JP5729637B2 - Manufacturing method of contrast improving sheet - Google Patents

Description

  The present invention relates to a method for producing a contrast enhancing sheet.

  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, it may be difficult to see the screen from people around you. There is a demand for a peeping prevention function for protecting privacy so that it can be seen only by an observer of the 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, Japanese Patent Laid-Open No. 2006-119365 (Patent Document 1) proposes a louver type optical sheet having a structure in which light transmission layers and light shielding layers are alternately arranged. In addition, it is disclosed to use a light shielding layer in which a material constituting the light transmission layer is mixed with a filler such as carbon black or carbon fiber.

  On the other hand, the louver-type optical sheet as described above simply cuts the image light in the oblique direction. Therefore, depending on the type of the 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 reduced.

  In order to solve the above problem, it has been proposed to install a contrast enhancing sheet that can improve the contrast by blocking external light and reduce the occurrence of double images. As such a contrast improving sheet, sheets having various structures have been proposed. For example, a light transmitting portion having a plurality of grooves arranged in parallel on the surface, a material having a refractive index lower than that of the light transmitting portion, and a carbon pigment. Have been proposed (for example, Japanese Patent Application Laid-Open No. 2006-85050, etc .: Patent Document 2).

  Then, in the production of the contrast enhancing sheet, an ink composition in which colored resin beads are mixed with a lens material such as an ionizing radiation curable resin is filled in the groove of the light transmitting portion, and is cured by irradiating with ionizing radiation. (For example, International Patent Application Publication No. WO2006 / 090784: Patent Document 3).

  The ink composition is filled, for example, while the doctor blade is fixed, while the sheet-shaped light transmitting portion having a plurality of grooves arranged in parallel on the surface is moved, and the ink composition is transmitted through the upstream side of the doctor blade. The ink composition is supplied to the surface of the portion, and the ink composition on the surface of the light transmitting portion is scraped off with the doctor blade while forming an ink reservoir upstream of the doctor blade and in the immediate vicinity of the doctor blade.

  However, when the ink composition is filled by such a method, strip-shaped filling unevenness, streaks, and the like are likely to occur. Since the appearance quality of the contrast enhancing sheet is directly related to the image quality, high quality is required. For this reason, it is preferable to reduce the above-mentioned filling unevenness and streak defect as much as possible.

JP 2006-119365 A JP 2006-85050 A International Application Publication WO2006 / 090784

  The present invention has been made to solve the above problems. That is, it aims at providing the manufacturing method of the contrast improvement sheet | seat which can reduce a stripe defect and filling nonuniformity.

  As a result of intensive research to reduce filling unevenness and streak defects, the inventors reduced filling unevenness and streak defects when the increase in viscosity and viscosity unevenness of the ink composition constituting the ink reservoir were suppressed. I found out that The present invention has been completed based on such findings.

  According to one aspect of the present invention, there is provided a method for manufacturing a contrast-enhancement sheet, comprising: a light transmission part having a plurality of grooves arranged in parallel on a surface; and a light absorption part formed in the groove of the light transmission part. The ink composition is continuously supplied to the surface of the light transmission part while moving the sheet-like light transmission part in which a plurality of grooves are arranged in parallel on the surface, from the supply position of the ink composition The ink composition on the surface of the light transmitting portion is formed by the scraping member while forming an ink reservoir containing the ink composition on the upstream side of the scraping member disposed on the downstream side and in the immediate vicinity of the scraping member. A method for producing a contrast-enhancing sheet, wherein a part of the ink composition constituting the ink reservoir is sucked and supplied to the surface of the light transmitting portion again. Provided.

  According to the method for producing a contrast-enhancing sheet of one aspect of the present invention, an ink reservoir is formed by sucking a part of the ink composition that constitutes the ink reservoir while continuously supplying the ink composition. An increase in viscosity and viscosity unevenness of the ink composition can be suppressed, whereby filling unevenness and streak defects can be reduced. Further, by sucking a part of the ink composition constituting the ink reservoir, it is possible to suppress the retention of the ink reservoir, thereby extending the life of the ink composition.

It is the figure which showed typically the manufacturing process of the contrast improvement sheet | seat which concerns on embodiment. It is the figure which showed typically the formation process of the light transmissive part which concerns on embodiment. It is the figure which showed the base material which has the adhesion layer and peeling layer which concern on embodiment. It is the figure which showed typically the filling process of the ink composition which concerns on embodiment. It is sectional drawing of the scraping part which concerns on embodiment. It is a side view of the scraping part which concerns on embodiment. It is the figure which showed typically the mode of scraping by the scraping member which concerns on embodiment. It is sectional drawing of the display apparatus provided with the contrast improvement sheet | seat which concerns on embodiment.

