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
1997-02-27
1998-09-08
Schofer, Joseph L.
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...
526241, 526243, 526247, 526248, C08L 2712
Patent
active
058046500
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an aqueous dispersion of a vinylidene fluoride copolymer, an aqueous dispersion of a vinylidene fluoride seed polymer and processes for preparation thereof. The above-mentioned aqueous dispersion of a vinylidene fluoride copolymer and aqueous dispersion of a vinylidene fluoride seed polymer are used suitably, for example, for paints for aqueous coating.
BACKGROUND ART
Hitherto fluorine-containing paints being excellent in water resistance and weather resistance have been used as paints for various buildings. However, many of the above-mentioned fluorine-containing paints are of organic solvent type, and fluorine-containing paints of aqueous type have been required from safety and environmental protection points of view. Many proposals have been made as to aqueous dispersion of a fluorine-containing polymer which is a base component of fluorine-containing paints of aqueous type and as to processes for preparation thereof.
For instance, in JP-B-33848/1986 there is described a process for preparing an aqueous dispersion of a fluorine-containing-elastomer made of vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene, which has a particle size of 0.02 .mu.m, in the presence of a fluorine-containing surfactant which has a polymerizable double bond and is represented by However, though there is obtained an aqueous dispersion containing small particles, since the content of the dispersed elastomer is not more than 25% by weight, the obtained aqueous dispersion is insufficient as one for an aqueous paint because a thickening effect by a thickener is not enough. Further there is no description as to stability of the elastomer-dispersed particles when the solid content is increased and also as to the use for an aqueous paint.
JP-B-55441/1992 discloses a process for emulsion-polymerizing an ethylenically unsaturated monomer in the presence of fluorine-containing polymer particles in an aqueous medium, and JP-A-7784/1991 discloses a process for emulsion-polymerizing an ethylenically unsaturated monomer in the presence of vinylidene fluoride copolymer particles in an aqueous medium. Those patent publications describe seed polymerization of an acrylic monomer, but there is no description therein as to controlling of size of seed particles used for seed polymerization and as to use for seed polymerization of seed particles prepared by employing a reactive emulsifying agent. When the seed particles of not more than 50 nm are used, there arise problems that since a viscosity of the obtained aqueous dispersion becomes high, the aqueous dispersion having a high solid content cannot be obtained and that coagulation occurs when the aqueous dispersion is used under high shearing force.
Also JP-B-4396/1975 discloses a process for preparing an acrylic emulsion system wherein a microemulsion having an average particle size of not more than 50 nm is prepared by copolymerizing with acrylic acid at the copolymerization and then neutralizing the produced emulsion with ammonia. In the polymerization of fluorine-containing olefin, particularly vinylidene fluoride monomer, if a non-fluorine-containing carboxylic acid monomer such as acrylic acid is present, the polymerization is inhibited remarkably. Therefore, no polymerization of a fluorine-containing olefin has been made actually in such a system.
In JP-B-17858/1974, there is disclosed a process for copolymerizing a linear saturated fluorine-containing elastic resin with a fluorine-containing vinyl compound having --COOH group on its side chain in order to introduce crosslinkable groups into the elastic resin, but there is no description as to an aqueous dispersion, controlling of particle size of particles in the aqueous dispersion and an aqueous paint.
In "Kobunshi Ronbunshu" Vol. 36, No. 11, pp. 729-737 (1979), there is disclosed that when a large amount of various surfactants is used in emulsion polymerization, particles of a polymer become smaller, and that even if a mixture of an anionic surfactant and a nonionic surfacta
REFERENCES:
patent: 5608022 (1997-03-01), Nakayama et al.
Answer 7 of 11, 1985: 114497, Showa JP83-70753, 83, 04, 20--In House Computer Searched-Abstract pp. 23-25.
Araki Takayuki
Imoto Katsuhiko
Iwakiri Ryuzi
Kondo Masahiro
Shimizu Yoshiki
Daikin Industries Ltd.
Sarofim N.
Schofer Joseph L.
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