JPH04114774A - Coating of steel plate - Google Patents

Abstract

PURPOSE:To obtain a film which has sufficiently high storage stability and is superior in anti-chipping property and visibility by apply an electrodeposition paint and then previously providing the electrodeposited surface with a barrier coat having a specific composition and property before a second coat is applied. CONSTITUTION:As commonly used in plates of steel such as iron, a cation electrodeposition paint applied is at first. Then, an aqueous paint having a vehicle which contains a composition an olefin resin and a urethane resin as the essential component is prepared and applied on the electrodeposited surface by means of spraying or the like to form a barrier coat. Next, a second coat is formed if need be, followed by the last coat of a paint having a vehicle which comprises a hardening resin composition combining a curing agent with a resin containing a hydrolytic group directly bonded to a hydroxysilane group and/or a silicon atom and an epoxy group as the essential functional group component These help in improving the anti-chipping, anti-rust and finishing properties.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a coating method for forming a coating film with excellent chipping resistance, corrosion resistance and physical performance on a steel plate, particularly an automobile body.

(Prior Art and its Problems) In the automobile industry, emphasis is being placed on the durability of paint films, especially the problem of reduced corrosion resistance of paint films due to impact peeling and progress of corrosion of steel materials. Pebbles thrown up by the wheels of a car traveling on the road collide with the paint surface, and the impact causes the paint film to peel off locally from the car body, a so-called "chipping" phenomenon. This phenomenon often exposes the metal surface of the impact area on the outer surface of the car body, which quickly rusts and progresses to corrosion.Especially in cold regions of Europe and America, to prevent road surfaces from freezing during winter. Gravel mixed with a large amount of relatively coarsely ground rock salt is often laid on the roads, and rust and corrosion due to chipping progresses particularly quickly in cars that drive on these types of roads.

In order to prevent this chipping and the progression of corrosion caused by it, various studies have been made regarding chemical conversion treatments on the surface of the external metal base of the vehicle body, as well as electrocoating paints, intermediate coat paints, and top coat paints.

For example, in chemical conversion treatments, the use of iron phosphate coatings and zinc phosphate coatings with different crystal forms has been considered, but it is difficult to sufficiently improve the adhesion of coatings on impact areas with such chemical conversion treatments. be. In addition, various studies have been conducted on the resin and/or pigment contained in electrodeposition paints and topcoat paints, but so far no one has been found that has a sufficient adhesion-improving effect to withstand chipping. .

On the other hand, bullet I whose main ingredient is olefin resin between the electric storage coating film and the intermediate coating film! 11. There are attempts to improve chipping resistance by coating with film-forming water-based paints, but
The storage stability of the water-based paint itself was poor, the excellent chipping resistance function did not last long, and the image clarity after topcoating was also insufficient.

(Means for Solving the Problems) Therefore, in order to improve the above-mentioned problems, the present inventors
The finish is at least equivalent to that achieved by a steel plate coating system consisting of electrodeposition paint, intermediate paint, and top coat, and it also has improved storage stability, chipping resistance, and sharpness, and has excellent physical properties and corrosion resistance. The present invention has been completed as a result of extensive research aimed at providing a coating method for forming a coating film.

That is, the present invention coats a steel plate with a cationic type II paint, then coats the coated surface with an aqueous barrier coat whose main vehicle component is a composition consisting of an olefin resin and a urethane resin, and After applying the intermediate coating to t=H according to the conditions, a curing agent is added to the resin containing a hydroxysilane group and/or a hydrolyzable group directly bonded to a silicon atom and an epoxy group as essential functional groups. The present invention relates to a method of coating a steel plate, which is characterized by coating a steel plate with a top coat containing a composition as a main component.

The feature of the present invention is that in the step of sequentially applying cationic type IIT paint, intermediate coat paint, and top coat paint to a steel plate, 1i
After applying the paint and before applying the intermediate paint, a barrier coat having a specific composition and properties is applied to the electrodeposited surface in advance.

The barrier coat film of the present invention is more flexible than conventional intermediate coat films and has unique viscoelasticity based on the polyolefin resin and polyurethane resin. Therefore, even if a strong impact force from rock salt, pebbles, etc. is applied to the surface of the intermediate coat to top coat system formed through a barrier coat with such physical properties, most or all of the impact energy is It is absorbed into the barrier coating film and does not spread to the underlying electrical storage coating film,
Furthermore, both the top coat and intermediate coat are virtually free from physical damage, resulting in improved chipping resistance and
Forms a coating film with outstanding corrosion resistance and physical performance. Furthermore, water-dispersed polyolefin resin alone lacks storage stability due to the large dispersed particle size, but by blending it with an emulsion of polyurethane resin, compared to existing water-based barrier coats, It has excellent storage stability, shows no deterioration in chipping resistance even after long-term storage, and has excellent image clarity.

Furthermore, in the method of the present invention, a curing agent is blended with a resin containing a hydroxysilane group and/or a hydrolyzable group directly bonded to a silicon atom and an epoxy group as essential functional group components as a top coat. Because it uses a characteristic curable resin composition as a vehicle component, it forms a firm and strong coating film even when baked at relatively low temperatures, and also has excellent performance such as stain resistance and TL quality. , smoothness,
It also has good thick coating properties, weather resistance, water resistance, and image clarity.

In the method of the present invention, the intermediate coating may be omitted if necessary, and after coating the barrier coat, the top coating may be directly applied to the coated surface.

The coating method of the present invention will be specifically explained below.

Steel plate: A material to be coated by the method of the present invention, which is not subject to any restrictions as long as it has a metal surface that can be coated by cationic electrodeposition. For example, iron, copper,
Examples include aluminum, tin, zinc, alloys containing these metals, and plated or vapor-deposited products of these metals and alloys. Specifically, vehicle bodies such as passenger cars, trucks, safari cars, and motorcycles made of these metals and alloys are included. be. Further, it is preferable that the steel sheet is previously subjected to a chemical conversion treatment with a phosphate or chromate prior to coating with a cationic electrodeposition paint.

Cationic electrical @paint: A T-adhesive paint for coating the above-mentioned steel plate, and any known per se can be used. The cationic electrodeposition paint uses a basic water-dispersed resin 1 that is neutralized with an organic or inorganic acid, such as an epoxy, acrylic, or polybutadiene resin that has a large number of amino groups in its resin skeleton. It is a water-based paint (resin is not limited to these), and the resin is combined with a neutralizing agent, pigment (coloring pigment, extender pigment, rust preventive pigment, etc.), and the amount of pigment blended is resin solid content 1
less than 40 parts by weight per 00 parts by weight) of a hydrophilic solvent;
Water and, if necessary, a curing agent, a crosslinking agent, additives, etc. are blended to form a paint by a conventional method. Examples of neutralizing agents for neutralizing and water-soluble (dispersing) the above basic water-dispersible resin (usually used by dissolving it in a hydrophilic solvent) include acetic acid, hydroxyl acetic acid, propionic acid, butyric acid, lactic acid, glycine, etc. Organic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and other inorganic acids can be used. The appropriate amount of the neutralizing agent is in the range of 0.1 to 0.4 in terms of neutralization equivalent relative to the base number (approximately 50 to 200) of the resin. The solid content is diluted with deionized water to a concentration of about 5 to 40% by weight, the pH is maintained within the range of 5.5 to 8.0, and the steel plate is electrodeposited using a conventional method. The thickness of the coating film is not particularly limited, but the thickness of the cured coating film is approximately 10 to 40 μm.
is preferred, and the coating film is cured by heating to about 140 to 210°C.

Furthermore, a block polyisocyanate compound can be used as the curing agent.

