JPH11128826A - Coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method by which a hardened film having rapid hardening property and excellent hardness and finish property is formed by using light/heat of a halogen lamp. SOLUTION: A coating resin compsn. containing an epoxy group-contg. compd. and a cationic polymn. initiator as the essential components is applied on the base body and hardened by irradiation of light and/or by heating to form a coating film. As the light source and/or heat source, a halogen lamp is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method capable of forming a cured film excellent in hardness, finish and the like by using light / heat by using a halogen lamp and utilizing light / heat.

[0002]

2. Description of the Related Art Conventionally, as a photocurable resin composition, a photoradical polymerizable resin composition curable by ultraviolet rays containing a resin containing a radically polymerizable unsaturated group and a photoradical polymerization initiator is known. Is well known, has features such as one-pack, fast-curing properties, and is widely used in the fields of paints, inks, electronic circuit protection materials, and the like. However, this requires an apparatus and a treatment for replacing with nitrogen or the like in order to remove oxygen in the air, which is a curing hindrance upon irradiation with ultraviolet rays, and furthermore, unreacted double bonds are present in the cured product after photocuring. Is not suitable for outdoor use due to insufficient weather resistance, yellowing resistance, etc. due to the large amount remaining, large volumetric shrinkage during curing and insufficient adhesion to various substrates,
And the like.

On the other hand, there is known a cationic photopolymerizable resin composition which cures an epoxy resin or the like in the presence of an aromatic sulfonium salt or the like by ultraviolet rays. It has features such as small size, no curing inhibition by oxygen, little odor, good adhesion, small skin irritation, and good storage stability, but has the disadvantage that the curing speed is slow and post cure is required.

Further, since an ultraviolet irradiation lamp is used as a light source, there is a problem that the lamp is harmful to human eyes and a harmful gas such as ozone gas is generated from the lamp. Therefore, the photocurable resin composition can be used only in a device that does not affect the human body, and cannot be used in general-purpose fields, for example, in the field of automobile repair.

In the field of automobile repair, urethane-curable coatings utilizing the reaction between hydroxyl groups and isocyanate groups have conventionally been the mainstream. Since these coatings are of a two-pack type, there is a need to use a main agent containing a polyol for each use. An operation of mixing the curing agent containing the polyisocyanate at a fixed ratio was required, and the curing time after coating usually took 30 minutes to 1 hour even in a 60 ° C. atmosphere.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a halogen lamp is used in cationic polymerization, and that light / heat is used in a special apparatus. It has been found that a clear coating excellent in hardness and finish can be formed by quick drying even if it is not dried quickly.

That is, according to the present invention, a resin composition for coating containing an epoxy group-containing compound (A) and a cationic polymerization initiator (B) as essential components is applied to a substrate surface, and irradiated with light and / or heating. The present invention provides a coating method for curing and forming a film, wherein a halogen lamp is used as a light source and / or a heat source.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy group-containing compound (A) used in the above coating resin composition may be a conventionally known low molecular weight compound containing a glycidyl group or an alicyclic epoxy group, a high molecular weight resin, or the like. Include. Examples of the low molecular weight compound containing a glycidyl group or an alicyclic epoxy group include glycidyl (meth) acrylate, allyl glycidyl ether;

[0009]

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[0010]

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And the like;

[0012]

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Adduct of polyisocyanate compound and the like;

[0014]

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And adducts with polybasic acids.
Further, as a resin containing a glycidyl group or an alicyclic epoxy group, for example, glycidyl ether type epoxy resin,
Glycidyl ester type epoxy resin, alicyclic epoxy resin, glycidyl group-containing acrylic resin, alicyclic epoxy group-containing acrylic resin, etc., may be used alone or in combination.
More than one species can be used in combination. They may also contain hydroxyl groups. Of these, an alicyclic epoxy group-containing acrylic resin is preferred.

