AU623299B2 - Crosslinked resin particles and production thereof - Google Patents

Description

COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION (Original) '2 FOR OFFICE USE 3299&? Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: 0 o 0 4 00 *0 '0 t089 o t 88 0 00W44~ 00

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o II Name of Applicant: Address of Applicant: NIPPON PAINT CO., LTD.

2-1-2, Oyodokita, Kita-ku, Osaka-shi, Osaka-fu,

JAPAN

08 8 0 0 4* Actual Inventor(s): Address for Service: Hiroyuki SAKAMOTO Kenshiro TOBINAGA Yasuyuki TSUCHIYA Hisaichi MURAMOTO Yusuke NINOMIYA Keizou ISHII Shinichi ISHIKURA 8 00 00 0 0408 0 0 0- 0e DAVIES COLLISON, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

Complete Specification for the invention entitled: "CROSSLINKED RESIN PARTICLES AND PRODUCTION THEREOF" The following statement is a full description of this invention, including the best method of performing it known to us: la- FIELD OF THE INVENTION The present invention relates to crosslinked resin particles and a process for preparing the same.

BACKGROUND OF THE INVENTION Crosslinked resin particles are widely used for paint, molding, adhesive, ink, cosmetics and the like. They are prepared by various methods, such as grinding, emulsion polymerization, suspension polymerization, microcapsulating, spray drying and so on. Since each method has particular advantage, a suitable method is selected according to the S, application or resin type of the particles.

In veiw of particle size, each method has particular size renge. For example, the emulsion polymerization method produces particles of 0.01 to 0.3 micron, and the other methods produce relatively large particles of 5 to 100 micron. Thus, it is quite difficult 20 to produce particles of 0.1 to 10 micron.

o Accordingly, a method which produces particles of 0.01 to 50 micron, especially 0.1 to 10 micron in an industrial scale is desired.

I 9 tooe -2- SUMMARY OF THE INVENTION In our copending Australian Patent Application No. 37866/89, the contents of which are hereby incorporated by reference, we claim a process for preparing crosslinked resin particles which comprises dispersing a resin having both a water-dispersible function and a self-crosslinkable function in each molecule in an aqueous medium and then threedimensionally crosslinking it.

In the emulsion polymerization method, a crosslinking reaction occurs simultaneously with a polymerization of monomers. In the invention of AU 37866/89, a resin which has both water-dispersible function and crosslinkable function and which is not oooo crosslinked is dispersed in an aqueous medium, and then the inside of the dispersed resin particles is threeo dimensionally crosslinked to retain their particulate o shapes. The present invention is directed to a related 0o process and resin as follows.

In one embodiment of the present invention there is 0o provided a process for preparing an aqueous dispersion of o cationic crosslinked resin particles, comprising dispersing or emulsifying in an aqueous medium a cationic aqueous resin and a resin having at least two polymerizable vinyl groups and a number average oo molecular weight of 400 to 20,000, followed by radicalpolymerizing.

In a further embodiment of the present invention there is provided an aqueous dispersion of cationic crosslinked resin particles prepared by dispersing or emulsifying in an aqueous medium a cationic aqueous resin and a resin having at least two polymerizable vinyl groups and a number average molecular weight of 400 to 20,000, followed by radical-polymerizing.

92 mda 82a:\37866nip.div2 920213,!rnmdat.082,a:\37866nip.div,2 L i I -2a- The present invention additionally provides a cationic coating composition containing the above micro gel particles.

DETAILED DESCRIPTION OF THE INVENTION In the present invention, two different resins, i.e.

a cationic aqueous resin and a resin having at

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a 0 0 Io 0 g e i o I f o 920213,immdaO82,a:\37866nip.div,3 ~1 least two polymerizable vinyl groups and a number average molecular weight of 400 to 20,000, are employed. The cationic aqueous resin is generally employed as a filmforming resin in the formulation of a cationic electrocoating composition. The resin has cationic functional groups which give positive charges and reFerc y hydrophilic nature to the resin, such as amino groups. Such resins are known to the art and all of them can be used in the present invention. Preferred aqueous resins are an epoxy resin having amino groups and a polybutadiene resin having amino groups (hereinafter referred to as "aminated 4 polybutadiene").

The epoxy resin having amino groups may be prepared by reacting a polyglycidyl compound with a primary or 15 secondary amine. The polyglycidyl compound herein is meant an epoxy compound which has at least two glycidyl groups in one molecule. The compound may be obtained by reacting an aromatic or aliphatic alcohol with epihalohydrin. Such polyglycidyl compounds are commercially available, for example, bisphenol type from Toto-kasei K.K. as .Epototo YD- 011; aliphatic type from Nagase-kasei K.K. as Denacol EX-212 and from Toto-kasei K.K. as PGo-207; and phenol novolak type from Toto-kasei K.K. as Epototo YDPN-638. Examples of the primary or secondary amines to be added to the polyglycidyl compounds are primary amines, such as monomethylamine, monoethylamine, n-butylamine, monoethanolamine and the like; and secondary amines, such as dimethylamine, diethylamine, ~--I(.Yllil tl 4,diisopropylamine, N-methylethanolamine, N-ethylethanolamine, diethanolamine and the like. The amines may be diketimine which is obtained by dehydration-reation of diethylenetriamine and methyl isobutyl ketone. The amines generally are reacted with the polyglycidyl compounds in an equivalent amount approximately equal to an epoxy equivalent amount of the polyglycidyl compound.

