JP5672080B2 - Optical sheet manufacturing method and scraping device - Google Patents

Description

  The present invention relates to an optical sheet manufacturing method and a scraping device.

  In recent years, with the widespread use of thin and large displays, the usages such as home televisions and commercial display devices have been diversified, and a high level of display image quality is being demanded.

  The optical sheets used for these are also required to have a function of improving the transmittance and contrast, a function of controlling the viewing angle, or the like. For this reason, for example, an optical sheet having a light absorbing portion may be formed in order to improve contrast and control the viewing angle.

  An optical sheet having such a light absorbing portion is formed, for example, by providing a groove on the surface of the light transmissive sheet, filling the groove with a filling material containing a light absorbing material, and then curing the filling material. Can do.

  For example, the filling material can be filled by supplying the filling material to the vicinity of the upstream end of the doctor blade with the nozzle while moving the light-transmitting sheet with the doctor blade fixed, and between the sheet main body and the doctor blade. The excess filling material can be scraped off with a doctor blade while forming a filling material reservoir.

  However, when the filling material is filled by such a method, a streak defect or a fog defect may occur. Since the appearance quality of the optical sheet is directly related to the image quality, high quality is required. For this reason, it is preferable to reduce the above-described streak defects and fog defects as much as possible. In particular, when particles are included in the filling material, these defects are likely to occur.

  Here, in order to improve the streak defect, a technique for scraping the filling material while swinging the scraping member is disclosed (for example, see Patent Document 1). According to this technique, by swinging the scraping member, the foreign matter biting into the scraping member at the time of scraping hits the groove wall as the scraping member moves, and the foreign matter is removed from the scraping member.

  However, even when the scraping member is swung, a streak defect may occur.

JP 2009-128645 A

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide an optical sheet manufacturing method and a scraping device that can reduce streak defects and fog defects.

  As a result of intensive studies to reduce streak defects and fog defects, the present inventors have found that streak defects and fog defects can be reduced by using two or more scraping members having different widths. The present invention has been completed based on such findings.

  Here, the above-mentioned “streak defect” means that the cured filling material 100 filled in the groove is partially recessed as shown in FIG. 9A, or shown in FIG. 9B. As described above, the cured filling material 101 filled in some grooves has a larger dent than the cured filling material 102 filled in other grooves, and the dents are linear. To do.

  In addition, the “fogging failure” means that the excess filling material cannot be completely scraped off by the scraping member, and the filling material remains in the sheet body.

  According to one aspect of the present invention, the filling material is applied to the surface of the sheet body while moving the sheet body having a plurality of grooves arranged on the surface, and the filling material remains in the groove. A method of manufacturing an optical sheet comprising a step of scraping off excess filler material on the surface of the sheet body, wherein the scraping of the filler material includes a first scraping member and the sheet body. It is located upstream of the first scraping member with respect to the moving direction, and is arranged at a predetermined interval from the first scraping member, and the width is smaller than the width of the first scraping member. A method for producing an optical sheet is provided, which is performed by bringing a second scraping member into contact with the surface of the sheet main body.

  According to another aspect of the present invention, the sheet body has a plurality of grooves arranged in parallel on the surface, and the filling material remains in the grooves while moving the sheet body coated with the filling material on the surface. A scraping device for scraping off excess filler material on the surface of the sheet body, wherein the first scraping member is capable of contacting the surface of the sheet body, and is capable of contacting the surface of the sheet body. The first scraping member is located upstream of the first scraping member with respect to the moving direction of the sheet main body, is disposed at a predetermined interval from the first scraping member, and has a width. And a second scraping member smaller than the width of the scraping device.

  According to the method of manufacturing an optical sheet of one aspect of the present invention and the scraping device of another aspect, foreign substances such as bubbles can be scraped by the second scraping member, and the second scraping member Since the filling material can be further filled into the groove using the scraped filling material, streak defects can be reduced. Moreover, since the filling material can be further scraped off by the first scraping member after scraping by the second scraping member, the fogging defect can be reduced.

