KR101406845B1 - Coating method of plastics substrate and coated plastics body obtained thereby - Google Patents

Abstract

Forming a flexible undercoat layer on the plastic substrate; Forming a light transmittance and reflectance control layer including a silicon oxide layer and a titanium oxide layer on the flexible undercoat layer; Forming a protective layer including aluminum oxide or silicon carbide on the light transmittance and reflectance control layer; And forming a friction reducing layer including at least one selected from the group consisting of a fluorocarbon resin, a silicon fluoride resin, a polysiloxane resin, and a polysilazane resin on the protective layer, wherein the light transmittance and the reflectance control layer Wherein the step of forming the protective layer and the step of forming the friction reducing layer are performed by a continuous deposition process under a pressure lower than atmospheric pressure in the same chamber and a high quality plastic A coating is provided. According to this, the mass production of the plastic coating material which 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

TECHNICAL FIELD The present invention relates to a method for coating a plastic substrate and a plastic coating obtained by the method.

The present invention relates to a coating method of a plastic substrate and a plastic coating obtained by the method. More specifically, the present invention can be applied to a large-scale production of a plastic coating material which can be used as a case of various small electronic apparatuses such as a feature phone, a smart phone and a tablet personal computer (PC), a notebook PC, To a method of coating a plastic substrate and a high-quality plastic coating body obtained by the method.

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 their respective functions is formed on a plastic cellular phone case, thereby realizing a sense of beauty such as color that can not be achieved by coating only the paint. However, in order to form multiple layers on a plastic cellular phone case, a number of processes must be performed. However, as the number of processes increases, the production cost increases due to an increase in defective products, that is, a decrease in production yield. Thus, it is difficult to economically produce a high-quality cell phone case in large quantities and cope with the demands of the market in a timely manner by using the method of manufacturing a plastic cell phone case by multilayer coating widely adopted in the technical field.

1 is a flow chart for explaining a process of forming a multi-layer coating composed of a plurality of layers on a plastic cellular phone case according to a conventional method.

Referring to FIG. 1, a first primer layer is formed on a plastic cellular phone case manufactured by an injection process (S1 '). To this end, a primer layer composition is usually applied onto a plastic 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 the plastic cellular phone case, and the primer layer is formed using an ultraviolet curable coating material having high light transmittance and compatibility with the reflectance control layer, which is composed of an inorganic material to be formed in a subsequent step . Subsequently, a light transmittance and a reflectance control layer are 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. Subsequently, a second primer layer is formed on the light transmittance and reflectance control layer (S4 '). The second primer layer is formed by using a paint having good affinity with the light transmittance and reflectance control layer made of 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 transmittance and reflectance control 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 '). For this purpose, the intermediate layer composition is usually applied by spraying onto the light transmittance and reflectance control layer and dried and / or irradiated with infrared rays 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 in bonding the top layer together with the primer layer to the light transmittance and the reflectance control layer. The upper layer is formed using a (meth) acrylate-based ultraviolet ray curing type coating material containing a slipping agent and having a chemical structure with good scratch resistance and abrasion resistance.

According to a conventional process for forming a multi-layer coating consisting of multiple layers on a plastic cell phone case as described above, the plastic cell phone case must move at least five times to the area where each unit process is performed and at least a plurality of ultraviolet irradiation processes It exposes a number of problems as follows.

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.

It is therefore 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 plastic coating material which can be used as a case of a mobile phone such as a smart phone, The present invention provides a method of coating a plastic substrate.

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

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

Forming a flexible undercoat layer on the plastic substrate;

Forming a light transmittance and reflectance control layer including a silicon oxide layer and a titanium oxide layer on the flexible undercoat layer;

Forming a protective layer comprising aluminum oxide or silicon carbide on the light transmittance and reflectance control layer; And

Forming a friction reducing layer comprising at least one member selected from the group consisting of a fluorocarbon resin, a silicone fluoride resin, a polysiloxane resin and a polysilazane resin as the friction reducing layer on the protective layer,

Wherein the step of forming the light transmittance and reflectance control layer, forming the protective layer, and forming the friction reducing layer are 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 flexible undercoat layer on the plastic substrate;

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

Forming a light transmittance and reflectance controlling layer including a silicon oxide layer and a titanium oxide layer on the protective layer; And

Forming a friction reducing layer comprising at least one selected from the group consisting of a fluorocarbon resin, a silicone fluoride resin, a polysiloxane resin and a polysilazane resin as the friction reducing layer on the light transmittance and reflectance control layer,

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

The step of forming the flexible 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; And 1 to 10 parts by weight of a photoinitiator may be applied by spraying and photocuring the photocurable coating composition onto the plastic substrate.

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 substrates;

A flexible undercoat layer formed on said plastic substrate;

A light transmittance and reflectance control layer including a silicon oxide layer and a titanium oxide layer as a light transmittance and reflectance control layer formed on the flexible undercoat layer;

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

There is provided a plastic coating comprising a friction reducing layer formed on the protective layer, the friction reducing layer comprising at least one selected from the group consisting of a fluorocarbon resin, a silicone fluoride resin, a polysiloxane resin and a polysilazane resin.

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

Plastic substrates;

A flexible undercoat layer formed on said plastic substrate;

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

A light transmittance and reflectance control layer including a silicon oxide layer and a titanium oxide layer as a light transmittance and reflectance control layer formed on the protective layer; And

There is provided a plastic coating comprising a friction reducing layer formed on the light transmittance and reflectance controlling layer, the friction reducing layer comprising at least one selected from the group consisting of a fluorocarbon resin, a silicone fluoride resin, a polysiloxane resin and a polysilazane resin .

The flexible 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 substrate 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 undercoating layer forming step are performed by using the flexible undercoating layer composition having a special chemical composition capable of taking the role of the conventional primer layer and undercoat layer together It can be replaced by the first step of the flexible layer formation step. Also, the steps of forming the light transmittance and reflectance control layer, forming the protective layer, and forming the friction reducing layer may be conducted in a continuous deposition process in one and the same chamber, rather than in separate locations .

Accordingly, the multilayer coating method of the present invention is characterized by a wet process of spray application and curing, which largely forms a flexible underlayer, and a dry process of continuously forming a light transmittance and reflectance control layer, a protective layer and a friction reducing layer in one and the same chamber And a high-quality multi-layer coating can be formed on a plastic cellular phone case simply. 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 environmental problems due to the use of a large amount of volatile organic compounds can be minimized. Therefore, according to the multilayer coating method of the simple process of the present invention, it is possible to economically produce a high-quality plastic cellular phone case in large quantities to respond to market demands in a timely manner.

The plastic coating material such as the plastic cell phone case obtained by the multilayer coating method of the present invention is superior in durability, moisture resistance, abrasion resistance, scratch resistance, texture, stain resistance, weather resistance, And the chemical properties such as chemical resistance are remarkably excellent.

1 is a flow chart for explaining a process of forming a multi-layer coating composed of a plurality of layers on a plastic cellular phone case according to a conventional method.
2 is a flow chart for explaining a process for forming a multilayer coating composed of a plurality of layers on a plastic cell phone case according to an embodiment of the present invention.

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

2 is a flow chart for explaining a process for forming a multilayer coating composed of a plurality of layers on a plastic cell phone case according to an embodiment of the present invention.

Referring to FIG. 2, a flexible undercoat layer is formed on a plastic cellular phone case manufactured by injection molding (S1). For this purpose, a flexible undercoat composition is sprayed onto a plastic cell phone case and the flexible undercoat composition is cured by activating active lines, such as ultraviolet light, to form a flexible undercoat layer. The plastic cellular phone case may be made of, for example, a polyester such as polycarbonate, polyethylene terephthalate, polybutylene terephthalate, an acrylonitrile-butadiene-styrene (ABS) copolymer, a vinyl resin such as polystyrene, polyvinyl chloride, And polyacetal.

The flexible undercoat layer composition comprises polymethylmethacrylate, a low viscosity, multifunctional photo-curable oligomer, a photocurable (meth) acrylate monomer, and a photoinitiator. Specifically, the flexible 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 100,000 to about 300,000, 15 to about 40 parts by weight, and preferably about 25 parts by weight to about 35 parts by weight, in terms of flexibility and application workability of the undercoat layer obtained.

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 flexible 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 are generated by heat or impact, and when the amount is less than 10 parts by weight, And mechanical properties such as abrasion may be reduced.

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 . When the content of the photocurable (meth) acrylate monomer and the styrene monomer is too low, the viscosity of the flexible composition becomes too high, and when the content of the photocurable (meth) acrylate monomer and styrene monomer is small, the viscosity of the flexible composition becomes too small, There is a problem that the hardenability and the cured properties 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 is lowered to make it impossible to form a desired coating film and the flexibility of the obtained undercoat film is lowered. If it is less than 20 parts by weight, the viscosity of the composition is increased, The workability leveling is lowered, and the miscibility of the components is deteriorated due to insufficient dilution.

