KR20120033902A - Condensing type optical sheet - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light collecting type optical sheet for use in a liquid crystal display device, and discloses an optical sheet having improved scratch resistance by increasing a friction coefficient between a structural layer and a back coating layer to lower slip properties.

Description

Condensing type optical sheet

The present invention relates to a light collecting optical sheet used in a liquid crystal display device.

In the liquid crystal display (LCD) device, since the liquid crystal itself cannot emit light, a separate light source is installed at the rear of the device, and the contrast is adjusted by adjusting the intensity of the passing light through the liquid crystal installed in each pixel. . In more detail, the liquid crystal display device is a device for controlling the light transmittance by using the electrical properties of the liquid crystal material, the uniformity and the directionality is controlled by passing through various functional prism films or sheets by emitting light from the light source lamp on the back of the device Indirect light-emitting display device that implements an image by passing light through a color filter to realize red, blue, green (R, G, B) colors, and controlling the contrast of each pixel by an electric method As a light emitting device that provides a light source, it is an important component for determining image quality such as brightness and uniformity of a liquid crystal display device.

A backlight unit (BLU) is widely used as the light emitting device, and the backlight unit emits light by using a light source such as a light emitting diode (LED) and a cold cathode fluorescent lamp (CCFL). Is sequentially passed through the light guide plate or the diffusion plate, the diffusion sheet and the prism sheet to reach the liquid crystal panel. Here, the light guide plate is mounted in the case of an edge type backlight unit, and transmits the light emitted from the light source to be distributed on the front surface of the liquid crystal panel in a flat shape, and the diffusion member such as the diffusion plate or the diffusion sheet is uniform light over the entire screen. It is possible to obtain the intensity and at the same time serves to conceal a device such as a light source mounted on the lower portion of the diffusion member from the front. On the other hand, the prism sheet performs a light path control function for converging light rays from various directions passing through the diffusion member within a range of viewing angle θ suitable for the viewer to recognize the image to be collected. In addition, the lower portion of the light guide plate or the diffusion plate is provided with a reflective sheet for increasing the efficiency of use of the light source by being reflected back to the light that is not delivered to the liquid crystal panel and out of the path.

Here, as an example of the prism film, the front luminance of the screen may be increased by using a film or sheet using the prism structures cited in US Patent Nos. 2,248,638 and 4,497,860 to increase the front luminance by increasing the amount of light transmitted to the front of the screen. The prism structure film has been proved to have higher front condensing efficiency by using two sheets arranged at right angles or at a predetermined angle than when using a single product (US Patent No. 4,542,449). Is used in orthogonal arrangement.

Such a film is made of a roll or a large-area sheet in which a prism structure is formed using a transparent curable resin on a transparent film such as polyester or polycarbonate, and is cut into a size and shape necessary for mounting to an actual device, thereby making it a liquid crystal. One or two sheets are orthogonally mounted on the backlight unit frame of the display device.

On the other hand, the light emitted from the light source diffuses from the diffusion sheet and is focused on a predetermined angle range in the process of condensing on the prism sheet, so that some non-condensed light is extinguished or re-condensed at this point. In the yellow band is a yellow band (yellow band) is generated, a rainbow (rainbow) phenomenon in which the rainbow-colored wave generated in the extinction portion and the re-condensation portion is generated, there was a problem that a failure occurs.

In order to make up for this point, a protective sheet has been laminated on a prism sheet, and recently, efforts have been made to reduce the number of sheets to produce a thinner display and to eliminate the protective sheet in order to simplify the manufacturing process.

In one embodiment of the present invention to provide an optical sheet that can minimize the damage in processing or circulating the film roll formed with a prism structure.

In one embodiment of the present invention further to provide an optical sheet that does not generate a yellow band or rainbow phenomenon.

In one embodiment of the present invention; A structural layer formed on one surface of the base layer and having a plurality of three-dimensional structures arranged thereon; And a back coating layer formed on the other side of the substrate layer and having particles dispersed therein, wherein the coefficient of static friction between the structural layer and the back coating layer is at least 0.2 or more.

In the optical sheet according to the preferred embodiment, the coefficient of static friction between the structural layer and the back coating layer may be 0.20 to 0.3.

In the optical sheet according to the embodiment of the present invention, the coefficient of kinetic friction between the structural layer and the back coating layer may be at least 0.2.

In the optical sheet according to the embodiment of the present invention, the coefficient of dynamic friction between the structural layer and the back coating layer may be 0.20 to 0.3.

In this way, the friction coefficient between the structural layer and the back coating layer can be maintained in a predetermined range, and the structural layer uses a planar indenter on the upper surface of the three-dimensional structure until the maximum compressive force is 1gf or 2gf at a pressure of 0.203 mN / sec. When pressing and releasing compression after stopping compression for 5 seconds when reaching the maximum compression force, the elastic recovery rate represented by the following Equation 1 may be 85% or more.

Equation  One

In the above formula, D ₁ means the depth that is compressed by the external pressure is applied, D ₂ is the difference between the height of the optical sheet without the external pressure and the height of the optical sheet at the time of recovery by removing the external pressure. it means.

