KR101360885B1 - Light Diffusive Ink Composition, Light Guide Panel And Back Light Unit Using The Same - Google Patents

Abstract

The present invention provides an ink binder selected from the group consisting of an acrylic resin and a vinyl chloride-vinyl acetate copolymer; A light diffusing agent having a particle size of 0.8 µm to 3 µm; A light diffusion ink composition including an ink solvent, a light guide panel, and a backlight unit using the same are disclosed.
According to the present invention, the light guide panel can be made slim, and the electronic device can be made thinner and lighter, and fine patterns can be formed, and the dot pattern eliminates white dots and brightness that can appear on the surface of electronic devices such as LCDs. The lowering can be prevented and the printability of the ink can be improved.

Description

Light Diffusive Ink Composition, Light Guide Panel And Back Light Unit Using The Same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusion ink composition, and more particularly, to a light diffusion ink composition that can cope with slimming (thinning of a light guide plate member) and a light guide panel and a backlight unit using the same.

In general, the light guide panel is an illumination component for emitting light in the form of a surface light source having a uniform brightness by receiving light from a light source, and is applied as a component for implementing a backlight unit (BLU) of a liquid crystal display (LCD).

The surface of the light guiding panel used for manufacturing the light guiding panel, for example, plastic or glass, or the surface of the light guiding member or thin light guiding film is cut by using a laser processing technique, so that a scratch or a dot is formed on the surface of the light guiding panel. When a pattern is formed in the form of a light source, the light guide panel emits light in the form of a surface light source by scattering / refracting / reflecting light of the light source.

As another method of forming a dot-shaped pattern on the light guide plate member, there is a method of coating (printing) the light diffusion ink composition on the surface of the light guide plate member to improve the amount of light (brightness).

On the other hand, in recent years, the development of electronic devices has been progressed to light weight and thinning. For example, in order to reduce the weight and thinness of a liquid crystal display device (hereinafter, referred to as an LCD), which is a display device, a large portion of the LCD thickness is used. It is necessary to slim down the backlight unit.

However, a conventional backlight unit having a light guide panel having a dot pattern formed by a light diffusion ink composition as described above, in particular, an edge-lit backlight unit for installing a light source at an edge of the light guide plate for slimming the LCD. In the case of, when the thickness of the light guide plate is reduced to 5T (5 mm), especially 4T (4 mm) or less in order to slim down the thickness of the LCD, the light-receiving portion of the light guide plate member (the part where light is incident) is As the amount of light transmitted decreases and moves away from the light incidence part, there is a problem in that the amount of light emitted forward from the light guide plate material is significantly reduced and darkened.

In addition, when the thickness of the light guide plate on which the dot pattern is formed by the light diffusion ink composition is reduced, white dots (white dots) by the dot pattern are exposed in front of the backlight unit, for example, the surface of the LCD, thereby revealing There is a problem that causes a poor appearance on the screen.

Accordingly, the present inventors have developed a light diffusion ink composition capable of emitting light to the light source evenly over the entire surface of the light guide plate and at the same time improving the white dots described above, and a light guide panel and a backlight unit using the same.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and includes a light diffusing ink composition capable of removing white dots and improving luminance by a dot pattern, and a light guide panel and a backlight unit which can be made slim by forming a fine dot pattern using the same. The purpose is to provide.

Another object of the present invention is to provide a light diffusion ink composition having an improved refractive index.

Still another object of the present invention is to provide a light diffusion ink composition having a low thixotropy index, which facilitates the formation of a dot pattern.

In order to solve the above object, the present invention is an ink binder selected from the group consisting of acrylic resin and vinyl chloride-vinyl acetate copolymer; A light diffusing agent having a particle size of 0.8 µm to 3 µm; And it provides the light-diffusion ink composition containing an ink solvent.

The light diffusing agent may be at least one selected from the group consisting of PMMA (Polymethylmethacrylte) particles and silicon particles. The PMMA particles and the silicon particles are included in an amount of 25 to 200 parts by weight based on 100 parts by weight of the ink binder, alone or in combination.

The light diffusing agent may include silica particles. The silica particles contain 10 to 80 parts by weight based on 100 parts by weight of the ink binder.

In addition, the light diffusing agent is preferably a particle size of 0.8㎛ ~ 2㎛.

