JP2008003515A - Optical sheet and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet having excellent condensation function and light diffusion function, capable of reducing the effect of sidelobe by effectively using a sidelobe light and having high rising rate of luminance in a desired angle direction, particularly in the front face direction and an efficient and high precision manufacturing method thereof. <P>SOLUTION: The optical sheet has a supporting body having a first surface on which rugged parts to condense or diffuse light are formed and an optical control part having optical properties different from that of the supporting body. The optical control part is formed at least on one part of a non-passing part of light in the supporting body when light parallel to the normal direction of a second surface positioned on an opposite side to the first surface enters from the first surface side and is formed from a material intrinsically having no visile light absorption. The method of manufacturing the same is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical sheet that is used in a display such as a liquid crystal display device, a display device, a lighting device, and the like, and has an excellent light collecting function or light diffusion function, and a method for manufacturing the same. In particular, the present invention relates to an optical sheet that reduces the influence of the side lobe by effectively using side lobe light and has an excellent luminance increase rate in a desired angular direction (for example, the front direction), and a method for manufacturing the same.

In recent years, a lens film for condensing light from a light source such as a light guide plate in a front direction, a diffusion sheet for diffusing, and the like are used for applications such as liquid crystal display elements and organic EL displays.
For example, in a direct-type backlight used in a television or the like as shown in FIG. The light is refracted and transmitted, the angle of emission changes, and the light is emitted in the front direction. The reflected light from the condensing film 41 is reflected by the surfaces of the light source 42, the diffusing plate 43, the diffusing sheet 44, etc. and enters the condensing film 41 again.
With such a configuration, the luminance distribution of the emitted light from the light source is widely dispersed and the front luminance is low. Therefore, the light from the light source is transmitted in the front direction by the condensing film 41. The directional characteristics have been improved to increase the brightness.

FIG. 2 is a cross-sectional view showing an optical path in the light collecting film (optical sheet) 41 as described above. As shown in FIG. 2, when the incident light is refracted and transmitted through the condensing film 41, the component A is refracted in the front direction, the component B is refracted in the direction away from the front instead of the front direction, and the surface. It is divided into the component C to be reflected. Among these light components, the component A is emitted in the front direction, that is, the observation direction, and is actually used. The reflected component C is diffusely reflected on the surface of a diffusion sheet or the like to change the angle of incidence on the condensing film, and part of the component C is converted to component A and emitted in the front direction. By repeating this reflection, most of the component C is converted to the component A, and the luminance in the front direction of the exit surface is increased.
On the other hand, the component B of light that passes through the X portion in FIG. 2 is light that is emitted at a wide angle outside the effective viewing angle of a liquid crystal display device or the like (hereinafter referred to as sidelobe light) and has a front luminance. It is lost as wasted light that does not contribute to the increase. For this reason, not only the brightness is lowered, but also an image having a high brightness is observed again at an angle extremely away from the normal direction of the screen, resulting in an uncomfortable image.

In order to solve such problems, a reflecting member that reflects side lobe light is provided on the opposite side of the prism surface of the prism sheet (light collecting sheet), and the side lobe light can be reused by this reflection. Has been proposed (see Patent Document 1).
However, this reflection member is less than two-thirds the size of the prism pattern, and is only described as being located in the valleys of the prism pattern, so that it accurately identifies the position where the sidelobe light can be effectively reflected. Therefore, there is a possibility that the side lobe light cannot be effectively used. Further, there is no disclosure about a specific method for forming the reflecting member.
Further, a proposal has been made to prevent the generation of sidelobe light by providing a light blocking portion on the prism sheet (see Patent Document 2). This Patent Document 2 discloses a specific method for forming the light absorbing portion, and uses the presence or absence (light density of light density) of an optical path through which the irradiated light enters by entering light from a specific direction. By using the self-alignment method, a light transmitting portion and a light absorbing portion are separately formed. Only the part through which the light passes (the part with high light density) is used as the transmission part, and the part through which the light does not pass (part with low light density) is used as the light blocking part.
However, in this case, light is not irradiated from the front direction to form a light transmission part and a light absorption part, but from a direction of 35 to 71 ° with respect to the front direction (normal direction of the prism sheet). Since it irradiates, it is unsuitable for the object of condensing light in the front direction. Further, since a black light absorbing layer is used as the light blocking portion, there is a problem that side lobe light is absorbed, effective light use is hindered, and luminance cannot be improved.

  Therefore, an optical sheet that has an excellent light collecting function or light diffusion function, reduces the influence of the side lobe by effectively utilizing side lobe light, and has an excellent luminance increase rate in a desired angular direction, particularly in the front direction. In addition, an efficient and highly accurate manufacturing method has not yet been provided, and further improvements and developments are desired.

JP 2006-79040 A JP 2006-119166 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention has an excellent light collecting function or light diffusing function, and by effectively using sidelobe light, the influence of the sidelobe is reduced, and a luminance increase rate in a desired angular direction, particularly in the front direction, is achieved. An object is to provide an excellent optical sheet and an efficient and highly accurate manufacturing method thereof.

Means for solving the problems are as follows. That is,
<1> An optical sheet formed of a material that has essentially no visible light absorption,
A support having a first surface on which concave and convex portions that collect or scatter light are formed;
An optical preparation part having different optical properties from the support,
The light in the support when the optical adjustment unit receives light parallel to the normal direction of the second surface located on the opposite side of the first surface from the first surface side An optical sheet formed on at least a part of the non-passing portion.
<2> The optical sheet according to <1>, wherein the optical property is light reflectivity.
<3> The optical sheet according to <1>, wherein the optical property is light diffusibility.
<4> The optical sheet according to <1>, wherein the optical property is a difference in refractive index.
<5> The optical sheet according to any one of <1> to <4>, wherein the support has a multilayer structure of two or more layers.
<6> The optical sheet according to any one of <1> to <4>, wherein the uneven portion has a prism structure.
<7> The optical sheet according to <6>, wherein the prism structure is an isosceles triangle having an apex angle of 60 to 120 °.

<8> The method for producing an optical sheet according to any one of <1> to <7>,
A photosensitive layer forming step of forming a photosensitive layer on the second surface of the support on which at least the concave and convex portions for condensing or scattering light are formed on the first surface, the side being opposite to the first surface. When,
From the first surface side of the support, an exposure step of exposing the photosensitive layer by entering light parallel to the normal direction of the second surface;
An optical adjustment portion forming step of forming an optical adjustment portion, which is a non-exposed portion of the photosensitive layer, and has an optical property different from that of the support on the support;
It is a manufacturing method of the optical sheet characterized by including.
<9> The method for producing an optical sheet according to <8>, including a step of forming at least one second support on the second surface side of the support.
<10> From <8> to <8> above, wherein the photosensitive layer is a positive photosensitive layer, the exposed photosensitive layer is removed by development, and an optical adjustment portion is formed on at least a part of the unexposed photosensitive layer. 9>. The method for producing an optical sheet according to any one of 9).
<11> The photosensitive layer is a negative photosensitive layer, the photosensitive layer in the non-exposed portion is removed by development, and the optical adjustment portion is formed in at least a part of the removed region of the photosensitive layer. 8> to <9>. The method for producing an optical sheet according to any one of <9>.
<12> The photosensitive layer is a photo-curing positive photosensitive layer, and an optical adjustment unit is formed on at least a part of the photosensitive layer of the non-exposed portion by utilizing a change in adhesiveness due to exposure. 8> to <9>. The method for producing an optical sheet according to any one of <9>.
<13> The concavo-convex portion of the support is formed by applying a coating liquid containing a photocurable resin onto the support, exposing and curing the coating liquid, according to any one of <8> to <12>. It is a manufacturing method of this optical sheet.

  <14> A display device comprising the optical sheet according to any one of <1> to <7> on a display surface.

The optical sheet of the present invention is an optical sheet formed of a material that essentially does not absorb visible light, and has a first surface on which an uneven portion for condensing or scattering light is formed; The support has at least an optical preparation section having optical properties different from each other, and the optical preparation section is located on a side opposite to the first surface from the first surface side. It is characterized in that it is formed in at least a part of the non-passing portion of the light in the support when light parallel to the normal direction of the surface is incident.
For this reason, the optical adjustment unit adjusts the optical path of the sidelobe light, so that the sidelobe light can be effectively used. It is possible to provide an optical sheet having an excellent luminance increase rate.

In the method for producing an optical sheet of the present invention, an uneven portion forming step of forming an uneven portion for condensing or scattering light on at least a first surface of a support, and a side opposite to the first surface of the support A photosensitive layer forming step of forming a photosensitive layer on the second surface located on the first surface side, and light parallel to the normal direction of the second surface is incident from the first surface side of the support. An exposure step for exposing the layer, and an optical adjustment portion forming step for forming an optical adjustment portion, which is a non-exposed portion of the photosensitive layer, having an optical property different from that of the support on the support. Become.
For this reason, it is possible to effectively use sidelobe light, an optical sheet having excellent light collecting function or light diffusing function, and excellent brightness increase rate in a desired angular direction, particularly in the front direction, with high accuracy and efficiency. Can be manufactured.

  According to the present invention, the conventional problems can be solved, the light collecting function or the light diffusing function is excellent, and the side lobe light is effectively used, thereby reducing the influence of the side lobe, and the desired angular direction, particularly the front surface. It is possible to provide an optical sheet excellent in the luminance increase rate in the direction and an efficient and highly accurate manufacturing method thereof.

(Optical sheet)
The optical sheet of the present invention includes at least a support and an optical adjustment unit.
The optical sheet of the present invention must be essentially free of visible light absorption.
Visible light absorptivity here means having the property of finally converting the absorbed light energy into heat inside the optical sheet, specifically, among the light absorption according to Lambert Beer's law, It means a visible light absorbing material, and those that absorb light in the ultraviolet or infrared region are excluded. Also, those having total reflection, Fresnel reflection, metallic luster and the like inside the optical sheet are excluded from visible light absorption because they reflect light with essentially no light absorption.
It is ideal that the visible light absorbency is zero, but it is difficult to substantially reduce the visible light absorbability to zero. It is preferable for improving the utilization efficiency. For this purpose, it is desirable not to use a material that absorbs visible light even in the light non-passing portion (any portion where the light flux density is low).

<Support>
The support has a first surface on which concave and convex portions for condensing or scattering light are formed, and has a second surface at a position opposite to the first surface. As said support body, you may form an uneven | corrugated | grooved part also in said 2nd surface.
The concavo-convex portion is not particularly limited as long as it is a fine concavo-convex portion that can collect or scatter light, and can be appropriately selected according to the purpose. For example, a prism structure is preferable.

  The support is not particularly limited in its shape, structure, size, thickness, material, and the like, and can be appropriately selected according to the purpose. Examples of the shape include a plate shape and a sheet shape. The structure may be a single layer structure or a laminated structure, and the size may be appropriately selected according to the size of the optical sheet. There is no restriction | limiting in particular, Although it can select suitably according to the objective, As a shape of a support body, rectangular shape, square shape, circular shape etc. are mentioned, for example.

The structure of the support may be, for example, a single layer or a multilayer structure in which two or more layers are provided.
When two or more layers of the support are provided to form a multilayer structure, for example, a second or more sheet-like support may be bonded to the first support, or the surface of the first support may be bonded. Alternatively, a coating solution containing a photocurable resin for forming the second support may be applied, exposed and cured.

  There is no restriction | limiting in particular as thickness of the said support body, Although it can select suitably according to the objective, For example, 0.005-4.0 mm is preferable. Here, the thickness of the support is, for example, a film thickness meter that measures the thickness of the support by sandwiching the support with a measuring meter, or a non-contact film thickness that measures the thickness of the support using optical interference. It can be measured by using a meter or the like.

The material for the support is not particularly limited as long as it is essentially transparent without visible light absorption and has a certain degree of strength (rigidity), and can be appropriately selected according to the purpose. For example, both inorganic materials and organic materials can be suitably used.
Specifically, the rigidity represents physical properties of the support that can be measured as the Taber stiffness described in the JIS P8125 standard.
Examples of the inorganic material include glass, quartz, and silicon.
Examples of the organic material include acetate resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyethersulfone resins, polysulfone resins, polycarbonate resins, and polyamides. Resin, polyimide resin, polyolefin resin, acrylic resin, polynorbornene resin, cellulose resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, Examples thereof include polyacrylic resins. These may be used individually by 1 type and may use 2 or more types together.

