KR102200688B1 - Water paint composition of base coating, painting method for vehicle parts and vehicle parts using the same - Google Patents

Abstract

The present invention relates to an aqueous coating composition for a base coat, a vehicle component coating method using the same, and a vehicle component. In one embodiment, the aqueous coating composition for the base coat is 60 to 80% by weight of deionized water, 5 to 15% by weight of non-halogenated polyolefin resin, 5 to 15% by weight of polyurethane dispersion, 5 to 15% by weight of hydrocarbon solvent, pigment It includes 3 to 10% by weight and 0.5 to 3% by weight of additives, and the non-halogenated polyolefin is a polyolefin modified with at least one of maleic acid and maleic anhydride. According to the present invention, adhesion to paint is excellent, convenience, reliability, appearance, durability, moisture resistance, abrasion resistance, weather resistance are excellent, and economic effects such as process reduction and cost reduction are excellent.

Description

Water-based coating composition for base coat, vehicle parts coating method and vehicle parts using the same {WATER PAINT COMPOSITION OF BASE COATING, PAINTING METHOD FOR VEHICLE PARTS AND VEHICLE PARTS USING THE SAME}

The present invention relates to an aqueous coating composition for a base coat, a vehicle component coating method using the same, and a vehicle component.

More specifically, the present invention relates to a water-based coating composition for a base coat, including a non-halogenated polyolefin that can function as a primer, showing excellent adhesion performance and excellent environmentally friendly and economical effect, a vehicle component painting method using the same, and a vehicle component. will be.

As materials for most vehicle parts including bumpers, in order to meet market requirements such as price, performance, and recycling, conventionally, substrates made of thermoplastic polyolefin (TPO) materials such as polyethylene and polypropylene are widely used instead of metal molded bodies.

However, since these polyolefin materials have nonpolar and low surface tension properties, it is generally difficult to paint or adhere. Accordingly, in order to improve the adhesion between the coating film and the substrate in the case of coating these molded articles, a method of first forming a primer layer on the substrate to improve adhesion is common.

2 is a cross-sectional view of a vehicle component (bumper) 200 painted by a conventional painting method. Referring to FIG. 2, after forming a primer coating layer 12 on the surface of a polyolefin-based substrate 10 for vehicle parts, a base coating layer expressing a desired color on the surface of the primer coating layer 12 (Base coating layer) 22 is formed, the so-called 3-coating 1 formed by drying (baking) and forming a clear coating layer 30 for the purpose of protecting the base coating layer 22 and providing gloss and sharpness, etc. -Painting is done with the baking (3C-1B) system.

However, the primers applied to the above-described polyolefin substrate generally contain a halogenated polyolefin resin to impart polarity, but organic components such as chlorine remain on the substrate on which the coating film is formed, so that odors and volatile organic compounds (volatile organic compounds, etc.) VOC) occurs, causing users and workers to be exposed to harmful environments.

Recently, there is a movement to regulate the emission of volatile organic compounds in countries around the world, and in reality, Europe and the United States are preparing guidelines to regulate the emission of volatile organic compounds in order to improve the concentration of ozone in the atmosphere.

In order to solve this problem, Japanese Laid-Open Patent Publication No. 2002-121462 proposes a primer comprising a specific halogenated polyolefin and a specific blocked polyisocyanate together with a polyol resin. However, this technology also has a problem due to chlorine as described above, since it is necessary to use a halogenated polyolefin.

In addition, when the above-described 3-coating system is applied, equipment such as a spray booth, robotic painter, circulation system, tank, sanding workshop, oven, etc. are required. In particular, there is a problem in that high cost is required in terms of process cost and equipment operation, such as manpower input for formation and correction of the primer coating layer, air conditioning and oven used for painting and curing are required.

On the other hand, paints play roles such as corrosion, aging, penetration of water or moisture, prevention of erosion, sound insulation, heat resistance, electrical conductivity, and plastering, and are classified according to types, and oil-based paints are commonly used. However, oil-based paints have limitations in that VOCs are discharged by diluting a thinner or the like in a liquid to apply cleanly without being thick when used, and that the speed of drying is slow. Therefore, there is a growing need for an eco-friendly water-based coating composition that can be used after diluting with water to compensate for these limitations, and has a property that improves color and dries quickly.

As discussed above, there is an urgent need to develop a coating method that can reduce costs by using a non-halogenated water-based paint that can solve the harmful effects of halogenated polyolefin resins and the impact on the human body and the environment. Until now, it is impossible to find anything disclosed about this.

An object of the present invention is excellent in adhesion to the polyolefin-based material as a substrate for vehicle parts and a clear coating paint to be subsequently painted, and also convenience, reliability, appearance, durability, moisture resistance, abrasion resistance, weather resistance, and process reduction, It is to provide an eco-friendly aqueous coating composition for an eco-friendly base coat having excellent economic effects such as cost reduction.

Another object of the present invention is to provide a vehicle component coating method using the aqueous coating composition for the base coat.

Another object of the present invention is to provide a vehicle component painted by the vehicle component painting method.

