KR101406847B1 - Coating method of plastics or metal substrate and coated plastics or metal body obtained thereby - Google Patents

Abstract

Forming a primer layer on the plastic or metal substrate; Forming a light reflectance control layer including an aluminum oxide layer and a titanium oxide layer on the undercoat layer; Forming a protective layer including aluminum oxide or silicon carbide on the light reflectance adjusting layer; And forming a friction reducing layer comprising a metal fluoride on the protective layer, wherein the step of forming the light reflectance control layer, forming the protective layer, and forming the friction reducing layer are the same There is provided a method of coating a plastic or metal substrate by a continuous deposition process under a pressure lower than atmospheric pressure in a chamber, and a high-quality plastic or metal coating obtained thereby. Accordingly, the mass production of a plastic or metal coating material that can be used as a case of a mobile phone such as a smart phone can drastically shorten the process and greatly improve the product quality and the production yield.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a plastic or metal substrate and a plastic or metal coating obtained by the method.

The present invention relates to a method of coating a plastic or metal substrate and a plastic or metal coating obtained thereby. More specifically, the present invention can be used in a large-scale production of a plastic or metal coating material which can be used, for example, as a case of various small electronic apparatuses such as a feature phone, a smart phone and a tablet personal computer A plastic or metal-based coating method capable of shortening the process and greatly improving the product quality and the production yield, and a high-quality plastic or metal coating body obtained thereby.

In the field of mobile phone technologies such as smart phones, the use of touch screens has made full use of the expression of the appearance of mobile phones toward the mobile phone case. Accordingly, a multi-layered coating composed of a plurality of layers exhibiting respective functions is formed on a plastic or metal cellular phone case, thereby realizing a beauty of colors, textures and the like that can not be realized by coating only the paint. However, in order to form multiple layers on a plastic or metal cell phone case, a number of processes must be performed. However, as the number of processes increases, the problem of increased production costs due to an increase in defective products . As described above, by using the method of manufacturing a plastic or metal cell phone case by multilayer coating widely adopted in the technical field, it is difficult to cope with the demands of the market in a timely manner by mass-producing a high quality cell phone case economically.

1 is a flow chart for explaining a process for forming a multilayer coating comprising a plurality of layers on a plastic or metal cellular phone case according to a conventional method.

Referring to FIG. 1, a first primer layer is formed (S1 ') on a plastic or metal cell phone case manufactured by an injection process. To this end, a primer layer composition is usually applied onto a plastic or metal cellular phone case by spraying and dried and / or irradiated with ultraviolet rays to form a first primer layer. Subsequently, a primer layer is formed on the first primer layer (S2 '). To this end, a primer layer composition is usually applied onto the first primer layer by spraying and irradiated with ultraviolet light to cure the primer layer composition to form a primer layer. The first primer layer is formed using a coating material having good affinity with a plastic or metal cellular phone case, and the primer layer is formed using an ultraviolet curing type coating material having high compatibility with the light reflectance controlling layer made of an inorganic material to be formed in a subsequent step . Subsequently, a light reflectance controlling layer is formed on the undercoating layer (S3 '). For this purpose, a silicon oxide layer and / or a titanium oxide layer or the like is formed by vacuum depositing silicon oxide and / or titanium oxide on the underlayer in a vacuum chamber. Next, a second primer layer is formed on the optical reflectance control layer (S4 '). The second primer layer is formed using a paint having good affinity with the light reflectance controlling layer made of a metal oxide. This step is basically the same as the first primer layer forming step. That is, the primer layer composition is usually applied onto the light reflectance controlling layer by spraying and dried and / or irradiated with ultraviolet rays to form the second primer layer. Subsequently, a middle layer is formed on the second primer layer (S5 '). To this end, the intermediate layer composition is usually applied by spraying onto the second primer layer and dried and / or irradiated with infrared light to form the intermediate layer. Finally, a top layer is formed on the intermediate layer (S6 '). To this end, the top layer composition is typically spray applied onto the middle layer and the top layer composition is cured by irradiation with ultraviolet light to form the top layer. The intermediate layer plays a role to strongly adhere the top layer to the light reflectance control layer together with the primer layer. The top layer is usually formed using a (meth) acrylate-based ultraviolet curing type coating material containing a slipping agent and having a chemical scratch resistance and a high abrasion resistance.

According to the conventional process of forming a multi-layer coating consisting of multiple layers on a plastic or metal cell phone case, as described above, the plastic or metal cell phone case must move at least five times into the area where each unit process is performed, The ultraviolet irradiation process must be performed to expose the following problems.

First, the conventional coating process increases the number of defective products through more than five processes, resulting in lowered production yield and increased production cost. In addition, since the ultraviolet ray irradiation process is excessive, the ultraviolet ray total exposure amount is excessively increased, so that the ultraviolet ray hardening type paint is not only excessively hardened but also receives a great deal of stress when moving between each unit process. As a result, when the mobile phone is moved or the battery is replaced, the mobile phone case is bent or the coating film is broken, and the yellowing of the coating film is likely to occur over time.

Due to such a problem, when the above-described conventional coating process is used, the manufacturing cost of the mobile phone increases, and the physical properties of the mobile phone case become weak. Therefore, it is difficult to cope with the demands of the market in a mass production of a high quality mobile phone case economically.

Also, in the above-described conventional mobile phone case coating process, all of the processes using the primer layer, undercoat layer, middle layer, and topcoat layer composition use a coating composition containing a large amount of volatile organic compounds.

Therefore, it is an object of the present invention to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a method of manufacturing a plastic or metal coating material, And a method of coating a plastic or metal base material capable of significantly improving the yield of production.

Another object of the present invention is to provide a plastic or metal coating obtained by the coating method of the plastic or metal substrate.

