JPH09132752A - Primer for aluminum wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject primer consisting of a polyurethane resin, an acrylic resin, a chelate compound, etc., as major components, excellent in adhering property to an aluminum surface and also in corrosion resistance, not containing a substance generating an environmental pollution, having an improved safety and useful for an aluminum wheel for an automobile. SOLUTION: This primer for an aluminum wheel consists of (A) a polyurethane resin having hydroxyl group and/or carboxyl group, (B) an acryl resin, (C) a chelate compound (e.g.; aluminum trisacetylacetate), (d) an epoxy resin and (E) a silane coupling agent [e.g.; γ-(2-aminoethyl) aminopropyltrimethoxysilane] as main components. Further, in order to constitute ratios of 50-100 pts.wt. component (B) and 2-10 pts.wt. component (C) based on 100 pts.wt. component (A), 5-15 pts.wt. component (D) and 1-5 pts.wt. component (E) based on the total of the components (A) to (C) are preferably contained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum wheel primer suitable for an automobile aluminum wheel and having excellent adhesion and corrosion resistance.

[0002]

2. Description of the Related Art Wheels for automobiles, which are mounting members for tubes and tires, are made of steel, aluminum or the like. Of these, weight reduction,
Aluminum wheels excellent in anticorrosion properties and design properties (hereinafter abbreviated as "aluminum wheels") are often used. For protection and aesthetics, aluminum wheels are usually used, for example. , 2 kinds of thermosetting acrylic resin-based pigmented paint and thermosetting acrylic resin-based clear paint
It is painted in the same way. Moreover, in order to impart adhesion between the coating film and the aluminum wheel, a primer mainly containing an epoxy resin and a chromic acid-based rust preventive pigment may be applied in advance.

However, the coating film coated as described above does not have sufficient adhesion to the substrate even if a primer is used, and is inferior in corrosion resistance (generation of white rust). Moreover,
There is also a problem that the use of a chromic acid-based rust preventive pigment is not preferable in terms of pollution prevention.

[0004]

The object of the present invention is to eliminate the above-mentioned defects, prevent pollution, and improve the adhesion to the base material and the corrosion resistance (white rust) of the primer for an aluminum hole. Regarding

That is, the present invention provides (A) a polyurethane resin having a hydroxyl group and / or a carboxyl group,
(B) Acrylic resin, (C) chelate compound, (D) epoxy resin and (E) silane coupling agent as a main component for aluminum wheel primer.

The aluminum wheel primer of the present invention will be described in detail below.

The aluminum wheel (object to be coated) coated with the primer of the present invention is an automobile wheel which is a mounting member for tires and tires for automobiles such as passenger cars, auto-byes, trucks and wagons. And is made of an alloy containing aluminum as a main component or further containing magnesium, silicon, or the like, and can be formed into an arbitrary shape for the purpose of weight reduction and design. It also includes an aluminum wheel in which a shot-blasted uneven casting surface and a cut smooth surface are mixed. It is preferable that the surface of the aluminum wheel is subjected to a chemical conversion treatment with a chromate or a phosphate before coating the primer.

Component (A): Polyurethane resin having a hydroxyl group and / or a carboxyl group: It has two or more hydroxyl groups and / or carboxyl groups in one molecule and has a urethane bond (or urea bond). It is obtained mainly by reacting an active hydrogen-containing compound with a polyisocyanate compound.

The active hydrogen-containing compound is a compound having two or more functional groups such as a hydroxyl group and an amino group which react with an isocyanate group in one molecule, and includes both a high molecular weight compound and a low molecular weight compound.

As the high-molecular weight active hydrogen-containing compound,
For example, polyester polyol, polyether polyol
And polycaprolactone polyol, polycarbonate carbonate polyol, polydiene polyol, acrylic resin polyol, polyamide resin and the like. As these high molecular weight active hydrogen-containing compounds, those known per se can be used, and their number average molecular weights are about 1000-1.
It is preferably in the range of 00000, particularly 2000 to 50,000.

As the low molecular weight active hydrogen-containing compound, for example, bifunctional glycols such as ethylene glycol and propylene glycol: glycerin, trimethylol
Tri- or higher functional polyols such as propane and sorbitol
Examples thereof include alkanol amines such as monoethanolamine and diethanolamine: diamines such as ethylenediamine, hexamethylenediamine, isophoronediamine, xylylenediamine and tolylenediamine. The molecular weight of these low molecular weight active hydrogen-containing compounds is suitably 1,000 or less, particularly 500 or less.

