Stock material or miscellaneous articles – Composite – Of polycarbonate
Reexamination Certificate
2000-03-09
2002-03-26
Boykin, Terressa M. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polycarbonate
Reexamination Certificate
active
06361865
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method of applying, to a synthetic resin substrate, a surface protective coating which is excellent in weather resistance and chemical resistance.
BACKGROUND ART
Hitherto a range of use of general-purpose resins such as vinyl chloride resin, vinyl acetate resin and acrylic resin and in addition, engineering plastics such as nylon, polyacetal, polycarbonate, modified PPO resin and modified PBT resin has been increasing in various fields because they have excellent heat resistance and impact resistance. For improvement in light stability and solvent resistance (solvent cracking) thereof, coating with a fluorine-containing resin has been desired.
As the method of such coating, a solvent-coating method of coating a fluorine-containing resin dissolved in a specific solvent has been proposed (JP-A-63-199771). However since a solvent is used, the method is disadvantageous from the viewpoint of removal of solvent, cost for recovering a solvent and working environment such as safety. In view of improvement of those properties, development of an aqueous coating method has been desired.
When a synthetic resin substrate contacts a solvent, deterioration of its surface arises. In order to prevent the surface deterioration, there has been proposed a method of coating by using a solvent having a low solubility such as a non-polar solvent or an alcoholic solvent. However in that method, sufficient adhesion to the resin substrate cannot be obtained.
The present invention can provide a method of forming a surface protective coating of a fluorine-containing resin on a surface of synthetic resin, in which the above-mentioned problems can be eliminated by applying the fluorine-containing resin composition in the form of an aqueous dispersion and then drying.
DISCLOSURE OF THE INVENTION
The present invention provides a method of forming, on a synthetic resin, a surface protective coating layer being excellent in weather resistance and chemical resistance by applying an aqueous dispersion of fluorine-containing resin to a surface of the synthetic resin.
Also the present invention provides a transparent laminated article of synthetic resin which is obtained by the above-mentioned method. Further it is preferable that the fluorine-containing resin in the aqueous dispersion has at least one functional group selected from the group consisting of hydroxyl, epoxy and carboxyl.
In the present invention, an aqueous dispersion of fluorine-containing resin is an aqueous dispersion in which the fluorine-containing resin particles are stably dispersed in water. Such an aqueous dispersion of fluorine-containing resin itself is a known one (for example, JP-A-8-120210, JP-A-8-120211, JP-A-4-7784, JP-A-7-258499).
BEST MODE FOR CARRYING OUT THE INVENTION
Examples of the fluorine-containing resin particles used for the aqueous dispersion of fluorine-containing resin of the present invention are particles of (1) a fluoroolefin polymer, (2) a copolymer of fluoroolefin and monomer copolymerizable therewith and (3) a composite resin comprising a non-fluorine-containing resin and the above-mentioned polymer or copolymer.
Examples of fluoroolefin are, for instance, fluoroolefins having 2 to 4 carbon atoms such as vinyl fluoride, vinylidene fluoride (VdF), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP) and trifluoroethylene.
Examples of the fluoroolefin polymer (1) are homopolymers of those fluoroolefins or copolymers comprising two or more of those fluoroolefins. Examples thereof are homopolymers of VdF, TFE and CTFE, VdF/TFE copolymer, VdF/HFP copolymer, VdF/CTFE copolymer, VdF/TFE/CTFE copolymer, VdF/TFE/HFP copolymer, TFE/HFP copolymer, and the like.
An aqueous dispersion of particles of fluoroolefin polymer (1) can be prepared through usual emulsion polymerization, for example, by emulsion-polymerizing, through usual method, the above-mentioned fluoroolefin in the presence of an emulsifying agent in an amount of not more than 5% (% by weight, hereinafter the same unless particularly noted), preferably not more than 1% on the basis of water.
Water used for the emulsion polymerization is preferably de-ionized water. Also it is preferable that the emulsifying agent is a fluorine-containing surfactant. Further a reactive fluorine-containing emulsifying agent can be used. It is also possible to use a slight amount of non-fluorine-containing nonionic emulsifying agent together.