<Method for producing contrast improving sheet>
First, a method for producing a contrast enhancing sheet according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically illustrating a manufacturing process of a contrast improving sheet according to the present embodiment, and FIG. 2 is a diagram schematically illustrating a process of forming a light transmission portion according to the present embodiment. These are the figures which showed the base material which has the adhesion layer and peeling layer which concern on this embodiment.

  First, the light transmission part 2 in which a plurality of grooves 2a are arranged in parallel in the cross section in the layer thickness direction is formed on the substrate 1 (FIG. 1A). The groove 2a shown in FIG. 1A has a substantially trapezoidal shape that tapers toward the substrate 1 side. The groove 2a is not limited to a substantially trapezoidal shape, and may be formed in, for example, a substantially V shape or a substantially rectangular shape. The groove 2 a extends along the longitudinal direction of the substrate 1.

  The base material 1 is a layer serving as a base for forming the light transmission part 2 and a light absorption part 4 described later. As the substrate 1, 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.

  The formation of the light transmitting portion 2 varies depending on the type of resin used. For example, when the light transmission part 2 is formed using a transparent thermoplastic resin, a hot press method or an injection molding method for pressing a heated mold against the thermoplastic resin, or a thermoplastic resin monomer is injected into the mold Then, the light transmitting portion 2 can be formed by a casting method for polymerization and solidification. In the case of using an ionizing radiation curable resin, particularly an ultraviolet curable resin, the light transmitting part 2 is formed by a so-called UV method in which the resin is injected into a mold and irradiated with ultraviolet rays to be cured. Can do. Among these methods, in the present invention, the UV method excellent in mass productivity can be suitably used. According to the UV method, the light transmission part 2 can be continuously manufactured using a mold roll.

  Specifically, for example, as shown in FIG. 2, the base material 1 is fed between a mold roll 10 having a groove corresponding to the shape of the light transmission part 2 and a nip roll 11 at a predetermined pitch. The arrow in FIG. 1 represents the direction in which the base material 1 is fed. In accordance with the feeding of the base material 1, droplets of the light transmission part forming composition 13 containing, for example, an ultraviolet curable resin or the like are continuously supplied from the supply part 12 between the mold roll 10 and the base material 1. When supplying the light transmissive part forming composition 13 from the supply unit 12 onto the base material 1, the composition reservoir 14 in which the light transmissive part forming composition 13 is accumulated between the mold roll 10 and the base material 1. To be formed. By forming the composition reservoir 14, the light transmitting portion forming composition 13 spreads in the width direction of the substrate 1.

  The composition 13 for forming a light transmitting portion supplied between the mold roll 10 and the base material 1 as described above is formed by the pressing force between the mold roll 10 and the nip roll 11. It is filled between the molds 10. Thereafter, the light transmitting portion forming composition 13 is irradiated with ultraviolet rays by the ionizing radiation irradiation device 15 to cure the light transmitting portion forming composition 13 to form the light transmitting portion 2. After forming the light transmission part 2, the light transmission part 2 is peeled off from the mold roll 10 through the peeling roll 16.

  The base material 1 fed into the mold roll 10 may include an adhesive layer 6 and a release layer 7 as shown in FIG. The adhesive layer 6 is for adhering the contrast enhancing sheet to the display unit of the display device. The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 6 is not particularly limited as long as it can transmit light and appropriately adhere another optical sheet. As an adhesive, an acrylic copolymer can be mentioned, for example.

  The release layer 7 is for preventing the adhesive layer 6 from coming into contact with others during handling, and is formed on the adhesive layer 6. Although it does not specifically limit as the peeling layer 7, For example, a polyethylene terephthalate (PET) resin etc. are mentioned.

  In addition, it is preferable that the surface of the groove | channel 2a of the light transmissive part 2 is hydrophilized before the filling process of the next ink composition. By performing the hydrophilic treatment on the surface of the groove 2a, it becomes easier to fill the groove 2a with the ink composition, and the ink filling rate is improved. The hydrophilization treatment can be performed using a conventionally known method. Examples thereof include dry processes such as low-pressure plasma treatment, atmospheric pressure plasma treatment, corona treatment, ultraviolet irradiation treatment, and excimer lamp treatment, and wet processes such as alkali treatment with sodium hydroxide, potassium hydroxide, ethanolamine, and the like. Among these, atmospheric pressure plasma treatment is preferable from the viewpoint of production efficiency.

