JP2008003244A - Optically functional sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optically functional sheet which is not deformed and damaged in handling such as assembling and is excellent in a light diffusing function and a condensing function. <P>SOLUTION: The optically functional sheet contains an optical diffusion component 3, and has a first surface 1A at which a prism structure 2 is formed and a second surface 1B at which the prism structure 2 is not formed, and the prism structure 2 of the first surface 1A is composed of recessed parts 2A. It is preferable that, e.g., each recessed part 2A has an almost conical shape and/or a polygonal pyramid shape, or the cross-section of the tip part 2a formed at each bottom face of the adjoining recessed parts 2A forms a curved line with an almost circular-arc shape and the radius of curvature r in the curved line is ≥2 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical functional 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 both a light collecting function and a light diffusion function.

In recent years, a lens film for condensing light from a light source such as a light guide plate in the front direction, a diffusion sheet for diffusing, and the like have been 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. 6, light emitted from a light source 45 such as a light guide plate enters a light collecting film (optical sheet) 41, and part of the incident light is The light is refracted and transmitted by the condensing film 41, and the angle of emission is changed and emitted in the front direction, and the rest is reflected and returned to the light source 42. 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 again.
With such a configuration, the luminance distribution of the light emitted from the light source is widely dispersed and the front luminance is low. Therefore, the light from the light source is increased in the front direction by the condensing film 41. The directional characteristics have been improved.

As the condensing film and the diffusing plate, an optical functional sheet having both a condensing function and a light diffusing function has been proposed.
As the optical functional sheet, for example, on at least one surface of a light diffusive sheet containing 0.5 to 10 parts by mass of a bead-shaped crosslinked acrylic resin having an average particle diameter of 1 to 20 μm with respect to 100 parts by mass of a highly transparent resin, A sheet (see Patent Document 1) on which fine cross-section serrated ridges are formed, and a sheet in which a prism array having a specific curved surface shape is formed on the surface of a diffusion plate containing a light diffusing agent (see Patent Document 2) A sheet (see Patent Document 3) in which a plurality of convex portions made of prisms are formed on at least one side of a light diffusion sheet having a total light transmittance of 60 to 95% has been proposed.

However, in any of the above proposals, as shown in FIG. 7, the optical functional sheet 51 is assembled because the top portion 52 a of the prism structure 52 provided to express the light collecting function protrudes and the tip is sharp. There was a problem that it was easily deformed or scratched during handling.
In addition, it is necessary to increase the diffusing agent in order to enhance the diffusion function. For this reason, there is a problem that the light transmittance is lowered due to the increase of the diffusing agent, and the luminance performance is lowered.

  Therefore, an optical functional sheet that is not deformed or scratched during handling such as assembly and has an excellent light diffusing function and light collecting function has not yet been provided, and further improvement and development are desired. is the current situation.

JP-A-9-304606 JP 2003-16819 A JP-A-2005-321681

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide an optical functional sheet that is not deformed or scratched during handling such as assembly and that has an excellent light diffusing function and light collecting function.

Means for solving the problems are as follows. That is,
<1> A first surface including a light diffusing component and having a prism structure formed thereon and a second surface not having the prism structure formed therein, wherein the prism structure on the first surface is a recess. It is an optical functional sheet characterized by comprising.
<2> The optical functional sheet according to <1>, wherein the concave portion has at least one of a substantially conical shape and a polygonal pyramid shape.
<3> The optical functional sheet according to any one of <1> to <2>, wherein a top cross section formed on an adjacent concave bottom surface forms a substantially arcuate curve.
<4> The optical functional sheet according to <3>, wherein the curvature radius of the curve is 2 μm or more.
<5> The content <1> to <4>, wherein the content of the light diffusing component increases from the first surface side where the prism structure is formed to the second surface side opposite to the first surface. The optical functional sheet according to any one of the above.
<6> The optical functional sheet according to <5>, wherein the optically functional sheet has a laminated structure of two or more layers, and the light collecting layer including the prism structure does not include a light diffusion component.
<7> An adjacent layer adjacent to the condensing layer, the condensing layer side surface of the adjacent layer has an uneven shape, and the uneven shape is the uneven shape formed by the prism structure included in the condensing layer, etc. The optical functional sheet according to <6>, wherein the optical functional sheet is a pitch.

The optical functional sheet of the present invention includes a first surface including a light diffusing component and having a prism structure formed thereon, and a second surface not having the prism structure formed thereon. The prism structure on the surface consists of concave portions.
For this reason, when the first surface is a continuous surface, and other members are placed on the first surface facing the reference horizontal surface by assembling or the like, no deformation or scratches occur, and Excellent light diffusing function and light collecting function.

  According to the present invention, it is possible to provide an optical functional sheet that can solve the above-described conventional problems, that is not deformed or damaged during handling such as assembly, and that has an excellent light diffusion function and light collecting function.

