JPH0819376B2 - Paint composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coating composition. More specifically, it relates to a one-pack type urethane coating composition which is particularly useful for applications such as chipping resistant coatings.

[Prior art] Conventionally, as a one-pack type urethane coating which can be used as a coating composition, especially as a chipping-resistant coating, a blocked urethane prepolymer using an organic polyisocyanate such as tolylene diisocyanate and a polyoxyalkylene polyamine are used. (See, for example,
226062).

[Problems to be Solved by the Invention] However, this composition has a relatively low temperature and a short time (for example,
Sufficient adhesion (curability) by heat treatment at 120 ° C for 20 minutes
However, there was a problem that chipping resistance was insufficient.

[Means for Solving the Problems] The present inventors have arrived at the present invention as a result of diligently studying a coating composition which solves these problems and is excellent in coating properties and storage stability.

That is, the present invention is a main agent comprising a blocked product (a) of a urethane prepolymer (abbreviated as NCO prepolymer I) having an isocyanate group derived from a polyisocyanate having an isocyanurate ring and polyols;
Polyoxyalkylene polyamine (1), alkylene oxide adduct of (poly) alkylene polyamine (however, the molecular weight per hydroxyl group of the adduct is 30 to 500)
(2), polyamide resin (3), ketimine (4) of polyoxyalkylene polyamine, ketimine (5) of polyamide resin, ketimine (6) of (poly) alkylene polyamine, and modified products thereof containing an epoxy group (hereinafter referred to as epoxy). A modified composition) (7), which contains a curing agent in combination of two or more selected from the group consisting of (7).

Examples of the polyisocyanate having an isocyanurate ring used in the present invention include isocyanurates derived from organic diisocyanates. Examples of the organic diisocyanate include aliphatic diisocyanates having 2 to 12 carbon atoms (excluding carbons in the NCO group) and 4 to 15 carbon atoms.
And alicyclic diisocyanates having 8 to 12 carbon atoms and aromatic diisocyanates having 6 to 20 carbon atoms. Further, specific examples thereof include aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) and lysine diisocyanate; hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), isophorone diisocyanate (IPDI), cyclohexane diisocyanate (CHDI), hydrogenated tolylene diisocyanate. Alicyclic diisocyanates such as isocyanate and hydrogenated xylylene diisocyanate; tolylene diisocyanate (TDI),
Examples include aromatic diisocyanates such as α, α, α ′, α′-tetramethylxylylene diisocyanate (TMXDI), diphenylmethane diisocyanate (MDI), naphthylene diisocyanate, and xylylene diisocyanate, and mixtures of two or more thereof. Of these, preferred are aliphatic diisocyanates and cycloaliphatic diisocyanates, and the most preferred are HDI and IPDI.
Is.

Exemplifying the method for producing the polyisocyanate having the isocyanurate ring, the organic diisocyanate exemplified above may be used as a catalyst, for example, an oxide (such as lithium oxide),
Alkoxides (such as sodium methylate), amines (such as triethylamine), carboxylates (such as calcium naphthenate), and organic metals (such as dibutyltin dilaurate) are used alone or in combination at high temperatures (usually 50 to 150).
C., preferably 60 to 100.degree. C.). The NCO% of the polyisocyanate having the isocyanurate ring is usually 5 to 35%, preferably 10 to 30%.

In the present invention, the polyols include a high molecular weight polyol (A) having a molecular weight per hydroxyl group of usually 500 to 3000 and a low molecular weight polyol (B) having a molecular weight per hydroxyl group of usually 30 to less than 500.

Examples of the polymer polyol (A) include polyether polyol (a), polyester polyol (b), polymer polyol (c), polycarbonate polyol (d), and a mixture of two or more thereof.

Examples of the polyether polyol (a) include polytetramethylene glycol (PTMG) which can be obtained by ring-opening polymerization of tetrahydrofuran (JP-A-58-11).
Those described in Japanese Patent No. 518). In addition, as the polyether polyol (a), an alkylene oxide adduct of a polyhydric alcohol can also be mentioned. As the polyhydric alcohol, for example, the molecular weight per hydroxyl group is usually 30 to 500, preferably 30 to 400 diol, for example,
Ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol and 3-methyl-1,5-pentanediol; triols having a molecular weight per hydroxyl group of usually 30 to 600, preferably 40 to 500, for example ,
Glycerin, trimethylolpropane; and mixtures of two or more thereof. Further, as the alkylene oxide, for example, ethylene oxide,
Propylene oxide, 1,2-1,3- or 2,3-butylene oxide, tetrahydrofuran, styrene oxide, epichlorohydrin and mixtures of two or more thereof are mentioned.

