JP2001254046A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition which can give by one coating process an excellently flexible film having a thickness of about 80-90 μm, especially can serve as a substitute for a vinyl chloride plastisol coating material that can give by one coating process a thick film, and can be burned to generate no dioxin. SOLUTION: The coating composition comprises (A) 100 parts by weight of an acryl resin having an acid value of 10-100 mg KOH/g and a hydroxyl value of 20-200 mg KOH/g, (B) 10-40 parts by weight of an epoxy phosphate resin, and (C) 20-100 parts by weight by of a mono-, di-, tri- or tetra-functional acrylate or methacrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition, and more particularly, to a coating composition having a coating thickness of about 80 to 90 .mu.m and excellent coating flexibility. A coating composition suitable for the use.

[0002]

2. Description of the Related Art Conventionally, PCM paints for industrial use include a paint for a front surface and a paint for a back surface. The surface paint is composed of an undercoat and an overcoat in the case of double coating and baking, and an intermediate coating is added in the case of triple coating.

[0003] The undercoat paint is intended to improve adhesion to a metal plate and corrosion resistance, and an epoxy resin paint or a polyester resin paint containing a rust preventive pigment is used. The thickness of the coating film is about 5 μm.

[0004] Depending on the intended use of the product, the top coat may be an oil-free polyester resin paint (including some oil-modified polyester), a thermosetting acrylic resin paint,
Silicon-modified polyester resin paint, fluororesin paint, vinyl chloride plastisol paint and the like are used.

[0005] Usually, a solvent type paint is applied to a thickness of about 10 to 25 µm, and a chloride plastisol paint is applied to a thickness of about 10 to 25 µm.
It is coated to a thickness of 0 to 250 μm.

However, when the PCM-coated steel sheet is reused after being discarded, it is often incinerated without peeling off the coating film. In this case, a steel plate coated with an oil-free polyester resin-based, thermosetting acrylic resin-based, silicon-modified polyester resin-based, or fluororesin-based paint is less likely to cause a problem, but a vinyl chloride plastisol paint is applied. For incinerated steel sheets,
The generation of harmful dioxin is a problem.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a film having a thickness of about 80 to 90 .mu.m with one coat, and has excellent flexibility of the coat. It is an object of the present invention to provide a paint composition which can substitute for a plastisol paint and does not generate dioxin during incineration.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object and found that (A) a specific acid value,
When a coating composition composed of an acrylic resin having a hydroxyl value, (B) an epoxy phosphate ester resin, and (C) a monofunctional, bifunctional, trifunctional, or tetrafunctional (meth) acrylate is used,
It has been found that a film thickness of about 80 to 90 μm can be obtained with one coat, that the film has excellent flexibility and that no dioxin is generated even when incinerated.

That is, the coating composition of the present invention comprises (B) 10 to 40 parts by weight of an epoxy phosphate ester resin (B) per 100 parts by weight of an acrylic resin having an acid value of 10 to 100 and a hydroxyl value of 20 to 200 mgKOH / g. (C) monofunctional, bifunctional, trifunctional, tetrafunctional acrylate or methacrylate in an amount of 20 to 100 parts by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The acrylic resin (A) used in the present invention comprises:
For example, methyl (meth) acrylate, ethyl (meth)
Acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth)
C1-C22 alkyl esters of (meth) acrylic acid such as acrylate and 2-ethylhexyl (meth) acrylate; methoxybutyl (meth) acrylate, methoxyethyl (meth) acrylate, methoxybutyl (meth) acrylate, ethoxybutyl (meth) acrylate , C2-C18 alkoxyalkyl esters of (meth) acrylic acid such as ethoxyethyl (meth) acrylate and ethoxybutyl (meth) acrylate; N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N -Diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate, Nt-butylaminoethyl acrylate, Nt-butylaminoethyl methacrylate,
Aminoacrylic monomers such as N-dimethylaminopropyl acrylate and N, N-dimethylaminopropyl methacrylate; acrylamide, methacrylamide, N
Acrylamide monomers such as -methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-butylacrylamide, N-butylmethacrylamide, N-dimethylacrylamide and N-dimethylmethacrylamide; Vinyl aromatic compounds such as styrene, α-methylstyrene and vinyltoluene; one or more non-functional monomers selected from vinyl monomers such as acrylonitrile, vinyl acetate and vinyl chloride; , An epoxy group, a carboxyl group, an alkoxysilane group or other polymerizable monomer having a crosslinkable functional group.

