JP2001089698A - Coating composition, metallic-base coating and coating film formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition, a metallic base coating and a coating method capable of doing 2 coats/1 bake coating-finishing which give good appearance (metallic feeling, smoothness, glass and the like), being excellent in quality (chemical resistance, adhesion between layers, water resistance, weather resistance and the like) and usable for metallic coating and nonmetallic coating. SOLUTION: After coating the surface of a substrate with a metallic base coating prepared by compounding a metallic pigment into a coating composition comprising a organic solvent (S) and a cellulose ester-modified vinylic copolymer (I), as a vehicle component, which is obtained by copolymerizing 5-40 wt.% of a cellulose ester derivative (a) obtained by ring-opening graft polymerization of cyclic esters on a cellulose ester having hydroxy groups with 95-60 wt.% of a vinyl monomer compound (b) (total of (a) and (b) is 100%), a transparent topcoat of a thermoplastic resin is applied in an uncured state followed by baking the coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a metallic base paint, a metallic paint, and a method of applying the same. More specifically, the present invention relates to a metallic paint having a good appearance and quality by a two-coating and one-time baking type metallic coating. The present invention relates to a novel composition for a metallic base paint used for forming a coating film, a metallic base paint, and a method for applying the same.

[0002]

2. Description of the Related Art In recent years, metallic coating by a two-coat, one-baking method, that is, a two-coat, one-bake method, has attracted attention as a coating method for providing excellent appearance and quality, and has been widely used for coating automotive bodies and the like. It's being used.
Also, various studies have been conducted to improve the quality. The metallic base paints used for these contain metal powders such as aluminum powders having different shapes and particle diameters compared to ordinary pigments in the paints. In this metallic base paint, the metallic feeling and color tone of the base coat change depending on the arrangement of the metal powders in the base coat when the coat is formed. In order to obtain a good appearance and quality or finish, after the metallic base paint is applied and before the overcoating transparent paint is applied, the movement of the metal powder in the base coating film has stopped. It must be fixed in the membrane. Therefore, conventionally,
Dilute a relatively high molecular weight acrylic resin as a vehicle with a highly volatile solvent and use a metallic base paint with a metallic pigment added to it. A method of fixing the movement of the metal powder by utilizing the increase in viscosity has been adopted.

However, in this method, the viscosity rise after application is not so large, and the movement of the metal powder is fixed slowly, so that when the topcoat is applied, the metal powder moves again,
There are drawbacks such as the color tone of the coating film changing and being cheap. Meanwhile,
Japanese Patent Publication No. 49-38005 discloses that when a cellulose acetate butyrate (hereinafter referred to as "CAB") is blended with this type of metallic base paint, the paint at the time of application and the coating film after application are mixed. It is disclosed that the viscosity increase occurs much more rapidly than that without CAB, and a metallic coating film having good appearance and quality can be formed. However, CAB generally has poor compatibility with an acrylic resin, and thus causes inconveniences such as clouding of a coating film during storage or occurrence of bumps in a coating material, and has a problem in storage stability.

In order to avoid such disadvantages, it is necessary to use an acrylic resin having good compatibility with CAB, but to obtain an acrylic resin having good compatibility with CAB, There are restrictions on the composition of the monomers constituting the resin, and among them, the blending of the styrene monomer is greatly restricted.
% By weight is the practical upper limit, and practically little styrene monomer is used. On the other hand, on the other hand, styrene monomer as a component of the acrylic resin is used for the interlayer adhesion between the metallic base coat and the top coat transparent coat, the pigment dispersibility of the metallic base paint, the water resistance and weather resistance of the entire metallic paint system, etc. It is known that the above-mentioned quantitative restriction on the amount of the styrene monomer has a considerable adverse effect on these properties. Then, in order to ensure the storage stability, it was the fact that the above properties such as interlayer adhesion, pigment dispersibility, water resistance and weather resistance had to be sacrificed.

[0005]

An object of the present invention is to provide good appearance (metallic feeling, smoothness, gloss, etc.) and excellent quality (chemical resistance, interlayer adhesion, water resistance, weather resistance, etc.). It is an object of the present invention to provide a paint composition, a metallic base paint, and a coating method that can be used for a metallic coating and a non-metallic coating and that can be finished in two coats and one bake.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies with the aim of drastically improving the above-mentioned drawbacks in an acrylic resin-CAB compound system in a metallic base paint, and as a result, for example, have found that hydroxyl groups If a graft copolymer of a vinyl derivative and a cellulose derivative obtained by subjecting a cyclic ester to ring-opening graft polymerization to a cellulose ester having the same as a vehicle for a metallic base paint, a cellulose ester represented by CAB is used. The problem of storage stability caused by poor compatibility with acrylic resin can be solved at once,
It is possible to greatly increase the amount of styrene monomer that is a component of the vehicle resin, and to improve the interlayer adhesion between the metallic base coating and the overcoating transparent coating, water resistance of the entire metallic coating system, weather resistance, etc. The inventors have found that a metallic coating film excellent in various properties can be formed, and have completed the present invention.

