JP5725398B2 - Visibility improvement sheet - Google Patents

Description

  The present invention relates to a visibility-enhancing sheet, and more particularly, is installed on the front surface of a display device, and the performance of the display device, in particular, contrast reduction, glare, and image reflection when the display device is exposed to external light. The present invention relates to a visibility-enhancing sheet having a function of preventing a decrease in performance due to stagnation and the like and a function of controlling the viewing angle by appropriately diffusing or condensing effective light of a display device.

  In a liquid crystal display device, it is usually preferred that the viewing angle is wide so that a good image can be obtained from any position of the observer. On the other hand, for example, when working on a commuter train or in a liquid crystal display device installed in a public place such as an ATM (automated teller machine), it may be difficult for people around to look into the screen. In such a case, a peeping prevention function is required to protect privacy so that it can be seen only by an observer of the liquid crystal display device and cannot be seen by others. In car-mounted liquid crystal display devices such as car navigation systems, the screen of the liquid crystal display device is reflected on the window glass at night and the like, and the phenomenon of blocking the field of view occurs. Control of the light emission angle is desired.

  In response to such a demand, for example, JP 2006-119365 A (Patent Document 1) proposes a louver-type visibility improving sheet having a structure in which light transmission layers and light shielding layers are alternately arranged. As a light shielding layer, it is disclosed to use a material comprising a light transmission layer mixed with a filler such as carbon black or carbon fiber.

  On the other hand, the louver-type visibility improving sheet as described above simply cuts the image light in the oblique direction, so that depending on the type of display device, the diffusion light source of the image light that should reach the observer is reduced. As a result, the brightness of the display screen may be lowered.

  In order to solve the above problems, a visibility improving sheet capable of improving the contrast by shielding outside light and reducing the occurrence of double images should be installed between the light source of the liquid crystal display device and the liquid crystal panel. Has been proposed. As such a visibility improving sheet, sheets having various structures have been proposed. For example, a lens portion having a trapezoidal cross-sectional shape is arranged at a predetermined interval, and a wedge portion between adjacent lens portions is provided with a lens portion. A structure having a light absorbing portion filled with a material having a lower refractive index and a carbon pigment is proposed (for example, Japanese Patent Application Laid-Open No. 2006-85050 and the like: Patent Document 2).

  In JP 2008-146074 (Patent Document 3), the visibility improving sheet is formed by forming the light absorbing portion with a material having a refractive index smaller by 0.01 to 0.5 than the refractive index of the light transmitting portion. Since it is possible to suppress the external light incident on the light from being reflected at the interface between the light transmission part and the light absorption part, it has been proposed that the contrast be improved, as disclosed in JP 2008-158530 A (Patent Document 4). In addition, there has been proposed a visibility improving sheet in which the difference in refractive index between the light transmitting portion and the light absorbing portion is within 0.05.

JP 2006-119365 A JP 2006-85050 A JP 2008-146074 A JP 2008-158530 A

  The inventors of the present invention pay attention to the respective refractive indexes of the binder resin and the colored fine particles constituting the light absorbing portion of the visibility improving sheet, and if the refractive index difference between the binder resin and the colored fine particles is within a predetermined range. Acquired the knowledge that a sheet with improved visibility can be obtained because the external light incident on the light-absorbing part can be suppressed from being diffused or reflected on the surface of the colored fine particles and can effectively absorb the external light. It was. The present invention is based on this finding.

  Therefore, an object of the present invention is to provide a visibility improving sheet that can suppress external light incident on the light absorbing portion from being diffused or reflected on the surface of the colored fine particles, can efficiently absorb external light, and is superior in contrast. There is.

The visibility improving sheet according to the present invention is a visibility improving sheet comprising a light transmitting part arranged in parallel at a predetermined interval, and a light absorbing part provided in parallel between the light transmitting parts,
The light absorbing portion comprises colored fine particles and a binder resin;
A difference in refractive index between the colored fine particles and the binder resin is 0.1 or less.

Further, according to the aspect of the present invention, when the refractive index of the material constituting the light transmitting portion is n ₁ , the refractive index of the binder resin is n ₂ , and the refractive index of the colored resin fine particles is n ₃ , The following formulas (I) and (II):
n ₁ ≧ n ₂ Formula (I)
| N ₂ −n ₃ | ≦ 0.1 Formula (II)
Are preferably satisfied at the same time.

