JP2009107088A - Manufacturing method for die, and manufacturing method for optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a die having a plurality of rows of fine grooves precisely formed, and also to provide a manufacturing method for an optical element. <P>SOLUTION: The die having the plurality of rows of grooves formed on its surface is obtained by cutting a workpiece made of a metal having a 0.6 or more average value r<SB>av</SB>(=(r<SB>0</SB>+2×r<SB>45</SB>+r<SB>90</SB>)/4) of Lankford values r<SB>0</SB>, r<SB>45</SB>, and r<SB>90</SB>in the directions of 0°, 45°, and 90° against the rolling direction, or a metal having a work hardening index of 0.2-1.0, by using a diamond bite, in which grooves going through from a face of an edge to a flank side of the edge are formed on a flank and its tip curvature of the edge is 50 nm to 5 μm. The optical element having the plurality of rows of grooves on the surface thereof is obtained by transcribing the shape of the plurality of rows of grooves on a transparent resin molding body by using the die. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mold manufacturing method and an optical element manufacturing method. More specifically, a mold manufacturing method in which fine plural rows of grooves are precisely formed, and an optical element in which plural rows of grooves are formed, including a step of transferring using the mold obtained by the manufacturing method. It relates to the manufacturing method.

As a method of cutting a workpiece using a single crystal diamond tool to form a plurality of rows of grooves, a single groove is formed by cutting with a tool having a sharp tip, the tool is moved by a pitch P, and then There is known a method of sequentially repeating the formation of a single groove by a single cutting.
Further, as described in Patent Document 1, in a processing method of cutting a workpiece using a single crystal diamond tool, a plurality of fine grooves formed on the single crystal diamond tool are collectively transferred to the workpiece. Also known is a method of processing a fine groove. However, the conventional method has a problem that it is difficult to manufacture a large-area mold because the shape of the groove formed at the tip of the diamond tool changes as the workpiece cutting amount increases.
JP 2004-188511 A

  An object of the present invention is to provide a method for manufacturing a large-area mold in which fine rows of grooves are precisely formed.

As a result of intensive studies to achieve the above object, the present inventor has formed a plurality of grooves formed on the flank face from the scooping face of the blade, and the radius of curvature of the blade tip is 50 nm to 5 μm. The average value r _av (= (r ₀ + 2 × r ₄₅ + r ₉₀ ) of the _rankford values r ₀ , r ₄₅ , and r _{90 in} the 0, 45, and 90 degrees directions with respect to the rolling direction. / 4) By cutting a workpiece made of a metal having a value of 0.6 or more or a work hardening index of 0.2 to 1.0, it is possible to manufacture a mold in which fine multiple rows of grooves are precisely formed. I found. The present invention has been further studied and completed based on this finding.

That is, the present invention includes the following aspects.
(1) Using a diamond tool having a plurality of grooves formed on the flank surface from the scooping surface of the blade and having a radius of curvature of 50 nm to 5 μm at the tip of the blade,
Cutting a workpiece made of a metal having a Rankford average value r _av of 0.6 or more represented by formula (1) or a metal having a work hardening index of 0.2 to 1.0,
A method for manufacturing a mold in which a plurality of rows of grooves are formed.
r _av = (r ₀ + 2 × r ₄₅ + r ₉₀ ) / 4 Formula (1)
(Where r ₀ is the Rankford value in the 0 degree direction with respect to the rolling direction, r ₄₅ is the Rankford value in the 45 degree direction with respect to the rolling direction, and r ₉₀ is the Rankford value in the 90 degree direction with respect to the rolling direction. Value.)
(2) The mold manufacturing method according to (1), wherein a pitch of grooves formed on the flank face of the diamond tool is 100 nm to 20 μm.
(3) The method for manufacturing a mold according to (1) or (2), wherein a cutting edge angle of the diamond tool is 70 to 90 degrees.
(5) The groove formed on the flank of the diamond tool is formed by irradiating a focused ion beam from the flank to the scooping surface, and is any one of (1) to (3) The manufacturing method of the metal mold | die as described in.
(6) The mold manufacturing method according to (4), wherein an angle formed by an incident direction of the focused ion beam and the flank is 10 degrees or less.

(7) Using a diamond tool having a plurality of grooves formed on the flank face from the scooping face of the blade on the flank face and having a radius of curvature of the blade tip of 50 nm to 5 μm,
By a method including cutting a workpiece made of a metal having a Rankford average value r _av of 0.6 or more represented by formula (1) or a metal having a work hardening index of 0.2 to 1.0, a plurality of rows are formed. Get a mold with grooves,
A method of manufacturing an optical element in which a plurality of rows of grooves are formed, the method including the step of transferring the shape of the plurality of rows of grooves to a transparent resin molding using the mold.
r _av = (r ₀ + 2 × r ₄₅ + r ₉₀ ) / 4 Formula (1)
(Where r ₀ is the Rankford value in the 0 degree direction with respect to the rolling direction, r ₄₅ is the Rankford value in the 45 degree direction with respect to the rolling direction, and r ₉₀ is the Rankford value in the 90 degree direction with respect to the rolling direction. Value.)

  According to the mold manufacturing method of the present invention, it is possible to easily manufacture a mold in which fine plural rows of grooves are precisely formed. With the mold, a resin molded body (such as an optical element) having a plurality of fine rows of grooves can be easily obtained.

The mold manufacturing method of the present invention is a diamond tool having a plurality of grooves formed on the flank face from the scooping face of the blade on the flank face, and having a radius of curvature of the blade tip of 50 nm to 5 μm in the rolling direction. The average value r _av (= (r ₀ + 2 × r ₄₅ + r ₉₀ ) / 4) of rankford values r ₀ , r ₄₅ , and r _{90 in} the directions of 0 °, 45 °, and 90 ° is 0.6. This includes cutting a workpiece made of the above metal or a metal having a work hardening index of 0.2 to 1.0.

  The diamond material used for the diamond tool can be selected from materials conventionally used as materials for cutting tools. In the present invention, the diamond material is preferably a single crystal. The diamond material is processed into a size and shape that can be easily attached to a cutting machine as a cutting tool. For example, it is processed into a shape such as a rectangular parallelepiped.

The diamond cutting tool used in the present invention has a radius of curvature of the blade tip of 50 nm to 5 μm, preferably 100 nm to 2 μm. The radius of curvature of the tip of the diamond bite can be easily measured by observing the edge from the side using a field emission scanning electron microscope (SEM).
The diamond tool has a scooping surface and a flank surface. The flank is the back of the cutting tool blade. The angle (flank angle) at which the back surface (flank face) of the blade is not touched with the work surface is preferably 0.5 to 10 degrees, more preferably 2 to 7 degrees.
The scooping surface is the surface on which the chips slide with the cutting blade. The angle formed between the perpendicular line at the cutting edge point and the scooping surface (the scooping angle or the throat angle) is preferably −10 degrees to 10 degrees, more preferably −5 degrees to 5 degrees.
The angle (cutting edge angle) formed between the scooping surface and the flank surface is preferably 70 to 90 degrees, more preferably 80 to 85 degrees. The angle (bias angle) that the cutting edge line makes with the line perpendicular to the cutting direction on the cutting surface is preferably 0 to 20 degrees, more preferably 0 to 10 degrees.

In the diamond tool, a groove is formed on the flank from the scooping surface of the blade. For example, a groove having the structure shown in FIG. 1 is formed. The dotted line in FIG. 1 (2) indicates the bottom surface of the groove. The pitch of the grooves formed on the flank is preferably 100 nm to 20 μm, more preferably 200 nm to 10 μm. The width of the groove is preferably 50 nm to 10 μm, more preferably 100 nm to 5 μm. The ratio of groove width / groove pitch is preferably 0.3 to 0.7.
It is preferable that the depth of the groove formed on the flank gradually decreases from the scooping surface toward the flank side. The depth of the deepest part is preferably 20 nm to 10 μm, more preferably 50 nm to 5 μm. In addition, it is preferable to leave a gap so that the bottom surface of the groove does not touch the work surface, just like making a space so that the flank does not touch the work surface.
The ratio of the depth of the deepest part of the groove / the width of the groove is preferably 0.1 to 5.0, more preferably 0.4 to 3.0, and particularly preferably 0.7 to 2.0. The groove is preferably formed so as to be parallel to the cutting direction.

  The cross-sectional shape of the groove formed on the flank is not particularly limited, and examples thereof include a rectangle, a triangle, a semicircle, a trapezoid, and a shape obtained by slightly deforming these shapes. Among these, a rectangle is preferable. The grooves are formed on the flank face of the diamond tool, preferably over a width of 500 nm to 5 μm, particularly preferably over the entire width. The scooping surface and the flank surface are preferably smooth, and the arithmetic average roughness (Ra) is preferably 10 nm or less, more preferably 3 nm or less.

Examples of a method for forming the groove as described above in the diamond material include a focused ion beam (FIB) processing method and a plasma etching processing method.
In the FIB processing method, an accelerated ion beam of Ga (gallium) is focused by an electrostatic lens system, a sample surface is scanned, and secondary electrons and secondary ions generated are detected and an image (SIM: Scanning Ion). This is a method of accurately processing a cross section of a target place with high positional accuracy while observing as a Microscopic image).

In the present invention, it is preferable to irradiate a focused ion beam from the flank side toward the scooping surface side to form a groove on the flank face of the diamond tool. By irradiating the focused ion beam from the flank side, the sagging of the processing edge due to flare can be reduced, sharp unevenness of the processing edge can be formed, and a highly accurate uneven shape can be formed Can do.
Further, it is preferable that the angle between the incident direction of the focused ion beam and the flank of the diamond tool is 10 degrees or less, preferably 5 degrees or less.

  On the other hand, in the plasma etching processing method, a portion other than the portion where the groove on the diamond tool is to be formed is covered with a mask made of a material resistant to plasma etching such as silicon oxide, and then exposed to plasma of a gas containing oxygen. In this method, grooves are formed on the flank (see Japanese Patent Application Laid-Open No. 2007-67453, etc.).

The diamond tool is usually used by brazing to a shank for easy attachment to a cutting machine. A diamond tool is attached to a precision micro-machining machine (cutting machine), and a plurality of fine grooves are formed on the workpiece using the diamond tool to obtain a die.
Examples of the workpiece include a flat plate and a roll. In the roll-shaped workpiece, the blade of the diamond tool is pressed against the curved surface of the roll-shaped workpiece, the roll-shaped workpiece is rotated, and the roll-shaped workpiece curved surface is cut or ground.

  The precision micromachining machine has an X-axis, Y-axis, and Z-axis movement accuracy of preferably 100 nm or less, more preferably 50 nm or less, and particularly preferably 10 nm or less. The precision micro-machining machine is preferably installed in a room in which the displacement of vibration of 0.5 Hz or more is controlled to 50 μm or less, more preferably in a room in which the displacement of vibration of 0.5 Hz or more is controlled to 10 μm or less. Processing. Further, the cutting or grinding of the flat workpiece or the roll workpiece is preferably performed in a temperature-controlled room whose temperature is controlled within ± 0.5 ° C., more preferably a temperature-controlled room where the temperature is controlled within ± 0.3 ° C.

Metal used in the work, the average value r _av of Lankford is 0.6 or more, preferably a metal of 0.7 to 1.2, or work hardening coefficient is 0.2 to 1.0, preferably 0. 4 to 0.6 metal. Particularly preferred metals for use in workpieces are those that exhibit a numerical value in the above range with a Rankford average or work hardening index.
Examples of the metals whose Rankford average value or work hardening index falls within the above range include pure copper, oxygen-free copper; copper alloys such as brass; nickel alloys such as Inconel, Hastelloy, Monel, Nichrome, Permalloy; chromium steel, It is selected from chromium nickel steel (for example, austenitic stainless steel such as stainless steel SUS304 and SUS316), duplex stainless steel, and the like. Moreover, as a workpiece | work used for cutting, the metal film which formed the said metal on the base material by electrodeposition or electroless plating is mentioned.

A plurality of rows of grooves can be formed directly on the mold by pressing the diamond bit having the above-described shape onto the workpiece made of metal. At that time, since the cutting edge of the diamond tool is rounded, the pressure applied to the work made of a highly ductile material can be increased, and the fine structure formed at the tip of the diamond tool can be faithfully formed on the work. it can.
Also, a diamond bit is pressed on the workpiece to form multiple rows of grooves, a metal plate is produced on the workpiece by electroforming, the metal plate is peeled off from the workpiece, and the metal plate is used as a base. You may produce a metal mold | die by affixing on a material. The mold may be plate-shaped or roll-shaped.

A plurality of rows of grooves can be transferred to the transparent resin molding by the mold obtained by the above method, and the transparent resin molding to which the plurality of rows of grooves are transferred can be used as an optical element.
As the transparent resin molding, a transparent resin film or plate is usually used. The transparent resin preferably has a glass transition temperature of 60 to 200 ° C, more preferably 100 to 180 ° C from the viewpoint of processability. The glass transition temperature can be measured by differential scanning calorimetry (DSC).

  Transparent resins include polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polyvinyl chloride resin, cellulose diacetate, cellulose triacetate, alicyclic ring And olefin polymers.

  The transparent resin used in the present invention contains coloring agents such as pigments and dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents, etc. An agent may be appropriately blended.

  The average thickness of the transparent resin molded body is usually 5 μm to 10 mm, preferably 20 to 500 μm, from the viewpoint of handleability. The transparent resin molding preferably has a visible light transmittance of 80% or more at a wavelength of 400 to 700 nm.

A long one is preferably used as the transparent resin molding. “Long” means a material having a length of at least about 5 times the width, preferably a material having a length of 10 times or more, and specifically wound and stored in a roll shape. Or what has the length of the grade carried.
The width of the long transparent resin molded body is preferably 500 mm or more, more preferably 1000 mm or more. In the course of the manufacturing process, both ends in the width direction may be arbitrarily cut off (trimming). In this case, the width | variety of the said transparent resin molding can be made into the dimension after cutting off both ends.
The transparent resin molding can be obtained by a known molding method. Examples of the molding method include a cast molding method, an extrusion molding method, and an inflation molding method.

The transfer method to the transparent resin molded product is not particularly limited. For example, when a roll-shaped mold (transfer roll) is used, a transparent resin film is sandwiched between the transfer roll and the nip roll, and a plurality of rows of grooves formed on the transfer roll surface are transferred to the resin film surface. The pinching pressure between the transfer roll and the nip roll is preferably several MPa to several tens of MPa. The temperature at the time of transfer is preferably Tg to (Tg + 100 ° C.), where Tg is the glass transition temperature of the transparent resin constituting the resin film. The contact time between the resin film and the transfer roll can be adjusted by the feed speed of the resin film, that is, the roll rotation speed, and is preferably 5 to 600 seconds.
As another transfer method, a photosensitive transparent resin is applied to the surface of the transparent resin molded body, a transfer mold is pressed against the coating film, and the photosensitive transparent resin is cured by exposure in that state, and then the gold The method of peeling a type | mold is mentioned.

By the transfer, an optical element having a plurality of rows of grooves (or ridges) formed on the surface of the resin molded body is obtained.
The optical element is used for a grid polarizing film, a diffraction grating, a light diffusion plate, a light collecting sheet (prism sheet), and the like.

Next, the manufacturing method of the optical element of the present invention will be described by taking a grid polarizing film as an example of the optical element.
The method of manufacturing an optical element having a plurality of rows of grooves according to the present invention includes a step of transferring the shape of the plurality of rows of grooves to a transparent resin molded body using a mold obtained by the mold manufacturing method. Is included.
The grid polarizing film has a lattice shape showing grid polarizing performance. Therefore, the transfer mold needs to have grooves corresponding to the lattice shape. And this metal mold | die adjusts the groove size of a diamond bite so as to correspond to the groove size of a metal mold | die, and it manufactures it according to the manufacturing method of the metal mold | die of the said invention.

  The grid shape showing the grid polarization performance is such that the height of the ridge is preferably in the range of 5 to 3000 nm, preferably in the range of 20 to 300 nm, more preferably in the range of 50 to 200 nm, and the width of the ridge. Is preferably in the range of 30 to 200 nm, more preferably in the range of 60 to 150 nm, and the distance (pitch) between the ridges is preferably in the range of 20 to 600 nm, more preferably in the range of 80 to 400 nm. Is within. Here, the distance between the ridges is the distance between the vertices of the ridges.

  The height, width, and pitch of the ridges are observed with an electron microscope, the dimensions of the observed image are measured, and an average is obtained therefrom. Specifically, 9 points are selected at random from the film surface, the portion is observed, and the height, width, and pitch of the ridges within the range of 10 μm in length of the observed image are measured. Calculated from point measurements.

  The height / width ratio of the ridges is preferably 0.3 to 3.0, more preferably 0.5 to 2.0. The ridges are elongated and linear, and the length is preferably 500 nm or more. The ridges are arranged substantially in parallel. Here, “substantially parallel” means within a range of ± 5 degrees from the parallel direction.

  In order to obtain a grid polarizing film, a metal grid layer is formed on the transparent resin molded body to which the ridges are transferred. The material used for the metal grid layer is preferably a conductive metal, and specific examples include metals such as aluminum, indium, magnesium, rhodium, and tin.

The metal grid layer is preferably formed on the top of the ridge or on the bottom of a groove formed between the ridges. The metal grid layer can be formed by physical vapor deposition (PVD method) of a conductive metal material. The PVD method is a method of forming a film by evaporating and ionizing a vapor deposition material. Specifically, it can be appropriately selected from vacuum deposition, sputtering, ion plating (ion plating), ion beam deposition, and the like. Of these, vacuum deposition is preferred.
The vacuum deposition method is a method of forming a thin film by heating and vaporizing or sublimating a deposition material in a vacuumed container and attaching it to the surface of a substrate placed at a remote position. Depending on the type of vapor deposition material and substrate, heating is performed by a method such as resistance heating, electron beam, high frequency induction, or laser.

In order to finely adjust the width of the metal grid layer formed by the PVD method, wet etching may be performed. Further, masking may be performed on the metal grid layer before wet etching.
An inorganic compound is usually used for masking. For example, a compound such as silicon oxide, silicon nitride, silicon carbide, or silicon nitride oxide can be used. Of these, silicon oxide is particularly preferable. The thickness of the inorganic compound film used for masking is not particularly limited, but is usually 1 to 100 nm, preferably 2 to 50 nm, more preferably 3 to 20 nm.

