JPS63186722A - Selfcrosslinking resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give a one-pack coating or adhesive excellent in low-temperature curability and film properties, by copolymerizing an isocyanato-containing ethylenically unsaturated monomer with a hydroxyl-containing ethylenically unsaturated monomer and, optionally, an ethylenically unsaturated monomer. CONSTITUTION:A selfcrosslinking resin composition prepared by copolymerizing an isocyanato-containing ethylenically unsaturated monomer of formula I (wherein R is H or CH3) or a monomer derived by blocking the NCO group of said monomer with a blocking agent of a phenol, lactam or the like type or formula II (wherein R is the same as the above and B is a residue of the blocking agent) with a hydroxyl-containing ethylenically unsaturated monomer [e.g., 2-hydroxyethyl (meth)acrylate] and, optionally, a functional group-free ethylenically unsaturated monomer [e.g., methyl (meth)acrylate]. This composition is useful as a one-pack coating or adhesive which is excellent in storage stability and can give a coating film excellent in all of low-temperature curability, weathering resistance, corrosion resistance, chemical resistance, mechanical properties, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition containing a self-crosslinking resin having an isocyanate group and a hydroxyl group in the molecule.

The resin composition obtained by the present invention forms a coating film with excellent low temperature curability. The resulting coating film has excellent flexibility, chemical resistance, water resistance, corrosion resistance, and impact resistance, and is therefore extremely useful as a baking paint or bone cement for metals, plastics, inorganic materials, etc.

Conventional technology Generally, resin compositions for coatings consisting of blocked polyisocyanates and hydroxyl group-containing compounds such as polyether polyols, polyester polyols, acrylic polyols, and epoxy resins have excellent corrosion resistance, chemical resistance, mechanical properties, etc. Because of this, it is widely used as a baking paint for automobile exteriors, home appliances, enamel electric wires, etc.

However, the compatibility between the blocked polyisocyanate and the hydroxyl group-containing compound is not necessarily sufficient, and even when they are compatible, when looking microscopically at the cured coating film, the surface and the base material have different compositions. There is.

In order to solve this drawback, one isocyanate group of diisocyanate is blocked to create a so-called half-block, and the remaining isocyanate group is reacted with a hydroxyl group-containing ethylenically unsaturated monomer to synthesize vinyl urethane. Copolymerization of the obtained vinyl urethane with an ethylenically unsaturated monomer containing a hydroxyl group-containing ethylenically unsaturated monomer to obtain a self-crosslinking resin is also being considered, but it is difficult to quantify the half block form. It is difficult to obtain a satisfactory result, and it is difficult to obtain a satisfactory result.

In general, a liquid paint containing a combination of a blocked polyisocyanate and a polyol compound requires heating at about 140 to 180° C. for about 20 to 40 minutes in order to cure. Therefore, the objects to be coated are limited to metal products. Even if the above-mentioned self-crosslinking resins are used, one that can be cured at low temperature has not been obtained.

Problems to be Solved by the Invention An object of the present invention is to provide a self-crosslinking resin composition that provides a liquid paint or bone cement with excellent storage stability, low-temperature curability, and coating film properties. It is in.

Means to solve the problem In view of the above-mentioned circumstances, we have developed a single solution that provides a coating film with excellent storage stability, low-temperature curing, weather resistance, corrosion resistance, chemical resistance, and mechanical properties. As a result of intensive research on polyester resin compositions, we have found that a specific isocyanate group-containing ethylenically unsaturated monomer, a hydroxyl group-containing ethylenically unsaturated monomer, and if necessary an ethylenically unsaturated monomer are copolymerized. It was discovered that a self-crosslinking resin composition containing the resin described above has excellent two-layer low-temperature curability and coating film properties, and based on this knowledge, the present invention was completed.

That is, the present invention provides a compound represented by (1) (a) general formula [wherein R represents hydrogen or a methyl group] or (b) a compound represented by the general formula [wherein R represents hydrogen or a methyl group, and B represents the residue of a blocking agent].

The present invention relates to a self-crosslinking resin composition containing a resin obtained by copolymerizing (2) a hydroxyl group-containing ethylenically unsaturated monomer and optionally (3) an ethylenically unsaturated monomer.