One aspect of the present invention relates to an aqueous coating composition for a base coat. In one embodiment, the aqueous coating composition for the base coat is 60 to 80% by weight of deionized water, 5 to 15% by weight of non-halogenated polyolefin resin, 5 to 15% by weight of polyurethane dispersion, 5 to 15% by weight of hydrocarbon solvent, pigment 3 to 10% by weight and 0.5 to 3% by weight of additives, and the non-halogenated polyolefin is a polyolefin modified with at least one of maleic acid and maleic anhydride.

In one embodiment, the non-halogenated polyolefin resin is characterized in that the weight average molecular weight is 80,000 to 150,000 g/mol.

In one embodiment, it is characterized in that it further comprises 0.1 to 3% by weight of a thickener based on the total weight of the aqueous coating composition for the base coat.

Another aspect of the present invention relates to a vehicle component coating method using the aqueous coating composition for the base coat. In one embodiment, the vehicle component painting method comprises the steps of forming a base coating layer by applying the water-based coating composition for a base coat to a surface of a substrate for a vehicle component; Forming a clear coating layer on the surface of the formed base coating layer; And baking the formed base coating layer and the clear coating layer.

In one embodiment, prior to applying the water-based coating composition for the base coat, the step of plasma treatment of the surface of the substrate for vehicle parts; characterized in that it further comprises.

In one embodiment, the baking is characterized in that carried out at 70 ~ 100 ℃.

Another aspect of the present invention relates to a vehicle component painted by the vehicle component painting method. In one embodiment, the vehicle component is a vehicle component substrate; A base coating layer formed on the surface of the vehicle component substrate; And a clear coating layer formed on the surface of the base coating layer, wherein the base coating layer is formed from the aqueous coating composition for the base coat.

In one embodiment, the thickness of the base coating layer is 15 ~ 30㎛, characterized in that the thickness of the clear coating layer is 25 ~ 40㎛.

In one embodiment, the vehicle component substrate is characterized in that one selected from a bumper, a side seal molding, a side garnish, and a side protector.

The base coating layer formed by applying the aqueous coating composition for the base coat according to the present invention can function as an existing primer coating layer at the same time, so it has excellent adhesion to the substrate, and also excellent adhesion to the clear coating paint to be painted afterwards. It has excellent convenience and reliability, excellent appearance, durability, moisture resistance, abrasion resistance, and weather resistance, and is environmentally friendly by minimizing the generation of volatile organic compounds by applying a non-halogenated polyolefin, shortening the primer coating process and reducing costs, etc. It has excellent economic effect and may be particularly suitable for vehicle bumper applications.

1 is a cross-sectional view of a vehicle component painted according to an embodiment of the present invention.
2 is a cross-sectional view of a vehicle part painted by a conventional painting method.
3 is a photograph showing the results of the adhesion test for the coating specimen prepared in the Example according to the present invention.

One aspect of the present invention relates to an aqueous coating composition for a base coat. In one embodiment, the aqueous coating composition for the base coat may include deionized water, a non-halogenated polyolefin resin, a polyurethane dispersion, a hydrocarbon-based solvent, a pigment, and an additive.

Hereinafter, the components constituting the present invention will be described in detail.

Deionized water

In the present specification, the'deionized water' refers to water formed by a deionization operation and is close to pure water obtained by removing all dissolved ions in water, which is usually used for the same purpose as distilled water.

Here, "deionization" refers to an operation of obtaining high-quality water close to pure water from which inorganic salts in water have been removed for the purpose of use for industrial water, drinking water, and the like. Usually, ion exchange resin is used, and it is manufactured by using a combination of hydrogen type strong acidic cation exchange resin and aquatic weak basic anion exchange resin. This removes cations such as sodium and calcium contained in natural water, and anions such as chloride ions and sulfate ions. do.

In one embodiment, the deionized water may be included in an amount of 64 to 66% by weight based on the total weight of the aqueous coating composition for the base coat. In the above range, the compatibility and adhesion of the aqueous coating composition for the base coat may be excellent, and discoloration of the pigment may be prevented, so that the appearance may be excellent. When the deionized water is included in an amount of less than 64% by weight, adhesion is deteriorated.

Non-halogenated polyolefin resin

The non-halogenated polyolefin resin can be included for the purpose of providing excellent adhesion by increasing the surface tension of the aqueous coating composition for the base coat and the polyolefin substrate, replacing the halogenated polyolefin used in the existing primer, and preventing discoloration of the pigment. have.

In addition, in the present specification, the'non-halogenated polyolefin resin' is defined to mean a polyolefin resin containing no halogen.

In one embodiment, the non-halogenated polyolefin resin may be a modified polyolefin. In one embodiment, the non-halogenated polyolefin may be a polyolefin modified with at least one of maleic acid and maleic anhydride. The modified polyolefin resin has excellent compatibility with the components of the aqueous coating composition for the base coat, and can improve adhesion to the polyolefin substrate, water resistance, and physical properties of chemical resistance.

