KR20050069731A - Resin and composition for automotive solventbourne 1k clearcoat for automotive aqueous basecoat containing the same - Google Patents

Abstract

The present invention relates to a resin for automotive transparent paints and to a one-component transparent topcoat composition for automobiles containing the same, and more particularly, to water-soluble coatings for automobile coating lines using resins containing hydroxyl groups and epoxy groups as acrylic monomers and reactive groups. The present invention relates to a resin for automotive transparent paint and a solvent-containing one-component transparent topcoat composition containing the same in consideration of acryl urethane composite color top coat. The top coat according to the present invention is a solvent type one-component transparent paint, and has excellent advantages in coating properties such as acid resistance and appearance, and is suitable for a clear paint for an aqueous base.

Description

Resin and composition for automotive solventbourne 1K clearcoat for automotive aqueous basecoat containing the same}

The present invention relates to a resin for automotive transparent paint and to a one-component transparent topcoat composition for automobiles containing the same, and more particularly, to a vehicle transparent paint resin having excellent acid resistance, scratch resistance and appearance, and a vehicle solvent containing the same. It relates to a one-component transparent top coat composition.

Automobile paints account for a large portion of the paint industry, and environmental regulations for the automotive industry are being strengthened. Therefore, eco-friendly automotive paints are being developed. One of these is water-soluble paints, but the use of water-soluble paints in automotive coating lines brings many limitations.

The water-soluble paint substitute for the solvent type has problems such as compatibility with the existing solvent-type paint, system suitability, etc., it is required to develop a water-soluble topcoat and a transparent topcoat suitable for physical properties and workability.

Automobile body is coated with water-soluble basecoat which gives color on the middle coat after electrodeposition coating and middle coat process, then transparent paint is applied.Base coat and transparent paint are coated with 2 coats 1 baking (2coat-1baking) Painted in a manner.

The transparent coating composition coated on the automobile body is generally composed of a hydroxyl group-containing acrylic resin, melamine resin, and block isocyanate resin, and a one-component type in which an additive and an acid catalyst are added, including a leveling agent, a slip agent, a UV absorber, and an antioxidant. Transparent paints are widely used.

In the case of the transparent paint prepared using the existing hydroxyl group-containing acrylic resin, the repaintability is poor when applied on the water-soluble color topcoat using the acrylic urethane copolymer resin, and the chemical resistance such as acid rain, which is emerging as an environmental factor, Due to its weakness, the property of acid resistance is required as an important property item with weatherability.

When painting the water-soluble top coat, the lowering of repainting adhesion is not a functional group of the topcoat, so the repainting adhesion with the transparent coating becomes a problem, and the cause is that the curing reaction rate of the conventional solvent-type color topcoat is different. Caused by. The acid resistance is understood to be due to the decomposition of the ether group generated when the melamine curing agent is used. However, by adjusting the basic skeleton of the main resin alone, the above properties can be satisfied to some extent, but there is a possibility of adversely affecting other physical properties. There is a difficulty in improving acid resistance and adhesion.

However, the conventional curing system in which the hydroxyl group of the acrylic polyol, which is developed as a solution to solve the above problems, is cured by reacting with a melamine resin, a block isocyanate, which is a curing agent, and the breakthrough improvement of acid resistance is limited. It's going all over the world, and in fact, some of it is commercially available.

Models of the new curing system include curing of epoxy groups and acid groups, curing of epoxy groups and anhydrides, curing of silane groups and hydroxyl groups, curing of fluorine-modified resins, and the neuralization system has a hydroxyl group of acryl polyol, which is a conventional curing method in acid resistance. Although it has excellent performance than the acid resistance of the coating film formed by the reaction with the melamine resin and the block isocyanate resin, there is a problem in appearance, price, productivity, adhesion, storage properties, etc. when applying the water-soluble color topcoat.

Therefore, in the present invention, in order to solve the problems described above, a variety of studies have been made, focusing on the development of a system capable of improving acid resistance while maintaining a curing system of conventional acrylic polyol resins, melamine resins, block isocyanates and paints. To solve the acid resistance problems of conventional solvent-type one-component transparent paints by synthesizing and selecting acrylic polyol resins, minimizing melamine content and maximizing the characteristic block isocyanate to form a characteristic coating film, The resin and the solvent type one-component transparent coating composition for automobile water-soluble color topcoat containing the same which improve the external appearance were obtained, and this invention was completed based on this.

Accordingly, an object of the present invention is to show an excellent effect in acid resistance and repainting adhesion when used in automotive transparent paints, excellent scratch resistance and water resistance, and to minimize the appearance of yellowing phenomenon due to impurities. It is to provide a manufacturing method.

Another object of the present invention is to provide an automotive solvent type one-component transparent topcoat composition having excellent acid resistance and coating film quality.

