JPH02219881A - Paint composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coating composition capable of producing a finish exhibiting fine wrinkles.

(Prior Art and its Problems) In recent years, various improvements have been made to paint compositions and coating methods due to consumers' desire for higher quality products and diversification of tastes, and various coatings have been applied.

Particularly in the field of pre-coat coatings, there is a demand in the market for low-gloss coatings with a 2-gloss (60° gloss) of 1O or less. The method of blending, etc., mica,
Methods such as adding alumina, silica, talc, etc. to lower the gloss are being used.

However, in all of these methods, the extender pigment used to reduce gloss has a high light transmittance, so it is easy to undergo photodeterioration inside the paint film, and paint films whose gloss has been reduced by these methods cannot be used outdoors. After 1 to 2 years of exposure, the paint film becomes more discolored and tends to suffer from yoking.

In addition, in the coating films obtained by these methods, the pigment volume of the extender pigment is large (exceeding the CPVC, the 2R pigment is not sufficiently covered by the resin, and the exposed part of the pigment is large. There is also the problem that if these coatings are strongly rubbed with gauze, the color is likely to be transferred to the gauze, causing discoloration.

(Means for Solving the Problems) The present inventor conducted extensive research in order to obtain a paint that does not have such problems and satisfies the requirements for a low gloss finish.

As a result, it has been found that adding sulfonic acid and an excess of a secondary amine to a paint combination of a certain polyester resin and a melamine resin, or adding a reaction mixture of a sulfonic acid and a certain excess of a secondary amine, The present inventors have discovered that the addition of these compounds can greatly reduce gloss, provide a shriveled coating film with a 60" gloss of 10 or less, and that the resulting coating film is free from problems such as color fading, etc., and has thus arrived at the present invention.

That is, according to the present invention, A) a polyester resin having a hydroxyl value of 5 to 110, 65 to 95;
C) 1 equivalent of sulfonic acid and 1.5 to 30 equivalents of a secondary amine with a boiling point of 30 to 250°C, based on 100 parts by weight of the total of parts by weight and B) 5 to 35 parts by weight of low-nuclear methylated melamine resin. The reaction mixture of
01 to 3 parts by weight or 0.1 to 3 parts by weight of sulfonic acid and a secondary amine having a boiling point of 30 to 250°C in an amount equivalent to 1.5 to 30 equivalents to the sulfonic acid. A characterized coating composition is provided.

The polyester resins used as component (A) in the present invention include oil-modified polyester resins, oil-free polyester resins, silicone-modified polyester resins, etc., which are generally used as polyester resins for paints.
Those having a hydroxyl value of 5 to 110, preferably 20 to 90 are used.

When the hydroxyl value is 5 or less, there are few crosslinking points, so it is difficult to obtain sufficient hardness (and solvent resistance is poor. When it is 110 or more, there are too many crosslinking points, and processability tends to be poor.

In addition, the number average molecular weight of the polyester resin is 600 in the shell.
~30,000, even l, 000~20.00
It is preferably within the range of 0. These polyester resins can be used singly or in combination of two or more.

The blending amount of polyester resin is 65 to 9 as resin solid content.
5 parts by weight, preferably 70 to 92 parts by weight.

The methylated melamine resin used as component (B) in the present Yumei composition must be a low-nuclear melamine resin having methoxy groups by methylation, having no NH groups, and having an average degree of condensation of 2. .5 or less, melamine resin containing 4 or more alkyl ether groups, of which 2.5 or more methyl ether groups, per triazine ring, especially melamine resin containing 40% by weight or more of hexamethoxymethylmelamine mononuclear substance. is preferred.

In addition to the above methoxy groups, examples of alkyl ether groups that can be mixed with methoxy groups include ethoxy groups,
Examples include n-butoxy group and isobutoxy group.

Examples of commercially available methylated melamine resins include:
Cymel 300, Cymel 303, Cymel 37G, Cymel 232, Cymel 235, Cymel 238, Cymel 272, [all manufactured by Mitsui Suyanamide Co., Ltd.] 5 Nikarac MW30, Nikalac MW22A [all manufactured by Sansho Chemical Co., Ltd.], Sumimaru M100 [all manufactured by Sansei Chemical Co., Ltd.] Examples include Sumitomo Chemical Co., Ltd.], Resimin 747, Resimin 745, and Shi-Jimin 755 [all manufactured by Monsando Co., Ltd. 1].

These melamines undergo a sufficient curing reaction with polyester resins by short baking in the presence of a strong acid catalyst;
On the other hand, if a strong acid catalyst is not present, a sufficient curing reaction with the polyester resin will not occur during short baking time. When the melamine resin contains NH groups or has a large number of methylol groups, it is not preferable because a curing reaction occurs due to short baking even in the absence of a strong acid catalyst.

