KR0143094B1 - High Sensitivity High Solid Acrylic Resin Coating Composition - Google Patents

Abstract

Disclosed is a high-fidelity high solid acrylic resin coating composition excellent in selectivity of appearance quality and high in nonvolatile content. The paint composition is 1-5 parts by weight of a vinyl monomer having an organic acid group, 15-50 parts by weight of a vinyl monomer having a hydroxyl group, 15-35 parts by weight of a vinyl monomer having an aromatic group and 15-65 parts by weight of a vinyl monomer having an aliphatic group. The acrylic resin produced by superposing | polymerizing a part is made into a main component. The acrylic resin is a solvent using a high boiling point aromatic hydrocarbon, the reaction temperature is 130-160 ℃, the reaction time is prepared under the reaction conditions of 4-6 hours, the acid value is 5-30mg KOH / g, hydroxyl group content It is 2-6%, glass transition temperature is -15-30 degreeC, 25 degreeC Gardner viscosity is Y-Z3, number average molecular weight is 3,000-8,000 and molecular weight distribution is 3 or less. The coating composition includes 50-80 parts by weight of the acrylic resin and 20-50 parts by weight of melamine resin. By using the coating composition, it is possible to form a coating film having excellent appearance quality or sensibility and excellent in water resistance, acid resistance and scratch resistance, and because the molecular weight of the acrylic resin is small, the content of the volatile organic solvent of the coating composition can be lowered, thereby saving resources and Contribute to environmental protection.

Description

High Sensitivity High Solid Acrylic Resin Coating Composition

The present invention relates to a high-sensitivity high-solid acrylic resin coating composition, and more particularly, it is excellent in the sensibility of appearance quality and excellent in water resistance, acid resistance and scratch resistance as well as lowering the content of organic solvent by increasing the nonvolatile content The present invention relates to a high-sensitivity high solid acrylic resin coating composition capable of conserving resources and conserving low pollution.

In Korea, there is no regulation on the allowance of volatile organic solvents in relation to the air pollution problem, but the developed countries including the US strictly regulate the emission concentration of organic solvents. The high solid resin coating composition can be manufactured with existing resin and paint manufacturing equipment and can be used as it is, so that the use of the existing coating line can reduce the amount of organic solvents. have.

In order to increase the nonvolatile content (solid content) in the conventional high-solid resin coating technology, the molecular weight of the acrylic resin used in the coating composition should be reduced. Mercapto compounds such as mercaptoacetic acid and mercaptopropionic acid have been mainly used as chain transfer agents for this purpose. Such chain transfer agents are expensive and have a strong irritating odor, and thus have an unpleasant odor in the resin as well as the cured coating film, and are pointed out as a cause of poor durability of the coating film such as yellowing.

Moreover, the low molecular weight acrylic resin used for the conventional high solid resin coating composition has a wide molecular weight distribution, and the distribution of the hydroxyl group which becomes a crosslinking point differs for every resin molecule. For this reason, uniform crosslink density was not formed, and some acrylic resin molecules which did not participate in crosslinking existed, and the coating-film performances, such as water resistance, scratch resistance, and chemical resistance, were poor.

In addition, when forming a cured coating film using a conventional low molecular weight acrylic resin, the selectivity of the coating film is inferior. Here, the sensibility of the coating film is a property related to the appearance quality of the coating film, and is a measure of how clear and clear the image reflected on the surface of the coating film is. If the surface of the coating is crumpled or there are minute irregularities on the surface, the sensitization is poor, and the sensibility is generally measured by a PGD (Portable Gloss Distinctiveness) measuring instrument.

The present inventors have studied the resin design and synthesis method to solve these drawbacks of high solid resins. As a result, the PDG values are 0.95 horizontal and 0.70 vertical, high stiffness, excellent appearance quality, water resistance, acid resistance and scratch resistance. Also developed a high-sensitivity high solid acrylic resin coating composition having excellent coating performance.

Accordingly, an object of the present invention is to reduce the content of volatile organic solvents, contributing to resource saving and environmental protection, as well as excellent appearance quality, especially sensibility, water resistance, acid resistance and scratch resistance. It is to provide a high-sensitivity high solid acrylic resin coating composition for having.