Method for producing a resin for automotive transparent paints according to the present invention for achieving the above object:

10 to 70% by weight of hydroxyl-containing acrylic monomer, 10 to 70% by weight of non-functional acrylic monomer, and 0 to 60% by weight of vinyl monomer were subjected to solution polymerization at a reaction temperature of 100 to 180 ° C. in the presence of a pyrolytic initiator and a solvent. Reacting to obtain an acryl polyol; And

50 to 80% by weight of the acrylic polyol and 10 to 30% by weight of ethylene glycol diglycidyl ether represented by the following formula (1) are reacted with 7 to 20% by weight of hexamethylene diisocyanate at a reaction temperature of 60 to 90 ℃ epoxy resin Obtaining an acryl polyol bonded thereto;

Includes:

Automotive solvent type one-component transparent topcoat composition according to the present invention for achieving the above another object is:

24 to 31% by weight of the main resin prepared according to the above method, and 10 to 13% by weight of an acrylic acid auxiliary resin copolymerized with a hydroxyl group-containing acrylic monomer, a nonfunctional acrylic monomer, a vinyl monomer, and a carboxyl group-containing acrylic monomer;

16 to 23 weight percent of blocked isocyanates;

6-10 weight% of acryl polyol resin of which flowability was controlled;

3 to 5% by weight of butoxy melamine resin;

0.05 to 0.1% by weight of surface conditioner;

1.0-2.0 weight% of light stabilizers;

0.005 to 0.05 wt% of a curing accelerator; And

The remainder is a solvent;

It includes.

Looking at the present invention in more detail as follows.

As described above, the present invention provides a resin for automotive transparent paint having excellent acid resistance and excellent re-coating property and appearance when coating on a water-soluble color topcoat, and an automotive solvent-type one-component transparent topcoat composition containing the same. .

The production method of the main resin according to the present invention is as follows.

First, an acrylic polyol is obtained by reacting a hydroxyl group-containing acrylic monomer, a nonfunctional acrylic monomer and a vinyl monomer through a solution polymerization method in the presence of a thermal decomposition initiator and a solvent.

The hydroxyl group-containing acrylic monomers used in the present invention are 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acryl Latex, 4-hydroxybutyl methacrylate, carduraacrylate, carduramethacrylate, caprolactone acrylate, caprolactone methacrylate, 2,3-dihydroxypropylacryl, 2,3-dihydroxypropylmetha Acrylate, polypropylene modified acrylate, polypropylene modified methacrylate, ethylene glycol diglycidyl ether and the like. The amount of the hydroxyl group-containing acrylic monomer is preferably 10 to 70% by weight to maintain scratch resistance as required by the consumer of automotive transparent paint.

Non-functional acrylic monomers used in the present invention are methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate Latex, cyclohexyl methacrylate, methyl acrylate, propyl acrylate, isobutyl acrylate, normal butyl acrylate, tertiary butyl acrylate, 2-ethylhexyl acrylate, normal octyl acrylate, isobornyl acrylate, And cyclohexyl acrylate. The amount of the non-functional acrylic monomer is preferably 10 to 70% by weight. If the amount of the non-functional acrylic monomer is less than 10% by weight, the increase in the functional acrylic monomer may adversely affect weather resistance and the like. Can be.

Vinyl monomers used in the present invention include styrene, vinyl toluene, vinyl acetate, α-methyl styrene, etc., the higher the amount used, the more the gloss tends to be improved, but when the content exceeds 60% by weight, the weather resistance is deteriorated have.

The thermal decomposition initiator used in the present invention is 2,2-azobis 2-methylbutylonitrile, 2,2-azobis isobutylonitrile, dibenzoyl peroxide, tertiary butyl peroxy benzoate, tertiary butyl perlock Side, tertiary butyl peroxy-2-ethylhexanoate, tertiary butyl peroxy acetate, cumyl hydro peroxide, dicumyl peroxide, tertiary butyl hydroperoxide and the like.

On the other hand, when the resin according to the present invention is mixed with a block isocyanate, melamine resin, acid catalyst, additives, solvents, etc. to prepare a transparent paint, yellowing may occur in a solution state and a cured coating film. The yellowing phenomenon is mainly affected by the block isocyanate and acid catalyst, but in order to minimize this, it is preferable to minimize the amount of the initiator used in the preparation of the resin according to the present invention as much as possible, and to recover sufficient reflux and, if necessary, impurities. In addition, if necessary, the antioxidant may be selectively added in an amount of 0.05 to 3% by weight, and the addition time may be added after the resin production or in the transparent paint manufacturing process.

The solvent used in the present invention is an aromatic hydrocarbon type such as toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, ethyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, ketones such as methyl acetate, ethyl Ester solvents such as acetate, normal propyl acetate, isopropyl acetate, isopropyl acetate, butyl acetate, methyl cellosolve acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, and normal propanol, isopropanol, and normal butanol And alcohol solvents such as isobutanol and tert-butanol.

On the other hand, the reaction is carried out through a solution polymerization method by a free radical mechanism at a temperature of 100 ~ 180 ℃ to produce an acrylic polyol having an acid value of zero.

Then, 50 to 80% by weight of the acryl polyol and 10 to 30% by weight of ethylene glycol diglycidyl ether were reacted at a reaction temperature of 60 to 90 ° C with 7 to 20% by weight of hexamethylene diisocyanate. Obtained combined acrylic polyols.

