JPS63207870A - Acrylic base coating composition - Google Patents

Abstract

PURPOSE:To provide the titled composition composed of a specific acrylic copolymer and a hardener, effective in improving interlaminar adhesivity between a two-coat one-bake base coating film and a clear coating film and improving the beautifulness and long-term weather resistance of vehicle, etc. CONSTITUTION:The objective composition for two-coat one-bake coating contains a base paint comprising an acrylic base paint composed of (A) 40-95wt.% acrylic copolymer having a hydroxyl value of 30-80mgKOH/g and an acid value of 0.5-25mgKOH/g produced by the copolymerization of (i) 5-20wt.% 1,4-butanediol mono(meth)acrylate, (ii) 0-20wt.% monomer containing hydroxyl group, (iii) 0.2-10wt.% alpha,beta-monoethylenic unsaturated carboxylic acid, (iv) 10-70wt.% 1-4C alkyl ester of methacrylic acid, (v) 10-70wt.% 1-4C alkyl ester of acrylic acid and (vi) 0-50wt.% other copolymerizable monomer and (B) 5-40wt.% hardener.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an acrylic base paint composition for use in automobiles, etc., which requires aesthetic properties and long-term weather resistance, and more specifically relates to metallic powders and colored pigments. The present invention relates to an acrylic base paint composition suitable for use as a base paint in laminated coating by a two-coat, one-ply system of clear paint and clear paint.

[Conventional technology]

Acrylic paint compositions are characterized by their physical properties, especially gloss,
It has excellent weather resistance, chemical resistance, stain resistance, etc., and is heavily used for coating automobiles, home appliances, etc. However, conventional acrylic coating compositions have the following problems, and the industry has desired to improve them. In other words, a method of laminating a base paint and a clear paint using a 2-coat, 1-bake method is used to improve the performance of the paint film, such as gloss, weather resistance, and chemical resistance. Membrane and clear 3M! There was a problem of delamination between the films. This occurs when the baking temperature is high, or when the paint film deteriorates or progresses due to ultraviolet rays and water.

In order to improve the durability of the clear paint film, it is essential that the acrylic resin in the clear paint has a high hydroxyl value. Ten thousand,
After achieving good gloss, if the base paint contains metallic powder, in order to improve the metallic feel,
Is it better to have a lower hydroxyl value of the acrylic resin in the base paint? ! ! The adhesion between the base IIi film and the clear coating decreases, probably because the compatibility between the two species decreases.

In this way, it has been difficult to form a coating film that has excellent interlayer peeling, weather resistance, gloss, and metallic feel.

[Problems to be solved by FJA] The purpose of the present invention is to provide a base coating without impairing the inherent gloss, coating performance, or metallic feel of the acrylic paint composition when it contains metallic powder. To provide an acrylic base paint by improving glabella adhesion between a paint film and a clear paint film.

[Means for solving problems]

The gist of the present invention is to provide a base paint for use in a coating system in which a base paint containing metallic powder and/or colored pigment is applied, and then a clear paint is laminated by a two-coat, one-bake method.
The paint contains 1) a) 1,4-pmenediol mono(meth)acrylate 5-20% by weight b) hydroxyl group-containing monomer 0-20% by weight C) α,β-monoethylenically unsaturated carbonaceous
α2-102-10% by weight 92111-4 alkyl group-containing methacrylic ester 10-70
Weight e) Acrylic acid ester having an alkyl group having 1 to 4 carbon atoms 10 to ¥01 (weight f) Other copolymerizable monomers 0 to 50 weight Hydroxyl value obtained by copolymerizing saliva 30 to 5oqKOH/l and acid value α'5~25
19KOH/l acrylic copolymer 40~
95 hardening agent and 11] hardening agent 5-40% by weight
An acrylic-based paint composition consisting of.