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 typically the formation process of the light absorption part which concerns on embodiment. It is sectional drawing of the sheet | seat in the manufacturing method of the optical sheet which concerns on embodiment. It is the figure which showed the base material sheet which has the adhesion layer and peeling layer which concern on embodiment. It is a side view of the 1st scraping member and the 2nd scraping member concerning an embodiment. It is the figure which looked at the 1st scraping member and the 2nd scraping member concerning an embodiment from the upper part. It is a side view which shows the other holder which concerns on embodiment. It is a top view which shows typically the filling process which concerns on embodiment. It is the figure which showed the stripe defect typically.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment mode, an optical sheet is manufactured. This optical sheet can be used for a display of a display device, for example.

  Examples 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.

  FIG. 1 is a diagram schematically illustrating a process of forming a light transmission unit according to the present embodiment, and FIG. 2 is a diagram schematically illustrating a process of forming a light absorption unit according to the present embodiment. FIG. 3 is a cross-sectional view of the sheet in the optical sheet manufacturing method according to the present embodiment.

  First, as shown in FIG. 1, the base sheet 1 is fed between a nip roll 11 and a mold 10 having a groove corresponding to the shape of a light transmitting portion 2 described later at a predetermined pitch. The arrow shown in FIG. 1 is the direction in which the base material sheet 1 is fed. In accordance with the feeding of the base sheet 1, droplets of the light transmission part forming composition 13 such as an ionizing radiation curable resin are continuously supplied from the supply device 12 between the mold 10 and the base sheet 1. When supplying the light transmissive part forming composition 13 from the supply device 12 onto the base sheet 1, a composition reservoir in which the light transmissive part forming composition 13 is accumulated between the mold 10 and the base sheet 1. 14 is formed. By forming the composition reservoir 14, the light transmission part forming composition 13 spreads in the width direction of the base sheet 1.

  The composition 13 for forming a light transmitting portion supplied between the mold 10 and the base sheet 1 as described above is applied to the base sheet 1 and the mold by the pressing force between the mold 10 and the nip roll 11. It is filled between the molds 10. Thereafter, the light transmitting device 15 is irradiated with light by the light irradiation device 15 to cure the light transmitting portion forming composition 13, thereby forming the light transmitting portion 2. After forming the light transmission part 2, the sheet main body 3 on which the light transmission part 2 is formed on the base sheet 1 is pulled away from the mold 10 by being pulled through the peeling roll 16.

  The base sheet 1 serves as a base for forming the light transmission part 2 on the base sheet 1. As the base material sheet 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. Furthermore, among polyester films, polyethylene terephthalate (PET) resin is preferable from the viewpoints of performance, mass productivity, price, availability, and the like.

  The base sheet 1 fed into the mold 10 may include an adhesive layer 6 and a release layer 7 as shown in FIG. The adhesive layer 6 is for bonding the optical sheet to the display 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.

  The “sheet main body” means a combination of at least the base sheet 1 and the light transmitting portion 2 as in the present embodiment. The sheet body 3 of the present embodiment is light transmissive.

  On the surface 3a of the sheet body 3, as shown in FIG. 3A, a groove 3b corresponding to the shape of the mold is formed between the unit light transmitting portions 2a. In the present embodiment, the groove 3b has a substantially trapezoidal shape as shown in FIG. The groove 3 b is formed so as to taper toward the base material sheet 1 side, and extends along the longitudinal direction of the base material sheet 1. The shape of the groove 3b is not limited to a substantially trapezoidal shape, and may be formed, for example, in a substantially V shape or a substantially rectangular shape. Specifically, the sheet body 3 having a width of 200 to 2000 mm on the surface 3a of the sheet body 3 can be used. Further, the unit light transmission part 2a may be one in which the width of the upper part of the unit light transmission part 2a is 10 to 100 μm. The groove 3b has, for example, an upper width of 5 to 50 μm, a depth of the groove 3b of 50 to 200 μm, and a side wall of the groove 3b of 0 to 10 with respect to the normal direction of the bottom surface of the groove 3b. It may be at an angle of °.

  In the above description, the sheet body 3 is formed using a mold and ultraviolet irradiation. However, the sheet body 3 may be formed by extrusion molding or hot press molding.

  After the sheet main body 3 is formed, the filling material 21 is filled into the groove 3b as shown in FIG.

  FIG. 5 is a side view of the first scraping member and the second scraping member according to the present embodiment, and FIG. 6 is the first scraping member and the second scraping member according to the present embodiment. It is the figure which looked at from the upper part. FIG. 7 is a side view showing another holder according to the embodiment, and FIG. 8 is a plan view schematically showing a filling process according to the present embodiment.

