JP2003039440A - Molding mold for forming uneven pattern and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple molding mold which can form an uneven pattern and can be manufactured easily and a molding mold which can reduce biting. SOLUTION: In the molding mold capable of forming the uneven pattern in a molding, the surface of the molding mold where the uneven pattern is formed is coated with a synthetic resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die used for injection molding or press molding for imparting an uneven pattern to the surface of a plastic molded product, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, when imparting an uneven pattern to the surface of a plastic molded product, a method of imparting an uneven pattern to the surface of the molding die by a blast method or an etching method has been performed. Was there.

Here, the blast method is to inject a sharp-angled abrasive or spherical abrasive on the surface of a molding die at high speed by using compressed air or centrifugal force, and by the impact action thereof. This is a method of carving a fine uneven pattern. It means sand blasting method or shot blasting method, and is a satin finish method by physical treatment. As the blast material, an alumina abrasive, a silicon carbide abrasive, glass beads, etc. are used. The etching method is a method in which an exposed surface and a non-exposed surface are formed on the surface of the molding die and the metal on the exposed surface is melted to give an uneven pattern to the surface of the molding die.

Incidentally, in order to give an uneven pattern to the molding die, not only the above method but also a machining method such as grinding may be adopted.

[0005]

It is time-consuming and costly to provide surface irregularities by a machining method, and when processing a fine portion, a tool suitable for the fine portion is required. There is a problem such as.

According to the blast method, it is necessary to use, as a molding die material, a die material having no material defects such as pinholes, rough scratches, and hardened layers. Also, if the size of the blast particles is non-uniform, the uneven shape of the molding die surface must be non-uniform, so the material and size of the particles to be sprayed must be taken into consideration. If wrong, there is a problem that desired surface irregularities cannot be formed on the surface of the molding die.
In particular, since it is a physical impact treatment, there is also a problem that the satin finish shape and texture are subtly different depending on the hardness and toughness of the mold material.

The etching method has the drawbacks that the carving is shallow and the three-dimensional appearance is poor, but the surface exposed to the processing liquid can be processed at the same time, and a complicated curved surface or a large area can be processed. , Commonly used. In addition, it is necessary to etch many times to give a three-dimensional effect, and it takes time to form a molding die.

The metal is dissolved in the etching process. However, since the dissolution of the metal is a chemical reaction, it is difficult to control the dissolution of the metal, and the surface to be dissolved cannot be uniformly dissolved. Also,
The metal of the die material has unique etching characteristics, and there is a problem that the etching shape, roughness, and gloss appear differently depending on the difference in chemical composition, structure, and grain size. And
There is also a problem that the texture and crystal grains are changed due to local alteration due to heat treatment of the die material and the like, resulting in unevenness of grain. further,
For fine patterns such as matte texture, mold materials with few material defects must be used.
It is necessary to polish up to # 600. On the other hand, there is also a problem that once the metal is dissolved in etching, it cannot be restored and cannot be redone.

Although both the blasting method and the etching method have the above-mentioned problems, they are generally used as a method for shaping a molding die. However, these methods are for physically or chemically treating the surface of the molding die. In the blast method, polishing is required after the blast treatment, and similarly in the etching method, polishing treatment is required. When the polishing treatment is not performed, there is a problem that a so-called "stripping" phenomenon occurs and the molded product cannot be removed from the mold depending on the removal angle.

[0010]

