JPH091579A - Method of accelerating the foaming of foam synthetic resin molding and foaming-accelerated molding - Google Patents

Abstract

PURPOSE: To enable formation of complicate-shaped of thin products without a fail by expanding the cavity promptly after the cavity is filled with a foam synthetic resin, so that the foaming of an interior is accelerated. CONSTITUTION: Polystyrene is injected into cavities 3, 3. When foam polystyrene fills the cavities 3, 3 and forms a skin layer 2a of a product, the injection is stopped and the supply of pressure gas is stopped. A mold 1 is opened by a control means moving back a movable part 1b. Thereby, the cavities 3, 3 are enlarged at the side of the stationary part of the mold 1, so that the cavities 3, 3 separate from the ornamental side of the molding, thus instantly releasing the pressure gas and foaming gas that have been present in the cavities 3, 3. Simultaneously, the molding is released from the foaming restraint, so that foaming occurs actively in an interior of the molding that is still in a molten state, thus achieving a sufficient porosity in the interior portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for promoting foaming of a foamed synthetic resin molded product and a foamed molded product. More specifically, the present invention relates to a novel foaming promotion method of rapidly expanding a cavity after fully filling a foaming synthetic resin into the cavity to promote internal foaming, and a foaming-promoting molded article having a specific structure produced by this method.

[0002]

2. Description of the Related Art Conventionally, as a method of accelerating the foaming of a foamed synthetic resin molded article, the amount of the synthetic resin filled in the cavity is kept to 80 to 90% of the full filling, and the filling is reduced by the foaming. The method is known. However, in this weight reduction method, it is difficult for the raw material resin to reach a portion having a large flow resistance, so that it is possible to mold a simple shape or a thick product having an average wall thickness of 5 mm or more. In the present situation, it is impossible to mold a complicated product or a thin product having an average wall thickness of 5 mm or less. Therefore, there is a strong demand in the industry to develop a method for reliably molding such a product. It was

[0003]

DISCLOSURE OF THE INVENTION The present invention was developed to meet the above-mentioned demands of the industry. After the cavity is fully filled with the foam synthetic resin, the cavity is rapidly expanded to promote foaming. As a result, after the outer shape of the product is formed, the inside of the product is sufficiently foamed, the shape is accurate, the surface condition is good, the effect of improving the characteristics by sufficient foaming is great, and the product is not deformed due to the residual foaming stress. Not happening, and
Provided is a method and a molded article capable of producing a foam-promoting molded article having a unique structure by adjusting the expansion range of a cavity by greatly adjusting the degree of foaming.

[0004]

In order to solve the above-mentioned problems, a method for promoting foaming of a foamed synthetic resin molded product and a foaming-promoted molded product according to the present invention are such that a mold cavity is filled with a foamed synthetic resin. After filling the cavity, the method is used to quickly expand the cavity to promote foaming inside the molded product.In doing so, after expanding the cavity to promote foaming inside the product, the cavity is quickly expanded. A method of compressing the product by shrinking it and a method of placing a pressure gas that suppresses foaming in the cavity when filling the mold synthetic resin into the cavity of the mold are adopted, and the cavity is filled after full filling. By accelerating the expanding internal foaming, we can obtain a unique foam-promoting molded product with a structure in which the front and back skin layers are bonded by fine fibers and a structure with cavities between the front and back skin layers. It is intended to so that.

[0005]

In the method for promoting foaming of the foamed synthetic resin molded product according to the present invention, when the foamed synthetic resin is filled into the cavity of the mold until it is fully filled, the foamed synthetic resin spreads to every corner of the cavity and touches the mold. Since the part forms a skin layer to shape the product, with this, if the mold is opened a little or the movable part of the mold is moved a little and the cavity is expanded, the decorative side of the molded product separates from the mold, The accumulated gas is released between the make-up side and the mold, and the suppression of foaming by the mold is released, so that the product promotes internal foaming and performs sufficient foaming. Since the mold is transferred by pressing, the external shape is accurate and the surface condition is good, even in the case of complicated products and thin products of 5 mm or less, and sufficient foaming reduces product weight, heat insulation and sound insulation. , Buffer It also has excellent properties such as relaxation of elasticity, and enables easy molding of excellent products that do not show deformation of the product due to residual foaming stress. Moreover, according to this method, the expansion of the cavity can be adjusted. It is possible to obtain a peculiar foaming-promoting molded article having a constitution in which the front and back skin layers are bonded by fine fibers and a constitution in which cavities exist between the front and back skin layers by freely changing the foaming degree.