To achieve the above object, according to a first aspect of an aspect of the present invention,

Forming a primer layer on the plastic or metal substrate;

Forming a light reflectance control layer including an aluminum oxide layer and a titanium oxide layer on the undercoat layer;

Forming a protective layer including aluminum oxide or silicon carbide on the light reflectance adjusting layer; And

Forming a friction reducing layer comprising a metal fluoride on the protective layer,

The step of forming the light reflectance control layer, forming the protective layer, and forming the friction reducing layer may be performed by a continuous deposition process under a pressure lower than atmospheric pressure in the same chamber. Coating method is provided.

To achieve the above object, according to a second aspect of an aspect of the present invention,

Forming a primer layer on the plastic or metal substrate;

Forming a protective layer comprising aluminum oxide or silicon carbide on the undercoating layer;

Forming a light reflectance controlling layer including an aluminum oxide layer and a titanium oxide layer on the protective layer; And

Forming a friction-reducing layer comprising a metal fluoride on the light reflectance control layer,

The step of forming the protective layer, forming the light reflectance control layer, and forming the friction reducing layer may be performed by a continuous deposition process under a pressure lower than atmospheric pressure in the same chamber. Coating method is provided.

The metal fluoride may be at least one selected from the group consisting of LiF, MgF2, AlF3, CaF2, BaF2, CeF2, MnF2, FeF3, CoF2, NiF2, YF3, ThF4 and CuF.

The step of forming the undercoating layer comprises: 15 to 40 parts by weight of polymethylmethacrylate based on 100 parts by weight of the total composition; 10 to 30 parts by weight of a photopolymerizable (meth) acrylate oligomer having a number average molecular weight of 200 to 5,000 selected from polyurethane (meth) acrylate, polyester (meth) acrylate or mixtures thereof; Coating a photocurable coating composition comprising 10 to 30 parts by weight of a photocurable (meth) acrylate monomer, 20 to 60 parts by weight of a styrene monomer, and 1 to 10 parts by weight of a photoinitiator onto the plastic or metal substrate and photocuring . ≪ / RTI >

The photocurable coating composition may further comprise 5 to 20 parts by weight of an organic solvent.

The organic solvent is selected from the group consisting of methyl isobutyl ketone, methyl ethyl ketone, dimethyl ketone, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, ethyl acetate, n-butyl acetate, ethyl cellosolve, butyl cellosolve, toluene and xylene And may be at least one selected from the group consisting of

The deposition process may be an electron beam or a resistance heating vacuum deposition or a sputtering vacuum deposition.

According to a first aspect of another aspect of the present invention,

Plastic or metal substrates;

A primer layer formed on the plastic or metal substrate;

A light reflectance control layer comprising an aluminum oxide layer and a titanium oxide layer as a light reflectance controlling layer formed on the undercoating layer;

A protective layer comprising aluminum oxide or silicon carbide as a protective layer formed on the light reflectance controlling layer; And

There is provided a plastic or metal coating comprising a friction reducing layer comprising a metal fluoride as a friction reducing layer formed on the protective layer.

According to a second aspect of another aspect of the present invention, in order to achieve the other object,

Plastic or metal substrates;

A primer layer formed on the plastic or metal substrate;

A protective layer comprising aluminum oxide or silicon carbide as a protective layer formed on the undercoat layer;

A light reflectance adjusting layer including an aluminum oxide layer and a titanium oxide layer as a light reflectance controlling layer formed on the protective layer; And

There is provided a plastic or metal coating comprising a friction reducing layer comprising a metal fluoride as a friction reducing layer formed on the light reflectance control layer.

The metal fluoride may be at least one selected from the group consisting of LiF, MgF2, AlF3, CaF2, BaF2, CeF2, MnF2, FeF3, CoF2, NiF2, and CuF.

Wherein the undercoat layer comprises 15 to 40 parts by weight of polymethylmethacrylate based on 100 parts by weight of the total composition; 10 to 30 parts by weight of a photopolymerizable (meth) acrylate oligomer having a number average molecular weight of 200 to 5,000 selected from polyurethane (meth) acrylate, polyester (meth) acrylate or mixtures thereof; 10 to 30 parts by weight of a photocurable (meth) acrylate-based monomer and 20 to 60 parts by weight of a styrene monomer can be a cured product of the photocurable coating composition.

The plastic or metal coating may be a cellular phone case, a tablet PC case, a notebook PC case, or a PDA (personal digital assistant) case.

According to the multilayer coating method of the present invention, the conventional primer layer forming step and the undercoat layer forming step are performed by using the undercoat layer composition having a special chemical composition capable of taking charge of both the primer layer and the undercoating layer, It can be replaced by one step of the layer forming step. Also, the steps of forming the light reflectance control layer, forming the protective layer, and forming the friction reducing layer may be performed in a continuous deposition process in one and the same chamber without being performed at separate locations.

Therefore, the multi-layer coating method of the present invention comprises a wet process of spray coating and curing to form a sub-base layer, and a wet process of spray coating and curing to form a sub-base layer of a dry deposition process in which the light reflectance control layer, Step process so that a high-quality multi-layer coating can be simply formed on a plastic or metal cellular phone case. Therefore, according to the multilayer coating method of the present invention, productivity and yield can be greatly improved as compared with the conventional multilayer coating method, and since the ultraviolet ray irradiation process is only one step, distortion and cracking due to excessive curing of the ultraviolet ray- And yellowing phenomenon can be greatly reduced, and environmental problems due to the use of a large amount of volatile organic compounds can be minimized. Therefore, according to the multi-layer coating method of the simple process of the present invention, it is possible to economically produce a high-quality plastic or metal cell phone case in large quantities to respond to market demands in a timely manner.