(1) represented by the above general formula used in the present invention (
Examples of the isocyanate compound a) include p-isopropenyl-α, α-dimethylbenzyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate, p-ethylenyl-α, α-dimethylbenzyl-isocyanate, m-ethylenyl-α , α-dimethylbenzyl isocyanate and the like. Among these, isopropenyl-α,α-dimethylbenzyl isocyanate (hereinafter abbreviated as TMI) is particularly preferred.

TMI monomers are described, for example, in U.S. Pat. No. 3,290.35.
Specification No. 0, Specification No. 4430.577, No. 4,37
7.530, No. 4,439,816, etc.

The content of the compound represented by the above general formula (a) in the resin is usually about 1 to 50% by weight, preferably about 3 to 15% by weight. Although this compound can be used in the form of free isocyanate, the compound of the general formula (1) is obtained by blocking the isocyanate group with an isocyanate group blocking agent as shown below.
It can also be used in the form of so-called blocked isocyanates represented by Cb'). In the formula, B is the residue of a blocking agent, and therefore DH indicates a blocking agent. It is preferable to use it in the form of a blocked isocyanate, since this further improves the storage stability of the composition.

Blocking agents represented by D I-I include, for example, phenol-based, lactam-based, active methylene-based, alcohol-based 1-mercaptan-based, acid amide-based, imide-based, amine-based, imidazole-based, urea-based, carbamate-based, Any blocking agent such as imine type, oxime type or sulfite type can be used, but especially phenol type,
Lactam type, alcohol type.

Oxime-based blocking agents are advantageously used.

Specific examples of these blocking agents include the following.

Phenolic blocking agents: phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol.

p-hydroxydiphenyl, t-butylphenol.

0-isopropylphenol, o-5ec-butylphenol, p-nonylphenol, pt-octylphenol, hydroxybenzoic acid, hydroxybenzoic acid ester, etc.

Lactam-based blocking agents: ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propiolactam, etc.

Active methylene blocking agents: diethyl malonate, dimethyl malonate, ethyl acetoacetate. Methyl acetoacetate, acetylacetone, etc.

Alcohol blocking agent: methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol.

n-amyl alcohol, t-amyl alcohol, lauryl alcohol, ethylene glycol mono, methyl ether, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether,
Glycolic acid esters such as benzyl alcohol, methoxymethanol, glycolic acid, medyl glycolate, ethyl glycolate, and butyl glycolate; lactic acid esters such as lactic acid, methyl lactate, ethyl lactate, and butyl lactate.

Methylorurea. Methylolmelamine, diacetone alcohol, ethylene chlorohydrin, ethylene bromohydrin, 1,3-dichloro-2-propatol, ω hydroperfluoroalcohol, acetocyanhydrin, etc.

Mercaptan-based blocking agents Nibutyl mercaptan, hexyl mercaptan, -butyl mercaptan, t-dodecyl mercaptan.

2-mercaptobenzothiazole, thiophenol, methyldiophenol, ethyldiophenol, etc.

Acid amide blocking agent: acetanilide, acedoanidicite, acetotoluide,
Acrylamide, methacrylamide, acetamide, stearamide, benzamide, etc.

Imide blocking agents: succinimide, phthalic imide, maleic imide, etc.

Amine blocking agents Nidiphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole.

Aniline, naphdylamine, butylamine, dibdelamine, butylphenylamine, etc.

Imidazole blocking agent: imidazole, 2-ethylimidazole, etc.

Urea-based blocking agent: urea, thiourea, ethylene urea, ethylene urea 91
, 3-diphenylurea, etc.

Carbamate-based blocking agents: phenyl N-phenylcarbamate, 2-oxacylidone, etc.

Imine blocking agent: Ethyleneimine, propyleneimine, etc.

Oxime-based blocking agents: formamidoxime, acetaldoxime, acetoxime, medyl edyl ketoxime, diacedyl monooxime, benzophenone oxime, cyclohexane oxime, etc.

Sulfite-based blocking agent: Sodium bisulfite, potassium bisulfite, etc.

Examples of the hydroxyl group-containing ethylenically unsaturated monomer (2) used in the present invention include 2-hydroxyedyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, and
．． Acrylates such as 3-dihydroxypropyl acrylate, 2-hydroxy-3-phenoxyethyl acrylate, 2-hydroxy-3-ethoxyethyl acrylate, such as 2-hydroxyethyl methacrylate,
Methacrylates such as 2-hydroxypropyl methacrylate, 2-hydroxy-3-phenoxy methacrylate, fumarates such as bis(2-hydroxyethyl) fumarate, bis(2-hydroxypropyl) fumarate, e.g. bis(2-hydroxyethyl) malate), bis(2-hydroxypropyl) malate, and other substances that have two hydroxyl groups in the molecule; for example, unsaturated alcohols such as allyl alcohol, cinnamon alcohol, and crotonyl alcohol. . The content of these hydroxyl group-containing ethylenically unsaturated monomers in the resin is usually about 1 to 50% by weight, preferably about 3 to 15% by weight.

The self-crosslinking resin of the present invention comprises isocyanate compounds represented by (a) and (1+) of the general formula (1) and (2).
) can also be obtained by copolymerizing only the hydroxyl group-containing ethylenically unsaturated monomers, but usually one or more ethylenically unsaturated monomers without functional groups (3) are copolymerized. Used as a monomer.

Examples of such monomers include acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, such as methyl methacrylate, ethyl methacrylate, and n-propyl methacrylate. , isopropyl methacrylate-1, n-butyl methacrylate, t-butyl methacrylate, fumarates such as dimethyl fumarate, diethyl fumarate, di-n-butyl fumarate, etc. malates such as di-n-butyl malate, styrene, vinyltoluene, α
- Styrenic monomers such as methylstyrene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, acrylonitrile, acrylamide, etc. The content of these ethylenically unsaturated monomers in the resin is usually about 0 to 98% by weight, preferably about 7% by weight.
It is about 0 to 90% by weight.

The self-crosslinking resin of the present invention can be produced by any of the solution polymerization method, bulk polymerization method, suspension polymerization method, and emulsion polymerization method in an inert solvent in the presence of a polymerization initiator that generates radicals. A solution polymerization method in a system free of is preferred.

Examples of solvents include esters such as ethyl acetate, butyl acetate, cellosolve acetate, carpitol acetate, dibasic acid paste methyl ester, ketones such as methyl edyl ketone, methyl isobutyl ketone, and cyclohexanone, toluene, xylene, and Tsurupez. #lOO
and aromatic solvents such as Tsurupetz #150.

Generally, the total monomer concentration is about 20 to 80 ffiffi%, and the polymerization initiators include oil-soluble free M, group-forming catalysts such as α, α'-azobisisobutyronitrile, benzoyl peroxide, t- Butyl hydroperoxide, cumene hydroperoxide, etc. are used, and if necessary, it is also possible to use a redox catalyst in combination with an appropriate reducing substance. Furthermore, a small amount of butyl mercaptan, dodecyl mercaptan, etc. may be added as a resin molecule m regulator, for example. Polymerization is carried out in an inert gas under normal pressure at around 30 to 100°C.

The resin thus obtained has at least one isocyanate group and at least one hydroxyl group, and has a molecular weight of about 1,000 to 1,000,000, preferably about 5,000 to 100, It is about 000.

The resin obtained by copolymerizing the blocked isocyanate represented by (b) of the general formula (1) is a new resin that has not been published in any literature.

The self-crosslinking resin composition of the present invention obtained in this way can be used as a hard-coated paint, an adhesive, an air-drying paint, an adhesive, etc. by adding a curing catalyst at the time of use. By adding a curing catalyst, the one-component resin composition can be advantageously used as a baking paint or adhesive.