Further, according to this method, after the foamed synthetic resin is fully filled in the cavity as described above, the cavity is rapidly expanded to promote the foaming, and thereafter the expanded cavity is quickly contracted. , When the mold is pressed against the surface of the molded product whose volume has increased due to internal foaming, the mold transfer of this part is forced, so the addition of this step improves the smoothness of the product surface and improves the appearance quality. It greatly contributes to making it.

Further, according to this method, when the foam synthetic resin is filled in the cavity, a pressurized gas is placed in the cavity, and the foam synthetic resin filled in the cavity is pressurized by the pressure gas. This pressure suppresses foaming of the foamed synthetic resin and entraps the foaming gas inside, so that the influence of foaming is less likely to appear on the surface of the molded product, and the surface condition of the molded product can be further improved.

[0008]

EXAMPLE An example of a method for promoting foaming of a foamed synthetic resin molded article according to the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional plan view showing a molding start state of a product according to a first embodiment of a method for promoting foaming of a foamed synthetic resin molded product according to the present invention, and FIG. FIG. 3 is a cross-sectional plan view showing the accelerated state, FIG. 3 is a side view showing the molding start state of the product shown in FIG. 1 with the fixed side of the mold omitted, and FIG. 4 is a product formed by slightly expanding the cavity in the same embodiment. FIG. 5 is an enlarged cross-sectional view of a product formed by increasing the cavity expansion method in the same embodiment, and FIG. 6 is an enlarged cross-sectional view of a product formed by further increasing the cavity expansion method in the same embodiment. FIG. 7 is a cross-sectional plan view showing the formation state of the product of the second embodiment of the method for accelerating the foaming of the foamed synthetic resin molded product according to the present invention, showing the formation state, and FIG. FIG. 9 is a cross-sectional plan view showing a state of promoting 7 is a side view showing the molding start state of the product shown in FIG. 7 with the fixed side of the mold omitted, FIG. 10 is a partially enlarged cross-sectional view showing a state in which the product molded according to the above embodiment is deformed when foaming is promoted, and FIG. FIG. 10 is a partially enlarged cross-sectional view showing an example of shape correction performed on the fixed side of the mold to prevent deformation, and FIG. 12 shows a third embodiment of the method for promoting foaming of a foamed synthetic resin molded product according to the present invention. FIG. 13 is a cross-sectional plan view showing the molding start state of the product, FIG. 13 is a cross-sectional plan view showing the condition of molding the product of the above-mentioned embodiment to promote foaming, and FIG. 14 is a foaming acceleration method of the foamed synthetic resin molded product according to the present invention. FIG. 9 is a perspective view showing a part of a product molded according to the fourth embodiment of FIG.

In the first embodiment shown in FIGS. 1 to 6, reference numeral 1 indicates a mold for molding a wind direction adjusting vane 2 of an air conditioner. The vane 2 is provided between a fixed side 1a and a movable side 1b.
As shown in FIG. 3, two cavities conforming to are provided side by side, and a sprue 4 is provided in the middle of the cavities 3 and 3, and the sprue 4 is communicated with the cavities 3 and 3 through the runner 5 and the gate 6. Vent grooves 8 communicating with the cavities 3 and 3 via a slit 7 are provided on the outer sides of the three sides of the cavity 3, and a pressure gas passage 9 is connected to each of the vent grooves 8 to burn the connection portion. The means for opening and closing the movable side 1b of the mold 1 (illustration omitted) is provided with a filter member 10 made of a binding metal or the like, and a control means for slightly opening the mold by adjusting the operating time by a timer (drawing). In this mold 1, the fixed side 1a is the makeup side of the product and the movable side 1b is the back side of the product, so molding is performed when the mold is opened. Items are always movable Projections Toka irregularities to improve the adhesion of the molded article to the movable side 1b away from the fixed side 1a arrived at b, so as subjected to surface roughening or the like.