The biggest feature of the resin according to the present invention is combining acrylic polyol and epoxy resin to have a combination of hydroxyl monomers and an epoxy cured structure. Accordingly, the acid resistance can be improved by appropriately blending one or two hydroxyl monomers according to appropriate recoating property, scratchability and purpose of use, and introducing a new curing system.

Ethylene glycol diglycidyl ether used in the present invention is a material having four epoxy groups and two hydroxyl groups, which gives fast curing properties and high crosslinking density, the structure of which is represented by the following Chemical Formula 1:

Formula 1

The amount of the ethylene glycol diglycidyl ether represented by the formula (1) is preferably 10 to 30% by weight. If the amount is less than 10% by weight, the degree of crosslinking does not have much influence. There is a problem that is difficult to increase the stable synthesis.

On the other hand, the amount of the hexamethylene diisocyanate used is preferably 7 to 20% by weight, and when the amount is less than 7% by weight, the curing density decreases.

According to the present invention, when the ethylene glycol diglycidyl ether and the block isocyanate are used as a curing agent, the curing density becomes dense, the content of melamine is reduced, and an acid-epoxy curing system is introduced to increase acid resistance.

The solid content of the main resin obtained therefrom is 50 to 70%, has a molecular weight of 5000 to 20000, a hydroxyl group of 50 to 150, an acid value of 0 to 80, and a glass transition temperature (Tg) of -10 to 50 ° C. At this time, when the hydroxyl value is less than 50, the crosslinking density of the coating film is decreased, leading to a decrease in coating film properties. When the hydroxyl value is more than 150, the crosslinking density of the coating film is improved, and the coating film properties are improved, but the surface tension is increased. The appearance of the coating film deteriorates, and the compatibility with the solvent, the resin, and the base coating layer is lowered, which is not preferable. At this time, the main resin is used in the amount of 24 to 31% by weight in the top coat composition of the present invention.

On the other hand, according to the present invention, an acrylic acid resin obtained by copolymerizing a hydroxyl group-containing acrylic monomer, a non-functional acrylic monomer, a vinyl monomer, and a carboxyl group-containing acrylic monomer is used as an auxiliary resin. At this time, the auxiliary resin is used in the amount of 10 to 13% by weight in the top coat composition of the present invention.

Here, the hydroxyl group-containing acrylic monomer, non-functional acrylic monomer and vinyl monomer usable in the polymerization of the auxiliary resin are as described above in the main resin, and as the carboxyl monomer, acrylic acid, methacrylic acid, maleic acid, itagonic acid, Crotonic acid and the like can be used.

The automotive solvent type one-component transparent topcoat composition according to the present invention is a transparent paint for application after coating of a water-soluble color topcoat of automobiles, and has the most important reaction for improving the acid resistance and the resin having the characteristic properties prepared as described above. Block isocyanate, acrylic polyol resin with controlled flow, surface conditioner, light stabilizer, curing accelerator, and solvent for improving wettability and bubble stability with water-soluble top coat surface in which water is remaining.

Block isocyanate used in the present invention serves to form a coating film through a curing reaction with the functional group of the acrylic polyol, and is usually used for thermosetting one-component paints by introducing a blocking agent to the existing type. There are two types of block isocyanates used in the intermediate or top coats for automobiles.

That is, hexamethylene diisocyanate trimer and isophorone diisocyanate trimer are used. In the latter case, they exhibit hard coating properties and may affect hardness or scratch properties, and the above physical properties can be adjusted through mixing with the former composition. Can adjust the properties of the desired coating film.

The resin structural skeleton of the block isocyanate is classified into the above two kinds, which again vary the dissociation temperature range of the blocking agent according to the type of the blocking agent, which may change the storage or drying conditions of the paint.

Accordingly, in the present invention, in order to satisfy the drying conditions of about 150 ° C., which are the line drying conditions for automotive paints, diethyl malonate (DEM), 3,5-dimethylpyrazole (DMP), and methyl ethyl ketoxim ( Block isocyanate using a blocking agent which dissociates in the range of 120-130 degreeC of MEKO) etc. was selected.

More preferably, as the block isocyanate, block isocyanate of 3,5-dimethylpyrazole (DMP) blocked hexamethylene diisocyanate trimer may be used, and here, hardness control or other desired change in coating properties Isophorone diisocyanate is used in combination.

It is preferable that the use amount of the block isocyanate of the isophorone diisocyanate type is 30% by weight or less in the total block isocyanate. When the amount is more than 30% by weight, yellowing and adhesion of the coating film are affected.

Herein, the amount of the block isocyanate used in the total transparent coating composition is preferably 16 to 23% by weight, and when the amount is less than 16% by weight, the curing density decreases, acid resistance and the like decreases. There exists a problem that coating film hardness falls.

On the other hand, automotive transparent paints are required to have a beautiful appearance, so due to the characteristics of the car body, the vertical part is painted and dried. Therefore, a method of improving the flowability during vertical coating has been devised. There are many techniques for controlling sex.

For this purpose, a method of controlling flowability using a microgel or silica dispersion is generally used, but in the case of such a flow inhibitor, defects such as gloss decrease and adhesion decrease due to an increase in content are found and used. There are some limitations.

