JP5720280B2 - Roll mold manufacturing method and optical sheet manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a roll mold used when manufacturing an optical sheet having a fine uneven shape on the surface, and a method of manufacturing an optical sheet including the method of manufacturing the roll mold.

  In an image display device that emits an image to an observer, such as a plasma television or a liquid crystal display device, an image light source and an optical sheet having various functions for improving the quality of image light from the image light source and transmitting the image light to the observer And are provided.

  In such an optical sheet, a plurality of layers are usually laminated, and one of the layers may include a layer having a fine uneven shape on the surface. In order to produce a sheet having fine irregularities on the surface as described above, a roll mold having grooves and projections capable of transferring a shape corresponding to the irregularities is usually used.

  Patent Document 1 discloses a method for manufacturing a roll mold applied to an optical sheet. Here, a technique relating to a bite shape for manufacturing a mold for manufacturing an optical sheet capable of suppressing the occurrence of point defects and linear defects is described.

JP 2003-21457 A

  The grooves and protrusions formed on the surface of the roll mold need not be formed on the roll mold, but a very large number of grooves and protrusions must be formed on the roll mold. From the viewpoint of ensuring the quality of the optical sheet transferred from the roll mold, the infinite number of grooves and protrusions need to be as uniform as possible at any part on the roll mold.

  In a conventional method for manufacturing a roll mold for manufacturing an optical sheet, the shape of a cutting tool corresponding to the cross-sectional shape of grooves and protrusions formed on the surface of the roll mold has been considered. However, when this is used for a long time, there is a possibility that the groove of the groove and the protrusion formed on the surface of the roll mold is bent so that the protrusion falls down, especially at a portion where the cutting ends and in the vicinity thereof. It was. If an optical sheet is manufactured with such a roll mold, the groove and protrusion shape of the roll mold are transferred to the optical sheet, which may affect the characteristics of the optical sheet.

  Therefore, the present invention provides a roll mold manufacturing method capable of suppressing a change in groove shape between a groove cutting start part and a groove cutting end part when manufacturing a roll mold for forming an optical sheet. I will provide a. Moreover, the manufacturing method of the optical sheet containing the manufacturing method of this roll metal mold | die is provided.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

The invention according to claim 1 is a method of manufacturing a roll mold (20) for forming a concavo-convex portion of an optical sheet (10) having a concavo-convex shape, the roll base having a work layer formed on the surface ( 21) and rotating the cutting tool (30) to form a groove (23) corresponding to the irregularities of the optical sheet. In the step of forming the groove, the cutting by the cutting tool is included in the cutting tool bit angle. The rotation axis of the roll base while moving the bite in the direction along the rotation axis of the roll base so as to have the same angle as the bite angle on the rear side with respect to the movement direction of the bite along the rotation axis of the roll base It is a manufacturing method of the roll metal mold | die characterized by being performed in the direction which approaches.

Invention according to claim 2, in roll mold manufacturing method according to claim 1, the diameter of the roll base body (21) is more than 300 mm, and is less than 500mm, the rotating speed of the roll substrate 300 r pm or more, 600 rpm A groove is formed as follows.

  Invention of Claim 3 is a manufacturing method of the roll metal mold | die of Claim 1 or 2, The cutting speed of the cutting tool (30) is 2 micrometer / rev or more and 5 micrometers / revolution or less, It is characterized by the above-mentioned.

  Invention of Claim 4 is a manufacturing method of the roll metal mold | die as described in any one of Claims 1-3 WHEREIN: With the attitude | position which the cutting tool (30) reached the cutting depth, roll base | substrate (21) It is characterized in that the cutting tool is retracted after one rotation or more.

Invention of Claim 5 is a manufacturing method of the roll metal mold | die as described in any one of Claims 1-4, The bottom part of the groove | channel (23) formed in a roll base | substrate (21), Between these groove | channels The cutting tool is moved in a direction along the rotation axis of the roll base so as to alternately cut the outer peripheral portion which is the tip portion of the annular protrusion (22) formed on the roll base .

The invention according to claim 6 is the method of manufacturing a roll mold according to claim 5, wherein after cutting one outer peripheral portion, the cutting tool (30) is pulled back in the radial direction of the roll base (21). When the cutting tool is moved in the direction along the rotation axis of the roll base in order to cut the groove (23), the pitch of the groove is p (mm), and the cutting tool moves along the rotation axis of the roll base. Rotation axis of the roll base when the bite angle on the rear side with respect to the direction is θa1 (degrees) and the distance between the bottom of the groove to be cut and the movement start position for cutting the cutting tool is t (mm) The feed amount r (mm) that is the amount of movement in the direction along
r = p / 2− (t · tan (θa1))
It is calculated by the following.

  Invention of Claim 7 manufactures a roll metal mold | die (20) with the manufacturing method as described in any one of Claims 1-6, Between a roll metal mold | die and a base material (11 '). The method for producing an optical sheet includes a step of filling a photocurable material with a photocurable material, and a step of irradiating the photocurable material with light in a filled state to cure the photocurable material.

ADVANTAGE OF THE INVENTION According to this invention, when manufacturing the roll metal mold | die which forms an optical sheet, it can suppress that the shape of a groove | channel changes by the cutting start part of a groove | channel, and the cutting end part of a groove | channel. Therefore, it is possible to form a longer distance groove with one cutting tool.
Moreover, according to the manufacturing method of an optical sheet using such a roll metal mold | die manufacturing method using this roll metal mold | die, an optical sheet with high optical uniformity can be manufactured.

It is the figure which showed roughly a part of cross section of the optical sheet manufactured with the manufacturing method concerning one embodiment. It is the figure which expanded a part of FIG. It is the figure which showed roughly the external appearance of the roll metal mold | die. It is the figure which expanded and showed the annular protrusion and groove | channel of the roll metal mold | die. It is the figure which showed the shape of the cutting tool roughly. FIG. 6A is a diagram illustrating a part of the process of the roll mold manufacturing method, and FIG. 6B is also a diagram illustrating a part of the process of the roll mold manufacturing method. Fig.7 (a) is a figure explaining a part of process of the manufacturing method of a roll metal mold | die, FIG.7 (b) is a figure explaining a part of process of the manufacturing method of a roll metal mold | die. FIG. 8 is a diagram for explaining a part of the process of the roll mold manufacturing method. It is a figure explaining a part of process of the method of manufacturing an optical sheet. It is a figure explaining a prospective angle.

  The above-described operation and gain of the present invention will be clarified from embodiments for carrying out the invention described below. Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these embodiments.

  First, the configuration of the optical sheet 10 manufactured by the manufacturing method according to one embodiment will be described. This is an example of an optical sheet manufactured using a roll mold described later.

  FIG. 1 is a diagram schematically showing a layer configuration of a part of a cross section in the thickness direction of the optical sheet 10. In FIG. 1, some repetitive symbols are omitted for ease of viewing (the same applies to the following drawings). The optical sheet 10 is provided on the viewer side with respect to the video light source when placed on the video display device, and can appropriately shield the light (so-called external light) irradiated from the viewer side and improve the contrast. It is a sheet-like member.

  The optical sheet 10 includes a base material layer 11 and an optical functional layer 12 formed on the base material layer 11. The base material layer 11 and the optical function layer 12 will be described below.

  The base material layer 11 is a layer serving as a base material for forming the optical functional layer 12 described in detail later. The base material layer 11 is preferably composed of a material mainly composed of polyethylene terephthalate (PET). When the base material layer 11 has PET as a main component, the base material layer 11 may contain other resins. Various additives may be added as appropriate. Examples of general additives include phenol-based antioxidants, lactone-based stabilizers, and the like. Here, “main component” means that the PET is contained in an amount of 50% by mass or more with respect to the entire material forming the base material layer (hereinafter the same).

However, the main component of the material constituting the base material layer 11 is not necessarily PET, and other materials may be used. Examples thereof include polybutylene terephthalate, polyethylene naphthalate, terephthalic acid-isophthalic acid-ethylene glycol copolymer, polyester resins such as terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, and polyamide resins such as nylon 6. , Polyolefin resins such as polypropylene and polymethylpentene, acrylic resins such as polymethyl methacrylate, styrene resins such as polystyrene and styrene-acrylonitrile copolymer, cellulose resins such as triacetyl cellulose, imide resins and polycarbonate resins Etc. Moreover, you may add additives, such as a ultraviolet absorber, a filler, a plasticizer, an antistatic agent, suitably in these resin as needed.
In addition to performance, from the viewpoints of mass productivity, price, availability, etc., it is preferable that the base material layer 11 is composed of a resin mainly composed of PET.

  The optical functional layer 12 is a layer having a function of appropriately absorbing stray light and external light while controlling the optical path of the image light from the image light source side. The optical functional layer 12 has a shape that has the cross section shown in FIG. 1 and extends to the back / near side of the drawing. That is, in the cross section shown in FIG. 1, light absorption formed between the light transmission portion 13 having a substantially trapezoidal cross section and the concave portion 13 a (see FIG. 2) having a substantially trapezoidal cross section. Part 14. In FIG. 2, one light absorption part 14 and the light transmission part 13 adjacent to this are expanded and shown among the optical sheets 10 shown in FIG.

  The light transmitting portion 13 is a portion that transmits light, and in the cross section shown in FIGS. 1 and 2, the surface on the base layer 11 side has a lower bottom, and the surface on the opposite side is shorter than the lower bottom. It is an element with a substantially trapezoidal cross section having an upper base. The light transmitting portions 13 are arranged in parallel at a predetermined interval along the sheet surface, and a recess 13a having a substantially trapezoidal cross section is formed therebetween. The concave portion 13a has a trapezoidal cross section having a lower base on the upper base side of the light transmitting portion 13 and an upper base on the lower base side of the light transmitting portion 13, and is filled with necessary materials described later. The light absorption part 14 is formed.