The polymerizable monomer having a hydroxyl group which can be used for the copolymerization is a compound having at least one hydroxyl group and at least one polymerizable unsaturated bond in one molecule. Examples thereof include hydroxyethyl (meth) acrylate and hydroxyethyl (meth) acrylate. C2-C20 hydroxyalkyl esters of (meth) acrylic acid such as propyl (meth) acrylate and hydroxybutyl (meth) acrylate.

The polymerizable monomer having an epoxy group is a compound having at least one epoxy group and at least one polymerizable unsaturated bond in one molecule. Examples thereof include glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate. ) Acrylate, allyl glycidyl ether, 3,4-epoxycyclohexylmethyl (meth) acrylate, 2-
(1,2-epoxy-4,7-methanoperhydroinden-5 (6) -yl) oxyethyl (meth) acrylate, 5,6-epoxy-4,7-methanoperhydroinden-2-yl- (meth ) Acrylates, 1,2-epoxy-4,7-methanoperhydroinden-5-yl-
Examples include (meth) acrylate, 2,3-epoxycyclopentenyl (meth) acrylate, and (meth) acrylate of 3,4-epoxycyclohexylmethylated polycaprolactone.

The polymerizable monomer having a carboxyl group is
Compounds having one or more carboxyl groups and one or more polymerizable unsaturated bonds in one molecule, for example, unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; maleic acid, itaconic acid, fumaric acid, mesaconic acid and the like. And unsaturated dicarboxylic acids such as half-esterification or modified products thereof.

Further, the polymerizable monomer having an alkoxysilane group is a compound having at least one alkoxysilane group and at least one polymerizable unsaturated bond in one molecule, such as vinyltrimethoxysilane and vinyltriethoxy. Silane, vinyltris (2-methoxyethoxy) silane,
γ- (meth) acryloyloxypropyltrimethoxysilane, vinyltriacetooxysilane, β- (meth)
Acryloyloxyethyltrimethoxysilane, γ-
(Meth) acryloyloxypropyltriethoxysilane, 2-styrylethyltrimethoxysilane, and the like.

The acrylic resin can have two or more crosslinkable functional groups such as a hydroxyl group, an epoxy group, a carboxyl group and an alkoxysilane group per molecule, and has an acid value of 10 to 100 mg, preferably 20 to 80 mg KO.
H / g, hydroxyl value is 20 to 200 mg, preferably 30
150 mgKOH / g.

If the acid value is less than 10 mg KOH / g, the reaction with the epoxy phosphate (B) becomes insufficient, and the strength of the coating film cannot be obtained, which is not preferred. Conversely, if the acid value exceeds 100, the hydrophilicity of the coating film increases, and the water resistance and chemical resistance decrease, which is not preferable.

When the hydroxyl value is less than 20 mgKOH / g, it is not preferable to modify the resin by using an amino resin or an isocyanate resin as a cross-linking agent because the reactivity is low and the effect is hardly obtained. Conversely, the hydroxyl value is 200 mg KO
If it exceeds H / g, the hydrophilicity of the coating film will increase and the water resistance will increase.
This is unfavorable because it adversely affects chemical resistance.

The resin has a weight average molecular weight of about 200.
Suitably, it is in the range of from about 0 to about 100,000, especially from about 5000 to 30,000.

