JPS63267519A - Manufacture of resin mold - Google Patents

Abstract

PURPOSE:To manufacture a resin mold of high quality, by performing filling of a thermosetting resin composition for casting through vacuum sucking force. CONSTITUTION:A casting model and its core are arranged so that a desired gap is provided between them and that the greater part of a forming part of a cavity becomes almost perpendicular. A casting sprue part for a liquid thermosetting resin composition is provided on the lower part of the same and a vacuum suction part is provided on the upper part of the sprue. An upper vacuum suction part is filled with the liquid thermosetting resin composition by vacuum suction force through a lower casting sprue part. Then the circumference of the lower casting sprue is clogged, vacuum suction is suspended and precuring is performed. Resin molds constituting a pair are cast as the casting model by making use of a precure resin mold provided with a product master. In this instance, casting is performed so that casting temperature falls within a range of the normal temperature - 100 deg.C and viscosity of the liquid thermosetting resin composition falls within a range of 1.0X10<2>-1.0X10<3> poise.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is suitable for molding plastics, filled plastics, etc. by compression molding, transfer molding, injection molding, vacuum forming, and other methods. This method is for manufacturing resin molds, sand molds for casting, etc., in which a thermosetting resin composition containing at least metal powder is fixed on the surface of the metal core used, and is an economically excellent method for manufacturing resin molds.

[Conventional technology and its problems]

Conventionally, the method for producing a resin mold in which a thermosetting resin composition containing at least metal powder is fixed on the surface of a metal core involves preparing a liquid thermosetting resin composition for casting that has been sufficiently vacuum degassed. However, a method is used in which this is pressurized and press-fitted using compressed air or the like between a casting model containing a product master and a metal core.

This method has problems such as insufficient degassing of the liquid thermosetting resin composition for casting or insufficient filling due to the shape of the cavity. Methods have been taken to solve this problem, such as applying a liquid thermosetting resin composition for casting onto the surface of the casting model containing the product master or the metal core using a brush. It was insufficient.

[Means for solving problems]

As a result of intensive studies to solve this problem, the present invention has developed a liquid thermosetting resin composition containing metal powder that can be easily and reliably filled with a thermosetting resin composition for casting by using vacuum suction force. The present invention was completed by discovering that it is possible to fill a composition and create a high-quality resin mold.

That is, in the present invention, a casting model having a releasable surface formed by temporarily fixing a product master and a metal core serving as the core of the mold are fixed to each other with a desired gap, and a metal is inserted into this gap. After filling the liquid thermosetting resin composition containing powder,
In a method for manufacturing a resin mold, the thermosetting resin composition is cured, and then the casting model is removed to form a desired resinous mold surface on the surface of the metal core. and the metal core with a desired gap and arranged so that most of the cavity forming part is substantially vertical,
A casting sprue for casting the liquid thermosetting resin composition is provided in the lower part, and a vacuum suction part is provided in the upper part, and the liquid thermosetting resin composition is transferred from the lower casting sprue to the upper vacuum suction. This is a method for manufacturing a resin mold, which is characterized in that after the mold is filled by vacuum suction, the area around the lower casting sprue is closed, the vacuum suction is stopped, and the resin mold is precured, and in a preferred embodiment,
As the casting model, a pre-cured resin mold with a product master is used to cast the resin molds constituting the pair, and the casting is performed at room temperature to 100°C, and the liquid thermosetting is performed. The viscosity of the resin composition is 1.0X102 to 1. OX10
It is characterized by being carried out within the range of 3 voices.

The configuration of the present invention will be explained below.

The production of resin molds is based on a model of a product whose surface has mold releasability (
A product master (hereinafter referred to as a product master) is set in a casting mold (hereinafter referred to as a casting model), a liquid curable resin composition is poured into this, the resin is precured or hardened,
Remove from the casting mold, remove the product master, and if necessary, post-cure (completely cure) to obtain a resin mold with the shape, surface, etc. of the product master transferred, and add desired auxiliary jigs, etc. to this resin mold. It is made by setting.

The method of the present invention is characterized in that the metal core is used and the casting is performed by vacuum suction casting,
Since vacuum suction power is used, it is possible to substantially eliminate voids that tend to occur during casting.

First, the materials and equipment used in the resin mold manufacturing method of the present invention are as follows.

