AU715580B2 - Novel melamine resin composition and use thereof - Google Patents

Description

DESCRIPTION

NOVEL MELAMINE RESIN COMPOSITION AND USE THEREOF FIELD OF THE INVENTION The present invention relates to a melamine resin composition prepared by blending a copolymer microgel emulsion comprising diallyl phthalate, as an essential component, and a vinyl compound with a melamine resin solution, and a decorative laminate obtained by using said composition as an impregnating resin composition.

RELATED ART As a conventional method of producing a high-pressure melamine decorative laminate, there has been used a method of impregnating a patterned or colored decorative paper with a melamine resin, positioning the impregnated decorative paper on a kraft paper impregnated with the other thermoplastic resin, hot-press molding to form a laminate, and adhering this laminate to the surface of a base material by an adhesive.

This method for production can afford a high-quality product, but has problems that a long-term continuous molding with a cycle of cold press/hot press/cold press is required so as to laminate an impregnating paper and a kraft impregnated paper and that the number of steps is large and, for example, the adherend must be subjected to a sanding process.

There has recently been used a method of impregnating a decorative paper with a rapid-curable melamine resin for exclusive use, and adhering directly to a ase material and molding at the same time. The resultant is a low-pressure short- 2 cycle melamine decorative laminate, and it became possible to conduct the mass production.

However, the low-pressure short-cycle melamine decorative laminate is inferior in design properties to a high-pressure melamine decorative laminate and results in low quality. The reasons therefor are considered as follows. Since an impregnating resin is cured within a short time, the molding of an impregnated paper and a base material is conducted at high temperature and the resulting product is removed from a hot press. Therefore, water contained in the impregnated paper and woody base material as well as an elimination product formed by the condensation reaction of a thermosetting resin can cause deterioration of surface properties such as deterioration of gloss in the process of coming out from the surface of the molded article.

Means for solving the above-described problems in the production of the iI: short-cycle melamine decorative laminate include a method of decreasing an 15 amount of a volatile component in a base material and an impregnated paper as much as possible (controlling an amount of the volatile component to about a method of increasing an amount of a thermosetting resin and an initiator in an impregnating resin, but the effect thereof is not sufficient. Particularly, the latter method is liable to cause deterioration of the heat stability at the molding step, 20 thereby deteriorating the surface properties of the product.

SUMMARY OF THE INVENTION ":"*Advantageously, the present invention alleviates the above-described problems in a method of producing a decorative laminate (a short cycle method), comprising adhering an impregnating paper directly to a base material simultaneously with the ding, so as to provide an impregnating melamine resin composition capable of imparting a gloss which is equal to that of a high-pressure melamine decorative laminate, and an improved wear resistance in most case. The present invention also provides a decorative laminate obtained by using this composition.

The present invention provides a melamine resin composition comprising a copolymer microgel emulsion comprising diallyl phthalate and a vinyl compound, and a melamine resin solution, the amount (in terms of solid content) of the copolymer microgel emulsion being from 0.2 to 30 parts by weight based on 100 parts by weight of a melamine resin in the melamine resin solution.

The present invention also provides a decorative laminate obtained by using said composition as an impregnating resin composition.

DETAILED DESCRIPTION OF THE INVENTION In the copolymer microgel comprising diallyl phthalate and a vinyl compound used in the present invention, an amount of diallyl phthalate is preferably from 5 to :.15 90% by weight based on the total amount of diallyl phthalate and the vinyl compound.

o oo Diallyl phthalate used in the present invention is a general name for diallyl orthophthalate, diallyl isophthalate and diallyl terephthalate, and these may be used alone or in combination thereof.

"20 The copolymer microgel emulsion containing diallyl phthalate as an essential component may be prepared by blending with other emulsion. In case of blending the copolymer microgel emulsion with the melamine resin, the copolymer microgel emulsion may be in a state of an emulsion, powder prepared by drying the emulsion, or a dispersion prepared by dispersing again in an organic solvent or It is possible to previously add an organic cosolvent to the emulsion or powder to be blended in an amount within the range from 1 to 50 parts by weight based on 100 parts by weight of the solid content of the emulsion or powder.

A polymerization degree of the copolymer microgel is not specifically limited, but it is preferred that the polymerization degree is high in view of problems of odor and deleterious effect, mechanical and physical properties and the like. Usually, the copolymer microgel having the polymerization degree of at least 70% may be used.

The vinyl compound used in the present invention may have a group selected from a silyl group, an epoxy group, a hydroxyl group, a carbonyl group, a N-methylol group, a N-(O-alkylmethylol) group, a vinyl group and a halogen group.

