JPS6131473A - Paint composition - Google Patents

Abstract

PURPOSE:To provide a paint composition containing a vinyl-modified chlorinated polyolefin, a specific oil-free or fatty acid-modified alkyd resin and a polyisocyanate compound as a binder, and suitable for the one-coat painting of a nonpolar plastic material. CONSTITUTION:The objective composition contains a binder composed mainly of (A) a vinyl-modified chlorinated polyolefin, (B) an oil-free or fatty acid-modified alkyd resin having a composition falling on the lines defined by the points (0.6, 20), (0.6, 100), (1.00, 30) and (1.00, 100) or within the quadrangle defined by the above lines, wherein the abscissa is the dibasic acid ratio defined by dividing (i) the total molar number of the polybasic acid component (>=30mol% of the polybasic component is saturated alicyclic polybasic acid) by (ii) the total molar number of polyhydric alcohol component, and the ordinate is the molar number of >=3C glycol component in the polyhydric alcohol component, and (C) a polyisocyanate compound.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition, and more particularly to a coating composition that has the functions of both an undercoat and a topcoat in one coat, and which exhibits remarkable effects particularly when applied to non-polar plastics. It is something that takes place in between.

In recent years, plastics have been increasingly used in place of metals for parts of automobiles, automobiles, and home appliances, and among these, polyolefin-based plastics are often used due to their price, strength, and other aspects. . however,
Even if parts made of polyolefin plastics are coated with paint to give them cosmetic properties, they have the drawback of poor adhesion to the paint film because they are non-polar.

To date, various research has been conducted to develop paints with excellent adhesion to polyolefin plastics.
Mixture of chlorinated polypropylene and acrylic resin; (1) mixture of chlorinated polypropylene, hydroxyl group-containing acrylic resin and incyanate compound; and (2) grafting of chlorinated polypropylene onto hydroxyl group-containing acrylic fR resin.1. Paints made from resins and isocyanate compounds have already been proposed. However, although an improvement in adhesion was observed, (1) cannot be applied to beards due to poor weather resistance and solvent resistance, and the compatibility of the components (2) and (2) is poor. Due to the high glass transition temperature of acrylic resin, gloss, impact resistance, gasoline resistance, water resistance, weather resistance, etc. are inferior. However, paints suitable for polyolefin plastics have not yet been developed, as they have drawbacks such as insufficient weather resistance17.

As a result of intensive research to overcome this stiffness defect, the inventors of the present invention found that when an alkyd resin having a specific composition is used in combination with vinyl-modified chlorinated polyprene and polyisocyanate, the compatibility of each of these components increases. To obtain a coating composition which is excellent in adhesion to polyolefin, weather resistance, gasoline resistance, water resistance, impact resistance, bending resistance, and adhesion between coats (interlayer adhesion). This discovery led to the completion of the present invention.

(A) a vinyl-modified chlorinated polyolefin, (B) a polybasic acid component in which at least 3 () mol% of the polybasic acid component is a saturated ring polybasic acid, and the total polybasic acid component is Divide the number of moles by the total number of moles of the polyhydric alcohol component1. When the value (dibasic acid ratio) is plotted on the horizontal axis and the mol% of the glycol component with 3 or more carbon atoms in the polyhydric alcohol component is plotted on the vertical axis (0,6120), (
0,6,100), (1,00,30), (1,00,
100) An oil-free or fatty acid-modified alkyd composition consisting of a composition included on and within a quadrilateral line surrounded by the four points of (0) and a coating composition whose binder is a polyisocyanate compound be.

(Component: Vinyl-modified chlorinated polyolefin dough is obtained by graft-polymerizing a vinyl monomer onto a chlorinated polyolefin.The chlorinated polyolefin to which a vinyl monomer is graft-polymerized has a chlorination rate of 50% or less, preferably The polyolefin has a content of 10 to 45%, more preferably 20 to 40%. Examples of the polyolefin to be chlorinated include ethylene, phlopylene, 1-butene, and 3-methyl-
Homopolymers or copolymers of olefins selected from 1-butene, 3-methyl-1-heptene, etc., and copolymers of these olefins with vinyl acetate, butadiene, acrylic esters, methacrylic esters, etc. These chlorinations are carried out by conventional methods. Preferred examples of the chlorinated polyolefin include chlorinated polyethylene, chlorinated polypropylene, chlorinated ethylene-propylene copolymer, and chlorinated ethylene-vinyl acetate copolymer.

The vinyl monomer to be graft-polymerized to such a chlorinated polyolefin is a compound having one or more polymerizable unsaturated bonds in one molecule, and in the present invention, a part of the vinyl monomer or It is preferable to use a hydroxyl group-containing vinyl monomer so that the hydroxyl value of component (4) itself is 20 to 80, preferably 40 to 60.

Hydroxyl group-containing vinyl monomers include, for example, C2 to acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.
Examples include 3-hydroxyalkyl esters, which can be used alone or in combination of 21f or more. Vinyl monomers other than these hydroxyl group-containing vinyl monomers include the following examples.

(a) Alkyl of acrylic acid or methacrylic acid (C
1-18) Esters: For example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, ucrylic acrylate, cyclohexyl acrylate, methyl methacrylate, methacrylate ethyl acid, propyl methacrylate, isopropyl methacrylate,
Alkoxyalkyl esters of acrylic or methacrylic acid, such as butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, cyclohegycyl methacrylate, etc., such as methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxy methacrylate Ethyl, ethoxybutyl acrylate, ethoxybutyl methacrylate, etc., glycidyl acrylate or iJ-glycidyl methacrylate and C
・2-18 monocarboxylic acid compounds (e.g. acetic acid, propionic acid, oleic acid, stearic acid, lauric acid, p-
adducts with t-butylbenzoic acid, etc.). Cardula E-1
0 (a product of Shell Petrochemicals) and an unsaturated acid such as acrylic acid or methacrylic acid.

(b) Vinyl aromatic compounds: for example, styrene, σ
-Methylstyrene, vinyltoluene, p-thalolstyrene, vinylpyridine, etc.

(c) Glycidyl group-containing vinyl monomers: for example, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc.

(d) Amides of acrylic acid or methacrylic acid: for example, acrylamide, N-methylolacrylamide,
N-butoxymethylacrylamide etc.

(e) Ethylenically unsaturated monomer having an alkoxysilane group: for example, r-methacryloxytrimethoxysilane.

(f) Others: acrylonitrile, methacrylate trile, acrylic acid, methacrylic acid, maleic acid.

These vinyl monomers are appropriately selected depending on the desired physical properties, and may be used alone or in combination of two or more.

The vinyl-modified chlorinated polyolefin (component A) is obtained by graft polymerizing the vinyl monomer to the chlorinated polyolefin, and the composition ratio of both components is based on the total weight of the chlorinated polyolefin. Polyolefin is 10~
90% by weight, preferably 20-7'o% by weight, 90-10% by weight, preferably 80-30% by weight of vinyl monomer
It is.

Graft polymerization is carried out, for example, by solution polymerizing both components at 50 to 140° C. in the presence of a radical-generating polymerization initiator.

(Component B: At least 30 mol% of the polybasic acid component is a saturated alicyclic polybasic acid, and the value obtained by dividing the total number of moles of the polybasic acid component by the total number of moles of the polyhydric alcohol component (dibasic acid Ratio) is plotted on the horizontal axis as the mol% of the glycol component having 3 or more carbon atoms in the polyhydric alcohol component, (0,7,30), (0
,7,100), (1,00°40), (1,00,1
00) It is an oil-free and fatty acid-modified alkyd resin whose composition is included on and inside the quadrilateral line surrounded by the four points.

An example of a saturated alicyclic polybasic acid is
Lophthalic acid and its anhydride, Methylhexahydrophthalic acid and its anhydride, Hexahydrotrifly-nodic acid and its anhydride, Hexahydro-2-methyltrimellitic acid and its anhydride, Hexahytroti! /phthalic acid, etc.

Examples of other polybasic acids include phthalic acid and its anhydride, isophthalic acid and its dimethyl ester, terephthalic acid and its dimethyl ester, trimellitic acid and its anhydride, 2-methyltrimellitic acid and its anhydride, Aromatic polybasic acids such as pyrofurinodonic acid and its anhydride; HO with succinic acid and its anhydride, adipic acid, cepatic acid, azelaic acid, dodecanoic acid, etc.
OC(CH2)n Saturated dibasic acid represented by C0OH (n is an integer of 1 to 12); tetrahydrophthalic anhydride, (
unsaturated polybasic acids such as maleic anhydride; and the like. If an unsaturated polybasic acid is used as part of the polybasic acid component, the amount used may be limited in applications where weather resistance is important, as the unsaturated bonds within the molecule may impair the weather resistance of the coating. , for example, should be kept at 10 mol% or less of the polybasic acid component.

If the content of the saturated alicyclic polybasic acid in the polybasic acid component is less than 30 mol %, the resulting alkyd resin will have poor compatibility with component (4).

On the other hand, the polyhydric alcohol component can be comprised of those conventionally used in the formation of alkyd resins. For example, glycol components include dihydric alcohols having 2 carbon atoms such as ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, 1.2-butylene glycol, 1.3-butylene glycol, 2.3-7' Tylene glycol, ■, 4-gutylene glycol, 1,5-bentanediol, 1.6-
Hexanediol, 2.5-hexanediol, ester diol 204 (product of Union Carbide (USA))
.

Examples include dihydric alcohols having 3 or more carbon atoms, such as tricyclodecane dimetatool and 1,4-cyclohexanedimetatool. As trihydric or higher alcohols, trimethylolethane, trimethylolpropane, glycerin,
Examples include pentaerythritol, dipentaerythritol, diglycerin, and sorbitol.

The alkyd resin can be produced by condensation polymerization of a polybasic acid component containing a saturated alicyclic polybasic acid and at least one polyhydric alcohol component according to a conventional method. as, for example, benzoic acid, p t
-Butylbenzoic acid, benzoic acid methyl ester, etc. may be used to adjust the molecular weight. The reaction ratio of the above polybasic acid component with the netylcol component and the composition of each component are calculated using the dibasic acid ratio on the horizontal axis and the mol% of the glycol component having 3 or more carbon atoms in the polyhydric alcohol content on the vertical axis. , so that it is included on and within the quadrilateral line surrounded by the four points mentioned above.

Alkyd resins obtained from compositions outside the above range have poor compatibility with the (A) lit component used in combination, and cannot serve the purpose of the present invention.

In addition, the fatty acids (including glycerides) used for modification are saturated or unsaturated fatty acids with 6 to 30 carbon atoms, preferably 12 to 22 carbon atoms, and especially those with a high iodine value tend to reduce weather resistance. Therefore, it is preferable to use fatty acids with an iodine value of 20 or less, such as coconut oil fatty acids.

In the present invention, the fatty acid content in the fatty acid-modified alkyd resin that can be used as the component (81) is preferably 50% or less, including the oil length.

(Component Q: A compound having at least two incyanate groups in one molecule of a polyisocyanate compound, and a crosslinking agent that reacts with the component (2) above and forms a three-dimensionally crosslinked coating film. Specifics Specifically,
Tolylene diisocyanate, 4.4'-diphenylmethane diisocyanate, xylylene diisocyanate, metaxylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, hydrogenated 4.4'
-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, tolylene diisocyanate) (3 mol)
Adduct of totrimethylolpropane (1 mol), polymer of tolylene diisocyanate, adduct of hexamethylene diisocyanate (3 mol) with totrimethylolpropane (1 mol), reaction product of hexamethylene diisocyanate and water, xylylene diisocyanate Use of one or more types selected from adducts of isocyanate (3 mol) and trimethylolpropane (1 mol), adducts of tolylene diisocyanate (3 mol) and hexamethylene diisocyanate (2 mol), etc. However, in order not to reduce the weather resistance etc., among the items listed in -h, the reaction product of hexamethylene diisocyanate and water, the adduct of xylylene diisocyanate and trimethylolpropane, the adduct of tolylene diisocyanate and hexamethylene diisocyanate, etc. Non-yellowing types such as adducts, isophorone diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate are preferred.

The blending ratio of each of the above components in the present invention is not particularly limited, but the solid content is in the range of 10 to 100 parts by weight, particularly 15 to 75 parts by weight, based on 100 parts by weight of component (A). It is preferable that the value is within the range of
The total number of moles of hydroxyl groups (abbreviated as -OH group) in component B and the isocyanate groups (abbreviated as NGO group) in component B.
The molar ratio of N COlo H is preferably in the range of 0.5 to 2.5, particularly 0.7 to 2.0.

Component (0) crosslinks with 33 parts of (A) and (B) in the paint and may gel during storage.
C) Component 1 is preferably mixed with component (A) (l1m) before coating.

The number of paint compositions of the present invention and materials include coloring pigments, extender pigments, metallic pigments, surface conditioners, catalysts for accelerating curing, anti-cissing agents, ultraviolet 41iIe, absorbers, antioxidants, and other additives, as necessary. can also be added.

The thus obtained paint #1 composition of the present invention has excellent weather resistance, chemical resistance (acid resistance), painting workability, appearance of the painted surface, flexibility,
It has excellent properties such as water resistance, adhesion, and pigment dispersibility, so it can be used on metals, wood, glass, concrete).
The coating composition of the present invention has significantly better adhesion to non-polar polyolefin resin molded products such as polypropylene and/or other materials than conventional plastic coatings. It is most preferable to apply this method to the coating of molded articles made of polio I-nofin yarn resin.

For example, in order to apply the coating composition of the present invention to a polypropylene automobile bumper, the coating composition described above is first applied.

Components (B) and (C) are mixed with coloring pigments, additives, etc. as necessary to produce a paint using a normal method, and this is diluted with a diluting solvent until the coating viscosity reaches 4 (2).
(0°C) for 15-20 seconds. This is then degreased and then painted onto a polypropylene bumper material to a dry film thickness of approximately 20 to 40 microns. Painting methods include regular air spray, airless spray, and electrostatic painting. The coating film is cured by being left at room temperature or by heating at 100° C. or less for 20 to 40 minutes to obtain the coating film targeted by the present invention.

The coating composition of the present invention has particularly excellent adhesion to polyolefin plastics, as well as excellent weather resistance, physical performance, and chemical performance, so it can be applied in one coat without using a primer or the like. A highly durable coating film can be formed on polyolefin plastics with just one coat.

The coating composition of the present invention can also be applied to various plastic materials other than polyolefin plastics, such as ABS (acrylonitrile, butadiene, styrene copolymer), polycarbonate, nylon, FRP (fine reinforced plastic), RIM, PU (RIM), etc. It is possible to form a coating film with excellent performance against materials such as polyurethane), and specifically, these materials can be degreased with trichloroethane vapor or without applying a primer after degreasing with toluene. This coating composition can be finished with one coat. Furthermore, when the isocyanate group of the (0 component) is made into a blocked polyisocyanate using a blocking agent such as an aliphatic or aromatic monoalcohol oxime, lactam, or phenol, the (0 component is
・If it separates, it will not gel during storage (even if it is mixed with the ingredients at the same time, and the coating film will show % by weight unless the blocking agent dissociates when heated to 100°C or higher).

(1) Production example (a) of alkyd resin (component B)
Alkyd Resin Fas A A normal alkyd resin production equipment equipped with a heating device, stirrer reflux device, water separator, rectification column, thermometer, etc. was used, and 46.2 parts of hexahydrophthalic anhydride (0.3 mole)
, 88.8 parts (0.6 mol) of phthalic anhydride, 13.6 parts (0.1 mol) of trimethylolpropane, and 94.55 parts (0.9 mol) of neopentyl glycol were charged and heated. Once the raw materials are melted and stirring becomes possible, stirring is started and the reaction tank temperature is raised to 230°C. However, 160
The temperature is raised uniformly from °C to 230 °C over 3 hours. The condensed water produced is distilled out of the system through a rectification column.

Once the temperature reaches 230°C, the temperature is kept constant and stirring is continued for 2 hours. After that, Kijirole is added to the reaction tank and the reaction is continued by switching to the solvent condensation method.

When the acid value reaches 7, the reaction is terminated and the mixture is cooled. After cooling, 139 parts of Pheasant Roll was added to obtain an oil-free alkyd resin face A having a solid content of 60%.

(bl) Alkyd resin varnish B Alkyd resin varnish B modified with fatty acids was produced in the same way as in (a) using the following raw materials in 1 to 1.

Phthalic anhydride 59.2 parts (0.4 mol) Hexahydroheptalic anhydride 46.2 parts (0.3 mol) Trimethylolpropane 34.・g (0.25 mol) Neopentyl glycol 78.8 parts (0.75 mol) Coconut oil fatty acid 105.0 parts (0.5 mol) The solid content of the obtained alkyd resin varnish B is 60%. (c) Alkyd resin varnish C Oil-free alkyd resin varnish C was produced using the following raw materials in the same manner as in (a).

Hexahydrophthalic anhydride 92.4 parts (0.6 mol) Adipic acid 14.6 parts (0.1 mol) Phthalic anhydride 14.8 parts (0.1 mol) Trimethylolpropane 81.6 fl< (0, 6 moles)
Neopentyl glycol 42. o parts (0.4 mol) The solid content of the obtained alkyd resin varnish C is 60%.

(d) Alkyd resin varnish d An oil-based alkyd resin varnish d was produced in the same manner as in (a) using the following raw materials.

7 Tallic anhydride 88.8 parts (0.6 mol) Adipic acid 43.8 parts (1.3 mol) Trimethylolpropane 13.65 (0.1 mol) Neopentyl glycol 94.5 parts (0.9 mol) mole) The solid content of the obtained alkyd resin varnish d is 60%.

(2) Examples 1 to 5 Coating compositions according to the present invention were manufactured according to the combinations shown in Table 1.

For dispersing the pigment, component (b) was diluted with an appropriate amount of Kijirol and dispersed using a Pebble Mill. Silicone oil KP-322 (Shin-Etsu Chemical Co., Ltd.) is used as a coating surface conditioner for each paint.
40PPm was added to the paint. The resulting paint was diluted to a viscosity of 18 seconds (Ford cup #4/2nC) with a mixed solvent of toluene/Sufuzol 4 #1000 (Maruzen Oil Co., Ltd. petroleum solvent)/Kijirol = 50/30/20.

In Table 1 (*1) Acridic AL-644: Product name manufactured by Dainippon Ink ■, acrylic resin grafted with chlorinated polypropylene (acrylic resin/chlorinated polypropylene = 8
0/20. Degree of chlorination = 38%, hydroxyl value: 50) solution,
Solid content 50% (*2) Acridic AL-1283
: Manufactured by Dainippon Ink■ Product name, acrylic resin grafted with chlorinated polypropylene (acrylic resin/chlorinated polypropylene = 85715. Degree of chlorination: 28%, hydroxyl value: 50) solution, solid content 45% (*3) Duranate 2
4A: Asahi Kasei Corporation product name, water adduct of hexamethylene diisocyanate (*4) Desmodur N-752 Bayer product name, water adduct of hexamethylene diisocyanate (*5) Titanium White JR-602: Teikoku Kako ■Product name, titanium white pigment (*6) Thai Bake CR-93: Ishihara Sangyo ■Product name, titanium white pigment (*7) Aluminum Paste 55-519: Toyo Aluminum■
Cylinder Product Name, Flaky Aluminum Pigment Paste Comparative Examples 1 to 3 Comparative coating compositions having the compositions shown in Table 2 were produced in the same manner as in the examples.

Table-2 In Table-2, (*8) Acrylic resin varnish: Reaction tank, stirrer, dripper, heating and cooling bag fill
In a conventional acrylic resin varnish manufacturing apparatus equipped with a reactor, 67 parts of pheasant rolls were charged into a reaction tank and heated to 112°C. This temperature (112°C) is maintained until the end of the reaction.

Then, the following chemical mixture was added dropwise to the reaction vessel at a uniform rate over a period of 4 hours.

Styrene 15 parts n-butyl methacrylate 49 parts n-butyl acrylate 20 parts 2-hydroxyethyl methacrylate 15 parts acrylic acid
1 part 2.2'-Azobisisobutyronitrile 1.3 parts One hour after the completion of the addition of the above mixture, add 0.5 parts of 2.2'-Azobisisobutyronitrile at 10 minute intervals. Add 71i at a time over 1 hour.

Then, after stirring was continued at 112° C. for 1 hour, the reaction was completed and the mixture was cooled. After cooling, one part of Kijiroru 1725 and 15 parts of n-butanol were added to obtain an acrylic varnish with a solid content of 50%.