The plastic or metal coatings obtained by the multilayer coating method of the present invention, such as plastics and metal cell phone cases, are superior in durability, moisture resistance, abrasion resistance, scratch resistance, texture , Stain resistance, weather resistance, and chemical resistance.

1 is a flow chart for explaining a process for forming a multilayer coating comprising a plurality of layers on a plastic or metal cellular phone case according to a conventional method.
FIG. 2 is a flowchart for explaining a process of forming a multilayered coating composed of a plurality of layers on a plastic or metal cellular phone case according to an embodiment of the present invention.

Hereinafter, a method of coating a plastic or metal substrate according to specific embodiments of the present invention and a plastic or metal coating body obtained thereby will be described in detail.

FIG. 2 is a flowchart for explaining a process of forming a multilayered coating composed of a plurality of layers on a plastic or metal cellular phone case according to an embodiment of the present invention.

Referring to FIG. 2, a primer layer is formed on a plastic or metal cell phone case manufactured by injection molding (S1). For this purpose, a primer layer composition is sprayed on a plastic or metal mobile phone case and an undercoat layer is formed by curing the primer layer composition by irradiating active rays such as ultraviolet rays. Examples of the plastic or metal cellular phone case include a polyester such as polycarbonate, polyethylene terephthalate and polybutylene terephthalate, an acrylonitrile-butadiene-styrene (ABS) copolymer, a vinyl type such as polystyrene and polyvinyl chloride Resin, and polyacetal, and metals such as magnesium, aluminum, titanium, stainless steel, and the like.

The undercoat layer composition comprises polymethylmethacrylate, a low viscosity, multifunctional photocurable oligomer, a photocurable (meth) acrylate monomer, and a photoinitiator. Specifically, the undercoat layer composition comprises 15 to 40 parts by weight of polymethylmethacrylate based on 100 parts by weight of the total composition; 10 to 30 parts by weight of a photopolymerizable (meth) acrylate oligomer having a number average molecular weight of 200 to 5,000 selected from polyurethane (meth) acrylate, polyester (meth) acrylate or mixtures thereof; 10 to 30 parts by weight of a photocurable (meth) acrylate monomer and 20 to 60 parts by weight of a styrene monomer; And 1 to 10 parts by weight of a photoinitiator are preferably used. From the point of view of the present invention, the normal temperature means a temperature range of 15 ° C to 25 ° C.

The polymethylmethacrylate is a polymer binder having a weight-average molecular weight of about 50,000 to about 500,000, preferably about 100,000 to 300,000, and has a weight average molecular weight of about 100 to about 300,000, 15 to about 40 parts by weight, and preferably about 25 parts by weight to about 35 parts by weight, is preferable in terms of coating workability of the obtained undercoating layer.

The photocurable (meth) acrylate oligomer has a number average molecular weight of 200 to 5,000, preferably 300 to 3,000, more preferably 300 to 5,000, selected from polyurethane (meth) acrylate, polyester (meth) acrylate, 500 to 2,000. One or more photocurable (meth) acrylate oligomers may be used in consideration of ease of preparation of the composition and workability of coating.

The photocurable (meth) acrylate oligomer is used in an amount of 10 to 30 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the total composition. If the amount of the photocurable (meth) acrylate oligomer is more than 30 parts by weight, the cross-linking density of the undercoat film after curing becomes too high, the film tends to be broken, cracks easily occur due to heat or impact, Mechanical properties such as hardness and abrasion may be lowered.

In the present invention, 10 to 30 parts by weight of a photocurable (meth) acrylate monomer and 20 to 60 parts by weight of a styrene monomer are used as a reactive diluent for controlling the viscosity of polymethyl methacrylate and a photocurable (meth) acrylate oligomer . If the content of the photocurable (meth) acrylate monomer and the styrene monomer is too low, the viscosity of the composition becomes too high, and if the content of the photocurable (meth) acrylate monomer and styrene monomer is high, the viscosity of the composition becomes too small, There is a problem in that the physical properties after that are deteriorated.

The photocurable (meth) acrylate-based monomer may be, for example, 2-ethylhexyl acrylate, octyldecyl acrylate, stearyl acrylate, behenyl acrylate, tridecyl methacrylate, nonylphenol ethoxylate monoacrylate , Beta-carboxyethyl acrylate, isobornyl acrylate, tetrahydroperfuryl acrylate, tetrahydroperfuryl methacrylate, 4-butylcyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate Acrylate based monofunctional monomers such as methoxyethoxyethyl acrylate, ethoxyethoxyethyl acrylate, ethoxylated monoacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate; 1,6-hexanediol diacrylate, hexamethylene diacrylate, triphenyl glycol diacrylate, butanediol diacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate , Neopentyl glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, triethylene glycol diacrylate Acrylate based monofunctional monomers such as triethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, dipropylene glycol diacrylate, and ethoxylated neopentyl glycol diacrylate; Pentaerythritol tri- or tetraacrylate, ditrimethylol propane tetraacrylate, trimethylol propane triacrylate, ethoxylated trimethylol propane triacrylate, ethoxylated trimethylolpropane methacrylate, Acrylate-modified polyfunctional monomer such as propoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane trimethacrylate, and the like.

The photocurable (meth) acrylate monomer as the reactive diluent is preferably used in an amount of 10 to 30 parts by weight, preferably 15 to 25 parts by weight, based on 100 parts by weight of the total composition. If the content of the photo-curable (meth) acrylate monomer is more than 30 parts by weight, the viscosity of the composition is lowered to make it impossible to form a desired coating film, and the curing rate is slowed down and the mechanical / chemical properties are deteriorated. As the viscosity increases, not only the workability of spray application deteriorates but also the workability and leveling are lowered, and the miscibility of the constituents is deteriorated due to insufficient dilution.

