JPH07173668A - Production of electroforming metal mold - Google Patents

Abstract

PURPOSE:To stably produce an electroforming metal mold having many micropores for degassing and excellent strength by adding a specific levelingless agent to an electroforming liquid at the time of producing the electroforming metal mold by precipitating metal. on a base body by an electroforming method. CONSTITUTION:The many micropores are formed in the metal mold in order to remove the gases produced from raw materials, such as plastic, and the air in the metal mold at the time of casting and molding the plastic, etc., in the metal mold. A conductive layer is formed on the surface of the base body consisting of various kinds of resin suitable for the metal mold and thereafter, the metal mold is immersed in a plating liquid contg. metal ions of, for example, Ni, etc., and the base body is energized as a negative electrode to form an electrodeposited metallic layer 14 consisting of the Ni on the surface of the base body 10, by which the metal mold is produced at the time of the metal mold by the electroforming method. In such a case, the levelingless agent, such as benzene sulfonic acid, is added into the plating liquid, by which the many micropits 12 are formed on the surface of the base body 10 and the metal mold consisting of the Ni plating layer is formed on the parts exclusive of these parts. The electroforming metal mold in which the non-plating parts by the pits 12 form air permeable pares is stably produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electroforming mold, and more particularly to a method for manufacturing an electroforming mold suitable as a plastic molding mold.

[0002]

2. Description of the Related Art Conventionally, plastic blow molding,
A metal mold for vacuum forming or the like is provided with a large number of fine holes for removing gas generated from a parison as a molding material or a heated sheet and air in the mold during molding.

As a method for making these holes, a mechanical method is used in which a die is made and then the holes are made with a fine drill, or a porous electrodeposition layer is obtained in order to form the die itself from a porous body. There is an electrochemical method for manufacturing a mold by electroforming or the like.

However, the former method is not very preferable because it takes much cost and days because the work of forming a large number of small holes is very complicated. On the other hand, the latter mold becomes porous in the manufacturing process, so there is no problem in terms of cost and days, but due to the characteristics of the manufacturing method, the formation and shape of the holes are uncertain, and the wall around the holes is uncertain. However, there is a drawback that it is difficult to obtain the required strength as a mold because the thickness of the mold tends to be thin, or a precipitate containing fine air bubbles is likely to be formed. In addition, there is a problem that even if it can be used as a mold, it is very difficult to repair it if it is damaged during use.

Japanese Unexamined Patent Publication (Kokai) No. 5-156486 discloses a method for manufacturing an electroformed mold having a large number of vent holes formed by an electroforming method. The electroforming operation is carried out with an electroforming solution containing substantially no surfactant. The idea is that by not adding a surfactant such as sodium lauryl sulphate, which has been conventionally added to suppress the formation of pinholes, it occurs during electrodeposition on the non-conductive part that was previously made by drilling holes in the mother die. The hydrogen gas is easily accumulated, and the hole portion is allowed to grow as it is.

However, in the production of the electroforming mold, it is important to make the wall thickness uniform. For this reason, the wall thickness of the already electrodeposited portion is measured by taking out the electroforming solution at an appropriate time in the production process. After masking the portion reaching the prescribed wall thickness with a non-conductive material, it is placed again in the electroforming liquid and the electroforming operation is repeated. Usually, such work is repeated about 5 times, but the number of times increases or decreases depending on the shape of the mold.

However, when the electrodeposition is started again by putting it in the electroforming solution after the masking work, at the beginning of this electrodeposition, the hole portion is certainly concave due to the already electrodeposition, and the hole is formed. , When the electrodeposition is resumed, there is no hydrogen gas reservoir, so it is not a non-conductive part, and due to the leveling action of the electroforming liquid, the holes are gradually electrodeposited around the holes until the hydrogen gas accumulates Becomes smaller. in this way,
Since the phenomenon that the hole is finally eliminated by repeating the masking work is likely to occur, the same problem is unavoidable when the hole is formed in the electroformed mold with a drill as in the conventional case.

Further, since the above-mentioned method is a method of maintaining and growing holes previously drilled in the mother die by hydrogen gas generated in the electrodeposition process, minute hydrogen gas bubbles are generated by the leveling action of the electroforming liquid. However, the drawbacks of conventional porous molds, such as brittle precipitates that contain embedded metal, have not been resolved.

[0009]

Therefore, the present invention is
To provide a simple method for producing a porous mold by a new electroforming method, which solves the problems of insufficient strength, non-uniformity of pore structure and shape found in the conventional porous mold obtained by the electroforming method. With the goal.

