JPS6399269A - Low temperature-curable coating composition - Google Patents

Abstract

PURPOSE:To provide the titled composition outstanding in curability and storage stability, capable of giving coating film of high solvent and impact resistances, etc., comprising a hydroxyl group-contg. compound, metal chelate compound, etc., carboxylic acid anhydride group-contg. compound and chelate-forming compound. CONSTITUTION:The objective composition comprising (A) a hydroxyl group- contg. compound (pref. low molecular weight diol, polyester resin, acrylic resin, silicone resin, or polybutadiene resin), (B) a metal chelate compound (pref. Ti-, Al-, Zr-, Co-, Cr-, or Ni-chelate compound) or metal alcoholate compound (pref. Ti-, Al-, or Zr-alcoholate compound), (C) a carboxylic acid anhydride group-contg. compound (pref. low molecular weight carboxylic acid anhydride), and (D) a chelate-forming compound (pref. keto-enol tautomeric compound).

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a coating composition that can be cured at low temperatures and provides a highly durable coating, particularly coating materials for automobiles, plastic decks, and electrical materials. Regarding coating compositions suitable as.

(Prior Art) Automotive paints are usually made of acrylic polyol or polyester polyol containing melamine resin as a curing agent. These coats cost $4 for 130
It requires heat curing at ~180°C for 10 to 30 minutes, making it unsuitable for coating thermoplastic materials such as plastics, and requiring high energy costs.

Two-component urethane paints are often used as paints for automobile refinishing, but they have the problem of toxicity due to residual low-molecular-weight isocyanate compounds, and their pot lives are short, making them inconvenient for work.

What is desired is a coating composition that cures at low temperatures, e.g. 50-150 DEG C., and provides a high degree of crosslinking without the use of isocyanates.

JP-A-50-2798 discloses that an acid anhydride is used as a curing accelerator in an epoxy resin, and β is used as a curing accelerator.
- A curable epoxy resin composition using a reaction product obtained by reacting at least one of a metal chelate compound of a diketone, an acid anhydride, and a cyclic ether compound is disclosed. However, this epoxy resin composition has low reactivity and is heated at 90°C for 16 hours and then at 130°C for 2 hours.
A curable resin was obtained by baking for 4 hours.

A sufficient crosslinked product cannot be obtained by curing at a low temperature and for a short time.

JP-A-56-100869 discloses a coating made by mixing an acrylic copolymer or alkyd resin having a carboxyl group in the molecule with an aluminum alcoholade complex compound, a keto-enol type tautomer compound, and a solvent. There is a description of a one-component room-temperature curing coating composition in which 0.01 to 1.0 wt% of a monovalent metal hydroxide is added to the composition, but it is still difficult to cure under low temperature and short curing conditions. It is not possible to obtain a coating film having solvent resistance.

(Progress of the Invention) Previously, the present inventors filed an application for a low-temperature curable coating composition comprising a hydroxyl group-containing polymer, a metal chelate compound or metal alcoholate compound, and an acid anhydride compound (Japanese Patent Application No. 1982-97759). ). This coating composition is 60'C~1
20'C1 Preferably, a cured film with sufficient coating performance can be obtained at 80°C to 100°C. As a result of research, the present inventors have found that in order to further improve the performance of the above-mentioned coating composition, in particular to improve the storage stability, the present inventors have found that, in addition to the above-mentioned components, a compound having chelate-forming ability is blended into the composition. It has been found that the storage stability of the paint is significantly improved.

Furthermore, it has been revealed that a cured film having sufficient coating performance can be obtained without any adverse effects on curability, and has the secondary effect of further improving the appearance.

(Structure of the Invention) The present invention comprises (A) a compound having a hydroxyl group, (r3) a metal chelate compound or a metal alcoholate compound, (C) a compound having a carboxylic anhydride group, and (D) a compound having a chelate-forming ability. A low temperature curable coating composition is provided.

The present invention also provides a low-temperature curable coating composition, which further contains a tertiary amine compound (E) as a curing accelerator in the above composition.

