JP2011197545A - Method for manufacturing anti-glare film manufacturing die, and method for manufacturing anti-glare film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a die for an anti-glare film preventing reduction in visibility caused by generation of discoloration and glare.SOLUTION: The method for manufacturing the die includes a step of forming nickel plating 3 on a surface of a base material 1 for the die, a mirror surface working step of forming a mirror surface 4 having ≤0.1 μm surface roughness by performing cutting working and/or polishing working to the nickel plating, a fine concave part forming step of forming a plurality of fine concave parts 5 in the formed mirror surface by cutting working and a heat treatment step of performing heat treatment to the surface in which the fine concave parts are formed. The cutting working of the plurality of fine concave parts in the fine concave part forming step is performed by using a cutting tool which is linearly moved relatively to a direction parallel to the mirror surface formed in the mirror surface working step and finely reciprocally moved in a direction vertical to the mirror surface formed in the mirror surface working step simultaneously with the linear movement and an average adjacent-most distance a (μm) between the cut fine concave parts and a cutting depth d (μm) satisfy a specific condition.

Description

  The present invention relates to a method for producing a mold for obtaining an antiglare film and a method for producing an antiglare film having excellent antiglare properties.

  In an image display device such as a liquid crystal display, a plasma display panel, a cathode ray tube (CRT) display, an organic electroluminescence (EL) display, and the like, when external light is reflected on the display surface, visibility is significantly impaired. In order to prevent such reflection of external light, TVs and personal computers that emphasize image quality, video cameras and digital cameras used outdoors with strong external light, mobile phones that display using reflected light, etc. The anti-glare film is disposed on the surface of the image display device.

  As a method for producing such an antiglare film, for example, in Japanese Patent Application Laid-Open No. 2007-187852 (Patent Document 1), a substrate is subjected to copper plating or nickel plating, and then polished and sandblasted. A method is described in which a roll having fine irregularities on its surface is produced by applying chrome plating, the irregularities of the roll are transferred to a transparent resin film, and then the film is peeled off.

JP 2007-188792 A

  The antiglare film is required to have antiglare properties, exhibits good contrast when placed on the surface of the image display device, and the entire display surface is whitish due to scattered light when placed on the surface of the image display device. Suppresses the occurrence of so-called “whitening”, which causes the display to become turbid, and the pixel of the image display device and the uneven surface shape of the antiglare film when placed on the surface of the image display device. There is a demand for suppressing the occurrence of so-called “glare” that interferes and results in a luminance distribution that is difficult to see. However, in the method described in Patent Document 1, since an antiglare film is produced using a mold having an uneven shape formed by sandblasting, it is not sufficient in terms of accuracy of the uneven shape in the obtained antiglare film. In particular, since there may be a relatively large uneven shape having a period of 50 μm or more, “glare” is likely to occur.

  Therefore, an object of the present invention is to produce an antiglare film that exhibits excellent contrast while exhibiting excellent antiglare properties, and that prevents deterioration in visibility due to the occurrence of “blink” and “glare”. It is in providing the method of manufacturing the metal mold | die for.

  The method for producing a mold for producing an antiglare film according to the present invention includes a plating step of performing nickel plating on the surface of the mold base, and a cutting and / or processing of the nickel plating applied to the surface of the mold base. A mirror surface processing step for forming a mirror surface having a surface roughness of 0.1 μm or less by polishing, a micro concave portion forming step for forming a plurality of micro concave portions on the formed mirror surface, and a micro concave portion were formed. A heat treatment step of heat-treating the surface, and the cutting of the plurality of fine recesses in the fine recess formation step relatively linearly moves in a direction parallel to the mirror surface formed in the mirror finish processing step, and At the same time, it is performed by a cutting tool that reciprocally moves in a direction perpendicular to the mirror surface formed in the mirror surface machining step, and the average nearest neighbor distance between the micro-recesses to be cut is a (μm), and the cutting depth is d ( μm), the following condition is satisfied.

  In the manufacturing method of the metal mold | die for anti-glare film manufacture of this invention, it is preferable that the processing temperature of the said heat processing process is 200 to 600 degreeC, and processing time is 30 minutes-10 hours.

  In the method for producing a mold for producing an antiglare film according to the present invention, a micro reciprocating movement in a direction perpendicular to the mirror surface formed in the mirror surface machining step of the cutting tool in the fine recess forming step is performed by a piezoelectric element. Is preferred.

  In the method for producing a mold for producing an antiglare film according to the present invention, the plurality of fine concave portions formed in the fine concave portion forming step are formed as a part of a spherical surface, and the radius of the spherical surface is R (μm). It is preferable to satisfy the following conditions.

  In the present invention, the surface on which the fine recesses of the mold manufactured by the above-described method for manufacturing the mold for manufacturing the antiglare film of the present invention are transferred to a transparent resin film, and then the surface on which the micro recesses are formed. The present invention also provides a method for producing an antiglare film, which comprises peeling off a transparent resin film having transferred thereon from a mold.

  According to the present invention, for producing an antiglare film exhibiting excellent contrast while exhibiting excellent antiglare property, and preventing deterioration in visibility due to occurrence of “whit” or “glare”. A mold can be manufactured. In addition, by including the above-described heat treatment step, an effect that a mold for producing an antiglare film having higher hardness can be produced is also exhibited. In addition, the above-described optical performance was excellent by transferring the surface (uneven surface) on which the fine recesses of the mold were formed onto the transparent resin film and then peeling the transparent resin film on which the uneven surface was transferred from the mold. An antiglare film can be obtained.

It is a figure which shows typically a preferable example of the manufacturing method of the metal mold | die for anti-glare film manufacture of this invention. Schematic view of a cutting tool that moves relatively linearly in a direction parallel to the mirror surface formed by the mirror surface machining process, and moves in a reciprocating direction in the direction perpendicular to the mirror surface formed by the mirror surface machining process simultaneously with the linear movement. FIG. It is a figure which shows typically the apparatus for performing the cutting process of a fine recessed part in the flat base material for metal mold | die. It is a figure which shows typically the apparatus for performing the cutting process of a micro recessed part to a cylindrical base material for metal mold | die. It is a schematic diagram for demonstrating the nearest distance a and the cutting depth d between micro recessed parts. It is a figure which shows typically a fine recessed part shape in case a fine recessed part is formed in a part of spherical surface. It is a figure which shows typically the state which has arrange | positioned the fine recessed part regularly. It is a figure which shows typically the state which has arrange | positioned the micro recessed part at random. FIG. 3 is a diagram illustrating an arrangement of fine recesses according to the first embodiment. It is a figure which shows arrangement | positioning of the fine recessed part of Example 2. FIG.

<Method for producing mold for producing antiglare film>
FIG. 1 is a diagram schematically showing a preferred example of a method for producing a mold for producing an antiglare film of the present invention. FIG. 1 schematically shows a cross section of a mold in each step. The method for producing a mold for producing an antiglare film of the present invention basically includes a [1] plating step, a [2] mirror surface processing step, a [3] fine unevenness forming step, and a [4] heat treatment step. Hereinafter, each step will be described in detail with reference to FIG.

[1] Plating Step In the method for producing a mold for producing an antiglare film of the present invention, first, nickel plating 3 is applied to the surface 2 of a substrate (mold substrate) 1 used for the mold. In this way, by applying the nickel plating 3 to the surface 2 of the mold base 1, minute irregularities and voids existing on the mold base 1 are eliminated. Since nickel plating has good machinability, mirror finishing in a subsequent mirror finishing process and cutting of fine recesses in a fine recess forming process are facilitated.

  Nickel used in the plating process may be a pure metal or may be an alloy mainly composed of nickel. Therefore, “nickel” in the present specification means to include nickel and a nickel alloy. is there. Among these, the nickel plating is preferably nickel alloy plating containing nickel as a main component and phosphorus, boron, tungsten or the like as subcomponents. Nickel plating may be performed by electrolytic plating or electroless plating, but electroless plating is usually employed.

  When nickel plating is performed, if the plating layer is too thin, the influence of the underlying surface cannot be completely eliminated. Therefore, the thickness is preferably 50 μm or more. Although the upper limit of the plating layer thickness is not critical, generally about 500 μm is sufficient from the viewpoint of cost and the like.

  In addition, in the manufacturing method of the metal mold | die for anti-glare film manufacture of this invention, aluminum, an iron base material etc. are mentioned from a viewpoint of cost as a metal material used suitably for formation of the base material 1 for metal mold | die, Furthermore, From the viewpoint of low thermal conductivity, stainless steel, titanium and the like can be mentioned. Aluminum, iron, titanium, and the like herein may be pure metals, but are preferably alloys mainly composed of aluminum, iron, titanium, and the like from the viewpoint of cost, hardness, machinability, and the like.

  In addition, the shape of the mold base 1 is not particularly limited as long as it is an appropriate shape that has been conventionally employed in this field, and may be a flat plate or a cylindrical or cylindrical roll. May be. If a mold is produced using a roll-shaped substrate, there is an advantage that the antiglare film can be produced in a continuous roll shape.

[2] Mirror surface processing step In the subsequent mirror surface processing step, the surface roughness of the nickel plating 3 formed on the surface 2 of the mold base 1 in the plating step described above is 0.1 μm by cutting and / or polishing. The following mirror surface 4 is formed. This is because metal plates and metal rolls that serve as base materials are often subjected to machining such as cutting and grinding in order to achieve the desired accuracy, and as a result, machine marks remain on the base material surface. This is because even when nickel plating is applied, those processed marks may remain, and when the plating is left as it is, undulations exist on the surface and a completely smooth surface cannot be obtained. In other words, when such a deep processing mark remains or a surface having waviness on the surface is subjected to a fine recess forming process described later, due to the influence of the processing eyes and waviness, the designed micro recess is cut by machining. Cannot be formed. FIG. 1 (a) shows a state in which a surface 2 of a plate-shaped mold substrate 1 is subjected to nickel plating 3 in a plating step and further has a surface 4 which is mirror-polished in a mirror finishing step. This is shown schematically.

  The method of forming the mirror-polished surface (mirror surface) 4 on the nickel plating 3 is not particularly limited, and cutting and / or polishing can be used. When performing mirror surface machining by cutting, it is preferable to form the mirror surface 4 on the nickel plating 3 by using an ultra-precision lathe and performing mirror surface cutting using a cutting tool. The material and shape of the cutting tool are not particularly limited, and carbide tools, CBN tools, ceramic tools, diamond tools, etc. can be used, but diamond tools are preferably used from the viewpoint of processing accuracy. In addition, when mirror finishing is performed by polishing, conventionally known methods such as mechanical polishing, electrolytic polishing, and chemical polishing can be used. Examples of the mechanical polishing method include super finishing, lapping, fluid polishing, and buff polishing. Further, in order to obtain a predetermined surface roughness, cutting and polishing can be combined. The surface roughness of the mirror surface after processing is preferably such that the center line average roughness Ra in accordance with the provisions of JIS B 0601 is 0.1 μm or less, and more preferably 0.05 μm or less. If the center line average roughness Ra after polishing is larger than 0.1 μm, the influence of the surface roughness remains on the cutting in the fine recess forming step, which is not preferable. In addition, the lower limit of the center line average roughness Ra is not particularly limited, and there is no limit in particular because there is a natural limit from the viewpoint of processing time and processing cost.

[3] Fine concave portion forming step In the subsequent fine concave portion forming step, a plurality of fine concave portions 5 are formed by cutting using a cutting tool on the mirror surface 4 formed by the mirror surface processing step. FIG. 1B schematically shows a state in which the fine recesses 5 are formed on the surface 4 of the substrate 1.

  The cutting of the plurality of fine recesses in the fine recess forming step is relatively linearly moved in a direction 6 parallel to the mirror surface 4 formed by the mirror finishing step, and is formed by the mirror finishing step simultaneously with the linear movement. It is preferable that the cutting tool 8 is reciprocally moved in a direction 7 perpendicular to the mirror surface 4. FIG. 2 schematically shows the state of the cutting tool 8 that relatively linearly moves in a direction 6 parallel to the mirror surface 4 and that reciprocally moves in a direction 7 perpendicular to the mirror surface 4 simultaneously with the linear movement. In FIG. 2, since the mold base 1 is shown fixed, only the cutting tool 8 performs linear movement and minute reciprocation in the vertical direction. By performing such a cutting process, the fine recesses 5 can be formed on the mold base 1 with a desired pitch and depth with high accuracy.

  An apparatus for performing such a cutting process is schematically shown in FIGS. FIG. 3 shows an apparatus in the case where the mold base 1 has a flat plate shape, and a first direction parallel to the mirror surface 4 formed on the nickel plating formed on the installed mold base 1. (Hereinafter referred to as X direction), a processing table 9 that is movable in a second direction (hereinafter referred to as Y direction) parallel to the mirror surface 4 and perpendicular to the X direction, and the surface of the mold base A Z-axis drive unit 10 movable in a vertical direction (hereinafter referred to as a Z direction), a micro-reciprocating drive mechanism unit 11 attached to the Z-axis drive unit 10, and a micro-reciprocating drive mechanism unit 11 It has a cutting tool 8 attached. The mold base 1 is placed on the machining table 9 and the fine reciprocating drive mechanism 11 is moved in the Z-axis direction by using the Z-axis drive unit 10 of the machining apparatus. The base material 1 is brought close to a predetermined amount that can be processed. Next, the mold base 1 is moved at a constant speed by driving the processing table in the X direction. At that time, the cutting tool 8 is reciprocated by a predetermined minute amount in the Z direction using the minute reciprocating drive mechanism 11. Thereby, the front-end | tip part of the cutting tool 8 moves so that the tool movement locus | trajectory 12 shown in FIG. 2 may be drawn with respect to the base material 1 for metal mold | dies, and the fine recessed part 5 can be formed with high precision.

  In FIG. 4, the apparatus in case the base material 1 for metal mold | dies is cylindrical shape was shown typically. 4 includes a support mechanism 13 that supports both ends of a roll that is a cylindrical mold base, and a motor 14 that rotates a roll that is a cylindrical mold base around its longitudinal axis. (The rotation direction is hereinafter referred to as the X direction), the Y-axis drive unit 15 movable in the longitudinal direction (hereinafter referred to as the Y direction), and the surface of the mold base attached to the Y-axis drive unit Z-axis drive unit 10 movable in a direction perpendicular to the Z-axis (hereinafter referred to as Z direction), micro-reciprocating drive mechanism unit 11 attached to Z-axis drive unit 10, and micro-reciprocating drive mechanism unit 11 Has a cutting tool 8 attached to the. The cylindrical mold base 1 is installed on the support mechanism 13, and the micro reciprocating drive mechanism 11 is moved in the Z-axis direction by using the Z-axis drive unit 10 of the processing apparatus. The mold base 1 is brought close to a predetermined amount that can be processed. Next, the mold base 1 is rotated in the X direction at a constant speed by driving the motor 14. At that time, the cutting tool 8 is reciprocated by a predetermined minute amount in the Z direction using the minute reciprocating drive mechanism 11. Thereby, the front-end | tip part of the cutting tool 8 moves so that the tool movement locus | trajectory 12 shown in FIG. 2 may be drawn with respect to the base material 1 for metal mold | dies, and the fine recessed part 5 can be formed with high precision.

  The drive source of the micro reciprocating drive mechanism 11 is not particularly limited as long as the cutting tool can be micro-driven, and piezoelectric elements, magnetostrictive elements, ultrasonic oscillators, etc. can be used. It is preferable to use a piezoelectric element from the viewpoint of processing speed. The material of the cutting tool to be attached to the micro reciprocating drive mechanism 11 is not particularly limited, and carbide tools, CBN tools, ceramic tools, diamond tools, etc. can be used. It is preferable to use a byte.

  In the method for producing a mold for producing an antiglare film of the present invention, an average nearest neighbor distance a (μm) between a plurality of fine recesses formed by cutting and a cutting depth d (μm) satisfy the following conditions. This is one of the characteristics.

  Here, the average nearest neighbor distance between the fine recesses is the average value of the distance between the deepest part of the fine recess and the deepest part of the fine recess closest to the fine recess when attention is paid to one fine recess. is there. FIG. 5 schematically shows the closest distance between the fine recesses. The distance aAB between the deepest portions 17 of the fine recess B closest to the noted fine recess A is the closest distance of the fine recess A. The cutting depth d of the fine recess is a distance from the highest portion 16 on the surface where a plurality of fine recesses are formed in the fine recess forming process to the deepest portion 17 of the fine recess.

  Here, as will be described later, the surface of the anti-glare film (the surface with fine irregularities) onto which the surface having the fine concave portions of the mold (uneven surface) has been transferred suppresses the glare generated by the surface with such fine irregularities. Therefore, it is preferable not to include a long period component of 50 μm or more. However, an excellent antiglare performance is not exhibited on a fine uneven surface containing only a short period component of 10 μm or less. Therefore, the fine uneven surface of the antiglare film preferably includes a surface shape having a period of 10 to 50 μm as a main component in order to sufficiently prevent glare while exhibiting a sufficient antiglare effect. Therefore, it is preferable that the metal mold | die for manufacturing the glare-proof film which fully prevents glare while expressing sufficient anti-glare effect contains the surface shape with a period of 10-50 micrometers as a main component. When the average nearest neighbor distance a exceeds 40 μm, a fine uneven surface shape having a period of 50 μm or more is likely to be formed in the obtained mold, and as a result, the obtained antiglare film is used as a high-definition image display device. Glare will occur when placed on the surface. Moreover, when the average nearest neighbor distance a is less than 10 μm, the obtained mold contains a lot of short-period components having a period of 10 μm or less, and the resulting anti-glare film does not exhibit excellent anti-glare performance. .

  In addition, the fine uneven surface of the anti-glare film has an average inclination angle θ of 3 ° or less of the fine uneven surface perpendicular to the main plane of the anti-glare film from the viewpoint of suppressing whiteness generated by the fine uneven surface. Preferably there is. Further, from the viewpoint of developing antiglare properties, the average inclination angle θ is preferably 0.5 ° or more. Here, the average inclination angle θ can be estimated by the following equation from the average nearest neighbor distance a and the cutting depth d.

  Therefore, the ratio d / a between the cutting depth d and the average nearest neighbor distance a is preferably tan (0.5 °) /2=0.444 or more, and tan (3 °) /2=0.026 or less. When the ratio d / a is less than 0.0044, the average inclination angle of the resulting mold is less than 0.5 °, and the resulting antiglare film does not exhibit a sufficient antiglare effect, which is not preferable. On the other hand, when the ratio d / a exceeds 0.026, the average inclination angle of the obtained mold exceeds 3 °, and the resulting antiglare film is not preferable.

  In addition, in order for the antiglare film to suppress whiteness and to exhibit excellent antiglare properties, the plurality of fine concave portions formed in the fine concave portion forming step may be formed by a part of a spherical surface. preferable. When the fine concave portion is formed of a part of a spherical surface, the fine concave shape can be schematically represented as shown in FIG. When the radius of the spherical surface at this time is R (μm), the average inclination angle θ can be estimated by the following equation.

  Therefore, the ratio d / R between the cutting depth d and the radius R of the spherical surface is preferably 1−cos (1 °) = 0.00015 or more, and preferably 1−cos (6 °) = 0.0005 or less. When the ratio d / R is less than 0.00015, the average inclination angle of the obtained mold is less than 0.5 °, and the obtained antiglare film does not exhibit a sufficient antiglare effect, which is not preferable. On the other hand, when the ratio d / R exceeds 0.0055, the average inclination angle of the mold to be obtained exceeds 3 °, and the resulting antiglare film is not preferable.

  Moreover, it is preferable that the obtained anti-glare film is 5% or less on a flat surface, that is, a surface having an inclination angle of about 0 °. This is because when the flat surface exceeds 5%, sufficient antiglare property is not exhibited. The flat surface ratio α can be estimated by the following equation from the average inclination angle θ, the radius R of the spherical surface, and the average nearest neighbor distance a.

  Therefore, the ratio a / R between the average nearest neighbor distance a and the radius R of the spherical surface preferably satisfies the following conditions.

  In order to form a plurality of fine concave portions formed in the fine concave portion forming step with a part of a spherical surface having a radius R, using a cutting tool having a nose radius R, the moving speed or rotational speed in the X direction, and the Z direction The fine reciprocating movement of the cutting tool may be controlled, and the machining locus may be set so that the moving locus of the cutting tool tip portion draws a part of an arc of radius R.

  The plurality of fine concave portions formed in the fine concave portion forming step may be formed by regularly arranging them, or may be arranged at random. Since interference colors due to the arrangement of the fine recesses may occur, it is preferable to arrange them randomly. FIG. 7 schematically shows the case where the fine recesses are regularly arranged. FIG. 8 schematically shows the case where the fine concave portions are randomly arranged.

[4] Heat treatment step In the method for producing a mold for producing an antiglare film of the present invention, in the subsequent heat treatment step, the surface 5 on which the fine recesses are formed is heat treated. As a result, the surface hardness and wear resistance of the mold can be improved, and the durability of the mold can be improved. Thus, in the manufacturing method of the metal mold | die for anti-glare film manufacture of this invention, when manufacturing an anti-glare film using the obtained metal mold | die by including the heat processing process, the surface of a metal mold | die is used during use. It is possible to prevent the unevenness from being worn away and the mold from being damaged, and more antiglare films can be produced using one mold.

  The heat treatment temperature in the heat treatment step of the present invention is preferably 200 to 600 ° C, and more preferably 250 to 550 ° C. When the heat treatment temperature is less than 200 ° C., sufficient surface hardness and wear resistance may not be obtained. On the other hand, when the heat treatment temperature exceeds 600 ° C., sufficient surface hardness may not be obtained, and the mold may be deformed.

  The heat treatment time in the heat treatment step of the present invention varies depending on the treatment environment and treatment temperature, but is preferably 30 minutes to 10 hours, and more preferably 1 hour to 5 hours. If the heat treatment time is less than 30 minutes, there is a possibility that sufficient surface hardness and wear resistance may not be obtained, and the effect does not change even if the heat treatment step is carried out for more than 10 hours, resulting in decreased productivity. To do.

  If the heat treatment step is performed in an oxygen-containing atmosphere, the mold may rust due to oxidation and discoloration, and unevenness may occur in the antiglare film produced using this. Therefore, in order to reduce the influence of oxidation during such heat treatment, the heat treatment step is preferably performed in a degassed state or in an inert gas atmosphere such as nitrogen or argon.

<Method for producing antiglare film>
The present invention also provides a method for producing an antiglare film using the mold obtained by the above-described mold production method of the present invention. That is, the method for producing an antiglare film of the present invention includes a step of transferring a surface on which a fine concave portion of the mold produced by the method for producing a mold of the present invention is formed to a transparent resin film, and a fine concave portion of the mold. And a step of peeling the transparent resin film having the transferred surface from the mold. By such a method for producing an antiglare film of the present invention, an antiglare film exhibiting preferable optical properties is suitably produced.

  The transfer to the mold-shaped film is preferably performed by embossing. Examples of the embossing include a UV embossing method using a photocurable resin and a hot embossing method using a thermoplastic resin. Among these, the UV embossing method is preferable from the viewpoint of productivity.

  The UV embossing method forms a photocurable resin layer on the surface of a transparent resin film, and cures the photocurable resin layer while pressing it against the surface on which the fine concave portions of the mold are formed. This is a method in which the surface on which is formed is transferred to the photocurable resin layer. Specifically, an ultraviolet curable resin is applied on the transparent resin film, and ultraviolet rays are applied from the transparent resin film side in a state where the applied ultraviolet curable resin is in close contact with the surface on which the fine concave portions of the mold are formed. Irradiation is performed to cure the ultraviolet curable resin, and then the shape of the mold is transferred to the ultraviolet curable resin by peeling the transparent resin film on which the cured ultraviolet curable resin layer is formed from the mold.

  When the UV embossing method is used, the transparent resin film may be a substantially optically transparent film. For example, a triacetyl cellulose film, a polyethylene terephthalate film, a polymethyl methacrylate film, a polycarbonate film, or a norbornene compound is used as a monomer. And a resin film such as a solvent cast film of thermoplastic resin such as amorphous cyclic polyolefin and an extruded film.

  Further, the type of the ultraviolet curable resin in the case of using the UV embossing method is not particularly limited, but a commercially available appropriate one can be used. It is also possible to use a resin that can be cured by visible light having a wavelength longer than that of ultraviolet rays by combining an ultraviolet curable resin with an appropriately selected photoinitiator. Specifically, polyfunctional acrylates such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate are used singly or as a mixture of two or more thereof and Irgacure 907 (manufactured by Ciba Specialty Chemicals). ), Irgacure 184 (manufactured by Ciba Specialty Chemicals), and a photopolymerization initiator such as Lucillin TPO (manufactured by BASF) can be suitably used.

  On the other hand, the hot embossing method is a method in which a transparent resin film formed of a thermoplastic resin is pressed against a mold in a heated state, and the surface shape of the mold is transferred to the transparent resin film. The transparent resin film used in the hot embossing method may be any material as long as it is substantially transparent. For example, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, triacetyl cellulose, norbornene compounds are used as monomers. A solvent cast film or an extruded film of a thermoplastic resin such as amorphous cyclic polyolefin can be used. These transparent resin films can also be suitably used as a base film for applying the ultraviolet curable resin in the UV embossing method described above.

  The anti-glare film produced using the mold obtained by the production method of the present invention is formed by controlling the fine concavo-convex surface with high precision, so that it exhibits sufficient anti-glare properties and is also whiteish. It does not occur, and no glare occurs even when it is arranged on the surface of the image display device, so that high contrast is exhibited.

  As described above, in the method for producing a mold for an antiglare film of the present invention, while exhibiting excellent antiglare properties, a good contrast is exhibited, and the visibility is lowered due to the occurrence of “blink” and “glare”. A mold for producing a prevented antiglare film can be produced. In addition, by including the above-described heat treatment step, an effect that a mold for producing an antiglare film having higher hardness can be produced is also exhibited.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

<Example 1>
Electroless nickel containing 92% elemental nickel as the main component and 8% phosphorus elemental as a minor component on the surface of stainless steel 100mm long x 100mm wide (STAVAX (trade name) manufactured by Uddeholm Co., Ltd.) A plated one was prepared. The thickness of the electroless nickel plating was set to be about 100 μm. The electroless nickel plating surface was mirror finished by cutting. On this mirror-finished electroless nickel plated surface, a plurality of fine recesses are cut in the arrangement shown in FIG. 9 so that the closest distance between the fine recesses is 25 μm and the cutting depth is 0.6 μm. A was produced. Here, the cutting process is performed by placing the mold base on a processing table that moves in the X and Y directions, and attaching the diamond tool having a nose radius of 143 μm to a micro reciprocating drive mechanism that is driven by a piezoelectric element. The substrate was moved in the X direction at a constant speed, and at the same time, the cutting tool was reciprocated in the Z direction by a predetermined minute amount. The fine recess was cut so as to be a part of a spherical surface having a radius of 143 μm. The electroless nickel surface with the fine recesses was heat-treated at 300 ° C. for 2 hours in an argon atmosphere.

A photocurable resin composition GRANDIC 806T (manufactured by Dainippon Ink & Chemicals, Inc.) is dissolved in ethyl acetate to obtain a 50% strength by weight solution. Further, a photopolymerization initiator, Lucillin TPO (manufactured by BASF). Chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) was added in an amount of 5 parts by weight per 100 parts by weight of the curable resin component to prepare a coating solution. This coating solution was applied onto a triacetyl cellulose (TAC) film having a thickness of 80 μm so that the coating thickness after drying was 10 μm, and was dried in a dryer set at 60 ° C. for 3 minutes. The film after drying was pressed and adhered to the surface of the mold A obtained in advance with a rubber roll so that the photocurable resin composition layer was on the mold side. In this state, light from a high-pressure mercury lamp with an intensity of 20 mW / cm ² was irradiated from the TAC film side so that the amount of light in terms of h-line was 200 mJ / cm ² to cure the photocurable resin composition layer. Thereafter, the TAC film was peeled off from the mold together with the cured resin to produce a transparent antiglare film A composed of a laminate of the cured resin having a fine uneven surface and the TAC film.

<Example 2>
A mold B is manufactured in the same manner as in Example 1 except that a plurality of fine recesses are cut in the arrangement shown in FIG. 10 so that the closest distance between the fine recesses is 40 μm and the cutting depth is 0.6 μm. did. An antiglare film B was produced in the same manner as in Example 1 except that the obtained mold B was used.

