GB2151637A - Branched type acrylic resin - Google Patents

Abstract

A branched type acrylic resin having the formula: <IMAGE> wherein R is aliphatic, alicyclic, aromatic or heterocyclic hydrocarbon residue; X is acrylic prepolymer chain and n is a real number of 2 to 6, and having a weight average molecular weight of 2000 to 200000 and a glass transition point of -20 DEG C to 100 DEG C. The resin is prepared by reacting a carboxy- terminated acrylic resin with a polyglycidyl compound. e.g. a polyglycidyl ether of diglycerol, trimethylolpropane or pentaerythritol. The resin may be further modified. e.g. by reaction at the hydroxyl group with succinic or phthalic anhydride or with propane sulfone. The products are used in coating compositions.

Description

SPECIFICATION Branched type acrylic resin, its preparation and resinous for coating use The present invention relates to a novel branched type acrylic resin, its preparation and coating resinous composition containing the same. The invention also extends to the technique for modifying said resin to improve pigment dispersibility thereof.

Heretofore, as a paint resin, have been widely used an acrylic resin, an alkyd resin and a polyester resin. Among them, particular interest has been concentrated to an acrylic resin because of its excellent durability as weathering resistance, chemical resistance and the like and its coating appearance as gloss and the like. However, the acrylic resins which fulfil the abovesaid requirements are in general of a higher molecular weight as compared with those of alkyd resins and polyester resins customarily used in coating compositions and therefore, at the same dilution rate, there result must viscose solutions. Thus, there is a drawback of being hardly formulated into a higher non-volatile content.

According to the latest social needs of the least public hazard and minimum energy consumption, it is of course preferred that the amount of solvent in a coating composition is as low as possible. Therefore, it has been longed to have a resin with the lowest viscosity, measured at the same level of non-volatile content, within the limits of possibility.

For lowering the viscosity of acrylic resin, the following are generally accepted. That is, the first one is to lower the molecular weight of the acrylic resin itself and the second one is to copolymerize a monomer having a good solubility. However, in the former, there is a tendency that the characteristic durability i.e. weathering resistance, chemical resistance and the like, of acrylic resin, be lowered, and in the latter, there are such drawbacks that solvent resistance and mechanical strength are lowered because of the use of easily soluble monomer.

The inventors, having paid attention to the fact that the heretofore proposed techniques did not take any account of three-dimensional structure of the resin, have made endeavored to make clear the correlation between the structural features and physico-chemical properties of the acrylic resin and have succeeded in comming to the invention.

Thus, a principal object of the invention is to provide an acrylic resin, whose composition is very similar to those of the resins heretofore proposed for coating use and whose viscosity is very low, without the necessity of lowering the molecular weight thereof.

An additional object of the invention is to provide an acrylic resin having an excellent pigment dispersibility hereinafter stated minutely.

The principal object of the invention can be achieved by the present novel branched type acrylic resin having the formula:

wherein R is aliphatic, alicyclic, aromatic or heterocyclic hydrocarbon residue; X is acrylic prepolymer chain, and n is a real number of 2 to 6, and having a weight average molecular weight (Gel permeation chromatography, polystyrene conversion) of 2000 to 200,000 and a glass transition point of - 20"C to 1 00 C.

The said novel resin can be advantageously prepared by the present method comprising reacting a polyfunctional epoxy compound of the formula:

wherein R and n are as defined above, with an acrylic prepolymer having an end carboxyl group of the formula: X-COOH wherein X is acrylic prepolymer chain having a weight average molecular weight of 1000 to 100,000 and a glass transition point of - 20 to 1 00 C, and is very useful as resinous vehicle in coating composition.

To attain the additional object, the invention provides a novel, branched type acrylic resin which is composed of branched acrylic resin of the formula:

to which is beared an electron accepting group and/or electron donating group.

In obtaining the present novel acrylic resin, a poly functional epoxy compound having 2 and more glycidyl groups is used as a nuclear substance, the glycidyl groups of which are reacted with carboxyl group of the acrylic prepolymer of the formula: X-COOH, thereby forming a star polymer with the epoxy compound as a nuclear substance.

Therefore, in this novel type of acrylic resin, it is thought that lowering of viscosity has been attained by the combination of solubility derived from the poly functional epoxy compound used as nuclear substance and star structure of the resinous molecule.

An additional advantage of the present novel acrylic resin resides in the point that since the skeleton portion of end carboxyl bearing acrylic prepolymer can be composed of any combination of monomers other than carboxyl containing monomer customarily used for the preparation of acrylic resins for coating use, the star polymer may be possessed of very similar chemical composition with those of conventional coating acrylic resins, and hence, no significant diffence in film properties, as compared with those of the conventional resins, might be produced.

In obtaining the carboxyl bearing acryl prepolymer, polymerization of selected monomer(s) other than carboxyl containing monomer is first initiated with a conventional initiator as, for example, azo-nitrile compound (e.g. 2,2'-azo-bis-isobutyro-nitrile, 1 , 1 '-azo-bis-1 -cyclobutane nitrile, 2,2'-azo-bis-2-methylbutyronitrile and the like), azo compound (e.g. 2,3-diazo-bicy clo[2,2, 1 3-heptene-2, 2,2'azo-bispropane, l,l'-azo-bis-l -phenyi ethane and the like) and peroxide compound (e.g. t-butyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide), and then carboxyl group is introduced to the acryl prepolymer by using, as chain transfer agent, carboxyl containing compound as, for example, mercapto acetic acid. 2-mercapto propionic acid, 3-mercapto propionic acid, O-mercapto benzoic acid and the like (Method 1).

Alternatively, carboxyl group may be introduced in the acryl prepolymer by initiating the polymerization of monomer(s) other than carboxyl containing monomer with carboxyl containing initiator as, for example, 4,4'-azo-bis(4-cyano-pentanoic acid), diglutaric peroxide and the like (Method 2).

Such monomers other than carboxyl containing monomer to be used for the polymerization of acryl prepolymer are divided into two groups-neutral monomer and functional group containing monomer.

Examples of said neutral monomer are ethylene, propylene, butadiene, isoprene, chloroprene, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, methyl vinyl ether, acrylic esters (e.g. methyl, ethyl, butyl esters), methacrylic esters (e.g. methyl, ethyl, butyl esters), nitrile derivatives (e.g. acrylonitrile, methacrylonitrile and the like), styrene, styrene derivatives (e.g. amethyl styrene) and the like.

As an example of functional group containing monomer, mention is made of amide group containing monomers as acrylamide, methacrylamide and the like, alkoxy containing monomers as N-methoxy methylol acrylamide, N-butoxymethylolacrylamide and the like, hydroxy containing monomers as 2-hydroxy ethylacrylate, 2-hydroxypropylacrylate, 2-hydroxyethyl methacrylate, 2hydroxypropyl methacrylate, N-methylolacrylamide and the like.

In the polymerization of such acryl prepolymer, any of the known techniques of bulk polymerization, solution polymerization and if desired suspension polymerization and the like may be used, coupled with at once charging system, initiator dropping system or monomer dropping system.

The reaction is usually carried out at a temperature of more than the decomposition temperature of used initiator, generally at 70"C to 1 70 C, for 1 to 8 hours.

The amount of carboxyl group containing chain transfer agent used in the aforesaid Method 1 for the introduction of end carboxyl group, is usually in a range of 0.2 to 8% by weight, preferably 0.3 to 5% by weight, of the prepolymer solid weight. On the other hand, in the Method 2 using carboxyl group containing initiator, the amount of said initiator is customarily in a range of 0.3 to 12% by weight, preferably 0.4 to 8% by weight, of the prepolymer solid weight.