Specific examples of the support having the uneven portions include a prism sheet, a lenticular sheet, a fly-eye lens sheet in which lenses are arranged in a fly's eye shape, and a diffusion having uneven surfaces formed using spherical particles. Sheet, and the like.
As the prism sheet, a plurality of long prism lenses having a triangular cross-section perpendicular to the length direction may be arranged on a support, or a triangular pyramid or a quadrangular pyramid. A plurality of prism lenses having a shape or the like may be two-dimensionally arranged on the support in a two-dimensional manner at regular intervals or at random (hereinafter sometimes referred to as a pyramid sheet). Further, the support may be formed with recesses such as a triangular pyramid shape and a quadrangular pyramid shape formed two-dimensionally at regular intervals or randomly (hereinafter sometimes referred to as an inverted pyramid sheet).
As the lenticular sheet, a plurality of long lenticular lenses having a semicircular cross-sectional shape perpendicular to the length direction may be arranged on a support, or a hemispherical lenticular lens may be used. In addition, a plurality may be two-dimensionally arranged at regular intervals or randomly on the support.
Among these, a support body that regularly uses an aspheric surface such as a prism sheet, a pyramid sheet, and an inverted pyramid sheet in which a plurality of long prism lenses are arranged has a high brightness increase rate in the front direction, and is more preferable. It is mentioned in.

-Uneven portion-
The period of the concavo-convex shape of the concavo-convex part is preferably 1 to 150 μm, and more preferably 5 to 100 μm. When the period (pitch) of the concavo-convex shape exceeds 150 μm, when used for a display, the fine concavo-convex shape is likely to be visually recognized, and a glare may occur. If the period (pitch) is less than 1 μm, it may be difficult to arrange the irregular shape with a regular period, and as is clear from Equation 1 described later, the light flux density inside the optical sheet Since the portion where the thickness is lowered is also reduced, a higher resolution is required for the photosensitive layer for forming the optical adjustment portion, which may make it difficult to produce an optical sheet. Furthermore, since the thickness of the optical sheet is also reduced at the same time, it is difficult to handle, and the production of the optical sheet may be more difficult.
The regularity of the period (pitch) of the concavo-convex shape is not particularly limited and can be appropriately selected according to the purpose. However, when there is no regularity, the portion where the light flux density inside the support is low Therefore, it is difficult to select the thickness of the support on which the photosensitive layer is formed, and it is preferable that there is a certain regularity.
When the period (pitch) of the uneven shape is not a constant value, the change in the period is preferably within 10 times, and more preferably within 4 times. When the period change exceeds 10 times, the efficiency of increasing the luminance in the front direction may be extremely reduced.
Moreover, as a height of the said uneven | corrugated | grooved part, 1-100 micrometers is preferable and 5-50 micrometers is more preferable. If the height of the concavo-convex portion is less than 1 μm, it may be difficult to develop a high light-collecting property. If the concavo-convex portion exceeds 100 μm, the mechanical strength of the concavo-convex portion decreases, scratches, etc. Defects may easily occur, or unevenness may be easily recognized and a glare may occur.

[Prism sheet]
Hereinafter, the prism sheet will be described in detail.
When the support on which the uneven portions are formed is a prism sheet, the shape of the prism (when the prism lens is a stripe shape, a cross-sectional shape with respect to the length direction) is preferably an isosceles triangle, and the apex angle is 60 to 120 ° is preferable, and 80 to 100 ° is more preferable. If the apex angle is less than 60 ° or exceeds 120 °, the light collecting effect may be reduced, and the luminance in the front direction may be reduced.

The material for the concavo-convex portion (prism structure) is not particularly limited, but a material having a high refractive index is preferable from the viewpoint of improving the front luminance. Examples of such a resin include an aromatic compound such as a benzene ring and a naphthalene ring, and an organic compound having a high halogen and sulfur content such as Br and Cl.
When the resin is used as a UV curable resin, it contains the structure as described above, and is further used for irradiation with a reactive group-containing compound such as a (meth) acryloyl group, a vinyl group, and an epoxy group, and radiation such as ultraviolet rays. And a compound that can react with the reactive group-containing compound and a compound that generates an active species such as a radical or a cation. In particular, in terms of the speed of curing, a combination of a reactive group-containing compound (monomer) containing an unsaturated group such as a (meth) acryloyl group or a vinyl group and a photo radical polymerization initiator that generates a radical by light is preferable. .

Examples of the reactive group-containing compound include radicals and cations capable of reacting a reactive group-containing compound such as a (meth) acryloyl group, a vinyl group, and an epoxy group with radiation such as ultraviolet rays. Those containing a compound that generates the active species can be used.
In particular, from the viewpoint of curing speed, a combination of a reactive group-containing compound (monomer) containing an unsaturated group such as a (meth) acryloyl group or a vinyl group and a photo radical polymerization initiator that generates a radical by light is preferable. Among them, (meth) acryloyl group-containing compounds such as (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate are preferable. As the (meth) acryloyl group-containing compound, a compound containing one or more (meth) acryloyl groups can be used. Moreover, the reactive group containing compound (monomer) containing unsaturated groups, such as said acryloyl group and a vinyl group, may be used independently or may be used in mixture of multiple types as needed.

  As such (meth) acryloyl group-containing compounds, for example, monoborn monomers containing only one (meth) acryloyl group-containing compound are isobornyl (meth) acrylate, bornyl (meth) acrylate, tricyclodecanyl ( (Meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, acryloylmorpholine, 2-hydroxyethyl ( (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, iso Lopyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate , Heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate , Dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate Butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypolyethylene glycol (meta ) Acrylate and methoxypolypropylene glycol (meth) acrylate.

Furthermore, as monofunctional monomers having an aromatic ring, phenoxyethyl (meth) acrylate, phenoxy-2-methylethyl (meth) acrylate, phenoxyethoxyethyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate, 2 -(Meth) acrylate of p-cumylphenol reacted with phenylphenoxyethyl (meth) acrylate, 4-phenylphenoxyethyl (meth) acrylate, 3- (2-phenylphenyl) -2-hydroxypropyl (meth) acrylate, ethylene oxide ) Acrylate, 2-bromophenoxyethyl (meth) acrylate, 4-bromophenoxyethyl (meth) acrylate, 2,4-dibromophenoxyethyl (meth) acrylate, 2,6-dibromophenoxyethyl (meth) ) Acrylate, 2,4,6-bromophenyl (meth) acrylate, 2,4,6-tribromophenoxyethyl (meth) acrylate.
Examples of such commercially available monofunctional monomers having an aromatic ring include Aronix M113, M110, M101, M102, M5700, TO-1317 (above, manufactured by Toagosei Co., Ltd.), Biscote # 192, # 193, # 220, 3BM (above, manufactured by Osaka Organic Chemical Industry Co., Ltd.), NK ester AMP-10G, AMP-20G (above, manufactured by Shin-Nakamura Chemical Co., Ltd.), light acrylate PO-A, P-200A, epoxy ester M-600A, light ester PO (manufactured by Kyoeisha Chemical Co., Ltd.), New Frontier PHE, CEA, PHE-2, BR-30, BR-31, BR-31M, BR-32 (above, Daiichi Kogyo Seiyaku) Etc.).

  Examples of unsaturated monomers having two (meth) acryloyl groups in the molecule include alkyl diols such as 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and 1,9-nonanediol diacrylate. Examples include polyalkylene glycol diacrylates such as diacrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol diacrylate, and tripropylene glycol diacrylate, neopentyl glycol di (meth) acrylate, and tricyclodecane methanol diacrylate.

Examples of unsaturated monomers having a bisphenol skeleton include ethylene oxide-added bisphenol A (meth) acrylate, ethylene oxide-added tetrabromobisphenol A (meth) acrylate, propylene oxide-added bisphenol A (meth) acrylate, propylene oxide-added tetra Bromobisphenol A (meth) acrylic acid ester, bisphenol A epoxy (meth) acrylate obtained by epoxy ring-opening reaction of bisphenol A diglycidyl ether and (meth) acrylic acid, tetrabromobisphenol A diglycidyl ether and (meth) acrylic Tetrabromobisphenol A epoxy (meth) acrylate, bisphenol F diglycidyl ether and (meth) obtained by epoxy ring-opening reaction with acid Bisphenol F epoxy (meth) acrylate obtained by epoxy ring-opening reaction with crylic acid, tetrabromobisphenol F epoxy (meth) acrylate obtained by epoxy ring-opening reaction of tetrabromobisphenol F diglycidyl ether and (meth) acrylic acid Etc.
Commercially available unsaturated monomers having such a structure include Biscote # 700, # 540 (above, manufactured by Osaka Organic Chemical Industry Co., Ltd.), Aronix M-208, M-210 (above, Toagosei Co., Ltd.) Manufactured), NK ester BPE-100, BPE-200, BPE-500, A-BPE-4 (above, manufactured by Shin-Nakamura Chemical Co., Ltd.), light ester BP-4EA, BP-4PA, epoxy ester 3002M, 3002A, 3000M, 3000A (above, manufactured by Kyoeisha Chemical Co., Ltd.), KAYARAD R-551, R-712 (above, manufactured by Nippon Kayaku Co., Ltd.), BPE-4, BPE-10, BR-42M (above, first Manufactured by Kogyo Seiyaku Co., Ltd.), Lipoxy VR-77, VR-60, VR-90, SP-1506, SP-1506, SP-1507, SP-1509, SP- 1563 (manufactured by Showa High Polymer Co., Ltd.), Neopole V779, Neopole V779MA (manufactured by Nippon Yupica Co., Ltd.) and the like.

  Furthermore, as the trifunctional or higher functional (meth) acrylate unsaturated monomer, a trihydric or higher polyhydric alcohol (meth) acrylate such as trimethylolpropane litho (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane Examples include trioxyethyl (meth) acrylate, tris (2-acryloyloxyethyl) isocyanurate, and commercially available products include Aronics M305, M309, M310, M315, M320, M350, M360, M408 (above, Toagosei ( Co., Ltd., Biscoat # 295, # 300, # 360, GPT, 3PA, # 400 (Osaka Organic Chemical Co., Ltd.), NK Ester TMPT, A-TMPT, A-TMM-3, A-TMM -3L, A-TMMT (Shin Nakamura Gaku Co., Ltd.), light acrylate TMP-A, TMP-6EO-3A, PE-3A, PE-4A, DPE-6A (above, manufactured by Kyoeisha Chemical Co., Ltd., KAYARAD PET-30, GPO-303, TMPTA) , TPA-320, DPHA, D-310, DPCA-20, DPCA-60 (manufactured by Nippon Kayaku Co., Ltd.) and the like.

  In addition, a urethane (meth) acrylate oligomer may be blended. Examples of urethane (meth) acrylates include polyether polyols such as polyethylene glycol and polytetramethyl glycol; succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, tetrahydro (anhydrous) phthalic acid, hexahydro (anhydrous) phthalic acid Obtained by reaction of a dibasic acid such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, etc. Polyester polyols; Poly ε-caprol kuton modified polyols; Polymethyl valerol kuton modified polyols; Ethylene glycol, propylene glycol, 1,4-butanediol Alkyl polyols such as 1,6-hexanediol and neopentyl glycol; bisphenol A skeleton alkylene oxide modified polyols such as ethylene oxide-added bisphenol A and propylene oxide-added bisphenol A; bisphenol F skeletons such as ethylene oxide-added bisphenol F and propylene oxide-added bisphenol F Alkylene oxide-modified polyols or mixtures thereof and organic polyisocyanates such as tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate Manufactured from hydroxy group-containing (meth) acrylates And urethane (meth) acrylate oligomers. A urethane (meth) acrylate oligomer is preferable for maintaining the viscosity of the curable composition of the present invention moderately.

  As a commercially available monomer of these urethane (meth) acrylates, for example, Aronix M120, M-150, M-156, M-215, M-220, M-225, M-240, M-245, M-270 ( As mentioned above, manufactured by Toagosei Co., Ltd.), AIB, TBA, LA, LTA, STA, Viscoat # 155, IBXA, Viscoat # 158, # 190, # 150, # 320, HEA, HPA, Viscoat # 2000, # 2100, DMA, biscort # 195, # 230, # 260, # 215, # 335HP, # 310HP, # 310HG, # 312 (above, manufactured by Osaka Organic Chemical Industry Co., Ltd.), Light Acrylate IAA, LA, SA BO-A, EC-A, MTG-A, DMP-A, THF-A, IB-XA, HOA, HOP-A, HOA-MP , HOA-MPE, light acrylate 3EG-A, 4EG-A, 9EG-A, NP-A, 1,6HX-A, DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), KAYARADTC-110S, HDDA, NPGDA , TPGDA, PEG400DA, MANDA, HX-220, HX-620 (manufactured by Nippon Kayaku Co., Ltd.), FA-511A, 512A, 513A (manufactured by Hitachi Chemical Co., Ltd.), VP (manufactured by BASF), ACMO, DMAA, DMAPAA (manufactured by Kojin Co., Ltd.) and the like.

  The urethane (meth) acrylate oligomer is obtained as a reaction product of (a) hydroxy group-containing (meth) acrylate, (b) organic polyisocyanate and (c) polyol, but (a) hydroxy group-containing (meth). A reaction product obtained by reacting an acrylate with (b) an organic polyisocyanate and then (c) a polyol is preferable.

