JPH04255773A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, containing an oxidative polymerization type alkyd resin, etc., as a substrate resin, a specific polyisocyanate compound and a metallic drying agent as a cross-linking agent, excellent in drying properties, weather resistance, adhesion, etc., and capable of imparting excellent finish to coated surfaces poor in solvent resistance. CONSTITUTION:The objective composition is obtained by blending (A) an oxidative polymerization type alkyd resin and/or an oxidative polymerization type acrylic graft alkyd resin as a substrate resin with (B) (i) a polyisocyanate compound [preferably at 0.3-1.0 molar ratio of NCO/OH based on the component (A)] selected from isocyanurate type adducts or diol adducts of aliphatic diisocyanates and alicyclic diisocyanates and (ii) a metallic drying agent such as cobalt or vanadium [in an amount of preferably 0.2-0.5wt.% based on the component (A)] as a cross-linking agent.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a coating for curing a coating film by using a metal drying agent and a specific polyisocyanate compound as a crosslinking agent in an oxidation polymerization type alkyd resin and/or an oxidation polymerization type acrylic graft alkyd resin. The present invention relates to a composition.

0002

[Prior Art] Compositions containing oxidation polymerization type alkyd resins or oxidation polymerization type acrylic graft alkyd resins as base resins have been widely used for coating steel structures, industrial machinery, non-metallic products, etc. There is. Usually, the crosslinking method for the composition is to oxidatively polymerize the unsaturated double bonds present in the resin using a metal drying agent.
In recent years, improvements in drying properties, weather resistance, adhesion, water resistance, etc. have been desired from the viewpoint of process shortening, labor saving, resource saving, etc., and the above-mentioned crosslinking methods cannot fully satisfy these demands.

[0003] In order to solve the above problem, Japanese Patent Application Laid-open No. 161869/1983 discloses that a polyisocyanate compound is blended into the composition, and a polyisocyanate compound is blended into the oxidation polymerization type alkyd resin and/or the oxidation polymerization type acrylic graft alkyd resin. It is proposed that the unsaturated double bonds present in the resin be oxidatively polymerized using a metal drying agent, and at the same time, the hydroxyl groups present in the resin be reacted with the polyisocyanate compound to cure the resin. In a film made of such a composition, a crosslinking reaction with the polyisocyanate compound occurs earlier than an oxidative polymerization reaction occurs in the early stage of drying, so the film dries quickly and hardness increases faster than in the case of only an oxidative polymerization reaction.
It also eliminates stickiness, and the hydroxyl groups are reacted with a polyisocyanate compound to introduce urethane bonds, which greatly improves coating performance.

However, in such compositions, the polyisocyanate compounds used are not compatible unless the solvent used for adjusting the viscosity and adjusting the molar ratio of hydroxyl groups/isocyanate groups is a true solvent such as xylene, toluene, or ethyl acetate. , a considerable amount of true solvent will be mixed into the composition, which will have an adverse effect on the compatibility with the base resin, and will cause lifting when overcoating the coated surface with oil-based paint or lacquer, etc. Materials with poor solvent resistance,
For example, when painted on plastic, etc., the surface of the material melts, resulting in a poor finish.

[0005]

[Problems to be Solved by the Invention] The object of the present invention is to provide a coating mainly based on oxidation polymerization type alkyd resin and/or oxidation polymerization type acrylic graft alkyd resin, which can be coated even on coated surfaces with poor solvent resistance. An object of the present invention is to provide a composition.

[0006]

[Means for Solving the Problem] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that by using a specific polyisocyanate compound as a crosslinking agent, the contamination of the true solvent can be suppressed. The present inventors have discovered that the polyisocyanate compound has excellent coating performance because the polyisocyanate compound has extremely good compatibility with the base resin, and has completed the present invention.

That is, the present invention provides a coating composition comprising an oxidatively polymerizable alkyd resin and/or an oxidatively polymerizable acrylic graft alkyd resin as a base resin, and a polyisocyanate compound and a metal desiccant as a crosslinking agent. The present invention relates to a coating composition characterized in that the isocyanate compound is selected from isocyanurate type adducts or diol adducts of aliphatic diisocyanates, alicyclic diisocyanates.

