JPH08176500A - Method for coating rapid-curing coating composition - Google Patents

Abstract

(57) [Summary] [Structure] An epoxy compound (a) having one or more epoxy groups in one molecule and a polymercapto compound (b) in the presence of an atomized or vaporized epoxy curing catalyst, Further, the ratio [epoxy group / thiol group] of the equivalent of the epoxy group contained in the epoxy compound (a) and the equivalent of the thiol group contained in the polymercapto compound (b) is 1.0.
/1.0-3.0/1.0 in the range of coating composition,
A method for coating a rapid-curing coating composition, which comprises coating and curing it on a substrate. [Effect] According to the above coating method, it is possible to uniformly mix the coating components and prolong the pot life of the coating composition.
Moreover, the coating composition cures rapidly and a uniform coating film can be obtained within a few minutes to a few hours.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for coating a rapid-curing coating composition.

[0002]

BACKGROUND OF THE INVENTION In recent years, it has been desired to reduce the amount of solvent discharged from paints for the purpose of environmental protection. Paints are being developed.

In general, a solvent-based multi-component paint or a solvent-free multi-component paint requires the use of a low-viscosity resin in order to secure a viscosity suitable for coating, and a low molecular weight resin is used. Such a coating composition has a slower drying speed than the conventional coating composition containing a large amount of solvent because apparent curing due to solvent volatilization cannot be expected, and the coating composition must be coated by mixing the coating composition components. The pot life is shortened.

On the other hand, from a practical point of view, the shorter the drying time of the coating film is, the better, and it is preferably from several minutes to several hours. If the drying time of the slightly solvent-type or solvent-free multi-component paint is shortened, the pot life becomes extremely short, and there is a problem that uniform mixing of the paint components and coating work become extremely difficult.

Therefore, in order to mix and coat the paint components in a short time, a spray coating device such as a two-head gun or a tip mixing type gun has been devised. However, these coating devices are more complicated than conventional airless coating devices,
In addition, since the process control of the painting work becomes complicated, it is the current situation that its practical application is hindered. Further, there is a problem that there are many design restrictions such that the viscosity, the specific gravity, the compatibility of the resins used, and the like of the multi-component paint components are approximated in order to ensure uniform mixing of the paint components.

As a coating method for solving the above problems,
A coating method in which the coating composition is spray-coated on a substrate such as an iron plate to form an uncured coating film, and then the coating film is brought into contact with a vapor amine catalyst to rapidly cure, or the presence of a vapor amine catalyst. Below, there is a coating method in which the coating composition is spray-coated on a substrate such as an iron plate and rapidly cured. In these coating methods, a coating composition is used in which the vapor amine catalyst penetrates into the coating film to cure the coating film.

For example, in Japanese Patent Publication No. 3-41113, a coating composition containing a polymercapto compound and a polyisocyanate curing agent is rapidly cured at room temperature in the presence of a vaporized tertiary amine catalyst to form a coating film. It is disclosed to obtain.

Further, Japanese Patent Laid-Open No. 3-163178 discloses a coating film curing method (coating method). This coating method is a vapor-grade tertiary composition in which a coating composition containing a polyol and a polyisocyanate curing agent is applied to a substrate such as an iron plate as a mist or as a coating applied on a substrate such as an iron plate. A method for obtaining a cured coating film by exposure to an amine catalyst is characterized in that the coating composition is cured in the presence of a thiourethane compound formed by the reaction of a mercapto compound and an isocyanate compound.

In order to solve the above-mentioned problems by a coating method other than the coating method proposed in the above publication, the inventors of the present invention have proposed one of the drawbacks of the composition of a multi-liquid coating which cures rapidly and the conventional coating method. A thorough study was made on a mixing method for a certain multi-component paint, and a paint composition containing an epoxy resin having a slow reaction rate and a paint composition containing a polymercapto compound were mixed before coating, and the mixture was sprayed during spray coating. Alternatively, by adopting a coating method in which a vapor-like epoxy curing catalyst is brought into contact, or a coating method in which a mist-like or vapor-like epoxy curing catalyst is brought into contact immediately after forming a coating film of this mixture, uniform mixing of the coating components and the coating composition are achieved. The present invention has been completed by finding that the pot life of a product can be extended and that the coating composition can be rapidly cured to form a uniform coating film.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and to achieve uniform mixing of the coating components and prolongation of the pot life of the coating composition. At the same time, it is an object of the present invention to provide a method for coating a rapid-curing coating composition that allows the coating composition to cure rapidly to form a uniform coating film.