If the amount of carboxyl containing chain transfer agent exceeds over said 8% by weight in the Method 1, or the amount of carboxyl containing initiator exceeds over said 12% by weight in the Method 2, there is an extreme lowering of the molecular weight of prepolymer and hence of acryl resin, with the resultant of failure in obtaining an improved durability as weathering resistance, chemical resistance and the like. On the other hand, if the amount of carboxyl containing chain transfer agent is less than the lower limit of 0.2% by weight or the amount of carboxyl containing initiator is less than the lower limit of 0.3% by weight, there is an extreme increase in the molecular weight of prepolymer and hence of acryl resin, which will cause an increase in viscosity to the extent of being unable to use as resinous vehicle in a coating composition.

There is also a lowering of reactivity of the prepolymer with the glycidyl group of the polyfunctional epoxy compound, and hence, the synthesis of acryl resin may take a longer duration of time. To attain the object of the invention, i.e. provision of acrylic resin having a lower viscosity without sacrificing the desirous properties as weathering resistance, chemical resistance, solvent resistance, mechanical strength and the like, the acryl prepolymer should preferably have a weight average molecular weight (Gel permeation chromatography, polystyrene conversion) of 1000 to 100,000 and a glass transition point of - 20"C to 1 00 C. Thus obtained acryl prepolymer having end carboxyl group is then reacted with the glycidyl group of poly functional epoxy compound which bears more than 2 glycidyl groups, to obtain the present novel star polymer.

As the abovesaid poly functional epoxy compound, any of the members belonging to saturated or unsaturated, aliphatic, alicyclic, aromatic and heterocyclic compounds may be used providing having 2 and more of glycidyl groups. They may be substituted with such groups as chlorine, hydroxyl group, ether group and the like and may be either monomeric or polymeric compounds.

The present polyfunctional epoxy compound may include epoxidated esters of aliphatic polybasic acids with unsaturated monohydric alcohols as, for example, di(2,3-epoxy hexyl)adipate, di(2,3-epoxy butyl)oxalate, di(2,3-epoxy hexyl) succinate, di(2,3-epoxy butyl)phthalate and the like, and glycidyl containing nitrogenous compound as for example diglycidyl aniline, di- and tri-glycidyl amine and the like.

Particularly preferable poly functional epoxy compounds are glycidyl ethers and especially glycidyl ethers of poly hydric phenols or poly hydric alcohols.

Glycidyl ethers of poly hydric phenols and of poly hydric alcohols may be obtained by the reaction of epichlorohydrine with the selected poly hydric phenols or alcohols. Examples of such glycidyl ethers are diglycidyl ether of bisphenol A, diglycidyl ether of resorcinol, triglycidyl ether of fluoroglucitol, triglycidyl ether of trihydroxydi biphenyl, polyglycidyl ether of O-cresol formaldehyde novolak, diglycidyl ether of butanediol, diglycidyl ether of polypropyleneglycol, diglycidyl ether of neopentyl glycol, triglycidyl ether of glycerin, triglycidyl ether of trimethylol propane, tetraglycidyl ether of pentaerythritol, polyglycidyl ether of sorbitol and the like. Other polyfunctional epoxy compounds include diglycidyl isophthalate, diglycidyl phthalate, diglycidyl ether of linolic dimer acid, triglycidyl isocyanurate, tetraphenylolethane epoxy and the like.

The reaction between the poly functional epoxy compound having 2 and more glycidyl groups and end carboxyl bearing acryl prepolymer may be carried out,, in the molar ratio of glycidyl groups in poly functional epoxy compound to carboxyl groups in end carboxyl bearing acryl prepolymer of 1:0.6 to 1:1.4, preferable 1:0.8 to 1:1.2, if desired in the presence of a solvent which is inert to glycidyl or carboxyl group, at 80"C to 1 80 C, preferable 1 00 C to 1 60 C, until the reaction rate of 80% and more, measured and determined by the acid value of unreacted carboxyl groups in the end carboxyl bearing acryl prepolymer.

In the reaction of said glycidyl and carboxyl groups, one may use a reaction catalyst as, basic catalyst, if desired. Examples of such basic catalysts are organic amines as pyridine, isoquinoline, quinoline, N,N-dimethylcyclohexylamine, a-picoline tri-n-butyl amine, triethyl amine, N-ethyl morpholine, N, N-dimethylaniline, N-(fi-hydroxyethyl)amine, N-ethyl-3. 5-dimethyl morpholine, dimethyl coconut amine and the like, and inorganic amines as sodium hydroxide, potassium hydroxide and the like. Thus obtained acryl resin has a star structure, the nucleus being composed of poly functional epoxy compound from which acryl prepolymer chains extend outwardly via

bonding obtained by the reaction of glycidyl group of said epoxy compound with carboxyl group of the acryl prepolymer.

To attain the object of lowering of viscosity without sacrificing the desired properties as weathering resistance, chemical resistance, solvent resistance, mechanical strength and the like, thus obtained acryl resin should preferably have a weight average molecular weight of 2000 to 200,000 and a glass transition temperature of - 20"C to 1 00 C.

In formulating an acrylic clear paint, the present novel acryl resin may be used alone or in the combination with other resin as, for example, acryl resin (outside the invention), alkyd resin, polyester resin, polyether resin, cellulose nitrate, urethane resin, vinyl acetate resin, polyvinyl alcohol resin, vinyl chloride resin, and/or curing agent as phenol resin, melamine resin, isocyanate compound, epoxy resin and the like. In the actual operation, one may use an organic solvent customarily used in the coating composition as, for example, hydrocarbon solvents (e.g.

toluene, xylene, Solvesso 100, Solvesso 1 50 and the like), esters (e.g. ethylacetate, butyl acetate, celloslve acetate, carbitol acetate and the like), ketones (e.g. methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone and the like), alcohols (e.g. n-propanol, nbutanol, isobutanol, methyl isobutyl carbinol, cyclohexanol and the like), etheralcohol and ethers (e.g. methyl Cellosolve, Cellosolve, butyl Cellosolve, butyl carbitol, dioxane and the like), and may add a surfactant as silicone, fluorin, acrylic, polyether series surfactants.

When it is intended to use as an acrylic enamel paint, the desired inorganic or organic pigments are compounded with the present acryl resin or the resinous composition containing the present acryl resin, and the mixture is further added, if desired, with the abovementioned solvent and/or surfactant and mixed well in a conventional mixing device as roll mill, ball mill, sand grind mill, planetary mixer, high speed disper and the like, to obtain a pigment dispersion paste.

he paste is then added with the present acryl resin or other resinous materials and/or solvent, surfactant and the like to obtain an acryl enamel paint.

Thus obtained clear and enamel paints containing the present acryl resin are characterized by being answered to the requirements of lower viscosity and higher non-volatile content, and when coated, resulting the coating with excellent weathering resistance, chemical resistance, solvent resistance, and mechanical strength which are the characteristic features of an acrylic resin.

Since the present branched type acryl resin per se is of lower viscosity, it is very advantageous in the preparation of pigment dispersion paste for increasing the dispersion speed and lowering the viscosity of the resulted paste.

However, surface properties of paint pigments are varied and therefore, in certain circumstances, dispersion performance is not always of satisfaction even with the present branched type acrylic resin.

Starting from the recognition that surface properties of pigments, may be classified in either concepts of acid or base, the inventors have now found that by the acidic and/or basic modification of the present branched type acryl resin depending on the surface properties of the pigment to be used, far improved pigment dispersion paste can be obtained in respect of dispersion speed, dispersion viscosity, yield value, storage stability, color mixing stability, nonvolatile content, application characteristic, color tone, gloss, shrpness and the like.

