KR20030079112A - Coating agent of organic/inorganic hybrid type for display - Google Patents

Abstract

PURPOSE: Provided is an organic/inorganic hybrid type coating agent for display, which can improve light transmittance, gas permeation-protecting property, anti-scratching property and surface hardness of a plastic substrate and can increase the affinity between the substrate and silicon oxide layer. CONSTITUTION: The organic/inorganic hybrid type coating agent comprises 30-65 wt% of an acrylate oligomer, 0.5-4.5 wt% of an inorganic silane compound, 3.5 to 4.0 wt% of a photo-initiator, and 0.5 to 2.5 wt% of a surfactant, based on the total weight of the coating agent. The coating agent may further comprise 0.1 to 0.5 wt% of a catalyst. The coating agent is characterized in that it is susceptible to photo-curing and sol-gel bonding.

Description

Organic / inorganic hybrid type coating for display {Coating agent of organic / inorganic hybrid type for display}

The present invention relates to organic / inorganic hybrid coatings for displays.

Displays are widely used in electronic calculators, electronic clocks, car navigation systems, operation screens of office automation equipment, mobile phones, notebook computers and portable information communication terminals.

In the past, a glass substrate was used as a material of a display. However, due to the characteristics of the glass, the impact resistance is insufficient, it is easily broken by the impact, there is a limit to thinning, the weight per unit volume is difficult to light weight.

Therefore, the glass substrate has been replaced with a plastic film having impact resistance and flexibility. The display of plastic film material is 1/3 (compared to 0.7 mm thick glass) and the weight of 1/5 of the display of glass material, and has light weight, thinness, and impact resistance. However, plastic substrates have disadvantages of greater oxygen and water vapor transmission and weaker surface hardness and scratch resistance than glass substrates.

In particular, plastic substrates require high chemical resistance against organic solvents, acids, and alkalis used in electrode patterning, alignment films, and various cleanings, and are introduced into the liquid crystal cell of the panel by thermal expansion coefficient due to liquid crystal injection and process temperature. Oxygen or water vapor bubbles are generated, which affects the screen quality of the display.

In order to compensate for this disadvantage of the plastic substrate film, a gas permeation prevention film is applied and used. However, since the gas permeation prevention film is made of an inorganic layer such as silicon dioxide, and the plastic substrate film is made of an organic material, when the silicon dioxide layer of thin film is applied to the plastic substrate film by plasma or sputtering method, the plastic film, which is an organic material, is formed at a high process temperature. Cracks and warpage of the thin film layer, which is an inorganic material, may occur in the gas permeation prevention film due to a difference in thermal expansion coefficient. Therefore, an anchor layer having a medium thermal expansion coefficient between the plastic film and the inorganic layer is required. When a material having a thermal expansion coefficient between the plastic film and the silicon dioxide layer is present between the organic layer and the inorganic layer, the difference in thermal expansion coefficient between the two materials can be alleviated.

Accordingly, there is a need to alleviate the disadvantages caused by the difference in thermal expansion coefficient between the plastic film and the gas permeation prevention film, and to develop a display coating agent having strong solvent resistance.

The present invention solves the above problems, improves the light transmittance, gas permeability, scratch resistance, surface hardness of the plastic substrate, organic / inorganic hybrid coating for display to improve the affinity between the plastic substrate and the silicon oxide layer The purpose is to provide.

1 is a view showing the light transmittance according to the amount of 3-triethoxysilylpropyl isocyanate in the coating component of the present invention.

The present invention relates to organic / inorganic hybrid type coatings for displays, characterized by photocuring and sol-gel bonding.

The organic / inorganic hybrid coating agent for display of the present invention includes 30 to 65% by weight of acrylate oligomer, 0.5 to 4.5% by weight of inorganic silane compound, 3.5 to 4.0% by weight of photoinitiator and 0.5 to 2.5% by weight of surfactant.