  First, the filling device 20 will be described. As shown in FIG. 2, the filling device 20 is present on the surface 3a of the sheet body 3 so that the filling material 21 remains in the groove 3b and the application nozzle 22 for applying the filling material 21 to the surface 3a of the sheet body 3. A scraping device 23 that scrapes off excess filling material 21 and a conveying means (device) 24 that moves the sheet main body 3 relative to the coating nozzle 22 and the like are provided.

  The application nozzle 22 is disposed upstream of the second scraping member 27 described below with respect to the moving direction of the sheet main body 3 and in the immediate vicinity of the second scraping member 27. In the present embodiment, the application nozzle 22 is disposed in the immediate vicinity of the second scraping member 27, but the position of the application nozzle 22 is particularly limited as long as it is upstream of the second scraping member 27. Not.

  In this embodiment, an example in which the filling material is applied using the application nozzle 22 is described. However, the filling material is applied by a die coating method or a slit coating method using an application head (not shown). May be.

  In this specification, “die coating method” means a method in which pressure is applied to the filling material and the filling material is pushed out from the slit of the coating head, and “slit coating method” means that no pressure is applied to the filling material. This means that the filling material is applied from the slit of the application head using the capillary phenomenon.

  In this case, the coating head has a slit having a length substantially the same as the width of the surface 3a of the sheet main body 3, and is disposed upstream of the filling material reservoir 32 described later with respect to the moving direction of the sheet main body 3. It is preferable.

  As shown in FIG. 5, the scraping device 23 includes at least a first scraping member 26 and a second scraping member located upstream of the first scraping member 26 with respect to the moving direction of the sheet body 3. And a member 27. In the present embodiment, the scraping device 23 includes two scraping members, a first scraping member 26 and a second scraping member 27, but the number of scraping members is three or more. There may be. In FIG. 5, the angles of the first scraping member 26 and the second scraping member with respect to the sheet body 3 are substantially the same, but are not necessarily the same. Specifically, for example, the angle of the first scraping member 26 with respect to the sheet body 3 and the angle of the second scraping member 27 with respect to the sheet body 3 may have a difference of 0 to 30 °.

  The scraping device 23 may further include a holder 28 that holds the first scraping member 26 and the second scraping member 27. The holder 28 shown in FIG. 5 holds both the first scraping member 26 and the second scraping member 27, but the holder that holds the first scraping member 26 as shown in FIG. 29 and a holder 30 that holds the second scraping member 27 may be separated.

  The first scraping member 26 and the second scraping member 27 are arranged so as to be orthogonal to the extending direction of the groove 3b, and are used in a state where the tips 26a, 27a are pressed against the surface 3a of the sheet body 3. Is done.

  As shown in FIGS. 5 and 7, the second scraping member 27 is disposed at a predetermined distance d from the first scraping member 26. Here, the “spacing” between the first scraping member and the second scraping member means the spacing between the base of the first scraping member and the base of the second scraping member. It shall be. This distance d is preferably 0.5 mm or more. The reason why this numerical range is preferable is that the filling material may not sufficiently enter between the first scraping member 26 and the second scraping member 27 if it is less than 0.5 mm. In addition, it may interfere with the first scraping member 26 and cause uneven filling. The upper limit value of the distance d is not particularly limited, but is preferably 30 mm or less.

  As shown in FIG. 6, the width W <b> 2 of the second scraping member 27 is smaller than the width W <b> 1 of the first scraping member 26. When the filling material 21 is scraped by making the width W2 of the second scraping member 27 smaller than the width W1 of the first scraping member 26, the second scraping member 27 and the first scraping member 27 are removed. The filling material 21 can be inserted between the take-up member 26.

  The width W2 of the second scraping member 27 is preferably 80 to 98% of the width W1 of the first scraping member 26. The reason why this numerical range is preferable is that if it is less than 80%, the width W2 of the second scraping member 27 is too small, and the filling material that flows into the first scraping member 26 increases. This is because foreign substances such as bubbles may not be removed reliably. On the other hand, if it exceeds 98%, it becomes difficult for the filling material to enter between the second scraping member 27 and the first scraping member 26, which may cause streak defects and band defects. In this case, it is possible to form a reservoir of filling material between the second scraping member 27 and the first scraping member 26 in advance, but in this case, the second scraping member 27 and It is necessary to replenish the filling material between the first scraping member 26 and the management of the filling material may be difficult.