The oxidation-polymerizable alkyd resin used in the present invention is produced by reacting a commonly known polyhydric alcohol with a polybasic acid, an unsaturated fatty acid, and, if necessary, a monobasic acid such as benzoic acid. In addition, the oxidative polymerization type acrylic graft alkyd resin further contains, in addition to the alkyd resin,
It can be obtained by reacting a polymerizable unsaturated monomer or the like.

Polyhydric alcohol components of the alkyd resin used in the present invention include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol,
2,2-dimethylpropanediol, glycerin, trimethylolethane, trimethylolpropane, 1,2,
Polyhydric alcohols such as 6-hexanetriol, pentaerythritol, sorbitol, diglycerol, and dipentaerythritol can be used.

Examples of the polybasic acid component include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, maleic anhydride, fumaric acid, tetrachlorophthalic anhydride, adipic acid, succinic acid, and sebacic acid. Basic acids are used.

[0011] The unsaturated fatty acids used in the present invention include linseed oil, tung oil, Chinese tung oil, sardine oil, safflower oil, soybean oil, sardine oil, eno oil, tall oil, dehydrated castor oil, olive oil, cottonseed oil, rice bran oil, Fatty acids such as castor oil and coconut oil, and one or more of these oils and fats are used. Fatty acids derived from the above oils may also be used.

[0012] The alkyd resin used in the present invention is prepared by subjecting the polyhydric alcohol, polybasic acid, and unsaturated fatty acid to the same reaction conditions as for ordinary alkyd resins, for example, 150 to 250%
It can be produced by reacting at ℃ for 1 to 15 hours.

The monomer used in the production of the acrylic graft alkyd resin used in the present invention is not particularly limited as long as it has a polymerizable unsaturated group, such as acrylic acid, methacrylic acid, maleic acid, anhydride, etc. Unsaturated carboxylic acids such as maleic acid, fumaric acid, crotonic acid, itaconic acid; methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-acrylate
- Acrylic acid esters such as butyl, glycidyl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, glycidyl methacrylate, 2-methacrylate - Methacrylic acid esters such as ethylhexyl; styrenic monomers such as styrene, vinyltoluene, and α-methylstyrene; and one or more of vinyl acetate, acrylonitrile, acrylamide, allyl acetate, allyl alcohol, vinyl chloride, vinylidene chloride, etc. More than one species is used.

As a radical initiator for graft polymerization, an organic peroxide initiator such as benzoyl peroxide; α
, nitrile initiators such as α'-azobisisobutyronitrile, and other radical initiators are used.

The polyisocyanate compound that can be used in the present invention is an isocyanurate type adduct of a diisocyanate compound selected from aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate, and alicyclic diisocyanates such as isophorone diisocyanate. Alternatively, a diol adduct obtained by reacting 2 moles of the diisocyanate compound with 1 mole of diol can be used. One or more of the diisocyanate compounds forming the isocyanurate-type adduct may be a diol adduct.

[0016] As such a polyisocyanate compound,
Specifically, hexamethylene diisocyanate to isocyanurate, for example, Duranate TPA-100 (
Asahi Kasei Co., Ltd.), Takenate XD-170HN (Takeda Pharmaceutical Co., Ltd.), Coronate HX (Japan Polyurethane Co., Ltd.), Sumidur N-3500 (Sumitomo Bayer Urethane Co., Ltd.)
, Burnock DN-901 (manufactured by Dainippon Ink &Chemicals); diol-modified hexamethylene diisocyanate to isocyanurate series, such as Burnock DN-990,
-991, -992 (manufactured by Dainippon Ink &Chemicals); Isophorone diisocyanate-isocyanurate series, e.g. Desmodur Z-4370 (manufactured by Sumitomo Bayer Urethane Co., Ltd.); Hexamethylene diisocyanate-diol adduct series, e.g. Burnock DN -921 (manufactured by Dainippon Ink & Chemicals) and the like are commercially available products.

