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
2001-06-14
2004-06-01
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...
C524S544000, C524S545000, C524S546000
Reexamination Certificate
active
06743842
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a fluorine-containing resin powder coating composition, particularly a fluorine-containing resin powder coating composition having excellent antistatic property and stain-proofing property.
BACKGROUND ART
Fluorine-containing resins are excellent in water repellency, oil repellency, heat resistance, weather resistance and chemical resistance and are used as various resins for coating.
Also powder coating compositions comprising a fluorine-containing resin are known. For example, JP-B-6-104792 describes a powder coating composition mainly comprising chlorotrifluoroethylene (CTFE)/tetrafluoroethylene (TFE) copolymer. Also JP-A-4-227743 describes a thermoplastic powder coating composition comprising a vinylidene fluoride (VdF)/hexafluoropropylene (HFP) copolymer and a thermoplastic acrylic resin, and JP-A-6-108103 describes a powder coating composition comprising polyvinylidene fluoride (PVdF), a thermoplastic resin and a VdF/tetrafluoroethylene (TFE)/HFP terpolymer. Further it is proposed in JP-A-1-103670 that a copolymer mainly comprising chlorotrifluoroethylene (CTFE) or TFE is used solely as a resin component in a thermosetting powder coating composition. Also JP-A-6-279549 proposes to use a copolymer of VdF and allyl derivative solely as a resin component.
Coating films formed by using those fluorine-containing resin powder coating compositions have problems that lipophilic stain is easily adhered thereto due to excellent water repellency of the fluorine-containing resin and is difficult to be removed. Further fluorine-containing resins are relatively soft and a surface thereof is easily damaged.
A powder coating is generally prepared by mixing a resin and other components such as a pigment and curing agent, and after once melt-kneaded, pulverized and classified with a sieve. However since a fluorine-containing resin has a high insulating property and is easily charged, when classifying after the pulverization, adhesion to walls of a vessel and sparking occur. Thus handling thereof is not good. Further since there arise a difference in charge amount at electrostatic coating, it is difficult to coat thick.
DISCLOSURE OF INVENTION
The present invention relates to a fluorine-containing resin powder coating composition which gives a property of a stain hardly adhering to a formed coating film (stain-proofing property) and is excellent in a property (electric-charge removability) of preventing accumulation of electric charge which becomes a problem when preparing a powder coating composition.
Namely the present invention relates to the powder coating composition comprising a fluorine-containing resin (A) and a silicate component (B).
As the silicate component (B), there is used at least one selected from
a tetrafunctional silicate compound represented by the formula (I): Si(OR)
4
, wherein R is the same or different and each is an organic group having 1 to 16 carbon atoms, preferably 1 to 8 carbon atoms, or a condensation product thereof;
a trifunctional silicate compound represented by the formula (II): R
2
Si(OR
1
)
3
, wherein R
1
is the same or different and each is an organic group having 1 to 16 carbon atoms, preferably 1 to 8 carbon atoms, R
2
is hydrogen atom or an organic group having 1 to 16 carbon atoms, preferably 1 to 8 carbon atoms, or a condensation product thereof; and a co-condensation product of the tetrafunctional silicate compound of the formula (I) and the trifunctional silicate compound of the formula (II).
An adding amount of the silicate component (B) is from 1 to 40 parts by weight (hereinafter referred to as “part”), preferably 5 to 15 parts based on 100 parts of the fluorine-containing resin (A). When the amount of the silicate component (B) is less than 1 part, not only an effect of preventing adhesion of stain of the obtained coating composition but also an effect of preventing electrostatic charge thereof are lowered. When more than 40 parts, storage stability of the coating composition is lowered.
The silicate component (B) prevents an excessive electrostatic charge of the fluorine-containing resin and makes an improvement in handling of the powder and coatability at electrostatic coating. Further a surface of the coating film is made hydrophilic by hydrolysis to exhibit functions of preventing stain from adhering, making removal of stain easy and enhancing a hardness of the coating film by condensation.