  Moreover, according to the aspect of this invention, it is preferable that the refractive index of the said binder resin is the range of 1.490-1.560.

  According to the aspect of the present invention, it is preferable that the refractive index of the colored fine particles is in the range of 1.490 to 1.590.

  According to the aspect of the present invention, it is preferable that the colored fine particles are made of resin beads in which carbon black is kneaded in a resin.

  Further, according to an aspect of the present invention, the binder resin is made of polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin, polythiol polyene resin, and polyhydric alcohol. It is preferable that it consists of oligomers or prepolymers, such as (meth) allylate of the polyfunctional compound selected.

  Moreover, according to the aspect of the present invention, it is preferable that the resin of the colored fine particles is composed of one or a mixture of two or more selected from an acrylic cross-linked resin, a styrene cross-linked resin, and an acrylic-styrene copolymer resin.

  Moreover, according to the aspect of the present invention, it is preferable that the colored fine particles are included in an amount of 10 to 35% on a mass basis with respect to the binder resin.

  According to another aspect of the present invention, a display device including the visibility improving sheet is also provided.

  According to the present invention, the light absorbing portion of the visibility improving sheet is composed of the colored fine particles and the binder resin, and the difference in refractive index between the two is 0.1 or less, so that the external light incident on the light absorbing portion is colored. Since diffusion or reflection on the surface of the fine particles can be suppressed, and as a result, external light can be efficiently absorbed, a visibility-enhancing sheet with better contrast can be obtained.

It is a schematic sectional drawing of the visibility improvement sheet | seat in one Embodiment of this invention. It is an enlarged view of a section of one direction of a visibility improvement sheet in one embodiment of the present invention. It is the schematic sectional drawing which expanded one pitch of the light transmission part and light absorption part of a visibility improvement sheet. It is the cross-sectional schematic of the display apparatus provided with the visibility improvement sheet | seat by this invention.

  The visibility improving sheet according to the present invention will be described in more detail with reference to the drawings. FIG. 1 is a view showing a cross section in one direction of the visibility improving sheet in the first embodiment of the present invention. As shown in FIG. 1, the visibility improving sheet 1 according to the present invention includes at least a base layer 2 and an optical function sheet layer 3, and the optical function sheet layer 3 is substantially trapezoidal or substantially in a cross section in the layer thickness direction. Light transmitting portions 4 having a rectangular shape are arranged in parallel at a predetermined interval, and light absorbing portions 5 having a substantially triangular or substantially trapezoidal cross section are arranged in parallel between the light transmitting portions 4. .

  The light transmission part 4 is an element having a substantially trapezoidal or substantially rectangular cross section arranged so that one sheet surface side is an upper side and the other sheet surface side is a lower side. Further, the light absorbing portion 5 is an element having a substantially triangular or substantially rectangular cross section formed between the light transmitting portions. The light absorbing portions 5 are arranged in parallel so that the surface corresponding to the base of the substantially triangular shape or the upper side of the substantially rectangular shape faces the sheet surface on the upper side of the light transmitting portion 4. Therefore, one surface of the visibility improving sheet 1 is configured by the upper side of the light absorbing unit 5 and the upper side of the light transmitting unit 4.

  It is preferable that the oblique side of the substantially triangular shape or the long side of the substantially rectangular shape in the light absorbing portion has an angle in the range of 0 to 3 ° with respect to the normal direction of the visibility improving sheet surface. For example, as one embodiment of the present invention, as shown in FIG. 2, a light transmitting portion having a substantially rectangular cross section with a height of 105 μm, an upper side width of 46 μm, and a lower side width of 48 μm, and an upper side (ie, The light-absorbing portion having a substantially rectangular cross section with a width of the groove opening portion of 12 μm and a lower side width of 10 μm can be used as a visibility improving sheet having one pitch. The thickness (height) of the light transmission part and the light absorption part can be approximately 50 to 150 μm. When the angle of the hypotenuse is close to 0 degrees, the cross section is substantially a rectangular shape.