[0010]

By the way, the inventors of the present invention add a levelingless agent to an electroforming liquid in the process of electroforming a conductive layer formed on an insulating substrate imitating a prototype. Then, the inventors have found that so-called pits (non-electrodeposited parts) are extremely easily formed and grow surely, which led to the present invention.

That is, in a broadest sense, the present invention is a method of manufacturing an electroformed mold in which a metal is deposited on a substrate by electroforming to form an electrodeposited metal layer, and leveling is performed in the process of depositing the metal on the substrate. A method for producing an electroforming die, which comprises using an electroforming solution containing a lacquer agent.

More specifically, in the present invention, a conductive or non-conductive substrate is prepared, and when the substrate is non-conductive, a conductive layer is provided on the surface of the substrate, and then a levelingless agent is added. This is a method for producing an electroformed mold in which a metal is deposited on the substrate by electroforming using an electroforming liquid to form an electrodeposited metal layer having a partially non-electrodeposited portion.

Here, the "levelingless agent" acts on the leveling performance of the plating electrolytic solution to reduce the lateral growth of the electrodeposition of the plating and positively in the longitudinal direction which is the thickness direction. Since it has a function of growing electrodeposition, it does not block the undeposited part (pit formation element) of electrodeposition generated due to various factors at the initial stage of electrodeposition, and has the function of growing with electrodeposition as a hole. It is something to demonstrate.

By the way, the "surfactant" functions by adsorbing to solid or liquid molecules, thereby enhancing the permeability or hydrophilicity of the substrate to be electrodeposited and the electroplating solution for plating, and In addition to facilitating the entry of the electroforming liquid into the fine parts of the surface, a thin film of air adhering to the surface of the substrate at the initial stage of electrodeposition, or hydrogen gas generated by the progress of electrodeposition and adhering to the electrodeposited surface It is intended to improve the detachability.

In the present invention, by further using an appropriate amount of a surfactant in combination, hydrogen gas generated during electrodeposition can be more easily desorbed from the electrodeposited surface, so that the amount of fine particles on the electrodeposited metal layer can be improved. It may be possible to improve the physical properties and the mechanical strength of the electrodeposited metal in order to prevent the incorporation of various hydrogen gas bubbles.

[0016]

The function of the present invention will be specifically described below. In carrying out the manufacturing method according to the present invention, first, a substrate having a shape imitating a prototype is prepared. The material forming the base may be either conductive or non-conductive and is not particularly limited, but as will be described later, the base is separated from the electroformed body to be cast. Therefore, it is preferable to use an inexpensive material as long as it is not intended to be reused, for example, a plastic material such as an epoxy resin, a polyester resin, a phenol resin, or a urea resin, which can easily give a predetermined shape.

Therefore, the base body is duplicated with an epoxy resin or the like on a predetermined surface shape such as a door trim of an automobile by using an inverted type of a product model. Next, the present invention will be described more concretely by taking an example of using a non-conductive epoxy resin as a material for forming the base.

Since the epoxy resin is originally an insulator, the surface to be transferred is continuously processed by utilizing a silver mirror reaction, which is a kind of chemical plating of silver, or by applying a conductive paint such as silver lacquer. A film-like conductive layer is formed.
When the silver mirror reaction is used for the conductive layer, the surface to be transferred of the substrate is subjected to degreasing treatment in order to enhance the adhesion of the conductive layer to the substrate prior to the molding of the conductive layer, and the stannous chloride solution is further added. It is desirable to further enhance the sensitivity by applying, for example.

In this way, the substrate having the conductive layer provided on the surface thereof is provided with an electrolytic plating solution of a predetermined composition containing a levelingless agent,
That is, it is placed in an electroforming tank filled with an electroforming solution, the conductive layer of the substrate is used as a cathode, and the other positive electrode is made of the same metal plate as the metal to be electrodeposited. Voltage is applied and electroforming is performed.

Usually, in order to prevent pits, the oxide film on the surface of the conductive layer is chemically removed and activated before being placed in an electroforming tank, and further, an aqueous solution of a surfactant is applied to make it hydrophilic. However, in the present invention, in order to positively generate the pits, it is desirable that the surface of the conductive layer is not dried and is put into the electroforming tank without drying.

The formation of the pits depends on the degree of a certain dielectric breakdown phenomenon during electrodeposition of the oxide film formed by air oxidation on the surface of the conductive layer after the conductive layer is formed as described above. It is generated by the degree of separation of the thin film of air adhering to the surface of the conductive layer during the bath, or by the discontinuity such as minute local recesses existing on the surface. Hydrogen generation is also promoted by adhesion of hydrogen gas generated due to a difference in overvoltage potential to the substrate or adhesion of dust (microscopic foreign matter) in the electroforming liquid to the electrodeposition surface. Of course, a large number of minute holes may be preliminarily formed on the substrate by mechanical means such as drilling.

