KR100993460B1 - High gloss high solid uv curable coating composition for color coating and process for coating plastic substrates using same - Google Patents

Abstract

The present invention relates to a high solid UV curable coating composition for high gloss color coating, comprising a high viscosity polyfunctional UV curable oligomer, UV curable monomer, inorganic or organic pigment, organic solvent and photoinitiator for high gloss process shortened color coating The high solid UV curable coating composition includes 0.5 to 30 parts by weight of the pigment and 10 parts by weight or less of an organic solvent based on 100 parts by weight of the total composition, and can be spray-coated and realize color with a single coating, and high gloss. It is eco-friendly and can be dried at room temperature by minimizing the volatile substances generated during painting, and there is no material deformation due to organic solvent and temperature, and it is excellent in workability and physical properties, so it is used for high-end products such as mobile phones, automobiles, and home appliances. It can be usefully used as a coating liquid for plastics.

Description

HIGH GLOSS HIGH SOLID UV CURABLE COATING COMPOSITION FOR COLOR COATING AND PROCESS FOR COATING PLASTIC SUBSTRATES USING SAME}

The present invention relates to a high-solid color UV-curable paint for high gloss color coating and a coating method of a plastic substrate using the same, and in particular, the color can be implemented in one painting process, so that the process can be shortened, environmentally friendly and spray coating is possible. It is related with this outstanding high gloss color coating high solid UV curing coating composition.

Due to the rapid industrialization, the global environment is rapidly deteriorating such as air and water pollution, ozone layer destruction, global warming, etc. It is actively underway.

Particularly, in the air pollution part, an eco-friendly paint system that minimizes the use of volatile organic compounds (VOCs) is required. Representative systems include powder coating systems and water born coating systems. system, UV curable coating system, high solid coating system, etc. Among them, UV curable coating system has been recognized as a representative eco-friendly system that is already commercialized.

However, the conventional UV curable coating system was initially designed not to use an organic solvent, but is now spray coating, dip coating, flow coating, and spin coating. According to the painting method, a large amount of organic solvent is used, and although this has caused air pollution and adversely affected the health of workers, it must be used for workability and appearance quality. Among them, plastic coatings such as automobiles and mobile phones mostly use spray coating methods, but until now, coating has been carried out using a coating composition containing 45 to 60% by weight of a solvent.

As described above, the conventional UV-curable coating paints use a large amount of volatile organic solvents for coating, which causes air pollution and industrial accidents, deformation of plastic materials, and securing a drying line due to the use of a large amount of organic solvents. Since it causes a problem of energy waste, it is urgent to develop an eco-friendly paint that reduces the concentration of volatile organic solvents.

In general, UV curable paints play an important role in the formation of a coating film, and when particles such as pigments are included in the paint, the UV absorber scatters and scatters ultraviolet rays depending on the color and optical characteristics of the coating film, thereby affecting the UV curing of the coating film. Crazy For this reason, the existing coating process is divided into a top coat process for realizing color and a top coat process using a top coat to protect the top coat, and at present, UV-curable paints containing pigments are only partially used. It is limited to.

Especially in the case of UV-curable paints containing pigments containing small amounts of organic solvents, most of them are limited to high viscosity applications such as silkscreen printing, and inkjet in the case of low-viscosity UV-curable paints containing small amounts of organic solvents. It is used in the field of printing ink for printing, but in the case of blue, red, and yellow in color, the color of pigment in the case of using carbon black for dark color such as black Due to the absorption, the uncured UV curable ink has poor physical properties, so the amount of carbon black used does not exceed 2.5 parts by weight based on 100 parts by weight of the UV curable ink. The product is limited by the use of. In addition, in the case of low-viscosity UV-curable inks including some of these pigments, spray coating is impossible due to poor physical properties and high viscosity for use as a paint for plastics.

In addition, in the case of high-solid paint is difficult to spray and difficult to wetting and leveling on the material, it is difficult to form a thin and flat coating, low gloss, and in the case of toning, there is a problem in curing the film in dark colors.

In addition, in the case of the conventional color coating paint for plastic spray coating is advantageous in the repaintability and color variety compared to the UV-curable paint, a large amount of 50 to 80% by weight for spray coating because of the use of a high molecular weight resin It requires an organic solvent, and the heat-drying paint is poor in physical properties compared to the curable paint.

