JPS63137967A - Coating compound composition - Google Patents

Abstract

PURPOSE:To obtain a coating compound composition suitable especially for base coating of two coating and one baking coating type, having excellent appearance of coating film and film performance, containing a specific acrylic modified cellulose derivative and a crosslinking agent as vehicle components. CONSTITUTION:The aimed composition containing (A) an acrylic modified cellulose derivative obtained by reacting (i) 5-70wt% cellulose derivative (preferably cellulose acetate butyrate) with (ii) 30-95wt% carboxyl group-containing acrylic resin having 10-80mgKOH/g resin acid value and 8,000-80,000 weight average molecular weight and (B) a crosslinking agent (preferably methylated melamine resin, butylated melamine resin, polyisocyanate compound or blocked isocyanate compound) in a ratio of the component A/B of 60/30-90/10 as vehicle components.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a coating composition with excellent coating film appearance and coating performance;
In particular, the present invention relates to a coating composition suitable for a base coat of a two-coat, one-bake coating system.

[Conventional technology]

BACKGROUND ART A two-coat, one-bake coating system is widely used as a top coat for automobiles, etc. as a coating composition that provides excellent coating film appearance and coating performance.

2-coat 1-bake painting includes metallic paint that uses metallic paint containing metal powder such as aluminum powder as the base coat paint, and solid color paint that uses solid color paint that does not contain metal powder and is made of colored pigment and binder. There is. In metallic painting, the arrangement of the metal powder contained in the base coat paint in the paint film, and the difference between the base coat and clear coat when the clear coat paint is applied without baking after the base coat paint is applied. Layer-forming properties (the state in which two layers are formed at the interface between the base coat and the clear coat without compatibility) have a large effect on the appearance of the coating film. Even in solid color coatings, the ability to form two layers, the base coat and clear coat, has a large effect on the appearance of the paint film.

Conventionally, as a method to control the above-mentioned arrangement of metal powders and the ability to form two layers of base coat and clear coat, the viscosity of the base coat film was rapidly increased after the base coat paint was applied and before the clear coat paint was applied. Relatively high molecular weight resins are used as vehicles to prevent powder movement and make clear coat paints less compatible when applied, or highly volatile solvents are used in base coat paints. It is being said.

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

In order to compensate for this drawback, a method is known in which a cellulose derivative is blended into a base coat paint. A paint blended with a cellulose derivative has a large increase in viscosity after application, and is advantageous for arranging metal powder and forming two layers of base coat and clear coat. However, cellulose derivatives generally have poor compatibility with acrylic resins or amino resins with which they are blended, and therefore have drawbacks such as clouding of paints or coatings and easy separation during storage.

As a method to compensate for these drawbacks, it has been proposed to use a resin obtained by graft polymerization of an acrylic resin and a cellulose derivative as a vehicle (for example, Japanese Patent Publication No. 60-23
792, JP-A No. 60-252664) 6 [Problems to be Solved by the Invention] However, although these graft polymer resins have improved compatibility with acrylic resins or amino resins, the appearance of the coating film is There was a problem that the improvement was only slightly, and the gasoline resistance was also inferior.

Although these graft polymer resins have improved compatibility with acrylic resins or amino resins,
The reason for the lack of noticeable effects on the appearance of the paint film and the poor gasoline resistance is that during the graft polymerization of cellulose derivatives and acrylic resins, the acrylic monomer is reacted in the cellulose derivative solution, so it does not graft polymerize with the cellulose derivatives. Low molecular weight acrylic resin is produced,
Due to the presence of this low molecular weight acrylic resin, when a clear coat paint is applied after the base coat paint is applied, a portion of the base coat and clear coat become compatible, reducing gloss and causing metal unevenness due to the movement of metal powder. This is thought to cause a deterioration in the appearance of the paint film.

When acrylic monomers are reacted in a cellulose derivative solution, a low molecular weight acrylic resin is produced because the radicals of the low molecular weight acrylic resin that started polymerization move to the cellulose derivative and stop the polymerization while maintaining a low molecular weight. It is speculated that it was meant to be stored away.

