JP2001172320A - Method for purifying copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying an acrylic copolymer, or the like, comprising removal of catalysts, unreacted monomers and oligomers which cause coloration. SOLUTION: To a copolymer solution obtained by polymerizing a polymerizable unsaturated monomer or a copolymer solution obtained by polymerizing a polymerizable unsaturated monomer in the presence of an unsaturated oligomer, is added activated clay and/or acid clay, and the solution is subjected to heating, stirring and then to a filtration treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying a copolymer, and more particularly, to a method for purifying an acrylic copolymer or the like by removing a catalyst causing coloration, unreacted monomers or oligomers. The purified copolymer is hardly colored and has excellent curability.

[0002]

2. Description of the Related Art Conventionally, acrylic copolymers and the like have been used in a wide range of fields such as paints, synthetic resins and adhesives. Usually, the monomers used as the raw material of the copolymer have already been decolorized and purified, and the polymerization catalyst can be easily removed. In the conventional synthesis using these, there were few problems such as coloring.

[0003] In recent years, various new polymerization techniques have been proposed for the above-mentioned copolymers, but despite the fact that copolymers produced by a polymerization method using a specific catalyst are very useful,
There was a problem that the removal of the catalyst was difficult and the obtained copolymer was colored. For example, when an oligomer having an ethylenically unsaturated group generated by using a metal complex as a catalytic chain transfer agent disclosed in Japanese Patent Publication No. Although the structure can be controlled, there is a problem that the metal complex is difficult to remove and the coloring is remarkable. Although there is a description of using activated carbon for removing the metal complex, the color of the activated carbon remains. Among the oligomers having an ethylenically unsaturated group further generated,
Depending on the type of monomer used as a raw material, low molecular weight compounds such as dimers have low reactivity and remain unreacted.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the produced copolymer solution was treated with activated clay and / or acid clay to obtain a color. It was found that the catalyst, unreacted monomers and oligomers, which cause the above, could be removed, and the copolymer after purification was hardly colored and was found to be excellent in curability and the like, and completed the present invention.

That is, the present invention relates to a copolymer solution obtained by polymerizing a polymerizable unsaturated monomer or a copolymer solution obtained by polymerizing a polymerizable unsaturated monomer in the presence of an oligomer having an ethylenically unsaturated group. An object of the present invention is to provide a method for purifying a copolymer, comprising adding activated clay and / or acidic clay to a coalescing solution, heating and stirring, and then performing a filtration treatment.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, activated clay and / or acid clay are used for purifying a copolymer solution. The activated clay and the acid clay are preferably fine particles having a size of 200 mesh or less and a small water content of 5% or less. In addition, the water content is a value assumed by heating loss at 120 ° C. for 1 hour. These are suitably added in an amount of 0.1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the solid content in the copolymer solution.

In the present invention, the above-mentioned activated clay and / or acid clay is added to a copolymer solution and heated to about 30 to 150 ° C.
After stirring at this temperature for about 0.5 to 2 hours, the activated clay and the acid clay are removed by a known filtration treatment such as celite filtration.

[0008] The copolymer solution to which the method of the present invention is applied is
In the presence of a radical polymerization initiator, a polymerizable unsaturated monomer is polymerized by a method such as solution polymerization in an organic solvent, emulsion polymerization in water, or the like, or is polymerized in the presence of an unsaturated oligomer. Examples thereof include those obtained by polymerizing an unsaturated monomer in the presence of a radical polymerization initiator by a solution polymerization method in an organic solvent, an emulsion polymerization in water, or the like.

