JPS5815564A - Coating composition - Google Patents

Abstract

PURPOSE:To provide a one-pack type urethane coating compsn. curable at low temp. with reduced energy consumption, prepared by adding a crosslinking agent to a reaction product of a partly blocked isocyanate compd. and a polyol. CONSTITUTION:A partly blocked isocyanate compd. with a blocking degree of 30-70% is made to react with a polyol comprising a macromolecular polyol (e.g. acrylpolyol) and, when necessary, a low-molecular polyol (e.g. ethylene glycol). A crosslinking agent consisting of a low-molecular polyol (e.g. glycerine) and/or a low-molecular polyamine (e.g. triethanol-amine, ehylenediamine) is added to the reaction product in such an amount that the equivalent ratio between a potential NCO group in the reaction product and an active hydrogen group in the acrosslinking agent may be 0.8:1.2-1.2:0.8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition. More specifically, the present invention relates to a one-component heat-curing urethane coating composition which has a curing temperature lower than conventional compositions and which saves energy by 9 degrees.

Hitherto, one-component heat-curable coating compositions consisting of three components: a completely blocked isocyanate compound, a polyol, and a curing agent have been known, but the dissociation temperature (deblocking temperature) is as high as about 140° C. or higher.

There is also a coating composition comprising a partially blocked isocyanate compound and an active hydrogen-containing compound (Public Patent Publication No. 49-2
8255), but the curing temperature is also high in this case.

Under these circumstances, from the viewpoint of energy saving, there is a desire for coating compositions that can be cured at lower temperatures.

The present inventors have arrived at the present invention as a result of intensive studies to satisfy the above-mentioned demands. That is, the present invention is a one-component heat-curable urethane coating composition comprising a solution containing a reaction product Q and a crosslinking agent (2) consisting of a low-molecular polyol or/and a low-molecular polyamine.

Partially blocked isocyanate compound in the present invention (
A) is obtained by reacting a polyisocyanate compound and a blocking agent such that the NCO groups of the polyisocyanate compound are in excess with respect to the blocking agent. Examples of the polyisocyanate compound include non-aromatic polyisocyanates such as aliphatic polyisocyanates (hexamethylene diisocyanate, lysine diisocyanate-1, etc.).
, alicyclic polyisocyanate (hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, hydrogenated 1
-lylene diisocyanate, etc.), aromatic nucleus-substituted aliphatic polyisocyanates (those with no NCO group in the nucleus, xylylene diisonanate, etc.), aromatic diisocyanates (tolylene diisocyanate 1-.diphenylmethane diisocyanate, naphthylene diisocyanate) , etc.) and mixtures of two or more of these.

Further, as polyisoneane-1-, an NCO-terminated prepolymer, such as an NCO-terminated prepolymer obtained by reacting a polyisocyanate with a low-molecular polyol, a high-molecular polyol, etc., which will be described later, can also be used.

Among these, preferred are aliphatic diisocyanates and alicyclic diisocyanates in consideration of light resistance, and particularly preferred are hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and isophorone diisocyanate.

As blocking agents, oxime compounds (ketoximes include acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, etc.); lactams (ε-caprolactam, δ-valerolactam).

γ-butyrolactam, β-propiolactamna); active methylene compounds (diester malonate and diethyl malonate, acetylacetone, acetoacetate such as ethyl acetoacetate); phenols (phenol, cresol, xylenol, reso/resinol, etc.) ) etc. Among these, oxime compounds are preferred.

Lactams and active methylene compounds are particularly preferred, and oxime compounds (particularly methyl ethyl ketone oxime) are preferred.

The partially blocked isocyanate compound is used so that the blocking rate is usually 30 to 70%, preferably 40 to 60%. The partially glocked isocyanate compound can be obtained by reacting the NCO group of the polyisocyanate with a blocking agent such that the NCO group becomes 03 to 07 degrees, preferably 04 to 06 degrees, on an equivalent basis. The reaction temperature is usually 10~
120'C, preferably 20-100°C.

Unreacted polyisocyanate remained in the partially blocked isocyanate compound. In some cases, compounds in which NGO groups are completely blocked may be produced as by-products, but they may be contained in the present invention. If necessary, they may be removed by distillation, extraction, etc.

