JP2505876B2 - Method for manufacturing resin mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a resin metal having a mold surface made of metal.

[Conventional technology]

A mold is required to obtain a plastic molded product by a molding method such as an injection molding method, a press molding method, or a transfer molding method. Generally, a metal mold is used, but a metal mold is manufactured. Generally, plastic molders do not make their own metal molds because they require skilled techniques and processing equipment, and they are outsourced. However, the metal mold is
Since it takes time and labor to process it, there are many problems in terms of delivery time and cost in making the prototype die of metal.

Therefore, it was considered to manufacture a trial mold by a resin molding method using a master mold. However, the mold surface of the resin mold, which is composed of the resin coating layer, is easily damaged and lacks in durability, which is a problem in practical use. Further, in the molding process, a cooling / heating medium is flown through the mold to cool or heat the resin in the cavity, but since the resin has poor thermal conductivity, the resin mold is There was also a problem with the cold heat conductivity of.

In view of such circumstances, the applicant has developed a resin mold having only the mold surface as the metal spray layer (see Japanese Patent Laid-Open No. 60-121022). Since the mold surface is constantly exposed to cold heat, the metal layer serving as the mold surface needs to have a certain thickness in order to have the strength to withstand the thermal stress at that time. It is conceivable to form this metal layer by a plating method instead of the thermal spraying method, but it takes cost and time to obtain a required thickness by the plating method. Therefore, the applicant, as described above,
The metal layer to be the mold surface was formed by the thermal spraying method.

[Problems to be Solved by the Invention]

This resin mold, which was developed by the applicant, is excellent in terms of delivery time and cost, but it has been found that the resin mold has the following problems in subsequent use. That is,
Since the mold surface is formed by a thermal spraying method, the mold surface lacks in denseness due to the inclusion of bubbles in the metal layer and the generation of crystal grains.
There is a problem that the surface of the obtained plastic molded product is clouded and the surface is not glossy. Therefore, this resin mold cannot be used when there is a high demand for the surface finish of the molded product. Furthermore, because it is difficult to spray hard metal with a high melting point on the master mold,
In order to form the mold surface by the thermal spraying method, there is no choice but to spray a soft metal such as zinc or a zinc alloy, but as a result, the mold surface is easily scratched due to insufficient surface hardness and durability is said to be poor. There was also a problem.

Then, this invention makes it a subject to provide the manufacturing method of the resin-made metal mold | die which was excellent not only in the precision of a mold surface but also in durability.

[Means for solving the problem]

In order to solve the above problems, the present invention is configured as follows. A method of manufacturing a resin mold according to the present invention is such that a mold release treatment is performed on a surface of a master mold to thinly form a first sprayed layer made of zinc and / or a zinc alloy, and copper and / or a copper alloy is formed on the first sprayed layer. After forming the second thermal sprayed layer, a backup layer made of fiber reinforced resin is formed thereon to obtain a mold base material on the master mold, and the mold base material is released from the master mold. Then, the first sprayed layer is removed to expose the second sprayed layer as a base layer of the mold surface, and then a metal plating layer to be a surface layer of the mold surface is formed on the second sprayed layer. To form. Implementation of this method may include the step of embedding a heating / cooling pipe in the backup layer. For embedding this pipe, for example, a first backup layer made of fiber reinforced resin is formed on the second sprayed layer, a pipe is arranged on the second backup layer, the irregularities are corrected with resin concrete, and then the fiber is laid on the first backup layer. This is performed by forming a second backup layer made of a reinforced resin. Further, the method may include a step of forming a resin coating on the first sprayed layer to strengthen the first sprayed layer before forming the second sprayed layer. Further, it may include a step of plating the surface of the second sprayed layer exposed by removing the first sprayed layer with a soft metal to close the cavity of the second sprayed layer.

As the resin constituting the backup layer, a thermosetting resin such as a phenol resin, an epoxy resin, an unsaturated polyester resin, a vinyl ester resin or a urethane resin is preferably used because it has excellent heat resistance and mechanical strength.
The composition of the resin composition forming the backup layer is based on, for example, the well-known FRP molding method. Therefore, a filler, a coloring agent, a curing agent, etc. are appropriately mixed with the resin, and various fiber materials are added for reinforcement. Examples of the fiber material include glass fiber, polyamide fiber, gypsum fiber and the like, and carbon fiber excellent in heat conductivity, corrosion resistance and mechanical strength is preferably used. The reinforcing fiber may be used by being preformed in a mat shape or a cloth shape, or may be used in a roving shape.
The back side of the backup layer may be reinforced with a resin composition containing no reinforcing fiber. The thickness of the backup layer and its reinforcing layer is set appropriately in consideration of the required strength and the like. For example, the thickness of the backup layer is
It is preferably 1.0 to 50 mm. These formation methods are F
The hand lay-up method or spray-up method generally used in the RP molding method may be adopted. At that time, if necessary, a reinforcing material such as a metal plate may be put in the layer.