The styrene monomer as the reactive diluent is contained in an amount of 20 to 60 parts by weight, preferably 30 to 60 parts by weight, more preferably 40 to 60 parts by weight, still more preferably 45 to 55 parts by weight, based on 100 parts by weight of the total composition Is preferably used. If the content of the styrene monomer is more than 60 parts by weight, the viscosity of the composition becomes low to make it impossible to form a desired coating film, and the toughness of the obtained undercoat film is lowered. When the content of the styrene monomer is less than 20 parts by weight, Not only deteriorates but also the workability and leveling are deteriorated and the compatibility of the components deteriorates due to insufficient dilution.

The undercoat layer composition comprises 1 to 10 parts by weight, preferably 2 to 8 parts by weight, more preferably 3 to 6 parts by weight of a photoinitiator. The content of the photoinitiator is preferably controlled according to the content of the low viscosity multifunctional photo-curable oligomer, the photocurable (meth) acrylate monomer, and the styrene monomer. If the content of the photoinitiator is more than 10 parts by weight, the molecular weight of the resin constituting the primer film becomes small to increase the brittleness of the coating film. If the amount of the photoinitiator is less than 2 parts by weight, the desired primer film properties may not be obtained or may be uncured. The photoinitiator forms a radical by, for example, ultraviolet rays, and the radical serves to polymerize and crosslink the multifunctional photo-curable oligomer, the photo-curable (meth) acrylate monomer, and the styrene monomer. Specific examples of photoinitiators that can be used in the present invention include 2-hydroxy-1- 4- [4- (2-hydroxy-2-methylpropionyl) -benzyl] phenyl (Irgacure 127), 1-hydroxycyclohexyl phenyl ketone (Irgacure 184), 2-benzyl-2- (dimethylamino) -1- [4- (Irgacure 369), bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Irgacure 819), 2,4,6-trimethylbenzoyldiphenylphosphine TPO), 2-hydroxy-2-methyl-1-phenyl-1-propane (Darocur 1173), benzophenone (BP) and the like.

The undercoat layer composition may further comprise an organic solvent if necessary. Specific examples of the organic solvent usable in the present invention include methyl isobutyl ketone, methyl ethyl ketone, dimethyl ketone, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, ethyl acetate, n-butyl acetate, ethyl cellosolve, Sorb, toluene and xylene. The content of the organic solvent in the photocurable coating composition may be 5 to 20 parts by weight, preferably 5 to 15 parts by weight, more preferably 7 to 10 parts by weight. If the amount of the organic solvent is more than 10 parts by weight, the amount of the volatile organic compound used increases. If the amount of the organic solvent is less than 5 parts by weight, the compatibility of the components of the composition deteriorates due to insufficient dilution force.

In addition, the undercoat layer composition may further contain other additives such as a leveling agent, a wetting agent, a pigment, a dispersing agent and the like in a usual amount.

The undercoat layer composition can be produced by a conventional method for preparing an ultraviolet curing type paint. Specifically, a homopolymerization process is performed by mixing polymethyl methacrylate, a low viscosity polyfunctional photo-curable oligomer, a photocurable (meth) acrylate monomer, and a photoinitiator in a photocurable (meth) acrylate monomer and a styrene monomer . If necessary, an organic solvent and other additives may be further added and mixed and homogenized.

In the present invention, the undercoat layer formed by cross-linking and curing the undercoat layer composition by ultraviolet irradiation includes a primer layer serving to adhere well to the plastic or metal substrate and the undercoat layer, and a light reflectance control layer (inorganic multilayer coating layer) Is integrated into one layer as a function of the sublayer to ensure good adhesion.

Next, a light reflectance controlling layer including an aluminum oxide layer and a titanium oxide layer is formed as a light reflectance controlling layer (S2) on the undercoating layer. For this purpose, a plastic or metal substrate, such as a plastic or metal cell phone case with undercoat layers, is placed in a deposition chamber of a vacuum deposition apparatus, and then an aluminum oxide layer and a titanium oxide (TiO ₂ ) layer are vacuum deposited on the undercoat layer. The light reflectance controlling layer controls the light transmittance in the range of 20 ± 5% by using aluminum oxide such as alumina and controls the increase and decrease of the light reflectance. As the light reflectance controlling layer, a layer having a two-layer structure of an aluminum oxide layer and a titanium oxide layer is preferable from the viewpoint of the characteristics of multi-coating. At this time, the aluminum oxide layer acts as an interlayer adhesive and hardness enhancer, and the titanium oxide layer serves to adjust the color of reflected light and shield ultraviolet rays.

Then, a protective layer containing aluminum oxide (Al ₂ O ₃ ) or silicon carbide (SiC) is formed as a protective layer on the light reflectivity controlling layer (S3). After the formation of the light reflectance controlling layer is completed for this purpose, a protective layer containing aluminum oxide or silicon carbide is vacuum deposited on the light reflectance controlling layer in the same deposition chamber. Aluminum oxide and silicon carbide all have a Mohs hardness of 9 or more and can be greatly improved in abrasion resistance of plastics and metal substrates because they are high hardness materials which are also used as abrasives. Therefore, the plastic or metal substrate produced according to the present invention is excellent in scratch resistance. Aluminum oxide and silicon carbide are dense enough to be used as gas barrier layer materials to protect plastic or metal covers from moisture and other aggressive materials. In particular, in the present invention, since aluminum oxide and silicon carbide are coated by vacuum evaporation, compared with the conventional method of protecting the surface of the light reflectance controlling layer, which is a multi-layer coating, by using a paint as a conventional method, And durability can be obtained.