Thus, in the second aspect of the invention, is provided a branched type acryl resin for pigment dispersion use composed of the resin of the formula:

(wherein R is aliphatic, alicyclic, aromatic or heterocyclic hydrocarbon residue of n valency; X is acryl prepolymer chain, and n is a real number of 2 to 6) on which an alectron accepting group and/or electron donating group is carried.

(1) The present electron accepting group bearing branched type acryl resin may be prepared by reacting active hydrogen bearing branched type acryl resin with acid anhydride and/or sultone compound, and (2) electron donating group bearing branched type acryl resin may be prepared by the method (a) wherein a carboxyl bearing acryl prepolymer is first prepared by using, as a part of monomer components, a polymerizable basic compound and the desired branched type acryl resin is then prepared by using the said base bearing prepolymer, or the method (b) wherein the active hydrogen contained in the branched acryl resin or active alkoxy intensionally introduced therein is reacted with a basic low molecular compound and/or basic resin having active alkoxy group and/or active hydrogen.

(3) The amphoteric branched type acrylic resin having both electron donating group and electron accepting group may be easily prepared by the combination of the abovesaid Method 1 and the Method 2 (a) or 2 (b).

The term "active hydrogen" as used herein denotes a reactive hydrogen atom attached to oxygen, sulfur, nitrogen atom or the like, as included in primary, secondary and tertiary hydroxyl groups, amide bonding, urethane bonding, carboxyl group or the like.

The term "active alkoxy group" shall mean a reactive alkoxy group like the group obtained by the substitution of hydrogen atom of active methylol with an alkyl group.

The term "functional group reactive with active hydrogen" shall mean the group capable of reacting easily with an active hydrogen, as primary, secondary and tertiary hydroxyl groups, isocyanate group, glycidyl group and the like.

The term "functional group reactive with active alkoxy" shall mean the group capable of reacting easily with an active alkoxy group, as primary, secondary and tertiary hydroxyl groups.

The term "electron accepting group" shall mean the group which shows a tendency to draw an electron from others judging on the basis of hydrogen within the molecule, as, for example, carboxyl, sulfon, nitro and the like.

The term "electron donating group" shall mean the group which shows a tendency to give an electron to others judging on the basis of hydrogen within the molecule, because of having -Nwith non-shared electron pair.

The term "basic resin" shall mean the resin with basic group as urea resin, melamine resin, polyamide resin, polyurethane resin and the like customary used in paint area.

The term "basic low molecular compound" shall mean such compounds as prepolymers of basic resins, hydroxyl amine compounds (e.g. monoethanolamine, diethanol amine, aminopentanol, amino benzyl alcohol, 2-dimethyl amino ethanol and the like), and amino acids (e.g. 3dimethyl amins benzoic acid, 2-amino-isobutyric acid, 4-amino-n-butyric acid) and the like.

Preparations of these branched type acryl resins bearing electron donating groups and/or electron accepting groups shall be now explained below.

(A) Branched type acryl resin bearing electron accepting group: The starting acryl prepolymer having carboxyl group may be prepared by using, as a component of monomers, an active hydrogen containing monomer to give an active hydrogen bearing prepolymer, or it may be prepared without using such monomer. This is because the branched acryl resin obtained by the reaction carboxyl bearing acryl prepolymer and poly functional epoxy compound and having the formula:

do possess secondary hydroxyl groups in the molecule, which can be utilized as active hydrogen bearing groups.

In order to make the branched type acryl resin with active hydrogens carry with electron accepting groups, any of the compounds being reactive with such active hydrogens and capable of resulting free acidic groups may be advantageously used.

Typical examples are the compounds which are reactive with active hydrogen to give carboxyl group, like acid anhydrides (e.g. acetic anhydrie, succinic anhydride, phthalic anhydride, maleic anhydride, tetra hydrophthalic anhydride, hexahydro phthalic anhydride, trimellitic anhydride, and the like), the compounds which are reactive with active hydrogen to give sulfonic acid group like aliphatic acid sultone (e.g. 1,3-propane sultone, 1 ,3-butane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-octane sultone, 2,3-decane sultone and the like), and inorganic acid an hydroxide (e.g. metaphoshoric acid).

In the addition reaction with such sultone compound, a solution of branched type acryl resin and aliphatic acid sultone is reacted at 60"C to 1 50 C for 2 to 10 hours to give a sultone modified, branched type acryl resin.

The amount of sultone is usually selected in a range of 0.01 to 6% by weight, preferably 0.02 to 4% by weight, of the branched acryl resin (solid weight).

If the charging amount exceeds over the upper limit of 6% by weight, there is a tendency that polymer melt viscosity will get higher, thereby causing difficulty in the preparation of the intended polymer.

(B) Branched type acryl resin bearing electron donating group: This type of resin may be prepared by the combination of steps of (1) preparing carboxyl bearing acryl prepolymer by using, as a component of monomers, a polymerizable basic compound, as, for example, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, butylaminoethyl methacrylate, butylaminoethyl acrylate, 2-vinyl pyridine, 4-vinyl pyridine, 2-methyl-5-vinyl pyridine, 2-ethyl-5-vinyl pyridine, dimethyl allylamine, diallylamine, vinyl pyroline, vinyl isoquinoline, N,N-dimethylaminoethyl vinyl ether, 2-(N,Ndimethylamino)-4-vinyl pyrimidine, trans-1,2-dipyridyl ethylene, 3-cinnamoyl pyridine, 2-methyl5-cinnamoyl pyridine, 4,6-diamino-2-vinyl-5-triazine and the like, and then (2) synthesizing the desired branched type acryl resin therefrom.

Alternatively, such resin may be prepared by the combination of steps of preparing carboxyl bearing acryl prepolymer by using, as a component of monomers, an active alkoxy containing monomer and/or active hydrogen containing monomer, preparing branched type acryl polymer carried with active hydrogen and/or active alkoxy group therefrom, and then reacting the said branched type acryl resin with a low molecular weight basic compound and/or basic resin.

As an alternative, such resin may be prepared by reacting the branched acryl resin having active hydrogens with polyisocyanate compound or glycidyl compound so as to remain an amount of said isocyanate or glycidyl groups, and then reacting the same with active hydrogens in the basic resin and/or basic, low molecular weight compound.

As the basic resin, any conventional resins customarily used in paint area including urea resin, melamine resin, polyamide resin and polyurethane resin, may be satisfactorily used.

Urea resin or melamine resin is prepared by condensing urea or melamine with formaldehyde.

If desired, an alcohol (e.g. methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol and the like) may be used as a part of raw materials, thereby forming an alkylated methylol urea resin or alkylated methylol melamine resin.

Polyamide resin is usually obtained by the condensation reaction of aliphatic diamine and dibasic acid or condensation of urea and cyclic lactam.

Examples of such aliphatic diamines are 1,2-ethane diamine, N,N'-dimethyl-1,2-ethane diamine, 1.6-hexane diamine and the like, and examples of dibasic acids are succinic acid, adipic acid, sebacic acid and the like.

Examples of cyclic lactams are a-pyrolidone, Bcaprolactam, a-capril lactam and the like.

Since the basic resin may carry with active hydrogen or active alkoxy group besides the electron donating group, it is possible to make react (addition or condensation) with the functional group of acidic resin (A).

Polyurethane resin may be obtained by the addition reaction of poly hydroxy compound as, for example, hydroxyl bearing oil-free polyester resin, long-oil or short-oil alkyd resin, acryl resin and polyether resin, with isocyanate compound. The abovesaid polyethers are the resins obtained by the polymerization of propylene oxide, ethylene oxide or the like with the help of initiator as sorbitol, pentaerythritol, sucrose, starch and the like. Examples of said isocyanate compounds are diisocyanates as hexamethylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate and the like, and polyisocyanates as Desmodule N, Desmodule L and the like.