In order to achieve the above object, the present invention has a vinyl monomer having 1-5 parts by weight of an organic acid group, 15-50 parts by weight of a vinyl monomer having a hydroxyl group, 15-35 parts by weight of a vinyl monomer having an aromatic group and an aliphatic group Acrylic resin for resin composition 50- with a acid value of 5-30 mg KOH / g, a hydroxyl group content of 2-6%, and a glass transition temperature of -15-30 ° C. prepared by polymerizing 15-65 parts by weight of a vinyl monomer. Provided is a high fidelity high solid acrylic resin coating composition containing 80 parts by weight and 20-50 parts by weight of melamine resin.

Hereinafter, the present invention will be described in detail.

The resin according to the present invention is prepared by radical polymerization of various kinds of monomers having a vinyl double bond using a pyrolysis initiator. The radical polymerization depends on the solution polymerization method.

The composition ratio of the monomer having a vinyl double bond is 1-5% by weight of the monomer having an organic acid group, 15-50% by weight of the monomer having a hydroxyl group, 15-35% by weight of the monomer having an aromatic group, and 15-65% by weight of the monomer having an aliphatic group. %to be.

Acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, maleic anhydride, etc. are mentioned as an example of the monomer which has an organic acid group used by this invention, One or two or more of these can be selected and used.

As an example of the monomer which has a hydroxyl group used by this invention, acrylic acid (2-hydroxyethyl), methacrylic acid (2-hydroxyethyl), acrylic acid (4-hydroxybutyl), methacrylic acid (hydroxypropyl), etc. Can be mentioned.

In addition, the ring-opening portion of these compounds and ε-caprolactone can be used as the monomer in which the reaction compounds have a hydroxyl group of the present invention. Examples of the ring opening reaction compound include Fraxel FM-1 (Japan, manufactured by Daicel Chemical Industries, Ltd.), Fraxel FM-2 (product of Daicel Chemical Industries, Ltd.), and Fraxel FC-1 (Japan). , The product of Daicel Chemical Industry Co., Ltd.), etc. are mentioned. Fraxel FMM-1 is a ring-opening compound of methacrylic acid (2-hydroxyethyl) and ε-caprolactone, and the Fraxel FMM-2 is a methacrylic acid (2-hydroxyethyl) and a 2-molecule ε The ring-opening portion of -caprolactone is the reaction compound, and the ring-opening portion of acrylic acid (2-hydroxyethyl) and ε-caprolactone is the reaction compound.

Among these hydroxyl group-containing monomers, acrylic acid (4-hydroxybutyl) or the above-mentioned ring-opening-added reaction compounds are used as essential components in the production of the acrylic resin according to the present invention. The resin according to the present invention should contain at least two hydroxyl group-containing monomers including the essential components. As such, at least two hydroxyl group monomers having different reactivity with the crosslinking agent are used to control the curing reaction. As a result, excellent appearance quality or high sensibility can be obtained, and the crosslinking density can be improved to achieve high functionality such as scratch resistance.

Examples of the monomer having an aromatic group used in the present invention are styrene and vinyltoluene.

Examples of the monomer having an aliphatic group used in the present invention include ethyl acrylate, acrylic acid (n-butyl), cyclohexyl acrylate, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, Isobutyl methacrylate, normal-hexyl methacrylate, methacrylic acid (2-ethylhexyl), isobornyl methacrylate, lauryl methacrylate, vinyl acetate, acrylonitrile and the like. The resin according to the present invention contains, as an essential component, a long-chain aliphatic monomer having 8 or more carbon atoms in a chain bonded to a vinyl group. By using such a monomer, the outstanding external appearance quality and favorable functionality, such as high clarity, were achieved.

In order to improve the problem of the prior art that the molecular weight distribution of the acrylic resin is wide, a method of preparing a low molecular weight resin showing a distribution close to monodispersity having a narrow molecular weight distribution has recently been known as group transfer polymerization or living. ) Polymerization and the like are known. However, since these methods have to use special monomers and initiators, there is a problem such as an increase in the price of the product has not yet been put to practical use.

However, the inventors of the present invention have led to the invention of producing a low molecular weight acrylic resin having a narrow molecular weight distribution while using a conventional solution polymerization method without employing a group polymerization method or a living polymerization method to overcome such problems. Hereinafter, the method of the present invention will be described in more detail.