The polymerizable unsaturated monomer is a compound having one or more polymerizable unsaturated bonds in one molecule, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n -Propyl (meth) acryle-
, Isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate
Tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl ( (Meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate )
Alkyl or cyclic alkyl (meth) acrylates having 1 to 24 carbon atoms such as acrylates; unsaturated monomers containing a carboxyl group such as (meth) acrylic acid, maleic acid and maleic anhydride; 2-hydroxyethyl (Meth) acrylate, hydroxypropyl (meth) acrylate
Monoesterified hydroxyl group-containing unsaturated monomer of a glycol having 2 to 10 carbon atoms such as 4-hydroxybutyl (meth) acrylate and the like, and (meth) acrylic acid; glycidyl (meth) acrylate, 3 N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (Meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-methylolacrylamide methyl
(Meth) acrylamide such as ter, N-methylolacrylamide butyl ether or a derivative thereof; 3-ethyl-3-methacryloyloxymethyloxetane;
Methyl-3-methacryloyloxymethyloxetane,
An oxetane ring-containing ethylenically unsaturated monomer such as 3-butyl-3-methacryloyloxymethyloxetane;
(Meth) acrylonitrile, styrene, vinyl acetate, piperidinyl-containing (meth) acrylate (for example, manufactured by Hitachi Chemical Co., Ltd., trade names “FA-711MM”, “FA-71”)
2HM "), fluorine-containing alkyl (meth) acrylate, siloxane-containing (meth) acrylate, isocyanate group-containing monomer, alkoxysilyl group-containing (meth) acrylate, and the like. These polymerizable unsaturated monomers can be used alone or in combination of two or more.

The unsaturated oligomer includes, for example, a polymer having one or more ethylenically unsaturated bonds in one molecule obtained by using the above-mentioned polymerizable unsaturated monomer.

As the radical polymerization initiator used in the above polymerization method, for example, cyclohexanone peroxide,
3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, 1,1-
Bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, n-butyl-4,4
-Bis (tert-butylperoxy) valerate, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,3-bis (tert-butylperoxy-m-isopropyl) Benzene, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, diisopropylbenzeneperoxide, tert-butylcumylperoxide, decanoylperoxide, lauroylperoxide, benzoylperoxide, 2,4- Dichlorobenzoyl peroxide, bis (tert-butylcyclohexyl) peroxydica-carbonate, tert-butyl peroxybenzoate, 2,5-dimethyl-2,
Peroxide-based polymerization initiators such as 5-di (benzoylperoxy) hexane; 2,2′-azobis (isobutyronitrile), 1,1-azobis (cyclohexane-1-carbonitrile), azocumene, 2'-azobismethylvaleronitrile, 4,4'-azobis (4-cyanovaleric acid), 2- (tert-butylazo) -2-cyanopropane, 2,2'-azobis (2,4,4-trimethyl Azo initiators such as pentane) and dimethyl-2,2'-azobis (2-methylpropionate). The use amount of these radical polymerization initiators is not particularly limited, but is usually a polymerizable unsaturated monomer-1.
0.1 to 20 parts by weight, especially 0.5
It is preferably in the range of 10 to 10 parts by weight.

As the organic solvent used when the radical polymerization reaction is carried out in an organic solvent, any organic solvent capable of dissolving or dispersing the polymerizable unsaturated monomer or unsaturated oligomer used in the polymerization is used without any particular limitation. Specific examples include, for example, heptane, toluene, xylene,
Hydrocarbon solvents such as octane and mineral spirits; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether teracetate, methyl ethyl ketone, methyl isobutyl ketone ,
Ketone solvents such as diisobutyl ketone and cyclohexanone; methanol, ethanol, isopropanol, n-
Alcohol solvents such as butanol, sec-butanol and isobutanol; n-butyl ether, dioxane,
Ether solvents such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; and aromatic petroleum solvents such as Swazol 310, Swazol 1000, and Swazol 1500 manufactured by Cosmo Oil Co., Ltd. be able to. These organic solvents can be used alone or in combination of two or more. The proportion of the organic solvent used is usually preferably in the range of 400% by weight or less based on the total weight of the polymerizable unsaturated monomer and the like at the time of the polymerization reaction.

In the method of the present invention, the polymerizable unsaturated monomer is prepared by a solution polymerization method in an organic solvent in the presence of a metal complex as a catalytic chain transfer agent and a radical polymerization initiator. A metal complex which is useful for a copolymer solution obtained by polymerizing a polymerizable unsaturated monomer in the presence of an oligomer having an ethylenically unsaturated group obtained by polymerization by a method such as emulsion polymerization, and which is a cause of coloring. Can be removed.

The polymerization method using a metal complex as a catalytic chain transfer agent is described, for example, in Japanese Patent Publication No. 6-232.
No. 09, Japanese Patent Publication No. Hei 7-35411, Japanese Patent Publication No.
JP-A-501457, JP-A-9-176256,
Macromolecules 1996, 29, 80
83-8089 and the like, and examples of the metal complex include a cobalt complex, an iron complex, a nickel complex,
Ruthenium complex, rhodium complex, palladium complex, rhenium complex, iridium complex and the like, among which,
Cobalt complexes are preferred because they efficiently act as chain transfer agents.