The above low-nuclear methylated melamine resins may be used alone or in combination.
It is possible to use a mixture of more than one species. The blending amount of the methylated melamine resin is 5 to 35 parts by weight as resin content (solid content),
Preferably it is 8 to 30 parts by weight. Polyester resin/
If the weight ratio of the melamine resin exceeds 9515, curing will not be sufficient and solvent resistance, corrosion resistance, etc. will be poor;
If it is smaller than 35, the processability of the coating film will be poor, which is not preferable.

In the present invention, the component (C) for causing shrinkage is: (1) a reaction mixture of 1 equivalent of sulfonic acid and 1.5 to 30 equivalents of secondary amine having a boiling point of 30 to 250°C, or (2)
Examples include sulfonic acid and a secondary amine having a boiling point of 30 to 250°C in an amount corresponding to 1.5 to 30 equivalents to the sulfonic acid.

The reaction mixture of (2) is the above-mentioned second reaction mixture per equivalent of sulfonic acid.
It is easily obtained by mixing 1.5 to 30 equivalents of a secondary amine at room temperature, and is a mixture of a secondary amine salt of a sulfonic acid and an excess amount of the amine. ■ is used when separately blending sulfonic acid and secondary amine into a paint containing components (A) and (B), and by blending both into the paint and stirring. , a secondary amine salt of sulfonic acid is formed, and a secondary amine salt of sulfonic acid and a secondary amine are present in the paint, similar to when the reaction mixture (1) is blended into the paint.

In the present invention, the catalytic action of sulfonic acid is temporarily suppressed by converting it into a secondary amine salt, but sulfonic acid is originally a curing catalyst for polyester resin and low-nuclear methylated melamine resin, and the sulfonic acid is used as a curing catalyst for polyester resin and low-nuclear methylated melamine resin. - During baking, secondary amines sometimes volatilize from the surface of the coating film, acting as a curing catalyst on the surface layer of the coating film, while a large amount of amine remains inside the coating film, so no curing catalytic action is obtained. For this reason, it is thought that the difference between the surface hardening and internal hardening of the coating film becomes thicker, resulting in the formation of a wrinkled pattern.

Examples of the sulfonic acid in the present invention include dodecylbenzenesulfonic acid, dinonylnaphthalenedisulfonic acid, dinonylnaphthalenesulfonic acid, paratoluenesulfonic acid, and the like, and these can be used alone or in combination of two or more.

Examples of secondary amines with a boiling point of 30 to 250°C that form salts with sulfonic acids include diethylamine, diisopropylamine, di-n-propylamine, diallylamine, cyamylamine, di-n-butylamine, diisobutylamine, di-5ec-butylamine, N-ethyl-1,2-dimethylpropylamine, N-methylhexylamine, di-n-octylamine, piperidine, 2-pipecoline,
3-pipecoline, 4-pipecoline, 2.4-, 2,6
-3.5-lupetidine, 3-piperidine methanol, etc. Among these, dialkylamines, especially diisopropylamine, di-n-propylamine, di-n-butylamine, diisobutylamine, etc., have low odor and are beautiful. This is preferable because it forms wrinkles.

When a tertiary amine 5 such as triethylamine is used as the amine, it has a strong ammonia odor and tends to have thick unevenness due to shrinkage. In this case, the film thickness in the recesses becomes extremely thin, and problems such as cracking in the recesses during processing and deterioration of corrosion resistance in the recesses are likely to occur.

In the present invention, by using a secondary amine with a boiling point of 30 to 250°C, there is no strong irritating odor (and the unevenness is smaller than when triethylamine is used).
Because smooth curvature occurs, even when forming a thin film such as pre-coated metal, cracking in the recesses and deterioration of corrosion resistance in the recesses during processing are less likely to occur.

The ratio of sulfonic acid/secondary amine is 1/1.5 in terms of equivalent ratio.
~l/30, preferably 115 to 1/15, and 1/30, preferably 115 to 1/15,
If it is larger than 1.5, the curing catalytic action of the sulfonic acid will be exerted even within the coating film and the curing will proceed before the wrinkles are sufficiently formed during baking, making it impossible to obtain a satisfactory wrinkle pattern. , l/30, problems arise such as insufficient curing of the inside of the coating film or a long time required for curing.

The amount of the combination of component (C), di-sulfonic acid and secondary amine, is 0.1 to 3 in terms of sulfonic acid per 100 parts by weight of the sum of components (A) and (B). Parts by weight, preferably 0.2 to 2 parts by weight. If the amount of sulfonic acid is less than 0.1 parts by weight, curing properties are insufficient;
It is not necessary to use more than 3 parts by weight, and even if more than this is used, coating film performance such as water resistance and moisture resistance will only deteriorate.