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

[Means for solving problems]

The present invention has a cellulose derivative of 5 to 70% by weight, a resin acid value of 10 to 80 mgKOH/g, and a weight average molecular weight of 80.
00 to 80,000 carboxyl group-containing acrylic resin 3
This is a coating composition characterized in that it contains an acrylic modified cellulose derivative obtained by reacting 0 to 95% by weight and a crosslinking agent as vehicle components.

Examples of cellulose derivatives used in the present invention include cellulose esters such as cellulose acetate butyrate, cellulose acetate, and cellulose acetate propionate. From the viewpoints of solubility and viscosity, cellulose acetate butyrate is preferred, particularly those having a degree of acetylation of 1 to 34% by weight, a degree of butyrylation of 16 to 60% by weight,
It is more effective that the viscosity is in the range of 0.005 to 5 seconds, preferably 0.01 to 2 seconds as measured by the measurement method described in ASTM-D-1343154. A specific example of such cellulose acetate butyrate is CAB-551 manufactured by Eastman Chemical Products.
-0,01,CAB-551-0,2,CAB-531
-1, CAB-500-1, CAB-381-0,1,
There are CAB-381-0, 5, CAB-381-2 (both are trade names), and the like.

Next, the carboxyl group-containing acrylic resin to be reacted with the above cellulose derivative contains a monomer having a polymerizable ethylenically unsaturated bond and a carboxyl group, and a monomer having other ethylenically unsaturated bonds that can be polymerized with these monomers. It is obtained by polymerizing one or more of the following compounds by a conventional method.

Examples of the monomer having an ethylenically unsaturated bond and a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, and crotonic acid. Other monomers that can be polymerized with these 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, etc. Alkyl or cycloalkyl ester of number 1 to 24; acrylic acid or methacrylic acid having 2 carbon atoms such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc.
-24 hydroxyalkyl esters; styrenic monomers such as styrene, vinyltoluene, and α-methylstyrene; or acrylonitrile, methacrylonitrile, and the like.

The above carboxyl group-containing acrylic resin has a resin acid value of 10 to 80 mgKOH/g and a weight average molecular weight of 8,000 to 80,000, preferably 10,000 to 8
0000 is suitable. Resin acid value is 10mgKO
If the acid value is less than 80 mgKOH/g, the reaction with the cellulose derivative will not be sufficient, and the resulting acrylic-modified cellulose derivative will have insufficient compatibility with acrylic resins and amino resins. , the solubility of the acrylic resin decreases, and the reaction product becomes insolubilized, making it difficult to use. If the weight average molecular weight is less than 8,000, the resulting acrylic-modified cellulose derivative will contain a low molecular weight acrylic resin, so when used in a base coat paint, some parts of the base coat and clear coat will be miscible when the clear coat is applied. This causes a decrease in the appearance of the coating film, such as a decrease in gloss and metal unevenness due to the movement of metal powder. Even if the weight average molecular weight exceeds goooo, no significant effect is observed on the appearance or performance of the coating film, and handling becomes difficult. Therefore, it is not necessary to use a material whose weight average molecular weight exceeds aoooo.

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 based on the total amount of the cellulose derivative and the carboxyl group-containing acrylic resin. , and react by mixing within this range. If the cellulose derivative is less than 5% by weight and the carboxyl group-containing acrylic resin is more than 95% by weight, no significant effect on the appearance and performance of the coating film will be observed even when used in a base coat paint. In addition, if the cellulose derivative exceeds 70% by weight and the carboxyl group-containing acrylic resin exceeds 30% by weight, the amount of acrylic modification of the cellulose derivative will be small and the compatibility with the acrylic resin or amino resin will deteriorate, resulting in an excellent coating film. It becomes difficult to obtain good appearance and film 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.

The esterification reaction catalyst used includes dibutyltin oxide, dioctyltin oxide, dibutyltin dilaurate, dioctyltin dilaurate, sodium methylate, sodium ethylate, zinc octylate, calcium acetate, antimony oxide, tetraisopropyl titanate, tetrabutyl titanate, etc. can give. Examples of reaction solvents include benzene, toluene, xylene, and aromatic solvents with a boiling point of 150 to 200°C, such as Exxon's Tsurpetz 100 and Tsurpetz 150 (all trade names), methyl ethyl ketone, methyl isobutyl ketone,
One or more solvents such as ketone solvents such as methyl amyl ketone, diisobutyl ketone, 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 vehicle for a coating composition, especially a basecoat in a two-coat, one-bake coating system. In the present invention, in addition to the above-mentioned acrylic modified cellulose derivative and crosslinking agent, other film-forming resins such as acrylic resins and polyester resins may be added as vehicle components. Examples of the crosslinking agent used here include amino resins such as methylated melamine resins and butylated melamine resins, as well as polyisocyanate compounds, blocked isocyanate compounds, and the like. In this case, the ratio of vehicle components and crosslinking agent excluding the crosslinking agent is:
It is preferable to combine them so that the vehicle component/crosslinking agent ratio excluding the crosslinking agent is in the range of 60/40 to 90/10 based on solid weight.