Thus, a first aspect of the present invention is a cellulose ester derivative (a) 5 obtained by ring-opening graft polymerization of a cyclic ester with a cellulose ester having a hydroxyl group.
-40% by weight and 95-60% by weight of the vinyl monomer component (b) (the total of (a) and (b) is 100% by weight).
A coating composition comprising a cellulose ester-modified vinyl copolymer (I) obtained by copolymerizing the above as a vehicle component and an organic solvent (S) added. The second aspect of the present invention is that the vinyl monomer component (b) is styrene 5-35.
The coating composition according to the first aspect of the present invention, which contains the composition by weight. A third aspect of the present invention provides a metallic base paint obtained by blending the metallic pigment (e) with the paint composition according to the first or second aspect of the present invention. A fourth aspect of the present invention is to apply the metallic base paint according to the third aspect of the present invention on a substrate surface, apply an uncured state, apply a thermosetting resin-based overcoating transparent paint, and then apply the coating film. A method for forming a metallic coating film characterized by baking is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for forming a coating composition, a metallic base paint and a metallic coating film of the present invention will be described in detail. Paint Composition The paint composition of the present invention is obtained by graft copolymerizing a cellulose ester derivative (a) obtained by ring-opening graft polymerization of a cyclic ester with a hydroxyl group-containing cellulose ester and a vinyl monomer component (b). Cellulose ester-modified vinyl copolymer (I) (hereinafter abbreviated as modified vinyl copolymer (I)) obtained by polymerization is used as a vehicle component.
An organic solvent (S) is added.

Cellulose Ester Derivative (a) The cellulose ester derivative (a) used in the present invention is obtained by subjecting a cyclic ester to ring-opening graft polymerization to a cellulose ester having a hydroxyl group. The above-mentioned cellulose ester having a hydroxyl group is one in which the hydroxyl group of cellulose is esterified with an acid leaving a part thereof, for example, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, nitric acid, and the like. Examples of cellulose esters such as cellulose include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose nitrate. Of these, cellulose acetate is particularly useful. An average of 1 to 2.9 ester bonds consisting of an acid and a hydroxyl group (up to 3) of a glucose unit of cellulose,
That is, the degree of substitution is preferably from 1 to 2.9, and the number of residual hydroxyl groups is preferably from 0.1 to 2 on average, and particularly preferably from 0.2 to 1.3.

The cyclic ester is not particularly limited as long as it can undergo ring-opening polymerization.
-Propiolactone, δ-valerolactone, ε-caprolactone, α, α-dimethyl-β-propiolactone,
β-ethyl-δ-valerolactone, α-methyllactone, β-methyl-ε-caprolactone, γ-methyl-ε
Lactones such as -caprolactone, 3,3,5-trimethyl-ε-caprolactone, 3,5,5-trimethyl-ε-caprolactone, and enantholactone; and cyclic esters such as glycolide and lactide. The cyclic ester is not limited to a single kind, but may be a combination of a plurality of the above-mentioned various kinds. As the cyclic ester, particularly, it is industrially easily available, relatively inexpensive, and has excellent ε- excellent compatibility with the cellulose ester according to the present invention, such as cellulose acetate.
Caprolactone is particularly preferred.

In the present invention, the charging ratio of the cellulose ester having a hydroxyl group and the cyclic ester for obtaining the cellulose ester derivative (a) is not particularly limited, and can be appropriately selected depending on the use form of the metallic coating composition. . However, graft polymerization of a cyclic ester to a cellulose ester having a hydroxyl group generally requires 99 to 15% by weight of the latter to 1 to 85% by weight of the former.
(The total of both is 100 wt%). When the charging ratio of the cellulose ester having a hydroxyl group exceeds 85% by weight, the viscosity of the reaction system becomes extremely high,
It becomes difficult to handle. Conversely, if it is less than 1 wt%, characteristics of cellulose ester such as heat resistance are lost, which is not preferable. If the viscosity is too high to handle easily, lower the viscosity of the system by adding an organic solvent that does not have active hydrogen with good compatibility with cellulose acetate and cyclic ester as a third component to facilitate the reaction. Is also possible.

The catalyst used for the graft polymerization of a cyclic ester, particularly a lactone, to a cellulose ester having a hydroxyl group includes a catalyst usually used for a ring opening reaction of a cyclic ester, that is, an alkali metal such as sodium or potassium, and an alkali metal such as sodium or potassium. Derivatives such as alkoxides, alkylaluminums and derivatives thereof represented by triethylaluminum, alkoxytitanium compounds represented by tetrabutyl titanate, organic metals or metal complexes such as tin octylate, dibutyltin laurylate, and metal halides such as organic tin And tin octylate is preferred.