  Prior to the wet etching, the film can be stretched in a direction perpendicular to the length of the ridges arranged substantially in parallel. Since the distance between the centers of the ridges is increased by this stretching, the distance between the metal grid layers is increased, and as a result, the light transmittance is increased. In addition, the metal grid layer formed on the bottom surface of the groove is separated from the base of the ridges by stretching to form a gap. A wet etching solution described later enters the gap, and both ends of the metal grid layer formed in the groove are preferentially removed, and both ends can be made thinner than the center.

The stretching method is not particularly limited, but the stretching ratio in the direction perpendicular to the ridges is preferably 1.05 to 5 times, more preferably 1.1 to 3 times, and the stretching ratio in the direction parallel to the ridges is preferably 0. .9 to 1.1 times, more preferably 0.95 to 1.05 times.
The width and height of the ridge after stretching are almost the same as the values before stretching. On the other hand, the distance between the centers of the ridges is longer than before stretching, and is preferably 30 to 1000 nm, more preferably 50 to 600 nm. In order to perform such stretching, continuous transverse uniaxial stretching by a tenter stretching machine is suitable.

  Wet etching is performed by bringing the metal grid layer into contact with an etching solution. The etching solution only needs to be a solution that can remove a part of the metal grid layer without corroding the transparent resin molded body, and depends on the material of the masking layer (inorganic compound film), the metal grid layer, and the transparent resin molded body. Are appropriately selected. Examples of wet etching solutions include solutions containing alkali metal compounds such as sodium hydroxide and potassium hydroxide; solutions containing sulfuric acid, phosphoric acid, nitric acid, acetic acid, hydrogen fluoride, hydrochloric acid, etc .; ammonium persulfate, hydrogen peroxide, fluorine A solution made of ammonium fluoride or the like or a mixture thereof may be used. An additive such as a surfactant may be added to the wet etching solution.

  By this wet etching, both sleeve portions of the metal grid layer laminated on the top of the ridge and both ends of the metal grid layer laminated on the bottom surface of the groove are removed. As a result, the metal grid layer having the same width as the width of the ridges remains without being removed at the top of the ridges, and the metal grid layer remains without being removed at the center of the bottom surface of the groove.

The width and length of the metal grid layer substantially follows the width and length of the ridges or the width or length of the grooves formed between the ridges. The thickness of the metal grid layer A formed on the top of the ridge is not particularly limited. Usually, it is 20-500 nm, Preferably it is 30-300 nm, More preferably, it is 40-200 nm. The thickness of the metal grid layer B formed at the bottom of the groove formed between the ridges is not particularly limited. Usually, it is 20-500 nm, Preferably it is 30-300 nm, More preferably, it is 40-200 nm. In the metal grid layer B formed at the bottom of the groove, the ratio of the thickness H ₂ at both ends to the thickness H ₁ at the center is preferably 0.6 or less, more preferably 0.4 or less, particularly preferably. What is 0.2 or less is preferable. That is, the vertical cross-sectional shape of the metal grid layer B formed at the bottom of the groove is preferably a shape (mountain shape) that is high in the center and low on both sides.
The pitch between the metal grid layers is shown as the distance between the metal grid layers A formed on the tops of the ridges and / or the distance between the metal grid layers B formed at the bottom of the groove, both of which are preferably 20 to 600 nm. And more preferably in the range of 80 to 400 nm.

You may laminate | stack a protective layer directly or through another layer on the surface in the side in which the metal grid layer of the obtained grid polarizing film was formed.
The protective layer is not particularly limited by its material, but is preferably made of a transparent material. Examples of the transparent material include glass, inorganic oxide, inorganic nitride, porous material, and transparent resin. Of these, those made of transparent resin are particularly preferred. The transparent resin can be appropriately selected from those shown as constituting the above-mentioned transparent resin molding.
The average thickness of the protective layer is usually 5 μm to 1 mm, preferably 20 to 200 μm, from the viewpoint of handleability. The protective layer preferably has a light transmittance in the visible region of 400 to 700 nm of 80% or more.

  The protective layer has a retardation Re measured at a wavelength of 550 nm of preferably 50 nm or less, and more preferably 20 nm or less. Moreover, the difference (retardation unevenness) of the retardation Re at any two points in the plane is preferably 10 nm or less, and more preferably 5 nm or less. When the retardation Re is large and the retardation unevenness is large, the brightness of the display surface tends to vary when used in a liquid crystal display device.

  An adhesive (including an adhesive) can be used for laminating the protective layer. The average thickness of the layer (adhesive layer) made of an adhesive interposed between the metal grid layer on the top of the ridge and the protective layer is usually 0.01 μm to 30 μm, preferably 0.1 μm to 15 μm. When attaching the protective layer with an adhesive, it is necessary to prevent the adhesive from entering the grooves formed between the ridges and to leave the air in the space between the metal grid layers. Is preferable.

  Next, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to this Example.