In the optical sheet according to the embodiment of the present invention, the three-dimensional structure of the structural layer has a slanted longitudinal section and includes an inclined portion extending in both directions based on one peak point, and the inclined portion is symmetrical or relative to the peak point. It is asymmetric and each slope may be one that satisfies a shape that is part of the circumference of the imaginary first circle and part of the circumference of the second circle.

In the optical sheet according to the embodiment of the present invention, the three-dimensional structure of the structural layer has a width that is perpendicular to the imaginary line connecting two intersection points of the imaginary first circle and the second circle, and the first circle and the first circle. It may be 1/10 to 1 with respect to the maximum length between each circumference at the overlap of the two circles.

In the optical sheet according to the embodiment of the present invention, the structural layer is perpendicular to the imaginary line connecting two intersection points of the imaginary first circle and the second circle and at the overlapping portion of the first circle and the second circle. The maximum length between each circumference of may be 50 ~ 1000㎛.

In the optical sheet according to the embodiment of the present invention, the three-dimensional structure of the structural layer has a height of 1/20 to 1/2 with respect to the imaginary line length connecting two intersection points of the imaginary first circle and the second circle. It may be.

In the optical sheet according to the embodiment of the present invention, the virtual line length connecting two intersection points of the virtual first circle and the second circle may be 1 to 1000 μm.

In the optical sheet according to the embodiment of the present invention, the peak portion is connected to the inclined portion, the virtual third circle may be 50㎛ or less in diameter.

In the optical sheet according to the embodiment of the present invention, the three-dimensional structure of the structural layer may be linearly arranged or non-linearly arranged.

When the optical sheet according to the embodiment of the present invention is wound in a roll shape, the slippage between the structural layer surface and the rear surface is reduced, thereby reducing or eliminating scratches, and further satisfying the appropriate luminance level while providing a separate protective sheet. No yellow band or rainbow phenomenon occurs without the need.

1 is a view showing the shape of a three-dimensional structure in a light collecting optical sheet according to an embodiment of the present invention,
FIG. 2 is a sectional view of an optical sheet including a three-dimensional structure having a shape obtained by FIG. 1;
3 is a view showing the shape of a three-dimensional structure in an optical sheet according to another preferred embodiment of the present invention,
4 is a cross-sectional view of an optical sheet including a three-dimensional structure having a shape obtained by FIG. 3;
5 is a view showing the shape of a three-dimensional structure in a light collecting optical sheet according to another preferred embodiment of the present invention;
FIG. 6 is a cross-sectional view of an optical sheet including a three-dimensional structure having a shape obtained by FIG. 5;
7 is a view showing the shape of the three-dimensional structure in the optical sheet according to another preferred embodiment of the present invention,
8 is a cross-sectional view of an optical sheet including a three-dimensional structure having a shape obtained by FIG.
9 is a yellow band and rainbow observation photograph when the light converging optical sheet according to Example 1 is applied;
10 is a schematic diagram for evaluation of a friction coefficient of an optical sheet according to an embodiment.

Hereinafter, the present invention will be described in more detail.

The present invention is a substrate layer; A structural layer formed on one surface of the base layer and having a plurality of three-dimensional structures arranged thereon; And a back coating layer formed on the other side of the substrate layer and having particles dispersed therein, wherein the coefficient of static friction between the structural layer and the back coating layer is at least 0.2 or more.

When the static friction coefficient between the structural layer and the back coating layer is at least 0.2 or more, the slippage between the structural layer and the back coating layer may be reduced or eliminated due to friction between the optical sheets and the rolled sheet for transport or storage. have.

Specifically, the static friction coefficient between the structural layer and the back coating layer may be 0.20 to 0.3.

On the other hand, in the friction coefficient measurement, in the case of the dynamic friction coefficient corresponding to the friction coefficient measured by the moving slad in addition to the static friction coefficient measured when the initial slad moves, the dynamic friction coefficient between the structural layer and the back coating layer is at least 0.2 or more, preferably 0.20 to 0.3, can prevent the damage of the optical sheet which may occur during roll conveying or reduce the defective rate when combining various optical sheets.

In this way, the friction coefficient between the structural layer and the back coating layer can be maintained in a predetermined range, and the structural layer uses a planar indenter on the upper surface of the three-dimensional structure until the maximum compressive force is 1gf or 2gf at a pressure of 0.203 mN / sec. When pressing and releasing compression after stopping compression for 5 seconds when reaching the maximum compression force, the elastic recovery rate represented by the following Equation 1 may be 85% or more.

Equation 1

In the above formula, D ₁ means the depth that is compressed by the external pressure is applied, D ₂ is the difference between the height of the optical sheet without the external pressure and the height of the optical sheet at the time of recovery by removing the external pressure. it means.

In the optical sheet including a structural layer in which a plurality of three-dimensional structures are arranged, when the middle cross-section of the three-dimensional structure is polygonal, since the upper part of the optical sheet is pointed in a mountain shape, it may be easily damaged by an external impact, which satisfies such a compression recovery rate. In the case of having a structural layer that is not only elastic but also to the scratch resistance can withstand a predetermined load range even if an external force is applied.