The flexible 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 layer becomes small and the brittleness of the coating film becomes large. If the content 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 flexible undercoat layer composition may further comprise an organic solvent as required. 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 flexible undercoat layer composition may further contain other additives such as leveling agents, wetting agents, pigments, dispersing agents and the like in a usual amount.

The flexible 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 flexible undercoat layer formed by cross-linking and curing the flexible undercoat layer composition by ultraviolet irradiation is composed of a primer layer serving to adhere well to the plastic substrate and the undercoat layer, a light transmittance and reflectance control layer Coating layer) is well integrated into one layer as a function of the sublayer.

Then, a light transmittance and a reflectance control layer including a silicon oxide layer and a titanium oxide layer are formed as a light transmittance and reflectance control layer on the flexible undercoat layer (S2). For this purpose, a plastic substrate such as a plastic cell phone case with a flexible undercoat layer is placed in a deposition chamber of a vacuum deposition apparatus, and then a silicon oxide (SiO ₂ ) layer and / or a titanium oxide (TiO ₂ ) . The light transmittance and reflectance control layer functions to adjust the light transmittance to 20 ± 5% using alumina and reduce the light reflectance. As the light transmittance and the reflectance control layer, a two-layer structure of a silicon oxide layer and a titanium oxide layer is preferable from the viewpoint of characteristics of multi-coating. At this time, the silicon oxide layer serves as an interlayer adhesive, and the titanium oxide layer serves as a hue definition of reflected light.

Next, a protective layer including aluminum oxide (Al ₂ O ₃ ) or silicon carbide (SiC) is formed as a protective layer on the light transmittance and reflectance control layer (S3). When the formation of the light transmittance and the reflectance control layer is completed for this purpose, a protective layer containing aluminum oxide or silicon carbide is vacuum deposited on the light transmittance and reflectance control 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 a plastic substrate because they are high hardness materials which are also used as abrasives. Therefore, the plastic substrate produced according to the present invention is excellent in scratch resistance. Aluminum oxide and silicon carbide are so dense that they can be used as gas barrier layer materials to protect the cell phone battery cover from moisture and other aggressive substances. Particularly, in the present invention, aluminum oxide and silicon carbide are coated by vacuum evaporation. Therefore, compared with the conventional method of protecting the surface of the multilayered coating, that is, the light transmittance and the reflectance control layer, Scratch resistance and durability can be obtained.

On the other hand, in the embodiment shown in FIG. 2, a protective layer is formed on the light transmittance and reflectance control layer, but according to another embodiment of the present invention, on the contrary, a protective layer is formed below the light transmittance and reflectance control layer . That is, in this case, a protective layer is formed on the flexible undercoat layer, and then a light transmittance and a reflectance control layer are formed. Particularly, in the present invention, since the light transmittance, the 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 antifinger layer (AF) layer 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. As the friction reducing layer, a fluorocarbon resin, a silicon fluoride resin, a polysiloxane resin and / or a polysilazane resin can be formed. Specific examples of the fluorocarbon resin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), and polyfluorovinylidene (PVDF). The fluorosilicone resin includes a resin in which the alkyl group of the side chain of the polysiloxane resin is at least partially substituted with a fluorine atom. Polysilazane resins are polymeric materials that form a skeleton by alternating silicon atoms and nitrogen atoms and are sometimes referred to as abrasion resistant resins or glass films. The friction reducing layer formed of such a material can also improve abrasion resistance by replacing the intermediate layer and the upper layer used to protect the surface of the light transmittance and reflectance control layer in the conventional method. The friction reducing layer material is a material containing a large amount of fluorine atoms and silicon 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 coating obtained according to the present invention having the protective layer and the friction reducing layer described above can be used not only for a phenomenon in which the appearance of the cell phone battery cover or the plastic substrate is deformed or discolored due to wear or moisture penetration, And prevents the fingerprint from being contaminated by dust or the like.

In the embodiment shown in FIG. 2, a friction reducing layer is formed on the protective layer, but according to another embodiment, on the contrary, a friction reducing layer is formed on the light transmittance and reflectance adjusting layer. Particularly, in the present invention, since the light transmittance and the reflectance control layer, the protective layer and the friction reducing layer are continuously formed by vacuum deposition in the same vacuum chamber, the deposition sequence of the two layers is particularly easy to change.

The process of continuously vacuum-depositing the light transmittance and the reflectance control layer, the protective layer, and the friction 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. Particularly, when the target material is evaporated by evaporation by heat resistance or e-beam irradiation, the light transmittance and reflectance control layer, the protective layer and the friction reduction layer can be easily and easily used in the same vacuum And can be continuously deposited in the chamber.