In addition, the organic / inorganic hybrid coating agent for display may further include a catalyst, and includes 0.1 to 0.5% by weight.

The organic / inorganic hybrid type coating for display of the present invention is characterized by ultraviolet curing and sol-gel bonding.

Hereinafter, the components of the organic / inorganic hybrid coating agent for display of the present invention will be described in detail.

The acrylate oligomer of the coating component of the present invention is selected from the group consisting of urethane acrylate, epoxy acrylate, urethane / epoxy acrylate, ester acrylate, silicon-containing acrylate, pentaerythritol triacrylate, hydroxyalkyl acrylate It contains 1 or more types. Acrylate oligomers comprise 30 to 65% by weight relative to the coating. If the amount of acrylate is too large or too small, the flexibility of the coating film itself is easy to be broken, it is difficult to apply a uniform coating during coating, and the coating surface is uneven.

The inorganic silane compound in the coating component of the present invention is a polymer in which a vinyl Q resin is dispersed in a polydimethylsiloxane having a vinyl group, a vinyl methoxysiloxane polymer (VMM-010-100GM), and a polyphenylmethylsilsesquinoxane having a 10% methyl group. It includes at least one member selected from the group consisting of a polymer, phenylsilsesquinoxane and polydimethylsiloxane copolymer, polymethylsilsesquinoxane, and 3-triethoxysilylpropyl isocyanate. The inorganic silane compound contains 0.5 to 4.5 wt% based on the coating agent. Urethane acrylate has good physical properties but poor light transmittance. Therefore, in order to improve affinity such as heat resistance and transparency, an inorganic silane compound such as vinyl methoxysiloxane polymer is added and used.

The photoinitiator in the coating component of the present invention may be selected from known free radical type photoinitiators which are effective for promoting crosslinking reactions, mainly using ketone type photoinitiators. Photoinitiators include benzophenone, acetophenone, benzylaldehyde, benzaldehyde and O-chlorobenzaldehyde, xanthone, thioxanthone, 2-chlorothioxanthone, 9,10-phenanthrenequinone, 9,10-anthraquinone, methyl Benzoin ether, ethylbenzoin ether, isopropylbenzoin ether, α, α-diethoxyacetophenone, α, α-dimethoxyacetophenone, (1-phenyl-1,2-propanediol-2-O-benzoyl Oxime and at least one selected from α, α-dimethoxy-α-phenyl acetophenone, 2,4,6-trimethylbenzoyl-diphenyl phosphine (TPO), and are quinone series 2,4,6- Trimethylbenzoyl-diphenyl phosphine (TPO) is preferred. The photoinitiator comprises 3.5 to 4.0 wt% of the coating agent. When the photoinitiator is more than 4.0% by weight, the physical properties of the coating agent are affected, and the film is not formed well. If the photoinitiator is less than 3.5% by weight, the concentration becomes thicker, resulting in uneven coating surface.

The surfactant in the coating component of the present invention uses γ-aminopropyl triethoxysilane. The surfactant includes 0.5 to 2.5 wt% based on the coating agent. In general, the coating agent has a polar group, and since the plastic film does not have a polar group, the surface of the film is made uniform by inducing a strong adhesive force due to the formation of a bond between silicon and oxygen between layers by adding a surfactant.

The coating agent of the present invention may further comprise a catalyst, wherein the catalyst is dibutyltin dilau as well as an organometallic catalyst comprising a titanate such as tetraisopropylorthotitanate and tetrabutoxyortitanate Metal carboxylates such as late, dibutyltin dioctoate and the like, with dibutyltin dilaurate being preferred. The catalyst is used in the range of 0.1 to 0.5% by weight.

The manufacturing method of the organic / inorganic hybrid coating for display of the present invention is as follows.