Furthermore, an epoxy resin having an average of two or more epoxy group-containing functional groups per molecule, which is formed by bonding an epoxy group to an alicyclic skeleton and/or a bridged alicyclic skeleton, can also be used as a curing agent. The group-containing functional group consists of an alicyclic skeleton/or a bridged alicyclic skeleton and an epoxy group,
The alicyclic skeleton contains a 4- to 10-membered, preferably 5- to 6-membered saturated carbocyclic ring or a condensed ring in which two or more of these rings are condensed, and one of the carbon atoms in the poxy group is the alicyclic ring. directly bonded to a ring carbon atom in the formula skeleton or a bridged alicyclic skeleton [for example, see formulas (a) and (b) below], or two carbon atoms of the epoxy group and the alicyclic ring It is important that two adjacent carbon atoms constituting the ring in the formula skeleton or the bridged alicyclic skeleton are common [see, for example, formulas (c) and (d) below].

Specific examples of such epoxy group-containing functional groups include those represented by the following formulas (a) to (d).

In the formula, R+, R2, Rs, Rs, Rs, R1, R+o and R, r each represent H, CH, or CgHs, and R4, Rs, and R9 each represent H or CH,
represents.

The above-mentioned epoxy resin curing agent is described in detail in British Published Patent No. 356,970 by the present applicant, and is also applicable to the present invention.

Barrier Coat The barrier coat used in the present invention is a water-based paint whose main vehicle component is a composition consisting of an olefin resin and a urethane resin.

The olefin resin used in the barrier coat of the present invention is a polymer containing an olefin monomer and/or a diene monomer as an essential monomer component.

Specifically, propylene-ethylene copolymer, chlorinated polypropylene, EPDM (ethylene-propylene-diene copolymer), polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. Examples include acid group-containing polymers obtained by polymerizing acid group-containing polymerizable unsaturated monomers such as maleic acid, maleic anhydride, acrylic acid, and meccrylic acid.

Among them, the acid group-containing polymer obtained by polymerizing chlorinated polypropylene and (anhydrous) maleic acid has a particularly superior chlorinated polypropylene (preferably chlorination rate of 20 to 30% by weight) component compared to propylene base materials. It shows adhesion and (
It is desirable to use this (anhydrous) maleic acid component because it exhibits excellent adhesion to the topcoat film and has excellent water resistance, etc., resulting in less adhesion deterioration. When a maleic acid component (anhydrous) is used, it is usually about 0.5% based on the acid group-containing polymer.
It can be used in a range of ~10% by weight, preferably about 1-5% by weight.

The olefin resin has a number average molecular weight of about 3000 to
50,000, preferably in the range of about 10,000 to 30,000. If the molecular weight is less than about 3,000, the paint film tends to stick, allowing foreign matter such as dust and dirt to adhere to it, resulting in poor appearance of the final topcoat film and poor adhesion after a water resistance test. On the other hand, if the molecular weight is greater than about 50,000, a coating film with excellent smoothness cannot be obtained.

This is not desirable because it has the following drawbacks.

The urethane resin, which is a vehicle component used in combination with the olefin resin, is obtained by reacting (1) a component containing an average of two or more active hydrogens per molecule and (2) a polyisocyanate component. It is a urethane polymer, or a urethane polymer obtained by reacting a prepolymer obtained by reacting component (i) and component (2) with a chain extender component. Further, these urethane resins may contain acid groups.

Component (1) can be used without any limitation as long as it contains an average of two or more active hydrogens (preferably hydroxyl groups) in one molecule. Specifically, the following can be mentioned.

(i) Diols: eg ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1.
4-butylene glycol, 15-pentadiol, neopentyl glycol, 1,6-hexane glycol, 2
．． 5-hexanediol, dipropylene glycol, 2
．． 4-trimethyl-1,3-penkdiol, tricyclodecane dimetatool, 1,4-cyclohexane dimetatool, etc.

(11) Polyether diol: For example, one obtained by ring-opening polymerization or ring-opening copolymerization (block or random) of an alkylene oxide adduct, alkylene oxide, cyclic ether (tetrahydrofuran, etc.) of the diol (1), e.g. Polyethylene glycol, polypropylene glycol, polyethylene-propylene (
block or random) glycols, dioxytetramethylene glycol, dioxyhexamethylene glycol, dioxyoctamethylene glycol, etc.

(i) Polyester diols (anhydrous) dicarboxylic acids (e.g. adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, fucuric acid, etc.) and glycols [e.g. ethylene glycol, propylene glycol,
1,4-butanediol, 1,6-hexanediol,
1.8-year-old cutamethylene dichloromethane, neopentyl glycol, bishydroxymethylcyclohexane, bishydroxyethylbenzene, alkyl dialkanolamine, m-xylylene glycol, 1.4-bis(2-hydroxyethoxy)benzene, 4゜4 '-bis(2-hydroxyethoxy)-diphenylpropane, etc.], such as polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyethylene/propylene adipate, bishydroxymethylcyclohexane and 04 - Polyester diols consisting of C8 linear dicarboxylic acid mixtures (e.g. KING Industries Inc.
Co, , ni-FLEX-148, same as left 188), polylactone diol (for example, polycaprolactone diol and mixtures of two or more thereof), and the like.

(IV) Polyether ester diol: ether group-containing diol (the above polyether diol, diethylene glycol, triethylene glycol, dipropylene glycol, etc.) or a mixture of these and other glycols with the above dicarboxylic acid or (anhydrous) dicarboxylic acid compound (fucric anhydride, maleic anhydride, etc.) and those obtained by reacting with alkylene oxides, such as poly(polyoxytetramethylene) adipate.

(V) Polycarbonate diol general formula % formula % (1) (wherein, R is a residue of a C1-1t saturated aliphatic diol,
X indicates the number of repeating units in the molecule, and is usually an integer of 5 to 50). The compound contains a saturated aliphatic diol (1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, polyethylene glycol such as diethylene glycol, polypropylene glycol, (oxyethylene oxypropylene copolymer diol, etc.) and substituted carbonates (diethyl carbonate, diphenyl carbonate, etc.)
It can be obtained by a transesterification method in which the saturated aliphatic diol is reacted with phosgene, a method in which the saturated aliphatic diol is reacted with phosgene, or a method in which a saturated aliphatic diol is further reacted if necessary.

The diols described in (i) to (V) above can be used alone or in combination of two or more.

Also preferred among the diols described in (i) to (V) above are those described in (i) to (j) 2, more preferably those having a number average molecular weight of about 5000 or less, preferably about 1000.
-3000.

In addition to the diol, (vi) a low molecular weight polyol containing three or more hydroxyl groups in one molecule (preferably a number average molecular weight of 500 or less) can be blended. When the low molecular weight polyol (vl) is used, for example, the urethane By imparting branching properties to the resin molecular skeleton and forming a three-dimensional structure in the urethane resin, the water dispersion stability of polyurethane particles can be improved, and the water resistance and chemical resistance of the formed coating film can be improved. There is an advantage to doing so.

Examples of the (vl) low molecular weight polyol include trimethylolpropane, trimethylolethane, glycerin, tris-2-hydroxyethyl isocyanurate,
Pentaerythritol etc. can be used. The (vl) low molecular weight polyol is about 0 per mole of the diol component.
．． It can be blended in a range of 1 mole or less. If the amount is more than about 0.1 mole, it is not preferable because the storage stability of the aqueous compound may deteriorate or the physical properties of the coating film may deteriorate.

As the polyisocyanate component (2) to be reacted with the component (1), a compound containing an average of two or more isocyanate groups in one molecule can be used. Specifically, as an aliphatic diisocyanate compound, an aliphatic diisocyanate having 1 to 12 carbon atoms, such as hexamethylene diisocyanate, 2.2.4-1-limethylhexane diisocyanate, lysine diisocyanate, etc.: As an alicyclic diisocyanate compound, carbon Alicyclic diisocyanates of numbers 4 to 18, such as 1,4-cyclohexane diisocyanate, 1-incyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate), 4,4'-dicyclohexylmethane diisocyanate, Methylcyclohexylene diisocyanate, isopropylidene dicyclohexyl-4
, 4'-diisocyanate, etc.: As the aromatic incyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate.

Examples include xylylene diisocyanate and meta-xylylene diisocyanate, and further examples include modified products of these diisocyanates (carposiimide, uretdione, uretoimine-containing modified products, etc.), and mixtures of two or more of these diisocyanates.