  The contact pressure of the first scraping member 26 with respect to the sheet body 3 is set to be larger than the contact pressure of the second scraping member 27 with respect to the sheet body 3. Such a difference in contact pressure can be realized, for example, by causing the tip 26a of the first scraping member 26 to slightly protrude from the tip 27a of the second scraping member 27, for example. In this way, by providing a difference in contact pressure between the first scraping member 26 and the second scraping member 27, it is possible to provide an adjustment range at the time of manufacturing progress, and to cope with the occurrence of defects. Can be easily. In addition, the protrusion length L shown by FIG. 5 and FIG. 7 is a positive value that the front-end | tip 26a of the 1st scraping member 26 protrudes rather than the front-end | tip 27a of the 2nd scraping member 27. Means that.

  Examples of the first scraping member 26 and the second scraping member 27 include a doctor blade.

  The first scraping member 26 and the second scraping member 27 shown in FIGS. 5 and 7 have the thicknesses of the tip portions 26b and 27b substantially equal to the thicknesses of the base portions 26c and 27c. As the scraping member and the second scraping member, those having a tip portion thinner than a base portion by taper processing or stepping processing may be used.

  The leading end 26a of the first scraping member 26 and the leading end 27a of the second scraping member 27 are portions that come into contact with the sheet body 3, and therefore have a curved shape from the viewpoint of preventing scratches and scraping defects. Is preferred. Specifically, the tip 26a of the first scraping member 26 and the tip 27a of the second scraping member 27 preferably have a radius of curvature of 0.01 to 1.0 mm.

  The thickness of the first scraping member 26 and the second scraping member 27 is preferably 0.05 to 2.0 mm. Here, the “thickness” of the first scraping member and the second scraping member means the thickness of the base of the first scraping member and the thickness of the base of the second scraping member. . The reason why this numerical range is preferable is that if it is less than 0.05 mm, the rigidity of the first scraping member 26 and the like is so weak that a good appearance cannot be obtained on the optical sheet. This is because if it exceeds 0 mm, the rigidity becomes too strong, and it may be difficult to finely adjust the position of the first scraping member 26 and the like being manufactured.

  The materials of the first scraping member 26 and the second scraping member 27 are preferably harder than the filling material 21. Examples of such a material include metals such as steel whose surface is plated.

  Next, the filling material 21 to be filled by the filling device 20 will be described. The filling material 21 is not particularly limited as long as it is a material that can be filled in the groove 3b. However, in the case where the light absorbing portion of the optical sheet is formed as in the present embodiment, for example, the filling material 21 is filled. The material 21 preferably includes a transparent ionizing radiation resin composition and a light absorbing material.

  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.

  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.

  Examples of the light absorbing material include a colorant that can selectively absorb a specific wavelength in accordance with the characteristics of image light, and light absorbing particles obtained by coloring resin beads or glass beads with a colorant. Examples of the colorant include metal salts such as carbon black, graphite, fibrous carbon, and black iron oxide, inks containing dyes and pigments, and the like.

  As the pigment, perylene black pigment, aniline black pigment, format black (mixed pigment of yellow, magenta and cyan pigment), phthalocyanine blue, brilliant carmine 6B and the like which can transmit infrared light are preferable.

  The light absorbing particles may be obtained by kneading a colorant into resin beads or glass beads. 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 a resin colored with a pigment or dye is preferably used, and a specific wavelength is selectively selected according to the characteristics of the image light. Although it may absorb, resin beads colored in black are preferably used.

  Among the above-mentioned materials, carbon black can be suitably used as the colorant used for the light absorbing particles. 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 material in the ionizing radiation curable resin composition, the light absorbing particles can 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 filling material 21 containing each component described above can be prepared by mixing a predetermined amount of a light absorbing material into the ionizing radiation curable resin composition and adding a polymerization initiator or the like as desired. The addition amount of the light absorbing material is preferably in the range of 15 to 35% with respect to the total mass of the filling material 21, and by setting it in this range, it is possible to realize an optical sheet with more excellent contrast. If the content of the light absorbing material is too small, the light shielding property of the light absorbing portion may be insufficient, and if the content of the light absorbing material is too large, the resin beads may come into contact with each other, causing a problem of cracking or chipping. It tends to occur.

