JP2021037752A - Method for producing molded body - Google Patents

Abstract

To provide a method for producing a molded body capable of suppressing the occurrence of void in a molded body.SOLUTION: There is provided a method for producing a molded body which comprises: a gate space filling step (first step) of filling a molding raw material in a gate space 12; and a molding space filling step (second step) of filling the molding raw material in a molding space 11. In the molding space filling step, before the molding raw material flows out into the molding space 11 from a first communication passage 13, the supply amount per unit time of the molding raw material is decreased.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a molded product.

Conventionally, a molding die having a molding space, a gate space, a vent space, a first continuous passage communicating with the molding space and the gate space, and a second continuous passage communicating with the molding space and the vent space has been used. A method for producing a molded product is known (see, for example, Patent Document 1). After the molding raw material is filled in the gate space, it is supplied from the gate space to the molding space via the first continuous passage.

International Publication No. 2009/044730

However, when the molding raw material flows into the molding space from the first passage, air is easily taken into the molding raw material, so that there is a problem that voids are generated on the surface of the molded product on the first passage side.

An object of the present invention is to provide a method for producing a molded product capable of suppressing the formation of voids in the molded product.

In the method for manufacturing a molded product according to the present invention, a molding space, a gate space, a vent space, a first continuous passage communicating with the molding space and the gate space, and a second continuous passage communicating with the molding space and the vent space. A molding die having the inside is used. The method for manufacturing a molded product includes a first step of filling the gate space with the raw material for molding and a second step of filling the molding space with the raw material for molding. Before the molding raw material flows into the molding space from the first communication passage, the supply amount of the molding raw material per unit time is reduced.

According to the present invention, it is possible to provide a method for producing a molded product capable of suppressing the formation of voids in the molded product.

It is a side view of the molding die 10 which concerns on embodiment. FIG. 1 is a cross-sectional view taken along the line AA of FIG. It is a schematic diagram for demonstrating the manufacturing method of the molded article which concerns on embodiment. It is a schematic diagram for demonstrating the manufacturing method of the molded article which concerns on embodiment. It is a schematic diagram for demonstrating the manufacturing method of the molded article which concerns on embodiment. It is a schematic diagram for demonstrating the manufacturing method of the molded article which concerns on embodiment.

(Structure of molding mold 10)
The configuration of the molding die 10 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a side view of the molding die 10. FIG. 2 is a cross-sectional view taken along the line AA of FIG.

The mold 10 is made of, for example, a metal (aluminum, aluminum alloy, SUS steel, nickel alloy, etc.). The molding die 10 is used for curing (gelling) a liquid or sol-shaped molding raw material injected into the molding body to form a molded product. The molding die 10 is suitable for forming a molded product by, for example, a mold casting method, which is a kind of casting molding method.

The raw material for molding is a fluid self-curing slurry. The molding raw material includes a predetermined powder, a reactant, a gelling agent, a solvent, a dispersion aid, and other additives (for example, a pore-forming agent).

The predetermined powder is the base material of the molded product. Predetermined powders include, for example, ceramic powders, metal powders, and mixtures thereof. Examples of the ceramic powder include, but are not limited to, alumina powder, zirconia powder, aluminum nitride powder, and silicon carbide powder. Examples of the metal powder include, but are not limited to, platinum powder, tungsten powder, molybdenum powder and the like. The content of the predetermined powder is not particularly limited, but can be, for example, 20% by volume or more and 60% by volume or less.

The reactant contains a reactive functional group that reacts with the gelling agent to cause a curing reaction (gelling reaction). Examples of the reactant include polyhydric alcohols (diols such as ethylene glycol, triols such as glycerin), polybasic acids (dicarboxylic acids and the like), polyethylene glycol and the like. The content of the reactant is not particularly limited, but can be, for example, 0.05% by volume or more and 5% by volume or less.