The acrylic copolymer used in the base coating composition of the present invention contains monomers a), b), and c) having the above-mentioned specific structures.
, a), e) and f) (however, the use of b) and f) is optional) at the specific ratio described above to obtain a hydroxyl value of 30 to 80 wg KoH/ and an acid value of α5 to 25.
It must be of W KOH/f. In particular, monomer a] is a component that exhibits a remarkable effect on improving interlayer adhesion with the clear coating film, and is also a component that exhibits a remarkable effect on improving interlayer adhesion with the clear coating film. It is a component that contributes to the crosslinking reaction. If the amount of monomer a) used is less than 5% by weight, the intended effect of improving the adhesion between the base coating film and the clear coating film will not be sufficient; on the other hand, if it exceeds 20% by weight, the The gloss, metallic feel, water resistance, etc. are reduced, which is undesirable.

Examples of the hydroxyl group-containing monomer of monomer 13) include hydrodialkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. , esterification reaction products of mono-ebo-Φ compounds represented by "Cardura E" (glycidyl ester of synthetic fatty acids manufactured by Shell Chemical Co., Ltd.) with (meth)acrylic acid, 7-maric acid, maleic acid, polymerizable unsaturated groups, etc. Examples include hydroxyl group-containing monomers such as low molecular weight polyester resins. Like monomer a), monomer b) is a component that contributes to the crosslinking reaction with the curing agent, and the total amount of monomer a) and monomer b) is within a range not exceeding 20% by weight. It can be used within a range that satisfies the hydroxyl value of 30 to 7011 IKOH/l according to the invention. If the amount of monomer b) exceeds 20% by weight, the gloss, metallic feel, water resistance, etc. of the coating film will deteriorate, which is undesirable. In addition, if the hydroxyl value is less than 30 ■KOFi/, crosslinking with the curing agent will be insufficient, resulting in poor solvent resistance.
Water resistance etc. decreases, and if it exceeds 80w9KOH/l, the gloss of the coating film decreases.

Metallic feel, water resistance, etc. deteriorate, both of which are unfavorable.

The α,β-monoethylenically unsaturated carboxylic acid, which is the E component of the present invention 0), is a component that plays an important role as a catalyst for the crosslinking reaction between the copolymer and the curing agent. Acids, itaconic acid, maleic acid, heptadalic acid, heptamalic acid and alcohols (e.g. LF! Methyl alcohol, ethyl alcohol, butyl alcohol, etc.) i-mono/fulkyl esters of itaconic acid, maleic acid, heptamalic acid, etc. Can be mentioned. The amount of these α,β-monoethylenically unsaturated carboxylic acids used is 12% in the acrylic copolymer.
-10 weights must be included. If the weight ratio is less than α2, the above-mentioned effects will be insufficient, and if it exceeds 10 weight, the gloss, metallic feel, water resistance, etc. of the coating film will deteriorate, which is not preferable. A more preferable range is 1 to 5% by weight when using an amine resin as a curing agent, and 2 to 3% by weight when using incyanate greborimer.
It is.

Ninth, the acid value of the copolymer is in the range of α5 to 25 ivxoB/l. If r: less than 15 tllKOTl/, the crosslinking is insufficient and the solvent resistance, water resistance, etc. of the coating film will decrease, and if it exceeds 25 W KoH/ff, the glossiness, metallic feel, and water resistance of the coating film will deteriorate. Both of these properties are unfavorable.

The monomer d) according to the invention can be used as a base paint (
It is a component that increases the D-full pen release property, and contributes to the metallic feel, etc., as well as improving the solvent resistance of the coating film.
It also has properties that improve chemical resistance, water resistance, etc. Specific examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, 1-butyl methacrylate, and t-butyl methacrylate.

The amount of monomer (2) used is in the range of 10 to 70% by weight,
If it is less than 10% by weight, the above effect is insufficient, and if it exceeds 70% by weight, the viscosity of the copolymer will increase, and the gloss, flexibility, adhesion to the substrate, etc. will decrease; Undesirable. A more preferable range is 20 to 60% by weight.