Therefore, the inventor has accomplished the present invention as a result of earnest research to solve these problems. The molding die according to claim 1 of the present invention is a molding die characterized in that a mold shaped in an uneven pattern is covered with a synthetic resin. The molding die according to claim 2 of the present invention is formed by spray coating.
The molding die according to claim 1, which is coated with a synthetic resin. The molding die according to claim 3 of the present invention is a molding die according to claim 1, characterized in that the molding die is coated with a synthetic resin. The molding die according to claim 4 of the present invention is a molding die, and the molding die is a blast-processed mold. It is the molding die described. The molding die according to claim 5 of the present invention is a molding die, and the molding die is an etching-treated mold, wherein the molding die is any one of claims 1 to 3. It is the molding die described. In the molding die according to claim 6 of the present invention, the synthetic resin is an epoxy resin, a phenol resin, a melamine resin, a diallyl phthalate resin, a polyimide resin, a polyamideimide resin,
The molding die according to any one of claims 1 to 5, which is one or more kinds of resins selected from fluorine resin. The molded article according to claim 7 of the present invention is a molded article characterized by being molded with the molding die according to any one of claims 1 to 6. The method for producing a molding die according to claim 8 of the present invention is a method for producing a molding die, characterized in that a synthetic resin is sprayed onto the molding die having an uneven pattern. A molding die according to claim 9 of the present invention is a method for producing a molding die, characterized in that the molding die having an uneven pattern is coated with a synthetic resin.

The objects, features and advantages of the present invention will become more apparent from the detailed description of the embodiments of the invention given below with reference to the drawings.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A molding die according to the present invention is characterized in that a synthetic resin layer is provided on the surface of a molding die shaped in an uneven pattern. Here, being shaped into an uneven pattern means being shaped into an uneven pattern such as leather grain and satin grain. The term "texture" refers to a wrinkle pattern found on the surface of leather, and is applied to interior parts of automobiles such as steering handles, console boxes, meter panels, dashboards, and side moldings. Pear-skin texture refers to the minute irregularities that can be seen on the surface of pears.
It is applied to the exterior of home appliances such as TVs, cooler panel grills, refrigerator panels, and washing machine panels. FIG. 1 shows a conceptual cross-sectional view of a molding die that is an embodiment of the present invention. By the synthetic resin layer 20 formed on the mold 101 having an uneven surface, a surface shape corresponding to the synthetic resin layer 20 is given to the surface of the molded product. The surface of the mold 102 may be covered with resin. Further, the entire molding die may be covered with resin. That is, if the synthetic resin layer is regarded as a convex shape, the molded article is provided with a corresponding concave surface shape. In addition, the surface shape of the unevenness may be applied to the entire surface, or the uneven shape may be applied only to a part of the surface. Depending on the shape of the uneven surface, it is referred to as leather grain or satin grain.

The present invention is made by coating the surface of a molding die, which is formed in an uneven shape, with a synthetic resin. In particular, when shaping is performed by etching, it is necessary to mold-paste and acid-treat a plurality of times, but according to the present invention, similar shaping can be performed even if the number of times of etching is small. Further, since the polishing process is not required, the time required for forming the molding die can be reduced.

Further, the resin is present between the molded product and the molding die, the heat transfer coefficient of the resin is lower than that of the metal, and the molten resin to be molded is a metal directly. Since it does not come in contact with the mold, the temperature drop of the molding resin is gentle, and welds are unlikely to occur.

Since the surface of the molding die is covered with the synthetic resin, the surface of the molding die can be prevented from being oxidized. Even if there are pinholes in the coating resin, since the surface of the molding die is covered with the resin,
Repair with the resin is easy. Moreover, since the resin can be easily removed with a solvent or the like, the molding die can be reused.

On the other hand, even though it is a synthetic resin, it may be affected depending on the operating temperature range. However, even when used near the heat-resistant limit temperature, it does not melt like metal, and the resin becomes flexible and easily deforms, so that galling is unlikely to occur.

The synthetic resin used here is required to have heat resistance, releasability, adhesion to a die material, abrasion resistance and the like. The heat resistance is preferably one that does not melt at least at 150 ° C. As abrasion resistance, resins used in injection molding, such as polypropylene resin and ABS resin (acrylonitrile-butadiene-styrene copolymer)
It is desirable to have sufficient resistance to the flow of melt such as. For example, it is desirable that the molding can withstand 1000 shots or more. This is because in the manufacture of molded products, many molded products are manufactured with the same mold. Synthetic resins suitable for these include epoxy resin, phenol resin, melamine resin, diallyl phthalate resin, polyimide resin, polyamideimide resin, and fluorine resin, and in the present invention, one kind selected from these synthetic resins or A resin obtained by combining these is used. The epoxy resin, the polyimide resin, the polyamide-imide resin, the fluorine resin, or a mixture thereof is preferable. As an epoxy resin, bisphenol A
Type, those using novolac, those using cyclopentadiene and cyclohexene derivatives, and the like. Examples of the polyimide resin include polyamino bismaleimide and bismaleimide-triazine resin. Polyamideimide resins include those synthesized from trimellitic acid and pyromellitic acid. Examples of the fluorine resin include polyfluoroethylene, fluorinated ethylene-propylene copolymer, polytrifluorochloroethylene, and polyvinylidene fluoride.

