JPS63212529A - Vacuum molding method for synthetic resin molded product - Google Patents

Abstract

PURPOSE:To adsorb a substance to be molded which is composed of synthetic resin material on the surface side of a mold main body by reducing the pressure of the back side of the mold main body having a number of through-holes running through the surface and back which are provided by means of growing, at the time of electroforming, micro non-electrodeposited sections generated at the initial stage of electroforming. CONSTITUTION:A number of through-holes 2 running through a mold main body 1 are provided by growing micro non-electrodeposited sections generated at the initial stage of electroforming in the thickness direction, and as the diameters are small enough on the surface side of the mold main body 1, the traces of through-holes 2 are not remained on the surface of a molded product, while the diameters are large on the back side of the mold main body 1 which lower air current resistance at the time of vacuum suction and strengthen suction force. When vacuum molding, therefore, a substance W to be molded which is composed of synthetic resin material is sucked strongly through a number of through-holes 2 of the mold main body 1 and adhered to the surface of the mold main body 1. Also, through-holes 2 are seldom clogged and the inside of the through-holes 2 can be cleaned easily.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for vacuum forming synthetic resin molded products using a porous molding die formed by electroforming.

(Prior art and problems to be solved by the invention) Conventionally,
To form a porous mold for vacuum forming, the mold can be molded using a thermal spraying method to make it naturally porous, or it can be mixed with synthetic resin material, molded into a mold, and then dehydrated. A method of making it porous was used.

However, in these methods, the holes are too small to perform vacuum suction during vacuum forming, and the holes are not penetrating and are easily clogged, making cleaning the holes difficult.

Another method used was to form molds using electroforming, which is an applied technology for plating. This m-poetry method will be briefly explained below.

■ First, a conductive coating film, such as a spray liquid containing a mixture of paste sample lacquer and butyl acetate solution, is sprayed onto the model to be electroformed (hereinafter referred to as the mandrel) to impart conductivity to the mandrel. .

■ Next, add pure water! A pretreatment solution containing till and stannous chloride is applied to the mandrel using a brush or the like to activate the surface of the mandrel and perform pretreatment to prevent pinholes from forming.

■ Next, perform electroforming. The electrolytic solution used is one in which a nickel sulfamate solution and boric acid are mixed, and then a small amount of sodium lauryl sulfate, for example, is added as a surface active additive. This sodium lauryl sulfate prevents pinholes from forming in the electrodes on the surface of the mandrel during electroforming.

The electroformed material and the mandrel are immersed in the electrolyte stored in the electrolyte tank, the electrolyte is circulated, and the cathode rocker is operated to move the mandrel in the electrolyte. In between, apply a current of 0°6A per W4100c+eL of the mandrel for 3 to 4 hours, and cover the entire surface of the mandrel! Electrodeposit a thin casting layer.

11fuW! After confirming that I has been thinly electrodeposited, the current is changed to 1 to 2 A per mandrel surface W4100 cm, and electroforming is continued to make the electroformed surface smooth to the desired shape. Mandrel and 1! Separate from the casting rib to form the mold body.

(2) A porous mold is completed by making a large number of small holes in the mold body formed as described above using a cone with a diameter of 0.31 mm at the tip or a laser beam.

However, even in the electroforming molds mentioned above, not only is the work of forming a large number of small holes extremely complicated, but in the case of molds with complex shapes, holes may be made transparent depending on the location. The problem was that it could not be done.

Therefore, when such a mold is used for vacuum forming, there are problems in that it is difficult to perform vacuum suction, and the through holes become clogged, making it difficult to clean the insides of the through holes.

This invention was made in order to solve the above-mentioned problems, and its purpose is to form a vacuum molding device that facilitates vacuum suction, reduces the possibility of clogging of the through hole, and facilitates cleaning of the inside of the through hole. The purpose is to provide a method.

Structure of the Invention (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a mold body formed by electroforming, in which minute non-electrodepositions generated in the early stage of electroforming are used. By reducing the pressure on the back side of the mold body, which has a large number of through holes penetrating between the front and back surfaces, the molded object made of a synthetic resin material is passed through the through holes. We adopted a method of adsorbing it to the surface side of the mold body.

(Function) When the pressure is reduced on the back side of the mold body, air on the front side of the mold body is sucked through the many through holes of the mold body. Since this through hole is made by allowing a minute non-1 to pass through by growing its neck, the airflow resistance during vacuum suction is low, and the molded object is strongly attracted to the mold body. Moreover, the through holes are less likely to become clogged.