  The interval at which the light transmission portions 13 are arranged in parallel (the interval between one light transmission portion 13 and the light transmission portion 13 adjacent thereto, the pitch) is not particularly limited, but may be 30 μm or more and 100 μm or less. preferable.

In FIG. 2, each dimension of the recessed part 13a was represented by AD. In FIG. 2, A is the length of the bottom of the recess 13a. Similarly, B is the length of the upper base, C is the height, and D is the angle between the hypotenuse and the sheet normal. Each of the dimensions A to D is designed to have performance required as an optical sheet, and its value is not particularly limited, but A is preferably 5 μm or more and 20 μm or less. Similarly, B is preferably the same as or smaller than A, 3 μm to 20 μm, C is 50 μm to 150 μm, and D is 0 ° to 5 °.
As will be described later, a roll mold corresponding to each dimension required here is manufactured.

  The light transmitting portion 13 has a refractive index of Np and has light transmittance. Such a light transmission part 13 can be formed by hardening the light transmission part structure composition mentioned later, for example. Details will be described later. The value of the refractive index Np is not particularly limited, but is preferably 1.49 to 1.56 from the viewpoint of the availability of the applied material.

  Next, the light absorption unit 14 will be described. The light absorbing portion 14 is formed in the concave portion 13a between the light transmitting portions 13 described above, and is configured to be able to absorb light as a whole. Therefore, the shape is generally along the recess 13a.

  The light absorbing portion 14 is made of a predetermined material having a refractive index Nb that is the same as or smaller than the refractive index Np of the light transmitting portion 13. When the refractive index Np of the light transmission part 13 and the refractive index Nb of the light absorption part 14 are Np> Nb, the difference in refractive index and the light incident on the interface at the interface between the light absorption part 14 and the light transmission part 13 Based on the relationship with the corner, a part of the image light can be appropriately reflected at this interface and emitted to the viewer side. Thereby, in addition to the image light transmitted through the light transmission part 13 without being reflected on the interface, the image light reflected in this way is provided to the observer, and a bright image can be obtained. Further, a part of the external light and stray light is incident on the light absorbing portion 14 without being reflected at the interface and absorbed, thereby improving the image quality. The difference in refractive index between Np and Nb is not particularly limited, but is preferably 0 or more and 0.06 or less. The greater the difference in refractive index, the easier it is to reflect at the interface.

  In the present embodiment, the light absorbing portion 14 has light absorbing performance by containing the light absorbing particles 16. That is, the concave portion 13a is filled with a binder (light absorbing portion constituting composition) in which the light absorbing particles 16 are dispersed. Therefore, in this case, the binder is a substance having a refractive index Nb. The material and method for forming the light absorbing portion 14 will be described in detail later.

  The means for absorbing light is not limited to the method using light absorbing particles as in this embodiment. In addition, for example, the entire light absorbing portion can be colored with a pigment or a dye.

  According to such an optical sheet 10, it is possible to appropriately shield outside light. FIG. 1 schematically shows an example of an optical path of external light incident on the optical sheet 10. In this description, the viewer side is on the paper surface of FIG. That is, as shown in FIG. 1, external light L <b> 1 incident on the optical sheet 10 at a predetermined angle is absorbed by the light absorbing unit 14 while being transmitted through the optical sheet 10. Thereby, contrast can be improved.

  Next, the roll metal mold | die 20 for forming the unevenness | corrugation (recessed part 13a) of the optical function layer 12 among the above optical sheets 10 is demonstrated. FIG. 3 is a perspective view schematically showing the appearance of the roll mold 20. 4 is an enlarged view of a part of the cross-section of the annular protrusion 22 and the groove 23 formed on the outer peripheral surface of the roll mold 20 shown in FIG. The cross section is a cross section orthogonal to the direction in which the annular protrusion 22 and the groove 23 extend, and is a cross section in the direction along the rotation axis of the roll mold 20.

  As shown in FIG. 3, the roll mold 20 is a so-called roll-shaped mold having a cylindrical shape, and a plurality of annular protrusions 22 projecting from the outer peripheral surface of the cylindrical roll base 21, and between the annular protrusions 22. A groove 23 is formed. Here, the annular protrusion 22 and the groove 23 are provided in the roll mold 20 so as to extend in the circumferential direction, and are further arranged in parallel in the width direction (the roll rotation axis direction). Further details are as follows.