The epoxy phosphate (B) used in the present invention is produced, for example, by the following method. An epoxy resin having an epoxy equivalent of preferably about 175 to 1000 is heated and reacted with a phosphoric acid component such as orthophosphoric acid, condensed phosphoric acid, pyrophosphoric acid or orthophosphoric acid in the presence of a catalyst such as imidazoles or phosphonium salts. Then, a monoesterified epoxy phosphate is produced by subjecting it to a triester or diester and then hydrolyzing.

Since the epoxy phosphate ester has a hydroxyl group and a phosphoric acid residue in the molecule, it promotes the curability of the coating, and exhibits an excellent crosslinking promoting effect because it reacts with the binder. It contributes to the improvement of properties and corrosion resistance.

Commercial products of such epoxy phosphates include, for example, XU-8096.07 and XU-718.
99.00, XQ-82908.00, XQ-8291
9.00, DER621-EB50 (trade names of Dow Chemical Japan Co., Ltd.), Epototo ZX1300, ZX1
300-1 (the trade name of Toto Kasei).

(B) The epoxy phosphate ester resin is
(A) It is used in an amount of 10 to 40 parts by weight based on 100 parts by weight of the acrylic resin. If the amount is less than 10 parts by weight, not only the crosslinking of the acrylic resin is insufficient, but also the contribution of the epoxy phosphate ester resin to the adhesion is insufficient, so that the original chemical resistance and workability of the coating film can be obtained. I can't. Conversely, if it exceeds 40 parts by weight, self-polymerization of the epoxy phosphate resin occurs in addition to the normal crosslinking reaction, which makes the coating film brittle and lowers the water resistance.

The monofunctional, bifunctional, trifunctional or tetrafunctional acrylate or methacrylate (C) used in the present invention includes, for example, phenol EO-modified acrylate, paracumylphenol EO-modified acrylate, nonylphenol EO-modified acrylate, nonylphenol PO Modified acrylate, 2-ethylhexyl carbitol acrylate, N-vinyl pyrrolidone, isobonyl acrylate, bisphenol F EO modified diacrylate, bisphenol A EO modified diacrylate, isocyanuric acid EO modified diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate , Pentaerythritol diacrylate monostearate, polyethylene glycol diacrylate, pentaerythritol Triacrylate, trimethylolpropane triacrylate, trimethylolpropane PO-modified triacrylate, isocyanuric acid EO
Modified triacrylate, trimethylolpropane PO modified triacrylate, trimethylolpropane EO modified triacrylate, dipentaerythritol penta and hexaacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1, 4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate,
Trimethylolpropane trimethacrylate, glycerin dimethacrylate, 2-hydroxy-2 acryloyloxypropyl methacrylate, bisphenol A EO
Modified dimethacrylate, tert-butyl methacrylate, isostearyl methacrylate, methoxyethylene glycol methacrylate, n-butoxyethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, triethylene glycol dimethacrylate,
PEG # 200 dimethacrylate, PEG # 400 dimethacrylate, PEG # 600 dimethacrylate, neopentyl glycol dimethacrylate, trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, etc. The pressure is not limited to these as long as it is higher than the ultimate temperature during baking at a pressure of 101325 Pa and a radical polymerization reaction is generated by heating.

(C) Monofunctional, bifunctional, trifunctional or tetrafunctional acrylate or methacrylate is used in an amount of 20 to 100 parts by weight based on 100 parts by weight of the acrylic resin (A). When the amount is less than 20 parts by weight, the plasticizer effect of the acrylate or methacrylate polymer is not sufficiently exerted, and the workability of the coating film is insufficient. Conversely, if it exceeds 100 parts by weight, the amount of the acrylate or methacrylate polymer in the coating film becomes too large, and the coating film strength is insufficient, and the chemical resistance and processability are undesirably reduced.

In the present invention, as a crosslinking agent,
A melamine resin, a benzoguanamine-based resin having a triazine ring and an aromatic ring, or a blocked isocyanate resin blended to improve the water resistance and hot water resistance of the resulting film can be used. In particular,
Representative examples include an alkyl etherified benzoguanamine resin and an alkyl etherified resin of diguanamine in which two triazine rings are bonded to a phenylene nucleus.

