KR20140135546A - Composite optical sheet and optical display device comprising the same - Google Patents

Abstract

The present invention relates to a composite optical sheet including a first base layer; an intermediate layer; a second base layer; and an optical pattern layer, and having thermal expansion coefficient of 100 micrometers/m°C at 60 to 80°C. Since the thermal expansion coefficient of the composite optical sheet is low, Wrinkling and bending may be minimized and peel resistance is excellent. Accordingly, the composite optical sheet represents excellent size stability and reliability. When an optical display device including the composite optical sheet is manufactured, processability is excellent, and a thin film of a display panel may be manufactured.

Description

Technical Field [0001] The present invention relates to a composite optical sheet and an optical display device including the composite optical sheet.

The present invention relates to a composite optical sheet and an optical display device including the composite optical sheet.

A liquid crystal display (LCD), which is one of the fields to which the present invention can be applied, generally includes an upper substrate on which a common electrode and a color filter are formed, a lower substrate on which a thin film transistor and a pixel electrode are formed A liquid crystal material is injected and an electric field is formed by applying different electric potentials to the pixel electrode and the common electrode to change the arrangement of the liquid crystal molecules and control the transmittance of light through the liquid crystal molecules. Since the liquid crystal display device is a light receiving element that can not emit light by itself, a backlight unit for supplying light is required.

BACKGROUND ART Generally, a backlight unit is composed of a diffuser plate or a light guide plate for converting light into a surface light source, a light source for supplying light, a linear light source or a point light source, and various optical sheets for improving optical performance. The optical sheet used for the backlight unit includes a light-condensing film for improving brightness, a diffusion film for performing a function of concealing defects on the backlight back surface, and a bright line of the light source.

In recent years, the thickness of the optical sheet is also minimized due to the slimming of the display panel. In order to minimize the overall thickness of the optical sheet, the thickness of the substrate layer must also be minimized. However, when the thickness of the base layer is reduced, the physical properties such as modulus and thermal stability of the optical sheet may be lowered, thereby causing serious problems in the reliability of the manufactured product.

It is an object of the present invention to provide a composite optical sheet with improved damping.

Another object of the present invention is to provide a composite optical sheet having a small amount of warping.

It is still another object of the present invention to provide a composite optical sheet excellent in dimensional stability and reliability.

It is still another object of the present invention to provide a composite optical sheet capable of thinning a display panel.

The above and other objects of the present invention can be achieved by the present invention described below.

One aspect of the present invention is a method for manufacturing a semiconductor device, comprising: a first base layer; Intermediate layer; A second base layer; And an optical pattern layer are sequentially laminated, and a coefficient of thermal expansion is 60 占 폚 to 80 占 폚 at 100 占 퐉 / m 占 폚 or less.

The composite optical sheet may satisfy the following formulas 1 and 2;

[Formula 1]

60 占 퐉? D1 + D2? 300 占 퐉

[Formula 2]

0.5? D1 / D2? 4

(D1 is the thickness of the first base layer, and D2 is the thickness of the second base layer).

The thickness of the intermediate layer may be 0.5 to 20 mu m.

The composite optical sheet may further include a light diffusion layer formed on the first base layer.

The optical pattern layer may be a pattern selected from the group consisting of a microlens pattern, a lenticular lens pattern, a prism pattern, a pyramid pattern, and a mixed pattern thereof.

The optical pattern layer may be a prism pattern formed on the second base layer, and the light diffusion layer may be a concavo-convex pattern formed on the bottom of the first base layer.

Wherein the unit prisms constituting the prism pattern have a height of 20 to 40 占 퐉 and a pitch of 40 to 80 占 퐉, the unevenness pattern has a surface roughness Ra of 0.01 to 2 占 퐉, Rz of 0.1 to 5 占 퐉, 10 mu m.

The first base layer and the second base layer may be made of the same material, and the intermediate layer may be a material different from the first base layer and the second base layer.