The molecular weight of the polymer polyol used as component Φ or a part thereof is usually 500 to 20,000. Preferably 800-10,000. Hydroxyl value is usually 10-4
50°, preferably 20 to 200°.

Specifically, examples of the polymer polyol include acrylic polyol, polyester polyol terpolyol, polymer polyol, and mixtures of two or more of these.

Acrylic polyol is an acrylic (b)polymer in which a hydroxyl group is introduced, and includes a (co)polymer of a hydroxyl group-containing monomer and another polymerizable monomer. As the hydroxyl group-containing monomer, hydroxyalkyl/I/(meth)acrylate [hydroquinethyl (meth)acrylate-1-,
hydroxypropyl (meth)acrylate, hydroxyhexyl (meth)acrylate, etc.], allyl alcohol, polyhydric alcohol, preferably hydroxyalkyl(meth)acrylate. Other polymerizable monomers include unsaturated carboxylic acid esters such as alkyl meth)acrylates [methyl-; ethyl-; n-, iso-, or t-butyl-;
2-Ethylhexyl; lauri7-(meth)acrylate], fumaric acid ester, maleic acid ester/I
/: Aromatic vinyl monomers (styrene, alkylstyrenes, etc.), vinyl halides (vinyl chloride, etc.), vinyl esters (vinyl acetate, etc.), unsaturated nitrile [(
(meta) acrylonitrile, etc.], unsaturated amides [('
(meth)acrylamide, etc.], unsaturated carboxylic acid anhydride (reta)acrylic acid, maleic anhydride, chloro1-
Examples include phosphoric acid, itaconic acid, etc.

Preferred is meth)acrylate.

Regarding Acrylic/Levodiol, please refer to the Japan Rubber Association magazine.

Vol. 45, No. 5, 1972, pp. 77-79; JP-A No. 48-1099, JP-A No. 56-15417; JP-A-55-19273; JP-A-56-15417; JP-A-39-29379 No.: U.S. Pat. No. 3,028,367 and Japanese Patent Application No. 55-65,767. Furthermore, a vinyl acetate (co)polymer hydrolyzate can also be used.

The hydroxyl value of acrylic polyol is usually 10 to 450.

The molecular weight is preferably 20 to 200, and the molecular weight is usually 500 to 20,000, preferably 800 to 10,000. The number of functional groups is usually 2 or more.

The polyester polyol is obtained by ring-opening polymerization of a polyester polyol or lactone obtained by polycondensing cica-7 levonic acid, its ester or halide with a low-molecular polyol in the presence of a low-molecular polyol-7. Examples include polylactone polyol Nether. For details, please refer to the patent application No. 53-7942.
It is described in the specification of No. 2.

Examples of polyether polyols include polyols prepared by ring-opening addition of alkylene oxide to low-molecular-weight polyamines, and ring-opening polymerization type polyether polyols produced by ring-opening polymerization of alkylene oxides.Details thereof is described in Japanese Patent Application No. 55-65767. Polymer polyolefins are also described in U.S. Pat.
-24737 publication, JP-A-50-15894 publication,
Japanese Patent Publication No. 47-47597, Japanese Patent Publication No. 53-1679
Examples include those described in Publication No. 6 and Japanese Unexamined Patent Publication No. 53-42294.

Among these polymeric polyols, preferred are acrylic polyols, polyester polyols, and polyols containing these as main components.

(When obtaining a reaction product between ω and ■, the ratio is (ω
The equivalent ratio of the NCO group (free NCO group) of (b) to the active hydrogen-containing group of (b) is usually α8:L2 to L2:α8.

Preferably α9:11 to 1.1:09. The reaction temperature is usually 50-100°C, preferably 70-90°C. Furthermore, low-molecular-weight polyols used as necessary in the components
Examples include low molecular weight glyco-/L/(ethylene glycol, fluoropylene glycol, 7" fV glycol, 1
4-Butanedio-μ,1. α-hexane di-1, etc.), low molecular weight trio-/L/(trimethylolpropane,
Examples include glycerin, castor oil, and mixtures thereof. Among these, preferred are ethylene glycol-/l',1,4-butanediol, glycerin and trimethylolpropane.