The optical sheet of the present invention for this purpose is pressed by a planar indenter on the upper surface of the structured surface of the structural layer until the maximum compression force of 1gf or 2gf at a pressing speed of 0.2031mN / sec, and when the maximum compression force is reached for 5 seconds When the compression force is released after stopping and compressing, the elastic recovery rate expressed by Equation 1 is preferably 85% or more, and more preferably, the elastic recovery rate expressed by Equation 1 is 90% or more.

In the optical sheet of the present invention, when the elastic recovery rate is satisfied when the pressurized and pressurized force is removed as described above, even when an external impact is applied, the optical sheet has an elastic force that is flexible enough to cope with the impact. Can prevent damage.

On the other hand, when the optical sheet does not satisfy the elastic recovery rate when the optical sheet is pressurized as described above, the upper portion of the structural layer remains pressed when the optical sheet is in contact with another film or under load. There is a risk of malfunction.

Meanwhile, in order to satisfy scratch resistance, a trifunctional acrylate compound having an ethylene oxide group number of 1 to 15 may be included in the curable material for forming the structure layer.

Among the trifunctional acrylate compounds, the number of ethylene oxide groups in the above range is between 50 and 200 cps, so the processability is good and the produced prism has good ductility, which is suitable for imparting elasticity to the prism sheet.

Specific examples of such trifunctional acrylate compounds include trimethyllopropane triacrylate, glycerin propoxylated triacrylate, pentaerythritol triacrylate, and the like.

As described above, when the curable material has a structural layer of a trifunctional acrylate compound having an ethylene oxide group of 1 to 15 while satisfying a predetermined elastic property, the coefficient of friction between the back coating layer and the structural layer can be increased.

Meanwhile, the curable material capable of forming a structural layer capable of satisfying the above-mentioned elastic recovery rate is not particularly limited, but for example, a molecular structure having a structure of a bifunctional monomer in which a flexible alkylene glycol chain in a molecule is repeatedly connected. Can increase the modulus of elasticity. In particular, in the case of including the compound of the formula (1) as a material for the structural layer, it is possible to satisfy the above elastic recovery rate and not inhibit the optical properties.

Formula 1

Wherein R is a hydrogen atom or an alkyl group of 1 to 15 carbon atoms, x, y, z is an integer of 0 or more, x, y, z is not all 0, a, b, c is an integer of 0 or more, x, y, z are not all zeros and an integer of a + b + c≥4 or more, or if a + b + c <4, one of x, y, z is 3 or more.

The compound of Formula 1 may have an elastic modulus after curing as a compound having a molecular weight of 150 to 10,000 by controlling the type and length of the flexible alkylene oxide chain in the molecular structure. And it is preferable as a material which is excellent in heat resistance and light resistance, and forms the structural layer of an optical sheet.

In addition, in the optical sheet of the present invention, the structure layer is the D ₁ which means the depth which is compressed by applying an external pressure. It is preferable to satisfy the following formula (2), more preferably the following formula (3), and more preferably the following formula (4).

Equation  2

In the above formula, D means the height of the optical sheet in the state that no external pressure is applied.

Equation  3

In the above formula, D means the height of the optical sheet in the state that no external pressure is applied.

Equation  4

In the above formula, D means the height of the optical sheet in the state that no external pressure is applied.

That is, when the optical sheet of the present invention is flexible or has a load such that the depth into which the optical sheet is compressed due to the external pressure is 1/20 or more with respect to the height of the optical sheet without the external pressure is in contact with another film or under load The top of the structure layer may be more advantageous in maintaining the normal shape.

As a result, the optical sheet of the present invention easily enters the structural layer having a three-dimensional structure when subjected to a large load, but recovers as close as possible to the original state when the compressed state is released, so that the structural layer is not damaged even by external impact. In addition, scratch resistance can be satisfied.

The optical sheet of the present invention preferably comprises 5 to 80% by weight based on the total weight of the composition forming the structural layer of the compound of Formula 1 so as to satisfy the elastic recovery rate described above. When included less than 5% by weight increase of the elastic recovery rate is insignificant, when included by more than 80% by weight may have a slight effect of increasing the brightness as an optical sheet.

Meanwhile, it is preferable to include 30 to 80% by weight of the trifunctional acrylate compound having 1 to 15 ethylene oxide groups with respect to the total weight of the composition forming the structural layer, in order to realize easy viscosity and elasticity in processability.

In addition, the composition forming the structural layer may further include a conventional UV curing agent, a photoinitiator, and a high refractive resin having a refractive index of 1.52 or more, in addition to the compound of Formula 1, and a trifunctional acrylate compound in which the number of ethylene oxide groups is controlled.

In one embodiment of the present invention as an example of another method that can satisfy the coefficient of friction between the structural layer and the back coating layer is the shape control of the three-dimensional structure of the structural layer.