In electroforming, pits (non-conductive parts)
In order to facilitate the formation of the above, hydrophobic non-conductive particles or the like may be sprayed onto the surface of the substrate as appropriate, or may be pre-blended in the resin.

In the case of a conductive substrate, it is not necessary to additionally provide a conductive layer when only the conductivity as the cathode is considered, but the electroforming mold is used by peeling the electrodeposited metal part from the substrate. Therefore, considering the convenience of peeling, it is desirable to provide a surface conductive layer for silver mirror reaction or the like as in the case of the non-conductive substrate. The electroforming operation itself may be a conventional one, including the composition of the electroforming liquid, other than containing the levelingless agent, and they are not limited in the present invention.

With the progress of electroforming, the non-electrodeposited portions (pits) formed grow due to the presence of minute remaining portions of the oxide film on the substrate surface or minute recesses on the substrate surface, which cause adsorption of the levelingless agent. By the action, the electrodeposited metal layer is stably stored and grown as it grows. Here, the concrete kinds of the levelingless agent used in the present invention will be explained as follows.

The levelingless agent used in the present invention, as its action, exerts activation control over diffusion control of the leveling agent during electrodeposition, and its component is benzenesulfonic acid or its derivative, formic acid. A carboxylic acid such as hemimellitic acid or a salt thereof, a nicotinic acid derivative such as nicotinic acid or nicotinic acid amide, methylputinol and a derivative thereof, and the like in appropriate amounts. Preferred leveling agents are benzenesulfonic acid, formic acid, nicotinic acid and methylputinol.
Because of the activation control, the crystal growth of the electrodeposited metal in the vertical direction of the substrate proceeds, but it hardly progresses in the horizontal direction, so that the pits remain.

That is, as shown in FIG. 1, according to the present invention, the pits 12 formed on the substrate 10 at the start of electrodeposition.
Is stably stored by the action of the levelingless agent, and so to speak, continues to grow as the electrodeposited metal layer 14 is formed. Figure 1 shows the pits existing on the surface of this substrate.
12 is a schematic diagram of how 12 is stored and grown. FIG.

As described above, when the levelingless agent is blended according to the present invention, the electrodeposition is activated and controlled by the action of the agent, so that the plating base metal remains in the shape, that is, the plating metal is not diffused in the pits. The bottom of the micro-recess, where current does not reach easily, is difficult to plate, and this tendency becomes more pronounced as the plating thickness increases. In spite of the growth of the plating layer, the non-electrodeposition part remains as it is.

In a preliminary test conducted by the present inventors to eliminate the leveling property of the electroforming liquid, benzenesulfonic acid or formic acid was added as a leveling-less agent to the nickel electroforming liquid having the standard composition, and the addition amount was 0.05 to 0.8 g. In the range of / L, it was possible to obtain a uniform electrodeposition without eliminating the polishing marks attached to the brass plate with # 800 file.

Also, when a nicotinic acid derivative or methylbutinol and its derivative were used as the levelingless agent, similar results were obtained within the addition amount of 0.001 to 0.1 g / L.

Also in a preliminary test for obtaining a perforated electroformed body, the non-deposited portion of the plating due to the hydrogen gas generated and attached to the silver mirror surface generated on the silver mirror surface at the initial stage of the electrodeposition due to the action of the levelingless agent remains unadhered As the plating grew, the unplated portion remained as a pit, and a perforated electroformed body was obtained.
In this state, electroforming is performed for several days to form a porous electroformed mold. Since the electroformed mold thus obtained has sufficient air permeability, it may be used as it is for the molding of plastics, but in order to further improve the strength, a backup layer may be provided for reinforcement. .

According to the preferred embodiment of the present invention, when it is judged that the thickness of the perforated electrodeposited surface formed as described above has reached the desired thickness, for example, 0.2 to 0.8 mm, the hydrophobic non-conductive material is used. An aqueous solution in which functional particles, for example, fine particles of a plastic material such as PTFE, are suspended with a surfactant or the like may be mixed in the electrolytic cell.

The fine particles such as PTFE in the electroforming liquid are diffused in the liquid by the action of the surfactant and the stirring of the electroforming liquid, and a part of them adheres to the electrodeposition surface of the substrate. Since the fine particles are uniformly diffused and dispersed, the fine particles are uniformly adhered to the electrodeposition surface of the substrate. Therefore, the adhesion density on the electrodeposition surface can be adjusted by adjusting the amount of fine particles to be mixed.