[0011]

SUMMARY OF THE INVENTION A method for coating a rapid-curing coating composition according to the present invention comprises an epoxy compound (a) having one or more epoxy groups in one molecule in the presence of a mist-like or vapor-type epoxy curing catalyst. And the polymercapto compound (b), and the ratio [epoxy group / thiol group] of the equivalent of the epoxy group contained in the epoxy compound (a) and the equivalent of the thiol group contained in the polymercapto compound (b) is 1.0
A coating composition having a ratio of /1.0 to 3.0 / 1.0 is applied and cured on a substrate.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The method for coating the rapid-curing coating composition according to the present invention will be specifically described below.

In the method for coating a rapid curing type coating composition according to the present invention, the coating composition is applied and cured on a substrate in the presence of a mist or vapor type epoxy curing catalyst. The coating composition used in the present invention comprises an epoxy compound (a) having one or more epoxy groups in one molecule and a polymercapto compound (b).

Epoxy compound (a) used in the present invention
Is a compound having one or two or more glycidyl groups in the molecule, and specifically, methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 2-methylhexyl glycidyl ether, stearyl glycidyl ether, lauryl Glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, butyl phenyl glycidyl ether,
Monoglycidyl ethers such as nonylphenyl glycidyl ether, cresyl glycidyl ether, monoglycidyl ether of bisphenol A [p, p'-isopropylidenediphenol], monoglycidyl ether of bisphenol F; ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether Ether, triethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylol Propane diglycidyl ether,
Diene of 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, polytetramethylene glycol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A [p, p'-isopropylidenediphenol] Glycidyl ether, bisphenol A polyethylene oxide diglycidyl ether, bisphenol A polypropylene oxide diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol A polypropylene oxide diglycidyl ether, bisphenol F diglycidyl ether, dibromoneopentyl glycol diglycidyl Ether, phloroglicinol triglycidyl ether, trimethylolpropanto Liglycidyl ether, trimethylolethane triglycidyl ether, glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, aliphatic polyglycidyl ether, castor oil modified polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl Polyglycidyl ethers of polyols such as ethers; polyglycidyl esters such as dimer acid diglycidyl ester, phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, diglycidyl p-oxybenzoic acid And so on.

Further, N, N-diglycidylaniline, tetraglycidylaminodiphenylmethane, triglycidyl p-
Glycidyl amines such as aminophenol, diglycidyl toluidine, tetraglycidyl metaxylylenediamine, tetraglycidyl bisaminomethylene cyclohexane; 1,3-diglycidyl hydantoin, 1,3-diglycidyl
-5-Methyl-5-ethylhydantoin, 1,3-diglycidyl
Hydantoin-type epoxy resins such as -5-ethyl-5-amylhydantoin and glycidylglycidoxyoxyalkylhydantoins; Triazine ring-containing epoxies such as triglycidyl isocyanurate, triallyl isocyanurate and triglycidyl tris (2-hydroxyl) isocyanate Resins: Epoxy resins such as styrene oxide, glycidyl methacrylate, glycidyl phthalimide, vinyl cyclohexene monoepoxide and cyclohexene oxide can be used.

Among the above epoxy compounds, pentaerythritol polyglycidyl ether, diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl ether of bisphenol A [p, p'-isopropylidenediphenol], hydrogenated Bisphenol A diglycidyl ether, hydrogenated bisphenol A
Polypropylene oxide diglycidyl ether and bisphenol F diglycidyl ether are preferable, and bisphenol F diglycidyl ether is particularly preferable.

The above epoxy compounds may be used alone or in combination with 2.
A mixture of two or more species can be used. The polymercapto compound (b) preferably used in the present invention is an ester composed of an aliphatic polyol and a mercapto lower fatty acid, has two or more thiol groups, and the hydroxyl group remaining without esterification is a thiol group. It may be found in the range of 0.1 to 2 moles.

As the aliphatic polyol, specifically,
Examples thereof include propanediol, butanediol, alkanediol, glycerin, 1,2,6-hexanetriol, aliphatic triol, trimethylolpropane, polyethylene glycol, polypropylene glycol, pentaerythritol, sorbitol and xylitol.
Of these, pentaerythritol is preferable.

Specific examples of the mercapto lower fatty acid include mercaptoacetic acid, mercaptopropionic acid,
Mercaptosalicylic acid, mercaptoglycolic acid, N-
(2-hydroxyethyl) thioglycolic acid, mercaptosuccinic acid, mercaptomalic acid and the like can be mentioned. Among them, mercaptoacetic acid (HSCH ₂ COOH) is particularly preferable.