When the vane 2 is molded by the mold 1, the mold is clamped and a pressurized gas of 20 kg / cm ² is sent into the cavities 3 and 3 from the passage 9 and placed.
Polystyrene to which 0.6% by weight of a CA-based foaming agent was added was used at a nozzle temperature of 195 ° C and a pressure of 100 kg / cm ^2.
When the foamed polystyrene fills the cavities 3 and 3 and forms the skin layer 2a of the product, the injection is stopped and the supply of pressure gas is stopped.
The movable side 1b of the mold 1 was retracted by about 0.2 mm by the control means to open the mold. As a result, as shown exaggeratedly in FIG. 2, the cavities 3 and 3 are separated from the makeup side of the molded product by expanding the fixed side of the mold 1, and the pressure gas and foaming gas existing in the cavities 3 and 3 are instantaneously separated. At the same time, the suppression of foaming added to the molded product is released, so that active foaming is performed inside the molded product which is still in a molten state, and at the same time, sufficient porosity 2b of this portion is achieved, and Due to the volume increase due to foaming, the makeup side once separated from the mold surface is pressed against the mold surface to perform the mold transfer. Therefore, according to this embodiment, the maximum thickness is as thin as 3.7 mm, and the vane 2 provided with the pivot 11 as shown in FIG. In addition to the effects of weight reduction, heat insulation, sound insulation, cushioning, etc. of the product due to sufficient internal foaming, an excellent vane 2 that does not cause deformation of the product due to residual stress is formed. The specific gravity of was 1.02 in the foam molding without mold opening, but was reduced to 0.9.

Next, in order to confirm the relationship between the mold opening size and the foaming degree in the above embodiment, the mold opening size was set to 0.1 m.
m and 0.15 mm were changed, and the specific gravity in this case was measured. As a result, the specific gravity was 1.0 when the mold opening was 0.1 mm and changed to 0.98 when the mold opening was 0.15 mm, and the foaming degree increased as the size of the mold opening increased. I was able to confirm. Therefore, the raw material was changed to polypropylene, which is easy to foam, and an inorganic foaming agent was added to this by 3% by weight.
Nozzle temperature 200 ° for added cavities 3 and 3
C, pressure 80kg / cm ² injection, cavity 3,3
After the full filling, the cavities 3 and 3 were immediately expanded by the mold opening of 3 mm and 5 mm to promote foaming. As a result, in the case of 3 mm, the inside of the product has a structure in which the front and back skin layers 2a are bonded by countless fine fibers 2c as shown in FIG. 5, and the specific gravity is 0.7, and in the case of 5 mm, As shown in FIG. 6, a cavity 2 is formed between the front and back skin layers 2a.
d has a specific gravity of 0.6, and according to these examples, the foaming degree can be widely changed by adjusting the dimension of the mold opening to facilitate a foaming-promoted molded product having a unique internal structure. It was confirmed that it was surely obtained.

Further, in the above embodiment, after the cavity is expanded and the pressure gas is released by opening the mold, the once opened mold is closed and the molded product whose volume is increased by sufficient internal foaming is fixed to the mold surface. When pressed against, the mold side of the makeup side of the molded product is forcibly transferred, so that the makeup side becomes more smooth and effective in improving the appearance beauty of the molded product, and this compression action is shown in FIG. In the case of a foam-promoting molded article in which the front and back skin layers 2a are bonded by the fine fibers 2c as shown in FIG.
The cushioning property and the soundproofing property can be greatly improved.

In the second embodiment shown in FIGS. 7 to 11, reference numeral 1 indicates a mold for molding a handle 12 for an automobile, wherein the handle 1 is provided between a fixed side 1a and a movable side 1b.
2. An annular cavity 3 suitable for 2 is formed as shown in FIG. 9, a sprue 4 is provided at the center of the cavity 3, and the sprue 4 is communicated with the cavity 3 at two points via a runner 5 and a gate 6. Four vent grooves 8 are provided on the outside of the cavity 3 so as to communicate with them through the slits 7, and the vent grooves 8 each have a passage 9 for pressurized gas.
And a filter member 10 made of sintered metal or the like is provided at the connecting portion, and an annular airtight holding member 13 is provided outside the vent groove 8, and the movable side 1b of the mold 1 is The opening / closing means (not shown) is equipped with a control means (not shown) for adjusting the operation time by a timer or the like and performing a slight mold opening.