According to the multilayer coating method of the present invention, the conventional primer layer forming step and the undercoating layer forming step are performed by using the flexible undercoating layer composition having a special chemical composition capable of taking the role of the conventional primer layer and undercoat layer together It can be replaced by the first step of the flexible layer formation step. Also, the steps of forming the light transmittance and reflectance control layer, forming the protective layer, and forming the friction reducing layer may be conducted in a continuous deposition process in one and the same chamber, rather than in separate locations .

Accordingly, the multilayer coating method of the present invention is characterized by a wet process of spray application and curing, which largely forms a flexible underlayer, and a dry process of continuously forming a light transmittance and reflectance control layer, a protective layer and a friction reducing layer in one and the same chamber And a high-quality multi-layer coating can be formed on a plastic cellular phone case simply. 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.

In addition, the plastic coating body such as the plastic cell phone case obtained by the multilayer coating method of the present invention is superior in durability, moisture resistance, abrasion resistance, scratch resistance, texture, stain resistance, weather resistance, And the chemical properties such as chemical resistance are remarkably excellent.

Accordingly, in the present invention, not only a light transmittance and reflectance control layer, which is a multi-coating layer, is protected by using a specially designed flexible undercoat layer also serving as a primer layer, but also a light transmittance and reflectance control layer And a friction reducing layer made of a material having a low coefficient of friction such as a silicone fluoride resin is applied to reduce the conventional five or more steps to two steps. In addition, the plastic coating material obtained according to the method of the present invention can exhibit flexibility, durability and vulcanization resistance which can not be realized in a plastic coating material used as a conventional cellular phone case.

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 the flexible undercoat layer composition used in the examples

1.0 equivalent of a dihydroxy functional polymethacrylate polyol (Germany Gold Schmidt Co., Ltd. Diol BD 1000) was placed in a four-necked round-bottomed flask together with a catalyst and a polymerization inhibitor, and a condenser, a stirrer and a thermometer were placed. Lt; / RTI > 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 flexible 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, the flexible undercoat composition obtained in Preparation Example 5 was applied on the case by spraying and dried at about 25 DEG C for about 10 seconds, and then irradiated with an ultraviolet ray irradiation apparatus (product name: metal halide UV lamp, A flexible undercoat layer having a thickness of 10 ± 3 μm was formed by irradiating ultraviolet rays having a wavelength of about 250 to 450 nm under a curing condition of a line speed of 12 m / min and an ultraviolet dose of 900 mJ / cm 2 using a manufacturer (manufactured by Korea Ultraviolet) .

Subsequently, the jig is mounted in a vacuum evaporator, and a first port for receiving an Al2O3 target material, a second port for receiving a TiO2 target material, and a third port for receiving a SiO2 target material, A port was mounted in the vacuum evaporator. Subsequently, when the internal 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 light transmittance and reflectance control layer of a TiO 2 layer of about 50 Å thick, a SiO 2 layer of about 50 Å thick, a TiO 2 layer of about 70 Å thick, and a SiO 2 layer of about 70 Å thick were deposited on the flexible undercoat layer.

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 transmittance and reflectance control layer.

Subsequently, a friction reducing layer of a PTFE layer of about 100 Å in thickness was continuously deposited on the protective layer of the Al2O3 layer by irradiating the fourth port with e-beam, thereby preparing 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 flexible undercoat layer having a thickness of 10 +/- 3 mu m, and then a TiO2 layer having a thickness of about 50 ANGSTROM / a SiO2 layer having a thickness of about 50 ANGSTROM / A case coating for a smartphone was prepared in the same manner as described in Example 1, except that the light transmittance and reflectivity control layer of a SiO2 layer of about 50 Å in thickness was deposited.

Example 3

A protective layer of an Al2O3 layer having a thickness of about 150 ANGSTROM was first deposited on a flexible undercoat layer having a thickness of 10 +/- 3 mu m and then a light transmittance and reflectance control layer of a TiO2 layer of about 250 ANGSTROM / Respectively. A light transmittance and a reflectance control layer of a protective layer of Al2O3 layer of about 150 Å in thickness and a SiO2 layer of about 50 Å in thickness were continuously 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, the solution evaporation type primer composition obtained in Preparation Example 1 was sprayed on the case and dried at about 25 ° C for about 10 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 transmittance and reflectance control layer of a multi-coating layer made of a TiO2 layer of about 80 ANGSTROM / a SiO2 layer of about 50 ANGSTROM thickness 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 on the intermediate layer by sputtering in the spindle spray line, and the coating solution was applied to the line by using an ultraviolet ray irradiation apparatus (product name: metal halide UV LAMP manufactured by Korea Ultraviolet Co., 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 smart phone into a vacuum evaporator, and simultaneously forming a light transmittance and reflectance control layer and a soda lime glass coating 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 water absorption rate was determined by measuring the change in weight after 24 hours after placing the coating on the inside of the thermo-hygrostat under the conditions of 100% humidity and 25 ° C.