On the other hand, in the embodiment shown in FIG. 2, a protective layer is formed on the optical reflectance control layer, but according to another embodiment of the present invention, a protective layer may be formed under the optical reflectance control layer. That is, in this case, a protective layer is formed on the undercoat layer, and then a light reflectance control layer is formed. Particularly, in the present invention, since the optical reflectance control layer and the protective layer are continuously formed by vacuum deposition in the same vacuum chamber, the deposition sequence of the two layers is particularly easy to change.

Next, an anti-foaming layer (AF layer) including a metal fluoride is formed on the protective layer (S4). When formation of the protective layer is completed for this purpose, the friction reducing layer is vacuum deposited on the protective layer continuously in the same deposition chamber. The friction reducing layer may be formed using at least one metal fluoride selected from the group consisting of LiF, MgF2, AlF3, CaF2, BaF2, CeF2, MnF2, FeF3, CoF2, NiF2, YF3, ThF4 and CuF have. The friction reducing layer formed of a metal fluoride material can remarkably improve abrasion resistance and visibility by replacing the intermediate layer and the upper layer used for protecting the surface of the light reflectance controlling layer in the conventional method. The friction reducing layer material is a material containing a large amount of fluorine atoms and has a low surface tension so that the surface of the substrate is prevented from being contaminated and easily removed even if it is contaminated. Therefore, the plastic or metal coating material obtained according to the present invention having the protective layer and the friction reducing layer described above is not only deformed or discolored due to wearing of the cellular phone battery cover, plastic or metal outer surface, Or a plastic or metal substrate to prevent fingerprints from being adhered to the outer surface of the device or being contaminated by dust or the like.

In the embodiment shown in FIG. 2, a dark reduction layer is formed on the protective layer, but according to another embodiment, a dark reduction layer is formed on the light reflection adjustment layer. Particularly, in the present invention, it is particularly easy to change the deposition order of the two layers because the light reflectance controlling layer, the protective layer and the reducing layer are continuously formed by vacuum deposition in the same vacuum chamber.

The process of continuously vacuum-depositing the light reflectance control layer, the protective layer, and the reducing layer in the same vacuum chamber may be performed by evaporation (thermal resistance or e-beam) or sputtering vacuum deposition during the vacuum deposition process. E-beam vacuum deposition or sputtering Vacuum deposition can be carried out under vacuum at a vacuum level of, for example, 10 < ^-5 > to 10 < ^{-2 &} gt ^; torr under process conditions well known to those of ordinary skill in the art.

According to the multilayer coating method of the present invention, the conventional primer layer forming step and the undercoat layer forming step are performed by using the undercoat layer composition having a special chemical composition capable of taking charge of both the primer layer and the undercoating layer, It can be replaced by one step of the layer forming step. Also, the steps of forming the light reflectance control layer, forming the protective layer, and forming the friction reducing layer may be performed in a continuous deposition process in one and the same chamber without being performed at separate locations.

Therefore, the multi-layer coating method of the present invention comprises a wet process of spray coating and curing to form a sub-base layer, and a wet process of spray coating and curing to form a sub-base layer of a dry deposition process in which the light reflectance control layer, Step process so that a high-quality multi-layer coating can be simply formed on a plastic or metal cellular phone case. Therefore, according to the multilayer coating method of the present invention, productivity and yield can be greatly improved as compared with the conventional multilayer coating method, and since the ultraviolet ray irradiation process is only one step, distortion and cracking due to excessive curing of the ultraviolet ray- And the yellowing phenomenon can be greatly reduced and the use of the ultraviolet curing type paint can be minimized, thereby minimizing environmental problems due to the use of a large amount of volatile organic compounds (VOC).

Therefore, according to the multi-layer coating method of the simple process of the present invention, it is possible to economically produce a high-quality cell-phone case in large quantities to respond to market demands in a timely manner.

The plastic or metal coatings obtained by the multilayer coating method of the present invention, such as plastics or metal cell phone cases, are superior in durability, moisture resistance, abrasion resistance, scratch resistance, and texture , Stain resistance, weather resistance, and chemical resistance.

Accordingly, in the present invention, not only the light reflectance controlling layer, which is a multi-coating layer, is protected by using a specially designed undercoat layer serving as a primer layer but also the light reflectance controlling layer is protected by using an aluminum oxide or silicon carbide having excellent performance, By applying a friction reducing layer made of a low coefficient of friction material such as metal fluoride, the conventional five or more steps are reduced to a two step process. In addition, the plastic or metal coating material obtained according to the method of the present invention can exhibit durability and vulcanization resistance which can not be realized in plastic or metal coatings used in conventional mobile phone cases.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are intended to illustrate the present invention and the scope of the present invention is not limited thereby.

Preparation Example 1: Preparation of solution-evaporation type primer composition (first and second primer layer composition) used in Comparative Examples

100 g of polyvinyl butylal (Sekisui Chemical Co., Ltd., S-LEC B) and 10 g of a leveling agent (EBECRYL 350, SK-UCB) were added at about 60 ° C for about 4 hours Followed by stirring to prepare a solution evaporative primer composition having a viscosity of about 500 cps at 25 ° C.

Preparation Example 2: Preparation of ultraviolet curable base coating composition (composition for undercoat layer) used in Comparative Example

, 100 g of pentaerythritol triacrylate (trade name: PETA, SK-UCB), 100 g of trimethylolpropane triacrylate (trade name: TMPTA, Miwon Chemical Co., Ltd.), 1 g of 1 , 10 g of a leveling agent (EBECRYL 350, manufactured by SK-UCB), 10 g of a photoinitiator (trade name: Irgacure 369, manufactured by Ciba Specialty Chemicals), and 10 g of 6-hexanediol diacrylate (trade name: HDDA, An ultraviolet curable composition having a viscosity of about 500 cps was prepared.