  The above unsaturated monomers may be used alone, or a plurality of types may be mixed as necessary.

  Examples of the photo radical polymerization initiator include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole. 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4-isopropylphenyl)- 2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthio Xanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, Examples thereof include bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, ethyl-2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, and the like.

  Examples of commercially available radical photopolymerization initiators include Irgacure 114, 369, 651, 500, 119, 907, 714, 2959, CGI 1700, CGI 1750, CGI 11150, CG 24-61, Darocurl 116, 1173 (above, Ciba Specialty Chemicals ( Co., Ltd.), Lucirin LR1728, 1193X (above BASF), Ubekrill P36 (UCB), KIP150 (Lamberti) and the like. Among these, Lucirin LR1193X is preferable from the viewpoint of being liquid and easily dissolved and having high sensitivity.

  The radical photopolymerization initiator is preferably blended in the total composition in an amount of 0.01 to 10% by weight, particularly 0.5 to 7% by weight. The upper limit of the blending amount is preferably in this range from the viewpoints of the curing characteristics of the composition, the mechanical properties and optical characteristics of the cured product, handling, and the like, and the lower limit of the blending amount is preferably in the range of preventing a decrease in the curing rate.

  The composition of the present invention may further contain a photosensitizer. Examples of the photosensitizer include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, 4-dimethyl Examples thereof include methyl aminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate and the like, and examples of commercially available products include Ubekryl P102, 103, 104, 105 (manufactured by UCB). .

  Furthermore, in addition to the above components, various additives as necessary include, for example, antioxidants, ultraviolet absorbers, light stabilizers, silane coupling agents, coating surface improvers, thermal polymerization inhibitors, leveling agents, surfactants. Colorants, storage stabilizers, plasticizers, lubricants, solvents, fillers, anti-aging agents, wettability improvers, mold release agents, and the like can be blended as necessary.

  Here, as the antioxidant, for example, Irganox 1010, 1035, 1076, 1222 (manufactured by Ciba Specialty Chemicals Co., Ltd.), Antigen P, 3C, FR, GA-10 (manufactured by Sumitomo Chemical Co., Ltd.). Examples of the ultraviolet absorber include Tinuvin P, 234, 320, 326, 327, 328, 329, 213 (manufactured by Ciba Specialty Chemicals Co., Ltd.), Seesorb 102, 103, 110, 501; 202, 712, 704 (above, manufactured by Sipro Kasei Co., Ltd.) and the like. Examples of the light stabilizer include Tinuvin 292, 144, 622LD (above, manufactured by Ciba Specialty Chemicals Co., Ltd.), Sanol LS770 ( Sankyo Co., Ltd.), Sumisorb TM-061 ( As a silane coupling agent, for example, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and a commercially available product. SH6062, 6030 (above, manufactured by Toray Dow Corning Silicone Co., Ltd.), KBE903, 603, 403 (above, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. Examples include silicone additives such as polyether and nonionic fluorosurfactants, and commercially available silicone additives include DC-57, DC-190 (above, manufactured by Dow Corning), SH-28PA, SH- 29PA, SH-30PA, SH-190 (above, Toray Dow Corning Silicone KF351, KF352, KF353, KF354 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), L-700, L-7002, L-7500, FK-024-90 (above, Nihon Unicar Co., Ltd.) And non-ionic fluorosurfactants commercially available as FC-430, FC-171 (above 3M), MegaFuck F-176, F-177, R-08 (above Dainippon Ink, Inc.) And a release agent such as Prisurf A208F (Daiichi Kogyo Seiyaku Co., Ltd.).

  The organic solvent for adjusting the viscosity of the resin liquid of the present invention may be any organic solvent that can be mixed without unevenness such as precipitates, phase separation, and cloudiness when mixed with the above resin liquid. For example, acetone, methyl ethyl ketone, Examples include methyl isobutyl ketone, ethanol, propanol, butanol, 2-methoxyethanol, cyclohexanol, cyclohexane, cyclohexanone, toluene and the like. May be. When an organic solvent is added, it is necessary to dry and evaporate the organic solvent during the product manufacturing process. However, if a large amount of residual solvent remains in the product, the mechanical properties of the product will deteriorate. There is also a concern that the organic solvent evaporates and diffuses during use as a product, causing bad odor and adverse health effects. For this reason, organic solvents having a high boiling point are not preferable because the amount of residual solvent increases. However, if the boiling point is too low, it will evaporate violently, resulting in rough surface, condensation water adhering to the surface of the composition due to the heat of vaporization during drying, resulting in surface defects and vapor concentration. It becomes higher and the risk of ignition etc. increases. Therefore, the boiling point of the organic solvent is preferably 50 ° C. or more and 150 ° C. or less, more preferably 70 ° C. to 120 ° C. Methyl ethyl ketone (bp. 79.6 ° C.), 1-propanol (bp. 97.2 ° C.) and the like are preferable as the organic solvent from the viewpoint of the solubility of the material and the boiling point.

  The amount of the organic solvent added to the resin solution of the present invention depends on the type of the solvent and the viscosity of the resin solution before the addition of the solvent. It is between 40% by weight, preferably 15% to 30% by weight. If the amount is too small, the effect of reducing the viscosity and the effect of increasing the coating amount are small, and the coating property is not sufficiently improved. However, when the amount is too much diluted, the viscosity is too low and the liquid flows on the sheet-like body to cause unevenness, or the liquid turns around the back surface of the sheet-like body. In addition, the product cannot be sufficiently dried in the drying process, and a large amount of organic solvent remains in the product, resulting in deterioration of product function, volatilization during product use, generating odors, and adverse health effects. Concerns arise.

The resin liquid of the present invention can be produced by mixing the above-mentioned components by a conventional method, and can be produced by heating and dissolving as necessary.
The viscosity of the resin liquid of the present invention thus prepared is usually 10 to 50,000 mPa · s / 25 ° C. When supplying a resin liquid to a substrate or embossing roll, if the viscosity is too high, it will be difficult to supply the composition uniformly, and when manufacturing a lens, uneven coating, undulation, and mixing of bubbles may occur. Therefore, it becomes difficult to obtain the target lens thickness, and the lens performance cannot be fully exhibited. In particular, this tendency becomes remarkable when the line speed is increased. Accordingly, in this case, the liquid viscosity is preferably low, 10 to 100 mPa · s, and more preferably 10 to 50 mPa · s. Such a low viscosity can be adjusted by adding an appropriate amount of the organic solvent. It is also possible to adjust the viscosity by setting the heat retention of the coating solution. On the other hand, if the viscosity after evaporation of the solvent is too low, it may be difficult to control the lens thickness when embossing the mold, and a uniform lens with a certain thickness may not be formed. The preferred viscosity is 100 to 3,000 mPa · s. It is. When an organic solvent is mixed, a low viscosity is provided when the resin liquid is supplied by providing a process for evaporating the organic solvent by heat drying, etc., between the process of supplying the resin liquid and embossing with the embossing roll. Thus, when the embossing roll is used for embossing, the embossing roll can be uniformly embossed with a resin liquid obtained by drying the organic solvent and increasing the viscosity.

  Here, it is particularly preferable that the cured product obtained by curing the resin liquid of the present invention has the following physical properties. First, the refractive index at 25 ° C. of the cured product is preferably 1.55 or more, and more preferably 1.56 or more. When the refractive index is less than 1.55, when an optical sheet is formed using this composition, there may be a case where sufficient front luminance cannot be ensured.

  Second, the softening point of the cured product is preferably 40 ° C or higher, particularly 50 ° C or higher. When the softening point is less than 40 ° C., the heat resistance may not be sufficient.

Furthermore, a material having a high refractive index by including an inorganic fine particle material having a high refractive index can also be used. Examples of such inorganic high refractive materials include Si (refractive index 3.5), TiO ₂ (refractive index 2.2 to 2.7), CeO ₂ (refractive index 2.2), and ZrO ₂ (refractive index 2.1). ), In ₂ O ₃ (refractive index 2.0), La ₂ O ₃ (refractive index 1.95), SnO ₂ (refractive index 1.9), Y ₂ O ₃ (refractive index 1.82), Sb ₂ O ₅ (refractive index of 2.09 to 2.29), and the like.
A smaller particle diameter of the high refractive index inorganic fine particles is preferable because the transparency of the resin is increased. Specifically, 100 nm or less is preferable, 50 nm or less is more preferable, and 20 nm or less is still more preferable.
The high refractive index inorganic fine particles can be used by mixing with ordinary UV curable resins. For this reason, a UV curable resin having a higher refractive index can be obtained by mixing with the UV curable resin having a high refractive index as described above.
The prism sheet is a method of pressing a metal saw-tooth prism sheet master roll while a thermoplastic sheet of polycarbonate or the like is in a molten state, and also has a serrated shape on one side with a thermoplastic resin. It can also be created by a method of extruding into the master.

[Diffusion sheet]
A case where the support on which the uneven portion is formed is a diffusion sheet will be described.
The method for imparting diffusibility to the diffusion sheet is not particularly limited, and may contain diffusing particles, may be kneaded with resins having different refractive indexes, or may contain air beads or hollow beads. Good. Further, it is possible to impart a diffusing effect in a surface shape by roughening the surface roughness, such as attaching beads to the light diffusing surface, roughing by blasting, impregnating a substance that dissolves easily, and dissolving after forming.
In more detail, the following diffusion sheet can also be used.
The diffusion sheet is formed by applying a coating liquid composed of a resin, a volatile liquid, and particles onto a support and drying.
Examples of the components of the coating liquid include resins, volatile liquids, particles, and other components as necessary.
There is no restriction | limiting in particular as said resin, Although it can select suitably according to the objective, An acrylic resin, a styrene-butadiene resin, etc. are mentioned.
Examples of the volatile liquid include methyl ethyl ketone (MEK), cyclohexanone, toluene, and water.
Examples of the shape of the particles include a spherical shape, an elliptical spherical shape, and a slanted ball shape.
The average particle diameter may be larger than the average thickness of the coating layer after drying, and is preferably 0.5 to 50 μm.
The average particle diameter of the particles can be measured, for example, by a measuring device using a dynamic light scattering method, a laser diffraction method, or the like.
There is no restriction | limiting in particular as said particle | grain, According to the objective, it can select suitably, For example, an organic particle, an inorganic particle, etc. are mentioned.
There is no restriction | limiting in particular as said organic particle, According to the objective, it can select suitably, For example, a polymethylmethacrylate resin particle, a melamine resin particle, a polystyrene resin particle, a silicone resin particle etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
As said organic particle, what has a crosslinked structure is preferable.
As the organic particles having a crosslinked structure, acrylic resin particles having a crosslinked structure are preferable.

There is no restriction | limiting in particular as said inorganic particle, According to the objective, it can select suitably, For example, a talc, a calcium carbonate, silicone, an alumina etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
As addition amount of the said particle | grain, 1-1000 mass parts is preferable with respect to 100 mass parts of said resins, and 25-400 mass parts is more preferable. When the addition amount is less than 1 part by mass, the function as a light diffusing agent may not be achieved, and when it exceeds 1,000 parts by mass, the particles may be difficult to disperse.
The value of the ratio between the refractive index of the resin and the refractive index of the particles is not particularly limited and may be appropriately adjusted according to the purpose. For example, the D (n ²⁵ ) line measured at 25 ° C. The refractive index is preferably 0.9 to 1.1, more preferably 0.95 to 1.05.
If the ratio of the refractive index of the resin and the refractive index of the particles is less than 0.9 or exceeds 1.1, the reflected light component at the particle / resin interface increases and the light transmittance decreases. There are things to do.

There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, particle | grain sedimentation inhibitor, a fluorochemical surfactant, a scattering agent, a thickener, a cationic surfactant, an anion interface An activator, a curing agent, a crosslinking agent, a photopolymerization initiator, a monomer, and the like can be given.
Examples of the particle settling inhibitor include fatty acid amide, polyethylene oxide, metal soaps, organic bentonite, hydrogenated castor oil wax, and the like. Among these, fatty acid amides and polyethylene oxide are more preferable. These may be used alone or in combination of two or more.
Since the scattering agent functions as a light diffusing agent as in the case of the above-described particles, the light diffusibility can be further improved.
There is no restriction | limiting in particular as an average particle diameter of the said scattering agent, According to the objective, it can select suitably, For example, it is preferable that it is 1-5 micrometers.
There is no restriction | limiting in particular in the average particle diameter of the said scattering agent, For example, it can measure with the measuring apparatus which used the dynamic light scattering method, the laser diffraction method, etc.
The material for the scattering agent is not particularly limited, and examples thereof include silica, calcium carbonate, alumina, and zirconia.
There is no restriction | limiting in particular as the addition amount in the said coating liquid of the said scattering agent, Although it can select suitably according to the objective, For example, 1-20 mass parts is preferable with respect to the said coating liquid whole quantity.
There is no restriction | limiting in particular as said thickener, According to the objective, it can select suitably, For example, an acrylamide amine salt etc. are mentioned.
The addition amount of the thickener is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin.
There is no restriction | limiting in particular as said fluorine-type surfactant, According to the objective, it can select suitably, For example, a fluorine-type anionic surfactant, a fluorine-type amphoteric surfactant, etc. are mentioned.
As addition amount of the said fluorosurfactant, 0.001-0.1 mass part is preferable with respect to 100 mass parts of said resin.