The polymercapto compound (b) which is particularly preferably used in the present invention is an ester having four thiol groups consisting of pentaerythritol and mercaptoacetic acid.

Specific examples of the polymercapto compound (b) other than the mercapto lower fatty acid ester of the above aliphatic polyol include 1,4-butanedithiol, 2,3-dimethylcaptopropanol and toluol-3,4-dithiol. , Α,
Examples include α'-dimethylcapto-p-xylol and the like.

In the present invention, it is desirable to use a polymercapto compound which does not require the use of a solvent and has no odor. In the present invention, the polymercapto compound (b) is equivalent to the epoxy group contained in the epoxy compound (a) having one or more epoxy groups in one molecule and the thiol group contained in the polymercapto compound (b). Ratio [epoxy group / thiol group] with equivalent is 1.0 / 1.0
~ 3.0 / 1.0, preferably 1.5 / 1.0 to 2.5
/1.0, and more preferably 1.8 / 1.0 to 2.2 /
It is used in an amount such that it becomes 1.0.

In the coating composition as described above, a coloring pigment,
Conventionally known paint additives such as rust preventive pigments, extender pigments, dispersants, iodine modifiers and solvents can be added within a range that does not impair the object of the present invention.

The coating composition used in the present invention has a temperature of 25 ° C.
Has a viscosity of 10 to 10,000 cP, preferably 1
It is 00-1,500 cP. The above viscosity is JIS-K
It is a value measured using a B-type viscometer [trade name: B8M-type viscometer manufactured by Toki Sangyo Co., Ltd.] according to 5400 (4.5.3) at a measurement temperature of 25 ° C.

The epoxy curing catalyst used in the present invention is
Any catalyst that accelerates the curing of the epoxy resin, such as low molecular weight secondary amine and tertiary amine, may be used. Specific examples of the secondary amine include piperidine, 2-methylpiperazine, morpholine and the like.

Specific examples of the tertiary amine include trimethylamine, triethylamine, tributylamine, trioctylamine, tetramethylethylenediamine, N,
N, N ', N'-tetramethylhexamethylenediamine, triethylenediamine, tetraethylenepentamine, dimethylethanolamine, diethylethanolamine, triethanolamine, dimethylaminopropanol, N-ethyldiethanolamine, triisopropanolamine,
Pyridine, picoline, N-methylpiperidine, pyrazine,
2-methylpiperazine, lutidine, 4-pyrrolidinopyridine, 1,8-diazabicyclo (5.4.0) undecene-7,
Dimethylhexylamine, dimethylcyclohexylamine, N, N-dimethylbenzylamine, 2-dimethylaminomethylphenol, 2,4-bisdimethylaminomethylphenol, 2,4,6-trisdimethylaminophenol, 2,4,6-
Examples thereof include trisdimethylaminomethylphenol, 2,4,6-trisdimethylaminomethylphenol tri-2-ethylhexyl acid salt, dimethylamino p-cresol, tetramethylguanidine, 1-methyl-2-ethylimidazole and the like.

Among these epoxy curing catalysts, dimethylethanolamine, N, N-dimethylbenzylamine,
Tetramethylethylenediamine, N, N, N ′, N′-tetramethylhexamethylenediamine, triethylenediamine, tetraethylenepentamine and 2,4,6-trisdimethylaminophenol are preferably used.

The above epoxy curing catalyst is sprayed from a spray nozzle and used in a mist or vapor state. At this time, the epoxy curing catalyst is used as it is, or is dissolved in a solvent to be used as a solution, or is heated to be used as a mist.

In the present invention, the concentration of the epoxy curing catalyst is
Depending on the activity of the catalyst, it is 0.01 to 25 with respect to the coating composition
It can be set in a wide range of% (weight ratio).
Specific examples of the substrate include metals such as iron, steel, copper, aluminum, zinc-plated steel, and zinc; plastic materials such as acrylic resin, vinyl resin, and polyester resin; and wood materials.

The coating method for the rapid-curing coating composition according to the present invention has the following aspects. (1) In the presence of a mist or vapor epoxy curing catalyst,
A coating method in which a coating composition is sprayed onto a substrate by a spray gun to cure rapidly and form a uniform coating film. (2) After spraying the coating composition onto the substrate with a spray gun to form an uncured coating film, the uncured coating film is brought into contact with a mist-like or vapor-form epoxy curing catalyst to rapidly form this coating film. A method of curing to form a uniform coating film. (3) A coating method of spraying the coating composition onto a substrate with a spray gun and simultaneously spraying an epoxy curing catalyst onto the substrate with another spray gun to form a uniform cured coating film.

