KR20150078378A - Coating composition liquid composition, light guide plate and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a composition for a coating solution, a light guide plate formed therefrom, and a manufacturing method thereof, wherein the composition enables a coating layer for reflecting and shielding light with proper light-blocking properties and reflectance and excellent adhesion to be more simply and easily formed on the side of a light guide plate. The composition for a coating solution comprises: an acrylic polymer in which a first monomer including methyl methacrylate or styrene and a second monomer including one or more acrylic monomers are copolymerized; a pigment including a metallic oxide or a metallic sulfide; and an organic solvent. The composition for a coating solution is to form a coating layer for reflecting and shielding light by being applied and dried on the side of a light guide plate.

Description

TECHNICAL FIELD [0001] The present invention relates to a coating liquid composition, a light guide plate formed therefrom, and a method of manufacturing the same. BACKGROUND ART [0002]

The present invention relates to a coating liquid composition capable of forming a light reflecting and light shielding coating layer having appropriate light shielding properties and reflectivity and good adhesion property on the side face of a light guide plate more easily and a light guide plate formed using the same, .

2. Description of the Related Art In recent years, the use of liquid crystal display devices (LCDs) as a display device for monitors, notebook PCs, tablet PCs, navigation devices, TVs, and mobile phones has increased significantly. Such a liquid crystal display device needs to have a backlight unit as a separate light source, and such backlight unit needs to irradiate uniform light over the entire screen. Accordingly, the backlight unit can have a structure of an edge-lit type or a direct-lit type.

In particular, the edge-type backlight unit is configured such that light is incident from one side of the light guide plate using a point light source or a linear light source, and the light incident from the light guide plate is uniformly diffused as a surface light source to emit light uniformly throughout the liquid crystal cell. Unit. Such an edge type backlight unit is generally applied to a display device such as a notebook PC, a tablet PC, or a cellular phone which requires miniaturization. In recent years, such an edge type backlight unit has also been widely applied to a so-called LED TV that uses a light emitting device (LED) as a light source to reduce power consumption and TV thickness.

In the structure of such an edge type backlight unit, in order to utilize more light efficiently, a reflector is provided around a point light source or a linear light source on one side of the light guide plate, and in order to efficiently reflect light diffused to the back side of the light guide plate toward the liquid crystal cell, Reflectors are installed on the bottom and sides. This can lower the loss of light and brighten the screen of the liquid crystal display device. In addition, in the above-mentioned edge type backlight unit structure, a plurality of members such as the above-mentioned light guide plate, the lamp house accommodating the light guide plate, the reflection film, the diffusion film, the frame supporting the light guide plate, or the light- , Which results in cost reduction in terms of assembly process and component management.

Incidentally, in the above-described structure of the edge type backlight unit, it is required that the remaining side surface of the light guide plate on which the point light source or the linear light source is not provided exhibits excellent light shielding property and reflectivity. This is because, if the other side of the light guide plate does not exhibit such light shielding property and reflectivity, light incident on the light guide plate may be lost through the other side, causing light loss and light blurring at the end of the screen of the liquid crystal display device. A lamp house made of metal is generally used so that the remaining side surface of the light guide plate on which the point light source is not provided can exhibit excellent light-shielding property and reflectivity, or the light-shielding reflective tape is manually attached to a necessary side surface of the light guide plate.

However, when the light-shielding reflective tape is manually attached, the uniformity and complexity of the work process may be a problem. Particularly, since the edge type backlight unit includes a plurality of members described above and the work process for reflection and shielding is also complicated, there is a great demand for modularization and automation of the unit. In addition, since a liquid crystal display device and a backlight unit included therein are required to be thin in recent years, it is required to secure a high reflectance and a sufficient light-shielding property even if a light-shielding reflective tape is applied to a thinner light guide plate side. However, when the light-shielding reflective tape is manually attached to the side of the light guide plate having such a thin thickness, it may become difficult to precisely and uniformly adhere without contamination. Also, even when the light guide plate has a relatively large thickness, problems such as contamination by the operator, poor adhesion due to inconstant bonding pressure, poor brightness and light blocking property due to difficulty in uniform and precise bonding may occur. In addition, since the light-shielding reflective tape is manually attached, the complexity of the work process and the decrease in productivity may be a major problem.

In addition, in the case of a light-shielding reflective tape which has been used in the past, a reflective layer and a light-shielding layer having a certain reflectance and shielding ratio and a protective layer for protecting the layer are usually laminated on one surface of an insulating base material film, And the like. In addition, the total thickness of such a light-shielding reflective tape can be in the range of 250 to 350 [mu] m due to the shape of the multilayer sheet.

The complex structure of the light-shielding reflective tape has a disadvantage in that the unit price thereof is considerably high. In addition, when the thickness is reduced, there is a disadvantage in terms of reflectivity, light shielding property, adhesion property, durability and the like.

