JPS6389306A - Molding of liquid plastic - Google Patents

Abstract

PURPOSE:To permit quick mold releasing, the improvement of a molding efficiency and the stabilized molding of a molded form having complexed configuration, by a method wherein the surface of liquid plastics, heated and reacted to be cured in a mold, is cooled to a temperature lower than at least the thermal deformation temperature thereof and the liquid plastic is released from the mold after curing. CONSTITUTION:The temperature of a mold 1 is kept higher than a molding temperature by a heat medium from a high-temperature heat source 2 and, then, liquid plastic material is poured into the mold 1. The poured liquid plastics material receives heat from the mold 1 and the temperature thereof is risen to the molding temperature after a predetermined hour while the reaction of curing agent, mixed with the plastics, is promoted and the curing thereof is advanced. When a predetermined time has elapsed, the supply of the high- temperature heat source 2 is stopped and heat medium from a low-temperature heat source 3 is made to flow through the mold 1 to cool the same to a temperature lower than the thermal deformation temperature of a molded form. According to this method, the temperature of the molded form in the mold 1 is reduced to a temperature lower than the thermal deformation temperature thereof after a predetermined period of time, then, the molded form is released from the mold. A force is exerted between the molded form and the mold 1 upon demolding whereby the deformation or breakage of the molded form may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid plastic molding method for molding a plastic molded article using a liquid plastic raw material, such as reaction molding or liquid molding.

[Prior art] A molding method in which a single type of liquid plastic raw material or multiple types of liquid plastic raw materials is supplied to a mold, and the mold is raised to an appropriate degree to harden the plastic raw materials mainly uses thermosetting resin. Widely used for resin molding. Examples include compression molding, transfer molding, injection molding, reaction injection molding or casting. In these cases, the heating (molding) temperature of the mold is determined by taking into account the type of resin to be used, the molding method, the shape and size of the product, the required manufacturing efficiency, etc. Molding is performed by repeatedly closing the mold, pouring, assimilating, and opening the mold while keeping the molding temperature constant.

[Problems to be Solved by the Invention] By the way, among the resins molded by this method, there are some, such as epoxy resins, whose heat distortion temperature of the molded product is lower than the above molding temperature. (See Figure 4).

When such a resin is molded using the above method, the temperature of the molded product at the time of mold release is close to the molding temperature, which is higher than the heat distortion temperature, and the molded product is in a soft state. If the peelability is poor, it may be damaged or deformed when released from the mold.
Otherwise, the surface may become rough, and in those using ejector pins, there are problems such as marks of the ejector pins being left on the molded product or, in extreme cases, holes being formed.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a liquid plastic molding method in which a liquid plastic raw material is supplied to a mold and hardened. A heating device that heats the liquid plastic raw material above its molding temperature and a cooling device that cools the molded product below its heat distortion temperature are attached, and the temperature of the liquid plastic raw material injected into the mold is controlled by the heating device. After the reaction is cured by raising the temperature above the molding temperature, the temperature of the reaction-facilitated molded product is lowered to below the heat distortion temperature of the molded product using the cooling device to cool the molded product and release the molded product. It was designed to be molded.

[Function] In such a molding method, the liquid plastic is heated by the heating device and reacted and hardened in the mold, and at least its surface is cooled to below the heat distortion temperature in the mold by the cooling device, so that the liquid plastic is sufficiently cooled. After curing, the mold is released.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. In this figure, 1 is a mold, 2 is a high temperature heat source, and 3 is a low temperature heat source. The mold 1 is usually constructed by being divided into two or more parts, and a cavity into which liquid plastic raw material is injected is formed between them. Two channels 4 for circulating the medium
．． 5 are formed independently from each other. The inlet 4a and outlet 4b of the high-temperature flow path 4 are connected to the supply port 2a and return port 2b of the heat medium of the high-temperature heat source 2 via piping 6.7, and the inlet 5a and outlet of the other low-temperature flow path 5 5b is connected to the supply port 3a and return port 3b of the heat medium of the low-temperature heat source 3 via piping 8.9, and a flow rate control valve 10.9 is connected to each piping on the supply side. I
t is provided to adjust the flow rate of the heat medium of each heat source 2, 3. These heat sources 2 and 3 have a heat storage tank with a flow path through which a heat medium made of fluid such as oil flows, and are equipped with a pump that circulates the heat medium, so that heat at a constant temperature is always generated. The temperature Ta of the high-temperature heat source 2 is higher than the molding temperature (for example, about 150°C) TI of the target resin, for example, 170 to 180°C.
The temperature of the low-temperature heat source Tb is lower than the heat distortion temperature (e.g. 100°C) T2 of the target resin, e.g.
The temperature is set at 80° C., and by appropriately changing the flow rate of the heat medium from each heat source 2 and 3, the amount of heat given to the mold 1 is changed and the mold temperature is controlled. The high-temperature heat source 2, the piping 6°7, the flow path 4 of the mold 1, etc. constitute a heating device that heats the liquid plastic raw material to a temperature higher than its molding temperature,
In addition, the low-temperature heat source 3, the pipes 8 and 9, and the flow path 5 of the mold l
etc. constitute a cooling device that cools a molded product made of the liquid plastic raw material to a temperature below its thermal deformation temperature.

