JPH0753841B2 - Paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a coating composition having excellent coating film appearance and coating film performance,
In particular, the present invention relates to a coating composition suitable for a two-coat one-bake coating base coat.

[Conventional technology]

As a coating composition which gives an excellent coating film appearance and coating film performance, a two-coat one-bake coating system is widely adopted for top coating of automobiles and the like.

Two-coat / one-bake coating uses metallic paint that uses metallic powder such as aluminum powder as the base coat paint, and solid color coating that uses solid color paint consisting of colored paint and binder without metallic powder. There is. In metallic coating, the arrangement of the metal powder contained in the base coat paint in the coating film and the base coat and clear coat when the clear coat paint is applied without baking after applying the base coat paint Layer formability (a state in which two layers are formed at the interface between the base coat and the clear coat without being compatible with each other) has a great influence on the appearance of the coating film. Even in solid color coating, the two-layer formability of the base coat and the clear coat greatly affects the appearance of the coating film.

As a method for controlling the arrangement of the metal powder and the two-layer formability of the base coat and the clear coat, conventionally, the viscosity of the base coat coating film is rapidly increased after the base coat coating material is applied and before the clear coat coating material is applied. There are methods such as using a relatively high molecular weight resin as a vehicle to prevent the movement of powders or making the clear coat paint less compatible when applied, or using a highly volatile solvent for the base coat paint. It is being appreciated.

However, in these methods, it is difficult to obtain an excellent coating film appearance due to the movement of metal powder or the compatibility of the base coat and the clear coat because the viscosity increase after application of the base coat paint is not so large. It was

In order to make up for this drawback, there is known a method of blending a cellulose derivative with a base coat paint. A paint blended with a cellulose derivative has a large increase in viscosity after application, and is advantageous for the arrangement of the metal powder and the two-layer formability of the base coat and the clear coat. However, the cellulose derivative generally has poor compatibility with the acrylic resin or amino resin to be blended, and therefore has drawbacks such as cloudiness of the paint or coating film, and easy separation during storage.

As a method of compensating for such drawbacks, it has been proposed to use a resin obtained by graft-polymerizing an acrylic resin and a cellulose derivative as a vehicle (for example, Japanese Patent Publication No. 60-23792).
No. 60-252664).

[Problems to be solved by the invention]

However, these graft-polymerized resins have a problem that the compatibility with an acrylic resin or an amino resin is improved, but the appearance of the coating film is only slightly improved, and the gasoline resistance is poor.

Although these graft-polymerized resins are improved in compatibility with acrylic resins or amino resins,
The reason why the appearance of the coating film does not show a remarkable effect and the gasoline resistance is inferior is that the acrylic monomer is reacted in the cellulose derivative solution during the graft polymerization of the cellulose derivative and the acrylic resin, so that it does not graft polymerize with the cellulose derivative. A low molecular weight acrylic resin is produced,
Due to the presence of this low molecular weight acrylic resin, when the clear coat paint is applied after the base coat paint is applied, the base coat and the clear coat are partly compatible, resulting in a decrease in gloss and unevenness of the metal due to the movement of metal powder. It is considered that the coating film appearance is deteriorated.

When the acrylic monomer is reacted in the cellulose derivative solution, the reason why the low molecular weight acrylic resin is generated is that the radical of the low molecular weight acrylic resin that started the polymerization moves to the cellulose derivative and the polymerization is stopped while the low molecular weight remains. It is presumed that it is because it ends up.

An object of the present invention is to provide a coating composition having an excellent coating film appearance and coating film performance by using a vehicle obtained by modifying a cellulose derivative with an acrylic resin without producing a low molecular weight acrylic resin.

[Means for solving problems]

The present invention relates to an acrylic modified cellulose derivative obtained by reacting 5 to 70% by weight of a cellulose derivative, and 30 to 95% by weight of a carboxyl group-containing acrylic resin having a resin acid value of 10 to 80 mgKOH / g and a weight average molecular weight of 8,000 to 80,000. And a cross-linking agent as a vehicle component.

Examples of the cellulose derivative used in the present invention include cellulose esters such as cellulose acetate butyrate, cellulose acetate, and cellulose acetate propionate. Cellulose acetate butyrate is preferred from the viewpoint of solubility and viscosity, and the degree of acetylation is 1 to 34% by weight, the degree of butyrylization is 16 to 60% by weight, and ASTM-
Viscosity by the measuring method described in D-1343154 is 0.005 to 5
Seconds, preferably in the range of 0.01 to 2 seconds, are more effective. Specific examples of such cellulose acetate butyrate include CAB-551-0.01, CAB-551-0.2, CAB-531 manufactured by Eastman Chemical Products.
-1, CAB-500-1, CAB-381-0.1, CAB-381-0.5,
There is CAB-381-2 (both are trade names).

