Flame-retardant polyolefin compositions, their method of preparation and insulated electrical conductors manufactured therewith

Claim 1

A curable polyolefin composition blend comprising an alpha-substituted polyolefin, about 1 to about 30 percent of a silarylenesiloxane-polydiorganosiloxane block copolymer and from zero to about 150 percent of a filler based on the weight of the polyolefin.

Claim 17

A method for preparing a cured polyolefin composition which comprises: (A) Blending (1) an alpha-substituted polyolefin resin; (2) from about 1 to about 30 weight percent based on the weight of the polyolefin of a silarylenesiloxane-polydiorganosiloxane block copolymer made up of units of silarylenesiloxane having the general formula: ##STR5## and diorganopolysiloxane of the general formula: ##STR6## wherein n is an integer equal to 1 to about 100, R is a divalent aromatic organic radical, R 1 is a monovalent organic radical, a is an integer equal to from about 5 to about 10,000 inclusive, and R 2 is an organic radical selected from the group consisting of monovalent hydrocarbon radicals, unsaturated aliphatic radicals and halogenated radicals; (3) a sufficient amount of an organotertiary peroxide curing agent; and (4) from zero to about 150 percent by weight of the polyolefin of a filler; and (B) heating the resultant composition sufficiently to affect curing thereof.

Claim 18

A method for preparing a cured polyolefin composition which comprises: (A) Blending (1) an alpha-substituted polyolefin resin; (2) from about 1 to about 30 weight percent based on the weight of the polyolefin of a silarylenesiloxane-polydiorganosiloxane block copolymer made up of units of silarylenesiloxane having the general formula: ##STR5## and diorganopolysiloxane of the general formula: ##STR6## wherein n is an integer equal to 1 to about 100, R is a divalent aromatic organic radical, R 1 is a monovalent organic radical, a is an integer equal to from about 5 to about 10,000 inclusive, and R 2 is an organic radical selected from the group consisting of monovalent hydrocarbon radicals, unsaturated aliphatic radicals and halogenated radicals; (3) a sufficient amount of an organotertiary peroxide curing agent; and (4) from zero to about 150 percent by weight of the polyolefin of a filler; and (B) heating the resultant composition sufficiently to affect curing thereof.

Claim 23

The method of claims 16 or 18, wherein the polyolefin is an alpha-substituted polyethylene.

Claim 24

The method of claims 16 or 18, wherein the polyolefin is selected from the group consisting of polyvinyl chloride, styrene and polyvinyl acetate.

Claim 25

The method of claims 16 or 18, wherein a has an average of between 10 and 1,000 inclusive.

Claim 26

The method of claims 16 or 18, wherein R 2 is selected from the group consisting of a methyl radical, an ethyl radical, and a combination of methyl and ethyl radicals.

Claim 27

The method of claims 16 or 18, wherein R is a phenylene radical and R 1 is a methyl radical.

Claim 28

The method of claims 16 or 18, wherein a has a value of about 26 and n has a value from about 4 to about 6.

Claim 29

The method of claims 16 or 18, wherein said peroxide curing agent is selected from the group consisting of dicumylperoxide and a,a'-bis(t-butylperoxy)di-isopropylbenzene.

Claim 30

The method of claims 16 or 18, wherein the composition is cured at a temperature of from about 149° C. to about 218° C.

Claim 31

The method of claims 16 or 18, wherein the composition is cured at a temperature of from about 163° C. to about 188° C.

Claim 32

The method of claims 16 or 18, wherein said filler is selected from the group consisting of hydrated alumina, aluminum oxide, titanium dioxide, carbon black and fume silica.

Claim 33

The method of claims 16 or 18, wherein the filler is present in an amount from about 25 percent to about 100 percent by weight of the polyolefin.

Claim 34

The method of claims 16 or 18, wherein said block copolymer contains copolymeric molecules comprising: (a) amorphous segments consisting of linked repeating units of the formula --(R 2 ) 2 SiO-- having an average minimum number of at least 10 units of --(R 2 ) 2 SiO--; and (b) crystallite segments consisting of linked repeating units of the formula --Si(R 1 ) 2 --R--(R 1 ) 2 SiO-- having an average minimum number of at least 3 units of --Si(R 1 ) 2 --R--(R 1 ) 2 SiO--, where each R 2 is a monovalent alkyl radical, each containing from 1 to about 8 carbon atoms, R 1 is a monovalent organic radical, and R is a divalent aromatic radical, the molar ratio of total --(R 2 ) 2 SiO-- units to total --Si(R 1 ) 2 --R--(R 1 ) 2 SiO-- units ranging from about 10:90 to about 95:5.