Due to such a problem of the prior art, the light-shielding reflective tape can be replaced and adhered to the side surface of the light guide plate with good adhesion, and while exhibiting the light-shielding property and the reflectance, And to develop alternative materials that can be automated.

Accordingly, it is an object of the present invention to provide a coating liquid composition which can more simply and easily form a coating layer for light reflection and light shielding, which exhibits appropriate light shielding properties and reflectivity, and excellent adhesion, on the side surface of a light guide plate.

The present invention also provides a light guide plate of an edge type backlight unit having a coating layer for light reflection and light shielding formed using the coating liquid composition and a method for manufacturing the same.

The present invention relates to an acrylic polymer in which a first monomer comprising methyl methacrylate or styrene and a second monomer comprising at least one acrylic monomer are copolymerized; A pigment comprising a metal oxide or a metal sulfide; And an organic solvent, and is coated on the side surface of the light guide plate and dried to form a coating layer for light reflection and light shielding.

The present invention also provides a light guide plate for an edge type backlight unit having at least one side on which light of a light source is incident, a front surface for emitting incident light toward the liquid crystal cell, and a back surface parallel to the front surface, An acrylic polymer in which a second monomer containing at least one acrylic monomer is copolymerized; And a coating layer for light reflection and light shielding formed on the other side of the light guide plate except for at least one side on which light of the light source is incident, the pigment including a metal oxide or a metal sulfide.

The present invention also provides a method of manufacturing a liquid crystal display device, comprising: applying the coating liquid composition on a side of a light guide plate of an edge type backlight unit on which light of a light source is not incident; And forming a light reflection and light shielding coating layer formed by drying the applied coating liquid composition.

Hereinafter, a coating liquid composition, a light guide plate and a method for manufacturing the same according to a specific embodiment of the present invention will be described.

According to an embodiment of the present invention, there is provided an acrylic polymer composition comprising: an acrylic polymer in which a first monomer containing methyl methacrylate or styrene and a second monomer containing at least one acrylic monomer are copolymerized; A pigment comprising a metal oxide or a metal sulfide; And an organic solvent, and is coated on the side surface of the light guide plate and dried to form a coating layer for light reflection and light shielding.

Such a coating liquid composition is a liquid composition containing an acrylic polymer of the same series as that of PMMA or the like which is a common material of a light guide plate. As a simplified method of coating and drying the side face of a light guide plate, a thinner thickness, for example, A light reflection and light shielding coating layer having a thickness of 200 mu m can be formed. Such a coating layer can exhibit excellent adhesion to the side surface of the light guide plate.

In particular, since the coating layer for light reflection and light shielding can be formed by a highly simplified process of coating and drying the coating liquid composition by an automated facility instead of the conventional method of manually attaching the tape, And can contribute greatly to quality and work process improvement by eliminating pollution, minimizing the maximum quality and minimum number of workers, shortening the work time, minimizing the work space, and facilitating the thin model.

Furthermore, since the light reflection and light-shielding coating layer formed using such a coating liquid composition can exhibit excellent light reflectance and low light transmittance, the light incident on the light guide plate at the side of the light guide plate can be coated on the coating layer So that light loss and light blurring at the end of the screen of the liquid crystal display can be greatly reduced.

Hereinafter, the coating solution composition will be described in more detail.

The coating liquid composition first comprises an acrylic polymer in which a first monomer containing methyl methacrylate or styrene and a second monomer containing at least one acrylic monomer are copolymerized.

In such an acrylic polymer, the first monomer may comprise methyl methacrylate or styrene or mixtures thereof, and the second monomer may be any acrylic compound, such as methyl acrylate, ethyl acrylate, n-butyl Acrylate, n-butyl methacrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, methacrylic acid, isopropyl methacrylate, 2-ethylhexyl acrylate, 1,6-hexanediol diacrylate Hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, acrylic acid, propyl acrylate, hexyl methacrylate, acrylamide, n-hexyl acrylate, hexyl acrylate, Acrylate, hydroxypropyl methacrylate, dimethacrylate, Aminoethyl methacrylate, tertiary-butylaminoethyl methacrylate and glycidyl may include dill methacrylate least one compound selected from the group consisting of.

The acrylic polymer may be copolymerized with the first monomer in an amount of 1 to 80% by weight based on the content of the second monomer in terms of excellent adhesion to the side face of the light guide plate and applicability.

The acrylic polymer may have a glass transition temperature of about 30 to 110 DEG C in terms of heat resistance or impact resistance of the coating layer formed from the coating liquid composition. In order to have such a glass transition temperature, the kind and composition of the above-mentioned first and second monomers can be adjusted within an appropriate range.