Accordingly, an object of the present invention is to achieve a color reduction and dark colors in the high-solid paint that was previously a problem while reducing the process to a single coating process in which the coating process is performed in two stages to realize the color when spraying the existing spray High solid UV curable paint composition for short-time color coating and high gloss process with high physical properties such as high gloss, workability, adhesion, pencil hardness, abrasion resistance, chemical resistance, moisture resistance, acid resistance, etc. It is to provide a coating method of a plastic substrate using the same.

In order to achieve the above object, in the present invention, with respect to 100 parts by weight of the total composition, as a reactive acrylate having an average of 4 to 16 functional groups in the molecule in the molecule, the polyfunctional UV-curable type having a viscosity at room temperature in the range of 300 to 20,000 cps 20 to 70 parts by weight of oligomer; 10 to 60 parts by weight of the ultraviolet curable monomer as a diluent; 0.5 to 30 parts by weight of pigment; 5 to 10 parts by weight of an organic solvent; And it provides a high-solid UV curable coating composition for high gloss color coating, comprising 2 to 12 parts by weight of the photoinitiator.

The present invention also provides a method for painting a plastic substrate, comprising applying the coating composition to a plastic substrate once by spray coating.

High solid UV curable paints for high gloss process shortening color coating according to the present invention are not only environmentally friendly paints that can be spray-coated and use dry conditions at room temperature even when using organic solvents in an amount suitable for environmental standards of volatile organic compounds. As a paint which can have a large amount of black pigment, which is difficult to manufacture in an ultraviolet curable paint, in particular, it is divided into a coating process of a paint for realizing a conventional color and a coating process of a paint for reporting a paint film. High-quality products such as mobile phones, automobiles, and home appliances are provided by providing a coating film with excellent physical properties such as color realization, high gloss and adhesion, pencil hardness, abrasion resistance, chemical resistance, moisture resistance, and acid resistance in one coating process. Very advantageously.

The high solid UV curable coating composition for high gloss process shortening color coating according to the present invention comprises 0.5 to 30 parts by weight of a pigment component, and 10 parts by weight or less of a volatile organic solvent based on 100 parts by weight of the total composition. It is characterized by possible and excellent physical properties.

The high-solid UV curable paint for high gloss process shortening color coating of the present invention includes, as essential components, a low-viscosity polyfunctional UV curable oligomer, an ultraviolet curable monomer, an inorganic and organic pigment, an organic solvent, and a photoinitiator.

The low viscosity polyfunctional UV curable oligomer used in the composition of the present invention contains reactive acrylates having 4 to 16 functional groups in the molecule, and has a viscosity at room temperature of 300 to 20,000 cps in consideration of the final workability of the paint. Preference is given to low viscosity acrylates. Specific examples thereof include low molecular weight acrylates such as dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol tri- or tetraacrylate, and ditrimethylolpropane tetraacrylate, and room temperature synthesized by a conventional method. Polyurethane acrylates, polyester acrylates, etc. whose viscosity in the range of 300-20,000 cps are mentioned. In the present invention, a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate or a low viscosity polyfunctional ultraviolet curable oligomer prepared by a conventional method may be used, and in consideration of the preparation of the pigment dispersion and the workability of the final paint. It is preferable to use at least one oligomer simultaneously.

In the present invention, the low viscosity oligomer is used in an amount of 20 to 70 parts by weight, preferably 30 to 60 parts by weight based on 100 parts by weight of the total composition. At this time, when the amount of the low-viscosity polyfunctional oligomer is greater than 70 parts by weight, the crosslinking density of the cured coating film is too high, the coating film is easily broken, cracks are generated by heat or impact, and when less than 20 parts by weight, mechanical properties such as hardness and wear Physical properties are lowered.

In addition, the UV-curable monomer used as a reactive diluent for controlling the viscosity of the oligomer in the present invention, pentaerythritol tri- or tetraacrylate (PETA), ditrimethylolpropane tetraacylate (DI) TMPTA), trimethylolpropane triacrylate (TMPTA), hexamethylene diacrylate (HDDA), hydroxyethyl acrylate (HEA), hydroxypropyl acrylate HPA), hydroxybutyl acrylate (HBA), isobonyl acrylate (IBOA), and the like.