After adding an acrylate-based polymer and an acrylate of a multi-functional group to an organic solvent, 1 to 5 g of a photoinitiator are added. After adding 1-20 g of inorganic silane compounds here, a small amount of dibutyl tin dilaurate is added and it reacts at 40-45 degreeC for 4 hours, and is manufactured. The organic / inorganic hybrid coating agent thus prepared is coated on the polyether sulfone film by solvent casting, and then dried to form a coating layer of a thin film by UV curing. Ultraviolet curing or heat curing is performed to prevent color fading and to withstand high temperatures, thereby reducing solvent resistance and intermolecular voids. In addition, after the coating on the optical film of the thin film to maintain the flexibility of the film, and to optimize the crosslinking density and flexibility.

The coating agent of the present invention forms a Si (EtO) ₃ on the surface by performing a sol-gel reaction between the hydroxyl group of the acrylate and the inorganic silane compound, thereby preventing the gas permeation prevention film and Si-O-Si covalent bond to be coated on the coating agent again. It is formed to improve the adhesion between the plastic film and the gas permeation prevention film, thereby increasing the crosslinking density of the film surface. This improves the gas permeation prevention film, chemical resistance and surface hardness.

The plastic substrate film for display to which the coating agent of the present invention is applied should be basically a film having good light transmittance, surface smoothness, optical anisotropy, mechanical strength, and thickness variation, and in addition to polyether sulfone film, polycarbonate, polyimide, polyarylate, Polyethylene naphthalate, polyethylene terephthalate, etc. can be used.

In order to obtain the coating of the present invention, conventional solvents and diluents are used. The solvent is toluene, xylene, butyl acetate, acetone, methyl isobutyl ketone, methyl ethyl ketone, methanol, ethanol, n-propanol, isopropanol, butanol, pentanol, hexanol, octanol, butoxyethanol, hexane, acetone, Ethylene glycol, monoethyl ether, mineral spirits, heptane and other aliphatic, cycloaliphatic, aromatic hydrocarbons, esters, ethers and ketones. If the amount of solvent is too small, the concentration becomes thick, and the coating surface becomes uneven during coating, and the coating liquid gathers everywhere, making it difficult to coat thinly. In addition, when the amount of the solvent increases, the viscosity becomes thin, so that the coating surface is not formed uniformly.

Hereinafter, the present invention will be described in more detail by the following examples, but the present invention is not limited to these examples.

Example 1 Preparation of Epoxyacrylate (EA) Coating Capable of Sol-Gel Reaction

10 g of epoxy acrylate and 1 g of 3-triethoxysilylpropyl isocyanate were added to a 250 ml flask filled with nitrogen. 100 ml of tetrahydrofuran (THF) was added and completely dissolved in a stream of nitrogen, followed by addition of a small amount of dibutyl tin dilaurate. It reacted at 45 degreeC for 4 hours. After completion of the reaction, the solvent was removed using a rotary evaporator, and the remaining solvent was removed using a vacuum pump.

Example 2 Preparation of Urethane Acrylate (UA) Coating Capable of Sol-Gel Reaction

In a 250 ml flask filled with nitrogen, 30 g of urethane acrylate, 0.5 g of 2-hydroxyethyl acrylate, 6.7 g of pentaerythritol triacrylate, and 1 g of 3-triethoxysilylpropyl isocyanate were added. 100 ml of butyl acetate was added and completely dissolved in a stream of nitrogen, and then a small amount of dibutyl tin dilaurate was added. It reacted at 40 degreeC for 4 hours. After completion of the reaction, the solvent was removed by a rotary evaporator, and then the remaining solvent was removed using a vacuum pump.

Experimental Example : Measurement of Physical Properties

In order to determine the light transmittance, hardness, scratch resistance, adhesion, heat resistance, and the like of the coating agent prepared in Examples 1 to 2, physical properties were measured.

In the experiment, UA is urethane acrylate, EA _x is a sample reacted with _x tri-ethoxysilylpropyl isocyanate with x weight content in epoxy acrylate, and VM _x is x weight content vinyl sample for mixed samples of UA and EA _x . It is a oxysiloxane polymer.