In the present invention, an acrylic polyol resin having a controlled flow is used to minimize the above-mentioned problems. The acrylic polyol resin with controlled flowability used in the present invention is a thixotropic resin in which a flow inhibitor is introduced into an existing acrylic polyol resin, and it is possible to reduce problems such as gloss reduction and adhesion along with performance of the existing acrylic polyol. . Here, in the case of the flow inhibitor is used more than 30% of the total acrylic polyol solids may act as a deterioration factor to the weather resistance or appearance somewhat. In addition, the amount of the acrylic polyol resin with controlled flowability in the total transparent paint is preferably 6 to 10% by weight. If the amount is less than 6% by weight, the flowability is lowered. It becomes an element which falls or the external appearance, such as glossiness, falls.

The butoxy melamine resin used in the present invention is preferably used as a curing agent in an amount of 3 to 5% by weight. If the amount is less than 3% by weight, the coating film hardness is lowered, and when it exceeds 5% by weight, acid resistance is lowered. Conventionally, 15-30% by weight of the melamine resin curing agent was used, but in the present invention, the acid resistance was improved by greatly reducing the amount thereof.

In addition, in the case of the surface regulator which affects an external appearance, the polyacrylate copolymer surface modifier and the polyether modified siloxane type surface modifier are mixed and used suitably. The use of the surface modifier may cause problems such as recoating property due to surface coating surface injury of the surface modifier or rather increase in the cratering sensitivity. In particular, it is essential to adjust the weight ratio of the polyacrylate copolymer and the polyether modified siloxane to 1: 1 to 2 because the polysiloxane modifiers act as such a factor. Therefore, the polyether modified siloxane may be mixed with an acrylate modifier to adjust the content thereof, thereby reducing the problem thereof and providing a smoothness of the coating film that may form a beautiful appearance. On the other hand, the amount of the surface modifier in which the polyacrylate copolymer and the polyether-modified siloxane are mixed is preferably used in the total transparent paint is 0.05 to 0.1% by weight, when out of the above range when coated with a water-soluble color topcoat Repaintability, appearance defects may occur.

Another important property of automotive paints is weather resistance. In fact, if the cycle of the vehicle is considered to be about 7 to 10 years, the durability of the coating should be ensured due to ultraviolet stability or other environmental factors. As mentioned above, if the change in acid resistance and scratch resistance due to the cured structure of the coating film is mentioned above, the influence of ultraviolet rays of sunlight depends on the UV stability of the coating film.

In order to maintain such optical stability, a light stabilizer is generally added to prevent destruction of the polymer by ultraviolet rays. The basis of this mechanism is to suppress the radical reaction of the formed coating, i.e., through the self-radical reaction of the light stabilizer itself and the reaction of the product of the radical reaction, instead of performing a series of polymer decay reaction mechanism to overcome the polymer collapse of the original dry coating It acts as a deterrent.

In the present invention, as a light stabilizer, a HALS-based light stabilizer and a hydroxybenzotriazole-based light stabilizer are mixed in a weight ratio of 1: 1 to 3, and when the weight ratio is out of the above range, the weather resistance is decreased or the coating film properties are reduced. May cause degradation. In addition, the amount of the light stabilizer in the total transparent paint amount may vary slightly depending on the weather resistance requirements of the composition, in the present invention, it is preferable to use in an amount of 1.0 to 2.0% by weight, the amount is 1.0 weight If it is less than%, weather resistance may occur, and if it exceeds 2.0% by weight, it is not preferable economically.

Next is the selection of the curing catalyst. In general, one-component solvent-type transparent paints applied to solvent-based color topcoats are mostly acid catalysts. However, an object of the present invention is to apply to a water-soluble color topcoat. Thus, the use of the existing acid catalyst causes a reaction between the acid and the amine used in the water-soluble color topcoat, which hinders the clear curing reaction, thereby lowering the hardness of the final dry coating film. Therefore, in the present invention, in order to solve such a problem, it was possible to compensate for such a problem of hardness degradation by using a tin catalyst. Preferably, the curing catalyst used in the present invention is a dibutyl tin laurate catalyst, the amount of use is preferably 0.005 to 0.05% by weight, if the amount is less than 0.005% by weight, the coating film hardness is lowered due to a decrease in the curing rate When it exceeds 0.05% by weight, the physical properties such as mechanical properties and repaint adhesion may be lowered due to an increase in hardness of the cured coating film.

On the other hand, the solvent composition of the solvent-type one-component transparent paints for automobiles is generally used by using a mixture of aromatic, ester-based and low-boiling acetate-based solvents, and by controlling the content of the high-boiling solvent in accordance with other line conditions, bubble generation problems and flowability It will control the optimum solvent content to satisfy the problem at the same time. The solvent composition of the present composition applied to the water-soluble color topcoat is not significantly different from that applied to the existing solvent type topcoat, but more preferably, it is generated by bubbles during drying by water remaining in the topcoat layer. In order to improve the pinhole problem, the use of a high boiling point aromatic, ketone-based and ester-based mixed solvent composition shows a stable result in pinhole generation. Most preferably, the content of the high boiling point solvent is higher than that of the one-component solvent type transparent paint used in the conventional solvent type color topcoat, and the content of the high boiling point aromatic solvent and the ester solvent is 10 It is preferably composed of 40 to 50% of the total solvent content in a ratio of 1 to 8: 1, 4 to 5% of other butanol solvents, 10 to 15% of acetate solvents, and 25 to 30% of low boiling aromatic solvents. The use of a high boiling point aromatic solvent and an ester solvent in the amount of the solvent used may cause problems such as pinhole generation and wettability with the top coat when less in the above range.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples.

