JPH02298384A - Method for forming film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for forming a coating film, and more specifically, to a method for forming a coating film, and more specifically, to a method for forming a coating film, and more specifically to a method for forming a coating film.
action injection molding)
Suitable for relatively flexible plastic materials such as , ABS polyurethane, polypropylene, and polycarbonate.
The present invention relates to a method for forming a coating film having excellent water repellency, stain resistance, low temperature bending resistance, gloss retention during outdoor exposure, and stain resistance.

[Conventional technology]

Acrylic thermosetting paints that use amino resin as a curing agent are
Its excellent weather resistance, water resistance, solvent resistance, chemical resistance and -i'! ! Since it can be treated as a fee, it can be used for automobiles, home appliances,
It is used in a wide range of fields such as building materials, and is particularly suitable as a top coat for the outer panels of automobile bodies.

Recently, soft plastic materials such as plastics and elastomers have been increasingly used for bumpers, fenders, etc. in response to the needs for diversification of vehicle body shapes, weight reduction, and improved impact resistance.

Paints that form a flexible coating are used for these soft plastic materials, and the coating must have sufficient flexibility even at low temperatures of -10°C to 40'C. . Specifically, these soft plastic materials need to have a certain degree of flexibility compared to steel plates from room temperature to low temperature ranges of -10°C to 40°C. When deformation and impact are applied to the material, the coating film follows the deformation and is required to have no damage such as cracks or cracks as an essential performance.

Acrylic urethane and polyester urethane paints, which have been conventionally used as paints for these plastic and elastomer materials, generally have excellent low-temperature performance.
Since it is handled as a two-component curing paint, its handling is complicated.

In addition, coating films using thermosetting acrylic paints using amino resin as a curing agent generally have poor flexibility, and it is necessary to significantly lower the glass transition temperature of the acrylic copolymer to improve the resulting flexibility. However, a problem arises in that its solvent resistance and stain resistance rapidly decrease.

[Problem to be solved by the invention]

It is an object of the present invention to solve the above-mentioned problems, maintain the properties of an acrylamino resin thermosetting coating film such as weather resistance and cosmetic properties, and improve impact resistance at low temperatures, water resistance and The present invention provides a method for forming a coating film with excellent stain resistance.

[Means to solve the problem]

That is, the gist of the present invention is that after applying a thermosetting base coat paint containing metallic powder or coloring pigment, a specific thermosetting clear coat paint is then overcoated using a wet-on-wet method. After that, in the method of forming a coating film in which both coating films are simultaneously heated and cured, as the above-mentioned base coat paint (1) (a) 10 to 40% by weight of a hydroxyl group-containing (meth)acrylic acid ester (b) a carboxyl group-containing vinyl monomer 0.2～
10% by weight (c) A (meth)acrylic ester represented by the general formula (1) (wherein R1 is a hydrogen atom or a methyl group, and n represents an integer of 1 to 6) 30 to 89.
8% by weight (d) Hydroxyl value 40-80111g obtained by copolymerizing 0-30% by weight of other copolymerizable vinyl monomers
KOH/g and acid value 0.5 to 30 mg KOH/g, mainly composed of 60 to 90% by weight of acrylic copolymer with glass transition temperature of -40°C to 10'C and 10 to 40% by weight of amino resin. (3) (e) 5 to 60% by weight of (meth)acrylic acid ester containing a fluoroalkyl group or perfluoroalkyl group (f) At least one type represented by general formula (IF) 10 to 60% by weight of (meth)acrylic acid ester containing a hydroxyl group ((a) 0.2 to 10% by weight of a vinyl monomer containing at least one kind of carboxyl group, sulfonic acid group, or phosphoric acid group) (c) General The acrylic copolymer (A) used in the base coat paint used in the practice of the present invention is 15 to 70% by weight of (meth)acrylic acid ester represented by formula (III), which improves the bending resistance of the paint film at low temperatures. Taking into consideration, the glass transition temperature is 140°C~1
It is preferable to select monomers so that the temperature is 0°C. Paints made using acrylic copolymers with a glass transition temperature of less than -4°C will have poor solvent resistance and weather resistance; Coatings made from paints containing such compounds are unfavorable because their bending resistance at low temperatures decreases. Further, the glass transition temperature of the acrylic copolymer can be determined from the glass transition temperature (Tg) of a known homopolymer using the following formula.