Next, the carboxyl group-containing acrylic resin to be reacted with the above cellulose derivative is a monomer having a polymerizable ethylenically unsaturated bond and a carboxyl group, and a monomer having another ethylenically unsaturated bond polymerizable with these. It is obtained by polymerizing one or more of the bodies by a conventional method.

Examples of the above-mentioned monomer having an ethylenically unsaturated bond and a carboxyl group include acrylic acid, methacrylic acid, itaconic acid and crotonic acid. In addition, other monomers that can be polymerized with them include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, i-butyl acrylate, i-butyl methacrylate, tert-butyl acrylate. , Tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2
-Ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, and other alkyl or cycloalkyl esters of acrylic acid or methacrylic acid having 1 to 24 carbon atoms; 2-hydroxyethyl acrylate, 2-
Hydroxyalkyl ester of acrylic acid or methacrylic acid having 2 to 24 carbon atoms such as hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; styrene, vinyltoluene,
Examples include styrene-based monomers such as α-methylstyrene; or acrylonitrile, methacrylonitrile and the like.

As the carboxyl group-containing acrylic resin, the resin acid value is 10 to 80 mgKOH / g, and the weight average molecular weight is 800 to 80.
Those of 000, preferably 10,000 to 80,000 are suitable. When the resin acid value is less than 10 mgKOH / g, the reaction with the cellulose derivative is not sufficiently performed, the obtained acrylic modified cellulose derivative has insufficient compatibility with the acrylic resin and amino resin, and the acid value is 80 mgKOH / g. When it exceeds g, the solubility of the acrylic resin decreases, and the reaction product becomes insoluble, making it difficult to use. If the weight average molecular weight is less than 8,000, the resulting acrylic modified cellulose derivative contains a low molecular weight acrylic resin.Therefore, when used as a base coat paint, when the clear coat is applied, part of the base coat and clear coat are compatible. As a result, the gloss is reduced and the appearance of the coating film such as unevenness of the metal due to the movement of the metal powder is deteriorated. Even if the weight average molecular weight exceeds 80,000, no significant effect is observed on the coating film appearance and coating film performance, and handling becomes difficult. Therefore, it is not necessary to use the one having a weight average molecular weight of more than 80,000.

The reaction ratio of the cellulose derivative and the carboxyl group-containing acrylic resin is in the range of 5 to 70% by weight of the cellulose derivative and 30 to 95% by weight of the carboxyl group-containing acrylic resin with respect to the total amount of the cellulose derivative and the carboxyl group-containing acrylic resin, Mix and react in this range. When the amount of the cellulose derivative is less than 5% by weight and the amount of the carboxyl group-containing acrylic resin is more than 95% by weight, no significant effect on the appearance and performance of the coating film can be seen even when used as a base coat paint. Further, when the amount of the cellulose derivative exceeds 70% by weight and the amount of the carboxyl group-containing acrylic resin is less than 30% by weight, the amount of the acrylic modification of the cellulose derivative is small and the compatibility with the acrylic resin or the amino resin is deteriorated. It becomes difficult to obtain the appearance and coating performance.

The reaction between the cellulose derivative and the carboxyl group-containing acrylic resin can be carried out in a solution in the presence of an esterification reaction catalyst.

Examples of the esterification reaction catalyst used include dibutyltin oxide, dioctyltin oxide, dibutyltin dilaurate, dioctyltin dilaurate, sodium methylate, sodium ethylate, zinc octylate, calcium acetate, antimony oxide, tetraisopropyl titanate and tetrabutyl titanate. can give. As the reaction solvent, benzene, toluene, xylene and an aromatic solvent having a boiling point of 150 to 200 ° C., for example, Solvexo 100, Solvesso 150 (trade name) manufactured by Exxon, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisobutyl ketone. One or more solvents such as ketone solvents such as cyclohexanone and isophorone can be used.

The reaction temperature of the esterification reaction is preferably in the range of 100 to 180 ° C.