Preferred are those selected from acrylate esters, methacrylate esters, allyl ethers, methallyl ethers, allyl esters, methallyl esters, allylamino compounds, methallyl amino compounds, vinyl compounds having a cyano group, aliphatic hydrocarbons having an unsaturated bond, a,P-unsaturated aldehydes, a,p-unsaturated ketones, vinyl carboxylic acids or acid anhydrides or salts thereof, acrylamides, methacrylamides, styrenes, a-methylstyrenes, vinyl ethers, vinyl esters, maleate esters, fumarate esters, vinylsilanes, allyl alcohol and methallyl alcohol.

Examples of the acrylate esters include esters of saturated aliphatic alcohols, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, t-butyl acrylate, pentyl acrylate, cyclopentyl acrylate, hexyl acrylate, cyclohexyl acrylate, heptyl acrylate, methylcyclohexyl acrylate, octyl acrylate and 2-ethylhexyl acrylate; polyacrylate esters having a plurality of acrylic groups in the molecule, such as ethylene glycol diacrylate, diethylene glycol diacrylate, propylene glycol diacrylate, dipropylene 2Z glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, glycerine triacrylate, trimethyloipropane triaorylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, triazine triacrylate and phosphazene triacrylate; esters having a hydroxyl group, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3hydroxypropyl acrylate, 4-hydroxybutyl acrylate, acrylic acid monoester of glycerine and acrylic acid monoester of pentaerythritol; esters having a halogen group, such as chloroethyl acrylate, trifluoroethyl acrylate, perfluoroalkyl acrylates and acrylate esters of a fluorinated alcohol component acrylate ester of perfluoroalcohol wherein only the 1-position is substituted with hydrogen); esters having an alkoxysilyl group, such as trimethoxysilyipropyl acrylate and triethoxysilylpropyl acrylate; esters having an epoxy group, such as glycidyl acrylate and 2methylglycidyl acrylate; esters having a carbonyl group, such as acetoacetoxyethyl acrylate; and esters having a vinyl group, such as allyl acrylate and methallyl acrylate.

Examples of the methacrylate esters include esters of saturated aliphatic alcohols, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, cyclopentyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, heptyl methacrylate, methylcyclohexyl methacrylate, octyl methacrylate and 2-ethylhexyl methacrylate; polymethacrylate esters having a plurality of methacrylic groups in the molecule, such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, propylene glycol dimethacrylate, dipropylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, glycerine trimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, triazine #;*hachrylate and phosphazene trimethacrylate; esters having a hydroxyl group, such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, methacrylic acid monoester of glycerine and methacrylic acid monoester of pentaerythritol; esters having a halogen group, such as chloroethyl methacrylate, trifluoroethyl methacrylate, perfluoroalkyl methacrylate and methacrylate esters of a fluorinated alcohol component methacrylate ester of perfluoroalcohol wherein only the 1position is substituted with hydrogen); esters having an alkoxysilyl group, such as trimethoxysilylpropyl methacrylate and triethoxysilylpropyl methacrylate; esters having an epoxy group, such as glycidyl methacrylate and 2-methylglycidyl methacrylate; esters having a carbonyl group, such as acetoacetoxyethyl methacrylate; and esters having a vinyl group, such as allyl methacrylate and methallyl methacrylate.

Examples of the allyl ethers include an allyl ether such as methyl allyl ether, ethyl allyl ether, propyl allyl ether, butyl allyl ether, hexyl allyl ether, cyclohexyl allyl ether, 2-ethylhexyl allyl ether, phenyl allyl ether, cresyl allyl ether, diallyl ether, allyl glycidyl ether and 2-methylglycidyl allyl ether; and an allyl ether having a plurality of allyl ether groups in the molecule, such as ethylene glycol diallyl ether, propylene glycol diallyl ether, hexanediol diallyl ether, trimethylolpropane diallyl ether, pentaerythritol triallyl ether, dimethylolcyclohexane diallyl ether and triallyl isocyanurate.

Examples of the methallyl ethers include a methallyl ether such as methyl methallyl ether, ethyl methallyl ether, propyl methallyl ether, butyl methallyl ether, hexyl methallyl ether, cyclohexyl methallyl ether, 2-ethylhexyl methallyl ether, phenyl methallyl ether, cresyl methallyl ether, dimethallyl ether, methallyl ether, ;a hallyl glycidyl ether and 2-methylglycidyl methallyl ether; and a methallyl ether having a plurality of methallyl ether groups in the molecule, such as ethylene glycol dimethallyl ether, propylene glycol dimethallyl ether, hexanediol dimethallyl ether, trimethylolpropane dimethallyl ether, pentaerythritol trimethallyl ether, dimethylolcyclohexane dimethallyl ether and trimethallyl isoyanurate.

Examples of the allyl esters include an allyl ester such as allyl acetate, allyl propionate, allyl butyrate, allyl benzoate and allyl lactate; and an allyl ester having a plurality of allyl ester groups in the molecule, such as diallyl carbonate, diallyl oxalate, diallyl succinate, diallyl fumarate, diallyl maleate, diallyl adipate and diallyl cyclohexanedicarboxylate.

Examples of the methallyl esters include a methallyl ester such as methallyl acetate, methallyl propionate, methallyl butyrate, methallyl benzoate and methallyl lactate; and a methallyl ester having a plurality of methallyl ester groups in the molecule, such as dimethallyl carbonate, dimethallyl oxalate, dimethallyl succinate, dimethallyl fumarate, dimethallyl maleate, dimethallyl adipate and dimethallyl cyclohexanedicarboxylate.

Examples of the allylamino compounds include an amino compound having an allyl group, such as allylamine, diallylamine, triallylamine, dimethylallylamine, methyldiallylamine and dimethyldiallylammonium chloride.

Examples of the methallylamino compounds include an amino compound having an methallyl group, such as dimethallylamine, trimethallylamine, dimethylmethallylamine, methyldimethallylamine and dimethyldimethallylammonium chloride.

Examples of the vinyl compounds having a cyano group include acrylonitrile and methacrylonitrile.

,PA- Examples of the aliphatic hydrocarbons having an unsaturated bond include an aliphatic hydrocarbon having one unsaturated bond in the molecule, such as propylene, butene, pentene, hexene and cyclohexene; aliphatic hydrocarbons having a plurality of unsaturated bonds, such as butadiene, isoprene, hexadiene and vinylcyclohexene; and aliphatic hydrocarbons whose unsaturated bonds other than at least one unsaturated bond are epoxidized, such as butadiene monoepoxide, isoprene monoepoxide, 1,5-hexadiene monoepoxide and vinylcyclohexene monoepoxide.

Examples of the a,3-unsaturated aldehydes include acrolein, methacrolein and crotonaldehyde.

Examples of the a,3-unsaturated ketones include methyl vinyl ketone and ethyl vinyl ketone.

Examples of the vinylcarboxylic acids or acid anhydrides or salts thereof include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, monoallyl phthalate, monomethallyl phthalate, monoallyl maleate, monomethallyl maleate, monoallyl fumarate, monomethallyl fumarate, and an acid anhydride and salt thereof.

Examples of the acrylamides and methacrylamides include amides such as acrylamide and methacrylamide; amides having a N-methylol group, such as Nmethylolacrylamide and N-methylolmethacrylamide; amides having an etherified or non-etherified methylol group, such as N-(O-methylmethylol)acrylamide,

N-(O-

methylmethylol)methacrylamide, N-(O-butylmethylol)acrylamide and N-(Obutylmethylol)methacrylamide; amides of a saturated amine having 1 to 5 carbon atoms, such as isopropylacrylamide and isopropylmethacrylamide; amides having a carbonyl group, such as diacetoneacrylamide and diacetonemethacrylamide; aides having a plurality of acrylamide groups in the molecule, such as ethylenediaminediacrylamide, hexanediaminediacrylamide and phenylenediaminediacrylamide; and amides having a plurality of methacrylamide groups in the molecule, such as ethylenediaminedimethacrylamide, hexanediaminedimethacrylamide and phenylenediaminedimethacrylamide.

Examples of the styrenes include styrenes having aromatic ring substituted with halogen, an alkyl group, a halogenated alkyl group or a vinyl group, such as styrene, ortho- or para-chlorostyrene, ortho- or para-methylstyrene, ortho- or parachloromethylstyrene, divinylbenzene and trivinylbenzene.

Examples of the a-methylstyrenes include a-methylstyrenes having aromatic ring substituted with halogen, an alkyl group, a halogenated alkyl group or a vinyl group, such as a-methylstyrene, ortho- or para-chloro-a-methylstyrene, ortho- or para-methyl-a-methylstyrene, ortho- or para-chloro-a-methylstyrene and diisopropenylbenzene.

Examples of the vinyl ethers include a vinyl ether having 3 to 10 carbon atoms, such as methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinyl ether, isobutyl vinyl ether, n-amyl vinyl ether, isoamyl vinyl ether, 2-ethylhexyl vinyl ether, 2-chloroethyl vinyl ether, allyl vinyl ether and methallyl vinyl ether.

Examples of the vinyl esters include vinyl acetate, vinyl propionate, a vinyl long-chain carboxylate such as Beova 10 (trade name, manufactured by Shell Japan Co.) and Beova 9 (trade name, manufactured by Shell Japan Co.).

Examples of the maleate esters include a maleate ester of a saturated or unsaturated aliphatic alcohol having 1 to 8 carbon atoms, such as dimethyl maleate, diethyl maleate, dibutyl maleate, diallyl maleate and dimethallyl maleate.

Examples of the fumarate esters include a fumarate ester of a saturated or 4unsaturated aliphatic alcohol having 1 to 8 carbon atoms, such as dimethyl fumarate, diethyl fumarate, dibutyl fumarate, diallyl fumarate and dimethallyl fumarate.

Examples of the vinylsilanes include an alkoxysilane such as trimethoxyvinylsilane, triethoxyvinylsilane and trimethylallyloxysilane; an alkylvinylsilane such as vinyltrimethylsilane and vinyldiethylmethylsilane; divinyldimethylsilane, divinyldiethylsilane, acryloxypropyltrimethoxysilane and methacryloxypropyltrimethoxysilane.

These vinyl compounds can be used alone or in combination thereof.

An amount of diallyl phthalate in the copolymer microgel of diallyl phthalate, as an essential component, and the vinyl compound according to the present invention is preferably from 5 to 90% by weight based on the total amount of the diallyl phthalate and vinyl compound. When the amount is less than 5% by weight, the gloss is poor in case of forming a composition of the copolymer microgel and melamine resin. On the other hand, when it exceeds 90% by weight, the storage stability of the resulting copolymer microgel emulsion is poor.

In the present invention, the copolymer microgel preferably comprises (1) diallyl phthalate, (meth)acrylate ester, and vinylcarboxylic acid and/or (meth)acrylate ester having a hydroxyl group. An amount of diallyl phthalate is from to 90% by weight, e.g. from 10 to 80% by weight, particularly from 20 to 80% by weight, based on the copolymer. An amount of the (meth)acrylate ester other than the (meth)acrylate ester having a hydroxyl group is from 2 to 95% by weight, e.g.

from 10 to 89% by weight, particularly from 10 to 78% by weight, based on the copolymer. An amount of the vinylcarboxylic acid and/or (meth)acrylate ester having a hydroxyl group is from 0 to 15% by weight, e.g. 1 to 10% by weight, 2,=rticularly from 2 to 10% by weight, based on the copolymer.

Examples of an emulsifier used in case of polymerizing diallyl phthalate with the vinyl compound include a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, an anionic-nonionic mixture surfactant or a complex surfactant thereof. Usually, the anionic surfactant and the anionicnonionic mixture surfactant give good results.

Examples of the cationic surfactant include a primary amine hydrochloride, a secondary amine hydrochloride, a tertiary amine hydrochloride and a quaternary ammonium hydrochloride.

Examples of the anionic surfactant include a fatty acid salt, a sulfuric ester salt of higher alcohol, a sulfuric ester of liquid fatty oil, a sulfate salt of aliphatic amine and aliphatic amide, a phosphate ester of fatty alcohol, a sulfonate salt of dibasic fatty acid ester, a sulfonate salt of aliphatic amide, an alkylallyl sulfonate salt and formalin-condensed naphthalene sulfonate salt.

Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene aryl ether, polyoxyethylene polyoxypropylene aryl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene polyoxypropylene alkyl aryl ether, polyoxyethylene polyoxypropylene alkyl ester; polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, sorbitan alkyl ester and polyoxyethylene sorbitan alkyl ester.

Examples of the amphoteric surfactant include amino acid, betaine, sulfate ester salt, sulfonate and phosphate ester salt surfactants.

A reactive emulsifier having a polymerizable double bond in one molecule may be used as the surfactant. Specific examples thereof include those manufactured by Sanyo Chemical Industries, Ltd., such as Eleminol JS-2, Ofse manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., such as Aqualon Lo rT~ O.

12 RN-50, HS-10, HS-20, HS-1025, New Frontiers; and those manufactured by Nihon Nyukazai Co., Ltd., such as Antox-MS-60, Antox-MS-2N, Antox-MS-NH4, RA-1000 series, RMA-500 series, RMA-1120-MA series and MPG-130-MA.

An amount of the used surfactant is preferably from 0.1 to 10% by weight based on the whole monomer. When the amount is less than 0.1% by weight, an agglomerate is liable to be formed during the polymerization. Even if the amount exceeds 10% by weight, an improvement in reaction stability due to an increase of addition amount is not recognized. Preferably, 0.5 to 7% by weight is used. The surfactant may be fed in one portion at the beginning, or fed in several portions with a lapse of the reaction.