In order to obtain the above-mentioned cellulose ester derivative (a) as a graft polymer, a conventional stirrer, a reactor equipped with a reflux condenser with a drying tube, and a twin-screw extruder are preferably used. .

The polymerization temperature for obtaining the above-mentioned derivative (a) is generally preferably the temperature applied to the ring-opening polymerization of the cyclic ester, and is preferably from 100 to 210 ° C. Also,
The polymerization reaction time varies depending on the type of the cellulose ester having a hydroxyl group and the cyclic ester, the charging ratio, the type and amount of the catalyst, the reaction temperature, and the reaction apparatus, and is not particularly limited. Hours to 8 hours. In addition, in obtaining the graft polymer according to the present invention, it is desirable that each raw material, nitrogen, a reactor, and the like used in the polymerization reaction be sufficiently dried.
Further, the water content of the reaction system is 0.1% by weight or less, preferably 0.01% by weight or less, more preferably 0.001% by weight.
It is as follows. The average graft polymer obtained by the polymerization reaction at such a charging ratio of the cellulose ester having a hydroxyl group and the cyclic ester is 1 to 50 mol, preferably 3 mol, of ε-caprolactone per residual hydroxyl group in the glucose unit.
Those having a structure formed by addition polymerization of from 30 to 30, more preferably from 5 to 20 mol are most preferred.

Vinyl monomer component (b) The vinyl monomer component (b) to be graft-copolymerized with the cellulose ester derivative (a) has a radically polymerizable α, β-ethylenically unsaturated bond of 1-2. Monomers, preferably one, are suitably used. For example, one or more of the following monomers can be appropriately selected and used. (A): vinyl monomers such as styrene, vinyltoluene, α-methylstyrene, vinyl acetate, acrylonitrile, and methacrylonitrile (B): methyl (meth) acrylate, ethyl (meth)
Acrylate, n-butyl (meth) acrylate, i-
The carbon number of (meth) acrylic acid such as butyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate 1 to 24 alkyl or cycloalkyl esters (C): 2-hydroxyethyl (meth) acrylate,
(Meth) such as hydroxypropyl (meth) acrylate
Hydroxyalkyl esters of acrylic acid having 1 to 24 carbon atoms (D): α, β-ethylenically unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, etc. (E): (meth) acrylamide, N-methyl (meth)
Functional (meth) acrylamides such as acrylamide and N-methylol (meth) acrylamide (F): glycidyl group-containing vinyl monomers such as glycidyl (meth) acrylate and allyl glycidyl ether

Among the above vinyl monomers (b), styrene (the component (A)); methyl methacrylate, ethyl methacrylate, and butyl methacrylate (the component (B)); 2-hydroxyethyl methacrylate A monomer comprising two or more of ((C) component) as main monomer constitutions and, if necessary, a small amount of (meth) acrylic acid ((D) component). While blends are given as a preferred example, it should be understood that the invention is not limited in any way to the above combinations. In particular, as the vinyl monomer component (b) to be graft-copolymerized with the cellulose ester derivative (a), a mixed component is preferable, and the mixed component is based on 100% by weight of the total of the monomer component (b). , Styrene 5-35
%, Preferably 10 to 25% by weight, with the remaining 9%
It is preferable that 5 to 65% by weight, preferably 90 to 75% by weight of the monomer component (b) is at least one vinyl monomer (b ') excluding styrene. As the vinyl monomer (b ′), acrylate monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-hydroxyethyl methacrylate, and mixtures thereof are particularly preferable.

Modified vinyl copolymer (I) The above-mentioned cellulose ester derivative (a) and the vinyl monomer component (b) are graft-copolymerized to obtain a modified vinyl copolymer (I). The ratio between the cellulose ester derivative (a) and the vinyl monomer component (b) can be changed depending on the composition ratio of the monomer components used, but generally, the cellulose ester derivative (a) and the vinyl monomer component are used. (B)
With the total being 100% by weight, cellulose ester derivative (a) 5 to 40% by weight, preferably 10 to 30% by weight, vinyl monomer component (b) 95 to 60% by weight, preferably 90 to 70% by weight Within the range.

The graft copolymerization between the cellulose ester derivative (a) and the vinyl monomer component (b) can be performed by a solution polymerization method in the presence of a radical polymerization initiator. Examples of the solvent used for the solution polymerization include benzene derivatives such as benzene, toluene and xylene; alcohols such as n-butanol and isobutanol; esters such as butyl acetate, ethyl acetate and cellosolve acetate; acetone and methyl ethyl ketone. Ketones and the like, and these can be used alone or as a mixture. As the polymerization temperature, a temperature in the range of generally about 50 to 200 ° C, preferably about 80 to 150 ° C is used.
As the radical polymerization initiator, among others, organic peroxide type initiators, for example, peroxide polymerization initiators such as benzoyl peroxide, lauroyl peroxide, dicumyl peroxide and tert-butyl hydroperoxide, cumene hydroperoxide, etc. Hydroperoxide-based polymerization initiators such as those described above are preferably used, and ketone peroxide-based or perester-based polymerization initiators can also be used. Particularly, benzoyl peroxide is preferred. Further, in addition to the above peroxides, hydroxyperoxides and the like, an azo polymerization initiator such as azobisisobutyronitrile may be used. These polymerization initiators are added alone or in combination of two or more to the polymerization reaction system.