In one embodiment, the non-halogenated polyolefin resin is high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene-propylene copolymer, metallocene-polyethylene, polypropylene homopolymer, polypropylene copolymer , Metallocene-polypropylene, and a polyolefin resin selected from the group consisting of reinforcing physical properties of the polypropylene homopolymer or copolymer-composite resin may be used.

In one embodiment, the non-halogenated polyolefin resin may be a non-halogenated polyolefin emulsion resin. Emulsion resin acts as a binder, and through the combination of the emulsion resin and all pigment components including pigment components added, that is, coloring pigments, extender pigments, and rust preventive pigments, the corrosion resistance of the dry coating film, moisture volatility in the coating film, The appearance of the coating film, the storage stability of the coating material in the container, the function of preventing the softening of the coating film when immersed in hot water can be maintained in a good state, and the dipping and spray coating can be maintained in a good state.

In one embodiment, the non-halogenated polyolefin resin has a resin solid content of 5 to 20% and its weight average molecular weight may be 80,000 to 150,000 g/mol . Preferably, it has a resin solid content of 8 to 15% and may be 90,000 to 130,000 g/mol. More preferably, it has a resin solid content of 10 to 12% and may be 100,000 to 120,000 g/mol. In the above range, the adhesion, appearance and reliability of the aqueous coating composition for the base coat may be excellent.

In one embodiment, the non-halogenated polyolefin resin is acid-modified PP, and the modification ratio may be 0.1 to 99%.

In one embodiment, the non-halogenated polyolefin resin may be included in an amount of 5 to 15% by weight based on the total weight of the aqueous coating composition for the base coat. Preferably it may be included in 8 to 13% by weight. More preferably, it may be included in 9 to 12% by weight. In the above range, the compatibility and adhesion of the coating composition for the base coat may be excellent, and discoloration of the pigment may be prevented, so that the appearance may be excellent. When the non-halogenated polyolefin resin is included in an amount of less than 5% by weight, adhesion is deteriorated, and when it is included in an amount exceeding 15% by weight, compatibility with other components and physical properties of the base coating layer may decrease.

Polyurethane dispersion

Polyurethane dispersion has properties such as adjacent packing effect and easy fusion, and can be manufactured from hard and hard to soft and flexible polymers, and has excellent physical properties in terms of abrasion, impact, and scratch resistance. Can represent.

The polyurethane dispersion of the present invention is in the form of a polyurethane resin dispersed in an aqueous medium. Here, the polyurethane resin can be synthesized by reacting a polyol and an isocyanate. As the polyol used in the polyurethane resin, acrylic polyol, polyester polyol, polycarbonate polyol, or the like can be used. The polyurethane resin preferably has a pH of 7.5 to 8.5, a solid content of 38 to 40%, and a viscosity of 50 to 500 mPas. In the above range, it is possible to implement a solid coating film in the primerless base water-based coating composition for vehicle parts and improve physical properties such as water resistance.

On the other hand, as an aqueous medium, water, a mixed medium of water and a hydrophilic organic solvent, etc. are mentioned. Examples of water include fresh water, ion-exchanged water, distilled water, and ultrapure water. Among them, it is preferable to use ion-exchanged water for ease of availability or for preventing the particles from becoming unstable under the influence of salt. Hydrophilic organic solvents include lower monohydric alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and glycerin, aprotic properties such as N-methylmorpholine, dimethylsulfoxide, dimethylformamide, and N-methylpyrrolidone. Hydrophilic organic solvents, etc. are mentioned. The amount of the hydrophilic organic solvent in the aqueous medium is preferably 20% by weight or less.

In one embodiment, the polyurethane dispersion may be used having an average molecular weight of 50,000 to 100,000 g/mol. Preferably, those having an average molecular weight of 60,000 to 90,000 g/mol may be used. It has excellent dispersibility within the above range, excellent strength of a coating film obtained by coating and drying, and excellent hydrolysis resistance, durability, heat resistance, and abrasion resistance.

In one embodiment, the polyurethane dispersion may be included in an amount of 5 to 15% by weight based on the total weight of the aqueous coating composition for the base coat. Preferably it may be included in 8 to 13% by weight. More preferably 10 to 11% by weight may be included. In the above range, compatibility with the aqueous coating composition for the base coat is excellent, and it is easily mixed with a pigment to be described later, so that the appearance and durability are excellent. When the polyurethane dispersion is included in an amount of less than 5% by weight, adhesion is deteriorated, and when it is included in an amount exceeding 15% by weight, compatibility with other components, workability, and durability of the base coating layer may decrease.

Hydrocarbon solvent

The hydrocarbon (Hydrocarbon)-based solvent may be included for the purpose of dissolving the aqueous coating composition for the base coat to adjust the viscosity, improving the smoothness of the coating layer and improving the coating workability. As the hydrocarbon-based solvent, an aliphatic hydrocarbon-based solvent, an aromatic hydrocarbon-based solvent, or a mixture thereof may be used.

Preferably, an aromatic hydrocarbon-based solvent can be used. For example, benzene, toluene, xylene, xylene, and the like can be used. These may be used alone or in combination of two or more, but are not limited thereto. When the above type of hydrocarbon solvent is used, the evaporation rate is slow and the spreadability of the pigment can be improved, thereby improving workability and adhesion of the coating composition for the base coat.