Example 1

In preparing an acrylic polyol, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, as a monomer, 150 parts by weight of styrene, 100 parts by weight of methyl methacrylate, 300 parts by weight of butyl methacrylate, 120 parts by weight of ethyl acrylate, 95 parts by weight of butyl acrylate, and 185 parts by weight of 2-hydroxyethyl methacrylate. And 38 parts by weight of tert-butyl peroxy 2-ethylhexanoate as an initiator were added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1. 750 parts by weight of the prepared acrylic polyol and 250 parts by weight of ethylene glycol diglycidyl ether represented by Formula 1 were stirred at 70 ° C. for 1 hour, and then added dropwise using 180 parts by weight of hexamethylene diisocyanate for 30 minutes to maintain 8 hours. To obtain a main resin.

When preparing an auxiliary resin, acrylic acid, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, 400 parts by weight of styrene as a monomer, 300 parts by weight of butyl methacrylate, 100 parts by weight of butyl acrylate, 163 parts by weight of 2-hydroxyethyl methacrylate, 125 parts by weight of methacrylic acid and tertiary butylper as an initiator A mixture consisting of 110 parts by weight of hydroxy 2-ethylhexanoate was added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

Example 2

In preparing an acrylic polyol, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, as a monomer, 150 parts by weight of styrene, 50 parts by weight of methyl methacrylate, 300 parts by weight of butyl methacrylate, 184 parts by weight of ethyl acrylate, 100 parts by weight of butyl acrylate, and 185 parts by weight of 2-hydroxyethyl methacrylate. And 38 parts by weight of tert-butyl peroxy 2-ethylhexanoate as an initiator were added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1. 750 parts by weight of the prepared acrylic polyol and 250 parts by weight of ethylene glycol diglycidyl ether represented by Formula 1 were stirred at 70 ° C. for 1 hour, and then added dropwise using 180 parts by weight of hexamethylene diisocyanate for 30 minutes to maintain 8 hours. To obtain a main resin.

When preparing an auxiliary resin, acrylic acid, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, 400 parts by weight of styrene as a monomer, 200 parts by weight of butyl methacrylate, 175 parts by weight of butyl acrylate, 185 parts by weight of 2-hydroxyethyl methacrylate, 125 parts by weight of methacrylic acid and tertiary butylper as an initiator A mixture consisting of 100 parts by weight of hydroxy 2-ethylhexanoate was added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

Example 3

In preparing an acrylic polyol, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, 150 parts by weight of styrene, 100 parts by weight of methyl methacrylate, 300 parts by weight of butyl methacrylate, 120 parts by weight of ethyl acrylate, 100 parts by weight of butyl acrylate, and 185 parts by weight of 2-hydroxyethyl methacrylate. And 38 parts by weight of tert-butyl peroxy 2-ethylhexanoate as an initiator were added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1. 750 parts by weight of the prepared acrylic polyol and 250 parts by weight of ethylene glycol diglycidyl ether represented by Formula 1 were stirred at 70 ° C. for 1 hour, and then added dropwise using 180 parts by weight of hexamethylene diisocyanate for 30 minutes to maintain 8 hours. To obtain a main resin.

When preparing an auxiliary resin, acrylic acid, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, 400 parts by weight of styrene as a monomer, 200 parts by weight of butyl methacrylate, 150 parts by weight of butyl acrylate, 210 parts by weight of 2-hydroxyethyl methacrylate, 125 parts by weight of methacrylic acid and tertiary butylper as an initiator A mixture consisting of 80 parts by weight of hydroxy 2-ethylhexanoate was added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

Example 4

In preparing an acrylic polyol, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, as a monomer, 150 parts by weight of styrene, 100 parts by weight of methyl methacrylate, 300 parts by weight of butyl methacrylate, 120 parts by weight of ethyl acrylate, 95 parts by weight of butyl acrylate, and 185 parts by weight of 2-hydroxyethyl methacrylate. And 33 parts by weight of tert-butyl peroxy 2-ethylhexanoate as an initiator were added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1. 750 parts by weight of the prepared acrylic polyol and 250 parts by weight of ethylene glycol diglycidyl ether represented by Formula 1 were stirred at 70 ° C. for 1 hour, and then added dropwise using 180 parts by weight of hexamethylene diisocyanate for 30 minutes to maintain 8 hours. To obtain a main resin.