Any conventional method can be used to introduce acid groups into the urethane resin, but for example, replacing dimethylolalkanoic acid with part or all of the glycol components described in (11) to (1v) above. By introducing a carboxy group into polyether diol, polyester diol, polyether ester shiol, etc. in advance (or by using a mixture of the diol component of (1) or (V) and dimethylolalkanoic acid). A method of introducing an acid group is preferred. Examples of such dimethylolalkanoic acid include dimethylol acetic acid,
Mention may be made of dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolvaleric acid.

Urethane resins with acid groups introduced can be dispersed in water without the use of surfactants or with a reduced amount of surfactants, which has the advantage of improving the water resistance of the coating film. be. The content of acid groups is about 25 to 150, preferably about 30 to 100, as the acid value of the urethane resin.
More preferably, the range is about 50 to 80. If the acid value is less than about 25, the water dispersibility will be poor, while if the acid value is more than about 150, the water resistance of the coating film may be poor, which is not preferred.

Urethane resin usually has a number average molecular weight of 10,000 to
100,000, preferably about 20,000 to 50,000,
More preferably, one having a molecular weight of 25,000 to 35,000 can be used. The reaction between component (1) and component (2) results in a urethane prepolymer (usually a number average molecular weight of 10
00 to 3000), the molecular weight may be adjusted to the above range by chain elongation.If the number average molecular weight of the urethane resin is less than about ioooo, water resistance, flexibility, etc. may deteriorate. On the other hand, if it is larger than 100,000, it is undesirable because it causes sedimentation, agglomeration, etc. during paint storage, causing defects such as pigs on the paint film, and reducing the smoothness of the paint film. .

The chain extension method for the urethane prepolymer can be carried out according to a known method. For example, water, water-soluble polyamines, glycols, etc. are used as the chain extender component, and the urethane prepolymer and the chain extender component are reacted. If necessary, a reaction catalyst can also be used. The water-soluble polyamine has a primary amine group and/or a secondary amino group.
Polyamine compounds having two or more polyamines in the molecule can be used, such as water-soluble polyamines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, xylylenediamine, diethylenetriamine, and triethylenetetramine.

Water-soluble alicyclic polyamines such as piperazine and mixtures thereof can be suitably used.

As glycols, for example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, butadiol, hexanediol, trimethylolpropane, etc. can be suitably used.

As reaction catalysts, trialkylamines such as trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine, N-alkylmorpholine such as N-methylmorpholine, N-ethylmorpholine; N-dialkylalkanolamine, For example, N-dimethylethanolamine, N-
Examples include diethylethanolamine; N-alkylvinylpyrrolidone and mixtures of two or more thereof.

The method for making the olefin resin and urethane resin water-based may be any conventionally known method, but for example, ■ Mixing the urethane resin (substantially containing no isocyanate groups) and the olefin resin. After that, a surfactant and/or neutralizing agent is added and dispersed in water.

■ After mixing the urethane resin raw materials (1) and (2) with the olefin resin, the (1) and (2)
) A method in which the components are reacted (so that they are substantially free of incyanate groups), and then a surfactant and/or a neutralizing agent is added and dispersed in water.

■ A surfactant and/or neutralizing agent is added to an olefin resin and dispersed in water, and a surfactant and/or neutralizing agent is added to a urethane resin (substantially not containing incyanate groups). A method in which the agent is added and dispersed in water.

■ NCO group-containing urethane prepolymer (usually NGO
/○H equivalent ratio in the range of 1.1 to 1.9) is mixed with an olefin resin, dispersed in water, and simultaneously subjected to a chain extension reaction. In this method, a chain extender other than wood may be added at the same time, and if necessary, a catalyst for chain extension reaction.

Surfactants, neutralizing agents, etc. may also be added.

■ After mixing the (1) component and (2) component of the urethane resin raw material with the olefin resin, the (1) component and (2)
After reacting the components to obtain a mixture of NCO group-containing urethane prepolymer (NGOloH equivalent ratio of about 1.1-1.9) and olefin resin, water dispersion and chain elongation reaction were carried out in the same manner as in ① above. (2) A method in which an NCO group-containing urethane prepolymer is subjected to a chain extension reaction in the same manner as in (2) above, and at the same time it is dispersed in water, and a water-dispersed olefin resin described in (1) above is mixed. A method such as that described above can be suitably applied.

The neutralizing agent is used when acid groups are present in the urethane resin, olefin resin, urethane prepolymer, etc., and the same neutralizing agent as the above-mentioned chain extension reaction catalyst can be used. Among these, preferred are trialkylamines,
N-alkylvinylpyrrolidone is particularly preferred, and triethylamine is particularly preferred. The amount of neutralization is about 0.5 to 2.0 equivalents, preferably 1 equivalent per equivalent of carboxyl group.
The amount may be approximately 1.5 equivalents.

Examples of surfactants include higher alcohols, alkylphenols, arylphenols, nonionic surfactants such as ethylene oxide adducts such as polyoxypropylene glycol, alkylphenols, sulfate salts of ethylene oxide adducts such as higher alcohols, and alkylbenzene sulfones. Anionic surfactants such as acid salts, and mixtures thereof are preferred, and the blending ratio of the surfactant is preferably about 10 parts by weight or less based on 100 parts by weight of resin solid content from the viewpoint of coating film water resistance. is preferably within a range of about 5 parts by weight or less.

Among the above, using those obtained by chain extension reaction can help water dispersion of polyolefin resin, stabilize the resin particles, and have water resistance and
It has the advantage of producing a coating film with excellent performance such as appearance. The polyurethane polymer obtained by carrying out the chain extension reaction is preferably one containing acid groups.

The blending ratio of the olefin resin and urethane resin, which are the vehicle components of the barrier coat, is about 5 to 40% by weight, preferably about 10 to 30% by weight of the former in terms of solid content of both resins.
, the latter in a range of about 95 to 60% by weight, preferably about 90 to 70% by weight. If the polyolefin resin is less than about 5% by weight or the urethane resin is more than about 95% by weight, adhesion etc. will decrease, while if the olefin resin is more than about 40% by weight or the urethane resin is about 60% by weight. If the amount is less than % by weight, the adhesion to the top coat, water resistance, storage stability of the paint, etc. will deteriorate, which is not preferable.

In the composition obtained by making it water-based by the above-mentioned methods ① to ②, the urethane resin component is used as a component to assist in the water dispersion of the olefin resin and to stabilize the olefin resin particles. Further, an aqueous dispersion of a urethane resin can be mixed with the aqueous olefin resin as a component having a function of improving coating performance.

As the aqueous dispersion of urethane resin used to improve coating film performance, the same aqueous dispersion of urethane resin as described in the above-mentioned aqueous conversion method can be used.

The urethane resin (hereinafter referred to as urethane resin A) contained in the aqueous mixture of the urethane resin and olefin resin obtained in steps (1) to (3) above, and the urethane resin added to this aqueous mixture to improve coating film performance. A preferred combination of the urethane resin (hereinafter referred to as urethane resin B) in the water dispersion of is a monomer having good compatibility with the olefin resin, such as an aliphatic or alicyclic polyol as the component (1). , a urethane resin obtained by using an aliphatic or alicyclic diisocyanate compound as the component (2) is used as the urethane resin A, and a urethane that uses a large amount of monomers with excellent physical properties, such as aromatic diisocyanates as the component (2). system resin with a number average molecular weight of 20,000 or more, preferably 30,000 to 100
A combination of using a urethane resin of No. 000 as the urethane resin B is mentioned. In addition, the blending ratio of these is such that the ratio of olefin resin/urethane resin A/urethane resin B is approximately 5% based on the solid content of these resins.
~40% by weight/15-60% by weight 10-5oii amount%,
Preferably about 10-30% by weight/20-50% by weight/2
The aqueous compound used for the barrier coat should be about 0.001 to 5% by weight from the viewpoint of storage stability, compatibility, coated surface smoothness, etc.
Preferably, it has an average particle size of about 0.05 to 2.0F.

