JPH0310671B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a shrinking paint that can be finished with a shrinking pattern, and particularly to a shrinking paint that is preferable for use on metals. [Prior art] As a shrinking paint that forms a shrinking pattern, the resin component is an alkyd resin varnish that uses a drying oil with conjugated double bonds, such as Shinakiri oil or Oiticica oil, and a large amount of cobalt or Paints containing organic acid salts such as manganese are commonly used. Usually, this paint is sprayed or brushed to a film thickness of 50 to 60 μm, and when most of the low boiling point solvent has evaporated, it is placed in a dryer kept at 60 to 100 degrees Celsius, and after 10 to 20 minutes, a shriveled pattern appears on the entire surface. Once completed, the temperature of the dryer is raised to 100 to 150°C to cure the coating to the inside, forming a coating that has a shrinking film appearance (for example, see Paint Technology, April 1964 issue). [Problems to be solved by the invention] However, in order to obtain a beautiful wrinkle pattern and good film performance with such conventional wrinkle paints, it is necessary to
It is necessary to apply a thick coat of highly concentrated paint to the point of dripping. Therefore, there are inconveniences in the coating process, such as having to use an aromatic low-boiling point solvent for diluting the coating material, and it takes a long time to obtain a cured coating film. In addition, paints tend to burr during storage, so care must be taken when storing them. When used, filtration is required to remove the burrs that have formed, and paints that have been stored for long periods of time have the disadvantage of being difficult to wrinkle. Furthermore, since natural resin is used, the weather resistance of the coating film is poor. [Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have developed hexakisalkoxymethylmelamine (hereinafter referred to as HAMM), which has high reactivity with acrylic resins and hydroxyl groups.
By using a low-nuclear melamine resin mainly composed of melamine resin and a sulfonic acid catalyst blocked with a specific tertiary amine (hereinafter referred to as the blocked acid catalyst), a shrinking effect can be expressed and crosslinked organic fine particles can be produced. The inventors have discovered that the "shrinking pattern" can be uniformly adjusted by adding the following, leading to the present invention. The present invention provides (A) 40 to 95 parts by weight of an acrylic resin with a hydroxyl value of 40 to 200, and (B) a low-nuclear melamine containing at least 40% by weight of hexakisalkoxymethylmelamine represented by the following general formula []. 5 to 60 parts by weight of resin; (In the formula, R represents an alkyl group, of which 3 or more are methyl groups and less than 3 are alkyl groups having 2 to 4 carbon atoms.) (C) A crosslinked organic compound with a particle size of 0.01 to 10 μm. (D) A sulfonic acid compound blocked with a tertiary amine having a boiling point of 80 to 150°C is added as a sulfonic acid to 100 parts by weight of a mixture consisting of 5 to 30 parts by weight of fine particles.
It is a shrinking paint characterized by containing 5 parts by weight. The acrylic resin as component (A) used in the present invention has a hydroxyl value in the range of 40 to 200, and can be used without any particular restrictions as long as it is a general acrylic resin commonly used in paints. ~95 parts by weight,
Preferably 60 to 85 parts by weight are used. Acrylic resins with a hydroxyl value of less than 40 do not form a sufficiently cured coating film, making it difficult to form a shrinking pattern, and coating film performance such as water resistance, solvent resistance, and weather resistance also deteriorates. When the hydroxyl value exceeds 200, the water resistance of the coating film decreases. If the amount of acrylic resin used is less than 40 parts by weight,
The reaction between the acrylic resin and the low-nuclear melamine resin is insufficient, making it difficult to form a shriveled pattern due to variations in baking conditions. If the acrylic resin exceeds 95 parts by weight, the amount of the low-nuclear melamine resin will be too small to cause a sufficient crosslinking reaction, resulting in poor coating performance and failure to obtain a wrinkled pattern. The low-nuclear melamine resin of component (B) used in the present invention is used as a curing agent and is a melamine resin containing 40% by weight or more of HAMM (mononuclear substance) represented by the above general formula []. , the content of HAMM is a value analyzed by gel permeation chromatography (GPC). In the general formula [], among the alkyl groups represented by R, examples of the alkyl group having 2 to 4 carbon atoms other than the methyl group include an ethyl group, an isopropyl group, a butyl group, and an isobutyl group. Such low-nuclear melamine resins contain a large amount of alkyl groups per unit weight compared to polynuclear (high molecular weight) melamine resins commonly used in paints, and the amount of high-functional groups causes the formation of wrinkled patterns. This is a necessary requirement. On the other hand, with polynuclear melamine resin, the viscosity effect increases the viscosity of the entire coated film, so no shrinkage pattern occurs. Three or more of the alkyl groups that are functional groups in the low-nuclear melamine resin are methyl groups, and less than three have 2 carbon atoms.