Although the molecular weight of the acrylic polymer is not particularly limited, the polymer may have a weight average molecular weight of 5000 to 300000, or 20,000 to 200,000. Thus, the coating layer formed using the coating liquid composition can have improved durability, and the coating property of the coating liquid composition and the like can be optimized.

On the other hand, the coating liquid composition of one embodiment includes the above-mentioned acrylic polymer together with a pigment containing a metal oxide or a metal sulfide. By including such a pigment, a coating layer formed from such a coating liquid composition can achieve excellent light reflectance and low light transmittance, thereby further reducing light loss on the side of the light guide plate.

(TiO ₂ ), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), or the like can be used as the above-mentioned pigments from the viewpoints of excellent light reflectance and low light transmittance. ₂ O ₃ , ZnO ₂ , Sb ₂ O ₃ , ZrO ₂ , ZnS, indium tin oxide (ITO), antimony tin compound oxide (ATO) titanium, antimony-tin composite oxide, tin oxide, lanthanum, cerium (CeO), yttria oxide (Y ₂ O _3), calcium carbonate, barium carbonate, zinc carbonate, calcium phosphate, barium sulfate, calcium sulfate, magnesium oxide, At least one inorganic particle selected from the group consisting of magnesium, silica, alumina, mica, mica titanium, talc, clay, kaolin, lithium fluoride and calcium fluoride can be used.

Among them, barium sulfate, titanium oxide, aluminum oxide and the like can be more preferably used in consideration of more excellent optical characteristics and stability of the coating layer. It goes without saying that two or more species selected from these may be used together. The barium sulfate, titanium oxide, aluminum oxide, or the like has a high refractive index and has a low light absorbance with respect to a visible light region of 380 to 780 nm. Therefore, when a coating layer is formed using this, the reflectance of the coating layer can be further improved, And can be advantageous in terms of low light transmittance, i.e., light shielding property.

On the other hand, in the case of titanium oxide usable as the pigment, titanium oxide having an anatase type or rutile type crystal structure can be more suitably used. In comparison with the anatase type, the rutile titanium oxide has a high refractive index because of its dense crystal structure, and thus the difference in refractive index between the rutile titanium oxide and the acrylic polymer becomes larger, and a higher reflectance of the coating layer can be obtained. Further, when rutile type titanium oxide is used, a coating layer having better weather resistance and heat resistance can be formed.

It is more preferable that the titanium oxide is surface-treated with a material selected from the group consisting of aluminum oxide, its hydrate, silicon oxide or its hydrate, amine compound and polyol compound. By such a surface treatment, it is possible to uniformly disperse the titanium oxide contained as a pigment in the coating liquid composition and to improve dispersion stability, and even when another resin other than the acrylic polymer is used, the affinity is improved and a more uniform composition Can be manufactured.

Specific examples of aluminum oxide or its hydrate, silicon oxide or its hydrate, amine compound and polyol compound which can be used in the surface treatment include alumina hydrate, silica hydrate, triethanolamine or trimethylolethane. The surface treatment method is not particularly limited, and can be treated by any method conventionally used for surface treatment of inorganic particles. The amount of the surface treatment agent to be imparted to the titanium oxide surface is not particularly limited. However, considering the light reflectivity of the titanium oxide and the affinity with the acrylic polymer or the like contained in the coating liquid composition, 10% by weight.

On the other hand, the above-mentioned pigment, for example, the particle size of the inorganic particles such as titanium oxide is not particularly limited, but it is preferable to have an average particle size of 0.1 to 0.5 占 퐉 in consideration of the optical properties and the dispersibility to the coating liquid composition . Among these, it is appropriate that the wavelength of light to be a target, that is, visible light, is about twice the particle size of the inorganic particles such as titanium oxide, so that the inorganic particles to be used as the pigment are preferably in the range of 0.2 - It is more preferable to have an average particle diameter of 0.4 mu m. If the particle diameter of the inorganic particles is excessively small, aggregation of the inorganic particles as pigments easily occurs and dispersion in the coating liquid composition may become difficult. On the contrary, if the particle size is too large, the reflectance of the coating layer to visible light may be lowered .

On the other hand, the coating liquid composition of one embodiment further comprises an organic solvent for preferably dispersing or dissolving the above-mentioned acrylic polymer and pigment. Examples of such an organic solvent include any solvent capable of well dispersing or dissolving the acrylic polymer and the pigment, for example, a hydrocarbon solvent, an ester solvent, a ketone solvent, an ether solvent and an alcohol solvent May be used.

More specific examples of such an organic solvent include hydrocarbon solvents such as toluene, xylene and heptane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethylacetate, butyl acetate, propylmethyl acetate and the like An ether solvent such as ethylene glycol ethyl ether and propylene glycol propyl ether; and an alcohol solvent such as isopropyl alcohol, butyl alcohol, methyl isobutyl carbinol and ethylhexanol, and the like. It is of course possible to use a mixture of two or more solvents selected from the above.