Furthermore, coloring pigments, extender pigments, coating surface conditioners, anti-wrinkle agents, fluidity control agents, anti-cissing agents, plasticizers and the like can be added to the barrier coat as required.

Barrier coat 1 usually has a solid content of about 20 to 50% by weight and a viscosity of about 500 to 3,000 centivoise (B-type viscometer, adjusted to a rotational speed of 6 RPl) before use.

The means for coating on the W@* film is not particularly limited, but specifically, it can be applied by means such as spray coating, spacing coating, dipping coating, and electrostatic coating.

In addition, the coating film thickness is usually about 5 to 50% based on the dry film thickness.
pn, preferably in the range of 10 to 20 tm.

This coating film is formed at room temperature to 160℃, preferably about 80℃ to 160℃.
It can be dried at a temperature of 120°C.

Intermediate paint: A paint to be applied to the barrier coated surface, and any known intermediate paint with excellent adhesion, smoothness, sharpness, overbake resistance, weather resistance, etc. can be used. Specifically, an organic solution-type thermosetting intermediate coating material whose vehicle main components are a short oil having an oil length of 30% or less, an ultra-short oil alkyd resin, or an oil-free polyester resin and an amine resin can be mentioned. These alkyd resins and polyester resins have a hydroxyl value of 60 to 140 and an acid value of 5.
~20, and preferably uses unsaturated oil [or unsaturated fatty acid] as the modified oil, and suitable amino resins include alkyl (1 to 5 carbon atoms) etherified melamine resin, urea resin, benzoguanamine resin, etc. . The blending ratio of these is 65-85% alkyd resin and/or oil-free polyester resin based on solid content weight.
, especially 70-80%, amino resin 35-15%1. In particular, it is preferably 30 to 20%.Furthermore, the amino resin can be replaced with a polyisocyanate compound or a blocked polyisocyanate compound.6Also, the form of the intermediate coating is most preferably an organic solution type. , a non-aqueous dispersion, a high solid type, an aqueous droplet type, an aqueous dispersion type, etc. using the above vehicle components are also acceptable. In the present invention, the hardness (pencil hardness) of the intermediate coating film is 3B to 2H.
(20°C, by the Surikisu method) is preferably in the range. Furthermore, extender pigments, coloring pigments, other paint additives, and the like can be added to the intermediate paint as necessary.

In the present invention, the intermediate coating paint can be applied to the barrier coat surface in the same manner as the barrier coating. The curing temperature of the film varies depending on the vehicle components, and when curing by heating, it is 80 to 170°C, and 12 to 12°C.
It is preferable to heat at a temperature of 0 to 150°C.

Although an intermediate coating is not essential in the method of the present invention, it is preferable to use it in order to further improve coating performance.

Top coat paint: A paint that is applied to the above intermediate coated surface or barrier coated surface. Specifically, the top coating is a curable resin made by blending a curing agent with a resin containing a hydroxysilane group and/or a hydrolyzable group directly bonded to a silicon atom and an epoxy group as essential functional group components. It is characterized in that the composition is a vehicle component.

The resin and curing agent used in the curable resin composition are the same as the base resin and curing agent that are crosslinked curable paint components described in Japanese Patent Application No. 01-204454 filed by the present applicant. be able to.

The base resin used in the crosslinked curable paint is a resin having a hydroxyl group directly bonded to a silicon atom and/or a hydrolyzable group and an epoxy group in the same resin molecule, or a hydroxyl group directly bonded to a silicon atom and/or a hydrolyzable group. Resin with degradable group■-
Mixed resin (2) is a mixture of (1) and (1)-2 having an epoxy group.

Further, examples of the base resin include those described in (1) to (8) below.

(1) A resin (A) having a functional group is converted into a compound (B) having a functional group and an epoxy group that reacts complementary to the functional group.
and a reactant (D) obtained by reacting with a compound (C) having a functional group that reacts complementary to the functional group of the resin (A) and a silane group (hereinafter referred to as "(1) resin composition") ) (2) A reactant (F) obtained by reacting a resin (E) having a functional group with a compound (B) having a functional group and an epoxy group that reacts complementary to the functional group, and a resin having a functional group. Mixture (1) (hereinafter referred to as "(2) Resin composition (3) Epoxy group-containing polymerizable unsaturated monomer (J), silane group-containing polymerizable unsaturated monomer (K), and other polymerizable unsaturated monomers ( Copolymer (L) containing M) as a monomer component (hereinafter referred to as "(3) resin composition") (4) Homopolymer (N) of the monomer (J) or the monomer Copolymer (N) of (J) and other polymerizable unsaturated monomer (M), and homopolymer (P) of the monomer (K)
Or the monomer (K) and other polymerizable unsaturated monomers (
(5) Polymerizable unsaturated monomer (Q) having a functional group and the epoxy group-containing polymerizable A copolymer (R) containing an unsaturated monomer (J) as an essential component, and a compound (S) having a functional group and a silane group that react complementary with the functional group originating from the monomer (Q). Reactant (T) (hereinafter referred to as "(5) resin composition")
(6) Polymerizable unsaturated monomer having a functional group (U
) and a copolymer (V) containing the silane group-containing polymerizable unsaturated monomer (K) as an essential component, and a functional group that reacts complementary with the functional group originating from the monomer (U); Reactant (X) with a compound (W) having an epoxy group (hereinafter referred to as "(6) resin composition") (7) Reactant (X) with the homopolymer (N) or copolymer (N) and the reactant ( (Y) (hereinafter referred to as "(7) resin composition") and (8) a mixture of the homopolymer (P) or copolymer (P) and the reactant (F) ( 2) (hereinafter referred to as "(8) Resin composition") Yuagari Sarakofu 1 The resin (A) can be appropriately selected from conventional resins without any particular restrictions as long as it has the above-mentioned functional group. . Specific examples include resins such as vinyl resin, fluororesin, polyester resin, alkyd resin, silicone resin, urethane resin, and polyether resin.

The resin (A) contains the compound (B) and the compound (
The resin has an average of two or more functional groups that react with the functional group in C), and the functional groups in the resin may be the same or different.

When the functional groups in the resin (A) are the same, for example, an average of 2
The resin (A) having at least 1 hydroxyl group is combined with a compound CB) having an incyanate group (5) and an isocyanate group (
5), or
Resin having an average of 2 or more isocyanate groups (5) (
A) can be reacted with a compound (B) having a hydroxyl group (1) and a compound (C) having an incyanate (5).

In addition, when the functional groups in the resin (A) are different, for example, the resin (A) having an average of one or more hydroxyl groups (1) and carboxyl groups (2) may be replaced with an incyanate group (5).
can be reacted with a compound (C) having an epoxy compound (C) and a compound (B) having an epoxy (4).

There is no problem even if the reactor in the compound (B) that reacts with the functional group in the resin (A) is the same as the epoxy group possessed by the compound (B). Similarly, the functional group in the compound (C) that reacts with the functional group in the resin (A) may be the same as the silane group contained in the compound (C).

Resin (A) can have a number average molecular weight of about 3000-200000, preferably about 5000-80000.6 Compound (B) and compound (C) can have a number average molecular weight of about 120-1000.
0, preferably about 120 to 3000.

The reactant (D) obtained by reacting the resin (A) with the compound (B) and the compound (C) has an average of 1 or more, preferably an average of 2 to 40 epoxy groups and silane groups in each molecule. can have.

This reactant corresponds to the resin (1) above. The resin (E) has on average one or more functional groups in one molecule that react with the functional group of the compound CB), Specifically, it can be used by appropriately selecting from among the resin compositions (1) above.

Compound (B) has on average one or more functional groups in one molecule that react with the functional groups of resin (E), and has on average one or more epoxy groups.

The functional group in the compound (B) may be the same as the epoxy group. As the compound (B), the same compounds as those described in (1) resin composition can be used.

