KR101531569B1 - Water-soluble paint composition and method for producing the same - Google Patents

Abstract

The aqueous coating composition comprises 10 to 20 wt% of a water-soluble polyurethane resin having a hydroxyl group, 1 to 10 wt% of a water-dispersible acrylic resin, 20 to 30 wt% of a water-dispersible polyurethane resin, 10 to 20 wt% 1 to 20 wt% of a curing agent, 0.01 to 1 wt% of a curing accelerator, 0.1 to 5 wt% of a wetting agent, 0.1 to 2 wt% of a light stabilizer, 0.1 to 3 wt% of a slip agent, 0.01 to 2 wt% By weight and 10 to 30% by weight of a solvent.
Thus, by excluding the step of coating and drying the primer on the material, the productivity can be improved and the process cost can be reduced by simplifying the process. In addition, it is possible to realize coating properties such as abrasion resistance, adhesiveness, heat resistance, and excellent scratch resistance and soft texture in water-based paints, and at the same time, increase working time in specifications required for water-based paints.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based coating composition,

The present invention relates to a water-base coating composition and a method for forming a coating film using the same, and relates to a water-base coating composition having improved texture and scratch resistance and a method for forming a coating film using the same.

Background Art [0002] In recent years, with the advancement of automobiles, physical properties and properties required for paints and leather materials used as automobile interior materials are gradually increasing.

Among them, parts such as door trim, crush pad, console, and center facia, which are in contact with the human body, are mostly used, and the use of water- Development of a water-based paint capable of minimizing the occurrence of scratches caused by external impacts such as human contact and irritation after formation of a coating film using a paint is under development.

Generally, waterborne paints for automobiles are composed of primer for attachment to a material, and base coat for appearance and durability. The water-based paint is composed of a mixture of a polyurethane resin having a hydroxyl group and a flexible water-dispersed polyurethane resin, and a hardener to exhibit excellent paint workability, texture and chemical resistance.

However, in the case of currently used water-based paints, a coating film is formed by 2-coat 2-baking, in which primers are coated, followed by drying at 80 ° C for about 10 minutes to coat the base to evaporate moisture inside the primer have. That is, in order to form a coating film on a plastic material, it is necessary to sequentially coat and dry the primer coating composition, the color base coating composition and the top coat coating composition. As a result, the cost is increased in the process and the use of the water-based paint is disadvantageous in terms of cost compared to the use of the oil-based paint. In addition, the conventional water-based paints have a short pot life, which means that they must be used within a short period of time after mixing the curing agent and the base.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of coating a primer on a plastic material, And can realize a plastic material having environment-friendly and high added value by realizing coating property such as abrasion resistance, adhesion property, heat resistance, and excellent scratch resistance and soft texture, which are advantages of oil-based paints, in water- To provide a water-based coating composition.

Another object of the present invention is to provide a method for forming a coating film using the above water-base coating composition.

The water-base coating composition according to an embodiment of the present invention for realizing the object of the present invention comprises 10 to 20% by weight of a water-soluble polyurethane resin having a hydroxyl group, 1 to 10% by weight of a water-dispersible acrylic resin, % Of a water-dispersible polycarbonate urethane resin, 1 to 20 wt% of a curing agent, 0.01 to 1 wt% of a curing accelerator, 0.1 to 5 wt% of a wetting agent, 0.1 to 2 wt% of a light stabilizer, 0.01 to 2% by weight of an antifoaming agent, 1 to 10% by weight of a pigment and 10 to 30% by weight of a solvent.

In one embodiment, the succinic polyurethane resin having a hydroxyl group is selected from the group consisting of a) isocyanates having two or more functional groups per molecule, b) hydrophilic polyols having two or more functional groups having an average number of functional groups of 500 to 5,000, c) A polyol compound comprising a carbonate polyol or polyester polyol, d) a solvent, and e) a neutralizing agent.

In one embodiment, the succinic polyurethane resin having a hydroxyl group comprises a) 5 to 30% by weight of an isocyanate having 2 or more average functional groups, b) 2 to 10% by weight of a hydrophilic polyol having 2 or more average functional groups %, c) 30 to 60 wt.% of a polyol compound comprising the polycarbonate polyol and the polyester polyol, d) 5 to 25 wt.% of the solvent and e) 1 to 5 wt.% of the neutralizing agent.