The other component of the composition of the present invention, the crosslinking agent (2), includes low-molecular polyols and low-molecular polyamines. As the low-molecular polyol, the same low-molecular polyols as described in the section of component (1) above can be used. Among these, preferred are ethylene glyco-1, 1,4
-butanedio-l, glycerin and trimethylolpropane.

Alkanolamines [mono-, di-, 1-ethanolamine, 1-lyisopropanolamine, N, N, N', N'-tetrakis (
2-hydroxypropyl) ethylenediamine], aliphatic polyamines (ethylenediamine, hegisanoethylenediamine), aromatic polyamines (piperazine, N-amine ethylpiperazine, etc.), and mixtures thereof. Among low-molecular polyols and low-molecular polyamines, low-molecular polyols are preferred.

The number of functional groups of the crosslinking agent is usually 2 to 4. The crosslinking agent is described in Japanese Patent Application No. 79422/1983.

The coating composition of the present invention contains (i) and (i).
It consists of night. The ratio of (g) and
:L2~1.2208. Preferably 09-1,1-L1
: This is the ratio of α9. In addition, the ratio (total NCO of ω:08) is preferably 0.9:1.1 to 11:09.

The solvent used for the solvent solution is aromatic hydrocarbons (toluene, xylene, etc.).

Ester type (ethyl acetate, methyl cellosolve acetate, etc.), ketone type (methyl ethyl ketone, methyl isobutyl ketone, etc.), amide type (dimethyl lenophor I leno amide N-methylpyrrolidone, etc.), sulfenophoxide type (dimethyl sulfoxide, etc.), chlorine type (Tetracarbonized carbon-Pl-!J chlorethylene, etc.) and other solvents may be used alone or in mixtures. Among these, preferred are ester-aromatic hydrocarbon-based, ketone-aromatic hydrocarbon-based and ENTEL-chthonic-aromatic hydrocarbon mixed solvents.

Methods for producing a solution containing (f) and a) include adding and mixing (e) and (i) into a solvent; mixing (e) and (e) and diluting them with a solvent; and a solution of (e) and (f). and a method of mixing the solution of (■) and the solution of (e) or (0).

When using the coating composition of the present invention, a pre-mixed solution of (1) and (0) may be used in storage, or each component may be mixed prior to use. Usually, for reasons of convenience, stored compositions are used.

Materials to which this coating composition can be applied include coating materials that require curability, such as rubber-like materials (natural rubber, synthetic rubber, EPDM rubber, polyurethane rubber, foamed rubber, polyurethane foam, vinyl foam, etc.), and materials such as plastic, wood, metal, glass, and leather. Also, undercoat material, E
It can be applied as painted paulownia wood.

When applying the coating composition of the present invention to a material, conventional coating methods such as brushing, dipping, and spraying can be applied, but spraying is suitable.

After the coating composition is applied to the base material, it is baked and cured by heating. Curing conditions are generally 100 to 160℃ and 10 to
60 minutes, preferably 110-1'2 at 40℃
The duration is 0 to 40 minutes. During curing, a curing catalyst can be added to accelerate curing, if necessary. In this case, curing can be performed at a lower temperature and in a shorter time than the above conditions.

In addition to the above-mentioned components, the coating composition of the present invention may optionally contain other components such as various types of pigments (coloring pigments, two-body pigments, etc.) commonly used in coatings, fillers, plasticizers, antioxidants, surfactants, etc. agents and other additives may be used.

The coating composition of the present invention can be cured at a lower temperature than conventional one-component heat-curable urethane coating compositions (for example, the curing conditions were 140°C for 30 minutes, but the curing conditions were 120°C for 30 minutes). ℃309), which is energy saving/leggy. The coating composition of the present invention is a solvent solution type, and the coating composition has good gloss and spreadability, as well as other coating properties.

The coating composition of the present invention can be used as a heat-curing coating composition for road vehicles (automobiles, etc.), architecture-related equipment (e.g. fences, etc.), ships, railway vehicles, or plastics (made of urethane). Used in paints for automobile bumpers, etc.

The present invention will be further explained below with reference to Examples, but the present invention is not limited to these Examples. Parts in Examples indicate parts by weight.