Example 1
Focused ion beam machining from the flank face side of a single crystal diamond bite made of a flank face (B) with a flank angle of 5 °, 0.2 mm × 1 mm, and a rake face angle of 90 °, 1 mm × 1 mm (A) Using an apparatus SMI3050 (manufactured by Seiko Instruments Inc.), an argon ion beam was irradiated at an angle of 93 degrees with respect to the scooping surface, and a 5 μm long groove (G ) On the flank face over the entire width (1 mm). The shape of the groove forming portion on the side of the ugly surface was a rectangular shape having a pitch of 200 nm, a width of 100 nm, and a depth of 70 nm. The obtained diamond cutting tool was brazed to an 8 mm × 60 mm surface of an 8 mm × 8 mm × 60 mm SUS shank.

  The entire surface of the curved surface of a stainless steel SUS430 cylinder having a diameter of 200 mm and a length of 150 mm was subjected to nickel-phosphorus electroless plating having a thickness of 100 μm. Next, using a precision cylindrical grinding machine S30-1 (manufactured by Studer), the cutting edge of the cutting tool is rounded by pressing the diamond tool prepared earlier against the nickel-phosphorous electroless plating surface while rotating the cylinder. A cutting tool was obtained. The radius of curvature of the cutting edge (T) of the cutting tool was 55 nm as measured with a field emission scanning electron microscope S-4700 (manufactured by Hitachi, Ltd.). FIG. 1 shows a rear view (1), a side view (2), and a front view (3) for showing an outline of the diamond tool.

  Copper plating having a thickness of 100 μm was applied to the entire curved surface of a stainless steel SUS430 cylinder having a diameter of 200 mm and a length of 500 mm. Note that the copper used for plating has a Rankford average value of 0.9 and a work hardening index of 0.44. Next, using a precision cylindrical grinding machine S30-1 (manufactured by Studer), press the cutting tool bit against the copper-plated surface while rotating the cylinder to form a concavo-convex line that goes around the curved surface with a width of 1 mm. did. The cutting tool was moved in parallel by 1 mm in the length direction of the cylinder, and in the same manner as described above, an uneven strip having a width of 1 mm that goes around the curved surface was formed. This cutting operation was repeated to form a concavo-convex strip having a width of 450 mm on the copper plated surface of the SUS cylindrical curved surface layer to obtain a transfer roll.

  In addition, the production of the cutting tool by focused ion beam machining and the machining of the nickel-phosphorus electroless plating surface and the copper plating surface are performed with a vibration control system (manufactured by Showa Science Co., Ltd.) with a vibration displacement of 0.5 Hz or more and 10 μm or less. The temperature was controlled in a constant temperature and low vibration chamber at a temperature of 20.0 ± 0.2 ° C.

A 100 μm cycloolefin polymer film (ZF-14, manufactured by Optes) between a rubber nip roll having a diameter of 70 mm (surface temperature of 100 ° C.) and the transfer roll (surface temperature of 160 ° C.) is 0.1 kgf / mm ^{2 in} conveying tension. The nip pressure was 0.5 kgf / mm, and the shape of the transfer roll surface was transferred to the film surface. The film with the transferred shape was wound into a roll. A transmission electron microscope H-7500 (Hitachi) shows that a plurality of convex strips having a width of 100 nm and a height of 70 nm are arranged on the surface of the obtained transfer film in parallel with the longitudinal direction of the film at a pitch of 200 nm. This was confirmed by observation of a manufacturing company. The sample for observation was prepared with a microsampling device of a focused ion beam processing observation device FB-2100 (manufactured by Hitachi, Ltd.)

On the concavo-convex surface side of the transfer film, SiO ₂ is sputtered at an output of 400 W from a direction inclined by 70 degrees from the normal direction of the film in the presence of argon gas and perpendicular to the film longitudinal direction (longitudinal direction of the ridges). The oblique film was formed. Next, oblique film formation was performed by sputtering SiO ₂ at a power of 400 W from a direction inclined 70 degrees to the opposite side of the direction and perpendicular to the longitudinal direction of the ridges. Finally, aluminum was vacuum deposited from the normal direction of the film to form a film.

Next, the aluminum vapor-deposited film was composed of 5.2% by weight of nitric acid, 73.0% by weight of phosphoric acid, 3.4% by weight of acetic acid, and the balance consisting of water (acid component equivalent concentration: 83.6% by weight). And immersed in an etching solution at a temperature of 33 ° C. for 30 seconds. It was rinsed with water and dried at 120 ° C. for 5 minutes to produce a long polarizing element.
This polarizing element was observed with a transmission electron microscope H-7500 (manufactured by Hitachi, Ltd.). The sample for cross-sectional observation by the transmission electron microscope was prepared using a microsampling apparatus of a focused ion beam processing observation apparatus FB-2100 (manufactured by Hitachi, Ltd.).
In this polarizing element, an aluminum layer having a width of 99 nm and a thickness of 75 nm is laminated on the top of the ridge where the ridge having a rectangular cross section is formed, and the top aluminum layer forms a grid lattice structure with a pitch of 200 nm. It was. In addition, an aluminum layer having a width of 61 nm and a thickness of 52 nm was laminated on the bottom of the groove between the ridges, and the bottom aluminum layer formed a grid lattice structure with a pitch of 200 nm. The aluminum layer formed on the bottom had a shape in which the film thickness at both ends was thinner than the film thickness at the center.

  Subsequently, a protective film made of triacetyl cellulose was bonded to the aluminum layer forming surface side of the polarizing element via a urethane adhesive to obtain a polarizing element with a protective layer. The polarization transmission axis of the polarizing element with a protective layer was substantially parallel to the width direction of the film.

A reflective sheet was affixed to the bottom of a milky white plastic case having an inner dimension of 300 mm in length, 240 mm in width, and 18 mm in depth. Eight cold-cathode tubes having a diameter of 4 mm and a length of 360 mm were arranged at a distance of 25 mm between the centers of the cold-cathode tubes at a distance of 4 mm from the reflecting sheet surface. The vicinity of the electrode part of the cold cathode tube was fixed with a silicone sealant, and an inverter was attached to obtain a backlight.
A stack of two light diffusion sheets is placed 14 mm away from the cold cathode tube, and the polarizing element is placed on the light diffusion sheet so that the polarization transmission axis is perpendicular to the longitudinal direction of the cold cathode tube. It was.
A cold cathode tube is turned on by applying a tube current of 6 mA and a tube voltage of 330 Vrms, and the luminance of the emitted light is measured in the length direction of the backlight using a luminance meter (BM-7, manufactured by Topcon) to obtain the luminance distribution. It was. The difference (brightness unevenness) between the maximum value and the minimum value was obtained from this brightness distribution. The luminance unevenness was 4 cd / m ² . Moreover, coloring was not seen by visual observation in the emitted light, and it turned out that it is a favorable polarized light source device.

Example 2
Focused ion beam machining device SMI3050 (Seiko Instruments Inc.) Irradiate an argon ion beam at an angle of 105 degrees with respect to the scooping surface using a stencil, and a sine wave groove with a length of 15 μm extending from the scooping surface of the diamond tool blade to the flank side has a full width on the flank surface. A plurality of (1 mm) was formed. The shape on the scooping surface side of the groove formation portion was a sine wave shape with a pitch of 5 μm and a depth of 1 μm. The obtained diamond tool was brazed to a SUS shank.

  The entire surface of the curved surface of a stainless steel SUS430 cylinder having a diameter of 200 mm and a length of 150 mm was subjected to nickel-phosphorus electroless plating having a thickness of 100 μm. Next, using a precision cylindrical grinding machine S30-1 (manufactured by Studer), the cutting edge of the cutting tool is rounded by pressing the diamond tool prepared earlier against the nickel-phosphorous electroless plating surface while rotating the cylinder. A cutting tool was obtained. The radius of curvature of the cutting edge of the cutting tool was 370 nm as measured with a field emission scanning electron microscope S-4700 (manufactured by Hitachi, Ltd.).

  Next, using a precision cylindrical grinding machine S30-1 (manufactured by Studer), the cutting tool tool was pressed against the stainless steel surface while rotating a stainless steel SUS430 cylinder having a diameter of 200 mm and a length of 500 mm. Concave and convex streak that goes around the curved surface was formed. The cutting tool was moved in parallel by 1 mm in the length direction of the cylinder, and in the same manner as described above, an uneven strip having a width of 1 mm that goes around the curved surface was formed. This cutting operation was repeated to form an uneven strip having a width of 450 mm on a cylindrical curved surface made of SUS to obtain a transfer roll. Stainless steel SUS430 has a Rankford average value of 1.2 and a work hardening index of 0.20.

  In addition, the production of a cutting tool by focused ion beam machining and the machining of nickel-phosphorus electroless plated surfaces and stainless steel surfaces are performed with a vibration control system (manufactured by Showa Science Co., Ltd.) with a vibration displacement of 0.5 Hz or more and 10 μm or less. The temperature was controlled in a constant temperature and low vibration chamber at a temperature of 20.0 ± 0.2 ° C.