For example, 1 is a view showing the shape of a three-dimensional structure in the light collecting optical sheet according to an embodiment of the present invention, Figure 2 is a cross-sectional view of a light collecting optical sheet including a three-dimensional structure having a shape obtained by the above-mentioned FIG. In addition, Figure 3 is a view showing the shape of the three-dimensional structure in the light converging optical sheet according to another embodiment of the present invention, Figure 4 is a cross-sectional view of the light collecting optical sheet including a three-dimensional structure having a shape obtained by the above-mentioned. . On the other hand, Figure 5 is a view showing the shape of the three-dimensional structure in the condensing optical sheet according to another preferred embodiment of the present invention, Figure 6 is a condensing optical sheet including a three-dimensional structure having a shape obtained by the above 5 It is a cross section. In addition, Figure 7 is a view showing the shape of the three-dimensional structure in the condensing optical sheet according to another preferred embodiment of the present invention, Figure 8 is a cross-sectional view of the condensing optical sheet including a three-dimensional structure having a shape obtained by the above-mentioned Fig. to be.

On the other hand, the accompanying drawings used the same reference numerals for the same components for convenience, they do not mean the same composition and form.

The optical sheet of the present invention includes, as a first preferred embodiment, a base layer 10 and a structural layer 20 formed on one side or both sides of the base layer 10 and arranged in a plurality of three-dimensional structures. The three-dimensional structure 25 of (20) has a slanted longitudinal section and includes an inclined portion 21 extending in both directions on the basis of one peak point, and the inclined portion 21 is symmetrical or relative to the peak point. It is asymmetrical and each inclined portion 21 is formed by a portion of the circumference of the overlapping virtual first circle 100 and a portion of the circumference of the second circle 200 (see FIGS. 1 to 4).

In another preferred embodiment, the present invention includes a base layer 10 and a structural layer 20 formed on one or both surfaces of the base layer 10 and having a plurality of three-dimensional structures arranged thereon. The three-dimensional structure 25 of the 20 has a streamlined longitudinal section, and includes a peak portion 22 including one peak point, and an inclined portion 21 extending in both directions with respect to the peak portion 22, The inclined portion 21 is symmetrical or asymmetrical with respect to the peak point, each inclined portion 21 is a part of the circumference of the circumferential first circle 100 and the circumference of the second circle 200, The peak part 22 is included in an overlapping portion of the virtual first circle 100 and the second circle 200 while being in contact with the circumference of the first circle 100 and the circumference of the second circle 200. A light collecting optical sheet which is a part of the circumference of the third circle 300 is provided. (See FIGS. 5 to 8).

According to the first and second preferred embodiments of the present invention, the size and the degree of inclination of the three-dimensional structure 25 are determined according to the size and the degree of overlap of the overlapping first circle 100 and the second circle 200. All.

That is, the three-dimensional structure 25 of the structural layer 20 is connected to the virtual line L connecting two intersection points of the virtual first circle 100 and the second circle 200 in which the width w overlaps. It may be 1/10 to 1 with respect to the maximum length (d) between the respective circumference at the overlapping portion of the two circles and perpendicular to the. At this time, the overlapping portion of the first circle 100 and the second circle 200 while being perpendicular to the virtual line L connecting the two intersection points of the virtual first circle 100 and the second circle 200. The maximum length (d) between each circumference in the 50 to 1000㎛ may be advantageous in terms of refracting the light so that the side of the light condensing and the rainbow phenomenon and yellow band does not occur in consideration of the light path.

When the three-dimensional structure 25 of the structural layer 20 first determines the width w as described above, the height h is naturally determined, and two intersection points of the first circle 100 and the second circle 200 are determined. It may be advantageous in that it is 1/20 to 1/2 with respect to the length of the virtual line (L) connecting the light in consideration of the path of light and refracting the light so that a rainbow phenomenon and a yellow band are not generated. In this case, the length of the virtual line L connecting two intersection points of the first circle 100 and the second circle 200 may be 1 to 1000 μm.

In the above description, the width of the three-dimensional structure 25 is determined first. On the contrary, if the height h of the three-dimensional structure 25 is determined first, the width w may be naturally determined.

On the other hand, the light converging optical sheet of the present invention may include a gentle peak portion 22, as in the second preferred embodiment of the present invention, which overlaps two virtual circles forming the inclined portion 21. It is formed as a part of the circumference of the virtual third circle 300 is in contact with the portion.

The degree and the degree of curvature of the peak portion 22 is determined according to the size and position of the third circle 300, the third circle 300 is the overlapping portion of the first circle 100 and the second circle (200) The circumference of the third circle 300 is in contact with the circumferences of the first circle 100 and the second circle 200 while being located within the area, and is a position for forming the peak portion 22. The diameter of the tern 300 may be 50㎛ or less.

The first circle 100 and the second circle 200 may be circles having the same diameter as shown in FIGS. 1 and 5, or circles having different diameters as shown in FIGS. 3 and 7. 25 may be symmetrical or asymmetrical about the peak when viewed in longitudinal section.

In addition, the three-dimensional structure 25 of the structural layer 20 may be linear or non-linear array.