Thus, in the case of the above embodiment, since the fine particles existing in the state of being adhered to the electrodeposition surface, that is, the first electrodeposition metal layer is an insulator, the metal ion is not electrodeposited to that portion, This portion begins to become a recess for electrodeposition. Further, when the adhered fine particles are both an insulator and a hydrophobic property, hydrogen gas which is inevitably generated during electrodeposition is apt to adhere to the relevant part, and as a result, the lower perforated electrodeposited metal layer It begins to grow as a larger pit than the pit.

FIG. 2 is an explanatory view schematically showing the constitution of the electrodeposited metal layer at this time. The pits 12 grown as described with reference to FIG. 1 grow larger as the second electrodeposited metal layer 18 is formed on the first electrodeposited metal layer 14 and grow to form enlarged pits 20.

Since the non-conductive particles such as PTFE used in the above embodiment are uniformly dispersed in the electroforming solution as described above, they will adhere to the entire electrodeposition surface of the substrate. Since the above-mentioned pits are generated at each of the above positions, a second electrodeposited metal layer having a uniform communication hole structure can be formed from the middle of normal electrodeposition as a whole, which is preferable. The thickness of the second electrodeposited metal layer thus electrodeposited is not particularly limited, but generally about 2/3 to 3/4 of the total thickness will suffice.

Thus, the electroformed mold manufactured according to the present invention is an electrodeposited metal layer. The molding surface of the surface layer is a perforated electrodeposited metal layer due to the aid of the levelingless agent. The layer has a large number of so-called plating pits, and the strength of the molding surface is sufficient because it is a normal plating film except for the pit portions, and when further forming the above-mentioned second electrodeposited metal layer, if necessary, Since there are two layers of the porous electrodeposition layer from the middle, a predetermined porous electroforming mold that can be used as it is can be obtained.

[0037]

EXAMPLES Examples of the present invention will now be given, but it will be understood that they are provided merely as examples of the present invention and the present invention is not limited thereto.

(Example 1) A substrate having the surface shape of an automobile door trim was made of epoxy resin by using an inverted type. A conductive layer made of a silver thin film is formed on the substrate by a normal silver mirror reaction, and then placed in an electroforming tank.

The substrate thus prepared is used as a cathode,
On the other hand, a small piece of nickel contained in a metal titanium basket case was used as an anode, and electrodeposition was carried out in an electroforming tank filled with an electroforming solution which was an electrolytic plating solution having the composition shown in Table 1. The electrodeposition conditions at this time are shown in Table 1. In this example, the levelingless agent described above was used.

[0040]

[Table 1] Electroforming solution for forming the first layer: Nickel sulfamate 300 to 400 g / L Nickel chloride 5 to 10 g / L Boric acid 30 to 40 g / L Surfactant Suitable amount Levelingless agent (benzenesulfonic acid) 0.1 ~ 0.5 g / L Electrodeposition conditions: pH 3 ~ 4 Temperature 40 ~ 50 ℃ Current density 0.5 A / dm ² period 4 days The electroformed mold produced has an electrodeposited metal layer thickness of 0.3 ~ 0.5.
It was an electroformed body having about 70 pits (holes) of 10 to 20 μm per mm ² and 1 dm ² .

Example 2 After completion of electroforming in Example 1, 0.02 to 0.02 of PTFE particles having a particle size of 5 μm were further added to the second electroforming solution described below.
05g / L was blended and the electrodeposition work was continued for another 2 days. The obtained electroformed body having a two-layer structure had sufficient air permeability. Electroforming solution for forming second layer: Nickel sulfamate 300 to 400 g / L Nickel chloride 5 to 10 g / L Boric acid 30 to 40 g / L Surfactant Suitable amount Polytetrafluoroethylene (PTFE) 0.02 to 0.05 g / L

[0042]

The electroformed mold manufactured according to the present invention is
As described in detail above, since it is composed of a porous electrodeposited metal layer, even when producing such a porous electroformed body, as in the conventional method, on the conductive layer of the substrate The insulating parts for forming the micropores are scattered in advance, but the non-electrodeposition part formed thereby continues to grow as it is by using the levelingless agent, and the predetermined strength of the electrodeposited metal is obtained, Moreover, the micropores are not filled, and therefore the mechanical strength of the electroformed mold is increased.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing how an electrodeposited metal layer and pits (non-electrodeposited layer) grow when electrodeposition is performed using an electroforming solution containing a levelingless agent according to the present invention.

FIG. 2 is a schematic view similar to FIG. 1 showing a preferred example of the present invention.

Claims (1)

[Claims] 1. A method for producing an electroformed mold, in which a metal is deposited on a substrate by electroforming to form a metal electrodeposition layer,
A method for producing an electroforming die, which comprises using an electroforming solution containing a levelingless agent in the process of depositing a metal on a substrate.