  The optical functional sheet of the present invention includes a first surface including a light diffusing component and having a prism structure formed thereon, and a second surface not having the prism structure formed thereon. The prism structure on the surface is formed of a concave portion.

  The optical functional sheet will be described in more detail with reference to FIG. 1. The optical functional sheet 1 of the present invention includes a first surface 1A on which a prism structure 2 is formed, and the prism structure 2 formed thereon. A part of light (not shown) from a light source such as a light guide plate is incident on the prism structure 2, and the incident light is refracted and transmitted to form an angle of emission. Changes, the light is emitted in the front direction, and the remaining light is reflected and returned to the direction of the light source, diffused by the light diffusing component 3, and incident on the prism structure 2 again. The prism structure 2 includes a recessed portion 2A that is recessed, and the first surface 1A is a continuous surface so that no protrusions are present. Thereby, generation | occurrence | production of a deformation | transformation and a damage | wound can be prevented at the time of handling, such as an assembly. In the illustrated example, the concave portion 2A has a shape that is recessed in a polygonal pyramid shape. However, other shapes such as a substantially conical shape, a substantially hemispherical shape, and a substantially elliptical shape can be formed. If there is no restriction in particular.

As shown in FIG. 2, the top 2a formed on the bottom surface of the adjacent recess 2A of the prism structure preferably has a substantially arc-shaped cross section as shown in FIG. The curvature radius r of the curve is preferably 2 μm or more, and more preferably 2 to 5 μm.
Here, the curvature radius r of 2 μm or more means a curvature radius when viewed from a cross section in a direction orthogonal to the bottom surface of the recess 2A.

  The optical functional sheet includes a light diffusing component, and a prism structure is formed in which the content of the light diffusing component is opposite to the first surface from the first surface side where the prism structure is formed. The second surface (hereinafter also referred to simply as “second surface”) increases, that is, the content of the light diffusing component is minimal on the first surface side, It is preferable that it increases as it approaches the surface side. In general, molding with ionizing radiation curable resin or extrusion molding tends to warp the prism structure side, but by adding a light diffusion component in this way, the warp to the prism structure side is offset, and as a whole It can be a flat shape. In addition, as long as the content of the light diffusing component increases from the first surface side to the second surface side, the density gradient may be continuous or discontinuous.

  In order to include a large amount of light diffusing components from the first surface side to the second surface side, the optical functional sheet has, for example, a two or more layered structure, and a condensing layer including a prism structure. Is preferably free of light diffusing components.

  As such a preferable configuration, for example, as in the optical functional sheet 11 shown in FIG. 3, the condensing layer 14 including the prism structure 12 located on the most first surface 11A side, and the condensing layer 14 The adjacent contiguous layer 15 and the light diffusing layer 16 positioned closest to the second surface 11B are included, the condensing layer 14 does not include the light diffusing component 13, and is more light diffusing than the adjacent layer 15. An embodiment in which 16 has a higher content of the light diffusing component 13 may be mentioned.

For example, the content of the light diffusion component 13 in the adjacent layer 15 is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass.
For example, the content of the light diffusion component 13 in the light diffusion layer 16 is preferably 1 to 50 mass%, and more preferably 2 to 25 mass%.

In the optical functional sheet 11, the surface of the adjacent layer 15 on the light collecting layer 14 side has an uneven shape, and the pitch l of the uneven shape is the pitch L of the uneven shape of the prism structure 12 included in the light collecting layer 14. And are formed at equal intervals. For this reason, it can condense also on the surface (surface by the side of the condensing layer 14) of the adjacent layer 15, and a condensing function improves. The pitch is preferably 10 to 100 μm, for example.
The other structures of the optical functional sheet 11 are the same as those of the optical functional sheet 1. In addition, as shown in FIG. 2, it is preferable that the top portion 12 a formed on the bottom surface of the adjacent concave portion 12 </ b> A is formed in a substantially arc shape like the optical functional sheet 1.

-Light diffusion component-
There is no restriction | limiting in particular as said light-diffusion component, A diffusion particle may be contained, resin of different refractive index may be knead | mixed, and an air bead, a hollow bead, etc. may be contained. 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.
There is no restriction | limiting in particular as said diffusion particle, According to the objective, it can select suitably, For example, a titanium oxide, a silicon | silicone, a crosslinked acrylic resin etc. are mentioned.

  The light diffusing component has a plurality of dispersed structures. It is observed with an optical microscope such as a microscope (manufactured by Keyence Corporation) or a transmission electron microscope (TEM) that such a structure is formed and the content of the light diffusion component is larger on the second surface side. This can be confirmed.