In addition, the acrylic copolymer (A) has a hydroxyl value of 40 from the viewpoint of adhesion between the base coat and the clear coat.
A hydroxyl group-containing vinyl monomer is copolymerized so that the amount is in the range of ~80 ■KOH/g. In the case of an acrylic copolymer (A) containing less than 10% by weight of a hydroxyl group-containing vinyl monomer, the crosslinking density of the cured coating film due to the crosslinking reaction between the copolymer and the amino resin is low, and sufficient coating performance cannot be obtained. In addition, an acrylic copolymer copolymerized with more than 40% by weight of a hydroxyl group-containing vinyl monomer has an excessively high solution viscosity.
This is not preferable because the water resistance of a cured coating film formed from a coating material containing the acrylic copolymer is reduced.

Examples of this hydroxyl group-containing (meth)acrylic ester include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Hydroxyalkyl (meth)acrylates, "Cardura E" (Shell Chemical)
There are esterification products of monoepoxy compounds and (meth)acrylic acid, fumaric acid, or maleic acid, such as glycidyl esters of synthetic fatty acids, and polyesters with polymerizable unsaturated groups. Plaxel FMI, Plaxel FA-2, Plaxel FM2, Plaxel FM6, etc. manufactured by Union Carbide, Tone M-100 manufactured by Union Carbide, Blenmar PP manufactured by NOF ■
-1ooo etc. are mentioned.

The carboxyl group-containing vinyl monomer in item (1) and (b) above plays an important role in improving the affinity between the acrylic copolymer (1) and pigments and as a catalyst for crosslinking reactions when used in base coat paints. A polymerizable monomer having one or more carboxyl groups, such as α,β-monoethylenically unsaturated carboxylic acid, specifically acrylic acid,
Mention may be made of methacrylic acid, itaconic acid, maleic acid and fumaric acid, as well as monoalkyl esters of these acids (e.g. monomethyl ester, monoethyl ester, monobutyl ester, etc.), which can be added to the acrylic copolymer (A). They can be used singly or in combination of two or more so that the acid value is 0.5 to 30 KOII/g.

If the acid value is less than 0.5 mgKOH/g, the crosslinking density of the cured coating film will be low, the solvent resistance will be low, and 30■KO
If it exceeds H/g, water resistance decreases. These α and β
- the amount of monoethylenically unsaturated carboxylic acid is 0.2% by weight;
If it is less than 10% by weight, the above-mentioned effects will be insufficient, and if it exceeds 10% by weight, the solution viscosity of the acrylic copolymer (1) will increase and the water resistance will decrease, which is not preferable. The preferred range of this amount is 0.5 to 5% by weight.

The (meth)acrylic acid ester of general formula (1) described in item (1)(c) above is an essential component from the viewpoint of cosmetic properties, weather resistance, and flexibility, and specific examples include methyl (meth)acrylate. , ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate,
Examples include isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, and the like.

Other copolymerizable vinyl monomers mentioned in (1) and (5) above include styrene derivatives such as styrene, α-methylstyrene, and vinyltoluene; polymerizable unsaturated nitriles such as acrylonitrile and methacrylonitrile; Vinyl esters such as vinyl acetate and vinyl propionate; N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-butoxymethyl (meth)
N-alkoxy-substituted amides such as acrylamide; epoxy group-containing monomers such as nigericidyl (meth)acrylate, (meth)acrylic glycidyl ether, metaglycidyl (meth)acrylic acid ester; dimethylaminoethyl (meth)acrylic acid, diethylaminoethyl (meth)acrylate; )
Basic polymers such as acrylic acid: (meth)acrylic acid esters having alicyclic or aromatic hydrocarbon substituents such as phenyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, and cyclohexyl acrylate, 2-ethylhexyl ( Examples include (meth)acrylic acid esters such as meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, and stearyl (meth)acrylate, and these can be used as necessary.