The aminated polybutadiene may be prepared by oxidizing liquid polybutadiene having a molecular weight of 500 to 5,000 with an peroxide in an amount ratio sufficient to form 3 to 12 by weight of an oxirane oxygen atom, followed by reacting with a primary or secondary amine in an amount of 30 to 300 mmol per 100 g of the polybutadiene.

Details of such an aminated polybutadiene are described in Japanese Patent Publication (unexamined) Nos. 60273/1985 and 60274/1985. The polybutadiene can form an aqueous solution or aqueous dispersion by neutralizing an acid and then diluting with water.

If desired, the cationic aqueous resin may further contain polymerizable vinyl groups. The vinyl S"groups enhance storage stability by reacting with the component infra. The introduction of the vinyl groups is known. For example, an alpha, beta-unsaturated carboxylic acid represented by CH C C -OH I I II

R

1

R

2 0 wherein R 1 and R 2 respectively represent a hydrogen 5 atom or a methyl group, may be reacted with the above mentioned cationic aqueous resin The resin has at least two polymerizable vinyl groups in one molecule and a molecular weight of 400 to 200,000, preferably 1,000 to 10,000. A principal backbone of the resin can not be limited, but preferably epoxy resin, polyester resin, alkyd resin, polyurethane resin, amino resin and the like. The polymerizable vinyl groups can be introduced into the principal backbone by known methods.

For example, an epoxy group of an epoxy resin may be esterified by acrylic acid or methacrylic acid. A resin A I having less than two vinyl groups may be mixed with the resin in a sufficient amount not to adversely affect on the reactivity.

Preferably, the resin is crosslinkable at a temperature of less than 100 °C at normal pressures, because it is crosslinked in an aqueous medium. If the crosslinking S reaction is carried out in an autoclave, a resin which is reactive at a temperature of more than 100 OC can be employed. The crosslinking reaction is generally conducted in the presence of a radical polymerization catalyst.

4 A Examples of the catalysts are azo catalysts, such as .azobisisobutylonitrile; and peroxides, such as ketone peroxides and diacyl peroxides.

For lowering the viscosity of the resin composition of the aqueous resin and the crosslinking agent to L

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6 emulsify with ease, the aqueous medium may further contain an organic solvent. Examples of the organic solvent are a water-niscible organic solvent, such as ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, ethylene glycol dimethyl ether, diacetone alcohol, 4-methoxy-4-methylpentanone-2, acetone, methyl ethyl ketone, methoxy butanol, dioxane, ethylene glycol monoethyl ether acetate and the like; and a water-immiscible organic solvent, such as xylene, toluene, methyl isobutyl ketone, hexane, carbon tetrachloride, 2ethylhexanol, isophorone, cyclohexane, benzene and the like.

Where the resin composition containing the aqueous resin and the resin is emulsified in an aqueous medium, at least 20 mol of the amino group in the aqueous resin is primarily neutralized with an acid and then emulsified together with the resin and the aqueous medium. An amount of the resin may be 5 to 250 parts by weight based on 100 parts by weight of the aqueous resin calculated in terms of the solid content. Amounts of less than 5 parts by weight can provide micro gel particles. The acid for neutralizing the aqueous resin (A) includes acetic acid, propionic acid, lactic acid and the like.

-7- Desirably with the present invention, the resin is dispersed in an aqueous medium. In order to reduce to a viscosity sufficient to mechanically emulsify the resin, an organic solvent toluene, xylene, dichloroethane, chlorobenzene, cyclohexane etc.) can be mixed as a diluent in a suitable amount. According to the resin V type or viscosity characteristics, such organic solvent can be eliminated. By the term "aqueous medium" herein is meant water or a mixture of water and other watermiscible solvents lower alcohols, ethers etc.).

In order to produce composite resin particles, solid particles, such as pigments and drugs, are formulated into the dispersion.

The dispersion is then three-dimensionally crosslinked by means of light, heat and the like. The crosslinking reaction occurs within the dispersed particles and therefore the particles are crosslinked with keeping dispersing conditions.

The crosslinking reaction can be assisted by a 91 a a:\37 6ip.v7 So a 9l0225,immdat82a: \3866nip.div,7 8crosslinking catalyst and/or a polymerization initiator, if necessary. The crosslinking catalyst can be one promoting a reaction between the reactive groups in the resin, including a tirtiary amine tris(dimethylaminomethyl)phenol) where the reactive groups are a combination of oxirane and carboxyl. The polymerization initiator is generally a radical polymerization initiator, such as an azo initiator azobisisobutylonitrile), a peroxide ketone peroxides, allyl peroxides) and the like. The crosslinking reaction is generally carried out at a temperature of 20 to 110 OC, preferably 40 to 90 °C.