(a) Product master: The target molded product itself or a mold of the same type as the target molded product, and the material can be dried wood, synthetic wood, plaster, ABS resin, as long as it can withstand temperatures of about 100℃. , resins such as silicone resins, acrylic resins, and epoxy resins, iron, aluminum, copper, and other materials, but materials with good workability such as wood, plaster, and resins are preferred.

Metal core: The metal surface is processed into a shape such that the thickness of the casting resin forming the surface layer is in the range of 1 to 50 mm, preferably 2 to 10 mm, and a fixing part for casting is suitably formed. , a fixing part to the mold frame, etc. are formed. Although various metals can be used, aluminum alloy materials are preferred from the viewpoint of the relationship between the coefficient of linear expansion of the casting resin and the metal core, as well as ease of casting and machining. Surface treatments are also used to improve adhesion.

(C) Metal inserts: Metal inserts are usually used for holes, protrusions, other parts with narrow areas, parts of sprues in injection molding molds, etc. because the strength is insufficient with resin alone.

(d), Model for casting: Sometimes the product master itself is used, but usually,
It consists of a part of the mold cavity in which the product master is attached and its surroundings, and the surface is coated with a mold release agent depending on the type of liquid thermosetting resin composition used for casting. The surrounding material may be the same as the product master, but it is convenient to use room-temperature curing gypsum, silicone resin, etc.; Preferably, the product master is temporarily fixed with resin or the like.

2(e), Filler, mold release agent: When using a wooden mold or the like, and when an uneven pattern on the surface is unnecessary, use a filler, level the surface, and release the molding resin. A mold release agent is used for mold release.

(f) Liquid thermosetting resin composition for casting: lXl at a temperature of 100°C or less containing metal powder as an essential component
0'~1x103 voids, preferably 3X10''~6X
It is a solvent-free addition polymerization type liquid thermosetting resin composition with a void range of 10", and is easy to perform vacuum suction casting, and in order to avoid classification of metal powder during vacuum suction casting. preferable.

As a resin component, a thermosetting resin having fluidity at a temperature of 100°C or less, such as an epoxy resin, a cyanate ester resin, an isocyanate resin, a bismaleimide resin, an addition polymerization type polyimide resin, and a composition of two or more of these resins. are exemplified, among which cyanate ester resin (
Cyanato resin, cyanate ester-epoxy resin, cyanate ester-maleimide resin, cyanate ester-maleimide-epoxy resin, etc.) are most preferred. In addition, metal powders include aluminum, copper, nickel, iron, stainless steel, etc., and mixtures thereof.
The amount of metal powder blended is usually selected from the range of 30 to 70% by volume.

These include low molecular weight thermosetting resin monomers to adjust the viscosity of the resin as appropriate, rubbery polymers and non-quality resins as flexibility imparting agents, thickeners, antifoaming agents, and surfactants. In addition, inorganic powders such as silica, boron nitride, wollastonite, talc, palladium oxide, copper oxide, and magnesium oxide, and fibrous materials such as alumina fiber, silica fiber, and carbon fiber may be mixed. be.

Moreover, it is preferable to use the liquid thermosetting resin composition for casting as a sufficiently deaerated composition.

Further, many resin compositions are usually prepared as a resin composition that can be precured at a temperature ranging from room temperature to 100° C. or less, and in this case, many are composed of a resin liquid and a curing agent composition. In this case, the preparation of the composition is preferably carried out under vacuum suction, or the composition is preferably degassed by vacuum suction while stirring.

((To) Coupling agent: Depending on the thermosetting resin composition used for casting, the adhesion to the metal core may be poor, so adhesion aids such as silane coupling agents and titanate coupling agents may be used as appropriate. use an agent.

etc.), auxiliary materials for vacuum suction casting: tapes and other sealing materials for sealing the surroundings for vacuum suction casting, containers for liquid thermosetting resin compositions for casting, appropriate conduits, and Filling auxiliary parts for filling the liquid thermosetting resin composition from the bottom, sealing cocks, upper vacuum suction parts, vacuum pumps, and others are used as appropriate.

(i) Dry explosion or furnace: Used for pre-curing and curing of resin molds.

(j) Auxiliary material for mold assembly: A mold frame (Gui set or mold base) made of iron, iron alloy, aluminum alloy, etc. for fixing the resin mold is usually used as an auxiliary material.

