JPH0768632B2 - Method for manufacturing master block for electroforming - 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 producing a mother die for electroforming, for producing a porous forming die used for vacuum forming plastic molded articles by electroforming.

[0002]

2. Description of the Related Art When manufacturing a plastic molding die by electroforming, for example, a so-called gel coat is applied to the surface of an inversion die made of, for example, a silicon resin having an uneven shape opposite to the original die having the same shape as the molded article. After being cured and further backed with a plurality of layers of epoxy resin, the epoxy resin is released from the reversal mold to manufacture a master mold having the same concavo-convex shape on the surface as the master mold.
Then, a conductive layer is formed on the surface of the mother die by, for example, a silver mirror reaction, and electroforming is performed using the conductive layer as a cathode to electrodeposit nickel on the surface of the mother die to a predetermined thickness, and the electrodeposition thereof is performed. The nickel layer is released from the mother die to obtain a molding die.

In recent years, therefore, a technique has been developed for producing a porous mold used for vacuum molding of plastic molded products by such electroforming.
As a technique for producing such a porous mold, there is one disclosed in Japanese Patent Laid-Open No. 60-152692. In this technique, instead of the silver mirror reaction, a spray liquid in which a conductive paint is mixed with an insulating lacquer is sprayed on the surface of the mother die to make the surface layer of the mother die mottled between the conductive portion and the insulating portion. By performing electroforming on the mold, a porous mold is obtained.

Further, as a technique different from that, there is one disclosed in Japanese Patent Laid-Open No. 61-253392. This technique consists of forming a silver conductive layer on the surface of the matrix by silver mirror reaction and then applying a silver corrosive agent to the conductive layer.
A part of silver is removed so that the surface layer of the master mold has a patchy pattern of conductive parts and insulating parts, and electroforming is performed on the master mold to obtain a porous mold.

[0005]

By the way, the above-mentioned porous molding die is used for molding, for example, an instrument panel of an automobile. In recent years, a molded article of this kind has a design problem. In order to meet the demand, a fine uneven pattern such as a leather grain pattern is formed on the surface. in this case,
On the surface of the prototype, affix a vinyl leather having a leather grain pattern, in a state where the uneven shape of the surface of the prototype is maintained,
By repeating inversion with a reverse mold, a mother mold, and a molding mold, the leather grain pattern is transferred to the surface of the molded product.

However, in the above-mentioned conventional technique, the spray liquid is sprayed on the surface of the master mold separated from the reversal mold, or the silver layer having a large number of holes is attached thereto. The surface of the mother die was roughened by the spray liquid and the silver layer, and the transfer accuracy was lowered. In this case, the paint has a thickness of about 10μ,
The silver layer formed by the silver mirror reaction also has a thickness of about 5 μ, but this makes it impossible to transfer a fine uneven pattern such as a skin grain pattern.

Further, in the above-described conventional method for producing a master mold, when the gel coat is applied to the surface of the reversal type, a curing agent for shortening the pot life is added, so that the viscosity of the gel coat is relatively high. It becomes taller and often entraps fine bubbles. As a result, bubbles appear as pinholes on the surface of the mother die, which again deteriorates the transfer accuracy.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a mother die for producing a porous molding die for electroforming which is excellent in transfer accuracy of the uneven shape of the surface of the master die. To provide a manufacturing method of the master mold of

[0009]

[Means for Solving the Problems]

The method for producing a master mold for electroforming according to the present invention comprises:
A step of adhering and curing an insulating paint in the form of many fine spots on the surface of the reversing mold having the concavo-convex shape opposite to the original mold having the same shape as the molded product, and a conductive paint on the entire surface of the reversing mold from above the insulating paint A step of adhering and curing, a step of adhering and curing a backing material on a paint layer composed of the insulating paint and a conductive paint, and releasing the paint layer from the reversal mold together with the backing material to the master mold on the surface. It is characterized in that a step of obtaining a mother die having a paint layer having the same concavo-convex shape is executed.

[0011]

[Action]

[0012]

According to the method for producing a master mold for electroforming of the present invention, the coating layer adhered and cured on the surface of the reversing mold is released from the reversing mold together with the backing material. It is possible to obtain a mother die having a surface layer in which the surface irregularities are directly transferred to the surface. At this time, since the surface of the mother die is in a state in which the insulating portion formed by the insulating coating appears in the form of a number of fine spots in the conductive portion formed by the conductive coating, it is possible to perform surface treatment after releasing from the reversal type. By performing electroforming using this mother die, a porous electrodeposited metal can be easily obtained.

Therefore, it is possible to maintain the surface shape of the master mold in a state of being released from the reversal mold without roughening the surface of the master mold, and to apply a paint having a relatively low viscosity to the surface of the reversal mold. Therefore, as compared with the case where gel coating is performed, there is almost no risk of entraining air bubbles, and it is possible to prevent pinholes from being generated on the surface of the matrix as much as possible.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a mother die 1 according to the present embodiment. This mother die 1 is for producing a porous molding die for vacuum molding of plastic by electroforming, as will be described later. belongs to.

