JPS63286306A - Manufacture of mold for resin molding - Google Patents

Abstract

PURPOSE:To manufacture economically a mold possessing heat resistance and mechanical strength, by a method wherein a compressable web containing surplus liquid thermosetting resin is compressed with a first mold to which a mold release agent is given and a second mold provided with a discharge hole, and the resin reinforced with the compressed web is cured and stuck to the second mold. CONSTITUTION:A web 12 containing resin is put on a first mold 1, a second mold 4 is lowered, the web 12 is compressed in proportion as a gap between the first mold 1 and second mold 4 decreases, and void volume of the web becomes low. A containable resin quantity into the web decreases gradually, the surplus resin is discharged outside of the second mold 4 through a discharge hole 5, and also bubbles contained within the resin is discharged and removed at the same time. Then after the surplus resin discharged outside of the second mold 4 has been removed, the resin is cured through heating. Therefore, as the resin is cured under a state where the discharge hole 5 has been filled completely with the resin, a resin cured matter 10 reinforced with the web 12 is stuck strongly to the surface of the second mold 4 and joined integrally to the second mold 4.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to molds for resin molding, particularly injection molding of thermoplastic resins (I
The present invention relates to a method for manufacturing a mold for injection molding.

(Prior Art) It is known that molds used for resin injection molding and the like are manufactured from metal or FRP.

(Problems to be Solved by the Invention) Injection molds (hereinafter simply referred to as "molding molds") for thermoplastic resins (including thermoplastic resins reinforced with I! fibers) have high heat resistance and mechanical strength. It must be constructed from a material with a large size, and metal molds are usually used.

Although it is practical to manufacture metal molds by casting,
In casting, it is difficult to directly manufacture molds with precise dimensions and shapes, and surface processing (finishing) such as grinding and polishing is required, and manufacturing molds requires a lot of effort and expense. do.

When manufacturing thermoplastic resin products (hereinafter simply referred to as "resin products") in large quantities, there is no problem in terms of cost even if the above-mentioned effort and expense are spent, but if you are producing a prototype product, a few hundred products, or a single product,
When manufacturing approximately ,000 products, the labor and cost required for mold manufacturing become a serious problem.

Generally, FRP molds are sometimes used as molds for resin molding, but such molds lack heat resistance and strength and cannot be used for injection molding of thermoplastic resins.

It is an object of the present invention to solve the above-mentioned difficulties of the prior art and to provide a method for economically manufacturing molds having sufficient heat resistance and mechanical strength.

[Structure 1 of the Invention (Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and is made by applying a release agent to a compressible web that also contains an excess of liquid thermosetting resin. The resin is compressed by the attached first mold and a second mold provided with a discharge hole for the liquid resin, the excess resin contained in the web is discharged from the discharge hole, and the resin is reinforced by the compressed web. The present invention relates to a method for manufacturing a resin molding mold, characterized by curing the resin and adhering it to a second mold.

Next, the present invention will be explained in more detail.

1 is a first mold having almost the same shape as one side of the "resin product", and is finished to a precise shape and size in consideration of the shrinkage of the resin during injection molding.

There is no particular limitation on the material constituting the first mold l, but a wooden mold with low mechanical strength and heat resistance is sufficient, and finishing and manufacturing are easy.

It is important to apply a mold release agent 2 to the surface of the first mold 1. The type of mold release agent is not particularly limited, but silicone resin such as KS707 (manufactured by Shin-Etsu Silicone Co., Ltd.) can be suitably used. The dosage is usually 50-60g per 1m.
That's about it.

It is also possible to apply a "gel coat" after applying the S mold release agent, thereby making the surface of the mold obtained by the method of the present invention even smoother. Known means can be used for the gel coat, and for example, the gel coat 3 can be formed by applying an epoxy resin containing metal powder.

For the compressible web 12 and binding, a cotton-like material (wool-like material) composed of inorganic fibers and thin metal wires can be suitably used.
It is preferable to use a thin metal wire such as SUS or A11. The inorganic fiber has a thickness of 5 to 15 IL, preferably 8 to 12 g. The thin metal wire has a thickness of 5 to 15 IL, preferably 83 to 12 ends, and a long length. A material having a diameter of 30 to 5011 is suitable.5, impregnation with a liquid thermosetting resin can be easily and uniformly carried out, and compression can be easily carried out with a small force. , and the web has a porosity of 95 to 95.5%, preferably 98 to 95.5%.
It is appropriate to use 99%. The porosity here means the proportion of voids in the web, and is defined by the following formula.

[(apparent volume of web - actual volume of fibers and thin wires constituting the web)/apparent volume of web] x 100 In the present invention, a web containing an excess liquid thermosetting resin is used.

Excess resin refers to the amount of resin that can be contained in the web after compression (
The amount of resin that exceeds the difference between the apparent volume of the web and the actual volume of the fibers and thin wires that make up the web, that is, the amount of resin that has a volume equal to the volume of the voids in the web (hereinafter referred to as the theoretical resin amount), 130-150% of the amount, preferably 11
It is appropriate that the web contains about 0 to 120% of resin.

Further, it is appropriate that the liquid resin be uniformly applied so that the entire surface of the fine wires or fibers constituting the web is covered with the resin, and preferably that all the voids in the web before compression are filled with the resin.

Epoxy resins and polyester resins can be used as the liquid thermosetting resin, but epoxy resins are particularly preferred, as they can provide molds with excellent mechanical strength and heat resistance.

A curing agent, a curing accelerator, etc. can be added to the liquid resin as necessary. The types and proportions of these compounds are not particularly limited, and known ones can be selected and used as appropriate, taking into consideration the desired heat resistance and strength.

Note that there is no particular limitation on the method of applying and containing the liquid resin to the web, and the web may be soaked in an impregnating tank filled with liquid resin in advance, or it may be soaked on top of the first mold. The web may be placed and resin poured.

The second mold 4 is provided with a discharge hole 5 for discharging excess liquid resin. The number and size of the discharge holes are determined depending on the size and shape of the mold, but it is appropriate to uniformly provide about 15 to 20 discharge holes of about 5 to 811111φ per ml.

The surface shape of the second mold 4 is determined in a male-female relationship with the first mold 1 so that the cured resin material 10 (reinforced with a web) obtained in the compression and curing process described later has a substantially uniform thickness. is desirable, but there is no need to accurately define its shape or perform precise surface processing (rather, the adhesive strength with the resin will be greater if the surface is slightly rougher), and it is easy to manufacture.

A compressible web containing an excess liquid thermosetting resin is pressed and compressed between the first mold 1 and the second mold 4. As shown in FIG. 1, a resin-containing web 12 is placed on the first mold 1, and the second mold 4 is lowered so that the gap between the first mold 1 and the second mold 4 is small. As the process progresses, the web is compressed, the porosity of the web becomes smaller, the amount of resin contained in the web gradually decreases, and the excess resin is discharged from the discharge hole 5 to the outside of the second mold 4. Air bubbles that should be contained in the resin are also discharged and removed at the same time. At this time, in order to prevent the resin from flowing out between the first mold and the second mold, a mold release agent (not shown) is applied to the inner surface of the first mold 1 so as to be in close contact with the circumferential surface 6 of the first mold 1. It is appropriate to provide a fence 7 with a given height.

Furthermore, the first mold 1 and the fence 7 are slightly larger than the second mold 4, and there is a gap of 5 to 8 cm between the fence 7 and the second mold 4.
(2) Appropriate voids 8 can also be formed. Excess resin is also discharged from this gap 8, and the gap 8 is filled with resin. As will be described later, when the resin is cured, the resin also covers the circumferential surface 9 of the second mold 4 and hardens, so that the resin can be bonded to the second mold 4 even more firmly.

Next, if necessary, after removing the excess resin discharged to the outside of the second mold 4, the resin is cured by heating, if necessary.

The web 12 whose voids are filled with resin is brought into close contact with the surfaces of the first mold 1 and the second mold 4 in the above-mentioned compression process, and is also brought into close contact with the discharge hole 5 provided in the second mold 4. Since the resin hardens with the discharge hole 5 completely filled, the cured resin material IO reinforced with the web 12 is firmly adhered to the surface of the second mold 4 and is integrated with the second mold 4. combined with
By removing the first mold 1 and the fence 7, a resin molding mold 11 of the present invention as shown in FIG. 3 can be obtained.

The molding die 11 obtained in this way can be used alone, for example, as a press molding die, but by adjusting the plate thickness, a mold 11' (not shown) having a male and female relationship with the die 11 can be used. The molds 11° and 11' are used in pairs. (
The manufacturing method for mold 11' is completely the same as above, so a description thereof will be omitted. ) (Function of the invention) The compressible web is a second mold having resin discharge holes with the voids filled with liquid thermosetting resin, and the compressible web is formed on the surface of the first mold to which a mold release agent has been applied. During this time, the excess resin is discharged from the discharge hole along with the air bubbles present in the resin, and the resin is uniformly reinforced with the web and then returned to the first stage.
and the second mold. The resin and web enter the discharge hole and are firmly and integrally connected to the second mold.

The pressure required to compress the web is small, the first mold is a wooden mold with low mechanical strength, and can be used satisfactorily, and manufacturing and finishing are easy. Since a mold release agent is applied to the surface of the first mold, it is easy to release the mold from the cured resin, and a resin molding mold having a smooth surface can be obtained.

(Example) Bulk density 36 kg/m made of SUS thin wire with a diameter of 12 JL
aluminum powder 6 on a compressible web with a thickness of 6011"
15 kg of liquid epoxy resin containing 0 wt% was contained.

This web was placed on a first wooden mold having a predetermined surface profile.

8 made by ZAS, which has a surface that is approximately male and female with the first type.
■Place the second mold with six 1φ discharge holes on the web,
It was compressed to a thickness of 51 mm, and excess resin was discharged from the discharge hole.

After removing excess resin, the resin was left to stand at 60° C. for 2 hours to cure the resin, and the resin reinforced with the web was adhered to a second mold. The first mold and the fence were removed to obtain a mold for molding the present invention.

This mold is made by injection molding of olefinic thermoplastic resin.
It was able to withstand use over oooo times.

(Effects of the Invention) A mold for resin molding can be manufactured by a simple method, and a mold with high heat resistance and durability due to improved mechanical strength and thermal conductivity can be produced.

[Brief explanation of the drawing]

Figure 1.2 is a sectional view for explaining the present invention in detail;
The figure is a sectional view of a resin molding mold obtained by the method of the present invention. In the figure, 1 is the first mold, 2 is the mold release agent, 3 is the gel coat layer, 4 is the second mold, 5 is the discharge hole, 6 is the circumferential surface of the first mold, 7
1 is a fence, 8 is a gap, 9 is a peripheral surface of the second mold, 10 is a cured resin material reinforced with a web, 11 is a mold for resin molding, 1
2 indicates the web.

Claims (3)

[Claims] (1) A compressible web containing excess liquid thermosetting resin is compressed with a first mold provided with a mold release agent and a second mold provided with discharge holes for the liquid resin, and the web is compressed. A method for producing a mold for resin molding, which comprises discharging excess resin contained therein from a discharge hole, curing the resin reinforced by a compressed web, and adhering it to a second mold. (2) The method for manufacturing a mold for resin molding according to claim 1, wherein the compressible web is composed of a thin metal wire. (3) The method for manufacturing a resin molding mold according to claim 1 or 2, wherein the thermosetting resin is an epoxy resin.