When preparing an auxiliary resin, acrylic acid, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, 400 parts by weight of styrene as a monomer, 200 parts by weight of butyl methacrylate, 125 parts by weight of butyl acrylate, 230 parts by weight of 2-hydroxyethyl methacrylate, 125 parts by weight of methacrylic acid and tertiary butylper as an initiator A mixture consisting of 20 parts by weight of hydroxy 2-ethylhexanoate was added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

Example 5

In preparing an acrylic polyol, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, as a monomer, 150 parts by weight of styrene, 50 parts by weight of methyl methacrylate, 300 parts by weight of butyl methacrylate, 184 parts by weight of ethyl acrylate, 100 parts by weight of butyl acrylate, and 185 parts by weight of 2-hydroxyethyl methacrylate. And 33 parts by weight of tert-butyl peroxy 2-ethylhexanoate as an initiator were added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1. 750 parts by weight of the prepared acrylic polyol and 250 parts by weight of ethylene glycol diglycidyl ether represented by Formula 1 were stirred at 70 ° C. for 1 hour, and then added dropwise using 180 parts by weight of hexamethylene diisocyanate for 30 minutes to maintain 8 hours. To obtain a main resin.

When preparing an auxiliary resin, acrylic acid, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, 400 parts by weight of styrene as a monomer, 200 parts by weight of butyl methacrylate, 100 parts by weight of butyl acrylate, 255 parts by weight of 2-hydroxyethyl methacrylate, 125 parts by weight of methacrylic acid and tertiary butylper as an initiator A mixture consisting of 75 parts by weight of hydroxy 2-ethylhexanoate was added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

Example 6

In preparing an acrylic polyol, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, as a monomer, 150 parts by weight of styrene, 300 parts by weight of butyl methacrylate, 120 parts by weight of ethyl acrylate, 100 parts by weight of butyl acrylate, 100 parts by weight of trifluoroethyl methacrylate, 2-hydroxyethyl methacrylate A mixture consisting of 185 parts by weight and 33 parts by weight of tertiarybutylperoxy 2-ethylhexanoate as an initiator was added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1. 750 parts by weight of the prepared acrylic polyol and 250 parts by weight of ethylene glycol diglycidyl ether represented by Formula 1 were stirred at 70 ° C. for 1 hour, and then added dropwise using 180 parts by weight of hexamethylene diisocyanate for 30 minutes to maintain 8 hours. To obtain a main resin.

When preparing an auxiliary resin, acrylic acid, 438 parts by weight of styrene was added to a four-necked flask equipped with a thermometer and a cooler, and the temperature was raised to a reflux temperature of 120 ° C. Next, 400 parts by weight of styrene as a monomer, 200 parts by weight of butyl methacrylate, 78 parts by weight of butyl acrylate, 280 parts by weight of 2-hydroxyethyl methacrylate, 125 parts by weight of methacrylic acid and tertiary butylper as an initiator A mixture consisting of 100 parts by weight of hydroxy 2-ethylhexanoate was added dropwise over 3 hours. Next, the mixture was held at reflux temperature at 120 ° C. for 2 hours, and then the mixed solution obtained by dissolving 2 parts by weight of butanol of tert-butylperoxy 2-ethylhexanoate as an initiator was added dropwise for 10 minutes. Then, the mixture was kept for 2 hours and reacted to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

Comparative Example 1

150 parts by weight of styrene, 40 parts by weight of methyl methacrylate, 330 parts by weight of butyl methacrylate, 101 parts by weight of butyl acrylate, 348 parts by weight of 2-hydroxyethyl methacrylate as a monomer and initiator mixture dropwise for 3 hours A mixture consisting of 24 parts by weight of acrylic acid and 65 parts by weight of tert-butyl peroxy 2-ethylhexanoate as an initiator was added dropwise over 3 hours. Next, the mixture was held for another 2 hours and dissolved in 77 parts by weight of 2 parts by weight of butanol, tertiary-butylperoxy 2-ethylhexanoate, which was an initiator, followed by dropwise addition for 10 minutes. It was then maintained for another 2 hours to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

Comparative Example 2

150 parts by weight of styrene, 40 parts by weight of methyl methacrylate, 331 parts by weight of butyl methacrylate, 125 parts by weight of butyl acrylate, 280 parts by weight of 2-hydroxyethyl methacrylate as a monomer and initiator mixture dropped in 3 hours A mixture consisting of 24 parts by weight of acrylic acid and 65 parts by weight of tert-butyl peroxy 2-ethylhexanoate as an initiator was added dropwise over 3 hours. Next, the mixture was held for another 2 hours and dissolved in 77 parts by weight of 2 parts by weight of butanol, tertiary-butylperoxy 2-ethylhexanoate, which was an initiator, followed by dropwise addition for 10 minutes. It was then maintained for another 2 hours to obtain an acrylic polyol. The viscosity, non volatile matter, glass transition temperature, hydroxyl value, acid value, and weight average molecular weight of the obtained acrylic polyol were measured. The component ratios used and the results are shown in Table 1.

