KR20020034040A - UV Curable Back Light Ink and Prepartion Thereof - Google Patents

Abstract

PURPOSE: Provided is an ink for a UV curing type backlight of an LCD, which can prevent the change in quality compared to an ink for a thermosetting backlight and can improve the drying speed of the ink and the brightness of the backlight. CONSTITUTION: The ink for the UV curing type backlight is produced by a process comprising the steps of: mixing tetramethoxy silane and 0.1-1.0% HCl water solution in the weight ratio of 2:1-3:1; adding 20-50wt% of an acryloxy-functional silane to the mixture to obtain a colloidal silica solution of which the surface is treated by the acryloxy-functional silane, wherein the acryloxy-functional silane is at least one selected from the group consisting of acryloxypropyl trimethoxy silane, acryloxypropyl triethoxy silane, methacryloxypropyl methyl diethoxy silane, and etc.; adding 20-50wt% of hexanediol diacrylate to the silica solution; eliminating an alcohol solution and moisture; adding 5-15wt% of epoxy acrylate, 1-5wt% of isobutylbenzene ether, and 5-12wt% of a filler containing SiO2, TiO2, and BaSO4 having an average particle size of less than 10 micrometer.

Description

UV curable backlight ink and its manufacturing method {UV Curable Back Light Ink and Prepartion Thereof}

The present invention relates to a UV-curable backlight ink of a liquid crystal display (LCD) and a manufacturing method thereof, and more particularly, to a backlight ink in which scattering particles are dispersed in a colloidal silica binder surface-treated with acryloxyfunctional silane. And to a method for producing the same.

With the trend toward miniaturization and lightening of electronic products, the CRT (Cathode Ray Tube), which is mainly used for monitors such as televisions, measuring devices, and information terminal devices, is able to respond to the demands for small size and light weight due to its large weight and size. Could not. Therefore, the development of liquid crystal display (LCD), which has the advantages of small size and light weight, has been actively progressed in order to replace it, and in recent years, it is enough to play a role as a flat panel display device, and the demand is continuously increasing. have.

However, since the liquid crystal display (LCD) does not emit light by itself and only modulates the amount of transmitted light, a backlight assembly for uniformly irradiating a monitor screen using liquid crystal should be installed at the rear of the LCD panel. . The performance required for the backlight in the form of surface light source should be uniform in the luminance of the entire display surface, and sufficient luminance should be maintained in consideration that the transmittance of the liquid crystal panel is less than 10%.

As shown in FIG. 1, the conventional lamp assembly includes a backlight assembly installed at the rear of the LCD panel to transmit light to the front of the LCD panel. The backlight assembly is provided with a lamp assembly composed of a light emitting lamp 5 and a lamp reflector 4 at the rear edge of the LCD panel, and the light beam from the light emitting lamp 5 and the light beam from the lamp reflector 4 are disposed on the LCD panel 1. A light guide plate 6 is installed to uniformly guide the front of the light guide plate, and a reflecting plate 8 is attached to a rear surface of the light guide plate 6, and a diffuser plate 3 for diffusing and condensing the light guided from the light guide plate 6; Sheets such as the prism 2 are configured to be installed between the light guide plate 6 and the LCD panel 1. The lower part of the light guide plate 6 is printed in a pattern in which the ink is dot-shaped, and the portion near the lamp is made small and the far portion is formed of dots of larger size to control the amount of reflection and to have a uniform luminance distribution over the entire backlight surface.

The conventional backlight assembly configured as described above has been concentrated on the development of high brightness sheets, high brightness light emitting lamps, high brightness mechanism structures, etc., for high brightness and thinness, which are a measure for determining the technological competitiveness of a product.

Among them, the ink printed on the lower part of the light guide plate 6 has been studied in a thermosetting type. However, there is a disadvantage that the material is deteriorated by the heat generated during thermal curing and the drying speed is low. Therefore, in order to overcome such drawbacks, there is a need for a backlight ink which has a high drying speed and no possibility of material deterioration due to heat.

The present invention is to solve the above-mentioned problems, to improve the work efficiency by increasing the drying speed of the ink during the manufacture of the backlight ink, UV to prevent the deterioration of the material due to thermal curing by using the UV curing method It is an object to provide a method for producing a curable backlight ink.

In addition, another object of the present invention is to use a colloidal silica with better scattering effect and light transmittance than the conventional backlight ink, UV-curable backlight to maintain a uniform surface light source of the LCD by increasing the brightness of the uniform scattering particles It is to provide ink for.

1 is a schematic diagram of a prior art LCD backlight assembly.

2 is a conceptual view of the UV curing mechanism of the prior art.

3 is a schematic diagram of a UV-curable backlight ink layer according to the present invention.