As the alicyclic epoxy group-containing acrylic resin, those obtained by a conventionally known method can be used without any particular limitation. For example, (i) a (meth) acrylate monomer having an alicyclic epoxy group Is homopolymerized by a known polymerization method such as solution polymerization in the presence of a radical polymerization initiator, or is copolymerized with another copolymerizable monomer, (i.
i) reacting a compound having an alicyclic epoxy group and a first reactive group with an acrylic resin having a second reactive group that reacts with the first reactive group. Acrylic resin can be used.

The alicyclic epoxy group-containing acrylic resin comprises:
The number of alicyclic epoxy groups in one molecule is about 5 or more on average, preferably about 5 to 1600 on average, more preferably 10 to 200 on average, and the number average molecular weight of the resin is 2, It is desirably in the range of 000 to 100,000, preferably 3,000 to 30,000.

The epoxy group-containing compound (A) may optionally contain other cationically polymerizable components such as a vinyl ether compound, an oxolane compound, a cyclic acetal compound, a cyclic lactone compound, a spiroorthoester compound and the like. Can be used together.

Of these, vinyl ether compounds include, for example, butyl vinyl ether, cyclohexyl vinyl ether, triethylene glycol divinyl ether, cyclohexane dimethylol divinyl ether, hydroxybutyl vinyl ether, and propenyl ether. Examples thereof include propylene carbonate, and vinyl ether-terminated urethane oligomers obtained by reacting hydroxybutyl vinyl ether with isocyanate.

The cationic polymerization initiator (B) used in the coating resin composition is one that is cleaved by light / heat to generate a carbocation. As the cationic polymerization initiator, an aromatic onium salt may be used. Preferably, for example, SbF
_{^{6 -, SbF 4 -, BF}} 4 -, AsF 6 -, PF 6 - nitrogen and anionic components and the like, sulfur, phosphorus or Yo -
And onium salts such as In particular

[0021]

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[0022]

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(Where X ⁻ is SbF ₆ ⁻ , AsF ₆ ⁻ ,
Or PF ₆ ^- shows a), and the like.

The amount of the cationic polymerization initiator (B) is 0.1 to 10% by weight based on the solid content of the component (A).
The degree is appropriate.

The above resin composition for coating contains an epoxy group-containing compound (A) and a cationic polymerization initiator (B), and may further contain a hydroxyl group-containing compound (C). The hydroxyl group-containing compound (C) includes a conventionally known low molecular weight compound having a hydroxyl group, a high molecular weight resin and the like, for example, an aliphatic or aromatic polyhydric alcohol,
And an alkylene oxide adduct or ε-caprolactone adduct of the polyhydric alcohol, or a vinyl ether thereof, and a hydroxyl-containing monomer such as hydroxyethyl (meth) acrylate as a copolymerization component. Acrylic resin and hydroxyl group-containing polyester resin. Among them, ε-caprolactone adducts and polymers thereof are particularly preferable, and polycaprolactone diol, polycaprolactone triol, and the like are preferable in terms of reactivity, physical properties, and the like.

The weight solids ratio of the above components (A) and (C) is 100/0 to 60/40, preferably 100/0.
７０70/30. If the amount of the component (C) exceeds this range, the reactivity is lowered and the resulting coating tends to be soft, which is not preferred.

The resin composition for coating contains an epoxy group-containing compound (A), a cationic polymerization initiator (B), and, if necessary, a hydroxyl group-containing compound (C).
Further, it can contain a polymerizable unsaturated group-containing compound (D) and a photoradical polymerization initiator (E), and can be hybridized.