In a copolymerization reaction using an organic peroxide or the like as a polymerization initiator as described above, generally, free radicals of an organic compound generated by thermal decomposition of the polymerization initiator are converted into a so-called chain compound by a hydrocarbon compound. Wake up,
It is thought that the polymerization of the vinyl monomer is started by the free radical generated in the hydrocarbon compound, and the vinyl monomer grows in a branched form in the hydrocarbon compound to form a graft copolymer. I have. In the graft copolymerization of the present invention using the cellulose ester derivative (a) and the vinyl monomer component (b), the cellulose ester derivative (a) (corresponding to the case of the above-mentioned hydrocarbon compound) has such a reaction mechanism. ) And the vinyl monomer component (b). When the vinyl monomer component (b) is grafted to the hydrocarbon compound in this manner, the graft, that is, the number of branches and the length of the branches are longer, and the graft copolymer to be formed is more soluble in the organic solvent. It is generally understood that solubility increases. The same applies to the modified vinyl copolymer (I) according to the present invention obtained by grafting the vinyl monomer component (b) to the cellulose ester derivative (a), that is, the cellulose ester derivative-modified vinyl copolymer. For this reason, it is assumed that the solubility of the cellulose ester derivative and the compatibility with the acrylic resin are improved. In the present invention, the compounded cellulose ester derivative (a) is desirably substantially copolymerized with the vinyl monomer component (b).
However, there is no problem even if a small amount of the cellulose ester derivative (a) is contained in the modified vinyl copolymer (I) without being reacted. The modified vinyl copolymer (I) thus prepared is used as a vehicle for a metallic base paint.

Metallic base paint The metallic base paint of the present invention is prepared by adding the above-mentioned modified vinyl copolymer (I) as a vehicle component to a paint composition comprising the following organic solvent (S) and a metallic pigment ( e). The metallic base paint can be prepared according to a method known per se. For example, a metallic pigment (e) and, if necessary, a coloring pigment and other conventional paint additives are dispersed in an organic solution of the modified vinyl copolymer (I). By adjusting the above, a metallic base paint can be obtained.

Examples of the organic solvent (S) for the organic solution or the organic solvent for the diluting solvent include alkylbenzene derivatives such as benzene, toluene and xylene; alcoholic solvents such as n-butanol and iso-butanol; There are acetate solvents such as butyl, ethyl acetate and cellosolve acetate; ketone solvents such as acetone and methyl ethyl ketone; these may be used alone or in combination. The final concentration of the modified vinyl copolymer (I) in these solvents is not critical and can vary widely depending on the coating conditions and the like, but generally ranges from 10 to 80 in 100% by weight of the coating composition. %, Preferably 20 to 40% by weight.

Examples of the metallic pigment (e) include metal powders such as aluminum powder, copper powder and bronze powder, mica like titanium dioxide, mica-like iron oxide, nickel sulfide powder, cobalt sulfide powder, manganese sulfide powder, titanium nitride powder. And other metallic pigments. Also, the amount of the metallic pigment (e) is not critical, and can be widely varied depending on the type of the metallic pigment (e).
Generally, it can be 5 to 30% by weight, preferably 5 to 20% by weight, based on 100% by weight of the coating composition. The average particle size of the metallic pigment (e) to be blended is generally 3 to 20 μm, and the particle size distribution is 3 to 40 μm.
Those in the range are suitable.

Further, the metallic base paint of the present invention reacts with a functional group (hydroxyl group, carboxyl group, glycidyl group, etc.) derived from a vinyl monomer component in the modified vinyl copolymer (I) to form a crosslinked structure. And it is generally desirable to do so. Examples of the curing agent that can be blended include aminoaldehyde resins such as butyl etherified melamine resins and methyl etherified melamine resins, as well as blocked isocyanates. Modified vinyl copolymer (I) in this case
Generally, the ratio of the curing agent to the curing agent is combined so that the copolymer / curing agent ratio is in the range of 60/40 to 90/10 based on the weight of the solid content.

As other resins used in combination with the cellulose ester derivative (a), conventionally known coating resins can be used. Specifically, for example, chlorinated polypropylene resin, maleated chlorinated polypropylene resin, ethylene-acrylic acid copolymer, polyolefin resin such as EPDM (terpolymer of ethylene-diene monomer), polybutadiene resin, the polyolefin resin Graft copolymer obtained by graft reaction of resin or polybutadiene resin with radically polymerizable unsaturated monomer such as (meth) acrylate, styrene, etc., epoxy-fatty acid ester resin, alkyd resin, acrylic resin Thermoplastic resin such as resin: Thermosetting resin composed of base resin such as acrylic resin, polyester resin, alkyd resin, epoxy resin and urethane resin and crosslinking agent (amino resin, blocked polyisocyanate compound) : The above base resin and cross-linking agent There is a room temperature curable resin consisting of a sulfonate compound).