The acrylic modified cellulose derivative thus obtained can be used in combination with a crosslinking agent as a coating composition, particularly as a vehicle for a base coat of a two coat, one bake coating system. In the present invention, in addition to the acrylic modified cellulose derivative and the cross-linking agent, other coating film forming resins such as acrylic resin and polyester resin may be added and used as a vehicle component. Examples of the crosslinking agent used here include amino resins such as methylated melamine resins and butylated melamine resins, as well as polyisocyanate compounds and blocked isocyanate compounds. In this case, the ratio of the vehicle component excluding the cross-linking agent and the cross-linking agent is based on the weight of the solid content.
It is preferable to combine them so that the ratio of the cross-linking agents is in the range of 60/40 to 90/10.

The coating composition of the present invention, in addition to the acrylic modified cellulose derivative and a crosslinking agent, and vehicle components such as acrylic resin and polyester resin, various solvents, metallic pigments,
Coloring pigments, dyes, fillers, and surface modifiers such as Modaflow (trade name, leveling agent manufactured by Monsanto Inc. in the US) and the like can also be incorporated. Examples of the metallic pigment include metal powder such as aluminum powder, copper powder and bronze powder, titanium dioxide coated mica, mica-like iron oxide, nickel sulfide powder, cobalt sulfide powder, manganese sulfide powder,
Examples thereof include titanium nitride powder, and examples of color pigments and dyes include metal oxides, metal hydroxides, metal powders, metal sulfides, sulfates, carbonates, lead chromate, etc. which are commonly known for coatings. Salts, carbon black, organic pigments and organic dyes.

The coating composition of the present invention is suitable as a base coat for a two-coat, one-bake coating system, but can be used as another coating composition.

The coating composition of the present invention is applied by a conventional method such as air spray coating, electrostatic air spray coating, electrostatic atomization coating and the like.
When the coating composition of the present invention is used as a base coat coating composition, after coating as described above, the clear coat coating composition is coated thereon without baking.

The clear coat paint used here is preferably a thermosetting acrylic resin-based paint, and from among the conventionally known combined use paints of a functional acrylic copolymer and a crosslinking agent, a metallic base coating film and Those having good interlayer adhesion and good weather resistance can be appropriately selected and used.
Above all, a transparent coating composition of a combination of an acrylic resin containing a monomer having a hydroxyl group in the monomer composition and an amino resin crosslinking agent such as a butylated melamine resin or a methylated melamine resin is preferable. In addition, it is also possible to use another thermosetting resin-based top coat clear coat coating composition such as a coating composition containing an amino-alkyd resin as a main component depending on the required performance of the coating system.

〔The invention's effect〕

According to the present invention, since an acrylic modified cellulose derivative is contained as a vehicle component, an excellent coating film appearance and coating film performance can be obtained. By using it as a 2-coat 1-bake coating system base coat paint, it has not been possible in the past. A coating film having an excellent coating film appearance and coating film performance can be obtained, which is particularly useful as a topcoat for automobiles and the like.

〔Example〕

The present invention will be described below with reference to Examples, Comparative Examples and Production Examples.
In each example, parts and% mean parts by weight and% by weight.

A. Production of carboxyl group-containing acrylic resin solution Production Example A1 Charge 49.7 parts of xylene to a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing device and a suitable lower funnel,
The mixture was heated and stirred while introducing nitrogen gas, and when the temperature reached 140 ° C, a mixed solution of the monomer component and the polymerization initiator shown below was added to the mixture.
At a constant temperature of 0 ° C., the solution was added dropwise at a constant speed over 2 hours from a dropping funnel.

After 2 hours styrene 5.0 parts methyl methacrylate 24.5 parts of acrylic acid n- butyl 12.8 parts of methacrylic acid 2 1.3 parts of hydroxyethyl 6.4 parts of acrylic acid tertiary butyl peroxy benzoate 0.3 parts Total 50.3 parts after dropping 140 ° C., It was cooled and the contents were taken out. The carboxyl group-containing acrylic resin solution A1 thus obtained had a nonvolatile content of 50.0% and a viscosity of VW by the GPC method (using a HLC-802A (trade name) manufactured by Toyo Soda Kogyo Co., Ltd. as a measuring device) and having a weight average in terms of polystyrene. Molecular weight measurement method)
The weight average molecular weight of the product was 3.8 × 10 ⁴ .

Production Examples A2 to A15 By the same method as in Production Example A1, carboxyl group-containing acrylic resin solutions A2 to A15 were obtained with the formulations shown in Table 1. The characteristic values of the obtained resin solutions A2 to A15 are shown in Table 1 together with the resin solution A1.