An example of molding, for example, epoxy resin using such an apparatus will be described with reference to FIG. In advance, open the flow control valve lO, close the flow control valve II, and turn on the high temperature heat source 2.
A heating medium from is passed through the mold l to maintain the temperature of the mold l at a molding temperature of 18 or higher, and just before the injection start time t0, the resin material and curing agent are uniformly mixed to form a liquid plastic raw material. and injected into the mold l heated to the above molding temperature or higher (completion time 1.). The liquid plastic raw material injected into the mold 1 receives heat from the mold 1 and rises in temperature, reaches the molding temperature T after a certain period of time, and the reaction between the resin and the curing agent is promoted and curing progresses. Then, at time t when a predetermined period of time has elapsed, the flow control valve 10. ll, the supply of heat medium from the high temperature heat source 2 is stopped, and the heat medium from the low temperature heat source 3 is passed through the mold l to cool the mold l, and the temperature is set to the heat distortion temperature T2 of the molded product. The temperature should be lower than T. As a result, the temperature of the molded product obtained by reaction-hardening of the liquid plastic raw material in the mold 1 will drop below its heat distortion temperature after a certain period of time, so at time t, when this certain period of time has elapsed, the mold 1 is opened. The molded product is released from the mold, and the mold 1 is heated again for the next cycle. In such a process, when the molded product is released from the mold, the temperature of at least the surface of the molded product has decreased to below the heat distortion temperature T, and in this state, even if a force is applied between the molded product and the mold l, the molded product will not work. This prevents deformation or damage.

In the above embodiment, the heating device circulates the heat medium from the high-temperature heat source 2 through the pipes 6 and 7 into the flow path 4 of the mold l,
Although the mold 1 is heated, the mold 1 may be heated by attaching an electric heating device such as an electric heater to the mold 1 instead. Can you get the effect?

FIG. 2 shows a second embodiment of the present invention, in which only one channel 12 is formed in the mold 1;
The inlet 12a of the flow path 12 is connected to the supply ports 2a and 3a of the high temperature heat source 2 of the heating device and the low temperature heat source 3 of the cooling device via a supply pipe 13, and the outlet 12b of the flow path 12 is connected to each heat source 2 via a return pipe 14. .3 is connected to the return ports 2 b and 3 b,
Flow control valves 10a, 11a, 10b, 1 are provided at supply ports 2a, 3a and return ports 2b, 3b of each heat source 2, 3, respectively.
lb is provided. In this second embodiment,
The heat medium from the high temperature or low temperature heat source 2.3 flows through the flow control valves 10a, 10b.

By opening and closing 11ajlb, one of them is supplied to the flow path 12 of the mold l via the supply pipe 13, and the mold l is heated to a required temperature. In this example, flow path 1 of mold l
2 is shared by the heat medium from each of the heat sources 2 and 3, and has the advantage of a simple structure and low manufacturing cost, and has the same functions and effects as the previous example. In addition, in the above embodiment, the case where one high-temperature side heat source and one low-temperature side heat source are provided is shown, but one or both of the heat sources may be set in degrees. For example, two high-temperature heat sources are provided, and each of them It may be configured such that it is connected to each of the flow paths 12 of the mold 1 divided into two parts.

[Effects of the Invention] As detailed above, the present invention provides a liquid plastic molding method in which a liquid plastic raw material is supplied to a mold and cured, in which the liquid plastic raw material is heated to the mold above its molding temperature. A heating device for cooling the molded product to a temperature below its heat distortion temperature is attached, and the temperature of the liquid plastic raw material injected into the mold is raised to a temperature above the molding temperature by the heating device to perform reaction hardening. After that, the temperature of the reaction-hardened molded product was lowered to below the heat deformation temperature of the molded product using the cooling device to cool the molded product and release the molded product, so that the molding temperature of the resin could be lowered. Even if the heat distortion temperature of the molded product is lower than that of the molded product, the molded product will not be deformed or damaged when it is released from the mold, and the surface properties will not be deteriorated. In addition, even if ejector pins are used, they do not leave any traces, so the mold can be released quickly, improving molding efficiency, and even products with complex shapes can be stably molded. It is effective.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a first embodiment of the present invention, Fig. 2 is a diagram showing a second embodiment of the invention, Fig. 3 is a diagram showing an example of mold temperature control, and Fig. 4 is a diagram showing a resin mold. 3 is a graph showing an example of molding temperature and molded product thermal deformation temperature. ■・・・Mold, 2...High temperature heat source, 3...
...Low temperature heat source, 11 ...High temperature flow path, 5...
...low temperature flow path, 12.... flow path.

Claims (5)

[Claims] (1) In a liquid plastic molding method in which a liquid plastic raw material is supplied to a mold and hardened, the mold is provided with a heating device that heats the liquid plastic raw material to a temperature higher than its molding temperature, and a molded product that is heated to its heat distortion temperature. The temperature of the liquid plastic raw material injected into the mold is raised to a temperature higher than the molding temperature by the heating device to cause reaction hardening, and then the reaction hardened molded product is A method for molding a liquid plastic, comprising cooling the molded product by lowering the temperature to a temperature below the thermal deformation temperature of the molded product using the cooling device, and releasing the molded product. (2) The heating device and the cooling device are configured to allow heat medium from a high-temperature heat source and a low-temperature heat source to flow through channels formed in the mold. Method of molding the liquid plastic described. (3) The above-mentioned flow path is characterized in that a flow path through which a heat medium from a high-temperature heat source flows and a flow path through which a heat medium from a low-temperature heat source flows are formed independently. Second
Method for molding liquid plastic as described in Section 1. (4) The liquid plastic molding method according to claim 2, wherein the flow path is formed as a flow path through which heat medium from each heat source is shared. (5) The heating device is comprised of an electric heating device such as an electric heater attached to the mold, and the cooling device is configured to cause a heat medium from a low-temperature heat source to flow through a flow path formed in the mold. A method for molding liquid plastic according to claim 1, characterized in that: