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
2002-04-05
2004-04-13
Wu, David W. (Department: 1713)
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...
C524S500000, C524S545000, C252S511000
Reexamination Certificate
active
06720381
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aqueous curing composition of a fluoroelastomer and an article coated with a fluoroelastomer. In particular, the present invention relates an aqueous curing composition of a fluoroelastomer containing a specific surfactant, and an article coated with a coating film formed from such a composition.
BACKGROUND ART
Fluoroelastomer coating compositions are widely used as industrial materials with being coated on or impregnated in fabric, fibers, metals, plastics, rubbers and other various substrates by making use of good heat resistance, weather resistance, oil resistance, solvent resistance and chemical resistance of the fluoroelastomers. In these years, particularly, aqueous coating compositions are increasingly used since they are friendly to the environments.
The conventional aqueous composition of fluoroelastomers usually contain a polyoxyethylene alkylphenyl ether of the formula:
R—Ph—O(CH
2
CH
2
O)
n
H
wherein R is an alkyl group, Ph is a phenylene group and n is an integer of at, least 1 as a surfactant.
However, this type of the surfactant tends to leave decomposition residues in the coating film of the fluoroelastomer after baking, since it has a relatively high decomposition temperature, and thus it may deteriorate the above-described inherent characteristics of the fluoroelastomer. When such a surfactant is used in a coating film covering the surface of a roll used in office automation equipment (e.g. copying machines, printers, etc.), the coating film has insufficient durability.
This type of the surfactant is not preferable from the viewpoint of environmental protection, since it is prepared from a raw material which is suspected to have internal secretion disturbing functions.
DISCLOSURE OF THE INVENTION
One object of the present invention is to provide an aqueous curing composition of a fluoroelastomer, which can make use of the inherent characteristics of the fluoroelastomer coating.
Another object of the present invention is to provide an article coated with a fluoroelastomer, which can solve the above drawbacks of the articles coated with a film formed from the conventional aqueous curing composition of a fluoroelastomer, in particular, the rolls of the office automation equipment.
The above objects can be achieved by an aqueous curing composition of a fluoroelastomer comprising a fluoroelastomer, a curing agent, and a surfactant with which an amount of decomposition residues is 0.3% by weight or less after being baked at 300° C. for 30 minutes, and an article at least a part of the surface of which is coated with a coating film formed from such an aqueous curing composition of a fluoroelastomer.
Hereinafter, the components contained in the composition of the present invention will be explained.
(A) Fluoroelastomer
The fluoroelastomer is usually supplied in the form of an aqueous dispersion. The aqueous dispersion of the fluoroelastomer is prepared by dispersing a fluorine-containing elastomeric copolymer (fluoroelastomer) in water at a concentration of 10 to 75% by weight in the presence of a surfactant.
The fluorine-containing elastomeric copolymer is a fluorine-containing copolymer containing repeating units represented by —CH
2
— in the backbones. One typical example of such a copolymer is a fluorine-containing elastic copolymer comprising vinylidene fluoride. Examples of such copolymer are copolymers comprising at least one repeating unit selected from the group consisting of —CF
2
—CH
2
—, —CH
2
—CH
2
— and —CH
2
—CH(CH
3
)—, and at least one repeating unit selected from the group consisting of —CF
2
—CF(CF
3
)—, —CF
2
—CF
2
— and —CF
2
—CF(ORf)— in which Rf is a fluoroalkyl group having 1 to 6 carbon atoms.
Specific examples of such copolymers include vinylidene fluoride-hexafluoropropylene copolymers, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymers, ethylene-hexafluoropropylene copolymers, tetrafluoroethylene-propylene copolymers, etc. Among them, the vinylidene fluoride copolymers are preferable from the viewpoint of their crosslinkability.
Such fluorine-containing elastomeric copolymers are commercially distributed under the trade name of “DAIEL®” (available from Daikin Industries, Ltd.), “VITONE FLOME®” (available from E. I. duPont), “AFLAS®” (available from ASAHI GLASS Co., Ltd.), etc.
The amount of the fluoroelastomer (solid component) to be contained in the composition of the present invention is from 1 to 500 parts by weight, preferably from 5 to 300 parts by weight, more preferably from 10 to 150 parts by weight, per 100 parts by weight of water.
(B) Curing Agent and Curing Accelerator
The curing agent to be contained in the aqueous curing composition of the present invention may be either a conventional diamine curing agent or a conventional polyol curing agent.
Examples of the diamine curing agent include an aminosilane compound of the formula:
wherein R
1
is a methyl group or an ethyl group, Z is a single bond, —C
2
H
4
NH—, —CONH— or —C
2
H
4
NH—C
2
H
4
NH—NH—, and y is 2 or 3, or its partially or completely hydrolyzed products, and a polyaminosiloxane compound of the formula:
wherein R
2
, R
3
and R
4
represent independently of each other a hydrogen atom, an alkyl group having 1 to 6 carbon atom, an amino group, a polyamino group, or an alkyl group having 1 to 6 carbon group at least one hydrogen atom of which is replaced with an amino group or a polyamino group provided that the amino groups are present in at least two of R
2
, R
3
and R
4
or a polyamino group is present in at least one of R
2
, R
3
and R
4
.
The polyol curing agent used in the present invention may be a compound or a polymer having at least two hydroxyl groups, in particular, phenolic hydroxyl groups in a molecule, and having a curing capability. Specific examples of polyol curing agents include salts of basic compounds with phenol compounds such as
and polyphenols represented by the formula:
wherein Y is a hydrogen atom, a halogen atom, R
5
, —CH
2
OR
5
or —OR
5
, Z is —CH
2
— or —CH
2
OCH
2
—, R
5
is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 100.
Examples of the basic compounds include ammonium salts, tertiary amines, phosphonium salts, alkali metals and alkaline earth metals.
Specific examples of ammonium salts include trimethylbenzylammonium, triethylbenzylammonium, dimethyldecylbenzylammonium, triethylbenzylammonium, myristylbenzyldimethylammonium, dodecyltrimethylammonium, dimethyltetradecylbenzylammonium, trimethyltetradecylammonium, coconuttrimethylammonium, stearyltrimethylammonium, distearyldimethylammonium, tetrabutylammonium, 1,4-phenylenedimethylenebistrimethylammonium, 1,4-phenylenedimethylenebistriethylammonium, ethylenebistriethylammonium, etc.
Specific examples of tertiary amines include 1,8-diaza-bicyclo[5.4.0]-undecene-7, 8-methyl-1,8-diaza-bicyclo[5.4.0]-undecene-7, 8-propyl-1,8-diazabicyclo[5.4.0]-undecene-7, 8-dodecyl-1,8-diaza-bicyclo[5.4.0]-undecene-7, 8-eicocyl-1,8-diaza-bicyclo[5.4.0]-undecene-7, 8-tetracocyl-1,8-diaza-bicyclo[5.4.0]-undecene-7, 8-benzyl-1,8-diaza-bicyclo[5.4.0]-undecene-7, 8-phenethyl-1,8-diazabicyclo-[5.4.0]-undecene-7, 8-(3-phenylpropyl)-1,8-diaza-bicyclo[5.4.0]-undecene-7, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, triisobutylamine, methyldiethylamine, dimethylethylamine, dimethyl-n-propylamine, dimethyl-n-butylamine, dimethylisobutylamine, dimethylisopropylamine, dimethyl-sec.-butylamine, dimethyl-tert.-butylamine, triallylamine, diallylmethylamine, allyldimethylamine, benzyldimethylamine, benzyldiethylamine, N-allylpiperidine, N-ethylpiperidine, N-butylpiperidine, N-methylpyrolidine, N-cyclohexylpyrolidine, N-n-butylpyrolidine, N-ethylpyrolidine, N-benzylpyrolidine, 2,4,6-trimethylpyridine, etc.
Specific examples of phosphonium salts include benzyltriphenylphosphonium, methyltriphenylphosphonium, 2,4-dichlorobenzyltriphenylphosphonium, 4-methylbenzyltriphenylphosphonium, 4-chlorobenzyltriphe
Nakatani Yasukazu
Ogita Koichiro
Terasaka Kiyotaro
Tomihashi Nobuyuki
Birch & Stewart Kolasch & Birch, LLP
Daikin Industries Ltd.
Hu Henry
LandOfFree
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