In one embodiment, the isocyanate having two or more of the average number of functional groups is selected from the group consisting of toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, Based polyfunctional isocyanate. The term " polyfunctional isocyanate "

In one embodiment, the hydrophilic polyol having two or more average functional groups is selected from the group consisting of polyoxyethylene glycol, polycaprolactone diol containing a carboxyl group in the side chain, polyether diol having a sulfonic acid group in the side chain, and polyoxy An ethylene group, and a polyol having an ethylene group.

In one embodiment, the polycarbonate polyol and the polyester polyol may have a weight average molecular weight of 500 to 5000.

In one embodiment, the solvent may include one or more selected from the group consisting of N-methyl pyrrolidone, acetone, methyl ethyl ketone, dimethyl formamide, glycol ether ester, and hydrogenated furan.

In one embodiment, the neutralizing agent may comprise at least one member selected from the group consisting of N-methyldiethanolamine and triethanolamine.

In one embodiment, the water-dispersible acrylic resin may comprise a) an acrylate monomer, b) a radical initiator, c) an amine-based neutralizing agent, and d) a water-dispersible organic solvent.

B) a hydrophilic polyol having two or more average number of functional groups having a weight average molecular weight of 500 to 5,000; c) a hydrophilic polyol having a weight average molecular weight of 500 To 5000, of an acrylic polyol and an ester polyol, d) a solvent, and e) a neutralizing agent.

According to another aspect of the present invention, there is provided a method of forming a coating film, comprising: coating and drying a base coating composition on a plastic material; 10 to 20% by weight of a water-soluble polyurethane resin having a hydroxyl group, 1 to 10% by weight of a water dispersible acrylic resin, 20 to 30% by weight of a water dispersible polyurethane resin, 10 to 20% by weight of a water dispersible polycarbonate urethane resin, Wherein the antifoaming agent is used in an amount of 0.1 to 2% by weight, the pigment is used in an amount of 1 to 10% by weight, the solvent is used in an amount of 0.1 to 5% by weight, the light stabilizer is used in an amount of 0.1 to 2% To 10% by weight and 30% by weight of the aqueous coating composition, and drying the applied coating composition.

In one embodiment, the succinic polyurethane resin having a hydroxyl group is selected from the group consisting of a) isocyanates having two or more functional groups per molecule, b) hydrophilic polyols having two or more functional groups having an average number of functional groups of 500 to 5,000, c) A polyol compound comprising a carbonate polyol or polyester polyol, d) a solvent, and e) a neutralizing agent.

In one embodiment, the succinic polyurethane resin having a hydroxyl group comprises a) 5 to 30% by weight of an isocyanate having 2 or more average functional groups, b) 2 to 10% by weight of a hydrophilic polyol having 2 or more average functional groups %, c) 30 to 60 wt.% of a polyol compound comprising the polycarbonate polyol and the polyester polyol, d) 5 to 25 wt.% of the solvent and e) 1 to 5 wt.% of the neutralizing agent.

In one embodiment, the isocyanate having two or more of the average number of functional groups is selected from the group consisting of toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, Based polyfunctional isocyanate. The term " polyfunctional isocyanate "

In one embodiment, the hydrophilic polyol having two or more average number of functional groups is selected from the group consisting of polyoxyethylene glycol, polycaprolactone diol containing a carboxyl group in the side chain, polyether diol having a sulfonic acid group in the side chain, and poly An oxyethylene group, and a polyol having an oxyethylene group.

In one embodiment, the polycarbonate polyol and the polyester polyol may have a weight average molecular weight of 500 to 5000.

In one embodiment, the coating composition may be applied to the plastic material to a thickness of 20 to 40 탆 and then dried.

The water-based coating composition according to the embodiment of the present invention excludes the step of coating and drying the primer on the material, so that the productivity can be improved and the processing cost can be reduced by simplifying the process. In addition, it is possible to realize coating properties such as abrasion resistance, adhesiveness, heat resistance, and excellent scratch resistance and soft texture in water-based paints, and at the same time, increase working time in specifications required for water-based paints.

Hereinafter, the present invention will be described in more detail. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are further described in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Also, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, the present invention will be described in detail.

The aqueous coating composition according to the present invention comprises 10 to 20% by weight of a water-soluble polyurethane resin having a hydroxyl group; 1 to 10% by weight of a water-dispersible acrylic resin; 20 to 30% by weight of a water dispersible polyurethane resin; 10 to 20% by weight of a water-dispersible polycarbonate urethane resin; 1 to 20% by weight of a hardener; 0.01 to 1% by weight of a curing accelerator; 0.1 to 5 wt% wetting agent; 0.1 to 2% by weight of a light stabilizer; 0.1 to 3% by weight of a slip agent; 0.01 to 2% by weight of antifoaming agent; 1 to 10% by weight of pigment and 10 to 30% by weight of solvent. The type and role of each component will be described in more detail.