In the present invention, the acrylic copolymer (1) contained in the base coat paint can be obtained by any known method such as solution polymerization, bulk polymerization, emulsion polymerization, etc., but especially by solution polymerization. Preferably, it is a polymer. In the case of solution polymerization, the mixture of monomers is copolymerized in the presence of an organic solvent and a polymerization initiator.

The organic solvent used may be a commonly used organic solvent such as isopropyl alcohol, n-butanol, toluene, or xylene, and the polymerization initiator may also be abbisisobutyronitrile,
Commonly used polymerization initiators such as benzoyl peroxide and cumene hydroperoxide may be used. Also, if necessary, 2-
Chain transfer agents such as mercaptoethanol and n-octylmercaptan can be used.

In the base coat paint used in carrying out the present invention, if the amino resin content is less than 10% by weight, the cured coating film will have a low crosslinking density and sufficient performance will not be obtained, and if it exceeds 40% by weight, the water resistance of the cured coating film will be poor. This is not preferable because flexibility decreases. The preferred range of the amount of amino resin is 15 to 30% by weight.
It is. This amino resin is produced by, for example, methylolizing aminotriazine, urea, dicyandiamide or N,N-ethylene urea, and producing cyclohexanol or carbon atoms of 1 to 1 carbon atoms.
Preferred are methyl etherified melamine resins, butyl etherified melamine resins, etc. obtained by alkyl etherification with alkanols of No. 6, particularly aminotriazine.

In the present invention, the acrylic copolymer (B) used in the clear coat paint has a hydroxyl value of 50 to 150 mgKOH from the viewpoint of solvent resistance, water resistance, and weather resistance of the resulting coating film.
The hydroxyl group-containing vinyl monomer can be selected so that the amount is 7 g. If the hydroxyl value is less than 50 to 011/g, the crosslinking density due to the crosslinking reaction between the acrylic copolymer (B) and the amino resin will be too low, making it impossible to obtain satisfactory coating performance. If it exceeds this, the solution viscosity of the acrylic copolymer (B) will increase, the cosmetic properties will decrease, and the water resistance of the cured coating film will decrease, which is not preferable.

In addition, the glass transition temperature of the acrylic copolymer (B) is determined by adjusting the amount of monomers copolymerized so that the glass transition temperature is 140°C to 10°C, taking into consideration the bending resistance of the coating film at low temperatures. You should choose your body. For acrylic copolymers with a glass transition temperature of less than 140°C, the solvent resistance of the resulting coating film,
A coating film made from an acrylic copolymer with reduced weather resistance and a temperature exceeding O''C is undesirable because of reduced bending resistance at low temperatures.

The acrylic copolymer (B) constituting the clear coat paint used in the present invention is selected from the acrylic copolymer (B) shown in item (3) (e) above for the purpose of improving the stain resistance and water clarity of the resulting paint film. A (meth)acrylic acid ester having a fluoroalkyl group or a perfluoroalkyl group is copolymerized. Specifically, a fluorocarbon ester having 1 or more carbon atoms, preferably 2 to 18 carbon atoms, substituted with a fluorine atom is copolymerized. Represents a compound having an alkyl group or a perfluoroalkyl group in its side chain, and is used in an amount of 5 to 60% by weight based on the total monomer component of the acrylic copolymer (B). An acrylic copolymer containing less than 5% by weight of alkyl (meth)acrylic acid ester cannot form a coating film with sufficient stain resistance and water repellency.
On the other hand, an acrylic copolymer copolymerized with 60% by weight or more of Motsumar is difficult to form into a coating film with excellent adhesion to the undercoat coating and re-repairability.