The polyisocyanate compound which can be reacted with these active hydrogen-containing compounds is a compound having two or more free isocyanate groups in one molecule. Specifically, aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate and trimethylene diisocyanate: isophorone diisocyanate Alicyclic diisocyanates such as methylenebis (cyclohexyl isocyanate) and cyclohexane diisocyanate
Toxylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate and biphenylene diisocyanate.
Aromatic diisocyanates such as g.
One or more of these can be used.

The component (A) is prepared by a conventional method such as the one-shot method or the prepolymer method using the above-mentioned high molecular weight active hydrogen-containing compound and / or low molecular weight active hydrogen-containing compound and a polyisocyanate compound. The free hydroxyl group and amino group can be introduced into the skeleton of the component (A) by reacting the active hydrogen group of the active hydrogen compound with a large amount of isocyanate groups. Further, the carboxyl group can be introduced by using a hydroxycarboxylic acid compound such as dimethylolpropionic acid as a low molecular weight active hydrogen-containing compound in combination.

Component (B): Acrylic resin A polymer containing acrylic acid ester and / or methacrylic acid ester as a main component, wherein the component (B) has a hydroxyl group, a carboxyl group, an amino group and the like in its molecule. It preferably has a crosslinkable functional group.

Examples of acrylic acid esters and methacrylic acid esters include monoesters of acrylic acid or methacrylic acid and alcohols having 1 to 201 carbon atoms, and specific examples thereof include methyl acrylate, methyl methacrylate, and acrylic acid. Examples thereof include ethyl acid, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, lauryl acrylate, and lauryl methacrylate.

Other monomers that can be copolymerized with the acrylic acid ester and the methacrylic acid ester include:
Unsaturated compounds having one or more polymerizable double bonds in one molecule, for example, acrylonitrile, methacrylonitrile, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl. Methacrylate, caprolactone hydroxyethyl acrylate, caprolactone hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, acrylic acid amide, methacrylic acid amide, glycidyl acrylate
Glycidyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, styrene, vinyl acetate,
Vinyl methyl ether, vinyl chloride, vinylidene chloride,
Examples include ethylene and propylene.

In the component (C), the constituent ratio of the acrylic acid ester or methacrylic acid ester and the other monomer can be arbitrarily selected according to the purpose, but based on the total weight of the both components, the acrylic acid ester and the It is suitable that the methacrylic acid ester is in the range of 20 to 100%, particularly 40 to 80%, and the other monomers are in the range of 80 to 0%, especially 60 to 20%. The number average molecular weight of the component (C) is about 10
The range of 00 to 100,000 and about 3000 to 50,000 is preferable.

Component (C): chelate compound Organoaluminum coordination compound such as aluminum trisacetyl acetate and aluminum triisopropoxide: zirconium tetrakisacetylacetonate, diisopropoxyzirconium bisacetylacetonate Examples thereof include organic zirconium coordination compounds such as titanium tetrakis acetylacetonate and diisopropoxy titanium bisacetylacetonate, and the like.

(D) Epoxy resin A compound having two or more epoxy groups in one molecule and known per se can be used. Specifically, glycidyl ethers of an epihalohydrin such as epichlorohydrin and an aliphatic polyhydroxy compound (eg, glycol or glycerin): an epihalohydrin such as epichlorohydrin and an alicyclic polyhydroxy compound (eg, hydrogenated bisphenol A) Glycidyl ethers with epihalohydrin such as epichlorohydrin and aromatic polyhydroxy compounds (for example, bisphenol A, F, novolac phenol, cresol phenol, etc.) Glycidyl ethers such as epichlorohydrin Examples thereof include glycidyl ethers of epihalohydrin and an aromatic polycarboxylic acid compound (such as phthalic acid): epoxy group-containing acrylic resin: epoxidized oil: alicyclic epoxy resin: and the like. Of these, glycidyl ethers of epihalohydrin such as epichlorohydrin and an aromatic polyhydroxy compound are particularly preferable. For example, Epon 1001 (manufactured by Shell Kagaku Co., Ltd.) can be mentioned.

The number average molecular weight of the component (D) is 30.
The range of 0 to 2000 and the epoxy equivalent of 150 to 1100 are preferable. By using this component (D), the corrosion resistance and adhesion of the coating film are improved.

(E) Silane Coupling Agent The component (E) is represented by the general formula XSi (OR) ₃ (X is a reactive functional group and represents, for example, an amino group, a vinyl group, an epoxy group, a mercapto group or a chloro group. , R represents a hydrolyzable methoxy group, an ethoxy group, or another alkoxy group having 1 to 10 carbon atoms.).