The coating composition of the present invention includes, in addition to the above-mentioned acrylic modified cellulose derivative, crosslinking agent, and vehicle components such as acrylic resin and polyester resin, various solvents, metallic pigments,
Colored pigments, dyes, fillers as well as e.g. Modaflow (
A surface conditioner such as Leveling Agent (trade name, manufactured by Monsando, Inc., USA) can also be blended. Examples of metallic pigments include metal powders such as aluminum powder, copper powder, and bronze powder, as well as titanium dioxide coated mica, mica-like iron oxide, nickel sulfide powder, cobalt sulfide powder, manganese sulfide powder, and titanium nitride powder. Examples of pigments and dyes include metal oxides commonly used for paints,
Metal hydroxide, metal powder, metal sulfide, sulfate, carbonate,
These include salts such as lead chromate, carbon black, organic pigments, and organic dyes.

Although the coating composition of the present invention is suitable as a base coat for a two-coat, one-bake coating system, it can also be used in other coating compositions.

The coating composition of the present invention can be coated by conventional methods such as air spray coating, electrostatic air spray coating, and electrostatic atomization coating.

When the paint composition of the present invention is used as a base coat paint, after the coating is applied as described above, a clear coat paint is applied over it without baking.

The clear coat paint used here is preferably one based on thermosetting acrylic resin, and from among the paints based on a combination of a functional acrylic copolymer and a crosslinking agent, it is possible to select a metallic base paint. A material having good interlayer adhesion and good weather resistance can be appropriately selected and used.

Among them, a transparent paint based on 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, depending on the required performance of the coating system, it is also possible to use other thermosetting resin-based top clear coat paints, such as paints containing amino-alkyd resin as a main component.

〔Effect of the invention〕

According to the present invention, since the acrylic modified cellulose derivative is contained as a vehicle component, excellent coating film appearance and coating film performance can be obtained, and in particular, by using it as a base coat paint of a 2-coat, 1-bake coating system, it is possible to achieve unprecedented A coating film with excellent coating appearance and coating performance can be obtained, and is particularly useful as a top coating for automobiles and the like.

〔Example〕

The present invention will be explained below with reference to Examples, Comparative Examples, and Production Examples.

In each example, parts and percentages indicate parts and percentages by weight.

A. Production of carboxyl group-containing acrylic resin solution Production example A1 49.7 parts of xylene was charged into a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction device, and a dropping funnel, and heated while introducing nitrogen gas. The mixture was stirred, and when the temperature reached 140°C, a mixture of monomer components and a polymerization initiator shown below was added dropwise at a constant rate from a dropping funnel over 2 hours under a 140°C window.

Styrene: 5.0 parts Methyl methacrylate: 24.5 parts After that, it was cooled and the contents were taken out. The obtained carboxyl group-containing acrylic resin solution A1 had a non-volatile content of 50.0%, a viscosity of -W, and was measured by GPC method (as a measuring device, Toyo Soda Kogyo Co., Ltd., Anal C-802A).
The weight average molecular weight measured using (product name) (weight average molecular weight measurement method based on polystyrene standards) is 3.8 x 1
It was 0'.

Production Examples A2 to A15 Carboxyl group-containing acrylic resin solutions A2 to A15 were obtained in the same manner as in Production Example A1 with the formulations shown in Table 1. The characteristic values of the obtained resin solutions A2 to A15 are determined as resin solution A.
1 and shown in Table 1.