The resin (G) has on average one or more functional groups in one molecule that react with the functional groups of the compound (C), and specifically, it is appropriately selected from the resin compositions (1) above. It can be used as

Compound (C) has on average one or more functional groups in one molecule that react with the functional groups of resin (G), and also has one or more silane groups on average. The functional group in the compound (C) may be the same as the silane group.6 The same compounds as those described in (1) Resin composition can be used as the compound (C).

Resin (E) and resin (G) are about 3000 to 20000
0, preferably about 5,000 to 80,000.

The reactant (F) obtained by reacting the resin (E) and the compound (B) has an average of 1 or more, preferably an average of 2 per molecule.
0 reactants (which can have ~40 epoxy groups)
F) corresponds to the resin @-2.

The reactant (H) obtained by reacting the resin (G) and the compound (C) has an average of 1 or more, preferably an average of 2 per molecule.
0 reactants (H
) corresponds to resin ■-1.

Reactant (F) and reactant (H) can be blended so that the ratio of epoxy group/silane group is usually 1/99 to 99/1. Corresponds to mixed resin ■.

Copolymer (L) obtained by radical polymerization reaction of monomer (J), monomer (K), and other monomers (M) as necessary Each molecule has an average of one or more epoxy groups and an average of 2 to 40 epoxy groups and silane groups, and corresponds to the resin (2).

A copolymer (N) of a monomer (J) and a monomer (M) is 1
The molecule can have an average of 1 or more epoxy groups, preferably 2 to 40 epoxy groups.

Corresponds to resin ■-2.

Copolymer (P) of monomer (K) and monomer (M) is 1
The molecule can have an average of one or more silane groups, preferably 2 to 40 silane groups. Corresponds to resin ■-1.

Homo or copolymer (N) and Homo or copolymer (N)
P) usually has an epoxy group/silane group ratio of l/99 to
It can be blended so that it becomes 99/l. Corresponds to mixed resin ■.

The reactant (T) obtained by the reaction of the copolymer (R) and the compound (S) contains an average of 1 or more epoxy molecules, preferably an average of 2 to 40 epoxy molecules in one molecule. group and a silane group. The reactant (T) corresponds to resin (■).

The reactant (X) obtained by the reaction of the industrial polymer (V) and the compound (W) each has an average of 1 or more, preferably an average of 2 to 40 epoxy molecules in one molecule. group and a silane group. Reactant (X) corresponds to resin (2).

As the monomer or copolymer (N) and reactant (H), use the same monomers and reactants as described in the resin compositions (2) and (4) above. be able to.

The homopolymer or copolymer (N) and the reactant (H) can be blended so that the epoxy group/silane group ratio is usually 1/99 to 99/1.

-Nichiguchi' 11 Copolymer 1 As the monomer or copolymer (P) and reactant (F), use the same monomers and reactants as described in the resin compositions (2) and (4) above. can do.

The homopolymer (P) or the copolymer (P) and the reactant (F) can usually be blended so that the ratio of epoxy group to silane group is 1/99 to 99/l.

(1) to (6) Reactants of resin compositions (DJ, (F), (
H), (L), (N), (P), (T) and (W) are
about 3,000 to 200,000, preferably about 50
It can have a number average molecular weight ranging from 0.00 to 80,000.

The resin composition may be used, for example, in a hydrocarbon solvent such as toluene or xylene, a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone, an ester solvent such as ethyl acetate or butyl acetate, or an ether solvent such as dioxane or ethylene glycol diethyl ether. The resin composition can be used in a dissolved or dispersed form in an alcoholic solvent such as butanol or propatool, or in the form of a non-aqueous dispersion containing the resin composition as a dispersion stabilizer component.

In the present invention, among the above resins (1) to (8), (3
) and (4) are preferably used. Furthermore, (3) among the resin compositions, the following epoxy group-containing polymerizable unsaturated monomer (a), silane group-containing polymerizable unsaturated monomer (b), and hydroxyl group-containing unsaturated monomer (c ) and, if necessary, other polymerizable unsaturated monomers (d), and (4) as the resin composition, the epoxy group-containing polymerizable unsaturated monomers (a) and A polymer with other polymerizable unsaturated monomers (d) as necessary, a silane group-containing polymerizable unsaturated monomer (b) and other polymerizable unsaturated monomers (d) as necessary. ), and one or both of these polymers contains a hydroxyl group-containing unsaturated monomer (C) as a monomer component.

Examples of the epoxy group-containing polymerizable unsaturated monomers include those represented by the following general formula 6 (wherein R1 is the same or different and represents a hydrogen atom or a methyl group, R2 is the same or different and represents CI~, represents a hydrocarbon group, R8
are the same or different and represent a C3-2° hydrocarbon group, and W represents an integer of 0 to 10.) Examples of the silane group-containing polymerizable unsaturated monomer include those represented by the following general formula. .

(In the formula, R1 and R1 have the same meanings as above, Y is the same or different and represents a hydrogen atom, a hydroxyl group, a hydrolyzable group, 01~.alkyl group, an aryl group, an aral chiral group, One of them is a hydrogen atom, a hydroxyl group, or a hydrolyzable group.

In addition to the above, polysiloxane unsaturated monomers having silane groups and polymerizable unsaturated groups obtained by reacting the silane group-containing polymerizable unsaturated monomer with a compound represented by the general formula % can also be used. Saturated monomers can be used as well.

(In the formula, Y' is the same or different and represents a hydrogen atom, a hydroxyl group, or a hydrolyzable group, and R4 represents an alkyl group, an aralkyl group, or an aryl group of 01 to 8.

Specific examples of the polysiloxane unsaturated monomer include 1. For example, a polysiloxane macromonomer obtained by reacting the above two types of compounds with 30 to 0.001 mol% of the former and 70 to 99.999 mol% of the latter ( For example, JP-A-62-
275132) and the compounds listed below.

Examples of the hydroxyl group-containing unsaturated monomer include those represented by the following general formula.

CH,=CR,0 COC,H,,OiCC,Ha,O),H In the formula, Ri has the same meaning as above, m is an integer of 2 to 8, and P is 2 to
An integer of 18, q represents an integer of 0 to 7.

Other polymerizable unsaturated monomers include the following.

■ Olefin compounds: e.g. ethylene, butylene,
Isoprene, chlorobrene, etc.

■ Vinyl ethers and allyl ethers: e.g. ethyl vinyl ether, propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether, tert-
Chain alkyl vinyl ethers such as butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, isohexyl vinyl ether, octyl vinyl ether, 4-methyl-1-pentyl vinyl ether, cycloalkyl vinyl ethers such as cyclopentyl vinyl ether, cyclohexyl vinyl ether, phenyl vinyl ether, o+, m+ , aryl vinyl ethers such as p-h ribinyl ether, benzyl vinyl ether,
Aralkyl vinyl ethers such as phenethyl vinyl ether, etc.

■ Vinyl esters and propenyl esters, such as vinyl acetate, vinyl lactate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl incaproate, vinyl bivaric acid, vinyl caprate, and impropenyl acetate, impropenyl propionate, etc. propenyl esters, etc.

■ Esters of acrylic acid or methacrylic acid: e.g.
Methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, methacrylic acid C1-18 alkyl esters of acrylic acid or methacrylic acid such as butyl, hexyl methacrylate, octyl methacrylate, lauryl methacrylate: methoxybutyl acrylate, methoxybutyl methacrylate,
Acrylic acid or methacrylic acid having 2 to 1 carbon atoms, such as methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, and ethoxybutyl methacrylate
8 alkoxyalkyl ester, etc.

(2) Vinyl aromatic compounds: For example, styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc.

■Others: Acrylonitrile, methacrylonitrile, etc.

The resin composition may be used, for example, in a hydrocarbon solvent such as toluene or xylene, a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone, an ester solvent such as ethyl acetate or butyl acetate, or an ether solvent such as dioxane or ethylene glycol diethyl ether. The resin composition can be used in a dissolved or dispersed form in an alcoholic solvent such as butanol or propatool, or in the form of a non-aqueous dispersion containing the resin composition as a dispersion stabilizer component.