When the handle 12 is molded by the mold 1, the mold is clamped and a pressurized gas of 20 kg / cm ² is fed into the cavity 3 through the passage 9 to make the ADCA-based foaming agent 1% by weight. The added soft vinyl chloride is injected into the cavity 3 at a nozzle temperature of 160 ° C. and a pressure of 50 kg / cm ² , and when the cavity 3 is fully filled and the skin layer 12a of the product is formed, the injection is stopped and the pressure gas The feeding was stopped, and the movable side 1b of the mold 1 was retracted by about 1.5 mm by the control means to open the mold. As a result, as shown exaggeratedly in FIG. 10, in the cavity 3, the fixed side 1a of the mold 1 is expanded, separated from the makeup side of the molded product, and the pressure gas and foaming gas existing in the cavity 3 are instantaneously released. Then, since the suppression of the foaming added to the molded product is released, the foaming proceeds smoothly inside the molded product which is still in the molten state, and the porosity 12b of this portion is sufficiently achieved, and According to this embodiment, the handle 12 having the cored bar 14 inserted therein has no appearance defect, the surface is smooth and beautiful, and the surface is smooth and sufficient. It has been confirmed that such internal foaming can be performed in a sufficient state for weight reduction, heat insulation, sound insulation, and cushioning. However,
In this embodiment, since soft vinyl chloride is used as a raw material, when the mold is opened to expand the cavity 3 to promote foaming after the outer shape of the product is formed, a part of the molded product exposed from the fixed side 1a of the mold 1 is foamed. As a result, the fixed side 1a of the mold 1 at the portion where the bulge occurs is shaped so as to be recessed as shown in FIG. If corrected, when the cavity 3 is expanded to promote foaming, it is possible to make the cross-sectional shape of the product a regular shape when this portion bulges.

In the third embodiment shown in FIGS. 12 and 13, reference numeral 1 denotes a mold for molding the rimmed disk 15.
A cavity 3 that fits the edged circular plate 15 is formed between the fixed side 1a and the movable side 1b as shown in FIG. 12, and a sprue 4 is connected to the center of the cavity 3.
In this embodiment, since the shape of the product is simple and small, the means for introducing the pressure gas adopted in the above embodiment is omitted, but it can be adopted. In the example, the movable part 1b is not opened to expand the cavity 3, but the movable part 16 is provided in a part of the cavity.
This is performed by moving the portion 16 back and forth. That is, a movable portion 16 corresponding to the cavity 3 is provided on the movable side 1b of the mold 1, and the movable portion 16 is moved forward and backward when molding (not shown).
As shown in FIG. 12, when the skin layer of the molded product is formed by injecting the cavity 3 into the cavity 3 by shrinking the cavity 3 and filling the raw material, the movable portion 16 is quickly shown in FIG. It is configured to retreat to the position and expand the cavity 3 to promote foaming.

When the edged disc 15 is formed by the die 1, the die is clamped and ADCA is inserted into the cavity 3.
Polystyrene containing 0.6% by weight of a foaming agent was injected at a nozzle temperature of 195 ° C and a pressure of 85 kg / cm ² , and when this filled the cavity 3 to form a skin layer of the product, the movable side was quickly moved. The moving part 16 of 1b was moved back 0.2 mm by the moving means. As a result, Cavity 3
As shown exaggeratedly in FIG. 11, the movable part 1b side expands, releases the foaming gas away from the outer surface of the molded product, and releases the suppression of foaming added to the molded product, so that the molded product is still in a molten state. Vigorous foaming is performed inside the product, and the transfer operation of pressing the surface of the molded product against the mold due to the volume increase due to foaming is sufficiently achieved in this part, so that the appearance is also in this embodiment. At the same time, it was possible to easily obtain a product having a sufficient effect of improving the characteristics by the internal foaming.

