초록

A heat cured fluorosilicone rubber exhibiting improved compression set comprises N,N'-meta-phenylenedimaleimide.

대표청구항 ▼

[ Having described the invention that which is claimed is:] [1.] A heat curable fluorosilicone rubber comprising:a) from about 55.0 to about 61.0 weight percent of a vinyl terminated fluorosilicone homopolymer having the formula: [ STR 14 ] where R.sup.1, R.sup.2, and R.sup.3 are each independently

[ Having described the invention that which is claimed is:] [1.] A heat curable fluorosilicone rubber comprising:a) from about 55.0 to about 61.0 weight percent of a vinyl terminated fluorosilicone homopolymer having the formula: [ STR 14 ] where R.sup.1, R.sup.2, and R.sup.3 are each independently selected from the group consisting of one to ten carbon atom aliphatic and aromatic monovalent hydrocarbon radicals, the subscripts a and c are positive integers which independently range from one to about ten, the subscript b is a positive integer which ranges from about 1,920 to about 4,480, and the subscript d is a positive integer which ranges from two to about six, and a vinyl content ranging from about 70 to about 200 parts per million by weight;b) from about 1.0 to about 4.0 weight percent of a vinyl terminated vinyl on chain fluorosilicone copolymer having the formula: [ STR 15 ] where R.sup.4, R.sup.5, R.sup.6, and R.sup.7 are each independently selected from the group consisting of one to ten carbon atom aliphatic and aromatic monovalent hydrocarbon radicals, the subscripts e and h are positive integers which each independently range from one to about twenty-five, the subscript f is a positive integer which ranges from about 700 to about 1,700, the subscript g is a positive integer which ranges from about 2,500 to about 6,500, the subscript i is a positive integer which ranges from two to about six, having a vinyl content ranging from about 3.0 to about 4.5 weight percent;c) from about 0.04 to about 0.5 weight of 1,3-divinyl-1,1,3,3-tetramethyldisilazane, [ STR 16 ] d) from about 0.5 to about 4.0 weight percent of a silanol terminated vinyl on chain copolymeric telomeric fluorosilicone fluid having the formula: [ STR 17 ] where R.sup.8 and R.sup.9 are each independently selected from the group consisting of one to ten carbon atom aliphatic and aromatic monovalent hydrocarbon radicals, the subscript j is a positive integer which ranges from one to about six, the subscript k is a positive integer which ranges from about one to about six, and the subscripts m and n are a positive integers which each independently range from two to about six where the vinyl content ranges from about 3.0 to about 7.0 weight percent;e) from about 3.0 to about 10.0 weight percent of a silanol terminated telomeric fluorosilicone fluid having the formula: [ STR 18 ] where R.sup.10 and R.sup.11 are each independently selected from the group consisting of one to ten carbon atom aliphatic and aromatic monovalent hydrocarbon radicals, the subscript p is a positive integer which ranges from one to about twenty, and the subscripts q and r are positive integers which each independently range from two to about six;n) from about 8 to about 22 weight percent of fumed or pyrogenic silica, SiO.sub.2, reinforcing filler which has an average particle size ranging from about 9 nanometers to about 16 nanometers, with a surface area ranging from about 170 to about 240 m.sup.2 /gm;o) from about 0.3 to about 1.5 weight percent of an organic peroxide cure initiator; andp) from about 0.10 to about 2.0 weight percent of N,N'-meta-phenylenedimaleimide.