The roll base 21 has a base serving as a base and a layer to be processed laminated on the outer surface of the base.
The base is a part for securing the rigidity of the roll base 21 and occupies most of the roll base 21. From this point of view, the base is preferably made of an iron-based material for mechanical structure. Further, from the viewpoint of reducing the weight while ensuring the necessary rigidity, the base may have a bottomed cylindrical shape having bottoms at both ends. Further, a double structure is generally adopted so that cold water, hot water, steam or high-temperature oil can be circulated inside the roll base 21 so that the temperature of the surface of the roll mold 20 can be adjusted.
On the other hand, the layer to be processed is a layer laminated so as to cover the outer surface of the substrate. Since the material of the substrate is selected from the viewpoint of structure as described above, it is often difficult to process. Therefore, since it is only necessary to actually process the vicinity of the surface of the roll base 21, a layer to be processed that is relatively easy to process is provided in the processed portion. Therefore, the layer to be processed is preferably a plating layer made of a material that can be easily processed, such as a copper plating layer or a nickel plating layer. The thickness of the layer to be processed is determined by the shape to be processed due to its nature. For example, the thickness of the copper plating layer is not a problem as long as it is higher than the required shape, but is usually 0.3 mm to 1.0 mm.

  As can be seen from the comparison of FIG. 4 with FIGS. 1 and 2, the annular protrusion 22 and the groove 23 have shapes corresponding to the light transmitting portion 13 and the concave portion 13 a of the optical function layer 12. That is, the annular protrusion 22 has the shape of the concave portion 13 a and the groove 23 has the shape of the light transmitting portion 13. Accordingly, A to D shown in FIG. 2 have dimensions corresponding to A 'to D' in FIG. However, considering that there is expansion and contraction when molding the material constituting the light transmission part, A to D in FIG. 2 are not necessarily the same dimensions as A ′ to D ′ in FIG. 4. It goes without saying that there is nothing.

  As can be seen from FIGS. 1 and 2, in the roll mold 20 for forming fine irregularities on the optical sheet, the grooves 22 and the annular protrusions 23 themselves are very fine, and the grooves 22 and the annular protrusions 23 are not formed. While extending in the circumferential direction of the roll mold 20, the roll mold 20 is densely formed so as to be aligned over the entire length in the width direction (roll rotation axis direction). Further, since the roll mold 20 is for molding an optical member, it is necessary to sufficiently ensure the accuracy of the groove 22 and the annular protrusion 23. Therefore, when the roll mold 20 is manufactured, it is necessary to form the annular protrusion 22 and the groove 23 efficiently for a long time while maintaining accuracy. Hereinafter, a method for manufacturing the roll mold 20 will be described.

A roll base 21 in which a layer to be processed is laminated on a base is prepared, and this is rotated by a roll rotation shaft. First, as a pre-processing for obtaining a reference surface, mirror processing is performed by a predetermined cutting tool (R bite) with a necessary cutting depth and feed. The R bit is a bit having an arcuate tip, and a diamond bit having a radius of curvature of 2 mm to 10 mm is often used. The feed pitch is generally 0.1 mm to 0.2 mm. Here, the diameter of the roll base 21 is not particularly limited, but is preferably 300 mm or more and 500 mm or less.
Thereafter, the groove 23 is formed by a cutting tool while rotating the roll base 21 based on the obtained reference surface. Here, the cutting tool has, for example, the following shape. FIG. 5 shows a schematic view of a cutting tip 30 as an example of the cutting tool used. In FIG. 5, the rake face is denoted by reference numeral 31, the front flank face is denoted by reference numeral 32, and the lateral flank face is denoted by reference numeral 33. 5 (a) is a perspective view, FIG. 5 (b) is a view from the rake face 31 side, FIG. 5 (c) is a view from the front flank face 32 side, and FIG. It is the figure seen from the side.

  The main dimensions of the cutting tip 30 are set so that the shape of the groove 23 can be formed.

  Further, the bite angles θa1 and θa2, the lateral clearance angle θb, and the front clearance angle θc shown in FIG. 5 are as follows. Here, the sum of the bite angles θa1 and θa2 is called an apex angle. The apex angle is an angle determined by the shape of the optical sheet to be manufactured. In FIG. 5 (b), w is the cutting edge width. The apex angle and the bite tip width are appropriately changed according to the shape of the groove to be formed.

The lateral clearance angle θb is preferably 2 degrees or more and 5 degrees or less. By setting the side clearance angle θb to 2 degrees or more, the cutting performance of the cutting tip 30 is improved and the burden on the cutting tip is reduced, so that wear can be reduced and processing can be performed with a single cutting tip with high accuracy. be able to. That is, it is possible to increase the number of cuttings by increasing the depth of the groove 23 or decreasing the pitch. Therefore, the roll die of the optical sheet can be manufactured without replacing the cutting tip or suppressing the number of replacements. That is, it is possible to improve the manufacturing efficiency and accuracy of the roll mold 20 and to manufacture the uneven shape of the optical sheet 10 that is the final product with high accuracy. Further, if the lateral clearance angle θb is larger than 5 degrees, it is necessary to increase the front clearance angle, and there is a concern that the strength of the cutting tip 30 is lowered.
The front clearance angle θc is usually 5 degrees or more and 20 degrees or less in many cases. If the angle is less than 5 degrees, the cutting performance tends to be deteriorated as with the side clearance angle. On the other hand, if it is greater than 20 degrees, the cutting tip tip is not rigid enough to cause chipping or chipping.

  The material of the cutting tip 30 can be appropriately selected depending on the material of the layer to be processed, the processing shape, and the like. Examples thereof include cemented carbide, CBN (cubic boron nitride), diamond and the like. Among these, diamond is preferable from the viewpoint of obtaining high accuracy. There are natural and synthetic diamonds, but there is no particular limitation.

  The rotational speed of the roll base 21 at the time of cutting is not particularly limited, but is preferably 300 rpm or more and 600 rpm or less. Although depending on the diameter of the roll base 21, for example, when the diameter is 400 mm, if it is less than 300 rpm, the cutting speed is slow, so that the burden on the cutting tip becomes large and it may not be possible to process with high accuracy. 600 rpm is approximately the maximum turning speed of the lathe. As the rotational speed of the roll base 21 is increased, the roll base tends to be shaken. From this viewpoint, about 400 rpm is preferable.

  The groove 23 and the annular protrusion 22 are formed as follows using the cutting tip 30 described above. A schematic diagram is shown in FIGS. 6, 7, and 8. Cutting is advanced in the order of FIG. 6A, FIG. 6B, FIG. 7A, FIG. 7B, and FIG.

  As shown in FIG. 6A, so-called cutting is performed from the outer peripheral surface of the roll base 21 toward the axial direction of the rotation axis of the roll base 21 by the cutting tip 30. At this time, the cutting direction is an oblique direction that proceeds in the feed direction (left direction on the paper surface) while moving in the axial direction of the rotation axis of the roll base 21. More specifically, as indicated by VI in FIG. 6A, the cutting tip 30 has the same angle as the cutting tool angle θa1 that is opposite to the feed direction (rightward in the drawing) during cutting. While feeding, cut in the axial direction of the rotating shaft. And it cuts to the position of FIG.6 (b), and the one groove | channel 23 is formed.

  By making an oblique cut in this way, the force from the cutting tip 30 that tries to tilt the annular protrusion 22 being formed in the direction indicated by E in FIG. It is possible to suppress falling down so as to bend in the direction of. In particular, as the cutting progresses, the cutting force of the cutting tip 30 decreases, and the force to be applied to the annular protrusion 22 tends to increase. On the other hand, according to the present manufacturing method, since the force to fall over the entire region from the start portion to the end portion of cutting can be suppressed, it is possible to suppress the groove shape from being different depending on the portion of the cutting roll, and to stabilize the shape. Can be improved.

  In the conventional manufacturing method, since the cutting direction coincides with the radial direction of the roll base, a force corresponding to the force indicated by E in FIG. When the cutting tip becomes sharp at the end of cutting, this force is further increased, resulting in a large difference in how the annular protrusions fall between the cutting start and end.

Next, from the state shown in FIG. 6B, the cutting tip 30 is retracted from the groove 23 in the radial direction of the roll base 21. And it feeds by the half pitch of the pitch of the groove | channel 23, and cuts in the radial direction of the roll base | substrate 21 to the outer peripheral part position of the cyclic | annular protrusion 22 as shown to Fig.7 (a). Thereby, the outer peripheral part of the annular protrusion 22 is formed.
After that, the cutting tip 30 is retracted in the radial direction of the roll base 21, and the cutting tip 30 is sent to cut the next groove 23. As shown in FIG. 7B, the feed amount r (mm) at this time takes into account the amount of cutting in the oblique direction from the half pitch (p / 2) of the pitch p (mm) of the groove 23. The amount is obtained by subtracting the amount s (mm). Here, the amount s (mm) to be subtracted is t (mm) when the distance between the bottom surface of the groove 23 and the position where the cutting tip 30 starts moving for cutting is t (mm).
s = t · tan (θa1)
It is represented by Therefore, the feed amount r (mm) is
r = p / 2− (t · tan (θa1))
It becomes.
6A and 6B, the grooves 23 and the annular protrusions 22 are formed as shown in FIG.

  Here, the cutting speed is preferably 2 (μm / rotation) or more and 5 (μm / rotation) or less. Further, when the cutting tip (cutting tool) reaches the cutting depth, it is preferable that the cutting tip 30 is retracted after the roll base 21 is rotated one or more times in the same posture. Thereby, it becomes the predetermined cutting depth over the circumference direction circumference of the roll base 21. If the cutting tip 30 is retracted in less than one rotation, there may be a portion that does not reach the predetermined cutting depth partially in the circumferential direction, and the appearance defect and the optical performance may vary.