  The filling material 21 preferably has a viscosity at 25 ° C. of 1000 to 5000 mPa · s, and more preferably 2000 to 3000 mPa · s. The reason why this numerical range is preferable is that if it is less than 1000 mPa · s, the shape of the filling material reservoir becomes unstable, which may affect the appearance of the sheet, and if it exceeds 5000 mPa · s, it is filled. This is because there is a possibility that the appearance of the sheet such as a defect, a fogging defect and a band unevenness may be affected.

  Using the filling device 20 and the filling material 21 as described above, the filling material 21 is filled in the grooves 3b of the sheet body 3.

  Specifically, the filling material 21 is applied from the application nozzle 22 while moving the sheet main body 3 by the conveying unit 24. Thereafter, as shown in FIG. 8, excess filling material present on the surface 3 a of the sheet body 3 so that the filling material 21 remains in the groove 3 b by the first scraping member 26 and the second scraping member 27. 21 is scraped off.

  Here, since the second scraping member 27 is located upstream of the first scraping member 26 with respect to the moving direction of the sheet main body 3, the scraping of the filling material 21 is first performed by the second scraping member 27. Performed by member 27. By scraping the second scraping member 27, most of the extra filling material and foreign matters such as bubbles can be removed.

  Since the width W2 of the second scraping member 27 is smaller than the width W1 of the first scraping member 26, a part of the filling material 21 scraped by the second scraping member 27 is used. Enters between the second scraping member 27 and the first scraping member 26. The filling material 21 that has entered the space is filled into the groove 3b that is not sufficiently filled. Thereby, since the filling rate of the filling material 21 can be improved, streak defects can be reduced. Further, the excessive filling material 21 existing on the groove 3b is scraped off by the first scraping member 26 for the groove 3b which has been sufficiently filled. Thereby, a fogging defect can be reduced.

  Further, by using two or more scraping members such as the first scraping member 26 and the second scraping member 27, the contact pressure of the scraping member with respect to the sheet main body 3 can be dispersed. Thereby, the load with respect to the sheet | seat main body 3 can be reduced, and defects, such as a damage | wound and rubbing, can also be reduced.

  When the filling material 21 is applied and the filling material 21 is scraped, the filling material 21 is accumulated between the surface 3a of the sheet body 3 and the tip 27a of the second scraping member 27 (filling material accumulation). 31 is formed. Similarly, a reservoir 32 (filling material reservoir) 32 of the filling material 21 is formed between the surface 3 a of the sheet body 3 and the tip 26 a of the first scraping member 26. Here, the filling material 21 is filled into the groove 3 b by the second scraping member 27, but most of the surplus filling material 21 is scraped by the second scraping member 27. Is larger than the filling material reservoir 32.

  It is preferable to swing the first scraping member 26 and the second scraping member 27 during scraping. When the first scraping member 26 and the second scraping member 27 are swung at the time of scraping, the first scraping member removes foreign matter biting into the first scraping member 26 and the second scraping member 27. Etc. can be removed.

  The swing width of the first scraping member 26 and the second scraping member 27 is preferably more than 0 mm and not more than 50 mm. The reason why this numerical range is preferable is that when it exceeds 50 mm, the shapes of the filling material reservoirs 31 and 31 become uneasy and the appearance of the sheet may be affected.

  Then, for example, as shown in FIG. 2, ionizing radiation is irradiated by an ionizing radiation irradiation device 25 such as an ultraviolet lamp to cure the filling material 21. As a result, as shown in FIG. 3B, the light absorbing portion 4 having a shape corresponding to the shape of the groove 3 b is formed in the groove 3 b of the sheet body 3, and the optical sheet 5 is formed.

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

(Example)
First, a transparent ultraviolet curable resin is applied on a base sheet made of polyethylene terephthalate resin having a thickness of 100 μm, and an ultraviolet ray is applied to a mold having a substantially trapezoidal groove and a substantially trapezoidal protrusion on the peripheral surface. The base sheet was pressed so that the curable resin was in contact with the mold.

  And after pressing the roll from the base material sheet side and making it into desired thickness, the ultraviolet-ray curable resin was hardened by irradiating an ultraviolet-ray through a base material sheet. Thereafter, the cured ultraviolet curable resin was peeled off from the mold to form a light transmission part having a plurality of unit light transmission parts.