Component Q The compound having a hydroxyl group used in the present invention may have either a high molecular weight or a low molecular weight, and preferably has a plurality of hydroxyl groups. Specifically, compounds having hydroxyl groups include low molecular weight polyols, polyester resins, acrylic resins,
Silicone resin, polybutadiene resin or a mixture thereof. Examples of low molecular weight polyols include low molecular weight diols (e.g. ethylene glycol, propylene glycol, 1,6-hexanediol, diehylene glycol, 1,5-bentanediol, etc.), higher functionality polyols ( Examples include neopendel glycol, glycerin, trimethylolpropane, etc.). Examples of such polyester resins include oil-free alkyds, long oil alkyds, short oil alkyds, very long oil alkyds, and medium oil alkyds. Examples of acrylic resins include acrylic polyols, styrene-containing acrylic polyols,
Examples include CAB-modified acrylic polyol, alkyd-modified acrylic polyol, NC-modified acrylic polyol, oil-free alkyd-modified acrylic polyol, and the like. Examples of silicone resins include silanol-terminated methyl silicone, silanol-terminated alkyl silicone, silanol-terminated phenyl silicone, and silanol-terminated methylphenyl silicone. Examples of polybutadiene resins include hydroxyl group-terminated polybutadiene. Preferably, the polymer has primary hydroxyl groups, particularly terminal hydroxyl groups. Although a secondary hydroxyl group or a tertiary hydroxyl group is not particularly preferred due to steric hindrance, their presence is not a hindrance. A compound having a hydroxyl group may have other functional groups in addition to the hydroxyl group. For example, those having a tertiary amine group, specifically triethanolamine or tripropaturamine, have both functions because the tertiary amine group functions as a curing accelerator as described below. The hydroxyl value of the compound having a hydroxyl group is 40 to 200, preferably 60 to 150.

When it exceeds 200, the flexibility of the crosslinked coating film decreases and cracks are likely to occur in the coating film. If it is less than 40, a sufficient degree of crosslinking cannot be obtained.

Boe Shimaguchi Various compounds can be mentioned as the metal chelate compound or metal alcoholate compound used in the present invention, but aluminum compounds [e.g., aluminum tris (ethyl acetoacetate), aluminum tris (acetylacetonate), aluminum di- Conititanium compounds such as n-butoxide monoethyl acetoacetate, aluminum di-n-butoxide monomethyl acetoacetate, aluminum diisobutoxide monomethyl acetoacetate [e.g. di-isopropoxy-bis(acetylacetone) titanate, di -n-butoxy-
Bis(triethanolamine) titanate, dihydroxy-bis(raftic acid) titanate, tetraoctylene glycol ditanate, etc.; Zirconium compounds [e.g., zirconium tetra(acetylacetonate), zirconium acetate, zirconium laurate, etc.]
Cobalt compounds [e.g., cobalt bis(acetylacetonate) cobalt oxalate, etc.]; Zinc compounds [e.g., zinc salicylate, zinc benzoate, zinc oleate, zinc stearate, etc.]; Nickel compounds [e.g., bisacetylacetonate, zinc stearate, etc.]; nickel nickelate, nickel dimethylglyoxime, nickel oxalate, etc.]; and mixtures thereof. Preferably, it is an aluminium or zirconium compound with little coloring. The amount of the metal chelate compound or metal alcoholate compound added is 0.1 to 3.0 equivalents of metal, preferably 0.3 to 1.0 equivalents, per 1 equivalent of hydroxyl group of the polymer. If the amount added is too large or too small, a good cured coating film cannot be obtained. This metal chelate compound or metal alcoholate compound acts as a crosslinking agent, and in the present invention participates in the crosslinking reaction via the acid anhydride described below.