4 is a schematic diagram of luminance measurement points of an LCD panel;

<Description of the symbols for the main parts of the drawings>

1 LCD Panel 2 Prism 3 Diffusion Plate

4 lamp reflector 5 light emitting lamp 6 light guide plate

7 dot printed layer 8 reflector 9 colloidal silica

10: filling material

In the method of preparing the UV-curable backlight ink of the present invention, after mixing the silane and the acid solution at 2: 1 to 3: 1 and reacting by controlling the time and temperature, a colloidal silica solution having a desired particle size is obtained, and then This month, the surface of the silica is acryloxyfunctional silane to obtain a colloidal silica having an acrylic functional group, and then a photoinitiator and a filler are added.

In the backlight generation method of the present invention, the UV-curable backlight ink prepared as described above is dot-printed on the bottom surface of the light guide plate of the backlight assembly of the LCD module, thereby efficiently scattering the light guided into the light guide plate and The surface light source is brought to the front.

Hereinafter, the present invention will be described in detail.

In the production method of the present invention, first, the vessel containing silane is slowly added dropwise to 0.1-1.0% HCl aqueous solution while maintaining the temperature at 40-60 ° C. At this time, the mixture of silane and HCl aqueous solution is 2: 1 to 3: 1 and mixed for 2 to 3 hours. If the ratio of silane is greater than or equal to the above range, no colloidal silica is formed, and if it is less than the range, the particle size of the colloidal silica is too large. Silanes that can be mixed include tetramethoxysilane and tetraethoxysilane with tetrafunctional groups or methyltrimethoxysilane with trifunctional groups. In addition, when the concentration of the HCl aqueous solution is more than the above range, the mixed solution is easily gelled, if less than the above range there is a problem that the colloidal silica is not formed.

Subsequently, 20 to 50% by weight of acryloxyfunctional silane was added to the solution having a colloidal particle size of about 20 to 100 nm and reacted at 40 to 60 ° C. for 2 to 3 hours to obtain a colloidal silica surface treated with acryloxyfunctional silane. Get When the addition ratio of acryloxyfunctional silane is more than the above range, ductility is not given to the coating film of the printed ink, so that a cracking phenomenon occurs, and when it is less than the above range, the adhesion of the coating film is inferior. Among the added acryloxyfunctional silanes, acryloxypropyltrimethoxysilane, acryloxypropyltriethoxysilane, acryloxymethyldimethylacryloxysilane, N- (3-acryloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, acryloxypropylmethyldimethoxysilane, methacryloxymethylphenyl methoxy oxy dimethyl aryl, methyl methoxy dimethyl dimethyl methyl methoxy dimethyl methyl methoxy Include.

After adding 20 to 50% by weight of acryl monomer to the solution, rotary evaporation is carried out at 40 ~ 50 ℃ to remove the alcohol solvent and water. If the addition ratio of the acryl monomer is above the above range, the physical properties of the coating film after printing is lowered, and below the above range, the viscosity increases when the solvent and water are removed. Acryl monomers that can be used here are hexanediol dicarylate, tripropyleneglycol diacrylate, polyethyleneglycol diacrylate, ethoxylated trimethylolpropane triacrylate, methyl methacrylate, 2-ethylhexyl acrylate, lauryl methacrylate, 2-hydroxyehtyl methacrylate, hydroxyethyl acrylate, glycidyl methacrylate, n-butyl acrylate, ethylhexyl methacrylate.

UV-curable backlight ink when 5 to 15% by weight of oligomer, 1 to 5% by weight of photoinitiator, and 5 to 12% by weight of filler were added to the colloidal silica solution obtained by the above method and then stirred at 40 ° C. or less for 30 minutes. Is obtained. If the oligomer addition ratio is greater than or equal to the above range, the viscosity is increased and screen printing workability is lowered. When the addition ratio of the photoinitiator is more than the above range, radical reaction by the photoinitiator continues to decompose the cured coating film, thereby lowering the durability, and when the photoinitiator is less than the above range, the curing rate is lowered. In addition, when the addition ratio of the filler is above the above range, the printability is inferior due to the increase in viscosity, and when it is below the above range, the scattering efficiency is lowered.

Usable oligomers include urethane acrylate, epoxy acrylate, epoxy methacrylate and melamine acrylate. Photoinitiators include 2-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl propanone, isobutylbenzoin ether, and 2,2-dimethyoxy-2-phenyl acetophenone. Fillers include SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , and BaSO ₄ .

The filler to be added is preferably used having an average particle size of less than 10㎛. By adding a filler, scattering of light guided into the light guide plate may be achieved.

An embodiment of the present invention is as follows.

<Production Example>

First, the vessel containing tetramethoxysilane is kept at 50 ° C. and 0.5% HCl aqueous solution is slowly added dropwise. At this time, the mixture of tetramethoxysilane and HCl aqueous solution was 2: 1 to 3: 1 and reacted for 3 hours. Subsequently, 40 wt% of acryloxypropyltrimethoxysilane was added and reacted at 50 ° C. for 3 hours to obtain colloidal silica whose surface was treated with acryloxypropyltrimethoxysilane. 40% by weight of hexanediol diacrylate was added to the resulting solution, followed by rotary evaporation at 45 ° C. to remove alcohol solvent and water.