Examples of curing catalysts include bismuth nitrate, 2-ethylhexoate, lead benzoate, lead oleate, sodium trichloroferrate, sodium propionate, lithium acetate, potassium oleate, tetrabutyltin,
Tributyltin chloride, dibutyltin dichloride, butyltin trichloride, tin chloride, tributyltin felt,
Tributyltin cyanate, tin octylate, tin oleate, tin tartrate, dibutyltin di(2-ethylhexoate), dibenzyltin di(2-ethylhexoate), dibutyltin dilaurate, dibutyltin diisooctyl maleate, dibutyltin sulfide, dibutyltin dipt oxide, dibdeltin bis(O-phenylferulate), dibdeltinbis(acetylacetonate), di(2-ethylhexyl)tin oxide, titanium tetrachloride, dibutylditane dichloride, tetrabutyl ditanate, butoxytitanium trichloride, iron trichloride, 2 - Ethylhexoate (■), iron acetylacetone (■), ferrocene, antimony trichloride, antimony pentachloride, triphenylantimony dichloride, triphenylantimony, uranium nitrate, cadmium nitrate, cadmium didiphosphate, benzoin Cobalt acid, cobalt 2-edylhexonate, thorium nitrate, triphenylaluminum, trioctylaluminum, aluminum oleate, diphenylmercury, °2~zinc ethylhexonate, zinc naphthenate, nilakerosene, hexacarbonylmolybdenum, cerium nitrate, vanadium trichloride , copper 2-ethylhexonic acid, copper acetate, manganese 2-ethylhexonic acid, zirconium 2-ethylhexonic acid, zirconium naphthenate, triphenyl arsenic, arsenic trichloride, boron trifluoride-diethyl ether complex, pyridine borane, calcium acetate, acetic acid Examples include metal catalysts such as barium.

In addition, organotin compounds represented by the following general formula (wherein R represents the same or different alkyl groups, and X represents the same or different halogen atoms, hydroxyl groups, alkoxy groups, or acyloxy groups) also include isocyanate groups and hydroxyl groups. It can be preferably used in the present invention because it has a catalytic effect on the reaction with.

Specific examples of such organic tin compounds include, for example, tetra-n-butyl-1,3-diacetyloxydista, l
xane, tetra-n-propyl-1,3-diacetyloxydistanoxane, tetra-n-propyl-1-chloro-3-hydroxydistanoxane, tetra-n-butyl-! -Chloro-3-hydroxydistanoxane, tetramethyl-! .

3-Diacetyloxydistanoxane, tetramethyl-
1-chloro-3-acetyloxydistanoxane, tetra-n-butyl-1,3-diformyloxydistanoxane, tetra-n-butyl-1゜3-diacryloxydistanoxane, tetra-n-butyl -1,3-dilauryloxydistanoxane, tetra-n-butyl-1,
3-dioleyloxydistanoxane, tetra-n-butyl-1,3-distearyloxydistanoxane, tetra-n-butyl-1,3-diphenylacederoxydistanoxane, tetra-n-butyl -1,3-diisocyanodistanoxane, tetra-n-butyl-1-acedeloxy-3-hydroxydistanoxane, tetra-
n-propyl-1-acetyloxy-3-hydroxydistanoxane, tetramethyl-1-acetyloxy-3
-Hydroxydistanoxane, tetra-n-butyl-1
, 3-dichlorodistanoxane, tetramethyl-1,3
-dichlorodistanoxane, tetra-n-butyl-1,
3-dipropoxydistanoxane, tetra-n-propyl-1,3-dipropoxydistanoxane, tetra-n
-Butyl-I-propoxy-3-acetyloxydistanoxane, tetra-n-propyl-1-hydroxy-3
-ethoxydistanoxane, 1,1-dibdel-3,3
Examples include -dipropyl-■-hydroxy-3-acetyloxydistanoxane, l+3-dipropyl-1,3-dibutyl-1-chloro-3-hydroxydistanoxane, and the like.

These metal catalysts may be used alone or as a mixture of two or more. Furthermore, for example trimethylamine, triethylamine, dimethylcyclohexylamine, N-
Tetramethylhexane-1,6-diamine, N-pentamedyldiethylenetriamine, 2-methyl-1,4-diazabicyclo[2°2.2]octane, 1,5-diazabicyclo(4,3°0) Tertiary amines such as -5-nonene can also be preferably used.