Method for Forming Coating Film The coating of the metallic base coating material of the present invention on the surface of a substrate is as follows.
According to a conventional method, for example, it can be performed by air spray coating, electrostatic air spray coating, electrostatic atomization coating, or the like. The thickness of the coating is generally preferably in the range of about 5 to 30 μm for a dry coating. Examples of the types of substrates on which the metallic base paint of the present invention can be applied include metals such as aluminum and steel plates; and plastics such as polystyrene and ABS resin.

According to the method of the present invention, the painted metallic base coating is applied with a thermosetting resin-based transparent top coat in an uncured state without baking. The thermosetting resin-based overcoating transparent coating is generally preferably a thermosetting acrylic resin-based coating, and is a combination of a conventionally known functional acrylic copolymer and a cross-linking agent, and has an interlayer adhesion with a metallic base coating film. There is no particular limitation as long as it has good properties and good weather resistance, and it can be appropriately selected from various known overcoating transparent paints. Among them, from a combination of an acrylic resin containing a functional acrylic monomer having a hydroxyl group in the monomer composition and an amino resin-based crosslinking agent such as a butyl etherified melamine resin or a methyl etherified melamine resin. Transparent paints are preferred.

As the above-mentioned transparent overcoat applied to the method of the present invention, a thermosetting acrylic resin-based resin is recommended, in particular, because it is necessary to maintain the weather resistance of the metallic coating for a long period of time. However, according to the required performance of the coating system, it is of course possible to use a known coating material containing an aminoalkyd resin as a main component, for example.

The overcoating transparent paint can also be applied in a conventional manner by means such as air spray coating, electrostatic air spray coating, electrostatic atomization coating, and electrostatic airless coating. Is generally sufficient as a dry coating film in the range of about 10 to 50 μm.

After the overcoating transparent paint is applied in this way, baking is performed. Baking is carried out according to a conventional method, for example, using an electric hot air dryer, an indirect hot air drying oven, a direct hot air oven, a far-infrared oven, etc., and keeping the coating film at a temperature of about 80 to about 180 ° C. for about 15 to about 45 minutes. Can be performed.

As described above, the two-coat / one-bake metallic coating film forming method according to the present invention does not require any special equipment, equipment, and usage for coating both the metallic base paint and the transparent top coat. It has the advantage that it can be easily achieved by known conventional means. However, it highly embodies the appearance and quality of metallic coatings,
In order to maintain excellent uniformity of coating, it is preferable to apply the metallic base paint and the overcoating transparent paint using a spray (spraying) coating method, and to appropriately introduce an electrostatic spray method as necessary. Can also.

According to the present invention described above, the following excellent technical effects can be achieved. First, when the metallic base paint of the present invention using the modified vinyl copolymer (I) is applied to the surface of a substrate, the viscosity of the applied paint sharply increases as the diluting solvent contained in the paint evaporates. To rise. The degree of increase in the viscosity is much higher than that without the cellulose ester derivative (a). This is the first factor for the movement of the metal powder such as aluminum powder to stop earlier and give a good metallic feeling. Second, since the modified vinyl copolymer (I) has improved compatibility with the cellulose ester derivative (a) remaining as an unreacted product, a coating film obtained by using the metallic paint of the present invention. Is more excellent in coating surface smoothness. Third, in the vinyl monomer composition to be graft-copolymerized with the modified vinyl copolymer (I), the compatibility has been deteriorated, the coating film becomes clouded, or the cellulose ester derivative (a) aggregates. Styrene which was not substantially used in the copolymerization system due to the occurrence of lumps due to styrene, or which was used but was 5 to 10% or less of the monomer composition even if it was used, was obtained. Can be Styrene is a monomer component that gives a polymer with excellent chemical resistance and water resistance.It also has the function of further enhancing the interlayer adhesion with the thermosetting resin-based overcoating transparent paint. The finished appearance of the coating system of the present invention when the modified vinyl copolymer (I) containing a wide range of 3 to 35% by weight, especially a large amount, based on the total weight of the monomer component is used as a vehicle. In addition, the chemical resistance, the water resistance, and the interlayer adhesion with the overcoated transparent coating film are remarkably improved, so that the durability of the entire metallic coating film is improved.

In the present invention, the desired purpose is achieved by incorporating the above-mentioned modified vinyl copolymer (I) into a metallic base paint containing a metallic pigment (e). The usefulness of the copolymer is not limited only to the case of a metallic coating film, but also to a non-metallic coating film, that is, a solid color coating film using a normal coloring pigment, a thermosetting acrylic resin-based topcoat. It can be applied as a two-coat / one-bake paint finish which should maintain excellent interlayer adhesion between the layers and good water resistance and weather resistance of the coating system.