(*9) Bardren 141, LB: Part name manufactured by Toyo Kasei Kogyo ■ Chlorinated polypropylene with a chlorination rate of 28% (solid content 15%) ■ Performance test results Paints manufactured in the above examples and comparative examples with viscosity adjustment , toluene-degreased polypropylene (Sumitomo Chemical AH)
-685) Apply one coat of air spray to a dry painted material (thickness 21) without applying a primer to a dry film thickness of 35μ, and after setting for 10 minutes at room temperature, dry in a hot air electric dryer. A test coated plate was prepared by drying at 80°C for 30 minutes.

Various performance tests were conducted on the coated plates and coating compositions thus prepared. The results are shown in Table-3.

In Table 26-3, (Note 1) Compatibility: After mixing each component except for the crosslinking agent (polyisocyanate compound), it was applied onto a glass plate using an applicator, and its transparency and texture were observed. 80 more
Observe the condition after drying at ℃ for 30 minutes. Next, a crosslinking agent is added and the same operation is performed. A sample with good transparency and smoothness in any condition was rated as ○, and a sample with poor transparency and smoothness in both conditions was rated as △.

(Note 2) The finished appearance of the coating film (shine, texture) was evaluated visually according to the following criteria.

○: Good G: Good △: Poor ×: Very poor (Note 3) Impact resistance: Using a DuPont impact tester, the product was dropped with the paint film facing up under a load of 500 t and a striking center of 1/2φ The maximum falling distance (cfn) at which no abnormality was observed in the coating film was shown.

(Note 4) The painted material was bent at 90 degrees with the paint film on the outside, and the paint film was examined for cracks or scuffs.

○: No abnormality ×: Significant cracking and peeling (Note 5) Acid resistance: Spot drop 0.5 CC of 10% sulfuric acid on the painted surface and leave it for 24 hours at 20°C and 75% RH, then wash with water and observe the painted surface. Next.

(Note 6) Gasoline wiping resistance: Apply Nisseki Silver gasoline to gauze and wipe the coated surface with 10crr1 length.
After rubbing back and forth, the painted surface was observed. Those with almost no scratches or glossy pixel on the painted surface were considered good.

(Note 7) Water resistance: The coated plate is immersed in a constant temperature water bath at 40°C for 240 hours. Those with no abnormalities such as glossy pique or blistering on the paint film after removal were considered good. Furthermore, after dipping, a cross-cuttle adhesive cellophane tape peeling test was conducted.

(Note 8) Interlayer adhesion: The test plate coated with paint and baked was further overbaked at 100℃ for 30 minutes, left to cool at room temperature, and after 2 hours, the same paint was applied again and baked at 80℃ for 30 minutes, then left to cool. Then, we conducted a peeling test using cross-cut adhesive cellophane tape, and those with no peeling were rated as good.
．． Ta.

(Note 9) Painting workability: The unadjusted diluted paint was air-sprayed and evaluated comprehensively, including the presence or absence of sagging, wrinkles, etc.

(Note 10) Ultraviolet rays were irradiated for 800 hours using Sunshine Weather Meta, and the subsequent 60 degree specular reflectance (%) was measured.

(Note) Bendability (90°) was performed in an atmosphere with a low temperature bending knee of 15°C to evaluate cracking of the coating film.

(Note 12) Adhesion: Using a cutter knife, 100 goblets with a width of l++m were made on the surface of the coating film, and a peeling test was conducted using adhesive cellon tape, and those with no peeling were evaluated as good.

Claims (1)

[Claims] (1) (A) Vinyl-modified chlorinated polyolefin, (B)
At least 30 mol% of the polybasic acid component is a saturated alicyclic polybasic acid, and the value obtained by dividing the total number of moles of the polybasic acid component by the total number of moles of the polyhydric alcohol component (dibasic acid ratio) is When the vertical axis is the mol% of the glycol component having 3 or more carbon atoms in the polyhydric alcohol component, (0.6, 20), (0
．． 6, 100), (1.00, 30), (1.00, 1
00) A coating composition whose main components are an oil-free or fatty acid-modified alkyd resin and (C) a polyisocyanate compound, which are comprised of compositions included on and within the quadrilateral line surrounded by the four points of 00).