In addition, as curing agents, metal chelate compounds, Lewis acids, protonic acids, metal alkoxides, organometallic compounds,
Compounds having an i-0-Ail bond can be used.

Among these, metal chelate compounds, aluminum chelate compounds, titanium chelate compounds, and zirconium chelate compounds are preferred. Specific examples of the preferred metal chelates include tris(ethylacetoacetate)aluminum, tris(n-pro-and-ruacetoacetate)aluminum, tris(isopropylacetoacetate)aluminum, tris(n-butylacetoacetate)aluminum, isopropoxy Bis(ethylacetoacetate)aluminum, diisopropoxyethylacetoacetatealuminum, tris(acetylacetonato)aluminum, tris(propionylacetonato)aluminum, tris(ethylacetonato)aluminum, diinpropoxypropionylacetonatoaluminum, acetylacetonato・Bis(propionyl acetonato)aluminum, monoethylacetoacetate bis(acetylacetonato)aluminum, tris(isopropylate)aluminum, tris(sec-
butyrate) aluminum, diisopropylate mono-
Aluminum chelate compounds such as 5ec-butoxyaluminum, tris(acetonatoacetone)aluminum, diisopropoxy bis(ethylacetoacetonato) titanate, diisopropoxy bis(acetylacetonato) titanate, diisopropoxy bis(acetylacetonate) Titanium chelate compounds such as nato) titanate: tetrakis(acetylacetone)zirconium, tetrakis(n-bro and ruacetoacetate)zirconium, tetrakis(acetylacetonato)zirconium,
Zirconium chelate compounds such as tetrakis(ethyl acetoacetate) zirconium can be mentioned.

The aluminum chelate compound, zirconium chelate compound, and titanium chelate compound may be used alone or in combination of two or more, and the amount of the curing agent is based on the solid content of the resin 100 weight It is appropriate that the amount is about 0.01 to 30 parts by weight.

The top coating composition of the present invention may contain organic pigments, inorganic pigments, various paint additives, and the like, if necessary.

Inorganic pigments include oxide-based pigments (titanium dioxide, red iron oxide, M-based ROM, etc.) and hydroxide-based pigments (alumina white, etc.)
, sulfate-based (precipitated barium sulfate, etc.), carbonate-based (precipitated calcium carbonate-based), sulfate-based (clay, etc.), carbon-based (carbon black, etc.), metal powder (aluminum powder, bronze powder, zinc powder) etc.). In addition, organic pigments include azo-based pigments (lake red, first yellow, etc.),
Examples include phthalocyanine (phthalocyanine blue, etc.).

Further, the top coating film can be formed, for example, as a solid color coat, clear coat/pace coat (two coat one bake, two coat one bake system, etc.).

It is also possible to apply the top coat directly to the barrier coated surface (omitting the intermediate coat).

The top coating used in the present invention is classified into enamel paint, which is a paint using the above-mentioned vehicle main component mixed with metallic pigments and/or colored pigments, and clear paint, which contains no or almost no of these pigments. Then, as a method of forming a top coat film using these paints, for example, ■Metallic pigment, if necessary, applying a metallic paint blended with a colored pigment or a solid color paint blended with a colored pigment. , heat cured (metallic or solid color finish using 1 coat 1 beta method)
.

■After applying metallic paint or solid color paint and curing with heat, apply clear paint and heat harden again (metallic or solid color finish using 2-coat, 2-bake method).

■Paint with metallic paint or solid color paint,
Subsequently, a clear paint is applied, and then heated to simultaneously cure both paint films (metallic or solid color finish using a two-coat one-bake method).

These top coat paints are preferably applied by spray painting, electrostatic painting, or the like. In addition, the coating film thickness is based on the dry coating film, 25 to 40μ for the above ■, and for the above ■ and ■,
10-3 for metallic paints and solid color paints
0μ and clear paint preferably have a thickness of 25 to 50μ. Heating conditions can be arbitrarily adopted depending on the vehicle components, but heating conditions are 80 to 170°C, especially 120 to 150°C and 10 to 40°C.
Minutes are preferred.

(Effect of the invention) The reason why the present invention provides chipping resistance in the steel plate coating system is that the barrier coating film has viscoelasticity based on olefin resin and urethane resin, so there are no pebbles etc. on the top coated surface. Even if a strong impact force is applied, most of the impact energy is absorbed within the barrier coating film and does not reach the underlying layer.

In addition, the reason why this barrier coat has improved storage stability and topcoat finish that could not be obtained with conventional water dispersion types is that the water dispersion of urethane resin has a particle size of 0.1μ or less, and the particle surface This is thought to be because it has a function of preventing olefin resin particles from agglomerating together due to charge repulsion.

In addition, the top coat has excellent low-temperature curing properties, so it is usually
The coating film formed by the coating method of the present invention, which is crosslinked at the top coating baking temperature of 20°C to 140°C for automobile steel plates to form a strong coating film, has excellent chipping resistance, rust resistance, and corrosion resistance. It is thought that the reason why this method is superior to conventional methods in terms of not only stain resistance and weather resistance is due to the use of the above-mentioned barrier coat and top coat.

(Effects of the Invention) As explained above, according to the present invention, a barrier coat film mainly composed of an aqueous compound of an olefin resin and a urethane resin can be applied between the eyebrows of an electrodeposition coating film and an intermediate coating film. By forming it into a steel plate, the chipping resistance, rust resistance, corrosion resistance, and finishing properties of the steel plate coating system are significantly improved. Moreover, the effect of dramatically improving the storage properties of conventional water-based barrier coats can be obtained. Furthermore, it has excellent stain resistance, chemical resistance, weather resistance, image clarity, and smoothness.

Next, examples and comparative examples related to the present invention will be described.

■Sample (1) Steel sheet: Galvanized steel sheet chemically treated with Bonterite #3O-30 (manufactured by Nippon Barker Rising ■, zinc phosphate system) (size 300x90x0.8mm) (2) Cationic electrodeposition paint: Nireclone #9200 (
(Manufactured by Kansai Paint ■, epoxy polyamide cationic electrodeposition paint, gray color) (3) Water-based barrier coat First, the emulsion (
a-1) ~ (a-3), (b-1) j5 and (b-2
), as well as the production examples of resin solutions (A-1), (A-2)i5 and (B-1), and then the production of barrier coats (E-1) to (E-5) will be explained. .

In addition, both parts and percentages are based on weight in principle.

Urethane prepolymer A-1 polybutylene adipate 225 with a number average molecular weight of 2000
parts, 375 parts of polycaprolactone diol with a number average molecular weight of 2000, 26 parts of 1,4-cyclohexane dimetatool
．． 6 parts of dimethylolpropionic acid, and 313 parts of inphorone diisocyanate (NG
O10H=1.57) was charged into a polymerization container, and the temperature was raised to 50°C in a nitrogen gas atmosphere while stirring, then 0.05 part of dibutyltin oxide was added as a polymerization catalyst, and then 70
The reaction was carried out at a temperature of 1 hour to obtain a urethane prepolymer (A-1) having a terminal NGO group and having an NCO group content of 3%. The number average molecular weight was 2150.

Urethane emulsion a-1 350 parts of the urethane prepolymer (A-1), 115 parts of acetone, and 35 parts of N-methylvinylpyrrolidone were charged into a reaction vessel, and after uniformly dissolving at 50°C, the mixture was stirred. 14.5 parts of triethylamine was added to the mixture, and 550 parts of deionized water was added while maintaining the temperature at 50° C., followed by stirring for 2 hours to complete the water extension reaction.

Further, vacuum distillation was performed at 80° C. or lower to remove acetone until the distillate amounted to 115 parts, thereby obtaining 950 parts of urethane resin emulsion (a-1) with a solid content of 37%. The number average molecular weight is 32,000, and the average particle diameter is 0. It was an IP.