B. Production of acrylic modified cellulose derivative solution Production Example B1 25 parts of carboxyl group-containing acrylic resin solution A1, CAB-5
31-1 (Previously mentioned cellulose acetate butyrate) 12.5
Part, Solvesso 100 (the above-mentioned aromatic petroleum solvent) 12.5 parts,
0.1 part of dibutyltin oxide was charged into a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube and a Dean Stark trap, and the reaction was carried out under a nitrogen gas atmosphere at a temperature of 150 to 155 ° C. for 5 hours. . Xylene 26.8 after completion of reaction
Parts, 7.8 parts of n-butyl alcohol and 15.3 parts of ethyl acetate were added for dilution, and the contents were taken out after cooling. The obtained resin solution B1 had a nonvolatile content of 24.8% and a viscosity S.

Production Examples B2 to B19 By the same method as in Production Example B1 above, acrylic modified cellulose derivative solutions B2 to B19 were obtained with the formulations shown in Table 2.
The characteristic values of the obtained resin solution are shown in Table 2 together with the resin solution B1.

C. Production of Comparative Resin Solution Comparative Production Example C1 12.5 parts of CAB-531-1 (supra) in a mixer equipped with a stirrer,
Charge 37.5 parts of xylene and 25 parts of n-butyl acetate, stir,
After dissolution, a carboxyl group-containing acrylic resin solution
25 parts of A1 was added and mixed at room temperature for 15 minutes. The obtained resin solution C1 had a nonvolatile content of 25.1% and a viscosity R.

Comparative Production Example C2 CAB-531-1 (supra) 12.5 in a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas introduction device and dropping funnel.
Part, Solvesso 100 (previously mentioned) 12.5 parts, xylene 16.4 parts were charged, and heated and stirred under a nitrogen gas atmosphere, and CAB-531-1.
When (the above) was dissolved and reached 140 ° C, 12.5 parts of a mixed solution of a monomer component and a polymerization initiator having the composition shown in Production Example A1 of a carboxyl group-containing acrylic resin solution was added dropwise at a constant temperature of 140 ° C. It was added at a constant rate from the funnel in 2 hours. 30 minutes after the end of dropping, tertiary butyl peroxybenzoate 0.1
And 2.5 parts of xylene were added dropwise. 90 minutes thereafter 1
Hold at 40 ℃, 20.4 parts xylene, n-butyl alcohol
7.8 parts and ethyl acetate 15.3 parts were added, cooled and the contents were taken out. The obtained resin solution C2 had a nonvolatile content of 24.7% and a viscosity RS.

Comparative Preparative Example C3 CAB-531-1 (supra) 16 in a reactor similar to Comparative Preparative Example C2.
Part, xylene 19 parts were charged and the temperature was gradually raised to CAB-531-
After confirming that 1 (above) was dissolved, 4 parts of monobutyl maleate, 0.04 part of dibutyltin oxide, 1 part of xylene
Part was charged from a dropping funnel, under the temperature condition of 145 ~ 150 ℃,
The mixture was heated and stirred under a nitrogen gas atmosphere for 7 hours. After the reaction,
50 parts of toluene and 9.96 parts of methyl isobutyl ketone were added for dilution, and the contents were taken out after cooling. Furthermore, 41.7 parts of this resin solution, 4.2 parts of toluene, 4.2 parts of methyl isobutyl ketone.
Part of the mixture was charged, and a mixed liquid of the following monomer components and a polymerization initiator was added dropwise at a constant rate of 3 hours from a dropping funnel at 105 ° C. under a nitrogen gas atmosphere. After the dropping was completed, a mixed solution of 0.2 parts of tertiary butyl peroxy 2-ethylhexanoate and 7.6 parts of toluene was added dropwise at a constant rate for 60 minutes. 90 ° C for 90 minutes after completion of dropping
After cooling, the contents were taken out after cooling.

Styrene 4.2 parts Methyl methacrylate 20.3 parts N-butyl methacrylate 10.8 parts 2-Hydroxyethyl methacrylate 5.3 parts Acrylic acid 1.2 parts Tertiary butyl peroxy 2-ethylhexanoate
0.3 parts Total 42.1 parts A resin solution C3 is non-volatiles 50.5%, a viscosity of Z ₁ -Z _2.

Comparative Production Examples C4 to C8 Resin solutions were prepared in the same manner as in Production Example B1 of acrylic modified cellulose derivative solution with the formulations of Comparative Production Examples C4 to C8 shown in Table 3. The characteristic values of the resulting resin solutions C4 to C8 are shown in Table 3.