3-triethoxysilylpropyl isocyanate reacted at a weight ratio of 5 and 10% for EA _x , respectively.

After applying the coating agent prepared in Examples 1 to 2 to the plastic film, and dried at room temperature and 40 ℃ for about one day, some of them were dried for about 2 hours at 100 ℃ and then photopolymerized with ultraviolet light. The coating agent was coated with a coater to a thickness of 1 to 20 μm, and then cured with an ultraviolet curing machine. Completion of the photocuring was confirmed whether the reaction was completed by UV / VIS spectrometer.

The solvent used in each experiment was butyl acetate, the photoinitiator was 2,4,6-trimethylbenzoyl-diphenyl phosphine (TPO), the light irradiation time was 2 minutes, and the coating thickness was 1-20 micrometers.

Physical properties were measured using the following analyzers.

The light transmittance was measured using a UV / VIS spectrometer (8452A from Hewlett-Packard).

Oxygen permeation rate was measured at 35 ℃, 0% relative humidity of Mocon OX-TRAN 2/20 MB.

The water vapor transmission rate was measured at 37.8 ° C. and 100% relative humidity with Mocon Permatran W3 / 31 MG.

For pencil hardness, Mitsubishi pencil was used at 1kg load manufactured by our company.

The scratch resistance test was made of steel wool # 0000.

The adhesion test was performed using the tape test method, and the adhesion was measured by the number of grids apart for 25 squares of 2 mm x 2 mm.

In the heat resistance test, the change in appearance and the degree of warpage of the film were examined after heat treatment at 170 ° C. for 30 minutes.

Formulation composition of the coating used in the experiment (UA-EA _x mixing ratio of 6: 4 and 8: 2, 3-triethoxysilylpropyl isocyanate 10% weight ratio of EA _x ) and the results are shown in Table 1 and Table 2 is shown.

Furtherance Surfactant (γ-aminopropyl triethoxysilane) Reaction temperature Film thickness (㎛) Transmittance (400, 600nm) Adhesion (Tape Test) Hardness (pencil test) UA-EA ₁₀ (6: 4) - - Room temperature 4 81.0, 86.9 12 3 - - Room temperature-> 12 77.7, 85.5 11 One - - 40 ℃ 14 73.1, 84.2 15 2 - - 40 ℃-> 10 74.4, 83.1 12 2 - O Room temperature 7 71.1, 79.6 11 2 - O Room temperature-> 14 78.1, 84.8 14 3 - O 40 ℃ 16 78.4, 85.8 15 One - O 40 ℃-> 16 73.5, 86.1 11 3 VM ₁₀ - Room temperature 5 70.1, 77.0 7 2 VM ₁₀ - Room temperature-> 8 79.0, 85.2 8 3 VM ₁₀ - 40 ℃ 14 79.0, 86.6 4 4 VM ₁₀ - 40 ℃-> 10 68.8, 85.0 18 2

Furtherance Surfactant (γ-aminopropyl triethoxysilane) Reaction temperature Film thickness (㎛) Transmittance (400, 600nm) Adhesion (Tape Test) Hardness (pencil test) UA-EA ₁₀ (8: 2) - - Room temperature 4 78.6, 87.5 9 4 - - Room temperature-> 5 81.9, 90.57 10 3 - - 40 ℃ 5 71.48, 80.6 2 3 - - 40 ℃-> 5 74.1, 84.2 9 3 - O Room temperature 4 76.6, 81.5 11 3 - O Room temperature-> 6 76.4, 83.3 10 3 - O 40 ℃ 2 77.7, 85.6 2 4 - O 40 ℃-> 5 78.7, 85.6 3 4 VM ₁₀ - Room temperature 7 79.6, 87.4 8 3 VM ₁₀ - Room temperature-> 7 74.3, 83.7 11 4 VM ₁₀ - 40 ℃ 9 83.7, 90.7 12 4 VM ₁₀ - 40 ℃-> 10 76.3, 82.2 12 3

In addition, the formulation composition of the coating used in the experiment (UA-EA _x mixing ratio of 6: 4 and 8: 2, 3-triethoxysilylpropyl isocyanate 5% by weight of EA _x ) and the results are shown in Table 3 And in Table 4.