  The base material layer is disposed on the incident side of the image light and is a layer serving as a base for forming a light transmission part and a light absorption part. As the base material layer, a transparent resin film, a transparent resin plate, a transparent resin sheet or transparent glass can be used. Transparent resin films include triacetate cellulose (TAC) film, polyester film such as polyethylene terephthalate (PET), diacetyl cellulose film, acetate butyrate cellulose film, polyethersulfone film, polyacrylic resin film, polyurethane resin film Polyester film, polycarbonate film, polysulfone film, polyether film, polymethylpentene film, polyether ketone film, (meth) acrylonitrile film, etc. can be suitably used. Among these, polyester films are preferably used. . Examples of the polyester film include polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, and polytrimethylene terephthalate.

  As shown in FIG. 1, the light transmission portion 4 is provided on the surface side of the base material layer 2 opposite to the incident side of the image light, and is incident on the base material layer 2 of the visibility improving sheet 1. It has a function of transmitting image light to the viewer side. In the present invention, the light transmitting portion 4 may be provided on the surface side of the base material layer 2 on the image light incident side. The light transmission part 2 can be formed of a transparent resin or the like, but in the present invention, the light transmission part is preferably constituted by a resin having a higher refractive index than the binder resin of the light absorption part described later. . As such a resin, although depending on the binder resin to be used, various thermoplastic resins and ionizing radiation curable resins can be used.

  The thermoplastic resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyester resins such as polyester thermoplastic elastomer, polyethylene resins, polypropylene, polymethylpentene, norbornene resins, polyolefin resins such as cycloolefin resins, cellophane, diacetyl. Cellulose resins such as cellulose, triacetyl cellulose, acetyl cellulose butyrate, etc., vinyl resins such as polyvinyl chloride, polyvinylidene chloride ethylene-vinyl acetate copolymer, poly (meth) acrylate, poly (meth) acrylic acid Acrylic resins such as butyl, methyl (meth) acrylate-methyl (meth) acrylate copolymer, methyl (meth) acrylate-styrene copolymer, polystyrene resin, poly Boneto resins, polyether ether ketone resin, polyether sulfone resin, and polyamide resin or the like, but is not limited thereto.

  When the light transmission part is formed using a transparent thermoplastic resin, polymerization is performed by injecting a thermoplastic resin monomer into the mold, such as a hot press method or an injection molding method in which a heated mold is pressed against the thermoplastic resin. -A light-transmitting portion having a desired shape can be formed by a casting method for solidifying.

  When forming the light transmission part using an ionizing radiation curable resin, the light transmission part having a desired shape is formed by injecting the ionizing radiation curable resin into a mold and irradiating and curing the ionizing radiation. be able to. Among the ionizing radiation curable resins, it is preferable to use an ultraviolet curable resin that can be used and can be applied with a UV method excellent in mass productivity.

  Examples of the ionizing radiation curable resin include a polymerizable prepolymer and / or a polymerizable monomer. The polymerizable prepolymer (also referred to as polymerizable oligomer) includes a radical polymerization type and a cationic polymerization type. Examples of the radical polymerization type polymerizable prepolymer include polyester (meth) acrylates and epoxy (meth) acrylates. System, urethane (meth) acrylate system, polyether (meth) acrylate system, triazine (meth) acrylate system, and the like, but are not limited thereto.

  In addition, a reactive diluent may be added to the ionizing radiation curable resin composition. Examples of such a reactive diluent include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, and methylstyrene. Monofunctional monomers such as N-vinylpyrrolidone as well as polyfunctional monomers may be used. Specifically, dimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, Examples include diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and the like.

  In order to make the ionizing radiation curable resin composition into an ultraviolet curable resin composition, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethylchuram as photopolymerization initiators in the resin composition Monosulfide, thioxanthones, and n-butylamine, triethylamine, poly-n-butylphosphine and the like can be used as a photosensitizer. In particular, in the present invention, it is preferable to mix urethane acrylate as an oligomer and dipentaerythritol hexa (meth) acrylate as a monomer.

  As a curing method of the ionizing radiation curable resin composition, the curing method of the ionizing radiation curable resin composition can be cured by a normal curing method, that is, irradiation with an electron beam or ultraviolet rays.

  For example, in the case of electron beam curing, 50 to 50 emitted from various electron beam accelerators such as a Cockloft Walton type, a bandegraph type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type An electron beam having an energy of 1000 keV, preferably 100 to 300 keV is used. In the case of ultraviolet curing, ultraviolet rays emitted from rays such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. Available.