Examples of a water-soluble radical initiator used to obtain the emulsion of the present invention include known initiators such as ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, a water-soluble azo initiator, a redox initiator and the like.

Examples of the water-soluble azo initiator include hydrochlorides of an azo compound having an amino group or an imino group, such as 2,2'-azobis(2methyl-N-phenylpropionamidine)dihydrochloride 2 ,2'-azobis(N-(4-chlorophenyl)- 2 -methylpropionamidine)dihydrochloride, 2,2'-azobis(2-methyl-N- S (phenylmethyl)propionamidine)dihydrochloride and 2 ,2'-azobis(2-methyl-N-(2propenyl)propionamidine)dihydrochloride; and hydrochlorides of an azo Ve Scompound having a cyclic amino group or imino group, such as 2,2'-azobis(2-(5methyl- 2 -imidazolin-2-yl)propane)dihydrochloride, 2 ,2'-azobis(2-(2-imidazolin-2yl)propane)dihydrochloride, 2 2 '-azobis(2-(4,5,6,7-tetrahydro-l1H-1,3-diazepin-2- R pane)dihydrochloride and 2,2'-azobis(2-(5-hydroxy-3,4,5,6tetra dropyrimidine-2-yl)propane)dihydrochloride.

~Vy oG 13 Examples of the redox initiator include a combination of potassium persulfate or ammonium persulfate with sodium hydrogensulfite, sodium metabisulfite, acidic sodium sulfite or Rongalit (sodium formaldehydesulfoxylate dihydrate), and a combination of an organic peroxide t-butyl hydroperoxide and cumene hydroperoxide) and acidic sodium sulfite or Rongalit. A combination of a persulfate salt and a reducing agent is particularly preferred because the polymerization can stably be conducted.

It is possible to optionally use a lipophilic peroxide benzoyl peroxide and t-butyl hydroperoxide) and a lipophilic azo compound 2,2azobisisobutyronitrile and 1,1 -azobis(cyclohexane-1 -carbonitrile)).

An amount of the used initiator is usually from 0.05 to 5% by weight based on the monomer, and the initiator may be added in one portion, or added in several portions.

The melamine resin of the melamine resin solution used in the present invention is preferably a melamine resin for low-pressure molding. A rapid-curable melamine resin for short cycle molding is particularly preferred. The melamine resin may also be a melamine resin for high-pressure molding.

Examples of a solvent of the melamine resin solution include water and I water-soluble organic solvent methanol, ethanol and isopropanol). A mixture of water and the water-soluble organic solvent may also be used.

A resin concentration of the melamine resin solution is preferably from 20 to 90% by weight, more preferably from 30 to 80% by weight.

The composition of the present invention can be obtained by blending the -polymer microgel emulsion of diallyl phthalate and the vinyl compound with the melaine resin solution, as described above. The copolymer microgel emulsion -o W can be prepared by using the diallyl phthalate and vinyl compound according to the following method.

A monomer concentration based on the total amount of the diallyl phthalate and vinyl compound is usually from 5 to 50% by weight, and this monomer concentration approximately becomes a concentration of the resulting emulsion.

The monomer may be fed in one portion at the beginning, or fed in several portions with a lapse of the reaction. The form at the time of addition may be a monomer solution as such or an emulsion prepared by using an emulsifier.

In the emulsion, the copolymer microgel is dispersed in a medium.

Examples of the medium of the emulsion include water and water-soluble organic solvent methanol, ethanol and isopropanol). A mixture of water and the watersoluble organic solvent may be used.

A polymerization temperature should be determined by the type of the used initiator, but is usually within the range from 40 to 100°C, preferably from 50 to 900C.

With respect to the resulting copolymer microgel, those having an average particle diameter of 5 to 1000 nm, more preferably 10 to 500 nm, are preferred so as to accomplish the object of the present invention.

An amount of the copolymer microgel emulsion to be blended with the melamine resin solution is preferably from 0.2 to 30 parts by weight based on 100 parts by weight of the melamine resin, in terms of the solid content. When the amount is less than 0.2 part by weight or exceeds 30 parts by weight, an improvement in gloss at the time of molding is not attained. An amount of the copolymer microgel emulsion may be 0.2 to 25 parts by weight, e.g. 0.2 to 20 parts by weight, in terms of solid content.

A The above blended liquid may contain additives which are usually used, such as a curing accelerator, a mold release agent, an organic or inorganic filler, a plasticizer, a dispersant, a thickener, a viscosity modifier, a defoamer, an antiseptic and a ultraviolet absorber. It is also possible to add a known aqueous emulsion as far as the effect of the composition of the present invention is not adversely affected.

