JP3479185B2 - Grain processing method for molds for forming grain products - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a texturing method for a metal mold for molding a plastic or rubber product having fine irregularities on a product surface, so-called grain shape. 2. Description of the Related Art In recent years, a variety of designs have been demanded for plastic and rubber molded products, and there is a high demand for a matte finish or the like in order to give a subtle and complicated pattern or a calm texture. Has become. A technique that meets these requirements is a technique of performing a process called graining on a die. A mold that has been subjected to such graining is called a grained mold, and a product having a grain shape on a product surface formed by the grained mold is called a grained product. [0003] The graining of a mold is performed by covering the mold surface with a resist film formed by photoengraving technology and then performing etching or further applying a mechanical method such as sandblasting to the molded product in the mold. A high value-added pattern is formed in a portion corresponding to the surface. The pattern formed in this way is called a grain pattern, and etching the pattern to give the grain pattern to the mold is called grain processing. The flow shown in FIG. 3 is a method for embossing a general mold for molding a plastic product. In this method, a resist is applied to the surface of the mold 1. After laminating the film 2 and laminating the grain pattern film 3 thereon (step 1), step 2
In step 3, exposure, development, and printing are performed. Then, in step 3, unnecessary portions of the film are removed and masking is performed. Then, in step 4, etching is performed. This is repeated several times to complete etching (step 5). Step 6
Is performed to finish the graining. [0005] However, with the above etching treatment alone, since the fine unevenness 1a due to corrosion is present on the etched surface of the mold 1, the fine unevenness is also transferred to the surface of the obtained molded product, and this is caused by the contact of a nail or the like. Therefore, there is a problem that the product is easily damaged, that is, the product has poor scratch resistance. As a solution to this problem, a method of crushing the fine irregularities 1a and smoothing the etched surface to some extent by blasting using bead-like glass or the like after completion of the etching (step 6) is generally adopted. (Step 6). [0007] On the other hand, in recent years, due to the variety of designs, a grain pattern having an excellent design that is a combination of a glossy portion and a non-glossy portion different from a homogeneous design, such as a conventional grain pattern, has been devised. . FIG. 4 shows a mold graining step for obtaining such a grained product. In FIG. 4, steps 1 to 4 are performed in the same manner as in the processing example of FIG. 3, and in the final stage, as shown in step 5, the resist film 2
Is removed to complete the graining. By doing so, the portion 2a from which the resist film 2 has been removed becomes smooth, and the grain concave portion on the molded product side corresponding thereto becomes glossy. FIG. 5 shows a mold and a molded product manufactured by using the processing method shown in FIG. 4 above. In this embossed die 4, the mirror surface is protected by a resist film without being etched. The product grain concave portion 7b of the grain product 5 to which the mold grain convex portion 6b holding the pattern is transferred has gloss. On the other hand, the mold grain concave portion 6a formed by etching the surface of the grain mold 4 has fine irregularities 6a 'due to corrosion on the surface,
The surface of the product grain convex portion 7a of the grain product 5 to which this is transferred also has fine irregularities 7a '. The fine irregularities 7a 'diffusely reflect light, and form contrast with the above-mentioned glossy portion as a non-glossy portion, thereby enhancing the design of the product by embossing. However, the fine unevenness 7 of this product grain convex portion 7a
a 'was apt to be damaged by contact with a nail or the like, impairing the appearance of the grain pattern, and lowering the product value. As described above, generally, blasting using bead-like glass or the like is used to improve the scratch resistance. However, in the case of a graining process having a contrast between a glossy portion and a non-glossy portion, the resist film 2 is formed. When blasting using bead-like glass or the like is performed after the peeling, blasting is performed not only on the etched mold grain concave portion 6a but also on the mirror-finished mold grain convex portion 6b protected by the mold resist film 2. There is a drawback that a mark is imprinted and the contrast between the glossy part and the non-glossy part of the product is impaired. Therefore, it is possible to protect the mold grain protrusions 6b with the resist film 2 and to perform blasting. However, the mold grain protrusions 6b are mirror-finished, and the adhesiveness of the resist film 2 is high. Is weak and easily peeled off, and blast marks are marked on the mirror surface of the mold grain convex portion 6b, and the contrast between the glossy portion and the non-glossy portion of the product is also impaired. [0012] Accordingly, an object of the present invention is to provide a product which retains the contrast between a glossy portion and a non-glossy portion in the case of a grain forming process for obtaining a grain product having a contrast between a glossy portion and a non-glossy portion. The purpose is to develop a technology that improves the scratch resistance of the surface. More specifically, in comparison with the conventional graining die , the graining of an injection molding mold capable of molding a grained product excellent in both designability and scratch resistance due to the contrast between a glossy part and a non-glossy part. Is to provide the law. Means for Solving the Problems The present inventors have conducted intensive studies on the surface condition of a mold and a molded product, and as a result, have found that a mold for injection molding of a grain product having a contrast between a glossy portion and a non-glossy portion. Regarding, in advance, the mold surface is subjected to a non-glossy treatment by blast treatment with Alundum, etc., a resist film is formed on the mold by photomechanical technology to cover the mold surface, and then the resist is etched. Blasting beads such as glass without removing the film, crushing fine irregularities by alumina random and etching only in the etched part to make it a smooth glossy part, and also improve the scratch resistance, so that the glossy part and the non-glossy part We have completed a textured die for injection molding that can form textured products that are excellent in both design properties and scratch resistance due to contrast. When this mold is used, since it has a smooth mold grain concave portion formed by glass bead blast and a rough mold grain convex portion formed by alundum, the grain product obtained by the conventional mold is used. The glossy portion and the non-glossy portion are reversed with respect to the glossy portion and the non-glossy portion of the uneven portion, whereby the contrast is increased, and thus a grain product excellent in design and scratch resistance can be formed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for embossing a mold surface according to the present invention and a mold obtained by the machining method will be described with reference to FIGS. 1 and 2. FIG. First, the graining step will be described with reference to FIG. In step 1, before forming a grain pattern for etching on the surface of the mold 1 with a resist film, the entire surface of the mold 1 is blasted with alumina random or the like in advance to form fine irregularities 1 on the surface.