D. Production of Acrylic Resin Solution for Clear Coat A reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen introducing pipe and a dropping funnel, 30 parts of Solvesso 100 (described above),
6 parts of n-butyl alcohol was charged and heated in a nitrogen gas atmosphere, and when the temperature reached 140 ° C., a mixed solution of a monomer component and a polymerization initiator shown below was kept at 140 ° C. under a constant temperature from a dropping funnel. It was added dropwise at a constant rate over time.

Styrene 18.0 parts 2.0 parts tertiary butyl peroxy benzoate 1.7 parts Total 61.7 parts dropping was completed 30 minutes after methacrylate n- methyl 11.8 parts lauryl methacrylate 18.5 parts 2-hydroxyethyl methacrylate 9.7 parts of methacrylic acid, tertiary butyl peroxy A mixed solution of 0.3 part of benzoate and 2 parts of Solvesso 100 (described above) was added dropwise, and the mixture was heated and stirred at 140 ° C. for 90 minutes. After the reaction was completed, the contents were taken out after cooling. The obtained resin solution D had a nonvolatile content of 60.5% and a viscosity VW.

E. Production of acrylic resin solution for base coat 49.6 parts of xylene was charged into a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing pipe and a dropping funnel, and heated and stirred while introducing nitrogen gas, 140 ° C. At this point, a mixed solution of a monomer component and a polymerization initiator having the composition shown below was added dropwise at a constant rate from a dropping funnel at 140 ° C. for 2 hours.

Was stirred for 2 hours styrene 5.0 parts methyl methacrylate 22.3 parts of acrylic acid n- butyl 15.6 parts of methacrylic acid 2 0.8 parts of hydroxyethyl 6.4 parts of acrylic acid tertiary butyl peroxy benzoate 0.3 parts Total 50.4 parts after dropping 140 ° C.. After completion of the reaction, the mixture was cooled and the contents were taken out. The obtained resin solution E has a nonvolatile content of 50.5
% And viscosity W-X.

Example 1 a. Preparation of metallic base coating material Using the acrylic modified cellulose derivative solution B1 and the base coating acrylic resin solution E, a metallic base coating material 1 of Example 1 was prepared according to the formulation shown in Table 4.

b. Preparation of clear paint Using acrylic resin solution D for clear coat, a clear paint was prepared with the following composition.

Clear coat Acrylic resin solution D 69.9 parts Uban 166-60 (supra) 30.0 parts Modaflow (supra) 0.1 parts Total 100.0 parts c. Dull steel plate of the coating film thickness of 0.8mm was subjected to forming zinc phosphate treatment And cationic electrodeposition paint (trade name: Aqua No. 4200, NOF Corporation)
17) by electro-deposition so that the dry coating film thickness is about 20 μm.
Bake at 5 ° C for 25 minutes, and then paint for intermediate coating (trade name Epico No.
1500CP sealer, manufactured by NOF CORPORATION, dry film thickness approx. 40
Toluene: Solvesso 100: n-on a test plate that had been air-spray coated to a size of μm and baked at 140 ° C for 30 minutes.
In a solvent mixed with butyl alcohol in the ratio of 7: 2: 1,
The metallic base paint 1 of the above-mentioned a, whose viscosity was adjusted to 14 seconds (20 ° C.) with Ford cup # 4, was applied in an interval of 1 minute and 30 seconds in two stages so that the dry coating film thickness was about 15 μm. The coating was performed with an electrostatic coating machine Auto REA (trade name, manufactured by Randsburg Japan Co., Ltd.) at an atomization pressure of 2.8 kg / cm ² . The atmosphere of the booth during painting was maintained at a temperature of 25 ° C and a humidity of 75%. After setting for 3 minutes, Solvesso 100
(Above): Solvesso 150 (above) was mixed at a ratio of 2: 1 to a Ford cup # 4, and the viscosity was adjusted to 30 seconds (20 ° C.) in the clear paint of b) above with the metallic paint of a) above. Paint under the same conditions as Base Paint 1 to a dry coating thickness of approximately 35 μm, set for 10 minutes, and then at 140 ° C for 3
Bake for 0 minutes. The performance of the obtained coating film is shown in Table 4.