The reactive diluent is used in an amount of 10 to 60 parts by weight, preferably 20 to 50 parts by weight based on 100 parts by weight of the total composition. At this time, when the amount of the monomer is more than 60 parts by weight, the viscosity is lowered, which is not only impossible to form a desirable coating film due to the shape flowing on the material, but also the curing speed is lowered, mechanical / chemical properties are lowered, and the viscosity of the paint is less than 10 parts by weight. Not only does this make spraying impossible, it also reduces workability and leveling, and poor compatibility due to poor dilution.

In the present invention, in order to impart various colors to the paint, the surface-treated and / or untreated inorganic or organic pigments, or mixtures thereof are 0.5 to 30 parts by weight, preferably 2 to 25 parts by weight, based on 100 parts by weight of the total composition. It can be used in negative amounts.

The surface-treated inorganic or organic pigment is a type that is dissolved in a solvent and is mainly coated with a vinyl resin. At this time, the coating resins of the pigment include vinyl and acrylic (acryl), cellulose acetate butylate (CAB) resin, and the like, by selecting a solvent according to the solubility in the solvent of the resin to disperse the pigment in the solvent To the paint in the form of a prepared dispersion. For example, in the case of a pigment coated with a vinyl resin can be used mainly dissolved in a solvent of ketones.

In addition, in the case of the inorganic pigment untreated surface can be used through a separate dispersion process.

As the inorganic pigment treated with the black surface usable / untreated according to the present invention, carbon black having a particle size of 5 to 100 nm is preferable, and both surface oxidation treatment and untreated carbon black can be used. The black inorganic pigment may be used in an amount of 0.5 to 30 parts by weight, preferably 1 to 30 parts by weight based on 100 parts by weight of the total coating composition, and may be used in an amount of 0.5 to 20 parts by weight when no concealment is required. . In this case, when the amount of the inorganic pigment exceeds 30 parts by weight, the hiding power is excellent, but the coating film having excellent physical properties cannot be formed due to the hardening of the coating film.

In addition, the surface-treated and untreated white inorganic pigment that can be used in the present invention is preferably titanium dioxide series (TiO ₂ ), depending on the particle size and whiteness (for example, DuPont R-700, R- 706, R-902, R-960 and the like can be used, and 5 to 30 parts by weight, preferably 10 to 25 parts by weight, based on 100 parts by weight of the total coating composition. In this case, when the amount of the white inorganic pigment is less than 5 parts by weight, the degree of curing and coating properties is excellent, but the hiding power is low, so that it is impossible to use a white paint alone. The physical properties of are lowered.

In the present invention, the surface of phthalocyanine, indanthrone, anthraquinone carbazole, perylene, isoindolinone, monoazo naphthol, rhodamine, indigoid dioxazine, tetrachloroisoindolinone, anthra pyrimidine and the like This treated / untreated colored organic pigment may be used in an amount of 3 to 30 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the total coating composition, wherein the organic pigments depend on the substituents connected to the main chain of the compound. There may be a difference in the color and a joke of the.

Specifically, pigments with all surfaces treated with a pigment index such as pigment blue, pigment brown, pigment green, pigment yellow, pigment orange, pigment red, and pigment violet are treated / untreated. Materials can be used as the colored organic pigment of the present invention.

Organic solvents usable in the present invention are methylisobutyl ketone, methylethyl ketone, dimethyl ketone, isopropyl alcohol, isobutyl alcohol, normal Butyl alcohol, ethyl acetate, normal butyl acetate, ethyl cellusolve, butyl cellusolve, toluene, xylene And the like, and may be used in an amount of 5 to 10 parts by weight, preferably 7 to 10 parts by weight based on 100 parts by weight of the total composition. In this case, when the amount of the organic solvent used is more than 10 parts by weight, it is in violation of the volatile organic compound regulation, and when it is less than 5 parts by weight, the compatibility is poor due to the insufficient dilution power, and the phenomenon of spraying occurs, resulting in deterioration of spray workability. .