<Comparative Example 1>
The surface of a 200 mm diameter iron roll (STKM13A by JIS) was prepared by applying copper ballad plating. Copper ballad plating consists of a copper plating layer / thin silver plating layer / surface copper plating layer, and the thickness of the entire plating layer was set to be about 200 μm. The copper-plated surface is mirror-polished, and the polished copper-plated surface is blasted (made by Fuji Seisakusho) using zirconia beads TZ-SX-17 (manufactured by Tosoh Corp., average particle size: 20 μm). ) Was blasted at a blast pressure of 0.09 MPa (gauge pressure, the same applies hereinafter) and a bead usage amount of 8 g / cm ² (a used amount per 1 cm ² of surface area of the roll, the same applies hereinafter) to give unevenness to the surface. The resulting copper-plated iron roll with unevenness was subjected to chrome plating to produce a metal mold C. At this time, the chromium plating thickness was set to 6 μm. An antiglare film C was produced in the same manner as in Example 1 except that the obtained mold C was used.

<Comparative example 2>
A mold D was produced in the same manner as in Example 1 except that the heat treatment was not performed on the electroless nickel surface on which the fine recesses were formed.

<Evaluation test 1>
The surface shape of each mold obtained in Example 1, Example 2 and Comparative Example 1 was evaluated. The surface shape was measured using a confocal microscope PL μ2300 (manufactured by Sensofar). At the time of measurement, the magnification of the objective lens was 50 times. Based on the measurement data, the arithmetic average height Pa, the average length PSm, and the maximum cross-sectional height Pt were calculated by calculating in accordance with JIS B 0601. Further, the average inclination angle θ and the maximum inclination angle θmax of each mold surface were calculated from the cross-sectional curve obtained by the measurement. The results are shown in Table 1 together with the mold production conditions.

<Evaluation Test 2>
About each obtained anti-glare film, the following optical characteristics and anti-glare performance were evaluated.

(1) Evaluation of optical properties 1: Measurement of haze The haze of the antiglare film was measured by a method defined in JIS K7136. Specifically, haze was measured using a haze meter HM-150 type (manufactured by Murakami Color Research Laboratory) compliant with this standard. In order to prevent the anti-glare film from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent pressure-sensitive adhesive so that the uneven surface becomes the surface. In general, when haze increases, an image becomes dark when applied to an image display device, and as a result, front contrast tends to decrease. Therefore, a lower haze is preferable.

(2) Evaluation of optical characteristics 2: Measurement of transmission definition The transmission definition was measured by a method defined in JIS K 7105. Specifically, the transmission clarity of the antiglare film was measured using an image clarity measuring device ICM-IDP (manufactured by Suga Test Instruments Co., Ltd.) compliant with this standard. In this standard, four types of optical combs are used for measuring the image definition: the ratio of the width of the dark part to the bright part is 1: 1 and the widths are 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm. Is stipulated. The sum of the image sharpness measured using these four types of optical combs was called the transmission sharpness. In this definition, the maximum value of the transmission definition is 400%. A larger transmission definition according to this definition is preferable. If the transmission clarity is low, the image tends to become unclear when it is placed on the image display device, and glare tends to occur, which is not preferable. Therefore, the transmission definition is preferably 200% or more, and more preferably 300% or more. At the time of evaluation, as in the case of haze measurement, in order to prevent warping of the antiglare film, it is bonded to a glass substrate so that the uneven surface becomes the surface using an optically transparent adhesive. And used for measurement. In this state, light was incident from the glass substrate side and measurement was performed.

(3) Evaluation of optical characteristics 3: Measurement of 60 degree glossiness The 60 degree glossiness was measured by a method defined in JIS Z 8741. Specifically, the glossiness of the antiglare film was measured using a gloss meter PG-1M (manufactured by Nippon Denshoku Industries Co., Ltd.) compliant with this standard. Also in this case, in order to prevent warping of the antiglare film and to prevent reflection from the back surface, an optically transparent adhesive is used, and the antiglare film has a thickness of 2 mm so that the uneven surface becomes the surface. After being pasted on the black acrylic resin plate, it was subjected to measurement. In this state, light was incident from the antiglare film side and measurement was performed. Generally, when the glossiness at 60 degrees is small, it means that the sample surface is cloudy, and as a result, whitening is likely to occur. Therefore, it is preferable that the glossiness is high. However, if the glossiness is too high, reflection occurs and the antiglare property is lowered. Therefore, a value of about 30 to 90% is preferable.

(4) Evaluation of anti-glare performance 1: Visual evaluation of reflection In order to prevent reflection from the back surface of the anti-glare film, the anti-glare film is bonded to the black acrylic resin plate so that the uneven surface becomes the surface, Visual observation was performed from the uneven surface side in a bright room with a fluorescent lamp, and the presence or absence of reflection of the fluorescent lamp was visually evaluated in three stages according to the following criteria.

