JPS6112760A - Coating resin composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition capable of giving coating film with long-terminal weatherability and high durability and corrosion resistance as well as with good appearance such as high gloss, by blending multivalent isocyanate compound and polyol component consisting of each specific fluorine-contg. copolymer and acrylic copolymer. CONSTITUTION:The objective composition can be obtained by blending (A) a polyol component consisting of (i) OH group-bearing fluorine-contg. copolymer [pref. a copolymer from 30-70wt% of fluorolefin, 5-60wt% of cyclohexylvinyl ether, 3-50wt% of alkylvinyl ether, 3-20wt% of hydroxyalkylvinyl ether and 0-40wt% of another comonomer] and (ii) an acrylic copolymer with a OH-value 5-150 containing, as comonomer, 5-80wt%, of (meth)acrylic acid 2-4C alkyl ester in a weight ratio (i)/(ii) pref. 95/5-10/90 and (B) a multivalent isocyanate compound or aminoplast one in an equivalent ratio NCO/OH pref. 0.15-1.5/1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for coatings that has long-term weather resistance, durability, and corrosion resistance, and has excellent coating film appearance such as high gloss.

In recent years, steel structures such as tanks and bridges, curtain walls,
In the field of metal coatings such as pre-coated metals, there is a growing demand for longer lifespans of coating films, and fluororesin coatings are attracting attention.

The mainstream of conventional fluorine resin paints is a dispersion type fluorine resin paint in which polyvinylidene fluoride resin powder is dispersed in a solvent or in a solution consisting of a solvent and a liquid resin. Although the paint has excellent weather resistance, durability, and corrosion resistance, polyvinylidene fluoride resin powder has a high melting point and requires high temperature baking to melt into a uniform phase in the liquid resin for dispersion. The film had fatal problems of poor adhesion, poor repaintability during repair, and poor gloss.

Therefore, a fluorine resin for paints which solves these problems has been developed and a patent application has been filed (Japanese Patent Application Laid-Open No. 57-34107).

The fluororesin is a hydroxyl group-containing fluorine-containing copolymer containing fluoroolefin, cyclohexyl vinyl ether, etc. as constituent components, and is soluble in a normal organic solvent at room temperature.
Since it also has hydroxyl groups, it is possible to form a paint film even when baked at room temperature or low temperature, and the resulting paint film has not only weather resistance and durability, but also corrosion resistance, chemical resistance, adhesion, and the ability to be repainted during repairs. It can be said to be a revolutionary resin with excellent properties such as properties.

However, paints using the above-mentioned hydroxyl group-containing fluorine-containing copolymers have selectivity in the dispersibility of pigments, and therefore, depending on the pigment, defects such as color separation and floating may occur, and the resulting paint The film had the disadvantage that it had a small elongation rate and was somewhat inferior in gloss and image clarity compared to acrylic resin-based paints, aminoalkyd resin-based paints, and the like.

Due to these drawbacks, the above paints still do not have sufficient commercial value in the field of paints where initial coating appearance and aesthetics are important, and therefore, although they have excellent weather resistance and durability, they cannot be said to have sufficient commercial value. There were also requests for early improvements.

The present inventors have arrived at the present invention as a result of intensive studies to eliminate the above-mentioned drawbacks in view of one or more of the current circumstances.

That is, the present invention uses a fluorine-containing copolymer having a hydroxyl group and a hydroxyl group value of 5 to 15 containing 5 to 80% by weight of an argyl ester having 2 to 4 carbon atoms of acrylic acid and/or methacrylic acid as a copolymerization component.
The present invention relates to a coating resin composition comprising a polyol component comprising an acrylic copolymer of 0 and a polyvalent isocyanate compound or an aminoplast compound.

The paint resin composition of the present invention has good pigment dispersibility, and the resulting paint film has excellent weather resistance, durability, corrosion resistance, chemical resistance, adhesion, repaintability during repair, etc. Because it uses a specific acrylic copolymer and has good compatibility with a fluorine-containing copolymer that has hydroxyl groups, it has the characteristic of dramatically improving the transparency of clear coatings and the gloss of enamel coatings. are doing.

The present invention will be explained in detail below.

The fluorine-containing copolymer having a hydroxyl group used in the present invention preferably includes the fluorine-containing copolymer described in JP-A-57-34107. That is, the fluorine-containing copolymer contains fluoroolefin, cyclohexyl vinyl ether, alkyl hinyl ether, and hydroxyalkyl vinyl ether as essential components, and has a content of 30% each.
~70% by weight, 5-60% by weight, ~50% by weight, and 3
It contains up to 20% by weight. A fluorine-containing copolymer having a number average molecular weight of about 20,000 to about 100,000 is preferred.