In the present invention, a benzoguanamine resin having an aromatic ring and a triazine ring is particularly preferred.

The epoxy phosphate ester used in the present invention does not cause a decrease in storage stability such as thickening of the coating composition, enables curing at a low temperature for a short time, and has an adhesive property and a corrosion resistance of the obtained film. It is effective in improving the quality.

In the present invention, an isocyanate compound can be used. The isocyanate compound is generally used as a blocked isocyanate compound in which a reactive group is blocked with a suitable blocking agent in order to enhance the stability of the obtained coating composition. The blocking agent is not particularly restricted but includes, for example, oxime blocking agents such as methyl ethyl ketoxime, acetoxime, cyclohexanone oxime, acetophenone oxime and benzophenone oxime; phenol blocking agents such as m-cresol and xylenol; methanol, ethanol Alcohol-based blocking agents such as, butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol monoethyl ether; lactam-based blocking agents such as ε-caprolactam; diketone-based blocking agents such as diethyl malonate and acetoacetate; Mercaptan blocking agents such as thiophenol; urea blocking agents such as thiourea; imidazole blocking agents; carbamic acid blocking agents and the like. It can be. Among them, lactam blocking agents, oxime blocking agents, and diketone blocking agents are preferred.

The isocyanate compound used as the blocked isocyanate is not particularly limited as long as it has at least two isocyanate groups in one molecule. For example, hexamethylene diisocyanate (HMD)
I), trimethylhexamethylene diisocyanate (T
Aliphatic diisocyanates such as MDI); alicyclic diisocyanates such as isophorone diisocyanate (IPDI); aromatic-aliphatic diisocyanates such as xylylene diisocyanate (XDI); tolylene diisocyanate (TDI), 4,4'-diphenylmethane Aromatic diisocyanates such as diisocyanate (MDI); dimer acid diisocyanate (DDI), hydrogenated TDI (HTDI), hydrogenated XDI (H6X
DI), hydrogenated diisocyanates such as hydrogenated MDI (H12MDI); dimers, trimers,
Multimeric polyisocyanates of at least tetramer; adducts of these with polyhydric alcohols such as ethylene glycol, trimethylolpropane and pentol, water or low molecular weight polyester resins. In order to further improve the reactivity, a small amount of a tin compound such as dibutyltin dilaurate may be used in combination as needed.

The above-mentioned blocked isocyanate compound is obtained by reacting the above-mentioned isocyanate compound and the above-mentioned blocking agent until free isocyanate groups disappear by a conventional method. Some of these are commercially available. For example, Desmodur series (manufactured by Sumitomo Bayer Urethane Co., Ltd.), Vernock D series (manufactured by Dainippon Ink and Chemicals, Inc.), Takenate B series (manufactured by Takeda Pharmaceutical Co., Ltd.), Coronate 2500 series (Manufactured by Nippon Polyurethane Industry Co., Ltd.) can be used.

The coating composition of the present invention comprises the above acrylic resin, epoxy phosphate ester resin, monofunctional, bifunctional,
It is composed of a functional or tetrafunctional acrylate or methacrylate, and may further contain various organic solvents, pigments, additives, and the like, if necessary.

Solvents to be added as required include aromatic hydrocarbons such as toluene and xylene, butanol,
Alcohols such as propanol, ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, esters such as butyl acetate, methoxyethyl acetate, ethoxyethyl acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone, isophorone and cyclohexanone Various organic solvents used can be used.

The above-mentioned pigments to be added as required are usually paints such as coloring pigments such as titanium oxide, carbon black, iron oxide and phthalocyanine blue, and extender pigments such as calcium carbonate, talc, barium sulfate, kaolin and clay. Various pigments used for the use can be used.

The additives to be added as required include various additives used for ordinary coatings such as a pigment dispersant, an antisettling agent, an antifoaming agent, a leveling agent, an ultraviolet absorber and an antibacterial agent. Can be used.