The branched acryl resin having both electron accepting group and electron donating group (C) may be prepared by the combination of the methods already stated in connection with the resins (A) and (B).

Thus obtained branched type acryl resins (A), (B) and (C) each has, as compared with the conventional acryl resins carried with electron accepting and/or donating groups, the common characteristic feature that resinous viscosity is quite low at the same molecular weight level.

Also, by selecting appropriate (A), (B) or (C) resin according to the surface properties of pigment to be used, it is able to get more advantageous effects on pigment dispersion, application characteristics, film performance or the like.

However, in a paint industry, a huge number of inorganic and organic pigments are used, whose surface properties vary considerably with species.

Viewing from the conception of acid or base, the acidity or basicity of such pigments may likewise vary with species. Therefore, the optimum acidity or basicity of the dispersing resin may, as a matter of course, vary with the pigment to be selected.

Under the circumstancies, the inventors, conceiving an idea that there will probably be certain optimum ranges, from the greatest common divisory sense of view, in the acidity and basicity of the dispersing resins to be used in combination with these pigments, have actually made various pigment dispersions with said dispersing resins and studied on the corselation between the acidity and basicity of the respective resin and effect on dispersibility of the selected pigment.

Since there are no known simple methods for the determination of acidity and basicity of the dispersing resins in non-aqueous system, the inventors have developed own methods, by which the actual acidities and basicities of various dispersing resins are determined and evaluated.

These methods are as follows.

That is, the test resin is dissolved in aniline and subjected to a quantitative determination by means of non-aqueous potentiometry with a titrant of n-tetrabutylammonium hydroxide, and the acidity of said resin is determined from the molar quantity of said reagent required for the neutralization of the resinous solution.

As the method for the determination of basicity, the test resin is dissolved in acetic acid and subjected to a quantitative determination by means of non-aqueous potentiometry with a titrant of perchloric acid, and the basicity of said resin is determined from the molar quantity of said reagent required for the neutralization.

From the test results obtained, the inventors have come to the conclusion that excellent dispersions are obtained, irrespect of the kind of inorganic and organic pigments, with the amphoteric type resin whose acidity is 1.0 to 1.0 X 10-2 m mol/g solid, and especially 0.8 to 2.0 x 10-2 m mol/g solid, and basicity is 1.0 to 5 X 10-3 m mol/g solid and especially 1.0 to 1 x 10-2 m mol/g solid. Therefore, in a particurally preferable embodiment of the invention, such amphoteric type resins as fulfilling the said requirements are used.

As the results of our extensive studies, the inventors have found that particularly good results are obtained with the electron accepting group bearing branched type arcyl resin prepared by using 99.9 to 50% by weight (on solid basis, herein after the same) of active hydrogen containing branched type acryl resin and 0.1 to 50% by weight of acid anhydride and/or sultone compound, and more preferably 99.9 to 70% by weight of the former and 0.1 to 30% by weight of the latter; with the electron donating group bearing branched type acryl resin prepared by using 99.9 to 50% by weight of active hydrogen and/or active alkoxy bearing branched type acryl resin and 0.1 to 50% by weight of active alkoxy and/or active hydrogen bearing low molecular weight basic compound and/or basic resin, and more preferable 99.9 to 70% by weight of the former and 0.1 to 30% by weight of the latter; and with the branched type resin having both electron accepting group and electron donating group prepared by using 99.5 to 40% by weight of the electron accepting group and functional group bearing branched type acryl resin and 0.5 to 60% by weight of functional group bearing basic resin, and most preferable 99.5 to 60% by weight of the former and 0.5 to 60% by weight of the latter.

These resins should preferably have a weight average molecular weight (Gel permeation chromato-graphy, polystyrene conversion) of 2,000 to 200,000 preferably 4,000 to 100,000 and a glass transition point of - 20"C to 100"C, and preferably - 1 0 to 80"C. Therefore, in the most preferable embodiment of this invention, such resins as fulfilling the above said, all requirements are used for the dispersion purpose of pigments.

The present dispersion base composition can be obtained by using the present resins defined in the specification and dispersing various pigments therein.

As the pigments, any of the inorganic and organic natures customarily used in paint compositions may be satisfactorily used. Examples of inorganic pigments are carbon black, zinc white, titanium dioxide, antimony white, iron black, rouge, red lead, cadmium yellow, zinc sulfide, lithopone, barium sulfate, lead sulfate, barium carbonate, white lead, alumina white and the like, and examples of organic pigments are of azo, polycondensation azo, metal complex azo, benzimidazolone, phthalocyanine (blue-green), thioindigo, anthraquinone, flavanthrone, indanthrene, anthrapyridine, pyranthrone, isoindolinone, perylene, perynone and quinacridone series. The compounding ration of said resin and pigment is not critical in this invention and may be selected in any desired range.However, from the economical and dispersion efficiency points of view, it is generally determined in the range of 10 to 90% by weight of resin (solid) to 90 to 10% by weight of pigment, preferably 30 to 70% by weight of resin (solid) to 70 to 30% by weight of pigment.

In formulating the present dispersion base composition, the abovesaid electron accepting and/or donating group bearing dispersion resin is optionally mixed with at least one other resin selected from the group consisting of acryl resin outside the invention, alkyd resin, polyester resin, polyether resin, cellulose nitrate, urethane resin, vinyl acetate resin, polyvinylalcohol resin, vinyl chloride resin, phenol resin, melamine resin, guanamine resin, urea resin, epoxy resin and the like, to which is added at least one pigment and optional solvent customarily used in a paint area as, for example, hydrocarbons (e.g. toluene, xylene, Solvesso 100, Solvesso 150), ester solvents (e.g. ethyl acetate, butyl acetate), ketone solvents (e.g.MEK, MIBK), and thus obtained mixture is milled well in a common grinding equipment like roll mill, ball mill, sand grind mill, planetary mixer and high speed disper.

The present dispersion base composition shows excellent pigment dispersibility, storage stability and compatibility with other resin, and hence is quite useful for the preparation of coating composition.

The invention shall be now more fully explained in the following examples. Unless otherwise being state, all parts and percentage are by weight.

Synthetic Example 1 Preparation of acryl prepolymer Into a reaction vessel fitted with dropping funnel, condenser, nitrogen inlet, thermometer and stirrer, were placed 224 parts of xylene and heated to 130"C. A mixture of 45 parts of 2hydroxyethyl methacrylate, 336 parts of methyl methacrylate, 60 parts of n-butyl acrylate, 1 27 parts of styrene, 26 parts of thioglycolic acid and 5.4 parts of azobisiobutyronitrile was placed in a dropping funnel and the mixture was dropped into the reactor at a constant speed at 130"C in a nitrogen atmosphere. After completion of the said addition, the content was maintained at 130"C for 30 minutes.Next, a solution of 0.56 part of azobisisobutyronitrile in 1 76 parts of xylene was placed in a dropping funnel and dropped into the reactor at a constant sped over 30 minutes. After completion of the said addition, the content was maintained at 130"C for 1 hour to complete the polymerization. After cooling, the conatent was removed to obtain a colorless, clear acryl prepolymer A, whose characteristics were shown in Table 1.

Synthetic Examples 2 to 4 Using the same procedures as stated in Synthetic Example 1 but following the prescriptions shown in Table 1, acryl prepolymers B,C and D were prepared, respectively. The characteristics of these prepolymers are shown in Table 1.

