KR100246929B1 - High cyclic forming method by the gas assist - Google Patents

Abstract

Provided is a high cycle molding method that eliminates or reduces appearance defects in gas assist molding without lengthening the molding cycle. In the gas assist molding method of thermoplastic resin, the molten thermoplastic resin is injected into the mold. It is a high cycle molding method that controls the mold temperature of the thermoplastic resin to be 10-100 ℃ higher than the heat deformation temperature of the thermoplastic resin.

Description

High cycle molding method by gas assist

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a molding method in a field where high quality surface appearance is required for molded parts such as exterior parts and shells, and high cycles are required in gas assist molding of thermoplastic resins. The present invention relates to a high cycle molding method in which the mold temperature is increased in order to eliminate or reduce appearance defects in the inorganic filler filling material.

Conventionally, in the gas assist molding, when the resin filled with the inorganic filler is used, the inorganic filler is molded because the resin pressure in the mold is lower than the general injection molding, the mold transferability is poor, or the shrinkage rate is large because the product thickness is thick. It floated on the surface and damaged the appearance of the molded article.

In the gas assist molding, when inert gas is injected into the molded part, a thick part called a gas channel is formed to form a hollow part as a target, and a thick part is selected in the thickness of the product with a general surface to select a thick inert gas part. Design to enter However, due to the difference in product thickness and the rapid flow of the ungwoong resin in the general surface and the gas channel part, the weld line occurred and damaged the appearance of the molded product.

In addition, in the case of extremely thick molding having a product thickness of more than 10 mm, which is one of the characteristics of gas assist molding, jetting occurs because the resin temperature drops due to extreme volume expansion when the molten resin flows through the gate in the mold to the product part. And damaged molded article appearance.

In order to solve these problems, it is well known to set the molding resin temperature and the mold temperature high. However, if the molding resin temperature and the mold temperature are increased, the molten resin takes a long time to cool and solidify and the molding cycle becomes long.

An object of the present invention is to provide a method for forming a hollow molded article capable of eliminating or reducing the defect of appearance defects in conventional gas assist molding without lengthening the molding cycle and forming a desired high quality appearance quality.

SUMMARY OF THE INVENTION An object of the present invention is to form a product shape in a gas assist molding method having a hollow molded part used as an automobile part such as a roof rail, a door handle, a grip, an office device such as a fax machine, a copier, a housing of a household electrical appliance, and the like. Mold temperature control system and mold which can control the mold temperature 0-40 ℃ lower than the thermal deformation temperature of the resin to be molded when the molten resin is injected in one cycle, and 0-100 ℃ lower than the temperature in the cooling process. It can be solved by the high cycle molding method of the hollow molded article using.

The mold temperature control system used in the high cycle molding method according to the present invention is used to stop cold water and cooling oil at elevated temperature, use hot water, heating oil or electrothermal heater alone or in combination, and hot water and heating at a temperature drop. Stop the oil or heater and turn the coolant and coolant to the same mold temperature control pipe or to each mold temperature control pipe.

At this time, the higher the temperature of the hot water and the heating oil used for the temperature increase, the lower the temperature of the cooling water and the cooling oil used for the temperature drop, and the larger the flow rate, the shorter the molding cycle. The higher the watt density, the better.

The more it is installed in the range where there is no problem in mold strength with respect to the mold temperature control pipeline, the better the efficiency and the shorter the cycle is possible.

According to the present invention, by setting the mold temperature closer to the heat deflection temperature at the time of injection of the molten resin, the molten resin can be filled without sudden cooling, jetting and weld lines can be eliminated, and the molten resin By quenching after filling, the molding cycle can be shortened.

In addition, the transfer rate of the mold can be improved, the gloss of the molded article is improved, and the molded article having a small lift of the filler can be molded for the inorganic filler filling material with a short cycle.

1 is a block diagram showing a schematic configuration example of a mold temperature control system suitable for a high cycle molding method according to the present invention.