In one embodiment, the hydrocarbon-based solvent may be included in an amount of 5 to 15% by weight based on the total weight of the aqueous coating composition for the base coat. Preferably it may be included in 7 to 13% by weight. More preferably 10 to 11% by weight may be included. It is easy to adjust the viscosity in the above range, and the smoothness and coating workability of the base coating layer may be excellent. When the hydrocarbon-based solvent is included in an amount of less than 5% by weight, the workability of the water-based coating composition for the base coat decreases, and when it is included in an amount of more than 15% by weight, the physical properties of the water-based coating composition for the base coat are lowered and The problem of eroding the surface of the substrate may occur.

Pigment

The pigment may be included for the purpose of expressing a desired color by mixing with the polyurethane dispersion described above in the present invention. Pigments provide color, particularly colored, to vehicle parts, and may include pigments such as organic/inorganic colored pigments, aluminum-paste, pearl, and extender pigments commonly used in painting vehicle parts. And these may be used alone or in combination of two or more. Specifically, red, yellow/orange, blue, black, white, pearl, metallic, etc. may be used, but the present invention is not limited thereto.

When pigments are used in excess, they can adversely affect the properties of the coating layer when they are painted on vehicle parts, and the amount of pigments used must be controlled.

In one embodiment, the pigment may be included in 3 to 10% by weight based on the total weight of the aqueous coating composition for the base coat. Preferably it may be included in 4 to 8% by weight. More preferably 5 to 6% by weight may be included. In the above range, when used in the aqueous coating composition for a base coat, material concealment and sufficient color can be realized, and the physical properties of the coating film are not affected.When the pigment is included in less than 3% by weight, the color expression is insignificant and the appearance characteristics are deteriorated, When it contains more than 10% by weight, physical properties such as adhesion of the aqueous coating composition for the base coat may be deteriorated.

additive

The additive is added in a predetermined content range to the aqueous coating composition for the base coat, thereby implementing additional effects for improving wettability and leveling properties during coating.

In one embodiment, the additive may be included in 0.5 to 3% by weight based on the total weight of the aqueous coating composition for the base coat. Preferably it may be included in 0.8 to 2% by weight. More preferably 1 to 2% by weight may be included. In the above range, the adhesion of the aqueous coating composition for the base coat is not lowered, and excellent wettability, leveling properties, and the like can be implemented.

In specific embodiments, additives commonly included in the aqueous coating composition for the base coat may be used. For example, the additive may include one or more of a wetting agent, an antifoaming agent, a light stabilizer, an adhesion promoter, a surface modifier, an anti-staining agent, a softening agent and a thickening agent.

The wetting agent is for improving the wettability and leveling properties of the coating film during coating by adjusting the surface tension of the aqueous coating composition for the base coat, and may be included in 0.5 to 3% by weight of the aqueous coating composition for the base coat. In the above range, there may be an effect of improving the wettability and leveling properties of the coating film.

The antifoaming agent is a mixture of a lipophilic substance and a polysiloxane and enhances the appearance of the coating film by destroying air bubbles generated during coating, and may be included in an amount of 0.1 to 1.5% by weight in the aqueous coating composition for a base coat. In the above range, it is possible to improve the appearance by suppressing the generation of bubbles during coating.

The light stabilizer is an ultraviolet absorber for enhancing the weather resistance of the coating film, and may be included in an amount of 0.5 to 3% by weight of the coating composition. Within the above range, there may be an effect of improving the weather resistance of the coating film.

The adhesion promoter is mainly for improving the adhesion of the aqueous coating composition when used in an appropriate amount in the metallic coating, and may be included in 0.5 to 3% by weight of the aqueous coating composition. In the above range, there is an effect of improving adhesion, and oxidation of silver can be prevented.

The surface modifier is for improving the wettability and leveling properties of the coating film during coating by controlling the surface tension of the aqueous coating composition for the base coat, and may be included in an amount of 0.1 to 1.5% by weight of the composition for aqueous coating. In the above range, there may be an effect of improving the wettability and leveling properties of the coating film.

The stain inhibitor is for suppressing the occurrence of stains when forming a coating film through a uniform arrangement of pigments, particularly silver particles during coating, and is 0.1 to 10% by weight, for example, 0.1 to 1% by weight, or 1 to 10% by weight of the coating composition. It can be included in %. In the above range, there may be an effect of suppressing the occurrence of spots when forming a coating film.

The softener is for alleviating the occurrence of cracks in the dried coating film, and may be included in an amount of 0.5 to 5% by weight of the composition for water-based coating. In the above range, the occurrence of cracks in the dry coating film is alleviated to improve impact resistance and bending resistance.

In the present invention, the aqueous coating composition for the base coat is characterized in that it further comprises 0.1 to 3% by weight of a thickener based on the total weight of the composition.

Thickener

The thickener is to control the viscosity of the aqueous coating composition for a base coat and impart a thixotropic index to prevent the flow of the aqueous coating composition during painting.It is mainly used in water-based coatings, and the composition for water-based coatings is 25 At °C, the viscosity can be 700-1300cPs.