B. Production example B of acrylic modified cellulose derivative solution
1 25 parts of carboxyl group-containing acrylic resin solution A1, C
AB-531-1 (previous cellulose acetate butyrate) 12.5 parts, Tsurpetz 100 (previous aromatic petroleum solvent) 12.5 parts, dibutyltin oxide 0.1 part, stirrer, thermometer, reflux condenser, The mixture was charged into a reactor equipped with a nitrogen introduction tube and a Dean-Stark trap, and the reaction was carried out at a temperature of 150 to 155° C. for 5 hours under a nitrogen gas atmosphere. After the reaction was completed, 26.8 parts of xylene, 7.8 parts of n-butyl alcohol, and 15.3 parts of ethyl acetate were added to dilute the mixture, and after cooling, the contents were taken out. Resin solution B1 obtained
had a nonvolatile content of 24.8% and a viscosity of S.

Production Examples B2 to B19 Acrylic modified cellulose derivative solutions 82 to B19 were obtained with the formulations shown in Table 2 by the same method as in Production Example B1 described above. The characteristic values of the obtained resin solution are shown in Table 2 together with resin solution B1.

Manufacture of C0 comparative resin liquid Comparative manufacturing example C1 CAB-531-1 (described above) in a mixer equipped with a stirrer
12.5 parts, xylene 37.5 parts, n-butyl acetate 25
After stirring and dissolving 1 part, 25 parts of carboxyl group-containing acrylic resin solution A1 was added and mixed for 15 minutes at room temperature. The resulting resin solution C1 has a nonvolatile content of 25.1%.
, viscosity R.

Comparative Production Example C2 In a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction device, and a dropping funnel, 12.5 parts of CAB-531-1 (mentioned above) and 12.5 parts of Tsurpetz 100 (mentioned above) were added.
and 16.4 parts of xylene were heated and stirred under a nitrogen gas atmosphere to dissolve CAB-531-1 (mentioned above) and give 16.4 parts of xylene.
When the temperature reached 40°C, 12.5 parts of the mixture of the monomer components and polymerization initiator having the composition shown in Production Example A1 of the carboxyl group-containing acrylic resin solution was poured into the dropping funnel at 140°C under a window for 2 hours. It was dropped at a uniform rate. Thirty minutes after the completion of the dropwise addition, a mixed solution of 0.1 part of tertiary-butyl peroxybenzoate and 2.5 parts of xylene was added dropwise. After that 90 minutes 14
The mixture was maintained at 0°C, 20.4 parts of xylene, 7.8 parts of n-butyl alcohol, and 15.3 parts of ethyl acetate were added, cooled, and the contents were taken out. The resulting resin solution C2 had a nonvolatile content of 24.7% and a viscosity of R-8.

Comparative Production Example C3 CAB-531-1,
After charging 16 parts of (above) and 19 parts of xylene and gradually raising the temperature to confirm that CAB-531,-1 (above) had dissolved, 4 parts of monobutyl maleate and 0.04 part of dibutyltin oxide were added. , 1 part of xylene was charged from the dropping funnel, and the mixture was heated and stirred at a temperature of 145 to 150° C. under a nitrogen gas atmosphere for 7 hours. After the reaction was completed, 50 parts of toluene and 9.96 parts of methyl isobutyl ketone were added to dilute the mixture, and after cooling, the contents were taken out. Furthermore, 41.7 parts of this resin solution, 4.2 parts of toluene, and 4.2 parts of methyl isobutyl ketone were charged, and a mixed solution of the following monomer components and polymerization initiator was added dropwise under a window at 105°C under a nitrogen gas atmosphere. The mixture was added dropwise from the funnel at a constant rate over 3 hours. After completing the dropwise addition, 0.2 parts of tert-butylperoxy 2-ethylhexanoate and 7 parts of toluene were added.
6 parts of the mixture was added dropwise at constant speed over 60 minutes. 90 minutes after completion of dripping
The temperature was maintained at 105° C. for minutes, and 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 Total
The resin solution C3 obtained in 42.1 parts had a non-volatile content of 50.5% and a viscosity of 2□.
-22.

Comparative Production Examples 04 to C8 Resin solutions were prepared using the formulations of Comparative Production Examples 04 to C8 shown in Table 3 in the same manner as Production Example B1 of the acrylic modified cellulose derivative solution. Table 3 shows the characteristic values of the obtained resin solutions C4 to C8.