Component (C) Various known compounds having a carboxylic anhydride group used in the present invention include maleic anhydride,
low molecular weight acid anhydrides such as phthalic anhydride, hydrogenated phthalic anhydride, 4-methyl hydrogenated phthalic anhydride, pyromellitic anhydride, pyromellitic anhydride triglyceride, trimellitic anhydride ethylene glycol ester, or mixtures thereof;
Alternatively, high molecular weight acid anhydrides such as copolymers of ethylenic acid anhydrides such as itaconic anhydride and maleic anhydride and α,β ethylenic monomonomers may be mentioned. The acid value of the high molecular weight acid anhydride is 30-500, preferably 50-350.

If compounds having a carboxylic anhydride group (hereinafter abbreviated as acid anhydride) are classified into -valent, divalent, and trivalent with respect to the acid anhydride group, in the present invention, polyvalent acid anhydrides of divalent or higher valence are highly This is preferred because it provides good curability. Examples of preferred acid anhydrides include trimellitic anhydride ethylene glycol ester, trimellitic anhydride triglyceride and water additives thereof, or high molecular weight acid anhydrides.

It is believed that the acid anhydride acts on the metal chelate compound or metal alcoholate compound to increase reactivity and promote curing. In addition, the solubility of high molecular weight acid anhydrides with other components is improved, and the addition of tertiary amine compounds (described later)
'', curing is further accelerated and further low-temperature curing is possible.The amount of acid anhydride blended is 0.1 to 10.0 equivalents of acid anhydride groups, preferably 0.1 to 10.0 equivalents of acid anhydride groups per 1 equivalent of hydroxyl groups in the polymer. It is 0.5 to 2.0 mm.A good cured film cannot be obtained whether the amount of acid anhydride is large or small.

Component (D) The compound having a chelate-forming ability used in the present invention is:
It can form a chelate compound with the metal of component (I3), thereby blocking the reaction of the metal compound and inhibiting the reaction with the acid anhydride at room temperature.
r. Typical examples include keto-enol tautomers such as acetylacetone, benzoylacetone, dibenzoylmethane, butyl acetoacetate, methyl acetoacetate, butyl acetoacetate, dimethyl malonate, diethyl malonate, dibutyl malonate, etc. Can be mentioned. The amount of the chelate-forming compound added is 1 hydroxyl group of the R combination.
The amount is 0.5 to 5 equivalents, preferably 1 to 3 equivalents. If the amount is less than 0.5 to 1, the storage stability of the coating material will be insufficient, and if it exceeds 5 equivalents, the curability at low temperatures will be low.

Component (E) The tertiary amine compound used in the present invention is added to further promote curing at low temperatures. The tertiary amine compound is preferably one that is volatile at low temperatures. Examples of suitable tertiary amine compounds include triethylamine, tripropylamine, tributylamine, and the like. The tertiary amine compound is 0.0 per equivalent of hydroxyl group! ~1.5
The amount is preferably 0.1 to 1.0 equivalent. 0.
If the amount is less than 1 equivalent of O, a good low-temperature crosslinked film cannot be obtained.

Although it is possible to add 1.5 equivalents or more, comparable effects cannot be obtained.

Other components 1 to 1 may be formulated as a clear coating composition, or they may be blended together with pigments to form a paint. Pigments may be of any conventional type, such as iron oxide, lead oxide, strontium chromate, carbon black, cold dust, titanium dioxide, talc, barium sulfate or color pigments such as cadmium yellow, cadmium red, Chromium yellow and metallic pigments such as aluminum flakes may also be used.

Pigment content in a paint is usually expressed as the pigment to nonvolatile weight ratio of the coating composition. In the practice of this invention, the pigment to coating composition nonvolatile weight ratio may be as high as 2:1 and is often in the range of 0.05 to 1:1.

The coating compositions of the present invention typically have a liquid diluent present in the composition. A liquid diluent is a solvent or a non-solvent,
They are volatile, removed after application, and require a reduction in viscosity so that the coating can be applied to the desired uniform and controllable thickness by a simple application method, ie, by spraying. The liquid diluent also aids in substrate wetting, polymer component compatibility, package stability and lamination or film forming properties. Examples of suitable diluents are aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone and methyl isobutylethyl ketone, alcohols such as isopropyl alcohol, n
-butyl alcohol, monoethers of glycols, such as ethylene glycol and diethylene glycol, monoether glycol acetates, such as 2-ethoxyethyl acetate, or compatible mixtures thereof. The diluent is 60% by weight based on the total weight of the diluent and non-volatile content of the coating composition.
up to 20% to 55% by weight.

In addition to the above ingredients, various fillers, plasticizers, antioxidants,
UV absorbers, flow control agents, surfactants, and other formulation additives may be used as desired. These materials may be optionally present, typically up to about 10% by weight based on the non-volatile content of the coating composition.

The coating composition of the present invention can be applied by spray coating, brush coating,
Coating may be done by dip coating, roll coating, flow coating, etc. The coating compositions of the present invention may be used on essentially any substrate, such as wood, metal, glass, fabric, plastic, foam, etc., or on various brimer surfaces. The paints are particularly advantageous for plastic and metal surfaces, such as steel and aluminum.

Generally, the film thickness will vary depending on the desired application. In most cases, 0.5 to 3 mils are useful.

After coating the base material, the coating film is cured. Curing can be carried out at various temperatures including room temperature, but at low temperatures, especially 50 to 150°C,
A cured coating film with a high degree of crosslinking is preferably obtained at 60 to 100°C. The curing time varies depending on the curing temperature, etc., but it is 60 to 1
It is appropriate to cure at 00°C for 10 to 30 minutes.

The coating composition of the present invention comprises the above-mentioned components (A), (B), and (C).
Based on the reactivity of (D) and (D), a one-liquid type may be used if possible, but a two-liquid type coating is usually adopted. Since component (A) and component (C) have high reactivity in a two-liquid type combination, any combination may be used except that the two are not combined into one package.

(Effect of the invention) Generally, metal chelate compounds are thought to react with hydroxyl groups and carboxyl groups to form a bond between the metal and the polymer through oxygen, but the bond is sufficient for oligomers such as paint polymers. It's not enough to do that. This is thought to be because oligomers have high steric hindrance and low reactivity. The mechanism of action is not yet clear, but by adding an active acid anhydride group between the metal and the resin, steric hindrance is reduced, making it easier for the reaction to proceed. This is thought to improve curability.

On the other hand, although improvement in curability may impair storage stability, the effect of the acid anhydride at room temperature can be prevented by adding a compound having chelate-forming ability.

Once heated, the compound with chelate-forming ability is evaporated off and the reaction mechanism described above occurs due to the acid anhydride. When a tertiary amine compound is added, curing is further accelerated and curing can be performed at lower temperatures. When a high molecular weight acid anhydride is used, the compatibility increases and the appearance of the coating film is improved. Therefore, the storage stability of the coating composition is greatly improved.

Therefore, a coating film with a high degree of crosslinking can be obtained by low temperature curing, and the solvent resistance, acid resistance, alkali resistance and impact resistance are improved, and the finished appearance etc. are also improved.

(Example) The present invention will be explained in more detail with reference to Examples.

In the examples, parts and percentages are by weight unless otherwise indicated.

Example 1 40 parts of xylene and 50 parts of butyl acetate were added to a reaction vessel equipped with a thermometer, a stirrer, a cooler, a nitrogen inlet tube, and a dropping funnel, and the temperature was raised to 120°C, and 30 parts of styrene monomer and 2-hydroxyethyl methacrylate were added. 23 parts, 1 methyl methacrylate
0 parts, butyl methacrylate 17 parts, butyl acrylate 2 parts
A monomer/initiator mixed solution of 0 parts and 3 parts of tert-butylperoxy-2-ethylhexanoate was added dropwise over 3 hours. After the completion of the dropwise addition, the temperature was maintained at 120°C for 30 minutes, and then Tajariebdelperoxy 2edylhexanoate 0
．． An initiator solution of 5 parts and 10 ffl of xylene was added dropwise over 1 hour. The temperature was further maintained at 120°C for 2 hours to complete the reaction and a colorless and transparent resin solution with a solid content of about 50% was obtained. The viscosity is op at 25°C.