When the main component is HAMM, which is an alkyl group of ~4, a shriveled pattern is produced due to the rapid crosslinking reaction between the methoxyl group and the hydroxyl group in the acrylic resin. When three or more of the alkoxyl groups have 2 to 4 carbon atoms, these functional groups have lower reactivity with the hydroxyl groups in the acrylic resin than do the methoxyl groups, so that a shriveled pattern is not formed or is insufficient. . Examples of such low-nuclear melamine resins include Cymel 300, 301, 303, and 1130 manufactured by Mitsui Toatsu Co., Ltd.
−266J, 1130−285J, Nikaratsuku MW−30M, MW−30, MX−40, MX− manufactured by Sanwa Chemical Co., Ltd.
485, MW-22, Sumimaru M- manufactured by Sumitomo Chemical Co., Ltd.
100C, M-40S, Resimin 745 manufactured by Monsanto Co., Ltd.
747, 753, 755, etc., and these can be used alone or in combination. The amount of the low-nuclear melamine resin used is 5 to 60 parts by weight, preferably 15 to 40 parts by weight as solid content.
If it is less than 5 parts by weight, a sufficiently cured coating film will not be obtained and wrinkle patterns will not easily occur. If it exceeds 60 parts by weight, the coating film will be brittle and have poor impact resistance, and it will be difficult to obtain a shriveled pattern due to variations in baking conditions. The crosslinked organic fine particles of component (C) used in the present invention are:
It plays the role of a regulator for the appearance of a uniform wrinkled pattern, and is generally called microgel.
10 μm cross-linked polymer particles. Such crosslinked organic fine particles can be added as particles alone, but a dispersion consisting of two or three components consisting of crosslinked polymer particles as a dispersed phase, an organic solvent as a dispersion medium, and a dispersion stabilizer polymer if necessary. It is preferable that the A preferred example of a dispersion of crosslinked organic fine particles is a non-aqueous polymer dispersion. This product uses a polymer soluble in organic solvents as a dispersion stabilizer, and polymerizes a vinyl monomer that becomes a polymer insoluble in organic solvents in an organic solvent. The polymer insoluble in the solvent is uniformly dispersed. For example, 2-5 of 12-hydroxystearic acid
A glycidyl group-containing vinyl monomer is reacted with the carboxyl group of a molar condensation polymer, and the resulting vinyl monomer and other vinyl monomers are polymerized in an organic solvent to obtain a dispersion stabilizer. A non-aqueous polymer dispersion can be obtained by polymerizing a vinyl monomer that becomes a polymer insoluble in an organic solvent in an organic solvent. Cross-linked organic fine particles have a dispersed particle size of 0.01~
A material having a diameter of 10 μm is used, and the solid content is 5 to 30 parts by weight. If the particle size is less than 0.01 μm, the shrinkage pattern tends to be non-uniform, and if the particle size exceeds 10 μm, the shrinkage pattern is less likely to appear. Furthermore, if the amount used is less than 5 parts by weight, the shriveled pattern tends to become uneven, and if it exceeds 30 parts by weight, the hardness of the coating film tends to decrease. The blocked acid catalyst of component (D) used in the present invention is:
One or more acid catalysts used as curing catalysts, such as methanesulfonic acid, paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalene disulfonic acid, etc., at a boiling point of 80 ~150℃
It is blocked with tertiary amine. Other acid catalysts include organic carboxylic acids such as maleic acid and phthalic acid, carboxylic acids inherent in polyols,
There are also phosphate-based catalysts, but these all have weak effects as acid catalysts, and when combined with the above-mentioned low-nucleus melamine resin, they have a weak effect of promoting the crosslinking reaction for forming a shriveled pattern. Examples of tertiary amines with a boiling point of 80 to 150°C that serve as blocking agents include N-methylmorpholine, triethylamine, N,N-dimethylallylamine,
N-methyldiallylamine, triallylamine,
N,N,N',N'-tetramethyl-1,2-diaminoethane, N,N,N',N'-tetramethyl-
Examples include 1,3-diaminopropane, N-methylpiveridine, and pyridine, and one or more of these may be used in combination. A blocked acid catalyst is produced by charging a tertiary amine and a sulfonic acid in a container and stirring the mixture at 20 to 30°C for 10 to 20 minutes. The mixing ratio of tertiary amine/sulfonic acid is 0.5~
2 moles, preferably 0.8 to 1.5 moles, and only in this case a beautiful crimp pattern is formed. If the molar ratio of tertiary amine/sulfonic acid is less than 0.5, there will be a large amount of unblocked sulfonic acid, so the curing reaction will proceed from a low temperature during baking and a sufficient wrinkle pattern will not be formed.