≪ Hydrous polyurethane resin containing hydroxyl group >

A) a hydrophilic polyol having two or more functional groups per molecule; c) a polycarbonate polyol (b) having an average number of functional groups of 2 or more; b) an isocyanate having two or more functional groups per molecule; ) And / or a polyester polyol (polyol compound).

In a general water-dispersed polyurethane reaction, a prepolymer is prepared by dissolving isocyanate in both ends and forming urea groups at both ends by using a polyhydric amine or the like as a chain extender to prepare a prepolymer, Dispersed. However, it is difficult to control the reproducibility and the molecular weight of the water-dispersed polyurethane thus obtained. Particularly, the coating film is softened after curing due to a lack of functional groups that can cause a curing reaction when applied to paints, which adversely affects the physical properties of coating films such as weatherability and abrasion resistance, and is inadequate for use as an aqueous top coat for automobiles.

The general water-dispersed polyurethane has a high molecular weight and is difficult to obtain a coating workability and has a hard characteristic. Therefore, it is necessary to further improve the properties for use as an automotive interior paint because of lack of excellent elasticity and soft feeling.

The water-dispersed polyurethane plays a crucial role in securing the pot life of the aqueous coating composition and causes a curing reaction with the curing agent to improve the durability and flexibility of the aqueous coating composition.

According to one embodiment of the present invention, the water-base coating composition is prepared without using a chain extender, and when the polyurethane prepolymer is prepared, the equivalent ratio of OH / NCO is adjusted to 1.4 to 2 to 10 to 80 mgKOH / g Respectively. When the remaining hydroxyl groups are applied to the coating material, the curing reaction with water-dispersed polyisocyanate causes a great improvement in paint properties such as weather resistance and abrasion resistance. A water-swellable polyurethane resin containing a hydroxyl group capable of being diluted with water was prepared without water dispersion in order to facilitate NV control at the time of coating.

The composition ratio of the composition material constituting the water-soluble polyurethane resin including a hydroxyl group is, for example, 5 to 30% by weight of an isocyanate having 2 or more average functional groups, 2 or more of a hydrophilic polyol 2 having an average number of functional groups of 2 or more To 10% by weight of a polyester polyol, 30 to 60% by weight of a polyester polyol, 5 to 25% by weight of a solvent and 1 to 5% by weight of a neutralizing agent.

Each of the constituent materials for the production of the water-soluble polyurethane resin containing the hydroxyl group will be described in more detail as follows.

First, an isocyanate having two or more average functional groups is exemplified by toluene diisocyanate, 4,4-diphenyl methane diisocyanate, hexamethylene diisocyanate, At least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate and polyfunctional isocyanates derived therefrom can be used. Particularly, at least one of isophorone diisocyanate and dicyclohexylmethane diisocyanate is preferably used.

The isocyanate is preferably used in an amount of 5 to 30% by weight based on the total weight of the water-swellable polyurethane resin containing a hydroxyl group. If the amount is less than 5% by weight, mechanical properties and chemical resistance may be deteriorated. If the amount is more than 30% by weight, viscosity may be increased, which may result in difficulty in synthesis.

The hydrophilic polyol having two or more average functional groups has the function of imparting hydrophilicity to the urethane chain to enable water dispersion, and is a polyoxyethylene glycol, a polycaprolactone containing a carboxyl group in its side chain At least one of polycaprolactone diol, a polyether diol having a sulfonic acid group in its side chain and a polyoxyethylene polyoxyethylene group substituted with an alkoxy group in the side chain can be used. The hydrophilic polyol is preferably used in an amount of 2 to 10% by weight based on the total weight of the hydrous polyurethane resin containing the hydroxyl group. If the amount is less than 2% by weight, hydrophilicity may be insufficient and dispersion of water may be difficult. If the amount of use is more than 10% by weight, the water resistance may be lowered.

The hydrophilic polyol having two or more average functional groups has a weight average molecular weight ranging from 500 to 5,000. It is advantageous in terms of chemical resistance and productivity that the weight average molecular weight is in the range of 500 to 5,000.

As the polyol compound containing a polyester polyol, it is advantageous in terms of chemical resistance and productivity to use a polyol compound having a weight average molecular weight in the range of 500 to 5,000. More preferably, a polyol compound containing a polyester diol is used.