In the coating composition of the present invention, the above-mentioned (A), CB
) and component (C), talc, clay silica,
Known materials conventionally used in paints, such as extender pigments such as mica and alumina, fillers, coloring pigments, additives, and solvents, can also be used.

The objects to be coated with the coating composition of the present invention include metals such as cold-rolled steel plates, hot-dip galvanized steel plates, electrogalvanized steel plates, alloy-plated steel plates, aluminum plates, stainless steel plates, copper plates, copper-plated steel plates, and tin-plated steel plates. Applicable to all types, plastics, wood, cement, etc.

As a coating method, curtain coating, roll coating 5, dip coating, spray coating, etc. are possible, and the coating is usually applied so that the coating thickness after drying is within the range of 5 to 200 microns.

When painting metals, if the metal surface is not contaminated with oil contaminants, it may be painted as is, but it is known to improve the adhesion and corrosion resistance between the paint film and the metal surface. It is desirable to perform metal surface treatment.

These known surface treatment methods include phosphate-based surface treatment, chromate-based surface treatment, and coating treatment with a chromic acid-based coating agent. In addition, when it is necessary to improve the quality of the coating film, it is preferable to perform a brimer coating after the metal surface treatment and then apply the coating composition of the present invention. Applicable brimers include known brimers used in the field of colored steel plate painting, industrial machine painting, metal parts painting, etc., and the type of material to be coated,
Although it is appropriately selected depending on the type of metal surface treatment, epoxy-based, polyester-based brimers, and modified brimers thereof are particularly suitable, and when processability is particularly required, polyester-based brimers are suitable.

When the composition of the present invention is used as a clear or color clear paint, it may be applied directly to metal plates such as iron, galvanized iron plates, aluminum plates, stainless steel plates, etc. In this case, by using a glossy metal plate. A frosted pattern appearance can be obtained.

When precoating the coating composition of the present invention by coil coating or the like, there are no restrictions on the coating method, but curtain coating and roll coating are recommended from the economic efficiency of precoating steel sheets. When applying the roll coating method, the top feed or bottom feed method using three rolls is recommended in order to achieve the best uniformity of the coated surface, but for practical purposes, the bottom feed method using the usual two rolls ( So-called natural reverse painting, natural painting) may also be used.

The curing conditions for the composition of the present invention are usually the maximum temperature reached by the material 1
It is about 15 seconds to 30 minutes at 20-260°C.

In the field of pre-coat painting, which involves coil coating, etc., the maximum temperature the material reaches is usually 160 to 2.
It is carried out at 60° C. for 15 to 90 seconds.

By forming a coating film using the coating composition of the present invention as described above, a finished coating film exhibiting fine wrinkles can be obtained.

(Functions and Effects) Although the mechanism of forming wrinkles in the paint film is not clear, the secondary amine evaporates from the surface layer of the uncured paint film due to baking, and the free sulfonic acid generated in the surface layer acts as a catalyst. This is thought to be due to the fact that although the surface layer part hardens, the secondary amine remains inside the coating film, and the sulfonic acid does not exert its catalytic action and is not cured (5), resulting in the so-called top-drying phenomenon.

The wrinkles formed by the composition of the present invention are fine and smooth wrinkles, exhibit low gloss, and do not require the use of large amounts of extender pigments, resulting in a coating film with good weather resistance and colorfastness. Furthermore, even when used to form thin films such as pre-coated metal, cracking in the concave areas and deterioration of corrosion resistance in the concave areas will not occur.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, hereinafter, "parts" and "%" each refer to "parts by weight".
and "% by weight".

Polyester 1' Production Example 1 Using a normal polyester resin production equipment equipped with a heating device, a stirrer reflux device, a water separator, a rectification tower thermometer, etc., 740 parts of phthalic anhydride, 498 parts of isophthalic acid, 146 parts of adipic acid, 735 parts of neopentyl glycol, and 236 parts of 1,6-hexanediol were charged and heated.

After the raw materials were melted, stirring was started, the reaction temperature was raised to 230°C, and the temperature was maintained at 230°C for 2 hours, and the resulting condensed water was distilled out of the system through a rectification column.

Next, 90 parts of Kijirole was added to the reaction tank, and the reaction was continued at λ by switching to the solvent condensation method, and when the acid value reached 5, the reaction was terminated and cooled. After cooling, add 1414 parts of pheasant roll to include solid content! A 60% polyester resin A solution was obtained. The obtained resin had a hydroxyl value of 79 and a number average molecular weight of 1,300.

Production Example 2 In Production Example 1, the composition of the raw materials initially charged into the reaction tank was 592 parts of phthalic anhydride, 747 parts of isophthalic acid, 146 parts of adipic acid, 735 parts of neopentyl glycol, and 1.
, 6-hexanediol and 68 parts of trimethylolpropane to obtain a polyester resin B solution having a solid content of 60%. The obtained resin had a hydroxyl value of 42 and a number average molecular weight of 2,100.

