Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1993-04-20
1997-02-18
Mulcahy, Peter D.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524284, 524386, 524387, 524388, 524544, 524545, 524546, C08K 517
Patent
active
056042833
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a fluororubber coating composition. In particular, the present invention relates to a fluororubber coating composition which has a long pot life and provides a film with a uniform thickness.
DESCRIPTION OF THE PRIOR ART
Since a conventional fluororubber coating composition suffers from gellation within 24 hours after the addition of a crosslinking agent, its pot life is short and it has some troubles in storage and application. If the composition is not gelled, crosslinking of the fluororubber will increase a viscosity of the composition, so that a coated film has an uneven thickness depending on a coating manner (See Industrial Material (KOGYO ZAIRYO), Vol. 26, No. 12 (Dec. 1978) 46-49).
SUMMARY OF THE INVENTION
One object of the present invention is to provide a fluororubber coating composition having a long pot life.
Another object of the present invention is to provide a fluororubber coating composition which provides a film having a uniform thickness when coated.
According to the present invention, there is provided a fluororubber coating composition comprising a fluororubber, a liquid medium, a coupling agent, a crosslinking agent and a carboxylic acid.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing the change of the viscosity with time of the compositions prepared in Example 1 and Comparative Example 1,
FIG. 2 is a graph showing the change of the viscosity with time of the composition prepared in Example 2 containing various concentrations of formic acid, and
FIG. 3 is a graph showing the change of the viscosity with time of the composition prepared in Example 3 containing various concentrations of acetic acid.
DETAILED DESCRIPTION OF THE INVENTION
As the fluororubber contained in the coating composition of the present invention, a highly fluorinated elastomeric copolymer may be used. A preferred example of the fluororubber is an elastomeric copolymer comprising 40 to 85% of vinylidene fluoride and at least one other fluorine-containing ethylenically unsaturated monomer copolymerizable with vinylidene fluoride.
As the fluororubber, one containing iodine atoms in the polymer chain may be used. An example of the fluororubber containing iodine atoms is an elastomeric copolymer comprising 40 to 85% of vinylidene fluoride and at least one other fluorine-containing ethylenically unsaturated monomer copolymerizable with vinylidene fluoride and having 0.001 to 10% by weight, preferably 0.01 to 5% by weight of iodine atoms which are bonded to terminals of polymer chains (see Japanese Patent Kokai Publication No. 125491/1978 and U.S. Pat. No. 4,243,770).
Typical examples of the other fluorine-containing ethylenically unsaturated monomer copolymerizable with vinylidene fluoride are hexafluoropropylene, pentafluoropropylene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether) and the like.
Preferred examples of the fluororubber are vinylidene fluoride/hexafluoropropylene copolymers and vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene terpolymers.
Examples of other fluororubber which may be used according to the present invention are tetrafluoroethylene/propylene copolymer, ethylene/hexafluoropropylene copolymer, tetrafluoroethylene/fluorovinyl ether copolymer, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene/fluorovinyl ether copolymer, vinylidene fluoride/hexafluoropropylene copolymer and the like.
To the fluororubber coating composition, a fluororesin may be added, if desired. Examples of the fluororesin are polytetrafluoroethylene, a copolymer of tetrafluoroethylene with at least other ethylenically unsaturated monomer (e.g. olefins such as ethylene and propylene; halogenated olefins such as hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene and vinyl fluoride; perfluoro(alkyl vinyl ether), etc.), polychlorotrifluoroethylene, polyvinylidene fluoride, and the like. Among the
REFERENCES:
patent: 4011361 (1977-03-01), Vassiliou et al.
patent: 4243770 (1981-01-01), Tatemoto et al.
patent: 4323603 (1982-04-01), Close
patent: 4845007 (1989-04-01), Hyosu et al.
Partial Translation of Industrial Material ("Kogyo Zairyo") (1978) 26(12):46-49.
Mizuno Toshio
Tanaka Hiroyuki
Wada Nobuyoshi
Daikin Industries Ltd.
Mulcahy Peter D.
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