The solvent may be selected from common solvents and is preferably selected from the group consisting of N-pyrrolidone, acetone, methyl ethyl ketone, dimethylformamide, glycoletherester, Hydrogenated furan, and the like. It is preferable to use at least one selected from these. The solvent is preferably used in an amount of 5 to 25% by weight based on the total weight of the water-soluble polyurethane resin containing the hydroxyl group. If the solvent is used outside the above range, it may be difficult to manufacture or may take a long time to dry when used as a coating agent have.

As the neutralizing agent, N-methylethanolamine, triethanolamine and the like can be used, and it is preferable to use triethanolamine. The neutralizing agent is preferably used in an amount of 1 to 5% by weight based on the total weight of the water-swellable polyurethane resin. When the amount of the neutralizing agent is less than 1% by weight, the effect of using a neutralizing agent is insufficient. There may be a problem causing discoloration. Therefore, it is preferable to use within the above range.

The polyester polyol used for producing the polyurethane resin which is the main component of the aqueous coating composition can be prepared by condensation reaction of an alcohol compound and an acid. Specifically, an alcohol compound such as polyester or methylpropane diol having a molecular weight of about 500 to 5,000 and diethylene glycol and adipic acid as a matrix and an adipic acid adipic acid, isophthalic acid or the like condensed with an acid such as a polyester polyol having a molecular weight of about 500 to 5,000 can be preferably used.

Next, a water-swellable polyurethane resin containing a hydroxyl group using a polyester polyol was prepared as follows.

First, 94 g of N-methylpyrrolidone, 660 g of a polyesterpolyol having a molecular weight of 500 to 5,000, obtained by using diethylene glycol and adipic acid as the matrix, and 660 g of dimethylpolysiloxane having a molecular weight of 500 to 5,000 were placed in a reaction vessel equipped with a reflux condenser, a nitrogen gas inlet tube, a thermometer, And 3 g of propionic acid were mixed and sufficiently stirred in a nitrogen stream. 60 g of hexamethylene diisocyanate was added to a mixture of polyester polyol and dimethylpropionic acid, and the mixture was heated to about 60 to 100 DEG C and stirred for about 6 hours to prepare a polyester polyurethane prepolymer containing a hydrophilic group. After cooling to 60 to 70 ° C, 2 g of triethanolamine was neutralized to a degree of neutralization of about 90 to 100% for neutralization of the prepolymer to prepare a polyester-based hydrous polyurethane resin having a hydroxyl group.

In the preparation of the coating composition, the amount of the hydrogenated polyurethane resin having a hydroxyl group is set in a range of about 10 to 20% by weight based on the total amount of the composition. Since the resin plays a decisive role in securing the pot life of the aqueous coating composition, when the amount of the resin used is less than about 10% by weight, the pot life of the aqueous coating composition becomes short. When the amount is more than about 20% by weight, the gloss becomes very high, the light extinction agent must be added in excess, and the physical properties of the coating film such as scratch resistance on the surface of the coating film may be deteriorated.

<Water-dispersible acrylic resin>

The water-dispersible acrylic resin is prepared by using a) a monomer, b) an initiator, c) a neutralizing agent, and d) a solvent.

Each of the composition materials for the production of the water-dispersible acrylic resin will be described in more detail as follows.

The monomer may be selected from the group consisting of Methylecrylate Monomer MAM, Methylmethacrylate monomer MMA, Butylacrylate monomer BAM, 2-hydroxyethylmethacrylate monomer 2 -HEMA, vinylacetate monomer VAM, styrene monomer SM, and the like. Particularly preferably, a carboxylic monomer such as a methylecrylate monomer (MAM), a methylmethacrylate monomer (MMA), a butylacrylate monomer (BAM), a 2-hydroxy And 2-hydroxyethylmethacrylate monomer (2-HEMA) may be used.

The initiator may be a radical initiator, and at least one of benzoyl peroxide (BPO) or azobisisobutyronitrile (AIBN) may be used as the radical initiator.

The neutralizing agent may be an amine neutralizing agent. The amine neutralizing agent may be at least one selected from the group consisting of triethanol amine (TEA), dimethyl ethanol amine (DMEA), diethanol amine, ammonia (NH 3) You can use more than one.

The solvent may be a water-soluble organic solvent. Examples of the water-soluble organic solvent include ether organic solvents such as butyl cellosolve (EC) (ethylene glycol monobutyl ether) and ethyl cellosolve (EC) Alcohol-based organic solvents such as methanol, ethanol, isopropyl alcohol (IPA), n-butanol, and isobutanol may be used. have. Particularly preferably, at least one of ethylene glycol monobutyl ether (EC), ethyl cellosolve (EC), methanol, and isopropyl alcohol (IPA) Or more can be used.