The obtained resin particles can be separated from r, the liquid component by removing the aqueous medium. The resin particles may be separated by salting out, spray drying, freeze drying and the like. The particles has a particle size of 0.01 to 50 micron, especially 0.1 to micron. If an aqueous emulsion of the resin particles is necessary, the organic solvent if used is removed from the S dispersion to form the aqueous emulsion. It may be prepared 44 t by dispersing the separated particles in another aqueous medium.

The resin particles can be used as a filler or functional particles for paint, ink, adhesive, mold, cosmetics. The coating containing the resin particles highly water-resistant, because an emulsifying agent is not employed when the resin is dispersed in the aqueous medium. If a part of the crosslinkable groups remains L f 9 during the crosslinking reaction, the resin particles solution has curing ability.

The obtained resin particles may be formulated into aqueous paint, especially cationic electrocoating paint. In addition to the resin particles, the aqueous paint generally contains a film-forming resin and a pigment. Examples of the pigments are color pigments, such as titanium dioxide, iron oxide red and carbon black; extender pigments, such as aluminum silicate and precipitated barium sulfate; corrosion preventive pigments, such as aluminum phosphomolybdate, strontium chromate, basic lead silicate and lead chromate.

Examples of the film-forming resins are an amine-modified S it epoxy resin, an amine-modified polybutadiene, polyether, polyester, polyurethane, polyaimide, phenol resin, acrylic I 15 resin and the like. The paint is classified by curing mechanism. The first is self-curing type by radical polymerization or oxidation polymerization, the second is curing agent type using such curing agent as melamine resin and blocked polyisocyanate and the third is combination type of the first and the second. The aqueous paint may further contain a water-insoluble resin, such as epoxyacrylate resin, to improve film properties. The aqueous paint is \a adjusted to a solid content of 10 to 20 and coated in a 'a dried thickness of 15 to 30 micron. The obtained film is a a 10 baked to cure. A number average molecular weight of the resin is preferably within the range of 500 to 1,000,000, more preferably 1,000 to 100,000 for paints.

4 0 .4 1 0 4 4 it 910225,unmdaLO8ZaA37866nip.div,10 11

EXAMPLES

The present invention is illustrated by the following examples which, however, are not to be construed as limiting the present invention to their details. In the examples, "part" and are based on weight unless otherwise indicated.

Reference Example 1 Preparation of a resin having both hydrophilic groups and crosslinkable groups A four neck 5 liter flask equipped with a stirrer, a condenser and a thermometer was charged with 720 parts of maleic polybutadiene (available from Nippon Soda Co., Ltd.

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as BN-1015), 735 parts of a 1:5 mol adduct of 2-hydroxy ,methacrylate and epsilon-caprolactone (available from Daicel 15 Chemical Industries, Ltd. as Plakcel FM-5, 365 parts of cyclohexanone and 0.1 part of hydroquinone, and reacted at 150 °C for one hour in air.

The obtained resin had a solid content of 80 an 0, average molecular weight of 2,920 and an acid value of 32..

Radical polymerizable double bonds were identified by IR spectrum.

Reference Example 2 0. Preparation of a resin having both hydrophilic St groups and crosslinkable groups A four neck 2 liter flask equipped with a stirrer, a condenser and a thermometer was charged with 192 parts of trimellitic anhydride, 130 parts of 2-hydroxy methacrylate, -RIVTr~-- TIIII~-- 12 100 parts of cyclohexanone and 0.1 part of hydroquinone, and reacted at 150 OC for 30 minutes in air. Then, 740 parts of polytetramethyleneglycol diglycidyl ether (available from Nagase Kasei Industries Ltd. as Denacol 992), 620 parts of cyclohexanone and 0.1 part of hydroquinone were added and reacted at 150 for one hour.

The obtained resin had a solid content of 80 an average molecular weight of 2,120 and an acid value of 53.

Radical polymerizable double bonds were identified by IR spectrum.

Reference Example 3 a Preparation of a resin having both hydrophilic groups and crosslinkable groups A four neck 2 liter flask equipped with a stirrer, c \15 a condenser, a nitrogen gas inlet and a thermometer was charged with 15 parts of methacrylic acid, 25 parts of glycidyl methacrylate, 50 parts of 1:23 mol adduct of methacrylic acid and ethylene oxide (available from Shinnakamura Chemical Co., Ltd. as NK-230), 200 parts of S 20 styrene, 160 parts of methyl methacrylate, 150 parts of nbutyl acrylate, 1 part of 2,2'-azobis(4-methoxy-2,4dimethylvalelonitrile) (available from Wako Junyaku Co., Ltd. as V-70) and 750 parts of cyclohexanone, and reacted at °C for 15 hours in a nitrogen atmosphere.