The gelling agent is an additive that reacts with a reactive functional group contained in the reactant to cause a curing reaction. Examples of the gelling agent include MDI (4,4'-diphenylmethane diisocyanate), HDI (hexamethylene diisocyanate), TDI (trilens isocyanate), IPDI (isophorone diisocyanate) and the like. The gelling agent preferably has at least one of an isocyanate group (-N = C = O) and an isocyanate group (-N = C = S). Thereby, the reaction between the gelling agent and the reactant can be promoted. The content of the gelling agent is not particularly limited, but can be, for example, 3% by volume or more and 20% by volume or less.

The solvent is an additive for dispersing a predetermined powder. Examples of the solvent include esters having two or more ester groups such as polybasic acid esters (dimethyl glutarate and the like), polyhydric alcohol acid esters (triacetin and the like), and aliphatic polyvalent esters. The content of the solvent is not particularly limited, but can be, for example, 30% by volume or more and 70% by volume or less.

The dispersion aid is an additive for reducing the viscosity of the molding raw material. The dispersion aid is any additive added as desired. Examples of the dispersion aid include sorbitan fatty acid esters, polycarboxylic acid-based copolymers, phosphoric acid ester salt compounds of polymers, alkylammonium salt compounds of polymers containing acid groups, and sodium alkylbenzene sulfonates. The content of the dispersion aid is not particularly limited, but can be, for example, 0.5% by volume or more and 10% by volume or less.

The catalyst is an additive for further promoting the reaction between the gelling agent and the reactant. The catalyst is any additive added as desired. Examples of the catalyst include triethylenediamine, hexanediamine, 6-dimethylamino-1-hexanol and the like. The content of the catalyst is not particularly limited, but can be, for example, 0.01% by volume or more and 3% by volume or less.

Since such a molding raw material starts to cure when the above compositions are mixed, the viscosity rapidly increases unlike, for example, a thermoplastic resin used for injection molding. Specifically, the raw material for molding has a viscosity of E1 (shear velocity 1 sec ^-1 ) 2 minutes after mixing of each composition, and an viscosity of E2 (shear velocity 1 sec -1) 12 minutes after mixing of each composition. When 1 sec ^-1 ), the relationship of 0.01 Pa · sec ≦ E1 ≦ 3.0 Pa · sec, 2.0 Pa · sec ≦ E2 ≦ 2000 Pa · sec, and E2 / E1 ≧ 5.0 is satisfied.

As shown in FIG. 1, the molding die 10 is used in a state of being vertically placed along the vertical direction. Although the molding die 10 is drawn as if it is composed of one member in FIGS. 1 and 2, the molding die 10 may be formed by connecting a plurality of members.

The molding die 10 has a molding space 11, a gate space 12, a first passage 13, a vent space 14, a second passage 15, and a runner 16 inside.

The molding space 11 is a space for forming a molded body. The molding space 11 is a so-called cavity. The molding space 11 is filled with a raw material for molding.

The molding space 11 is arranged above the gate space 12. A first continuous passage 13 is arranged between the molding space 11 and the gate space 12. The molding space 11 is arranged below the vent space 14. A second passage 14 is arranged between the molding space 11 and the vent space 14.

The molding space 11 may correspond to the outer shape of the molded body, and its shape is not particularly limited. As shown in FIG. 1, in the present embodiment, the molding space 11 is formed in a substantially rectangular parallelepiped shape. Further, as shown in FIG. 2, in the present embodiment, the lower end portion of the molding space 11 is formed in a taper shape toward the first continuous passage 13, and the upper end portion of the molding space 11 is formed in the second continuous passage 15. It is formed in a tapered shape toward the end.

When a structure such as a flow path is provided in the molded body, an object (for example, a rod or the like) corresponding to the shape of the structure may be arranged in advance in the molding space 11. Further, when some object (for example, a conductor, an electronic device, etc.) is embedded in the molded body, the object may be arranged in advance in the molding space 11.