Monomers) are fractions that contribute to improving the removability of the coating film, the adhesion to the substrate, etc. Specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, Examples include L-butyl acrylate. The amount of monomer e) used is from 10 to VO by weight.

If it is less than 10% by weight, the above effect is insufficient, and if it exceeds 70% by weight, the chemical resistance, solvent resistance, etc. of the coating film will decrease, and both are unfavorable. A more preferable range is 20 to 60% by weight.

Other copolymerizable monomers used in the present invention include:
(methacrylate esters: styrene,
Styrene 11 such as α-methylstyrene and vinyltoluene
Conductors: Polymerizable unsaturated nitriles such as acrylonitrile and methacrylate, vinyl esters such as vinyl acetate and vinyl clopionate: N-methoxymethyl (methane acrylamide, N-ethoxymethyl (meth)acrylamide, N-butoxymethyl (meth) ) N-alkoxy substituted amides such as acrylamide; epoxy group-containing monomers such as glycidyl (meth)acrylate, (meth)allyl glycidyl ether, metaglycidyl (meth)acrylic acid ester; dimethylaminoethyl (meth)acrylic acid,
Examples include basic monomers such as diethylaminoethyl (methacrylic acid).

[These other copolymerizable monomers] are used to improve quality performance in automobile paints, etc., which are the main uses of the present invention, such as weather resistance, aesthetic properties, and chemical resistance.

They are appropriately selected and used within a range that does not impair performance, taking into account solvent resistance, water resistance, removability, adhesion, etc. The range of use of other copolymerizable monomers is limited to 0 to 50% by weight, from the viewpoint of aesthetics and interlayer adhesion, which are the objectives of the present invention, but in addition, 30% by weight. Particularly preferred is the use of

The acrylic copolymer (1) in the present invention may be polymerized by any known polymerization method such as solution polymerization, bulk polymerization, emulsion polymerization, etc., but in particular, the polymer should be produced by solution polymerization. Or preferable. When using solution polymerization method,
The monomer mixture 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 inopropyl alcohol, n-7'tanol, tolueno, xylene, etc., and the polymerization initiator may be azobisin butyronitrile, benzoyl peroxide, cumene hydroperoxide, etc. Any commonly used polymerization initiator may be used.

Further, if necessary, a chain transfer agent such as 2-mercaptoethanol or n-octylmercaptan may be used.

The base coating composition of the present invention contains a curing agent (ii) such as an amino resin or an incyanate prepolymer in order to satisfy the above-mentioned quality performance t' in automobile paints and the like, which are the main uses of the present invention.

The amount of curing agent used is i) for the acrylic copolymer 1).
/1:)=95-6015-40 (weight ratio).If the amount of curing agent used is less than 5% by weight, the weather resistance of the coating film
Insufficient solvent resistance, water resistance, etc., and 40% by weight
Exceeding this level is undesirable as it affects the gloss, metallic feel, physical performance, and chemical performance of the coating film in general.

Specific examples of amine resins include alkyl etherification of aminotriacif, urea, dicyandiamide, li, and methylolated products of H-ethylene 7 urea with cyclohexano-k or alkanols having 1 to 6 R primes; Preferred are melamine resins obtained from aminotriazine, such as methyl etherified melamine resins and butyl etherified melamine resins.

In addition, when used as an amino resin gold curing agent, an external catalyst typified by para-toluenesulfonic acid, dodecylbenzenesulfone sulfone, naphthalenesulfonic acid, or their amine neutralized products is added to the above coating composition. can do.