256 parts of the polybutylene adipate of urethane A-2, 427 parts of the polycaprolactone diol, 30 parts of 1,4-cyclohexane dimetatool, 68 parts of dimethylolpropionic acid,
and a raw material consisting of 219 parts of inphorone diisocyanate (NGO10H=0.975) into a polymerization container,
Heat while stirring and filling with nitrogen gas, and when the temperature reaches 50°C, add 0.05 part of dibutyltin oxide.
The reaction was carried out at 0°C for 4 hours. After that, the temperature was lowered to 60°C and 50 parts of methanol was added to inactivate the unreacted NGO groups. Then, 345 parts of acetone and 105 parts of N-methyl-vinylpyrrolidone were added and stirring was continued until uniformly dissolved. A 67% urethane resin (A-2) was obtained. The number average molecular weight was 25,000.

528.5 parts of the urethane resin (A-2) of urethane emulsion a-2 was charged into a reaction vessel, and while stirring at 50°C, 14.5 parts of triethylamine was added, and while maintaining the temperature at 50°C, 620 parts of deionized water was further added. The acetone and methanol were gradually added and stirred for an additional hour.Next, acetone and methanol were distilled off under reduced pressure at 70°C. When the distillate reached 139 parts, the vacuum distillation was stopped and the solids were removed. 35%, organic solvent content 14.
A 6PHR urethane resin emulsion (a-2) was obtained. The average particle diameter was 0.05P.

Urethane emulsion a-3 476 parts of polytetraoxymethylene glycol with a molecular weight of 2000, and -FLEX188 (K
ING Industries Inc.
o.

130 parts of cyclohexane dimetatool-terminated linear polyester, 26 parts of 1,4-cyclohexane diisocyanate, 63 parts of dimethylolpropionic acid, 3.5 parts of glycerin, tolylene diisocyanate (TDI)
184 parts, and isophorone diisocyanate (IPDI
) A raw material consisting of 117 parts (OH/NGO = 1.33) was charged into a polymerization vessel, and in the same manner as prepolymer (A-1), a urethane prepolymer having an NCO group content of 3% and terminal NGO groups was prepared. Polymer Obtained First Step A urethane resin emulsion (a-3) with a solid content of 38% was obtained in exactly the same manner as emulsion (a-1) except that this prepolymer was used.6 The molecular weight was 43,000, and the average Particle size is 0.074
Met.

Examples of Olefin Emulsion b-1 Maleated chlorinated polypropylene with an average molecular weight of 10,000 (chlorination rate 25%, maleic anhydride content 2.0%)
), 150 parts of n'S butane and 50 parts of 1N-methylvinylpyrrolidone were charged into a reaction vessel, and stirred at 70°C under a nitrogen gas atmosphere to uniformly dissolve, to obtain an olefin resin solution (B-1). . After that, after cooling the inside of the system to 50°C, 10.6 parts of triethylamine and Neugen EA were added.
-140 (polyethylene glycol noniphenyl ether, nonionic surfactant, HLB 1 4, manufactured by Dai-Kogyo Yakuhin) was added and stirred for 1 hour, followed by 2 parts of deionized water.
000 parts were gradually added and stirring was continued for an additional hour.
Next, the solvent was removed under reduced pressure at 70°C, and n-hebutane and water were distilled off until the distillate became 600 parts, and the solid content was 2.
A 3.6% olefin resin emulsion (b-1) was obtained. The average particle diameter was 0.8P.

A chlorinated polypropylene resin (number average molecular weight (
Mn) 5800. Chlorine content 2696) (7) Solid content 5
700 parts of 0% toluene solution and 350 parts of butyl cellosolve
A portion was charged and heated to 100°C.

Next, a mixture of 52 parts of acrylic acid, 130 parts of styrene, 468 parts of n-butyl acrylate, 69 parts of 75% benzoyl peroxide, and 50 parts of isopropanol was added dropwise to the chlorinated polypropylene resin solution over 3 hours. , and aged for 1 hour at the same temperature. Next, a solution prepared by dissolving 3.25 parts of azobisisovaleronitrile in 50 parts of butyl cellosolve was added dropwise to this mixture over 1 hour, and the temperature was kept at the same temperature for 1 hour.The temperature was further raised to 110°C to remove unreacted monomers. , water, isopropanol, and toluene were removed under reduced pressure to obtain a resin solution (B-2) with a resin acid value of 40.5.

Next, while stirring (B-2), dimethylethanolamine was added to the mixture in an amount of 1.0 neutralization equivalent to the carboxyl group in the resin solution, and then 2 mL of deionized water was added.
075 parts were added to obtain an emulsion (b-2) with a solid content of 28.2% and an olefin resin/acrylic resin solid content ratio of 35/65. The average particle diameter was 0.5P.

Barrier coat E-1 208 parts of the urethane resin emulsion (a-1) and 106 parts of the olefin resin emulsion (b-1) were mixed well at 25°C in a stirring vessel, and the solid content was 31.8% (maleic chlorination). Olefin/urethane resin = 25/75)
, (a-1), (b-) with an organic solvent content of 12.5 PHR
1) A mixed emulsion (c-1) was obtained.

Emulsion (c-1) 404 parts, titanium white 100 parts,
and 0.3 part of carbon pigment were thoroughly kneaded to obtain a barrier coat (E-1).

Barrier Coat E-2 120 parts of the urethane resin (A-2) and 35 parts of the olefin resin solution (B-1) were charged into a reaction vessel, and while stirring the system was maintained at 50°C, 3.1 parts of triethylamine was added.
After adding 25 parts of Neugen EA-1400 and 25 parts of Neugen EA-1400 and continuing stirring for 1 hour, 127.4 parts of deionized water was added over 1 hour, and the solvent was removed under reduced pressure at 70°C until the distillates (acetone, methanol) were removed. Repeat until the weight is 29.6g, and the non-volatile content is 3.
9.0% (maleated chlorinated polypropylene/polyurethane ratio = 25/75), organic solvent content 17.4PH
An emulsion of H (c-2) was obtained. The average particle size is 0
．． It was 28 μm. This emulsion (c-2) 25
6 parts of titanium white, 100 parts of titanium white, and 0.3 parts of carbon pigment were thoroughly kneaded to obtain a barrier coat (E-2).

Barrier Coat E-3 214.2 parts of the urethane resin emulsion (a-2) and 105 parts of the olefin resin emulsion (b-1).
9 parts were mixed well at 25°C in a stirring vessel until the solid content was 32.
2% (maleated chlorinated polypropylene/urethane resin = 25/75), organic solvent content 16 PHH (a-2
) (b-1) Mixed emulsion (c-3) Obtained.

320 parts of this emulsion (c-3), 100 parts of titanium white
1 part and 0.3 part of carbon pigment were thoroughly kneaded to obtain a barrier coat (E-3).

Bar1 Arcoat E-4 Maleated polyethylene-bolybropylene copolymer resin 70 having a number average molecular weight of 30,000 and having a maleic anhydride content of 2% by weight and a ratio of ethylene to polypropylene of 40 parts/60 parts.
1, 70 parts of N-methyl-vinylpyrrolidone, and 70 parts of toluene were stirred in a reaction vessel at 100°C for 1 hour to obtain a homogeneous olefin resin solution (B-3).Next, the inside of the reaction vessel was heated to 75°C. Then, 280 parts of the urethane prepolymer (A-1) and 7 parts of methyl ethyl ketone were added.
After neutralizing with 14.5 parts of triethylamine, 700 parts of deionized water was added while maintaining the temperature at 75°C, and the reaction was allowed to proceed for 2 hours to complete the water extension reaction. Furthermore, methyl ethyl ketone was distilled off by vacuum distillation, and the solid content was 29.
3% (maleated ethylene-propylene copolymer/polyurethane resin = 20/80), solvent content 39.5PH
An emulsion of H was obtained. The average particle size of this emulsion was 0.5P. A barrier coat (E-
4) was obtained.

Barrier coat E-5 177.3 parts of emulsion (b-3), emulsion (
a-1) 135.1 parts, 100 parts of titanium white, and 0.3 parts of carbon pigment were thoroughly kneaded to form a barrier coat (E-
5) was obtained.

1 company Yudan two-way polyolefin resin emulsion (b-1) 423.7
100 parts of titanium white, and 0.4 parts of carbon pigment were thoroughly kneaded to obtain a paint (E-6).