Various additives may be added to these synthetic resins to increase their properties. For example,
A release agent for improving the releasability and a filler for improving the strength of the synthetic resin layer may be added to the synthetic resin. As the additive, a release agent, a cross-linking agent, an antistatic agent, a curing agent or the like is used. Alumina, silicon carbide whiskers, pigments or the like are used as the filler.

As a method of coating the surface of the mold with a synthetic resin, a method of spraying and coating a synthetic resin, a method of coating, a method of coating with a brush or the like, a method of coating the mold by dipping it in a resin liquid, etc. However, the present invention is not limited to these. From the viewpoint of productivity, the spray coating method and the coating method are preferable. This is because the mold can be easily manufactured. The synthetic resin coating layer formed by spray coating or coating has a thickness of 10 μm to 100 μm, preferably 10 μm to 50 μm. 10μ
If it is m or less, it is difficult to cover the entire surface in the case of covering the entire surface, and if it is 100 μm or more, the uneven shape may change.

Examples of the metal used for the mold include not only steel materials such as pre-hardened steel, hardened steel, precipitation hardening steel and stainless steel but also non-ferrous metals such as zinc alloy, aluminum alloy and beryllium copper alloy. The present invention is not limited to these.

If the mold is blasted or etched, the adhesion of the synthetic resin is improved due to the anchor effect. Further, corona discharge, ultraviolet irradiation, radiation irradiation, or the like may be performed as the surface treatment of the mold. By these treatments, the adhesiveness can be improved.

In the molded product by the molding die according to the present invention, since the surface property of the molded product is similar to that of the coated product, it is not necessary to further coat the molded product. That is, the surface of the molded product directly reflects the surface properties of the resin coating, unlike the reversal of the pseudo pattern itself such as etching. For this reason,
The surface texture not only retains the characteristics of the resin itself, but also retains the feel of the resin when applied. Further, since no painting is required, this molded product does not contain paint components and the like, and can be easily recycled.

In producing such a molding die, a synthetic resin is dissolved in a solvent, mixed with a curing agent, adjusted to have an appropriate viscosity, and then the die is applied by a spray coating method or a coating method. Is coated with a synthetic resin.

In the spray coating method, a mixed solution of synthetic resin and curing agent (viscosity of 10,000 to 100,000) is used.
Centipoise) is sprayed with a spray gun in a spraying pressure range of 1 to 7 kg / cm2 to perform spray coating.

In the coating method, a solution (viscosity of 10,000 to 100,000) in which a synthetic resin and a curing agent are mixed is used.
Centipoise) is coated using a device such as a bar coater.

The molding die surface-coated with the synthetic resin and the curing agent is heat-treated in a heating furnace at 100 to 180 ° C. for 1 to 2 hours in order to surely cure the synthetic resin.

The present invention will be described below with reference to examples.

[0028]

Example 1 100 parts by weight of an epoxy resin and 28 parts by weight of an amine curing agent were kneaded, and air bubbles remaining in the resin were removed by a defoaming treatment to be used as a coating resin.
Next, a coating resin is sprayed with an air gun onto a mold having an uneven pattern formed by etching as shown in FIG. 3, the resin is applied, and the mold surface 52 is formed into an uneven pattern. Coated with the resin. Before coating the resin, the mold was washed with a solvent to remove oil, dust and the like adhering to the mold surface. After that, heat treatment in a heating furnace,
The resin was cured. Then, after the finishing inspection, a molding die was obtained. The average depth of the recesses of the molding die thus obtained was 112.8 μm.