The obtained resin had a solid content of 40 an average molecular weight of 58,000 and an acid value of 18. Oxirane rings were identified by IR spectrum.

26 r' 13 Reference Example 4 Preparation of a resin having both hydrophilic groups and crosslinkable groups A four neck 2 liter flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a thermometer was charged with 500 parts of a xylene solution (solid content of polybutadiene polybutadiene with a presumed average molecular weight of 45,000 (available from Kuraray Co., Ltd.

as LIR-300), 30 parts of maleic anhydride and one part of Nphenyl-l,3-dimethylbutyl)-p-phenyldiamine (available from Ohuchi Shinko Chemical Industries Ltd. as NOCRAC 6C, and reacted at 190 OC for 6 hours in a nitrogen atmosphere.

The obtained maleic polybutadiene had an average molecular weight of about 48,00 and an acid value of 72.

Example Dispersing process One part of 2,2'-azobis-2,4-dimethylvaleronitrile S(available from Wako Junyaku Co., Ltd. as V-65) and 300 I parts of the resin of Reference Example 1 neutralized 100 20 with ammonia were uniformly mixed, to which 900 parts of 4 t deionized water was added and emulsified at 40 °C for minutes by a homogenizer.

Crosslinking process S'The obtained emulsion was charged to a 2 liter four neck flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a thermometer and reacted at 75 °C for one hour in a nitrogen atmosphere.

14 14 Removing organic solvent The obtained emulsion was subjected to an evaporation of the solvent at a pressure of 20 mmHg at The resultant resin emulsion contained resin particles of 0.28 micron determined by a laser light scattering method.

Example 2 Dispersing process One part of 2,2'-azobis-2,4-dimethylvaleronitrile (available from Wako Junyaku Co., Ltd. as V-65) and 300 parts of the resin of Reference Example 2 neutralized 60 I with dimethylethanolamine were uniformly mixed, to which 900 1i parts of deionized water was added and emulsified at 40 °C for 30 minutes by a homogenizer.

0 15 Crosslinking process 6 0 The obtained emulsion was charged to a 2 liter four neck flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a thermometer and reacted at 75 °C for one Gi, hour in a nitrogen atmosphere.

Removing organic solvent SThe obtained emulsion was subjected to an evaporation of the solvent at a pressure of 20 mmHg at 4 4«t IThe resultant resin emulsion contained resin Sparticles of 0.15 micron determined by a laser light scattering method.

Example 3 Dispersing process Two parts of tris(dimethylaminomethyl)phenol Iavailable from Anker Chemical Co., Ltd. as Ankamine K-54 and 300 parts of the resin of Reference Example 3 were uniformly mixed, to which 500 parts of deionized water was added and emulsified at 40 °C for 30 minutes by a homogenizer.

Crosslinking process The obtained emulsion was charged to a 2 liter three neck flask equipped with a stirrer, a condenser and a thermometer and reacted at 40 OC for 24 hours.

Removing organic solvent e a The obtained emulsion was subjected to an evaporation of the solvent at a pressure of 20 mmHg at The resultant resin emulsion contained resin 1. L5 particles of 6.68 micron determined by a laser light 0 00.

scattering method.

Example 4 o Dispersing process The resin of Reference Example 4 of 240 parts was 04 V diluted with 160 parts of xylene and then neutralized with ,dimethylethanolamine 100 The resultant solution and 2.4 parts of t-butylperoxide were uniformly mixed, to which 1,800.parts of deionized water and 200 parts of n-propyl alcohol were added and emulsified at 40 OC for 30 minutes by a homogenizer.

Crosslinking process The obtained emulsion was charged to a 2 liter four L 1_7r7CI~~ICII?-~-- iZ- r i r 11_11~-- 16 neck flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a thermometer and reacted at 60 OC for 6 hours in a nitrogen atmosphere by adding 2.4 parts of tetramethylenepentamine as a reducing agent.

Removing organic solvent The obtained emulsion was subjected to an evaporation of the solvent at a pressure of 20 mmHg at The resultant resin emulsion contained resin particles of 0.20 micron determined by a laser light scattering method.

Reference Example Preparation of a resin having both hydrophilic groups and crosslinkable groups j°n, To 200 parts of an 80 cyclohexanone solution of 0 1i I 15 polytetramethylene glycol (available from Sanyo Kasei Co., Ltd. as PTMG 1,000) were added dropwise using a dropping -4 funnel 35.9 parts of itaconic anhydride and reacted 150 °C for one hour. The obtained resin had a solid content of 83 and an average molecular weight of 1,200. Polymerizable double bonds are identified by an IR spectrum.

Example Dispersing process 1.6 part of 2,2'-azobis-2,4-dimethylvaleronitrile (available from Wako Junyaku Co., Ltd. as V-65) and 200 25 parts of the resin of Reference Example 5 neutralized 100 with ammonium were uniformly mixed, to which 500 parts of 1_ 1 1 i.r i -17i deionized water was added and emulsified at 40 °C for minutes by a homogenizer.