The coating composition of the present invention comprises the above-described constituents. The compounding amount of the organic solvent is such that the coating viscosity is 40 to 200 seconds (Ford Cup No.
4 / room temperature) is appropriate. The amount of the pigment is from 0 to 60% by weight, preferably 20% by weight, based on the solid content of the paint.
~ 50% by weight is suitable. Also, the amount of additives
0 to 5% by weight, preferably 0.1 to 2% by weight in the solid content of the coating material is suitable. The coating composition of the present invention is obtained by kneading and dispersing such constituents, and has a pigment dispersity of a grind gauge A.
It is appropriate that the thickness be 10 μm or less.

Next, a method of manufacturing the PCM will be described.
Apply various surface treatments such as chromic acid surface treatment and phosphate surface treatment as necessary,
Continuous coating of the coating composition of the present invention on various metal sheets such as galvanized steel sheets, cold-rolled steel sheets, and aluminum sheets coated with various primers such as polyester-based primers using a reverse or natural roll coater or flow coater. Depending on the means, the dry film thickness is about 60-100
μm, preferably 80-90 μm,
Maximum plate temperature (hereinafter referred to as "PMT") approx.
For a short time of 50 to 120 seconds to form a cured coating film and produce PCM. The line speed is 10
About 100 m / min is appropriate.

[0038]

The present invention will be described in more detail with reference to the following examples. In the examples, "parts" and "%" are shown on a weight basis.

Examples 1 to 8 and Comparative Examples 1 to 3
A polyester resin-based primer [“V-nit # 160 primer” (trade name, manufactured by Dainippon Paint Co., Ltd.)] is applied to an electro-galvanized steel sheet having a chromate treatment of 5 mm so as to have a dry film thickness of 5 μm. Bake hardened.

Next, the coating composition shown in Table 1 was reverse-roll coated so that the dry film thickness was 80 to 90 μm.
It was baked and dried in a hot air drying furnace for 60 seconds so as to have a PMT of 220 ° C. to produce PCM. The following evaluation tests were performed on the coated plates obtained in Examples 1 to 8 and Comparative Examples 1 to 3, and the results are shown in Table 1 and the lower part.

Each measurement item, each test method, and evaluation criteria were in accordance with the following methods.

1. Acid value 2 g of a sample was precisely weighed and dissolved in 100 ml of a mixture of ethyl ether and ethyl alcohol (1: 1), and titrated with 0.1 N potassium hydroxide (ethanol solution). Phenolphthalein was used as the indicator (JIS-K-0).
070).

2. Hydroxyl value The hydroxyl value of an acrylic resin was acetylated, and the degree of acetylation was determined by an acetic anhydride / pyridine method (JI).
SK-0070).

3. Electromagnetic thickness gauge (PERMASCOPE M10B; HEL
MUT FISCHER) (unit: μ)
m).

4. Appearance The degree of occurrence of wrinkles and cissing on the coating film surface was visually evaluated.

：: No cracks or cissing occurred. △ to Δ: Slight cracking or cissing occurred. Δ: Marking or cissing occurred.

5. Hardness The coating film surface was measured using a pencil specified in JIS-S-6006 in accordance with JIS-K-5400, and judged by the presence or absence of scratches.

6 Workability The PCM was bent at 180 ° (0T) with the surface to be evaluated at 20 ° C. outside, and cracks generated in the bent portions were observed with a 10-fold loupe, and evaluated in the state of cracks.

：: no cracks generated ○ to △: slight cracks generated Δ: cracks generated ×: remarkable cracks generated

7. The acid-resistant PCM was immersed in a 5% sulfuric acid aqueous solution, and blistering on the coated surface after 48 hours at 20 ° C. was visually determined.

：: no blisters generated ○ to △: slight blisters generated Δ: blisters generated ×: extremely blisters generated

8. Alkali Resistance PCM was immersed in a 5% NaOH aqueous solution, and the gloss of the coated surface after 48 hours at 20 ° C. was determined.