A 100 μm cycloolefin polymer film (ZF-14, manufactured by Optes) between a rubber nip roll having a diameter of 70 mm (surface temperature of 100 ° C.) and the transfer roll (surface temperature of 160 ° C.) is 0.1 kgf / mm ^{2 in} conveying tension. The nip pressure was 0.5 kgf / mm, and the shape of the transfer roll surface was transferred to the film surface. The film with the transferred shape was wound into a roll. A transmission electron microscope H-7500 (Hitachi) is formed on the surface of the obtained transfer film, in which a plurality of concave and convex strips having a pitch of 5 μm and a depth of 1 μm having a sinusoidal cross-section are formed in parallel to the film longitudinal direction. This was confirmed by observation of a manufacturing company. The sample for observation was prepared with a microsampling device of a focused ion beam processing observation device FB-2100 (manufactured by Hitachi, Ltd.)

A reflective sheet was affixed to the bottom of a milky white plastic case having an inner dimension of 300 mm in length, 240 mm in width, and 18 mm in depth. Eight cold-cathode tubes having a diameter of 4 mm and a length of 360 mm were arranged at a distance of 25 mm between the centers of the cold-cathode tubes at a distance of 4 mm from the reflecting sheet surface. The vicinity of the electrode part of the cold cathode tube was fixed with a silicone sealant, and an inverter was attached to obtain a backlight.
The transfer film was placed 14 mm away from the cold cathode tube so that the direction in which light was diffracted was the longitudinal direction of the cold cathode tube, and a laminate of two light diffusion sheets was placed thereon.
A cold cathode tube was turned on by applying a tube current of 6 mA and a tube voltage of 330 Vrms, and the luminance distribution was obtained by measuring the luminance of the emitted light in the width direction of the backlight using a luminance meter (BM-7, manufactured by Topcon). . The difference (brightness unevenness) between the maximum value and the minimum value was obtained from this brightness distribution. The luminance unevenness was 5 cd / m ² . It was found to be a good polarized light source device.

Comparative Example 1
A polarizing element was obtained and evaluated in the same manner as in Example 1 except that the radius of curvature of the cutting edge of the cutting tool was changed to 10 nm. The luminance unevenness was a very large value of 125 cd / m ² . In addition, the emitted light transmitted through the part of the polarizing element corresponding to the part that was cut at the initial stage of the transfer roll was colored by visual observation.

Comparative Example 2
A transfer film was obtained in the same manner as in Example 2 except that the curvature radius of the cutting edge of the cutting tool was changed to 15 nm, and the same evaluation was performed. The luminance unevenness was a large value of 25 cd / m ² .

It is the rear view (1), side view (2), and front view (3) which show the outline | summary of the shape of the diamond cutting tool obtained by the manufacturing method of this invention.

Explanation of symbols

A: scooping surface B: flank G: groove T: cutting edge

Claims (6)

Using a diamond tool having a plurality of grooves formed on the flank face from the scooping face of the blade on the flank face and having a radius of curvature of the blade tip of 50 nm to 5 μm,
Cutting a workpiece made of a metal having a Rankford average value r _av of 0.6 or more represented by formula (1) or a metal having a work hardening index of 0.2 to 1.0,
A method for manufacturing a mold in which a plurality of rows of grooves are formed.
r _av = (r ₀ + 2 × r ₄₅ + r ₉₀ ) / 4 Formula (1)
(Where r ₀ is the Rankford value in the 0 degree direction with respect to the rolling direction, r ₄₅ is the Rankford value in the 45 degree direction with respect to the rolling direction, and r ₉₀ is the Rankford value in the 90 degree direction with respect to the rolling direction. Value.)   The manufacturing method of the metal mold | die of Claim 1 whose pitch of the groove | channel formed in the flank of the said diamond cutting tool is 100 nm-20 micrometers.   The mold manufacturing method according to claim 1 or 2, wherein a cutting edge angle of the diamond tool is 70 degrees to 90 degrees.   The groove formed on the flank of the diamond tool is formed by irradiating a focused ion beam from the flank to the scooping surface. Mold manufacturing method.   The manufacturing method of the metal mold | die of Claim 4 whose angle made by the incident direction of the said focused ion beam and the said flank is 10 degrees or less. Using a diamond tool having a plurality of grooves formed on the flank face from the scooping face of the blade on the flank face and having a radius of curvature of the blade tip of 50 nm to 5 μm,
By a method including cutting a workpiece made of a metal having a Rankford average value r _av of 0.6 or more represented by formula (1) or a metal having a work hardening index of 0.2 to 1.0, a plurality of rows are formed. Get a mold with grooves,
A method of manufacturing an optical element in which a plurality of rows of grooves are formed, the method including the step of transferring the shape of the plurality of rows of grooves to a transparent resin molding using the mold.
r _av = (r ₀ + 2 × r ₄₅ + r ₉₀ ) / 4 Formula (1)
(Where r ₀ is the Rankford value in the 0 degree direction with respect to the rolling direction, r ₄₅ is the Rankford value in the 45 degree direction with respect to the rolling direction, and r ₉₀ is the Rankford value in the 90 degree direction with respect to the rolling direction. Value.)

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