Crosslinking process The obtained emulsion was charged to a one liter three neck flask equipped with a stirrer, a condenser and a thermometer and reacted at 75 °C for one hour in a nitrogen atmosphere.

Removing organic solvent The obtained emulsion was subjected to an evaporation of the solvent at a pressure of 20 mmHg at The resultant resin emulsion contained resin particles of 0.34 micron determined by a laser light scattering method.

Example 6 15 The emulsions of Examples 1 to 5 was subjected to a storage stability test at 25 °C for 3 months, but no 4t separation and sedimentation were observed. All emulsion had good storage stability.

Example 7 Three parts of calcium chloride was added in the emulsion of Example 1 to agglomerate particles which were separated from the aqueous medium by a reduced pressure filtrate method. The obtained particles were dried at 40 °C .I and 1-2 nmHg for 12 hours to obtain dried particles of about 25 300 parts.

Example 8 The emulsion was frozen at -50 °C and dried by 18 freeze-drying to obtain dried particles of about 300 parts.

Reference Example 6 Preparation of polybutadine having amino groups Polybutadiene having an average molecular weight of 2,000 and 1.2 bond of 65 (available from Nippon Oil Company Ltd. as Nisseki Polybutadiene B-2,000) was treated with peracetate to obtain epoxidized polybutadine having an oxirane oxygen content of 6.4 A 2 liter autoclave was charged with 1,000 g of the epoxidized polybutadiene and 354 g of ethyleneglycol monoethyl ether, to which 62.1 g of dimethylamine was added and reacted at 150 OC for 5 hours. After distilling unreacted amine away, it was cooled to 120 °C and a mixture of 79.3 g of acrylic acid, 7.6 g of hydroquinone and 26.4 g I" 15 of ethyleneglycol monoethyl ether was added and reacted at 120 °C for 3-3/4 hours. The obtained resin had an amine 4 I value of 85.2 mmol/100 g, an acid value of 10.0 mmol/100 g and a solid content of 75.0 Reference Example 7 Preparation of aminated epoxy resin 1,900 parts of Epicot 1004 (bisphenol type epoxy St resin having an epoxy equivalent of 950 available from Yuka Shell Epoxy Co., Ltd.) was dissolved in 685.3 parts of xylene, to which 112.7 parts of n-methylethanolamine was added and reacted at 130 °C for three hours.

Thereafter, 2.1 parts of hydroquinone and 0.6 parts of quinone were added and mixed and, after an addition of -19 43.1 parts of methacrylic acid, reacted at 110 oC for three hours. Then, 216 parts of methyl isobutyl ketone was added to obtain an aminated epoxy resin. The resin had an amine value of 73 mmol/100 g solid and a solid content of 70 Example 9 Eighty parts of the aminated polybutadiene of Reference Example 6 was mixed with 2.0 parts of glacial acetic acid at 55 OC and 3.0 parts of azobisisobutylonitrile was then added and mixed. Then, 215 parts of deionized water was added thereto and emulsified to form a resin emulsion. The resin emulsion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 for three days and cooled to form a cationic resin particle dispersion. This I' 15 dispersion was not dissolved in tetrahydrofurane to form a o white semiopaque solution.

o A degreased polished steel panel was cationically electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 OC for 20 minutes to S 20 form a clear coating of 20 micron. A 60 o gloss was evaluated and the result is shown in Table 1.

o Example One hundred parts of the aminated epoxy resin of Reference Example 7 was mixed with 3.0 parts of glacial 25 acetic acid at 55 OC and 2.0 parts of azobisisobutylonitrile was then added and mixed. Then, 362 parts of deionized water was added thereto and emulsified to form a resin L_ 1 20 emulsion. The resin emulsion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 for three days and cooled to form a cationic resin particle dispersion. This dispersion was not dissolved in tetrahydrofurane to form a white semiopaque solution.

A degrease polished steel panel was cationically electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 OC for 20 minutes to form a clear coating of 20 micron. A 60 O gloss was evaluated and the result is shown in Table 1.

Table 1 Examples 60 O Gloss 1 1 2 12 1 Gloss was measured at an incidence angle of 60 o Reference Example I Aminated polybutadiene A An epoxidized polybutadiene having an oxirane oxygen atom of 6.4 was prepared by epoxidizing polybutadiene having a number average molecular weight of 2,000 and 1,2-bond of 65 (available from Nippon 44 Petrochemicals Co. Ltd. as Nisseki Polybutadiene B-2000) 25 with peracetate.