On the other hand, the coating liquid composition according to one embodiment of the present invention contains 50 to 95 parts by weight, or 60 to 90 parts by weight of the acrylic polymer, and 5 to 50 parts by weight of the pigment, based on 100 parts by weight of the solid content including the acrylic polymer and the pigment Or 10 to 40 parts by weight. In addition, the coating liquid composition can appropriately disperse and dissolve the acrylic polymer and the pigment in consideration of the amount of the acrylic polymer and pigment to be used. In addition, the coating liquid composition may contain an organic solvent in a content capable of more easily removing the organic solvent in a coating layer forming step have.

In one example, the coating liquid composition of one embodiment comprises 10 to 60% by weight of the acrylic polymer, 1 to 40% by weight of the pigment, and a residual organic solvent, based on the total composition including the organic solvent .

If the content of the pigment is excessively low or the content of the acrylic polymer is excessively high, the light shielding property of the coating layer becomes insufficient and the light reflectance becomes insufficient, resulting in light loss on the side of the light guide plate. On the other hand, if the content of the pigment becomes too high or the content of the acrylic polymer becomes too low, the stability of the coating liquid composition may be lowered or the durability of the coating layer may be lowered.

On the other hand, the coating liquid composition of one embodiment described above may further include one or more binders selected from the group consisting of a polyurethane resin, an alkyd resin, an epoxy resin, a melamine resin, a polyamideimide resin, a polyester resin and an elastomer .

Further, the coating liquid composition may further include at least one additive selected from the group consisting of a leveling agent, a wetting and dispersing agent, an anti-settling agent, a light stabilizer, and a defoaming agent. As such an additive, additives commonly used in conventional coating compositions including an acrylic binder can be used without any limitation. For example, a leveling agent containing polysiloxane or polyacryl as a main component may be used for improving the smoothness of the surface of the coating layer, a wetting or dispersing agent may be used for improving the dispersibility of the acrylic polymer and the pigment, Can be used. Various other additives may be additionally used, but these are well known to those skilled in the art, and a further explanation thereof will be omitted.

On the other hand, the above-mentioned coating liquid composition is prepared by dropping the above-mentioned first and second monomers together with a polymerization initiator into a reactor in an organic solvent for copolymerization, for example, a hydrocarbon solvent or an ester solvent, And then the copolymerization reaction is carried out while controlling the amount of the organic solvent to form the acrylic polymer, and then the organic solvent, the acrylic polymer and the pigment are mixed with each other. In order to mix the components, the organic solvent and the acrylic polymer are put into a stirrer to stir and mix the acrylic polymer so that the acrylic polymer dissolves, and then the pigment may be added to the stirrer to uniformly disperse it.

The coating liquid composition of one embodiment described above is excellent in light reflection and light shielding coating layer having excellent light resistance, heat resistance, abrasion resistance, flame resistance, thermal shock resistance, insulation property and the like and having high optical properties such as light reflectance and light- To be formed on the side surface of the light guide plate. Furthermore, such a coating liquid composition has a high drying rate, and thus enables a coating layer having good properties and a thin thickness to be formed very effectively on the side of the light guide plate. Such a coating layer exhibits excellent adhesion with PMMA or ABS, which is a common material of the light guide plate, .

According to another embodiment of the present invention, there is provided a light guide plate for an edge type backlight unit having at least one side on which light of a light source is incident, a front face for emitting incident light toward the liquid crystal cell, and a rear face parallel to the front face, An acrylic polymer in which a first monomer including methacrylate or styrene and a second monomer including at least one acrylic monomer are copolymerized; And a coating layer for light reflection and light shielding formed on the other side of the light guide plate excluding at least one side on which light of the light source is incident, the light guide plate comprising a pigment including a metal oxide or a metal sulfide.

Since the light reflection and light shielding coating layer formed from the coating liquid composition of one embodiment is formed on the other side of the light guide plate except for one side on which light is incident, the light reflection and light shielding coating layer has excellent light reflectance and light shielding property even at a thin thickness The loss of light incident on the light guide plate can be minimized. Particularly, unlike conventional tapes, such a coating layer can be easily formed in an automated process without manual work and can have a thinner thickness. Therefore, it is possible to make the light guide plate manufacturing process and the like much more efficient, and to provide a light guide plate having a thinner thickness and a liquid crystal display Can be very preferably applied.