Preparation Example 3: Preparation of a solvent-evaporating transparent intermediate layer composition used in Comparative Example

100 g of polyvinyl butylal (Sekisui Chemical Co., Ltd., S-LEC B) and 10 g of a leveling agent (EBECRYL 350, SK-UCB) were added at about 60 ° C for about 4 hours And the mixture was stirred to prepare a solution evaporation type transparent intermediate layer composition having a viscosity of about 500 cps at 25 캜.

Preparation Example 4: Preparation of composition for ultraviolet curing type transparent topcoat layer used in Comparative Example

, 100 g of pentaerythritol triacrylate (trade name: PETA, SK-UCB), 100 g of trimethylolpropane triacrylate (trade name: TMPTA, Miwon Chemical Co., Ltd.), 1 g of 1 , 10 g of a leveling agent (EBECRYL 350, manufactured by SK-UCB), 10 g of a photoinitiator (trade name: Irgacure 369, manufactured by Ciba Specialty Chemicals), and 10 g of 6-hexanediol diacrylate (trade name: HDDA, An ultraviolet curable composition having a viscosity of about 500 cps was prepared.

Preparation Example 5: Preparation of undercoat layer composition used in the examples

1.0 equivalent of a dihydroxy-functional polymethacrylate polyol (Gold Schmidt Co., Diol BD 1000, Germany) was placed in a four-necked round-bottomed flask, and a condenser, a stirrer and a thermometer were placed, and the temperature was raised to 40 ° C. Then, 2 equivalents of an isophorone diisocyanate trimer (product name: LUXATE ITM 800, manufactured by Olin, USA) was added dropwise into the dropping tube and added dropwise for 1 hour and reacted for 1 hour while maintaining 45 ° C. Then 1.1 equivalents of caprolactone acrylate was added dropwise into the dropping tube and added dropwise for 30 minutes, and the mixture was maintained at 65 DEG C until all of the isocyanate groups disappeared to prepare an ultraviolet curable polyurethane acrylate oligomer having a number average molecular weight of about 1,800.

800 g of polymethyl methacrylate having a weight average molecular weight of about 300,000 (manufactured by Mitsubishi Rayon Co., Ltd.), 650 g of the ultraviolet curable polyurethane acrylate oligomer, 100 g of ethoxylated trimethylolpropane triacrylate (trade name: TMPEOTA, 250 g of 1,6-hexanediol diacrylate (trade name: HDDA, Mitsubishi Chemical Corporation), 1200 g of styrene monomer, 30 g of a photoinitiator (Irgacure 369, Ciba Specialty Chemicals) and 10 g of a leveling agent (EBECRYL 350, SK-UCB) To prepare an ultraviolet curable undercoat layer having a viscosity of about 500 cps at 25 ° C.

Example 1

A 1.0 mm thick smartphone case injection molded with polycarbonate resin was attached to the jig. The jig was mounted on a spindle spray line for manufacturing a mobile phone case, and the undercoating composition obtained in Preparation Example 5 was applied on the case by spraying and dried at about 25 ° C for about 10 seconds. Thereafter, an ultraviolet irradiator (product name: Metal Halide UV Lamp, Ultraviolet ray having a wavelength of about 250 to 450 nm was irradiated under a curing condition of a line speed of 12 m / min and an ultraviolet ray dose of 900 mJ / cm2 using an ultraviolet lamp (Korea Ultraviolet) to form a sublayer having a thickness of 20 3 m.

Subsequently, the jig was mounted in a vacuum evaporator, and a first port accommodating the Al2O3 target material, a second port accommodating the TiO2 target material, and a third port accommodating the AlF3 target material, respectively, were mounted in the vacuum evaporator. Then, when the inner space of the vacuum evaporator is evacuated and the degree of vacuum reaches 4.0 x 10 ^-5 torr, the e-beam is selectively irradiated in the order of the second port, the third port, the second port, and the third port A TiO 2 layer having a thickness of about 50 Å, an Al 2 O 3 layer having a thickness of about 50 Å, a TiO 2 layer having a thickness of about 70 Å, and an Al 2 O 3 layer having a thickness of about 70 Å were deposited on the underlayer.

Then, an e-beam was irradiated to the first port to deposit a protective layer of Al2O3 layer having a thickness of about 100 Å on the light reflectance control layer.

Subsequently, an e-beam was irradiated to the third port, and a friction reducing layer of AlF 3 layer having a thickness of about 100 Å or more was successively deposited on the protective layer of the Al 2 O 3 layer to prepare a case coating for a smartphone.

Example 2

A protective layer of an Al2O3 layer having a thickness of about 100 angstroms was first deposited on the undercoat layer having a thickness of 20 +/- 3 mu m, and then a TiO2 layer having a thickness of about 50 ANGSTROM / an Al2O3 layer having a thickness of about 50 ANGSTROM / a TiO2 layer / A case coating for a smartphone was prepared in the same manner as described in Example 1, except that the light reflectance control layer of Al2O3 layer of about 50 angstroms was deposited.

Example 3

A protective layer of an Al2O3 layer having a thickness of about 150 angstroms was first deposited on the underlayer having a thickness of 20 +/- 3 mu m, and then a TiO2 layer having a thickness of about 250 angstroms / a thickness of about 50 angstroms of an Al2O3 layer was deposited on the protective layer. A protective layer of an Al2O3 layer having a thickness of about 150 ANGSTROM and a TiO2 layer having a thickness of about 250 ANGSTROM / a light reflectance controlling layer of an Al2O3 layer having a thickness of about 50 ANGSTROM were sequentially deposited thereon.

Except for this, a case coating for a smartphone was prepared in the same manner as in the method described in Example 1.