The polymerizable unsaturated group-containing compound (D) includes a low molecular weight compound having a polymerizable unsaturated group, a high molecular weight resin and the like. The low molecular compound is a monomer or an oligomer having a polymerizable unsaturated group, such as ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, or isobornyl. (Meth) acrylate, norbornyl (meth)
Acrylate, adamantyl (meth) acrylate, hydroxyethyl (meth) acrylate, trimethylolpropanetri (meth) acrylate, tetramethylol methanetetra (meth) acrylate, dipentaerythritol (meth) Acrylate, tricyclodecanedimethanoldi (meth) acrylate, 2,2-bis (4-
(3-methacryloxy-2-hydroxypropoxy)-
Phenyl) propane, di (methacryloxyethyl) trimethylhexamethylenediurethane, 2,2-bis (4-
(Meth) acrylic esters of mono- or polyhydric alcohols such as methacryloxypolyethoxyphenyl) propane; ethylene glycol dimaleate, propylene glycol diitanate, etc .; 4- (meth) acryloyloxymethoxycarbonyl phthalate Acid, 4- (meth) acryloyloxyethoxycarbonylphthalic acid, etc.
(Meth) acryloyloxyl group-containing aromatic polycarboxylic acid and its anhydride; aromatic vinyl compounds such as styrene, α-methylstyrene, chlorostyrene, vinyltoluene, t-butylstyrene, divinylbenzene; diallyl phthalate, diallyl Isophthalate, triallyl phthalate; epoxy acrylate, polyester acrylate, polydimethyl silicon di (meth) acrylate, urethane oligomer and the like.
It can be used in combination of two or more species.

The resin having a polymerizable unsaturated group is, for example, a resin having at least one, preferably three or more ethylenically unsaturated groups in one molecule, such as a polyester resin, an acrylic resin, a vinyl resin, Examples thereof include resins in which a (meth) acrylate group, an allyl group, or the like is introduced into a resin such as a polybutadiene resin, an alkyd resin, an epoxy resin, or a urethane resin, and these can be used alone or in combination of two or more. Among them, polyester (meth) acrylate resin, epoxy (meth) acrylate resin,
Urethane (meth) acrylate resins are preferred.

When the component (D) is blended, the weight ratio to the total solid content of the components (A) and (C) ｛(A)
+ (C)｝ / (D) is desirably 98/2 to 50/50, preferably 90/10 to 70/30.

As the photo-radical polymerization initiator (E), conventionally known photo-radical polymerization initiators that generate a radical by absorbing ultraviolet to visible light can be used. For example, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone , 4-t-butyl-trichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1 -One, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-
(Hydroxyphenoxy) -phenyl (2-hydroxy-
Acetophenone-based compounds such as 2-propyl) ketone, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinpropan-1-one; thioxanthone, 2-chlorothioxanthone, -Methylthioxanthone, 2,4
Thioxanthone compounds such as dimethylthioxanthone, isopropylthioxanthone and 2,4-dichlorothioxanthone; benzyl compounds such as benzyl, benzyldimethylketal, benzyl-β-methoxyethylacetal, 1-hydroxycyclohexylphenylketone; Benzophenone, o-benzoyl methyl benzoate,
Benzophenone compounds such as Michler's ketone, 4,4'-bisdiethylaminobenzophenone and 4,4'-dichlorobenzophenone; benzoin ether such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isobutyl ether Compound: camphor-quinone, anthraquinone, 3-ketocoumarin, α
-Naphthyl, diphenylphosphine oxide and the like.

The amount of the photoradical polymerization initiator (E) is suitably about 0.1 to 5% by weight based on the solid content of the component (D).

The coating resin composition may further contain fillers such as extender pigments such as silica, glass and mica and resin powders, coloring agents, ultraviolet absorbers, light stabilizers, organic solvents, sensitizers and the like, if necessary. And various additives such as a surface conditioner and the like.

In the method of the present invention, the coating resin composition obtained as described above is applied to a substrate surface and cured by light / heat, and a halogen lamp is used as the light source and / or heat source. .

As the substrate surface, for example, various material surfaces such as metal (iron, aluminum, etc.), plastic, ceramic, etc.
And an undercoating to an overcoating on the surface of the material.Especially, an overcoating surface such as an automobile outer panel is suitable, and the coating resin composition may be used as a finish coat. It can also be used as a top coat clear applied on a solvent-based or water-based overcoated basecoat film that is coated during repair.