  The unit light transmission part has a substantially trapezoidal shape, and a groove having a substantially trapezoidal cross section is formed between the unit light transmission parts. This groove extends in the flow direction of the base sheet. The groove has a depth of 120 μm, a width of the top of the groove of 20 μm, and an angle formed between the normal of the base sheet and the slope of the groove. The length of the repeating unit of 3 ° and the groove was 85 μm.

  Next, a doctor blade tilted by 60 ° from the surface of the light transmission part is arranged so as to be orthogonal to the groove, and the blade speed of the doctor blade is pressed against the surface of the light transmission part at a line speed of 5.0 m / min. A filling material containing a black ink (light absorbing material) and an ultraviolet curable resin having a viscosity of 3500 mPa · s at 25 ° C. from the upstream side of the doctor blade, flowing through a sheet main body having a base sheet and a light transmitting portion Was applied to the surface of the light transmission part.

  The applied filling material was filled in the grooves between the unit light transmitting portions. And the excess filling material which exists on the unit light transmission part was scraped off by the doctor blade. The scraping with the doctor blade was performed while the doctor blade was swung at a speed of 10% of the line speed and with a width of ± 5 mm.

  Two doctor blades were used. The upstream doctor blade (second scraping member) had a width of 1000 mm, and the downstream doctor blade (first scraping member) had a width of 1050 mm. The interval between the doctor blades was set to 1 mm by interposing a 1 mm thick spacer between the doctor blades. The tip of the downstream doctor blade protruded 1 mm from the tip of the upstream doctor blade. Further, the doctor blade was made of metal, and was stepped on one side so that the tip of the doctor blade was thinner than the base of the doctor blade. The thickness of the tip portion was 0.07 mm, and the thickness of the base portion was 0.2 mm. The tip of the doctor blade had a radius of curvature of 0.035 mm. The upstream and downstream doctor blades are installed so that the angle of the upstream and downstream doctor blades with respect to the seat body is both 60 ° and the stepped surface is both downstream. It was.

  After the excess filling material was scraped off, ultraviolet rays were irradiated to cure the ultraviolet curable resin contained in the filling material in the groove to produce the optical sheet of the example.

(Comparative Example 1)
In Comparative Example 1, an optical sheet was produced in the same manner as in the Example except that one doctor blade was used. The width of the doctor blade according to Comparative Example 1 was 1050 mm, and the doctor blade was installed so that the angle of the doctor blade with respect to the sheet body was 60 °.

(Comparative Example 2)
In Comparative Example 2, an optical sheet was produced in the same manner as in Example except that one doctor blade was used and the doctor blade was not rocked. The width of the doctor blade according to Comparative Example 2 was 1050 mm, and the doctor blade was installed so that the angle of the doctor blade with respect to the sheet body was 60 °.

(Comparative Example 3)
In Comparative Example 3, an optical sheet was produced in the same manner as in Example except that one doctor blade having a tip of 90 ° was used. The width of the doctor blade according to Comparative Example 3 was 1050 mm, and the doctor blade was installed so that the angle of the doctor blade with respect to the sheet main body was 60 °.

(Comparative Example 4)
In Comparative Example 4, an optical sheet was produced in the same manner as in Example except that the tip was 90 ° and one doctor blade made of polyacetal resin was used. The width of the doctor blade according to Comparative Example 4 was 1050 mm, and the doctor blade was installed so that the angle of the doctor blade with respect to the sheet body was 60 °.

(Comparative Example 5)
In Comparative Example 5, an optical sheet was produced in the same manner as in Example except that one doctor blade having a thickness of 0.3 mm was used. The width of the doctor blade according to Comparative Example 5 was 1050 mm, and the doctor blade was installed so that the angle of the doctor blade with respect to the sheet body was 60 °.

(Comparative Example 6)
In Comparative Example 6, an optical sheet was produced in the same manner as in Example except that one doctor blade having a thickness of 0.15 mm was used. The width of the doctor blade according to Comparative Example 6 was 1050 mm, and the doctor blade was installed so that the angle of the doctor blade with respect to the sheet main body was 60 °.

(Comparative Example 7)
In Comparative Example 7, two doctor blades were used, but the width of the upstream doctor blade was larger than the width of the downstream doctor blade. Specifically, the upstream doctor blade according to Comparative Example 7 had a width of 1050 mm, and the downstream doctor blade had a width of 1000 mm. Such a doctor blade was installed in the same manner as in the example, and an optical sheet was produced in the same manner as in the example.