In one embodiment, the thickener may be included in an amount of 0.1 to 3% by weight based on the total weight of the aqueous coating composition for the base coat. Preferably it may be contained in 0.2 to 2% by weight. More preferably 0.3 to 1% by weight may be included. In the above range, when the composition for water-based paint is painted, flow may be prevented, and it may have an appropriate viscosity, so that coating on the vehicle part material may be possible.

Another aspect of the present invention relates to a vehicle component coating method using the aqueous coating composition for the base coat. In one embodiment, the vehicle component painting method comprises the steps of forming a base coating layer by applying the above-described aqueous coating composition for a base coat to a material surface for a vehicle component; Forming a clear coating layer on the surface of the formed base coating layer; And baking the formed base coating layer and the clear coating layer.

In the vehicle parts painting method, even if the conventional primer application step is not included, by applying the aqueous coating composition for the base coat without primer treatment on the surface of the vehicle parts material, the adhesion of the existing primer application and the color effect of the base coat Can be achieved at the same time.

In one embodiment, the vehicle component substrate may be a polyolefin-based material.

The application of the aqueous coating composition for the base coat may be carried out by a conventional method. For example, it is possible to supply the water-based coating composition for the base coat to a painting gun of a painting robot and paint each time the vehicle parts pass.

In one embodiment, the thickness ratio of the base coating layer and the clear coating layer may be formed in a ratio of 1:0.8 to 2.5. Preferably, it may be formed in a ratio of 1:1 to 2. More preferably, it may be formed in a ratio of 1:1.5-2. In the above ratio, the surface and adhesion of the vehicle component material may be excellent, and color expression and physical properties may be excellent.

In one embodiment, the base coating layer may be formed by being applied to the surface of the vehicle component material to a thickness of 15 ~ 30㎛. Preferably it may be formed to a thickness of 15 ~ 25㎛. More preferably, it may be formed to a thickness of 20 ~ 25㎛. In the above range, the surface and adhesion of the vehicle component material are excellent, color expression and physical properties are excellent, and appearance defects can be prevented.

The clear coating layer may be formed by applying a commonly used component to the surface of the formed base coating layer. For example, it is possible to use a urethane paint prepared by urethane bonding of acrylic and isocyanate. In addition, a curing agent may be further included for easy curing in the baking step. For example, it may further include a polyisocyanate type curing agent.

In one embodiment, the clear coating layer may be formed by applying to a thickness of 25 ~ 40㎛. Preferably it may be formed to a thickness of 30 ~ 40㎛. More preferably, it may be formed to a thickness of 30 ~ 35㎛. In the above range, the base coating layer may be easily protected, and weather resistance, water resistance, chemical resistance, and environmental resistance may be excellent.

In one embodiment, the baking may be carried out for 20 to 60 minutes at 70 to 100° C. using the formed base coating layer and the clear coating layer using hot air. Within the above range, easy drying can be performed to prevent appearance defects.

In addition, in order to improve the adhesion of the water-based coating composition for the base coat and to improve the appearance after painting, washing the substrate for vehicle parts before applying the water-based coating composition for the base coat; may be further included.

The cleaning may be performed by a conventional method, for example, by a whipping method such as isopropyl alcohol (IPA).

In addition, in one embodiment of the present invention, prior to applying the aqueous coating composition for the base coat, the surface of the vehicle component substrate is subjected to plasma treatment. The plasma treatment may be performed for the purpose of removing foreign substances from the surface of the substrate, improving the surface tension and contact angle of the surface of the substrate, and improving the appearance after painting.

The plasma treatment may be performed by a conventional method. In one embodiment, the plasma generated by the plasma burner may be sprayed onto the surface of the vehicle component substrate. In this case, the filling gas of the plasma burner may be used by mixing an inert gas and a reactive gas. Argon (Ar), xenon (Kr), and xenon (Xe) may be used as the inert gas, and as the reactive gas, O ₂ , N ₂ , NH ₃ , methane, ethane and propane It can be used including one or more. During the plasma treatment, molecules of the reactive gas are also ionized during the plasma treatment, and neutral atoms (or molecules) that are not ionized are activated with high kinetic energy due to collision by electrons.

Therefore, during the plasma treatment, the surface of the substrate for vehicle parts is activated to increase the surface tension and contact angle, and foreign substances such as dust and release agents remaining on the surface are easily removed by the high-temperature flame generated from the burner, and the adhesive strength Due to the improvement, adhesion is improved, and a section having a complex shape can be easily painted while forming a base coating layer having a vivid color, thereby preventing an unpainted phenomenon. In addition, the plasma treatment may have an advantage of not impairing physical properties of the vehicle component substrate itself.

When plasma treatment of the surface of the vehicle component substrate described above, the separation distance between the vehicle component substrate and the plasma burner, the processing speed, and the mixing ratio of the inert gas and the reactive gas, etc. It can be adjusted according to physical properties.

Another aspect of the present invention relates to a vehicle component by the vehicle component painting method. The vehicle component may include a vehicle component substrate; A base coating layer formed on the surface of the vehicle component substrate; And a clear coating layer formed on the surface of the base coating layer.