Examples of such a cobalt complex include, for example, Japanese Patent Publication No. 6-23209 and Japanese Patent Publication No. 7-3541.
No. 1, US Pat. No. 4,526,945, US Pat.
No. 4054, US Pat. No. 4,837,326, USP
No. 4,886,861 and US Pat. No. 5,324,879,
WO95 / 17435, Tokuhei 9-510499
Japanese Patent Application Publication No. JP-A-2005-26095 can be used. Specifically, for example, bis (borondifluorodimethyldioxyiminocyclohexane) Co (II), bis (borondifluorodimethylglyoxymate) Co
(II), bis (borondifluorodiphenylglyoxymate) Co (II), cobalt (II) chelate of vicinaliminohydroxyimino compound, cobalt (II) chelate of tetraazatetraalkylcyclotetradecatetraene , N, N'-bis (salicylidene) ethylenediaminocobalt (II) chelate, cobalt (II) chelate of dialkyldiazadioxodialkyldodecadiene,
Cobalt (II) porphyrin complex and the like. Of these, bis (borondifluorodiphenylglyoxymate) Co (II), bis (borondifluorodimethylglyoximate) Co (II) and the like are preferable because they are easily available.

Further, for example, a complex described in JP-B-8-19172, in which a radical cleavable group is directly bonded to a metal, can be used in place of the above-mentioned metal complex. . Examples of the radical cleavable group include an alkyl group, an aryl group, and a heterocyclic group. Furthermore, substituted derivatives capable of homolytic dissociation from metal ions by irradiation with visible light or ultraviolet light or heating; halides bonded to chelate metal ions; substitution with carbon atoms bonded to other anions, nitriles, esters, and metal ions And aromatic or substituted aromatic groups. In a system using these complexes, the radical polymerization initiator may not be used in combination.

The use ratio of these complexes is not particularly limited, but usually, the ratio of the polymerizable unsaturated monomer 100
1 × 10 −6 to 1 part by weight, especially 1 × 10
A range of -4 to 0.5 parts by weight is preferred.

In order to adjust the reactivity of the metal complex and improve the solubility, a known coordination compound may be added as necessary. Examples of such coordination compounds include phosphorus compounds such as triphenylphosphine and tributylphosphine; and amine compounds such as pyridine and tributylamine.

Among the polymerizable unsaturated monomers, when methacrylic acid, alkyl methacrylates, styrene, styrene derivatives, α-methylstyrene and α-methylstyrene derivatives are used, ethylenically unsaturated monomers can be obtained in high yield. This is preferable because an oligomer having a group can be obtained. Further, in the oligomer, a functional group capable of reacting with a cross-linking agent can be provided in the molecule, and specifically,
Carboxyl group, hydroxyl group, epoxy group, oxetane group,
It can be introduced by copolymerizing a polymerizable unsaturated monomer having a functional group such as an isocyanate group. The proportion of the polymerizable unsaturated monomer having such a functional group is 5 to 90% by weight, particularly 20 to 70% by weight, based on the polymerizable unsaturated monomer component constituting the oligomer having the ethylenically unsaturated group. % Is preferred from the viewpoint of the performance of the finally formed crosslinked coating film.

In producing the above-mentioned oligomer having an ethylenically unsaturated group, polymerization is carried out by heating a polymerizable unsaturated monomer in an organic solvent in the presence of a metal complex and a radical initiator. The following method (1) or (2) is preferably used to suppress the temperature rise of the system due to the above. (1) A metal complex and an organic solvent are charged into a reaction vessel, and a polymerizable unsaturated monomer and a radical polymerization initiator are mixed and dropped or separated and dropped over a predetermined time with stirring at a temperature of 60 to 200 ° C. . (2) In the method (1), a part or all of the metal complex is mixed and dropped or separated and dropped together with the polymerizable unsaturated monomer.

The dimer formed when, for example, glycidyl methacrylate is used as the above polymerizable unsaturated monomer has a very low reactivity, and may degrade various properties of paints and coatings. Can be effectively removed.