In such a light guide plate, the coating layer may have a thickness of 20 to 200 占 퐉, or 50 to 150 占 퐉. When the thickness of the coating layer is too thin, optical properties such as reflectance or light shielding properties thereof may be deteriorated, thereby making it difficult to achieve necessary luminance and light leakage prevention. On the other hand, if the thickness of the coating layer is excessively increased, it may lead to deterioration of BLU assemblability, increase in cost as excess thickness over the original luminance performance, inhibition of display miniaturization, and deterioration in coating film durability.

The coating layer can exhibit a reflectance of 4.5 to 6% and a light transmittance of 0.1% or less when the reflectance of the mirror is 100% with respect to visible light at an appropriate thickness, and the appropriate reflectance and low light transmittance (excellent light shielding property) The loss of light incident on the light guide plate can be minimized.

According to another embodiment of the present invention, there is provided a method of manufacturing the light guide plate described above. Such a manufacturing method includes: applying a coating liquid composition of one embodiment to the side of the light guide plate of the edge type backlight unit on which light of the light source is not incident; And forming a light reflection and light shielding coating layer formed by drying the applied coating liquid composition.

In such a production method, the application step may be carried out by any application method applicable to a liquid composition such as roll coating, die coating, bar coating, gravure coating, rod coating, pad coating, dispenser coating or spray coating. Among these coating methods, it is preferable to combine a pad coating, a roll coating, a dispenser coating, or a spray coating on the basis of high workability, high quality of coated outer appearance, uniformity of light reflection, and precision.

The drying step may be performed by hot air drying, heating drying, infrared drying or near-infrared drying, or a combination of two or more of these methods may be carried out.

At this time, the drying step may be performed at 50 to 100 ° C or 60 to 100 ° C for 1 to 10 minutes. If the temperature of the drying step becomes excessively high, the light guide plate itself may be thermally deformed.

After the drying step, the light guide plate having the light reflection and light shielding coating layer may be further aged at room temperature for 1 to 5 days.

The coating layer for light reflection and light shielding having a thinner thickness can be formed very easily on the side of the light guide plate while exhibiting excellent durability, adhesion to the light guide plate, and optical characteristics in the above-described manufacturing process.

In the above description, the coating liquid composition of one embodiment is applied to a light guide plate of a liquid crystal display device. However, the present invention is also applicable to fluorescent tubes, LED, EL, plasma, and laser used in general lighting equipment, It is of course also possible to effectively use a product which simultaneously requires reflection and shading of light emitted from a light source.

According to the present invention, there is provided a coating liquid composition capable of forming a single layer of a light reflection and light shielding coating layer by a single application through an automatic coating facility instead of a complex multilayered light-shielding reflective tape. The coating layer formed using such a coating liquid composition can attain lightness, cost reduction, miniaturization, and the like through reduction in thickness while simultaneously achieving the same or higher level of reflection and shielding effect as compared with existing light-shielding reflective tape. In addition, the coating layer is excellent in light fastness, heat resistance, abrasion resistance, flame resistance, thermal shock resistance, insulation, etc., has a high drying speed and is excellent in storage stability even in a high temperature and high humidity environment. It can exhibit excellent optical characteristics even in a high temperature and high humidity environment and can exhibit a strong adhesion force with a plastic material such as a PMMA material of a light guide plate.

Therefore, the present invention can highly efficiently and simplify the process of forming the coating layer without minimizing the optical loss in the light guide plate, and can be preferably applied to a light guide plate and a liquid crystal display device having a thinner thickness.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

≪ Example 1 >

First, toluene 21 wt% was added to the four-necked flask reactor, and the temperature in the reactor was maintained at 100 to 105 DEG C, and then 37.5 wt% of methyl methacrylate, 5 wt% of isobutyl methacrylate, 6.3 wt , 0.9% by weight of acrylic acid and 0.2% by weight of azobisisobutyronitrile was added dropwise to the reactor over 150 minutes. After completion of the dropwise addition, the temperature in the reactor is adjusted to 110 to 115 DEG C and the acrylic copolymerization reaction is performed at this temperature for 180 minutes. Thereafter, a mixture of 4% by weight of toluene and 0.1% by weight of azobisisobutyronitrile was slowly added dropwise to the reactor and reacted at this temperature for 60 minutes. After the reaction, the temperature in the reactor was cooled to 60 to 70 캜, 16% by weight of n-butyl acetate and 9% by weight of methyl isobutyl ketone were added and diluted to prepare an acrylic polymer.

At this time, the glass transition temperature (Tg) of the acrylic polymer is 65 to 70 ° C and the molecular weight (Mw) is 10 to 150,000.

5% by weight of a dispersant, 2% by weight of a silicone defoamer, 6% by weight of ethyl acetate, 2% by weight of xylene and 9% by weight of methyl isobutyl ketone were added to 50% by weight of the acrylic polymer and stirred for 20 to 30 minutes.

After thoroughly stirring, 15 wt% of rutile titanium oxide was added and the titanium oxide average particle diameter was dispersed to 0.1 to 0.5 mu m.