As general radical polymerization initiators, benzoyl peroxide, azoisobutyronitrile, 2-ethylhexanoic acid (tertiary-butylperoxy) and the like were used, and as a solvent, Cocozol-100 (manufactured by Yugong Co., Ltd.), Cocosol-150 A high boiling point solvent such as (product of Yugong Co., Ltd.) was used. Cocosol-100 and Cocosol-150 contain 99.2% or more and 99.8% or more of aromatic hydrocarbon solvents as mixed solvents, respectively.

Thus, by using a high boiling point solvent, the acrylic resin was able to superpose | polymerize at 130-160 degreeC higher than 100-130 degreeC which is a normal acrylic resin polymerization temperature. The monomer and the initiator mixture of the present invention were introduced into a flask containing a solvent at a uniform rate over a period of 4-6 hours longer than that of the conventional method, thereby suppressing a decrease in reaction temperature due to reflux of the low boiling point monomer.

Thus, the acrylic resin synthesized by the method of adding the monomer at a high temperature for a long time is uniform in the monomer composition ratio and functional group distribution of each resin molecule, has a molecular weight distribution close to monodispersion, and the molecular weight is small. In the cured coating film formed by using the resin of the present invention as a crosslinking agent, the PGD value exhibits excellent appearance quality or high stiffness of at least 0.95 horizontal and at least 0.70 vertical, and shows good performance in terms of water resistance, acid resistance and scratch resistance.

The acrylic resin prepared according to the present invention has an acid value of 5-30 mg KOH / g, a hydroxyl content of 2-6%, a glass transition temperature of -15-30 ° C, a 25 ° C Gardner viscosity of Y-Z3, a number average molecular weight of 3000-8000 And a thermosetting acrylic polyol resin having a molecular weight distribution of 3 or less.

If an acid value is less than 5 mgKOH / g as a characteristic value of the said acrylic polyol resin, sufficient crosslinking reaction may not be performed with crosslinking agent resin, and a high functional hardened coating film, such as scratch resistance, cannot be obtained. In addition, the solubility coefficient and thixotropic value of the resin are low, and high stiffness cannot be expected, particularly at the vertical coating site. When the said acid value exceeds 30 mg KOH / g, since a polar group is in an excessive state in resin, a viscosity will become high, a high solid resin composition cannot be obtained and high sensibility cannot be expected. Therefore, the preferable acid value of the acrylic resin of this invention is 5-30 mg KOH / g.

If the hydroxyl group content of the acrylic resin of this invention is less than 2%, a crosslinking density will become low and the molecular weight of a crosslinking coating film will become small, and sufficient function as a coating film cannot be exhibited. When the hydroxyl group content is more than 6%, compatibility with the crosslinking agent, nonpolar solvent, and the like becomes poor, so that excellent appearance quality cannot be expected. Therefore, the preferable hydroxyl group content of the acrylic resin of this invention is 2-6%.

If the glass transition temperature is less than -15 ° C, sufficient hardness of the cured coating film cannot be expected, and uniform coating is not obtained due to excessive flow of resin molecules during curing in the external appearance of the coating film, especially in the vertical region, and the sensibility of the coating film is lowered. . When the glass transition temperature exceeds 30 ° C, the resin viscosity becomes high, and a low molecular weight high solid resin coating composition having sufficient performance cannot be obtained, and scratch resistance becomes very poor. Therefore, the preferred glass transition temperature is -15-30 ° C.

When the resin coating composition is prepared using the acrylic resin of the present invention, the content of nonvolatile matter (solid content) may be increased to 70% by weight or more. If the number average molecular weight is less than 3000, sufficient crosslinking density cannot be obtained, resulting in deterioration of the physical properties of the cured coating film, which is undesirable. If the number average molecular weight is more than 8000, a high solid resin composition of 70% by weight or more of nonvolatile content cannot be obtained. Therefore, the preferable number average molecular weight of the acrylic resin of this invention is 3000-8000.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples. However, the following examples do not limit the scope of the present invention.

