Patent US4806592A successfully refreshed from Google Patents.
US4806592A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Storage-stable liquid silicone rubber composition containing a platinum-alkenysiloxane complex catalyst
Assignee: DuPont Toray Specialty Materials KK
•
Filing: 1987-08-31
•
Granted: 1989-02-21
•
Expires: 2007-08-31
Abstract
Abstract The liquid silicone rubber compositions of this invention comprise an organopolysiloxane having silicon-bonded alkenyl radicals, a reinforcing silica filler and, as the curing catalyst, a platinum-alkenylsiloxane complex wherein the pKa value of the catalyst when measured under a specifed set of conditions is from 2.0 to 9.0, inclusive. The compositions have an excellent storage stability as one part of a two-package liquid silicone rubber composition that cures by a platinum catalyzed hydrosilation reaction.
Inventors
- 👤 Toshio Saruyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:14
CPC Classifications
C; C08; C08K; C08K3/00; C08K3/34; C08K3/36; C08K5/00; C08K5/0091
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
119 words
In an improved liquid silicone rubber composition comprising the product obtained by blending to homogeniety (A) an organopolysiloxane containing at least 2 silicon-bonded alkenyl radicals in each molecule and having a viscosity of from 100 to 300,000 centipoise (0.1-300 Pa.s) at 25° C. (B) a microparticulate hydrophilic silica, and (C) an amount of a platinum-alkenylsiloxane complex sufficient to promote curing of said composition in the presence of an organohydrogensiloxane, the improvement characterized by the pK a value exhibited by a dispersion in a nonpolar solvent of 100 parts by weight of said silica and from 10 to 100 weight parts of said complex as atomic platinum, where said value is within the range of from 2.0 to 9.0, inclusive.
Claim 2
Dependent Claim
119 words
In an improved liquid silicone rubber composition comprising the product obtained by blending to homogeniety (A) an organopolysiloxane containing at least 2 silicon-bonded alkenyl radicals in each molecule and having a viscosity of from 100 to 300,000 centipoise (0.1-300 Pa.s) at 25° C. (B) a microparticulate hydrophilic silica, and (C) an amount of a platinum-alkenylsiloxane complex sufficient to promote curing of said composition in the presence of an organohydrogensiloxane, the improvement characterized by the pK a value exhibited by a dispersion in a nonpolar solvent of 100 parts by weight of said silica and from 10 to 100 weight parts of said complex as atomic platinum, where said value is within the range of from 2.0 to 9.0, inclusive.
Claim 3
Dependent Claim
19 words
A composition according to claim 1 where said silica is produced by the reaction of water glass with acid.
Claim 4
Dependent Claim
12 words
A composition according to claim 1 where said alkenylsiloxane is a divinyltetramethyldisiloxane.
Claim 5
Dependent Claim
13 words
A composition according to claim 3 where said alkenylsiloxane is a symmetrical divinyltetraalkyldisiloxane.
Claim 6
Dependent Claim
11 words
A composition according to claim 4 where said alkenylsiloxane is sym-tetramethyldivinyldisiloxane.
Claim 7
Dependent Claim
14 words
A composition according to claim 1 where said nonpolar solvent is an aromatic hydrocarbon.
Claim 8
Dependent Claim
12 words
A composition according to claim 6 where said aromatic hydrocarbon is benzene.
Claim 9
Dependent Claim
68 words
A composition according to claim 1 where the pK a value of the silica is adjusted by treating it with a basic material selected from the group consisting of an alkali metal, an alkaline earth metal, an alkali metal hydroxide, an alkali metal silanolate, an alkali metal alcoholate, an alkaline earth metal hydroxide, an alkaline earth metal silanolate, and a calcium salt of a higher aliphatic carboxylic acid.
Claim 10
Dependent Claim
17 words
A composition according to claim 8 where the silica treating agent is sodium hydroxide or calcium stearate.
Claim 11
Dependent Claim
22 words
A composition according to claim 1 where said organopolysiloxane is a diorganovinylsiloxy-terminated diorganopolysiloxane exhibiting a viscosity of from 300 to 100,000 centipoise.
Claim 12
Dependent Claim
14 words
A composition according to claim 10 where said diorganovinylsiloxy-terminated diorganopolysiloxane is a dimethylvinylsiloxy-terminated dimethylpolysiloxane.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-21 | 1992-08-22 | 1993-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-21 | 1996-08-22 | 1997-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-21 | 2000-08-22 | 2001-02-21 | $7700.00 | Window Closed / Lapsed |