The composition of the present invention includes a conventional photoinitiator that serves to form radicals by ultraviolet light and to crosslink unsaturated hydrocarbons present in the coating solution, specific examples of which include 2-hydroxy- from Ciba Specialty Chemicals. 1-4- [4- (2-hydroxy-2-methylpropionyl) -benzyl] phenyl-2-2-methyl propane-1-one (Irgacure 127), 1-hydroxy cyclohexyl phenyl ketone (Irgacure 184 ), 2-benzyl-2- (dimethylamino) -1- [4- (4-morpholinyl) phenyl] -1-butanone (Irgacure 369), bis (2,4,6-trimethyl benzoyl) Phenyl phosphine oxide (Irgacure 819), 2,4,6-trimethyl benzoyl diphenyl phosphine (TPO), 2-hydroxy-2-methyl-1-phenyl-1-propane (Darocur 1173), benzophenone ( BP) and the like, and may be used in an amount of 2 to 12 parts by weight, preferably 3 to 8 parts by weight, based on 100 parts by weight of the total composition, and a low viscosity polyfunctional ultraviolet ray light. To control, depending on the pigment used and the amount of oligomer-type ultraviolet-curable monomer is preferred. At this time, if the amount of the photoinitiator used is more than 12 parts by weight, the molecular weight of the resin in the coating film is shortened, the coating film is broken, less than 2 parts by weight does not obtain the desired coating properties or uncured phenomenon occurs.

In addition, the present invention further includes, as other additives, a conventional pigment wet dispersant that serves to enhance the dispersibility of the pigment and the shelf life of the paint, and specific examples thereof include SOLSPERES ™, Ciba Specialty, manufactured by Noveon. EFKA ™ from Chemicals, BYK ™ from BYK Chemie, and mixtures thereof, and may be used in an amount of 0 to 4 parts by weight, preferably 0 to 3 parts by weight, based on 100 parts by weight of the total composition. It is preferable to adjust according to the type and color of the pigment used. At this time, when the amount of the pigment wet dispersant used is greater than 4 parts by weight, it may affect the upper layer of the coating film in which the excess pigment wet dispersant is formed, thereby deteriorating the physical properties and repainting properties of the coating film.

In addition, depending on the viscosity, liquid state, spray workability and the degree of film formation of the paint, a conventional leveling agent usable for the coating composition, preferably a polysiloxane-based leveling agent, for example BYK-300, BYK-333, BYK -310 (BYK Chemi Co.), and a humectant or the like can be used in an amount of 0 to 2 parts by weight based on 100 parts by weight of the total composition.

The composition according to the invention can be prepared by conventional methods of preparing paints, and in particular, some of the low viscosity polyfunctional UV curable oligomers, UV curable monomers, surface treated and untreated inorganic and organic pigments, and pigment wetting dispersants. It can be prepared by dispersing the pigment by mixing, and then mixing the remaining amount of the low viscosity polyfunctional UV curable oligomer and ultraviolet monomer, organic solvent, photoinitiator, and other additives in the pigment dispersion.

For example, 10 to 30 parts by weight of a low-viscosity polyfunctional UV curable oligomer, 10 to 50 parts by weight of ultraviolet curable monomer, 0.5 to 30 parts by weight of untreated inorganic and organic pigments, and a pigment wet dispersant based on 100 parts by weight of the total composition. After mixing 0 to 4 parts by weight, a pigment dispersion including particles having a diameter of 5 μm or less is prepared by using a conventional dispersion equipment. At this time, the pigment dispersion is changed in proportion depending on the pigment added to obtain the desired color. Then, in the pigment dispersion for each color, 10 to 60 parts by weight of the same or different types of low-viscosity polyfunctional UV curable oligomers, 0 to 50 parts by weight of the UV curable monomer, 5 to 10 parts by weight of the organic solvent, and 1 to 2 types After the addition of 2 to 12 parts by weight of the photoinitiator and 0 to 2 parts by weight of the additive, a high-solid UV curable coating material for color coating can be prepared by stirring.

