Silanol-free resins

• US 4,130,599 A
• Filed: 06/16/1976
• Issued: 12/19/1978
• Est. Priority Date: 05/19/1975
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Merrill, Duane F., Cooke, Richard C. Jr.
• Primary Examiner(s): Marquis, Melvyn I.
• Application Number:
  US05/696,663
• Time in Patent Office: 916 Days
• Field of Search: 260/46.5 R, 260/825, 260/37 SB, 260/29.1 SB
• US Class Current: 525/477
• CPC Class Codes: C08G 77/06 Preparatory processes C08G77/045 takes precedence
• CPC Class Codes: C08G 77/16 to hydroxyl groups
• CPC Class Codes: C08G 77/24 halogen-containing groups
• CPC Class Codes: 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
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane

Abstract

A silicone molding composition with improved thermal shock resistance having a plasticizing amount of a silicone resin comprising chemically combined RSiO_3/2 units and R₂ SiO units where the R to Si ratio may vary from 1.0 to 1.9 and the ratio of RSiO_3/2 units to R₂ SiO units may vary from 1:2.5 to 1:5.0 and containing less than 0.5 weight percent of silanol groups and preferably being substantially free of silanol groups where R is a monovalent hydrocarbon radical. There is also provided by the present invention a process for improving the thermal shock resistance of a silicone molding composition by having in said composition the aforesaid resin.

Claims

1. A silicone molding composition with improved thermal shock resistance having therein a base silicone resin having R¹ SiO_3/2 unit and R₂¹ SiO units where R¹ is selected from the class consisting of monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals, a filler and comprising the improvement in which there is present a plasticizing amount of a low-silanol content silicone resin having less than 0.5 weight silanol groups and an R to Si ratio that varies from 1.0:

1 to 1.9;

1 that is produced by the process comprising (a) adding a mixture of hydrolyzable silanes of the formula,

space="preserve" listing-type="equation">R.sub.a SiX.sub.4-a

to water where there is present at least 2 parts of water per part of said silanes and 1 to 5 parts of a water-immiscible organic solvent per part of said silanes at a temperature range of 25°

C. to 85°

C. and where the silanes are added to said water slowly so as to form a hydrolyzate;

(b) continually agitating said mixture;

(c) separating the organic layer and adjusting it to 10-40% solids;

(d) within 24 hours from the formation of said hydrolyzate catalyzing said organic layer with 300-600 ppm of an alkali metal hydroxide per part of solid, and refluxing the resulting mixture at 100°

-160°

C.;

(e) neutralizing the alkali metal hydroxide in the refluxed mixture with acetic acid; and

(f) stripping from the organic layer excess acetic acid and solvent, where R is selected from the group consisting of alkyl radicals of 1 to 8 carbon atoms, cycloalkyl radicals of 5 to 7 carbon atoms, alkenyl radicals of 2 to 8 carbon atoms, mononuclear aryl radicals, mononuclear aryl lower alkyl radicals where the alkyl portion is 1 to 6 carbon atoms and halogenated derivatives of the above radicals, where X is a chlorine radical and a is a whole number that varies from 1 to 2 and such that 40 mole percent to 60 mole percent of the R radicals are selected from the class consisting of mononuclear aryl radicals and mononuclear aryl lower radicals and halogenated derivatives of the foregoing radicals.

2. The composition of claim 1 wherein the water-immiscible organic solvent is selected from the group consisting of toluene, xylene, heptane, octance and cyclohexane.

3. The composition of claim 1 wherein the alkali metal hydroxide is potassium hydroxide.

4. The composition of claim 1 where R is selected from methyl and phenyl.

5. The composition of claim 1 wherein the low-silanol content resin is substantially silanol-free and has an R to Si ratio of 1.5:

1 to 1.9;

1.

6. A process for improving the thermal shock resistance of a silicone resin molding composition comprising adding to a base silicone resin having R¹ SiO_3/2 unit and R₂¹ SiO unit wherein R¹ is selected from the class consisting of monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals and a filler and a plasticizing amount of a low-silanol content silicone resin produced by the process comprising (a) adding a mixture of hydrolyzable silanes of the formula,

View Dependent Claims (7, 8, 9, 10)

7. The process of claim 6 wherein the water-immiscible organic solvent is selected from the group consisting of toluene, xylene, heptane, octane and cyclehexane.

8. The process of claim 6 wherein the alkali metal hydroxide is potassium hydroxide.

9. The process of claim 6 where R is selected from methyl and phenyl.

10. The process of claim 6 wherein the low silanol content resin is substantially silanol-free and has an R to Si ratio of 1.5:

1 to 1.9;

1.