In the colloidal silica solution obtained by the above method, a filler containing 10% by weight of epoxy acrylate, 3% by weight of isobutylbenzoin ether, and SiO ₂ , TiO ₂ , and BaSO ₄ with an average particle diameter of 7 μm was mixed in the same ratio. After the addition, it was dispersed for about 30 minutes with Dispermat (Germany, VMA-Getzmann) at 40 ° C. or less to prepare a UV-curable backlight ink.

<Comparative Manufacturing Example>

According to the prior art of the Republic of Korea Patent Application No. 2000-58772 of the present inventors, an acrylic copolymer having a molecular weight of 30% by weight and a molecular weight of 30,000 in a mixed solvent in which toluene, xylene and cyclohexanone are mixed in the same ratio composition Vinyl copolymer was dissolved. The solution was mixed with polydimethylsiloxane having a molecular weight of 25,000 containing ethylene oxide and propylene oxide, and then stirred for 2 hours at a speed of 300 rpm at a temperature of 130 ° C., and then the temperature was lowered to 60 ° C. or less, and tetraethoxysilane and methyl tetramethoxysilane were 8 weights. Methanol solution containing% was added dropwise for 2 hours. After maintaining for 1 hour under the same conditions, a solution of aminomethylpropanol and methanol in a 1: 1 weight ratio was added dropwise for 30 minutes, and maintained for 4 hours under the same conditions. Then, SiO ₂ , TiO ₂ , and BaSO having an average particle diameter of 7 μm were added. ₄ was added at the same ratio, and then mixed with Dispermat (VMA-Getzmann, Germany) for about 30 minutes to prepare a thermosetting backlight ink.

<Examples and Comparative Examples>

UV-curable backlight ink obtained according to the manufacturing example was dot-printed on the bottom surface of the light guide plate of the backlight assembly of the liquid crystal display (LCD) module and UV-cured using Fusion Lamp of Fusion Systems. At this time, the curing conditions were line speed of 7.7m / min, light quantity was 128.8mJ / cm ² . The thermosetting backlight ink obtained by the Comparative Production Example was also printed in the same manner as above and dried in an oven at 60 ° C. for 10 minutes.

Table 1 shows the points and the results of measuring the luminance on the LCD panel. As shown in Table 1, the printing by UV curing type than the thermosetting type shows about 5% (50-100 cd / m ² ) of luminance increase and the uniformity is improved.

point Comparative Example (Unit cd / m ² ) Example (Unit cd / m ² ) One 1935 1995 2 1919 2011 3 1914 1996 4 1958 2017 5 1919 1992 6 1780 1924 7 1727 1848 8 1836 1892 9 1888 1915 10 1892 1952 11 1832 1945 12 1748 1893 13 1811 1921 medium 5 points 1929 2002 13 points 1858 1946 Uniformity 5 points 1.02 1.01 13 points 12.43 8.77

As can be seen through the above examples and comparative examples, the UV-curable backlight ink according to the present invention not only prevents the deterioration of materials as compared with the thermosetting backlight ink, but also improves the drying speed of the ink and the brightness of the backlight. It is effective to improve.

Claims (5)

Tetramethoxysilane and 0.1 to 1.0% HCl aqueous solution were mixed so that the weight ratio was 2: 1 to 3: 1, and 20 to 50% by weight of acryloxyfunctional silane was added to the mixture to obtain a colloidal silica solution treated with acryloxyfunctional silane. After the addition of 20 to 50% by weight of hexanediol diacrylate to the silica solution, the alcohol solvent and water were removed, 5 to 15% by weight of epoxy acrylate, 1 to 5% by weight of isobutylbenzoin ether, and 5 to 12 fillers. Method for producing a UV curable backlight ink comprising the step of adding a weight%. The acryloxyfunctional silane to be added is acryloxypropyl. trimethoxysilane, acryloxypropyltriethoxysilane, acryloxymethyldimethyl Acryloxysilane, N- (3-acryloxy-2-hydroxypropyl) -3-aminopropyltriethoxysilane, acryloxypropyldimethylmethoxysilane, acryloxypropylmethyldimethoxysilane, methacryloxymethylphenyldimethylsilane, methacryloxyethoxytrimethylsilane, methacrylamidopropyltrimethoxysilane, methacryloxyemthylsilicone or more, selected from a group of more than 1acryloxymethoxyoxymethyl-methoxysilanes that include at least 1 Method for preparing ink The method of claim 1, wherein the filler contains less than 10 μm of SiO ₂ , TiO ₂ , and BaSO ₄ . UV-curable backlight ink obtained by the method of claim 1. The UV-curable backlight ink of claim 4 is dot-printed on the bottom surface of the light guide plate of the backlight assembly of the LCD module to effectively scatter visible light emitted from the cold cathode tube (CCFL) to maintain a uniform surface light source. A high brightness backlight generating method.