Specifically, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, aminosilane, γ-methacryloxypropyltrimethoxysilane, N-β. -(N-vinylbenzylaminoethyl) -γ
-Aminopropyltrimethoxysilane-hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, vinylitriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane , Γ−
Examples thereof include anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride and trimethylchlorosilane. These can be used alone or in combination of two or more.

By using the component (E), the adhesion to aluminum is improved. The primer for an aluminum wheel of the present invention comprises the above-mentioned polyurethane resin having (A) hydroxyl group and / or carboxyl group, (B) acrylic resin, (C) chelate compound, (D) epoxy resin and (E). The main component is a silane coupling agent, and the composition ratio of each of these components can be arbitrarily selected according to the purpose. For example, per 100 parts by weight of the component (A),
The component (B) is preferably 10 to 160 parts by weight, particularly 50 to 100 parts by weight, and the component (C) is preferably 1 to 15 parts by weight, particularly 2 to 10 parts by weight. Then, the component (D) is 1 per 100 parts by weight of the total of the components (A), (B) and (C).
.About.20 parts by weight, particularly 5 to 15 parts by weight, and the component (E) is 0.
A range of 1 to 10 parts by weight, particularly 1 to 5 parts by weight is preferable.

The primer of the present invention is the above (A),
It can be obtained by using the components (B), (C), (D) and (E) as essential components and dissolving or dispersing them in an organic solvent.

Further, the primer of the present invention may be blended with a dye, a coloring pigment, an extender pigment, a metallic pigment, a plasticizer and the like, if necessary.

The primer for aluminum wheels of the present invention is
It is preferable to coat the aluminum wheel by airless spray, air spray, electrostatic method or the like. The viscosity during coating is preferably 5 to 15 seconds / fod cup # 4/20 ° C., and the coating film thickness is preferably about 1 to 15 μm based on the cured coating film on the flat portion (cut surface). If necessary, it is preferable that the coating film is left standing at room temperature or dried at 100 ° C. or lower for a short time and then heated to crosslink and cure the coating film at a temperature of 100 to 180 ° C.

The uncured or cured coating surface of the primer of the present invention can be coated with a topcoat paint such as a colored paint or a clear paint.

Thermosetting acrylic resin-based paints are suitable for these colored paints and clear paints. In particular,
A thermosetting paint prepared by dissolving or dispersing an acrylic resin, a crosslinking agent and a pigment (optional component) in an organic solvent is preferable.

As the acrylic resin, an acrylic resin having one or more functional groups selected from a hydroxyl group, an epoxy group and a carboxyl group which form a coating film having excellent weather resistance, smoothness and chemical resistance. Examples thereof include resins and modified resins thereof. As the cross-linking agent, compounds having a functional group capable of undergoing a cross-linking reaction with these functional groups can be used. One or more compounds selected from a compound containing a carboxyl group and a compound containing a carboxyl group are preferable. As the pigment for coloring, it is possible to use a coloring pigment and a metallic pigment for ordinary paints, for example, titanium white,
Examples thereof include carbon black, phthalocyanine blue, cincacia red, aluminum powder, mica powder, surface-coated mica powder, and mica-like iron oxide, but are not limited thereto.

Such a topcoat paint is prepared by the above primer.
It is preferable to coat the cured or uncured coated surface by airless spray, air spray, electrostatic method, or the like. Viscosity during painting is 10 to 30 seconds / Forward cup # 4/20
C is preferable, and the coating film thickness is about 15 to 35 μm, especially 20 to 30 μm, based on the cured coating film on the flat portion (cut surface).
Is preferred. If necessary, it is left at room temperature or dried at 100 ° C. or lower, and then heated to 100 to 180 ° C. to crosslink and cure the coating film.

[0031]

【The invention's effect】

1) The primer coating film of the present invention has excellent adhesion to the aluminum surface.

2) The aluminum wheel coated with the primer has excellent corrosion resistance. 3) Since the primer does not contain substances that cause pollution, such as chromic acid-based rust preventive pigments, the safety is improved.

Next, examples and comparative examples relating to the present invention will be described. All parts and% are by weight in principle.

1. Sample 1) (A) Preparation of Polyurethane Resin Having Hydroxyl Group and / or Carboxyl Group (A-1): 2000 parts of polycaprolactone diol (number average molecular weight 2000), 1,4 in a four-necked flask.
-Butanediol 270 parts, dimethylolpropionic acid 402 parts, trimethylolpropanpan 40.2 parts, isophorone diisocyanate 1576 parts, toluene 3210
Parts, 3210 parts of methyl isobutyl ketone and 0.4 parts of dibutyltin dilaurate were charged, and the mixture was charged to 10 parts under a nitrogen atmosphere.
Obtained by reacting at 0 ℃ for 12 hours, solid content concentration 40
%, The viscosity was 3000 centipoise / 25 ° C.