On the other hand, the ink solvent, but may be selected from the group consisting of ketones, ethers and petroleum solvents, but is not limited thereto.

The light diffusion ink composition according to the present invention; It is preferable to further include at least one auxiliary particle selected from the group consisting of titanium oxide (TiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) having a particle size of 0.05 μm to 4 μm, respectively.

The auxiliary particles may include 1 to 70 parts by weight based on 100 parts by weight of the ink binder, but is not limited thereto.

The light diffusion ink composition according to the present invention; A dispersant for lowering the thixotropic index of the ink, for example, an acrylic copolymer-based dispersant may be further included. The dispersant is included in the light diffusion ink composition to lower the thixotropy index of the ink to 2 or less.

In another aspect, the present invention provides a light guide panel including a light guide plate material and a pattern formed by a light diffusion ink composition coated on the light guide plate material, and a backlight unit having the same; The light diffusion ink composition is; At least one ink binder selected from the group consisting of an acrylic resin and a vinyl chloride-vinyl acetate copolymer, a light diffusing agent and an ink solvent having a particle size of 0.8 μm to 3 μm.

The thickness of the light guide plate material is characterized in that up to 4mm, more specifically 3mm or less.

The pattern may be a dot-shaped pattern having a maximum size of 400 μm, more specifically 300 μm or less.

According to the light diffusing ink composition and the light guide panel and the backlight unit using the same according to the present invention, the following effects are obtained.

First, according to the present invention, the light guide panel can be made slimmer and thinner and lighter in electronic devices, and fine patterns can be formed, and the dot pattern eliminates white dots that may appear on the surface of electronic devices such as LCDs. And lowering of luminance can be prevented.

Secondly, according to the present invention, the printability of screen-printing the light-diffusing ink composition on the light guide plate may be improved, and the quality of the backlight unit may be improved, and the thixotropy index of the ink may be reduced to facilitate formation of a fine dot pattern. Furthermore, the refractive index of the ink may be improved, thereby improving the brightness of the light guide panel.

1 is a perspective view showing a schematic structure of an embodiment of a backlight unit having a fine dot pattern formed by a light diffusion ink composition according to the present invention.
2A and 2B are cross-sectional views illustrating a light guide panel according to the present invention.
3 is a light reflectivity showing the incidence / reflection of light.
4 is a plan view illustrating the luminance of each part of specific embodiments of the backlight unit according to the present invention.
5 are micrographs of a dot pattern.

Hereinafter, exemplary embodiments of a light diffusion ink composition and a light guide panel and a backlight unit using the same according to the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, the same reference numerals are used for the same configurations.

One embodiment of the light diffusion ink composition according to the present invention comprises an ink binder (Ink Binder), a light diffusing agent and an ink solvent. Here, the light diffusion ink composition may further include a dispersant and / or an additive.

The ink binder may be at least one selected from the group consisting of an acrylic resin and a vinyl chloride-vinyl acetate copolymer. In other words, the acrylic resin and the vinyl chloride-vinyl acetate copolymer may be used alone or in the light diffusion ink composition.

Next, the ink solvent may be selected from the group consisting of ketones, ethers and petroleum solvents, but is not limited thereto. Examples of the ketone solvents include isophorone and cyclohexanone, and examples of the ester solvents include butyl ketitol acetate and ethyl ketitol acetate. Examples of the ether solvents include butyl ketitol and ethyl kebitol.

The petroleum solvent may be a hydrocarbon solvent or the like. The ink solvent may be constituted by mixing one or more of the above-described ketones, esters, ethers, and petroleum solvents in combination.

Next, in the present invention, the light diffusing agent corresponds to the thinning of the electronic device and has a particle size of 0.8 μm to 3 μm for the improvement and uniformity of the brightness, and the type of the light diffusing agent is PMMA (polymethylmethacryl). Polymethylmethacrylate) particles, silicon particles, urethane particles, nylon particles, and the like, but in terms of light transmittance, the PMMA particles and silicon particles are preferable to the urethane particles and nylon particles, and silica particles may be used.

In the present embodiment, the light diffusing agent may be selected from the group consisting of the PMMA particles, silicon particles and silica particles. Therefore, the PMMA particles, the silicon particles, and the silica particles may be used alone or in combination of two or more kinds to form a light diffusing agent of the light diffusion ink composition according to the present invention.