In this mother die 1, the surface layer on which electrodeposition is performed is
The paint is a hardened paint layer 2, and the back surface of the paint layer 2 is provided with a backing layer 3 made of a backing material having an FRP structure if epoxy resin and reinforcing fibers are laminated. ing. The coating layer 2 is composed of a conductive portion 2a made of a conductive coating material that is adhered and hardened over the entire upper surface of the backing layer 3, and an insulating coating material that is adhered and hardened in a myriad of fine spots on the surface of the conductive portion 2a. Insulation part 2b
It consists of and.

Now, a procedure for manufacturing the mother die 1 will be described with reference to FIG. FIG. 2A shows a prototype 4 made of, for example, a wooden mold, and the prototype 4 has the same outer shape as that of a molded product (not shown). Although not shown, a vinyl leather having a fine relief pattern such as a skin grain pattern is attached to the surface of the master 4 as needed.

Next, a step of manufacturing the reversal mold 5 shown in FIG. 2B from the master mold 4 is executed. This inversion type 5
Is cast on the surface of the master 4 to cure it, and then released from the master 4 to obtain an inversion mold 5 having an uneven shape opposite to the outer shape of the master 4. In this case, since it is manufactured by the casting method of silicon resin, high transfer accuracy can be obtained, and the master mold 4 having a complicated shape such as an undercut shape can be applied.

Then, the master mold 1 is manufactured by further inverting the reverse mold 5, but in this embodiment, first, as shown in FIG. A step of adhering and curing the insulating paint in the form of many fine spots on the inner surface is performed. Here, the insulating paint is sprayed toward the inner surface of the reversing mold 5 in the form of a mist, for example, by spraying, so that the insulating paint is attached in the form of many fine spots. By hardening the insulating paint, the insulating portion 2b of the paint layer 2 is first formed in a form of being attached to the inner surface of the reversing mold 5.

Subsequently, as shown in FIG. 2 (d), a step of adhering and curing a conductive paint on the entire inner surface of the reversing mold 5 from the insulating paint (insulating portion 2b) to a predetermined thickness is performed. It Also in this step, for example, by spraying, the inversion type 5
Is performed by spraying a conductive coating toward the inner surface of the surface of the inner surface of the sheet, and the conductive section 2a is cured on the front side by curing the conductive coating.
The coating layer 2 in which the insulating portion 2b and the insulating portion 2b are mixed in a so-called spot shape and the conductive portion 2a is entirely formed on the back surface side is formed in a form of adhering to the inner surface of the reversing mold 5.
At this time, since the insulating paint and the conductive paint have relatively low viscosities, there is no possibility that air bubbles will be caught between the inner surface of the reversing mold 5 and the paint layer 2.

After that, as shown in FIG. 2E, a step of adhering and curing a backing material on the paint layer 2 is carried out. As a result, the backing layer 3 formed by laminating the epoxy resin and the reinforcing fibers on the back surface of the coating layer 2 is formed. Finally, a step of releasing the paint layer 2 from the reversal mold 5 together with the backing layer 3 is carried out, and as shown in FIG.
As shown in (f), the matrix 1 having the coating layer 2 on the surface of the backing layer 3 is obtained.

The master 1 has a coating layer 2 on the surface of which the uneven shape of the inner surface of the reversing mold 5 has been inverted and transferred, in other words, the uneven shape of the surface of the master 4 has been transferred as it is. Is manufactured. Then, as described above, the surface of the mother die 1 is in a state in which there are innumerable minute speckled insulating portions 2b in the conductive portion 2a.

Thereafter, electroforming is performed using the mother die 1 manufactured as described above, so that the porous molding die 6 can be obtained as shown in FIG. 2 (g). Here, this electroforming process will be briefly described.

That is, although not shown, the mother die 1 is placed in, for example, a nickel electroforming bath, and the coating layer 2 (conductive portion 2) is formed.
A direct current is passed between the nickel electrode and a). Then, nickel metal is electrodeposited on the surface of the mother die 1 (paint layer 2). At this time, the surface of the paint layer 2 has a so-called spot-like shape because the conductive portion 2a and the insulating portion 2b are so-called mottled.
Nickel is deposited on the surface of the conductive portion 2 and the conductive portion 2
An excessive electric field is generated at the boundary between a and the insulating portion 2b, a large number of fine bubbles such as hydrogen gas are generated, and nickel grows while extending so as to enclose the bubbles.