  As shown in FIG. 1, the light absorbing portion 5 is provided in parallel between the light transmitting portions 4 arranged in parallel at a predetermined interval. The light absorbing portion 5 is colored as shown in FIG. It consists of fine particles 7 and a binder resin 6. 1 and 3 show a form in which the cross-sectional shape of the light absorbing portion is a substantially rectangular shape having two oblique sides on a straight line, but the present invention is not limited to such a form. As long as the light absorbing portion has the above optical function, it may have any shape.

The binder resin preferably has a refractive index that is the same as or smaller than the refractive index of the material constituting the light transmission portion. That is, when the refractive index of the material constituting the light transmission part is n ₁ and the refractive index of the material constituting the light transmission part is n ₂ , the following formula (I):
n ₁ ≧ n ₂ Formula (I)
It is preferable to satisfy this relationship. When the refractive index between the light transmitting part and the light absorbing part is as described above, the image light from the light source incident on the light transmitting part under a predetermined condition is appropriate at the boundary surface between the light absorbing part and the light transmitting part. It is possible to provide a bright image to the observer. Further, since a part of the external light from the observer side is absorbed, the contrast is improved. Further, stray light that is incident on the inside of the light absorbing portion without being reflected at the boundary surface between the light absorbing portion and the light transmitting portion is absorbed by the colored fine particles described later. In addition, since the external light from the observer side incident at a predetermined angle can be appropriately absorbed, the contrast can also be improved.

  As the binder resin, any material that satisfies the above formula (I) may be used. In the present invention, it is preferable to use the ionizing radiation curable resin as described above. . This is because a light absorption part having a desired shape can be easily formed by using an ionizing radiation curable resin. When a plurality of light transmission portions are formed on the base material layer as described above, wedge-shaped or substantially rectangular grooves provided in parallel are formed between the light transmission portions. In the present invention, an ink composition containing a binder resin composed of an ionizing radiation curable resin and colored fine particles is filled in the groove, and the binder resin is cured by irradiation with ionizing radiation. It is because it can form.

It is necessary to select a resin and a binder resin that constitute the light transmission part so as to satisfy the above formula (I). For example, the resin refractive index (n ₁ ) of the light transmission part is 1.540 to 1.560. And a combination in which the refractive index (n ₂ ) of the binder resin is 1.490 to 1.560 can be suitably used. In addition, from the relationship with colored fine particles described later, it is more preferable to use a resin having a refractive index in the range of 1.540 to 1.550 among the above-described resins. As such an ionizing radiation curable resin, , Urethane acrylate, polyester acrylate, epoxy acrylate and the like.

  In the light absorbing portion, the colored fine particles are present in a dispersed state in the binder resin. As described above, the colored fine particles can be dispersed in the binder resin by forming the light absorbing portion using the ink composition containing the ionizing radiation resin composition and the colored fine particles.

  As the colored fine particles, resin beads or glass beads containing a colorant capable of selectively absorbing a specific wavelength in accordance with the characteristics of image light can be suitably used. As the colorant, a material in which a colorant such as a metal salt such as carbon black, graphite, fibrous carbon, black iron oxide, a dye, or a pigment is kneaded can be used. As the colorant, carbon black can be preferably used among those described above.

  The amount of carbon black kneaded into the resin beads is about 0.1 to 0.7 parts by mass, preferably 0.15 to 0.5 parts by mass, more preferably 1 part by mass of the resin beads. Is 0.2 to 0.35 parts by mass. When the amount of kneading of carbon black is more than 0.7 parts by mass, the resin beads may be easily broken. On the other hand, when the amount is less than 0.1 parts by mass, colored fine particles having desired blackness cannot be obtained. There is a case.

  Carbon black having an average particle diameter of 10 to 500 nm can be suitably used. For example, furnace black, acetylene black, channel black, thermal black, carbon nanotube, carbon fiber and the like can be used. Commercially available products can also be used. For example, HCF series, MCF series, RCF series, LFF series (all manufactured by Mitsubishi Chemical Corporation), Vulcan series (made by Cabot Corporation), Ketjen series (Lion Corporation) Can be suitably used. Here, the average particle diameter means an arithmetic average diameter obtained by observing carbon black particles with an electron microscope.

From the viewpoint of easy kneading of the colorant, it is preferable to use resin beads. As the resin beads, substantially spherical beads made of resin can be used. In the present invention, resin beads are selected so that the refractive index difference between the colored fine particles and the binder resin is 0.1 or less. And use. Therefore, although it depends on the kind of the binder resin described above, the refractive index of the resin beads constituting the colored fine particles is preferably in the range of 1.490 to 1.590.
By using the resin beads having the refractive index described above, when the refractive index of the binder resin is n _{2 and} the refractive index of _the colored resin fine particles is n ₃ , the following formula (II):
n ₂ −n ₃ ≦ 0.060 Formula (II)
Will be satisfied. As described above, in the visibility improving sheet according to the present invention, the refractive indexes (n ₁ , n ₂ , n ₃ ) of the light transmitting part, the binder resin of the light absorbing part, and the colored fine particles are respectively the above formulas (I ) And the formula (II) are satisfied, it is possible to suppress the diffusion or reflection of the external light incident on the light absorbing portion at the interface between the binder resin and the colored fine particles, and as a result, the light absorption Since the external light and stray light can be efficiently absorbed by the portion, a visibility improving sheet with more excellent contrast can be obtained.

  As resin beads satisfying the above formula, polystyrene crosslinked resin (refractive index 1.59), urethane crosslinked resin (refractive index 1.55), acrylic crosslinked resin (refractive index 1.49), styrene crosslinked resin (refractive index). 1.547), and beads made of styrene-acrylic copolymer resin (refractive index 1.545) or the like. These resins may be used alone or in combination of two or more. By using two or more types in combination, resin beads having a desired refractive index can be obtained. In particular, the styrene-acrylic copolymer resin is a resin obtained by copolymerizing a styrene monomer, a methyl methacrylate monomer, and a crosslinking agent by a suspension polymerization method, and the blending ratio of the styrene monomer and the methyl methacrylate monomer is adjusted during the copolymerization. By doing so, fine particles made of a resin having a refractive index in the range of 1.49 to 1.59 can be obtained. These resins are preferably transparent, but those colored with pigments or dyes may be used. For example, a colored resin that selectively absorbs a specific wavelength in accordance with the characteristics of image light. There may be.

  The above-mentioned colored fine particles are preferably contained in the binder resin in a range of 15 to 35% with respect to the total mass of the light absorbing portion, and by setting this range, a visibility improving sheet with more excellent contrast is realized. can do. If the content of the colored fine particles is less than 15%, the light-shielding property of the light absorbing portion may be insufficient. If the content of the colored fine particles exceeds 35%, the colored fine particles contact each other in the binder resin. Cracking and chipping problems are likely to occur.

  Further, the colored fine particles preferably have an average particle size of 5 μm or less, and more preferably 3.3 μm or less. If the average particle size of the colored fine particles is larger than 5 μm, the filling ability when forming the light absorbing portion using the ink composition containing the colored fine particles deteriorates, so the bottom portion of the light absorbing portion (light having a substantially trapezoidal cross section). It becomes difficult to uniformly disperse the colored fine particles up to the lower side portion of the absorbing portion. The average particle size can be measured, for example, with a particle size distribution measuring device (LA-920, manufactured by Horiba, Ltd.).

  As shown in FIG. 1, the visibility improving sheet according to the present invention may have only one optical function layer 3, but two or more layers may be stacked and laminated. When two optical functional layers are stacked, the optical functional layers can be laminated via an adhesive or the like, or the optical functional layers can be formed on both surfaces of the base material layer.

  In addition, when two or more optical function layers are stacked, the optical function layers may have different structures. For example, the first optical functional layer and the second optical functional layer can change the width, pitch, depth (wedge shape depth) and shape of the light absorption part, or the direction of the light absorption part in the thickness direction. Or the bias angle of the light absorbing portion with respect to the image light (the inclination angle of the light absorbing portion with respect to the horizontal direction) can be changed. For example, the second layer is designed to cut outside light efficiently and focus on improving the contrast, and the second layer is designed to focus on the front brightness improvement effect using reflection. It is preferable.

  The visibility improvement sheet | seat by this invention may contain the other functional layer employ | adopted as the conventional visibility improvement sheet | seat and the viewing angle expansion member. Specifically, an antireflection layer, an adhesive layer, an electromagnetic wave shielding layer, a wavelength filter layer, an antiglare layer, a hard coat layer, and the like may be appropriately combined. The stacking order and the number of stacks of these functional layers can be appropriately determined according to the use of the visibility improving sheet to be used.

  The visibility improvement sheet | seat by this invention can be used for the display of a display apparatus. For example, the visibility improving sheet can be used as an optical filter for a display device. Examples of the display of the display device include a plasma display panel (PDP), a liquid crystal display panel, an organic EL display, a field emission display (FED), a surface conduction electron-emitting device display (SED), and a projection television.

  Hereinafter, the example which attached the visibility improvement sheet | seat by this invention to the plasma display panel as an optical filter for display apparatuses is demonstrated. FIG. 4 is a schematic cross-sectional view of a display device provided with a visibility improving sheet according to the present invention. The display device 10 shown in FIG. 4 includes the above-described visibility improving sheet 1. That is, the visibility improving sheet 1 includes a base material 2, a light transmission part 4, and a light absorption part 5. The visibility improving sheet 1 is disposed on the image light emitting side of the PDP 12 that is an image source. The visibility improving sheet 1 and the PDP 12 are bonded via an adhesive layer 13. Note that the visibility improving sheet 1 and the PDP 12 are not necessarily bonded. On the front side of the visibility improving sheet 1, an antistatic layer 14, an antireflection layer 15, a hard coat layer 16 and the like are arranged. In the present embodiment, the antistatic layer 14 and the like are disposed on the front surface of the visibility improving sheet 1, but the present invention is not limited thereto, and a layer that blocks electromagnetic waves, infrared rays, or neon lines may be disposed. Good.

Example 1
<Preparation of colored fine particles>
A styrene monomer and a methyl methacrylate monomer are added to a monomer having a mass ratio of 5: 5, and ethylene glycol dimethacrylate as a crosslinking agent is added so that the addition amount is 5% by mass. Resin beads having a rate of 1.545 were obtained. Next, carbon black having an average particle size of 24 nm (RCF # 45, manufactured by Mitsubishi Chemical Corporation) was kneaded into the resin beads so that the resin beads had a ratio of 25% on a weight basis to form colored fine particles. .

<Preparation of ink composition>
As binder resin, urethane acrylate 33.6 parts by mass, epoxy acrylate 14.4 parts by mass, tripropylene glycol diacrylate 28 parts by mass, methoxytriethylene glycol acrylate 4 parts by mass, and Irgacure 184 (product name used as a photopolymerization initiator) ) Was mixed with 4 parts by mass. The refractive index of this binder resin was 1.545. To this composition, the colored fine particles obtained above were added at a ratio of 16 parts by mass with respect to 84 parts by mass of the composition to prepare an ink composition.

<Preparation of a sheet for improving visibility>
On a PET substrate (A4300, manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm, a urethane mold curable resin having a refractive index of 1.55 after curing is subjected to continuous molding using a molding die, and a plurality of light It formed so that a permeation | transmission part might arrange | position in parallel. Next, the wedge-shaped grooves provided in parallel between the light transmitting portions were filled with the ink composition obtained as described above into the wedge-shaped grooves using a die coater. Subsequently, after the excess ink composition was scraped off with a metal doctor blade, the visibility was improved by forming the light absorbing portion by irradiating the ultraviolet ray to cure the ink composition. .

<Contrast evaluation>
Next, the obtained visibility improving sheet was evaluated for contrast by the following evaluation method. First, the luminance of the black screen in a state where the visibility improving sheet was pasted on the display screen and the luminance of the black screen in a state before pasting the visibility improving sheet on the display screen were visually observed. The evaluation criteria for contrast were as follows.
◎: Clearly black ○: Black equal to or better than △: Almost black equal ×: Black equal to or lower

Example 2
In the preparation of the colored fine particles of Example 1, it was visually recognized in the same manner as in Example 1 except that resin beads having a refractive index of 1.49 and a mass ratio of styrene monomer to methyl methacrylate monomer of 1: 9 were used. A property improving sheet was prepared, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), the binder resin (n ₂ ), and the resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.545. , N ₃ = 1.49.

Example 3
In the preparation of the colored fine particles of Example 1, except that resin beads having a refractive index of 1.547 and a mass ratio of styrene monomer to methyl methacrylate monomer of 5.3: 4.7 were used, Example 1 In the same manner, colored fine particles were prepared, and as a binder resin, 35 parts by weight of urethane acrylate, 13 parts by weight of epoxy acrylate, 28 parts by weight of tripropylene glycol diacrylate, 4 parts by weight of methoxytriethylene glycol acrylate, and a photopolymerization initiator A visibility improving sheet was prepared in the same manner as in Example 1 except that Irgacure 184 mixed with 4 parts by mass was used. The refractive indexes of the light transmission part (n ₁ ), binder resin (n ₂ ), and resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.547. , N ₃ = 1.547. Further, the obtained visibility improving sheet was evaluated for contrast in the same manner as described above.

Example 4
The visibility improving sheet is the same as in Example 1 except that the same binder resin as that used in Example 3 is used and the same resin beads as those used in Example 2 are used. And the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), binder resin (n ₂ ), and resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.547. , N ₃ = 1.49.

Example 5
As binder resin used in Example 2, 37 parts by mass of urethane acrylate, 11 parts by mass of epoxy acrylate, 28 parts by mass of tripropylene glycol diacrylate, 4 parts by mass of methoxytriethylene glycol acrylate, and Irgacure 184 as a photopolymerization initiator. A visibility improving sheet was prepared in the same manner as in Example 2 except that a mixture of 4 parts by mass was used, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), the binder resin (n ₂ ), and the resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.55. , N ₃ = 1.49.

Example 6
As binder resin used in Example 2, 48 parts by mass of epoxy acrylate, 28 parts by mass of tripropylene glycol diacrylate, 4 parts by mass of methoxytriethylene glycol acrylate, and 4 parts by mass of Irgacure 184 as a photopolymerization initiator were mixed. A visibility improving sheet was prepared in the same manner as in Example 2 except that the above was used, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), the binder resin (n ₂ ), and the resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.49. , N ₃ = 1.49.

Example 7
The colored fine particles used in Example 6 were visually recognized in the same manner as in Example 6 except that resin beads having a refractive index of 1.59 and a mass ratio of styrene monomer to methyl methacrylate monomer of 9: 1 were used. A property improving sheet was prepared, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), the binder resin (n ₂ ), and the resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.49. , N ₃ = 1.59.

Example 8
On a PET substrate (A4300, manufactured by Toyobo Co., Ltd.) with a thickness of 100 μm, an epoxy ultraviolet curable resin with a refractive index after curing of 1.56 is used for continuous molding with a molding die, and a plurality of light Example except that the light transmission part was formed in the same manner as in Example 1 except that the transmission parts were arranged in parallel, and the same color fine particles used in Example 2 were used. A visibility improving sheet was prepared in the same manner as in No. 1, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), the binder resin (n ₂ ), and the resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.56 and n ₂ = 1.545. , N ₃ = 1.49.

Example 9
On a PET substrate (A4300, manufactured by Toyobo Co., Ltd.) with a thickness of 100 μm, an epoxy ultraviolet curable resin with a refractive index after curing of 1.54 is used for continuous molding with a molding die, and a plurality of light A light transmission part is formed in the same manner as in Example 1 except that the transmission parts are arranged in parallel, and 30 parts by mass of urethane acrylate, 18 parts by mass of epoxy acrylate, and 28% tripropylene glycol diacrylate are used as a binder resin. A visibility improving sheet was prepared in the same manner as in Example 8 except that 4 parts by mass of methoxytriethylene glycol acrylate and 4 parts by mass of Irgacure 184 as a photopolymerization initiator were used. The contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), binder resin (n ₂ ), and resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.54 and n ₂ = 1.54, respectively. , N ₃ = 1.49.

Example 10
As binder resin used in Example 1, 30 parts by weight of urethane acrylate, 18 parts by weight of epoxy acrylate, 28 parts by weight of tripropylene glycol diacrylate, 4 parts by weight of methoxytriethylene glycol acrylate, and Irgacure 184 as a photopolymerization initiator. In the preparation of colored fine particles, a mixture of 4 parts by mass was used except that resin beads having a refractive index of 1.560 and a mass ratio of styrene monomer to methyl methacrylate monomer of 8: 2 were used. A visibility improving sheet was prepared in the same manner as in No. 1, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), binder resin (n ₂ ), and resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.54. , N ₃ = 1.56.