  As described above, the annular protrusion 22 and the groove 23 are formed so as to extend in the circumferential direction of the roll base 21 and to be arranged in parallel over the entire length of the rotation base direction (width direction) of the roll base 21. In the present manufacturing method, as described above, the cutting direction is the direction approaching the rotation axis of the roll base 21 while including the feeding direction, and by adjusting the angle to the bite angle, the annular protrusion extends over the entire roll die. It becomes possible to suppress changes in the shapes of the grooves 22 and the grooves 23. Therefore, it is possible to manufacture a roll mold without exchanging the cutting tip (cutting tool) or by reducing the number of exchanges compared to the conventional technique. Particularly, in the shape of the optical functional layer 12 described above of the present embodiment, the opening (the dimension indicated by A in FIG. 2) of the recess 13a is narrow and the depth (the dimension indicated by C in FIG. 2) is large. The effect is more remarkable.

  From the viewpoint of preventing the surface of the roll mold from corroding after the annular protrusions 22 and the grooves 23 are formed by the above-described cutting, and improving the releasability of the light transmitting portion constituting composition described later, the roll mold The mold surface is preferably plated with chromium or the like.

  Next, a method for manufacturing the optical sheet 10 using the roll mold 20 will be described. FIG. 9 shows a schematic diagram. First, the light transmission part 13 is formed on the substrate 11. That is, as can be seen from FIG. 9, the base material 11 ′ to be the base material layer 11 is inserted between the roll mold 20 and the nip roll 41 disposed so as to face the roll mold 20. At this time, the roll mold 20 and the nip roll 41 are rotated as shown by the arrows in FIG. 9 while supplying the light transmitting portion constituting composition 13 ′ between the base material 11 ′ and the roll mold 20. Thereby, the light transmitting portion constituting composition 13 ′ is filled in the groove 23 formed on the surface of the roll die 20, and the light transmitting portion constituting composition 13 ′ is along the surface shape of the roll die 20. Become.

  Here, as the light transmission part constituting composition 13 ′, for example, a photocurable resin composition in which a reactive dilution monomer (M1) and a photopolymerization initiator (S1) are blended with a photocurable prepolymer (P1). Is preferably used.

  Examples of the photocurable prepolymer (P1) include epoxy acrylate-based, urethane acrylate-based, polyether acrylate-based, polyester acrylate-based, and polythiol-based prepolymers.

  Examples of the reactive dilution monomer (M1) include vinyl pyrrolidone, 2-ethylhexyl acrylate, β-hydroxy acrylate, and tetrahydrofurfuryl acrylate.

  Examples of the photopolymerization initiator (S1) include hydroxybenzoyl compounds (2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, benzoin alkyl ether, etc.), benzoyl Formate compounds (such as methylbenzoylformate), thioxanthone compounds (such as isopropylthioxanthone), benzophenones (such as benzophenone), phosphate compounds (1,3,5-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-) Trimethylbenzoyl) -phenylphosphine oxide and the like, and benzyldimethyl ketal and the like. Among these, the irradiation device for curing the photocurable resin composition and the curability of the photocurable resin composition can be arbitrarily selected. From the viewpoint of preventing coloring of the light transmitting portions 13, 13,..., 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone and bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide.

  The amount of the photopolymerization initiator (S1) contained in the photocurable resin composition is based on the total amount of the light transmission part constituent composition (100% by mass) from the viewpoint of curability and cost of the photocurable resin composition. 0.5 mass% or more and 5.0 mass% or less is preferable. Generally, the photoinitiator is at least partially soluble (eg, at the processing temperature of the resin) and is substantially colorless after polymerization. The photopolymerization initiator may be colored (for example, colored yellow), provided that it is substantially colorless when the light transmissive part constituent composition is cured to form a light transmissive part.

  These photocurable prepolymer (P1), reactive diluent monomer (M1) and photopolymerization initiator (S1) can be used alone or in combination of two or more.

  The light transmitting unit constituting composition sandwiched between the roll mold 20 and the base material 11 ′ and filled therein is irradiated with light from the base material 11 ′ side by the light irradiation device 42. Thereby, the light transmissive portion constituting composition 13 ′ can be cured and its shape can be fixed. And the base material layer 11 and the shape | molded light transmission part 13 are released from the roll metal mold | die 20 with the release roll 43. FIG.

  Next, the light absorption part 14 is formed. In order to form the light absorbing portion 14, first, the light absorbing portion constituting composition is excessively applied to the concave portion 13a. Thereafter, the surplus light absorbing part constituting composition is scraped off with a doctor blade or the like. Then, by irradiating light from the light transmitting portion side to the light absorbing portion constituting composition remaining in the recess 13a, the binder 15 contained in the light absorbing portion constituting composition is cured to form the light absorbing portion 14. it can.

  Although what is used as a binder is not specifically limited, For example, the photocurable resin composition which mix | blended the reactive dilution monomer (M2) and the photoinitiator (S2) with the photocurable prepolymer (P2). Is preferably used.

  Examples of the photocurable prepolymer (P2) include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and butadiene (meth) acrylate.