Table 1

Synth. Example 1 2 3 4 varnish name A B C D xylene 224 747 262 285 2-hydroxyethyl methacrylate 45 45 45 45 methyl methacrylate 336 336 336 336 n-butyl acrylate 60 60 60 60 styrene monomer 127 127 127 127 thioglycolic acid 26 14 6.5 3.6 azobisisobutyro nitrile 5.4 2.6 2.7 2.9 azobisisobutyro nitirile 0.56 0.35 0.30 0.33 xylene 176 129 123 132 non-volatile content % 60.3 34.7 62.2 60.7 viscosity cps 1770 - 13620 acid value mg KOH/ag solid 20.8 15.5 6.4 4.1 number average molecular weight 2700 3100 6800 7800 Mn weight average molecular weight 5900 6800 15900 21500 Mw OH value mg KOH/g solid 34 34 34 34 Tg C 76 76 76 76 Synthetic Example 5 Preparation of branched type acryl resin In a reactor fitted with condenser, nitrogen inlet, thermo meter and stirrer, were placed 451 parts of acryl prepolymer A obtained in Synthetic Example 1, 28 parts of Denacol EX 411 (diglycerol polyglycidyl ether, manufactured by Nagase Kasei Kogyo), 21 parts of xylene and 0.72 part of Farmin DMC (manufactured by Kaoh Sekken K.K.) and the content was heated to 140 C. The mixture was maintained at 140 C for 10 hours to complete the addition reaction and thus obtain a branched type acryl resin E. The characteristics are shown in Table 2.

Synthetic Examples 6 to 10 Using the same procedures as stated in Synthetic Example 5 but following the prescriptions shown in Table 2, branched type acryl resins E to J were prepared. The characteristics of these resins are shown in Table 2.

Synthetic Examples 11 to 1 3 (Comparative resins) Using the similar procedures as stated in Synthetic Example 5 but following the prescriptions shown in Table 3, a set of Comparative resins K to M were prepared. The characteristics of these resins are shown in Table 3.

Table 2

Synth. Example 5 6 7 8 9 10 varnish name E F G H I J acryl prepolymer A 451 436 463 acryl prepolymer B 460 acryl prepolymer C 475 acryl prepolymer D 450 diglicidyl ether * 1 37 trimethylol propane polyglycidyl ether 20 * 2 pentaerythritol tetra glycidylether 28 23 9 5 * 3 xylene 21 17 15 26 16 9 Farmin DMC 0.72 0.46 0.72 0.72 0.72 0.67 non-volatile content % 54.4 69.7 54.2 56.7 62.5 52.1 viscosity cps 525 55700 3773 402 2883 acid value mg KOH/g solid 0.5 1.0 0.5 2.2 1.2 0.3 number average molecular weight 4600 6200 10800 3800 4600 10700 Mn weight average molecular weight 11500 16400 33300 7600 10600 46800 Mw OH value mg KOH/g solid 122 99 101 78 90 114 Tg C 76 76 76 76 76 76 * 1 Sumi Epoxy ELG-300 ( canufact. by Sumitomo Chem. Co.) *2 Denacor EX-321 (manufact. by Nagase Kasei K.K.) *3 Denacor EX-411 (manufact. by Nagase Kasei K.K.) Table 3

Synth. Example 11 12 13 varnish name , K L xylene 168 168 -- 168 2-hydroxyethyl methacrylate 45 45 45 methyl methacrylate 194 194 194 n-butyl acrylate 39 39 39 styrene monomer 57 57 57 butyl acetate 67 67 67 lauryl mercaptane 5.0 2.3 1.6 butyl acetate 101 101 101 azobisisobutyro nitirile 3.8 3.8 3.8 non-volatile content % | 50.3 51.0 50.0 viscosity cps * 770 1780 2900 acid value tug KOH/ag solid ' 6.9 7.1 | 7.8 number average molecular weight 7500 11000 13500 Mn * * weight average 30500 molecular weight 18200 30500 35800 Mw ** OH value mg KOH/g solid 58 58 58 Tg C 68.4 68.4 68.4 * Tokyo Keiki E type viscometer ** Gel permeation chromatography, polystyrene conversion Example 1 Each of the acryl prepolymers A to C obtained in Synthetic Examples 1 to 3, branched type acryl resins E to J obtained in Synthetic Examples 5 to 10, and Comparative resins K and M obtained in Synthetic Examples 11 and 13, was diluted with solvent (xylene/butyl acetate = 1 /1) to obtain a varnish having a solid content of 50%, respectively. By using Corn plate type viscometer, varnish viscosity was measured. Thus determined viscosities of the resinous varnishes are shown in Table 4.

Table 4

acryl prepolymer branched acryl resin Synth. Example 1 2 3 4 5 6 7 varnish name A B C D E F G Mw 5900 6800 15900 11500 16400 33300 viscosity 169 300 544 209 451 1441 branched acryl resin Compara. resin Synth. Example 8 9 10 11 13 varnish name H I J K M Mw 7600 10600 46800 18200 35800 viscosity cp 115 186 2035 765 2900 From these results, it may be said that at the same level of weight average molecular weight, the present branched type acryl resin shows a lower viscosity as compared with others.

Example 2 Using branched type acryl resin G obtained in Synthetic Example 7 and comparative resin M obtained in Synthetic Ex. 13 (each having approximately same weight average molecular weight), pigment dispersions were prepared, according to the prescriptions Table 5 and using paint shaker (Red Devil Co.), so as to give 20 mirror gloss (Murakami gloss meter GM-26D) of more than 40.

Table 5

Dispersion paste N O Titanium oxie R-820 # 62 62 Compara. resin M 18 branched type acryl resin G 17 xylene 8 8 butyl acetate 12 12 manufactured by Ishihara Sangyo K.K.

Viscosity of the respective dispersion paste was measured by using corn plate type viscometer (E type viscometer, Tokyo Keiki K.K.), and the results were shown in Table 6.

Table 6

Dispersion paste viscosity- I viscosity- II viscosity I/ 20 dispersing (cp) # 1 (cp) # 2 viscosity II Mirror time (min.) glass N 127 122 1.0 46 230 O 82 84 1.0 42 170 #1) viscosity at the rate of shear of 76.8 sec-1) #2) viscosity at the rate of shear of 384.0 sec-1 rrom these datas, it might be clear that dispersion paste viscosity be lowered about 35% by the use of the present branched type acryl resin.

Example 3 According to the prescriptions shown in Table 7 and using ether branched type acryl resin G or Comparative resin M, carbon black (MA-100, manufactured by Mitsubishi Carbon K.K.) was dispersed as in Example 2, to obtain dispersion pastes diepersion being carried out up to 80 and more of 60 mirror gloss). Their viscosities are shown in Table 8.

From this table, it is clear that by the use of the present branched type acryl resin, there is a marked viscosity down to about 1 fifth of that of conventional resin and the dispersion paste shows Newtonian flow.

Table 7 Prescription of dispersion paste

Dispersion paste P carbon black NA100"( 16 16 comparative resin M 59 branched type acryl resin G 54 xylene 7 32 butyl acetate 20 o Table 8

ispersion paste viscosity-I viscosity-II viscosityI/ 60 dispersing (cp) (1) (cp) (2) viscosityII mirror time (min.) gloss P 1738 1128 1.5 83 820 0 300 282 1.1 91 110 (1) viscosity at the rate of shear of 19.2 sec-t (2) viscosity at the rate of shear of 38.4 sec-1 Example 4 According to the prescriptions shown in Table 9 wherein the Comparative resin K, branched type acryl resin F and acryl prepoiymer C each having the almost same order of weight average molecular weight were used, and following the procedures given in Example 2, Mapico yellow LLXLO dispersion pastes were prepared (dispersion being carried out up to 50 and more of 60 mirror gloss).