Production Example 3 In Production Example 1, the composition of the raw materials initially charged into the reaction tank was 895.4 parts of phthalic anhydride, 572.32 parts of adipic acid,
The reaction was carried out in the same manner except that 525 parts of neopentyl glycol and 590 parts of 1,6-hexanediol were used, and when the acid value reached 2, it was cooled, and quijirole was added, and polyester resin C with a solid content of 60% was used. A solution was obtained.

The obtained resin had a hydroxyl value of 3.4 and a number average molecular weight of 330.
It was 0.

Example 1 A mixture of 100 parts of polyester resin A solution having a solid content of 60%, 10 parts of Kijirole, 70 parts of titanium white, and 5 parts of phthalocyanine blue was dispersed in a shaker until the welts became 10 microns. Next, 50 parts of polyester resin A solution, 1.0 part of Cymel 303, 0.3 parts of dodecylbenzenesulfonic acid, and 1.2 parts of di-n-butylamine were mixed with this at room temperature to obtain a reaction mixture. 1.
5 parts were added and stirred uniformly to obtain a paint.

Examples 2 to 8 and Comparative Examples 1 to 6 Each coating material was obtained in the same manner as in Example 1 except that the formulations shown in Table 1 were used. Incidentally, the fine silica powder and mica powder in Comparative Example 6 were not dispersed in a shaker, but were mixed into the paint by post-addition.

Each paint obtained in Examples 1 to 8 and Comparative Examples 1 to 6 was applied to an epoxy resin-based brusher (manufactured by Kansai Paint Co., Ltd.,
r K P 8410 Brimer") was painted to a dry film thickness of approximately 18 microns on the baked brimer board, and then heated at a temperature of 200°C for 4 hours.
Baking was performed for 0 seconds.

Tests were conducted on each of the obtained coated plates. The test results are shown in Table 1.

Notes in Table 1 are as follows.

* 1 * 4 Cynull 303: Manufactured by Mitsui Cyanamid Co., Ltd., low-nuclear methylated melamine resin, solidity ratio IOO%.

Resimin 755: Manufactured by Monsando, low-nuclear methylated melamine (mixed etherification of methyl ethyl and butyl ether) resin, 100% solids Super Beckamine J 820-60: Manufactured by Dainippon Ink & Chemicals, polynuclear butylated melamine resin , solid public approx. 60%.

Kneepan 20SE: Made by Nurcyanamide, polynuclear butylated melamine resin, approximately 60% solids.

DNBA-DDBSA di-n-butymyrmine/dodecylbenzenesulfonic acid = 1O/1 (mole * 6 * 7 * 8 * 9 ratio) D I PA-DDBSA di-isopuramine/dodecylbenzenesulfonic acid = IO/l (mole ratio) DNBA-DNNDSA di-n-butylamine/
Dinonylnatutale disulfonic acid = 10/1 (molar ratio) The test method in Table 1 was conducted in accordance with the following.

Painted surface appearance: The shrinkage pattern was evaluated visually.

O: A wrinkled pattern appeared on the entire surface.

■...The shriveled pattern was uneven and a disordered pattern.

×: No shrinkage pattern was produced.

Colorfastness: Wrap 4 layers of gauze around your index finger and rub the painted surface firmly (back and forth 10 times).

The color on the gauze surface and the scratches on the square Judging visually from wear.

O...The color of the paint film does not stick to the gauze.

Δ...The color of the paint film is slightly attached to the gauze.

×... Significant paint film scrapings are left on the gauze.

Processability: Bend the test plate with the painted side facing outward, and the inside of the bent part has a thickness of 0.35+! Five iron plates of +/m were sandwiched, tightened in a vise, bent iao'', and the processed portion was visually evaluated for cracks.

O...I can't recognize the crack.

■...Slight cracks were observed.

Δ: Many fine cracks are observed.

×: Many large cracks are observed.

Solvent resistance: Soak gauze in methyl ethyl ketone solvent and wrap it around your index finger until the brimer side is exposed.

Claims (1)

[Claims] 1. (A) Polyester resin 65 having a hydroxyl value of 5 to 110
(C) 1 equivalent of sulfonic acid and 1.5 parts of a secondary amine with a boiling point of 30 to 250°C per 100 parts by weight of the sum of ~95 parts by weight and (B) 5 to 35 parts by weight of the low-nuclear methylated melamine resin. ~30 equivalents of boiling point 30 of the reaction mixture with 0.1 to 3 parts by weight of sulfonic acid, or 0.1 to 3 parts of sulfonic acid and an amount equivalent to 1.5 to 30 equivalents with respect to the sulfonic acid. A coating composition comprising a secondary amine having a temperature of ~250°C.