Next, 1,000 g of the epoxidized polybutadiene and 354 g of ethylene glycol monoethyl ether were charged in a 2 L 1 21 liter autoclave and 62.1 g of dimethylamine was added to react at 150 OC for 5 hours. Unreacted dimethylamine was removed by distillation to obtain an aminated polybutadiene. The aminated polybutadiene had an amine value of 120 mmol/100 g (solid content) and a nonvolatile content of 75 Reference Example II Epoxyacrylate resin B One thousand parts of a bisphenol type epoxy resin having an epoxy equivalent of 950 (available from Yuka Shell Epoxy Co., Ltd. as Epicoat 1,004) was dissolved in 343 parts of ethyleneglycol monoethyl ether, to which 76.3 parts of S' acrylic acid, 10 parts of hydroquinone and 5 parts of N,Ndimethylamino ethanol were added and reacted at 100 °C for ti hours to obtain a resin solution. The resin had an acid value of 2 mmol/100 g and a solid content of 75 Example I Eighty parts of the aminated polybutadiene A of Reference Example I was mixed with 53.3 parts by weight of S 20 the epoxy acrylate resin of Reference Example II, and then mixed with 2.0 parts of glacial acetic acid. Next, I parts by weight of azobisisobutylonitrile was added and mixed. Deionized water was added thereto and emulsified to form a resin emulsion A. The resin emulsion was 25 transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 °C for 7 days and cooled to form a cationic resin particle dispersion. This *22dispersion was not dissolved in tetrahydrofurane to form a white semiopaque solution.

A tin plate was dipped in the dispersion having a solid content of 10 and taken out. The plate was dried in the air and dried at room temperature and a reduced pressure. It was then observed by a microscope to find resin particles having less than 100 nm on the surface.

A degreased steel panel was cationically electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 OC for 20 minutes to form a clear coating of 20 micron. A 60 o gloss was evaluated and the result is shown in Table 2.

S. Example II Eighty parts of the aminated polybutadiene A of Reference Example I was mixed with 40 parts of isocyanuric acid triacrylate (available from Toagosei Chemical Industry Co., Ltd. as Aeronix M-315) at 55 OC, to which 2.0 parts of glacial acetic acid was added and mixed. Then, 3.0 parts of azobisisobutylonitrile was mixed and deionized water was added to form a resin emulsion B. The resin emulsion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 40 OC for 7 days and cooled to form a cationic resin particle dispersion. This 0: dispersion was not dissolved in tetrahydrofurane to form a S. 25 white semiopaque solution.

A degreased steel panel was cationically electrocoated in the above obtained cationic dispersion.

L i I* The coated article was baked at 170 OC for 20 minutes to form a clear coating of 20 micron. A 60 O gloss was evaluated and the result is shown in Table 2.

Reference Example III Aminated polybutadiene C An epoxidized polybutadiene having an oxirane oxygen atom of 6.4 was prepared by epoxidizing polybutadiene having a number average molecular weight of 2,000 and 1,2-bond of 65 (available from Nippon Petrochemicals Co. Ltd. as Nisseki Polybutadiene B-2000) with peracetate.

Next, 1,000 g of the epoxidized polybutadiene and 354 g of ethylene glycol monoethyl ether were charged in a 2 liter autoclave and 62.1 g of dimethylamine was added to react at 150 OC for 5 hours. After removing unreacted dimethylamine by distillation, the resultant product was 4 t cooled to 120 OC and a mixture containing 79.3 g of acrylic acid, 7.6 g of hydroquinone and 26.4 g of ethylene glycol monoethyl ether was added to be allow to react at 120 OC for S 20 3-3/4 hours. The aminated polybutadiene had an amine value of 85.2 mmol/100 g (solid content), an acid value of 10.0 xmmol/100 g and a solid content of 75.4 Example III r A cationic crosslinked resin particle dispersion t 25 was prepared as generally described in Example II, with the exception that the aminated polybutadiene C of Reference Example III was employed instead of that of Reference

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S-'24- Example I. The resin dispersion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 40 °C for 5 days and cooled to form a cationic resin particle dispersion. This dispersion was not dissolved in tetrahydrofurane to form a white semiopaque solution.

Reference Example IV Firstly, 1,900 parts of a bisphenol type epoxy resin having an epoxy equivalent of 950 (available from Yuka Shell Epoxy Company as Epicoat 1,004) was dissolved in 685.3 parts of xylene, to which 112.7 parts of nmethylethanolamine was added and reacted at 130 OC for 3 hours.

To the resultant solution, 2.1 parts of hydroquinone and 0.6 parts of quinore were added. After the completion of mixing, 43.1 parts of methacrylic acid was added and reacted at 110 OC for 3 hours, to which 216 parts of methyl isobutyl ketone was added to from an aminoepoxy resin C. The resin had an amine value of 73 mmol/100 g (solid) and a solid content of 70 Example IV Eighty parts of the aminated polybutadiene C of Reference Example III was mixed with 40.0 parts by weight of nitrile-modified polybutadiene, and then mixed with 1 25 parts of glacial acetic acid. Next, 3.0 parts by weight of azobisisobutylonitrile was added and mixed. Deionized water was added thereto and emulsified to form a resin emulsion A. The resin emulsion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 OC for 3 days and cooled to form a cationic resin particle dispersion. This dispersion was not dissolved in tetrahydrofurane to form a white semiopaque solution.

A degreased steel panel was cationically electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 OC for 20 minutes to form a clear coating of 20 micron. A 60 0 gloss was evaluated and the result is shown in Table 2.