The resin mold of the present invention is manufactured using the above components. An example of how to use a split mold for injection molding with a metal core to create a model for casting is as follows: (1) A set of models for casting: A metal core is placed, and a room-temperature curing mold is placed on it. Fix the product master with plaster, silicone resin, etc., apply a mold release agent, and set metal inserts as appropriate to create a casting model.

Fix the metal core on the opposite side to this casting model at a predetermined interval using a pre-made position fixing part or a position fixing jig, so that a part of the product master is approximately vertical. . At this time, it is also a preferred embodiment to be able to apply pressure to the casting resin as appropriate during gelling or preliminary curing of the vacuum-cast resin.

(2) Set the parts for vacuum suction casting: Set the sprue member for introducing the resin for casting into the lower part and the member for vacuum suction into the upper part.Furthermore, seal the sides and other parts with tape or putty, and then cast. The resin reservoir and the lower sprue are connected with a tube or the like, and the vacuum pump and the upper suction part are connected with a tube or the like. In addition, the lower part of the casting resin introduction sprue member may be omitted, a vat or other wide-mouthed container may be used as the casting resin reservoir, and the gap at the bottom may be used as it is as the introduction sprue part. .

(3) Casting work: After preparing a predetermined amount of thermosetting resin composition for casting and introducing it into the resin reservoir for casting, the vacuum pump is operated to reduce the pressure in the casting part and remove the injection part. Open the injection cock of the sprue member and start casting.

As the casting process progresses and the resin rises up into the upper vacuum suction member, close the injection cock, etc., confirm that the resin has gone into the gap, and then stop the vacuum suction. Then, remove the injection tube, vacuum suction tube, etc.

(4) Precuring: 100°C depending on the thermosetting resin composition for casting used.
Place in a dryer etc. set at the following temperature to pre-cure.

(5) Demolding: After preliminary curing, the metal core to which the product master is fixed with room temperature curable plaster, silicone resin, etc. and the room temperature curable composition are removed, leaving the product master behind.

(6) Manufacturing the opposite side resin mold: After cleaning the surface of the product master and the surface of the pre-cured casting resin, apply a mold release agent and use this as the opposite side casting model.

The surface of the metal core is also cleaned.

Next, operations (1) to (5) are performed to produce a pre-cured resin mold on the opposite side.

(7) Ato-curing: Remove the product master from the pre-cured resin mold created above and place in a dryer or the like for ato-curing.

(8) Finishing: Part of the ejector pin and sprue is machined, and the mold surface is finished as appropriate to finish the mold.

An example of the method for producing a resin mold according to the present invention has been described above, and the method according to the present invention is characterized by vacuum-suction casting of a thermosetting resin composition for casting. Except for the use of casting models and other methods of creation, there are no particular limitations.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 ABS resin containing wood powder was cut, and the back side was matte, and the front surface was finished with a striped pattern of uneven heights of 1 to 5 mm and widths of 2 to 10 mm (100 mm) x 100 mm (
A rectangular parallelepiped (W) x 20 mm (D) was created and used as a product master.

200mm (L) X 200a+m (W) X
Prepare two 40mm (D) aluminum plates, and place a 110
mm (L) x 110mm (W) x 20mm (D
) were formed by cutting, and holes were formed in the squares of both aluminum plates.

Temporarily adhere the product master created above to the center of the aluminum plate that does not have a recess, and apply a mold release agent (manufactured by Free Coat, USA) to the surface of the product master and aluminum plate.
A 5-casting model was prepared by applying Free Coat 44) (trade name).

Next, the casting model and the aluminum plate with the depressions were fixed through a spacer with a thickness of 2M, and the two aluminum plates were placed vertically on the stand, and the horizontal stripes of the product master were aligned. I arranged them so that the smaller ones were on the bottom.

A 10mm thick acrylic resin 10
A box with dimensions of 0mm x 40n+m x 60mm ()f) with a hole drilled in the bottom and a vacuum rubber tube fixed thereon was covered, and a rubber tube with an inner diameter of 10mmφ was cut diagonally into the gap on the bottom surface. Contact the object with a cock attached to the middle of the object, and tape the contact area between the top surface and the box body, the contact area between the rubber tube and the bottom surface, and the other top, bottom, and side surfaces with polyethylene terephthalate adhesive tape (AIRTIIIICll I).
NTERNATIONAL, manufactured by lNC0, product name;
It was completely fixed and sealed with G5213 high-tack vacuum bag sealant tape to serve as an upper vacuum suction port and a lower casting sprue.