Suitable solvents for use in the composition of the present invention include hydrocarbon solvents having a boiling point of about 140° C. or higher and poor solvents such as mineral spirits (industrial gasoline). Specifically, A-solvent (manufactured by Nippon Oil Co., Ltd.), Swazol 310, Swazol 1000 (manufactured by Cosmo Oil Co., Ltd.), Exxon Naphtha No. 5 (manufactured by Exxon Chemical Co., Ltd.) HAWS
, LAWS (manufactured by Shell Chemical Co., Ltd.), and can be appropriately selected depending on the polyisocyanate compound used. When a true solvent such as xylene, toluene, ethyl acetate, etc. is used in the production of the base resin, it is appropriate that the amount of the solvent be 20% by weight or less, preferably 10% by weight or less in the composition. Exceeding this range is undesirable because lifting tends to occur when overcoating the surface with oil-based paint, lacquer, or the like.

The mixing ratio of the alkyd resin and/or acrylic graft alkyd resin according to the present invention and the polyisocyanate compound is 0.000 molar ratio of NCO/OH.
The range is 1 to 1.5, preferably 0.3 to 1.0. In the case of a mixture with a molar ratio of less than 0.1, drying properties, hardness rise, and tackiness are insufficient, while if it exceeds 1.5, physical properties, water resistance, etc. will be adversely affected due to excess polyisocyanate compound. appears.

The metal desiccant used in the present invention includes:
For example, cobalt, vanadium, manganese, cerium,
Metals such as lead, iron, copper, nickel, chromium, calcium, zirconium, zinc, tin, etc., and rosin (abietic acid), linseed oil fatty acid, soybean oil fatty acid, naphthenic acid, diethylhexanic acid (synthetic octylic acid), etc. Soap can be used.

The amount of the metal drying agent added to the alkyd resin and/or acrylic graft alkyd resin according to the present invention (in terms of metal amount) is 0.1 to 1.0% by weight, preferably 0.2 to 0.5% by weight. % is good. If it is less than 0.01% by weight, drying properties and adhesiveness will be insufficient;
If it exceeds this, the pot life will be short and water resistance will likely be poor.

The coating composition of the present invention can also be used as a clear, pigmented enamel, filler-contained base coat, or intermediate coat. When using it, it can be applied with a regular brush, air spray, airless spray, roller, etc.

For curing, curing at room temperature is sufficient, but there is no problem in accelerating curing by heating.

[0023]

Effects of the Invention The coating film obtained by the coating composition of the present invention is strong and has good properties such as water resistance, weather resistance, and adhesion. Even when applied to a coated surface, it can provide a good finish without any problems.

[0024]

[Examples] The present invention will be explained in detail below with reference to Examples, but the present invention is not limited by the Examples. In addition, “
All "parts" and "%" are "parts by weight" and "% by weight."
represents.

Production Example 1 In a three-neck flask, 587 parts of soybean oil fatty acid, 251 parts of phthalic anhydride, 7.5 parts of maleic acid, 195 parts of pentol,
After charging 29 parts of ethylene glycol and heating at 180°C for 1 hour, the temperature was raised to 230°C and reaction was carried out for 8 hours. A general oxidative polymerization type alkyd resin solution with an oil length of 61 was obtained.

Production Example 2 555 parts of safflower oil and 166 parts of pentol were placed in a three-necked flask and heated to raise the temperature to 200°C. After adding the catalyst Lissage, the temperature was raised to 240°C and heated for 30 minutes. , an esterification reaction was carried out. 269 parts of phthalic anhydride, 48 parts of paratertiary butylbenzoic acid.
When 4 parts of xylene for reflux was charged and the reaction was carried out at 220°C for 6 hours, an oxidative polymerization type alkyd with a viscosity of U and an OH value of 16 and a very common oil length of 55 was obtained at a concentration of 55% (diluted with mineral spirit). A resin solution was obtained.

Production Example 3 482 parts of linseed oil fatty acid, 168 parts of phthalic anhydride, 151 parts of tetrahydrophthalic anhydride, 92 parts of pentol, 177 parts of trimethylolethane, and 600 parts of A-solvent were placed in a three-necked flask and heated at 120°C for 2 hours. A base alkyd resin was obtained by reaction. This base alkyd resin 18
After charging 3 parts of xylene, 77 parts of xylene, 59 parts of styrene, 30 parts of methyl methacrylate, 11 parts of acrylonitrile, and 10 parts of 2-ethylhexyl acrylate,
After aging for a period of time, 3 parts of benzoyl peroxide and 67 parts of xylene were added dropwise over 1 hour, followed by further reaction for 2 hours. This was diluted with A solvent to obtain a very common acrylic graft alkyd resin solution having a viscosity of X and an OH value of 20 at a concentration of 60%.