The fluorine-containing emulsifying agent used in the present invention is one or a mixture of compounds containing fluorine atoms in their structures and having surface activity. For example, there are an acid represented by X(CF
2
)nCOOH, in which n is an integer of 6 to 20, X is F or H, its metal salt, ammonium salt, amine salt or quaternary ammonium salt; an acid represented by Y(CH
2
CF
2
)mCOOH, in which m is an integer of 6 to 13, Y is F or Cl, its metal salt, ammonium salt, amine salt or quaternary ammonium salt; and the like. In addition, it is possible to use solely a reactive emulsifying agent disclosed in JP-A-8-67795 and to use the reactive emulsifying agent in combination with the above-mentioned fluorine-containing emulsifying agent. Also it is possible to use a non-fluorine-containing nonionic emulsifying agent disclosed in JP-A-7-90153 together.
Then the copolymer (2) comprising fluoroolefin and monomer copolymerizable therewith is explained below.
Examples of the monomer copolymerizable with fluoroolefin are, for instance, ethylene; a-olefins such as propylene and isobutylene; vinyl ethers such as ethyl vinyl ether (EVE), cyclohexyl vinyl ether (CHVE), hydroxybutyl vinyl ether (HBVE), butyl vinyl ether, isobutyl vinyl ether, methyl vinyl ether and polyoxyethylene vinyl ether; allyl ethers such as polyoxyethylene allyl ether, ethyl allyl ether and hydroxyethyl allyl ether; allyl alcohols such as allyl alcohol, diallyl alcohol and eugenol; vinyl esters such as vinyl acetate, vinyl lactate, vinyl butyrate, vinyl pivalate, vinyl benzoate, and VEOVA9 and VEOVA10 (brand names of products available from Shell Chemical Co., Ltd.); allyl esters such as allyl acetoacetate; ethylenically unsaturated carboxylic acids such as itaconic anhydride, succinic anhydride and crotonic acid; and the like. Particularly ethylene, &agr;-olefins, vinyl ethers, vinyl esters, allyl ethers and allyl esters are preferably used.
Examples of the copolymer (2) comprising fluoroolefin and monomer copolymerizable therewith are TFE/propylene copolymer, TFE/ethylene copolymer, TFE/vinyl ester copolymers, TFE/vinyl ether copolymers, HFP/vinyl ether copolymers, HFP/vinyl ester copolymers, CTFE/vinyl ether copolymers, and the like. Further there are copolymers comprising three or more monomers, i.e. copolymers containing the above-mentioned copolymer and as a modifying monomer, the above-mentioned monomer copolymerizable with fluoroolefin in an amount of not more than 30% by mole.
It is preferable that the fluoroolefin monomer is contained in those copolymers comprising fluoroolefin and monomer copolymerizable therewith in an amount of 20 to 80% by mole.
When an amount of the fluoroolefin monomer is less than 20% by mole, weather resistance cannot be exhibited sufficiently. When more than 80% by mole, it is not preferable because at the time of making a coating and forming a coating film, lowering of appearance occurs.
The aqueous dispersion of particles of fluoroolefin copolymer (2) can be prepared, for example, through the same emulsion polymerization as in the preparation of the aqueous dispersion of particles of fluoroolefin polymer (1).
It is preferable that the copolymer of fluoroolefin and monomer copolymerizable with fluoroolefin has at least one functional group selected from the group consisting of hydroxyl, epoxy and carboxyl. Examples of a preferred monomer for introducing such a functional group are, as monomers having hydroxyl, hydroxyl-containing vinyl ethers such as HBVE; hydroxyl-containing allyl compounds such as allyl alcohol and hydroxyethyl allyl ether; hydroxyl-c
Imoto Katsuhiko
Iwakiri Ryuji
Nagato Masaru
Tsuda Nobuhiko
Boykin Terressa M.
Daikin Industries Ltd.
Sughrue & Mion, PLLC
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