[0029]

COMPARATIVE EXAMPLE 1 As a comparative example, a molding die having the same shape as that shown in FIG. The average depth of the recesses of the molding die thus obtained was 102.0 μm.

A molding die was prepared according to Example 1 and Comparative Example 1 and molded by a conventional method to obtain a molded product having a skin texture. However, in the first embodiment, the draft angle is 3
Even if it was a degree, it could be removed without scoring, but with etching, the scoring was severe, and in some cases the molded product could not be removed. The results are shown in Table 1. In addition, although the time required to manufacture the molding die by the spray coating method was 3 hours, the time required for manufacturing the molding die was 5 hours when the etching treatment was used, and the manufacturing time of the molding die was significantly increased. Could be shortened to

[0031]

[Table 1]

The evaluation of the draft angle test results is described below. "○": No shaving was observed. "△": Shavings were found in some parts, but could be removed. “×”: The sword was so severe that it could not be pulled out.

[0033]

Example 2 A mold prepared by the same steps as in Comparative Example 1 was coated with a coating liquid containing an epoxy resin as a main component and an amine curing agent in a predetermined ratio to obtain a molding mold having a coating layer. It was The surface shapes before and after coating are shown in FIG. As is clear from FIG. 2, the macroscopic shape is the same, but microscopically, some micropores are filled with resin. Therefore, it is considered that there is little galling in the molded product with the main molding die, but no galling was observed in the molded product with the main mold as in Example 1.

[0034]

According to the present invention, it is possible to obtain a molding die capable of forming an uneven pattern on a molded product. Further, it is possible to obtain a molded product having the same surface shape as that of the surface coated with the mold.

[Brief description of drawings]

FIG. 1 is a conceptual cross-sectional view of a molding die that is an embodiment of the present invention.

FIG. 2 is a diagram showing surface shapes of an etching treatment mold and a resin coating mold.

FIG. 3 is a schematic view of a molding die used for measuring a draft angle.

[Explanation of symbols]

10 Mold for molding 101 Fixed mold (Cavity side) 102 Movable mold (core side) 20 resin layer 40 Roughness of mold surface 42 Roughness by etching 44 Roughness due to resin coating 50 Scratch check mold 52 Etching part or resin coating part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masayo Kawazoe             2-10-10 Nishiishikiri-cho, Higashi-Osaka City, Osaka Prefecture             Hanako Tanasawa Co., Ltd. (72) Inventor Hisao Aota             2-10-10 Nishiishikiri-cho, Higashi-Osaka City, Osaka Prefecture             Hanako Tanasawa Co., Ltd. F term (reference) 4D075 AA01 AC22 BB04X BB66X                       CA02 CA07 CA13 CA18 DA07                       DA29 DB01 DC16 EA07 EB16                       EB17 EB18 EB32 EB33 EB34                       EB39 EB45                 4F202 AG05 AJ03 AJ09 CA09 CA11                       CB01 CD22

Claims (9)

[Claims] 1. A molding die, characterized in that the die having an uneven pattern is covered with a synthetic resin. 2. The molding die according to claim 1, wherein the molding die is coated with a synthetic resin by spray coating. 3. The molding die according to claim 1, wherein the molding die is coated with a synthetic resin. 4. The molding die according to claim 1, wherein the molding die is a blasted mold. 5. A molding die, wherein the die is an etching-treated die.
The molding die according to any one of 1 to 3. 6. The synthetic resin is one or more resins selected from epoxy resin, phenol resin, melamine resin, diallyl phthalate resin, polyimide resin, polyamideimide resin, and fluorine resin. The molding die according to claim 1. 7. A molded article, which is molded by the molding die according to claim 1. 8. A method of manufacturing a molding die, which comprises spraying a synthetic resin onto a molding die having an uneven pattern. 9. A method for producing a molding die, which comprises coating a synthetic resin on a die having an uneven pattern.