2 is a cross-sectional view of a mold structure suitable for carrying out the high cycle molding method according to the present invention.

3 is a perspective view showing an example of a molded article molded by the high cycle molding method according to the present invention.

* Explanation of symbols for main parts of the drawings

1: temperature controller for hot water 2: chiller for cold water

3: switching and control unit 4: mold

5: Heat and cold water supply path to the mold 6: Heat and cold water return from the mold

7: fixed mold 8: movable mold

9: Cavity 10: Tanggu

11: gate 12: gas inlet

EMBODIMENT OF THE INVENTION Hereinafter, this invention is disclosed, referring an accompanying drawing which shows an Example. 1 is a block diagram showing a configuration example of a mold temperature control system suitable for a high cycle molding method of a hollow molded article according to the present invention.

This mold temperature control system owns the thermostat 1 for hot water and the chiller 2 for cold water, and is connected to the switching unit 3. The switching unit 3 has an outlet 5 for supplying cold water and hot water to the mold 4 and a return port 6 for recovery. In order to achieve a desired mold temperature, control of the switching and control unit 3 is carried out so that the respective switching valves VIN and VR in the apparatus are in an appropriate state.

2 is a cross-sectional view of a mold suitable for carrying out the high cycle molding method according to the present invention. The mold is formed with a cavity 9 at the mating surface of the stationary mold 7 and the movable mold 8, and the stationary mold 7 has a spout 10 and a gate (10) for filling molten resin in the cavity 9. 11), the movable mold 8 has a gas inlet 12 for injecting gas into the filled resin.

In this embodiment, a modified PPE resin Noryl GFN3 (trademark: made by Japan Plastic Co., Ltd., glass fiber filling amount: 30%) and an alloy of polycarbonate resin and polybutylene terephthalate resin XENOY 1760 (trademark: Japan Paper Plastics, and a glass fiber filling amount of 10%).

In order to confirm the effect of the examples, the same mold was used to mold and compare at the mold temperature used in normal gas assist molding.

3 is a schematic view of a molded article obtained by injection molding using the mold of the embodiment shown in FIG. It has the thickness part 13 which forms the hollow part by gas injection.

In this example, the molding was carried out under the molding conditions shown in Table 1.

Table 2 shows the results of the molding cycle for obtaining a molded article without any problem on the product when it was carried out to confirm the effect of this example.

According to the present invention, a product having excellent appearance quality in gas assist molding can be molded stably with a high cycle. In particular, in the inorganic filler filling material, problems such as the lifting of the filler, the weld line and the jetting can be solved, so that secondary processing similar to the surface treatment such as sanding, painting and plating can be omitted or reduced.

Claims (6)

In the gas assist molding method of the thermoplastic resin, when the molten thermoplastic resin is injected into the mold, the mold cycle of the mold is set to be 0-40 ° C lower than the heat deformation temperature of the thermoplastic resin to be injected. Molding method. The method of claim 1, wherein the mold temperature is set to be 0-40 ° C lower than the thermal deformation temperature of the thermoplastic resin until the completion of the thermoplastic resin after the start of the injection into the mold. High cycle molding method characterized by the above-mentioned. The mold temperature set forth in claim 1 or 2, in order to cool and solidify the mold temperature set 0-40 DEG C lower than the heat deformation temperature of the thermoplastic resin during one molding cycle, so as to quickly cool and solidify the thermoplastic resin injected into the mold. High cycle molding method characterized in that the lowering. 3. The high cycle molding method according to claim 2, wherein the timing at which the temperature of the mold begins to rise and fall during the molding cycle is arbitrarily controllable according to the molding material and the molding object. The method of claim 4, wherein the temperature rise of the mold is performed by using either hot water, heating oil, or electrothermal heater alone, and the temperature drop of the mold is performed by circulation of cold water or cooling oil. High cycle molding method. The high cycle molding method according to claim 1, wherein the gas is injected while the molten resin is injected or at some time after completion of the injection.

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