b is formed and coarsened. The fine unevenness 1b formed on the surface of the mold is transferred to the surface of the grain when the grain mold is formed using the mold 1, and irregularly reflects light to form a non-glossy portion. Next, a resist film 2 and a grain pattern film 3 for forming a desired grain pattern are formed on the mold surface by photolithography as in the conventional method (step 2). At this time, in this method, since the mold surface is previously roughened by blasting, the adhesion between the mold surface and the resist film 2 is good, so that there is little resist peeling during etching and only little disturbance of the etching pattern. In addition, even during the blasting process using glass beads in the etching portion described later, the blasting air pressure can be set high because it is difficult to peel off, and a sufficient effect can be obtained in crushing the fine unevenness of the etching portion by the blasting. Next, masking is performed (step 4).
Next, etching is performed (Step 5), and after this etching, the etched portion is blasted with beads such as glass while leaving the resist film 2, leaving fine irregularities caused by corrosion in the etched portion to smooth the surface (Step 5). 6). In this way, the concave portion formed by etching the surface of the mold whose surface is smoothed is transferred to the surface of the product when the grain product is formed using the present mold, and becomes a convex portion having a smooth surface. It reflects light well to form a glossy part.
Furthermore, since the surface of the convex portion of the grain product is smooth, it is hard to be damaged by nails or the like, and is excellent in scratch resistance. Further, according to the present invention, contrary to the conventional method, the convex portion of the grain unevenness of the product is smooth and hard to be damaged, and the concave portion has fine unevenness that is easily scratched, so that the structure is easily protected, so that gloss and non-gloss are obtained. Effectively retains the appearance with excellent design while maintaining gloss contrast. The material of the blasting material may be steel, plastic, crushed walnut, or the like, other than alundum or glass, and is not particularly limited. In addition, a bead-shaped blasting material having a small particle diameter may be used where a blasting material having a random shape is used. The mold material is not particularly limited, and may be an aluminum-based material, a titanium-based material, or the like, in addition to a material generally used for the mold material, such as soft iron and beryllium copper. The resin molded by the injection mold according to the present invention is not limited to general-purpose resins such as polyolefin resin, polystyrene resin and ABS resin, or industrial resins such as polycarbonate resin and polyamide resin, as well as various resins. Or a mixture of a reinforcing agent, and there is no particular limitation. FIG. 2 is a schematic partial sectional view of the surface structure of the grain mold according to the present invention and the grain product obtained. The steel material of the grain mold 4 is S55C, and the surface thereof is a mold grain concave part 8a which has been subjected to an etching treatment and a mold grain convex part 8b which is protected by a resist film and is not etched.
Is composed of many unions. Mold grain convex part 8
b, both the mold embossed concave portions 8a are blasted in advance under the conditions of Alundum # 150 and blast air pressure of 2 kg / cm ² before etching to form fine irregularities on the surface. Since the mold embossed portion 8b is protected by a resist film during etching, the blasted surface state is maintained. The mold grain concave portion 8a is blasted under the conditions of glass beads # 100 and blast air pressure of 2 kg / cm ² after the etching process, and fine irregularities generated by the etching are crushed to have a smooth surface state. The surface roughness is such that the mold grain convex portion 8b has Rz = 0.4.