As a liquid thermosetting resin composition for casting, a room temperature curable epoxy resin composition containing aluminum powder (manufactured by Ciba Geigy, trade name: CW-216, viscosity 300 voids (at 20°C)) was used. Place the end of the rubber tube for lower casting sprue into this liquid, and vacuum from the upper part (10 mm).
Hg), after filling the upper box with resin until it overflows,
After closing the cock of the rubber tube and disconnecting the piping from the vacuum pump to stop vacuum suction, it was allowed to stand at 25° C. for 20 hours to pre-cure.

After preliminary curing, the upper box body, lower rubber tube, other vacuum seal parts, and excess resin were removed.

Next, after removing the fixture and removing the aluminum plate, the pre-cured resin and the surface of the product master were cleaned, and the same mold release agent was applied as a casting model. was cleaned and used as a metal core, and the same process as above was repeated to cast and pre-cure the resin mold on the opposite side.

Remove the product master from the resin mold obtained above and heat to 120°C.
It was cured after 14 hours.

Auxiliary tools such as guide pins, resin injection ports, and knockout pins were attached to the pair of molds obtained above, and die sets H and Z were fixed to obtain molds for injection molding.

The mold obtained above was in good condition except for casting defects such as classification of aluminum powder and voids, and the glass transition temperature was 1.
The temperature was 20°C, and it was suitable for use in general-purpose plastics such as vinyl chloride resin.

Example 2 In Example 1, a hole was made in the lower part of the metal core to serve as a casting sprue, and a cyanate ester containing aluminum powder was used as a liquid thermosetting resin composition for casting.
Maleimide resin composition (manufactured by Mitsubishi Gas Chemical, trade name,
BT C555, viscosity 300 poise (at 45℃))
using a molding temperature of 60℃, pre-curing at 50℃ for 3 hours,
A resin mold was similarly obtained by curing at 60°C for 3 hours and at 80°C for 6 hours, and post-curing at 175°C for 8 hours.

The resin mold obtained above was in good condition except for casting defects such as classification of aluminum powder and voids, and the glass transition temperature was 170°C.

Next, a plated layer having a thickness of 50 mm was formed on this resin surface by known electroless nickel plating.

This resin mold was also suitably used for molding engineering plastics such as bolliger carbonate resin.

[Operation and effects of the invention]

As is clear from the above examples, the method of manufacturing a resin mold by the casting method of the present invention does not require any special auxiliary tools for casting.
In addition, it provides a method for manufacturing resin molds by simple casting that does not create voids in the cast resin or classify metal powder, and has high industrial significance in the field of simple molds. It is.

Claims (1)

[Scope of Claims] 1. A casting model whose surface has releasability, which is formed by temporarily fixing a product master, and a metal core that is the core of the mold are fixed to each other with a desired gap, and this gap is filled with After filling a liquid thermosetting resin composition containing metal powder, the thermosetting resin composition is cured, and then the casting model is removed to form a desired resin mold surface on the metal core surface. In the method for manufacturing a resin mold, the casting model and the metal core are arranged with a desired gap and most of the cavity forming part is substantially vertical, and the liquid is placed in the lower part of the mold. A casting sprue section for thermosetting resin composition is provided with a vacuum suction section above it, and the liquid thermosetting resin composition is transferred from the lower casting sprue section to the upper vacuum suction section by vacuum suction force. A method for manufacturing a resin mold, which is characterized in that after filling with a resin mold, the area around the lower casting sprue is closed, vacuum suction is stopped, and preliminary curing is performed. 2. A method for manufacturing a resin mold according to claim 1, characterized in that a pre-cured resin mold with a product master is used as the casting model to cast a pair of resin molds. . 3. The casting temperature is in the range from room temperature to 100°C or less, and the viscosity of the liquid thermosetting resin composition is 1.0 x 10^2 to 1.
．． The method for manufacturing a resin mold according to claim 1 or 2, wherein vacuum casting is performed in the range of 0x10^3 poise.