As the nickel electrodeposition progresses, the mother die 1
Further bubbles are generated toward the outside of the mother die 1 so as to be continuous from the bubbles generated on the surface portion of nickel, and nickel is further deposited while enclosing the bubbles while extending. In this case, the bubbles gradually increase in diameter from the surface of the matrix 1 to the outside. After the electrodeposition of a predetermined thickness (for example, 3 mm) is completed, the electrodeposited nickel layer is released from the mother die 1 to form a porous structure having a large number of pores 6a continuous in the thickness direction as shown in FIG. The molding die 6 is obtained. The surface of the molding die 6 is in a state in which the concave and convex shape of the surface of the mother die 1 is directly transferred as it is. Therefore, the outer shape of the mother die 1 and then the master die 4 is formed on the surface of the vacuum molded product using the molding die 6. The same uneven shape is transferred.

According to the master mold 1 of this embodiment manufactured as described above, the coating layer 2 adhered and hardened on the inner surface of the reversing mold 5 is released from the reversing mold 5 together with the backing layer 3. Therefore, it was possible to obtain the mother die 1 having the coating layer 2 in which the uneven shape of the surface of the reversing mold 5 was reversely transferred to the surface as it was. At this time, the surface of the mother die 1 is in the conductive portion 2a,
Since the insulating portion 2b is formed in a state where a large number of fine spots are formed, it is possible to obtain a surface state for manufacturing the porous molding die 6 without performing surface treatment after releasing from the reversing die 5. You can

Therefore, unlike the conventional one in which the transfer accuracy is undesirably lowered by roughening the surface of the master mold because the paint or the silver mirror layer is attached to the surface of the master mold after releasing from the reversal mold. It is possible to reliably transfer a fine concavo-convex pattern such as a leather grain pattern and to obtain extremely high transfer accuracy. By the way, according to the method of the present embodiment, 0.
It became possible to transfer the uneven pattern of about 1μ.

Moreover, instead of the conventional method of reversibly transferring the uneven shape of the inner surface of the reversing mold to the surface of the mother die by gel coating with a resin, a paint is adhered and cured on the inner surface of the reversing mold 5 to form the coating layer. 2 to form the concavo-convex shape of the reversal mold 5
Since the reverse transfer is performed on the surface of the mold 1, it is possible to prevent the inclusion of fine bubbles, and to prevent the generation of pinholes on the surface of the mother die 1.

Incidentally, the conventional gel coat is
According to the method of the present example, about 600 pinholes were found to be generated within a 5 mm square on the surface of the matrix.
Only a few pinholes were generated in the same area. As a result, according to the present embodiment, the transfer accuracy is extremely excellent in addition to the fact that the surface of the mother die 1 is not roughened.

According to the mother die 1 of this embodiment, the surface condition required for manufacturing the porous molding die 6 can be obtained by spraying the reversing die 5 with the insulating paint and the conductive paint. . Therefore, the step of performing the surface treatment on the master mold which has been released from the reversal mold, which has been conventionally required, becomes unnecessary, the manufacture of the master mold 1 becomes easy, and the master mold having an extremely excellent transfer accuracy as compared with the conventional one. 1 can be manufactured at a lower cost.

Further, in the mother die 1 of this embodiment, the coating layer 2
Since the insulating portion 2b is formed only on the main portion on the front surface side of the paint layer 2 with respect to the conductive portion 2a which is continuous on the entire back surface of the mother die 1 on the back side of It is also possible to obtain an advantage that a current can be stably supplied during processing.

The present invention is not limited to the above embodiments, and the material of the prototype 4, the reversal type 5, the backing layer 3, etc. can be changed as appropriate and within the scope not departing from the gist. Various modifications are possible.

[0033]

As is apparent from the above description, according to the present invention, there is provided a method for producing a porous mold by electroforming, which is extremely accurate in transferring the uneven shape of the surface of the master. It has an excellent practical effect that an excellent mother die can be easily manufactured at low cost.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a partially enlarged vertical sectional view of a mother die.

FIG. 2 is a diagram for explaining a mother die manufacturing process.

FIG. 3 is a partially enlarged vertical sectional view of a porous molding die.

[Explanation of symbols]

In the drawings, 1 is a mother mold, 2 is a paint layer, 2a is a conductive part, 2b is an insulating part, 3 is a backing layer, 4 is a master, 5 is a reverse mold, and 6 is a porous mold.

Claims (1)

[Claims] 1. A step of adhering and curing an insulating coating material in the form of a large number of fine spots on a surface of a reversing type having a concavo-convex shape opposite to that of a prototype having the same shape as a molded product, and a conductive coating on the entire surface of the reversing type A step of adhering and curing from above the insulating paint, a step of adhering and curing a backing material onto a paint layer consisting of said insulating paint and a conductive paint, and releasing said paint layer from said reversal mold together with said backing material And a step of obtaining a mother die having a coating layer having the same uneven shape as that of the master die on the surface thereof, the method for producing a mother die for electroforming.