To 100 parts of the obtained varnish were added 20 parts of a 50% toluene solution of aluminum tris (ethyl acetoacetate), 20 parts of a 33% solution of trimellitic anhydride triglyceride in dioxane, and 20 parts of acedelacetone to prepare a clear paint. As for the storage stability of this clear paint, a three-month stability test was conducted at room temperature, but no increase in viscosity or other changes were observed. 45 parts of Rudil-type titane oxide was blended with 66.6 parts of the solid content of the obtained paint, and a white enamel was obtained by roll dispersion. This enamel was spray painted onto a phosphate treated steel plate and baked at lOOoC for 30 minutes. The performance of the coating film is shown in Table 2.

Total amount of toluene 1017 parts
Hitaloid 44-127 was added to 100 parts of Alpaste 1100NA, stirred at room temperature for 5 to 10 minutes, and then mixed with toluene.

Add the specified amount of Disbaron 4200-10 and stir for about 1 hour.
After 0 minutes, metallic paint A was obtained. To the above metallic paint A were added 15 parts of a 50% solution of aluminum tris(ethyl acetoacetate) in luene, 20 parts of a 33% solution of trimellitic anhydride triglyceride in dioxane, 20 parts of acedelacetone, and 10 parts of ethyl acetoacetate. Regarding the storage stability of this paint at room temperature, no increase in viscosity was observed even after 3 months.

The clear paint obtained in Example 1 and the above metallic paint were mixed with 10 parts of toluene, 20 parts of butyl acetate, and 50 parts of xylene.
The mixture was diluted to a spray viscosity with a mixed solvent of 100 parts of Tsurupetz #20 (aromatic hydrocarbon solvent manufactured by Esso) and sprayed onto a phosphate-treated steel plate using a wet-on-wet method. The performance of the obtained coating film is shown in Table 2.

An acrylic resin face was obtained by blending monomers not shown in Table 1 using the same method as shown in Example 1 of Jitsougumi 1, 2, and an aluminum chelate compound, an acid anhydride, and a compound having chelate-forming ability were added to make a clear paint. I got it.

A storage stability test was conducted on the clear paint having the above composition, but no changes in viscosity or other changes were observed even after storage at room temperature for 30 days. Further, in the same manner as in Example 2, metallic coating was performed and the coating film performance was tested. The coating film performance test results are shown in Table-2.

Comparative Example 1 A varnish was synthesized by the same method as in Example 1, and 45 parts of rutile titanium oxide was mixed with 50 parts of the solid varnish, and a white enamel was obtained by roll dispersion. This white enamel 95
20 parts of a 50% solution of aluminum tris(ethyl acetoacetate) in toluene and 20 parts of a 33% solution of trimellitic anhydride triglyceride in dioxane were added to obtain a white paint.

The performance of the coating film applied in the same manner as in Example 1 is shown in Table 2.

Comparative Example 2 100 parts of the varnish obtained in Example 1 was added with aluminum tris (
20 parts of a 50% toluene solution of ethyl acetoacetate), 3 parts of trimellitic anhydride triglyceride in dioxane
20 parts of a 3% solution was added to prepare a clear paint. Metallic paint A in Example 2 as the base metallic paint
5 of aluminum tris(ethyl acetoacetate)
It was prepared by adding 15 parts of a 0% toluene solution and 20 parts of a 33% solution of trimellitic anhydride triglyceride in dioxane. Coating was performed using the wet-on-wet method as in Example 2. The coating performance is shown in Table-2.