1 μm, and Rz = 0.34 μm for the embossed concave portion 8a. In addition, the step between the mold grain convex part 8b and the mold grain concave part 8a was 14.84 μm. Injection molding was performed using the above-described grained mold and polystyrene (SEHI119, Idemitsu Petrochemical Co., Ltd.) as a resin material. An excellent grain product was obtained. [Comparative Example 1] The same die steel material as that of the embodiment was subjected to grain processing for forming a combination of a glossy portion and a non-glossy portion by the conventional method shown in FIG. The surface of the grain mold 4 is mirror-finished in advance to form a glossy part in the product, and a grain-patterned resist film is formed thereon by photomechanical technology to cover the mold surface and then etched. An etched portion serving as a concave portion and a non-etched portion serving as a convex portion were formed on the mold surface. The film material, exposure time, development time, baking time and other conditions for forming the resist film, and the conditions for the etching solution and etching time for etching were all the same as in the examples. Injection molding was carried out using the above-mentioned embossed mold and the same resin material polystyrene (SEHI119, Idemitsu Petrochemical Co., Ltd.) as in the example. The obtained grain products are
The scratch resistance was remarkably inferior to the examples. The non-glossy portion was easily scratched with nails, and the scratched portion further lost gloss and became white, or conversely, caused gloss and impaired the appearance of a grain pattern, thereby significantly lowering the product value. Comparative Example 2 The same mold steel, resist film forming conditions, and etching conditions as in the example except that the blast treatment with Alundum # 150 was not performed before forming the resist film on the mold surface. Was subjected to graining. Since the mold surface has not been blasted with alumina random # 150 in advance, the adhesion between the mold surface and the resist film is weak, and the target blast air pressure is 2 kg / cm ² in the blast process with glass beads # 100. 5
At kg / cm ² , peeling of the resist film occurred. Injection molding was carried out using the above-mentioned embossed mold and the same resin material polystyrene (SEHI119, Idemitsu Petrochemical Co., Ltd.) as in the example. The obtained grain products are
In the mold, the glass beads hit the non-glossy part of the mold which should be protected from the glass bead blasting treatment by the resist film, and the gloss was generated and the grain pattern was impaired, so that the product value was significantly reduced. Further, the blast air pressure of the glass beads against the mold etching portion was insufficient, so that the fine irregularities generated by the etching were sufficiently crushed and a smooth surface state could not be obtained. For this reason, the obtained grain product had poor glossiness in the glossy portion, did not provide sufficient contrast between the glossy portion and the non-glossy portion, and had extremely poor scratch resistance of the glossy portion as compared with the examples. . The surface roughness in the case of this comparative example is such that the mold grain convex part 8b has Rz = 0.24 μm and the mold grain concave part 8a has
Was Rz = 0.92 μm. Also, the mold embossed portion 8
b, the step of the mold embossed concave portion 8a was 13.54 μm. As described above, according to the present invention, the surface of the mold is subjected to a non-glossy treatment by blasting in advance, and a pattern resist film is formed on the mold by a photoengraving technique to perform etching. After that, beads such as glass were blasted to smooth and gloss only the etched surface. As a result, the mold can mold a grain product excellent in both design properties and scratch resistance due to the contrast between the glossy part and the non-glossy part. In the graining method according to the present invention, the mold surface is first blasted to form fine irregularities.
The increase in cost is small compared to the conventional graining.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart showing an example of a grain forming step of a mold for obtaining a grain product having a contrast between a glossy part and a non-glossy part according to the embodiment. FIG. 2 is a schematic partial cross-sectional view of a graining die manufactured by the graining step of the embodiment and a grained product molded using the same. FIG. 3 is a flowchart showing an example of a general mold graining step; FIG. 4 is a flow chart showing an example of a mold graining step for obtaining a grained product having a glossy part and a non-glossy part contrast. 5 is a schematic partial cross-sectional view of a graining die manufactured by the graining step of FIG. 4 and a grained product molded using the same; [Description of Signs] 1 mold 2 resist film 3 grain pattern film 4 grain processing mold 5 grain product 6a mold grain concave part 6b mold grain convex part 7a product grain convex part 7b product grain concave part 8a mold grain concave part 8b gold Mold grain convex part 9a Product grain convex part 9b Product grain concave part

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B29C 33/00-33/76 B29C 39/26-39/36 B29C 41/38-41/44 B29C 43 / 36-43/42 B29C 43 / 50,45 / 00-45/84 B29C 49/48-49 / 56,49 / 70 B29C 51/31-51 / 40,51 / 44

Claims (1)

(57) [Claims] [Claim 1] Non-glossy treatment of the mold surface by blast treatment
Then, a resist film layer is formed on the blasted mold by a photoengraving technique to cover the mold surface,
Next, after performing etching, blasting without removing the resist film, crushing fine irregularities traces by alumina random and etching only in the etched portion to form a smooth glossy portion, and then removing the resist film, A mold graining method for forming a glossy portion in a grain concave portion of a product by forming a non-glossy portion in a mold grain convex portion.