JPS5868038A - Manufacture of molded product and exposure mask used in its manufacture - Google Patents

Abstract

PURPOSE:To faithfully reproduce an image with a harmless material easy to work by selectively swelling the unexposed part of a water-soluble resin contg. a diazonium salt or an azido compound as a photosensitive material and by transferring the resulting uneven surface onto a pattern material for molding. CONSTITUTION:An aqueous soln. of PVA contg. a diazonium salt or an azido compound is applied to a substrate 1 and dried to form a photosensitive PVA layer 2. An exposure mask 3 is set on the surface of the layer 2, irradiated with light 4, and immersed in a developer. The unexposed part 2a is swollen, the exposed part 2c is not swollen, and the partially exposed part 2b is slightly swollen. Molten wax is poured onto the resulting uneven surface and solidified by cooling to form a pattern material 6 for molding, and the layer 2 is stripped by a known method. The pattern material 6 is worked to a desired plane shape and uniformly coated with a shell 7 by dipping in a frefractory soln. The wax 6 is then melted by heating and removed to manufacture a mold 7 having a space 8. Molten metal is poured into the molding space 8 and solidified by cooling, and by destructing and removing the mold 7, a casting 9 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing molded articles, such as relief images, and to an exposure mask used in carrying out the method.

When molding or casting a relief image such as a portrait or painting with metal, the image drawn thereon is optically transferred onto a photosensitive resin layer using a negative or positive as an exposure mask. Taking advantage of the fact that the exposed area retains water absorption, only the non-exposed area is selectively swollen with water, and a molding pattern material such as low-melting wax is applied to the resulting uneven surface. Furthermore, the conventional investment method using this pattern material is notable in that it skillfully utilizes the difference in the degree of swelling of the photosensitive resin layer and can faithfully transfer the image. After further investigation by the inventor, it has been discovered that there are several problems that should be improved.

That is, in the above casting method, gelatin is used as a photosensitive resin, a dichromate such as ammonium dichromate is used as a photocrosslinking agent in this gelatin, and the gelatin in the exposed area is coated with the dichromate. However, such 1' (chromate) is harmful to the human body and produces ROM ions, so it is unsuitable in terms of 1' and d boundary destruction and pollution. It is difficult to uniformly coat gelatin on a substrate such as metal to form a uniform photosensitive layer, and it is also not easy to purify gelatin itself. Since the exposure mask simply consists of a combination of an inhospitable bright part and a clear part, the expansion 11 occurs near the boundary between them.
After circumferential (development) processing, the unevenness of the gelatin layer becomes steeper.

For this reason, even if the image to be transferred is intended to have a surface shape with a certain bulge, such as a human face or arm, the inner part of the transferred contour line will be almost entirely flat. Therefore, in the created relief, the inner portions (namely, the face and arm portions) have a square shape, which lacks a sense of realism and is therefore unsatisfactory.

In view of the above-mentioned circumstances, the present invention aims to faithfully reproduce an image using a photosensitive material that is harmless and easy to work with, and to give the obtained relief a sense of reality.

In order to achieve this object, according to the method of the present invention, a water-soluble synthetic resin containing a diazonium salt and/or an azide is used as a photosensitive material, and the non-exposed portions of this water-soluble synthetic resin layer are selectively exposed to light. The material is allowed to swell and the resulting uneven surface is transferred to the pattern material for molding. Therefore, most of the photocrosslinking agents used in photosensitive materials are harmless to the human body.
Water-soluble synthetic resins are also easily synthesized and uniformly coated in a solution state. In addition, the exposure mask used in the method of the present invention has a half-mask part that transmits a certain amount of light in a contour line adjacent to the mask part, so that the area adjacent to the mask part also has a certain amount of uniformity. By exposing to light, it is possible to make the level difference transferred between the masked portion and the non-masked portion gentle or gentle.

All photocrosslinking agents that can be used in the method of the present invention must be water-soluble and have little toxicity, such as aromatic diazonium salts represented by the following general formula.

Y◇N"=NX- (However, X represents a halogen such as a chlorine atom, a negative element or group such as H2O2, and Y represents a hydrogen atom, halogen, alkoxy group, other aromatic group, alkyl group, alkenyl group, etc. ) For example, benzenediazonium salts, p-methoxybenzenediazonium salts, and p-diazodiphenylamine can be used. Also, among these diazonium salts, those containing two or more diazo groups in one molecule. For example, bisphenyltetradiazonium salt (this condensate is excellent in sensitivity and thermal stability).Also, an aromatic azide compound can be used in place of the above diazonium salt or in combination with the diazonium salt. This includes bisazide compounds such as 4,4'-diazidiphenyl, 4,4'-
Diazidiphenylamine, 4,4'-diazidophenylmethane, 4.4'-diazidostilhene, 4.4'-
Examples thereof include diazidodiphenylketone, sodium 4,4'-diazidostilpuff-2,2'-disulfonate, and the like.

These diazonium salts or azide compounds are decomposed by irradiation with light, and the generated active intermediates (free radicals) react with the water-soluble synthetic resin to crosslink and insolubilize it. Moreover, since it is water-soluble, it is easy to prepare a photosensitive material coating by mixing it with a water-soluble resin, and it has excellent uniform coating properties on a substrate.

As the water-soluble synthetic resin, polyvinyl type, water-soluble nylon, and water 1M (meth)acrylic resin can be used. For polyvinyl, the processing agent used in the development process after selectively exposing the water-soluble synthetic resin layer containing a predetermined amount of the photocrosslinking agent has the effect of selectively swelling the non-exposed areas without dissolving them. For this purpose, various combinations are possible.
For example, an aqueous solution of borax (containing glycerin) is good for polyvinyl alcohol, and a saturated aqueous solution of boric acid is good for nylon.

After exposing and developing this water-soluble resin layer, the pattern material for molding onto which the resulting uneven surface is to be transferred may be made of low-melting wax, room-temperature-setting silicone or epoxy resin, plaster, or the like. For example, if a low melting point wax is injected into the uneven surface of a water-soluble resin layer in a molten state and peeled off after assimilation, a reverse pattern will be transferred to the wax layer. Next, this wax is dipped into a refractory material that is a known molding material, and the wax surface is coated with the refractory material. Furthermore, the internal wax is removed by heating, and a refractory shell mold is created by firing. If a desired molding material, for example metal, is poured into the molding space formed in the mold 11111 and solidified, and then the shell mold is removed, an image that accurately corresponds to the original positive or negative is transferred. A metal molded product is obtained. Although this casting process itself is known as investment casting, the present invention is of course applicable to side casting processes as well.

Next, the method according to the present invention will be explained in more detail with reference to the drawings.

As shown in FIG.
, 2'-sodium disulfonate) is uniformly applied onto a substrate 1 made of aluminum or the like, and dried to a thickness of 0.1 to 15 strands (0.1 to 15 mm for V/ll process).
7m) of photosensitive polyvinyl alcohol layer 2 is obtained. This coating operation is easy and uniform coating is possible.

Next, as shown in FIG. 1B, an exposure mask 3 is set on the surface, and exposure light 4 is irradiated. Except for this, mask 3
For example, if the pattern is drawn in a ring shape as shown in Figure 2, a circular obscured part (mask part)
Half mask portions 5b are formed adjacent to both sides of 5a.

The half-mask part 5b is a transparent light-transmitting part (non-mask part)
The mask portion 5c has a smaller amount of transmitted light, and is provided as a gray pattern, for example, so as to transmit a certain amount of light compared to the black mask portion 5a. This half-mask pattern is
As shown in the figure, it is important that K is provided in a contour line shape with a uniform width, and plays an important role especially in forming a relief with a rounded surface shape at the inner position of the mask portion 5a. . As a result of using such a unique mask 3, the photosensitive resin layer 2 has a half-mask portion 5b around the non-exposed portion 2a below the mask portion 5a, as shown schematically.
A partially exposed portion 2b corresponding to the above is formed, and a fully exposed portion 2c is formed continuously to this partially exposed portion. Although various light sources can be used for this exposure process, a halogen lamp is preferable in terms of exposure intensity.

After a predetermined image is transferred to the resin layer 2 to form a latent image, if it is immersed in a 70 C developer for a predetermined period of time, as shown in Fig. 1C, the resin layer retains its water solubility. The non-exposed portion 2a absorbs water and swells, while the exposed portion 2c cured by exposure treatment substantially does not swell. Moreover, since the low exposure area 2b swells to some extent, the surface shape after the development process becomes an uneven shape in which the part of the surface from the swollen area 2a to the non-swelled area 2c changes gently or curved due to the swollen area 2b. A developer suitable for obtaining such a surface shape is, for example, borax.
207 An aqueous solution of borax (containing glycerin) consisting of 300 cc of water and 100 cc of glycerin is exemplified. This aqueous solution is effective in appropriately swelling polyvinyl alcohol.

Next, as shown in FIG. 1D, melted low melting point wax is injected onto the uneven surface and solidified by cooling to form a molding pattern material 6. The depth of this pattern material should match the thickness of the intended product.

Next, as shown in FIG. 1E, the wax pattern material 6 is first peeled off according to a known investment fabrication method (for example, the lost wax method).