Preferably, the water-dispersible acrylic resin has a pH in the range of 7.0 to 8.0, and the Konig value in the Konig Pendulum Hardness Test (DIN 53157) ranges from 130 to 140 seconds.

The amount of the water-dispersible acrylic resin used in the preparation of the coating composition is in the range of about 1 to 10% by weight based on the total amount of the coating composition. If the amount is less than about 1% by weight, the chemical resistance is deteriorated. If the amount is more than about 10% by weight, the coating film becomes hard and adversely affects the scratch of the coating film.

<Water-dispersible polyurethane resin>

The water-dispersible polyurethane resin is used for securing sunscreen properties. Since the water-dispersible polyurethane resin is excellent in adhesion to a plastic material, it is unnecessary to use a primer. In the step of forming a coating film, the step of coating and drying the primer may be omitted, -coat 1-baking).

The water-dispersed polyurethane resin can be synthesized by reacting a polyol and an isocyanate. The polyol used in the production of the water-dispersed polyurethane resin may be a polyol other than the polycarbonate polyol. Examples of the polyol used in the production of the water-dispersed polyurethane resin include polyacryl polyols and polyester polyols.

The water-dispersed polyurethane resin preferably has a pH of 6 to 10, a tensile strength of 5 to 35 mPa, and a fracture elongation of 600 to 800%.

The amount of the water-dispersed polyurethane resin used in the preparation of the coating composition is about 20 to 30% by weight based on the total amount of the coating composition. If the amount is less than about 20% by weight, physical properties such as adhesiveness and chemical resistance deteriorate. If the amount of the coating is more than about 30% by weight, wettability becomes poor, have.

<Water-dispersible polycarbonate urethane resin>

The water-dispersible polycarbonate urethane resin is prepared by using a) an isocyanate having two or more average functional groups, b) a polycarbonate polyol having a weight average molecular weight of 500 to 5000, c) a solvent and d) a neutralizing agent.

The water-dispersible polycarbonate urethane resin dissolves the water-dispersible polyurethane resin. The water-dispersible polycarbonate urethane resin is superior in scratch resistance to other polyurethane resins, but is susceptible to sun cream resistance.

Each of the constituent materials for the production of the water-dispersible polycarbonate urethane resin will now be described in more detail.

The amount of the water-dispersed polyurethane resin used in the preparation of the coating composition is in the range of about 10 to 20% by weight based on the total amount of the coating composition. If the amount is less than about 10% by weight, scratch resistance and coating workability are deteriorated. If the amount is more than about 20% by weight, resistance to chemical resistance such as sunscreen property deteriorates .

<Curing agent>

The curing agent added for the curing of the coating composition is preferably isophoron diisocyanate and hydrolytic hexamethylene diisocyanate excellent in non-yellowing and weathering resistance, and is preferably contained in the range of about 1 to 20% by weight based on the coating composition. If the content of the curing agent is less than about 1% by weight, the curing of the curing agent does not occur and it is difficult to secure physical properties of the coating film. If the content of curing agent is more than about 20% by weight, Because it can cause problems.

<Curing accelerator>

As the curing accelerator, trimethylenediamine, tin octoate, dibutyltin dilaurate, lead 2-ethylhexanoate and the like are preferable, and the curing accelerator is preferably contained in the range of 0.01 to 1% by weight with respect to the aqueous coating composition . If the content is less than 0.01% by weight, the drying time is prolonged and physical properties such as chemical resistance, moisture resistance and abrasion property are deteriorated. When the content is more than 1% by weight, hardening of the coating occurs too rapidly, Popping phenomenon occurs in the coating film or contraction of the coating film occurs.

<Wetting agent>

The wettability is basically determined by the difference between the surface tension of the paint and the surface tension of the conductor. The general rule is that the paint surface tension must be at least equal to the surface tension of the conductor. This is because the surface tension of the coating material is higher than the surface tension of the object to be coated if the coating material does not spread well on the coating surface. Water-borne water-based paints generally have very high surface tension and wettability is often a problem.

A polyether siloxane copolymer, a polydimethylsiloxane, a polyether-modified polydimethylsiloxane and the like are preferably used in order to strongly decrease the surface tension of the paint to improve the wettability, prevent the cratering phenomenon and give the slip property to the surface, In the range of 0.1 to 5% by weight based on the aqueous coating composition. If the content thereof is less than 0.1% by weight, problems of external appearance due to dust on the surface of the coating will occur. If the content exceeds 5% by weight, there is a problem of adhesion deterioration upon re-coating.