The decorative laminate is made by impregnating an impregnation paper or fabric with a melamine resin composition, drying the impregnated paper or fabric, positioning it on a base material and conducting a hot-press molding by a press machine.

The molding is conducted by a HOT-HOT press method without cooling in the same manner as a usual short cycle melamine. A molding pressure is from kg/cm2 to 30 kg/cm2, preferably from 15 kg/cm2 to 25 kg/cm2. A molding temperature is from 130°C to 2500°C, preferably from 150°C to 2200°C. A molding time is from 10 seconds to 30 minutes, preferably from 30 seconds to 10 minutes.

Examples of the impregnation paper or fabric include a titanium paper, a tissue paper, a reinforced paper, a kraft paper, a cellulose paper, and a nonwoven fabric of polyester, rayon, acryl and vinylon. Examples of the base material include a particle board, veneered wood, MDF (middle-density fiberboard), a slate plate, a calcium silicate plate, an aluminum plate and a stainless plate.

EXAMPLES

The present invention will be illustrated by the following Examples. In the Examples, is by weight unless otherwise specified.

(Preparation of diallyl emulsion) -Diallyl emulsion 1- The following materials were charged in a 1 L separable flask equipped with ^^-crer, a thermometer, a condenser, a gas introducing inlet and a sampling opening to prepare an aqueous emulsifier solution.

Sodium dodecylbenzenesulfonate 7.2 g (trade name: Neogen R, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) Deionized water 430 g A monomer mixture having the following composition was separately prepared.

Diallyl phthalate (DAP) 90 g (25% monomer) Ethyl acrylate (EA) 261 g (72.5% monomer) Acrylic acid (AA) 9 g monomer) The internal temperature of the flask was increased to 80 0 C and the atmosphere in the flask was sufficiently replaced with nitrogen with stirring at 300 rpm by a half-moon type stirring blade. Then, 10% of the prepared monomer mixture was charged and an aqueous solution prepared by dissolving 0.54 g of ammonium persulfate in 10 g of deionized water was added. After the reaction was conducted for 1 hour, the remaining 90% of the monomer mixture was successively added over about 3 hours (a monomer addition method). The polymerization was conducted at 80°C for 9 hours after the addition of the initiator. The resulting emulsion had a solid content of 45%, a polymerization degree for DAP of 97% and Sfor EA of 100%, and an average particle diameter of 127.3 nm.

The polymerization degree was determined by measuring the residual DAP and EA by gas chromatography (column: CBP-1), then calculating according to the following equation: Polymerization degree eight of charged monomer weight of unreacted monomer) x 100/weight of 4 fy5 charie monomer.

The average particle diameter was measured by a laser particle diameter analysis system (PHOTON CORRELATOR LPA-3000, Otsuka Denshi Co., Ltd.).

-Diallyl emulsion 2- The following aqueous emulsifier solution was prepared in a 1 L separable flask equipped with a stirrer, a thermometer, a condenser, a gas introducing inlet and a sampling opening.

Sodium dodecylbenzenesulfonate 1.92 g Deionized water 160 g The following emulsified monomer was separately prepared.

DAP 160 g (50% monomer) EA 152 g (47.5% monomer) AA 8 g monomer) Sodium dodecylbenzenesulfonate 4.48 g Deionized water 310 g o15 The internal temperature of the flask was increased to 70°C and the 0* atmosphere in the flask was sufficiently replaced with nitrogen with stirring at 300 rpm by a half-moon type stirring blade. Then, 10% of the emulsified monomer was charged and an aqueous solution prepared by dissolving 1.12 g of ammonium persulfate in 10 g of deionized water was added. After the reaction was conducted for 1 hour, the remaining emulsified monomer was successively added over 4 hours (emulsion addition method). The polymerization was conducted at 70 0 C for 9 hours after the addition of the initiator. The resulting emulsion had a solid content of 40%, a polymerization degree for DAP of 91.4% and for EA of 100% and an average particle diameter of 98.1 nm.

-Dialvrtemulsion 3- The following aqueous emulsifier solution was prepared in a 1 L separable flask equipped with a stirrer, a thermometer, a condenser, a gas introducing inlet and a sampling opening.

Sodium dodecylbenzenesulfonate 1.92 g Deionized water 160 g The following emulsified monomer was separately prepared.