The first base layer or the second base layer may be formed of a resin such as a polyacetal resin, an acrylic resin, a polycarbonate resin, a styrene resin, a polyester resin, a vinyl resin, a polyphenylene ether resin, a polyolefin resin, Acrylonitrile-butadiene-styrene copolymer resin, a polyaryl sulfone resin, a polyether sulfone resin, a polyphenylene sulfide resin, a polyethylene naphthalate resin, or a fluorine resin.

The intermediate layer may comprise a cured product of a urethane acrylate oligomer.

The optical pattern layer and the light diffusion layer may include an ultraviolet curable unsaturated compound.

The maximum height C of the composite optical sheet bent from the bottom of the composite optical sheet after aging at room temperature for 120 hours at 85 캜 and 85% relative humidity may be 40 mm or less.

Another aspect of the present invention is to provide an optical display device including the composite optical sheet.

The composite optical sheet of the present invention has a low coefficient of thermal expansion, minimizes the development and deflection, and is excellent in peel resistance. As a result, the composite optical sheet is excellent in dimensional stability and reliability, has excellent processability in the manufacture of an optical display device including the composite optical sheet, and can produce a thin film of a display panel.

1 shows a perspective view of a composite optical sheet according to one embodiment of the present invention.
2 shows a cross-sectional view of a composite optical sheet according to one embodiment of the present invention.
3 is a conceptual diagram of the measurement of the deflection amount of the composite optical sheet.
4 shows a perspective view of an optical display device including a composite optical sheet according to an embodiment of the present invention.
5A and 5B show a sheet as an evaluation criterion of the test, wherein (a) shows a case where there is no atomic phenomenon, (b) shows a case where there is a slight phenomenon, and Respectively.
6 is a graph showing a change in thickness of the composite optical sheet according to Example 1 with temperature change.

Embodiments of the present application will now be described in more detail with reference to the accompanying drawings. However, the techniques disclosed in the present application are not limited to the embodiments described herein but may be embodied in other forms. It should be understood, however, that the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the width, thickness, and the like of the components are enlarged in order to clearly illustrate the components of each device. In addition, although only a part of the components is shown for convenience of explanation, those skilled in the art will be able to easily grasp the rest of the components. It is to be understood that when an element is described above as being located above or below another element, it is to be understood that the element may be directly on or under another element, It means that it can be done. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. In the drawings, the same reference numerals denote substantially the same elements.

Composite optical sheet

The composite optical sheet of the present invention comprises a first base layer; Intermediate layer; A second base layer; And an optical pattern layer are sequentially laminated.

1 shows a perspective view of a composite optical sheet according to an embodiment of the present invention. 1, the composite optical sheet 100 includes a base layer composed of a first base layer 110 and a second base layer 130, and the first base layer 110 and the second base layer 130 (Not shown).

As the area of the optical sheet formed of the single base layer becomes wider, the distortion of the sheet or the roughness of the sheet can easily occur. The optical sheet is composed of two kinds of base layers composed of the first base layer and the second base layer in order to minimize the warping phenomenon or the obtius phenomenon of the sheet even if the optical sheet is made large or minimized in thickness .

2 is a cross-sectional view of a composite optical sheet to explain thickness ratios of the respective layers constituting the composite optical sheet. Referring to FIG. 2, when the thicknesses of the first base layer 110 and the second base layer 120 are D1 and D2, the following equations 1 and 2 can be satisfied.

[Formula 1]

60 占 퐉? D1 + D2? 300 占 퐉

[Formula 2]

0.5? D1 / D2? 4

When the thicknesses D1 and D2 of the first base layer and the second base layer are out of the range of the above formula 1, the rigidity of the base layer having a relatively low thickness is low, so that the processability can be lowered and the effect of improving the bending property can be sufficiently secured I can not.

Also, as shown in Formula 2, the value of D1 / D2 may be 0.5 to 4, preferably 0.5 to 2. When the D1 / D2 value range is satisfied, a sufficient strength can be secured and the damping phenomenon can be improved.