<Photon tablets>

The light stabilizer has the effect of preventing the aging and the color change of the coating film caused by exposure to long-term light, and it performs UV blocking, light energy absorption and conversion, free radical removal function and the like. UV absorbers and UV hindered amine light stabilizers, which are organic amine compounds with steric hindrance effects, should be properly mixed. As ultraviolet absorbing light stabilizers, various types such as benzophenone, oxanilide, benzotriazole, and triazine can be used. Examples of the organic amine light stabilizers include 4-benzoyloxy-2,2,6,6-tetramethylbipyridine, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl- Etc. may be used. It is preferable to mix the ultraviolet absorber and the ultraviolet light inhibitor amine photostabilizer at a weight ratio of about 2: 1.

It is preferable that the light stabilizer is contained in the range of 0.1 to 2% by weight based on the water-base coating composition. If the content thereof is less than about 0.1% by weight, the coating film may yellow easily and degrade in gloss over time, and if the content is more than about 2% by weight, the paint storage stability becomes unstable.

<Slip agent>

The silicone additive can improve the slipperiness of the coating film surface. Sometimes it can be thought of in conjunction with other properties of the coating as well as simple slip properties. When the slip property is good, scratch resistance and stain resistance are improved, and the product can be easily cleaned and the tack resistance is improved.

The slip agent is preferably contained in an amount of 0.1 to 3% by weight based on the aqueous coating composition. If the content is less than 0.1% by weight, the physical properties such as abrasion resistance and scratch resistance are deteriorated. If the content is more than 3% by weight, there is a problem of adhesion deterioration upon re-coating.

<Defoamer>

Bubbles occur during the stirring, dispersing and painting processes of various stages of production. This causes surface defects such as cratering or weakening of the coating film on the dry film, so it is necessary to use a defoaming agent to suppress bubble removal and bubble formation. Suitable chemical structures as defoamers are molecules with low surface tension, such as silicon, mineral oils, fatty acids and fluorocarbons. The use of a non-silicone antifoaming agent is preferred, and the antifoaming agent is preferably included in the range of 0.01 to 2% by weight based on the waterborne coating composition. If the content thereof is less than 0.01% by weight, the effect of defoaming is insufficient. If the content is more than 2% by weight, cratering may occur during the formation of the coating film.

<Pigment>

The pigments are generally used to impart color to paints, the pigments may be organic or inorganic pigments, and black and colored pigments may be used. The pigment may be added to produce a matte coating, which may degrade the gloss of the coating.

The organic and inorganic pigments may include organic pigments including carbon black, anthraquinone, phthalocyanine, and benzimidazolone, and organic pigments such as iron oxide yellow, iron oxide yellow, oxide red, manganese pyrophosphate, titanium dioxide (TiO 2) and zinc oxide (ZnO), and the like.

The pigment is preferably contained in an amount of 1 to 10% by weight based on the total weight of the aqueous coating composition. If the content thereof is less than about 1% by weight, it is difficult to exhibit a desired color in the paint, and the color of the paint may become uneven. On the other hand, if it exceeds about 10% by weight, there is a problem that moisture resistance is reduced.

<Solvent>

The solvent may be at least one selected from the group consisting of ethyl acetate, propyl acetate, butyl acetate, ethylene glycol methyl ether, diethylene glycol methyl ether, butylene glycol methyl ether, dibutylene glycol methyl ester, propylene glycol methyl ether and dipropylene glycol methyl ether It can be selected and mixed properly. The solvent is present in the range of 10 to 30% by weight based on the total amount of the composition for the aqueous coating composition. When the content is less than 10% by weight, there is a problem that the surface leveling is lowered. When the content is more than 30% by weight, there is a problem that smell can be caused.

<Light Extinguishing Agent>

Silica gel, precipitated silica, titanium dioxide and the like can be used as a quenching agent which serves to reduce or eliminate the gloss of the material. Particularly, in the present invention, it is preferable to use a micronized silica dispersion having an average particle size of about 1 to 30 μm. If the average particle diameter exceeds about 30 탆, the surface of the coating film may become coarse, resulting in poor appearance and poor scratch resistance. Therefore, it is preferable to use a dispersion having the above-mentioned particle size range.

The quencher containing the micronized silica dispersion having an average particle size of about 1 to 30 μm is preferably contained in the coating composition in the range of about 1 to 20% by weight, and when the content is within the above range, the quenching agent (quenched) Can be improved. The amount of the quencher to be used is in the range of about 1 to 20% by weight based on the total amount of the composition. If the content is less than about 1% by weight, it is difficult to obtain a quenching effect. If the content is more than about 20% by weight, scratch resistance is deteriorated.