room One room 2 room 3 room 4 room 5 room 6 ratio ratio A B A B A B A B A B A B One 2 Xylene 43.8 43.8 43.8 43.8 43.8 43.8 43.8 43.8 43.8 43.8 43.8 43.8 43.8 43.8 SM 15 40 15 40 15 40 15 40 15 40 15 40 15 15 MMA 10 0 5 0 10 0 10 0 5 0 0 0 4 4 BMA 30 30 30 20 30 20 30 20 30 20 30 20 33 33.1 EA 12 0 18.4 0 12 0 12 0 18.4 0 12 0 0 0 BA 9.5 10 10 17.5 10 15 9.5 12.5 10 10 10 7.8 10.1 12.5 TFEMA 0 0 0 0 0 0 0 0 0 0 10 0 0 0 2-HEMA 18.5 16.3 18.5 18.5 18.5 21 18.5 23 18.5 25.5 18.5 28 34.8 28 MAA 0 12.5 0 12.5 0 12.5 0 12.5 0 12.5 0 12.5 2.4 2.4 TBPO 3.8 11 3.8 10 3.8 8 3.3 2 3.3 7.5 3.3 10 6.5 6.5 Butanol 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 TBPO 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Nonvolatile matter 65 65 65 65 65 65 65 65 65 65 65 65 70 70 Viscosity Z2 X Z2 Y Z2 Z Z3 X Z3 Y Z3 Z Z4 Z3 Acid 0 80 0 80 0 80 0 80 0 80 0 80 14 14 Ohv 80 70 80 80 80 90 80 100 80 110 80 120 150 120 Tg (℃) -8.3 28.7 13.9 23.8 1.5 23.6 -8.3 21.5 13.9 20.3 1.5 19 0 6 Molecular Weight 10000 2000 10000 3000 10000 6000 12000 20000 12000 6000 12000 3000 8000 8000

1) Viscosity measured by Gardner Viscometer at 25 ° C.

2) The acid value and OHv are values for the resin solids.

A: main resin, B: auxiliary resin

SM: Styrene Monomer

MMA: Methyl methacrylate

BMA: Butyl methacrylate

EA: ethyl methacrylate

BA: Butyl methacrylate

TFEMA: trifluoroethyl methacrylate

2-HEMA: 2-hydroxyethyl methacrylate

MAA: methacrylic acid

TBPO: tertiarybutylperoxy 2-ethylhexanoate

Examples 7-8 and Comparative Examples 3-7

To prepare a transparent paint as a composition (unit: parts by weight) as shown in Table 2 below, and the results of measuring the physical properties of the coating film is shown in Table 3 below.

After adding the said component A, A1, A2 and / or B, a part of component K is put and stirred. While stirring this at medium speed, the rest of the components D, E, E ', and K are sequentially added.

Additives of components F, G, H, I and J are prepared in 10% dilution solution in butyl acetate and then added sequentially. The remaining L solvent was added and diluted with Ford cup # 4 (25 ° C) to a coating viscosity of 25 seconds.

The test pieces were coated with a solvent-type intermediate weight (KCC FU2260 L / Grey) on an electrodeposited coating (applied by Hyundai Motor). The baking conditions were the pre-drying conditions of the water-soluble color top coat, which was dried at 80 ° C. for 2 minutes and then dried at 150 ° C. for 25 minutes after a setting time of about 10 minutes after coating the transparent paint.

Example 7 Example 8 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 A 28 28 - - 28 32 28 B 12 12 - - 12 16 12 A1 - - 60 - - - - A2 - - - 60 - - - C 8 8 - - 8 - 8 D 3 3 10 10 10 3 3 E 20 14 13 13 13 20 - E ' - 6 - - - - 20 F 0.025 0.025 0.025 0.025 0.025 0.025 0.025 G 0.05 0.05 0.05 0.05 0.05 0.05 0.05 H 0.01 0.01 0.01 0.01 0.01 0.01 0.01 I 0.5 0.5 0.5 0.5 0.5 0.5 0.5 J 1.0 1.0 1.0 1.0 1.0 1.0 1.0 K 10 10 10 10 10 10 10 L 18 18 18 18 18 18 18

A: acrylic polyol main resin prepared according to Example 1

B: Acrylic Acid Auxiliary Resin Prepared According to Example 1

A1: acrylic polyol resin prepared according to Comparative Example 1

A2: acrylic polyol resin prepared according to Comparative Example 2

C: thixotropic acrylic polyol: Akzo Nobel company flow controlled acrylic polyol

D: melamine resin: DIC butoxy melamine resin

E: Block isocyanate (Bayer) with 3,5-trimethylpyrazole blocked hexamethylene diisocyanate trimer

E ': Block isocyanate with butanone oxime blocked isophorone diisocyanate trimer (Dedussa)

F: Surface conditioner: Polyacrylate copolymer (BYK company)

G: Surface conditioner: Polyether modified siloxane type (BYK company)

H: Curing accelerator: Dibutyl tin laurate

I: Light stabilizer: HALS (Ciba Tinuvin 123)

J: Light stabilizer: Hydroxybenzotriazole UV absorber (Ciba Tinuvin 384)

K: low boiling point aromatic and acetate solvents

L: High boiling aromatic, ketone-based, ester-based mixed solvent

Example 7 Example 8 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Exterior 58 57 57 57 59 50 57 Acid resistance pH 2 pH 2 pH 3 pH 3 pH 2.5 pH 2 pH 2 Scratch resistance 65 64 60 62 58 66 60 Repaintability Good Good Good Good Good Good Good Water resistance Good Good Good Good Good Good discoloration Chipping resistance Grade 8 Grade 8 Grade 7 Grade 7 Grade 7 Grade 8 Grade 7 Hardness HB F HB HB HB HB F Yellowing Good Good Good Good Good Good discoloration

1) Appearance: It was measured by the US PERCCEPTRON's QMS-BP equipment, and the three items such as gloss, sunyoung, and orange peel were added at a 20:30:50 ratio and expressed as a rating at 100%. The numerical value of Table 2 is a result of vertical coating appearance of water-soluble silver top coat.