The thermal spray layer of copper or copper alloy, which is the base layer of the mold surface, is 0.3
It is preferably about 20 mm thick. If it is less than 0.3 mm, the strength against cold heat tends to be insufficient.
It is costly to exceed mm. The thermal spraying is performed by an arc thermal spraying method, a plasma thermal spraying method, a gas thermal spraying method or the like under ordinary conditions to spray a metallic material in a molten or semi-molten state on the surface of the master mold to form a metallic coating.

The metal plating layer serving as the surface layer of the mold surface is formed by a usual plating method using the underlayer as an electrode. The thickness is preferably 5 to 100 μm. If it is less than 5 μm, it is difficult to eliminate the roughness of the metal sprayed layer, and it is costly to form it over 100 μm. The metal used for the plating layer is not limited as long as it is a metal that can be plated, but it is easy to obtain a dense mold surface, excellent in corrosion resistance and wear resistance, and hard and has good durability. Hard metals such as nickel (Ni) and chromium (Cr) are preferred. The plating conditions may be as usual.

The pipe for cold heat transfer embedded in the backup layer is preferably a pipe having good thermal conductivity such as a copper pipe. in this case,
The pipe is preferably arranged as close to the mold surface as possible.

In manufacturing a mold, first, a mold release treatment is performed on the surface of the master mold. Here, the master mold is a mold having an original shape of a molded product to be molded with a mold, wood,
Handmade using plaster, clay, etc. As the release treatment agent, for example, water or an alcohol solution of polyvinyl alcohol or an aqueous solution of polyethyleneimine is used,
This is applied to the surface of the master mold.

Then, the first sprayed layer made of zinc and / or a zinc alloy is thinly formed on the surface of the master mold. The thickness of this layer is preferably 20 to 500 μm, for example. 20
This is because if the thickness is less than μm, the strength is poor and the film is easily broken at the time of release. The reason why the thickness exceeds 500 μm is that this layer will be wasted after all, considering that this layer will be removed later.

A second thermal spray layer made of copper and / or a copper alloy is formed on the first thermal spray layer. In this case, a resin coating is formed on the first thermal spray layer before forming the second thermal spray layer. It is preferable to strengthen the first sprayed layer. As the resin for this purpose, for example, a thermoplastic resin such as polystyrene or polymethylmethacrylate is selected, which is dissolved in a solvent such as ethyl acetate or toluene or methyl isobutyl ketone at a concentration of 5 to 30% by weight, This solution is used by applying it to the surface of the first sprayed layer and drying it.

Next, a backup layer is formed on the metal sprayed layer. When embedding a heating / cooling pipe in this backup layer, first, the first backup layer is formed on the sprayed layer to a thickness of about 1 to 30 mm. If the thickness of this layer is less than 1 mm, it tends to peel off and unevenness of embedded metal fittings such as pipes tends to appear on the surface, and if it exceeds 30 mm, the thermal conductivity deteriorates (heat insulating property). Is caused).

When the first backup layer is formed in this way,
Next, the pipes are placed on it, the recesses between the pipes are filled with resin concrete, and the irregularities are corrected. As the resin concrete, for example, a thermosetting liquid resin such as an epoxy resin or an unsaturated polyester resin mixed with metal powder or metal particles of aluminum, iron, copper or the like,
It is common. In this way, when the granular material or powder made of metal such as aluminum or iron is dispersed in the resin concrete, the thermal conductivity of the entire mold is improved. The average particle size of these metal substances is preferably 0.1 to 3.0 mm. The mixing ratio is preferably 50 to 1200 parts by weight with respect to 100 parts by weight of the resin. Such a metal substance may be dispersed on the mold surface side or the whole of the backup layer.
Then, a second backup layer is formed thereon so as to obtain a desired strength. Then, if necessary, a reinforcing layer is formed on the back surface thereof to obtain a mold base material on the master mold.