The gate space 12 is arranged below the molding space 11. The gate space 12 is a space for storing the molding raw material supplied to the molding space 11. The volume of the gate space 12 may be smaller than the volume of the molding space 11. The gate space 12 may be configured so that the raw material for molding can be smoothly supplied to the molding space 11, and its shape is not particularly limited. As shown in FIG. 1, in the present embodiment, the gate space 12 is arranged along the lower end portion of the molding space 11. Further, as shown in FIG. 2, in the present embodiment, the upper end portion of the gate space 12 is formed in a tapered shape toward the first continuous passage 13.

The first communication passage 13 communicates with the molding space 11 and the gate space 12. The first continuous passage 13 is a flow path for guiding the molding raw material filled in the gate space 12 to the molding space 11. As shown in FIG. 2, the first continuous passage 13 is formed narrower than the molding space 11 and the gate space 12. That is, the first continuous passage 13 narrows the space between the molding space 11 and the gate space 12. As a result, the gate space 12 can be smoothly filled with the raw material for molding, and after the molded product is cured, the product portion cured in the molding space 11 and the non-product portion cured in the gate space 12 can be easily separated. Can be excised.

The vent space 14 is arranged above the molding space 11. The vent space 14 is a space for storing the overfilled raw material for molding supplied to the molding space 11. The volume of the vent space 14 may be smaller than the volume of the molding space 11. As shown in FIG. 1, the vent space 14 is connected to a plurality of discharge ports 14a formed on the upper surface of the molding die 10. The raw material for molding the excess stored portion in the vent space 14 is discharged to the outside from the discharge port 14a. The shape of the vent space 14 is not particularly limited. As shown in FIG. 1, in the present embodiment, the vent space 14 is arranged along the upper end portion of the molding space 11. Further, as shown in FIG. 2, in the present embodiment, the lower end portion of the vent space 14 is formed in a tapered shape toward the second continuous passage 15.

The second communication passage 15 communicates with the molding space 11 and the vent space 14. The second continuous passage 15 is a flow path for guiding the molding raw material filled in the molding space 11 to the vent space 14. As shown in FIG. 2, the second passage 15 is formed narrower than the molding space 11 and the vent space 14. That is, the second passage 15 narrows the space between the molding space 11 and the vent space 14. As a result, the molding raw material can be reliably filled in the molding space 11, and after the molded product is cured, the product portion cured in the molding space 11 and the non-product portion cured in the vent space 14 can be easily separated. Can be excised.

The runner 16 communicates with the gate space 12 and the injection port 16a formed on the upper surface of the molding die 10. The runner 16 is a flow path for guiding the molding raw material supplied from the outside of the molding die 10 to the gate space 12. The molding raw material is supplied into the runner 16 from the injection port 16a.

(Manufacturing method of molded product)
Next, a method for manufacturing the molded product will be described.

1. 1. Gate space filling process (first process)
First, the gate space 12 is filled with a raw material for molding. Specifically, the gate space 12 is filled with the molding raw material by supplying the molding raw material from the outside of the molding mold 10 to the gate space 12 via the runner 16. At this time, since the space between the molding space 11 and the gate space 12 is narrowed by the first continuous passage 13, the molding raw material is filled from the gate space 12 to the molding space 11 before the gate space 12 is filled with the molding raw material. Can be suppressed from flowing in.

The supply amount R1 per unit time of the molding raw material supplied to the gate space 12 in this gate space filling step (hereinafter, abbreviated as “supply amount R1”) is the filling time, the viscosity of the molding raw material, and the gate space. It can be appropriately set in consideration of the volume of 12 and the shape of the molding space 11. In the gate space filling step, it is preferable to keep the supply amount R1 at a predetermined value.

In the present specification, the supply amount per unit time means the volume of the molding raw material supplied in one second, and the unit is "mL / sec". The supply amount per unit time can be controlled by adjusting the injection pressure of the molding raw material injected from the injection port 16a. The value of the supply amount R1 is not particularly limited, but can be, for example, 0.1 to 10 mL / sec.