After the dispersion as described above, the leveling first weight%, the sedimentation inhibitor 4 wt%, and the cyclochexanone 6 wt% were added and stirred for 30 to 40 minutes to form the coating liquid composition of Example 1.

≪ Example 2 >

Except that 50 wt% of Paroloid A-21 (PARALOID ^TM A-21, manufactured by The Dow Chemical Company) as an acrylic polymer, 25 wt% of toluene as a solvent for dissolving the same, 16% by weight of methyl isobutyl ketone and 9% by weight of methyl isobutyl ketone were mixed and stirred at 50 to 60 DEG C for 5 to 6 hours to completely dissolve the coating liquid composition. As the pigment, 15 wt% of the same rutile type titanium oxide as used in Example 1 was used.

The para Lloyd ^{A-21 (PARALOID TM A-} 21) is two weeks monomer configuration is composed of methyl methacrylate (MMA), molecular weight (Mw) is preferably from 10 to 15 manyi said glass transition temperature (Tg) of from 100 to 110 / RTI >

≪ Comparative Example 1 &

Lumiror E60L manufactured by Toray Industries, Inc. was used as a conventional white tape. (The adhesive tape is an adhesive tape described on the bottom surface of the tape. Manually attached by hand.)

≪ Comparative Example 2 &

In general, Balune BCP-80MT correction fluid, one of the most widely distributed white correction fluid products in Korea, was used.

≪ Comparative Example 3 &

Marastar SR 070 White (manufacturer: Marabu GmbH & Co. KG) inks used in displays and general industrial applications was used.

The Marastar SR 070 White has an average particle diameter of titanium oxide of about 7 μm or less. Applicable plastic materials include PMMA, acrylonitrile butadiene styrene (ABS), styrene acrylonitrile (SAN), and polycarbonate (PC)

Test Example 1: Measurement of average relative reflectance

First, a light reflection and light shielding layer was formed on the upper surface of the light guide plate by using the composition, tape or the like of each of the examples and comparative examples in the following manner. We used this as a specimen for reflectance measurement.

-. Examples 1 and 2: The upper surface of a light guide plate (PMMA material) was used as a base material of the substrate, and the coating liquid compositions of Examples 1 and 2 were coated with an applicator so as to have a dry film thickness of 90 to 110 탆.

-. COMPARATIVE EXAMPLE 1 The upper surface of a light guide plate (PMMA material) was used as a base material of the substrate, and a white tape of Comparative Example 1, which was conventionally applied, was directly adhered by a person who was a conventional mass production method.

-. Comparative Examples 2 and 3: The upper surface of the light guide plate (PMMA material) was used as the base material of the substrate, and the compositions of Comparative Examples 2 and 3 were coated with an applicator so as to have a dry film thickness of 90 to 110 탆.

For each specimen, the average relative reflectance was measured in the following manner.

A reflectance measuring attachment device (Shimadzu Corporation Cat. No. 206-14046) was attached to a UV-2450 spectrophotometer manufactured by Shimadzu Corporation, and a mirror was used as a standard plate to measure the reflectance of 380 nm to 780 nm The relative reflectance was measured at a wavelength range of 100% in a standard plate. More specifically, the reflectance of each 1 nm was measured in a wavelength range of 380 nm to 780 nm (visible light range), and the average value was used as an average reflectance. Finally, for comparison and analysis with a conventional white tape, And the average relative reflectance was calculated based on 100% of the average reflectance values.

The measurement results are summarized in Table 1 below.

Wavelength (380 to 780 nm) Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Maximum reflectance in the upper wavelength (%) 5.014 4.828 4.942 5.943 5.783 The lowest reflectance in the upper wavelength (%) 3.764 2.548 2.611 4.802 4.759 Average reflectance (%) 4.087 3.717 3.786 5.113 5.026 Average Relative Reflectance (%)
(Comparative Example 1 = 100%) 100% 90.9% 92.6% 125.1% 123.0%

Referring to Table 1, it was confirmed that the coating liquid compositions of Examples 1 and 2 exhibited excellent reflectance as compared with the tapes of Comparative Example 1 which were applied at the time of coating layer formation, Reflectance. Thus, it was confirmed that the coating layer can more effectively suppress the light loss of the light guide plate.

Test Example 2: Measurement of transmittance

First, a specimen for measuring transmittance was prepared in the same manner as in Test Example 1.

The transmittance of these specimens was measured by the following method.

The transmittance value per 1 nm was measured in a wavelength range between 380 nm and 780 nm (visible light range) in the thickness direction of the coating layer by using a UV-2450 spectrophotometer manufactured by Shimadzu Corporation, The average transmittance value was derived. Thereafter, for relative comparison and analysis with Comparative Example 1, an average relative transmittance of Comparative Example 1 was determined based on the relative transmittance of 100%. For reference, the average relative transmittance is preferably 98% or less, more preferably 95% or less.

The results of the measurement of the transmittance are summarized in Table 2 below.

Wavelength (380 to 780 nm) Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Maximum transmittance in the upper wavelength (%) 0.089 0.121 0.081 0.073 0.047 Minimum transmittance in the upper wavelength (%) 0.04 0 0.002 0 0.002 Average transmittance (%) 0.065 0.057 0.043 0.030 0.029 Average relative permeability (%)
(Comparative Example 1 = 100%) 100% 87% 66% 47% 45%

Referring to Table 2, it was confirmed that the coating liquid compositions of Examples 1 and 2 exhibited lower light transmittance (i.e., excellent light shielding property) than the tapes of Comparative Example 1 that were applied at the time of forming the coating layer, 3 shows excellent light shielding properties even in comparison with the coating layer formed of the composition of the present invention.

As a result, the coating layer of the embodiment can suppress the light leakage to the side of the light guide plate, and as a result, it is possible to obtain excellent whiteness and light shielding property, and to obtain a high luminance improvement effect when used for a liquid crystal display .

Test Example 3: Measurement of luminance

First, a light reflecting and light shielding layer was formed on the side surface of the light guide plate using the compositions or tapes of the examples and comparative examples in the following manner. This was used as a specimen for luminance measurement.

-. Examples 1 and 2: The side surfaces of the light guide plate (PMMA material) having a thickness of 2 mm were used as the substrate of the substrate, and the coating liquid compositions of Examples 1 and 2 were applied on the other side except the side of the light- The coating was applied using a dispenser to a dry film thickness of 90 to 110 탆.

-. Comparative Example 1 A white tape of Comparative Example 1, which had been conventionally applied to the other side surface except for the side of the light-incoming portion on which the edge type LED light source was provided, was used as a substrate of a light guide plate (PMMA material) The person was directly attached by hand.

-. COMPARATIVE EXAMPLES 2 and 3 The compositions of Comparative Examples 2 and 3 were applied to the sides of the light guide plate (PMMA material) with a thickness of 2 mm as a base material of the substrate, except for the side of the light entrance portion where the edge type LED light source was installed, (Dispenser) to a dry film thickness of 90 to 110 탆.

The brightness of each specimen was measured by the following method.

First, the backlight unit is provided with an edge-type LED light source on a light guide plate for a 23-inch monitor for evaluation, a reflective sheet on the bottom of the light guide plate, and two general optical sheets on the light guide plate. In addition, a light guide plate having a dot pattern formed on the lower surface of the light guide plate so that light incident on the light guide plate from the light source can be emitted upward. After the backlight unit was prepared as described above, the brightness of the LED light source was uniformly and constantly turned on for 30 minutes or more under a normal temperature environment, and then the PR-650 spectroradiometer (manufactured by Photo Research, Inc.) ) Was used to measure the vertical luminance at 17 points at a measurement distance of 50 cm. For the final luminance evaluation, a comparative evaluation of 100% of the conventional comparative example 1 was used, and the results were divided into one point relative luminance per point, five point average luminance relative comparison ratio, and 17 point average luminance relative comparison ratio.

For reference, the schematic diagram at the 17-point luminance measurement is as shown in the following figure 1, and the 1 point luminance is measured at the lower 1 position, and the 5 point average luminance is 1, 2, 4, And a mean value is calculated by measuring one point from each of the positions from 1 to 17 in the case of the average brightness of 17 points.

[Figure 1]

These luminance measurement results are summarized in Table 3 below.

The luminance (cd / m ² (nt) Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 1 point luminance 6937 6436 6464 7331 7233 5 point luminance 6552 6112 6009 6862 6811 17 point brightness 6337 5937 5817 6577 6507 1 point relative luminance relative ratio (Comparative Example 1 = 100%) 100% 92.8% 93.2% 105.7% 104.3% 5 point relative luminance relative ratio (Comparative Example 1 = 100%) 100% 93.3% 91.7% 104.7% 104.0% 17 points relative luminance relative rate (Comparative Example 1 = 100%) 100% 93.7% 91.8% 103.8% 102.7%

Referring to Table 3, it was confirmed that the optical loss was minimized from the light guide plate because the brightness was higher than that of the tape of Comparative Example 1, which was applied when forming the coating layer with the coating liquid compositions of Examples 1 and 2, It was confirmed that the brightness enhancement effect and the light loss suppression can be exhibited even in comparison with the coating layer formed of the composition of < RTI ID = 0.0 >

Claims (20)

An acrylic polymer in which a first monomer including methyl methacrylate or styrene and a second monomer including at least one acrylic monomer are copolymerized;
A pigment comprising a metal oxide or a metal sulfide; And
An organic solvent,
And coating and drying the coating on the side surface of the light guide plate to form a coating layer for light reflection and light shielding.
The coating liquid composition according to claim 1, wherein the first monomer is copolymerized in an amount of 1 to 80% by weight based on the content of the second monomer.
The composition of claim 1, wherein the second monomer is selected from the group consisting of methyl acrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, Propyl methacrylate, 2-ethylhexyl acrylate, 1,6-hexanediol diacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, cyclohexyl methacrylate, acrylic acid, propyl acrylate , Hexyl methacrylate, acrylamide, n-hexyl acrylate, hexyl acrylate, hydroxy methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, tertiarybutylaminoethyl methacrylate and glycidyl Methacrylic acid and one or more selected from the group consisting of Based coating composition comprising a cryol-based monomer.
The coating liquid composition according to claim 1, wherein the acrylic polymer has a glass transition temperature of 30 to 110 캜.
The coating liquid composition according to claim 1, wherein the acrylic polymer has a weight average molecular weight of 5,000 to 300,000.
The method of claim 1, wherein the pigment is selected from the group consisting of titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO ₂ ), antimony oxide (Sb ₂ O ₃ ) (ZrO ₂ ), zinc sulfide (ZnS), indium tin compound oxide (ITO), antimony tin compound oxide (ATO), titanium antimony-tin compound oxide, tin oxide, lanthanum oxide, cerium oxide ₂ O ₃ ), calcium carbonate, barium carbonate, zinc carbonate, calcium phosphate, barium sulfate, calcium sulfate, magnesium sulfate, magnesium oxide, silica, alumina, mica, talc, clay, kaolin, lithium fluoride and calcium fluoride And at least one inorganic particle selected from the group consisting of the inorganic particles.
The method according to claim 6, wherein the pigment comprises titanium oxide which has been surface-treated or surface-untreated with a material selected from the group consisting of barium sulfate, aluminum oxide or aluminum oxide or its hydrate, silicon oxide or its hydrate, amine compound and polyol compound Lt; / RTI >
7. The coating liquid composition according to claim 6, wherein the pigment has an average particle diameter of 0.1 to 0.5 mu m.
The coating liquid composition according to claim 1, wherein the organic solvent comprises at least one solvent selected from the group consisting of a hydrocarbon solvent, an ester solvent, a ketone solvent, an ether solvent and an alcohol solvent.
The coating fluid composition according to claim 1, which comprises 50 to 95 parts by weight of the acrylic polymer and 5 to 50 parts by weight of the pigment based on 100 parts by weight of the solid content including the acrylic polymer and the pigment.
The coating liquid composition according to claim 1, further comprising at least one binder selected from the group consisting of a polyurethane resin, an alkyd resin, an epoxy resin, a melamine resin, a polyamideimide resin, a polyester resin and an elastomer.
The coating liquid composition according to claim 1, further comprising at least one additive selected from the group consisting of a leveling agent, a wetting and dispersing agent, an anti-settling agent, a light stabilizer, and a defoaming agent.
1. A light guide plate of an edge type backlight unit having at least one side on which light from a light source is incident, a front surface for emitting incident light toward the liquid crystal cell, and a back surface parallel to the front surface,
An acrylic polymer in which a first monomer including methyl methacrylate or styrene and a second monomer including at least one acrylic monomer are copolymerized; And a coating layer for light reflection and light shielding formed on the other side of the light guide plate except for at least one side on which light of the light source is incident, the light guide plate comprising a pigment comprising a metal oxide or a metal sulfide.
14. The light guide plate according to claim 13, wherein the coating layer has a thickness of 20 to 200 mu m.
The light guide plate according to claim 13, wherein the coating layer exhibits a reflectance of 4.5 to 6% and a light transmittance of 0.1% or less when the reflectance of the mirror is 100% with respect to visible light.
Applying the coating liquid composition of claim 1 on a side of the light guide plate of the edge type backlight unit on which light of the light source is not incident; And
And forming a light reflection and light shielding coating layer formed by drying the applied coating liquid composition.
The method of manufacturing a light guide plate according to claim 16, wherein the applying step is performed by roll coating, die coating, bar coating, gravure coating, rod coating, pad coating, dispenser coating or spray coating.
The method of manufacturing a light guide plate according to claim 16, wherein the drying step is performed by hot air drying, heat drying, infrared drying, or near-infrared drying.
The method of manufacturing a light guide plate according to claim 16, wherein the drying step is performed at 50 to 100 ° C for 1 to 10 minutes.
The method of manufacturing a light guide plate according to claim 16, further comprising, after the drying step, aging the light guide plate having a coating layer for light reflection and light shielding at room temperature for 1 to 5 days.