The surface tension of the coating solution is preferably 40 N / m or less, and more preferably 30 N / m or less. If the surface tension exceeds 40 N / m, the surface state of the coating layer may deteriorate.
The surface tension of the coating solution can be measured by, for example, an automatic surface tension meter (CBVP-A3, manufactured by Kyowa Interface Science Co., Ltd.).
There is no restriction | limiting in particular as a viscosity of the said coating liquid, Although it can select suitably according to the objective, 10-200 mPa * s is preferable at 25 degreeC, and 5-150 mPa * s is more preferable. When the viscosity is less than 10 mPa · s, it may be difficult to maintain the particle sedimentation property, and when it exceeds 200 mPa · s, the liquid feeding property, the coating property, the surface state, and the like may be deteriorated.
The viscosity of the coating solution can be measured by, for example, an E-type viscometer (ELD type) manufactured by Tokyo Keiki Co., Ltd.
There is no restriction | limiting in particular as a density | concentration of solid content of the said coating liquid, Although it can select suitably according to the objective, 10-40 mass parts is preferable with respect to 100 mass parts of the whole quantity of the said coating liquid, 20-20. 30 parts by mass is more preferable.

<Optical adjustment unit>
The optical adjusting unit is provided inside or on the surface of the support and has optical properties different from those of the support.
The optical adjustment portion of the optical sheet of the present invention is a normal direction of a second surface located on the opposite side of the first surface from the first surface side where the uneven portion of the support is formed. Is formed on at least a part of the non-passing portion of the light in the support. The light non-passing portion means a portion where the light flux density is essentially reduced except for some light or stray light entering by Fresnel reflection, and more specifically, the light flux density inside the optical sheet is the highest. It refers to the portion where the light flux density is less than 50% compared to the higher portion.
As for the light non-passing portion, as shown in FIG. 4, the case where the optical sheet is a prism sheet in which a plurality of long prism lenses having, for example, an isosceles triangular shape are arranged in parallel will be described below. .
As shown in FIG. 4, with respect to the optical sheet 1, from the first surface 3 side having the concavo-convex portion 5, in the normal direction of the second surface 4 located on the opposite side to the first surface 3. On the other hand, when the parallel light hν is incident, the light non-passing portion inside the optical sheet 1, that is, the inside of the support 2 becomes a shaded region (non-passing portion 6) in FIG. 4.
The non-passing portion 6 is a quadrangular pyramid shape with a rhombus section having a height Y and a width X
θ1: Prism apex angle L: Prism base length (pitch)
n1: Refractive index of the prism formed product (uneven portion 5) n2: Refractive index of the support 2 (n1 = n2 in the case of the same material by injection molding)
θ2: An exit angle from the air layer to the inside of the prism (uneven portion 5) when the parallel light hν is incident on the normal direction of the second surface 4 θ3: From the prism (uneven portion 5) to the support 2 Incidence angle θ4: When the emission angle from the prism (uneven portion 5) to the support 2 is used, it can be expressed by the following formula 1.

<Formula 1>
θ2 = arcsin ((sin (90− (θ1) / 2)) / (n1))
θ3 = 90− (θ1) / 2− (θ2)
θ4 = arcsin ((n1) · (sin (θ3)) / (n2))
Y = L · (1 / (2 · tan (θ4)) − 1 / (2 · tan ((θ1) / 2)))
X = Y · tan (θ4)

Therefore, from the above equation 1, when, for example, θ1 = 90 °, L = 50 μm, n1 = 1.59, n2 = 1.65, the height Y and the width X of the non-passing portion 6 are
Y = 52.4 μm
X = 16.9 μm can be calculated.

An optical adjustment unit having optical properties different from those of the support is formed on at least a part of the light non-passing portion. The optical adjustment unit may be formed in any part as long as it is at least a part of the non-passing part, and the entire non-passing part 6 having a diamond shape in FIG. 4 may be used as the optical adjustment part, as shown in FIG. As described above, the optical adjustment unit may be formed in a part of the non-passing part.
Specifically, as shown in FIG. 5A, an optical adjustment unit 7 which is a part of the non-passing part 6 and has a triangular cross section may be used. Further, as indicated by a two-dot chain line in FIG. 3A, a support 2B may be further laminated on the second surface 4 side of the support 2 on which the optical adjustment unit 7 is formed. Moreover, as shown to FIG. 5B, it is good also as a part of the non-passing part 6, Comprising: It is good also as the optical adjustment part 7 of a cross-section inverted triangle shape. Moreover, as shown in FIG. 5C, the optical adjustment unit 7 may be formed on the second surface 4 of the support 2 that is a part of the non-passing unit 6. Further, as shown in FIG. 5D, the optical adjusting unit 7 may be formed at a part of the non-passing part 6 and at the interface with the light passing part. Alternatively, as shown in FIG. 5E, the non-passing part The optical adjustment unit 7 may be formed in a part of the vicinity of the center of 6.
The optical adjustment unit in the present invention may be formed in any shape, size, and position as long as it is at least a part of the non-passing portion, and is not limited to the above specific example.

Examples of the optical property include light reflectivity, light diffusibility, and refractive index difference. By providing the optical adjustment unit with the light reflectivity and light diffusibility, or by providing a refractive index difference from the support, the optical adjustment unit has optical properties different from those of the support that does not absorb visible light. The optical adjustment unit can be easily formed.
Hereinafter, the optical adjustment unit having light reflectivity, light diffusibility, and refractive index difference will be described in detail.

[Optical adjustment unit having light reflectivity]
The optical sheet of the present invention has a light flux inside or on the surface of the support when light parallel to the normal direction of the second surface is incident from the first surface side where the uneven portion of the support is formed. It is preferable to have a region (optical adjustment part) having a light reflectivity different from that of the support in any part where the density is low.
For example, the optical adjustment unit having different light reflectivity may be formed of a regular reflective material such as a metal film, or may be formed of a white layer having diffuse reflectivity. Specifically, for example, as shown in FIG. 5C, a metal film having light reflectivity can be formed on the second surface 4 of the support 2 by vapor deposition of metal to form the optical adjustment unit 7.
Examples of the specular reflective metal film include gold, silver, aluminum, platinum, palladium, rubidium, rhodium, osmium, iridium, mercury, copper, iron, nickel, etc. Among these, from the viewpoint of high reflectivity A metal film formed by vapor-depositing silver, aluminum is more preferable. These metals may be used individually by 1 type, and may use the alloy which combined 2 or more types.
The thickness of the metal film is not particularly limited as long as it does not transmit light, and can be appropriately selected according to the purpose, but is preferably 100 nm or less.

Examples of the diffuse reflective white layer include Si (refractive index 3.5), TiO ₂ (refractive index 2.2 to 2.7), CeO ₂ (refractive index 2.2), and ZrO ₂ (refractive index 2.). 1), In ₂ O ₃ (refractive index 2.0), La ₂ O ₃ (refractive index 1.95), SnO ₂ (refractive index 1.9), Y ₂ O ₃ (refractive index 1.82), Sb ₂ O ₅ (refractive index: 2.09 to 2.29), layer containing inorganic particles such as zinc oxide, barium sulfate, calcium carbonate, silica, etc., layer containing particles having air inside such as hollow particles, porous A quality layer. Among these, titanium oxide is more preferable from the viewpoint of high refractive index and excellent reflectivity. An air-containing layer such as hollow particles is more preferable because it has a large refractive index difference from the binder and is excellent in reflectivity.
The particle size of the particles to be added is preferably 0.1 to 5 μm, and more preferably 0.2 to 1 μm. When the particle size of the particles to be added is less than 0.1 μm, the reflection performance may be deteriorated. When the particle size is more than 5 μm, it is difficult to ideally design the thickness of the white layer, or the particles are in the white layer. Overhanging can still make it difficult to design ideally.
The particles are used by being added in a binder (binder). The binder is not particularly limited and may be appropriately selected depending on the intended purpose. Specific examples include gelatin, polyvinyl alcohol. , Polyvinylpyrrolidone, methylcellulose, ethylcellulose, diacetylcellulose, triacetylcellulose, carboxylated cellulose and other modified celluloses, starches, polyethylene oxide, polypropylene oxide, acetal resin, nylon, phenolic resin, polyvinyl butyral, polyvinyl formal, vinyl acetate, Polyacrylic acid, polymethacrylic acid, and its esterified products such as acrylic resin, polystyrene, polyethylene, polypropylene, and other polyolefin resins, polyester resin, polyvinyl chloride Resin, ethylene vinyl acetate resins, vinyl chloride, SBR, and the like rubbers such as NBR.
There is no restriction | limiting in particular as addition amount of the said particle | grain, Although it can select suitably according to the objective, 1-90 volume% is preferable with respect to the volume of the said binder. When the addition amount is less than 1% by volume, the light reflectivity may be reduced, or the white layer may require an excessive thickness. When the addition amount exceeds 90% by volume, the durability of the white layer may be increased. May deteriorate, causing damage such as scratches.

  The light reflectance of the optical adjustment unit having light reflectivity is preferably 5 to 100%, and more preferably 50 to 100%. If the reflectivity is less than 5%, it may be difficult to exhibit an effect as an optical adjustment unit having light reflectivity.

[Optical adjustment unit having light diffusibility]
The optical sheet used in the present invention is formed on the inside or the surface of the support when light parallel to the normal direction of the second surface is incident from the first surface where the uneven portion of the support is formed. It is preferable to have a light diffusing region (optical adjustment part) in any part where the light flux density is lowered. When the optical adjusting unit having the light diffusibility exists, the light that has not been collected to the front can be used by changing the optical path.
The term “light scattering” here means that the ratio of reflected light / transmitted light is 1 or less.
The optical adjustment unit having light diffusibility includes, for example, enclosing low refractive index particles such as PMMA and silica in a relatively high refractive index binder such as styrene, or using a layer containing particles on the surface. It can be formed by forming fine irregularities.

(Optical adjustment unit having a refractive index difference)
The optical sheet used in the present invention is formed on the inside or the surface of the support when light parallel to the normal direction of the second surface is incident from the first surface where the uneven portion of the support is formed. It is preferable to have a region (optical adjustment unit) having a refractive index different from that of the support in any part where the light beam density is low. Due to the presence of the optical adjustment units having different refractive indexes, the optical path is changed by refracting light that could not be collected in the front and could not be used, and then returned to the incident surface side or collected in the front direction. The effect of light is expressed and preferable.

The refractive index is the refractive index of a portion (non-passing portion) where the light flux density inside the support is lowered when parallel light is incident from the first surface side to the normal direction of the second surface. Either a case where the refractive index is higher than that of the support or a case where the refractive index is lower than that of the support may be used, and can be appropriately selected depending on the optical design. In particular, in the case of the prism sheet, when parallel light is incident on the normal direction of the second surface, as shown in FIG. The triangular prism region on the prism side (uneven portion 5 side) has a high refractive index, or as shown in FIG. 5B, the triangular prism on the opposite side of the prism (uneven portion 5) from the center of the non-passing portion 6 It is preferable to make this area | region into a low refractive index. By having such a configuration, the light path of the so-called sidelobe light that has been totally reflected once at the prism inclined surface and emitted to the outside, is refracted more in the front direction (normal direction of the support), By making regular reflection twice on the slope of the prism, it becomes possible to return light to the back side, and the light collection efficiency is improved, which is more preferable.
The refractive index difference between the optical adjustment unit and the support is preferably 0.05 or more, and more preferably 0.1 or more. If the difference in refractive index is less than 0.05, the side lobe light may not be favorably refracted and the light collection efficiency may be lowered.

The support portion other than the optical adjustment portion having the refractive index difference is preferably formed using a photopolymerizable material. In the case of a photopolymerizable material, in the self-alignment method used in the optical sheet manufacturing method of the present invention described later, a portion where light flux density becomes low (light non-passing portion) does not overlap when parallel light is incident. The cavity can be formed by development. Then, by filling the cavity with a material having a refractive index different from that of the photopolymerizable material, an optical adjustment unit having a refractive index difference can be easily formed.
The photopolymerizable material is not particularly limited and may be appropriately selected depending on the purpose. It can be used by adding a photopolymerization initiator to a conventionally known radical polymerizable or cationic polymerizable monomer. .
As the polymerizable monomer, a monofunctional or polyfunctional monomer can be used alone or in combination, but the development can be stabilized by mixing a part of the polyfunctional monomer rather than the monofunctional monomer alone. From the viewpoint of making it more preferable.
The refractive index of the optical adjustment unit can be appropriately selected depending on the combination of the materials, but is preferably 1.45 to 1.65 from the viewpoint of ease of optical design.

