Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-01-05
2001-06-19
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S032000, C528S033000, C528S034000, C528S037000, C528S043000, C556S460000, C556S461000
Reexamination Certificate
active
06248853
ABSTRACT:
BACKGROUND OF THE INVENTION
It is well known that silicone resins can be obtained from organic chloro silane or organic alkoxy silane by means of hydrolysis and polycondensation. Under the presence of a catalyzer or by means of heating, silicone resins can be turned to an insoluble thermosetting product of three-dimensional network structure. When hardened, silicone resins are maintained stable within a wide range of temperature, humidity and frequency. Because silicone resins are oxidation resistant, electric arc resistant, radiation resistant, weather proof, water proof, salty fog resistant and damp proof, they are suitable for use as a base material for making insulative paint, or material for molding or laminating into products for industrial use. Most silicone resins are polycondensed into a three-dimensional network structure. These resins contain a large amount of silanol. When these resins are added with inorganic stuffing such as glass fibers, quartz powder, etc., the material thus obtained can be used for molding into a variety of products. However, because a low molecular compound is released when hubbing, air bubbles exists in the molded product. Therefore, these silicone resins are not suitable for molding transparent products. Dimethyl dichloro silane, diphenyl dichloro silane, phenyl trichloro silane or vinyl methyl dichloro silane can used for making a polycondensed silicone resin that contains vinyl with little silanol. When the resin is heated or induced by peroxide, the double chains of vinyl are opened, therefore the resin is polycondensed into a product of three-dimensional network structure. This material does not release a low molecular compound when molding. However, when this resin is hardened, it tends to break due to the occurrence of a stress resulted from high shrinkage.
SUMMARY OF THE INVENTION
The present invention has been accomplished to provide a liquid state non-solvent silicone resin which eliminates the aforesaid drawbacks. The liquid state non-solvent silicone resin can be made into a transparent hard resin of high strength and low shrinkage by means of polycondensation or molding. The transparent hard resin thus obtained does not break, and has high strength and low shrinkage.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A liquid state non-solvent silicone resin made according to the present invention is colorless, transparent, and stable. It is comprised of:
(A) dimethyl poly silioxane
in which, R′: methyl or vinyl; R
2
, R
3
N R
4
, R
5
: methyl, vinyl or phenyl, preferably methyl; “m” and “n”: 0~1000.
(B) organic cyclo siloxane
in which, R
6
and R
7
: methyl, vinyl or phenyl, preferably methyl for R
6
and phenyl for R
7
; “p”: 3, 4 or 5, preferably 4. (C) diphenyl dihydroxy silane
The aforesaid materials (A), (B) and (C) are commonly used materials for organic silicone, and can easily be obtained from the market.
The aforesaid materials (A), (B) and (C) are prepared at 1~5:1:6~1 by mole. Under the presence of anionic polymerization catalyzer through a polycondensation reaction, the molecules of Si-O-Si chain are re-arranged into a balanced status. The anionic polymerization catalyzer can be an alkali metal hydroxide such as KOH, NaOH, LiOH, and their reacted product with silane, such as potassium silane, sodium silane, lithium silane, preferably lithium silane. The amount of the anionic polymerization catalyzer is about 0.005~0.004% by weight of the amount of the silicone resin, preferably about 0.01~0.02%. The polycondensation reaction temperature is within about 140~180° C., preferably within about 150~160° C. The vacuum state is controlled within about 0.0 1MPa~0.095MPa. The reaction time is within 1~3 hours. Reinforcing agent may be added. However, the use of reinforcing agent must match the liquid state non-solvent silicone resin in refractive index. Reinforcing agent can be obtained from white-carbon or MQ resin (silicone resin containing vinyl). White-carbon can be obtained by deposition or gas phase method. White-carbon from hydrophobic gas phase method is preferably accepted. The added amount of reinforcing agent is about 50~120% by weight of the amount of liquid state non-solvent silicone resin, preferably about 80~100% by weight.
REFERENCES:
patent: 2915497 (1959-12-01), Clark
patent: 2975203 (1961-03-01), Bailey
patent: 3269983 (1966-08-01), Holbrook
patent: 5273670 (1993-12-01), Endres et al.
Liu Jian
Sun Yong Zhou
Tsai Chi-Lung
Zhao Peng
Dawson Robert
Robertson Jeffrey B.
Rosenberg , Klein & Lee
Silitek Corporation
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