Their viscosities are shown in Table 10.

From these results, it is clear that the dispersion paste with the present branched type acryl resin shows a lower viscosity as compared with those of other dispersion pastes, i.e. about 60% reduction from the viscosity of the dispersion paste with comparative resin and about 80% reduction from the viscosity of the dispersion paste with the acryl prepolymer.

Table 9 Prescription of dispersion paste

dispersion paste R S T Mapico yellow LLXLO # 51 51 51 Compara. resin K 47 branched type acryl resin F 34 acryl prepolymer C 38 xylene 2 15 11 X aanufactured by Titan Kogyo K.K.

Table 10

Dispersion viscosity-I viscosity-II viscosityI/ 60 dispersing paste (cp) #1 (cp) #2 viscosityII mirror time (min.) gloss R 3990 4170 1.0 53 120 S 1540 1590 1.0 89 180 T 9220 - - 75 120 #1 viscosity at the rate of shear of 19.2 sec-1 #2 viscosity at the rate of shear of 38.4 sec-1 Synthetic Example 14 Preparation of acryl polymer Into a reaction vessel fitted with dropping funnel, condenser, nitrogen inlet, thermometer and stirrer, were placed 33 parts of xylene and heated to 1 30 C.

A mixture of 45 parts of 2-hydroxy ethyl methacrylate, 336 parts of methyl methacrylate, 60 parts of n-butyl acrylate, 127 parts of styrene, 6.5 thioglycolic acid and 2.7 parts of azobisisobutyronitrile was placed in a dropping funnel and the mixture was dropped into the reactor at a constant speed at 130 C for 30 minutes.

Next, a solution of 0.3 part of azobis isobutyronitrile in 123 parts of xylene was placed in a dropping funnel and dropped into the reactor at a constant speed over 30 minutes. After completion of said addition, the content was maintained at 1 30 C for 1 hour to complete the polymerization. After cooling, the content was removed to obtain a colorless, clear acryl prepolymer I, whose characteristics were shown in Table 11.

Synthetic Example 1 5 Preparation of branched type acryl resin Into a reactor fitted with condenser, nitrogen inlet, thermometer, and stirrer, was placed a solution consisting of 747 parts of acryl prepolymer I obtained in Synthetic Example 14, 14 parts of Denacol EX-411 (manufactured by Nagase Kasei Kogyo K.K.) and the 1.19 parts of Farmin DMC (manufactured by Kaoh Sekken K.K.), and the solution was heated to 1 30 C.

Thereafter, the same temperature was maintained for 7 hours to complete the addition reaction and their mixture was added with 119 parts of xylene and 119 parts of butyl acetate and then allowed to cool to obtain a branched type acryl resin II. The characteristics of this resin are shown in Table 12.

Synthetic Example 1 6 Preparation of acid-added, branched type acryl resin Into a reactor fitted with condenser, nitrogen inlet, thermometer and stirrer, was placed a solution consisting of 865 parts of branched type acryl resin II obtained in Synthetic Example 15 and 7.2 parts of succinic anhydride, and the solution was heated to 130"C. Thereafter, the solution was maintained at 130"C for 1 hour to complete the addition reaction, and added with 0.1 part of xylene and 0.1 part of butyl acetate to obtain an acid-added, branched type acrylic resin III. The characteristics of this resin are shown in Table 1 3.

Synthetic Example 1 7 Preparation of acid-added, branched type acryl resin Using the same procedures as stated in Synthetic Example 1 6 but following the prescription given in Table 13, phthalic anhydride-added, branched type acryl resin was prepared. At this time, DBTO (manufactured by Wako Junyaku Kagaku Kogyo K.K.) and phthalic anhydride were çharged in at the same time. The characteristics of thus obtained resin IV are shown in Table 13.

Synthetic Example 1 8 Preparation of acid-added, branched type acryl resin Into a reactor fitted with condenser, nitrogen inlet, thermometer and stirrer. was placed a solution consisting of 865 parts of branched type acryl resin II obtained in Synthetic Example 15, 1.3 parts of propanesultone (manufac. by Daisel Co.), 0.1 part of xylene and 0.1 part of butyl acetate and heated to 105"C. Thereafter, the solution was maintained at 1054C for 5 hours to complete the addition reaction and obtain acid-added, branched type acryl resin V. The characteristics of the resin are shown in Table 1 3.

Synthetic Example 1 9 Using the same procedures as stated in Synthetic Example 1 4 but following the prescription given in Table 14, comparative resin VI was prepared. The characteristics of this resin are shown in Table 14.

Synthetic Example 20 Preparation of base-added, branched type acryl resin Into a reactor fitted with dropping funnel, condenser, nitrogen inlet, thermometer and stirrer, were placed 33 parts of xylene and 1 56 parts of butyl acetate and the mixture was heated to 130"C. Separately, 45 parts of 2-hydroxyethyl methacrylate, 336 parts of methyl methacrylate, 60 parts of n-butyl acrylate, 127 parts of styrene, 11.5 parts of N,N-dimethyl aminoethyl methacrylate, 6.5 parts of thioglycolic acid and 2.7 parts of azobisisobutyronitrile were placed in the dropping funnel and the content of said dropping funnel was dropped in the reactor at a constant speed, at 130"C in 3 hours under nitrogen stream. Then, the mixture was maintained at 1 30"C for 30 minutes.Next, a solution of 0.3 part of azobisisobutyronitrile and 1 23 parts of xylene was placed in the dropping funnel and the solution was dropped into the reactor over 30 minutes at a constant speed. After completion of said addition, the thus obtained mixture was maintained at 130"C for 1 hour, added with 1 7 parts of Denacor EX-411 (manufactured by Nagase Kasei Kogyo K.K.) and 1.44 parts of Farmin DMC, maintained at 130"C for 7 hours to complete the addition reaction, added with 144 parts of xylene and 1 44 parts of butyl acetate and allowed to cool to obtain base-added, branched type acryl resin VII. The characteristics of this resin are shown in Table 1 7.

Synthetic Example 21 Preparation of base-added, branched type acryl resin Into a reactor fitted with condenser, nitrogen inlet, thermometer and stirrer, was placed a solution consisting of 192 parts of branched type acryl resin 11, 4 parts of U-20 SE 60 (manufactured by Mitsui Toatsu K.K.), 2 parts of xylene and 2 parts of butyl acetate and reacted at 110"C until the viscosity was exceeded over Y measured by bubble viscometer.

The characteristics of thus obtained base-added, branched type acryl resin VIII are shown in Table 18.

Synthetic Example 22 Preparation of amphoteric, branched type acryl resin Into a reactor fitted with condenser, nitrogen inlet, thermometer and stirrer, was added a solution consisting of 665 parts of base-added, branched type acryl resin VII obtained in Synthetic Example 20, 9.1 parts of phthalic anhydride and 0.44 part of DBTO (manufactured by Wako Junyaku Kogyo K. K.) and heated to 130"C. The mixture was then maintained at 130"C for 1 hour to complete the addition reaction, and added with 105 parts of xylene and 105 parts of butyl acetate.

The characteristics of thus obtained amphoteric, branched type acryl resin IX are shown in Table 20.

Example 5 Using the comparative resin VI and the acid-added branched type acryl resin III, obtained in Synthetic Example 16, each having the similar weight average molecular weight and following the prescriptions as given in Tables 1 5 and 16, pigment dispersions were prepared by means of paint shaker (Red Davil Co.) and mirror gloss of the respective dispersion was measured by Murakami Gloss meter Type GM-26D. Their viscosities were also determined by Corn plate type viscometer (manufactured by Tokyo Keiki K.K., E type viscometer).