Example 1 44.0 parts of the alkyd resin solution obtained in Production Example 1 and 26.4 parts of titanium oxide were mixed and dispersed in a shaker until the particle size became 10 μm or less using a finesse gauge.
．． 4 parts and 0.13 parts of cobalt naphthenate were added. Furthermore, 5.6 parts of Desmodur Z-4370 and A solvent (
5.6 parts of mineral spirit) were added to obtain the coating material of Example 1. A test plate was prepared using this paint and heated to 20°C.
After drying for 7 days, a performance test was conducted. The results are shown in Table 2.

Examples 2 to 6 and Comparative Examples 1 to 4 Paints were obtained in the same manner as in Example 1 according to the formulations in Table 1. Test plates were prepared for each paint in the same manner as in Example 1, and performance tests were conducted. The results are shown in Table 2.

[0030]

[Table 1] (Note 1) Desmodur Z-4370: Manufactured by Sumitomo Bayer Urethane, non-volatile content 70%, NCO content 11.
Isocyanurate form of 5% isophorone diisocyanate. (Note 2) Burnock DN-991S: Manufactured by Dainippon Ink & Chemicals, 100% non-volatile content, NCO content 13.
Isocyanurate type of 0% diol-modified hexamethylene diisocyanate. (Note 3) Duranate TPA-100: Manufactured by Asahi Kasei Corporation, isocyanurate type of hexamethylene diisocyanate with 100% non-volatile content and 23.3% NCO content. (Note 4) Coronate HL: Manufactured by Nippon Polyurethane Co., Ltd.
Trimethylolpropane adduct type of hexamethylene diisocyanate with non-volatile content of 75% and NCO content of 12.8%. (Note 5) Duranate 24A-90E: Manufactured by Asahi Kasei Corporation, biuret type adduct of hexamethylene diisocyanate with non-volatile content of 90% and NCO content of 21.2%.

[0031]

[Table 2]

The test method shown in Table 2 is as follows. (*1) Pencil hardness: A scratch test was conducted with a pencil according to JIS K5400. (*2) Gloss: 60 degree specular reflectance was examined according to JIS K5400.

(*3) Recoatability: Each coating was applied to a coated plate obtained by coating a mild steel plate with Rasgon 100 (manufactured by Kansai Paint Co., Ltd., an oil-based anti-rust paint) and drying it at 20°C for one day. Each was painted with a brush and the condition of the painted surface was observed. 〇: Good ×: Stiffness occurs

(*4) Water resistance: Place the test plate in tap water (20°C)
After being immersed in water for 14 days, the condition of the coated surface was examined. 〇: No abnormality △: Slight blister formation ×: Gloss decrease, significant blister formation

(*5) Alkali resistance: After the test plate was immersed in a 5% caustic soda solution for 3 days, the condition of the coated surface was examined. 〇: No abnormality ×: Blister occurrence

(*6) Acid resistance: After the test plate was immersed in a 5% hydrochloric acid solution for 3 days, the state of the coated surface was examined. 〇: No abnormality ×: Blister occurrence

(*7) Accelerated weather resistance: Weatherometer (
The appearance of the coating film was examined after conducting an accelerated weathering test on the test plate for 750 hours (manufactured by Suga Test Instruments Co., Ltd.). 〇: No abnormality △: Only gloss reduction ×: Significant gloss reduction, cracking, chalking (whitening)
occurrence

(*8) Adhesiveness: Cut 100 goblets of 1 x 1 mm in size on the test plate using a knife to reach the substrate, paste cellophane tape on top of the cut, and press it vigorously. The number of gobans remaining after peeling was examined.

(*9) Bending resistance: Place the test plate in a bending tester with the coating surface outside, bend it, and find the diameter of the circular bar that fits the maximum bending surface without any cracks or chips. I looked into it.

Claims (1)

[Claims] 1. A coating composition comprising an oxidative polymerizable alkyd resin and/or an oxidative polymerizable acrylic graft alkyd resin as a base resin, and a polyisocyanate compound and a metal drying agent as crosslinking agents, wherein the polyisocyanate compound is 1. A coating composition selected from isocyanurate-type adducts or diol adducts of aliphatic diisocyanates or alicyclic diisocyanates.