Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-10-28
2001-04-03
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S261000, C524S588000, C366S301000
Reexamination Certificate
active
06211267
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
FIELD OF THE INVENTION
This invention relates to a method for the continuous production of organopolysiloxane gum solutions. More particularly, the invention relates to a highly productive method for the continuous production of homogeneous solutions of organopolysiloxane gums.
BACKGROUND OF THE INVENTION
Organopolysiloxane gum solutions are widely used in the industrial and commercial spheres as cosmetic bases, release agents, lubricants, and lustrants. These organopolysiloxane gum solutions are typically produced by mixing the starting organopolysiloxane gum and solvent, for example, mineral oil or organopolysiloxane fluid, in a planetary mixer such as a Henschel mixer using a batch process. Batch mixing, however, requires long mixing times in order to dissolve organopolysiloxane gums that have a high degree of polymerization.
To improve the mixing efficiency in such cases, the organopolysiloxane gum or solvent can be divided into portions for introduction into the mixer, but this in turn requires substantial inputs of labor. In addition, when an attempt is made to raise the concentration of the organopolysiloxane gum in the organopolysiloxane solution, a corresponding increase in the viscosity impairs mixing to the point that the quality of the solution may no longer be constant.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a highly productive method for the continuous production of homogeneous solutions of organopolysiloxane gums. The method is characterized by the use of a twin screw compounding extruder having a self-cleaning function. The compounding extruder is provided with at least 2 solvent feed ports downstream from the organopolysiloxane gum feed port, and the internal pressure in the compounding extruder is from 0.00981 to 0.981 MPa.
The method can be used in the continuous production of organopolysiloxane gum solutions that have a viscosity at 25° C. of 10 to 5,000,000 mPa·s, by mixing a solvent with a viscosity at 25° C. of 0.65 to 5,000 mPa·s with an organopolysiloxane gum that has a plasticity at 25° C. of 75 to 200 as measured by the plasticity test in Section 8 of Japanese Industrial Standard K 6249.
These and other features of the invention will become apparent from a consideration of the detailed description.
REFERENCES:
patent: 4534652 (1985-08-01), Stade
patent: 5505591 (1996-04-01), Tynan
patent: 5806975 (1998-09-01), Hosokawa et al.
Higuchi Norikatsu
Matsuda Norio
Mori Hideyuki
Suto Fumitaka
Dawson Robert
DeCesare James L.
Dow Corning Toray Silicone Ltd.
Peng Kuo-Liang
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