Example 1

38 g of cocosol-100 and 5 g of n-butanol were added to a four-necked flask equipped with a thermometer, a condenser, a dropping funnel and a stirrer, and then the temperature was increased to 145-150 ° C. while stirring. Thereafter, the monomer and initiator mixtures of Table 1 were added dropwise at a uniform rate over 5 hours while keeping the temperature of the solvent constant. After completion of the dropping, the mixture was further stirred for 1 hour, and then 0.5 g of azoisobutyronitrile was added thereto, followed by further stirring for 2 hours to react the unreacted monomer.

In this manner, an acrylic resin solution having a characteristic value of 25 ° C Gardner viscosity Z1, a nonvolatile content of 70% by weight, a glass transition temperature of -3 ° C, a hydroxyl content of 3.5%, an acid value of 21 mg KOH / g, a number average molecular weight of 4700 and a molecular weight distribution of 1.9. Got.

(Unit: g) ingredient Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Styrene 25 20 30 30 30 Methacrylic acid Lauryl 25 17 22 - 15 Methacrylic acid 3 3 5 One One Acrylic acid (2-hydroxyethyl) 7 15 - - 15 Methacrylic acid (2-hydroxyethyl) 5 10 - 16 - Methacrylic acid (2-ethylhexyl) 10 - - 40 14 Methacrylic acid (n-butyl) 10 - 20 13 25 Acrylic acid (4-hydroxybutyl) 15 - 10 - - Hexanoic acid (t-butylperoxy 2-ethyl) 2 - 3 2 2 Acrylic acid (n-butyl) - 25 - - - Fraxel FM-1 - 10 - - - Azoisobutyronitrile - 2 - - - Acrylic acid - - 3 - - Acrylic acid (hydroxypropyl) - - 10 - - system 102 102 103 102 102

Example 2

The mixture of Table 1 was solution polymerized in the same manner as in Example 1.

In this manner, an acrylic resin solution having a characteristic value of 25 ° C Gardner viscosity Z2, a nonvolatile content of 70% by weight, a glass transition temperature of 8 ° C, a hydroxyl content of 4.2%, an acid value of 21 mg KOH / g, a number average molecular weight of 5700, and a molecular weight distribution of 2.1. Got.

Example 3

38 g of Cocozol-100 was added to the same sand dune flask as in Example 1, the temperature was raised to 155-160 ° C. while stirring, and the monomer and initiator mixtures of Table 1 were maintained at a uniform rate over 6 hours while maintaining the temperature constant. It dripped. After the addition was completed, the mixture was further stirred for 1 hour, and 0.5 g of 2-ethylhexanoic acid (t-butylperoxy) was added thereto, followed by further stirring for 2 hours to react the unreacted monomer. After cooling to 100 ° C. or less, 5 g of n-butanol was added thereto, followed by stirring well.

In this manner, an acrylic resin solution having a characteristic value of 25 ° C. Gardner viscosity Z, 70% by weight of nonvolatile matter, 7 ° C of glass transition temperature, 3% hydroxyl content, acid value of 24 mg KOH / g, number average molecular weight 4500, and molecular weight distribution degree 2.0 Got.

Comparative Example 1

After putting 45 g of xylene, 38 g of cocosol-100, and 15 g of n-butanol in the same sand dune flask as in Example 1, raising the temperature to 125-130 ° C. while stirring, the monomers of Table 1 above were kept at a constant temperature. And the initiator mixture were added dropwise at a uniform rate over 2 hours. After completion of the dropwise addition, the mixture was further reacted for 1 hour, and 0.5 g of azoisobutyronitrile was added thereto, followed by further stirring for 3 hours to react the unreacted monomer.

In this manner, an acrylic resin solution having a characteristic value of 25 ° C Gardner viscosity VW, 50% by weight of nonvolatile content, 32 ° C of glass transition temperature, 2.1% of hydroxyl content, acid value of 7mg KOH / g, number average molecular weight of 12000, and molecular weight distribution of 3.2 Got.

Comparative Example 2

40 g of xylene, 40 g of toluene, and 12 g of n-butanol were added to the same four-necked flask as in Example 1, the temperature was raised to 120-125 ° C. while stirring, and the monomer and initiator mixtures of Table 1 were maintained for 2 hours while maintaining the temperature constant. It was dripped at the uniform speed over. After completion of the dropwise addition, the mixture was further reacted for 1 hour, and 0.5 g of azoisobutyronitrile was added thereto, followed by further stirring for 3 hours to react the unreacted monomer.