[0033]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. All parts and percentages in the examples are parts by weight and percentage by weight. [Synthesis Example 1] (Synthesis of Cellulose Ester Derivative (a1)) In a reactor equipped with a stirrer, a thermometer, and a reflux condenser with a drying tube on the top, absolutely dried cellulose acetate (Vinegar, manufactured by Daicel Chemical Industries, Ltd.) 55%, degree of substitution 2.45, Table 1
In the reaction system) and purified ε-caprolactone at a weight ratio shown in Table 1 to reduce the water concentration in the reaction system to 0.1 wt%.
In the following manner, the mixture was heated to 180 ° C. and stirred to uniformly dissolve the cellulose acetate. After confirming dissolution, 0.24 parts of tin octylate (II value) was added dropwise as a catalyst, and after reacting for 4 hours, the graft was taken out of the reactor.

[0034]

[Table 1]

[Synthesis Example 2] (Modified vinyl copolymer (I
Synthesis of A)) The following components are charged into a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a dropping funnel. Toluol: 25 parts n-butanol: 25 parts Cellulose ester derivative (a1) of Synthesis Example 1: 20 parts Subtotal: 70 parts The above cellulose ester derivative solution is heated in a nitrogen gas atmosphere and takes about 1 hour to reach 100 ° C. Heat.
After the temperature reaches 100 ° C. and the cellulose ester derivative is completely dissolved, a mixed solution of the following vinyl monomer and a polymerization initiator is dropped into the cellulose ester derivative solution over 3 hours. Styrene: 20 parts Methyl methacrylate: 20 parts Ethyl acrylate: 47 parts 2-hydroxyethyl methacrylate (2-HEM
A): 12 parts Acrylic acid: 1 part Xylol: 50 parts Benzoyl peroxide: 2 parts Subtotal: 152 parts 30 minutes after the completion of dropping, azobisisobutyronitrile was added to 0.1 part.
5 parts were further added and kept at 100 ° C. for 2 hours under a nitrogen atmosphere, and then 20 parts of xylol was added to obtain a modified vinyl copolymer solution (IA) having a solid content of 50%. This copolymer solution was colorless and transparent, and had a Gardner cell viscosity (25 ° C.) of Z at 50% solution.

[Synthesis Examples 3 to 15] A modified vinyl copolymer was prepared in the same manner as in Synthesis Example 2 except that the compositions of the cellulose ester derivative (a1) and the vinyl monomer shown in Tables 2A and 2B were used. Polymer solutions (IB) to (IH) and (I-
L) to (IN) were obtained. For comparison, Synthesis Examples 10 to 12
Modified vinyl copolymer solutions (II) to (I-)
The three types (K) are obtained by synthesizing only a vinyl monomer in the absence of the cellulose ester derivative (a1) by the same production method as in Synthesis Example 2. The compositions and results of Synthesis Examples 2 to 15 are summarized in Tables 2A and 2B. Table 2A and Table 2B
In the above, the transparency of the coating film is evaluated for a coating film obtained by applying the film to a transparent glass plate, leaving it to stand, and then heating it at 130 ° C. for 3 hours. The evaluation is ◎ transparent, Δ slightly cloudy, × cloudy (component separation).

[0037]

[Table 2]

[0038]

[Table 3]

[Production of Metallic Base Coating] (1) Metallic Base Coating A Metallic coating A was prepared using the modified vinyl copolymer solution (IA) with the following composition. Modified vinyl copolymer solution (IA): 200 parts Butylated melamine resin solution (Note i): 55.6 parts Aluminum paste (Note ii): 10 parts Carbon black (Note iii): 0.2 parts Cyanine Blue (Note iv): 0.5 parts Total: 266.3 parts (Note i) manufactured by Dainippon Ink and Chemicals, Inc., trade name Super Beckamine J-820, solid content 60% (Note ii) Toyo Aluminum ( Aluminum Paste 1109MA (trade name), manufactured by Columbia Carbon Co., USA, Neospectra Bead AG (trade name), Cyanine Blue # 5030SA, manufactured by Dainippon Ink and Chemicals, Inc. 40 parts of base paint A in toluene,
Swazole # 100030 parts, butyl acetate 20 parts, n-
The viscosity was adjusted to 14 seconds (Ford cup # 4/20 ° C.) with a mixed solvent consisting of 10 parts of butanol.