Examples of the polyester polyol (b) include polyester polyols obtained by polycondensing a dicarboxylic acid, its ester or halide, and a polyhydric alcohol. Examples of this dicarboxylic acid include aliphatic dicarboxylic acids (adipic acid, sebacic acid, maleic acid, dimer acid, etc.); aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, etc.); and their anhydrides. Of these, preferred are aliphatic dicarboxylic acids, and particularly preferred is adipic acid. Examples of the polyhydric alcohol include those described when exemplifying the polyether polyol, and preferable ones are ethylene glycol and 1,4-butanediol.

As the polyester polyol (b), a polylactone polyol obtained by ring-opening polymerization of a lactone (eg, ε-caprolactone) in the presence of a polyhydric alcohol (such as ethylene glycol), for example, polycaprolactone diol (PCL) can also be mentioned. To be

As the polymer polyol (C), JP-A-55-1189
Examples include those described in Japanese Patent No. 48.

Examples of the polycarbonate polyol (d) include those derived from the polyhydric alcohol (dihydric alcohol) and carbonic acid diester (dimethyl carbonate, diethyl carbonate, etc.).

Among the polyols exemplified above, the polyether polyol (a) is preferable, and the alkylene oxide adduct of a polyhydric alcohol is particularly preferable.

Examples of the low molecular weight polyol include alkylene oxide adducts of polyhydric alcohols described when exemplifying a polyether polyol, those having a molecular weight of 30 to less than 500, and mixtures of two or more thereof.

In the NCO prepolymer I, the NCO / OH equivalent ratio of the organic polyisocyanate unit and the polyols unit is usually 1.3-
It is 8.0, preferably 3.0 to 6.0. The molecular weight of NCO Prepolymer I is usually 500 to 10,000, preferably 700 to 8,000. If the molecular weight is less than 500, the resin becomes hard and brittle, which adversely affects chipping resistance and
If it exceeds, it is difficult to obtain good adhesion. The NCO% of this prepolymer is usually 1 to 20%, preferably 2 to 15%.
Is.

An example of the method for producing the NCO prepolymer I is as follows.

When carrying out the formation reaction of the NCO prepolymer I, usually known polymerization catalysts for promoting the reaction, for example, organometallic compounds such as dibutyltin dilaurate, stannous octoate, stannas octoate, triethylenediamine, triethylamine, 1 , 8-diazabicyclo [5,4,
0] A tertiary amine compound such as undecene-7 is used.

The reaction is usually performed in the presence of a solvent. Examples of the solvent include aromatic hydrocarbons (toluene, xylene,
Trimethylbenzene, etc.), ester type (ethyl acetate,
Examples thereof include butyl acetate), ethers (dioxane, cellosolve acetate, etc.), ketones (acetone, methyl ethyl ketone, etc.), and mixed solvents of two or more of these.

The reaction temperature is usually 40 to 140 ° C, preferably 60 to 120 ° C. The reaction time is usually 3 to 10 hours, preferably 5 to 8 hours.

Examples of the blocking agent used to obtain the blocked product (a) of the urethane prepolymer include oxime compounds [acetoxime, ketoxime such as methylethylketoxime (MEK oxime), methylisobutylketoxime (MIBK oxime)]; Lactam compound [ε-caprolactam, δ-valerolactam, γ-
Butyrolactam, etc.]; active methylene compounds [malonic acid diesters (such as diethyl malonate), acetylacetone, acetoacetic acid esters (such as ethyl acetoacetate)]; phenols (phenol, m-cresol, etc.); dialkylphenols [xylenol, diester Propylphenol, di-t-butylphenol, dinonylphenol, etc.); alcohol (methanol, ethanol, n-butanol, etc.); hydroxyl group-containing ether (methyl cellosolve, butyl cellosolve, etc.); hydroxyl group-containing ester (ethyl lactate, amyl lactate, etc.); mercaptan (Butyl mercaptan, hexyl mercaptan, etc.); Acid amides (acetanilide, acrylic amide, dimer acid amide, etc.); Imidazoles (imidazole, 2-ethylimidazo) Le etc.); and acid imides (succinimide, phthalic acid imide), with can also be used in combination.

Of these, preferred are oxime compounds and lactams, and particularly preferred are MEK oxime and ε-caprolactam.

The blocking agent can be added and reacted at any stage of the NCO prepolymer I forming reaction to obtain a blocked product of the urethane prepolymer. That is, it is possible to add the NCO prepolymer I at the end of the polymerization, to add it at the beginning of the polymerization, or to add it partially at the beginning of the polymerization, and to add the balance at the end of the polymerization. The preferred method is to add at the end of the polymerization.

When it is added at the end of the polymerization, the addition amount is usually 1 equivalent or more and less than 2 equivalents, preferably 1.05 to 1.5 equivalents, relative to the free isocyanate groups of the NCO prepolymer I. When the blocking agent is added at the initial stage of the polymerization, it is preferable to use the blocking agent in an amount substantially equal to the value obtained by subtracting the total OH equivalent of the polyols from the NCO equivalent of the raw material polyisocyanate.

The reaction temperature when adding the blocking agent is usually 50.
~ 150 ° C. It is also possible to promote the reaction by adding a known urethane polymerization catalyst during the blocking reaction.

In the present invention, examples of the aromatic polyisocyanate include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthylene diisocyanate, and xylylene diisocyanate. Preferred of these are TDI and MDI.

In the present invention, examples of the blocked compound (b) include those described in JP-A No. 61-218664.

In the present invention, when the blocked products (a) and (b) are used in combination as the main agent, (b) can be usually contained in an amount of 0% to 80% based on the total weight of the main agents. The combined use of (a) and (b) is preferable from the viewpoint of broadening the balance range of low temperature curability and storage stability.

In the present invention, examples of the polyoxyalkylene polyamine (1) include alkylene oxides such as ethylene glycol, propylene glycol, diethylene glycol, glycerin, trimethylolpropane, and ethylenediamine. 2-, 1,3- or 2,3-butylene oxide, tetrahydrofuran, styrene oxide, epichlorohydrin and a mixture of two or more thereof) obtained by addition polymerization of a polyether polyol, for example, by ammonolysis The thing which changed the non-end hydroxyl group into the amino group is mentioned.

Specific examples of the polyoxyalkylene polyamine exemplified above include, for example, the general formula: [In the formula, n represents 2 to 50. ] And the general formula [In the formula, x, y, and z represent positive numbers such that x + y + z is approximately 3 to 50. ] The polyoxypropylene polyamine shown by these is mentioned.

In the present invention, the alkylene oxide adduct (2) of the (poly) alkylenepolyamine constitutes (poly).
Examples of the alkylene polyamine include diethanolamine, triethanolamine, (poly) ethylene polyamine (eg, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, etc.), (poly) propylenepolyamine (eg, propylenediamine, diamine). Propylene triamine, tripropylene tetramine, etc.),
(Poly) cycloalkylene polyamine (eg 1,8-p
-Methanediamine, isophoronediamine, diaminocyclohexane, 4,4'-methylenebisdicyclohexylamine, 1,3-bis (aminomethyl) cyclohexane and the like). Two or more of these polyalkylene polyamines may be used in combination. Among these, preferred are diethylenetriamine and dipropylenetriamine. Examples of the alkylene oxide adduct (2) of the (poly) alkylene polyamine include the alkylene oxide adducts of the (poly) alkylene polyamines exemplified above. As alkylene oxide,
What was illustrated when exemplifying this polyoxyalkylene polyamine is mentioned. The alkylene oxides may be used alone or in combination of two or more. In the latter case, block addition, random addition, or a mixture of both may be used. Preferred among the alkylene oxides are ethylene oxide, propylene oxide and combinations thereof.
The molecular weight per hydroxyl group of the alkylene oxide adduct of the (poly) alkylene polyamine is 30 to 500, preferably 60 to 500.

Examples of the polyamide resin (3) include those known as epoxy resin curing agents, that is, those obtained by reacting at least one of polymerized fatty acid, monobasic acid and dibasic acid with polyamides. . As the polymerized fatty acid, monobasic acid, dibasic acid and polyamines, those described in JP-B-53-41121 and JP-B-53-41122 can be used.

The amine value of the polyamide resin (3) is usually 90 or more, preferably 100 to 450, particularly preferably 150 to 400.
If the amine value is less than 90, (3) generally has a high molecular weight, so that the compatibility of the urethane prepolymer with the blocked product decreases.

The polyamide resin (3) is a partially modified product thereof, for example, a polyamide resin modified product modified with a compound containing an imidazoline ring in the molecule or a compound having an electron-withdrawing group such as a vinyl compound (acrylonitrile, epoxy acrylate, etc.) 51-23560 and Japanese Patent Publication No. 525554).

The polyamide resin (3) may contain a free polyamine. As this polyamine, JP-A-54-12
Those described as polyamines in 2395 and JP-A-54-101899 can be used. Among the polyamines, polyalkylene polyamines (diethylene triamine, dipropylene triamine, triethylene tetramine, etc.) are preferable.

Examples of the polyoxyalkylene polyamine constituting the ketimine (4) of the polyoxyalkylene polyamine include the aforementioned polyoxypropylene diamine and polyoxypropylene triamine.

Examples of the polyamide resin that constitutes the ketimine (5) of the polyamide resin include those exemplified as the polyamide resin (3).

Examples of the (poly) alkylene polyamine constituting the ketimine of the (poly) alkylene polyamine include ethylenediamine, diethylenetriamine, propylenediamine, hexamethylenediamine, and (poly) cycloalkylenepolyamine.

Further, the ketimines of (4), (5) and (6) are reaction products of the above-exemplified amine-based components and ketones. Examples of this ketone include acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone diethyl ketone, dipropyl ketone, diisopropyl ketone, dibutyl ketone, diisobutyl ketone, and the like, with preference given to methyl isobutyl ketone.

These ketimines can be produced by dehydration condensation of each amine component and ketone. The above condensation reaction is usually carried out while distilling water in the presence of a water absorbing agent. Specifically, polyamine or polyamide compound and stoichiometrically excess ketone are added, and an appropriate solvent (toluene, xylene, etc.) is added, and then dehydration condensation is performed under heating and reflux while separating water, and necessary. Can be produced by removing excess ketone and solvent.

Examples of the epoxy modified product (7) include epoxidized fatty acid alkyl ester of polyoxypropylene triamine [epoxy modified product of (1)]; propylene oxide adduct of glycidyl ether adduct of polyethylene polyamine [epoxy of (2)]. Modified product]; Polymerized fatty acid
Polyethylene polyamine / fatty acid polycondensate and bisphenol A diglycidyl ether adduct [epoxy modified product of (3)]; polyoxypropylene triamine glycidyl ether adduct ketone condensate [(4) epoxy modified product], above Ketone condensate of (3) epoxy modified product [epoxy modified of (5)]; condensate of glycidyl ether adduct of polyethylene polyamine and ketone [(6)
Epoxy modified product].

Two or more of the curing agents exemplified above are used in combination. Among the combined use of these curing agents, preferred are (2) and (5), (1) and (5), and (2) and (3).
And (5) together. By using (2) and (5) together, the coating property and yellowing can be improved.
Further, by using (1) and (5) together, curability and coatability can be improved. The combined use of (2), (3) and (5) is preferable from the viewpoint of curability, storage stability and coatability.

A catalyst usually used in the reaction of urethane-based polymers (for example, lead octylate and octylate) for the purpose of lowering the heat treatment temperature or shortening the heat treatment time when applying the coating by promoting the reaction of the main agent and the curing agent during heating. It is also possible to use an organometallic compound such as tin and a tertiary amine compound such as triethylenediamine and triethylamine) together.

In the present invention, the ratio of the NCO equivalent of the main agent to the active hydrogen equivalent of the curing agent is usually 1 / 0.1 to 2, preferably 1 / 0.5 to 1.5. If the active hydrogen equivalent is less than 0.1 or more than 2, curing is insufficient or chipping resistance is reduced.

The composition of the present invention may optionally contain a pigment, a filler and a solvent. Examples of the pigment include inorganic pigments such as titanium oxide, carbon black, red iron oxide, and oxide yellow, and organic pigments such as phthalocyanine blue and phthalocyanine green.

Examples of the filler include clay, calcium carbonate, barium sulfate, talc, alumina, silica, barite, flint and clay.

As the solvent, for example, the same solvent as that used in the production of the urethane prepolymer can be mentioned.

If necessary, the composition of the present invention may also contain various kinds of auxiliaries such as a leveling agent, an anti-sagging agent, an antifoaming agent, a surfactant, a curing accelerator, an anti-cissing agent, a pigment dispersant, an antistatic agent, etc. It can also be blended within a range that does not impair the coating film performance.

Table 1 shows an example of the formulation when the composition of the present invention is used as it is as a compounding system that can be used as a paint. (% Is based on the weight of the composition.) The composition of the present invention can be produced by a known method. For example, the above components are mixed in a usual mixing apparatus (disperser, three rolls, ball mill, steel mill, pebble mill, attritor, sand mill, sand grinder,
Roll mill, pot mill, high-speed stirrer with blades, etc.) are used for mixing and coating.

The composition of the present invention is used as it is, or after adding components such as pigments necessary for a paint, and then directly coated on an untreated iron plate surface or a chemical conversion treated iron plate surface; It can be used in various application methods such as direct coating on the surface; coating on the surface such as anion electrodeposition coating surface or cation electrodeposition coating surface by an arbitrary method.

The composition of the present invention can be used not only as the above-mentioned undercoat paint but also in any step such as on the undercoat paint cured coating film, the intermediate coating paint cured coating film, the topcoat paint cured coating film.

The coating can be performed using an air spray coating machine, an airless spray coating machine, a hot airless spray coating machine, or the like. Since it takes time for the air spray coater to obtain the required film thickness, it is preferable to use the airless spray coater. In the case of an airless spray coating machine, it usually takes 1 stroke or 2 depending on the stroke speed.
The required film thickness can be obtained by the stroke. Brush coating, roller coating, spatula coating, etc. can be used when repairing or applying to complex areas.

The baking temperature of the composition of the present invention is usually 90 ° C or higher, preferably 100 to 170 ° C, particularly preferably 110 to 150 ° C. The baking time is usually within 120 minutes, preferably 10 to 60 minutes.

Dry film thickness formed by the composition of the present invention is usually 30 to
It is 500μ, preferably 50-300μ. When the film thickness is less than 30 μm, the chipping resistance is insufficient. On the other hand, when the film thickness exceeds 500 μm, defects such as cracks and sagging tend to occur.

When the composition of the present invention is applied on an electrodeposition coated surface, an intermediate coating composition and a top coating composition are usually further coated on the coating film formed.

The intermediate coating composition can be applied wet-on-wet even when the composition of the present invention is not dried, and can be applied even when the composition is cured and dried. (Dry on wet).

The intermediate coating can be used to improve the gloss of the top coating and to fill fine irregularities on the coating surface, and usually epoxy resin-based paint, melamine alkyd resin-based paint, etc. are used. Examples of the coating method include spray coating method and electrostatic coating method. In addition, the intermediate coating may be omitted.

The top coat can be used for aesthetic purposes, and is usually a melamine alkyd resin paint, a thermosetting acrylic resin paint or the like, and is applied in the same manner as the intermediate coat.

It is also possible to apply the usual intermediate coating composition in a wet-on-wet manner as described above, and then cure and dry it at a usual baking temperature of about 120 to 170 ° C. without any preliminary drying.

"Example" The present invention will be further described with reference to production examples and examples, but the present invention is not limited thereto. In the following, "part" means "part by weight".

Production Example 1 1 L capacity 4 equipped with a stirrer, thermometer and nitrogen inlet tube
Isocyanate group-containing polyisocyanate derived from hexamethylene diisocyanate in one-end Kolben (manufactured by Asahi Kasei Kogyo, trade name; Duranate TPA-100 NCO% = 2
3.1) 289 parts, polypropylene glycol (molecular weight = 1200) 196 parts, carbitol acetate 400 parts were charged, and the reaction was carried out at 80-100 ° C for 5 hours under a nitrogen stream, then 0.1 part of dibutyltin dilaurate was added, and the reaction was continued for another 3 hours. Then, a urethane prepolymer having an NCO% of 10.3% (solid content conversion) was obtained. Then add 115 parts of MEK oxime and
After reacting at 60 to 80 ° C. for 3 hours, it was confirmed by infrared absorption spectrum that the isocyanate group had disappeared.

Thus, a urethane prepolymer solution having a blocked isocyanate group having a solid content of 60% was obtained.

Manufacture example 2 It carried out like manufacture example 1 except having replaced isocyanurate derived from hexamethylene isocyanate of manufacture example 1 with tolylene diisocyanate (however, reaction temperature of tolylene diisocyanate was 70-80 ° C). .),
A urethane prepolymer solution having a blocked isocyanate group was obtained. This urethane prepolymer solution having blocked isocyanate groups and Production Example 1
Using the urethane prepolymer solution having a blocked isocyanate group obtained in the above, a coating composition I of the present invention was prepared in the following blending ratios. The proportions of the urethane prepolymer solution having a blocked isocyanate group and the composition I are as follows.

[Urethane prepolymer solution having blocked isocyanate group] Tolylene diisocyanate 203 parts Polytetramethylene glycol 234 parts (Molecular weight = 1000) Trimethylol propane 31 parts Carbitol acetate 400 parts ε caprolactam 132 parts [Composition I] block Urethane prepolymer (TDI-based) with a modified isocyanate group 30 parts Urethane prepolymer (HDI isocyanurate-based) with a blocked isocyanate group 30 parts Obtained by reacting a polymerized fatty acid with a polyamine (triethylenetetramine) Polyamide resin ketimine 16 parts (total amine value 250) PO adduct of diethylenetriamine 5 parts (molecular weight = 400) calcium carbonate 80 parts titanium white 5 parts carbon black 1 part aromatic petroleum naphtha (boiling range 100-200 ° C) 35 parts comparison Example 1 Example 1 was repeated except that isocyanurate derived from hexamethylene diisocyanate of Production Example 1 was replaced with tolylene diisocyanate (however, the reaction temperature of tolylene diisocyanate was 70 to 80 ° C). ), A urethane prepolymer solution having a blocked isocyanate group was obtained. A coating composition II was prepared in the following blending ratio using this urethane prepolymer solution having a blocked isocyanate group. The proportions of the urethane prepolymer solution having a blocked isocyanate group and the composition II are as follows.

[Urethane prepolymer solution having blocked isocyanate group] Tolylene diisocyanate 214 parts Polytetramethylene glycol 246 parts (Molecular weight = 1000) Trimethylol propane 33 parts Carbitol acetate 400 parts Methyl ethyl ketoxime 107 parts [Composition II] block Polyurethane resin obtained by reacting polymerized fatty acid with polyamine (triethylenetetramine) ketimine 17 parts (total amine value 250) calcium carbonate 80 parts titanium white 5 parts Carbon black 1 part Aromatic petroleum naphtha (boiling range 100-200 ° C) 36 parts Comparative Production Example 2 Same as Comparative Production Example 1 except that the blocking agent of Comparative Production Example 1 was changed from MEK oxime to ε-caprolactam. Isocyanate blocked by the method To obtain a urethane prepolymer solution having a group (provided that the temperature of the block of ε-caprolactam was 80 to 100 ° C.). Using the blocked urethane group prepolymer solution having an isocyanate group, a coating composition III was prepared in the following blending ratio.

The proportions of the urethane prepolymer solution having a blocked isocyanate group and the composition III are as follows.

[Urethane prepolymer solution having blocked isocyanate group] Tolylene diisocyanate 210 parts Polytetramethylene glycol 242 parts (molecular weight = 1000) Trimethylolpropane 32 parts Carbitol acetate 422 parts ε-caprolactam 150 parts [Composition III] Urethane prepolymer with blocked isocyanate group 61 parts Ketimine, a polyamide resin obtained by reacting polymerized fatty acid with polyamine (triethylenetetramine) 16 parts (total amine value 250) Calcium carbonate 80 parts Titanium white 5 parts Carbon Black 1 part Aromatic petroleum naphtha (boiling range 100 to 200 ° C.) 36 parts [Example 1 and Comparative Examples 1-2] Baking coating film of the coating composition obtained in Production Example 1 and Comparative Production Examples 1-2. Adhesion, curability, paintability, chipping resistance, storage stability, yellowing The evaluation results are shown in Table 3.
In the evaluation, the following coating film test method was adopted.

Chipping resistance A 100 x 100 x 0.8 mm electrodeposition coated plate is coated with a 200 μm thick (after drying) chipping resistant coating composition. The baked sample is then coated with a commonly used intermediate coating (melamine / alkyd resin). After baking (medium coating dry film thickness: 30μ, baking condition: 140 ° C × 20 minutes), a 3 type-M-4 shaped iron hexagon nut specified in JIS B-1181 with a pipe diameter of 20 mm from a height of 2 m Table 3 shows the total weight (kg) of the falling nuts until the scratches of the coating film reached the metal surface after being dropped through the cylinder onto each sample plate having an angle of 45 ° with respect to the falling direction of the nuts.

Adhesion (goggles method) Applying a chipping-resistant coating composition with a thickness of 200μ (after drying) to an electrodeposition coated plate of 100 × 100 × 0.8 mm Put a 1 mm square cross cut (area: 1 cm ² ) on the baked sample . Then, a peeling test was performed using cellophane tape, and the number of 1 mm square coating films that adhered and remained was examined. The display shows the residual number in the numerator and the number of crosscuts first in the denominator.

A chipping-resistant coating composition was applied to a 100 × 100 × 0.8 mm curable electrodeposition coated plate so as to have a thickness of 200 μ and 350 μ (after drying), and baked at 120 ° C. for 20 minutes. After cooling, the degree of tack was examined by finger touch.

：: no tack △: slightly tacky, but practically acceptable ×: tacky Paintability The paint composition was 200μ and 350 using airless spray
Spray it on the electrodeposition coated plate so that the film thickness will be μ (after drying)
After baking at 140 ° C. for 40 minutes, the appearance (blister, armpit, etc.) of the cured coating film was examined.

◯: No blisters and blisters, etc. Δ: Some blisters are seen, but extremely minute. ×: Blisters and blisters, etc., are generated. Storage stability The chipping-resistant coating composition is stored at 40 ° C for 10 days, and the viscosity increase rate of the coating before and after storage (%)investigated.

Yellowing Examples 1-4 on polypropylene trays of 150 x 100 mm
A sample was prepared by applying and baking the resin liquid of Comparative Example 1 except for the pigment component to a thickness of 200 μm (after drying). The baking conditions were 150 ° C. × 40 minutes. The yellowing degree of this sample was measured using a multi-source spectrophotometer (manufactured by Suga Test Instruments Co., Ltd.).

The ranking of the degree of yellowing is as shown in Table-2.

[Effect of the Invention] The coating composition of the present invention adheres to the substrate at a low temperature in a short time and has good curability as compared with the conventional composition. It also has excellent paintability, chipping resistance, and storage stability. Therefore, when applied to vehicles, etc., it exhibits excellent rust prevention.

A conventional one-pack resin composition comprising a urethane prepolymer having a blocked isocyanate group, a polyol composition and a monoalcohol has been insufficient in terms of adhesion, curability and chipping resistance.

Because of the above effects, the coating composition of the present invention is particularly useful as a chipping-resistant coating for vehicles such as automobiles.

Claims (3)

[Claims] 1. A blocked product (a) of a urethane prepolymer having an isocyanate group derived from a polyisocyanate having an isocyanurate ring and a polyol.
And a polyoxyalkylene polyamine (1), an alkylene oxide adduct of (poly) alkylene polyamine (however, the molecular weight per hydroxyl group of the adduct is 30 to 500) (2), a polyamide resin (3), Two or more selected from the group consisting of polyoxyalkylene polyamine ketimines (4), polyamide resin ketimines (5), (poly) alkylene polyamine ketimines (6), and epoxy group-containing modified products (7) thereof. A coating composition comprising a curing agent which is used in combination. 2. The composition according to claim 1, wherein the main component comprises (a) and a blocked product (b) of a urethane prepolymer having an isocyanate group derived from an aromatic polyisocyanate and a polyol. 3. Curing agents (1) and (5), (2) and (5)
Or (2), (3) and (5).
The coating composition described.