JP3137662B2 - Manufacturing method of micro spherical mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mold for forming a surface having a large number of fine hemispherical projections.

A product having such a surface having a large number of fine hemispherical projections is, for example, a decorative film which exhibits a kind of geometric pattern on a myriad of lenses or a pattern of an underlayer having a flowing feeling. It is used as toys, displays, covers, panels, etc.

[0003]

2. Description of the Related Art When manufacturing a mold used for forming a surface having a large number of such fine hemispherical projections, a conventional method generally employed is to machine the mold surface. However, forming a mold surface having minute and numerous depressions at extremely fine intervals is a complicated operation requiring an extremely long time, and is an expensive operation, and it is difficult to obtain a stable product. there were.

[0004]

Therefore, it has recently been considered to combine a photographic technique and an etching technique with a mold having a mold surface composed of a large number of fine hemispherical depressions. It is difficult to completely adjust the depth of the dent by the technique described above, and it is difficult to form a hemispherical dent having a depth that is deepest in the center and gradually becomes shallower toward the periphery. .

[0005] In view of the above, there is a demand for the development of a technique capable of easily and surely manufacturing a mold surface including a large number of minute, high-precision hemispherical depressions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is easy to combine a photographic technique and an etching technique with a mold having a mold surface composed of a large number of minute, high-precision hemispherical depressions. It is an object of the present invention to provide a manufacturing method capable of reliably manufacturing.

[0007]

In order to cope with this object, a method of manufacturing a micro-spherical mold according to the present invention is characterized in that the center of a halftone dot is dark and the circumference is small.
Blur-like halftone dots whose density becomes lighter toward the side
A first baking by contact exposure of the array to the mesh pattern, the transparent off the mesh pattern, after the first baking
A master for etching is prepared by a second baking in which the film and the diffusion sheet are overlapped, and a large number of fine spherical surfaces are formed on the surface of the mold by etching using the master. Features.

[0008]

[Function] A first baking step of baking the mesh pattern film and the original plate in close contact with each other, and then baking a transparent film and a diffusion sheet between the mesh pattern film and the original plate. The second printing step is performed by double exposure. In the first baking step, an exposed portion in which the outline of the mesh is transferred onto the etching master is formed, and in the second baking step, a distribution of the burning depth is given to the exposed portion. The black spots in the portion have the highest density at the center and have low density at the periphery. When the mold is etched using this master, a recess having a hemispherical surface with a large depth at the center and a small depth at the periphery is formed on the mold surface of the mold.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings showing one embodiment. The target mold 1 is shown in FIG. 1 and FIG.

The mold 1 is made of, for example, copper, and has a mold surface 3 having a large number of fine depressions 2 on its surface. The depression 2 has a hemispherical shape in which the depth h ₁ at the center is the largest and the depth h ₂ is gradually reduced toward the periphery.

A manufacturing method for manufacturing such a mold 1 is shown in FIG.
Is shown in

That is, as shown in FIG.
The film 4 is exposed in close contact with the continuous tone film 5. The mesh pattern film 4 used here is a film holding a black and white halftone dot pattern of about 100 lines / inch, and such a mesh pattern film is produced by outputting with a scanner.

As the continuous tone film 5, for example, a gravure film manufactured by Fuji Photo Film Co., Ltd. or a gravure film manufactured by Konica Corporation can be used as a commercially available product (first baking step, FIG. 3A).

In FIG. 3, the mesh of the mesh pattern film 4 is indicated by diagonal lines, but it is actually a blurred halftone dot in which the center is deeper and the density becomes lighter toward the periphery.

Next, after the first baking step is completed, the same mesh pattern film 4 is overlaid and adhered to the continuous tone film 5 with the transparent film 6 and the diffusion sheet 7 interposed therebetween without being developed. I do.

The transparent film 6 used here has a thickness of 0.1 mm.
As a commercially available transparent film having a thickness of 1 mm, Toray Lumilar (trademark) manufactured by Toray Industries, Inc. can be used.

As the diffusion sheet 7, a milky white sheet having a thickness of 0.1 mm is used. A commercially available example of such a diffusion sheet 7 is Lumipar TC-1 manufactured by Toyo Cross Corporation.
10 (second baking step, FIG. 3).
b).

After the completion of the second baking step, the continuous tone film 5 is developed to obtain an original plate 8 for etching (development step, FIG. 3c).

This etching master 8 has a number of fine black spots 11 corresponding to the meshes of the mesh pattern film. The density of the black spots 11 is high at the center and lower at the periphery. . The reason is that in the first baking step, the continuous tone film 5 and the mesh pattern film 4 can be exposed in close contact with each other, so that the density tone of the mesh of the mesh pattern film 4 can be directly applied to the continuous tone film 5. In the second printing step, the transparent film 6 and the diffusion sheet 7 are interposed between the continuous tone film 5 and the mesh pattern film 4, and the light during the exposure is transmitted to the transparent film 6.
And the diffusion or wraparound at the diffusion sheet 7,
The light tends to concentrate toward the center of the black spot 11 of the continuous tone film 5, and as a result, the black spot 11 of the continuous tone film 5 has a high density at the central portion and goes to the peripheral portion and therefore has a low density. You.

Next, the original master 8 for etching produced in the second baking step is subjected to close-contact exposure to the high-contrast continuous tone film 12 (positive return step, FIG. 3D).

Next, the exposed continuous tone film 12 is developed to obtain a positive original plate 13 (positive development step, FIG. 3e). The black spots 14 on the positive master 13 have a higher density at the center and a lower density toward the periphery.

Next, the positive master 13 is placed on the carbonish 15.
Are exposed to light (carbon exposure step, FIG. 3f).

Thus, the exposed carbon tissue 1
5a is obtained (carbon tissue forming step, FIG. 3g).

Next, like making a normal gravure plate,
The exposed carbon tissue 15a is bonded to the mold 16 and etched (etching step, FIG. 3h). As the etching step, for example, the carbon tissue 15a
Is adhered to the mold 16 and sufficiently immersed in hot water (about 40 ° C.), and then the ferric chloride solution is corroded. The erosion time is about 30 minutes, and a mold surface 3 having a depression 2 with a maximum depth of 50 μm can be formed (etching step, FIG. 3h).

As the mold member 16, a copper material is usually used.

Thus, the mold 1 is completed (FIG. 3)
i).

FIG. 4 shows another embodiment of the present invention. In this embodiment, the first baking step and the second baking step in the embodiment shown in FIG. 3 are performed on a carbon tissue, and etching is performed using the carbon tissue.

That is, as shown in FIG.
The film 4 is exposed in close contact with the carbon tissue 15 (first baking step, FIG. 4A).

Next, after the first baking step is completed, the car
The same mesh pattern film 4 is overlaid on and adhered to the bonche 15 with the transparent film 6 and the diffusion sheet 7 interposed therebetween, and exposed (second baking step, FIG. 4B).

Thus, the exposed carbon tissue 1
5a is obtained (carbon tissue forming step, FIG. 4g).

After the second baking step, the exposed carbon tissue 15a is bonded to the mold 16 and etched (etching step, FIG. 4h).

Thus, the mold 1 is completed (FIG. 4)
i).

The mold 1 manufactured in this manner is used, for example, as a mold for injection molding. In the resin molded product injected into the mold surface 3, many small depressions 2 of the mold surface 3 are formed. Correspondingly, numerous fine projections are formed.

[0034]

According to the method for manufacturing a microspherical mold of the present invention, the outline of black spots and the density distribution are given on the original plate 8 for etching by the first and second baking processes. Since the pit having the contour and the depth distribution is given to the mold surface by the etching performed, a mold used for manufacturing a resin molded product having a large number of protrusions having a hemispherical surface can be obtained.

The use of this mold facilitates the production of a fine hemispherical lens sheet, which was conventionally difficult to produce.
Special lens effects can be applied to toys, displays, sheet cover panels, etc.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective explanatory view showing a mold.

FIG. 2 is a cross-sectional enlarged explanatory view of a mold.

FIG. 3 is a block diagram showing a manufacturing process in the present invention.

FIG. 4 is a block diagram showing another manufacturing process according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die 2 Dent 3 Mold surface 4 Mesh pattern film 5 Continuous tone film 6 Transparent film 7 Diffusion sheet 8 Master 11 Black spot 12 Hard tone continuous tone film 13 Positive original 14 Black spot 15 Carbon 15a After exposure -Bonchish 16 type material

────────────────────────────────────────────────── ─── Continuation of the front page (72) Ryoichi Kishi Inventor, Kyodo Printing Co., Ltd., 4-14-12 Koishikawa, Bunkyo-ku, Tokyo (56) Reference JP-A-58-28353 (JP, A) JP-A Sho 55-22758 (JP, A) JP-A-4-52286 (JP, A) JP-B-43-22374 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23F 1/00 -3/06 B29C 33/38 G02B 3/00 G03F 7/26

Claims (3)

(57) [Claims] (1) As the center of a halftone dot goes deeper toward the periphery,
A first baking by close-contact exposure of a mesh pattern in which blurred halftone dots whose density becomes thinner is arranged, and after the first baking, the mesh pattern is formed by using a transparent film and a diffusion sheet.
Producing a master for etching by a second baking of multiple layers through the intermediary process, and then forming a large number of microspheres on the surface of a mold by etching using the master; Law. 2. The etching master is a continuous tone film on which the first printing and the second printing have been performed, and the master is turned back to form a positive master. 2. The method for producing a fine spherical mold according to claim 1, wherein the exposure is carried out in close contact with a carbon tissue, and then the exposed carbon tissue is superimposed on the surface of the mold and etched to form the surface of the mold. . 3. The etching master is a carbon tissue that has been subjected to the first baking and the second baking, and the twice-baked carbon tissue is superposed on a surface of a mold and etched. 2. The method for producing a fine spherical mold according to claim 1, wherein the surface of the mold is formed.