DAP 240 g (75% monomer) 2-Ethylhexyl acrylate (2-EtHA) 80 g (25% monomer) Sodium dodecylbenzenesulfonate 4.50 g Deionized water 310 g The internal temperature of the flask was increased to 70 0 C and the atmosphere in the flask was sufficiently replaced with nitrogen with stirring at 300 rpm by a half-moon type stirring blade. Then, 10% of the emulsified monomer was charged and an aqueous solution prepared by dissolving 1.12 g of ammonium persulfate in 10 g of deionized water was added. After the reaction was conducted for 1 hour, the remaining emulsified monomer was successively added over 4 hours (emulsion addition method). The polymerization was conducted at 70°C for 9 hours after the addition of the initiator. The resulting emulsion had a solid content of 40%, a polymerization degree for DAP of 87.3% and for 2-EtHA of 100% and an average particle diameter of 117.0 nm.

-Diallyl emulsion 4- The following aqueous emulsifier solution was prepared in a 1 L separable flask equipped with a stirrer, a thermometer, a condenser, a gas introducing inlet d,,a sampling opening.

Soium dodecylbenzenesulfonate 1.40 g T u Os-' Deionized water 430 g The following emulsified monomers A and B were separately prepared.

Emulsified monomer A: DAP 54 g (25% monomer) EA 60 g (22.5% monomer) Sodium dodecylbenzenesulfonate 1.6 g Deionized water 57 g Emulsified monomer B: DAP 54 g (25% monomer) EA 60 g (22.5% monomer) AA 12 g monomer) Sodium dodecylbenzenesulfonate 1.8 g Deionized water 63 g Therefore, the whole blending ratio was as follows: DAP (50% monomer), EA (45% monomer) and AA monomer).

The internal temperature of the flask was increased to 70°C and the atmosphere in the flask was sufficiently replaced with nitrogen with stirring at 300 rpm by a half-moon type stirring blade. Then, 20% of the emulsified monomer A was charged and an aqueous solution prepared by dissolving 0.84 g of ammonium persulfonate in 10 g of deionized water was added. After the reaction was conducted for 1 hour, the remaining emulsified monomer A was successively added over 1.5 hours. Then, the emulsified monomer B was successively added (an emulsion addition method). The polymerization was conducted at 70°C for 9 hours after the addition of the catalyst. The resulting emulsion had a solid content ;)7oncentration of 30%, a polymerization degree for DAP of 94.7% and for EA of 100% and an average particle diameter of 84.0 nm.

(Preparation of impregnating liquid) The above allyl emulsions 1, 2, 3 and 4 were added to a rapid-curable melamine resin for the low-pressure molding (average amount of formaldehyde added to 1 mol of melamine was 2.8 mol) with stirring by a laboratory mixer manufactured by Tokushu Kika Co., Ltd. to give an impregnating resin liquid (see: Table 1 as for formulation).

Examples 1 to 11 and Comparative Examples 1 to 3 (Production of decorative laminate) Base paper for decorative laminate having a basis weight of 80 g/m 2 was impregnated with the impregnating resin liquid having a specified formulation so that an amount of the adhered resin was 60% (based on the weight of the impregnation paper) and then dried at 800C for 15 minutes to obtain an impregnated paper of the present invention. For comparison, an impregnated paper was produced according to the same manner as that described in the Examples except for using an impregnating resin liquid containing no diallyl emulsion and an impregnating resin liquid wherein the amount of the blended emulsion is not within the range of the present invention. Then, a decorative laminate was produced by using these impregnated papers. As a base material, a particle board having a thickness of 18 mm was used. A brass-chromium-plated mirror plate was used for a flat sheet press. With respect to the molding, a HOT- HOT press molding without cooling was conducted. The formulation of the resin, press conditions and surface characteristics of the resulting decorative laminate are summarized in Table 1.

A

1 The gloss was measured by using a 600 incidence-60 0 measurement photometry gloss meter (a gloss checker IG-320, manufactured by Horiba, Ltd.).

The pencil hardness was determined by examining the hardness of the lead of the pencil at which no scratch is formed (unevenness is excluded from the scratch) according to JIS K5400. The scratch hardness was determined by measuring a depth of a scratch formed under a load of 200 g according to a JAS (Japanese Agricultural Standard)-B test of a special plywood laminate. The wear resistance.

was determined according to a JAS (Japanese Agricultural Standard)-A test (500 g load) of a special plywood laminate. The stain resistance was determined by putting a mark on the surface of a decorative laminate by red and black felt pens, standing at room temperature for 24 hours, wiping off the mark by using ethanol, and observing the surface of the decorative laminate. The adhesion properties were determined by a X cut adhesive tape method according to JIS K-5400. The alkaline resistance was determined by dropping several drops of an aqueous NaOH solution on the surface of a decorative laminate and observing a change after 3 hours. In the stain resistance, adhesion properties and alkaline resistance, the evaluation was conducted according to the following criteria.