Since the three-dimensional structure 25 having such a shape does not have the same angle at which light is incident and refracted and exits, the rainbow phenomenon and the yellow band are not generated. In addition, in the case of a lenticular lens, a rainbow phenomenon and a yellow band do not occur, but brightness is very low because it does not perform a function of condensing. The three-dimensional structure 25 having the shape has a high luminance degree as in a conventional prism structure. However, more than the required level of brightness can be provided sufficiently.

In addition, in one configuration formed to control the coefficient of friction with the structural layer, the back coating layer may be composed of a transparent organic binder and organic or inorganic particles. The back coating layer may use a resin having good adhesion with the plastic support and good compatibility with the particles. Specifically, unsaturated polyester, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, and normal butyl methacryl are used. Latex, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxy ethyl acrylate, acrylamide, metyrolacrylamide, glycidyl methacrylate, Acrylic type, urethane type, epoxy type, melamine type etc., such as ethyl acrylate, etc. are mentioned, In order to improve heat resistance, abrasion resistance, and adhesiveness, it is also possible to use a hardening film of a resin using a hardening | curing agent.

In preparing the back coating layer, various organic and inorganic particles may be used as the particles. Representative particles that can be used are methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide, metyrolacrylamide, glycidyl methacrylate and ethyl acrylate. Olefin particles such as acryl-based, polyethylene, polystyrene, and polypropylene, such as isobutyl acrylate, normal butyl acrylate and 2-ethylhexyl acrylate polymer; Copolymers of acryl and olefins; Organic particles, such as a multi-layered multicomponent particle | grains made by forming the particle | grains of a homopolymer, and covering it with the other kind of monomer on the layer, are mentioned. In addition, inorganic particles such as silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, and magnesium fluoride may be used.

The size of the particles used in the back coating layer may vary depending on the thickness of the coating film, and particles of 0.1 to 20 microns are preferable, and when the particles are large, the protruding portions may be too high to cause damage to the top surface of the optical structure. Preferably, the particles are preferably 0.1 to 10 microns.

In forming the back coating layer, the content of particles to the organic binder is preferably 0.1 to 100 parts by weight per 100 parts by weight of the binder. When the amount of particles used is large, light is diffused in the case of organic particles or light in the case of inorganic particles. It is preferable that it is 1 to 50 parts by weight since it is reflected at the surface and rather reduces the light efficiency.

In addition, if a large number of protruding particles in the individual particles may cause damage to the prism vertices by the protruding particles, it is preferable that the protruding portions of the individual particles protrude not to exceed 50% of the particle diameter.

In addition to these particles, an antistatic agent that imparts contamination resistance may be further added to prevent dust or impurities that may occur when manufacturing the backlight unit. Antistatic agents can be used a variety of quaternary amine, anionic, cationic, nonionic, fluoride-based.

The base layer of the optical sheet according to an embodiment of the present invention is a group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polymethacrylate, polymethyl methacrylate, polyacrylate, polyimide, polyamide It may be formed of any one or more materials selected from among, and may further include light diffusing particles to form a structure in which the irregularities are formed.

An optical prism film capable of preventing shock, vibration and handling damage by forming a structural layer from an ultraviolet curable resin composition on one surface of the base film and applying a particle dispersing layer composed of a transparent organic binder and organic or inorganic particles on the opposite side thereof. It can manufacture.

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

Acrylate Oligomer Manufacturing example

Synthetic example

About 1 mole of HO- [CzH ₂ zO] c- [CyH ₂ yO] b- [CxH ₂ xO] aH compound to 2.2 moles of CH ₂ = CH (R) COCl using a reaction vessel in about 5 in the presence of a solvent of tetrahydrofuran Compounds of the desired structure could be synthesized by refluxing for about a time, and after the reaction, unreacted CH ₂ = CH (R) COCl and the solvent were removed by filtration and distillation under reduced pressure using a filter to synthesize the structure of Chemical Formula 1. . At this time, the variables of the compound were synthesized as in Table 1 below.

Synthetic example HO-R-OH CH ₂ = CH (R) COCl yield(%) Viscosity
(mPaS / 25 ℃) One x = 2, y, z = 0, a = 4, b, c = 0 R = H 93.5 25 2 x = 2, y, z = 0, a = 9, b, c = 0 95.8 58 3 x = 2, y, z = 0, a = 14, b, c = 0 97.0 106 4 x = 2, y, z = 0, a = 23, b, c = 0 92.8 100/40 ℃ 5 x = 2, y, z = 0, a = 4, b, c = 0 R = CH ₃ 93.5 50 6 x = 3, y, z = 0, a = 2, b, c = 0 R = H 97.5 8 7 x = 3, y, z = 0, a = 3, b, c = 0 96.3 12 8 x = 3, y, z = 0, a = 7, b, c = 0 95.2 34 9 x = 3, y, z = 0, a = 12, b, c = 0 94.6 68 10 x = 3, y, z = 0, a = 7, b, c = 0 R = CH ₃ 96.7 30 11 x, z = 2, y = 4, a, b, c = 1 R = H 95.5 10 12 x, z = 2, y = 4, a, b, c = 1 R = CH ₃ 94.6 10 13 x = 5, y, z = 0, a = 1, b, c = 0 R = H 96.5 6 14 x = 9, y, z = 0, a = 1, b, c = 0 R = H 94.5 20 * HO-R-OH is HO- [CzH ₂ zO] c- [CyH ₂ yO] b- [CxH ₂ xO] aH

