Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2003-01-27
2004-10-19
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S318600, C526S329000, C526S329400, C526S329600, C526S329700, C524S458000, C525S276000
Reexamination Certificate
active
06806333
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an aqueous dispersion of a fluorocopolymer.
BACKGROUND ART
Heretofore, a vinylidene fluoride type resin is widely used as a baking-type coating material, since it is excellent in weather resistance, heat resistance and chemical resistance and it is soluble in a solvent at a high temperature. As such a vinylidene fluoride type resin, a homopolymer of vinylidene fluoride or a copolymer of vinylidene fluoride with a fluoroolefin (such as tetrafluoroethylene, hexafluoropropylene or chlorotrifluoroethylene), has been proposed.
Further, it is known that a copolymer of a fluoroolefin with cyclohexyl vinyl ether and other various monomers, is soluble in an organic solvent even at room temperature, and when used as a coating material, it gives a coating film which is transparent and has high gloss and which further has excellent characteristics such as high weather resistance, water and oil repellency, stain resistance and non-tackiness (JP-A-55-44083), and its use is increasing in the field of weather resistant coating materials for interior and exterior of e.g. buildings.
On the other hand, in recent years, restriction on use of organic solvents has been increasing from the viewpoint of the environmental protection against e.g. air pollution, and social demand for an aqueous coating material or a powder coating material employing no organic solvent, has increased.
Also with respect to a fluororesin, from such a viewpoint, an aqueous dispersion type has been studied, and with respect to a vinylidene fluoride type resin, a method for emulsion polymerization of an acrylic monomer in the presence of vinylidene fluoride resin particles, has been proposed (JP-A-3-8884, JP-A-4-325509).
Further, also with respect to a copolymer of a fluoroolefin with cyclohexyl vinyl ether and other various monomers, an aqueous dispersion type has been studied, and it has been reported that such can be prepared by emulsion polymerization (JP-A-57-34107, JP-A-61-231044). Further, an aqueous dispersion has been proposed in which a fluorine-containing copolymer having, as an essential constituting component, polymerized units based on a macro monomer having a hydrophilic moiety, is dispersed in water (JP-A-2-225550). This aqueous dispersion is excellent in the film-forming properties and presents a coating film having good mechanical strength, and it is reported further that it can be produced even without using an emulsifier or a hydrophilic organic solvent.
However, with an aqueous dispersion of a vinylidene fluoride type resin, the stability of the aqueous dispersion is not necessarily good, and the transparency of the coating film is poor due to the crystallizability of the resin, and if the crystallizability is lowered in an attempt to improve the transparency, there has been a problem that the glass transition temperature of the coating film tends to be so low that the stain resistance tends to deteriorate. By seed polymerization of an acrylic monomer, there has been some improvement over the problems, but such has not been adequate. Further, there has been a problem also with respect to the film-forming properties.
Furthermore, if the vinylidene fluoride type resin is composed solely of a copolymer with a fluoroolefin, the cost tends to be high. A copolymer of a fluoroolefin with cyclohexyl vinyl ether and other various monomers is practically useful as the transparency of the coating film and the film-forming properties are good, but since a liquid monomer is employed, the coating film tends to be slightly tacky, and a further improvement in this respect, has been desired.
The present inventors have proposed that the above problems can be basically solved by an aqueous dispersion of a composite of a fluorocopolymer comprising a fluoroolefin and ethylene or propylene and a (meth)acrylate type copolymer (such as JP-A-12-128934). However, the compatibility of a fluorocopolymer and a (meth)acrylate type copolymer is not necessarily sufficient, and whitening of a coating film may take place in some cases under a high temperature baking condition at a level of 200° C. depending upon the purpose of use.
The present invention is to solve the above-described problems of the prior art and has an object to present an aqueous dispersion of a fluorocopolymer which is excellent in stability and film-forming properties, and which gives a coating film of the fluorocopolymer excellent in mechanical strength, and having improved weather resistance, water resistance, stain resistance and transparency.
DISCLOSURE OF THE INVENTION
The present invention has been made to solve the above problems, and according to the present invention, the following inventions are presented.
(1) An aqueous dispersion of a fluorocopolymer, which is obtained by emulsion polymerization, in the presence of 100 parts by mass of particles of a fluorocopolymer (A) comprising polymerized units based on (a) a fluoroolefin, polymerized units based on (b) propylene, polymerized units based on (c) ethylene and/or polymerized units based on (d) butylene, and polymerized units based on (e) a vinyl monomer having a reactive group, of from 5 to 200 parts by mass of a radical polymerizable monomer mixture comprising (g) a (meth)acrylic acid capable of forming a bond by reaction with the reactive group of the above (e) and/or (h) an alkyl(meth) acrylate having a carbon number of from 1 to 18 in the alkyl group, and having a reactive group capable of forming a bond by reaction with the reactive group of the above (e).
(2) An aqueous dispersion of a fluorocopolymer, which is obtained by mixing an aqueous dispersion of 100 parts by mass of a fluorocopolymer (A) comprising polymerized units based on (a) a fluoroolefin, polymerized units based on (b) propylene, polymerized units based on (c) ethylene and/or polymerized units based on (d) butylene, and polymerized units based on (e) a vinyl monomer having a reactive group, with an aqueous dispersion of from 5 to 200 parts by mass of a copolymer (B) obtained by emulsion polymerization of a radical polymerizable monomer mixture comprising (g) (meth)acrylic acid capable of forming a bond by reaction with the reactive group of the above (e) and/or (h) an alkyl (meth)acrylate having a carbon number of from 1 to 18 in the alkyl group, and having a reactive group capable of forming a bond by reaction with the reactive group of the above (e).
The aqueous dispersion of a fluorocopolymer of the above (1) is an aqueous dispersion of a fluorocopolymer by a “composite treatment” as described hereinafter, and the aqueous dispersion of the above (2) is an aqueous dispersion of a fluorocopolymer by a “mixing treatment”.
BEST MODE FOR CARRYING OUT THE INVENTION
Now, preferred mode for carrying out the invention will be explained in detail.
In the present invention, a fluorocopolymer (A) comprising polymerized units based on (a) a fluoroolefin, polymerized units based on (b) propylene, polymerized units based on (c) ethylene and/or polymerized units based on (d) butylene, and polymerized units based on (e) a vinyl monomer having a reactive group, is used as a copolymer to be the base in a treatment. The copolymer to be the base may further contain polymerized units based on (f) another copolymerizable monomer.
The fluorocopolymer (A) to be the base is preferably composed of the following compositional proportions of the polymerized units based on the following monomers (hereinafter represented by the monomer names). Namely,
(a) fluoroolefin
20 to 80 mol %
(b) propylene
2 to 70 mol %
(c) ethylene
(5) to (70) mol %
(d) butylene
(5) to (70) mol %
(e) vinyl monomer having a reactive group
0.5 to 20 mol %
(f) another copolymerizable monomer
0 to 50 mol %.
The compositional proportions are further preferably:
(a) fluoroolefin
35 to 65 mol %
(b) propylene
4 to 55 mol %
(c) ethylene
(8) to (60) mol %
(d) butylene
(8) to (60) mol %
(e) vinyl monomer having a reactive group
0.5 to 10 mol %
(f) another copolymerizable monomer
0 to 30 mol %.
Most preferably:
(a) fluoroolefin
40 to 60 mol %
(b) pr
Ichikuni Naomi
Ishida Toru
Asahi Glass Company Limited
Hu Henry S.
Wu David W.
LandOfFree
Aqueous dispersion of fluorocopolymer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aqueous dispersion of fluorocopolymer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aqueous dispersion of fluorocopolymer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3280444