This pattern material has the above-mentioned uneven surface of the resin layer 2 accurately transferred thereto, and has a curved inclined portion 6b extending from the ring-shaped four portions 6a to the substantially flat surface 6c.

Next, after processing this pattern material 6 into a desired planar shape, it is immersed in a known refractory material solution as shown in FIG. 1F, so that a shelf of refractory material is uniformly applied to the entire surface.

Next, the wax 6 inside the shelf is melted and removed by heating, and then fired to form a flat surface 7c from the ring-shaped recess 7a in accordance with the shape of the pattern material 6, as shown in FIG. 1G.
A mold material 7 having a curved inclined portion 7b and having a molding space 8 for casting inside is created.

Next, a bath-melted metal (molten metal) is injected into the molding space 8 by a known method, and after cooling and solidifying, the mold material 7 is destroyed and removed. As a result, as shown in FIG. 1H, the mold material 7 (i.e., the first
A casting 9 having a shape that exactly corresponds to the mask pattern shown in Figure B is obtained. This product has a concavo-convex surface corresponding to the mask pattern transferred thereto, and in particular has a curved smooth sloped portion 9b extending from the ring-shaped concave portion 9a to the inner circular protrusion 9c. Therefore, the protrusion 9c has a smooth three-dimensional shape with a raised spherical shape.

As explained above, according to the method of the present leprosy example, polyvinyl alcohol containing a harmless photo-crosslinking agent such as a diazonium salt or an azide compound is used as the photosensitive resin, which causes environmental damage and pollution problems. Work can be carried out safely without causing any problems. Moreover, since the photosensitive resin used is easy to apply, it is easy to form a uniform photosensitive layer, and its synthesis is also easy.

In addition, the positive (or negative) pattern as an exposure mask is uniquely formed at 414 as shown in Figures 1B and 2, and the half-mask area is provided in contour lines adjacent to the opaque area that becomes the outline. In addition, the water absorption of the photosensitive layer changes depending on the amount of light corresponding to the half-mask portion, and the resin surface after development can be finished in a smooth uneven shape (see FIG. 1C). As a result, the final product has a smooth uneven surface due to the transfer of the resin surface. For example, in the case of a relief such as a human face or arm, this uneven surface forms a rounded three-dimensional image, effectively giving a sense of reality. Such a three-dimensional image cannot be obtained by using a single opaque pattern exposure mask as described above. The inventor of the present invention has succeeded in realizing the above-described three-dimensional image for the first time by fundamentally changing the way of thinking and uniformly providing a half-mask portion in contact with an opaque pattern. The mask pattern illustrated in FIG. 2 can be modified in various ways. For example, the half-mask portion 5c may be provided only on the inner periphery of the mask portion 5a, or the mask pattern illustrated in FIG.
Alternatively, the half-mask portions 5b may be provided in multiple layers, for example, from the mask portion 5a to the non-mask portion 5c in stages (2
The present invention has been illustrated above, but the above-mentioned embodiments can be further modified based on the technical idea of the present invention. .

[Brief explanation of the drawing]

