Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1997-03-28
2000-10-10
Reddick, Judy M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524819, 524823, 524832, 524833, 524845, C08L 3100
Patent
active
061302880
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a copolymer latex and a process for producing the same.
BACKGROUND TECHNOLOGY
Copolymer latices have been used in various fields such as paper processing, paints, fibers and adhesives. From the standpoint of resource-saving and energy-saving advocated in recent years, improvements in drying efficiency and productivity of these copolymer latices and reduction in their transportation costs are required, and as a means to meet such requirements, it is necessary to raise concentration of copolymer latices.
As a method for obtaining a high solids-content copolymer latex, it is known to mix a large particle size latex with a small particle size latex. Whereas, such a method necessitates production facilities for two kinds of copolymer latices and facilities for mixing them, which provides a serious drawback to its production. Furthermore, when the latices to be mixed exhibit poor compatibility, the mixture shows low storage stability, and eventually is inferior in its qualities.
Whereas, there is known a process for producing directly through polymerization a copolymer latex containing two groups of particles, each group having different particle sizes (Japanese Patent Publication, [Kokoku] No. Hei 5-31582). This method, however, has problems in productivity, because it requires condensing operations after the polymerization reaction to provide a high solids-content latex and the condensation consumes many hours. Solids content of such copolymer latices obtained upon condensation is about 60 weight percent, and latices of higher solids-content are in demand. Furthermore, because the copolymer latices obtained through this method have small average particle size, the condensation for providing a still higher solids-content latex causes a problem of viscosity rise.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a copolymer latex having a low viscosity and a high solids-content of at least 67% by weight, and to provide a process for obtaining a high solids-content copolymer latex through a polymerization step only, without additional operations such as condensation after termination of the polymerization reaction.
Such objects of the present invention can be accomplished by a copolymer latex with a total solids-content of at least 67% by weight, characterized by a viscosity of 2,000 centipoises or less as measured with a BM viscometer under the conditions of total solids content of 67% by weight and at room temperature.
The object of the present invention is also accomplished by a copolymer latex, characterized in that said copolymer is obtained through polymerization of monomers composed of 0.1-10% by weight of an ethylenically unsaturated carboxylic acid monomer or monomers and 90-99.9% by weight of other monomer or monomers copolymerizable therewith, in that said copolymer latex has a volume average particle size of all the particles ranging 500-1,000 nm, in that said copolymer latex comprises two groups of a smaller size particle group (a) consisting of particles whose particle size ranges 50-300 nm and a larger size particle group (b) consisting of particles whose particle size ranges 400-1200 nm, in that the total weight of the particles constituting group (a) and those constituting group (b) is at least 80% of the weight of all the particles, and in that the volumetric ratio of the group (a) particles to the group (b) particles is 10:90-40:60.
Furthermore, the object of the present invention is accomplished by a process for producing the above copolymer latex, which is characterized by continuous addition of, into an aqueous solution of a polymerization initiator containing no emulsifier, a monomeric component composed of 0.1-10% by weight of an ethylenically unsaturated carboxylic acid monomer and 90-99.9% by weight of another monomer copolymerizable therewith, and 0.1-1.5 parts by weight of an emulsifier per 100 parts by weight of the total monomeric component to be used for obtaining the copolymer latex, and further characteriz
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Inoue Toshihiro
Nakano Yasuhiro
Nippon Zeon Co Ltd
Reddick Judy M.
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