O: pass (no change was observed) x: fail (some change was observed) An impregnated paper was prepared by using the impregnating liquid of the present invention, and then a decorative laminate was molded under the same molding conditions as those used in case of a conventional short cycle melamine decorative laminate. As a result, it has been found that the resulting decorative laminate is extremely superior in gloss and wear resistance to the conventional short cycle melamine decorative laminate.

Thesurface of these decorative laminates was observed by a scanning electron microscope. As a result, remarkable unevenness caused by degassing was observed on the surface of the conventional decorative laminate, while the surface of the decorative laminate obtained in the present invention was smooth.

It is considered that good gloss in the present invention is attributed to the smoothness of the surface and good wear resistance is attributed to the thickness of the resin formed on the patterned surface of the titanium paper.

It is considered as follows. That is, regarding a high-pressure melamine decorative laminate, the formation of unevenness of the surface caused by a gas is prevented by increasing the pressure. Regarding the product of the present invention, the melt viscosity is increased and the pressure is uniformly applied by formulating the microgel emulsion. Therefore, the formation of unevenness of the surface caused by a gas can be prevented and thickness of the resin increases with an increase in viscosity.

O a Table 1. Data for production of decorative laminate Example 2 3 4 5 6 No- 1 7 8 9 10 11 Comparative 2 I lN N 1 AllAJI l: IU. I Emulsion No. 1 1 1 1 1 2 2 3 4 4 4 -1 1 Formulation DAP 25 25 25 25 25 50 50 75 50 50 50 25 EA 72.5 72.5 72.5 72.5 72.5 47.5 47.5 45 45 45 72.5 72.5 2-EtHA AA 2.5 2.5 2.5 2.5 2.5 2.5 2.5 5 5 5 2.5 Formulation of impregnating liquid (parts by weight of solid content) Melamine resin liquid 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Emulsion 0.6 5 10 20 10 2.5 5 5 5 10 5 0.1 Press conditions Hot plate temperature Molding pressure (kg/cm 2 Molding time (min) Physical properties of surface Gloss Pencil hardness Scratch hardness (ii) Wear value (times) Wear amount (mg) Stain resistance Adhesion properties Alkaline resistance 160 160 160 160 180 160 160 180 160 160 180 15 15 15 15 15 15 15 15 15 15 15 6 6 6 6 1 6 6 1 6 6 1 160 15 6 160 160 15 6 6 6 6 6 87 92 110 87 110 104 105 106 102 108 105 9H 8H 7H 7H 7H 8H 8H 8H 8H 8H 8H 2.2 2.6 3.2 6.8 3.4 2.5 2.7 2.9 2.6 2.8 2.6 290 320 430 320 420 340 390 390 360 440 340 23 23 23 23 23 23 23 23 21 20 22 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 83 9H 2.2 270 23 0 0 83 77 9H 6H 2.2 11.5 270 290 23 23 0 0 0 0 O 0 0 0 0 EFFECT OF THE INVENTION A decorative laminate having excellent gloss can be obtained, with maintaining good workability, by blending a diallyl phthalate emulsion with a melamine resin. Also, when using a melamine resin for the low-pressure molding, the good gloss obtained in case of using a melamine resin for the high-pressure molding can be obtained.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers or steps.

SS

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Claims (5)

1. A melamine resin composition comprising a copolymer microgel emulsion comprising diallyl phthalate and a vinyl compound, and a melamine resin solution, the amount (in terms of solid content) of the copolymer microgel emulsion being from 0.2 to 30 parts by weight based on 100 parts by weight of a melamine resin in the melamine resin solution.

2. The melamine resin composition according to claim 1, wherein a microgel of the copolymer microgel emulsion is a copolymer microgel containing to 90% by weight of diallyl phthalate.

3. The melamine resin composition according to claim 1 or 2, wherein the vinyl compound is selected from acrylate esters, methacrylate esters, vinylcarboxylic acids, acrylamides, methacrylamides, styrenes, a-methylstyrenes, vinyl ethers, vinyl esters, maleate esters, fumarate esters, vinylsilanes, acrylonitrile and methacrylonitrile, which optionally have a group selected from a silyl group, an epoxy group, a hydroxyl group, a carbonyl group, a N-methylol group, a N- alkoxymethylol group, a vinyl group and a halogen group.

4. A melamine resin composition substantially as hereinbefore described with reference to the Examples, but excluding the Comparative Examples.

5. A decorative laminate obtainable by impregnating an impregnation paper or fabric with the melamine resin composition of any one of claims 1 to 4, drying the impregnated paper or fabric, positioning the impregnated paper or fabric on a base material and conducting the hot-press molding. DATED this 18th day of November, 1999 Daiso Co., Ltd by DAVIES COLLISON CAVE Patent Attorneys for the Applicant(s)