  After the light transmission part 2 is formed on the substrate 1, the ink composition 3 is filled in the groove 2a (FIG. 1B). FIG. 4 is a diagram schematically illustrating a filling process of the ink composition according to the present embodiment, FIG. 5 is a cross-sectional view of a scraping portion according to the present embodiment, and FIG. 6 is a scratch according to the present embodiment. FIG. 7 is a side view of the take part, and FIG. 7 is a view schematically showing a state of scraping by the scraping member according to the present embodiment. In addition, the arrow A in FIG. 4 represents the moving direction of a light transmissive part, and the arrow B represents the circulation direction of an ink composition.

  First, a filling device for filling the ink composition 3 in the groove 2a will be described. As shown in FIG. 4, the filling apparatus mainly includes a supply unit 30, a scraping unit 40, an ink circulation system 50, and a transport system (not shown).

  The supply unit 30 is for supplying the ink composition 3 to the surface 2 b of the light transmission unit 2. It is preferable that the supply part 30 can supply the ink composition 3 uniformly in the width direction of the light transmission part 2.

  Examples of the supply unit 30 include a die coater, a bar coater, a roll coater, and a knife coater. Among these, the ink composition 3 is uniformly applied to the surface 2b of the light transmission unit 2 in the width direction of the light transmission unit 2. A die coater that can be supplied is preferred.

  The scraping unit 40 is for scraping the ink composition 3 supplied onto the surface 2b of the light transmitting unit 2. The scraping section 40 is a scraping member 41 that actually scrapes the ink composition 3 supplied to the surface 2b of the light transmitting section 2, a holder 42 that holds the scraping member 41, and the rigidity of the scraping member 41. The contact plate 43 to be raised is provided.

  The scraping member 41 is disposed downstream of the supply position of the ink composition 3 by the supply unit 30. That is, for example, the scraping member 41 is disposed downstream of the supply unit 30. Further, the scraping member 41 is disposed so as to be orthogonal to the extending direction of the groove 2a.

  The scraping member 41 is a thin plate, and the thickness of the scraping member 41 can be about 200 μm. For example, a doctor blade or the like can be used as the scraping member 41. The scraping member 41 may be composed of at least one scraping member, but is preferably composed of two scraping members. In the present embodiment, as shown in FIG. 5, the scraping member 41 is positioned downstream of the first scraping member 41 with respect to the moving direction of the first scraping member 44 and the light transmitting portion 2. The example comprised from the 2nd scraping member 45 to perform is demonstrated.

The first scraping member 44 and the second scraping member 45 are configured such that the tip 45a of the second scraping member 45 is 0.3 mm or more larger than the tip 44a of the first scraping member 44 for the following reason. The tip 44a of the first scraping member 44 is in contact with the surface 2b of the light transmitting portion 2 and the tip 45a of the second scraping member 45 is set to the light transmitting portion in a state set to protrude less than 5 mm. 2 is preferably arranged so as not to contact the surface 2b. Here, the fact that the tip 45a of the second scraping member 45 protrudes by 0.3 mm or more and less than 0.5 mm from the tip 44a of the first scraping member 44 is the length L ₁ shown in FIG. Is 0.3 mm or more and less than 0.5 mm.

  For example, the tip 45a of the second scraping member 45 is set to protrude 0.5 mm or more from the tip 44a of the first scraping member 44, and the tip 44a of the first scraping member 44 is the light transmitting portion. The first scraping member 44 and the second scraping member 45 are arranged so that the tip 45a of the second scraping member 45 is in contact with the surface 2b of the light transmitting portion 2 without contacting the surface 2b of the second. Then, the ink composition 3 stays in or clogs in the gap between the first scraping member 44 and the surface 2b of the light transmission part 2, and the density unevenness of the ink composition 3 is thereby formed. There is a possibility that a streak defect may occur in the light absorbing portion 4 described later.

  Further, the tip 45a of the second scraping member 45 is set so as to protrude less than 0.3 mm from the tip 44a of the first scraping member 44, and the tip 44a of the first scraping member 44 is the light transmitting portion. When the first scraping member 44 and the second scraping member 45 are arranged such that the tip 45a of the second scraping member 45 is not in contact with the surface 2b of the light transmission part 2 The scraping property by the second scraping member 45 is inferior, and the phenomenon that the ink composition 3 remains on the light transmitting portion 2 (black stripe defect) may occur.

  Furthermore, even when the tip 45a of the second scraping member 45 is set to protrude 0.3 mm or more and less than 0.5 mm from the tip 44a of the first scraping member 44, the first scraping member The first scraping member 44 and the second scraping member 44 are in contact with the surface 2b of the light transmitting part 2 and the tip 45a of the second scraping member 45 is in contact with the surface 2b of the light transmitting part 2. If the scraping member 45 is disposed, the first scraping member 44 is pushed into the surface 2b of the light transmitting portion 2, so that the scraping property by the second scraping member 45 is inferior and black streaks are poor. May occur.