If it exceeds this amount, no improvement is observed due to the addition of the blocking agent, and the water resistance of the resulting coating film decreases. The amount of blocking acid catalyst used is acrylic resin,
The amount of sulfonic acid is 0.1 to 5 parts by weight, preferably 0.2 to 2 parts by weight, based on 100 parts by weight of the total solid content consisting of the low-nuclear melamine resin and crosslinked organic fine particles. If it is less than 0.1 part by weight, the catalytic effect during baking will be insufficient, so a beautiful wrinkled pattern will not be formed, and the strength of the coating film will be low. Further, it is not necessary to use more than 5 parts by weight, and even if more than this amount is used, coating film performance such as water resistance will only deteriorate. The shrinking paint of the present invention can be used as a clear paint like conventional paints, and if necessary, dyes; coloring pigments such as titanium oxide, carbon black, and various organic pigments; and extender pigments such as talc, clay, barium sulfate, and silica. Can be mixed with pigments commonly used in paints, such as anti-corrosion pigments, metal powder pigments such as aluminum pigments, and mica powder coated with titanium oxide, as well as flow regulators, surface regulators, ultraviolet absorbers, and light stabilizers. Additives such as anti-sagging agents, anti-foaming agents, etc. can also be used in the same way as in conventional paints. Further, it is preferable to use alcohols such as isopropanol and butanol as part of the solvent in order to improve the storage stability of the paint. As the painting method, conventionally used painting methods can be applied, but spray painting is particularly suitable. The selection range of thinners is wider than before, and there is no need to be particular about low boiling point solvents. There is no problem with baking in a dryer set at 120 to 160 degrees Celsius, and it is usually completed in a short time of 15 to 30 minutes. If the temperature is below 120°C, the reaction between the hydroxyl groups in the acrylic resin and the alkoxyl groups in the low-nuclear melamine resin may not be completed, making it difficult to form a wrinkled pattern and reducing coating performance such as water resistance. If the temperature exceeds 160°C, the coating film becomes brittle and yellows easily, and higher temperatures are not necessary even for the formation of wrinkled patterns. The resulting coating film has fine crepe-like unevenness in two-dimensional unspecified directions, and the size of the unevenness,
The shape etc. changes depending on the composition of the crimp pattern, coating conditions, baking conditions, etc., and by adjusting these, a coating film having an arbitrary crimp pattern can be obtained. [Operation] The mechanism of wrinkle pattern formation is not fully understood, but it is thought to be due to the so-called top-drying phenomenon in which the surface hardens rapidly when the uncured coating reaches a certain baking temperature. In the present invention, a low-nuclear melamine resin containing a large amount of methoxyl groups, which are highly reactive with the hydroxyl groups of acrylic resin, is used in the presence of a sulfonic acid catalyst blocked with a specific amine (blocked acid catalyst). Therefore, it is presumed that such rapid surface hardening causes a shrinking pattern during baking. The action of the blocking agent in this curing reaction is important; for example, when morpholine is used, a good wrinkle pattern cannot be obtained, so with N-methylmorpholine, it is due to the steric hindrance effect of the methyl group. Although it does not dissociate until the temperature reaches that temperature, it is thought that once that temperature is exceeded, a dissociation reaction between the blocking agent and the sulfonic acid catalyst occurs rapidly, accelerating the curing reaction. Furthermore, in the case of triethylamine, despite its strong basicity, its boiling point is as low as 89.7°C, so it is thought to participate in the dissociation reaction at a relatively low temperature and promote the curing reaction. Furthermore, the mechanism for adjusting the uniformity of the wrinkled pattern by adding cross-linked organic fine particles is thought to be because the surface layer becomes thicker before the curing reaction begins, and becomes the nucleus for the formation of the wrinkled pattern. [Effects of the Invention] As described above, according to the shrinking paint of the present invention, a low-nuclear melamine resin, which has not been conventionally used in shrinking paints, is used as a curing agent, and an acrylic resin, a low-nuclear melamine resin, and crosslinked organic fine particles are used as a curing agent. Contains a specific proportion of silica and blocked acid catalyst, which gives the coating film excellent physical performance and weather resistance, and the use of crosslinked organic fine particles makes it easier to obtain a uniform crimp pattern than before. Excellent storage stability due to the blocking effect of the blocked acid catalyst.