In the present invention, among the various curing catalysts mentioned above, tin octylate, dibutyltin dilaurate,
Organic tin compounds such as distanoxanes are preferably used. The curing catalyst claws vary depending on the type, but usually,
It is about 0.01 to 5% by weight.

When baking paint is used as an adhesive, baking conditions vary depending on the presence or absence of blocking agents and the type, but usually about 40~
The temperature is about 150°C. Approximately 4 if no blocking agent is used
The temperature is about 0-80°C, about too-120°C when an oxime-based blocking agent is used, and about 130-150°C when an alcohol-based or lactam-based blocking agent is used.

If a block compound is used as the isocyanate compound and a part of the solvent is replaced with a monoalcohol, the storage stability of the liquid resin composition will be further improved, so it can be used more advantageously.

The self-crosslinking resin composition of the present invention has at least 61
It has at least one isocyanate group which may be blocked and at least one hydroxyl group. Urethane bonds are formed by intermolecular reaction between isocyanate groups and hydroxyl groups by heating or a curing catalyst, resulting in crosslinking. In the case of blocked isocyanate groups, the isocyanate groups are regenerated by heating or a curing catalyst, and the regenerated isocyanate groups react with hydroxyl groups to form urethane bonds and crosslink.

The self-crosslinking resin composition of the present invention has excellent storage stability,
In particular, those using blocked TMI do not show any change in viscosity or hardenability even if stored at 40° C. for two months or more.

Therefore, it is possible to form a coating film with excellent low-temperature curability. The resulting coating film has excellent mechanical properties such as flexibility, chemical resistance, water resistance, corrosion resistance, and impact resistance, so it is suitable for metals,
It can be used as a baking paint or adhesive for plastics, inorganic materials, etc.

Next, the present invention will be described in more detail with reference to Examples. In the examples, parts and % each indicate parts by weight (m%).

Example 1 Thermometer, fi r+! A reactor equipped with a dropping funnel flow condenser and a nitrogen inlet tube was charged with 95 parts of toluene/isopropanol (70/30) mixed solvent, and 8 parts of m-TMI and methyl methacrylate were heated at about 80°C under nitrogen introduction. 45 parts, 536 parts of n-butyl acrylate, 10 parts of hydroxyethyl acrylate.

1 part of α,α'-azobisisobutyronitrile was added dropwise over 6 hours. 2 hours after the completion of dropping, add the above mixed solvent 5.
α, α′-Azobisisobutyronitrile dissolved in 0 parts
．． After adding 25 parts, the polymerization was continued for a total of 10 hours.

The resulting resin had a nonvolatile content of 50% and an ff1ffl average molecular weight of 25,000. The infrared absorption spectrum of the resin is shown in FIG.

Absorption based on hydroxyl group at 3550 cm-', 2260 cm
-' absorption based on isocyanate groups is observed,
There was no amide absorption band around 1530 cm-'. From the above results, it was confirmed that the isocyanate group of m-TMI and the hydroxyl group of hydroxyedyl methacrylate were present in the resin without reacting.

135 parts of this resin solution and 45 parts of titanium dioxide.

Cellosolve acetate IQ part, n-butyl acetate) 1
0 parts were kneaded in a ball mill to prepare a white paint. 1,
1,3.3-tetra-n-butyl-1,3-diacetoxydistanoxane 0. Add IPHL, 0,8 m
The coating film was spray-painted on a mild steel plate to a thickness of 50 μm and cured at room temperature for one week, resulting in a lead board hardness of 2 to I.
, passed the goban test, passed the bending test (3mmmm), passed the acid resistance test (%HtSO, 7 days), passed the alkali resistance test (5
%Na0I-T, 7 days) passed, volatile oil resistance passed, 60°
The specular gloss was 95.

Accelerated weathering tester (Q-Panel Co., USA) Gloss retention after irradiation for too long was 95%. Color difference was 0.5.

Example 2 A resin solution was obtained in the same manner as in Example 1 except that 11.5 parts of the methyl ethyl ketoxime block of m-TMI was used instead of the m-TMIB part.