For surface treated inorganic and organic pigments, a solvent of ketones, preferably methyl isobutyl ketone, is used in an amount of 50 to 99 parts by weight based on 100 parts by weight of the total composition, and the surface-treated inorganic and organic pigments are 1 Stirring is carried out to from 50 parts by weight. The dispersion thus obtained is 5 to 30 parts by weight, 10 to 30 parts by weight of a low viscosity polyfunctional UV curable oligomer, 10 to 50 parts by weight of an ultraviolet curable monomer, homogeneous or heterogeneous low viscosity polyfunctional UV based on 100 parts by weight of the total composition. 10 to 60 parts by weight of a curable oligomer, 0 to 50 parts by weight of an ultraviolet curable monomer, 2 to 12 parts by weight of one or two kinds of photoinitiators and 0 to 2 parts by weight of an additive are added, followed by stirring to obtain a high solid UV curable paint for color coating. It can manufacture.

The coating composition according to the present invention may implement a color by spray coating on various substrates, preferably plastic substrates such as mobile phones, automobiles, home appliances, etc., and may form a coating film having high gloss and excellent physical properties. The thickness of the coating film may range from 15 to 30 μm.

The coating film may be formed by applying the coating composition according to the present invention on a substrate, and then drying at room temperature for 1 to 5 minutes, followed by curing with ultraviolet rays.

The composition according to the present invention can be spray-painted by using only 10 parts by weight or less of an organic solvent based on 100 parts by weight of the total composition, and is fast to dry at room temperature, and has a low volatile organic component (VOC) content. In particular, as a paint which can use a large amount of black pigment, which is difficult to manufacture in an ultraviolet curable paint, it is highly glossy and can form a coating film having excellent physical properties such as adhesion, pencil hardness, abrasion resistance, chemical resistance, moisture resistance, and acid resistance. It is useful for coating high quality products such as mobile phones, automobiles, and home appliances, especially undercoat.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the invention only.

Production Example  One : Low viscosity Multifunctional  UV curable Oligomer  Produce

In a four-necked flask equipped with a thermometer, a condenser, a dropping vessel, and a stirrer, 500 g of a pentaerythritol tetraacrylate and pentaerythritol triacrylate mixture having a pentaerythritol triacrylate ratio of 55 to 60% by weight was added thereto. 200 ppm of p -methoxy phenol were added. The resulting mixture was stirred at room temperature for about 30 minutes, after which 100 ppm of dibutyltindilaurylate was added as a catalyst, and then the temperature was raised to about 70 ° C to give 1,6-hexamethylene diisocyanate trimer (TKA-100P, 1 equivalent of Asahi Kasei, Japan) was added dropwise and allowed to react for 5 hours. After confirming that the isocyanate (NCO) peak disappeared from the reaction product by infrared spectrophotometry (IR), it was cooled to 50 ° C, and then methyl isobutyl ketone, a diluting solvent, was added to 10 parts by weight based on 100 parts by weight of the total reaction solution. By adding, a low viscosity polyfunctional ultraviolet curable oligomer having a viscosity of 13,000 cps was prepared.

<UV Hardening  Preparation of Paint Composition>

Example  One

10 parts by weight of the low-viscosity polyfunctional UV curable oligomer obtained in Preparation Example 1, 26 parts by weight of hydroxybutyl acrylate as an ultraviolet curing monomer and 3 parts by weight of carbon black MA-100 (Mitsubishi, Japan) as a black inorganic pigment 20.68 parts by weight of a low-viscosity polyfunctional UV curable oligomer obtained in Preparation Example 1, 8.54 parts by weight of hexamethylene diacrylate as an ultraviolet curable monomer after the black pigment dispersion was prepared by adding to a type disperser (ball mill or basket mill) and mixing. And 17.28 parts by weight of hydroxy butyl acrylate, 4 parts by weight of toluene and 4 parts by weight of methyl isobutyl ketone as organic solvents, and 4.5 parts by weight of Irgacure 369 (Ciba Specialty Chemicals) as photoinitiator (Darocur) 1173 (Ciba Specialty Chemicals) added 2 parts by weight and stirred for 30 minutes, To prepare a UV-curable black lead paint