(First Embodiment) A first embodiment embodying the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a mold body according to the present invention, which is formed by N casting.・2 is a large number of through holes provided through the mold body 1, and as described later, the minute non-Wi deposited portions generated at the initial stage of the same casting are removed in the thickness direction ( It is formed by growing between the front and back surfaces of the mold body 1, and as shown in FIG. 3(b), the mold body 1
The diameter gradually increases from the front to the back. In addition,
The shape of the through hole 2 is shown in a simplified tapered shape as shown in FIG. 3(b), but i! It goes without saying that the way it spreads varies depending on the castability. 1 For example,
The inner surface of the through hole 2 may be uneven, or adjacent through holes 2 may be connected to each other.

The maximum diameter of this through hole 2 on the surface side of the mold body 1 is 0.
It is desirable that it is 1 to 0.5 aa+. While it is necessary to increase the vacuum suction power, there are two through holes in the specially molded synthetic resin product.
This is to prevent any traces from remaining. Further, the number of through holes 2 is desirably 5 to 10,000 per 10 cm of area of the mold body 1 from the viewpoint of vacuum suction force.

This mold body 1 is placed on a vacuum forming device, and the same vacuum forming device! By driving the suction pump P of D and reducing the pressure on the back side of the mold body 1, the numerous through holes 2 of the mold body 1 are
Air on the surface side of the mold body 1 is sucked through the mold body 1, and vacuum forming is performed. During this vacuum forming, the molded object W made of a synthetic resin material is strongly attracted through the many through holes 2 of the mold body 1 and is brought into close contact with the surface side of the mold body 1.

Since the through hole 2 is penetrated by growing a minute non-tR portion, the air flow resistance during vacuum suction is low (vacuum suction is easy to perform).

In addition, the through hole 2 is less likely to be clogged (and the inside of the through hole 2 can be easily cleaned).Furthermore, since the through hole 2 is formed at the same time as electroforming, the through hole 2 can be opened after Wll. There is no need to perform the second forming step, and the mold can be manufactured easily.

Further, the diameter of the through hole 2 of this embodiment gradually increases on the back side of the mold body 1 as electroforming progresses. Therefore, the diameter of this through hole 2 is sufficiently small on the front side of the mold body 1, so that not only no trace of the through hole 2 remains on the surface of the molded product, but also the diameter is large on the back side of the mold body 1. ' Therefore, the airflow resistance during vacuum suction is lowered, and the suction force is increased, which is a practical effect for the mold.

That is, in conventional electroforming technology, pinholes occur irregularly and unstablely, and are thick (appear) on the surface, so they have been considered to be defects that must be avoided at all costs.

In contrast, in the present invention, the minute non-electrodeposited portions generated at the initial stage of electroforming are allowed to grow during the same electroforming process, so that the holes 2 are formed not as pinholes but as minute through holes 2 that can be used during vacuum suction. It can be said that this mold is an epoch-making mold based on a completely reversible idea.

As described above, the use of the mold body 1 having a large number of through holes 2 through which the minute non-electrodeposited portions generated at the initial stage of electroforming are grown during the same electroforming process is used for vacuum forming. It is very effective in terms of the direction of vacuum suction force, the ease of maintenance such as vacuum maintenance, cleaning, and the ease of manufacturing molds.

Next, the equipment, materials, etc. used to manufacture this mold body 1 will be explained.

3 is an electrolytic solution stored in electrolytic solution tank A as shown in FIGS. 2(a) and (b), which is composed of a nickel sulfamate solution of 450 (J) and boric acid of 40 Q or more. Its temperature is maintained at 37° C. to 40° C. The pH value of this electrolyte 3 is adjusted to remain within the range of 3.8 to 4.2 by adding nickel chloride agent as an additive. ing.

If the pH value of the electrolytic solution 3 exceeds the above range, the cathode current efficiency during electroforming will decrease, but if the pH value of the electrolytic solution 3 exceeds the above range,
．． If it does not reach 8, basic precipitates will be formed in the electrolytic solution 3, causing defects such as the electrolyzed metal becoming more likely to discolor.

Here, since the electrolytic solution 3 of this example does not contain a surfactant additive such as sodium lauryl sulfate, it has no effect of suppressing the formation of pinholes.

Therefore, non-electrodeposited portions (which were the seeds of pinholes in the past) are likely to occur in the initial stage of electroforming, and the growth of through holes 2 is also promoted.

Reference numeral 4 denotes an electroformed material placed in the electrolytic solution 3, and nickel is used in this embodiment.