Figure 2 shows the infrared absorption spectrum of this resin.
Unlike the spectrum of the resin in Example 1, 2260 cm
-' absorption by isocyanate groups was not observed, confirming that the isocyanate groups were blocked.

To this resin solution, 10 parts of ethyl alcohol, 85 parts of n-butyl acetate, 1.1. ．． 0.22 part of 3.3-tetra-n-butyl-1,3-diacetoxydistanoxane was added to prepare a liquid paint solution.

A mild steel plate was spray-painted in the same manner as in Example 1, and 120
The paint film baked at °C for 20 minutes has a pencil hardness of 2 points ■.

Solvent resistance was good. This -liquid paint was spray-coated onto the white coated board obtained in Example 1 so that the cured film had a thickness of 30 μm, and was cured at 120° C. for 20 minutes.

The 60 parts specular gloss of this painted board is 95 and accelerated weathering test 1
The results after 000 hours were a gloss retention rate of 95% and a color difference of 1. Further, even when this liquid paint solution was stored at 40°C for 2 months, there was no change in viscosity or curability.

Example 3 In Example 1, instead of the m-TMIB section, m-T'M
A resin solution was obtained in the same manner using 9.8 parts of the ethyl alcohol block of I. FIG. 3 shows the infrared absorption spectrum of the resin, and it can be seen that, like the resin of Example 2, the isocyanate groups are completely blocked.

1.1,3.3-tetra-n- to 100 parts of this resin solution
Butyl-1,3-diacetoxydistanoxane 0.22
10 parts of ethyl alcohol was spray-painted on a 0.8 mm mild steel plate and cured at 140°C for 20 minutes.The coating film had a pencil hardness of 2H and exhibited good solvent resistance.

Examples 4 to 11 Resins were synthesized by changing the monomers and initiator m as listed in Table 1. I, l to 100 parts of these resin solutions
, 0.2 part of 3.3-tetra-n-butyl-1,3-diacetoxydistanoxane was added and spray-painted on a 0.8 mm mild steel plate and the white painted plate prepared in Example 1, Table 1 shows the physical properties of the coating film cured at room temperature for one week and the results of the accelerated weathering test.

(Margin below)

[Brief explanation of the drawing]

Figure 1 shows the infrared absorption spectrum of the resin obtained in Example 1, Figure 2 shows the infrared absorption spectrum of the resin obtained in Example 2, and Figure 3 shows the infrared absorption spectrum of the resin obtained in Example 3. Showing the infrared absorption spectrum.

Claims (1)

[Claims] 1. (1) A compound represented by (a) general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R represents hydrogen or a methyl group] or (b) general formula ▲ There are mathematical formulas, chemical formulas, tables, etc.▼ Compounds represented by [In the formula, R represents hydrogen or a methyl group, and B represents the residue of a blocking agent]. (2) A self-crosslinking resin composition containing a resin obtained by copolymerizing a hydroxyl group-containing ethylenically unsaturated monomer and optionally (3) an ethylenically unsaturated monomer. 2. (1) (a) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R represents hydrogen or methyl group] Compounds represented by or (b) General formula ▲ Numerical formulas, chemical formulas, tables, etc. There is a compound represented by ▼ [wherein R represents hydrogen or a methyl group, and B represents the residue of a blocking agent]. (2) A self-crosslinking resin composition containing a curing catalyst and a resin obtained by copolymerizing a hydroxyl group-containing ethylenically unsaturated monomer and optionally (3) an ethylenically unsaturated monomer. 3. (1) A compound represented by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R represents hydrogen or a methyl group, and B represents the residue of a blocking agent]. (2) A resin obtained by copolymerizing a hydroxyl group-containing ethylenically unsaturated monomer and, if necessary, (3) an ethylenically unsaturated monomer. 4. (1) General formula ▲ Numerical formula, chemical formula, table, etc. available▼ [In the formula, R represents hydrogen or a methyl group, and B represents the residue of a blocking agent]. (2) A method for producing a resin, which comprises copolymerizing a hydroxyl group-containing ethylenically unsaturated monomer and, if necessary, (3) an ethylenically unsaturated monomer.