In the present invention, the above-mentioned coating method (3) is particularly preferable.

[0032]

EFFECTS OF THE INVENTION According to the method for coating a rapid-curing coating composition according to the present invention, an epoxy compound having one or more epoxy groups in one molecule (in the presence of a mist or vapor epoxy curing catalyst) ( Since a coating composition containing a) and a polymercapto compound (b) in a specific ratio is applied and cured on a substrate, it is possible to uniformly mix the coating components and prolong the pot life of the coating composition. In addition, the coating composition rapidly cures and a uniform coating film can be obtained in a few minutes to a few hours.

Further, in the method for coating a rapid-curing coating composition according to the present invention, it is not necessary to heat the coating composition in order to cure the coating composition, and therefore there is a risk that it may be damaged by a large object to be baked or by heating. It can be applied to the coating of coated objects.

The present invention will be described below with reference to examples.
The present invention is not limited to these examples.
The method for measuring the curing time of the coating material and the method for measuring the peeling of the cathode, which were carried out in Examples and Comparative Examples, are as follows. (1) Method for measuring coating curing time The coating curing time was measured according to JIS K 5400 (6.5 (5) (C) curing drying). (2) Cathode Peeling Test The cathode peeling test was conducted according to ASTM G8-90 (Method B) in the following manner.

A central portion of the coating film applied to a test piece having a length of 150 mm and a width of 70 mm was cut into a circular shape having a diameter of 7 mm by using a drill to expose a steel plate substrate, and then the test pieces were each dried with anhydrous sodium chloride. Immersed in purified water containing 1% by weight of anhydrous sodium sulfate and anhydrous sodium carbonate to obtain copper-
A copper sulfate electrode is used as a reference electrode, a voltage of -1.5 V is applied, and after 700 hours, it is pulled up and the coating film in the area where the adhesiveness is reduced is peeled off toward the outside of the circle with a cutter knife.
The diameter (mm) of the peeled portion was measured. 7 mm was subtracted from the diameter of the peeled portion, and 1/2 of the value was evaluated as the peeled width. (3) Salt Spray Test According to JIS K 5400 (9.1), a salt spray test was performed for 700 hours, and then the appearance of the coating film was evaluated.

The composition of solution A containing the glycidyl ethers used in Examples and Comparative Examples is shown in Table 1, and the composition of solution B containing the polymercapto compound is shown in Table 2. In addition,
The components in Tables 1 and 2 are as follows. Diglycidyl ethers (1) YDF-170: Bisphenol F diglycidyl ether, manufactured by Tohto Kasei Co., Ltd., trade name Epototo YDF-
170 (2) EX-411: Pentaerythritol polyglycidyl ether, manufactured by Nagase Chemical Industry Co., Ltd., trade name Denacol EX-411 (3) EX-721: O-phthalic acid diglycidyl ester, manufactured by Nagase Chemical Industry Co., Ltd. , Brand name Denacol EX-7
21 (4) YD-128: Bisphenol A diglycidyl ether, manufactured by Tohto Kasei Co., Ltd., trade name Epototo YD-1
28 Polymercapto compound (1) PETP: pentaerythritol tetrakisthiopropionate, viscosity at 25 ° C. 470 cps, manufactured by Yodo Chemical Co., Ltd., trade name PETP (2) EGTG: ethylene glycol bisthioglycolate, viscosity at 25 ° C. 14 cps Yodo Chemical Co., Ltd.
EGTG epoxy curing catalyst (1) Dimethylethanolamine: Katayama Chemical Co., Ltd.
(2) DMP-30: 2,4,6-trisdimethylaminomethylphenol, manufactured by ACI Japan Limited
Product name Ancamine K.54 (3) N, N-Dimethylbenzylamine: Katayama Chemical Co., Ltd. (4) Tetramethylethylenediamine: Koei Chemical Industry Co., Ltd. (5) Tetramethylhexamethylenediamine: Koei Chemical Industry Pigment Co., Ltd. (1) Talc Fuji Talc Industry Co., Ltd., trade name Talc NKK, average particle size 6-8 microns (2) Titanium white taioxide, trade name TR-92 (3) Colloidal silica Nippon Aerosil Co., Ltd., product name Aerosil 200,
Specific surface area 200 m ² / g (BET method) (4) Cyanine blue manufactured by Toyo Ink Mfg. Co., Ltd., trade name Cyanimble PR
PL-T

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

Example 1 Blast-treated mild steel plate (150 × 70 ×
3.2 mm) of an inorganic zinc shop primer [China Paint Co., Ltd., product name: Cerabond] on the surface of a coated product (hereinafter referred to as a substrate), A liquid 1 of (a-1) shown in Table 1
A coating composition obtained by mixing 00 parts by weight and 84.5 parts by weight of the solution B of (b-1) shown in Table 2 is sprayed with an air spray winder 77 (trade name) manufactured by Iwata Coating Machine Co., Ltd. Then
At the same time, a 5% by weight solution of DMP-30 in 50% xylene was applied to the paint, and an air spray wiper 6 manufactured by Iwata Co., Ltd. was used.
Sprayed with 1 (trade name) at the same time.

The amount of paint and catalyst discharged from the spray gun was determined by mounting a polyethylene bag on the tip of the gun, capturing the paint or catalyst discharged within a specified time, and measuring the weight. The coating was performed so that the thickness of the coating film was 200 μm with a wet gauge.

Then, the coated test pieces obtained as described above were left for 3 days after coating and then baked at 120 ° C. for 1 hour, and the above-mentioned cathode peeling test was conducted to evaluate the physical properties. Further, the curing time of the paint was measured by the above method.

The results are shown in Table 3.

[0043]

Examples 2 and 3 and Comparative Example 1 Example 1 was repeated except that the coating composition of Example 1 was replaced by the coating composition having the composition shown in Table 3. A coating test piece was prepared and a cathode peeling test was conducted. Further, the curing time of the paint was measured by the above method.

The results are shown in Table 3.

[0045]

[Table 3]

The epoxy group / thiol group equivalent ratio is 2/1.
In Examples 2 and 3 using the coating composition of ~ 2.5 / 1, the coating was cured within 2 hours and showed good physical properties in the cathode peel test, but the equivalent of epoxy group / thiol group was In Comparative Example 1 using a coating composition having a ratio of 3.3 / 1,
Sufficient coating film physical properties were not obtained.

[0047]

Example 4 In Example 1, 100 parts by weight of solution A of (a-1) shown in Table 1 and B of (b-1) shown in Table 2 were used instead of the coating composition of Example 1. Example 1 except that the coating composition obtained by mixing 42.2 parts by weight of the liquid was used.
A coating test piece was prepared in the same manner as above, and a cathode peeling test and a salt spray test were conducted. Further, the curing time of the paint was measured by the above method.

The results are shown in Table 4.

[0049]

Examples 5 to 8 Coating test pieces were prepared in the same manner as in Example 4 except that the coating composition of Example 4 was used instead of the coating composition of Example 4. Prepared,
A cathode peel test and a salt spray test were conducted. Further, the curing time of the paint was measured by the above method.

The results are shown in Table 4.

[0051]

[Table 4]

[0052]

Examples 9 to 14 and Comparative Example 2 A coating test piece was prepared by coating the surface of a substrate with the coating composition having the composition shown in Table 5 and a catalyst by the same coating method as that of Example 1. It was prepared and evaluated for physical properties in the same manner as in Example 1 by a cathode peeling test and a salt spray test. Further, the curing time of the paint was measured by the above method.

However, regarding the epoxy curing catalyst, DM
Except P-30, it was used as a stock solution without diluting with a solvent. Also,
In Comparative Example 2, no epoxy curing catalyst was used. The results are shown in Table 5.

[0054]

[Table 5]

The coating compositions of Examples 9 to 13 were cured in several tens of minutes and good coating films were obtained. In Comparative Example 2 coated without using the epoxy curing catalyst, a cured coating film was not obtained.

Claims (5)

[Claims] 1. An epoxy compound comprising an epoxy compound (a) having one or more epoxy groups in one molecule and a polymercapto compound (b) in the presence of an atomized or vaporized epoxy curing catalyst. The ratio [epoxy group / thiol group] of the equivalent of the epoxy group contained in (a) and the equivalent of the thiol group contained in the polymercapto compound (b) is 1.
A coating method for a rapid-curing coating composition, which comprises coating and curing a coating composition in the range of 0 / 1.0 to 3.0 / 1.0 on a substrate. 2. The coating composition is sprayed onto a substrate with a spray gun, and at the same time, an epoxy curing catalyst is sprayed onto the substrate with another spray gun to form a cured coating film. How to paint. 3. The coating method according to claim 1, wherein the epoxy compound (a) is glycidyl ether or glycidyl ester. 4. The coating method according to claim 1, wherein the polymercapto compound (b) is an ester having four thiol groups consisting of pentaerythritol and mercaptoacetic acid. 5. The coating method according to claim 1, wherein the atomized or vaporized epoxy curing catalyst is present in a weight ratio of 0.01 to 25% with respect to the coating composition.