  In contrast, in the first scraping member 44 and the second scraping member 45, the tip 45a of the second scraping member 45 is 0.3 mm or more than the tip 44a of the first scraping member 44. The tip 44a of the first scraping member 44 is in contact with the surface 2b of the light transmitting portion 2 while the tip 45a of the second scraping member 45 is in the light transmitting portion in a state set to protrude less than 5 mm. 2, the ink composition 3 is not retained or clogged in the gap between the first scraping member 44 and the surface 2 b of the light transmitting portion 2. Further, since the scraping property by the second scraping member 45 is improved, it is possible to suppress the occurrence of both the stripe defect and the black stripe defect.

  The distance d between the first scraping member 44 and the second scraping member 45 shown in FIG. 5 is preferably 0.05 to 2 mm. This numerical range is preferable because if the distance d is less than 0.05 mm, the first scraping member 44 and the second scraping member 45 overlap, and the ink composition 3 is scraped off. May be insufficient. If the distance d exceeds 2 mm, the ink composition 3 is clogged between the first scraping member 44 and the second scraping member 45, which may cause streaks.

  The angles α and β of the first scraping member 44 and the second scraping member 45 with respect to the surface 2b of the light transmitting portion 2 shown in FIG. 5 are preferably 40 ° or more and 70 ° or less, and 50 to 65. More preferably. The reason why this numerical range is preferable is that if the angles α and β are less than 40 °, the ink composition 3 may be insufficiently scraped, and the angles α and β may be 70 °. If it exceeds, the scraping efficiency by the first scraping member 44 and the second scraping member 45 is improved, but the first scraping member 44 and the second scraping member 45 in contact with the ink composition 3 are improved. This is because, since the area is small, black stripe defects may occur.

  The contact plate 43 is in contact with the second scraping member 45 and is disposed between the second scraping member 45 and the holder 42. The contact plate 43 only needs to be made of a material capable of increasing the rigidity of the second scraping member 45, and can be made of stainless steel having a thickness of 600 μm, for example.

The contact plate 43 is preferably arranged so that the protruding amount of the second scraping member 45 is 1 to 10 mm, and more preferably 3 to 7 mm. The “protruding amount” is the length in the vertical direction of the portion of the second scraping member 45 not covered by the contact plate 43, that is, the second scraping member from the lower end of the contact plate 43 shown in FIG. up to 45 of the tip 45a means the length _{L 2.}

  As shown in FIGS. 4 and 6, the holder 42 is provided at both the holding portion 46 that holds the scraping member 41 and both end portions 46 a in the width direction of the holding portion 46, and the end portion 46 a of the holding portion 46. And a weir portion 47 protruding upstream. The weir portion 47 is for holding an ink reservoir 3a described later. By providing the weir portion 47, the ink reservoir 3a can be efficiently held.

  The weir portion 47 has a suction hole 47a for sucking a part of the ink composition 3 constituting the ink reservoir 3a. The diameter of the suction hole 47a is preferably 10 to 16 mm. The reason why this numerical range is preferable is that if the diameter is less than 10 mm, it takes a long time to suck the ink composition 3. If the diameter exceeds 16 mm, the ink composition is excessively excessive. This is because the object 3 is sucked.

  The suction hole 47a is formed on either the bottom surface 47b or the side surface of the dam portion 47. However, in consideration of the liquid level stability of the ink reservoir 3a, the suction hole 47a is preferably formed on the bottom surface 47b of the dam portion 47. In FIG. 6, the suction hole 47a is formed from the bottom surface 47b of the dam portion 47 to the outer side surface 47c of the dam portion 47, and the ink composition 3 sucked from the bottom surface 47b side is discharged from the outer side surface 47c. It has become. Further, as shown in FIG. 6, when the suction hole 47 a is formed in the bottom surface 47 b of the dam portion 47, the dam portion 47 can suck the ink composition 3 so that the bottom surface 47 b of the dam portion 42 can be sucked. It is preferable that the gap is disposed between the surface of the light transmitting portion 2 and the surface 2b of the light transmitting portion 2 so as to have a slight gap.

  The ink circulation system 50 shown in FIG. 4 is connected to the suction hole 47a. The ink circulation system 50 includes a cleaner 51 such as an air suction cleaner, pumps 52 and 53 such as a diaphragm pump, a mixing tank 54, an unused ink composition storage tank 55, a filter 56, and the like.

  The cleaner 51 is for sucking the ink composition 3 and is disposed in front of the pump 52. The pump 52 is for conveying the ink composition 3 in the cleaner 51 and sending it to the mixing tank 54. The mixing tank 54 is for mixing the collected used ink composition 3 and the unused ink composition 3 stored in the unused ink composition storage tank 55.

