# US 10,370,574 B2 · Method for forming thermally conductive thermal radical cure silicone compositions

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- Number: US 10,370,574 B2
- Document ID: US10370574B2
- Status: Granted
- Kind: B2
- Application number: 14/766,774
- Filed: 2014-02-10
- Published: 2015-12-31
- Granted: 2019-08-06
- Earliest claimed: 2013-02-11
- Assignees: Dow Silicones Corporation
- Applicants: Dow Silicones Corporation
- Inventors: Arianne Tan; Yin Tang; James Tonge
- Web page: https://patentgrep.com/patent/US10370574B2

## CPC

- C09K 5/14: Solid materials, e.g. powdery or granular
- C08L 83/06: containing silicon bound to oxygen-containing groups (C08L83/12 takes precedence)
- C08L 83/14: in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms (C08L83/10 takes precedence)
- C09D 183/04: Polysiloxanes
- C09J 183/06: containing silicon bound to oxygen-containing groups (C09J183/12 takes precedence)
- C09J 183/14: in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms (C09J183/10 takes precedence)
- C08G 77/12: containing silicon bound to hydrogen
- C08G 77/14: containing silicon bound to oxygen-containing groups
- C08G 77/20: containing silicon bound to unsaturated aliphatic groups
- C08K 2003/2227: {of aluminium}
- C08L 83/00: Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

A method for forming a thermally conductive thermal radical cure silicone composition comprising (I) a clustered functional polyorganopolysiloxane; optionally (II) a silicone reactive diluent, (III) a filler comprising a thermally conductive filler, (III′) a filler treating agent, and (IV) a radical initiator is provided. In this method, the clustered functional polyorganosiloxane (I) and the optional silicone reactive diluent (II) are premade prior to their addition to respective components (III), (III′) and (IV).

## Claims

### Claim 1

A method for forming a thermally conductive thermal radical cure silicone composition comprising (I) a clustered functional polyorganopolysiloxane; (II) a silicone reactive diluent; (III) a filler comprising a thermally conductive filler, (III′) a filler treating agent, and (IV) a radical initiator, the method comprising:
(A) providing a clustered functional polyorganosiloxane (I) that comprises a reaction product of a reaction of:
a) a polyorganosiloxane having an average, per molecule, of at least 2 aliphatically unsaturated organic groups,
b) a polyorganohydrogensiloxane having an average, per molecule, of 4 to 15 silicon atoms and at least 4 silicon bonded hydrogen atoms per aliphatically unsaturated organic group in component a),
c) a reactive species having, per molecule at least one aliphatically unsaturated organic group and one or more curable groups selected from acrylate groups and methacrylate groups, and
in the presence of d) a hydrosilylation catalyst and e) an isomer reducing agent, wherein the isomer reducing agent is present in an amount based on the total weight of the clustered functional polyorganosiloxane (I) to produce at least a 10% reduction in beta-addition of SiH groups to the polyorganosiloxane to the aliphatically unsaturated group of the reactive species as compared to a clustered functional polyorganosiloxane formed in the absence of the isomer reducing agent;
(B) forming a first mixture by mixing the filler (III) comprising the thermally conductive filler, the filler treating agent (III′), and at least one of the silicone reactive diluent (II) and the clustered functional polyorganosiloxane (I);
(C) heating the first mixture to a temperature from 50° C. to 110° C. to treat the thermally conductive filler (III) with the filler treating agent (III′)
(D) after heating in step (C), introducing the silicone reactive diluent (II), the clustered functional polyorganosiloxane (I), or neither to the first mixture as needed to obtain a final mixture that comprises both the silicone reactive diluent (II) and the clustered functional polyorganosiloxane (I); and then
(E) cooling the final mixture to 30° C. or less and then blending a radical initiator (IV) with the final mixture to form a thermally conductive thermal radical cure silicone composition.

### Claim 2 (depends on 1)

The method according to claim 1 further comprising:
(F) blending at least one additional component with the final mixture prior to Step (E), the at least one additional component selected from the group consisting of (III) an additional amount of filler comprising the thermally conductive filler, (III′) an additional amount of filler treating agent, (V) a moisture cure initiator, (VI) a crosslinker, (VII) a moisture cure polymer, (VIII) a solvent, (IX) an adhesion promoter, (X) a colorant, (XI) a reactive diluent, (XII) a corrosion inhibitor, (XIII) a polymerization inhibitor, (XIV) an acid acceptor, and any combination thereof,
wherein, after performing Step (F), the final mixture to be used in Step (E) comprises the at least one additional component.

### Claim 3 (depends on 2)

The method as set forth in claim 2, wherein the (VI) crosslinker and the moisture cure polymer (VII) are both present in the thermally conductive thermal radical cure silicone composition and wherein the amount of the crosslinker (VI) comprises from 0.001 to 50 weight percent of the total weight of moisture cure polymer (VII) and wherein the amount of the moisture cure polymer (VII) comprises from 0.1 to 5 weight percent of the total weight of thermally conductive thermal radical cure silicone composition.

### Claim 4 (depends on 2)

The method as set forth in claim 2, wherein the moisture cure polymer (VII) comprises an organopolysiloxane polymer of the formula: (OR7)3-zR6zSi-Q-(R252SiO2/2)y-Q-SiR6z(OR7)3-z, wherein each R25 is independently a monovalent hydrocarbon group having 1 to 6 carbon atoms, each R6 independently is a monovalent hydrocarbon group having 1 to 6 carbon atoms, each R7 independently is selected from the group consisting of a alkyl group and alkoxyalkyl group, Q is a divalent linking group, the subscript z has a value of 0, 1 or 2, and the subscript y has a value of 60 to 1000.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the silicone reactive diluent (II) comprises a reaction product of a reaction of:
a) a polyorganohydrogensiloxane having an average of 10 to 200 silicon atoms per molecule, and
b) a second reactive species having, per molecule, at least 1 aliphatically unsaturated organic group and 1 or more curable groups,
in the presence of c) a second isomer reducing agent and d) a second hydrosilylation catalyst and e) inhibitor for the second hydrosilylation catalyst.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the silicone reactive diluent (II) comprises a reaction product of a reaction of:
a) a siloxane compound according to the formula:
wherein:
R is a monovalent hydrocarbon having 1 to 6 carbon atoms,
R′ is a divalent hydrocarbon having 3 to 12 carbon atoms,
R″ is H or CH3, and
the subscripts m and n independently have a value from 1 to 10, and
b) a second polyorganosiloxane having an average, per molecule, of at least 2 aliphatically unsaturated organic groups,
in the presence of c) a second hydrosilylation catalyst and d) an inhibitor for the second hydrosilylation catalyst.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the silicone reactive diluent (II) comprises from 20 to 90 weight percent of a total combined weight of the clustered functional polyorganosiloxane (I) and the silicone reactive diluent (II) in the thermally conductive thermal radical cure silicone composition.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the thermally conductive filler comprises from 30 to 80 volume percent of the total volume of the thermally conductive thermal radical cure silicone composition.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the clustered functional polyorganosiloxane (I) comprises from 20 to 99.9 weight percent of a total combined weight of the clustered functional polyorganosiloxane (I) and the silicone reactive diluent (II) in the thermally conductive thermal radical cure silicone composition.