D. Stirrer for producing acrylic resin solution for clear coat;
Into a reactor equipped with a thermometer, a reflux condenser, a nitrogen introduction tube, and a dropping funnel, 30 parts of Tsurpetz 100 (above), n-
6 parts of butyl alcohol was charged, heated under a nitrogen gas atmosphere, and when the temperature reached 140°C, a mixture of monomer components and a polymerization initiator with the composition shown below was poured into the dropping funnel at a constant temperature of 140°C for 2 hours. It was dropped at a uniform rate.

Styrene 18.0 parts n-butyl methacrylate 11.8 parts Lauryl methacrylate 18.5 parts 2-hydroxyethyl methacrylate 9.7 parts Methacrylic acid 2.0 parts Total
Thirty minutes after the completion of dropping 61.7 parts, a mixed solution of 0.3 parts of tertiary-butyl peroxybenzoate and 2 parts of Tsurupetz 100 (mentioned above) was added dropwise, and the mixture was heated and stirred at a constant temperature of 140°C for an additional 90 minutes. After the reaction was completed, it was cooled and the contents were taken out. The resulting resin solution had a nonvolatile content of 60.5% and a viscosity of V-W.

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 introduction tube, and a dropping funnel, and heated and stirred while introducing nitrogen gas. When the temperature reaches ℃, add 1 part of the mixture of monomer components and polymerization initiator as shown below.
The mixture was added dropwise at a constant rate of 2 hours from a dropping funnel at a constant temperature of 40°C.

Styrene 5.0 parts Methyl methacrylate 22.3 parts n-Butyl acrylate 15.6 parts 2-Hydroxyethyl methacrylate 6.4 parts Acrylic acid 0.8 parts Total
After dropping 50.4 parts, the mixture was stirred at 140°C for 2 hours. After the reaction is completed, cool
I took out the contents. The resulting resin solution E has a nonvolatile content of 5
The viscosity was 0.5% and the viscosity was W-x.

Example 1 a. Preparation of metallic base paint Metallic base paint 1 of Example 1 was prepared using acrylic modified cellulose derivative solution B1 and base coat acrylic resin solution E according to the formulation shown in Table 4.

b. Preparation of clear paint A clear paint was prepared using an acrylic resin solution for clear coating with the following formulation.

Acrylic resin solution D for clear coat 69.9 parts Kneepan 166-60 (mentioned above)
30.0 parts total 100.0 parts Formation of C0 coating film On a dull steel plate with a thickness of 0.8 mm that has been subjected to zinc phosphate treatment,
A cationic electrodeposition paint (trade name Aqua No. 4200, Nippon Oil & Fats Co., Ltd. vl) was electrodeposited to a dry film thickness of approximately 20 μm, baked at 175°C for 25 minutes, and an intermediate coat (trade name Epico NcL1500CP) was applied. A test board was air-sprayed with sealer (manufactured by NOF Corporation) to a dry film thickness of approximately 40 μm and baked at 140°C for 30 minutes, and then a mixture of toluene:Solvesso 100:n-butyl alcohol in a ratio of 7:2 was applied. The metallic base paint 1 of the above a was adjusted to have a viscosity of 14 seconds (20°C) using a Ford cup #4 using a solvent mixed in a ratio of 1:1, and was dried in two stages at intervals of 1 minute and 30 seconds. The coating was applied to a thickness of approximately 15 μm. Painting is done using electrostatic paint machine Auto REA
(manufactured by Nippon Landsburg Co., Ltd., trade name) with atomization pressure of 2.8
It was carried out in kg/a#. The atmosphere in the booth during painting is at a temperature of 2.
It was maintained at 5°C and humidity 75%. After setting for 3 minutes, use a 2:1 mixture of Tsurupetz 100 (mentioned above) and Tsurupetz 150 (mentioned above) in a solvent containing Ford Cup #.
The above clear paint whose viscosity was adjusted to 30 seconds (20°C) in step 4 was applied under the same conditions as the metallic base paint in step a above to a dry film thickness of about 35 μm,
After setting for 10 minutes, it was baked at 140°C for 30 minutes. Table 4 shows the performance of the resulting coating film.