The results are shown in Tables 1 5 and 1 6.

It was observed that by the use of acid-added branched type acryl resin, viscosity of the dispersion paste could be lowered to the level of 40 to 50% of that of the comparative paste, in both carbon black and phthalocyanine pigment cases.

In Tables 1 5 and 16, there are also shown the test results of storage stability of the respective dispersion pastes. It might be clear that the successive viscosity of the dispersion paste is also at 50 to 70% lower level than that of the comparative paste.

Example 6 Using the same procedures as given in Example 5 and following the prescriptions shown in Table 16, dispersion pastes were prepared with phthalic anhydride-added branched type acryl resin IV and with the comparative resin VI. Mirror gloss and viscosity of the respective paste and test results on storage stability are shown in Tables 15 and 16.

From these test results, it would be clear that by the use of the present phthalic acid-added, branched type acryl resin, in both carbon black and phthalocyanin cases, viscosity of dispersion paste be almost 60% lower and successive viscosity of dispersion paste be 20 to 70% lower than those of the comparative paste with resin VI.

Example 7 Using the same procedures as stated in Example 5 and following the prescriptions given in Table 16, dispersion pastes were prepared with sultone-added, branched type acryl resin V and with the comparative resin VI. Dispersion test results are shown in Tables 15 and 16. From these test results, it would be clear that by the use of the present sultone-added, branched type acryl resin, paste viscosity be 40 to 60% lower than those of the comparative paste with the resin VI, in both carbon black and phthalocyanin cases.

Example 8 Using the same procedures as stated in Example 5 and following the prescriptions shown in Table 19, dispersion pastes were prepared with the base-added, branched type acryl resin VII obtained in Synthetic Example 20. Dispersion test results are shown in Table 1 9. From athe test results of Table 1 9 and the results of Table 1 5 concerning the comparative resin VI, it would be clear that by the use of base-added branched atype acryl resin, paste viscosity be almost 70% lower and successive viscosity be almost 70% lower than athose of the comparative paste in carbon black case.

Example 9 Using the same procedures as stated in Example 5 and following the prescription given in Table 9 dispersion paste was prepared with the base-added, branched type acryl resin VIII. The test results for this paste were shown in Table 1 9. From the comparison of the test results of Table 1 9 and of Table 5, it would be clear that by the use of the base-added, branched type acryl resin, paste viscosity be almost 70% lower and successive viscosity be almost 60% lower than the corresponding values of the dispersion paste with the comparative resin VI.

Example 10 Using the same procedures as stated in Example 5 and following the prescription shown in Table 21, dispersion pastes were prepared with the amphoteric branched type acryl resin TX.

From the comparison of the test results of Table 21 and of Table 15, it would be clear that by the use of the present amphoteric, branched type acryl resin IX, paste viscosities be almost 60% lower than those of the comparative paste in both carbon black and phthalocyanin cases and that the successive viscosities are also about 60% lower than those of the comparative paste with the resin VI.

Table 11

Synthetic Example 14 Name of varnish I xylene 33 butyl acetate 156 2-hydroxyethyl methacrylate 4% methyl methacrylate 336 n-butyl acrylate 60 styrene 127 thioglycolic acid 6.5 azobisisobutyronitrile 2.7 azobisisobutyronitrile 0.30 xylene 123 non - volatile content % 67 acid value mg KOH/g solid 6.7 number average molecular weigth Mn # 8200 weight average molecular weigth Mw # 16900 OH value mg KOH/g solid 34 Tg C 76 * gel permeation chromatography, polystyrene conversion Table 12

Synthetic Example 15 Name of varnish II acryl prepolymer I 747 Denacor EX-411(3) 14 Farmin DMC 1.19 xylene 119 butyl acetate 119 non - volatile content % 50 viscosity cps (E type viscometer) # 2130 acid value mg KOH/g solid 0.4 number average molecular weight Mn # # 7870 weight average molecular weight Mw # # 23890 OH value mg KOH/g solid 40 Tg C 76 * manufactured by Tokyo Keiki K.K.

* * gel permeation chronatography, polystyrene conversion Table 13

Synth. Example 16 17 18 varnish name III IV V branched type acryl resin II 865 865 865 succinic anhydride 7.2 phthalic anhydride 9.1 propane sultone 1.3 xylene 0.1 4.7 0.1 butyl acetate 0.1 4.7 .1 DBTO 0.44 non - volatile % 54 50 50 viscosity cps # 1 6000 1700 1400 acid value mg KOH/g solid 3.7 8.5 0.4 number average molecular weight Mn # 2 9210 12920 8000 weigth average molecular weigth Mw # 2 31000 32900 24000 OH value mg KOH/ g solid 31 32 39 Tg C 76 76 76 # 1 e type viscoleter, ianufactured by Tokyo Keiki K.K.

# 2 gel permeation chromatography, polystyrene conversion Table 14

Synthetic Example 19 Name of varnish VI xylene 168 2-hydroxyethyl methacrylate 45 methyl methacrylate 194 n - butyl acrylate 39 styrene 57 butyl acetate 67 lauryl mercaptane 1.6 butyl acetate 101 azobisisobutyronitrile 3.8 non - volatile content % 50 viscosity cps 2900 acid value mg KOH/g solid 7.8 number average molecular weight Mn # 13500 weight average molecular weigth Mw # 35800 OH value mg KOH/g solid 58 Tg C 68 * get permeation chrosatography, polystyrene conversion Table 15

dispersion paste 1 2 3 titanium oxide CR - 95 (1) 62 carbon MA100 (2) 16 Fastgen blue-NK (3) 22 comparative resin VI 20 57 55 xylene 9 14 12 butyl acetate 9 13 11 20 mirror gloss 41 60 mirror gloss 83 79 viscosity - I (cps) 192 1740 1640 STORAGE STABILITY 20 mirror gloss 40 60 mirror gloss 65 81 viscosity-II (cps) 206 6740 2170 viscosity-II/ viscosity-I 1.1 3.9 1.3 (1) manufactured by Ishihara Santyo K.K.

(2) manufactured by Mitsubishi Kasei Kogyo K.K.

(3) manufactured by DainichiSeika Kogyo K.K. Table 16

dispersion paste 4 5 6 7 8 9 10 11 12 titanium oxide 62 62 62 carbon MA 100 16 16 16 Fastgel blue NK 22 22 22 acid - added branched type acryl resin III 20 57 5 ibid IV 20 57 55 ibid V 20 57 55 xylene 9 14 12 9 14 12 9 14 12 butyl acetate 9 13 11 9 13 11 9 13 11 20 mirror gloss 57 49 50 60 mirror gloss 90 76 90 87 80 80 viscosity - I (cps) 150 680 5160 130 720 680 180 750 60 STORAGE STABILITY 20 mirror gloss 50 56 47 60 mirror gloss 75 78 75 88 75 75 viscosity - II (cps) 170 3230 670 100 2360 1100 200 3300 700 viscosity II / I 1.1 4.7 1.2 0.8 3.3 1.6 1.1 4.4 1.2 Table 17

Synthetic Example 20 Name of varnish VII xylene 33 butyl acetate 2-hydroxyethyl methacrylate methyl methacrylate n - butyl acrylate 60 styrene 127 thioglycolic acid 6.5 azobisisobutyronitrile 2.7 N,N - dimethylaminoethyl methacrylate 11.5 azobisisobutyronitrile 0.30 xylene 123 Denacor EX - 411 17 Farmin DMC 1.44 xylene 144 butyl 1 acetate 144 non-volatile content % 50 acid value mg KOH/g solid 6.5 number average nolecular weight Mn * 8300 weight average molecular weight Mw * 17000 OH value g KOH/g solid 34 Tg C 76 $ gel permeation chromatography, polystyrene conversion Table 18