1: Reflection is not observed 2: Reflection is slightly observed 3: Reflection is clearly observed (5) Evaluation of anti-glare performance 2: Visual evaluation of whitish reflection from the back of the anti-glare film In order to prevent this, the antiglare film is bonded to the black acrylic resin plate so that the uneven surface becomes the surface, and visually observed from the uneven surface side in a bright room with a fluorescent lamp, the degree of whiteness is observed. Visually, it was evaluated in three stages according to the following criteria.

1: No whitening is observed 2: Some whitening is observed 3: Whiteness is clearly observed Table 2 shows the results. In Table 2, for example, the breakdown of the transmission clarity of Example 1 is as follows.

Transmission sharpness 0.125 mm optical comb: 48.1%
0.5mm optical comb: 73.2%
1.0 mm optical comb: 79.8%
2.0mm optical comb: 80.2%
Total 281.3%

  From the results shown in Table 1, it was found that the mold produced by the production method of the present invention was formed by appropriately controlling the inclination angle of the surface irregularity shape. Moreover, from the results shown in Table 2, the antiglare film obtained from the production method of the present invention showed excellent antiglare performance. The anti-glare film A that satisfies all the preferable requirements of the present invention has achieved sufficient anti-glare performance and prevention of whitishness. In addition, since the transmission definition is high, no glare occurs even when it is arranged in the image display device. On the other hand, the anti-glare film B in which the ratio a / R does not satisfy the preferable requirements of the present invention showed prevention of whitening and high transmission clarity, but slight reflection occurred. This is because, as described above, since the ratio a / R does not satisfy the requirements of the present invention, there are many flat surfaces in the mold B and the antiglare film B obtained therefrom. On the other hand, the mold C produced by a manufacturing method different from that of the present invention was not able to control the inclination angle of the surface concavo-convex shape, and whitish was clearly observed.

<Evaluation Test 3>
The Vickers hardness of each mold obtained in Example 1, Example 2 and Comparative Example 2 was measured. Vickers hardness was measured according to JIS Z 2244. The results are shown in Table 3.

  From the results shown in Table 3, in Examples 1 and 2 where heat treatment was performed, higher hardness was obtained than in Comparative Example 2 where heat treatment was not performed. The high hardness obtained by the heat treatment improves the durability, reduces the unevenness of the unevenness and reduces the risk of damage to the mold.

  DESCRIPTION OF SYMBOLS 1 Mold base material, 2 Mold base surface, 3 Nickel plating, 4 Mirror surface, 5 Fine recess, 6 Mirror surface parallel direction, 7 Mirror surface perpendicular direction, 8 Cutting tool, 8a Cutting tool edge , 9 Machining table, 10 Z-axis drive unit, 11 Micro-reciprocating drive mechanism unit, 12a Trajectory of cutting tool tip, 12b Trajectory of cutting tool, 13 Cylindrical mold support mechanism, 14 Cylindrical metal Motor for rotating the mold, 15 Y-axis drive unit, 16 highest part of the surface on which the fine concave part is formed, 17 deepest part of the fine concave part, A one fine concave part of interest, B the finest adjacent to the fine concave part A Concave part, aAB Distance between deepest part of fine concave part A and fine concave part B.

Claims (5)

A plating process for applying nickel plating to the surface of the mold substrate;
A mirror finishing step of forming a mirror surface having a surface roughness of 0.1 μm or less by cutting and / or polishing nickel plating applied to the surface of the mold base;
A fine recess forming step of forming a plurality of fine recesses on the formed mirror surface by cutting;
A heat treatment step of heat treating the surface on which the fine recesses are formed,
The mirror surface formed in the mirror-finishing step simultaneously with the linear movement, in which the cutting of the plurality of minute recesses in the fine-recess forming step relatively linearly moves in a direction parallel to the mirror surface formed in the mirror-finishing step. Is performed by a cutting tool that reciprocally moves in a direction perpendicular to the
A method for producing a mold for producing an antiglare film, wherein the following conditions are satisfied when an average nearest neighbor distance between fine recesses to be cut is a (μm) and a cutting depth is d (μm).

  The manufacturing method according to claim 1, wherein a processing temperature of the heat treatment step is 200 ° C to 600 ° C, and a processing time is 30 minutes to 10 hours.   The manufacturing method according to claim 1 or 2, wherein the micro reciprocating movement of the cutting tool in the fine recess forming step in a direction perpendicular to the mirror surface formed in the mirror finishing step is performed by a piezoelectric element. The plurality of fine concave portions formed in the fine concave portion forming step are formed by a part of a spherical surface, and satisfy the following condition when the radius of the spherical surface is R (μm). Manufacturing method.

  A surface of the mold manufactured by the method according to any one of claims 1 to 4 is transferred to a transparent resin film, and then the surface of the mold having the micro recesses is transferred. A method for producing an antiglare film, comprising peeling from a mold.

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