Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Patent
1995-07-16
1996-09-10
Szekely, Peter A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
528496, 524565, 524571, C08J 302, C08L 904
Patent
active
055547265
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method for producing hydrogenated NBR (nitrile-butadiene rubber) latex having small particle size and excellent standing stability. The hydrogenated NBR latex according to this invention gives high heat resistance, high oil resistance and high aging resistance to a material when a coating film is formed on it. As the result it is highly advantageous to surface treatment agent for textile and coating agent for plastics, films or sheets.
PRIOR ART
As a production technology for hydrogenated NBR latex, there has been known the method which comprises dissolving a hydrogenated NBR in an organic solvent such as toluene, dichloroethane, mixing the resulting organic solution with an aqueous solution of an emulsifying agent, agitating the mixture using a homomixer or the like, and removing the organic solvent (Japanese Kokai Publication Sho-62-201945).
However, since halogenated hydrocarbon solvents such as dichloroethane are harmful to human body, rigorous control is in force over their use in view of the enviromnental pollutions. It is, therefore, not desirable for industrial practice to employ the technology which involves the use of such solvents in large quantities.
Meanwhile, there is an ardent demand for improving the fundamental performance of common rubber latex through diminution of latex particle size and enhancement of the stability when the latex stands quietly (hereinafter refers as `standing stability`). However, the latex particles produced by the known technology inclusive of the above-mentioned process are not as small as desired and there also is the problem that the standing stability obtained by conventional method is not commensurate with the amount of the emulsifier added.
To overcome the above disadvantages, the present inventors previously discovered that a hydrogenated NBR latex with reduced particle size and improved standing stability could be provided by the process which comprises mixing an organic solvent solution of a hydrogenated NBR and a fatty acid with an aqueous solution of an alkaline metal hydroxide and a dialkylsulfosuccinic acid, then emulsifying the mixture, and removing the organic solvent. They accordingly filed a patent application (Japanese Patent Application Hei-5-228238).
However, the above invention has the problem that because of the restriction of emulsifier which can be used, the use of the resulting hydrogenated NBR latex are also limited. Therefore, a demand for an industrial production technology with no limitation of emulsifier as well as short emulsifying time still remains.
DESCRIPTION OF THE INVENTION
Under these circumstances, the object of this invention is to provide a method for producing a hydrogenated NBR latex with sufficiently reduced latex particle size and excellent standing stability without using any harmful solvent or restricting the kind of usable emulsifier.
The gist of this invention resides in a method for producing a hydrogenated NBR latex comprising mixing an organic layer in which a hydrogenated NBR is dissolved in organic solvent with an aqueous layer in which an emulsifier is dissolved in water, then agitating the mixture, and removing the organic solvent by distillation, characterized in that said emulsification is performed in the presence of an alcohol.
This invention is now described in detail.
The hydrogenated NBR that can be used in this invention includes but is not limited to unsaturated nitrile-conjugated diene copolymer rubber whose conjugated diene unit has been hydrogenated, unsaturated nitrile-conjugated diene-ethylenically unsaturated monomer terpolymer rubber whose conjugated diene unit has been hydrogenated or the like. These copolymer rubbers can be obtained by the conventional polymerization and hydrogenation processes.
Specific examples of such hydrogenated NBR are hydrogenated butadiene-acrylonitrile copolymer rubber, hydrogenated isoprene-butadiene-acrylonitrile copolymer rubber, hydrogenated butadiene-methyl methacrylate-acrylonitrile copolymer, hydrogenated butad
REFERENCES:
patent: 3558576 (1971-01-01), Weller
patent: 3923738 (1975-12-01), Van Sorge
Araki Eiichi
Kamada Mari
Matsukawa Taiji
Sugihara Norihiro
Sumitomo Seika Chemicals Co. Ltd.
Szekely Peter A.
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