(2) Metallic base paints BH and O
To Q, using a modified vinyl copolymer solution (IB) to (IH), (IL) (IN) according to the composition of the metallic base coating material A, and a cellulose ester derivative-vinyl graft. Copolymer solutions BH and OQ were prepared. (3) Metallic base paints I to K for comparison 50% containing no cellulose ester derivative for comparison
Metallic base paints I to K were prepared using the vinyl copolymer solutions (I-I) to (I-K). (4) Comparative mixed metallic base paints L to N Further, in order to compare the modified vinyl copolymer (I) with a simple blend of the cellulose ester derivative (a) and the acrylic resin, the above 50% Vinyl copolymer solutions (II) to (IK) and cellulose ester derivative (a
1) with a 30% solution of the cellulose ester derivative (a
Metallic base paints L to N were prepared by blending so that the content of 1) was 20%. In this case, a 30% solution of the cellulose ester derivative is obtained by mixing the cellulose ester derivative (a1) with 40 parts of toluene, 40 parts of ethyl acetate, n
-A 30% solution in a mixed solvent consisting of 10 parts of butanol and 10 parts of xylol. These A to Q
Table 3 shows the composition of the metallic base paint and the solid content concentration (%) at the time of coating.

[0041]

[Table 4]

[Production of an Acrylic Resin Solution for a Thermosetting Acrylic Resin Topcoat Transparent Paint] An aromatic petroleum solvent (trade name: Swazole # 1000, Maruzen) was placed in a reactor equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel. Oil company products) 4
5 parts were charged and heated under a nitrogen gas atmosphere. When the temperature reached 120 ° C., the flow of the nitrogen gas was stopped, and a mixed liquid of a vinyl-based and acrylic-based monomer and a polymerization initiator shown below was added to 3 parts.
Drip over time. Styrene: 30 parts n-butyl methacrylate: 22 parts Lauryl methacrylate: 30 parts 2-hydroxymethacrylate: 15 parts Methacrylic acid: 3 parts n-butanol: 15 parts Azobisisobutyronitrile: 2 parts Subtotal: 117 parts Dropping end 30 After a minute, the azobisisobutyronitrile 0.1.
Add 5 parts over 1 hour, and add 2 parts under nitrogen atmosphere.
Continue heating to 120 ° C. for hours. Then swazole # 1
000 was added to obtain a 50% resin solution. The obtained acrylic resin solution L was a colorless and transparent liquid, and had a Gardner bubble viscosity (25 ° C.) of P.

[Production of Thermosetting Acrylic Resin Topcoat Transparent Coating] Using the above acrylic resin solution for a topcoating transparent coating, a thermosetting acrylic resin topcoating transparent coating was prepared with the following composition. 50% Acrylic resin solution for overcoat transparent coating: 140 parts 60% Super Beckamine J-820: 50 parts Subtotal: 190 parts Next, this overcoat transparent paint was swirl # 1000 with a viscosity of 30 seconds (Ford cup # 4/20 ° C.) Was adjusted. The solid content concentration of this paint at the time of application was 41%.

Example 1 A polybutadiene-based electrodeposition primer (trade name: Electron No. 6000, manufactured by Kansai Paint Co., Ltd.) was dry-coated on a 0.8 mm-thick dull steel plate that had been subjected to zinc phosphate conversion treatment. After electrodeposition coating to a film thickness of about 20 μm, baking at 170 ° C. for 20 minutes, sharpening with # 400 sandpaper, wiping with petroleum benzene and degreasing.
Then, an amino-alkyd resin-based intermediate coating surfacer for automobiles (trade name: Amirac Surfacer, manufactured by Kansai Paint Co., Ltd.) is applied by air spraying so as to have a dry coating of about 25 μm, and baked at 140 ° C. for 30 minutes.
Wet with # 400 sandpaper and drain and dry.
This is degreased by wiping with petroleum benzene and used as a test material. This material was coated with the metallic base coating material A under the following coating conditions. (Coating conditions) Temperature and humidity of coating base: 23 ° C, 75 RH Coating machine: Electrostatic coating machine Auto REA (manufactured by Ransburg Company) Atomizing air pressure: 5 kg / cm ² (gun hand pressure during spraying) : 400 ml / min. Coating film thickness: 18 ± 2 μm (dry coating film) After applying the metallic base coating material A, it is left at room temperature for 3 minutes. Then, the above-mentioned thermosetting acrylic resin-based overcoating transparent paint was applied under the same coating conditions as the metallic base paint to a dry film thickness of 3
After coating at 0 ± 2 μm and leaving it at room temperature for 10 minutes, it was cured by heating at 140 ° C. for 30 minutes using an electric hot air dryer. The obtained coated plate was excellent in metallic feeling. This was applied to the test coated plate No. Let it be 1.

[Examples 2 to 11 and Comparative Examples 1 to 6] Under the same coating conditions as in Example 1, a metallic base paint shown in Table 4 was applied on a test coated plate. 2 to 8 (Examples 2 to 8), test coated plate Nos. 15-17 (Examples 9-1)
1) and the test coated plate No. 9 to 14 (Comparative Examples 1 to 6) were prepared. Table 4 below shows the type of the metallic base paint used, the key points in the composition of the modified vinyl copolymer (I) or the acrylic resin used therein, and the performance test results of each test coated plate.