Note that if the fluoroolefin content is too low, the weather resistance will deteriorate, and if the fluoroolefin content is too high, it will be difficult to manufacture. Schiff 1) If the hexyl vinyl ether content is too low, the hardness of the coating film will decrease, and if the alkyl vinyl ether content is too low, the flexibility will decrease.

Furthermore, it is particularly important to contain hydroxyalkyl vinyl ether in a proportion within the above range from the viewpoint of improving curability without impairing various useful properties as a paint base. Namely: 1; If the droxyalkyl vinyl ether content is too high, not only will the solubility of the copolymer in organic solvents decrease, but the flexibility of the coating film will also decrease; Durability and adhesion will decrease.

In the fluorine-containing copolymer, the fluoroolefins are preferably barhaloolefins, particularly chlorotrifluoroethylene or tetrafluoroethylene.

Moreover, as the alkyl vinyl ether, those containing a linear or branched alkyl group having 2 to 8 carbon atoms, particularly those in which the alkyl group has 2 to 4 carbon atoms, are preferable.

Further, the fluorine-containing copolymer may contain comonomers other than the four essential components in an amount not exceeding 40% by weight. Typical examples of such comonomers include ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, methyl methacrylate, and butyl acetate.

The fluorine-containing copolymer can be produced by causing a copolymerization reaction by allowing a polymerization initiator to act on a monomer mixture in a predetermined proportion in the presence of a polymerization medium.

Further, the acrylic copolymer used in the present invention contains an alkyl ester of acrylic acid and/or methacrylic acid having 2 to 4 carbon atoms and a hydroxyl group.

It is a copolymer containing β-ethylenically unsaturated monomer as an essential component. Those having a weight average molecular weight of about 10,000 to about 120,000 are suitable.

The alkyl ester of acrylic acid and/or methacrylic acid having 2 to 4 carbon atoms is an essential component that is uniformly compatible with the fluorine-containing copolymer, and its content is 5 to 80% by weight.
Particularly preferably 10 to 70% by weight.

If the content is too low, the compatibility will decrease, resulting in a decrease in the transparency of the clear coating and the gloss of the enamel coating in which the pigment is dispersed, which is not preferable.

Conversely, if the content is too high, the hardness of the coating will decrease,
Furthermore, weather resistance tends to decrease, which is not preferable.

The amount of the α,β-ethylenic non-saturated monomer having a hydroxyl group is such that the resulting copolymer has a hydroxyl value of 5 to 150, particularly preferably 10 to 120. It should be noted that if the hydroxyl value is lower than the above range, the curability of the coating film will be poor, and the hardness, stain resistance, etc. will also be reduced, which is not preferable. On the other hand, if the hydroxyl value is higher than the above range, the flexibility of the coating will decrease,
This is not preferable because it impairs post-processability.

The acrylic acid and/or methacrylic acid has 2 to 4 carbon atoms.
Examples of alkyl esters include ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate,
Examples include tert-butyl acrylate and tert-butyl meccrylate.

In addition, α,β-ethylenically inert saturated monomers having hydroxyl W include hydroxylethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate,
Typical examples include hydroxypropyl methacrylate.

In addition to the above two types of monomers, acrylic copolymers include acid monomers such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic anhydride, methyl acrylate, methyl methacrylate, and acrylic acid 2. Acrylic acid and/or methacrylic acid esters such as ethylhegycyl, cyclohexyl methacrylate, and ethyl methacrylate, other styrene,
It is a product obtained by copolymerizing one or more types of α-methylstyrene, vinylpyridine, etc., and a comonomer of J2.

The acrylic copolymer described in 2. is produced by reacting a polymerization initiator with a monomer mixture in a predetermined proportion in the presence of a polymerization solvent such as xylene, toluene, ethyl acetate, butyl acetate, etc. by a conventional method to carry out a copolymerization reaction. It can be manufactured by

The polyol component used in the present invention is composed of the fluorine-containing copolymer and the acrylic copolymer, and the mixing ratio (by weight) of the two is (95:5 to 10:90):
Particularly preferred is (90:10 to 20:80).