As a method of making the optical adjusting unit have a higher refractive index than that of the support, it can be formed by pouring a high refractive index material into the cavity formed by the above development. Preferred examples of the high refractive index material include hot melt materials and photopolymerizable materials. These hot-melt materials or photopolymerizable materials are also preferable from the viewpoint of controlling fluidity and non-fluidity by temperature and light. Furthermore, these are also preferable from the viewpoint of facilitating pouring of the material into the cavity formed by the above development by imparting fluidity with an organic solvent. In this case, the used organic solvent is preferably dried by heating in the subsequent steps. In addition, these hot-melt materials and photopolymerizable materials contain organic compounds such as aromatic rings such as benzene rings and naphthalene rings, halides such as chlorine and bromine, or sulfur in the molecule. Is preferred.
It is also preferable to add inorganic fine particles in order to give a high refractive index to the optical adjustment unit.
Examples of the inorganic fine particles include Si (refractive index 3.5), TiO ₂ (refractive index 2.2 to 2.7), CeO ₂ (refractive index 2.2), ZrO ₂ (refractive index 2.1), In ₂ O ₃ (refractive index 2.0), La ₂ O ₃ (refractive index 1.95), SnO ₂ (refractive index 1.9), Y ₂ O ₃ (refractive index 1.82), Sb ₂ O ₅ ( Examples thereof include fine particles having a high refractive index such as a refractive index of 2.09 to 2.29). The particle size of these inorganic fine particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less. Furthermore, for the purpose of imparting light diffusibility and light reflectivity, particles larger than 100 nm can be added.

-Second support-
In the optical sheet of the present invention, a second support having essentially no visible light absorptivity and rigidity is laminated on the second surface side of the support on which the concave and convex portions are formed. It is preferable to do this. As the second support, a sheet-like one is preferably bonded.
Thus, by laminating the second support, it is more preferable from the viewpoint of improving the handleability of the optical sheet due to the appropriate rigidity.
There is no restriction | limiting in particular as a sheet | seat used for said 2nd support body, A conventionally well-known thing can be used, Specifically, a polyester-based sheet | seat, such as a polyethylene terephthalate and a polyethylene naphthalate, a TAC base sheet | seat etc. Is mentioned.
In addition, a sheet having essentially no visible light absorption and rigidity to be bonded may be a sheet having an uneven portion formed on the surface. As this uneven part, there is no particular limitation, and a prism sheet, a lenticular sheet, a fly-eye lens sheet, a pyramid sheet in which a square weight, etc. are two-dimensionally arranged, as used in the first support, and a square pyramid shape. Examples thereof include an inverted pyramid sheet in which concave portions are formed, a diffusion sheet in which irregularities are formed on the surface using spherical particles, and the like.
Thus, by bonding the second support having a concavo-convex portion formed on the surface, an effect of improving the luminance from the front of the optical sheet can be obtained, and the rigidity of the optical sheet can be further improved. From the viewpoint, it is more preferable.
A conventionally known method can be used for bonding the first support and the second support. For example, a method of applying and bonding an adhesive to the entire surface or a part of the surface of any one of the supports, a method of melting a part of any one of the supports and bonding the both supports, and the like. However, when the second support having a concavo-convex shape on the surface is bonded, it is preferable to bond the second support and the first support by providing an air layer, In order to provide this air layer, it is preferable to partially bond both supports.

  The second support may be formed by applying a coating solution containing a resin on the first support and drying it, or by applying a coating solution containing a photo-curable resin, and exposing to light. By doing so, the photocurable resin may be cured.

-Use-
The optical sheet of the present invention has an excellent light collecting function or light diffusing function, and an excellent luminance increase rate in a desired angle direction, particularly in the front direction. It can be suitably used for a display device. More specifically, the optical sheet may be preferably used by providing an uneven portion on the upper surface of a light guide plate of an edge light type surface light source device used as a backlight of the liquid crystal display device. it can.
Further, since the optical sheet is particularly excellent in the light condensing property to a required angle, in the above-described liquid crystal display device, it is possible to reduce emitted light to an unnecessary angle, that is, sidelobe light, As an optical sheet which can raise the brightness | luminance of a liquid crystal display device, it can be used more suitably.

(Optical sheet manufacturing method)
The method for producing the optical sheet of the present invention includes at least a photosensitive layer forming step, an exposure step, and an optical adjustment portion forming step, and if necessary, an uneven portion forming step, a developing step (liquid developing step), It comprises other steps such as a second support forming step.

<Concavity and convexity formation process>
The uneven portion forming step is a step of forming an uneven portion that collects or scatters light on at least the first surface of the support. When a commercially available prism sheet, lenticular lens sheet, fly-eye lens sheet, diffusion sheet, or the like is used, the uneven portion forming step can be omitted.
The uneven portion may be formed also on the second surface of the support.
There is no restriction | limiting in particular as a formation method of the said uneven | corrugated | grooved part, A conventionally well-known method can be used, For example, the metal mold | die which apply | coated the coating liquid containing a photocurable resin etc. on the support body, and formed unevenness | corrugation It can form by removing the metal mold | die after exposing and hardening the said photocurable resin in the state pressed on.
Further, the uneven portion has a method of pressing a metal serrated prism sheet master roll while a thermoplastic sheet of polycarbonate or the like is in a molten state, and also has a serrated shape on one side of the thermoplastic resin. It can also be formed by a method such as extrusion molding in a master.
Further, when the uneven portion is formed of particles or the like and has diffusibility, the uneven portion can be formed by the method described in the description of the diffusion sheet.
Moreover, as a manufacturing method of the support body in which the uneven | corrugated | grooved part was formed, you may use the manufacturing method of the following prism sheets.
The material for the support and the uneven portion and other details are as described in the description of the optical sheet.

-Manufacturing method of prism sheet-
An example of a method for manufacturing the prism sheet will be described with reference to the drawings. FIG. 3 is a conceptual diagram showing a configuration of a prism sheet manufacturing apparatus 80 to which the present invention is applied. The prism sheet manufacturing apparatus 80 includes a sheet-like material supply unit 81, a coating unit 82, a drying unit 89, an embossing roll 83 that is an uneven roll, a nip roll 84, a resin curing unit 85, and a peeling roll 86 , Protective film supply means 87, sheet winding means 88, and the like.

The sheet supply unit 81 that is a sheet-like body supply unit is configured to send out the sheet W that is a sheet-like body, and includes a delivery roll on which the sheet W is wound.
Generally, the width of the sheet W is 0.1 to 3 m, the length of the sheet W is 1,000 to 100,000 m, and the thickness of the sheet W is generally 1 to 300 μm. Is done. However, application of other sizes is not impeded.

  These sheets W may be previously subjected to corona discharge, plasma treatment, easy adhesion treatment, heat treatment, dust removal treatment and the like. The surface roughness Ra of the sheet W is preferably 3 to 10 nm at a cutoff value of 0.25 mm.

  The sheet W may be a sheet W provided with a base layer such as an adhesive layer in advance and dried and cured, or a sheet having another functional layer formed in advance on the back surface. Similarly, as the sheet W, not only a one-layer structure but also a structure having two or more layers can be adopted. Moreover, it is preferable that the sheet | seat W is a transparent body and anti-transparent body which can permeate | transmit light.

  The coating means 82 is a device that applies a radiation curable resin to the surface of the sheet W, and includes a supply source 82A for supplying the radiation curable resin, a supply device (pump) 82B, a coating head 82C, and the sheet W at the time of coating. Are supported by a support roll 82D and a pipe for supplying a radiation curable resin supply source 82A to the coating head 82C. In FIG. 3, an application head of an extrusion type die coater is used as the coating head.

  As the drying means 89, various known systems can be adopted as long as the coating liquid applied to the sheet W can be uniformly dried, such as a tunnel-shaped drying apparatus shown in FIG. . For example, a radiant heating method using a heater, a hot air circulation method, a far infrared method, a vacuum method, or the like can be employed.

  The embossing roll 83 is required to have an uneven pattern accuracy, mechanical strength, roundness, and the like that can transfer and form the unevenness of the roll surface on the surface of the sheet W. As such an embossing roll 83, a metal roll is preferable.

  A regular fine uneven pattern is formed on the outer peripheral surface of the embossing roll 83. Such a regular fine concavo-convex pattern is required to have a shape obtained by inverting the fine concavo-convex pattern on the surface of the prism sheet as a product.

  As the prism sheet, fine cones such as fly-eye lenses, cones, pyramids, etc., which are arranged in two dimensions, for example, lenticular lenses, prism lenses, fine projection patterns, etc., are arranged in the XY direction. A flat lens or the like laid on the surface is an object, and the regular fine uneven pattern on the outer peripheral surface of the embossing roll 83 is made to correspond to this.

  As a method for forming a regular fine concavo-convex pattern on the outer peripheral surface of the embossing roll 83, a method of cutting the surface of the embossing roll 83 with a diamond bit (single point), photo etching, electron beam drawing on the surface of the embossing roll 83, The method of forming irregularities directly by laser processing etc. can be adopted, and irregularities are formed on the surface of thin metal plate by photo etching, electron beam drawing, laser processing, stereolithography, etc. Can be wound around and fixed to the embossing roll 83. In addition, uneven surfaces are formed on the surface of materials that are easier to process than metal by photo-etching, electron beam drawing, laser processing, stereolithography, etc., and a reversal of this shape is formed by electroforming etc. to make a thin metal plate A method of forming an embossing roll 83 by forming a body and winding and fixing the plate-like body around the roll can also be adopted. In particular, when the inversion mold is formed by electroforming or the like, there is a feature that a plurality of plate-like bodies having the same shape can be obtained from one original (mother).

  It is preferable to perform a mold release process on the surface of the embossing roll 83. Thus, the shape of the fine concavo-convex pattern can be satisfactorily maintained by performing the mold release treatment on the surface of the embossing roll 83. As the mold release treatment, various known methods such as coating treatment with a fluororesin can be employed. The embossing roll 83 is preferably provided with driving means. The embossing roll 83 rotates counterclockwise (CCW) as shown in the arrow.

  The nip roll 84 is roll-formed while pressing the sheet W in a pair with the emboss roll 83, and is required to have predetermined mechanical strength, roundness, and the like. The longitudinal elastic modulus (Young's modulus) on the surface of the nip roll 84 is set to an appropriate value because roll forming is insufficient if it is too small, and if it is too large, it reacts sensitively to the inclusion of foreign matter such as dust and tends to cause defects. It is preferable. The nip roll 84 is preferably provided with a driving means. The nip roll 84 rotates in the clockwise direction (CW) as shown in the figure.

  In order to apply a predetermined pressing force between the embossing roll 83 and the nip roll 84, it is preferable to provide a pressing means on either the embossing roll 83 or the nip roll 84. Similarly, it is preferable to provide fine adjustment means on either the embossing roll 83 or the nip roll 84 so that the gap (clearance) or pressure between the embossing roll 83 and the nip roll 84 can be accurately controlled.

  The resin curing means 85 is a radiation irradiation means provided opposite to the embossing roll 83 on the downstream side of the nip roll 84. The resin curing means 85 transmits the sheet W through radiation irradiation and cures the resin layer. The resin curing means 85 can irradiate the radiation according to the curing characteristics of the resin, and can irradiate the amount of radiation according to the conveyance speed of the sheet W. Is preferred. As the resin curing means 85, for example, a columnar irradiation lamp having substantially the same length as the width of the sheet W can be adopted. Further, a plurality of the columnar irradiation lamps can be provided in parallel, and a reflector can be provided on the back surface of the columnar lamp.

  The peeling roll 86 is a pair of the embossing roll 83 and peels the sheet W from the embossing roll 83, and is required to have predetermined mechanical strength, roundness, and the like. The sheet W is peeled from the embossing roll 83 and wound around the peeling roll 86 while the sheet W wound on the peripheral surface of the embossing roll 83 is sandwiched between the rotating embossing roll 83 and the peeling roll 86 at the peeling portion. In order to ensure this operation, the peeling roll 86 is preferably provided with a driving means. The peeling roll 86 rotates in the clockwise direction (CW) as shown in the figure.

  In addition, when the temperature of resin etc. rises by hardening, the structure which provides a cooling means to the peeling roll 86 can also be employ | adopted in order to cool the sheet | seat W at the time of peeling, and to ensure peeling.

  Although not shown, a plurality of backup rolls are provided to face each other between the pressing location (9 o'clock position) of the embossing roll 83 and the peeling location (3 o'clock position). A configuration in which the curing process is performed while pressing the sheet W with the roll 83 can also be adopted.