(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
15.8% 15.5% 20.5%
16% Pencil hardness
2H or more 2H or more 2H 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% 0.1% 0.03% 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. Also, in the case of Examples 1 to 3, the coating was excellent in aesthetic effect that the outer 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 20 to 25 dyne / cm, which was much lower than 39 dyne / cm of Comparative Example 1. Therefore, the antifouling property It is also known that the contaminants adhered to the surface are also desorbed well. 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. In particular, in Example 3, the light transmittance of the Al 2 O 3 protective layer / TiO 2 layer + SiO 2 layer, and the light transmittance of the Al 2 O 3 protective layer / SiO 2 layer / It was possible to obtain a coating having excellent adhesion, antifouling property, desorbing property of contaminants, water absorption rate, and bending property with good yield.

S1: Flexible underlayer formation step
S2: light transmittance and reflectance control layer formation step
S3: protective layer forming step
S4: step of forming friction reducing layer

Claims (8)

Forming a flexible undercoat layer on the plastic substrate;
Forming a light transmittance and reflectance control layer including a silicon oxide layer and a titanium oxide layer on the flexible undercoat layer;
Forming a protective layer including aluminum oxide or silicon carbide on the light transmittance and reflectance control layer; And
Forming a friction reducing layer comprising at least one selected from the group consisting of a fluorocarbon resin, a silicon fluoride resin, a polysiloxane resin and a polysilazane resin on the protective layer,
Wherein the step of forming the light transmittance and reflectance control layer, forming the protective layer, and forming the friction reducing layer are performed by a continuous deposition process under a pressure lower than atmospheric pressure in the same chamber. Coating method. Forming a flexible undercoat layer on the plastic substrate;
Forming a protective layer comprising aluminum oxide or silicon carbide on the flexible undercoat layer;
Forming a light transmittance and reflectance controlling layer including a silicon oxide layer and a titanium oxide layer on the protective layer; And
Forming a friction reducing layer on the light transmittance and reflectance controlling layer, the friction reducing layer including at least one selected from the group consisting of a fluorocarbon resin, a silicon fluoride resin, a polysiloxane resin and a polysilazane resin,
Wherein the step of forming the protective layer, forming the light transmittance and reflectance control layer, and forming the friction reducing layer are performed by a continuous deposition process under a pressure lower than atmospheric pressure in the same chamber, Coating method. The method of claim 1 or 2, wherein the forming of the flexible 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 substrate and photocuring Wherein the plastic substrate has a thickness of at least 10 mm. The method of claim 3, wherein the photocurable coating composition further comprises 5 to 20 parts by weight of an organic solvent. Plastic substrates;
A flexible undercoat layer formed on said plastic substrate;
A light transmittance and reflectance control layer including a silicon oxide layer and a titanium oxide layer as a light transmittance and reflectance control layer formed on the flexible undercoat layer;
A protective layer comprising aluminum oxide or silicon carbide as a protective layer formed on the light transmittance and reflectance control layer; And
And a friction reducing layer formed on the protective layer, the friction reducing layer comprising at least one member selected from the group consisting of a fluorocarbon resin, a silicone fluoride resin, a polysiloxane resin, and a polysilazane resin. Plastic substrates;
A flexible undercoat layer formed on said plastic substrate;
A protective layer comprising aluminum oxide or silicon carbide as a protective layer formed on the flexible undercoat layer;
A light transmittance and reflectance control layer including a silicon oxide layer and a titanium oxide layer as a light transmittance and reflectance control layer formed on the protective layer; And
And a friction reducing layer formed on the light transmittance and reflectance controlling layer, the friction reducing layer comprising at least one member selected from the group consisting of a fluorocarbon resin, a silicone fluoride resin, a polysiloxane resin and a polysilazane resin. 7. The method of claim 5 or 6, wherein the flexible 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, which is a cured product of the photocurable coating composition. The plastic coating according to claim 5 or 6, wherein the plastic 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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