Example 1 1.222 parts of isophorone diisocyanate and 87 parts of hydrene oxime were gradually added to the mixture at 20.-25°C.
The partially blocked isocyanate 1-
The compound was obtained. The free NCO% was measured to be a7%. Next, in this solution, acrylic polyol-/I/(β-hydroxyethyl methacrylate-1, methyl methacrylate, butyl methacrylate copolymer 50% butyl acetate, xylene mixture @ liquid, hydroxyl group equivalent -1, 0 0 0 )
1,000 parts (NCO10H=1/1) was added and reacted at 80 to 90°C for 7 hours to obtain a product. When the NCl) group is measured by infrared absorption Nupectol, N
CO absorption had disappeared.

To this reaction product, 45 parts of 1-dimethylolpropane was added and dissolved uniformly at 40 to 50°C, and then 4 g of zinc octyl-Vate was added as a catalyst to obtain the composition of the present invention.

Example 2 A composition of the present invention was obtained in the same manner as in Example 1 except that hydrogenated 4,4'-diphenylmethane diisocyanate-1.

Water [K in a mixed solution of 264 parts of 4,4'-diphenylmethane diisocyanate and 351 parts of toluene
87 parts of mef/L'eth)V ketoxime was gradually processed and reacted at 20-25°C for 12 hours to obtain a partially blocked isocyanate l-compound. Free NCO% was determined to be aO%.

Next, add 1,000 parts (same as acrylic polyol 1) to this solution (NCO10H=t/
1') was added and reacted at 80 to 90°C for 7 hours to obtain a product.

When NCO groups are measured using infrared absorption Nupecl, N
CO absorption had disappeared.

To this reaction product, 45 parts of 1-dimethylolpropane was added and dissolved uniformly at 40 to 45 DEG C., and then 4 tons of zinc octylate was added as a catalyst to obtain the composition of the present invention.

Comparison Example 1 87 parts of methyl ethyl ketoxime was added to a mixed solution of 222 parts of inphorone diisocyanate and 309 parts of 1-toluene.
The mixture was gradually added and reacted at 20-25°C for 12 hours to obtain a partially blocked isocyanate compound. Yu91 NC
When 0% was measured, it was 67%.

Next, during the night, 2,000 parts of acrylic polyol (same as in Example 1) (NGO10H=1/2)
was added and reacted at 80-90°C for 7 hours to obtain a product.

When NCO groups are measured by infrared absorption
CO absorption had disappeared.

To this reaction product, 6 tons of lead octylate was added as a catalyst and uniformly dissolved to obtain a coating composition.

Test Example 1 The coating compositions of Examples 1 and 2 and Comparative Example 1 were applied to an iron plate, and baked at 120°C for 30 minutes to cure. To test the hardening of the obtained coating film, toluene was spotted at room temperature, and after it was allowed to stand for 2 hours, the toluene was wiped off, and the state of the coating film was observed and the pencil hardness was determined. The results were as shown in Table 1 below.

Table-1

Claims (1)

[Scope of Claims] 1. A one-component heat-curable urethane paint consisting of a solution containing a partially blocked isocyanate compound (a) and a crosslinking agent consisting of polyol/I/and/and a low-molecular polyamine. Composition for use. 2,' (b) is an acrylic polyol, a borie ether polyol, or a polyol/polyester containing these as main components.
The composition according to claim 1, which is The composition according to claim 1 or 2, wherein the blocking rate of a'(a) is 30 to 70%. 4. According to any one of claims 1 to 3, the equivalent ratio of the free NGO group of (a> to the active hydrogen-containing group of (D) is from 0.8:L2 to 1.2:α8. A composition in which the equivalent ratio of the total NCO groups (total of free NGO groups and latent NGO groups) in 5(a) to the active hydrogen-containing groups in [■ and ■] is 0.
8: The composition according to any one of claims 1 to 4, wherein α8 is 1.2 to 1.2 to α8. a (a) is a non-aromatic polyisoane l-, =4-
6. The composition according to any one of claims 1 to 5, which is a partially blocked polyisocyanate compound selected from prepolymers of 44-≠Chichiko ÷-+ and ←-F.