-Manufacturing apparatus and manufacturing method-
The manufacturing apparatus and manufacturing method used for manufacturing the optical functional sheet are not particularly limited as long as a fine uneven shape can be formed. For example, the manufacturing apparatus 20 having the configuration shown in FIG. 4 is used. The method is preferably used.
The manufacturing apparatus 20 includes a sheet supply unit 21, a coating unit 22, a drying unit 29, an embossing roll 23 that is an uneven roll, a nip roll 24, a resin curing unit 25, a peeling roll 26, a protective film supply unit 27, and a sheet winding unit 28. It is composed of

  The sheet supply unit 11 sends out a sheet, and includes a feed roll around which the sheet is wound.

  The coating means 22 is a device that applies a radiation curable resin to the surface of the sheet. The supply means 22A for supplying the radiation curable resin, a supply device (pump) 22B, a coating head 22C, and a sheet are wound when coating. The supporting roller 22D is hung and supported, and a pipe for supplying the radiation curable resin supply source 22A to the coating head 22C. In FIG. 4, an application head of an extrusion type die coater is used as the coating head.

  As the drying means 29, various known methods can be appropriately selected as long as the coating liquid applied to the sheet can be uniformly dried, such as a tunnel-shaped drying apparatus shown in FIG. Can be used. Specific examples include a radiant heating system using a heater, a hot air circulation system, a far infrared system, and a vacuum system.

  The embossing roll 23 is required to have a concavo-convex pattern accuracy, mechanical strength, roundness, and the like so that the ruggedness of the roll surface can be transferred and formed on the surface of the sheet. As such an embossing roll 23, a metal roll is preferable, for example.

  A regular fine uneven pattern is formed on the outer peripheral surface of the embossing roll 23. 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 an embossed sheet as a product.

  As an embossed sheet as a product, for example, a lens in which fine concavo-convex patterns such as lenticular lenses and prism lenses are arranged two-dimensionally; for example, a lens in which fine concavo-convex patterns such as fly-eye lenses are arranged three-dimensionally; A flat lens or the like in which fine cones are laid in the X and Y directions is an object, and a regular fine uneven pattern on the outer peripheral surface of the embossing roll 23 corresponds to these lenses.

  As a method of forming a regular fine uneven pattern on the outer peripheral surface of the embossing roll 23, for example, a method of cutting the surface of the embossing roll 23 with a diamond bit (single point); Examples thereof include a method of directly forming irregularities by drawing, laser processing, and the like. Further, unevenness is formed on the surface of the thin metal plate by photo etching, electron beam drawing, laser processing, optical modeling, etc., and this plate is wound around the roll and fixed, The method of doing is also mentioned. In addition, uneven surfaces are formed on the surface of materials that are easier to process than metal by photoetching, electron beam drawing, laser processing, stereolithography, etc. There is also a method in which a plate-shaped body made is manufactured, and this plate-shaped body is wound and fixed around the roll to form an emboss roll 23. In particular, when the reversal 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 plate (mother).

It is preferable to perform a mold release process on the surface of the embossing roll 23. Thus, the shape of the fine concavo-convex pattern can be satisfactorily maintained by performing the mold release process on the surface of the embossing roll 23.
As the mold release treatment, various known methods can be appropriately selected according to the purpose, and examples thereof include a coating treatment with a fluororesin. The embossing roll 23 is preferably provided with driving means. Further, the embossing roll 23 rotates counterclockwise (CCW) as shown by the arrow in the figure.

  The nip roll 24 forms a roll while pressing the sheet while being paired with the embossing roll 23, and is required to have predetermined mechanical strength, roundness, and the like. The longitudinal elastic modulus (Young's modulus) of the surface of the nip roll 24 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 substances such as dust and tends to cause defects. It is preferable. The nip roll 24 is preferably provided with a driving means. Further, the nip roll 24 rotates in the clockwise direction (CW) as shown in the figure.

  In order to apply a predetermined pressing force between the embossing roll 23 and the nip roll 24, it is preferable to provide a pressing means on either the embossing roll 23 or the nip roll 24. Similarly, it is preferable to provide fine adjustment means on either the embossing roll 13 or the nip roll 14 so that the gap (clearance) or pressure between the embossing roll 23 and the nip roll 24 can be accurately controlled.

  The resin curing means 25 is a radiation irradiation means provided opposite to the embossing roll 23 on the downstream side of the nip roll 24. This resin curing means 25 transmits the sheet by radiation irradiation and cures the resin layer, and can preferably irradiate the radiation according to the curing characteristics of the resin and irradiate the amount of radiation according to the sheet conveyance speed. . As the resin curing means 25, for example, a cylindrical irradiation lamp having substantially the same length as the width of the sheet can be mentioned. A plurality of the cylindrical irradiation lamps may be provided in parallel, or a reflection plate may be further provided on the back surface of the cylindrical lamp.

The peeling roll 26 is a pair of the embossing roll 23 and peels the sheet from the embossing roll 23, and is required to have predetermined mechanical strength, roundness, and the like.
Specifically, the sheet is peeled from the embossing roll 23 while being sandwiched between the rotating embossing roll 23 and the peeling roll 26 at the peeling location, and the sheet is wound on the peeling roll 26. Wrap it around. In order to ensure this operation, the peeling roll 26 is preferably provided with a driving means. The peeling roll 26 rotates clockwise (CW).