A specific example of the 7-mer is C[1z=CtlCOO
CHzCF:+, CHz=C(cfh)COOCHz
Ch, CHz=CHCOOCH*ChCHFz, CHl
=C(cfti)COOCHzCFzCHPz, CH
! =CHcOOcH(cL)CzFs, cHz=c(c
lh)COOCH(cHl)C,Ps,CHg=CHC
00C) I(ch)z, C1(t = C(cll 5
)COOCII (cF s) z, CHz=C)IC
OOCHzCFtCHFCh, C11t =C(ctl
a) COOCHzCFtCllFCFi, CElt=C
HCOOC1l(cH3)C3F? , CI(t=c(c
Hx)COOCH(cHs)Csh, CHz=CHC0
0CII*(cFz)J.

CHx=C(cHs)COOCfh(cFt)J, C
Hz=CIICOOC1hCtF+s, CH1 bow HCO
OCHgctFs, CHx=C(cHi)COOCzF
s, CHz = CllCOO(cfl□)z(ch)4
F.

C11z = C(cH:1)COO(c11ri 2 (
cF2) aF.

CHl = CHC00 (cL) 2 (ch) 6F.

C11t=C(cH3)Coo(cHlri!(cFri6
F.

CHx=CflCOOCHICaF+7, CJ=C(c
Hz) COOCHzCaF+7, CHz = CHCO
OCHtC+ l)F! l, Ctb = C(c
H:+) COOCII zCloF z +, CH,=
CFI COCoo(cF1++CaF+t, CL
=C(cHl3)COO(cH2) l +CaF+
7 or various acrylic esters or methacrylic esters having a fluoroalkyl group or perfluoroalkyl group; 2-hydroxyethyl (meth) with fluorinated carboxylic acids or their acid chlorides with linear or branched side chains.
Acrylate or 2-hydroxypropyl (meth)
It can be obtained by a known synthesis method such as reacting a hydroxyl group-containing vinyl monomer such as acrylate. These can also be used singly or as a mixture of two or more.

(3) The amount of copolymerization of the hydroxyl group-containing (meth)acrylic acid ester shown in (f) into the acrylic copolymer (B) is 5
~60% by weight. The amount of copolymerization of the heptamer is 5
If the acrylic copolymer is less than 60% by weight, the crosslinking density of the cured coating film due to the crosslinking reaction with the Ami71 resin will be too low and satisfactory coating performance cannot be obtained; Polymers are not preferred because their solution viscosity becomes too high and, furthermore, the water resistance of the cured coating film decreases. Examples of the hydroxyl group-containing vinyl monomer shown in (3)(f) above include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,
Hydroxyalkyl (meth)acrylate neck such as 3-hydroxypropyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; adducts of 2-hydroxyethyl (meth)acrylate and ethyl oxide and 2-hydroxyethyl (meth)acrylate Adduct of acrylate and propylene oxide: 2-hydroxyethyl (meth)
Adduct of acrylate and T-butyrolactone and 2-
Adducts of 2-hydroxyethyl (meth)acrylate and organic lactones, such as adducts of hydroxyethyl (meth)acrylate and ε-caprolactone, 2-hydroxyethyl (meth)acrylate or 2-hydroxypropyl (meth)acrylate Examples include dimers and trimers of. Specific examples of the hydroxyl group-containing (meth)acrylic acid ester represented by the general formula (n) include Plaxel FMI, Plaxel FM2, and Plaxel Luxel FM6 manufactured by Daicel Chemical ■; Blenmar PE-9 manufactured by NOF Corporation;
0, Fibernmar PH-350, Fibern-pp
-1000, etc.; Acrylic oligomer, HE-20, IIP-20, etc. manufactured by Nippon Shokubai Kagaku (■); Tone M-100, manufactured by Union Carbide.

The vinyl monomer containing a carboxyl group, sulfonic acid group or phosphoric acid group shown in items (3) and (6) above is added so that the acid value of the acrylic copolymer (B) is 2 to 40 mg and 0.87 g. They can be used alone or in combination of two or more.