Comparative Example 1

A 1.0 mm thick smartphone case injection molded with polycarbonate resin was attached to the jig. The jig was mounted on a spindle spray line for manufacturing a mobile phone case, and the solution evaporation primer composition obtained in Preparation Example 1 was sprayed on the case and dried at about 80 캜 for about 30 seconds to obtain a first primer Layer.

Subsequently, the ultraviolet curable base coating material obtained in Preparation Example 2 was applied onto the first primer layer by spraying on the spindle spray line, and the coating was sprayed on the line using an ultraviolet ray irradiation apparatus (product name: metal halide UV lamp, manufactured by Kanku UV Co., Ltd.) Under a curing condition of a speed of 12 m / min and an ultraviolet dose of 900 mJ / cm < 2 > to form a primer layer having a thickness of about 25 to 30 mu m.

Subsequently, a SiO 2 layer having a thickness of about 50 Å, a TiO 2 layer having a thickness of about 70 Å, a SiO 2 layer having a thickness of about 50 Å, and a thickness of about 50 Å were formed on the underlayer by vacuum evaporation using e-beam on the underlayer in the vacuum evaporator described in Example 1 A light reflectance control layer of a multi-coating layer made of a TiO2 layer of about 80 ANGSTROM / a SiO2 layer of about 50 ANGSTROM was deposited.

The jig equipped with the case for the smartphone obtained above was mounted on the spindle spray line again. Subsequently, the solution evaporative primer composition obtained in Preparation Example 1 was sprayed on the case and dried at about 25 ° C for about 15 seconds to form a second primer layer having a thickness of about 2 to 3 μm.

Subsequently, the solvent-evaporated transparent intermediate layer composition obtained in Preparation Example 3 was sprayed on the second primer layer in the spindle spray line and dried at about 80 캜 for about 30 seconds to form a middle layer having a thickness of about 4 to 6 탆 Respectively.

Subsequently, the composition for ultraviolet curing type transparent topcoat layer prepared in Preparation Example 4 was applied by spraying on the intermediate layer in the spindle spray line, and the composition was applied to the line using an ultraviolet irradiator (product name: metal halide UV lamp, manufactured by Korea Ultraviolet Co., Ltd.) Ultraviolet rays having a wavelength of about 250 to 400 nm were irradiated under a curing condition of a speed of 12 m / min and an ultraviolet dose of 900 mJ / cm2 to form a top coat layer having a thickness of about 25 to 30 탆 to prepare a case coating for a smartphone.

Character rating

Properties of the following items were evaluated for the case coatings for smartphones obtained in Examples 1 to 3 and Comparative Example 1. The evaluation method was as follows.

(1) Overall yield

The case coatings for 30 smartphones were manufactured according to the methods described in the respective Examples and Comparative Examples, and the yields were calculated from the number of good products according to the following formula.

Overall yield = number of good products / 30 × 100 (%).

In the case where the surface of the coating material was observed to be cracked, the coating material was warped, or any foreign material was formed on the coating material.

(2) Reflectance

The reflectance was measured by placing a soda lime glass having a size similar to that of a polycarbonate case coating material for a smartphone into a vacuum evaporator, concurrently with the case, a soda lime glass coating obtained by vacuum evaporation of a metal oxide multi- Was measured using a spectrometer (product name: CL-200, manufacturer: Minolta). The reference wavelength used for the measurement was 550 nm. The transmittance of the light of this wavelength was measured and the reflectance was calculated using the following relational expression.

Light reflectance (%) = 100-light transmittance (%).

(3) Pencil Hardness

According to the method and conditions specified in ASTM D3363-74, when a pencil is pushed at an angle of 45 ° to the plane of the coating and a measurement is made five times by pushing it under a load of 1 kg, if the scratch pattern or the surface of the coating is not broken more than twice, The hardness value was the surface hardness value.

(4) Adhesiveness

The adhesion between the coating layer and the polycarbonate substrate was evaluated according to the method and conditions specified in ASTM D3359-87 as follows.

11 strips of horizontal and vertical lines were drawn with a knife so as to reach the polycarbonate substrate at intervals of 1 mm on the surface of the coating material, and 100 cells each having a size of 1 mm x 1 mm were made, and a cellophane tape having excellent adhesive strength was stuck thereon. To the nearest angle. This is repeated three times at the same position, where the adhesion criteria are as follows:

Defective: More than one peeled off from the grid.

Excellent: No peeling occurs in all grids.

However, it was not considered in the judgment that the corners of the grid fell in the form of a triangle.

(5) Antifouling property and pollutant release property

Blue stripe magic was used to draw a line in the direction of 45 degrees on the surface of the coating, and then the ink was completely dried and rubbed with a clean cloth and visually observed. The following criteria were evaluated.

Excellent: The ink is completely removed from the rubbed surface.

Poor: ink is not completely removed from the rubbed surface.

(6) Water Absorption Rate

The coatings were placed in a constant temperature and humidity chamber at 100% humidity and 25 ° C. After 24 hours, weight change was measured to determine the water absorption rate.

(7) Bending characteristics

When both ends of the coating were held and bent at 90 or 180 degrees, whether or not the surface layer or the material was broken was visually observed and evaluated according to the following criteria.

Excellent: The state of the coated surface is maintained.

Normal: Cracking occurs in the same direction as the deflection direction.

Poor: Cracks occur in all directions.