5 is a mandrel placed at a position facing the electroforming material 4 in the electrolytic solution 3, and is made of a synthetic resin material such as epoxy, acrylic, acrylic-butadiene-styrene copolymer, vinyl chloride, solid wax, or metal. , made of wood, ceramics, fabric, thread, etc. This mandrel 5 is a model of the mold body 1 shown in FIGS. 1 and 3(b), and is suspended from a cathode rocker 6 movably attached to the upper end of the electrolyte tank A. (b
), the cathode rocker 6 moves back and forth in the electrolytic solution 3 in accordance with the movement of the cathode rocker 6 in the length direction.

Note that 7 is a moving device that drives the cathode locker 6 back and forth. In addition, a power source S is provided outside the electrolyte tank A,
Electroforming material 4 is applied to the anode and sprayed with mandrel 5!
8 are each electrically connected to the cathode.

Next, a method for manufacturing the mold body 1 will be explained in order.

(2) In order to make the mold body 1 porous, the mandrel 5 is subjected to a surface treatment process and a racking process before being immersed in the electrolytic solution 3.

First, in the surface treatment step, the surface of the mandrel 5 is polished with an abrasive such as a solvent or polishing powder to remove impurities attached to the surface and roughen the surface. The purpose of roughening the surface is to improve the compatibility of the conductive material and to improve the adhesion of the electroformed film. After this, mandrel 5
is washed with water to remove the abrasive on the surface, and then dried with jet air to complete the surface treatment process.

In the racking process, a spray liquid is injected onto the desired surface of the mandrel 5 for electroforming to impart conductivity. This spray liquid was prepared by mixing a paste test lacquer (RC-10 manufactured by Kashitsu Metal Powder Co., Ltd. was used in this example) and a butyl acetate solution in a ratio of 1=1. It is made by mixing vinyl chloride lacquer liquid at a ratio of 30% or less to the total liquid m.

This spray liquid is sprayed twice until the surface of the mandrel 5 exhibits a complete metallic color to form a spray 118 of approximately 15 μm or more on the surface of the mandrel 5 as shown in FIG. 3(a). 5 is naturally dried for about 24R. Since the spray liquid contains a vinyl chloride lacquer liquid, the spray layer 8 on the surface of the mandrel 5 has low conductivity, and a large number of holes 2 are likely to be formed on the surface of the mandrel 5.

Looking at it more microscopically, the spray layer 8 not only has conductive parts made of silver powder, but also minute non-conductive parts are formed by the vinyl chloride lacquer scattered in the silver powder, so the overall conductivity is low. It is. In the minute non-conductive parts made of vinyl chloride lacquer, is there an electroforming material used in the early stages of electroforming, which will be described later? Since it is difficult to form ff1L, it greatly contributes to the generation of minute non-electrodeposited areas.

By adjusting the degree of mixing of the vinyl chloride lacquer liquid in the spray liquid, the conductivity of the surface of the mandrel 5 can be freely set, and the size and distribution of the non-conductive parts can be changed. It is possible to change the dimensions of the mandrel 5 and to freely manage the number of through holes 2 per unit area of the mandrel 5 and the aperture ratio. Accordingly, Figure 4<a
It is also possible to form many through holes 2 only in a part of the mold body 1 surrounded by the two-point ta line, as in the mold shown in >.

As shown in FIG. 4(b), this part has an uneven part 10 for forming wrinkles and an uneven part 11 for forming threads such as stitches, so by increasing the number of through holes 2, it is possible to W
This uneven portion 10. is firmly brought into close contact with the mold body 1.
11 can be attached to the molded object W.

Also, other insulating materials may be used in place of the vinyl chloride lacquer solution as a contaminant in the spray solution.

Note that a silver plating film may be provided on the surface of the mandrel 5 to impart conductivity before the racking step.

After the racking process is finished, the mandrel 5 is washed with water again to remove foreign matter from the surface, and the pretreatment of the mandrel 5 is completed.

(2) In this embodiment, the step of activating the surface of the mandrel 5 using a pretreatment liquid in the prior art is omitted. This is to facilitate the formation of minute non-WIW portions on the surface of the mandrel 50 at the initial stage of electroforming.

(2) Subsequently, the mandrel 5 and the electroformed material 4 are immersed in the electrolytic solution 3 in the electrolytic solution tank A. At this time, the electrolytic solution 3 is in a stopped state without being circulated, and the moving device 7 of the cathode locker 6 is in an OFF state, so the mandrel 5 also does not move. This is to facilitate the generation of minute non-electrodeposited portions.

[With source S on, the area of mandrel 5 is 100012
When a current of 3 A is passed between the electroformed material 4 and the spray I18 of the mandrel 5, the electroformed material 4 is electrolyzed and coated on the spray WJs of the mandrel 5, forming m casting L19.