Production Example 1 Synthesis of Polymer (1) Containing Carboxylic Anhydride Groups 120 parts by weight of butyl acetate was charged into a 112 reaction vessel equipped with a thermometer, a stirrer, a cooling tube, and a nitrogen introduction tube, and the temperature was raised to 100°C.
21 parts by weight of butyl acrylate, 95 parts by weight of n-butyl methacrylate, 3 parts by weight of 2-ethylhexyl methacrylate
4 parts by weight, itaconic anhydride 45 parts by weight, dioxane 6
0 parts by weight and 1 part of t-butyl peroxyhexanoate
A monomer and initiator solution containing 0 parts by weight was added dropwise over a period of 3 hours, and stirring was continued for an additional 2 hours to obtain an acrylic resin with a nonvolatile content of 53% and a number average molecular weight ff of 15,500.

Production Examples 2 to 5 Synthesis Production Example 1 of Polymers ■ to ■ Containing Carboxylic Anhydride Groups
Polymers containing carboxylic anhydride groups were obtained in the same manner as above using the components shown in Table 3.

Polymer-I containing carboxylic acid anhydride obtained in Production Example 1
128 parts by weight, 1,5-pentanediolua parts by weight,
A clear paint was prepared by mixing 12 parts by weight of triethylamine, 35 parts by weight of 50% liter of aluminum (ethyl acetoacetate), 35 parts by weight of a luene solution, and 1.20 parts by weight of ethyl acetoacetate as a compound capable of forming Clear-1. Obtained. Similarly, paints were prepared using the formulations shown in Table 4.

The resulting paint was diluted with a 1/1 mixture of butyl acetate and kiln (7). It was applied to a phosphate-treated steel plate using a doctor blade and baked at 80°C for 30 minutes. The performance of the resulting paint film is shown in Table 1. 5.

Tanmotoshi IA- A coating material was obtained in the same manner as in Example 1, except that 25 parts by weight of acedelacetone, which is a compound that controls the ability to form Kir-1, was removed.

The performance of the coating film is shown in Table-5.

A coating material was obtained in the same manner as in Example 1 except that the compound having chelate-forming ability, acedelacetone, was changed to 6 moieties.

The performance of the coating film is shown in Table-5.

In Example 1, the stabilizer acetylacetone was added to 12
The paint was obtained in the same manner except that 0 heavy debt was used.

The performance of the coating film is shown in Table-5.

Claims (1)

[Claims] 1. (A) a compound having a hydroxyl group, (B) a metal chelate compound or a metal alcoholate compound, (C) a compound having a carboxylic anhydride group, and (D) a compound having chelate-forming ability. A low temperature curable coating composition containing. 2. The coating composition according to item 1, wherein the composition further contains a tertiary amine compound (E) as a curing accelerator. 3. The coating composition according to item 1 or 2, wherein the compound having a hydroxyl group is a compound having a plurality of hydroxyl groups selected from the group consisting of low molecular weight diols, polyester resins, acrylic resins, silicone resins, and polybutadiene resins. thing. 4. The first metal chelate compound or metal alcoholate compound is a compound selected from the group consisting of metal chelate compounds of Ti, Al, Zr, Co, Cr or Ni and metal alcoholate compounds of Ti, Al or Zr. Coating composition according to item 1 or 2. 5. The coating composition according to item 3, wherein the metal of the metal chelate compound or metal alcoholate is Al, Zr or Ti. 6. The coating composition according to item 1 or 2, wherein the compound having a carboxylic anhydride group is a low molecular weight carboxylic anhydride or a polymer having a carboxylic anhydride group. 7. The coating composition according to item 1 or 2, wherein the compound having chelate-forming ability is an etho-kenol tautomer compound. 8. Metal chelate compound or metal alcoholate compound 0.1 to 1 per hydroxyl group of the compound having a hydroxyl group
3.0 equivalent, compound having carboxylic anhydride group 0.1~
10. The coating composition according to item 1, which is blended in an amount of 10.0 equivalents. 9. The coating composition according to item 2, wherein the tertiary amine compound is blended in an amount of 0.1 to 1.5 equivalents per equivalent of the hydroxyl group of the compound having a hydroxyl group.