1 is a cross-sectional view of a vehicle component 100 painted according to an embodiment of the present invention. In FIG. 1, a base coating layer 20 and a clear coating layer 30 are sequentially stacked on the surface of the vehicle component substrate 10.

The vehicle component substrate 10 may be a polyolefin-based material. For example, it may be a polypropylene material, but is not limited thereto.

The base coating layer 20 may be formed from the aforementioned coating composition for a base coat. In one embodiment, the base coating layer 20 may be formed to a thickness of 15 ~ 30㎛. Preferably it may be formed to a thickness of 15 ~ 25㎛. More preferably, it may be formed to a thickness of 20 ~ 25㎛. In the above range, it is possible to have excellent adhesion to the surface of the vehicle component substrate 10, excellent color expression and physical properties, and prevent appearance defects.

The clear coating layer 30 may include the aforementioned coating composition for a base coat. The clear coating layer 30 may contain commonly used components. For example, it is possible to use a urethane paint prepared by urethane bonding of acrylic and isocyanate. In addition, as described above, a curing agent may be further included for curing in the baking process. For example, it may further include a polyisocyanate type curing agent.

In one embodiment, the clear coating layer 30 may be formed on the surface of the formed base coating layer 20 to a thickness of 25 to 40 μm. Preferably it may be formed to a thickness of 30 ~ 40㎛. More preferably, it may be formed to a thickness of 30 ~ 35㎛. In the above range, the base coating layer 20 may be easily protected, and weather resistance, water resistance, chemical resistance, and environmental resistance may be excellent.

The vehicle component base includes, for example, a bumper, side sill molding, side garnish, side protector, and other polyolefin-based materials. ) It may include color painted parts, but is not limited thereto.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are for aiding understanding of the present invention, and the scope of the present invention is not limited to the following examples. Contents not described herein can be sufficiently technically inferred by those skilled in the art, and thus description thereof will be omitted.

Example

The specifications of each component used in the following Examples and Comparative Examples are as follows:

As the halogenated polyolefin resin, EW5515 manufactured by Toyobo was used. Hydrocarbon-based solvents were selected from DOW and Eastmant's BC, DPM, DPnB, DPnP, and Hexylglycol. As the pigment, IRGAZINDPPREDBTR manufactured by BASF was used. As an additive, S104BC manufactured by Air product was used. As a thickener, Aquatix 8421 manufactured by BYK was used.

Composition (% by weight) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Deionized water 64 66 65 64 56 Non-halogenated polyolefin emulsion 10.5 9.5 10.5 - 4 Halogenated polyolefin - - - 10.5 - Polyurethane dispersion 10 9 9 10 17 Hydrocarbon solvent 9 9 9 9 20 Pigment 5 5 5 5 2 additive One One One One 0.5 Thickener 0.5 0.5 0.5 0.5 0.5 Total content 100 100 100 100 100

Examples 1 to 3 and Comparative Examples 1 to 2

As the aqueous coating composition for the base coat of Examples 1 to 3 and Comparative Examples 1 to 2, an aqueous coating composition including the component content ratio shown in Table 1 was prepared.

Comparative Example 1 is a performance comparison of Toyobo's EW5515 containing chlorine as a halogenated element, and Comparative Example 2 is a comparative experiment in which chlorine as a halogenated element was contained but other content conditions were set to deviate from the conditions of Example of the present invention.

The substrate for vehicle bumpers made of HR580, a type of thermoplastic olefin (TPO), was washed with isopropyl alcohol. As the composition for clear coating applied in Examples 1 to 3 and Comparative Examples 1 to 2, a urethane paint and a curing agent (polyisocyanate) prepared by urethane bonding of acrylic and isocyanate were prepared.

The aqueous coating composition for base coat prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was applied to the surface of the bumper substrate to form a base coating layer having a thickness of 20 μm, and after 10 minutes elapsed for the clear coating The composition was applied to form a clear coating layer having a thickness of 30 μm. After 5 minutes passed, baking was performed at 80° C. for 30 minutes to complete the painting of the vehicle bumper.

Test example

Physical properties such as adhesion of the vehicle bumper specimens coated in Examples 1 to 3 and Comparative Examples 1 to 2 were evaluated as follows, and are shown in Table 2 below.

(1) Adhesion: According to JIS D0202, parallel lines were drawn at intervals of 2 mm to adhere the cellophane tape and then peeled off, and the state of the coating film was graded. All of the M-6 was stripped, and it was judged to meet the standard below M-2.5.

(2) Impact resistance: 4.9 N (0.5 N (0.5) at room temperature using a weight drop tester of ISO 6272 or JIS K 5600-5-3 with the coated surface of the bumper specimens of Examples 1 to 3 and Comparative Examples 1 to 2 facing up. The impact is applied to the coating surface with a weight of kgf) (diameter of 12.7 mm), and the state of the coating is investigated. In addition, the thickness of the test piece is 3.0±0.2 mm, and the weight is dropped from a height of 20 cm to observe peeling and cracking on the coating film with the naked eye. It was judged that fine cracking in the coating film was allowed, and if there was no peeling, the standard was satisfied.