(A-2): In a four-necked flask, 200 polycaprolactone diol (number average molecular weight 2000) was added.
0 parts, dimethylolpropionic acid 134 parts, dicyclohexylmethanediamine 346 parts, diethanolamine 7
It was obtained by charging 0 parts, 888 parts of isophorone diisocyanate, 3437 parts of toluene and 1719 parts of isopropyl alcohol and reacting them at 100 ° C. for 12 hours under a nitrogen atmosphere. The solid content concentration was 40% and the viscosity was 15,000. It was centipoise / 25 ° C.

(B) Acrylic resin (B-1): 304 parts of 2-ethylhexyl acrylate, hydroxyethyl using a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen blowing tube and a dropping device. 62 parts of acrylate, 634 parts of methyl methacrylate, 1000 parts of toluene, 500 parts of butyl acetate and 20 parts of azobisisobutyronitrile were reacted to give a solid content of 4
A hydroxyl group-containing acrylic resin solution having 0%, a viscosity of 8200 centipoise / 25 ° C., and a glass transition temperature of 40 ° C. was obtained.

(B-2): Using a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen blow-in tube and a dropping device, 317 parts of 2-ethylhexyl methacrylate and 83 of hydroxyethyl acrylate were used. Part, methyl methacrylate
634 parts, 1000 parts of toluene, 500 parts of butyl acetate and 20 parts of azobisisobutyronitrile are reacted to give a solid content concentration of 40% and a viscosity of 8200 centipoise / 2.
A hydroxyl group-containing acrylic resin solution having a temperature of 5 ° C. and a glass transition temperature of 40 ° C. was obtained.

(C) Chelate Compound (C-1): Aluminum Trisacetylacetonate (C-2): Zirconium Tetrakisacetylacetonate (D) Epoxy Resin (D-1): Epon 1001 ( E) Silane coupling agent (E-1): glycidoxypropyltrimethoxysilane (E-2): γ-methacryloxypropyltrimethoxysilane 1. Examples and Comparative Examples A primer for an aluminum wheel was prepared using the components (A) to (E). The composition ratio of each of these components is as shown in Table 1 below, and the blending amount is shown by the solid content. Mix and dilute with a solvent (equal weight solvent mixture of methyl ethyl isobutyl ketone and isopropyl alcohol) to obtain a coating viscosity of 1
It was adjusted to 0 sec / fod cup # 4/20 ° C.

[0039]

[Table 1]

3. Application Example Using a thermosetting metallic paint and a thermosetting clear paint on the above aluminum wheel primer, 3
It was painted by the coating method of the coat 2 bake system. The coating process is shown in Table 2.

[0041]

[Table 2]

Test method Adhesion: A primer, a colored paint and a clear paint were applied, and the coating film of the cut portion after heat curing was cross-cut so as to reach the base material, and a 1 mm × 1 mm gouged pattern was used. Individual pieces were made, an adhesive cellophane tape was attached to the surface, and the tape was peeled off rapidly at 20 ° C., after which the number of coating films remaining was examined. ◯ indicates 100 remaining coatings, Δ indicates 99 to 70 remaining coatings, and x indicates 69 or less remaining coatings.

Water resistance: The aluminum wheel after being coated with a primer, a coloring paint and a clear paint and cured by heating is kept at 40 ° C.
Immersed in water for 240 hours, the coated surface of the cut portion immediately after pulling was visually evaluated, and then dried at room temperature for 1 hour, and then the adhesion property of the cut part was examined by the same method as the above adhesion test. In the visual evaluation, ◯ indicates that there is no abnormality, Δ indicates that there are a few microblisters, and × indicates that there are many blister. Adhesion was evaluated in the same manner as above. Corrosion resistance: Cross-cut the coating of the cut part of the aluminum wheel, which was coated with primer, coloring paint and clear paint and heat-cured, to reach the base, and then salt spray
(JISK5400-9.1) for 1000 hours,
Then, after washing with water and drying, an adhesive cellophane tape was attached to the cross-cut portion, the tape was rapidly peeled off at 20 ° C., and then the peeling width (one side) of the coating film from the cut portion was examined. ◎: within 0.5 mm, ○: within 1 mm, △: 3 mm
Above, x shows 10 mm or more.

[0044]

[Table 3]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C09D 163/00 PKK C09D 163/00 PKK

Claims (1)

[Claims] 1. A polyurethane resin having (A) a hydroxyl group and / or a carboxyl group, (B) an acrylic resin,
A primer for an aluminum wheel containing (C) a chelate compound, (D) an epoxy resin and (E) a silane coupling agent as main components.