In the present invention, the light diffusing agent, more specifically, the PMMA particles, silicon particles, and silica particles have a particle size of 0.8 μm to 3 μm, more specifically, 0.8 so as to cope with thinning and weight reduction of the electronic device as described above. It has an average particle size of micrometer-3 micrometers, More preferably, it is good that particle size, ie, average particle size is 0.8 micrometer-2 micrometers.

1 to 3, a conventional general light diffusion ink composition and a light diffusion ink composition according to the present invention may be used to implement the light guide panel 110 and the backlight unit 100, wherein the backlight unit 100 is used. ) Is configured to include the light guide panel 110 and a light source 120 that emits light toward the light guide panel 110.

The conventional general light diffusion ink composition and the light diffusion ink composition according to the present invention are coated on the light guide plate 111 in the form of dots to form the dot pattern 120 on the surface of the light guide plate 111. Dot pattern '), and the light source 120 is provided at one side of the light guide plate 111, particularly at a corner of the light guide member to emit light toward the light guide plate 111.

The light guide plate 111 is preferably made of a thin film, that is, a thin film of less than 5T (5mm), more preferably 4T (4mm) in order to realize a thinner and lighter weight of the electronic device, the conventional light guide plate As the thickness of the material 111 is reduced, the dot pattern 112 has a problem that white dots appear on the LCD screen and the luminance is not uniform and is degraded.

In more detail, when the thickness of the light guide plate 111 decreases from t ₁ of FIG. 2A to t ₂ as shown in FIG. 2B, the dot pattern 112 is formed on the surface of the light guide plate 111. The parts appear bright with white spots, which impairs the uniformity of the light and causes poor image quality on the LCD screen. In other words, a diffusion sheet (not shown) is generally stacked on the light guide plate 111, and as the thickness of the light guide plate 111 becomes thin, the dot pattern 112 is moved forward through the diffusion sheet. The light emitted as may be expressed in the form of the white spot described above.

On the other hand, the dot pattern 112 is formed at the same position of the light guide plate material having a different thickness (one vertex of the rectangular light guide plate material of the same area having different thickness is the origin of the XY coordinate plane and the same (x, y) coordinates when the dot pattern when the basis of the state) is formed to, the light guide member 111 having a reduced thickness in the t ₂ Figure 2a in FIG. 2b from t ₁ of, for example, reduced to less than 4T, the dot pattern The incident angle of the light incident on the 112 is relatively large as shown in FIG. 2B, whereby the opposite side edge of the light incident portion 111a of the light guide plate 111 (one edge of the light guide plate facing the light source) is formed. The amount of light transmitted in the direction of 111b is reduced, so that the brightness is remarkably reduced on the opposite side 111b of the light incident portion 111a.

In addition, as the particles of the light diffusing agent become larger, the amount of light transmitted from the light incidence portion 111a of the light guide plate 111 toward the opposite edge 111b is reduced, so that the brightness is opposite from the light incidence portion 111a. Shows a phenomenon that greatly decreases, but the experimental result is determined to be due to the phenomenon that the light scattered more than the light reflected by the dot pattern 112 is increased, according to the present invention, the average particle size of 0.8㎛ ~ 3㎛, Preferably, a light diffusing agent having an average particle size of 0.8 μm to 2 μm is used to reduce the amount of light transmitted from the light incidence portion 111a of the light guide plate 110 to the opposite side 112b.

In addition, in order to improve the occurrence of the white spot phenomenon on the surface of the light guide plate 111 as the thickness of the light guide plate 111 becomes thin, in the present invention, the size of the dot pattern 112 (in the case of a circular dot pattern) Diameter) to 400 μm or less, more specifically 300 μm or less, and thus, the density of the dot patterns 112 may be increased and white spot phenomenon may be improved.

In general, in order to form the dot pattern by coating a light diffusion ink composition on the surface of the light guide plate 111, a screen printing method using a mesh is applied.

Here, in order to coat the light-diffusion ink composition on the surface of the light guide plate 111 so that the size of the dot pattern 112 is 400 μm or less, the resolution is improved by using a mesh of 325 mesh or more. The opening size of the 325 mesh is 43 Micron (μm) as shown in Table 1 below.