  Moreover, when the temperature of resin etc. rises by hardening, you may provide a cooling means in the peeling roll 26 in order to cool a sheet | seat at the time of peeling, and to ensure peeling.

  In addition, although illustration was abbreviate | omitted, between the pressing location (9 o'clock position) of the embossing roll 23 and the peeling location (3 o'clock position), a plurality of backup rolls are provided to face each other. The curing process may be performed while pressing the sheet with the roll 23.

  The sheet take-up means 28 stores the peeled sheet, and includes a take-up roll that takes up the sheet. By the sheet winding means 28, the protective film supplied from the adjacent protective film supply means 27 is supplied to the surface of the sheet, and is stored in the sheet winding means 28 in a state where both films are overlapped.

  Further, in the manufacturing apparatus 20, a guide roller or the like that forms a sheet conveyance path may be provided between the coating unit 22 and the embossing roll 23, between the peeling roll 26 and the sheet winding unit 28, and the like. In addition, a tension roller or the like may be provided as needed to absorb slack during conveyance of the sheet W.

  Next, the operation of the manufacturing apparatus 20 will be described. The sheet is fed from the sheet supply means 21 at a constant speed. The sheet is fed into the application means 12 and the resin is applied to the surface of the sheet. After application, the solvent in the coating solution is evaporated by the drying means 29. Next, the sheet is fed into forming means composed of an embossing roll 23 and a nip roll 24. Thus, roll forming is performed while pressing the continuously running sheet with the rotating embossing roll 23 and the nip roll 24 at the 9 o'clock position of the embossing roll 23. That is, the sheet is wound around the rotating embossing roll 23, and the unevenness on the surface of the embossing roll 23 is transferred to the resin layer.

  Next, in a state where the sheet is wound around the embossing roll 23, the resin curing means 25 transmits the sheet and irradiates the resin layer with radiation, thereby curing the resin layer. Then, the sheet is peeled from the embossing roll 23 by winding the sheet around the peeling roll 26 at the 3 o'clock position of the embossing roll 23.

  In addition, although not shown in FIG. 1, after peeling a sheet | seat, in order to accelerate hardening further, you may irradiate with radiation again.

  The peeled sheet is conveyed to the sheet take-up means 28, the protective film supplied from the protective film supply means 27 is supplied to the surface of the sheet, and the take-up roll of the sheet take-up means 28 in a state where both films overlap. Is wound and stored.

  Thus, the resin layer is formed on the surface of the sheet without unevenness of thickness, and the embossing roll is also stably and uniformly pressed. Thereby, the uneven | corrugated sheet | seat in which the regular fine uneven | corrugated pattern was formed in the surface can be manufactured with high quality without a defect.

  Further, in the example of the manufacturing apparatus 20 described above, the embodiment in which the roll-shaped embossing roll 23 is used has been described. However, the surface of the belt such as an endless belt having an uneven pattern (embossed shape) is used. Also good. This is because even such a belt acts in the same manner as a cylindrical roll, and the same effect can be obtained.

−Material−
Examples of the material of the sheet used as the optical functional sheet include a resin film, paper (resin coated paper, synthetic paper, etc.), metal foil (aluminum web, etc.), and the like.
Examples of the material of the resin film include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyolefin, acrylic, polystyrene, polycarbonate, polyamide, PET (polyethylene terephthalate), and biaxial stretching. Examples include polyethylene terephthalate, polyethylene naphthalate, polyamideimide, polyimide, aromatic polyamide, cellulose acylate, cellulose triacetate, cellulose acetate propionate, and cellulose diacetate. Of these, polyester, cellulose acylate, acrylic, polycarbonate, and polyolefin are particularly preferably used.

  The sheet generally has a width of 0.1 to 3 m, a length of 1,000 to 100,000 m, and a thickness of 1 to 300 μm. However, application of other sizes is not impeded.

  The sheet 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 is preferably 3 to 10 nm at a cutoff value of 0.25 mm.

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

As the resin used for the resin layer, for example, a reactive group-containing compound such as a (meth) acryloyl group, a vinyl group, and an epoxy group can be reacted with the reactive group-containing compound by irradiation with ultraviolet rays or the like. And compounds containing compounds that generate active species such as radicals and cations.
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 these, (meth) acryloyl group-containing compounds such as (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate are preferable. As this (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 individually by 1 type, and 2 or more types are mixed and used as needed. May be.

  Examples of the (meth) acryloyl group-containing compound include, for example, isobornyl (meth) acrylate, bornyl (meth) acrylate, and tricyclodecanyl (meth) as monofunctional monomers containing only one (meth) acryloyl group-containing compound. 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, isopropyl (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, butto Siethyl (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 (meth) Examples include acrylate and methoxypolypropylene glycol (meth) acrylate.

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

  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. Diacrylate; polyalkylene glycol diacrylate such as ethylene glycol di (meth) acrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate; neopentyl glycol di (meth) acrylate, tricyclodecane methanol diacrylate, and the like.

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 Addition tetrabromobisphenol 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 ) Tetrabromobisphenol A epoxy (meth) acrylate, bisphenol F diglycidyl ether obtained by epoxy ring-opening reaction with acrylic acid Bisphenol F epoxy (meth) acrylate obtained by epoxy ring-opening reaction with (meth) acrylic acid, tetrabromobisphenol F epoxy (meta) obtained by epoxy ring-opening reaction between tetrabromobisphenol F diglycidyl ether and (meth) acrylic acid ) Acrylate and the like.
Examples of commercially available unsaturated monomers having such a structure include, for example, Biscote # 700, # 540 (above, manufactured by Osaka Organic Chemical Industry Co., Ltd.), Aronix M-208, M-210 (above, Toagosei ( 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, Daiichi Kogyo Seiyaku Co., Ltd.), Lipoxy VR-77, VR-60, VR-90, SP-1506, SP-1506, SP-1507, SP-1509 SP-1563 (manufactured by Showa Polymer Co., Ltd.), Neopole V779, Neopole V779MA (manufactured by Nippon Iupika Co., Ltd.), and the like.

Examples of the trifunctional or higher functional (meth) acrylate unsaturated monomer include trimethylolpropane litho (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, and tris (2-acryloyloxy). (Meth) acrylates of trihydric or higher polyhydric alcohols such as ethyl) isocyanurate.
Examples of commercially available trifunctional or higher functional (meth) acrylate unsaturated monomers include, for example, Aronix M305, M309, M310, M315, M320, M350, M360, M408 (above, manufactured by Toagosei Co., Ltd., Biscote # 295, # 300, # 360, GPT, 3PA, # 400 (above, manufactured by Osaka Organic Chemical Industry Co., Ltd.), NK ester TMPT, A-TMPT, A-TMM-3, A-TMM-3L, A-TMMT (above, Shin Nakamura Chemical Co., Ltd.), Light Acrylate TMP-A, TMP-6EO-3A, PE-3A, PE-4A, DPE-6A (above, Kyoeisha Chemical Co., Ltd., KAYARAD PET-30, GPO-303) , TMPTA, TPA-320, DPHA, D-310, DPCA-20, DPCA-60 (above, manufactured by Nippon Kayaku Co., Ltd.) ) And the like.

  From the viewpoint of keeping the viscosity moderate for the (meth) acryloyl group-containing compound. A urethane (meth) acrylate oligomer may be further blended. Examples of the urethane (meth) acrylate 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) A dibasic acid such as phthalic acid and a diol such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol Polyester polyol obtained by reaction; polyε-caprolactone-modified polyol; polymethylvalerolactone-modified polyol; ethylene glycol, propylene glycol, 1,4-butanedio 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; bisphenols such as ethylene oxide-added bisphenol F and propylene oxide-added bisphenol F F-skeleton alkylene oxide modified polyol, or a mixture thereof and organic polyisocyanates such as tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meta ) From hydroxy group-containing (meth) acrylates such as acrylate The urethane (meth) acrylate oligomer etc. which are manufactured are mentioned.

  Examples of commercially available monomers of urethane (meth) acrylate include, for example, Aronix M120, M-150, M-156, M-215, M-220, M-225, M-240, M-245, and M-270. (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, Biscote # 195, # 230, # 260, # 215, # 335HP, # 310HP, # 310HG, # 312 (above, manufactured by Osaka Organic Chemical Industry Co., Ltd.), Light Acrylate IAA, LA, S- A, 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 ( A reaction product obtained by reacting (meth) acrylate with (b) organic polyisocyanate and then (c) polyol is preferable.

  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, die Ruthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide Bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, ethyl-2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, and the like.

  Commercially available products of the photo radical polymerization initiator include, for example, Irgacure 184, 369, 651, 500, 819, 907, 784, 2959, CGI 1700, CGI 1750, CGI 11850, CG 24-61, Darocur 116, 1173 (above, Ciba Specialty Chemicals), Lucirin LR8728, 8893X (above BASF), Ubekrill P36 (UCB), KIP150 (Lamberti) and the like. Among these, Lucirin LR8883X is preferable from the viewpoint of being liquid and easily dissolved and having high sensitivity.

  0.01-10 mass% is preferable in the whole composition which comprises resin, and, as for the compounding quantity of the said radical photopolymerization initiator, 0.5-7 mass% is more preferable. When the blending amount exceeds 10% by mass, the curing characteristics of the composition, the mechanical and optical characteristics of the cured product, and the handleability may be deteriorated. When the blending amount is less than 0.01% by mass, the curing rate is decreased. May decrease.

A photosensitizer can be further blended in the composition constituting the resin. Examples of the photosensitizer include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and 4-dimethylaminobenzoate. An isoamyl acid etc. are mentioned.
As a commercial item of the said photosensitizer, Ubekrill P102, 103, 104, 105 (above, the product made from UCB) etc. are mentioned, for example.

  In addition to the above components, various additives include, for example, antioxidants, ultraviolet absorbers, light stabilizers, silane coupling agents, coating surface improvers, thermal polymerization inhibitors, leveling agents, surfactants, and coloring agents. An agent, a storage stabilizer, a plasticizer, a lubricant, a solvent, a filler, an anti-aging agent, a wettability improver, a release agent, and the like can be blended as necessary.

Examples of the antioxidant include Irganox 1010, 1035, 1076, 1222 (above, manufactured by Ciba Specialty Chemicals Co., Ltd.), Antigen P, 3C, FR, GA-80 (manufactured by Sumitomo Chemical Co., Ltd.), and the like. Is mentioned.
Examples of the ultraviolet absorber include Tinuvin P, 234, 320, 326, 327, 328, 329, 213 (above, manufactured by Ciba Specialty Chemicals Co., Ltd.), Seesorb 102, 103, 110, 501, 202, 712. 704 (above, manufactured by Sipro Kasei Co., Ltd.).
Examples of the light stabilizer include Tinuvin 292, 144, 622LD (manufactured by Ciba Specialty Chemicals Co., Ltd.), Sanol LS770 (manufactured by Sankyo Co., Ltd.), Sumisorb TM-061 (Sumitomo Chemical Co., Ltd.). Manufactured) and the like.
Examples of the silane coupling agent include γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and commercially available products such as SH6062, 6030 (above, Toray Dow Corning). -Silicone Co., Ltd.), KBE903, 603, 403 (above, Shin-Etsu Chemical Co., Ltd.).
Examples of the coating surface improver include silicone additives such as dimethylsiloxane polyether and nonionic fluorosurfactants.
Commercially available products of the silicone additive include DC-57, DC-190 (above, manufactured by Dow Corning), SH-28PA, SH-29PA, SH-30PA, SH-190 (above, Toray Dow Corning Silicone ( Co., Ltd.), KF351, KF352, KF353, KF354 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), L-700, L-7002, L-7500, FK-024-90 (above, made by Nihon Unicar Co., Ltd.) ), Commercial products of nonionic fluorosurfactants include FC-430, FC-171 (above 3M Co., Ltd.), MegaFuck F-176, F-177, R-08 (above, Dainippon Ink) Etc.).
Examples of the release agent include Prisurf A208F (Daiichi Kogyo Seiyaku Co., Ltd.).

The organic solvent used for adjusting the resin liquid viscosity of the resin is not particularly limited as long as it can be mixed without unevenness such as precipitates, phase separation, and cloudiness when mixed with the resin liquid, Examples thereof include acetone, methyl ethyl ketone, methyl isobutyl ketone, ethanol, propanol, butanol, 2-methoxyethanol, cyclohexanol, cyclohexane, cyclohexanone, toluene and the like. These may be used individually by 1 type as needed, and 2 or more types may be mixed and used for them.
When the organic solvent is added, it is necessary to dry and evaporate the organic solvent during the manufacturing process of the product. However, if a large amount of residual solvent remains in the product, the mechanical properties of the product 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, as the organic solvent, those having a high boiling point are not preferable because the residual solvent amount increases. On the other hand, if the boiling point is too low, it will evaporate violently, resulting in rough surface conditions, 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 to 150 ° C, more preferably 70 to 120 ° C. Specifically, as the organic solvent, methyl ethyl ketone (bp. 79.6 ° C.), 1-propanol (bp. 97.2 ° C.) and the like are preferable from the viewpoint of the solubility of the raw material and the boiling point.

  The amount of the organic solvent added to the resin liquid depends on the type of the solvent and the viscosity of the resin liquid before the addition of the solvent, but usually 10 to 40% by mass in order to sufficiently improve the coatability. And 15-30 mass% is preferable. When the addition amount is less than 10% by mass, the effect of reducing the viscosity and the effect of increasing the coating amount are so small that the coatability may not be sufficiently improved. On the other hand, when the added amount exceeds 40 masses, the viscosity is too low and the liquid may flow on the sheet to cause unevenness, or the liquid may rotate around the back surface of the sheet. 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 can be produced by mixing the respective components by a conventional method, and can be produced by heating and dissolving as required.
The viscosity of the resin liquid thus prepared is usually 10 to 50,000 mPa · s / 25 ° C., but when the resin liquid is supplied to a substrate or an embossing roll, if the viscosity is too high, It becomes difficult to supply the composition uniformly, and when manufacturing lenses, uneven coating, undulation, and air bubbles are mixed in, making it difficult to obtain the desired lens thickness, and sufficient lens performance It cannot be demonstrated. In particular, this tendency becomes remarkable when the line speed is increased. Therefore, in this case, the liquid viscosity is preferably low, preferably 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. Further, the viscosity can be adjusted by setting the temperature of the coating solution to be kept warm.
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 die, and a uniform lens with a certain thickness may not be formed. Accordingly, in this case, the liquid viscosity is preferably high, and is preferably 100 to 3,000 mPa · s.
When the organic solvent is mixed, by providing a step of evaporating the organic solvent by heating and drying between the steps of supplying the resin solution and embossing the embossing roll, when supplying the resin solution, The liquid can be supplied uniformly with a low viscosity, and when embossing with an embossing roll, it is possible to uniformly emboss with a resin liquid obtained by drying an organic solvent and increasing the viscosity.