At the beginning of this electroforming process, as mentioned above, one layer of spray 8
Among these, the electroforming material 4 is well electrodeposited on the conductive parts made of silver powder, but it is difficult to electrodeposit the electroforming material 4 on the minute non-1'f1 parts made of vinyl chloride lacquer dotted in the silver powder. A minute non-electrodeposited portion is generated starting from this non-conductive portion.

As electroforming progresses, this minute non-electrodeposited portion grows to become a through hole 2.

In particular, in this embodiment, in addition to the presence of this non-conductive part, as described above, techniques such as adjusting the composition of the electrolytic solution 3, omitting the surface activation treatment of the mandrel 5, stopping the cathode rocker 6, and adjusting the current are used. is added, the generation and growth of the non-electrodeposited portion is further facilitated.

Further, in this embodiment, the through holes 2 grow not only in the thickness direction of the electroformed layer 9 but also in the radial direction as electroforming progresses, and the through holes 2 grow in the mold body 1.
The back side of the hole is a through hole 2 with an enlarged diameter.

Then, r! is applied to the entire desired surface of the mandrel 5! i After confirming that the cast layer 9 has been covered and that a large number of through holes 2 have been formed in the electroformed W 19, a current is applied to the area 1 of the mandrel 5.
Drop it to about 1-2A per 00cm2. Thereafter, by circulating the electrolytic solution 3 and further operating the cathode rocker 6, the cathode current density is made uniform, so that the thickness of the electroformed n9 becomes uniform.

(2) When the surface of the mandrel 5 is electroformed as described above, the mandrel 5 is taken out from the electrolytic solution 3 and dried. After this, the electroformed FJ9 is peeled off from the mandrel 5. It should be noted that since the spray layer 8 is interposed on the surfaces of the electric VI layer 9 and the mandrel 5, the 'Wi cast layer 9 can be easily peeled off. The 18 layers 9 removed from the mandrel 5 are used as the mold body 1 of the mold.

(Second example) Next, a second embodiment of the invention will be described.

In this example, surfactant additives such as sodium lauryl sulfate are not added to the electrolyte 3 as in the first example, but the other steps are different from those in the first example.
It is performed in the same way as casting.

In this case, since the generation of bottle balls on the surface of the mandrel 5 is promoted only by the modification of the electrolytic solution 3, the rate of occurrence of the through holes 2 is extremely low compared to the case of the first embodiment.

In addition to this electroforming method, vinyl chloride lacquer is mixed into the spray liquid in the pretreatment of the mandrel 5, and the spray F
18, the incidence of through holes 2 can be increased somewhat.

Furthermore, (1) In the pretreatment of the mandrel 5, no pretreatment liquid is used.

(2) During electroforming, the electrolytic solution 3 is not circulated, and the cathode rocker 6 is also kept in a stopped state.

(3) Applying a stronger current than usual during electroforming.

By appropriately combining the following steps, the mold body 1
The number of through holes 2 can be managed.

Note that this invention is not limited to the above-described embodiments; for example, other metals that can be electrolyzed with positive ions may be used instead of nickel as the rR casting material 4, as long as they do not deviate from the spirit of the invention. Any changes are possible.

Effects of the Invention As detailed above, the present invention provides a mold body having a large number of through holes formed by growing minute non-electrodeposited portions generated at the initial stage of electroforming. When used in vacuum forming, it has excellent effects such as easy vacuum suction, less clogging of the through holes, and easy control of the inside of the through holes.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the usage state of the mold according to this example,
FIG. 2(a) is a schematic diagram showing an electroforming method for manufacturing a mold, FIG. 2(b) is a plan view of FIG. 2(a), and FIG.
a) is a cross-sectional view showing the state in which 'Fi casting is applied to the mandrel;
Fig. 3(b) is a partially broken enlarged sectional view of the mold, Fig. 4(a)
) is a plan view showing the separate molds, and FIG. 4(b) is the fourth
FIG. 2 is an enlarged sectional view taken along line BB in FIG. Mold body 1, through hole 2, to-be-molded object W, vacuum forming device D1 suction pump P0

Claims (1)

[Claims] 1. A mold body (1) formed by electroforming, in which a large number of microscopic non-electrodeposited parts generated at the initial stage of electroforming are grown to penetrate between the front and back surfaces. Through hole (
2) by reducing the pressure on the back side of the mold body (1), the molded object (W) made of a synthetic resin material is adsorbed onto the front side of the mold body (1) through the through hole (2). A vacuum forming method for synthetic resin molded products, characterized by: