Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2000-08-25
2004-07-20
Wilson, D. R. (Department: 1713)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S379000, C428S421000, C428S906000, C524S456000
Reexamination Certificate
active
06764763
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aqueous fluoroelastomer curable composition and a coated article. In particular, the present invention relates to an aqueous fluoroelastomer curable composition comprising a fluorine-containing copolymer and a specific polyol curing agent, and an article having a coating film formed from such a composition.
BACKGROUND ART
A method for curing an aqueous fluoroelastomer coating composition with a polyamine curing agent is known (see JP-B-58-53671 corresponding to U.S. Pat. No. 4,339,553). In general, the coating film formed by this method has good mechanical properties, but low sealing properties. In addition, when such a coating film is used to coat the surface of a roll used in office automation (OA) equipment (e.g. copying machines, printers, etc.), it has drawbacks such as insufficient elasticity, heat resistance, and so on. When the polyamine curing agent is added to a fluoroelastomer curable composition, for example, a coating composition, its pot life is shortened because of gelling, etc. Accordingly, two or more fluid type compositions are practically supplied, but no practically usable one-fluid type composition is available.
When a fluoroelastomer is cured with a polyol curing agent, it is possible to prepare one-fluid type fluoroelastomer coating compositions containing organic solvents (see PCT/JP97/02853). However, in these years, the VOC regulation and the like become severer and severer, and thus environment friendly aqueous coating compositions are desired. However, one-fluid type aqueous fluoroelastomer coating compositions in the form of an aqueous dispersion containing no organic solvent are not known.
DISCLOSURE OF THE INVENTION
One object of the present invention is to provide a one-fluid type aqueous fluoroelastomer curable composition, which can be formulated as an aqueous dispersion, form a cured film having high strength at a relatively low temperature in a short time, and has a long pot life.
Another object of the present invention is to provide a coated article, which does not suffer from the drawbacks of coated articles having a coating film formed from a conventional aqueous fluoroelastomer coating composition, in particular, rolls for OA equipment.
To achieve these and other objects, the present invention provides an aqueous fluoroelastomer curable composition comprising an aqueous fluoroelastomer dispersion and a basic polyol curing agent, and a coated article at least a part of the surface of which is coated with a coating layer formed from such a composition.
EMBODIMENTS TO CARRY OUT THE INVENTION
Now, the components contained in the composition of the Present invention will be explained.
(A) Aqueous Dispersion of Fluoroelastomer
The aqueous dispersion of a fluoroelastomer is prepared by dispersing a fluorine-containing elastic copolymer in water in a concentration of 10 to 75 wt. % in the presence of a surfactant such as polyoxyethylene, an alkyl phenyl ether, an alkylsulfonate salt, etc.
The fluorine-containing elastic copolymer is a fluorine-containing copolymer comprising repeating units represented by the formula: —CH
2
— in the backbone. Typical examples of such a copolymer include fluorine-containing elastic copolymers, comprising vinylidene fluoride, and specific examples of such copolymers are those comprising the following repeating units in the backbone:
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
—(ORf)CF— 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. Such fluorine-containing elastic copolyers are commercially sold under the trade names of “DAIEL®” (by Daikin Industries Ltd.), “BAITON FLOAM®” (by E. I DuPont), “AFLAS®” (by ASAHI GLASS Co., Ltd.), and so on. Among them, the vinylidene fluoride base copolymers are preferable in view of the crosslinkability.
(B) Basic Polyol Curing Agent
Herein, the basic polyol curing agent means a compound or a polymeric compound having at least two hydroxyl groups, in particular, phenolic hydroxyl groups in the molecule, and the curing ability.
Examples of the polyol curing agent includes salts of a basic compound with a phenol compound of the formula:
or a phenolic resin of the formula:
wherein Z is —CH
2
— or —CH
2
OCH
2
—, Y is a hydrogen atom, a halogen atom, or a group of the formula: —R, —CH
2
OR or —OR in which R is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 100.
Examples of the basic compound include ammonium, phosphonium, alkali metals (e.g. lithium, sodium, potassium, etc.), alkaline earth metals (e.g. beryllium, magnesium, calcium, barium, etc.), and so on.
Among them, the salts of hydroquinone, bisphenol A, bisphenol AF, resol type phenolic resins, etc. are preferable in view of the properties of the coating films.
As a curing agent, a combination of the above basic polyol and other polyol may be used.
(C) Curing Accelerator
The composition of the present invention may contain the following compound as an optional curing accelerator:
Quaternary Ammonium Salt
A quaternary ammonium salt of the formula:
NR
4
X or R
3
N—R′—NR
3
.2X
wherein X is an acid residue or a hydroxyl group, R groups are the same or different and each an alkyl group having 1 to 20 carbon atoms, an halogenated alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, or two or more R groups together form a carbon ring or a heterocyclic group, and R′ is an alkylene group having 2 to 21 carbon atoms or a phenylenedialkylene group having 8 to 12 carbon atoms.
Examples of the acid residue include halide, sulfate, sulfite, bisulfite, thiosulfate, sulfide, polysulfide, hydrogen sulfide, thiocyanate, carbonate, bicarbonate, nitrate, carboxylate, borate, phosphate, biphosphate, phosphite, perchlorate, bifluoride, arsenate, ferricyanide, ferrocyanide, molybdate, selenate, selenite, uranate, tungstate, etc.
Specific examples of the quaternary ammonium salt include quaternary alkyl- and aralkyl-ammonium salts (e.g. trimethylbenzylammonium chloride, triethylbenzylammonium chloride, dimethyldecylbenzylammonium chloride, triethylbenzylammonium chloride, myristylbenzyldimethylammonium chloride, dodecyltrimethylammonium chloride, dimethyltetradecylbenzylammonium chlroride, trimethyltetradecylammonium chloride, coconuttrimethylammonium chloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, tetrabutylammonium hydroxide, 1,4-phenylenedimethylenebistrimethylammonium dichloride, 1,4-phenylenedimethylenebistriethylammonium dichloride, ethylenebistriethylammonium dibromide, etc.), quaternary 1,8-diaza-bicyclo[5.4.0]-7-undecenium salts (e.g. 8-methyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium chloride, 8-methyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium iodide, 8-methyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium hydroxide, 8-methyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium methylsulfate, 8-methyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium bromide, 8-propyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium bromide, 8-dodecyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium chloride, 8-dodecyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium hydroxide, 8-eicosyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium chloride, 8-tetracosyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium chloride, 8-benzyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium chloride, 8-benzyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium hydroxide, 8-phenetyl-1,8-diaza-bicyclo[5.4.0]-7-undecenium chloride, 8-(3-phenylpropyl)-1,8-diaza-bicyclo[5.4.0]-7-undecenium chloride, etc.), and the like.
Furthermore, as curing acce
Nakatani Yasukazu
Ogita Koichiro
Terasaka Kiyotaro
Tomihashi Nobuyuki
Birch & Stewart Kolasch & Birch, LLP
Daikin Industries Ltd.
Wilson D. R.
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