In addition to the above-mentioned components, it has excellent physical properties such as abrasion resistance, adhesiveness and heat resistance, and it can prevent cracks and erosion of plastic materials by using a water-based paint instead of oil-based coatings, In addition, various additives such as anti-settling agent, anti-coloring agent and the like may be further added to the coating composition for automobile plastic which can provide good scratch resistance. The amount of these additives to be used may be properly adjusted depending on the desired end use and various factors It can be used by adding and subtracting.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but it should be understood that the present invention is not limited to these examples. Table 1 shows the components and their contents for preparing the aqueous coating composition.

<Table 1>

A coating film was formed using the aqueous coating composition samples according to each of the above Examples and Comparative Examples, and the following test was carried out.

<Test Example: Evaluation of Physical Properties of Coating Film>

Each water-based coating composition prepared by the composition shown in Table 1 was coated on a test piece of polycarbonate / acrylonitrile butadiene styrene (PC / ABS) to a thickness of about 20 to 40 탆, allowed to stand at room temperature for about 15 minutes, Lt; 0 &gt; C for about 30 minutes to complete the sample. Various evaluation tests were carried out on the following items using the completed samples.

Scratch test: When the coated specimen according to Example 1 and Comparative Examples 1 to 5 was moved vertically to the coated film surface using a sapphire scratcher (tip: 1 mm) under a load of 10 cm and a load of 500 gf according to JIS K 6718, , And confirmed the results. At this time, the evaluation of the scratch resistance was expressed as excellent (5) to poor (1) according to the degree of scratching.

Reinforcing test: A first coating was applied to the polycarbonate / acrylonitrile butadiene styrene (PC / ABS) specimen, and then the coated film was repainted on the dried film at intervals of one day. The adhesion test was carried out according to the elapsed time. The specimens were cross-cut by 11 cuts at 2 mm intervals horizontally and vertically. The surface was then cleaned with a soft brush and firmly adhered to the specimens of the appropriate width and length. The tape was then cut at a 90 ° angle The number of scale marks peeled off by pulling strongly was counted. It is also called a checkerboard adhesion test. The number of peeled checkers was measured from a total of 100 checkerboard scales, and the more the scraped scales were, the worse the adhesion was evaluated.

Inner Sun Cream Resistance: Two sheets of the same size (TOYOSYNTHETIC, CH2070-3) were superimposed on an acrylic plate (50 mm x 50 mm) and 0.25 g of sun cream was applied to the entire surface. The application area of the sun cream was placed on the coating specimen, and the acrylic plate was pressed to be in close contact. After standing for 1 hour in a thermostatic chamber at 80 ± 2 ° C, the white cotton cloth and the acrylic plate were removed. After standing at room temperature for 10 to 15 minutes, it was washed with a neutral detergent and dried. The surface condition of the coating film was examined and immediately subjected to the above re-coatability test.

Pot life test:

A paint having an initial viscosity of 120 to 130 seconds in which a subject and a curing agent were mixed was stirred at 200 to 300 RPM. The time point at which the viscosity changed over 30 seconds was measured at intervals of 30 minutes.

The physical properties of the coating were evaluated on five specimens for each composition, and the average values were taken. The results are shown in Table 2.

<Table 2>

As shown in Table 2, it can be confirmed that the coating film prepared using the water-based coating composition according to Example 1 exhibits excellent physical properties. It can be confirmed that the water-based coating composition according to Example 1 is the most excellent in all physical properties such as scratch resistance, re-coatability, resistance to sun cream, and pot life.

As described above, the water-base coating composition of the present invention and the coating film forming method of the present invention provide a water-based coating composition capable of forming a coating film through conventional 1-coat 1 baking of 2-coat 2 baking, It is possible to improve physical properties in terms of resistance to weathering, resistance to sun cream, and pot life, and it is possible to protect from ultraviolet rays, heat, chemicals and the like for a long time, and to provide soft touch and increase strength of painted surface, .