Raw 1 and 420 parts of the polyolefin resin solution (B-3), 3.0 parts of triethylamine, Neugen EA-150 (polyethylene glycol) nylphenyl ether, nonionic surfactant, HLB15, manufactured by Dai-Kogyo Yakuhin. ) and 280 parts of deionized water are thoroughly mixed to obtain an aqueous dispersion of polyolefin resin (B-3). The particle size of the dispersion was 25μ. 504 parts of this aqueous dispersion, 100 parts of titanium white, and 0.3 parts of carbon were thoroughly kneaded to obtain a paint (E-7).

1 mm 1 g of polyoxytetramethylene glycol with an OH value of 55 (PTG-50011020, manufactured by Hodogaya Chemical Industry ■) was dehydrated under reduced pressure at 100°C, and then cooled to 40°C to form tolylene diisocyanate. 178.6 parts were added and reacted at 85°C for 3 hours. Next, an acid value of 233 synthesized from 134.0 parts of trimethylolpropane and 98.0 parts of maleic anhydride was added to this polyurethane prepolymer.
．． 8. 49.9 parts of a half ester compound was added and reacted at 85° C. for 3 hours under a nitrogen stream to obtain an incyanate-terminated prepolymer containing carboxyl groups. This prepolymer was maintained at 85°C and 8.2% of sodium hydroxide was added.
When the mixture was poured and emulsified into 1534 parts of an aqueous solution containing 1,534 parts of a milky white solid with a homomixer, a milky white solid content of 44.5 parts was obtained.
A 9% polyurethane emulsion was obtained.

222.7 parts of this emulsion, 100 parts of titanium white, and 0.3 parts of carbon pigment were mixed well to form a paint (E-8).
I got it.

For (E-1) to (E-8), the viscosity was adjusted to 500 to 600 centibois (B-type viscometer, 20°C) with deionized water, and then used for coating.

Furthermore, among (E-1) to (E-8), (E-6) to (
E-8) is a barrier coat for comparison.

(4) Intermediate paint Near Mirac N-2 Sealer (manufactured by Kansai Paint ■, amino polyester resin intermediate paint) [5) Top coat IUIL Methyltrimethoxysilane 2720g γ-methacryloxypropyltrimethoxysilane 256g Deionized Water 1134g 30% hydrochloric acid
2g hydroquinone
1 g of these mixtures were reacted at 80° C. for 5 hours to obtain a polysiloxane macromonomer. The number-average molecular weight of the macro-hetamine was 2000. It had an average of one vinyl group (polymerizable unsaturated bond) and four hydroxyl groups per molecule.

Using the above polysiloxane macromonomers, a mixture of 100g of polysiloxane macromonomers, 00g of 2-hydroxyethyl acrylate, 00g of 3.4-cyclohexylmethyl methacrylate, 500g of 2-ethylhexyl methacrylate, 100g of styrene, and 50g of azobisisobutylnitrile was mixed with butanol and xylene. was added dropwise at 120° C. to 1000 g of a mixture of equal weights to obtain a resin solution with a solid content of 50% by weight. The number average molecular weight of the resin was approximately 10.000.

A mixture of 100 g of γ-methacrylate trimethoxysilane, 00 g of 2-hydroxyethyl methacrylate, 00 g of 3.4-cyclohexyl methacrylate, 500 g of 2-ethylhexyl methacrylate, 500 g of styrene, 100 g of azobisisobutylnitrile, and 50 g of butanol. The mixture was added dropwise at 120° C. into 1000 g of a mixture of equal weights of xylene and xylene to obtain a resin solution with a solid content of 50% by weight. The number average molecular weight of the resin was approximately 9,000.

Polysiloxane-based macro 100g 2-hydroxyethyl acrylate 100g 2-ethylhexyl methacrylate 500g styrene
A mixture of 50 g of 200 g of azobisisobutyronitrile was dropped into 1.000 g of an equal weight mixture of butanol and xylene at 120° C. to obtain a resin solution with a solid content of 50% by weight. The number average molecular weight of the resin was approximately 10.000.

A mixture of 200g 2-hydroxyethyl methacrylate 00g 2-ethylhexyl methacrylate 500g styrene 200g azobisisobutylnitrile 50g was added to 1.000g of an equal weight mixture of butanol and xylene. The mixture was added dropwise at 0.degree. C. to obtain a resin solution with a solid content of 50% by weight. The number average molecular weight of the resin was approximately 9.000.

Spoon 1Ω111 3.4-cyclohexyl methacrylate 00g 2-hydroxyethyl methacrylate 00g 2-ethylhexyl methacrylate 400g styrene 100g azobisisobutylnitrile A mixture of 50g was dropped into 1.000g of an equal weight mixture of butanol and kijirole at 120°C. As a result, a resin solution with a solid content of 50% by weight was obtained. The number average molecular weight of the resin was approximately 9.000.

Top 1 Unit 1 Side 11 Solid color paint, metallic base paint, and clear paint were prepared using the formulations shown in Table-1.

■Example Comparative Example Using the above sample, a cationic electrodeposition paint, a barrier coat, an intermediate coat and a top coat were applied to a steel plate as shown in Table 2.

In Table 2, the film thickness is based on the cured coating;
Both systems using top coats B and C have a two-coat bake finish.

■ Performance test results A coating film performance test was conducted using the coated plates coated in the above Examples and Comparative Examples. The results are shown in Table 3.

Test method (*1) Image clarity: Image C1arity Meter (HA
-I CH, Suga Test Instruments ■).

(*2) Impact resistance JIS K5400-1979 6.13.3B method, 6 weight 500 in an atmosphere of 0°C
Damage to the paint film was examined by dropping a 50 cm weight from a height of 50 cm.

(*3) Adhesion: In accordance with JIS K5400-1979 6.15, grooves were made on the coating film, adhesive cellophane tape was applied to the surface, and the coated surface was evaluated after it was quickly peeled off.

(*4) Water resistance: Evaluation of painted surface after 10 days of immersion in 40°C water (*5)
Chipping resistance - ■ (1) Test equipment: Q-G-R Gravelometer (product of Q Panel Company) (2) Stone to be sprayed: Crushed stone with a diameter of 15 to 20 m/m (3) Stone to be sprayed Capacity: Approximately 500 m1' (4) Air pressure: Approximately 4 kg/cm2 (5) Temperature during test: Approximately 20°C The test piece was attached to the test piece holding stand, and the air pressure was approximately 4 kg/cm2.
The spraying is about 500+Id with air pressure! After blasting crushed stone particles onto a test piece, the coating surface condition and salt spray resistance were evaluated. The condition of the painted surface was visually observed and evaluated using the following criteria. For salt spray resistance, test pieces were subjected to a salt spray test for 240 hours in accordance with JIS Z2371, and the presence or absence of rust from the impact area and the state of corrosion were observed. .

0 (Good): Very few scratches due to impact were observed in a part of the top coat, and no peeling of the electrodeposited film was observed.

△ (slightly poor) There are many scratches on the second coat and intermediate coat due to impact (noted, and peeling of the electrodeposition coating is also observed here and there).

× (Poor) Most of the second top coat and intermediate coat peeled off, and the electric @ paint film on the impacted area, including the impacted area and its surroundings, peeled off.

(*6) Chipping resistance - ■ The barrier coats (E-1) to (E-5) and the paints (E-6) to (E-8) were each stored at 20°C for one month. The chipping resistance of the coated plate produced using
The same tests were conducted and evaluations were made using the same criteria.

Claims (1)

[Claims] A cationic electrodeposition paint is applied to a steel plate, and then a water-based barrier coat whose main vehicle component is a composition consisting of an olefin resin and a urethane resin is applied to the painted surface, and an intermediate paint is applied as necessary. The main component is a composition obtained by adding a curing agent to a resin containing a hydroxysilane group and/or a hydrolyzable group directly bonded to a silicon atom and an epoxy group as essential functional groups. A steel plate coating method characterized by applying a top coat of paint.