It is known that a silicate compound is added to a coating composition (JP-A-10-11078, WO944/06870, etc.). However an object of the addition is mainly to improve stain-proofing property and weather resistance of a solvent based coating and aqueous coating, and there is no description as to the above-mentioned specific problem of a powder coating composition (electrostatic charge, hardness of a coating film, etc.).
An object of the present invention is to select a silicate compound suitable for a powder coating composition among silicate compounds known as a stain-proofing agent and solve the specific problem of a powder coating composition.
BEST MODE FOR CARRYING OUT THE INVENTION
The fluorine-containing resin powder coating composition of the present invention comprises the fluorine-containing resin (A) and the silicate component (B) as mentioned above.
Examples of the fluorine-containing resin (A) are, for instance, a tetrafluoroethylene (TFE) copolymer, vinylidene fluoride (VdF) copolymer, chlorotrifluoroethylene (CTFE) copolymer, and the like.
Examples of the TFE copolymer are those mainly comprising TFE and prepared by copolymerizing one or two or more of other monomers, for example, hexafluoropropylene (HFP), ethylene (ET), isobutylene (IB) and propylene (PR). Concretely there are a TFE/HFP/ET copolymer (THE), TFE/HFP/IB copolymer (THI), TFE/ET/PR copolymer (TEP), and the like. Particularly from the viewpoint of pulverizability and storage stability, THE and THI are preferable.
Examples of the VdF copolymer are those mainly comprising VdF and prepared by copolymerizing one or two or more of other monomers such as TFE, trifluoroethylene (TrFE), chlorotrifluoroethylene (CTFE), HFP and monofluoroethylene (VF). Concretely there are a VdF/TFE copolymer, VdF/TFE/HFP copolymer, VdF/TFE/CTFE copolymer, VdF/TrFE copolymer, VdF/VF copolymer, and the like. Particularly from the viewpoint of pulverizability and storage stability, VdF/TFE copolymer and VdF/TFE/HFP copolymer are preferable.
Also examples of the CTFE copolymer are those mainly comprising CTFE and prepared by copolymerizing one or two or more of other monomers such as TFE, ethyl vinyl ether (EVE), isobutyl vinyl ether (iso-BVE) and vinyl acetate (VA). Concretely there are a CTFE/TFE copolymer, CTFE/EVE copolymer, CTFE/iso-BVE copolymer, CTFE/TFE/iso-BVE/VA copolymer, and the like.
In the present invention, a thermosetting powder coating composition can be provided by introducing a crosslinkable functional group into the fluorine-containing resin (A).
Examples of preferable crosslinkable functional group are, for instance, functional groups represented by the following group of formulae (i):
wherein R is an alkyl group having 1 to 3 carbon atoms.
Among the above-mentioned functional groups, the following group of formulae (ii) is preferable.
Examples of monomers being capable of introducing such a crosslinkable functional group are, for instance, perfluorobutenoic acid (PFBA), fluorine-containing monomers having an ether unit described in JP-A-8-67795, and in addition, non-fluorine-containing monomers having carboxylic acid group such as meleic anhydride (MAL); hydroxyl group-containing monomers such as hydroxybutyl vinyl ether (HBVE) and allyl alcohol; epoxy group-containing monomers such as glycidyl vinyl ether (GVE); vinyl methoxy silane, vinyl ethoxy silane and hydrolyzable silyl group-containing monomers described in JP-A-8-120211, monomers having aminopropoxy group, and the like.
Among them, PFBA, carboxyl group-containing monomers such as maleic anhydride, hydroxyl group-containing monomers such as HBVE and epoxy (glycidyl) group-cont
Fukagawa Ryoichi
Iwakiri Miyuki
Iwakiri Ryuji
Nagai Go
Nagato Masaru
Daikin Industries Ltd.
Hu Henry S.
Iwakiri Miyuki
Wu David W.
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