The coating of the resin composition for coating is mainly performed by spray coating, but can also be performed by roller coating or brush coating. Usually, the coating amount is suitably 200 μm or less.

As the halogen lamp, a conventionally known halogen lamp can be used. In particular, the halogen lamp has a maximum intensity at a wavelength of 0.8 to 1.2 μm, preferably 0.8 to 1.0 μm and has a maximum intensity of 2.0 μm or more. In terms of wavelength, those having an intensity attenuated to 40% or less, preferably 35% or less of the maximum intensity, and having a spectral distribution extending to a wavelength range of 0.4 μm or less are suitable.
One example is shown in FIG.

By using the lamp, thermal cationic polymerization by light in the near-infrared region and photo-cationic polymerization by light in a very small amount in the ultraviolet region occur simultaneously, and depending on the composition of the resin composition for coating, Photoradical polymerization by light in the ultraviolet to visible region occurs, and complex curing is possible.

The irradiation distance from the light source to the painted surface is 4
A range of 0 to 90 cm, preferably 45 to 85 cm is suitable.

In the case where the base material is a material that is thermally deformable, such as plastic, the surface temperature can be adjusted by using air blowing in order to prevent a rapid rise in the heating and drying temperature during light irradiation.

[0041]

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

Example 1 After 100 parts of alicyclic epoxy resin (A-1) (Note 1) and 10 parts of polycaprolactone triol (Note 3) were mixed and stirred, a cationic polymerization initiator (C-1) ( Note 5) 5 parts were added and mixed to obtain a clear.

"Rethane PG2K metallic base"
Spray (Acrylic urethane-based metallic base paint, manufactured by Kansai Paint Co., Ltd.) so as to have a dry film thickness of 15 μm, and after touch drying, the clear is sprayed to a thickness of about 40 μm. I painted it. Immediately after painting, the halogen lamp "PAR36 110V500W M
F "(Iwasaki Electric Co., Ltd., wavelength 0.8 to
It has a maximum intensity at 1.2 μm and has a spectral distribution in which the intensity is attenuated to 35% of the maximum intensity and extends to a wavelength range of 0.4 μm or less at a wavelength of 2.0 μm or more. It was irradiated with light for 10 minutes and cured to obtain a coated plate.

Examples 2 to 7 In Example 1, compounding components such as compounds and initiators are shown in Table 1.
The same procedures as in Example 1 were carried out except for using the formulations shown in Table 1, to obtain each of the clear materials. Using these clears, the same coating as in Example 1 was performed to obtain each coated plate.

Comparative Example 1 A coated plate was obtained in the same manner as in Example 1, except that a high-pressure mercury lamp (having a spectral distribution at 200 to 400 nm) was used instead of the halogen lamp.

Comparative Example 2 "Rethane PG2K metallic base" was spray-coated on a steel sheet so as to have a dry film thickness of 15 μm, and dried by touching.
On top of that, "Rethane PG2K Clear-A" (Acrylic urethane resin paint, manufactured by Kansai Paint Co., Ltd.) was sprayed for about
Coating was performed so as to be 0 μm. This was dried in a hot air dryer at 60 ° C. to obtain a coated plate.

Each coated plate obtained above was subjected to a performance test. Table 2 shows the results. The test methods in Table 1 (Note) and Table 2 are as follows.

(Note 1) Alicyclic epoxy resin (A-1):
"UVR-6110", manufactured by Union Carbide, 3,
4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Note 2) Alicyclic epoxy resin (A-2): “EX-42
1), manufactured by Nagase Kasei Co., Ltd., sorbitol polyglycidyl ether (Note 3) Polycaprolactone triol: "Placcel 305", manufactured by Daicel Chemical Industries, Ltd., molecular weight: 550, hydroxyl value: 305 KOHmg / g (Note 4) Poly Caprolactone Diol: "Placcel 2
20 ", manufactured by Daicel Chemical Industries, Ltd., molecular weight: 2,000, hydroxyl value: 56 KOHmg / g (Note 5) Cationic polymerization initiator (C-1):" UVI-6 "
974 ", manufactured by Union Carbide, an initiator represented by the following formula:

[0049]

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(Note 6) Cationic polymerization initiator (C-2):
"UVI-6990", manufactured by Union Carbide, an initiator represented by the following formula

[0051]

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(Note 7) Radical polymerization initiator: “Irga
cure 184 ", manufactured by Ciba Geigy Co., Ltd. (* 8) Ultraviolet absorber:" Sanduvor320 "
6 ", manufactured by Clariant Co. (Note 9) Light stabilizer:" Sanduvor 3050 ", manufactured by Clariant Co., Ltd. Test method (* 1) Curability: The tackiness of the obtained coated plate surface immediately after lamp irradiation was examined with a finger (○). : Good, ×: tack on the surface). In Comparative Example 2, 10 ° C. in a heat drier at 60 ° C.
The tackiness after drying for one minute was examined.

(* 2) Hardness: Pencil hardness after standing at 20 ° C. for 24 hours after lamp irradiation on the surface of the obtained coated plate is JIS K
-5400. In Comparative Example 2, the temperature was 60 ° C.
After drying for 60 minutes in a hot air drier, pencil hardness was examined.

(* 3) Finishing property: The finishing property of the coated surface obtained in the same manner as in (* 2) was visually evaluated (A: very good, O: good, Δ: slight distortion on the coated surface) , ×: The coated surface is considerably distorted).

(* 4) Adhesion: 100 pieces of gobangs at intervals of 2 mm were formed on the coating film of the coated plate obtained in the same manner as in (* 2) using a cutter, and a cellophane tape was stuck thereon. Adhesiveness was evaluated by the number of gobangs remaining when the film was suddenly peeled off (100: 100/100, ×: ~ 99/100).

Examples 8 to 14 and Comparative Example 3 "Magicron TC-71 Clear" (manufactured by Kansai Paint Co., Ltd., aminoacrylic resin paint) was applied on a steel plate at a dry film thickness of 40%.
μm and baked at 140 ° C. for 20 minutes on a coated plate, each of which is coated with a spray to a thickness of about 40 μm, and irradiated using the same halogen lamp as in Example 1 above. Each coated plate was obtained by light irradiation at a distance of 50 cm for 10 minutes. In Comparative Example 3, irradiation was performed using the same high-pressure mercury lamp as in Comparative Example 1.

Each coated plate obtained above was subjected to the same performance test as described above. Table 3 shows the results.

[0058]

According to the present invention, by using a halogen lamp for cationic polymerization, the composition can be cured in a short time without using any special equipment, and has the same hardness and finish as when using an ultraviolet irradiation lamp. A very excellent film can be formed. Therefore, the method of the present invention is useful for topcoat coating such as automobiles and automobile repairs.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a spectral distribution diagram of an example of a halogen lamp used in the method of the present invention.

Claims (5)

[Claims] 1. An epoxy group-containing compound (A) on a substrate surface
And a coating method comprising applying a coating resin composition containing a cationic polymerization initiator (B) as an essential component and curing the composition by light irradiation and / or heating to form a coating, comprising a light source and / or a heat source. A halogen lamp is used as the coating method. 2. The coating method according to claim 1, wherein the coating resin composition further contains a hydroxyl group-containing compound (C). 3. The coating resin composition further comprises a polymerizable unsaturated group-containing compound (D) and a photo-radical polymerization initiator (E).
3. The coating method according to claim 1, further comprising: 4. A halogen lamp having a wavelength of 0.8 to 1.2.
4. The light-emitting device according to claim 1, which has a maximum intensity at .mu.m, and at a wavelength of 2.0 .mu.m or more, the intensity attenuates to 40% or less of the maximum intensity and has a spectral distribution extending to a wavelength range of 0.4 .mu.m or less. The coating method according to any one of the above. 5. The method according to claim 1, wherein the surface of the substrate is a surface of a top coat.
5. The coating method according to any one of items 4 to 4.