Example  2

2.5 parts by weight of the surface-treated black pigment (SCP-BLACK 7982, Ilsam Korea) and 7.9 parts by weight of methyl isobutyl ketone as an organic solvent were first stirred to confirm that the pigment was dissolved, and then the low-viscosity polyfunctional ultraviolet ray obtained in Preparation Example 1 above. 21 parts by weight of curable oligomer, 15 parts by weight of ditrimethylolpropane tetraacrylate (DI-TMPTA), 17.1 parts by weight of trimethylolpropane triacrylate (TMPTA), 16.5 parts by weight of hexamethylene diacrylate (HDDA), isobo 9.5 parts by weight of Nyl acrylate (IBOA), 5 parts by weight of Irgacure 184 (Ciba Specialty Chemicals) and 5 parts by weight of Irgacure 819 (Ciba Specialty Chemicals) and 0.5 parts by weight of leveling agent were stirred for 30 minutes , High Solid UV Curable Black Paint was prepared. In the case of the black paint thus prepared, the solvent content is 10 parts by weight, which is the sum of 2.1 parts by weight, which is 10% in 21 parts by weight of the low-viscosity polyfunctional UV curable oligomer, and 7.9 parts by weight of methyl isobutyl ketone used in the manufacture of the paint. It will have 10 parts by weight based on 100 parts by weight.

Example  3

      50 parts by weight of the black paint of Example 1 and 50 parts by weight of the black paint of Example 2 were mixed to prepare a high solid UV curable black paint having a total weight of 100.

Example  4

2.5 parts by weight of the surface-treated white pigment (SCP-WHITE 3970, Ilsam Korea) and 7.9 parts by weight of methyl isobutyl ketone as an organic solvent were first stirred to confirm that the pigment was dissolved, and then the low-viscosity polyfunctional ultraviolet ray obtained in Preparation Example 1 above. 21 parts by weight of a curable oligomer, 17.1 parts by weight of ditrimethylolpropane tetraacrylate (DI-TMPTA) as a UV curable monomer, 15 parts by weight of trimethylolpropane triacrylate (TMPTA), 16.5 parts by weight of hexamethylene diacrylate (HDDA) Part 9.5 parts by weight of isobornyl acrylate (IBOA), 10 parts by weight of Irgacure 184 (Ciba Specialty Chemicals) as an initiator and 0.5 parts by weight of a leveling agent were added and stirred for 30 minutes to prepare a high solid UV curable white paint. It was.

In the case of the white paint thus prepared, the solvent content is 10 parts by weight, which is 10 parts by weight of 2.1 parts by weight, which is 10% in 21 parts by weight of the low-viscosity polyfunctional UV-curable oligomer, and 7.9 parts by weight of methyl isobutyl ketone, which is used to prepare the paint. It will have 10 parts by weight based on 100 parts by weight.

Comparative example  One

15 parts by weight of acrylic resin (Dianal BR-73, Mitsubishi, Japan), 15 parts by weight of vinyl resin (Ucar-VMCH, Union Carbide) based on the universal composition of UV-curable undercoat paints currently commercially available 30 parts by weight of toluene and 36.4 parts by weight of methyl isobutyl ketone were added to the vessel as a solvent, followed by stirring at 50 ° C to completely dissolve the resin. 3 parts by weight of carbon black MA-100 (Mitsubishi, Japan) and 0.6 parts by weight of pigment wetting dispersant BYK-142 (BYK-Kemi) as a black inorganic pigment were added to the dissolved resin, followed by mixing. To prepare an ultraviolet curable black paint containing 66.4 parts by weight.

Comparative example  2

12 parts by weight of acrylic resin (Dianal BR-73, Mitsubishi, Japan), 12 parts by weight of vinyl resin (Ucar-VMCH, Union Carbide), 20 parts by weight of toluene as organic solvent, 35.3 parts by weight of methyl isobutyl ketone, white inorganic A UV curable white coating material containing an organic solvent in an amount of 55.3 parts by weight was prepared in the same manner as in Comparative Example 1, except that 20 parts by weight of titanium dioxide R-706 and 0.7 parts by weight of a pigment wet dispersant were used.

< Top coat  Manufacturing of Paints>

Comparative example  3

Based on the universal composition of the UV-curable paint that is currently commercialized, a top coat for repaintability experiment was prepared as follows.

First, 15 parts by weight of urethane acrylate oligomer (EBECRYL 1290, UCB, Belgium), 11 parts by weight of urethane acrylate oligomer (EBECRYL 9260, UCB, Belgium), 6 parts by weight of trimethylolpropane triacrylate, hexamethylenediol di 7 parts by weight of acrylate, 30 parts by weight of toluene, 15 parts by weight of methyl isobutyl ketone, 5 parts by weight of ethyl acetate and 5 parts by weight of ethyl cellulsolve were added, and the mixture was stirred. 5 parts by weight of Darocur 1173 (Ciba Specialty Chemicals Co., Ltd.) and 1 part by weight of leveling agent were added thereto, followed by stirring for 30 minutes to prepare a UV-curable top coat having a nonvolatile content of 45%.