The obtained mold base material is released from the master mold,
This demolding may be performed immediately after the backup layer is formed.

After that, the first sprayed layer is removed from the die base material, which is performed by polishing or melting the first sprayed layer. Polishing is performed using sandpaper or an abrasive, and dissolution is performed using an oxidizing aqueous solution such as hydrochloric acid.

The exposed second sprayed layer serves as an underlayer of the mold surface, but since cavities caused by bubbles, crystal grains, etc. often remain in this second sprayed layer, copper or a copper alloy is formed on top of this. It is preferable to plate a soft metal such as the above and then polish the surface so as to close the bubbles.

Then, metal plating such as nickel plating or chromium plating is performed using the second sprayed layer as an electrode, and then surface finish polishing is performed as necessary.

[Action]

The mold of the present invention has a mold surface having a two-layer structure of an underlayer and a surface layer. Since the surface layer is composed of a metal plating layer, the surface of the mold surface is dense and has good durability. Since the underlayer, which occupies most of the thickness of the mold surface, is composed of the thermal sprayed layer, the mold surface formation requires less time and is less expensive than the case of plating alone.
Since the type of metal of this underlayer is copper and / or copper alloy, compared with zinc or zinc alloy, the current density at the time of metal plating can be easily obtained, and plating is easy. The backup layer keeps the shape of this mold surface. This backup layer also maintains the strength of the entire mold. In the mold of the present invention, the parts other than the mold surface are all made of resin in this way, so that the manufacturing cost does not increase and the delivery time can be shortened.

In making this resin mold, it is conceivable to spray copper or copper alloy directly on the surface of the master mold, but since copper and copper alloy are difficult to adhere to the master mold, the film obtained by direct spraying will be broken. easy. In this respect, according to the manufacturing method of the present invention, first, zinc or zinc alloy having good adhesiveness is thinly sprayed on the surface of the master die. Since copper or a copper alloy is easily compatible with zinc or a zinc alloy, copper or a copper alloy is sprayed onto the first sprayed layer made of this zinc or a zinc alloy to facilitate the adhesion.

Since the first sprayed layer is thin, it is easily broken when spraying copper or a copper alloy. In this respect, if a resin thin film is formed on this, it is possible to prevent the first sprayed layer from breaking. But,
If the first sprayed layer is made a little thick, the resin film need not be formed.

When the exposed surface of the second sprayed layer is plated with a soft metal such as copper to close the cavity in the second sprayed layer, the die surface is beautifully finished.

[Examples and Comparative Examples]

Hereinafter, examples of the present invention will be described in comparison with comparative examples.

-Practical example- A male mold (resin mold) used when casting a wash bowl with a width of about 500 mm was manufactured as follows. That is, a wood mold (master mold) having an inverted mold surface is first prepared, and the surface thereof is subjected to finish coating, and then a release agent (manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd., Epolak) is applied.
EP-11) was applied with a brush and dried at room temperature. Then, using an arc-type thermal spraying machine (TAFA, USA, 375EFS)
The first sprayed layer was formed by spraying to a thickness of 50 μm. Next, a solution of polystyrene (Sbright T-2 beads manufactured by Showa Denko KK) dissolved in toluene at a concentration of 20% by weight was applied onto the first sprayed layer, and dried at room temperature. Then, using the same arc type thermal spraying machine, copper was sprayed thereon to a thickness of about 2 mm to form a second thermal sprayed layer. After this, a carbon fiber cloth (Toray Industries, Inc., trading card cloth # 6341) and vinyl ester resin (Nippon Shokubai Chemical Co., Ltd., Epolak RF-1001H) were used to form the first packup layer. Laminate and harden it to a thickness of about 3 mm by the hand lay-up method, and place copper pipes with an outer diameter of 12 mm and an inner diameter of 10 mm at a pitch of about 40 mm on it. Granules (manufactured by Minato Aluminum Co., Ltd., aluminum granules # 8, average grain size 2.1 mm) were covered with resin concrete mixed with 200 parts by weight and cured. Next, a glass mat (MC-450A manufactured by Nitto Boseki Co., Ltd.) and an unsaturated polyester resin (Nippon Shokubai Kagaku Kogyo Co., Ltd. manufactured by Epolak G-753PTM) were used to handle the second backup layer. Approximately 15 mm with lay-up method
Was laminated and cured to a thickness of. In this way, a die base material was obtained on the wooden die (master die).