Based on the opening size of the mesh, less than tenths of particles (light diffusing agent) of the opening size should be used for good mesh dropping when screen printing, and when using the 325 mesh, a particle size of about 4 μm or less is used. Since the light diffusing agent may be applied, the particle size of the light diffusing agent may be 0.8 μm to 4 μm, but the density of the dot pattern 112 may be improved and the dot pattern 112 may be formed to a size of 300 μm or less. In order to be able to use a mesh of 400 mesh or more at the same time, and to realize a high resolution without affecting the omission of the mesh, a light diffusing agent having a particle size of 3 µm or less, especially 0.8 µm to 2 µm or less is preferable.

Mesh specification (standard)
Mesh Opening (opening) Mesh wire
Inch opening
Area rate (%) Inch Micron (μm) 200 0.0029 74 0.0021 33.6 250 0.0024 61 0.0016 36.0 270 0.0021 53 0.0016 32.0 325 0.0017 43 0.0014 30.5 400 0.0015 38 0.0010 36.0 500 0.0010 25 0.0010 25.0 635 0.0008 20 0.0008 25.0

The reason why the particle size of the light diffusing agent is 0.8 μm or more is that the difference in refractive index between the PMMA particles and the silicon particles is smaller than or equal to that of the ink binder, so that the particle size is 700 nm (0.7 μm) in the visible light band. This is because the light scattering property is lowered when the value is less than or equal to).

Of course, inorganic particles such as titanium oxide (TiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) have a large refractive index difference from the ink binder and thus do not significantly affect light scattering characteristics even at a particle size of 0.8 μm or less, and thus, 0.05 μm to 4 μm. Among the inorganic particles, the silica particles have a low refractive index (1.43), such that the PMMA particles and the silicon particles are 0.8 μm to 4 μm, and more preferably, fine pattern formation and ease of screen printing. For this purpose, 0.8 µm to 3 µm, in particular 0.8 µm to 2 µm, is preferable.

Hereinafter, one embodiment of the light diffusion ink composition to which the PMMA particles and / or the silicon particles are applied as the light diffusing agent and another embodiment of the light diffusion ink composition to which the silica particles are applied as the light diffusing agent will be described. .

First, in one embodiment of the light diffusion ink composition (applying the PMMA particles and / or the silicon particles as the light diffusing agent), the PMMA particles and / or the silicon particles are 25 to 100 parts by weight of the ink binder. It is disclosed that 200 parts by weight is included in the light diffusion ink composition, and when the PMMA particles and / or the silicon particles are less than 25 parts by weight, the light diffusion effect is lowered so that the light intensity is significantly lowered. As a result, the total light transmittance may be lowered, the light diffusing effect may be lowered, and screen printing workability may be lowered.

When the PMMA particles and / or the silicon particles are applied as the light diffusing agent, the ink solvent may include 110 to 470 parts by weight based on 100 parts by weight of the ink binder.

In addition, in forming the fine dot pattern using the screen mesh on the light guide member, the thixotropy index of the ink affects the formation of the dot pattern. Therefore, the ink composition according to the present invention may further comprise the dispersant in order to lower the thixotropic index according to the thixotropic index of the ink.

In more detail, when the weight ratio of the light diffusing agent and the ink binder is higher than a predetermined ratio, for example, one-to-one (1: 1), the addition of the dispersant to the light-diffusing ink composition may occur. good. In the present embodiment, the dispersant may be introduced so that the thixotropy is 2 or less, but is not limited thereto. Examples of the dispersant include a known acrylic copolymer-based dispersant, and the dispersant may be included in 100 parts by weight of the ink binder. It includes 2.5 to 20 parts by weight, but is not limited thereto, and may be changed according to design conditions.

In addition, the light diffusion ink composition may further include one or more additives such as an antifoaming agent and a leveling agent. The amount of the additive may be variously adjusted according to design conditions, but the present embodiment discloses that 1 to 15 parts by weight of the additive is included with respect to 100 parts by weight of the ink binder.

On the other hand, the light diffusion ink composition according to the present invention may further include auxiliary particles for improving the light diffusion efficiency by increasing the refractive index of the ink. The auxiliary particles include inorganic particles such as titanium oxide (TiO ₂ ) and aluminum oxide (Al ₂ O ₃ ). The refractive index of the titanium oxide is about 2.4 to 2.7 and the refractive index of the aluminum oxide is about 1.7, according to the present invention. The refractive index of the light diffusion ink composition can be improved.