  The cured product obtained by curing the resin liquid with radiation has a refractive index at 25 ° C. of preferably 1.55 or more, and more preferably 1.56 or more. If the refractive index is less than 1.55, sufficient front luminance may not be ensured when an optical functional sheet is formed.

-Use-
Since the optical functional sheet of the present invention is not deformed or scratched during handling such as assembly, and has excellent light diffusing function and light collecting function, various displays such as liquid crystal display devices and organic EL, display devices In a lighting device or the like, it can be suitably used to adjust the light emission efficiency and emission characteristics. In particular, it is disposed between the light source device and the liquid crystal cell and can be used to form a liquid crystal display element as a whole.

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

(Example 1)
A 200 μm thick sheet containing 5 parts by weight of a cross-linked acrylic resin (manufactured by Soken Chemical Co., Ltd., MR8GSN) having an average particle size of 10 μm as a light diffusion component is extruded using a polycarbonate resin (Mitsubishi Chemical Co., Ltd.) as a base resin. After forming the film by molding, the concave quadrangular pyramid is transferred by hot pressing with a mold having a convex quadrangular pyramid with a bottom width of 50 μm and a height of 25 μm under conditions of 200 ° C. × 2 MPa × 10 minutes. An optical functional sheet was obtained.

The optical functional sheet has the structure shown in FIG. 1, and, as shown in FIG. 2, the cross section of the top 2a formed on the bottom surface of the adjacent recess 2A forms a substantially arc-shaped curve, and the curvature radius of the curve r was 2 μm.
Further, when the optical functional sheet was observed with a microscope (manufactured by Keyence Corporation), it was confirmed that a plurality of light diffusion components were dispersed.

(Example 2)
A 200 μm thick sheet containing 1 part by weight of a crosslinked acrylic resin (manufactured by Soken Chemical Co., Ltd., MR8GSN) having a polycarbonate resin (Mitsubishi Chemical Corporation) as a base resin and a light diffusion component having an average particle diameter of 10 μm is extruded. A film was formed by molding. After superposing this sheet and a polycarbonate sheet containing 5 parts by mass of the crosslinked acrylic resin formed in Example 1, the sheet side containing 1 part by mass of the crosslinked acrylic resin was 200 ° C. × 2 MPa × 10. The optical functional sheet on which the concave quadrangular pyramid was transferred was obtained by hot pressing with a mold having a convex quadrangular pyramid having a bottom width of 50 μm and a height of 25 μm.

(Example 3)
After laminating 25 μm of an acrylic resin film (manufactured by Mitsubishi Rayon Co., Ltd., HBS006) on a sheet formed by extrusion molding in the same manner as in Example 1, the bottom width was 50 μm under the conditions of 200 ° C. × 2 MPa × 10 minutes. An optical functional sheet having the concave quadrangular pyramid transferred thereon was obtained by hot pressing with a mold having a convex quadrangular pyramid having a height of 25 μm.

When the obtained optical functional sheet was observed with a microscope (manufactured by Keyence Corporation), the light-diffusing layer 14 having the structure shown in FIG. It was confirmed that the interface between the condensing layer 14 and the light diffusing layer 15 was formed with the pitch L of the concavo-convex shape of the prism structure 12 and the pitch l that was equally spaced. Further, it was confirmed that a plurality of light diffusion components 13 were dispersed in the light diffusion layer 15.
Here, in the optical functional sheet, the cross section of the top portion 12a formed on the bottom surface of the adjacent 12A concave portion has a substantially arcuate curve, and the curvature radius r of the curve is 2 μm.

(Comparative Example 1)
A sheet formed by extrusion molding in the same manner as in Example 1 is subjected to hot press processing using a mold having a continuous triangular prism having a bottom width of 50 μm and a height of 25 μm under the same conditions as in Example 1, so that a continuous triangular prism can be obtained. A transferred optical functional sheet was obtained. In addition, the convex part (top part) of a continuous triangular prism protrudes from the said functional sheet.