Table 1 summarizes the evaluation results of the characteristics of the casing coatings for smartphones obtained in Examples 1 to 3 and Comparative Example 1. [

Example 1 Example 2 Example 3 Comparative Example 1 Overall yield
93.4% 93.0% 93.1% 70.0% reflectivity
15.5% 16.7% 19.8%
16% Pencil hardness
3H or more 3H or more 3H or more F Polycarbonate
Adhesion to substrate Great Great Great Great Antifouling
Great Great Great Bad Removal of pollutants
Great Great Great Bad Water absorption rate
0.25% 0.21% 0.2% 2.5% Bending property
Great Great Great Bad

Referring to Table 1, it can be seen that the yields of Examples 1 to 3 according to the present invention were all higher than 90% of the total yield, but in Comparative Example 1, the overall yield was 70%, indicating a high defect rate. Also, in Examples 1 to 3, the pencil hardness was high due to the aluminum oxide called artificial sapphire even though the coating thickness was 1/5 or less as compared with the case of Comparative Example 1. [ Therefore, in Examples 1 to 3, it is found that the coating material is excellent in abrasion resistance and scratch resistance. In the case of Examples 1 to 3, the coating was excellent in aesthetic effect that the appearance was beautiful as a ceramic because of aluminum oxide called artificial sapphire.

On the other hand, in Examples 1 to 3, the surface tension was about 40 dyne / cm, which was much lower than 59 dyne / cm of Comparative Example 1. Therefore, It can also be seen that the contaminants adhering to the surface are also easily removed. Further, in the case of Examples 1 to 3, the moisture absorption rate was about 0.25% or less, which is much lower than that of Comparative Example 1, which is much lower. Especially in the case of Example 3, by continuously depositing the Al 2 O 3 protective layer / the TiO 2 layer + the Al 2 O 3 layer, the light reflectance control layer / Al 2 O 3 protective layer / TiO 2 layer + Al 2 O 3 layer and the AlF 3 layer, A coating having excellent adhesion, antifouling property, decontamination property, water absorption rate, and bending property could be obtained with good yield.

S1: sublayer formation step
S2: light reflectance control layer formation step
S3: protective layer forming step
S4: step of forming a friction reducing layer.

Claims (10)

Forming a primer layer on the plastic or metal substrate;
Forming a light reflectance control layer including an aluminum oxide layer and a titanium oxide layer on the undercoat layer;
Forming a protective layer including aluminum oxide or silicon carbide on the light reflectance adjusting layer; And
Forming a friction reducing layer comprising a metal fluoride on the protective layer,
The step of forming the light reflectance control layer, forming the protective layer, and forming the friction reducing layer may be performed by a continuous deposition process under a pressure lower than atmospheric pressure in the same chamber. Coating method. Forming a primer layer on the plastic or metal substrate;
Forming a protective layer comprising aluminum oxide or silicon carbide on the undercoating layer;
Forming a light reflectance controlling layer including an aluminum oxide layer and a titanium oxide layer on the protective layer; And
Forming a friction-reducing layer comprising a metal fluoride on the light reflectance control layer,
The step of forming the protective layer, forming the light reflectance control layer, and forming the friction reducing layer may be performed by a continuous deposition process under a pressure lower than atmospheric pressure in the same chamber. Coating method. The metal fluoride according to claim 1 or 2, wherein the metal fluoride is at least one selected from the group consisting of LiF, MgF2, AlF3, CaF2, BaF2, CeF2, MnF2, FeF3, CoF2, NiF2, YF3, ThF4, A method of coating a substrate. The method of claim 1 or 2, wherein the forming the undercoat layer comprises: 15 to 40 parts by weight of polymethylmethacrylate based on 100 parts by weight of the total composition; 10 to 30 parts by weight of a photopolymerizable (meth) acrylate oligomer having a number average molecular weight of 200 to 5,000 selected from polyurethane (meth) acrylate, polyester (meth) acrylate or mixtures thereof; Coating a photocurable coating composition comprising 10 to 30 parts by weight of a photocurable (meth) acrylate monomer, 20 to 60 parts by weight of a styrene monomer, and 1 to 10 parts by weight of a photoinitiator onto the plastic or metal substrate and photocuring ≪ / RTI > 5. The method of claim 4, wherein the photocurable coating composition further comprises 5 to 20 parts by weight of an organic solvent. Plastic or metal substrates;
A primer layer formed on the plastic or metal substrate;
A light reflectance control layer comprising an aluminum oxide layer and a titanium oxide layer as a light reflectance controlling layer formed on the undercoating layer;
A protective layer comprising aluminum oxide or silicon carbide as a protective layer formed on the light reflectance controlling layer; And
And a friction reducing layer comprising a metal fluoride as a friction reducing layer formed on the protective layer. Plastic or metal substrates;
A primer layer formed on the plastic or metal substrate;
A protective layer comprising aluminum oxide or silicon carbide as a protective layer formed on the undercoat layer;
A light reflectance adjusting layer including an aluminum oxide layer and a titanium oxide layer as a light reflectance controlling layer formed on the protective layer; And
And a friction reducing layer comprising a metal fluoride as a friction reducing layer formed on the light reflectance controlling layer. The metal fluoride according to claim 6 or 7, wherein the metal fluoride is at least one selected from the group consisting of LiF, MgF2, AlF3, CaF2, BaF2, CeF2, MnF2, FeF3, CoF2, NiF2, YF3, ThF4, Coating body. 8. The method of claim 6 or 7, wherein the undercoat layer comprises 15 to 40 parts by weight of polymethylmethacrylate based on 100 parts by weight of the total composition; 10 to 30 parts by weight of a photopolymerizable (meth) acrylate oligomer having a number average molecular weight of 200 to 5,000 selected from polyurethane (meth) acrylate, polyester (meth) acrylate or mixtures thereof; 10 to 30 parts by weight of a photocurable (meth) acrylate monomer and 20 to 60 parts by weight of a styrene monomer, wherein the curable product is a cured product of the photocurable coating composition. The plastic or metal coating according to claim 6 or 7, wherein the plastic or metal coating is a cellular phone case, a tablet PC case, a notebook PC case, or a PDA (personal digital assistant) case.

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