Example V o oo Sp 143 parts of the aminated polybutadiene D of oao S" Reference Example IV was mixed with 80 parts of isocyanuric 0 0 acid triacrylate (available from Toagosei Chemical Industry o Co., Ltd. as Aeronix M-315) at 55 OC, to which 2.0 parts of glacial acetic acid was added and mixed. Then, 3.0 parts of azobisisobutylonitrile was mixed and deionized water was added to form a resin emulsion. The resin emulsion was 20 transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 °C for 3 days and o Scooled to form a cationic resin particle dispersion. This dispersion was not dissolved in tetrahydrofurane to form a o. white semiopaque solution.

25 A degreased steel panel was cationically electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 °C for 20 minutes to S26form a clear coating of 20 micron. A 60 gloss was evaluated and the result is shown in Table 2.

Comparative Example I Example I was repeated with the exception that azobisisobutylonitrile was not employed. The obtained dispersion was dissolved in tetrahydrofurane even after keeping at 55 °C for 7 days.

Comparative Example II Example II was repeated with the exception that azobisisobutylonitrile was not employed. The obtained dispersion was dissolved in tetrahydrofurane even after keeping at 55 OC for 7 days.

Comparative Example III Example III was repeated with the exception that azobisisobutylonitrile was not employed. The obtained dispersion was dissolved in tetrahydrofurane even after keeping at 40 °C for 7 days.

Reference.Example V Firstly, 1,900 parts of a bisphenol type epoxy resin having an epoxy equivalent of 950 (available from Yuka i Shell Epoxy Company as Epicoat 1,004) was dissolved in 685.3 I parts of xylene, to which 112.7 parts of n- I methylethanolamine was added and reacted at 130 OC for 3 hours. To the resultant solution, 225.6 parts of methyl isobutyl ketone was added to from an aminoepoxy resin E.

The resin had an amine value of 146 mmol/100 g (solid) and a solid content of 70 S' -27 Reference Example VI Firstly, 3760 parts of a bisphenol type epoxy resin having an epoxy equivalent of 188 (available from Toto Kasei Company as Epototo 128R) was dissolved in 154.4 parts of ethyleneglycol monoethyl ether, to which 10 parts of hydroquinone and 5 parts of N,N-dimethylamino ethanol was added and heated at 90 OC. To the resultK.r' solution, 72.1 parts of acrylic acid was added. After the completion of the addition, it was heated to 100 OC for 3 hours to obtain an epoxy acrylate resin F. The resin had an acid value of 7 mmol/100 g (solid) and a solid content of 70 Example

VI

One hundred and forty three parts of the aminated polybutadiene D of Reference Example IV was mixed with 107 parts by weight of the epoxy acrylate resin B of Reference I Example II at 55 OC, and then mixed with 3.0 parts of glacial acetic acid. Next, 2.0 parts by weight of azobisisobutylonitrile was added and mixed. Deionized water was added thereto and emulsified to form a resin emulsion.

The resin emulsion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 OC for 3 days and cooled to form a cationic.resin particle dispersion. This 2. l dispersion was not dissolved in tetrahydrofurane to form a S 25 white semiopaque solution.

A degreased steel panel was cationically electrocoated in the above obtained cationic dispersion.

L r 28 The coated article was baked at 170 OC for 20 minutes to form a clear coating of 20 micron. A 60 0 gloss was evaluated and the result is shown in Table 2.

Example VII One hundred and forty three parts of the aminated polybutadiene E of Reference Example V was mixed with 107 parts by weight of the epoxy acrylate resin B of Reference Example II at 55 OC, and then mixed with 3.0 parts of glacial acetic acid. Next, 2.0 parts by weight of azobisisobutylonitrile was added and mixed. Deionized water was added thereto and emulsified to form a resin emulsion.

The resin emulsion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 °C for 3 days and cooled to form a cationic resin particle dispersion. This dispersion was not dissolved in tetrahydrofurane to form a white semiopaque solution.

A degreased steel panel was cationically electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 °C for 20 minutes to form a clear coating of 20 micron. A 60 O gloss was evaluated and the result is shown in Table 2.

Example VIII Eighty parts of the aminated polybutadiene C of Reference Example III was mixed with 53.3 parts by weight of the epoxy acrylate resin of Reference Example II, and then mixed with 2.0 parts of glacial acetic acid. Next, Tnr*r I

I__LIL

S- 29 parts by weight of azobisisobutylonitrile was added and mixed. Deionized water was added thereto and emulsified to form a resin emulsion A. The resin emulsion was transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 °C for 3 days and cooled to form a cationic resin particle dispersion. This dispersion was not dissolved in tetrahydrofurane to form a white semiopaque solution.

A degreased steel panel was cationically electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 OC for 20 minutes to form a clear coating of 20 micron. A 60 0 gloss was evaluated and the result is shown in Table 2.