The intermediate layer 120 may be formed between the first base layer 110 and the second base layer 130. The intermediate layer 120 can be formed by a method in which the optical sheet of the present invention composed of two kinds of base layers secures a modulus equal to or more than that of a conventional single base layer and a stress that may occur between the first base layer and the second base layer It is introduced in order to alleviate stability such as bending due to heat.

In the case where the intermediate layer is not provided, that is, the composite film formed of the single base layer is insufficient in stability against heat and humidity, and therefore, it is difficult to exhibit a uniform luminance.

The thickness of the intermediate layer may be thinner than that of the first base layer and the second base layer.

In one embodiment, the thickness M1 of the intermediate layer may be 0.5 to 20 占 퐉, preferably 1 to 10 占 퐉. When the thickness of the intermediate layer is 0.5 mu m or less, the effect of improving the phenomenon of misting is insignificant, the heat shrinkability of the intermediate layer for suppressing thermal expansion of the base layer can not be ensured, and the peeling resistance between the first base layer and the second base layer is sufficiently Can not be secured. On the other hand, as the thickness of the intermediate layer increases, the improvement of the damping phenomenon and the heat shrinkage of the intermediate layer may increase. However, there is a critical point at which the improvement of the damping phenomenon is no longer caused by the increase of the thickness. In view of thinning of the display panel, Mu] m.

An optical pattern layer 140 may be further provided on the light outgoing surface of the second base layer 130. 1 and 2 show a composite optical sheet in which a prism pattern is formed by an optical pattern layer, the optical pattern layer is not limited to a prism pattern but may be a micro lens pattern, a lenticular lens pattern, a prism pattern, a pyramid pattern, A pattern selected from the group consisting of patterns may be formed, but it may be a light-collecting pattern, and more preferably a prism pattern. For example, when the optical pattern layer is a prism pattern, the height of the unit prisms constituting the prism pattern may be 20 to 40 탆, and the pitch may be 40 to 80 탆.

In another embodiment of the present invention, a light diffusion layer may be further formed on the other surface of the first base layer. A pattern for a diffusion function may be formed on one surface of the light diffusion layer, for example, a concavo-convex pattern may be formed. The light-diffusing layer may be formed by sandblasting, for example, sanding the surface of a pulling roll with a bead having a diameter of 1 to 200 mu m to form a concavo-convex pattern, To the surface of the substrate. Specifically, an ultraviolet ray hardening resin is injected between the stamp roll formed with the relief pattern and the first base layer so that the stamp roll is passed through the first base film while being in contact with the ultraviolet ray curable resin. At this time, UV can be cured by irradiating the curable resin to form a light diffusion layer on the first base layer. The concavo-convex pattern of the light-diffusing layer has a surface roughness Ra of 0.01 to 2 占 퐉, Rz of 0.1 to 5 占 퐉, and Ry of 1 to 10 占 퐉 as measured by a three-dimensional measuring machine. In this range, the diffusion efficiency due to surface scattering increases and the shielding force can be improved. The surface roughness can be measured by the standard of JIS B0601: 1994. Specifically, the surface roughness of the measuring device can be measured using a VK-9700 manufactured by Keyence. At this time, the surface roughness can be measured by setting the measurement magnification to 1000 magnification and the Z axis pitch to 1 nm.

The first base layer and the second base layer may be made of the same material, and the intermediate layer may be a material different from the base layer.

The first base layer and the second base layer may be formed of a material selected from the group consisting of a polyacetal resin, an acrylic resin, a polycarbonate resin, a styrene resin, a polyester resin, a vinyl resin, a polyphenylene ether resin, a polyolefin resin, Acrylonitrile-butadiene-styrene copolymer resin, a polyaryl sulfone resin, a polyether sulfone resin, a polyphenylene sulfide resin, a polyethylene naphthalate resin, or a fluorine resin.