Next, the mold base is removed from the wooden mold, and the surface of the mold surface is polished with sandpaper to obtain the first
The sprayed layer was removed, the second sprayed layer was exposed, and the surface became a mirror surface. Then, metal chrome was plated on this surface to a thickness of 10 μm to obtain a male mold (resin mold) having a chrome-plated finish on the mold surface.

A female resin mold was also manufactured in the same manner as above.

Using the obtained male and female molds, a wash bowl was molded as follows. That is, hot water was passed through a mold pipe to keep the mold at 70 ° C., and 100 parts by weight of unsaturated polyester resin (Epolac G-227 manufactured by Nippon Shokubai Chemical Co., Ltd.) was used for aluminum hydroxide (Showa Denko KK). Higelite H-320) 150 parts by weight and a shrinkage reducing agent (Nippon Shokubai Kagaku Kogyo Co., Ltd., AT-100) 30 parts by weight and a curing agent (Kayaku Nouri Co., Kayaester O) 2 An unsaturated polyester casting material containing 1 part by weight was cast and cured, and after 1 hour, the product was taken out of the mold. In this case, the releasability at the time of demolding was good, and the finished product was also good. That is, the surface of the molded product was a beautiful mirror surface. Just in case,
The smoothness measured by a surface roughness meter was 20 μm or less.

-Comparative Example-Zinc is sprayed to a thickness of about 1.0 mm on the surface of the release-treated wooden mold using the arc spraying machine, and thereafter, the first backup layer is formed in the same manner as in the example. A resin concrete layer including pipes and a second backup layer were sequentially formed and cured, and then demolded to obtain a male mold (resin mold). A female mold was obtained in the same manner.

Using this male and female mold, an unsaturated polyester casting material was cast in the same manner as in the example to form a wash bowl.
In this case, the molded product could be scratched if care was not taken during the demolding. The surface of the molded product was slightly cloudy. The smoothness (surface roughness) of the mold surface of the resin mold according to this comparative example was 45 μm.

—Comparison— The durability of the mold surfaces of the resin mold of the example and the resin mold of the comparative example was examined as follows.

The molding described in the above examples was continuously performed using these molds, and the glossiness of the surface was visually observed each time a molded product was obtained.

The results were as follows. That is, in the resin mold of the example, even after 100 pieces were molded, the surface of the molded product had good gloss, and a beautiful molded product was obtained. On the other hand, in the resin mold of the comparative example, as the number of moldings increased, the surface gloss of the molded product gradually disappeared, and uneven gloss occurred. The molded product after molding 15 pieces had no surface gloss and was of no commercial value.

As can be seen from these results, the resin molds of the examples have excellent mold surface durability as compared with the resin molds of the comparative examples.

〔The invention's effect〕

Since the resin mold manufacturing method according to the present invention is configured as described above, it is possible to easily manufacture the resin mold in which the surface layer of the mold surface is the metal plating layer.

Continuation of the front page (56) Reference JP-A-56-56820 (JP, A) JP-A-60-121022 (JP, A) JP-B-38-25023 (JP, B1)

Claims (5)

(57) [Claims] 1. A mold release treatment is applied to the surface of a master mold to form a thin first sprayed layer made of zinc and / or a zinc alloy,
After forming a second sprayed layer made of copper and / or a copper alloy on it, a backup layer made of fiber reinforced resin is formed thereon, and a die base material is obtained on the master die. By removing the mold base from the master mold and removing the first sprayed layer, the second sprayed layer is exposed as an underlayer of the mold surface, and then the mold is placed on the second sprayed layer. A method of manufacturing a resin mold for forming a metal plating layer to be a surface layer of a surface. 2. The method of manufacturing a resin mold according to claim 1, further comprising the step of burying a heating / cooling molten pipe in the backup layer. 3. The embedding of a pipe comprises forming a first backup layer made of a fiber reinforced resin on a second sprayed layer, arranging the pipe on the first backup layer and correcting the irregularities with resin concrete, and thereafter, The method for producing a resin mold according to claim 2, which is performed by forming a second backup layer made of a fiber-reinforced resin on the substrate. 4. The resin according to claim 1, further comprising a step of forming a resin coating on the thin first sprayed layer to strengthen the first sprayed layer before forming the second sprayed layer. Manufacturing method of metal mold. 5. The method according to claim 1, further comprising the step of closing the cavity of the second sprayed layer by plating the surface of the second sprayed layer exposed by removing the first sprayed layer with a soft metal. The method for producing a resin mold according to item 1.