Note that if the amount of the fluorine-containing copolymer is too much than the above range, color separation due to pigment selectivity tends to occur, and the gloss, flexibility, etc. of the resulting coating film decreases; All of these are unfavorable because the characteristics of the polymer, such as weather resistance, durability, corrosion resistance, and chemical resistance, deteriorate.

Next, in the present invention, a polyvalent isocyanate compound and/or an aminoplast compound are used as the curing agent component of the polyol component.

Examples of polyvalent isocyanate compounds include aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenyl diisocyanate, and hydrogenated xylylene diisocyanate; Typical examples include reaction products of excess amounts of these isocyanate compounds and low-molecular-weight polyols such as ethylene glycol, glycerin, trimethylolpropane, and pentaerythritol. By mixing these polyvalent isocyanate compounds in a predetermined ratio with a polyol component consisting of the fluorine-containing copolymer and acrylic copolymer, a two-component coating material that can be cured even at room temperature is obtained.

Blocked isocyanate compounds obtained by masking the polyvalent isocyanate compounds with masking agents such as phenols, alcohols, oximes, lactams, amines, and amides can also be used, and in this case, they are mixed with the polyol component in a predetermined ratio. This results in a one-component paint that can be cured by baking.

The mixing ratio of the polyol component consisting of the fluorine-containing copolymer and the acrylic copolymer and the polyvalent isocyanate compound curing agent component is the isocyanate of the isocyanate compound.
The equivalent ratio of hydroxyl groups to the polyol component (NCO/OH) is (0.15 to 1.5/l), particularly preferably (0
, 2 to 1.2/1''),
Within this range, it becomes possible to exhibit the original resin properties.

If the number of isocyanate groups is too large than the above range, the free isocyanate groups will react with moisture in the air, resulting in a decrease in weather resistance, while if it is too small, satisfactory curability will not be obtained and the crosslinking density will be low, resulting in poor durability. All of these are unfavorable because solubility, resistance to lTi staining, chemical resistance, weather resistance, etc. are reduced.

Furthermore, as mentioned above, an aminoplast compound can also be used as a curing agent. The aminoplast compound is a condensation product of an amino compound such as melamine, urea, henzoguanamine, or acetoguanamine and an aldehyde compound, or a compound obtained by further etherifying the condensation product with an alcohol such as butanol. When an aminoplast compound is used, it becomes a one-component paint that can be cured by baking by mixing it with the polyol component in a predetermined ratio.

Mixing ratio of polyol component consisting of fluorine-containing copolymer and acrylic copolymer and aminoplast compound curing agent component (
(accumulation standard) is (95:5 to 6o:40), particularly preferably (90:10 to 70:30), and within this range the original resin properties can be exhibited.

If the amount of aminoplast compound is too much than the above range, reactions between the aminoplast compounds tend to occur, resulting in decreased flexibility, chemical resistance, etc. of the coating film, and conversely, if it is too little, satisfactory curability may not be obtained and crosslinking may occur. Since the density is low, the dissolution resistance, stain resistance, etc. are deteriorated, and both are unfavorable.

The resin composition for paint of the present invention is composed of the above-mentioned polyol component and curing agent component, and can be used as a paint by blending various pigments, organic solvents, additives, etc. as necessary.

As the pigment, pigments commonly used for paints can be used as they are. Specifically, acid-colored organic pigments, extender pigments such as quartz powder, alumina oxide, and precipitated barium sulfate, and metal powders such as stainless steel powder, zinc powder, aluminum powder, bronze powder, and mica powder are representative examples. Can be mentioned.

Examples of organic solvents include hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; Typical examples include alcohol-based solvents.

Examples of additives include those commonly known as paint additives, such as surface conditioners, dispersants, ultraviolet absorbers, thickeners, and reaction regulating catalysts.

The paint obtained in this way can be applied to steel plates, stainless steel plates,
It can be applied to various metal materials such as aluminum plates, as well as mortar, concrete, inorganic materials such as glass, plastics, wood, etc.

Painting methods include air spray, airless spray,
Conventional methods such as electrostatic spraying, dry coating, dip coating, brush printing, and roll coating can be used as they are.

In addition, the curing conditions can range from room temperature drying to low temperature baking at 130 to 150℃ for 20 to 30 minutes, and high temperature short baking at 200 to 230℃ for 30 to 200 seconds (various conditions up to q) can be determined by selecting the curing agent. Can be adopted.

As explained above, the coating resin composition of the present invention has not only long-term weather resistance, durability, corrosion resistance, chemical resistance, and flexibility, but also
It has the characteristic that it is possible to obtain a coating film with excellent coating appearance such as gloss and sharpness.

Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" and "%" are based on weight.

Furthermore, the following fluorine-containing copolymers and acrylic copolymers were used in Examples and Comparative Examples.

<Fluorine-containing copolymer> (1) Fluorine-containing copolymer (8) Chlorotrifluoroethylene 55.2%, cyclohexyl vinyl ether 20.0%, ethyl beer x -7
-/l/15.0% and hydroxybutyl vinyl ether 9.8% was prepared in JP-A-57-34107.
According to the method described in the publication, a 60% fluorine-containing copolymer (hydroxyl value 28.3, Tg, 15°C) was prepared. One piece of the solution was prepared. (This is referred to as fluorine-containing copolymer (A)) (2) Fluorine-containing copolymer B Monomer consisting of 47% tetrafluoroethylene, 30% cyclohexyl vinyl ether, 8% ethyl vinyl ether, and 15% hydroxybutyl vinyl ether were polymerized in the same manner, resulting in a fluorine-containing copolymer with a hydroxyl value of 43.4.
A 60% quijirole solution was prepared at 7835°C. (This is referred to as fluorine-containing copolymer (B)) (n) Acrylic copolymer (i) to (xii) 32.3 parts of Kijirole and 32.3 parts of butyl acetate were placed in a reaction vessel equipped with a stirrer and a cooler. After charging and raising the temperature to 80° C., 100 parts of the monomer mixture shown in Table 1 and 1.5 parts of azobisisobutyronitrile were added dropwise over about 2 hours to stir and react.

Furthermore, add 0.5 part of azohisisobutyronitrile, 85
The reaction mixture was stirred and reacted at CW for 4 hours to prepare an acrylic copolymer having a non-volatile molecule i of 0% and a weight average molecular weight N of 1.8 to 45,000.

Examples 1 to 4 and Comparative Example 1 A metallic paint shown in Table 2 was applied to a mild steel plate with a cationic electrodeposition coating and a polyester/melamine resin intermediate coating with a viscosity of 17 seconds (fumate) using a Kijiroll. After adjusting the temperature to 20°C (Cup #4), the coating was applied by air spray to a dry film thickness of 20μ.

Then, after leaving it for 3 minutes, the top clear shown in Table 2 was diluted with a mixed solvent of Dorol/Xylolu 50150 to a viscosity of 2.
After adjusting the time to 2 seconds, it was coated with air spray to give a dry film thickness of 25 μm. Then after 13 minutes of flash-off, 1
Bake at 50°C for 825 minutes.

The appearance and gloss of the resulting coating film were as shown in the lower row of Table 2.

As is clear from Table 2, the examples using the resin compositions of the present invention had good coating film appearance and high gloss.

On the other hand, acrylic acid and/or methacrylic acid has 2 or more carbon atoms.
In Comparative Example 1 in which the acrylic copolymer (vi) having a low alkyl ester content in Example 4 was used, the clear coating film had a milky appearance and low gloss.

Examples 5 to 7 and Comparative Examples 2 to 5 The black paint shown in Table 3 was applied to the same substrate as in Example 1 with a mixed solvent of cellosolve acetate/xylolu 20/80 to adjust the viscosity to 22 seconds. It was then applied by electrostatic spraying to a dry film thickness of 35 μm.

Then, after being left for 10 minutes, it was baked at 160°C for 20 minutes. The appearance, hardness, blackness, initial gloss, and gloss after the weather resistance test of the resulting coating film were as shown in the lower row of Table 3.

As is clear from Table 3, the examples using the resin compositions of the present invention had good coating film appearance, high gloss, and excellent weather resistance.

Comparative Example 2, in which no acrylic copolymer was used, had low gloss. Comparative Examples 3 and 5, which did not use a fluorine-containing copolymer, had poor weather resistance. In addition, in Comparative Example 4, in which an acrylic copolymer (1) that does not contain an alkyl ester of acrylic acid and/or methacrylic acid having 2 to 4 carbon atoms was used as an acrylic copolymer, the coating film was peeled off. The gloss is also very low and the accelerated weathering test is 150.
Chalking occurred at 0hrs. These causes are thought to be due to poor compatibility between the fluorine-containing copolymer and the acrylic copolymer (1), and this shows that Comparative Example 2 of the fluorine-containing copolymer alone and Comparative Example 2 of the acrylic copolymer (1)) (1)) This can be estimated from the fact that the gloss is lower than that of Comparative Example 5 alone.