In this manner, an acrylic resin solution having a characteristic value of 25 ° C Gardner viscosity XY, a nonvolatile content of 55% by weight, a glass transition temperature of 11 ° C, a hydroxyl content of 2.2%, an acid value of 7mg KOH / g, a number average molecular weight of 11000, and a molecular weight distribution of 3.5 Got.

Physical property evaluation of coating film

In order to examine the properties of the coating film formed from the composition comprising the acrylic resin of Examples 1-3 and Comparative Examples 1-2, the acrylic resin 60-70g, melamine resin (Norumin-2060, manufactured by Daehan Paint Ink Co., Ltd.) 30-40 g of melamine formaldehyde resin) were mixed. To this, a dilution solvent consisting of toluene, xylene, cocozol-100, cocozol-150, isobutanol, and the like was added to adjust the viscosity of the Pod Cup No. 4 at 25 ° C. to 20-30 seconds so as to be sprayed. If necessary, an additive for preventing pinholes or cruttering on the coating film could be used.

The acrylic resin and melamine resin mixed solution thus prepared was first coated with a metallic leak paint having a thickness of 10-20 μm on the specimen coated with the electrodeposition paint. After 2-5 minutes, the coating was spray-painted to have a thickness of 30-40 μm and left for 10-20 minutes. Then, the film was formed by heating and drying in an oven at 140 ° C. for 20 minutes to investigate the performance of the coating film.

The performance of the coating film was evaluated according to the general coating material evaluation method.

Sensitivity was measured with a PGD meter.

Acid resistance was determined by dropping the sulfuric acid solution of 0.1 normal concentration and leaving it at 40 degreeC for 1 hour, and visually determining the damage of the coating film appearance.

Scratch resistance was evaluated as a gloss retention rate of the degree of scratches generated after mixing a very small, constant particle size sand with water at a constant pressure.

Table 2 shows the results of evaluating the physical properties.

Properties Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Pencil hardness F F F HB HB Polished 60 ° 95 96 95 94 92 Sunyoungsung PGD level 0.95 0.95 0.95 0.80 0.85 Perpendicular 0.70 0.70 0.65 0.45 0.55 Water resistance O O O O O Acid resistance O O O O O Scratch resistance ◎ ◎ ◎ △ △ Naked appearance O O O O O

In scratch resistance,? Is very excellent, O is excellent, and? Is normal.

The acrylic resin of Example 1-3 has a non-volatile content of 70% by weight or more, 25 ℃ Gardner viscosity of Y-Z3, the coating film formed from the coating composition is a gloss and appearance quality or It is not only excellent in sensibility, but also excellent in water resistance, acid resistance and scratch resistance.

The cured coating film formed by using the high solid acrylic resin coating composition of the present invention is superior in appearance quality or contrast properties and excellent in water resistance, acid resistance and scratch resistance as compared with the conventional cured coating film. In addition, by lowering the acrylic resin, the content of the volatile organic solvent of the acrylic resin composition may be lowered, contributing to resource saving and environmental protection.

Claims (3)

Manufactured by polymerizing 1-5 parts by weight of a vinyl monomer having an organic acid group, 15-50 parts by weight of a vinyl monomer having a hydroxyl group, 15-35 parts by weight of a vinyl monomer having an aromatic group and 15-65 parts by weight of a vinyl monomer having an aliphatic group. 50-80 parts by weight of acrylic resin and 20-50 parts by weight of melamine resin for a resin composition having an acid value of 5-30 mg KOH / g, a hydroxyl group content of 2-6%, and a glass transition temperature of -15-30 ° C. A high sensitizing high solid acrylic resin containing composition. The high sensitization high solid acrylic resin coating composition according to claim 1, wherein the acrylic resin has a Gardner viscosity of 25 ° C of Y-Z3, a number average molecular weight of 3,000-8,000, and a molecular weight distribution of 3 or less. The method of claim 1, wherein the acrylic resin is 130-160 ℃ reaction temperature is 4-6 hours, the reaction time is produced under the reaction conditions of the high-selectivity high solid acrylic resin coating composition.