Optical sheet manufacturers

Example  1-14

90 parts by weight of acrylic polyol and 10 parts by weight of isocyanate are dissolved in 200 parts by weight of methyl ethyl ketone and 100 parts by weight of toluene in a solvent, 50 parts by weight of PMMA particles (5 micron monodisperse particles) and 2 parts by weight of quaternary amine antistatic agent Dispersion to prepare a back coating layer crude liquid.

The 188 micrometer polyethylene terephthalate film T600 (Mitsubishi Corporation) (refractive index: 1.49) was used for the base material layer.

The backcoating layer crude solution was applied to one side of the base film using gravure, and dried at 100 ° C. for 30 seconds to prepare a base film having a back coating layer such that the thickness was 6 μm and the thickness of 4 microns was not included. .

On the other hand, with respect to 100 parts by weight of the total composition, 30 parts by weight of the acrylate produced in Synthesis Examples 1 to 14, 35 parts by weight of bisphenol A-type diacrylate (M-2100, unyarn yarn), trimethylpropane triacrylate (6 ethylene oxide groups) 30 parts by weight, photoinitiator 2,4,6-trimethylbenzoyl diphenylphosphine oxide 1.5 parts by weight, photoinitiator methylbenzoylformate 1.5 parts by weight, additive bis (1,2,2,6,6 2.0 parts by weight of -pentamethyl-4-piperidyl) sebacate was mixed and mixed at 60 ° C. for 1 hour to prepare an acrylic UV curable resin composition.

In order to design the three-dimensional structure of the structural layer is designed as shown in Figure 1, the diameter of the circumference of the imaginary first circle and the second circle is 250㎛, respectively, the virtual connecting the intersection of the imaginary first circle and the second circle The length of the line L is 200 μm, and the maximum length d between each circumference at the overlapping portion of the first circle and the second circle is perpendicular to the imaginary line L connecting two intersection points, and 100 μm. The mold was manufactured such that the width (w) of the three-dimensional structure was 50 μm (1/2 of the length of d), and the height (h) was 25 μm (1/8 of the length of L). A resin composition (refractive index: 1.58) was added to form a structural layer (refractive index: 1.60) that was UV-cured on the other surface of the substrate layer to prepare an optical sheet.

<Example 15>

In the first embodiment, the length of the virtual line (L) connecting the intersection of the virtual first circle and the second circle is 225㎛, the first direction perpendicular to the virtual line (L) connecting the two intersections The maximum length d between each circumference at the overlapping portion of the circle and the second circle is 150 μm, and the width w of the three-dimensional structure is 50 μm (1/3 of the length d), and the height h is The optical sheet was manufactured by the same method except that it was set to 12.5 micrometers (1/8 of L length).

<Example 16>

In Example 1, the diameter of the circumference of the imaginary first circle and the second circle is 500 μm, respectively, and the length of the imaginary line L connecting the intersection points of the imaginary first circle and the second circle is 350 μm, The maximum length d between each circumference at the overlapping portion of the first circle and the second circle while being perpendicular to the imaginary line L connecting two intersection points is 150 μm, and the width of the three-dimensional structure (w) ) Was manufactured in the same manner except that 50 µm (1/3 of d length) and height h were 25 µm (1/4 of L length).

<Example 17>

In the first embodiment, to design a three-dimensional structure of the structural layer is designed as shown in Figure 5, but located in the overlapping portion of the virtual first circle and second circle virtual contact with the circumference of the first circle and the second circle The third circle had a diameter of 10 µm, and the optical sheet was produced in the same manner except that the height h of the three-dimensional structure was set to 23 µm.

&Lt; Example 18 >

In Example 4, the optical third sheet was manufactured in the same manner except that the virtual third circle had a diameter of 20 µm and the height h of the three-dimensional structure was 21 µm.

&Lt; Example 19 >

In Example 1, to design a three-dimensional structure of the structural layer, it is designed as shown in Figure 3, wherein the diameter of the circumference of the virtual first circle and the second circle is 150㎛ and 250㎛, respectively, The length of the imaginary line L connecting the intersection points of the second circle is 145 μm, and is perpendicular to the imaginary line L connecting the two intersection points, and the angles at the overlapping portions of the first circle and the second circle are perpendicular to each other. The maximum length (d) between the circumference was 80㎛, the mold was produced so that the width (w) of the three-dimensional structure is 50㎛, height (h) 23㎛, acrylic ultraviolet curable resin composition (refractive index: 1.58) Was added to form an ultraviolet cured structural layer (refractive index: 1.60) to prepare an optical sheet.

Example 20

In the sixth embodiment, in order to design a three-dimensional structure of the structural layer, it is designed as shown in Figure 7, but located in the overlapping portion of the virtual first circle and the second circle virtual contact with the circumference of the first circle and the second circle In the third circle, a light converging optical sheet was manufactured in the same manner except that the diameter was 10 µm and the height h was 21 µm.

&Lt; Comparative Example 1 &

A light converging optical sheet was manufactured in the same manner as in Examples 1 to 14, except that a prism was manufactured using KOLON KF2 composition (general prism).

&Lt; Comparative Example 2 &

Friction and elastic modulus were measured using 3M BEF3.

Evaluation of physical properties of the optical sheet according to the embodiment was performed as described below, and the evaluation results are shown in Table 2 below.

(1) luminance evaluation

The optical sheet manufactured in Example was laminated on top of a diffusion sheet (manufacturer: Kolon, trade name: LX210), mounted on a backlight unit for a 17-inch liquid crystal display panel, and fixed, and a luminance meter (model name: BM-7, Japan TOPCON) The luminance was measured at any of 13 points using, and the average value was obtained.

(2) yellow band observation

The camera was photographed by a digital camera at about 40 degrees when the top and bottom viewing angles were observed, and about 50 degrees when the left and right viewing angles were observed.

(3) rainbow observation

When the upper and lower viewing angles were observed, the photographs were photographed by a digital camera in a section before the side lobe occurrence point at about 40 degrees or more.

(4) coefficient of friction

Fig. 10 shows a schematic diagram for evaluating the friction coefficient. In Fig. 10, ① slad (weight role, 200g, 63mm * 63mm), ② up sheet (fixed to ①), ③ evaluation sheet (vertical cutting in the moving direction) ), ④ pedestal (secure ③), ⑤ measuring instrument LLOYD LF-PLUS. The up sheet uses the same sheet as the evaluation sheet.

(First, the measurement sample (No. ③) is placed on the movable support (④) with the structural layer on top. Then, the back coating surface of the up sheet (②) And face it so that it is fixed to ① Next, stack it so that ② is on top of ③ as shown in Fig. 10. And move ① at a constant speed (250mm / min). Check the friction force and coefficient of friction through

The specific measurement standard was based on ASTM D 1894.

division Luminance evaluation Yellow band Rainbow Friction Coefficient (between Structural Layer and Back Coating Layer) Static friction coefficient Dynamic friction coefficient Example 1 100% Does not occur Does not occur 0.274 0.253 Example 2 100% Does not occur Does not occur 0.269 0.247 Example 3 100% Does not occur Does not occur 0.281 0.259 Example 4 100% Does not occur Does not occur 0.296 0.273 Example 5 100% Does not occur Does not occur 0.279 0.258 Example 6 100% Does not occur Does not occur 0.271 0.249 Example 7 100% Does not occur Does not occur 0.273 0.248 Example 8 100% Does not occur Does not occur 0.276 0.259 Example 9 100% Does not occur Does not occur 0.282 0.263 Example 10 100% Does not occur Does not occur 0.277 0.257 Example 11 100% Does not occur Does not occur 0.286 0.263 Example 12 100% Does not occur Does not occur 0.288 0.264 Example 13 100% Does not occur Does not occur 0.281 0.261 Example 14 100% Does not occur Does not occur 0.284 0.263 Example 15 80% Does not occur Does not occur 0.276 0.254 Example 16 100% Occurs but weak Occurs but weak 0.254 0.241 Example 17 95% Does not occur Does not occur 0.292 0.272 Example 18 90% Does not occur Does not occur 0.298 0.277 Example 19 87% Does not occur Does not occur 0.272 0.251 Example 20 82% Does not occur Does not occur 0.273 0.250 Comparative Example 1 104% Occurs Occurs 0.182 0.135 Comparative Example 2 101% Occurs Occurs 0.198 0.137

(5) D ₁ and elastic recovery rate

The optical sheet manufactured in Example was measured using a micro compression hardness meter (Shimadzu DUH-W201S) manufactured by Shimadzu Corporation, Japan, and D1 and elastic recovery rate were measured according to the 'Load-Unload test' item. In the center of the planar indenter having a diameter of 50㎛, the peak point of the mountain shape in the optical sheet structure layer is placed, and after measuring the D1 and the elastic recovery rate five times under the following conditions and the average value is shown in Table 3 below .

 [Measurement Condition 1]

a. Maximum compressive force applied: 1gf (= 9.807mN)

b. Compression force per hour: 0.2031mN / sec

c. Stop time at maximum compression: 5 sec

 [Measurement Condition 2]

a. Maximum compressive force applied: 2gf (= 19.614mN)

b. Compression force per hour: 0.2031mN / sec

c. Stop time at maximum compression: 5 sec

division D (μm) Measurement condition 1 Measurement condition 2 D ₁ (μm) D ₂ (μm) Elastic recovery rate (%) D ₁ (μm) D ₂ (μm) Elastic recovery rate (%) Example 1 219 10 1.2 88 13 1.8 86 Example 2 219 10 1.1 89 13 1.7 87 Example 3 219 12 0.8 93 15 1.5 90 Example 4 219 11 1.2 89 14 1.8 87 Example 5 219 10 1.2 88 12 1.8 85 Example 6 219 10 1.4 86 13 2.0 85 Example 7 219 10 1.2 88 14 2.0 86 Example 8 219 12 1.2 90 15 1.7 89 Example 9 219 13 1.0 92 12 1.3 89 Example 10 219 10 1.1 89 14 1.8 87 Example 11 219 11 1.0 91 13 1.6 88 Example 12 219 10 1.3 87 13 2.0 85 Example 13 219 12 1.1 91 14 1.7 88 Example 14 219 13 0.9 93 15 1.4 91 Example 15 206.5 5 0.4 92 7 0.8 88 Example 16 219 11 1.0 91 12 1.3 89 Example 17 217 11 1.2 89 13 1.7 87 Example 18 215 12 1.2 90 13 1.6 88 Example 19 2174 12 1.3 89 14 1.4 90 Example 20 215 12 1.2 90 14 1.7 88 Comparative Example 1 213 2 0.6 72 4 1.2 70 Comparative Example 2 213 3 0.8 73 5 1.5 71

As a result of evaluation of the physical properties of the optical sheet, in the optical sheets of Examples 1 to 20, no yellow band and rainbow were generated, the static friction coefficient was 0.254 or more, the dynamic friction coefficient was 0.241 or more, and the elastic recovery rate was 85% or more. I could see that. In the luminance evaluation, the luminance of the optical sheets of Examples 15 and 17 to 20 was slightly lower.

On the other hand, in the optical sheets of Comparative Examples 1 to 2, the luminance was more than 100%, yellow band and rainbow were generated, and both the static friction coefficient and the dynamic friction coefficient were less than 0.2, and the elastic recovery ratio was 70 ~ 73. It was determined to be%.

As such, the static friction coefficient or dynamic friction coefficient between the structural layer and the back coating layer is optimized in the base layer, the structural layer, and the back coating layer optical sheet, so that the physical properties such as luminance, yellow band, rainbow, elastic recovery rate, etc. are required without a separate protective layer in the optical sheet. It can be seen that can be maintained excellent.

100: won 1 200: won 2
300: third source 10: base layer
20: structural layer 21: inclined portion
22: peak portion 25: three-dimensional structure

Claims (12)

A base layer;
A structural layer formed on one surface of the base layer and having a plurality of three-dimensional structures arranged thereon; And
It is formed on the other side of the base layer and includes a back coating layer dispersed particles,
The optical sheet having a coefficient of static friction between the structural layer and the back coating layer is at least 0.2 or more.
The optical sheet of claim 1, wherein the coefficient of static friction between the structural layer and the back coating layer is 0.2 to 0.3.
The optical sheet of claim 1, wherein the coefficient of kinetic friction between the structural layer and the back coating layer is at least 0.2 or more.
The optical sheet of claim 1, wherein the coefficient of kinetic friction between the structural layer and the back coating layer is 0.2 to 0.3.
The method of claim 1, wherein the structural layer is pressurized using a planar indenter at a pressure of 0.203 mN / sec until the maximum compression force of 1 gf or 2 gf on the top surface of the three-dimensional structure, and stopped and compressed for 5 seconds when the maximum compression force is reached. After releasing the compressive force, the elastic sheet represented by the following equation 1 is 85% or more of the optical sheet.
Equation 1

In the above formula, D ₁ means the depth that is compressed by the external pressure is applied, D ₂ is the difference between the height of the optical sheet without the external pressure and the height of the optical sheet at the time of recovery by removing the external pressure. it means.
The three-dimensional structure of claim 1, wherein the three-dimensional structure of the structural layer has a slanted longitudinal section and includes an inclined portion extending in both directions with respect to one peak point, wherein the inclined portion is symmetrical or asymmetrical with respect to the peak point, each inclined portion An optical sheet that satisfies a shape that is a part of the circumference of the circumferential first circle and the circumference of the second circle.
7. The three-dimensional structure of claim 6, wherein the three-dimensional structure of the structural layer is perpendicular to the imaginary line connecting the two intersections of the imaginary first circle and the second circle and at the overlapping portions of the first circle and the second circle. A light converging optical sheet of 1/10 to 1 with respect to the maximum length between each circumference.
8. The maximum length of each circumference of the circumference of the first circle and the second circle while being perpendicular to the imaginary line connecting two intersection points of the imaginary first circle and the second circle is 50 ~. It is an optical sheet of 1000 micrometers.
The optical sheet according to claim 7 or 8, wherein the three-dimensional structure of the structural layer has a height of 1/20 to 1/2 with respect to an imaginary line length connecting two intersection points of the imaginary first circle and the second circle.
10. The optical sheet according to claim 9, wherein an imaginary line length connecting two intersection points of the imaginary first circle and the second circle is 1 to 1000 µm.
The optical sheet according to claim 8, wherein the peak portion is connected to the inclined portion, and the imaginary third circle has a diameter of 50 µm or less.
The optical sheet according to claim 7 or 8, wherein the steric structure of the structural layer is linearly arranged or nonlinearly arranged.

Images