(3) Acid resistance: 0.2 ml of hydrochloric acid of 0.1N was added dropwise to the surface of the coating film on the bumper specimens of Examples 1 to 3 and Comparative Examples 1 to 2, which had been painted, and left at room temperature for 24 hours, washed with water, and the film was in surface condition. Check. It is evaluated whether or not there is significant discoloration, fading, swelling, cracking, deterioration of gloss, and exposure of the adherend of the coating film. Depending on the level, it is evaluated with a gray scale (G/S) grade, and the higher the score, the better the acid resistance due to the formation of a solid coating film. If it is G/S level 3 or higher, it was judged to meet the standard.

(4) Alkali resistance: 0.2 ml of 0.1N sodium hydroxide was added dropwise on the surface of the bumper specimens of Examples 1 to 3 and Comparative Examples 1 to 2 on which the coating was completed, and left at room temperature for 24 hours and washed with water. And inspect the surface condition of the coating film. It is evaluated whether or not there is significant discoloration, fading, swelling, cracking, deterioration of gloss, and exposure of the adherend of the coating film. It is evaluated with a G/S grade according to the level, and the higher the score, the better the acid resistance due to the formation of a solid coating film. Gray scale (G/S) grade 3 or higher was judged to meet the standard.

(5) Chemical resistance: Grease, gasoline, engine oil, etc. are applied to the specimen coating, and the state of the coating film is evaluated after 2 hours in an oven at 80℃. Depending on the level, it is evaluated as a G/S grade, and the higher the grade, the better the chemical resistance due to the formation of a solid coating film. Gray scale (G/S) grade 3 or higher was judged to meet the standard.

(6) Moisture resistance: After leaving the specimen for 168 hours at 50°C and 98% relative humidity, the specimens were observed, and the gray scale, the degree of color difference value change (ΔE*), and adhesion were evaluated. It was judged to be satisfied if the adhesiveness was M-2.5 or less, the color difference value change (ΔE*) 2.0 or less, and G/S level 3 or more.

(7) Water resistance: After 10 days of putting the specimen in water at 40°C, the gray scale, the degree of color difference value change (ΔE*), and adhesion were evaluated. It was judged to be satisfied if the adhesiveness was M-2.5 or less, the color difference value change (ΔE*) 2.0 or less, and G/S level 3 or more.

(8) Salt water spray resistance: According to ISO 7253 or JIS K 5600-7, water is removed after spraying the specimen for 240 hours, and after leaving it at room temperature for 1 hour, G/S, degree of color difference value change (△E*) and adhesion Evaluated. It was judged to be satisfied if the adhesiveness was M-2.5 or less, the color difference value change (ΔE*) 2.0 or less, and G/S level 3 or more.

(9) Heat resistance: After leaving the specimens of Examples 1 to 3 and Comparative Examples 1 to 2 at 90°C for 300 hours, G/S, the degree of color difference value change (ΔE*), and adhesion were evaluated. It was judged to be satisfied if the adhesiveness was M-2.5 or less, the color difference value change (ΔE*) 2.0 or less, and G/S level 3 or more.

(10) Heat-resistance cycle: 80±2℃×3h → room temperature 1h → -40℃×3h → room temperature 1h → 50±2℃, 95%RH ×7~15h → Room temperature 1h cycle 3 times, take out and take out to room temperature After leaving for 1 hour at, the surface condition of the coating film was examined, and an adhesion test was immediately performed. In addition, the surface condition of the coating film was examined every cycle to evaluate the G/S, the degree of color difference value change (ΔE*), and adhesion. It was judged to be satisfied if the adhesiveness was M-2.5 or less, the color difference value change (ΔE*) 3.0 or less, and G/S level 3 or more.

(11) Accelerated weatherability: The specimen was mounted on an accelerated weathering tester, and G/S, the degree of change in color difference value (ΔE*), and adhesion were evaluated. It was judged to be satisfied if the adhesiveness was M-2.5 or less, the color difference value change (ΔE*) 2.0 or less, and G/S level 3 or more.

(12) Wear resistance: It was observed whether the surface of the coating film of the specimen was worn by reciprocating 500 times at a speed of 300 mm/sec. Depending on the level, it was rated as 0-5 points. The higher the score, the better the wear resistance.

(13) High pressure washability: After spraying the specimen coatings of Examples 1 to 3 and Comparative Examples 1 to 2 with a commercial high pressure washer (maintaining at least 8500 kPa for 5 seconds in a nozzle gun with a gun tip angle of 15° or 25°), the above The degree of peeling, swelling, and cracking of the specimen coatings of Examples 1 to 3 and Comparative Examples 1 to 2 was checked, and evaluated as 0 to 5 points according to the level. The higher the score, the lower the degree of peeling, swelling and cracking of the coating film.

(14) Low-temperature flexibility: After leaving the specimens of Examples 1 to 3 and Comparative Examples 1 to 2 at 90°C for 300 hours, the flexibility was evaluated and evaluated as 0 to 5 points depending on the level. The higher the score, the better the low-temperature flexibility.