(3) The monomer shown in (g) has one or more carboxyl group, sulfonic acid group, or phosphoric acid group in the molecule, such as acrylic acid, methacrylic acid, itaconic acid,
citraconic acid, maleic acid, fumaric acid, crotonic acid,
Itaconic acid monobutyl ester, itaconic acid monomethyl ester, itaconic acid monooctyl ester, maleic acid monobutyl ester, maleic acid monomethyl ester, maleic acid monooctyl ester, 2-sulfoethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid , vinylbenzenesulfonic acid, Kasema-PM-21 manufactured by Nippon Kayaku ■, and Light Ester PM manufactured by Kyoeisha Yushi ■. The usage amounts of vinyl monomers having these acidic substituents are (3) (e), (f), (
9), (c), 0) based on the total weight of each seven points
．． It is 2 to 10% by weight. If it is less than 0.2% by weight, the reaction rate with the curing agent will be slow and sufficient coating performance will not be obtained, and if it exceeds 10% by weight, the water resistance of the coating will decrease, which is not preferred.

The (meth)acrylic acid ester represented by item (3) (c) above is an essential component in terms of solvent resistance, towability, cosmetic properties, and weather resistance, and is used in a range of 15 to 70%. However, if the amount used is less than 15% by weight, cosmetic properties and weather resistance will decrease, and if it exceeds 70% by weight, hardness and solvent resistance will decrease, which is not preferable. Specifically, n-butyl acrylate, n-butyl methacrylate, i-butyl acrylate, i-butyl methacrylate, (-butyl acrylate, t-butyl methacrylate, 5ec-butyl acrylate, 5ec-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, lauryl acrylate, lauryl methacrylate, tridecyl methacrylate, tridecyl acrylate, cetyl methacrylate, cetyl acrylate, stearyl methacrylate, stearyl acrylate, benzyl methacrylate, benzyl acrylate, phenyl methacrylate, phenyl Acrylate, FA-511A manufactured by Hitachi Chemical, FA
-513M and the like.

The other copolymerizable vinyl monomers mentioned in item (3)(i) may be used as necessary in amounts within a range that does not impair the cosmetic properties that are a feature of the present invention. Specific examples include styrene, α-methylstyrene, etc. , styrene derivatives such as vinyltoluene; polymerizable unsaturated nitrites such as acrylonitrile and methacrylaterile; vinyl esters such as vinyl acetate and vinyl propionate; N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth) N- such as acrylamide, N-butoxymethyl (meth)acrylamide, etc.
Alkoxy-substituted amides; Epoxy group-containing monomers such as glycidyl (meth)acrylate, (meth)allyl glycidyl ether, metaglycidyl (meth)acrylic acid ester; dimethylaminoethyl (meth)acrylic acid, diethylaminoethyl (meth)acrylic acid, etc. Basic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and the like. The polymerization method for the acrylic copolymer (B) contained in the clear coat paint is similar to the polymerization method for the acrylic copolymer (A) contained in the base coat paint, but especially solution polymerization. Preferably legal.

The clear coat paint of the present invention contains an amino resin as a curing agent in order to satisfy the quality performance in the automotive paint, which is the main application. If the amount of amino resin is less than 10% by weight, the crosslinking density of the cured coating film will be low, resulting in insufficient weather resistance, solvent resistance, water resistance, etc. of the coating film, and if it exceeds 50% by weight, the cured coating film will be insufficient. This is undesirable because it causes deterioration in physical and chemical properties, including glossiness and metallic feel. Specific examples of this amino resin are the same as those described for the amino resin contained in the base coat paint.

Furthermore, when an amino resin is used as a curing agent, an external acid catalyst such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, or their amino neutralized products is added to the clear coat paint. can be used.

The base coat paint in the present invention includes known aluminum pastes, mica, scaly iron oxide, and other brightening agents that can be commonly used in paint production; pigments such as titanium oxide, carbon black, quinacridone, and cyanine blue; polyester-based Resins other than acrylic resins such as resins, epoxy resins, and cellulose resins; and surface conditioners, ultraviolet absorbers,
Auxiliary additives such as antioxidants and pigment anti-settling agents can be selected as necessary and added by common compounding methods.

The present invention will be explained in more detail with reference to Examples below.

〔Example〕

The present invention will be explained below with reference to Examples.

Aku L fire stirrer attached to Baseco S,
4 toluene in a container equipped with a temperature control device or condenser.
0 parts by weight and ton parts of n-butanol were charged. The contents of the vessel were heated with stirring to raise the temperature to 90°C. Next, a solution of composition (1) shown in Table 1 was added to
After dropping for 30 minutes, a solution consisting of 0.6 parts by weight of benzoyl peroxide and 20 parts by weight of toluene was added dropwise for 30 minutes. The reaction solution was further stirred and heated at 100°C for 2 hours to increase the conversion rate to resin, and then 30 parts by weight of toluene was added to terminate the reaction. The resulting acrylic copolymer solution (non-volatile).

The acrylic copolymer contained in this varnish, which contains 50% by weight of acrylic resin varnish N), satisfies the requirements for the acrylic copolymer (A) in the present invention.

The weight average molecular weight of this copolymer was 80.000.

Next, in place of the composition (1), the composition shown in Table 1 (
Perform the reaction using the solution of 2) in exactly the same manner as above,
An acrylic copolymer solution (nonvolatile content: 50% by weight) was obtained. This is referred to as acrylic resin varnish (II). The monomer composition of the acrylic copolymer contained in this varnish does not meet the requirements for the acrylic copolymer (A). The weight average molecular weight of this copolymer was 90.000.

Table 1 Base coat ・ LjlJl Each material in the proportion shown in Table 2 was placed in a stainless steel container, thoroughly stirred, and the viscosity was adjusted with a diluent mixed solvent to produce base coat paints B-1 to B-3. did.

Table 2 Note) *1) Butylated melamine resin manufactured by Mitsui Toatsu Chemical ■ (
Non-volatile content: 60%) *2) Aluminum paste made by Toyo Aluminum ■3) Red pigment umbrella made by Tosoh ■4) The mixed solvent for dilution has the following composition.

Aromatic Petroleum Derivatives manufactured by Esso Co., Ltd. A polymerization reaction was carried out in the following procedure for each mixture having the six types of monomer compositions shown in Table 3.

First, 56.6 parts by weight of xylene was charged into a container equipped with a stirrer, a temperature controller, and a condenser, and heated while stirring to raise the temperature to 120°C. Next, 2 parts by weight of azobisisobutyronitrile and 2 parts by weight of t-butylperoxyisopropyl carbonate were added to 100 parts by weight of the seven-mer mixture listed in Table 3, and the mixture was allowed to drip over 3 hours. Next, 0.1 part by weight of azobisisobutyronitrile was added four times at 30 minute intervals.

After stirring and heating at 120"C for another 2 hours to increase the conversion rate to resin, 10 parts by weight of n-butanol was added to terminate the reaction. The six types of acrylic copolymer solutions obtained The viscosity and nonvolatile content of each acrylic copolymer and the acid value of each acrylic copolymer were as shown in Table 3.

Clear coat paints P-1 to P were prepared using the above six types of acrylic copolymer solutions and the paint formulations shown in Table 3.
-6 was manufactured.

Among these clear coat paints, the acrylic copolymer is the acrylic copolymer (B) in the present invention.
Paints P-1 to P-4 meet these requirements.

Notes: 1) Propylene oxide adduct to 2-hydroxypropyl methacrylate manufactured by NOF ■ 2) C-caprolactone adduct to 2-hydroxyethyl acrylate manufactured by Union Carbide 3) 2- manufactured by Daicel Chemical ■ ε-caprolactone adduct to hydroxyethyl methacrylate 4) The glass transition temperature (Tg) of the acrylic copolymer was calculated using the following formula.

Umbrella 5) Measured at 25°C using a Gardner-Holdt foam viscometer.

Liao 6) Acrylic surface conditioner manufactured by Monsanto Company 7) Butylated melamine resin manufactured by Dainippon Ink Chemical (non-volatile content 6)
0%) *8) Measured at 20°C using an Nα4 force cup.

Examples 1 to 5 and Comparative Examples 1 to 5 The diluted base coat paints listed in Table 2 were applied to a dry film thickness of 20 μ, and after being left for 5 minutes, the diluted clear coat paints listed in Table 3 were applied. was applied wet-on-wet to a dry film thickness of 30μ. After leaving the undried overcoated film at room temperature for 10 minutes, it was heated at 120°C x 30
It was dried under curing conditions for 10 minutes to form a coating film.

As is clear from the results shown in Table 4, the coating films obtained in Examples exhibit excellent performance in terms of gloss, water repellency, bending resistance at low temperatures, stain resistance, and weather resistance. In the case of a comparative example that deviates from the range specified by , the water repellency, stain resistance, low temperature bending resistance, etc. are lower than those of the example.

Note) l) 60″C digital angle gloss meter manufactured by Suga Test Instruments
Measured using lGV-40.

2) Place pure water on the painted surface with a syringe and measure the contact angle with a microscope. (Unit is degree) 3) At -20℃, 1
Coated surface condition when bent at 80 degrees 4) After immersing in a 5% sulfuric acid aqueous solution at room temperature for one day, the appearance was visually judged.

5) Visually judge the appearance after immersing the mouth surface in regular gasoline at room temperature for 1 day6 6) Visually judge the appearance after immersing in 40°C hot water for 10 days.

7) QUV accelerated weather resistance manufactured by Q Panel was evaluated for 1000 hours.

8) A black marker was applied to the painted surface, and after leaving it at room temperature for 24 hours, gauze was dipped in n-butanol and wiped off, and the erasability was evaluated.

〔Effect of the invention〕

The method for forming a coating film of the present invention provides a coating film with excellent performance such as gloss, water clarity, low temperature flexibility, and weather resistance. Regarding the method of forming a coating film, it is particularly useful for soft plastics for automobiles.

Claims (1)

[Claims] After applying a thermosetting base coat paint containing metallic powder or colored pigments, then applying a thermosetting clear coat paint in a wet-on-wet manner, then applying both paints at the same time. In the method for forming a coating film that is heated and cured, as the above-mentioned base coat coating material (1) (a) hydroxyl group-containing (meth)acrylic ester 1
0 to 40% by weight (b) Carboxyl group-containing vinyl monomer 0.2 to 10
Weight% (c) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R^1 is a hydrogen atom or a methyl group, and n represents an integer from 1 to 6.) Represented by (meth)acrylic acid ester 30-89.
8% by weight (d) Hydroxyl value 40-80mgKO obtained by copolymerizing 0-30% by weight of other copolymerizable vinyl monomers
Acrylic copolymer (A) 6 with H/g and acid value 0.5 to 30 mgKOH/g, glass transition temperature -40°C to 10°C
(3) (e) (meth)acrylic containing a fluoroalkyl group or a perfluoroalkyl group; Acid ester 5-60
Weight% (f) 10 to 60% by weight of at least one hydroxyl group-containing (meth)acrylic acid ester represented by general formula (II) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (II) In the formula, R^2 is a hydrogen atom or represents a methyl group, and R^3 represents an organic substituent represented by the following general formula (III), (IV), (V) or (VI). -R^4-OH(III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(IV) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(V) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(VI) In the formula , R^4, R^5 represent an alkylene group having 1 to 8 carbon atoms with a linear or branched structure, and R^6, R^7, R^8 and R^9 represent a hydrogen atom or a methyl group. , l represents an integer of 2 to 5, j represents an integer of 2 to 10, k represents an integer of 1 to 7, and m represents an integer of 1 to 3, respectively. (g) 0.2 to 10% by weight of a vinyl monomer containing at least one type of carboxyl group, sulfonate, or phosphoric acid group (h) 15 to 15% of (meth)acrylic acid ester represented by general formula (III) 70% by weight ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) In the formula, R^1^0 represents a hydrogen atom or a methyl group,
R^1^1 represents a hydrocarbon substituent having 4 or more carbon atoms. (i) Hydroxyl value 50-150 mgK obtained by copolymerizing 5-50% by weight of other copolymerizable vinyl monomers
Acrylic copolymer (B) 5 having an OH/g and acid value of 2 to 40 mgKOH/g and a glass transition temperature of -40°C to 0°C
0-90% by weight and (4) amino resin 10-50% by weight
A method for forming a coating film, characterized by using a coating film containing.