(Comparative Example 2)
A sheet formed by extrusion molding in the same manner as in Example 1 is subjected to hot press processing using a mold having a concave quadrangular pyramid having a bottom width of 50 μm and a height of 25 μm under the same conditions as in Example 1. An optical functional sheet having a transferred quadrangular pyramid was obtained. In addition, as shown in FIG. 6, the top part 52a of the prism structure 52 protrudes from the optical functional sheet.

(Reference Example 1)
Similarly to Example 2, a sheet containing 1 part by mass of a cross-linked acrylic resin and a sheet containing 5 parts by mass of the cross-linked acrylic resin were formed and overlaid, and then 5 parts by mass of the cross-linked acrylic resin. The optically functional sheet on which the concave quadrangular pyramid was transferred was obtained by subjecting the partially blended sheet to hot press processing under the same conditions as in Example 1.

[Evaluation]
For the optical functional sheets obtained in Examples 1 to 3, Comparative Examples 1 to 2 and Reference Example 1, the following criteria were used: (1) damaged by handling, (2) diffusion performance, (3) front luminance, And (4) Warpage balance was evaluated respectively. The results are shown in Table 1.
(1) Damage from handling ○ ・ ・ ・ No damage from handling.
X: There are scratches due to handling.
XX ・ ・ Scratches due to handling, causing problems in appearance.
(2) Diffusion performance ○ ・ ・ ・ There is no luminance unevenness and excellent diffusion performance.
X: Luminance unevenness is observed in the plane direction.
(3) Front luminance ○ Excellent.
X: Low.
(4) Warpage balance ○ ・ ・ ・ No warpage due to extrusion molding is observed, which is a good warpage balance.
Δ: Slightly warped to the prism structure side by extrusion molding, but at a practical level.
X: The prism structure is clearly warped by extrusion molding, and the warp balance is poor.

From the results of Table 1, the optical functional sheets of Example 1 and Example 2 in which the prism structure on the first surface is composed of concave portions are all good in handling damage, diffusion performance, and front luminance. understood. In particular, the optical contents of Example 2 and Example 3 in which the content of the light diffusing component increases from the first surface side where the prism structure is formed to the second surface side which is the opposite surface of the first surface. It was found that the functional sheet has an excellent warpage balance. In Reference Example 1, the content of the light diffusing component decreases from the first surface side where the prism structure is formed to the second surface side opposite to the first surface. The scratches, diffusion performance, and front brightness were good, but the warpage balance was poor.

  Since the optical functional sheet of the present invention is not deformed or scratched during handling such as assembly, and has excellent light diffusing function and light collecting function, various displays such as liquid crystal display devices and organic EL, display devices In a lighting device or the like, it can be suitably used to adjust the light emission efficiency and emission characteristics. In particular, it is disposed between the light source device and the liquid crystal cell and can be used to form a liquid crystal display element as a whole.

FIG. 1 is a schematic perspective view showing an example of the optical functional sheet of the present invention. FIG. 2 is a cross-sectional view of an essential part showing an example of a top portion formed on an adjacent concave bottom surface of the prism structure in the optical functional sheet of the present invention. FIG. 3 is a schematic cross-sectional view showing an example of the optical functional sheet of the present invention. FIG. 4 is a conceptual diagram showing an example of a manufacturing apparatus used for manufacturing the optical functional sheet of the present invention. FIG. 5 is a schematic cross-sectional view showing the optical functional sheet obtained in Example 3. FIG. 6 is a schematic cross-sectional view showing an example of a direct type backlight. FIG. 7 is a schematic cross-sectional view showing an example of a conventional optical functional sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Optical functional sheet 2,12 Prism structure 2A, 12A Concave part 2a, 12a (Prism structure) Top part formed in the bottom of an adjacent recessed part (Prism structure) 3,13 Light diffusion component 14 Condensing layer 15 Adjacent Layer 16 Light diffusion layer

Claims (5)

  It has a first surface including a light diffusion component and having a prism structure formed thereon, and a second surface not having the prism structure formed thereon, and the prism structure on the first surface is formed of a recess. An optical functional sheet characterized by the above.   2. The optical functional sheet according to claim 1, wherein a top cross section formed on an adjacent concave bottom surface forms a substantially arcuate curve, and the curvature radius of the curve is 2 μm or more.   The content of the light diffusing component increases from the first surface side on which the prism structure is formed to the second surface side that is the opposite surface of the first surface. Optical functional sheet.   The optical functional sheet according to claim 3, wherein the optical functional sheet has a laminated structure of two or more layers, and the light collecting layer including the prism structure does not include a light diffusion component. The condensing layer has an adjacent layer adjacent to the condensing layer, and the condensing layer side surface of the adjacent layer has an uneven shape, and the uneven shape has the same pitch as the uneven shape formed by the prism structure included in the condensing layer. The optical functional sheet according to claim 4.