Furtherance Surfactant (γ-aminopropyl triethoxysilane) Reaction temperature Film thickness (㎛) Transmittance (400, 600nm) Adhesion (Tape Test) Hardness (pencil test) UA-EA ₀₅ (6: 4) - - Room temperature 7` 73.0, 83.2 0 4 - - Room temperature-> 6 82.3, 88.2 One 4 - - 40 ℃ 8 78.4, 84.1 4 3 - - 40 ℃-> 6 76.9, 84.7 0 4 - O Room temperature 15 85.8, 90.3 2 4 - O Room temperature-> 18 81.0, 86.8 2 4 - O 40 ℃ 15 80.2, 87.3 0 3 - O 40 ℃-> 19 80.4, 91.5 6 3 VM ₁₀ - Room temperature 10 81.4, 89.8 7 3 VM ₁₀ - Room temperature-> 19 74.5, 80.3 6 3 VM ₁₀ - 40 ℃ 20 80.5, 89.9 0 4 VM ₁₀ - 40 ℃-> 15 74.9, 83.9 One 3

Furtherance Surfactant (γ-aminopropyl triethoxysilane) Reaction temperature Film thickness (㎛) Transmittance (400, 600nm) Adhesion (Tape Test) Hardness (pencil test) UA-EA ₀₅ (8: 2) - - Room temperature 5 79.7, 83.1 One 4 - - Room temperature-> 7 69.5, 82.0 One 4 - - 40 ℃ 10 81.6, 88.7 9 2 - - Room temperature-> 5 75.6, 85.6 4 4 - O Room temperature 7 82.6, 89.4 One 4 - O Room temperature-> 6 85.2, 95.0 7 4 - O 40 ℃ 6 76.0, 85.5 5 4 - O Room temperature-> 10 82.5, 89.7 2 3 VM ₁₀ - Room temperature 7 80.2, 86.3 2 3 VM ₁₀ - Room temperature-> 10 73.3, 81.5 0 4 VM ₁₀ - 40 ℃ 9 73.5, 84.6 13 4 VM ₁₀ - Room temperature-> 10 82.1, 88.7 4 3

As shown in Table 1 to Table 4, it can be seen that the coating agent of the present invention maintains excellent levels of transmittance, adhesion, and hardness.

In particular, it was confirmed that UA-EA ₀₅ (6: 4) shown in Table 3 had the best transmittance, adhesion, hardness, and the like.

The results of the light transmittance are shown in FIG. 1.

The results of oxygen permeability and water vapor permeability are shown in Table 5.

Isocyanate Silane Compound (wt%) menstruum Film thickness (㎛) Water vapor permeability (g / m ² .day) 0 Butyl acetate 4 ~ 14 46 One Butyl acetate 2-12 42.49 5 Butyl acetate 4 ~ 14 42.69 10 Butyl acetate 4-12 37.91 15 Butyl acetate 5-12 46.75 20 Butyl acetate 5-15 45.68

It was observed that the water vapor permeability decreased to some extent as the amount of 3-triethoxysilylpropyl isocyanate compound increased, which was the best at 10wt%, and the oxygen permeability was also the best. When the amount of the 3-triethoxysilylpropyl isocyanate compound was 10 wt%, silicon oxide was precipitated thereon and observed. As a result, the water vapor permeability showed values of 3.3 at 750 kPa and 4.8 at 500 kPa.

Overall, the adhesiveness and hardness were improved in the samples using less 3-triethoxysilylpropyl isocyanate, the transmittance tended to decrease slightly, and some samples showed an increased phenomenon. This appears to be due to the evenness of the film surface rather than the result of the composition change of the sample. As a result of experiments by changing the type and concentration of solvent to find the factors affecting the film's evenness, it was observed that as the concentration increases, small islands on the surface of the film decrease.