(Note 1) Acrylic resin solution E for base coat (Note 2) Manufactured by Mitsui Toatsu Chemical Co., Ltd., melamine resin, solid content 60%, product name (Note 3) Manufactured by Toyo Aluminum Co., Ltd., aluminum pigment, product name ( Note 4) Novobalm Red F-3RK-70 (manufactured by Hoechst, monoazo pigment, trade name) 12.9 parts, acrylic resin solution E for base coat 64.3 parts, xylene 1
1.4 parts of ethylene glycol monobutyl ether acetate and 11.4 parts of acetic acid ethylene glycol monobutyl ether were charged into an attritor and dispersed for 24 hours.

(Note 5) Cyanine Blue 4940 (manufactured by Dainichiseika Kagyo Co., Ltd., cyanine blue pigment, trade name) Same as Note 4 except that 12.9 parts was used instead of Novo Palmlet F-3RK-70. Paste made with composition and conditions.

(Note 6) Manufactured by Monosand, leveling agent, product name (Note 7)
) "(Acrylic modified cellulose derivative + acrylic resin)
'' means ``vehicle components, excluding crosslinking agent, based on solids weight''.

(Note 8) Metallic appearance by visual inspection. The evaluation is as follows.

◎：Excellent 0: Excellent Δ: Slightly inferior ×: Inferior (Note 9) Smoothness by visual inspection. The evaluation is the same as Note 8.

(Note 10) Metal unevenness by visual inspection. The evaluation is the same as Note 8.

(Attention) JIS K 54006.760 degree specular gloss.

(Note 12) Based on JIS K 54006.760 degree specular gloss.

(Note 13) Idemitsu high octane gasoline immersion 20”C24
time. The evaluation is as follows.

O: No abnormality Δ: Occurrence of blister
Solid color base paints 20.21 of Example 9 and Example 20.21 were prepared, and coatings of Examples 2-21 were formed in exactly the same manner as in Example 1-c.

Table 4 shows the performance of the resulting coating film.

Comparative Examples 1 to 7 Using the resin solutions of Comparative Production Examples, Comparative Metallic Base Paints 1 to 7 of Comparative Examples 1 to 7 were prepared according to the formulations shown in Table 5 in the same manner as in Example 1-a, and Coating films of Comparative Examples 1 to 7 were formed in exactly the same manner as 1-c.

Table 5 shows the performance of the resulting coating film.

From the results in Table 4, the coating compositions of each example have good metallic feel, smoothness, good gloss, no metal unevenness, excellent coating appearance, and excellent coating performance. On the other hand, as shown in Table 5, Comparative Example 1 used a cellulose derivative without modification, and Comparative Example 2 modified by reacting an acrylic monomer in the presence of a cellulose derivative (Japanese Patent Publication No. 60-23
No. 792) and Comparative Example 3 (JP-A No. 60-252)
664), Comparative Example 4 in which the cellulose derivative to be modified exceeds 70% by weight and the carboxyl group-containing acrylic resin is less than 30% by weight, the cellulose derivative is less than 5% by weight and the carboxyl group-containing acrylic resin is 95% by weight. Comparative Example 5, in which the resin acid value of the carboxyl group-containing acrylic resin was less than 10 mgKOH/g, and Comparative Example 7, in which the weight average molecular weight was less than 8000, all had a metallic feel, poor smoothness, and metal unevenness. The appearance of the paint film is poor, and the film performance such as gasoline resistance is also poor. In addition, the resin acid value of the carboxyl group-containing acrylic resin to be reacted is 80.
Comparative Production Example C7, which exceeds mgKOH/g, becomes insoluble during the reaction and cannot be used.

From the above results, it can be seen that excellent appearance and film performance can be obtained with the coating composition of the present invention.

Claims (4)

[Claims] (1) Cellulose derivative 5-70% by weight, resin acid value 10-80mgKOH/g, weight average molecular weight 8000
~80,000 carboxyl group-containing acrylic resin 30~
A coating composition comprising, as a vehicle component, an acrylic-modified cellulose derivative obtained by reacting 95% by weight of an acrylic modified cellulose derivative and a crosslinking agent. (2) The coating composition according to claim 1, wherein the vehicle component further contains another film-forming resin. (3) The vehicle component/crosslinking agent ratio excluding the crosslinking agent is 6
Claim 1 in the range of 0/40 to 90/10
The coating composition according to item 1 or 2. (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.