  The sheet winding means 88 stores the peeled sheet W and includes a winding roll that winds the sheet W. In this sheet winding means 88, the protective film H supplied from the adjacent protective film supply means 87 is supplied to the surface of the sheet W, and is stored in the sheet winding means 88 in a state in which both films overlap. The

In the prism sheet manufacturing apparatus 80, a guide roll or the like that forms a conveyance path for the sheet W may be provided between the coating means 82 and the embossing roll 83, between the peeling roll 86 and the sheet winding means 88, or the like. In addition, a tension roll or the like can be provided as needed to absorb slack during conveyance of the sheet W.
As described above, it is possible to manufacture a prism sheet in which a lens array in which prism-shaped unit lenses are formed in a uniaxial direction is adjacently arranged on the entire surface.

<Photosensitive layer forming step>
The photosensitive layer forming step is a step of forming a photosensitive layer on a second surface located on the side opposite to the first surface of the support.
The method for forming the photosensitive layer is not particularly limited and may be appropriately selected according to the purpose.For example, by applying a coating solution for the photosensitive layer on the second surface of the support and drying, Can be formed.
The application can be performed using a known application means such as a spin coater, a roll coater, a bar coater, or a curtain coater.
As temperature in a drying process, 60-140 degreeC is preferable and 80-120 degreeC is more preferable. The drying time is preferably 10 seconds to 2 minutes, more preferably 10 seconds to 1 minute.

The photosensitive layer may be a positive photosensitive layer or a negative photosensitive layer.
When the positive photosensitive layer is an alkali developing type, the composition contains at least a binder having an acid value and quinonediazide. Examples of the binder include phenol novolac resins, polymers containing carboxylic acids such as polyacrylic acid, polymethacrylic acid, and polymaleic acid, and copolymers with monomers having unsaturated double bonds copolymerizable therewith. It is done. Among these, a phenol novolac resin is more preferable.
Examples of the solvent that dissolves the composition include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, propyl acetate, and butyl acetate, and alcohol solvents such as normal propanol, ethanol, and methanol. . Among these, ketone solvents such as methyl ethyl ketone are more preferable.
In addition to the above, a surfactant, a matting agent, a wax for imparting slipperiness, and the like can be appropriately used as the photosensitive layer.
Further, it is more preferable to add white fine particles for the purpose of imparting diffuse reflectivity because the number of steps can be reduced. As white fine particles, Si (refractive index 3.5), TiO ₂ (refractive index 2.2 to ₂ ). .7), CeO ₂ (refractive index 2.2), ZrO ₂ (refractive index 2.1), In ₂ O ₃ (refractive index 2.0), La ₂ O ₃ (refractive index 1.95), SnO _2. (Refractive index 1.9), Y ₂ O ₃ (refractive index 1.82), Sb ₂ O ₅ (refractive index 2.09 to 2.29), inorganic particles such as zinc oxide, barium sulfate, calcium carbonate, silica A layer containing particles, a layer containing particles having air inside, such as hollow particles, and a porous layer. Among these, titanium oxide is more preferable from the viewpoint of high refractive index and excellent reflectivity. An air-containing layer such as hollow particles is more preferable because it has a large refractive index difference from the binder and is excellent in reflectivity.
In addition, as the positive photosensitive layer, a photocurable photosensitive layer utilizing loss of adhesiveness due to photopolymerization can also be used. In this case, since the development with a liquid is not required, the process can be simplified, which is more preferable.
When the positive photosensitive layer is a photocurable photosensitive layer, the composition contains a binder, a polymerizable monomer, and a photopolymerization initiator. A binder is added for the purpose of controlling the tackiness of the uncured film, and known ones can be used. Among these, acrylic resins are preferable because of good compatibility with monomers. The polymerizable monomer is preferably one having an unsaturated double bond in the molecule as represented by an acrylic monomer. More specifically, a (meth) acryloyl group-containing compound, a monofunctional monomer having an aromatic ring, an unsaturated monomer having two (meth) acryloyl groups in the molecule, and a bisphenol skeleton as listed in the description of the prism sheet. Monomers such as unsaturated monomers having a trifunctional or higher-functional (meth) acrylate unsaturated monomer, urethane (meth) acrylate oligomer can be used as appropriate. In the case of using a monomer having an unsaturated double bond in the molecule, the atmosphere is replaced with an inert gas such as nitrogen during exposure, or an oxygen-blocking cover film is used for the purpose of preventing polymerization inhibition by oxygen. More preferably, it is used. A conventionally known material may be used for the oxygen-blocking cover film, but a material having low oxygen permeability is more preferable. Examples of the material having a high oxygen barrier property include films coated with polyvinyl alcohol, polyethylene terephthalate, and polypropylene. Further, a cationic polymerizable monomer typified by oxetane or the like can be used as the polymerizable monomer. Specifically, a compound having a molecular weight of 1,000 or less having a cyclic ether group such as an epoxy group, an oxetane group, an oxolane group, an acrylic or vinyl compound having a substituent in the side chain, a carbonate compound, a low molecular weight Monomers having a vinyl bond capable of cationic polymerization such as melamine compounds, vinyl ethers and vinyl carbazoles, styrene derivatives, alpha-methyl styrene derivatives, vinyl alcohol esters including vinyl alcohol and acrylic, methacrylic ester compounds, etc. Can be used together. Cationic polymerizable monomers are preferred because they are not affected by oxygen in the polymerization.
As the photopolymerization initiator, it is preferable to use a photoradical generator (photoradical polymerization initiator) as long as it is radically polymerizable. Specifically, radical photopolymerization initiators such as acetophenone as listed in the description of the prism sheet can be used.
When a cationic polymerizable monomer is used, it is preferable to use a photoacid generator typified by an onium salt as the photopolymerization initiator. Specifically, for example, onium salts, diazonium salts, quinonediazide compounds, organic halides, aromatic sulfonate compounds, bisulfone compounds, sulfonyl compounds, sulfonate compounds, sulfonium compounds, sulfamide compounds, iodonium compounds, sulfonyldiazomethane compounds, and the like A mixture of these can be used.

<Exposure process>
The exposure step is a step of exposing the photosensitive layer by entering light parallel to the normal direction of the second surface from the first surface side of the support.
When the positive photosensitive layer is an alkali development type, the exposed portion, that is, the light passage portion is soluble in the developer, and only the non-exposed portion, that is, the light non-passion portion of the photosensitive layer is supported by development. It remains on the body.
When the positive photosensitive layer is a photo-curing type, the exposed portion, that is, the light passage portion loses its adhesiveness due to the polymerization reaction, and the adhesion of the developer can be controlled, so that an image can be formed.
In the case of a negative photosensitive layer, only the exposed portion, that is, the light passage portion is cured, and the development removes the non-exposed portion, that is, the light non-passion portion of the photosensitive layer. Remains on top.
Although there is no restriction | limiting in particular as said exposure method, It is required that the light ray parallel to a sheet normal line direction can inject. Specific examples include a digital exposure machine such as a laser beam and an analog exposure machine that generates parallel light from a light source using a lens system.
There is no restriction | limiting in particular as said analog exposure, According to the objective, it can select suitably, For example, the method of exposing with a high pressure mercury lamp, a super-high pressure mercury lamp, a xenon lamp etc. is mentioned.
There is no restriction | limiting in particular as said digital exposure, According to the objective, it can select suitably, For example, relative scanning is performed, modulating light based on image data, using the spatial light modulation device arranged in two dimensions. Thus, a method of forming a two-dimensional image can be used.
Among these, when a laser beam is used, it is easy and preferable to irradiate parallel light.

<Optical adjustment part formation process>
The optical adjustment portion forming step is a step of forming an optical adjustment portion which is an unexposed portion of the photosensitive layer and has optical properties different from those of the support on the support.
When the positive photosensitive layer is of the alkali development type, only the non-exposed portion of the photosensitive layer remains on the support, and an optical adjustment portion is formed on the photosensitive layer portion of the non-exposed portion. Various methods can be used to form the light adjusting portion. Specifically, (1) a method of adhering powder toner using the adhesive property of the positive photosensitive layer, (2) A method in which a sheet-like toner layer is superimposed on the surface of a positive photosensitive layer, thermally laminated at an appropriate temperature, the toner sheet is peeled off, the toner layer is transferred to a portion of the positive photosensitive layer, and an optical adjustment unit is provided. (3) A method in which an optical adjustment member is previously contained in a positive photosensitive layer and an optical adjustment portion is formed simultaneously with alkali development. (4) An optical adjustment member is formed on the upper layer (opposite surface side of the support) of the positive photosensitive layer. There is a method in which a toner layer containing is coated to form a two-layer structure of a photosensitive layer and a color material layer, and an optical adjustment portion is formed simultaneously with development. In this case, the light of the exposure process can be used effectively, and the sensitivity is more preferable. As the optical adjusting member to be contained in the powder toner, the toner layer of the toner sheet, and the positive photosensitive layer, a white diffuse reflective member is preferable.
In the case where the positive photosensitive layer is a photo-curing type, the exposed portion, that is, the light passage portion loses its adhesiveness due to the polymerization reaction, and the adhesion of the developer can be controlled, and the adhesive remains unexposed. An optical adjustment part is formed in the part. As a method for forming the optical adjustment unit, (1) a method of adhering powder toner, (2) a sheet-like toner layer is superimposed on the surface of the positive photosensitive layer, and heat-laminated at an appropriate temperature, The method of peeling and providing an optical adjustment part can be mentioned. As the toner layer of the powder toner and toner sheet, a white member having diffuse reflectivity is preferable.
In the case of the negative photosensitive layer, the photosensitive layer in the non-exposed area is removed from the support. An optical adjustment portion is formed in the non-exposed portion where no photosensitive layer exists. As a method for forming the optical adjustment portion, (1) a method in which a metal reflective layer is vapor-deposited, and then the remaining portion of the negative photosensitive layer is peeled off together with the metal reflective layer using a strong acid or strong alkali stripping solution. (2) A method in which a resin having a different refractive index or a resin monomer is filled in a portion where the photosensitive layer in the non-exposed portion is removed from the support.

<Liquid development process>
The liquid developing step is a step of removing the exposed layer or the unexposed region of the photosensitive layer using a liquid. The liquid development step can be performed as part of the optical adjustment portion forming step or between the optical adjustment portion formation step after the exposure step.
There is no restriction | limiting in particular as the removal method of the said unhardened area | region, According to the objective, it can select suitably, For example, the method etc. which remove using a developing solution are mentioned.
There is no restriction | limiting in particular as said developing solution, Although it can select suitably according to the objective, For example, alkaline aqueous solution, an aqueous developing solution, an organic solvent etc. are mentioned, Among these, weakly alkaline aqueous solution is preferable. Examples of the basic component of the weak alkaline aqueous solution include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium phosphate, phosphorus Examples include potassium acid, sodium pyrophosphate, potassium pyrophosphate, and borax.

<Second support forming step>
The second support forming step is a step of forming at least one second support on the second surface side of the support (first support). The second support may be a single layer or a multilayer structure of two or more layers.
The method for forming the second support is not particularly limited and may be appropriately selected depending on the purpose. For example, the sheet-like second support is bonded to the first support with an adhesive or the like. May be attached. The second support may be formed by applying a coating solution containing a resin on the first support and drying it, or may be formed on the first support by a photocurable resin or the like. You may form by apply | coating the coating liquid containing this and exposing and hardening the said photocurable resin.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Preparation of support with irregularities>
A prism sheet was produced as follows as a support on which the uneven portions were formed.
[Adjustment of prism layer coating solution]
A prism layer coating solution having the following formulation was prepared.
The following composition was put into a mixing tank and stirred while heating to 50 ° C. to dissolve each component to prepare a coating solution. The refractive index of the cured prism layer was 1.59. The refractive index of the prism layer was measured with a prism coupler refractive index measuring machine (SPA4000 Sairon Technology Inc.) by forming the same liquid as a flat coating film.
・ Evekril 3700 (manufactured by Daicel UBC Co., Ltd.) 2.55 parts by mass NK ester BPE-200 (manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.85 parts by mass Aronix M-110 (Toagosei) 0.85 parts by mass, New Frontier BR-31 (Daiichi Kogyo Seiyaku Co., Ltd.), 4.25 parts by mass, methyl ethyl ketone, 2.89 parts by mass, Lucyrin TPO -L (manufactured by BASF Corporation) ... 0.17 parts by mass

[Preparation of prism sheet A]
The prism layer coating solution prepared above was applied to the first surface of a 25 μm thick transparent PET support that had been subjected to easy adhesion treatment on both sides so that the dry mass was 14 g / m ² , at 80 ° C. After drying for 1 minute, the prism layer was pressed against a metal mold (mold) in which the prism shape was engraved in a stripe shape with an apex angle of 90 ° and a pitch (base length) of 50 μm. In this pressed state, from the second surface side of the support made of PET, exposure is performed using a high-pressure mercury lamp at an exposure amount of 1,500 mJ / cm ² , the mold is peeled off, and the prism sheet A (uneven portion is removed). A formed support) was obtained.