In summary, the coating thickness of the film did not correlate with the measured physical properties. When the concentration was diminished, nodules were formed due to the relationship between the surface of the pure film and the solvent, and the sample was observed to have a slight viscosity to evenly distribute on the surface and form a smooth surface.

The coating agent of the present invention is capable of photocuring and sol-gel reaction by using a polyfunctional acrylate, improve solvent resistance, light transmittance, crosslinking density, and deformation of the substrate due to the difference in thermal expansion coefficient due to the addition of a silicon compound Prevention, gas permeability, surface hardness and affinity with the gas permeation prevention film containing silicon dioxide is effective.

Claims (12)

Organic / inorganic hybrid coating for display, comprising an acrylate oligomer, an inorganic silane compound, a photoinitiator, and a surfactant The method of claim 1, wherein the acrylate oligomer is in the group consisting of urethane acrylate, epoxy acrylate, urethane / epoxy acrylate, ester acrylate, silicon-containing acrylate, pentaerythritol triacrylate, hydroxyalkyl acrylate Organic / inorganic hybrid coating for display, characterized in that it comprises one or more selected The organic / inorganic hybrid coating agent for display according to claim 2, wherein the acrylate oligomer comprises 30 to 65% by weight relative to the coating agent. 2. The inorganic silane compound according to claim 1, wherein the inorganic silane compound is a polymer in which a vinyl Q resin is dispersed in a polydimethylsiloxane having a vinyl group, a vinyl methoxy siloxane polymer (VMM-010-100GM), and a polyphenylmethylsilsesquine having a 10% methyl group. Organic / inorganic for display, characterized in that it comprises one or more selected from the group consisting of oxane polymer, phenylsilsesquinoxane and polydimethylsiloxane copolymer, polymethylsilsesquinoxane, and 3-triethoxysilylpropyl isocyanate Hybrid coating The organic / inorganic hybrid coating agent for display according to claim 4, wherein the inorganic silane compound contains 0.5 to 4.5 wt% based on the coating agent. The photoinitiator of claim 1, wherein the photoinitiator is benzophenone, acetophenone, benzylaldehyde, benzaldehyde and O-chlorobenzaldehyde, xanthone, thioxanthone, 2-chlorothioxanthone, 9,10-phenanthrenequinone, 9 , 10-anthraquinone, methylbenzoin ether, ethylbenzoin ether, isopropylbenzoin ether, α, α-diethoxyacetophenone, α, α-dimethoxyacetophenone, (1-phenyl-1,2-propane Diol-2-O-benzoyl) oxime and at least one selected from α, α-dimethoxy-α-phenyl acetophenone and 2,4,6-trimethylbenzoyl-diphenyl phosphine (TPO) Organic / inorganic hybrid coatings for displays The organic / inorganic hybrid coating for display according to claim 6, wherein the photoinitiator comprises 3.5 to 4.0 wt% of the coating agent. The organic / inorganic hybrid coating for display according to claim 1, wherein the surfactant comprises γ-aminopropyl triethoxysilane. The organic / inorganic hybrid coating for display according to claim 8, wherein the surfactant comprises 0.5 to 2.5 wt% based on the coating agent. 10. The organic / inorganic hybrid coating for display according to claim 1, further comprising a catalyst. 11. The catalyst of claim 10, wherein the catalyst is not only an organometallic catalyst comprising a titanate such as tetraisopropylortho titanate and tetrabutoxy ortho titanate, but also dibutyltin dilaurate, dibutyltin dioctoate. Organic / inorganic hybrid coating for display, characterized in that it comprises one or more selected from the group consisting of metal carboxylates such as 12. The organic / inorganic hybrid coating for display according to claim 11, wherein the catalyst comprises 0.1 to 0.5% by weight.