  Moreover, as a reactive dilution monomer (M2), a vinyl monomer, a (meth) acrylic acid ester monomer, and a (meth) acrylamide derivative are mentioned as a monofunctional monomer, for example. Moreover, (meth) acrylate type thing is mentioned as a polyfunctional monomer.

  Examples of the photopolymerization initiator (S2) include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1 -One, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and the like. Among these, the irradiation device for curing the photocurable resin composition and the curability of the photocurable resin composition can be arbitrarily selected.

  The amount of the photopolymerization initiator (S2) contained in the photocurable resin composition is based on the total amount of the photocurable resin composition from the viewpoint of curability and cost of the photocurable resin composition (100% by mass). ) Is preferably 0.5% by mass or more and 10.0% by mass or less.

  These photocurable prepolymer (P2), reactive diluent monomer (M2), and photopolymerization initiator (S2) can be used alone or in combination of two or more.

  Specifically, a photopolymerizable component composed of urethane acrylate, epoxy acrylate, tripropylene glycol diacrylate and methoxytriethylene glycol acrylate (specifically, photocurable prepolymer (P2) and reactive dilution monomer (M2)). In consideration of the refractive index, the viscosity, the influence on the performance of the optical function layer 12, etc., they are arbitrarily mixed and used.

  Moreover, you may add a silicone, an antifoamer, a leveling agent, a solvent, etc. to an optical absorption part structure composition as an additive as needed.

  The light absorbing particles 16 are preferably light-absorbing colored particles such as carbon black, but are not limited thereto, and are colored particles that selectively absorb a specific wavelength in accordance with the characteristics of image light. May be used. Specific examples include organic fine particles colored with metal salts such as carbon black, graphite, and black iron oxide, dyes, pigments, colored glass beads, and the like. In particular, colored organic fine particles are preferably used from the viewpoints of cost, quality, availability, and the like. More specifically, acrylic cross-linked fine particles containing carbon black, urethane cross-linked fine particles containing carbon black, and the like are preferably used. Such colored particles are usually contained in the light absorbing part constituting composition in a range of 3% by mass to 30% by mass. The average particle diameter of the colored particles is preferably 1.0 μm or more and 20 μm or less. As will be described later, when the light absorbing portion 14 is formed, the light absorbing portion constituting composition containing the colored particles is filled in the recesses 13a between the light transmitting portions 13, and then the excess light is used using a doctor blade. A step of scraping off the absorbent part composition is included. At this time, by using colored particles having an average particle diameter of 1.0 μm or more, it becomes difficult for the colored particles to pass through the gap between the doctor blade and the upper portion of the light transmitting portion 13, and the colored particles are formed on the upper portion of the light transmitting portion 13. Can be prevented from remaining.

  As described above, the optical sheet 10 can be obtained by forming the light transmitting portion 13 and the light absorbing portion 14 on the base material layer 11.

  The optical sheet 10 may be further laminated with layers having other functions as necessary. Specifically, for example, an electromagnetic wave shielding layer, a wavelength filter layer, an antiglare layer, an antireflection layer, a hard coat layer, and the like can be formed by bonding using an adhesive layer. The order of lamination of these layers and the number of laminations are appropriately determined according to the use of the optical sheet. Although any known layer can be applied to each layer, each layer will be described below.

  The electromagnetic wave shielding layer is a layer having a function of shielding electromagnetic waves. As long as the layer has the function, a means for blocking electromagnetic waves is not particularly limited. Examples thereof include a metal mesh formed by a method such as an etching method, a printing method, a vapor deposition method, or a sputtering method.

  The wavelength filter layer is a layer having a function of attenuating and transmitting light of a predetermined wavelength. The light of the wavelength to be attenuated can be selected as needed, but the layer that attenuates / blocks the neon line emitted from the plasma display panel (PDP), attenuates / blocks infrared rays, near infrared rays, and ultraviolet rays. And a layer for correcting a color tone.

  The antiglare layer is a layer having a function of suppressing so-called glare and is sometimes called an antiglare layer or an AG layer.

  The antireflection layer is a layer that is disposed closest to the viewer and has a function of preventing reflection of external light. According to this, it can suppress that external light reflects on the observer side surface of an optical sheet, returns to the observer side, and what is called reflection arises and it becomes difficult to see an image | video.

  The hard coat layer is sometimes called a protective layer or an HC layer. This is a layer in which a film having a function capable of imparting scratch resistance is provided in order to prevent the image display surface from being scratched.

  The adhesive layer is a layer in which an adhesive is disposed. An acrylic adhesive can be mentioned as this adhesive. However, the pressure-sensitive adhesive is not limited to this as long as necessary light transmittance, adhesiveness, and weather resistance can be obtained. Depending on the layer structure, it is desirable to include a UV absorber (benzotriazole type or the like) having an effect of absorbing ultraviolet rays in the pressure-sensitive adhesive in order to prevent deterioration of the pigment. Moreover, a UV absorber, a near-infrared absorber, a neon ray absorber, and a toning pigment may be included in the adhesive layer in the adhesive layer.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.