Synthetic Example 21 varnish name VIII branched type acryl resin II 192 U - OSE - 60 4 xylene 2 butyl acetate 2 non - volatile % 50 acid value mg KOH/g solid 0.4 number average molecular weight Mn 9000 weight average molecular weight Mw 62000 Tg C 76 Table 19

dispersion paste 13 14 15 16 17 18 titanium oxide CR - 95 62 62 carbon MA 100 16 16 Fastgel blue NK 22 22 base-added branched type acryl resin VII 20 57 55 ibid VIII 20 57 55 xylene 9 14 12 9 14 12 butyl acetate 9 13 11 9 13 11 20 mirror gloss 40 40 60 mirror gloss 80 80 80 80 viscosity - I (cps) 210 550 2000 220 550 2100 STORAGE STABILITY 20 mirror gloss 37 37 60 mirror gloss 73 74 75 75 viscosoty - II (cps) 230 2000 2500 240 230 2500 viscosity II / I 1.1 3.6 1.3 1.1 4.2 1.2 Table 20

Synthetic Example 22 varnish name IX base - added, branched type acryl resin VII 665 phthalic anhydride 9.1 xylene 105 butyl acetate 105 DBTO 0.44 non-volatile content % 50 acid value mg KOH/g solid 8 number average molecular weigth Mn 88000 weigth average molecular weigth Mw 27000 OH value mg KOH/ g solid 32 Tg C 76 Tables 21

dispersion paste 19 20 21 titanium oxide CH - 95 62 carbon MA 100 16 Fastgel blue NK 22 amphoteric branched type acryl resin IX 20 57 55 xylene 9 14 12 butyl acetate 9 13 11 20 mirror gloss 40 60 mirror gloss 80 80 viscosity - I (cps) 160 700 600 STORAGE STABILITY 20 mirror gloss 36 60 mirror gloss 73 74 viscosity - II (cps) 200 3000 900 viscosity - II/ viscosity - I 1.3 4.3 1.5

Claims (1)

1. A branched type acryl resin of the formula:

wherein R is aliphatic, alicyclic, aromatic or heterocyclic hydrocarbon residue, X is acryl prepolymer chain, and n is a real number of 2 to 6, having a weight average molecular weight (gel permeation chromatography, polystyrene conversion) of 2000 to 200,000 and a glass transition temperature of - 20"C to 1 00 C.

2. The resin according to claim 1 wherein the acryl prepolymer has a weight average molecular weight of 1000 to 1 00,000 and a glass transition temperature of - 20"C to 1 00 C.

3. A method for preparing a branched type acryl resin of the formula:

wherein R, X and n are as defined below, characterizing by reacting a poly functional epoxy compound of the formula:

wherein R is aliphatic, alicyclic, aromatic, or heterocyclic hydrocarbon residue, and n is a real number of 2 to 6, and carboxyl bearing acryl prepolymer of the formula: X-COOH wherein X is an acryl prepolymer chain having a weight average molecular weight of 1000 to 100,000 and a glass transition temperature of - 20 to 1 00 C.

4. The method according to claim 3 wherein the acryl prepolymer is of the type prepared by using a carboxyl containing chain transfer agent in an amount corresponding to 0.2 to 8% by weight of the prepolymer in solid weight ratio.

5. The method according to claim 3 wherein the acryl prepolymer is of the type prepared by using a carboxyl containing initiator in an amount corresponding to 0.3 to 12% by weight of the prepolymer in solid weight ratio.

6. The method according to claim 4 wherein the carboxyl containing chain transfer agent is selected from the group consisting of mercapto acetic acid, 2-mercapto propionic acid, 3mercapto propionic acid and 0-mercapto benzoic acid.

7. The method according to claim 5 wherein the carboxyl containing initiator is selected from the group consisting of 4,4'azobiscyanopentanoic acid and peroxidized diglutaric acid.

8. The method according to claim 3 wherein the poly functional epoxy compound is selected from the group consisting of neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether and sorbitol polyglycidyl ether.

9. A coating resinous composition containing, as a film-forming component, a branched type acryl resin of the formula:

wherein R is aliphatic, alicyclic, aromatic or heterocyclic hydrocarbon residue, X is acryl prepolymer chain, and n is a real number of 2 to 6, having a weight average molecular weight (gel permeation chromatography, polystyrene conversion) of 2000 to 200,000 and a glass transition temperature of - 20"C to 1 00 C.

10. A modified branched type acryl resin consisting of the branched type acryl resin represented by the formula:

wherein R is aliphatic, alicyclic, aromatic or heterocyclic hydrocarbon residue of n valency, X is acryl prepolymer chain and n is a real number of 2 to 6, to which is (are) carried electron accepting group and/or electron donating group.

11. The modified resin according to claim 10, which is obtained by reacting an active hydrogen bearing branched type acryl resin of the formula:

wherein R, X nad n are as defined above, and an acid hydride and/or sultone.

1 2. The modified resin according to claim 11, wherein the acid anhydride is selected from acetic anhydride, succinic anhydride, phthalic anhydride, maleic anhydride, tetra hydrophthalic anhydride, hexahydrophthalic anhydride and trimellitic anhydride.

1 3. The modified resin according to claim 11, wherein the sultone is selected from 1,3propanesultone, 1 3-butane sultone, 1 3-octane sultone and 1,3-decane sultone.

1 t The modified resin according to claim 10, which is obtained by the reaction of active hydrogen and/or optionally introduced active alkoxy bearing branched type acryl resin of the formula:

wherein R, X and n are as defined above, and active alkoxy and/or active hydrogen bearing basic compound, 1 5. The modified resin according to claim 10, which is obtained by the reaction of poly functional epoxy compound of the formula:

wherein R and n are as defined above, and carboxyl bearing acryl prepolymer of the formula: X'-COOH wherein X' is an acryl polymer chain having basic group(s).

16. The modified resin according to claim 10, which is obtained by the combination of the method of claim 11, and the method of claim 14 and/or 15, thereby making the resin carry with electron accepting group and electron donating group.

1 7. The modified resin according to claim 10, having a weight average molecular weight (gel permeation chromatography, polystyrene conversion) of 2000 to 200,000, and a glass transition temperature of - 20 to 100"C.

1 8. The modified resin according to claim 10, whose acidity determined by a non-aqueous potentiometric titration as defined in the invention is 1.0 to 1.0 X 10-2 m mol/g solid and basicity determined by a non-aqueous potentiometric titration as degined in the invention is 1.0 to 5.0 x 10-3 m mol/g solid.

1 9. A dispersion base composition consisting essentially of the branched type acryl resin of the claim 10, and pigment.

20. The composition according to claim 19, wherein the compounding ratio of the branched type acryl resin and pigment is 10 to 90% by weight of the resin (solid) and 90 to 10% by weight of the pigment.

21. A branched type acryl resin according to claim 1, substantially as herein described in any of the foregoing Examples.

22. A method according to claim 3 for preparing a branched type acryl resin, substantially as herein described in any of the foregoing Examples.

23. A coating resinous composition according to claim 9, substantially as herein described in any of the foregoing Examples.

24. A modified branched type acryl resin according to claim 10, substantially as herein described in any of the foregoing Examples.

25. A dispersion base composition according to claim 19, substantially as herein described in any of the foregoing Examples.