Incyanate prepolymers are compounds containing two or more free or blocked incyanate groups in one molecule, and specifically include aliphatic compounds such as tetramethylene diincyanate, hexamethylene diincyanate, and trimethylhexane diincyanate. Incyanates,
Alicyclic diincyanates such as inphorone diincyanate and 4,4'-methylenebis(cyclohexyl incyanate), aromatic diincyanates such as xylylene diincyanate and tolylene diincyanate, and other incyanates with ethylene Adducts of polyhydric alcohols such as glycol, phlopylene gellicol, neopentyl glycol, trimethylolpropane, low molecular weight polynisful resins containing functional groups that react with incyanate groups, adducts of water, etc., biulet forms, diincyanates Similar polymers, and further these and lower monohydric alcohols,
Examples include those in which incyanate groups are blocked with a known blocking agent such as methyl ethyl ketoxime.

Further, even when incyanate prepolymer 7 is used, an external catalyst such as dibutyltin dilaurate or triethylamine can be added.

The base coating composition of the present invention may contain the following conventionally known components when it is made into a coating material. That is, brightening agents such as aluminum paste, mica, scale-like iron oxide,
Auxiliary materials such as organic pigments such as titanium oxide, carbon black, and quinacridone, non-acrylic resins such as polyester resins, epoxy resins, and cellulose resins, surface conditioners, ultraviolet absorbers, antioxidants, pigment sedimentation inhibitors, etc. Examples include additives.

The base paint composition of the present invention is produced by blending the above-mentioned components using a common blending method. Thereafter, with a known and commonly used diluting solvent, 20
The viscosity at ℃ is adjusted to be within the range of 10 to 20 seconds, and the dry film thickness is 10 to 30 μm to the base material.
Either apply directly to the base material or form a primer coating film on the base material in advance so that the dry film thickness is 10 to 100 m.
50 pm, and then allowed to stand for several minutes at room temperature (setting), for example, acrylic resin/amino resin or acrylic resin/
A clear paint containing incyanate prepolymer as a vehicle and auxiliary additives such as ultraviolet absorbers, light stabilizers, anti-sagging agents, etc. as required is diluted at 20°C using a known and commonly used diluting solvent according to 7 Ordkatupum 4. Viscosity is 13~
Adjust the drying time to within 40 seconds, then apply a layer of paint on top of the above-mentioned base coating film to a dry film thickness of 20 to 50 μm, and then leave it at room temperature for several minutes (set it). (temperature range from 60 to 180°C when amino resins are used as curing agents, and from room temperature to 140°C when using incyanate prepolymers).
It is cured for 10 to 40 minutes at a temperature range of
In this way, a two-coat, one-bake cured coating film is formed.

The present invention will be specifically explained below using examples.

It should be noted that all figures in the middle part and section of the example are based on weight unless otherwise specified.

Synthesis of acrylic copolymers B-1 to B-11 for polymer bases> As shown in Table 1, first, the solvent was heated to t-100°C, and then dropped onto the mixture of monomers and polymerization initiator for 4 hours. Then, polymerization was further carried out at the same temperature for 3 hours to obtain base acrylic copolymers B-1 to B-1114! It was completed.

Synthesis of clear copolymers 0-1 and O-2〉Table-2
As shown in Figure 1, after heating the solvent to > 1 sa °C, the mixture of monomers and polymerization initiator? , dropped over 4 hours and polymerized at the same temperature for another 2 hours to form clear copolymers 0-1 and 0-
27 synthesized 9.

[Example 1 and Comparative Example 1] Preparation of solid color base paint> Solid color base paint BP-1,2t having the following formulation was prepared.

Composition Parts by weight Acrylic yarn copolymer B-1 or B-2 *1) 160 Nippan 20 Day 5-60 *2) 33 Titanium oxide (OR-70) *3) 10 G-Xyref 20 Selonlupe acetate 20 Eji *1) In the case of copolymer B-1 or BP-1 ° In the case of B-2 or BP-2 *2) Melamine toilet fat manufactured by Mitsui Toatsu Chemical Co., Ltd. *3) 5 Hara Sangyo (a: ) Adjustment of clear paint produced> A clear paint 0F-1'i having the formulation shown below was prepared.