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (17)

10 to 20% by weight of a water-soluble polyurethane resin having a hydroxyl group;
1 to 10% by weight of a water-dispersible acrylic resin comprising a) an acrylate monomer, b) a radical initiator, c) an amine-based neutralizing agent and d) a water-dispersible organic solvent;
20 to 30% by weight of a water dispersible polyurethane resin;
10 to 20% by weight of a water-dispersible polycarbonate urethane resin;
1 to 20% by weight of a hardener; 0.01 to 1% by weight of a curing accelerator; 0.1 to 5 wt% wetting agent; 0.1 to 2% by weight of a light stabilizer; 0.1 to 3% by weight of a slip agent; 0.01 to 2% by weight of antifoaming agent; 1 to 10% by weight of a pigment and 10 to 30% by weight of a solvent,
The hydrous polyurethane resin having a hydroxyl group
a) 5 to 30% by weight of an isocyanate having 2 or more average functional groups, b) 2 to 10% by weight of a hydrophilic polyol having an average number of functional groups of 2 to 500, and a weight average molecular weight of 500 to 5,000, c) a polycarbonate polyol and a polyester 30 to 60% by weight of a polyol compound comprising a polyol, d) 5 to 25% by weight of a solvent and e) 1 to 5% by weight of a neutralizing agent. delete delete The process of claim 1, wherein the isocyanate having two or more average functional groups is selected from the group consisting of toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, And at least one member selected from the group consisting of a polyfunctional isocyanate-derived polyfunctional isocyanate. The hydrophilic polyol as claimed in claim 1, wherein the hydrophilic polyol having two or more average functional groups is at least one selected from the group consisting of polyoxyethylene glycol, polycaprolactone diol containing a carboxyl group in a side chain, polyether diol having a sulfonic acid group in a side chain, and poly An oxyethylene group, and a polyol having an oxyethylene group. The waterborne coating composition according to claim 1, wherein the polycarbonate polyol and the polyester polyol have a weight average molecular weight of 500 to 5,000. The aqueous coating composition according to claim 1, wherein the solvent comprises at least one selected from the group consisting of N-methyl pyrrolidone, acetone, methyl ethyl ketone, dimethyl formamide, glycol ether ester and hydrogenated furan Composition. The waterborne coating composition according to claim 1, wherein the neutralizing agent comprises at least one selected from the group consisting of N-methyldiethanolamine and triethanolamine. delete The water-dispersible polyurethane resin according to claim 1, wherein the water-dispersible polyurethane resin comprises a) an isocyanate having two or more average functional groups, b) a hydrophilic polyol having two or more average functional groups of 500 to 5,000, c) 500-5000 of acrylic polyols and ester polyols, d) a solvent and e) a neutralizing agent. Applying and drying the base coating composition on the plastic material;
a) 5 to 30% by weight of an isocyanate having 2 or more average functional groups, b) 2 to 10% by weight of a hydrophilic polyol having an average number of functional groups of 2 to 500, and a weight average molecular weight of 500 to 5,000, c) a polycarbonate polyol and a polyester From 30 to 60% by weight of a polyol compound comprising a polyol, d) from 10 to 20% by weight of a hydrogenated polyurethane resin having a hydroxyl group comprising from 5 to 25% by weight of a solvent and from 1 to 5% by weight of a neutralizing agent; 1 to 10% by weight of a water-dispersible acrylic resin comprising a) an acrylate monomer, b) a radical initiator, c) an amine-based neutralizing agent and d) a water-dispersible organic solvent; 20 to 30% by weight of a water dispersible polyurethane resin; 10 to 20% by weight of a water-dispersible polycarbonate urethane resin; 1 to 20% by weight of a hardener; 0.01 to 1% by weight of a curing accelerator; 0.1 to 5 wt% wetting agent; 0.1 to 2% by weight of a light stabilizer; 0.1 to 3% by weight of a slip agent; 0.01 to 2% by weight of antifoaming agent; 1 to 10% by weight of a pigment and 10 to 30% by weight of a solvent; And
And drying the applied coating composition. delete delete The method of claim 11, wherein the isocyanate having two or more average functional groups is selected from the group consisting of toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, Derived polyfunctional isocyanate, and a polyfunctional isocyanate derived from the polyfunctional isocyanate. The hydrophilic polyol as claimed in claim 11, wherein the hydrophilic polyol having two or more average functional groups is at least one selected from the group consisting of polyoxyethylene glycol, polycaprolactone diol containing a carboxyl group in a side chain, polyether diol having a sulfonic acid group in a side chain, A polyoxyethylene group, a polyoxyethylene group-containing polyoxyethylene group, and a polyoxyethylene group-containing polyol. The method for forming a coating film according to claim 11, wherein the polycarbonate polyol and the polyester polyol have a weight average molecular weight of 500 to 5,000. The method for forming a coating film according to claim 11, wherein the coating composition is applied on the plastic material to a thickness of 20 to 40 탆 and then dried.