A copolymer solution using the above-mentioned oligomer having an ethylenically unsaturated group can be obtained by subjecting the oligomer to a radical polymerization reaction of the above-mentioned polymerizable unsaturated monomer. Among the polymerizable unsaturated monomers described above, particularly, methacrylic acid, alkyl methacrylates,
Styrene, styrene derivative, α-methylstyrene, α-
It is preferable to use a methylstyrene derivative because a copolymer solution can be obtained in high yield. The ratio of the two can be arbitrarily selected according to the purpose, but based on the total solid weight of both, the oligomer having an ethylenically unsaturated group is 1 to
99%, especially 5 to 90%, when the polymerizable unsaturated monomer is 99%
１1%, particularly preferably 95〜１０10%.

As described above, a purified copolymer is obtained by the method of the present invention, and a coating composition containing the copolymer as a binder component is obtained. According to the paint, a coating film excellent in various performances can be formed.

When the copolymer has one or more kinds of functional groups capable of three-dimensionally cross-linking reaction, a self-curing type that cross-links only with the functional group and a separation type that cross-links by reaction with a curing agent used in combination. The self-curable functional group includes, for example, an oxirane ring functional group such as an epoxy group and an oxetanyl group. Further, as the functional group of the separation type, for example, an epoxy group / carboxyl group,
Epoxy group / hydroxyl group, epoxy group / hydroxyl group / carboxyl group, hydroxyl group / isocyanate-
And a combination of groups. The introduction of these functional groups into the copolymer can be carried out by polymerizing using a polymerizable unsaturated monomer having these functional groups.

In the case of the separation type, a curing agent having a functional group capable of reacting with the functional group provided in the copolymer by a combination of the functional groups described above is used. As the curing agent, for example,
Polycarboxylic acids and their (poly) anhydrides, amino resins,
Polyamine, polyamide, polyisocyanate compound,
And polyepoxy compounds.

Examples of the polycarboxylic acids and their (poly) anhydrides include adipic acid, sebacic acid, suberic acid, succinic acid, glutanic acid, maleic acid, fumaric acid, dodecandioic acid, pimelic acid, azelaic acid, and itaconic acid. acid,
Aliphatic polycarboxylic acids such as citraconic acid and its (poly) anhydride; terephthalic acid, isophthalic acid, phthalic acid,
Aromatic polycarboxylic acids such as trimellitic acid and pyromellitic acid and their (poly) anhydrides; aliphatic polycarboxylic acids such as hexahydrophthalic acid, hexahydroisophthalic acid and methylhexahydrophthalic acid and their anhydrides (( Anhydrous) polycarboxylic acid compounds and the like)).

Examples of the amino resin include a methylolated amino resin obtained by reacting an aldehyde with an amino component such as melamine, urea, benzoguanamine, acetoguanamine, steloguanamine, sporoguanamine and dicyandiamide. Aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. The methylated amino resin may be etherified with a suitable alcohol. Examples of the alcohol used for the etherification include methyl alcohol, ethyl alcohol, and n.
-Propyl alcohol, i-propyl alcohol, n-
Butyl alcohol, i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

Examples of polyamines and polyamides include aliphatic and aromatic ones, which may be unmodified or modified amine adducts. For example, aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, pentanediamine, aminoethylpiperazine; m-phenylenediamine, p, p-diaminodiphenylmethane, diaminodiphenylsulfone, benzyldimethylamine Aromatic polyamines such as butyl glycidyl ether and phenyl glycidyl ether; adducts of polyamines such as ethylenediamine; adducts of polyamines such as ethylenediamine with ethylene oxide; aliphatic polyamines such as ethylenediamine And acrylonitrile are reacted (cyanoethylation) with an epoxy compound by reacting a large excess of polyamine with the diepoxy compound. Amine adducts made by adding the polyamine 2 molecules per molecule; polyamide compounds of the reaction products of aliphatic dimer and diamine.

Examples of the polyisocyanate compound include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate.
Alicyclic diisocyanates such as hydrogenated xylylene diisocyanate and isophorone diisocyanate;
Aromatic diisocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate; one or more cyclic polymers selected from these diisocyanates;
And an isocyanate burette.

Examples of the polyepoxy compound include ethylene glycol diglycidyl ether and hexane di-
Rudiglycidyl ether, neopentyl glycol-diglycidyl ether, glycerin diglycidyl ether,
Polyglycidyl ethers of polyhydric alcohols such as glycerin triglycidyl ether, sorbitol polyglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and bisphenol A diglycidyl ether; p-oxy Examples include glycidyl ester / glycidyl ether of benzoic acid, diglycidyl ester of phthalic acid, diglycidyl ester of hexahydrophthalic acid, epoxy resin containing a hydantoin ring, and vinyl resin having an epoxy group in a side chain.

In order to accelerate the crosslinking reaction, a curing catalyst may be used. Examples of such a curing catalyst include onium salt compounds, imidazole compounds, sulfonic acid compounds, primary, secondary, and tertiary amine compounds, dicyandiamide, metals, organometallic compounds, metal chelate complexes and metals. Conventionally known salts and the like can be mentioned, and these can be used alone or in combination of two or more.

If necessary, the coating composition may further contain a pigment, a filler, a fluidity regulator, a blocking inhibitor, an ultraviolet absorber, an ultraviolet stabilizer, a surface stabilizer, an anti-bake agent, and an antioxidant. And paint additives such as a charge controlling agent and a curing accelerator.

The coating composition is not particularly limited and may be in various forms such as solvent type, aqueous type and powder type.

[0034]

According to the method of the present invention, an acrylic copolymer or the like useful as a binder component for synthetic resins, paints, adhesives and the like can be removed from the catalyst and unreacted monomers and oligomers which cause coloring. can get.

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. “Parts” and “%” mean “parts by weight” and “% by weight”, respectively.

Of the oligomer having an ethylenically unsaturated group
Producing all of the polymerizable monomer - and organic solvent, prior to use, by feeding 1 hour with the nitrogen gas and subjected degassed (deoxygenated).

Production Example 1 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device was charged with 100 parts of toluene as a solvent, and heated to 105 ° C. while passing nitrogen gas. 100 parts of glycidyl methacrylate as a polymerizable monomer and bis (borondifluorodimethylglyoximate) Co (II) 0.01 as a metal complex.
And a mixture of 2.0 parts of 2,2'-azobis (2-methylbutyronitrile) as a radical initiator were added dropwise over 3 hours. Then, after leaving at 105 ° C. for 1 hour, 2,2′-azobis (2-methylbutyronitrile) is further added.
0.5 part and 10 parts of toluene were added dropwise over 1 hour.
The reaction was completed by leaving at 5 ° C. for 1 hour. Thereafter, toluene was removed by distillation under reduced pressure, and the mixture was cooled to obtain an oligomer (A-1) having an ethylenically unsaturated group.

Production Example 2 "Glycidyl methacrylate 100" in Production Example 1
Parts) and “100 parts of 2-hydroxyethyl methacrylate”, and the other steps were performed in the same manner as in Production Example 1 to obtain an oligomer having an ethylenically unsaturated group (A
-2) was obtained.

Production Example 3 of Acrylic Copolymer Solution Oligomer (A-1) having an ethylenically unsaturated group in a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device. 17 parts and 100 parts of xylene were charged and heated to 125 ° C. while passing nitrogen gas. As a polymerizable monomer, 23 parts of glycidyl methacrylate, 40 parts of methyl methacrylate, and isobutyl methacrylate were added. 15 parts, n-butyl methacrylate 5 parts,
2,2'-azobis (2-methylbutyronitrile) 0.
5 parts of the mixture were added dropwise over 3 hours. Then 125
C. for 1 hour, then 0.5 part of 2,2'-azobis (2-methylbutyronitrile) and 10 parts of xylene 10
The reaction mixture was added dropwise over 1 hour, left at 125 ° C. for 1 hour to terminate the reaction, and cooled to obtain an acrylic copolymer (B-1) solution. The acrylic copolymer (B-
The weight average molecular weight of 1) was 8,000.

Production Example 4 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device was charged with 15 parts of an oligomer having an ethylenically unsaturated group (A-2) and 100 parts of xylene. The mixture was heated to 125 ° C. while passing nitrogen gas, and 10 parts of 2-hydroxyethyl methacrylate, 45 parts of methyl methacrylate, 20 parts of isobutyl methacrylate were added thereto as polymerizable monomers. n-butyl methacrylate
And a mixture of 0.5 parts of 2,2′-azobis (2-methylbutyronitrile) was added dropwise over 3 hours. Then, after leaving at 125 ° C. for 1 hour, 2,2′-
0.5 parts of azobis (2-methylbutyronitrile) and 10 parts of xylene were added dropwise over 1 hour.
The reaction was completed by allowing the mixture to stand for a period of time, followed by cooling to obtain an acrylic copolymer (B-2) solution. The weight average molecular weight of the acrylic copolymer (B-2) was 9,000.

Example 1 Purification of Copolymer Solution Example 1 The acrylic copolymer (B) prepared above was placed in a reaction vessel equipped with a thermometer, a thermostat, a stirrer, and a reflux condenser.
-1) 100 parts of the solution and 2 parts of activated clay (trade name "Powdered activated clay SA1 low moisture product" manufactured by Japan Active Shirato Co.)
The mixture was heated to 100 ° C. while passing nitrogen gas, and stirred for 1 hour. Thereafter, a filtration treatment was performed using celite and filter paper to remove activated clay. After cooling, a purified acrylic copolymer (C-1) solution was obtained.

Example 2 Purification was completed in the same manner as in Example 1 except that the acrylic copolymer (B-1) solution was changed to the acrylic copolymer (B-2) solution. An acrylic copolymer (C-2) solution was obtained.

Example 3 The procedure of Example 1 was repeated, except that the used amount of activated clay was changed from “2 parts” to “25 parts”. D-1) A solution was obtained.

Example 4 Purification was completed in the same manner as in Example 3, except that the acrylic copolymer (B-1) solution was changed to the acrylic copolymer (B-2) solution. An acrylic copolymer (D-2) solution was obtained.

Comparative Example 1 Example 1 was the same as Example 1 except that “2 parts of activated clay” was changed to “2 parts of activated carbon (manufactured by Wako Pure Chemical Industries, trade name“ activated carbon, granular ”)”. The same procedure was performed to obtain a purified acrylic copolymer (E-1) solution.

Comparative Example 2 Example 2 was the same as Example 2 except that “2 parts of activated clay” was changed to 2 parts of “activated carbon (manufactured by Wako Pure Chemical Industries, trade name“ activated carbon, granular ”)”. The same procedure was performed to obtain a purified acrylic copolymer (E-2) solution.

The acrylic copolymer (B-1) before purification
The solution and the acrylic copolymer (B-2) solution were used as Comparative Examples 3 and 4, respectively.

Each of the acrylic copolymer solutions purified in these Examples and Comparative Examples was subjected to distillation under reduced pressure to remove xylene and cooled, and then 100 parts of each acrylic copolymer was dissolved in 100 parts of toluene to form a varnish. And the degree of coloring was evaluated. Table 1 shows the results. The coloring degree is APHA.
(American Public Health As
sn. According to the method (2), the color was visually compared with a platinum-cobalt standard solution and evaluated. The larger the value, the more colored.

[0049]

[Table 1]

Preparation of coating compositions Examples 5 to 8 and Comparative Examples 5 to 8 Combinations and amounts of the above-purified or purified acrylic copolymers, curing agents, curing catalysts and the like shown in Table 2. After dry-blending with a Henschel mixer at room temperature, the mixture was melt-kneaded with an extruder. These are then cooled and then finely ground with a pin disk.
Each powder coating composition was obtained by filtration through 50 mesh. still,
(Note 1) and (Note 2) in Table 2 are as follows. Each of the obtained powder coating compositions was subjected to the following performance tests. The results are shown in Table 2. (Note 1) “IPDI B-1530”: Daicel Huls, ε-caprolactone-blocked isophorone diisocyanate (Note 2) “Neostan U-200”: Nitto Kasei, trade name, dibutyltin dilaurate performance test method ( * 1) Blocking resistance of paint: Each powder paint was placed in a cylindrical container having a bottom area of about 20 cm 2 so as to have a height of 6 cm, and left at 30 ° C. for 7 days. Thereafter, the powder coating was taken out and the state was visually observed. ◎ has no hardening at all and has good blocking resistance, は has slight hardening but can be easily released with a finger, △ has hardened and cannot be released unless strongly pressed with a finger, and has poor blocking resistance. The results show that clumps are formed, cannot be released even when strongly pressed with a finger, and have very poor blocking resistance.