In addition, the painting process has been simplified, and there is no need to apply thick coatings using low-boiling point solvents as with conventional products, and you can simply spray paint, and bake at 120-160℃ for 15 minutes.
It can be completed in a short time of ~30 minutes and can be used as a shrinking paint for metals. [Example] Next, the present invention will be explained in more detail by giving examples and comparative examples. In each example, % and parts indicate weight % and parts by weight. <Resin production example: Acrylic varnish A ₁ > In a four-necked flask equipped with a thermometer, stirrer, condenser, and dropping funnel, charge 45 parts of xylene and 22 parts of n-butyl acetate and heat to reflux temperature (135°C). Heat. Then, from the dropping funnel, 1.3 parts of acrylic acid (AA), 11.6 parts of 2-hydroxyethyl methacrylate (HEMA), and styrene (St) were added.
30 parts, 6.1 parts of methyl methacrylate (MMA),
A mixture of 51 parts of n-butyl methacrylate (BMA) and 1 part of Perbutyl Z (polymerization initiator, manufactured by NOF Corporation, registered trademark) was added dropwise over a period of 3 hours. 1 hour after completion of dropping, add 0.2 of polymerization initiator (described above)
was added dropwise with 1 part of xylene and kept at the same temperature for 2 hours to obtain 60% solids acrylic varnish _A1 . Table 1 shows the composition and characteristic values. <Resin production example; Acrylic varnish A ₂ to _{A 4} > Based on the formulation shown in Table 1, acrylic varnish A ₁
Acrylic varnish with a solids content of 60% was produced using the same reaction vessel and reaction procedure as used for the production of
I got _A2 - _A4 . Table 1 shows the composition and characteristic values.

[Table] <Production example: Cross-linked organic fine particles C ₁ > 900 parts of 12-hydroxystearic acid was placed in a four-necked flask equipped with a thermometer, stirrer, moisture meter equipped with a condenser, and nitrogen gas inlet tube. , stir at a temperature of 200℃ while blowing nitrogen gas,
The reaction was terminated when the acid value reached 65, and after cooling
96 parts of xylene was added to obtain a 3 molar 12-hydroxystearic acid condensation polymer solution with a nonvolatile content of 90%. Note that 36 parts of water was released in this reaction. Next, add this mixture to a 54-necked flask equipped with a thermometer, stirrer, condenser, and nitrogen gas inlet tube.
1000 parts of 12-hydroxystearic acid 3 molar condensation polymer solution, 142 parts of glycidyl methacrylate,
3.2 parts of dimethylbenzylamine, 1.4 parts of hydroquinone, and 153.6 parts of xylene were charged, and a reaction between glycidyl groups and carboxyl groups was carried out at 140 to 145°C for 6 hours in a nitrogen atmosphere, resulting in a solid content of 83.5%.
A dispersion stabilizer polymer solution with an acid value of 0.2 was obtained. Next, 609.46 parts of mineral spirits were placed in a four-necked flask equipped with a thermometer, stirrer, condenser, and dropping funnel, and the temperature was raised while blowing nitrogen gas, and the mixture with the following composition was heated to 80°C for 2 hours. dripped. Dispersion stabilizer polymer solution 125.00 parts Methyl methacrylate (MMA) 285.50 parts Acrylonitrile (AN) 81.82 parts Acrylic acid (AA) 14.73 parts Glycidyl methacrylate (GMA) 29.05 parts Solid content
45%, a viscosity of 0.5 poise at 25°C, and an average particle diameter of 1.0 μm, milky white crosslinked organic fine particles _C1 were obtained. The crosslinked organic fine particles _C1 remained stable even after being left at 25°C for 6 months, with no particle sedimentation, phase separation, or change in viscosity observed. <Production example: Crosslinked organic fine particles C ₂ to C ₄ > Based on the formulation shown in Table 2, crosslinked organic fine particles
Crosslinked organic fine particles C ₂ to _{C 4} were obtained by the same reaction procedure using the same reaction vessel as that used for producing C ₁ . Table 2 shows the composition and characteristic values of the crosslinked organic fine particles C ₁ to _{C 4} .