<Manufacture of coating film>

Example  5 to 8

After spray coating the high-solvent UV curable paint for short coat color coating prepared in each of the above Examples 1 to 4 onto a polycarbonate material, at room temperature (25 ° C.) to remove trace organic solvents. After drying for ˜2 minutes, using an fusion lamp (Fusion Lamp, Fusion System), 15 to 30 ㎛ by ultraviolet curing three times under the curing conditions of line speed (line speed) 10 m / min, light quantity 300 mJ / ㎠ Color ultraviolet curable coating film was prepared.

Comparative example  4 & 5

The UV curable paints prepared according to Comparative Examples 1 and 2, respectively, were mixed with a paint and a diluting solvent in a ratio of 3: 4, and spray-coated on a polycarbonate material, such as a method used in general spray coating, and then a large amount of organic In order to remove the solvent it was dried for 5 to 10 minutes at 60 ℃ to prepare a coating film.

Comparative example  6 & 7: Preparation of Top Coating

After spray-coating the UV curable top coat prepared in Comparative Example 3 on the undercoats prepared in Comparative Examples 4 and 5, dried at 60 ° C. for 4 to 5 minutes, and then using a fusion lamp, a line speed of 10 m / min., UV curing 2 times under the curing conditions of the light amount of 300 mJ / ㎠ to prepare a top coat of 18 to 20 ㎛.

Test Example  1: used Organic solvent amount  compare

The components of the coating composition used in the preparation of the undercoat according to Examples 5 to 8 and Comparative Examples 4 and 5 are shown in Table 1 below.

As shown in Table 1, it can be seen that the high solid UV curable coating composition according to the present invention contains 10 parts by weight or less of an organic solvent based on 100 parts by weight of the composition during spray coating.

Test Example  2: volatile organic solvent ( VOC ) Generation Comparison

Using the paint of Example 2 and Comparative Example 2 by comparing the amount of volatile organic solvent generated when spraying 1 million mobile phone materials are shown in Table 2 below.

As shown in Table 2, the high solid UV curable coating composition according to the present invention can be coated in a small amount compared to the composition of the comparative example with a high content of an organic solvent, and economically, since the generation of VOC is significantly less, it is very environmentally friendly. to be.

Test Example  3: property evaluation

The physical and chemical properties of the high gloss process shortened color coated high solid UV curable coating film obtained in Examples 5 to 8, the undercoat film obtained in Comparative Examples 4 and 5, and the top coat film obtained in Comparative Examples 6 and 7, were respectively measured. It is shown in Tables 3 and 4, the measurement method and evaluation criteria of the physical properties are as follows:

(1) gloss

A glossmeter (BYK Gardener glossmeter) is closely adhered to the cured and dried coating film, and the gloss at an angle of 60 degrees is measured.

(2) Adhesiveness: ASTM D3359 Evaluation by -87

To reach the material at intervals of 1 mm, the hardened transparent coating film was cut with 11 lines on each side horizontally and vertically, and 100 cells of 1 mm x 1 mm were made. Remove to close to the angle of °. This is repeated three times at the same location, where the criteria for determining adhesion are as follows:

   5B: There is no coating film fall off of the cut edge and no coating film peeling in the lattice.

   4B: Deterioration of the edge is weakly observed and peeling occurs within 5% of the total.

   3B: Peeling and chipping of corners are observed and peeled off within 15%.

   2B: Even within the lattice, peeling and chipping are observed and peeled off within 35%.

   1B: A large ribbon peeling is observed and 35% to 65% peeling.

   0B: Peeled at an area of 65% or more and poor adhesion.

(3) pencil hardness: ASTM D3363 Evaluation by -74

If the pencil is placed on the plane of the coated specimen at a 45 ° angle and pushed with a 1 kg load, and the scraping pattern or crushing of the coating film does not occur more than two times when measuring five times, the hardness value of the pencil is the surface hardness value.