(* 2) Appearance of coating film: An epoxy resin-based cationic electrodeposition paint was electrodeposited on a 0.8 mm thick dull steel plate which had been subjected to a zinc phosphate conversion treatment to a dry film thickness of 20 μm. After heating and curing at 30 ° C. for 30 minutes, an intermediate coating surface for automobile is applied so as to have a dry film thickness of 20 μm, and cured by heating at 140 ° C. for 30 minutes.
After sanding with a # 400 sandpaper, "Magiclon Beaut Coat HM-22" (trade name, metallic paint, manufactured by Kansai Paint Co., Ltd.) was applied so as to have a dry film thickness of 20 μm, and was heated at 140 ° C. It was cured by heating for 30 minutes to obtain a test plate. Each of the powder coatings was electrostatically coated on the coated surface so as to have a film thickness of 70 μm, and was cured by heating at 16 ° C. for 30 minutes. The coloring degree of the obtained coating film was measured by measuring the color difference b * value of the coating film in accordance with JIS Z-8722. b *
The larger the value, the more colored.

The finished appearance (glossiness, smoothness) of the obtained coating film was visually observed. ○ indicates good gloss and smoothness, Δ indicates slightly poor gloss and smoothness, and X indicates very poor gloss and smoothness.

(* 3) Gloss: The 60 ° specular reflectance of each powder coating applied in the same manner as in (* 2) above was measured according to JIS.
It was measured according to K-5400.

(* 4) Acid resistance: 40% sulfuric acid aqueous solution was applied to the coating surface of each powder coating in the same manner as in (* 2) above.
After 4 cc was dropped, the mixture was heated on a hot plate heated to 85 ° C. for 15 minutes, washed with water, and the coating film was visually observed. ◎ indicates no change and good, and ○ indicates that there is a very slight level difference at the interface between the dripped portion and the non-dropped portion.
Indicates a step at the boundary between the dripped portion and the non-dropped portion, and indicates poor, and x indicates that the coating film of the dropped portion is whitened and defective.

(* 5) Solvent resistance: The grease impregnated with xylene was reciprocated 10 times with the fingertip strongly pressed against the coating surface of each powder coating applied in the same manner as in (* 2) above. The appearance of the coating film after wiping was visually observed. ◎: no change, good, ○: very slight traces are observed in the wiped part, good, △: scratches and glossy appearance are observed in the wiped part, ×: paint in the wiped part It shows that it was whitened.

(* 6) Scratch resistance: A coated plate coated in the same manner as in (* 2) above was attached to a roof of an automobile, and the state of the coated surface after being washed five times with a car washer was visually observed. . As the car washer, "PO 20FWRC" manufactured by Yasui Sangyo was used. ◎ indicates that almost no scratches are found, ○ indicates that some scratches are found, but the degree is light, △ indicates that scratches are conspicuous, and X indicates that marked scratches are clearly observed.

[0057]

[Table 2]

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4J038 CC021 CC022 CF031 CF032 CG031 CG032 CG071 CG072 CG141 CG142 CG161 CG162 CG171 CG172 CH031 CH032 CH041 CH042 CH071 CH072 CH121 CH122 CH171 CH172 CH201 AL202P04P02 AL06 AL10Q AM02P AM21P BA02P BA03P BA29P BA77P BB07P BC02P BC53P BC65P CA01 CA04 FA03 FA04 FA19 GC01 GC29 GC35 JA01

Claims (5)

[Claims] An activated clay and / or a copolymer solution obtained by polymerizing a polymerizable unsaturated monomer in the presence of an unsaturated oligomer or a polymer solution obtained by polymerizing a polymerizable unsaturated monomer in the presence of an unsaturated oligomer. Alternatively, a method for purifying a copolymer, comprising adding an acid clay, heating and stirring, and then performing a filtration treatment. 2. The unsaturated oligomer is an oligomer having an ethylenically unsaturated group obtained by polymerizing a polymerizable unsaturated monomer in the presence of a metal complex as a catalytic chain transfer agent and a radical polymerization initiator. A method for purifying the copolymer according to claim 1. 3. The method for purifying a copolymer according to claim 2, wherein the polymerizable unsaturated monomer is glycidyl methacrylate. 4. A copolymer purified by the purification method according to claim 1. 5. A coating composition comprising the copolymer according to claim 4.