(Note 1) Acrylic resin solution E for base coat (Note 2) Mitsui Toatsu Chemical Co., Ltd., melamine resin, solid content
60%, trade name (Note 3) Toyo Aluminum Co., Ltd., aluminum pigment, trade name (Note 4) Novo Palm Red F-3RK-70 (Hoechst, monoazo pigment, trade name) 12.9 parts, for base coat A paste in which 64.3 parts of acrylic resin solution E, 11.4 parts of xylene, and 11.4 parts of ethylene glycol monobutyl ether acetate were placed in an attritor and dispersed for 24 hours.

(Note 5) Cyanine Blue 4940 (manufactured by Dainichiseika Kogyo Co., Ltd.,
Cyanine blue pigment, trade name) A paste made with the same composition and conditions as Note 4, except that 12.9 parts of Cyanine Blue pigment was used instead of Novopermlet F-3RK-70.

(Note 6) Leveling agent manufactured by Monsanto Co., Ltd., trade name (Note 7) “(acrylic modified cellulose derivative + acrylic resin)” means “vehicle component excluding crosslinking agent based on solid content weight”.

(Note 8) Visual metallic feeling. The evaluation is as follows.

⊚: Very good O: Excellent Δ: Slightly inferior ×: Inferior (Note 9) Visual smoothness. Evaluation is the same as Note 8.

(Note 10) Visual unevenness of metal. Evaluation is the same as Note 8.

(Note 11) According to JIS K 5400 6.7 60 degree specular gloss.

(Note 12) According to JIS K 5400 6.7 60 degree specular gloss.

(Note 13) Idemitsu high octane gasoline soaked at 20 ° C for 24 hours. The evaluation is as follows.

◯: No abnormality Δ: Tingle generation ×: Tingle discoloration generation Examples 2 to 21 In the same manner as in Example 1-a, the metallic base coatings 2 to 19 of Examples 2 to 19 and the formulations shown in Table 4 were used. The solid color base paints 20 and 21 of Examples 20 and 21 were prepared, and the coating films of Examples 2 to 21 were formed in the same manner as in Example 1-c.

The performance of the obtained coating film is shown in Table 4.

Comparative Examples 1 to 7 Comparative Example metallic base coatings 1 to 7 of Comparative Examples 1 to 7 were prepared in the same manner as in Example 1-a by using the resin solutions of Comparative Production Examples and the formulations shown in Table 5. The coating films of Comparative Examples 1 to 7 were formed in exactly the same manner as 1-c.

The performance of the obtained coating film is shown in Table 5.

From the results shown in Table 4, the coating composition of each example has a good metallic feeling, smoothness, good gloss, no metallic unevenness, an excellent coating appearance, and excellent coating performance. On the other hand, as shown in Table 5, Comparative Example 1 in which the cellulose derivative was used without modification, and Comparative Example 2 in which the acrylic monomer was reacted in the presence of the cellulose derivative and modified (Japanese Patent Publication No. 60-23792).
No.) and Comparative Example 3 (corresponding to JP-A-60-252664), Comparative Example 4 in which the modified cellulose derivative exceeds 70% by weight and carboxyl group-containing acrylic resin is less than 30% by weight, and 5% in the cellulose derivative. Comparative Example 5 in which the acrylic acid resin containing a carboxyl group exceeds 95% by weight, Comparative Example 6 in which the resin acid value of the acrylic resin containing a carboxyl group is less than 10 mgKOH / g, and Comparative Example 7 in which the weight average molecular weight is less than 8000 are In all cases, the metallic appearance and smoothness are poor, the coating appearance is poor due to metal unevenness, and the coating performance such as gasoline resistance is poor. In addition, Comparative Production Example C7 in which the resin acid value of the carboxyl group-containing acrylic resin to be reacted exceeds 80 mgKOH / g cannot be used because it becomes insoluble during the reaction.

From the above results, it is understood that the coating composition of the present invention can provide excellent appearance and coating film performance.

Claims (4)

[Claims] 1. An acrylic modified cellulose derivative obtained by reacting 5 to 70% by weight of a cellulose derivative and 30 to 95% by weight of a carboxyl group-containing acrylic resin having a resin acid value of 10 to 80 mg KOH / g and a weight average molecular weight of 8,000 to 80,000. And a crosslinking agent as a vehicle component. 2. The coating composition according to claim 1, wherein the vehicle component further contains another coating film forming resin. 3. The coating composition according to claim 1 or 2, wherein the ratio of the vehicle component excluding the crosslinking agent / the crosslinking agent is in the range of 60/40 to 90/10. 4. The coating composition according to any one of claims 1 to 3, wherein the crosslinking agent is a methylated melamine resin, a butylated melamine resin, a polyisocyanate compound, or a blocked isocyanate compound.