2. Molding space filling process (second process)
Following the gate space filling step, the molding space 11 is filled with a molding raw material. Specifically, after the molding raw material flows into the molding space 11 from the first connecting passage 13, the supply of the molding raw material to the gate space 12 is continued until the molding raw material reaches the second connecting passage 15.

Here, in the present embodiment, the supply amount of the molding raw material per unit time is reduced before the molding raw material flows into the molding space 11 from the first continuous passage 13. Specifically, the unit time smaller than the supply amount R1 from the supply amount R1 in the gate space filling step before the molding raw material exceeds the line L13 having the narrowest width between the molding space 11 and the gate space 12. The per-supply amount R2 (hereinafter, abbreviated as "supply amount R2") is changed. The change from the supply amount R1 to the supply amount R2 can be performed by reducing the injection pressure of the molding raw material injected from the injection port 16a. The change from the supply amount R1 to the supply amount R2 may be performed before the molding raw material starts to flow into the molding space 11, for example, while the liquid level of the molding raw material is located in the first continuous passage 13. It may be carried out before the liquid level of the molding raw material reaches the first continuous passage 13.

In this way, by reducing the supply amount R1 to the supply amount R2 before the molding raw material flows into the molding space 11, the molding raw material can be slowly flowed from the first passage 13 into the molding space 11. .. Therefore, as shown in FIG. 3A, the molding raw material can be gradually extruded along the wall surface of the molding space 11, so that air can be suppressed from being mixed into the molding raw material. As a result, it is possible to suppress the formation of voids in the molded product. As shown in FIG. 3B, the supply amount R2 may be set so that air does not get mixed into the molding raw material vigorously flowing in from the first communication passage 13. The value of the supply amount R2 may be relatively smaller than the value of the supply amount R1 and is not particularly limited, but may be, for example, 0.01 to 8 mL / sec.

Further, after the molding raw material has flowed into the molding space 11, it is preferable to increase the supply amount of the molding raw material per unit time. Specifically, after the molding raw material has flowed into the molding space 11 from the first continuous passage 13, the supply amount R3 per unit time, which is larger than the supply amount R2 at the start of the inflow of the molding raw material (hereinafter, “supply amount”). It is preferable to change to (abbreviated as R3). The change from the supply amount R2 to the supply amount R3 can be performed by increasing the injection pressure of the molding raw material injected from the injection port 16a. The change from the supply amount R2 to the supply amount R3 may be performed after the molding raw material has flowed into the molding space 11.

In this way, by increasing the supply amount R2 to the supply amount R3 after the molding raw material has flowed into the molding space 11, the filling time of the molding raw material in the molding space 11 can be shortened. It is preferable to keep the supply amount R3 at a predetermined value during filling of the molding raw material. The value of the supply amount R3 is preferably relatively larger than the supply amount R2 and is not particularly limited, but can be, for example, 0.1 to 10 mL / sec.

Further, it is preferable to reduce the supply amount of the molding raw material per unit time before the molding raw material flows out from the molding space 11 into the second continuous passage 15. Specifically, before the raw material for molding exceeds the line L15 having the narrowest width between the molding space 11 and the vent space 14, the supply amount R3 is reduced from the supply amount R3 to the supply amount R4 per unit time, which is smaller than the supply amount R3. (Hereinafter, it is abbreviated as "supply amount R4"). The change from the supply amount R3 to the supply amount R4 can be performed by reducing the injection pressure of the molding raw material injected from the injection port 16a. The change from the supply amount R3 to the supply amount R4 may be performed before the molding raw material starts to flow out into the second connecting passage 15.

In this way, by reducing the supply amount R3 to the supply amount R4 before the molding raw material flows out to the second continuous passage 15, the molding raw material is gently flowed out from the molding space 11 to the second continuous passage 15. Can be done. Therefore, as shown in FIG. 4A, the molding raw material can be gradually extruded along the wall surface of the molding space 11, so that air can be suppressed from being mixed into the molding raw material. As a result, it is possible to further suppress the formation of voids in the molded product. As shown in FIG. 4B, the supply amount R4 may be set so that air is not left behind between the molding raw material and the wall surface of the molding space 11. The value of the supply amount R4 is preferably relatively smaller than the value of the supply amount R3, and is not particularly limited, but can be, for example, 0.01 to 8 mL / sec.

3. 3. Outflow process (third process)
Following the molding space filling step, the molding raw material is discharged from the molding space 11 to the vent space 14. Specifically, after the molding raw material is filled in the molding space 11, the supply of the molding raw material to the gate space 12 is continued until the molding raw material flows out from the second passage 15 into the vent space 14.

The supply amount R5 per unit time of the molding raw material supplied to the gate space 12 in this outflow step (hereinafter, abbreviated as “supply amount R5”) may be the same as the above-mentioned supply amount R4. , It may be different from the supply amount R4.

4. Curing Step Next, a molded product is formed by curing (gelling) the molding raw material after leaving it for a certain period of time (for example, 0.1 to 24 hours). After that, the molding die 10 is appropriately disassembled and the molded product is taken out.

(Modified example of the embodiment)
Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, the lower end of the molding space 11 is formed in a tapered shape toward the first passage 13, and the upper end of the molding space 11 is formed in a taper shape toward the second passage 15. However, the shape of the molding space 11 is not particularly limited. For example, the molding space 11 may be formed in a rectangular shape.

Further, in the above embodiment, the upper end portion of the gate space 12 is formed in a tapered shape toward the first continuous passage 13, but the shape of the gate space 12 is not particularly limited. For example, the gate space 12 may be formed in a rectangular shape.

Further, in the above embodiment, the lower end portion of the vent space 14 is formed in a tapered shape toward the second continuous passage 15, but the shape of the vent space 14 is not particularly limited. For example, the vent space 14 may be formed in a rectangular shape.

Further, in the above embodiment, the first communication passage 13 is formed in a tapered shape toward each of the molding space 11 and the gate space 12, but the present invention is not limited to this. For example, the first passage 13 may be formed in a rectangular shape. That is, the first passage 13 may have the same width (that is, the width in the horizontal direction is the same in the vertical direction). In this case, the supply amount of the molding raw material per unit time may be reduced before the molding raw material crosses the upper end line of the first continuous passage 13.

Further, in the above embodiment, the second passage 15 is formed in a tapered shape toward each of the molding space 11 and the vent space 14, but the present invention is not limited to this. For example, the second passage 15 may be formed in a rectangular shape. That is, the second passage 15 may have the same width (that is, the width in the horizontal direction is the same in the vertical direction). In this case, the supply amount of the molding raw material per unit time may be reduced before the molding raw material crosses the line at the lower end of the second passage 15.

10 Molding mold 11 Molding space 12 Gate space 13 1st continuous passage 14 Vent space 14a Outlet 15 2nd continuous passage 16 Runner 16a Injection port

Claims (3)

A molding die having a molding space, a gate space, a vent space, a first communication passage communicating with the molding space and the gate space, and a second communication passage communicating with the molding space and the vent space inside. This is the method for manufacturing the molded product used.
The first step of filling the gate space with a raw material for molding, and
The second step of filling the molding space with the molding raw material, and
With
Before the molding raw material flows into the molding space from the first communication passage, the supply amount of the molding raw material per unit time is reduced.
A method for manufacturing a molded product. After the molding raw material flows into the molding space, the supply amount of the molding raw material per unit time is increased.
The method for producing a molded product according to claim 1. Before the molding raw material flows out of the molding space into the second passage, the supply amount of the molding raw material per unit time is reduced.
The method for producing a molded product according to claim 1 or 2.

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