[0046]

[Table 5]

In Table 4, (a1) in the column of the modified vinyl copolymer indicates the cellulose ester derivative of Synthesis Example 1. The St amount in (b) indicates the styrene amount in the vinyl monomer component (b). (Note 1) to (Note 6) are as follows. (Note 1) Metallic feeling of coating film and (Note 2) Smoothness of coated surface:
The evaluation criteria were as follows. ：: extremely good 〇: good Δ: slightly poor ×: poor The better the uniformity of the coated surface, the evenness and the glittering metallic feeling. The specular reflectivity is 60 ° specular reflectivity (%). (Note 3) Chemical resistance: Chemical solution: 10% by weight H ₂ SO ₄ aqueous solution Spot: Five drops of the chemical solution were spotted on each coated plate. Evaluation: After 50 minutes at 50 ° C., the coating film was evaluated for blistering and discoloration. (Note 4) Interlayer adhesion test: Each coated plate was exposed to warm water of 40 ° C for 24 hours.
After immersion for 0 hour and pulling up, 30 minutes later, an adhesion test was conducted by peeling off the pressure-sensitive adhesive tape at the cross cut portion. (Note 5) Moisture resistance test: Each coated plate was placed in a blister box at 50 ° C. and 100% relative humidity for 100 hours, and the occurrence of blisters was examined. (Note 6) Weather resistance test: Each coated plate was placed in a sunshine type weather ometer (SWOM), irradiated for 2,300 hours, and then the gloss retention was measured.
Vertical and horizontal cross cuts were made at m intervals, and an adhesion test was performed by peeling off the adhesive tape at those portions.

Examples 1 to 11 are metallic finishes according to the present invention. Example 2 is an example in which styrene is not contained in the vinyl monomer at all, and is slightly inferior in chemical resistance to other examples. On the contrary, Example 5 is an example containing too much styrene, in which the compatibility with the cellulose ester derivative is deteriorated, the resin solution becomes cloudy, and the finished appearance is slightly lowered. Comparative Examples 1 to 3 use the comparative metallic base paints I to K containing no cellulose ester derivative, and have styrene amounts of 0, 20, and 30%, respectively. Comparative Example 1 in which the amount of styrene is 0% has good compatibility with that in which 20% of the cellulose ester derivative is added (see Production Examples 10 to 12 in Table 2), but the finished appearance and other performances are poor. ing. Similarly, Comparative Examples 2 and 3 contain 20% and 30% styrene, respectively.
%, And the compatibility with the cellulose ester derivative is extremely deteriorated with generation of fogging and separation (see Table 2), and similarly to Comparative Example 1, the finished appearance and other properties are also deteriorated. Further, Comparative Examples 4 to 6 used the mixed metallic base paints L to N for comparison, but those containing no styrene at all were cellulose ester derivatives (a1).
(In Table 4, (a1) is described as (20) in Table 4 because it is not a modified vinyl copolymer).
Although the finished appearance is improved as compared with Comparative Example 1, the performance test results still show defects. Comparative Examples 5 and 6 further containing 20% and 30% styrene
In the addition of a cellulose ester derivative,
In addition to fogging and blemishes (separation), Comparative Example 6 had an extremely poor coating surface condition, and was not subjected to a performance test.

[0049]

According to the present invention, styrene can be contained in a wide range as a constituent component of the graft polymer, and the chemical resistance, the water resistance, and the interlayer adhesion with the overcoated transparent coating film are good. A paint composition capable of 2 coats and 1 bake finish, which can be used for metallic coatings and non-metallic coatings that give good metallic feeling,
A metallic base paint and coating method are obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 5/29 C09D 5/29 5/38 5/38 // C09D 101/10 101/10 F-term (reference 4D075 AE06 BB28Z CB13 EA43 EB07 4J038 CG141 CH121 CP011 CP051 DA162 HA066 HA216 HA316 HA356 KA03 KA06 KA08 KA20 MA09 NA01 NA03 NA04 NA12 NA24 NA26 PA19

Claims (4)

[Claims] A cellulose ester derivative (a) obtained by subjecting a cyclic ester to a cellulose ester having a hydroxyl group by ring-opening graft polymerization, 5 to 40% by weight, and a vinyl monomer component (b) 95 to 60% by weight ( (A) and (b) are 100% by weight). The cellulose ester-modified vinyl copolymer (I) obtained by copolymerizing (a) and (b) is used as a vehicle component, and an organic solvent (S) is added. Paint composition. 2. The method according to claim 1, wherein the vinyl monomer component (b) is styrene 5
The coating composition according to claim 1, comprising 35% by weight. 3. A metallic base paint comprising the paint composition according to claim 1 and a metallic pigment (e). 4. The method according to claim 3, wherein the metallic base paint according to claim 3 is applied to a substrate surface, and then, in an uncured state, a thermosetting resin-based overcoating transparent paint is applied, and then the coating film is baked. A method for forming a metallic coating film.