The drawings illustrate the present invention and include Figures 1A to 1.
Figures H are sectional views sequentially showing the process of casting a relief image, and Figure 2 is a plan view showing the principle of the pattern of the exposure mask used therein. In addition, in the symbols used in the drawings, 1-1--
−−−−−−−−−−−− Board 2−−−−−−−
------ Photosensitive synthetic gutter resin layer 2a --------
----------1 non-exposed part 2b, 2cm----
1 exposure portion 3--11-------Exposure mask 5a-----1~--Mask portion 5b
------------1--Half mask part 5cm~-
−−−−～−−−−−−Non-mask portion 6−−−−−−−
-----------Pattern materials 6a, 7a, 9a--Concave portions 6b, 7b, 9b--11 curved inclined portion 7----
−−−−−−−−−−−−1 mold material 8−−−−−−−−−−
1~----Molding space 9--------1-
---It is a cast product. Agent: Patent Attorney Hiroshi Tsuita (Voluntary) Procedural Amendment November 6, 1980 Commissioner of the Patent Office Mr. Haruki Shimada Self 1 Indication of the case 1981 Patent Application No. 167509 2, Title of invention Method for manufacturing molded articles; and actual control of the method 3, K
Relationship with C1°, a coffin light used in history by ITE Gao 6 parties Patent applicant address: 2-13-22-22, Kamiosaki, Parts Ward, Tokyo 4, Agent 5 Date of amendment order 6, By amendment Increasing number of inventions 7, patent 11 based on the specification to be amended, the scope column and detailed explanation column of the invention, the drawings 1C to 1H (]), and the claims. Please correct it as shown in the attached sheet. (2), "Contiguously in a contour line" on page 5, lines 15-16 of Specification 4'F will be corrected to "contiguously over all sides." (3), "Rounded" on page 10, line 8 is corrected to "with small steps." (4), "curved" in line 6 of page 11 is corrected to "small step". (5), ``Curved surface shape'' on page 12, line 5, line 144, and page 13, line 4 are corrected to ``1 small step shape.'' (6), "spherical shape" in the 5th line of No. 13 Tei is corrected to "ring shape and small step shape". (7), “smooth” on page 14, lines 1 and 4.
is corrected to "step-like with small steps." (8), page 14, lines 6-7, “Rounded eleven--
--------It's going to happen. "It forms a small step-like three-dimensional image with a relatively gentle slope, and therefore can give a certain degree of three-dimensional or real appearance. The mask pattern shown in Figure 2 is a basic one. Therefore, in reality, it is better to make the color of the half-masked portion 5b lighter in color (that is, to increase the amount of light transmitted) toward the non-masked portion 5c in a multi-step or continuous manner.Therefore, in this case This means that it is possible to effectively give the relief image a substantially rounded, realistic feel.'' (9), page 14, line 17, ``for example'' is corrected to [For example, -1 as above. (10, p. 14, lines 19-20, "can also be done." , it is possible to give better roundness (curved surface shape) to the relief.''al) Of the drawings attached to the application, Figures 1C to 1H are corrected as shown in the attached sheet. Claim 1: Forming a water-soluble synthetic resin layer containing at least one of a diazonium salt and an azide compound as a photocrosslinking agent; and forming the water-soluble synthetic resin layer into a predetermined pattern using an exposure mask. a step of exposing the exposed portion to an insoluble material; a step of swelling only the non-exposed portion of the water-soluble synthetic resin layer to create unevenness between it and the exposed portion; and a step of forming the uneven shape into a molding material. A method for manufacturing a molded article, comprising the steps of transferring the pattern onto a pattern material, and using the pattern material to obtain a molded article having a corresponding shape. 2 As water-soluble synthetic resins, water-soluble polyvinyl resins,
The method according to claim 1, characterized by water-soluble nylon and water-soluble acrylic acid resin. 3. As a developer to swell the non-exposed areas of the water-bathable synthetic resin layer, a borax bath solution is used for water-soluble polyvinyl synthetic resin, and a boric acid aqueous solution is used for water-soluble nylon. A method according to claim 2. 4. After a refractory material is applied to the surface of a molding pattern material, the molding pattern material is melted and removed to form a molding space, and a molding material is further injected into this molding space and solidified. The method described in any one of Items 1 to 3 in the range of . 5. In an exposure mask comprising a mask part that does not substantially transmit light and a non-mask part that transmits light, a half-mask part that transmits a certain amount of light, although the amount of light transmitted is slightly smaller than that of the non-mask part. is provided adjacent to the mask portion over all sides thereof. 6. The exposure mask according to claim 5, wherein the amount of light transmitted through the half mask portion increases stepwise or continuously from the mask portion to the non-mask portion. (2)

Claims (1)

[Claims] 1. A step of forming a water-soluble synthetic resin layer containing at least one of a diazonium salt and an azide compound as a photocrosslinking agent, and exposing the water-soluble synthetic resin layer in a predetermined pattern using an exposure mask. a step of processing to change the exposed part into an insoluble substance; a step of swelling only the non-exposed part of the water-soluble synthetic resin layer to create unevenness between it and the exposed part; and molding the uneven shape. A method for producing a molded article, comprising the steps of transferring the pattern onto a pattern material, and using the pattern material to obtain a molded article having a corresponding shape. 2. As water-soluble synthetic resin, water-soluble polyvinyl resin,
The method according to claim 1, characterized by water-soluble nylon and water-soluble acrylic acid resin. 3. A patent that uses an aqueous solution of borax for water-soluble polyvinyl synthetic resin and a boric acid aqueous solution for water-soluble nylon as a developer to swell the non-exposed areas of the water-soluble synthetic resin layer. A method according to claim 2. 4. After applying a refractory material to the surface of the pattern material for molding, the pattern material for molding is melted and removed to form a molding space, and a molding material is further injected into this molding space and solidified. The method described in any one of items 1 to 3 of the range. 5. In an exposure mask comprising a mask portion that does not substantially transmit light and a non-mask portion that transmits light, a half-mask portion that transmits a certain amount of light that is smaller than the non-mask portion; An exposure mask characterized in that the exposure mask is provided in contour lines adjacent to the mask portion. 6. The exposure mask according to claim 5, wherein the amount of light transmitted through the half-mask portion increases stepwise from the mask portion to the non-mask portion.