<Example 1>
In Example 1, a roll mold is formed by forming grooves in a base having a diameter of 400 mm, a width of 1000 mm, and a hard copper plating (Vickers hardness 210 Hv) as a work layer having a thickness of 0.5 mm on the surface. Manufactured. The groove to be cut has a pitch of 45 μm, the cut depth in the groove portion is 84 μm, and the cut depth when forming the outer peripheral portion of the annular protrusion is 10 μm. Further, the rotation speed of the roll substrate was 420 rpm, the cutting speed was 2 μm / rotation, and half was cut, and the rest was cut at 2.5 μm / rotation.
A diamond tip is used as the cutting tip, the apex angle is 3 degrees (the left and right bite angles are the same, 1.5 degrees each), the lateral relief angle is 3 degrees, the front relief angle is 15 degrees, and the bite tip width Was 35 μm. Further, the cut was made obliquely in the direction of 1.5 degrees in the feed direction with respect to the radial direction of the roll base. That is, it is the same as the byte angle.

As a result, it was possible to cut with one diamond tip from the cutting start point to the cutting end point, and to suppress the fall of the annular protrusion at the cutting end point. Specifically, the difference between the prospective angle of the first groove where cutting was started and the prospective angle of the last groove at the end point of cutting was 0.5 degrees.
Here, the prospective angle is the diagonal line in the cross-sectional shape of the groove as shown by φ in FIG. 10 (the line connecting one end of the groove bottom and the corner of the annular protrusion at the diagonal position) in the radial direction of the roll mold. It is the angle formed. That is, if the difference in the prospective angle between the cutting start point and the cutting end point is small, it means that the change in the inclination of the annular protrusion is small and the change in the shape of the groove and the annular protrusion is suppressed to be small.

<Comparative Example 1>
In Comparative Example 1, the cutting direction was the same as Example 1 except that the cutting direction was the same as the radial direction of the roll base. As a result, it was possible to cut with one diamond tip from the cutting start point to the cutting end point, but the difference between the prospective angle of the first groove at which cutting was started and the prospective angle of the last groove at the cutting end point was 3.0. It was a degree. That is, the change of the groove and the annular protrusion was large between the cutting start point and the cutting end point.

DESCRIPTION OF SYMBOLS 10 Optical sheet 11 Base material layer 12 Optical functional layer 13 Light transmission part 14 Light absorption part 15 Binder part 16 Light absorption particle 20 Roll metal mold | die 21 Roll base | substrate 22 Annular protrusion 23 Groove

Claims (7)

A method of manufacturing a roll mold for molding the uneven portion of the optical sheet having an uneven shape,
Rotating a roll base having a layer to be processed formed on the surface, and forming a groove corresponding to the unevenness of the optical sheet with a cutting tool;
In the step of forming the groove, the cutting with the cutting tool is the same angle as the bite angle on the rear side with respect to the moving direction of the bite along the rotation axis of the roll base, among the bite angles of the cutting tool. As described above , the roll mold manufacturing method is performed in a direction approaching the rotation axis of the roll base while moving the cutting tool in a direction along the rotation axis of the roll base. The diameter of the roll base body is more than 300 mm, and is less than 500mm, the roll body rotational speed of 300 r pm or more, roll mold manufacturing method according to claim 1, characterized in that to form the groove below 600rpm .   The roll die manufacturing method according to claim 1 or 2, wherein a cutting speed of the cutting tool is 2 µm / rotation or more and 5 µm / rotation or less.   The roll die according to any one of claims 1 to 3, wherein the cutting tool is retracted after the roll base is rotated once or more in a posture in which the cutting tool has reached the cutting depth. Manufacturing method. The cutting tool is moved along the rotation axis of the roll base so as to alternately cut the bottom of the groove formed in the roll base and the outer peripheral portion which is the tip of the annular protrusion formed between the grooves. The method for manufacturing a roll mold according to any one of claims 1 to 4, wherein the roll mold is moved in a direction . After cutting one of the outer peripheral portions, the cutting tool is pulled back in the radial direction of the roll base, and the cutting tool is moved in a direction along the rotation axis of the roll base to cut the next groove. The pitch of the groove is p (mm), the bite angle on the rear side with respect to the moving direction of the bite along the rotation axis of the roll base is θa1 (degrees), the bottom of the groove to be cut and the cutting When the distance from the movement start position for cutting the tool is t (mm) , the feed amount r (mm), which is the movement amount in the direction along the rotation axis of the roll base, is
r = p / 2− (t · tan (θa1))
The roll metal mold manufacturing method according to claim 5, wherein A roll mold is manufactured by the manufacturing method according to any one of claims 1 to 6,
A step of filling a photocurable material between the roll mold and the base material, and a step of curing the photocurable material by irradiating the photocurable material with light in the filled state. The manufacturing method of the optical sheet containing this.