  In the mixing tank 54, it is preferable that the used ink composition 3 and the unused ink composition 3 are mixed so that the mixing ratio is 1: 4 to 4: 1. Further, in the mixing tank 54, the viscosity of the ink composition 3 is adjusted so that the viscosity of the ink composition 3 after mixing is preferably 2500 to 5000 mPa · s, and more preferably 3000 to 4000 mPa · s. Is done. This numerical range is preferable because if the viscosity of the ink composition 3 is less than 2500 mPa · s, it may be difficult to fill the groove with the ink composition 3, and the viscosity of the ink composition 3 may be If it exceeds 5000 mPa · s, it may be difficult to suck the ink composition 3. In addition, the viscosity of an ink composition shall mean the value measured in 25 degreeC environment using the B-type viscosity meter.

  The pump 53 is for sending the mixed ink composition 3 in the mixing tank 54 to the supply unit 30, and the filter 56 is interposed between the pump 53 and the supply unit 30. A conveyance system is for conveying the light transmission part 2, and is comprised from the conveyance roll etc., for example.

  Next, the ink composition 3 will be described. The ink composition 3 includes a transparent ionizing radiation resin composition and light absorbing particles. As the ionizing radiation curable resin composition, an ionizing radiation curable resin composition used for a conventionally known visibility improving sheet or viewing angle improving sheet can be used. For example, those having an acrylate functional group can be suitably used. Specifically, polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetals having a relatively low molecular weight can be used. Examples thereof include oligomers or prepolymers such as (meth) allylates of polyfunctional compounds such as resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols. Although depending on the material constituting the light transmitting portion of the visibility improving sheet, a resin having a refractive index smaller than that of the material constituting the light transmitting portion may be selected from these resins.

  In addition, a reactive diluent may be added to the resin composition. Examples of such a reactive diluent include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N- Monofunctional monomers such as vinyl pyrrolidone and polyfunctional monomers may be used. Specifically, dimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di ( Examples include 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 convert the ionizing radiation curable resin composition into an ultraviolet curable resin composition, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethylchuram mono as a photopolymerization initiator in the composition. A mixture of sulfides, thioxanthones, n-butylamine, triethylamine, poly-n-butylphosphine, or the like as a photosensitizer can be used. 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 the light absorbing particles, resin beads or glass beads may be light absorbing particles that can selectively absorb a specific wavelength according to the characteristics of the image light. Carbon black, graphite, fibrous carbon, black oxidation What knead | mixed colorants, such as metal salts, such as iron, dye, and a pigment, can be used. From the viewpoint of easy kneading of the colorant, it is preferable to use resin beads. As the resin beads, melamine beads, acrylic beads, acrylic-styrene beads, polycarbonate beads, polyethylene beads, polystyrene beads, polyvinyl chloride beads and the like can be suitably used. Further, urethane cross-linked fine particles and silicon-based beads can also be suitably used. These resin beads are preferably those having a refractive index difference of about 0.1 of the ionizing radiation curable resin composition described above. Also, as the resin before kneading the colorant, a transparent resin can be used, but it is preferable to use a resin colored with a pigment or a dye, and a specific wavelength is selectively selected according to the characteristics of the image light. However, resin beads colored in black are preferably used.

  Among the above-mentioned materials, carbon black can be preferably used as the colorant. 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, light absorbing particles having desired blackness can be obtained. There may not be. 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.

  In order to improve the dispersibility of the light absorbing particles in the ionizing radiation curable resin composition, the light absorbing particles may be surface-treated. Examples of the surface treatment include hydrophilic treatment with a conventionally known silica coating and surface modification with plasma or the like.

  The ink composition 3 containing each component described above is prepared by mixing a predetermined amount of light-absorbing particles into an ionizing radiation curable resin composition and adding a polymerization initiator or the like as desired. The addition amount of the light absorbing particles is preferably in the range of 15 to 35% with respect to the total mass of the ink composition. By setting this range, it is possible to realize a contrast-enhancement sheet with more excellent contrast. If the light-absorbing particle content is too small, the light-shielding property of the light-absorbing part may be insufficient. If the light-absorbing particle content is too large, the resin beads may come into contact with each other, causing problems such as cracking and chipping. It tends to occur.

  Using such a filling device and the ink composition 3, the ink composition 3 is filled into the groove 2 a of the light transmitting portion 2.