The intermediate layer may be formed by applying a composition for forming an intermediate layer on one surface of the first base layer, and then laminating the second base layer, followed by heat or UV curing. As an example of the application method of the composition for forming an intermediate layer, an intermediate layer is formed by coating on one entire surface of the first base layer using a die coater, a gravure coater, a microgravure coater, a reverse coater, a knife coater or a comma coater Can

The composition for forming an intermediate layer may include a (meth) acrylate oligomer, a monofunctional or polyfunctional (meth) acrylate monomer, and a photoinitiator.

As the (meth) acrylate oligomer, urethane (meth) acrylate oligomer or epoxy (meth) acrylate oligomer may be used. Specifically, it may include at least one member selected from the group consisting of a urethane (meth) acrylate oligomer having a weight average molecular weight ranging from 2,000 to 100,000 and an epoxy (meth) acrylate oligomer having an average molecular weight ranging from 500 to 30,000 . Preferably, the urethane (meth) acrylate having a weight average molecular weight of 10,000 to 50,000 can be used in an amount of 40 to 90 parts by weight based on the composition.

As the (meth) acrylate-based monomer, one or more (meth) acrylate-based monomers containing an epoxy group, a carboxyl group or a hydroxy group may be used. Preferred examples of the hydroxy group-containing (meth) acrylate-based monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylate, 1-hydroxybutyl (meth) acrylate, polycaprolactone polyol mono (meth) acrylate, 2-hydroxy-3-phenyloxy (Meth) acrylate, 2-hydroxypropyl acrylate, 2-acryloyloxyethyl 2-hydroxyethyl phthalate, di (meth) acrylate-based bisphenol A : SK-UCB), and the like. Examples of the (meth) acrylate monomer containing an epoxy group include (meth) acrylates containing glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate and alicyclic epoxy (M100 or A200 of Daicel Co.), and examples of the (meth) acrylate monomer containing a carboxyl group include 2-methacryloyloxyethylhexahydrophthalate and 2-methacryloyloxyethylenecarboxylate. .

In the present invention, a (meth) acrylate monomer may be used to control the viscosity of the composition. Examples of such (meth) acrylate monomers include neopentyl glycol mono (meth) acrylate, 1,6-hexanediol mono (Meth) acrylate, pentaerythritol penta (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerin di (meth) acrylate, tetrahydroperfuryl (meth) acrylate acrylate, isodecyl (meth) acrylate, 2- (2-ethoxy) ethyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, Acrylate, ethoxylated nonylphenolacryl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, isobonyl (meth) acrylate, tridecyl ate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (Meth) acrylate, ethoxy added bisphenol-di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, tripropylene glycol di (Meth) acrylate such as cyclohexanedimethanol di (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, 2-methacryloyloxyethyl phosphate, 2-hydroxymethacryloyloxyethyl phosphate, dimethylol tricyclodecane Di (meth) acrylate, dipentaerythritol hexaacrylate, trimethylopropane benzoate acrylate, and mixtures thereof. Or more can be used.

Preferably, 20 to 40 parts by weight of 2-hydroxyethyl acrylate is used as the (meth) acrylate-based monomer, trimethylpropane triacrylate (Sartomer, SR351) To 5 parts by weight to 20 parts by weight.

The photoinitiator may be an alpha-hydroxy ketone type compound, a benzyl ketal type compound, or a mixture thereof, but is not limited thereto. Hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone, and the like. These photoinitiators may be used alone or in combination of two or more. The photoinitiator may be used in an amount of 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the (meth) acrylate-based copolymer. Specifically, 2 parts by weight of TPO from Ciba and 3 parts by weight of Irgacure 819 can be used.

The composition for forming an intermediate layer may further contain conventional additives such as a coupling agent, a curing accelerator, a tackifier resin, a modified resin, an ultraviolet absorber, a leveling agent, a defoamer, a plasticizer, a dispersant, a heat stabilizer, a light stabilizer, .