[Preparation of prism sheet B]
The prism layer coating solution prepared above was applied to the first surface of a 5 μm thick transparent PET support that had been subjected to easy adhesion treatment on both sides so that the dry mass was 14 g / m ^2. After drying for 1 minute, the prism layer was pressed against a metal mold (mold) in which the prism shape was engraved in a stripe shape with an apex angle of 90 ° and a pitch (base length) of 50 μm. In this pressed state, exposure is performed from the second surface side of the PET support using a high-pressure mercury lamp at an exposure amount of 1,500 mJ / cm ² , the mold is peeled off, and the prism sheet B (uneven portion is removed). A formed support) was obtained.

<Preparation of coating solution for positive photosensitive layer>
A coating solution for positive photosensitive layer having the following formulation was prepared.
・ Phenol novolac resin (Sumitomo Durez KK, PR-50716, melting point: 76 ° C.) 2.5 parts by mass Phenol novolac resin (Sumitomo Durez KK, PR-51600B, melting point: 55 ° C.) -3.5 parts by mass-1,2-naphthoquinone (2) Diazide-4-sulfonic acid cumylphenol ester-2.0 parts by mass-Methyl ethyl ketone-40 parts by mass-Propylene glycol monomethyl ether acetate- 20 parts by mass / surfactant (Dainippon Ink Co., Ltd., MegaFuck F-176PF) ... 0.1 parts by mass

<Preparation of negative photosensitive layer coating solution (photocurable resin solution 1)>
A negative type photosensitive layer coating solution having the following formulation was prepared.
Benzyl methacrylate / methacrylic acid copolymer (molar ratio 73/27) ... 100 parts by massPentaerythritol tetraacrylate ... 80 parts by massLucirin TPO-L (manufactured by BASF Corporation) ... 1. 6 parts by mass, methyl ethyl ketone, 1,134 parts by mass, propylene glycol monomethyl ether acetate, 486 parts by mass, surfactant (manufactured by Dainippon Ink Co., Ltd., MegaFuck F-176PF), 0.2 parts by mass Part

<Preparation of photocurable resin liquid 2>
The photocurable resin liquid 2 for optical adjustment part formation was adjusted with the following prescription.
NK ester BPE-200 (made by Shin-Nakamura Chemical Co., Ltd.) 35.0 parts by mass Aronix M-5700 (produced by Toagosei Co., Ltd.) 15.0 parts by mass New Frontier BR-31 (Daiichi Kogyo Seiyaku Co., Ltd.) ... 50.0 parts by mass / Quin Titanic (Catalyst Chemical Industries, Ltd. 20% MIBK) ... 485.3 parts by mass / Lucirin TPO-L (BASF Corporation) ) Made ... 2.0 parts by mass

<Preparation of photocurable resin liquid 3>
The photocurable resin liquid 3 for optical adjustment part formation was adjusted with the following prescription.
-NK ester A-400 (made by Shin-Nakamura Chemical Co., Ltd.) ... 100.0 parts by mass-Lucirin TPO-L (made by BASF Corp.) ... 2.0 parts by mass

<Preparation of coating solution for white reflective layer>
The coating liquid for white reflective layer for optical adjustment part formation was adjusted with the following prescription.
[Composition of white pigment dispersion mother liquor]
・ Polyvinyl butyral (ESREC B BL-SH, manufactured by Sekisui Chemical Co., Ltd.) 2.7 parts by mass. Rutile-type titanium oxide (JR805, manufactured by Teika Co., Ltd., mass average particle size 0.29 μm). -35.0 parts by mass-Dispersing aid (Solsperse 20000, manufactured by Avicia Co., Ltd.) ... 0.35 parts by mass-n-propyl alcohol ... 62.0 parts by mass A white pigment dispersion mother liquor was prepared by dispersing using zirconia beads with a mill M50.

[Composition of white reflective layer coating solution]
-White pigment dispersion mother liquor prepared as above-1,200 parts by mass-Wax compound stearamide (Neutron 2, manufactured by Nippon Seika Co., Ltd.)-5.7 parts by weight behenamide ( Diamond BM, manufactured by Nippon Kasei Co., Ltd.) 5.7 parts by mass Lauric acid amide (Diamid Y, manufactured by Nippon Kasei Co., Ltd.) 5.7 parts by mass Palmitic acid amide (Diamindo KP, Japan) 5.7 parts by weight Erucamide (Diamid L-200, manufactured by Nippon Kasei Co., Ltd.) ... 5.7 parts by weight Oleamide (Diamid O-200, Japan) 5.7 parts by mass, rosin (KE-311, manufactured by Arakawa Chemical Co., Ltd.), component: resin acid 80 to 97%; resin acid component: abietic acid 30 to 40%, neoabietin 10-20% acid, dihydro 80.0 parts by mass / surfactant (Megafac F-780F, solid content 30%, manufactured by Dainippon Ink & Chemicals, Inc.) ... 16.0 parts by mass Parts · n-propyl alcohol ··· 1,600 parts by mass · methyl ethyl ketone · · · 580 parts by weight

<Preparation of alkali developer>
An alkali developer having the following composition was prepared.
・ Sodium carbonate: 59 parts by mass. Sodium bicarbonate: 32 parts by mass. Water: 720 parts by mass. Butyl cellosolve: 1 part by mass.

<Alkaline stripping solution>
An alkali stripping solution having the following composition was prepared.
-1N sodium hydroxide aqueous solution ... 1,000 parts by mass-Butyl cellosolve ... 1 part by mass

(Example 1)
<Preparation of white reflective sheet>
The white reflective layer coating solution prepared above was applied onto a PET support having a thickness of 25 μm so that the dry film thickness was 2 μm, and dried at 100 ° C. for 2 minutes to prepare a white reflective sheet.

<Production of optical sheet>
As shown in FIG. 6A, the positive photosensitive layer coating solution prepared above is dried on the flat second surface 4 side of the prism sheet A (support 2 on which the concavo-convex portion 5 is formed). The film was applied to a thickness of 0.5 μm and dried at 100 ° C. for 2 minutes to form a positive photosensitive layer 8 on the second surface 4 of the support 2.
Next, as shown in FIG. 6B, from the first surface 3 side on which the concavo-convex portion 5 of the support 2 is formed, using a parallel beam irradiator (mask alignment apparatus M-2L, manufactured by Mikasa Corporation). The positive photosensitive layer was exposed by irradiating with ultraviolet rays parallel to the normal direction of the flat second surface 4. A portion indicated by reference numeral 6 in FIG. 6B is a light non-passing portion (a portion having a low luminous flux density).
Next, using the alkaline developer prepared above, the exposed portion of the positive photosensitive layer is washed away, and as shown in FIG. 6C, the second surface 4 of the support 2 and the light non-passing portion 6 A support 2 partially having a positive photosensitive layer 8 was obtained.
The white reflective sheet 10 provided with the white reflective layer 9 prepared above is adhered to the second surface 4 of the support 2 having the positive photosensitive layer 8 partially formed on the positive photosensitive layer 8. The positive-type photosensitive layer 8 having the property is disposed so that the white reflective layer 9 is in contact with the second surface 4 and is thermally laminated by a laminating apparatus (speed: 0.5 m / min. Heating temperature: 80 ° C.). . Thereafter, the white reflective sheet 10 is peeled off from the support 2 to obtain the support 2 having the white reflective layer 9 transferred in a stripe shape to the formation part of the positive photosensitive layer 8. Sheet 1 was formed. The white reflective layer 9 was the optical adjustment unit 7, and the light reflectance was 75%.

<Production of display device with optical sheet>
The optical sheet (prism sheet) of Example 1 on which the optical adjustment unit 7 having partial light reflectivity was formed was placed on a liquid crystal display panel of a liquid crystal display device. The installation direction was set so that the first direction coincided with the substantially vertical direction of the erected liquid crystal display panel.
Using this liquid crystal display device, the optical sheet of Example 1 was evaluated as follows. The results are shown in Table 1.

<Evaluation of front brightness>
An optical sheet is laid on a flat light source (FLR3: Funatec Co., Ltd.), and the luminance is measured with a color luminance meter (BM-7: Topcon Co., Ltd.). Luminance evaluation was performed using the magnification of the front luminance when the optical sheet was laid when the front luminance of only the light source without the optical sheet was set to 1.
[Evaluation criteria]
◎: 1.9 or more ○: 1.8 or more, less than 1.9 Δ: 1.7 or more, less than 1.8 x: less than 1.7

<Evaluation of sidelobe effects>
The value of the current flowing through the cold-cathode tube was adjusted so that the front luminance (the light intensity received by the light receiver) in the optical sheet of Example 1 was 10,000 cd / m ² . Then, the front is set to 0 °, the light receiver is operated ± 90 °, the angle distribution of the emitted light emitted from the optical sheet 1 is measured, and the side is determined depending on whether or not a phenomenon in which the light intensity decreases once around ± 45 ° occurs. The effect of lobes was evaluated.
[Evaluation criteria]
◎: Phenomenon that the light intensity decreases once around ± 45 ° does not occur ○: Phenomenon that the light intensity decreases once around ± 45 ° occurs slightly ×: Phenomenon that the light intensity decreases once around ± 45 °

  In the optical sheet of Example 1, the front luminance was high, and as shown in FIG. 7, there was little emission of side lobe light, and therefore, there was no influence of side lobe, and it had characteristics suitable as a display material.

(Example 2)
<Production of optical sheet>
As shown in FIG. 8A, the negative photosensitive layer coating solution (photocuring) prepared on the flat second surface 4 side of the prism sheet A (the support 2 on which the concavo-convex portion 5 is formed) prepared as described above. The photosensitive resin solution 1) was applied so as to have a dry film thickness of 0.5 μm and dried at 100 ° C. for 2 minutes to form a negative photosensitive layer 11 on the second surface 4 of the support 2.
Next, as shown in FIG. 8B, from the first surface 3 side on which the concavo-convex portion 5 of the support 2 is formed, using a parallel beam irradiator (mask alignment apparatus M-2L, manufactured by Mikasa Corporation). The negative photosensitive layer was exposed by irradiating with ultraviolet rays parallel to the normal direction of the flat second surface 4. A portion indicated by reference numeral 6 in FIG. 8B is a light non-passing portion (a portion having a low luminous flux density), and the other negative photosensitive layer portion of the light passing portion is cured.
Next, using the alkali developer prepared above, the non-exposed portion of the negative photosensitive layer is washed away, and as shown in FIG. 6C, the support 2 having the negative photosensitive layer 11 partially in the light passage portion is formed. Obtained.
Subsequently, as shown in FIG. 8D, 100 nm of metal aluminum (aluminum vapor deposition layer 12) was vapor-deposited on the second surface 4 on which the negative photosensitive layer 11 was partially formed, and then the alkali peeling prepared above was performed. The negative photosensitive layer 11 was peeled off using a solution to obtain a support 2 having an aluminum vapor-deposited layer 12 formed in a stripe shape on the light non-passing portion 6 as shown in FIG. 8E. Two optical sheets 1 were formed. This aluminum vapor deposition layer 12 was the optical adjustment part 7, and the light reflectance was 90%.

<Production and Evaluation of Display Device with Optical Sheet>
The optical sheet (prism sheet) of Example 2 on which the optical adjustment unit 7 having partial light reflectivity is thus formed is placed on the liquid crystal display panel of the liquid crystal display device, and the optical sheet is obtained in the same manner as in Example 1. Was evaluated. The results are shown in Table 1.

(Example 3)
<Production of optical sheet>
In Example 2, except that silver was used instead of aluminum, the light was not transmitted through the second surface 4 of the support 2 in the same manner as in Example 2, but the silver as stripes as an optical adjustment unit The optical sheet (prism sheet) of Example 3 on which the vapor deposition layer was formed was obtained. The optical reflectance of the optical adjustment unit was 92%.

<Production and Evaluation of Display Device with Optical Sheet>
The optical sheet (prism sheet) of Example 3 on which the optical adjustment unit 7 having partial light reflectivity is thus formed is placed on the liquid crystal display panel of the liquid crystal display device, and the optical sheet is obtained in the same manner as in Example 1. Was evaluated. The results are shown in Table 1.