  Specifically, first, as shown in FIG. 4, the light transmission unit 2 is moved while moving the sheet-like light transmission unit 2 together with the base material 1 by the transport system with respect to the supply unit 30 and the scraping unit 40. The ink composition 3 is continuously supplied from the supply unit 30 to the surface 2b of the ink, and the ink composition 3 on the surface 2b of the light transmission unit 2 is scraped off by the scraping unit 40 located downstream of the supply unit 30. Thereby, the ink composition 3 is filled in the groove 2a, and the excess ink composition 3 present on the surface 2b of the light transmitting portion 2 is scraped off.

  Here, as shown in FIG. 7, the ink composition 3 is supplied by forming an ink reservoir 3 a containing the ink composition on the upstream side of the first scraping member 44 and in the immediate vicinity of the first scraping member 44. To be done. Specifically, the ink reservoir 3 a is formed by supplying the ink composition 3 from the supply unit 30 to the surface 2 b of the light transmission unit 2 relatively excessively. The arrow shown in FIG. 7 represents the moving direction of the light transmission part 2.

  Further, while supplying the ink composition 3 from the supply unit 30 and scraping off the ink composition 3 by the scraping unit 40, a part of the ink composition 3 constituting the ink reservoir 3 a is sucked into the suction hole of the weir unit 47. Suction is performed by the pump 52 through 47a. The used ink composition 3 sucked from the suction holes 47 a of the weir part 47 is sent to the mixing tank 54 by the pump 52.

  The used ink composition 3 sent to the mixing tank 54 is mixed with the unused ink composition 3 in the mixing tank 54, and then sent to the supply unit 30 via the filter 56 by the pump 53. And it is again supplied to the surface 2b of the light transmission part 2 from the supply part 30. FIG.

  After filling the groove 2a with the ink composition 3, the ink composition 3 in the groove 2a is cured by irradiating ionizing radiation to form a light absorbing portion 4 having a substantially trapezoidal cross-sectional shape (FIG. 1). c)). Thereby, the contrast improvement sheet | seat 5 is produced. The ink composition 3 can be cured by a normal curing method, that is, by 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.

  When an ink reservoir is formed, the viscosity of the ink composition constituting the ink reservoir increases with time, or viscosity unevenness occurs in the ink reservoir, which may contribute to uneven filling and streak defects. . In contrast, according to the present embodiment, a part of the ink composition 3 constituting the ink reservoir 3a is sucked while continuously supplying the ink composition 3, so that the ink composition constituting the ink reservoir 3a is sucked. No. 3 viscosity increase and viscosity unevenness can be suppressed. Thereby, filling irregularities and streak defects can be reduced.

  The increase in viscosity of the ink composition constituting the ink reservoir causes a shortened life of the ink composition, but according to the present embodiment, since a part of the ink composition 3 constituting the ink reservoir 3a is sucked, The increase in viscosity of the ink composition 3 can be suppressed, and the life of the ink composition 3 can be extended.

<Contrast improvement sheet>
The contrast improving sheet 5 obtained as described above includes a base material 1, a light transmitting portion 2 formed on the base material 1 and having a plurality of grooves 2a, and a light absorbing portion formed in the grooves 2a. 4 is provided.

  The light absorption unit 4 has a refractive index that is the same as or smaller than the refractive index of the light transmission unit 2. Since the refractive indexes of the light transmission part 2 and the light absorption part 4 are as described above, the image light from the light source incident on the light transmission part 2 under a predetermined condition is transmitted to the light absorption part 4 and the light transmission part 2. It is possible to provide a bright image to the observer by appropriately reflecting at the boundary surface. 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 inner side of the light absorbing unit 4 without being reflected at the boundary surface between the light transmitting unit 2 and the light absorbing unit 4 is absorbed by the light absorbing material in the light absorbing unit 4. 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.

  In addition, two layers of contrast enhancing sheets may be superposed, and in this case, each contrast enhancing sheet may have a different structure. For example, the width, pitch, depth, and shape of the light absorbing portion can be changed between the first layer contrast improving sheet and the second layer contrast improving sheet, or the direction of the light absorbing portion in the thickness direction can be changed. It is possible to change the bias angle of the light absorbing portion with respect to (the inclination angle of the light absorbing portion with respect to the horizontal direction). Moreover, the material (the kind of resin and the density | concentration of a light absorption particle) which forms a light absorption part can also be changed. For example, the second layer is designed to cut external light efficiently and emphasize the improvement of contrast, and the second layer is designed to focus on the front brightness improvement effect using reflection, and the effect is changed in each layer. It is preferable.

  The contrast enhancing sheet according to the present invention may include other functional layers employed in conventional optical sheets and viewing angle widening members. 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 order of stacking and the number of stacks of these functional layers can be appropriately determined according to the application.

  The contrast improving sheet according to the present invention can be disposed on a display unit of a display device, for example. Specifically, the contrast improving sheet can be used as an optical filter for a display device, for example. Examples of the display unit of the display device include a plasma display, a liquid crystal display, an organic EL display, a field emission display (FED), a surface conduction electron-emitting device display (SED), and a projection television.

