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...
Reexamination Certificate
1998-08-25
2001-01-16
Sanders, Kriellion A. (Department: 1714)
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...
Reexamination Certificate
active
06174955
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a water-based fluorine-containing paint which is curable at ambient temperature.
Fluororesins are generally excellent in chemical resistance, weather resistance and heat resistance, and in view of these favorable properties the use of fluororesin based paints is increasing in various fields.
As a fluororesin suitable for solvent-thinned paints, U.S. Pat. No. 4,631,326 discloses a fluorine-containing copolymer comprising chlorotrifluoroethylene, a vinyl or isopropenyl ester of fatty acid and a hydroxyl-containing allyl ether. This allyl ether provides a functional group to the copolymer for curing the copolymer. Japanese Patent Unexamined Publication No. 57-34107 discloses a fluorine-containing copolymer which is curable at ambient temperature and comprises a fluoroolefin, cyclohexylvinyl ether, an alkylvinyl ether, and an hydroxyalkylvinyl ether. This hydroxylalkylvinyl ether provides a functional group to the copolymer for curing the copolymer.
Fluororesin-containing solvent-thinned paints are widely used as weather resistant paints in the fields of architecture, automobile and chemical engineering. Furthermore, in view of the environmental protection, fluororesin-containing water-based paints, powder paints, and high-solid paints have been developed, too. Each fluororesin for these paints comprises a fluorocarbon as a main component, such as chlorotrifluoroethylene, tetrafluoroethylene or vinylidene fluoride, and a copolymerizing hydrocarbon monomer such as vinyl ester or vinyl ether, which is added for the purpose of increasing solubility of the fluororesin. it has been difficult to provide the above-mentioned fluororesin-containing water-based paitt with a functional group for forming a cross-linking structure Therefore, a so-called lacquer-type water-based paint in the form of emulsion of a high-molecular compound prepared by emulsion polymerization was used in many cases of the coating step. In view of this, a hardener for forming a cross-linking structure at ambient temperature was developed, such as an oxazoline compound or a self-emulsifiable polyisocyanate. The hardening action by the polyisocyanate, however, tends to terminate due to the reaction of isocyanate group with water (dispersion medium). Thus, it has been necessary to add the polyisocyanate to vehicle, immediately before the coating step, in view of pot life of the paint. However, a conventional self-emulsifiable polyisocyanate is insufficient in dispersibility in water. Thus, it has been difficult, particularly in a coating site, to t uniformly finely disperse the polyisocyanate in water. With this, a coated film becomes insufficient in water resistance, weather resistance, stain resistance and the like.
In contrast to the above-mentioned two-package type paints, there have been proposed one-package type paints in the field of water-based acrylic-ester paints. For example, Japanese Patent Unexamined Publication No. 57-3850 discloses a water-based disperse system containing, as a disperse phase, carbonyl-containing copolymer particles. Japanese Patent Unexamined Publication No. 4-81447 discloses a water-based emulsion composition which is a mixture of a self-emulsifiable polyurethane and a water-based acrylic-resin emulsion which is cross-linkable at ambient temperature.
Similar to the above-mentioned acrylic ester paint, there has been a recent demand for a water-based fluorine-containing paint which is one-package type and capable of providing a coated film superior in water resistance, weather resistance, stain resistance and the like.
SUMMARY OF THE INVENTION
It is therefore an object of the first aspect of the present invention to provide a water-based fluorine-containing paint containing a hardener well dispersed in the paint.
It is therefore an object of the second aspect of the present invention to provide a water-based fluorine-containing paint which is chemically stable at ambient temperature, even after the hardener is added thereto, and thus usable as a one-package type paint.
According to a first aspect of the present invention, there is provided a first water-based fluorine-containing paint comprising:
a water-based emulsion containing water as a dispersion medium and a fluorine-containing copolymer as a disperse phase, said fluorine-containing copolymer being prepared by copolymerizing 30-65 mol % of a fluoroolefin, 14-69 mol % of a copolymerizable vinyl-containing compound, and 1-30 mol % of a first compound which is at least one of a hydroxyl-containing compound and a polymerizable carboxyl-containing compound; and
1-50 parts by weight of a hardener per 100 parts by weight of said fluorine-containing copolymer, said hardener being prepared by mixing a self-emulsifiable polyisocyanate with 0.01-1 part by weight, per part by weight of said polyisocyanate, of a second compound containing in the molecule an oxygthylene unit and an alkoxysilyl group.
According to the first aspect of the present invention, the inventors have unexpectedly found that, when the second compound is mixed with a self-emulsifiable polyisocyanate, the polyisocyanate becomes well dispersed in water contained in the first paint. That is, the hardener which is a mixture of the polyisocyanate and the second compound is well dispersed in the paint. With this, a coated film prepared by applying the first paint becomes homogeneous and exhibits a good water resistance, a good stain resistance and a good weather resistance, which are directly derived from a fluororesin contained in the first paint. The first paint can be easily prepared by mixing together the water-based emulsion and the hardener at a coating site, because the hardener is well mixed with and well dispersed in the emulsion.
According to a second aspect of the present invention, there is provided a second water-based fluorine-containing paint comprising:
a water-based emulsion containing water as a dispersion medium and a fluorine-containing copolymer as a disperse phase, said fluorine-containing copolymer being prepared by emulsion polymerization of 30-65 mol % of a fluoroolefin, 0.1-20 mol % of a polymerizable unsaturated carboxylic acid represented by the general formula (1), 1-30 mol % of a polymerizable allyl compound represented by the general formula (2), and 20-65 mol % of a first compound which is one of a vinyl ester and a vinyl ether; and
a hardener which is a second compound containing in the molecule at least two hydrazino groups,
CH
2
═CH—(CH
2
)
n
—COOH (1)
where n is an integer from 7 to 9,
where R represents —(AO)
n
— in which A is an alkylene group having a carbon atom number from 2 to 4, and n is an integer from 0 to 20.
According to the second aspect of the present invention, the inventors unexpectedly found that the second paint does not cure until its use and thus can be stably stored until its use, even after the above-mentioned special hardener has been mixed with the water-based emulsion. Therefore, the second paint can be used as an one-package paint. After the second paint is applied to a substrate to form a coated film thereon, cross-linking of the second paint proceeds at ambient temperature. The thus formed coated film is superior in water resistance, weather resistance, stain resistance and the like. Furthermore, the second paint does not contain an organic solvent. This is an advantage from a view point of environment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, a water-based fluorine-containing paint according to the first and second aspects of the present invention will be described in detail.
According to the first and second aspects of the present invention, there is used 30-65 mol % of a fluoroolefin as a monomer for preparing the fluorine-containing copolymer, based on the total number of moles of all the monomers. The mol percentages of the other monomers are also defined in the same manner as this fluoroolefin. Examples of the fluoroolefin are chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropene, hexafluoroisobutene
Hirashima Yoshi
Kobayashi Satoru
Maeda Kazuhiko
Tsutsumi Kentaro
Central Glass Company Limited
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Sanders Kriellion A.
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