polyol,reacting said polyol with said polyisocyanate in the presence of said mineral oil and said coupling agent to obtain a grease compatible, cured, cross-linked, mineral oil extended polyurethane which is non-spewing, and which is characterized by the presence of a polydiene moiety in the polyurethane structure, and which comprises from about 8 to about 45 parts of polyurethane, from about 20 to about 75 parts of mineral oil and from about 10 to about 47 parts of coupling agent, all parts expressed on a weight basis.

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