[Table] <Production example: Cross-linked organic fine particles C ₅ > In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 553 parts of deionized water,
Dioctylsulfosuccinic acid sodium salt (Nitsunrapizole B-90, manufactured by NOF Corporation, registered trademark)
6 parts were added and stirred at about 30°C for 30 minutes to obtain a uniform surfactant aqueous solution. Next, a mixture of 83 parts of methyl methacrylate, 42 parts of n-butyl methacrylate, 14 parts of divinylbenzene, and 3 parts of Perbutyl O (manufactured by NOF Corporation, registered trademark) was gradually stirred into the above surfactant aqueous solution. The mixture was added while stirring to form a monomer dispersion. This dispersion was heated to 80℃ under a nitrogen atmosphere.
Holds time. After the reaction was completed, the mixture was cooled to room temperature to obtain a fluorescent aqueous dispersion with a solid content of 19.8% and a pH of 6.8. This water dispersion was composed of crosslinked organic fine particles and was not dissolved even in boiling acetone. The average particle size was 0.005 μm. Further, 126 parts of xylene, n
- 54 parts of butyl alcohol and 15 parts of a 20% aqueous sodium chloride solution were added to separate 200 parts of water. Add 30 parts of toluene to 295 parts of this water-removed product, and add 85 parts of
Azeotropically dehydrated at °C, solids content 21.2%, average particle size
Crosslinked organic fine particles _C5 of 0.005 μm were obtained. Example 1 Acrylic varnish A ₁ 55 parts with carbon black (carbon FW200 beads manufactured by Degussa, registered trademark)
After adding 2.2 parts of acetic acid ethylene glycol monoethyl ether/xylene = 50/50 solvent to viscosity, it was dispersed to a particle size of 10 μm or less using an attritor. Acrylic varnish A ₁ 61.7 on this dispersion base
1 part, 30 parts of Cymel 303 (manufactured by Mitsui Toatsu Co., Ltd., registered trademark) as a low-nuclear melamine resin and 22.2 parts of crosslinked organic fine particles C ₁ were added, and the molar ratio of N-methylmorpholine/paratoluenesulfonic acid was added. 1.1 blocked acid catalyst, acrylic varnish A ₁ , Cymel
Total solid content of 303 (mentioned above) and crosslinked organic fine particles
An amount equivalent to 1.0% of sulfonic acid was added to 100 parts. Then, 0.5% of a surface conditioner Modaflow (manufactured by Monsanto, registered trademark) was added to obtain a black enamel. Apply Solbetsuso 100 (manufactured by Etsuso Co., Ltd., registered trademark)/n-butanol = 90/10 thinner to this black enamel in a food cup No. 4 for 25 seconds (temperature 20
Bonderite No. 144 (Japan Parker Rising) was diluted to a viscosity of
Metal Surface Treated Steel Sheet Co., Ltd. (registered trademark) was air-sprayed and baked at 140°C for 30 minutes. The coating film thus obtained exhibited a beautiful crimp pattern and had good coating performance. Examples 2 to 9 Based on the formulations shown in Table 3, black enamels of Examples 2 to 9 were prepared in the same manner as in Example 1, and coated in the same manner as in Example 1 to give an example in which the dry coating film was 50 μm. 2
A black enamel coating of ~9 was obtained. Examples 2 and 3 are examples in which the type of acrylic varnish was mainly changed, and Examples 4 and 5 were examples in which the solid content ratio of the acrylic varnish, low-nuclear melamine resin, crosslinked organic fine particles, and amount of blocking acid catalyst were changed. This is an example. Examples 6 to 9 are examples in which the type and amount of the low-nuclear melamine resin and the blocking acid catalyst were changed. In each of Examples 2 to 9, a beautiful crimp-patterned coating film was obtained, and the coating film performance was also good. Table 4 shows the coating property values and coating film performance test results for each example. Comparative Example 1 Synthesis of Alkyd Varnish A ₅ 75 parts of glycerin, 48 parts of phthalic anhydride, and 85 parts of linseed oil fatty acid were placed in a four-necked flask equipped with a thermometer, stirrer, water metering receiver equipped with a condenser, and nitrogen gas inlet. 1 part and 85 parts of tung oil were charged, and the mixture was reacted at 240°C for 45 minutes while introducing nitrogen gas. Then 150℃
Cool to 60% solids alkyd varnish by adding 49 parts of high-flat naphtha and 49 parts of toluene.