The optical pattern layer and the light-diffusing layer may include a cured product of a composition including an ultraviolet curable unsaturated compound, an initiator, and the like. In one example, the ultraviolet ray-curable unsaturated compound includes a fluorene derivative unsaturated resin and a phenoxybenzyl (meth) acrylate, phenylphenoxyethyl (meth) acrylate, ethoxylated thiodiphenyl di Thioethyl (meth) acrylate monomers, or oligomers thereof, but are not limited thereto.

Fig. 3 is a conceptual diagram of the amount of deflection of the composite optical sheet. The maximum height C curved from the bottom 200 of the composite optical sheet 100 is measured as a deflection.

The composite optical sheet of the present invention has a composite optical sheet having a width of 170 mm, a length of 100 mm, and a thickness of 230 mm at 85 ° C and a relative humidity of 85% for 120 hours, aging at 25 ° C for 4 hours, The maximum height C curved from the bottom of the optical sheet may be 20 mm or less. Within this range, the composite optical sheet can have excellent reliability and dimensional stability.

In addition, the composite optical sheet of the present invention may have a coefficient of thermal expansion of 100 占 퐉 / m 占 폚 or less. M, preferably not more than 10 mu m / m DEG C, and more preferably not more than 0 mu m / m DEG C. In the case of a composite optical sheet having the above-described range of the thermal expansion coefficient, the thermal expansion of the optical sheet due to the heat source generated in the backlight unit is suppressed, which minimizes the phenomenon of disturbing the uniform light luminance. The thermal expansion coefficient was measured by DMA (Dymamic mechanical analysis) (TA company, Q400 model). There are various methods depending on the purpose of measurement, but they are measured using the expansion method. The specimen size of the optical sheet was set to 1 cm x 1 cm. The thermal expansion coefficient was calculated by changing the thickness of the optical sheet by increasing the temperature at a temperature range of 60 ° C to 80 ° C while heating at a starting temperature of 25 ° C, a temperature raising rate of 5 ° C / min, and a termination temperature of 80 ° C.

Optical display device

An optical display device which is another aspect of the present invention may include the composite optical sheet. In the optical display member, the composite optical sheet may be comprised of a prism sheet, a diffusion sheet, or a light guide plate. The optical display device may include a liquid crystal display, and the light source in the liquid crystal display may include an LED lamp or a CCFL.

4, an optical display device 300 according to an exemplary embodiment of the present invention includes a light source 210, a light guide plate 220 for guiding light emitted from the light source 210, a light guide plate A diffusion sheet 240 disposed on the upper portion of the light guide plate 220, a composite optical sheet 100 disposed on the diffusion sheet 240, and a composite optical sheet And a protective sheet 260 disposed on an upper portion of the substrate 100. [ In addition, a light source cover 210a may be disposed outside the light source 210 of the backlight unit. Here, although not shown, a liquid crystal display panel and an antireflection layer are sequentially stacked on the optical display device 300 to form a liquid crystal display device.

The light source 210 generates light, and various light sources such as a linear light source lamp, a planar light source lamp, a CCFL, or an LED may be used.

The light guide plate 220 guides the light generated from the light source 210 to the diffusion sheet 240, and may be omitted when a direct-type light source is employed.

The reflective sheet 230 reflects light generated from the light source 210 and supplies the light to the diffusion sheet 240.

The diffusion sheet 240 diffuses and scatters light incident through the light guide plate 220 and supplies the light to the composite optical sheet 100.

The composite optical sheet 100 refracts light incident through the diffusion sheet 240 and condenses the light onto a plane of a liquid crystal display panel (not shown). The composite optical sheet has a variety of design variations and combinations such as the shape of the light collecting portion and the angle of the inclined portion of the light collecting portion according to various design goals such as high condensing efficiency, wide viewing angle, prevention of moire phenomenon, and prevention of optical outflow And is commercially available.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples. The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Example  One

The first base layer, the intermediate layer, the second base layer and the optical pattern layer were sequentially laminated to produce a composite optical sheet.

The first base layer and the second base layer were made of PET (T600E38WM13) manufactured by Mitsubishi, and the intermediate layer was composed of 92 wt% of a (meth) acrylate oligomer resin (NP-S20, 5% by weight of a monomer (Sartomer SR351) and 3% by weight of a photoinitiator (Ciba TPO).

The optical pattern layer was a prism pattern having a height of 25 占 퐉 and a pitch of 50 占 퐉, and 92% by weight of two kinds of ultraviolet curing resins (Polynetron PN6310 and PN2020) mixed at a ratio of 1: 1, and a trifunctional acrylate structure 5% by weight of a phosphorus monomer (Sartomer SR454) and 3% by weight of a photoinitiator (Ciba TPO).

A prism pattern layer was prepared by coating a prism pattern on one surface of a first base layer with a gravure roll and then curing by ultraviolet rays. The second base layer was laminated on the other surface of the first base layer through an intermediate layer having the above composition, To prepare an optical sheet.

The thicknesses of the first base layer, the second base layer and the intermediate layer are as shown in Table 1 below, and the properties of the resultant composite optical sheet were measured and are shown together in Table 1 below.

Example  2-3

Composite optical sheets were prepared in the same manner as in Example 1 except that the first optical resin layer and the second optical resin layer were formed to have the thicknesses shown in Table 1 below, .

Comparative Example  1 - 2

Composite optical sheets were prepared in the same manner as in Example 1 except that a first base layer having a thickness of the following Table 1 was used as a single base layer, and physical properties were measured and shown in Table 1 below.

Property evaluation method

1. Bending amount ( mm ) : The composite optical sheet having the thicknesses of 50 mm x 100 mm and the thicknesses of the respective layers set forth in Table 1 was allowed to stand at 85 DEG C and 85% RH for 120 hours, followed by aging at room temperature for 4 hours. In the present specification, ambient temperature means 25 캜 3 캜 unless otherwise specified, and humidity means about 40% 5%. The warping amount was measured according to FIG. 3 at the maximum height (C) curved from the bottom of the composite optical sheet before and after the evaluation.

2. Test : Place the composite optical sheet on a satin glass and attach both corners to the nitto tape. After covering the composite optical sheet with a rectangular glass, the central part of the four sides was fixed with a tape to fix the glass, composite optical sheet, and ordinary glass, and then maintained at 75 ° C and a relative humidity of 99% for 15 minutes After lowering the temperature to 5 ° C, keep it for 10 minutes. Thereafter, the same light source as that of the backlight unit was placed on the rear surface, and then a glass plate on which a single polarizing film or one polarizing film was coated was placed on the composite optical sheet, and the glass was visually observed. 5 (a) shows a case in which there is no atomic phenomenon, (b) shows a case in which an atomic phenomenon is somewhat, and (c) shows an example in the case of an atomic phenomenon Respectively. The greater the darkness, the more significant the difference between the contrast and the darkness.

○:

△: There is a slight phenomenon.

×: There is a phenomenon.

3. Thermal Expansion Coefficient : DMA (Dymamic mechanical analysis) (TA company, Q400 model) was used as the measuring instrument and measured by the expansion method. The specimen size of the optical sheet was set to 1 cm x 1 cm. The thermal expansion coefficient was calculated by changing the thickness of the optical sheet by increasing the temperature at a temperature range of 60 ° C to 80 ° C while heating at a starting temperature of 25 ° C, a temperature raising rate of 5 ° C / min, and a termination temperature of 80 ° C. The coefficient of thermal expansion can be obtained by the formula of thickness change / unit length / temperature range. As an example, FIG. 6 is a graph showing a thickness change according to a temperature change of the composite optical sheet of Example 1, from which the thermal expansion coefficient can be obtained.

Example
One Example 2 Example
3 Example
4 Example
5 Example 6 Comparative Example
One Comparative Example
2 two
To
(탆) The first base layer (D1) 38 50 50 75 100 150 75 150 The second base layer (D2) 38 50 75 50 50 38 - - The intermediate layer (M1) 2 4 5 5 6 10 - - D1 / D2 One One 0.67 1.5 2 3.95 - - Deflection (mm) 4 4 3 3 4 2 5 5 Coefficient of thermal expansion
(60 to 80 DEG C, m / m DEG C) -191 -150 -86 -85 -38 4 165 195 Um test O X

As shown in Table 1, the composite optical sheets of Examples 1 to 6, in which an intermediate layer was introduced between two kinds of base layers, had a thermal expansion coefficient of D1 to D2 satisfying the above-mentioned Formula 1 and Formula 2, 100 占 퐉 / m 占 폚 or less, it is found that the test test is insignificant and the warpage is small, and thus the dimensional stability and reliability are excellent.

In Comparative Example 1, a single substrate layer having a relatively small thickness was used, but the warpage amount was large and the reliability could not be ensured. In Comparative Example 2, a single base layer having a relatively large base layer thickness was used. However, not only the bending amount was large but also the thermal expansion coefficient was remarkably increased to cause a damping phenomenon, and the dimensional stability and reliability were not sufficiently secured.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (13)

A first base layer; Intermediate layer; A second base layer; And an optical pattern layer are sequentially laminated,
Wherein the coefficient of thermal expansion is 60 占 폚 to 80 占 폚 at 100 占 퐉 / m 占 폚 or less. The method according to claim 1,
A composite optical sheet satisfying the following formulas 1 and 2;
[Formula 1]
60 占 퐉? D1 + D2? 300 占 퐉
[Formula 2]
0.5? D1 / D2? 4
(D1 is the thickness of the first base layer, and D2 is the thickness of the second base layer). The method according to claim 1,
Wherein the intermediate layer has a thickness of 0.5 to 20 占 퐉. The method of claim 3,
Wherein the intermediate layer has a thickness of 1 to 10 mu m. The method according to claim 1,
And a light diffusing layer formed on the first base layer. 6. The method of claim 5,
Wherein the optical pattern layer is a prism pattern formed on the second base layer,
Wherein the light diffusion layer is a concavo-convex pattern formed in a lower portion of the first base layer. The method according to claim 6,
The unit prisms constituting the prism pattern have a height of 20 to 40 mu m and a pitch of 40 to 80 mu m,
The concavo-convex pattern has a surface roughness Ra of 0.01 to 2 占 퐉, Rz of 0.1 to 5 占 퐉, and Ry of 1 to 10 占 퐉. The method according to claim 1,
Wherein the optical pattern layer is a pattern selected from the group consisting of a microlens pattern, a lenticular lens pattern, a prism pattern, a pyramid pattern, and a mixed pattern thereof. The method according to claim 1,
Wherein the first base layer and the second base layer are made of the same material and the intermediate layer is a material different from the first base layer and the second base layer. The method according to claim 1,
The first base layer or the second base layer may be formed of a resin such as a polyacetal resin, an acrylic resin, a polycarbonate resin, a styrene resin, a polyester resin, a vinyl resin, a polyphenylene ether resin, a polyolefin resin, A composite optical sheet comprising at least one of an acrylonitrile-butadiene-styrene copolymer resin, a polyaryl sulfone resin, a polyether sulfone resin, a polyphenylene sulfide resin, a polyethylene naphthalate resin, or a fluorine resin. The method according to claim 1,
Wherein the intermediate layer comprises a cured product of a urethane acrylate oligomer. The method according to claim 1,
Wherein the composite optical sheet is allowed to stand at 85 캜 and 85% RH for 120 hours and aged at room temperature for 4 hours, and then the maximum height C curved from the bottom of the composite optical sheet is 40 mm or less. A display device comprising the composite optical sheet according to any one of claims 1 to 12.

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