(Comparative Example 8)
In Comparative Example 8, two doctor blades were used, but the upstream and downstream doctor blades had the same width. Specifically, both the upstream and downstream doctor blades according to Comparative Example 8 had a width of 1050 mm. Such a doctor blade was installed in the same manner as in the example, and an optical sheet was produced in the same manner as in the example.

Appearance Observation When the appearance of the optical sheets of Examples and Comparative Examples 1 to 8 thus prepared was observed, the optical sheets of the examples were in a good state with very few streak defects and fog defects. . On the other hand, in the optical sheet of Comparative Example 1, more streak defects are observed than in the example, in the optical sheet of Comparative Example 2, many streak defects are observed, and in the optical sheet of Comparative Example 3, many streak defects are observed. In addition, poor fog was observed. In the optical sheet of Comparative Example 4, the appearance produced in the initial stage was good in appearance, but an increase in streak defects was observed over time. In the optical sheet of Comparative Example 5, more streak defects were observed than in Examples, and in the optical sheet of Comparative Example 6, fogging defects and weak shading unevenness were observed. In the optical sheets of Comparative Examples 7 and 8, many streak defects and band defects were observed.

  From these results, it is confirmed that when scraping is performed using two doctor blades whose upstream doctor blade width is smaller than that of the downstream doctor blade, streak defects and fog defects can be reduced. It was done.

  DESCRIPTION OF SYMBOLS 1 ... Base material sheet, 2 ... Light transmission part, 2a ... Unit light transmission part, 3 ... Sheet main body, 3a ... Surface, 3b ... Groove, 4 ... Light absorption part, 5 ... Optical sheet, 21 ... Filling material, 22 ... Application nozzle, 23 ... scraping device, 26 ... first scraping member, 26a ... tip, 27 ... second scraping member, 27a ... tip.

Claims (10)

While moving the plurality of grooves seat body which is arranged on a surface, said Filling material is applied to the surface of the seat body, on the surface of the seat body such that the filling material in the trench remains A method for producing an optical sheet comprising a step of scraping off excess filler material,
The scraping of the filling material is positioned upstream of the first scraping member and the first scraping member with respect to the moving direction of the first scraping member and the sheet main body, and a predetermined distance from the first scraping member Of the optical sheet, wherein a second scraping member having a width smaller than the width of the first scraping member is brought into contact with the surface of the sheet body. Production method.   The manufacturing method of the optical sheet of Claim 1 whose space | interval between a said 1st scraping member and a said 2nd scraping member is 0.5-30 mm.   The scraping of the filling material is performed while swinging at least one of the first scraping member and the second scraping member with a swing width of more than 0 mm and 50 mm or less. 2. A method for producing an optical sheet according to 2.   The method of manufacturing an optical sheet according to any one of claims 1 to 3, wherein a tip of at least one of the first scraping member and the second scraping member has a curved shape.   The method for manufacturing an optical sheet according to any one of claims 1 to 4, wherein a material of at least one of the first scraping member and the second scraping member is a metal.   The method for producing an optical sheet according to claim 1, wherein a thickness of at least one of the first scraping member and the second scraping member is 0.05 to 2.0 mm.   The method for manufacturing an optical sheet according to any one of claims 1 to 6, wherein at least one of the first scraping member and the second scraping member is a doctor blade.   8. The optical sheet according to claim 1, wherein the sheet main body is a light transmissive sheet, and the filling material includes a transparent resin and a light absorbing material dispersed in the transparent resin. Method.   The method for manufacturing an optical sheet according to any one of claims 1 to 8, wherein a shape of the groove is a substantially trapezoidal shape, a substantially V shape, or a substantially rectangular shape. Excess filling material on the surface of the sheet body such that a plurality of grooves are juxtaposed on the surface and the filling material remains in the grooves while moving the sheet body on which the filling material is applied. A scraping device for scraping
A first scraping member that can contact the surface of the sheet main body, and a surface that can contact the surface of the sheet main body, upstream of the first scraping member with respect to a moving direction of the sheet main body. A second scraping member located at a predetermined distance from the first scraping member and having a width smaller than the width of the first scraping member. Scraping device.

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