The auxiliary particles are disclosed to be mixed at 0.5 wt% to 10 wt% of the total weight of the light diffusion ink composition, but are not limited thereto. The (average) particle size of the auxiliary particles is 0.05 μm to 4 μm, more preferably. It is disclosed that it is 0.1 micrometer-3 micrometers especially 0.1 micrometer-2 micrometers.

Specific examples of one embodiment of the light diffusing ink composition to which the PMMA particles and / or the silicon particles are applied as the light diffusing agent are disclosed as follows.

As the PMMA particles, PMMA beads may be applied, and as the silicon particles, silicon beads may be applied. Specific examples of the light diffusion ink composition disclosed in this embodiment include 15-35% by weight of an ink binder containing an acrylic resin and / or a vinyl chloride-vinyl acetate copolymer, PMMA beads having an average particle size of 0.8 μm to 3 μm, and / Or 10-30 wt% of a light diffusing agent having silicon beads, 40-70 wt% of an ink solvent containing one or more of ketones, esters, ethers, and petroleum-based solvents, 1-3 wt% of a dispersant, and other additives 0.5 2 wt%, 0-10 wt% of the auxiliary particles.

Next, in another embodiment of the light diffusion ink composition (applying the silica particles as the light diffusion agent), the silica particles are contained in the light diffusion ink composition 10 to 80 parts by weight based on 100 parts by weight of the ink binder. When the silica particles are less than 10 parts by weight, the light diffusing effect is lowered, the light intensity of the light guide panel is significantly lowered. When the silica particles are 80 parts by weight or more, the total light transmittance is lowered due to the overlapping of particles and the light diffusing effect. And the screen print workability may be degraded.

When the silica particles are applied as the light diffusing agent, the ink solvent contains 150 to 550 parts by weight, particularly 180 to 500 parts by weight based on 100 parts by weight of the ink binder.

In addition, in forming the fine dot pattern using the screen mesh on the light guide member, the thixotropy index of the ink affects the formation of the dot pattern. Therefore, the ink composition according to the present invention, it is preferable to further comprise the dispersant as in the above-described embodiment in order to lower the thixotropy index of the ink increases as the content of the light diffusing agent is increased.

More specifically, when the light diffusing agent is included in the total weight of the light diffusing ink composition by a predetermined amount or more, for example, 6 wt% or more, the thixotropy index is 2 to 5 or more, which affects the formation of the dot pattern. Therefore, in the present embodiment, when the thixotropy index is increased to a predetermined level, for example, 2 or more in consideration of the thixotropy index, it is preferable to add the dispersant to the light diffusion ink composition.

In the present embodiment, the dispersant may be introduced so that the thixotropy is 2 or less, but is not limited thereto. Examples of the dispersant include a known acrylic copolymer-based dispersant, and the dispersant may be included in 100 parts by weight of the ink binder. More specifically, 0 to 20 includes 3 to 20 parts by weight, but is not limited thereto. It may be changed according to design conditions.

In addition, the light diffusion ink composition may further include one or more additives such as an antifoaming agent and a leveling agent. The amount of the additive may be variously adjusted according to design conditions, but the present embodiment discloses that 1 to 15 parts by weight of the additive is included with respect to 100 parts by weight of the ink binder.

On the other hand, the light diffusion ink composition according to the present embodiment may further include the auxiliary particles for improving the light diffusion efficiency by increasing the refractive index of the ink. Since the auxiliary particles have already been described in the above-described embodiment, additional descriptions thereof will be omitted.

Specific examples of one embodiment of the light diffusing ink composition to which the silica particles are applied as the light diffusing agent are disclosed as follows.

Examples of the specific light-diffusion ink composition disclosed in this embodiment include 15-30% by weight of an ink binder containing an acrylic resin and / or a vinyl chloride-vinyl acetate copolymer, and silica particles having an average particle size of 0.8 µm to 3 µm. 4-12% by weight of light diffusing agent, 55-75% by weight of ink solvent containing at least one of ketones, esters, ethers and petroleum-based solvents, 1-3% by weight of dispersant, 0.5-2% by weight of other additives, Auxiliary particles may be prepared from 0 to 10% by weight.

The light diffusion ink composition according to the present invention described above is printed on the light guide plate 111, more specifically PMMA or PC (Poly carbonate) or PS (Polystyrene) material by silk screen printing (Silk Screen Printing) technique to the dot pattern A light diffusing layer (112) is formed, and the dot pattern 112 is formed to have a fine size of 400 μm, in particular 300 μm or less, and may be densely provided on the surface of the light guide plate material. In other words, as the dot pattern 112 becomes finer, the gap between the dot patterns 112 may be denser in the light guide panel 110.

In addition, in the present invention, a light diffusing agent having an average particle size of 0.8 μm to 3 μm is applied to improve the decrease in luminance of the light guide panel 110, which may be caused by the reduction of the thickness of the light guide plate material. To improve the variation in the amount of light and to reduce the printability caused by miniaturizing the dot pattern to 400㎛ or less to facilitate the formation of the dot pattern.

The dot pattern may have a size of 10 μm to 400 μm, in particular 30 μm to 300 μm, but the minimum size is not limited thereto and may be further reduced according to the grade of the mesh used for screen printing. A dot pattern of approximately 50 μm may be formed using 600 mesh, and as the mesh is refined, the size of the dot pattern may be reduced to 10 μm or less, and a more dense dot pattern may be formed.

And the light guide plate material is less than 5mm, particularly up to 4mm, preferably less than 3mm is good for the thinning and light weight of the electronic device, for example, can be made of 1mm ~ 4mm, in particular 1mm ~ 3mm, the thickness of the light guide plate material is the lower limit Without being limited thereto, the thickness of the light guide plate may be thinner and thinner as the manufacturing technique permits. Since the light guide plate is a fluid, it is natural that the thickness of the light guide plate is greater than 0 (Zero). Even if the size is indicated as being limited to the upper limit, the lower limit is naturally present and thus corresponds to a clear description that can specify the scope of the present invention.

The light source 120 is provided at a side edge of the light guide panel 110 like a known backlight unit and emits light toward the light incident part of the light guide plate 111. An example of the light source is an LED (LED) 121. There are a plurality of LEDs 121 may be disposed along the side edges of the light guide panel 110, and may be configured to emit light simultaneously or sequentially or alternately.

Hereinafter, specific examples of the light diffusion ink composition according to the present invention will be described, and the following examples are merely illustrative of the present invention and are not limited to the following examples.

[Production of Light Diffusion Ink Composition According to Example 1 to Example 3 and Comparative Example]

A light diffusion ink composition according to Example 1, Example 2, and Example 3 and Comparative Example was prepared according to the components and contents of Table 1 as follows, and the light diffusion ink composition was 23 mm (Inch) having a thickness of 2 mm. A light guide panel having a dot pattern having a size of 400 μm was manufactured by printing on a light guide plate material.

ingredient Example 1 Example 2 Example 3 Comparative Example Remarks A-21
25
25
20
25 Acrylic resin
(Molecular weight 120,000)
Rohm & Haas Products Kocosol 180 27.6 27.6 30.1 27.6 Ketone Solvent
(Boiling point 210 degrees Celsius) Isophorone 30 30 40 30 Ketone Solvent
(Boiling point 210 degrees Celsius) BYK-052 0.4 0.4 0.4 0.4 Silicone Defoamer
BYK Products G-410 0.5 0.5 0.5 0.5 Silicone Leveling Agent
Tego Products BYK-2008 1.5 1.5 2 1.5 Acrylic Dispersant
BYK Products PMMA Bead
(Average particle size 2㎛) 15 Silicone beads
(Average particle size 2㎛) 15 Silica
(Average particle size 2㎛ 7 PMMA Bead
(Average particle size 6㎛) 15 Sum 100 100 100 100

And the physical properties of the light diffusion ink composition according to Examples 1 to 3 and Comparative Examples are shown in Table 3 below.

division Example 1 Example 2 Example 3 Comparative Example Remarks Viscosity (cps / 25 ℃) 7000 7500 7500 6500 Thixotropic index 1.1 1.2 1.7 1.1

In the light diffusion ink compositions according to Examples 1 to 3 and Comparative Examples described above, a dot pattern was formed on a light guide plate having a thickness of 2 mm by using a silk screen printing method, and at a position (1 to 17 Point) shown in FIG. About the same amount of light was measured with a known measuring equipment (measurement equipment photo research PR650) and are shown in the following [Table 4].

location Example 1 Example 2 Example 3 Comparative Example Remarks One 5115 4790 4800 4680 2 4761 4720 4740 4530 3 4683 4630 4650 4601 4 4486 4500 4560 4630 5 4774 4728 4760 4580 6 4733 4510 4800 4890 7 4642 4732 4638 4480 8 4763 4640 4667 4660 9 4638 4522 4790 4730 10 4442 4500 4320 4205 11 4678 4650 4660 4530 12 4455 4321 4730 4846 Light receiver 13 4156 4600 4100 4156 14 5210 5020 5250 5420 Light receiver 15 4359 4520 4230 4100 16 4585 4650 4579 4580 17 4547 4330 4630 4890 Light receiver Total light quantity 79024 78363 78904 78508 Uniformity 1.25 1.16 1.28 1.32 MAX (1 ~ 17) / MIN (1 ~ 17)

As light is scattered around the light incident part close to the light source, Comparative Examples were lower than Examples 1 and 3 in the total amount of light as shown in [Table 4], and Example 2 to which silicon beads were applied in terms of uniformity of light amount was the most. It was found to be good, and Example 1 and 3 were also superior to the comparative example, and the workability was also excellent when screen printing.

On the other hand, Figure 5 (a) and (b) is a micrograph showing the shape of the dot pattern (400㎛ size) according to the thixotropy index, the higher the thixotropy index appeared unstable appearance of the dot pattern, ( b) is a dot pattern formed by a light diffusion ink composition to which a dispersant is added to lower the thixotropic index.

The light guide panel and the backlight unit using the light diffusion ink composition according to the present invention may be widely applied to various fields such as electronic devices such as LCDs, light emitting signs and decorative panels.

As described above, according to the present invention, the present invention can be embodied in other specific forms without departing from the spirit and scope of the present invention. It is obvious to them.

Therefore, the above-described embodiments are to be considered as illustrative rather than restrictive, and the present invention is not limited to the above description, but may be modified within the scope of the appended claims and equivalents thereof.

100: backlight unit 110: light guide panel
111: Light guide plate 111a: Light receiving part
112: pattern 120: light source
121: LED

Claims (17)

As a light diffusion ink composition for slimming the light guide panel:
At least one ink binder selected from the group consisting of acrylic resins and vinyl chloride-vinyl acetate copolymers;
A light diffusing agent selected from the group consisting of PMMA particles and silicon particles and having a particle size of 0.8 μm to 3 μm;
At least one ink solvent selected from the group consisting of ketones, ethers and petroleum solvents; And
A dispersant for lowering the thixotropy index of the light diffusion ink composition to 2 or less;
The PMMA particles and the silicon particles may be included alone or in a mixture of 25 to 200 parts by weight based on 100 parts by weight of the ink binder, and the ink solvent may include 110 to 470 parts by weight based on 100 parts by weight of the ink binder. . delete delete delete delete The method of claim 1,
The light diffusing agent is a light diffusion ink composition, characterized in that the particle size is 0.8㎛ ~ 2㎛. delete The method of claim 1,
A light diffusion ink composition further comprising at least one auxiliary particle selected from the group consisting of titanium oxide (TiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) each having a particle size of 0.05 μm to 4 μm. 9. The method of claim 8,
The auxiliary particles, light diffusion ink composition, characterized in that 1 to 70 parts by weight based on 100 parts by weight of the ink binder. delete delete Light guide plate material; And
A light guide formed on the light guide plate by the light diffusion ink composition of any one of claims 1, 6, 8, and 9, and comprising dot patterns having a maximum size of 400 μm. panel. The method of claim 12,
The light guide panel has a thickness of 4 mm maximum. The method of claim 12,
The light guide panel has a thickness of 3 mm or less. The method of claim 12,
The dot pattern is a light guide panel, characterized in that the size is 300㎛ or less. delete Light guide plate material;
A dot pattern formed on the light guide plate by the light diffusion ink composition of any one of claims 1, 6, 8, and 9, and having a maximum size of 400 µm; And
And a light source for emitting illumination light toward the light guide plate.

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