(15) Low temperature impact property: After leaving the specimens of Examples 1 to 3 and Comparative Examples 1 to 2 at 90° C. for 300 hours, the impact property was evaluated and evaluated as 0 to 5 points according to the level. The higher the score, the better the low-temperature impact.

(16) Painting workability: The coating was performed by spraying, and was evaluated as 0-5 points according to the spreadability of the sprayed paint and the level of appearance at which the coating film was formed smoothly. The higher the score, the better the painting workability.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Adherence M-1 M-1 M-1 M-4 M-5 Impact resistance OK OK OK Peeling Peeling Acid resistance 5 5 5 4 4 Alkali resistance 5 5 5 4 4 Chemical resistance 5 5 5 5 4 Moisture resistance G/S 5 4 5 3 2 △E* 0.04 0.47 0.05 1.05 1.68 Adherence M-1 M-1 M-1 M-5 M-4 Water resistance G/S 5 5 4 3 2 △E* 0.761 0.66 0.05 1.27 1.59 Adherence M-1 M-1 M-1 M-4 M-5 Salt water spray resistance G/S 5 5 5 2 3 △E* 1.13 1.67 0.34 1.48 1.72 Adherence M-1 M-1 M-1 M-5 M-4 Heat resistance G/S 5 5 5 3 3 △E* 0.61 0.44 0.63 1.34 1.61 Adherence M-1 M-1 M-1 M-4 M-5 Heat cycle resistance G/S 5 5 5 3 2 △E* 0.18 0.44 0.61 1.82 1.49 Adherence M-1 M-1 M-1 M-5 M-4 Accelerated weathering 5 5 5 3 2 Wear resistance 5 5 5 4 3 High pressure car wash 5 5 5 2 3 Low temperature flexibility 5 5 5 3 2 Low temperature impact 5 5 5 2 3 Painting workability 5 4 5 3 4

3 is a photograph showing the results of the adhesion test performed on the coating specimen prepared in Example 2. Referring to FIG. 3, it can be seen that the coating film specimen of Example 2 does not exhibit a peeling phenomenon of the coating film and has excellent adhesion.

Referring to Tables 2 and 3, in the Example, after the bumper physical property, water resistance, excellent effects in the occurrence and adhesion of external blisters can be seen, whereas in the case of the Comparative Example, the poor initial adhesion was not overcome, and the coating film It can be seen that the gloss loss of the top coat clear layer is caused by the Tacky phenomenon.

Accordingly, as a result of the above experiment, it can be confirmed that all physical properties, such as coating workability, adhesion, acid resistance, alkali resistance, water resistance, and accelerated weather resistance, are excellent when using the aqueous coating composition for a base coat according to the present invention.

10: vehicle parts substrate 12: primer coating layer
20: base coating layer 22: base coating layer
30: clear coating layer 100: vehicle parts
200: bumper

Claims (9)

64 to 66% by weight of deionized water,
5 to 15% by weight of non-halogenated polyolefin resin,
5 to 15% by weight of polyurethane dispersion,
5 to 15% by weight of a hydrocarbon-based solvent,
Pigment 3-10% by weight,
It contains 0.5 to 3% by weight of additives,
The non-halogenated polyolefin is characterized in that it is a polyolefin modified with at least one of maleic acid and maleic anhydride,
The deionized water is characterized in that it maintains the adhesion of the aqueous coating composition for the base coat,
The hydrocarbon-based solvent is an aromatic hydrocarbon-based solvent, characterized in that it contains any one or more of benzene, toluene, and xylene,
Water-based coating composition for base coat.
The aqueous coating composition for a base coat according to claim 1, wherein the non-halogenated polyolefin resin has a weight average molecular weight of 80,000 to 150,000 g/mol.
The aqueous coating composition for a base coat according to claim 1, further comprising 0.1 to 3% by weight of a thickener based on the total weight of the aqueous coating composition for the base coat.
Forming a base coating layer by applying the water-based coating composition for a base coat according to any one of claims 1 to 3 to the surface of a substrate for vehicle parts;
Forming a clear coating layer on the surface of the formed base coating layer; And
Baking the formed base coating layer and the clear coating layer;
Vehicle parts coating method comprising a.
The vehicle component painting method according to claim 4, further comprising: subjecting the surface of the vehicle component substrate to a plasma treatment before applying the water-based coating composition for the base coat.
The method of claim 4, wherein the baking is performed at 70 to 100°C.
Substrates for vehicle parts;
A base coating layer formed on the surface of the vehicle component substrate; And
Includes; a clear coating layer formed on the surface of the base coating layer,
The vehicle component, characterized in that the base coating layer is formed from the aqueous coating composition for a base coat according to any one of claims 1 to 3.
The vehicle component according to claim 7, wherein the base coating layer has a thickness of 15 to 30 μm, and the clear coating layer has a thickness of 25 to 40 μm.
The vehicle component according to claim 7, wherein the vehicle component base material is a bumper, a side seal molding, a side garnish, or a side protector.

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