Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-09-27
2002-07-09
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S194000, C525S205000, C525S207000, C525S209000, C525S221000, C525S224000, C525S226000, C525S227000, C525S230000, C525S238000, C525S239000, C525S241000, C428S500000, C428S513000
Reexamination Certificate
active
06417277
ABSTRACT:
The present invention relates to a coating composition which is excellent in a curing property (particularly a low temperature curing property) of a coating film and which forms a coating film having excellent properties such as a chipping resistance and an adhesive property.
Publicly known is a coating composition prepared by adding a melamine resin or a polyisocyanate compound as a cross-linking agent to a hydroxyl group-containing acryl resin or a hydroxyl group-containing polyester resin, and the above coating composition forms a coating film which is excellent in a smoothness and a weatherability, so that it is widely used as a top coating material for outside plates for car bodies and home electric products. However, these coating materials are requested to be improved further more in coating film performances, and an improvement in particularly a curing property of a coating film, particularly a low temperature curing property, a chipping resistance and an adhesive property is pointed out.
The present inventors have intensively researched a coating composition comprising a hydroxyl group-containing resin and a cross-linking agent for the purpose of improving a curing property, a chipping resistance and an adhesive property of a coating film without reducing a smoothness and a weatherability of the coating film. As a result thereof, they have found that the object described above can be achieved by adding a phosphoric acid group-containing resin to the above coating composition and thus have come to complete the present invention.
Thus, the present invention provides a coating composition comprising a hydroxyl group-containing resin (A), a cross-linking agent (B) and a phosphoric acid group-containing vinyl resin (C).
The coating composition of the present invention shall be explained below in further details.
Component (A): Hydroxyl Group-containing Resin
It is a resin containing at least 2 hydroxyl groups in a molecule and, for example, a hydroxyl group-containing acryl resin and a hydroxyl group-containing polyester resin can suitably be used.
The hydroxyl group-containing acryl resin can be obtained by, for example, copolymerizing a hydroxyl group-containing polymerizable monomer with an acryl base monomer and, if necessary, other polymerizable monomers.
The hydroxyl group-containing polymerizable monomer is a compound having at least one hydroxyl group and at least one polymerizable unsaturated bond in a molecule and includes, for example, monoesters of glycols having 2 or more carbon atoms, preferably 2 to 10 carbon atoms with acrylic acid or methacrylic acid, such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate. Further, those obtained by subjecting hydroxyl groups of these monomers to ring-opening addition reaction with cyclic esters such as &egr;-caprolactam to introduce hydroxyl groups into terminals thereof can also be used as the hydroxyl group-containing polymerizable monomer.
The acryl base monomer includes, for example, esters of acrylic acid or methacrylic acid with monohydric alcohols having 1 to 22 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate and 2-ethylhexyl (meth)acrylate; diesters of glycols having 2 to 10 carbon atoms such as ethylene glycol, propylene glycol and-butylene glycol with acrylic acid or methacrylic acid; and alkoxyalkyl esters having 2 to 18 carbon atoms with acrylic acid or methacrylic acid, such as methoxybutyl (meth)acrylate, methoxyethyl (meth)acrylate and ethoxybutyl (meth)acrylate.
The other polymerizable monomers are compounds having at least one polymerizable unsaturated bond in a molecule excluding the hydroxyl group-containing polymerizable monomers and the acryl base monomers described above and include, for example, styrene, a-methyl styrene, vinyltoluene, acrylonitrile, vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid and maleic acid.
These polymerizable monomers can be copolymerized by a publicly known method, and the hydroxyl-group-containing acryl resin thus obtained can have a number average molecular weight falling in a range of usually 2000 to 50000, particularly 3000 to 20000, a hydroxyl group value falling in a range of 10 to 200 mg KOH/g, particularly 20 to 150 mg KOH/g and an-acid value falling in a range of 80 mg KOH/g or less, particularly 50 mg KOH/g or less.
The hydroxyl group-containing polyester resin can be obtained by, for example, esterifying a polybasic acid with a polyhydric alcohol in a proportion of hydroxyl group excess.
The polybasic acid is a compound having at least 2 carboxyl groups in a molecule and includes, for example, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic.acid, sebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, hexachloro endomethylene tetrahydrophthalic acid, trimellitic acid and their anhydrides. The polyhydric alcohol is a compound having at least 2 hydroxyl groups in a molecule and includes, for example, ethylene glycol, propylene glycol, butylene glycol, hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane and pentaerythritol.
The polybasic acid can be esterified with the polyhydric alcohol on a hydroxyl group excess condition by a conventional method, and the hydroxyl group-containing polyester resin thus obtained can have a number average molecular weight falling in a range of usually 3000 to 20000, particularly 5000 to 13000, a hydroxyl group value falling in a range of 30 to 150 mg KOH/g, particularly 65 to 120 mg KOH/g and an acid value falling in a range of 80 mg KOH/g or less, particularly 50 mg KOH/g or less.
Further, those obtained by subjecting hydroxyl groups contained in the polyester resins described above to ring-opening addition with cyclic esters such as &egr;-caprolactam to introduce hydroxyl groups into terminals thereof can also be used as the hydroxyl group-containing resin.
The coating composition of the present invention can be preferably used in water base form, and in the water base form, a carboxyl group is preferably allowed to be present together in these hydroxyl group-containing resins and is neutralized with a basic compound to be made water-soluble or water-dispersible. Capable being used as the basic compound used for neutralization are, for example, hydroxides of alkaline metals or alkaline earth metals, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide and barium hydroxide; primary monoamines such as ethylamine, propylamine, butylamine, benzylamine, monoethanolamine, neopentanolamine, 2-aminopropanol and 3-aminopropanol; secondary monoamines such as diethylamine, diethanolamine, di-n- or di-iso-propanolamine, N-methylethanolamine and N-ethylethanolamine; tertiary monoamines such as dimethylethanolamine, trimethylamine, triethylamine, triisopropylamine, methyldiethanolamine and dimethylaminoethanol; and polyamines such as diethylenetriamine, hydroxethylaminoethylamine, ethylaminoethylamine and methylaminopropylamine.
Component (B): Cross-linking Agent
It is intended to react with a hydroxyl group of the hydroxyl group-containing resin which is the component (A) described above to cross-link three-dimensionally the above resin form to cure it and, for example, a melamine resin and a block polyisocyanate compound can be.
An etherified melamine resin obtained by etherifying a part or all of methylol groups of methylol-reduced melamine with monohydric alcohol having 1 to 8 carbon atoms can suitably be used as the melamine resin. The melamine resin can contain 1 to 5 triazine nuclei and has preferably a number average molecular weight falling in a range of usually 300 to 2000. Further, the resins in which the etherification described above is partially made and an etherified methylol group and a methylol group are present together can be used as well.
The block polyisocyanate compound is obtained
Kasari Akira
Tomizaki Yasuhiro
Kansai Paint Co. Ltd.
Nutter Nathan M.
Wenderoth , Lind & Ponack, L.L.P.
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