<Optical filter for display device and display device>
Hereinafter, an example in which the contrast improving sheet according to the present invention is attached to a display unit of a display device as an optical filter for the display device will be described. FIG. 8 is a cross-sectional view of a display device provided with a contrast enhancing sheet according to the present embodiment. The display device 60 shown in FIG. 8 includes the contrast enhancing sheet 5 manufactured by the manufacturing method described above. The contrast improving sheet 5 is attached to the display unit 61 of the display device 60 via the adhesive layer 62 so that the base 1 is on the video light source side. On the front side of the contrast improving sheet 5, an antistatic layer 63, an antireflection layer 64, an antiglare layer 65, and the like are disposed. In the present embodiment, the antistatic layer 63 and the like are disposed on the front surface of the contrast enhancing sheet 5, but the present invention is not limited thereto, and a layer that blocks electromagnetic waves, infrared rays, or neon lines may be disposed. .

  Hereinafter, the present invention will be specifically described with reference to examples. In this example, a contrast improving sheet was produced by the same method as in the above embodiment, and the appearance of the contrast improving sheet was observed.

Example <Preparation of Ink Composition>
As photocurable prepolymer, epoxy acrylate oligomer Oxirane, 2,2 '-[(1-methylethylidene) bis (4,1-phenyleneoxymethylene)] bis-, homopolymer, 2-propenoate, 20.0 parts by mass and reactive dilution monomer 20.0 parts by mass of 2-phenoxyethyl acrylate, 20.0 parts by mass of α-acryloyl-ω-phenoxypoly (oxyethylene), and 2- {2- [2- (acryloyloxy) (methyl) ethoxy] Acrylic crosslinked fine particles (manufactured by Ganz Kasei Co., Ltd.) 20.0 containing 13.0 parts by weight of (methyl) ethoxy} (methyl) ethyl acrylate and 25% carbon black having an average particle size of 4.0 μm as light absorbing particles 1 part by weight and 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, Ciba Specialty Chemicals Co., Ltd.) 7 parts by mass) (made by a formula company) were mixed and homogenized to obtain an ink composition.

  The viscosity of this ink composition at 25 ° C. was 4000 mPa · s. In the present invention, the viscosity was measured based on the rotational viscometer method of JIS K-5400. Specifically, a BL type viscometer manufactured by Tokyo Keiki Co., Ltd. Using a 4-rotor, the value indicated by the viscometer at 12 rpm and 1 minute at 25 ° C. was measured, and a value obtained by multiplying the measured value indicated by the viscometer by a conversion multiplier (500 in this condition) was defined as the viscosity.

In addition, the composition of the ink composition excluding the light-absorbing particles was applied at a thickness of 10 μm, cured by irradiating with 800 mJ / cm ² of ultraviolet light with a high-pressure mercury lamp, and a multiwavelength Abbe refractometer DR-M4 (stock The refractive index of 589 nm was measured using a product of Atago Co., Ltd. and found to be 1.547.

<Adjustment of composition for forming light transmitting portion>
Bisphenol A-ethylene oxide 2 mol adduct 41 parts by mass, isophorone diisocyanate 14.0 parts by mass, and bismuth tri (2-ethylhexanoate) (2-ethylhexanoic acid 50% solution)) 0.02 mass as urethanization catalyst The urethane acrylate oligomer obtained by adding 5 parts by mass of 2-hydroxyethyl acrylate and reacting at 80 ° C. for 5 hours was used as a photocurable prepolymer. . This urethane acrylate oligomer 32, 0 parts by mass, 10.0 parts by mass of phenoxyethyl acrylate (molecular weight 192) as a photocurable monomer, and 30.0 masses of diacrylate (molecular weight 512) of EO4 mol adduct of bisphenol A And 0.03 parts by mass of a tetradecanol-ethylene oxide 10-mole adduct as a mold release agent (monoester / diester = molar ratio 1/1), and a tearylamine ethylene oxide 15-mole adduct 02 parts by mass, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator, mixed and homogenized to form a light transmission part Got.

The composition for forming a light transmission part was applied at a thickness of 100 μm, and the light transmission part constituent composition was cured by irradiating with 800 mJ / cm ² of ultraviolet light from a high-pressure mercury lamp, and the multiwavelength Abbe refractometer DR-M4 The refractive index of 589 nm was measured using (manufactured by Atago Co., Ltd.) and found to be 1.550.

<Preparation of contrast improving sheet>
The composition for forming a light transmission part is supplied onto a polyethylene terephthalate substrate (Toyobo Co., Ltd., A4300, 100 μm), the composition for light transmission part formation is cured, and a plurality of grooves are arranged in parallel on the surface. The light transmission part thus formed was formed.

  Next, while moving the light transmitting part for each substrate, the ink composition obtained above is continuously supplied from the die head of the die coater to the surface of the light transmitting part so as to be uniformly supplied in the width direction of the light transmitting part. After that, the ink composition on the surface of the light transmission part was scraped off using a metal doctor blade as a scraping member.

  The ink composition was supplied so that an ink reservoir was formed on the upstream side of the doctor blade and in the immediate vicinity of the doctor blade. In addition, while supplying the ink composition from the die head and scraping the ink composition with a doctor blade, a part of the ink composition constituting the ink reservoir was sucked with an air suction cleaner. The used ink composition thus sucked was sent to a mixing tank by a pump and mixed with an unused ink composition in the mixing tank. Then, the mixed ink composition was sent to the die head through a filter by a pump, and again supplied from the die head to the surface of the light transmitting portion.

  After filling the groove of the light transmitting portion with the ink composition, the ink composition was irradiated with ultraviolet rays to cure the ink composition, thereby forming the light absorbing portion, and the contrast improving sheet of Example 1 was produced. .

Comparative Example First, in the same manner as in Example 1, the composition for forming a light transmission part of Example 1 was supplied onto a polyethylene terephthalate substrate (Toyobo Co., Ltd., A4300, 100 μm), and the composition for light transmission part formation was supplied. Was cured to form a light transmission part having a plurality of grooves arranged in parallel on the surface.

  Next, while moving the light transmission part, the ink composition obtained above is supplied to the surface of the light transmission part from one nozzle arranged in the vicinity of the center part of the light transmission part. The ink composition on the surface of the light transmitting portion was scraped off using a doctor blade.

  The ink composition was supplied from the nozzle so that an ink reservoir was formed on the upstream side of the doctor blade and in the immediate vicinity of the doctor blade, but without being continuously supplied from the nozzle, the ink reservoir started to disappear. The ink composition was supplied again. Further, the ink composition constituting the ink reservoir was not sucked.

  After filling the ink composition in the groove of the light transmitting part, the ink composition was irradiated with ultraviolet rays to cure the ink composition, thereby forming a light absorbing part, and a contrast improving sheet of a comparative example was produced.

Appearance Observation When the appearances of the contrast improving sheets of Examples and Comparative Examples produced in this way were observed, filling unevenness and streak defects were observed on the contrast improving sheets of the Comparative Examples. On the other hand, in the contrast improving sheets of the examples, no filling unevenness and streak defects were observed, and it was in a good state.

  From these results, it was confirmed that when a part of the ink composition constituting the ink reservoir was sucked while continuously supplying the ink composition, filling unevenness and streaks could be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Light transmission part, 2a ... Groove, 2b ... Surface, 3 ... Ink composition, 3a ... Ink reservoir, 4 ... Light absorption part, 5 ... Contrast improvement sheet, 30 ... Supply part, 40 ... Scratch Picking part 41 ... Scraping member 42 ... Holder 43 ... Plate plate 44 ... First scraping member 44a ... Tip, 45 ... Second scraping member 45a ... Tip 46, Holding part 46a ... end, 47 ... weir, 47a ... suction hole, 50 ... ink circulation system, 60 ... display device.

Claims (3)

A method for producing a sheet, comprising: a light transmission part having a plurality of grooves arranged in parallel on a surface; and a light absorption part formed in the groove of the light transmission part,
An ink composition is continuously supplied to the surface of the light transmitting portion while moving a sheet-like light transmitting portion having a plurality of grooves arranged on the surface, and downstream of the ink composition supply position. The ink composition on the surface of the light transmitting portion is formed by the scraping member while forming an ink reservoir containing the ink composition on the upstream side of the scraping member disposed on the surface and in contact with the scraping member. With a scraping process,
The scraping member holds the ink reservoir that is provided at a holding portion that holds the scraping member and at both ends in the width direction of the holding portion and protrudes upstream from the both ends of the holding portion. Is held by a holder provided with a weir portion for
The weir portion has a suction hole for sucking a part of the ink composition on the bottom surface of the weir portion;
A part of the ink composition constituting the ink reservoir is sucked from the suction hole of the weir part and supplied again to the surface of the light transmission part.   The sheet manufacturing method according to claim 1, wherein the dam portion is disposed so as to have a gap between the bottom surface of the dam portion and the surface of the light transmission portion.   The manufacturing method of the sheet | seat of Claim 1 or 2 whose shape of the groove | channel of the said light transmissive part is a substantially trapezoid shape, a substantially V shape, or a substantially rectangular shape.

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