(4) Hot water resistance

The coated specimen is left at room temperature for 24 hours, then heated in 100 ° C. for 30 minutes, then dried with a cloth and left at room temperature for 2 hours to achieve appearance and adhesion according to ASTM D3359-87. . At this time, evaluation criteria are the same as the said adhesive test.

(5) wear resistance

An industrial eraser with a load of 500 g on the surface of the coating film was rubbed at a rate of 40 times / min to visually check the exposure point of the material.

(6) chemical resistance

The exposure time of the material is visually confirmed by rubbing at a rate of 40 times / min while sufficiently moistening methyl alcohol (99.3%) on an industrial eraser loaded with 500 g on the surface of the coating film.

(7) moisture resistance

The coated specimens were left for 72 hours under a constant temperature and humidity condition of 50 ° C. and 95% humidity, and then tested for appearance deformation and adhesion.

(8) Acid resistance

The specimens coated in a standard solution of pH 4.6 are immersed for 72 hours and then subjected to appearance deformation and adhesion.

As shown in Tables 3 and 4, the high-solid UV curable coating composition according to the present invention has less deformation during UV curing compared to the composition of Comparative Example having a high content of an organic solvent, but also has pencil hardness, hot water resistance, abrasion resistance, and chemical resistance. It is possible to provide a coating film having excellent physical properties such as acid resistance, and also to implement a color through a single coating process, a two-step process consisting of a top coat coating method for realizing a color through the existing undercoat and protecting the undercoat. And a high gloss and excellent coating film can be provided.

Claims (10)

Reactive acrylate having 4 to 16 functional groups in the molecule, based on 100 parts by weight of the total composition, 20 to 35 parts by weight of a polyfunctional ultraviolet curable oligomer having a viscosity at room temperature in the range of 300 to 20,000 cps; 34 to 60 parts by weight of the ultraviolet curable monomer as a diluent; 0.5 to 30 parts by weight of pigment; 5 to 10 parts by weight of an organic solvent; And 2 to 12 parts by weight of photoinitiator, At this time, the ultraviolet curable oligomer and the ultraviolet curable monomer, characterized in that it comprises in an amount satisfying the weight ratio of 1: 1.69 to 2.77 in the content range, respectively, High solid UV curable coating composition for high gloss color coating and spray coating. The method of claim 1, Polyfunctional UV-curable oligomers in the group consisting of dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol tri- or tetraacrylate, ditrimethylolpropane tetraacrylate, polyurethane acrylate and polyester acrylate At least one selected. The method of claim 1, UV curable monomers include pentaerythritol tri- or tetraacrylate (PETA), ditrimethylolpropane tetraacrylate (DI-TMPTA), trimethylolpropane triacrylate (TMPTA), hexamethylene diacrylate (HDDA) At least one selected from the group consisting of hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), hydroxybutyl acrylate (HBA) and isobornyl acrylate (IBOA). The method of claim 1, Wherein the pigment is carbon black having a particle size of 5 to 100 nm as a surface treated or untreated black inorganic pigment. The method of claim 1, The pigment is a surface-treated or untreated white inorganic pigment, titanium dioxide series (TiO ₂ ), characterized in that contained in 5 to 30 parts by weight based on 100 parts by weight of the total coating composition. The method of claim 1, Colored organic pigments, surface-treated or untreated, as phthalocyanine, indanthrone, anthraquinone carbazole, perylene, isoindolinone, monoazo naphthol, rhodamine, indigoid dioxazine, tetrachloroisoindolinone and anthrapyri At least one selected from the group consisting of midine, and the composition, characterized in that it comprises 3 to 30 parts by weight with respect to 100 parts by weight of the total coating composition. The method of claim 1, The organic solvent is methylisobutyl ketone, methylethyl ketone, dimethyl ketone, isopropyl alcohol, isobutyl alcohol, normal butyl alcohol selected from the group consisting of alcohol, ethyl acetate, normal butyl acetate, ethyl cellusolve, butyl cellusolve, toluene and xylene At least one composition. A coating method of a plastic substrate, comprising applying the coating composition according to any one of claims 1 to 7 to a plastic substrate by spray coating. Products coated by the method according to claim 8. The method of claim 9, A product characterized by being a mobile phone, a car or a home appliance.