Parts by weight: copolymer 0-1
117 Yuban 208 Toro 0
50n rubetsun+150*1) 2
On-butanol 5 chima and 7
528 *2) α7 Sanol L
B-770*3) α4 Moda 70-
*4) 12 Note 2 *1) Shell Oil (
Aromatic hydrocarbon manufactured by Ciba-Geigy Co., Ltd. *2 Ultraviolet absorber manufactured by Ciba-Geigy Corporation *3) Light stabilizer manufactured by Sankyo (Kyu) *4) Leveling agent manufactured by Monsando Co., Ltd. Paint test> (L8sm x 70m x 300m phosphoric acid A dull steel plate that has been subjected to zinc chemical conversion treatment is further subjected to catio 7 electrodeposition and medium m coating R.
On the sanded test piece, a solution of 150'i4:3:3 (by weight) of a mixture of toluene:ethyl acetate:150'i4:3:3 (by weight) was applied with a 47-odd cup.
A solid color base paint whose viscosity was adjusted to 4 seconds was applied to the base paint so that the viscosity was 2 aμ in 2 states. After setting at room temperature for 3 minutes, use a solvent mixture of NRUBETSUN 100 and NRUBETSUN 150 at a ratio of 2:1 to +47
Viscosity I so that it is 27 seconds with an ordop! I41i Metal Ridge Metallic Clear Paint was applied, and after setting for 10 minutes, baking was performed at 140°C for 30 minutes. The evaluation results for aesthetics, adhesion, etc. are shown in Table 3. In the case of Example 1, both aesthetics and adhesion were excellent.
In contrast to Coat 1, which formed a baked yarn film, in the case of Comparative Example 1, delamination occurred between the base coating film and the clear coating film.

[Example 2.3 and Comparative Examples 2 to 6] Preparation of metallic base paint> Metallic base paint BP-3 to BP-9 with the following formulations
Adjust nine.

Assembled Part by Weight Acrylic Copolymer B-3~9*Li 160 Euvano 208 Ifi-6033 Arpeist 1109M *2) 15 Xylene 20 Note: *1)
BP-3 to 9 correspond to B-5 to B-9, respectively.

*2) CP-1 used in Example 1 was used as the aluminum paste clear paint manufactured by Toyo Aluminum Co., Ltd. Using the metallic base paint and clear paint t thus obtained, a 2-coat, 1-bake yarn metallic coating film was formed using the same steps as in the case of solid color in Example 1. The evaluation results are shown in Table 4, and in the case of Examples, aesthetics.

A two-coat, one-bake yarn coating with good adhesion was completely formed, whereas Comparative Examples 2.3 had good adhesion, Comparative Example 4 had good aesthetics, and Comparative Example 5 had good cosmetics and repainting. Comparative Example 6 had poor aesthetics and coating performance, and lacked commercial value.

[Example 4 and Comparative Example 7] Preparation of metallic base paint> Metallic base paint BP-10 with the following formulation,
BP-11 was adjusted.

Composition Part by weight Acrylic copolymer E-10, B-11*1) 16
0 Sumidule N-75*2) 25 Alpeist 1109M 15 Xylene
20 Note: *1) BP-1
0 and 11 correspond to B-10 and 11.

*2) Preparation of Sumitomo Chemical Group Incyanate Prepolymer Clear Paint> A clear paint 0F-21ii11 having the formulation shown below was prepared.

Composition Part by weight Copolymer C-2
120 Sumidur N-7556 Xylene 20 Chimavi 73
28 I17 Sanol LS-
770 (L4 Moda 70-02) The metallic base paint and clear paint thus obtained were mixed on the test piece at a ratio of toluene/ethyl acetate/solben $150'i6:!1:1 (weight ratio). Metallic base material whose viscosity was adjusted to 13 seconds with a +47 odor cup using a solvent was heated to 20 in two stages.
It was painted to be μ. After setting for 3 minutes at room temperature, toluene/xylene/n-butyl acetate = 50
/ 50 / 20 (by weight) with a solvent mixed with a 47 ord cup for 15 seconds. Apply clear paint to a thickness of 35μ, set for 10 minutes, and bake for AO'CXSO minutes. went.

The evaluation results for aesthetics, adhesion, etc. are shown in Table 5. In the case of Example 4, a 2-coat, 1-bake coating film with excellent aesthetics and adhesion was formed, whereas Comparative Example 7 In the case of
t- occurred.

Table -2 *1] Aromatic hydrocarbon table manufactured by Shell Oil Co., Ltd. -6 *1) 8-stone regular gasoline, room temperature x 24 hour immersion, appearance evaluation *2) 10%-H, So4 spot Room temperature x Appearance judgment after 24 hours *3) Appearance judgment after immersion in 50℃ warm water for 2 weeks *4)
Repair paintability in case of m membrane defects such as bumps etc. 2 coats → 160
℃ x 30 minutes → 2 coats → 160℃ x 30 minutes → Perform a cellophane peeling test on 7 rows and display the adhesion *5) Perform a cellophane peel test on the grains and display the adhered heavy metal *6) Sunshine W-0-M After 2000 hours , 5
Appearance after 240 hours of humidity resistance at 0C, 98 Excellent RH *7) *After conducting the appearance evaluation of *6), a score of "4" was displayed in the cellophane tape peel test for seven runs *1) 8-stone regular gunrin room temperature x 24 hours After dipping and pulling up, appearance judgment *2) 10%-H, 130, spot room temperature x 24
Appearance judgment after hours *5) Appearance judgment after immersion in 50°C warm water for 2 weeks and lifting *4]
Repair paintability in case of paint film defects such as bumps etc. 2 coats → 160
°C x 30 minutes → 2 coats → 160°C x 30 minutes → Perform a cellophane stripping test and display the adhesion rate *5) Perform a stripe cellotape peel test and display the adhesion rate *6) Sansha (N W-0-M 2000) 50 hours later
Appearance after 240 hours of humidity resistance at 98% RE at 98% RE *7)) After evaluating the appearance of k6), a cellophane tape peeling test was performed and the adhesion force T-display Table -5 *1] Nisseki regular gasoline room temperature x 2 Appearance judgment after immersion in 50°C warm water for 2 weeks *4)
Repair paintability in case of paint film defects such as spots 2 coats → 1
0°C x 50 minutes → 2 coats → 80°C x 30 minutes → Carry out a cellophane tape peel test and display the adhesion rate *5) Carry out a cellophane tape peel test and display the adhesion rate *6) Sunshine W-0-M After 2000 hours , 5
Appearance after 240 hours of humidity resistance at 0°C x 98cm RH *7) After evaluating the appearance of *6), a cross-cut Sellotape peel test was performed and the adhesion rate was displayed. [Effects of the Invention] As detailed above, the present invention The acrylic base paint composition of the invention maintains excellent aesthetic properties when a base clear paint film is formed using a two-coat, one-paste method, and has excellent layering properties between the base paint film and the clear paint film. The effect is extremely large.

Claims (1)

[Claims] In a base paint used in a painting system in which a base paint containing metallic powder and/or colored pigment is applied, and then a clear paint is laminated by a two-coat, one-ply method,
The coating material contains i) a) 5-20% by weight of 1,4-butanediol mono(meth)acrylate, b) 0-20% by weight of a hydroxyl group-containing monomer, and c) 0.0% by weight of α,β-monoethylenically unsaturated carboxylic acid. 2～
10% by weight d) 10-70% by weight of a methacrylic ester having an alkyl group having 1 to 4 carbon atoms e) 10-70% by weight of an acrylic ester having an alkyl group having 1 to 4 carbon atoms f) Others that can be copolymerized Acrylic copolymer 40 with a hydroxyl value of 30 to 80 mgKOH/g and an acid value of 0.5 to 25 mgKOH/g obtained by copolymerizing 0 to 50% by weight of monomers of
-95% by weight and ii) 5-40% by weight of a curing agent.