Example 4
<Production of optical sheet>
In Example 4, as described later, the support has a multilayer structure, and an optical adjustment unit is formed in a part of the light non-passing part of these supports.
First, as shown in FIG. 9A, the prism layer coating solution (cured) prepared above is applied to the flat second surface 4 side of the prism sheet B (support 2 on which the concavo-convex portion 5 is formed) obtained above. The refractive index after 1.59) was applied so as to have a dry film thickness of 20 μm, and dried at 100 ° C. for 2 minutes to obtain a support 2 having a photosensitive layer 13.
A PET support 14 having a thickness of 25 μm and not subjected to an easy adhesion treatment was bonded to the surface of the support 2 having the photosensitive layer 13 on the photosensitive layer 13 side.
From the side of the first surface 3 on which the concavo-convex portion 5 of the support 2 is formed, using the parallel light irradiation machine (mask alignment device M-2L, manufactured by Mikasa Co., Ltd.), the flat second surface 4 After irradiating ultraviolet rays parallel to the normal direction and exposing the photosensitive layer 13, the PET support 14 having a thickness of 25 μm is peeled off, and then an unexposed portion of the photosensitive layer 13 using normal propanol (ie, light The non-passing portion 6) was washed away, and as shown in FIG. 9B, the support 2 partially having the photosensitive layer 13 (that is, the second support) was formed.
On the second surface 4 of the support 2 partially having the photosensitive layer 13 as described above, the photocurable resin liquid 2 prepared above (with a refractive index after curing of 1.71) is added to the dry film weight. Was applied at a temperature of 15 g / m ² , then dried at 100 ° C. for 1 minute, and then subjected to an easy adhesion treatment, the PET support 15 having a thickness of 188 μm (that is, the third support) was subjected to the photocuring property. The photosensitive layer 13 was flattened by bonding to the surface to which the resin solution 2 was applied (FIG. 9C). Then, it exposed with the exposure amount of 1,500 mJ / cm < ² >, and obtained the optical sheet 1 (prism sheet | seat) of Example 4 which has a high refractive index part (code | symbol 7 of FIG. 9C) partially. In such an optical sheet 1, the side lobe light emission as shown by the dotted line B in FIG. 9C is small, and the optical path is corrected to the optical path shown by the solid line B ′, so that an optical sheet with high front luminance is obtained.

<Production and Evaluation of Display Device with Optical Sheet>
The optical sheet (prism sheet) of Example 4 in which the optical adjustment unit 7 having a partially high refractive index was formed in this way was placed on the liquid crystal display panel of the liquid crystal display device, and the optical sheet was obtained in the same manner as in Example 1. Was evaluated. The results are shown in Table 1.

(Example 5)
<Production of optical sheet>
Also in Example 5, the support has a multilayer structure, and an optical adjustment unit is formed in a part of the light non-passing part of these supports.
As shown in FIG. 10A, the prism layer coating solution prepared above (the refractive index after curing) is formed on the flat second surface 4 side of the prism sheet A prepared above (the support 2 on which the concavo-convex portion 5 is formed). 1.59) was applied so as to have a dry film thickness of 20 μm and dried at 100 ° C. for 2 minutes to obtain a support 2 having a photosensitive layer 13.
A PET support 14 having a thickness of 25 μm and not subjected to an easy adhesion treatment was bonded to the surface of the support 2 having the photosensitive layer 13 on the photosensitive layer 13 side.
From the side of the first surface 3 on which the concavo-convex portion 5 of the support 2 is formed, using the parallel light irradiation machine (mask alignment device M-2L, manufactured by Mikasa Co., Ltd.), the flat second surface 4 After irradiating ultraviolet rays parallel to the normal direction and exposing the photosensitive layer 13, the PET support 14 having a thickness of 25 μm is peeled off, and then an unexposed portion of the photosensitive layer 13 using normal propanol (ie, light The non-passing portion 6) was washed away, and as shown in FIG. 10B, the support 2 partially having the photosensitive layer 13 (that is, the second support) was formed.
On the second surface 4 of the support 2 partially having the photosensitive layer 13 as described above, the photocurable resin liquid 3 adjusted as described above (the refractive index after curing is 1.48) is added to the dry film weight. Was applied at a temperature of 15 g / m ² , then dried at 100 ° C. for 1 minute, and then subjected to an easy adhesion treatment, the PET support 15 having a thickness of 188 μm (that is, the third support) was subjected to the photo-curing property. The photosensitive layer 13 was flattened by bonding to the surface to which the resin solution 3 was applied (FIG. 10C). Then, it exposed with the exposure amount of 1,500 mJ / cm < ² >, and obtained the optical sheet 1 (prism sheet) of Example 5 which has a low-refractive-index part partially (code | symbol 7 of FIG. 10C).

<Production and Evaluation of Display Device with Optical Sheet>
The optical sheet (prism sheet) of Example 5 in which the optical adjustment unit 7 having a partially low refractive index was formed in this way was placed on the liquid crystal display panel of the liquid crystal display device, and the optical sheet was obtained in the same manner as in Example 1. Was evaluated. The results are shown in Table 1.

(Examples 6 to 8)
<Production of optical sheet>
In the same optical sheet 1 as in Examples 1 to 3, on the flat surface side opposite to the first surface 3 on which the concavo-convex portion 5 was formed, the prism layer coating liquid prepared above (the refractive index after curing is 1.59) was applied so that the dry film thickness was 2 μm, then dried at 100 ° C. for 1 minute, and then subjected to easy adhesion treatment, a 188 μm thick PET support (that is, the second support), It bonded together on the surface which apply | coated the said prism layer coating liquid, and it exposed by the exposure amount of 1,500 mJ / cm < ² >, and obtained the optical sheet 1 (prism sheet) of Examples 5-7, respectively.

<Evaluation of optical sheet>
In the optical sheets of Examples 6 to 8, since the second support was laminated, the support had sufficient rigidity, and had sufficient rigidity as a prism sheet for large-size displays.

<Production and Evaluation of Display Device with Optical Sheet>
Further, the optical sheets (prism sheets) of Examples 6 to 8 were installed on the liquid crystal display panel of the liquid crystal display device, and the optical sheets were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
<Production of optical sheet>
As the optical sheet of Comparative Example 1, the prism sheet A produced above was used as it was.
<Production and Evaluation of Display Device with Optical Sheet>
The optical sheet (prism sheet) of Comparative Example 1 was placed on the liquid crystal display panel of the liquid crystal display device, and the optical sheet was evaluated in the same manner as in Example 1. The results are shown in Table 1.

From the results shown in Table 1, the optical sheet (prism sheet) on which the optical adjustment unit having optical properties different from those of the supports of Examples 1 to 8 is formed has high brightness on the front surface (normal direction of the prism sheet). In addition, there was little emitted light seen at an angle of about 70 ° in the direction perpendicular to the prism ridge line from the normal direction of the prism sheet called a side lobe, and it had characteristics suitable as a display material.
On the other hand, in the optical sheet of Comparative Example 1 in which no optical adjustment unit is formed, the emitted light seen at an angle of about 70 ° from the normal direction of the prism sheet called side lobe in a direction orthogonal to the prism ridge line The brightness of the front surface (normal direction of the prism sheet) was low.
In addition, since the optical sheets of Examples 4 to 8 had two or more layers of the support, the optical sheets had high rigidity and good properties, and had characteristics suitable as an optical sheet for direct display.

  The optical sheet of the present invention has an excellent light collecting function or light diffusing function, reduces the influence of the side lobe by effectively using the side lobe light, and increases the luminance in a desired angular direction, particularly in the front direction. Therefore, it can be suitably used for a liquid crystal display device used in a mobile phone, a monitor for a personal computer, a television, a liquid crystal projector, and the like. Moreover, since the said optical sheet is especially excellent in condensing property, in the above-mentioned liquid crystal display device, it can be used more suitably as a condensing sheet excellent in the brightness | luminance.

FIG. 1 is a schematic view showing an example of a liquid crystal display device using a conventional optical sheet. FIG. 2 is a schematic view showing an optical path such as sidelobe light in a conventional optical sheet (prism sheet). FIG. 3 is a schematic diagram illustrating an example of a prism sheet manufacturing apparatus. FIG. 4 is a schematic diagram illustrating a light non-passing portion. FIG. 5A is a schematic diagram illustrating an example of an optical adjustment unit formed on the optical sheet of the present invention. FIG. 5B is a schematic diagram illustrating an example of an optical adjustment unit formed on the optical sheet of the present invention. FIG. 5C is a schematic diagram illustrating an example of an optical adjustment unit formed on the optical sheet of the present invention. FIG. 5D is a schematic diagram illustrating an example of an optical adjustment unit formed on the optical sheet of the present invention. FIG. 5E is a schematic diagram illustrating an example of an optical adjustment unit formed on the optical sheet of the present invention. FIG. 6A is a schematic diagram illustrating a manufacturing process (No. 1) of an optical sheet of Example 1 of the present invention. FIG. 6B is a schematic diagram illustrating a manufacturing process (No. 2) of the optical sheet of Example 1 of the present invention. FIG. 6C is a schematic diagram illustrating a manufacturing process (No. 3) of the optical sheet of Example 1 of the present invention. FIG. 6D is a schematic diagram illustrating a manufacturing process (No. 4) of the optical sheet according to the first embodiment of the present invention. FIG. 6E is a schematic diagram illustrating a manufacturing process (No. 5) of an optical sheet according to Example 1 of the present invention. FIG. 7 is a schematic view showing an optical path of the optical sheet of the present invention. FIG. 8A is a schematic diagram showing a manufacturing process (No. 1) of an optical sheet of Example 2 of the present invention. FIG. 8B is a schematic diagram illustrating a manufacturing process (No. 2) of the optical sheet of Example 2 of the present invention. FIG. 8C is a schematic diagram illustrating a manufacturing process (No. 3) of the optical sheet of Example 2 of the present invention. FIG. 8D is a schematic diagram illustrating a manufacturing process (No. 4) of an optical sheet of Example 2 of the present invention. FIG. 8E is a schematic view showing a manufacturing process (No. 5) of an optical sheet of Example 2 of the present invention. FIG. 9A is a schematic view showing a manufacturing process (No. 1) of an optical sheet of Example 3 of the present invention. FIG. 9B is a schematic diagram illustrating a manufacturing process (No. 2) of an optical sheet according to Example 3 of the present invention. FIG. 9C is a schematic diagram illustrating a manufacturing process (No. 3) of an optical sheet according to Example 3 of the present invention. FIG. 10A is a schematic diagram illustrating a manufacturing process (No. 1) of an optical sheet according to Example 4 of the present invention. FIG. 10B is a schematic diagram illustrating a manufacturing process (No. 2) of an optical sheet according to Example 4 of the present invention. FIG. 10C is a schematic diagram illustrating a manufacturing process (No. 3) of an optical sheet according to Example 4 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical sheet 2 Support body 3 1st surface 4 2nd surface 5 Concavity and convexity part 6 Non-passing part 7 Optical adjustment part 80 Prism sheet manufacturing apparatus 81 Sheet supply means 82 Application means 83 Embossing roll 84 Nip roll 85 Resin hardening means 86 Peeling Roll 87 Protective film supply means 88 Sheet winding means 89 Drying means W Support

Claims (12)

An optical sheet formed of a material that is essentially non-visible to light absorption,
A support having a first surface on which concave and convex portions that collect or scatter light are formed;
An optical preparation part having different optical properties from the support,
The light in the support when the optical adjustment unit receives light parallel to the normal direction of the second surface located on the opposite side of the first surface from the first surface side An optical sheet formed on at least a part of the non-passing portion.   The optical sheet according to claim 1, wherein the optical property is light reflectivity.   The optical sheet according to claim 1, wherein the optical property is light diffusibility.   The optical sheet according to claim 1, wherein the optical property is a refractive index difference.   The optical sheet according to any one of claims 1 to 4, wherein the support has a multilayer structure of two or more layers.   The optical sheet according to any one of claims 1 to 4, wherein the uneven portion has a prism structure.   The optical sheet according to claim 6, wherein the prism structure is an isosceles triangle having an apex angle of 60 to 120 °. A method for producing an optical sheet according to any one of claims 1 to 7,
A photosensitive layer forming step of forming a photosensitive layer on the second surface of the support on which at least the concave and convex portions for condensing or scattering light are formed on the first surface, the side being opposite to the first surface. When,
From the first surface side of the support, an exposure step of exposing the photosensitive layer by entering light parallel to the normal direction of the second surface;
An optical adjustment portion forming step of forming an optical adjustment portion, which is a non-exposed portion of the photosensitive layer, and has an optical property different from that of the support on the support;
A method for producing an optical sheet, comprising:   The method for producing an optical sheet according to claim 8, comprising a step of forming at least one second support on the second surface side of the support.   10. The photosensitive layer according to claim 8, wherein the photosensitive layer is a positive photosensitive layer, the photosensitive layer in the exposed portion is removed by development, and an optical adjustment portion is formed on at least a part of the photosensitive layer in the non-exposed portion. The manufacturing method of the optical sheet of description.   10. The photosensitive layer is a negative photosensitive layer, the photosensitive layer in the non-exposed area is removed by development, and an optical adjustment section is formed in at least a part of the removed area of the photosensitive layer. The manufacturing method of the optical sheet in any one of. 10. The photosensitive layer is a photocurable positive photosensitive layer, and an optical adjustment portion is formed on at least a part of the photosensitive layer in the non-exposed portion by utilizing a change in adhesiveness due to exposure. The manufacturing method of the optical sheet in any one of.