：: gloss retention 85 to 100% ○ to Δ: gloss retention 65 to 84% Δ: gloss retention 40 to 64% ×: gloss retention 39% or less

9. Stain resistance A line was drawn on the coated surface of PCM with black magic (registered trademark), left for 2 hours, and then wiped off with ethanol, and the mark of the magic was visually evaluated.

：: no traces △ to △: slight traces △: traces remaining ×: marked traces remain

[0056]

[Table 1]

Note 1) Acid value: 36.5 mg KOH / g, hydroxyl value: 80 mg KOH / g, weight average molecular weight (M
w): 23,000 Note 2) Acid value: 55 mg KOH / g, hydroxyl value: 80 mg
KOH / g, weight average molecular weight (Mw): 11,900 Note 3) Acid value: 120 mg KOH / g, hydroxyl value: 80 m
gKOH / g, weight average molecular weight (Mw): 12,200 Note 4) Acid value: 35 mgKOH / g, hydroxyl value: 220 m
gKOH / g, weight average molecular weight (Mw): 11,000 Note 5) Acid value: 8 mgKOH / g, hydroxyl value: 80 mgK
OH / g, weight average molecular weight (Mw): 13,000 Note 6) Trade name of Dow Chemical Japan; DER621-E
B50 Note 7) Trade name of Mitsui Cytec; Cymel 303 Note 8) Trade name of VESTAGON; RSi-B-15
30 (NCO% = 15%) in isophorone solution (NV = 6
0%) * 9) Tetraethylene glycol diacrylate * 10) Tripropylene glycol diacrylate * 11) Product name manufactured by Monsanto; Modaflow * 12) Product name manufactured by Shin-Etsu Chemical Co., Ltd .; KP323 * 13) Product name manufactured by Ishihara Sangyo ; CR95

As is clear from Table 1, the coating compositions of the present invention, Examples 1 to 8, had good coating performance. On the other hand, in Comparative Example 1 using an acrylic resin having an acid value of 120, the chemical resistance was inferior, and the workability was somewhat reduced. Comparative Example 2 using an acrylic resin having a hydroxyl value of 220 mgKOH / g is inferior in alkali resistance. Comparative Example 3 using an acrylic resin having an acid value of 8
Is inferior in both processability and chemical resistance because the film strength cannot be obtained. Comparative Example 4, in which no epoxy phosphate resin was used, did not cure and did not form a coating film.

[0059]

EFFECT OF THE INVENTION The coating composition of the present invention is 80
Even when coating a film having a high film thickness of up to 90 μm, there is no occurrence of wrinkles, and it has both processability and durability as a coating film, and is suitable as a paint for PCM as an alternative to vinyl chloride plastisol paint.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Mitsuhiro Matsuda 2-4-16 Hirata, Ibaraki-shi, Osaka F-term (reference) 4J038 CC021 CC022 CC071 CC072 CC081 CC082 CD021 CD022 CF021 CF022 CG031 CG032 CG061 CG062 CG071 CG071 CG141 CG CG171 CG172 CH031 CH032 CH041 CH042 CH131 CH132 CH171 CH172 CH201 CH202 CL001 CL002 DB162 DB211 DB212 DB221 DB222 FA001 FA002 FA111 FA112 FA121 FA122 FA271 FA272 GA03 GA06 GA07 GA14 KA03 KA06 MA07 MA12 MA14 NA01 NA04 NA11 NA12 NA24 NA27 PC07 PA13

Claims (1)

[Claims] (A) an acid value of 10 to 100 and a hydroxyl value of 20 to
(B) 10 to 40 parts by weight of an epoxy phosphate resin and (C) 20 to 100 parts by weight of a monofunctional, bifunctional, trifunctional, or tetrafunctional acrylate or methacrylate based on 100 parts by weight of an acrylic resin of 200 mg KOH / g. Paint composition.