Example 11
On a PET substrate (A4300, manufactured by Toyobo Co., Ltd.) with a thickness of 100 μm, an epoxy ultraviolet curable resin with a refractive index after curing of 1.56 is used for continuous molding with a molding die, and a plurality of light Example except that resin beads having a refractive index of 1.55 and a mass ratio of styrene monomer to methyl methacrylate monomer of 7: 3 were used as colored fine particles, formed so that the transmission portions were arranged in parallel. A visibility improving sheet was prepared in the same manner as in No. 5, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), the binder resin (n ₂ ), and the resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.56 and n ₂ = 1.55. , N ₃ = 1.55.

Comparative Example 1
Example 3 except that resin beads having a refractive index of 1.47 with a mass ratio of styrene monomer and methyl methacrylate monomer of 0.5: 9.5 were used as the colored fine particles used in Example 3. Similarly, a visibility improving sheet was produced, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), binder resin (n ₂ ), and resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.547. , N ₃ = 1.47.

Comparative Example 2
On a PET substrate (A4300, manufactured by Toyobo Co., Ltd.) with a thickness of 100 μm, an epoxy ultraviolet curable resin with a refractive index after curing of 1.54 is used for continuous molding with a molding die, and a plurality of light Except that the transmissive parts are arranged in parallel, a light transmissive part is formed in the same manner as in Example 1, and the same binder resin as that used in Example 5 is used. A visibility improving sheet was prepared in the same manner as in Example 1 except that the same one as used in Example 10 was used, and the contrast was evaluated in the same manner as described above. The refractive indexes of the light transmission part (n ₁ ), binder resin (n ₂ ), and resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.54 and n ₂ = 1.55. , N ₃ = 1.56.

Comparative Example 3
As binder resin used in Example 1, urethane acrylate 36 parts by mass, epoxy acrylate 12 parts by mass, tripropylene glycol diacrylate 28 parts by mass, methoxytriethylene glycol acrylate 4 parts by mass, and Irgacure 184 ( A product for improving visibility was prepared in the same manner as in Example 1 except that 4 parts by mass of the product name used) and polystyrene resin beads having a refractive index of 1.60 were used as the colored fine particles. The contrast was evaluated in the same manner as described above. The results of contrast evaluation were as shown in Table 1. The refractive indexes of the light transmission part (n ₁ ), the binder resin (n ₂ ), and the resin beads (n ₃ ) of the obtained visibility improving sheet are n ₁ = 1.55 and n ₂ = 1.549. , N ₃ = 1.60.

DESCRIPTION OF SYMBOLS 1 Visibility improvement sheet 2 Base material layer 3 Optical function sheet layer 4 Light transmission part 5 Light absorption part 6 Binder resin 7 Colored fine particle

Claims (7)

A visibility improving sheet comprising: a light transmitting portion arranged in parallel at a predetermined interval; and a light absorbing portion provided in parallel between the light transmitting portions,
The light absorbing portion comprises colored resin fine particles and a binder resin;
When the refractive index of the material constituting the light transmission part is n ₁ , the refractive index of the binder resin is n ₂ , and the refractive index of the colored resin fine particles is n ₃ , the following formulas (I) and (II):
0 ≦ n ₁ −n ₂ ≦ 0.005 Formula (I)
0 ≦ n ₂ −n ₃ ≦ 0.060 Formula (II)
Satisfied at the same time,
The visibility improvement sheet | seat characterized by the refractive index of the said colored resin fine particle being the range of 1.410-1.590.   The visibility improvement sheet | seat of Claim 1 whose refractive index of the said binder resin is the range of 1.490-1.560. The visibility improving sheet according to claim 1 or 2 , wherein the colored resin fine particles are made of resin beads in which carbon black is kneaded in a resin. The binder resin is a polyfunctional compound (meth) selected from polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols. The visibility improving sheet according to any one of claims 1 to 3 , comprising an oligomer or prepolymer such as arylate. The visibility improvement sheet | seat of Claim 3 which the resin of the said colored resin fine particle consists of 1 type, or 2 or more types of mixtures selected from acrylic crosslinked resin, styrene crosslinked resin, and acrylic-styrene copolymer resin. The visibility improving sheet according to any one of claims 1 to 5 , wherein the colored resin fine particles are contained in an amount of 10 to 35% on a mass basis with respect to the binder resin. The display apparatus provided with the visibility improvement sheet | seat as described in any one of Claims 1-6 .

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