Examples 8 to 9 and Comparative Examples 6 to 9 The white paint shown in Table 4 was applied to a 0.5 mm thick aluminum plate that had been subjected to chromic acid chemical conversion treatment using a knife coater to a dry film thickness of 25 mm. It was applied and baked at 230°C for 1 minute.

The resulting coating film has gloss, weather resistance, rubbing resistance, bending properties,
The impact resistance and strong solvent resistance were as shown in the lower row of Table 4.

As is clear from Table 4, the Examples using the resin composition of the present invention had high gloss and excellent coating performance.

On the other hand, Comparative Example 6, which did not use an acrylic copolymer, had poor bending properties and impact resistance. Furthermore, Comparative Example 7, which did not use a fluorine-containing copolymer, had poor weather resistance. In addition, Comparative Examples 8 and 9, which used acrylic copolymers (v) that do not contain acrylic acid and/or methacrylic acid alkyl esters having 2 to 4 carbon atoms, have very low gloss. Met.

Examples 10 to 14 and Comparative Examples 10 to 15 A composition obtained by kneading and dispersing the main ingredients shown in Table 5 was mixed with a polyvalent isocyanate compound in the proportions shown in Table 6 to prepare a blue paint.

The blue paint was painted with 0.5 stainless steel (SUStt'3) from a wholesaler.
04-2D) It was applied to a plate by spraying to a dry film thickness of 2071 mm and dried at room temperature for 7 days.

The gloss, solvent resistance, impact resistance, adhesion, and adhesion after the spring water test of the resulting coating film were as shown in the lower row of Table 6.

As is clear from Table 6, the Examples using the resin composition of the present invention had high gloss and excellent coating performance.

On the other hand, the equivalent ratio of the isocyanate groups of the polyvalent isocyanate-1 compound to the hydroxyl groups of the main ingredient (NGOloll) is 0.
Comparative Example 10 with a ratio of 1.1 and Comparative Example 1) with a corresponding ratio of 1.7 had poor impact resistance and adhesion. Furthermore, Comparative Example 1) in which no acrylic copolymer was used had low gloss and poor impact resistance and adhesion. Furthermore, both Comparative Examples 13 and 15, which used an acrylic copolymer with a smaller hydroxyl value than the hydroxyl value of the acrylic copolymer used in the present invention, and Comparative Example 14, which used an acrylic copolymer with a larger hydroxyl value, had poor boiling water resistance. .

Procedural amendment band Manabu Shiga, Commissioner of the Patent Office1, Indication of the case Patent Application No. 133884 of 19822, Title of the invention Resin composition for paint 3, Relationship with the person making the amendment Applicant name Title (332) Dai Nippon Toyo Co., Ltd. 4 Agent 5, Date of amendment order Voluntary action 6, Subject of amendment Detailed explanation of the invention in the specification column 7, Contents of amendment Procedure amendment band 59.12.2) Showa year, month, day 3. Relationship with the case to be amended Applicant name (332) Dainippon Nuri Co., Ltd. 4, Agent

Claims (5)

[Claims] (1) Acrylic acid and/or methacrylic acid having 2 to 4 carbon atoms as a copolymerization component with a fluorine-containing copolymer having a hydroxyl group
Contains 5 to 80% by weight of alkyl ester, hydroxyl value 5
A resin composition for a paint comprising a polyol component comprising an acrylic copolymer of 150 to 150, and a polyvalent isocyanate compound or an aminoplast compound. (2) The fluorine-containing copolymer is fluoroolefin 30
~70% by weight, cyclohexyl vinyl ether 5-60
Claim (1) characterized in that the copolymer is a copolymer consisting of 3 to 50% by weight of alkyl vinyl ether, 3 to 20% by weight of hydroxyalkyl vinyl ether, and 0 to 40% by weight of other copolymers. The resin composition for coatings described in . (3) The paint according to claim (1), characterized in that the mixing ratio (by weight) of the fluorine-containing copolymer and the acrylic copolymer is (95:5 to 10:90). Resin composition for use. (4) Equivalent ratio of isocyanate groups of the polyvalent isocyanate compound to hydroxyl groups of the polyol component (
Claim (1) characterized in that the ratio of NCO/OH) is (0.15 to 1.5/1).
) The resin composition for paint according to item 1. (5) The resin composition for paint according to claim (1), wherein the mixing ratio (by weight) of the polyol component and the aminoplast compound is (95:5 to 60:40). .