Got _A5 . Add 2.0 parts of carbon black (carbon FW200 beads (registered trademark) manufactured by Degussa) to 100 parts of this alkyd varnish _A5 , thicken it with a solvent of n-butyl acetate/toluene = 50/50, and then use an attritor to make it viscous. The particles were dispersed to a particle size of 10 μm or less. To this dispersion base, 66.7 parts of alkyd varnish A ₅ , 0.83 parts of 6% cobalt naphthenate solution and 0.5 parts of surface conditioner Modaflow.
% to obtain black enamel. Painting was carried out in the same manner as in Example 1 to obtain a black enamel coating with a dry coating of 50 μm.
This conventional type paint had poor storage stability, somewhat poor coating performance, and showed significant chalking of the coating after one year of outdoor exposure, resulting in very poor weather resistance. Comparative Examples 2 to 8 Based on the formulations shown in Table 3, black enamels of Comparative Examples 2 to 8 were prepared in the same manner as in Example 1. 8
A black enamel coating was obtained. Comparative Example 2 is an example of a low hydroxyl value acrylic resin in which the hydroxyl value of the acrylic resin is 20, Comparative Examples 3 and 4 are examples of using a melamine resin different from the present invention, and Comparative Example 5 is an example of using an acid catalyst blocking agent. This is an example in which morpholine was used in Comparative Example 6.
is an example in which no crosslinked organic fine particles were used, Comparative Example 7 is an example in which the crosslinked organic fine particles have a particle size exceeding 10 μm, and Comparative Example 8 is an example in which the crosslinked organic fine particles have a particle size less than 0.01 μm. This is an example of a thing. Comparative Example 2 had a poor crimp pattern and poor solvent resistance, water resistance, etc., Comparative Examples 3 and 4 had a poor crimp pattern, and Comparative Example 5 also had a poor crimp pattern. Comparative Example 6 had a nonuniform crimp pattern, and Comparative Examples 7 and 8 did not produce a crimp pattern. Table 4 also shows the coating property values and coating film performance test results for each comparative example.

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Claims (1)

[Claims] 1 (A) Acrylic resin with a hydroxyl value of 40 to 200, 40 to 95
(B) 5 to 60 parts by weight of a low-nuclear melamine resin containing at least 40% by weight of hexakisalkoxymethylmelamine represented by the following general formula []; (In the formula, R represents an alkyl group, of which 3 or more are methyl groups and less than 3 are alkyl groups having 2 to 4 carbon atoms.) (C) A crosslinked organic compound with a particle size of 0.01 to 10 μm. (D) A sulfonic acid compound blocked with a tertiary amine having a boiling point of 80 to 150°C is added as a sulfonic acid to 100 parts by weight of a mixture consisting of 5 to 30 parts by weight of fine particles.
A shrinking paint characterized by containing 5 parts by weight. 2. The shrinking paint according to claim 1, wherein the crosslinked organic fine particles are made into a dispersion liquid consisting of crosslinked polymer particles, an organic solvent, and, if necessary, a dispersion stabilizer. 3. Claim 1 in which the sulfonic acid is methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, or dinonylnaphthalenesulfonic acid
Shrinking paint as described in Section 2 or Section 2. 4 Tertiary amine is N-methylmorpholine, triethylamine, N,N-dimethylallylamine, N
-methyldiallylamine, triallylamine,
N,N,N',N'-tetramethyl-1,2-diaminoethane, N,N,N',N'-tetramethyl-
The shrinking paint according to any one of claims 1 to 3, which is 1,3-diaminopropane, N-methylpiperidine, or pyridine.