2) Acid resistance: After dropping several drops of phosphoric acid and sulfuric acid pH-1, 2 solution, and left at 70 ℃ for 30 minutes, the softening of the coating film and the degree of color change was visually determined.

3) Scratch resistance: The resistance to automatic car wash was measured through a scratch test using Amtek's Car Washer tester.

4) Repaintability: The top coat and transparent paint were repainted on the normal painted surface to measure the adhesion.

5) Water resistance: After 10 days of immersion at 40 ℃ was measured whether the appearance of the mistery, gloss loss, adhesion.

6) Cold resistance chipping resistance: After standing for 3 hours in a freezer at minus 40 ℃, the degree of damage to the coating film was determined by hitting 50g vertically at a pressure of 4bar with chimping stone # 7.

7) Hardness: Measured by Mitsubishi's pencil hardness.

8) Yellowing: Color change after over-drying at 150 ° C for 1 hour after normal coating.

All test standards above are based on the HD-ME-EP-019 standard.

As can be seen from the table, in the case of the coating film prepared using the coating composition according to the present invention, the acid resistance is superior to the conventional solvent-type one-component transparent paint shows excellent acid resistance in other physical properties and appearance gave.

As described above, according to the present invention, the coating is coated with a solvent-type one-component transparent paint that is suitable as a system according to the application of a water-soluble color topcoat for automobiles, and thus exhibits excellent acid resistance and excellent appearance performance compared to a solvent-type color topcoat. It is possible to provide a topcoat composition.

Claims (7)

10 to 70% by weight of hydroxyl-containing acrylic monomer, 10 to 70% by weight of non-functional acrylic monomer, and 0 to 60% by weight of vinyl monomer were subjected to solution polymerization at a reaction temperature of 100 to 180 ° C. in the presence of a pyrolytic initiator and a solvent. Reacting to obtain an acryl polyol; And 50 to 80% by weight of the acrylic polyol and 10 to 30% by weight of ethylene glycol diglycidyl ether represented by the following formula (1) are reacted with 7 to 20% by weight of hexamethylene diisocyanate at a reaction temperature of 60 to 90 ℃ epoxy resin Obtaining an acryl polyol bonded thereto; Method for producing a resin for automotive transparent topcoat, comprising: Formula 1 The resin produced is characterized in that the molecular weight of 5000 to 20000, the hydroxyl group of 50 to 150, the acid value of 0 to 80, the glass transition temperature (Tg) of -10 to 50 ℃ characterized in that Method for producing a resin for automotive transparent topcoat. The method of claim 1, wherein the hydroxyl group-containing acrylic monomer is 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxy Propyl acrylate, 4-hydroxybutyl methacrylate, carduraacrylate, carduramethacrylate, caprolactone acrylate, caprolactone methacrylate, 2,3-dihydroxypropylacryl, 2,3-dihydroxy A method for producing a resin for automotive transparent topcoat, characterized in that at least one selected from the group consisting of propyl methacrylate, polypropylene modified acrylate, polypropylene modified methacrylate, and ethylene glycol diglycidyl ether. The method of claim 1, wherein the non-functional acrylic monomer is methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl Methacrylate, cyclohexyl methacrylate, methyl acrylate, propyl acrylate, isobutyl acrylate, normal butyl acrylate, tertiary butyl acrylate, 2-ethylhexyl acrylate, normal octyl acrylate, isobonyl acryl A method of producing a resin for a transparent topcoat, characterized in that at least one selected from the group consisting of a rate, and cyclohexyl acrylate. The method of claim 1, wherein the vinyl monomer is one or more selected from the group consisting of styrene, vinyltoluene, vinyl acetate, and α-methylstyrene. 24 to 31% by weight of the main resin prepared according to the method of any one of claims 1 to 5; 10 to 13% by weight of an acrylic acid auxiliary resin copolymerized with a hydroxyl group-containing acrylic monomer, a non-functional acrylic monomer, a vinyl monomer, and a carboxyl group-containing acrylic monomer; 16 to 23 weight percent of blocked isocyanates; 6-10 weight% of acryl polyol resin of which flowability was controlled; 3 to 5% by weight of butoxy melamine resin; 0.05 to 0.1% by weight of surface conditioner; 1.0-2.0 weight% of light stabilizers; 0.005 to 0.05 wt% of a curing accelerator; And The remainder is a solvent; Solvent type one-component transparent topcoat composition for automobile water-soluble color base, comprising a. 7. The method according to claim 6, wherein the block isocyanate is composed of 70 to 100% by weight of block isocyanate having blocked hexamethylene diisocyanate trimer and 0 to 30% by weight of block isocyanate having blocked isophorone diisocyanate trimer. Solvent type one-component transparent topcoat composition for automobile water-soluble color base.