Example IX Eighty parts of the aminated polybutadiene C of Reference Example III was mixed with 53.3 parts by weight of the epoxy acrylate resin F of Reference Example VI, and then mixed with 2.0 parts of glacial acetic acid. Next, parts by weight of azobisisobutylonitrile was added and mixed. Deionized water was added thereto and emulsified to form a resin emulsion A. The resin emulsion was 4 4 transparently dissolved in tetrahydrofurane.

The emulsion was kept at 55 °C for 3 days and Sicooled to form a cationic resin particle dispersion. This dispersion was not dissolved in tetrahydrofurane to form a white semiopaque solution.

A degreas a steel panel was cationically j; ii j1i a i: 'j -i

MMM&MMA

U

30 electrocoated in the above obtained cationic dispersion.

The coated article was baked at 170 °C for 20 minutes to form a clear coating of 20 micron. A 60 8 gloss was evaluated and the result is shown in Table 2.

Comparative Example IV Example VI was repeated with the exception that azobisisobutylonitrile was not employed. The obtained dispersion was dissolved in tetrahydrofurane even after keeping at 55 OC for 7 days.

I i 1r 0 40o 4 L *f t I 31 Table 2 Examples J 60 0 Glossi IV 14 V 13 VII VIII 13 Ix 11 Comparative Example I II 42 111 52 IV 48 q t 1 Gloss was measured at an incidence angle of 60 8 4 4 444% 4' 44 4 4 t4 4 4 74 4 I 44 4 44

Claims (12)

1. An aqueous dispersion of cationic crosslinked resin particles prepared by dispersing or emulsifying in an aqueous medium a cationic aqueous resin and a resin having at least two polymerizable vinyl groups and a number average molecular weight of 400 to 20,000, followed by radical-polymerizing.

2. The aqueous dispersion according to claim 1 wherein said cationic aqueous resin is an epoxy resin having amino groups or a polybutadiene resin having amino groups.

3. The aqueous dispersion according to claim 1 wherein said cationic aqueous resin further contains polymerizable vinyl groups.

4. The aqueous dispersion according to any preceding claim wherein said resin is crosslinkable at a temperature of less than 100 OC at normal pressures.

The aqueous dispersion according to any preceding claim wherein said crosslinking reaction is conducted in the presence of a radical polymerization catalyst.

6. A process for preparing an aqueous dispersion of cationic crosslinked resin particles, comprising dispersing or emulsifying in an aqueous medium a cationic aqueous resin and a resin having at least two polymerizable vinyl groups and a number average molecular weight of 400 to 20,000, followed by radical- polymerizing.

7. The process according to claim 6 wherein said cationic aqueous resin is an epoxy resin having amino 910225,immdaLO2.a:\37866nip.div,32 W 71, -32- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. An aqueous dispersion of cationic crosslinked resin particles prepared by dispersing or emulsifying in an aqueous medium a cationic aqueous resin and a resin having at least two polymerizable vinyl groups and a number average molecular weight of 400 to 20,000, followed by radical-polymerizing. 2. The aqueous dispersion according to claim 1 wherein said cationic aqueous resin is an epoxy resin having amino groups or a polybutadiene resin having amino groups. 3. The aqueous dispersion according to claim 1 wherein said cationic aqueous resin further contains polymerizable vinyl groups. 4. The aqueous dispersion according to any preceding claim wherein said resin is crosslinkable at a temperature of less than 100 °C at normal pressures. The aqueous dispersion according to any preceding 0 claim wherein said crosslinking reaction is conducted in the presence of a radical polymerization catalyst. S6. A process for preparing an aqueous dispersion of cationic crosslinked resin particles, comprising dispersing or emulsifying in an aqueous medium a cationic aqueous resin and a resin having at least two polymerizable vinyl groups and a number average molecular weight of 400 to 20,000, followed by radical- polymerizing. 7. The process according to claim 6 wherein said cationic aqueous resin is an epoxy resin having amino 910225,immda08ZaA37866nip.div,32 _I_ -33- groups or a polybutadiene resin having amino groups.

8. The process according to claim 6 wherein said cationic aqueous resin further contain polymerizable vinyl groups.

9. The process according to any one of claims 6 to 8 wherein said resin is crosslinkable at a temperature of less than 100 *C at normal pressures.

The process according to any one of claims 6 to 8 wherein said crosslinking reaction is conducted in the i presence of a radical polymerization catalyst.

11. An aqueous coating composition containing the aqueous dispersion of cationic crosslinked resin particles according to any one of claims 1 to

12. An aqueous dispersion of crosslinked resin particles according to claim 1, or methods for their manufacture, substantially as hereinbefore described with reference to the examples. Thp tepq,- fPaturTR, compositions and compounds disclosed herein or referred to or indicated in-the specification and/or claims of this-application, individually or collect' j and any and all combination any two or more of said steps or DATED this 25th day of February 1991. NIPPON PAINT CO., LTD. By Its Patent Attorneys DAVIES COLLISON 910225,immdatO82,a:\37866nip.div,33