Room-temperature curable organopolysiloxane composition

• US 20040082736A1
• Filed: 10/14/2003
• Published: 04/29/2004
• Est. Priority Date: 10/25/2002
• Status: Active Grant

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Sakamoto, Takafumi, Kimura, Tsuneo, Kameda, Norio
• Granted Patent: US 6,939,925 B2
• Time in Patent Office: Days
• US Class Current: 525/477
• CPC Class Codes: C08G 77/44 containing only polysiloxane sequences
• CPC Class Codes: C08L 83/10 Block- or graft-copolymers containing polysiloxane sequences obtained by polymerising a compound having a carbon-to-carbon double bond on to a polysiloxane C08L51/08, C08L53/00
• CPC Class Codes: C09D 5/1675 Polyorganosiloxane-containing compositions

Abstract

Provided is a room-temperature curable organopolysiloxane composition including (I) an organopolysiloxane, and (II) a silane compound containing silicon-bonded hydrolysable groups and/or a partial hydrolysis-condensation product thereof. The organopolysiloxane (I) is a condensation product of (A) an organosiloxane which includes R₃SiO_1/2 units wherein R represents an unsubstituted or substituted monovalent hydrocarbon group and SiO_4/2 units, in which the molar ratio R₃SiO_1/2 to SiO_4/2 is 0.6 to 1.2, and further includes less than 2.0% by weight of silicon-bonded hydroxyl groups, and (B) a diorganopolysiloxane with molecular chain terminals blocked with functional group-containing silyl groups. This composition generates a cured product or coating film with good transparency and good strength, which is useful as a coating material for electrical or electronic components or circuits, a sealant for liquid crystal display elements, and an antifouling paint for underwater structures.

Claims

1. A room-temperature curable organopolysiloxane composition comprising:

(I) 100 parts by weight of an organopolysiloxane that is a condensation reaction product of 100 parts by weight of a component (A) described below, and from 1 to 200 parts by weight of a component (B) described below,

(A) an organopolysiloxane which comprises from R₃SiO_1/2 units (wherein, each R represents, independently, an unsubstituted or substituted monovalent hydrocarbon group of 1 to 6 carbon atoms) and SiO_4/2 units, in which a number of mols of said R₃SiO_1/2 units relative to 1 mol of said SiO_4/2 units is from 0.6 to 1.2 mols, and which may further comprises from 0 to 1.0 mols of both R₂SiO_2/2 units and RSiO_3/2 units (wherein in each formula, R is as defined above) relative to 1 mol of said SiO_4/2 units, and moreover comprises less than 2.0% by weight of hydroxyl groups bonded to silicon atoms,

(B) a diorganopolysiloxane with molecular chain terminals blocked with functional group-containing silyl groups; and

(II) from 0.1 to 30 parts by weight of a silane compound containing two or more hydrolysable groups bonded to silicon atoms within one molecule, and/or a partial hydrolysis-condensation product thereof.

2. The composition according to claim 1, wherein the number of mols of the R₃SiO_1/2 units relative to 1 mol of the SiO_4/2 units in the component (A) is within a range from 0.65 to 1.15 mols.

3. The composition according to claim 1, wherein in said component (A) the R₂SiO_2/2 units and RSiO_3/2 units are present, and the quantities of both of the R₂SiO_2/2 units and RSiO_3/2 units are each within a range from 0.2 to 0.8 mols relative to 1 mol of said SiO_4/2 units.

4. The composition according to claim 1, wherein in said component (A) said hydroxyl groups bonded to silicon atoms are present in a quantity of at least 0.1% by weight but less than 2.0% by weight.

5. The composition according to claim 1, wherein in said component (A) said hydroxyl groups bonded to silicon atoms are present in a quantity of 0.2% to 1.8% by weight.

6. The composition according to claim 1, wherein said component (B) is a diorganopolysiloxane represented by a general formula (1) shown below:

7. The composition according to claim 6, wherein in said general formula (1) each R¹ is a methyl group, and each X is a hydroxyl group or an alkoxy group.

8. The composition according to claim 6, wherein in said general formula (1) n is a number that results in a fluid diorganopolysiloxane with a viscosity at 25°

C. of no more than 300,000 mm²/s.

9. The composition according to claim 1, further comprising:

(III) from 1 to 200 parts by weight of an organopolysiloxane containing from 3 to 50 mol % of phenyl groups, and with molecular chain terminals blocked with trialkylsiloxy groups and/or functional group-containing silyl groups.

10. The composition according to claim 1, further comprising:

(IV) from 1 to 200 parts by weight of an organopolysiloxane containing a group with a polyoxyalkylene structure, with molecular chain terminals blocked with trialkylsiloxy groups and/or functional group-containing silyl groups, and having an HLB value of 1 to 8.

11. A sealant for a liquid crystal display element comprising a composition according to claim 1.

12. A liquid crystal display element produced using a sealant for a liquid crystal display element as defined in claim 11.

13. An antifouling paint for an underwater structure comprising a composition as defined in claim 1.