In the embodiment shown in FIG. 14, reference numeral 17 is
This shows a vane for adjusting the wind direction of an air conditioner, in which several vanes 17 are fixed pieces 19 and movable pieces 20 by hinges 18 on both sides.
With a structure in which 1% of an inorganic foaming agent was added to polypropylene, the mold (not shown) was fully filled, and then the movable side of the mold was quickly retracted by 0.2 mm to form the cavity. It was spread and molded by a method of promoting foaming. As a result, the specific gravity changed from 0.85 in the case of foam molding without expanding the cavity to 0.8, and the flexible elasticity is given to the hinge 18 by the promotion of foaming, and it is smoother with less force than before. Since it moves, it was confirmed that the load of the motor can be reduced by about 10% when the vane operation is performed by the motor.

[0019]

As described above, in the method for promoting foaming of a foamed synthetic resin molded product according to the present invention, when the outer shape of the product is formed by fully filling the cavity with the foamed synthetic resin, the cavity is rapidly expanded and foamed. Because it suppresses the suppression of foaming and promotes foaming, it is possible to reliably mold even complicated shapes and thin products of 5 mm or less that cannot be obtained by conventional foaming promotion by the weight loss filling formula. It is accurate, has excellent surface smoothness, and achieves sufficient foaming, so not only is the product lightweight, heat-insulating, sound-insulating, shock-absorbing, etc. No deformation occurs, and the elasticity of the synthetic resin can be adjusted by adjusting the degree of foaming to obtain excellent operability when the hinge is molded. In particular, this method can realize a structure in which the front and back skin layers are bonded by fine fibers or a peculiar structure in which cavities exist between the front and back skin layers, by adjusting the range in which the cavity is expanded. It is effective in reforming the structure and saving the material, and at the time of filling the synthetic resin foam, there is a pressure gas in the cavity to suppress the foaming at the time of filling, or to promote the foaming once. When the method of forcing the product after foaming by re-compressing the expanded cavity and again forcing the product, a good result is obtained for further improving the surface condition of the product.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view showing a molding start state of a product of a first embodiment of a method for promoting foaming of a foamed synthetic resin molded product according to the present invention.

FIG. 2 is a cross-sectional plan view showing a state in which the product of the above embodiment is molded to promote foaming.

FIG. 3 is a side view showing the molding start state of the product shown in FIG. 1 with the fixed side of the mold omitted.

FIG. 4 is an enlarged cross-sectional view of a product formed by slightly expanding the cavity in the above embodiment.

FIG. 5 is an enlarged cross-sectional view of a product formed by increasing the method of expanding the cavity in the same embodiment.

FIG. 6 is an enlarged cross-sectional view of a product formed by further expanding the method of expanding the cavity in the same example.

FIG. 7 is a cross-sectional plan view showing a forming state showing a molding start state of the product of the second example of the foaming acceleration method for the foamed synthetic resin molded product according to the present invention.

FIG. 8 is a cross-sectional plan view showing a state in which the product of the above Example is molded to promote foaming.

FIG. 9 is a side view showing the molding start state of the product shown in FIG. 7 with the fixed side of the mold omitted.

FIG. 10 is an enlarged cross-sectional view of a part showing a state in which the product molded according to the above embodiment is deformed when foaming is promoted.

FIG. 11 is a partially enlarged cross-sectional view showing an example of shape correction performed on the fixed side of the mold to prevent the deformation shown in FIG.

FIG. 12 is a cross-sectional plan view showing the molding start state of the product of the third embodiment of the method for promoting foaming of a foamed synthetic resin molded product according to the present invention.

FIG. 13 is a cross-sectional plan view showing a state in which the product of the above Example is molded to promote foaming.

FIG. 14 is a perspective view showing a part of a product molded by the fourth embodiment of the method for promoting foaming of a foamed synthetic resin molded product according to the present invention.

[Explanation of symbols]

 1 type 1a fixed side 1b movable side 3 cavities 2, 12, 15, 17 product 10 passage of pressurized gas

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Claims (5)

[Claims] 1. A foamed synthetic resin molded article characterized by injecting a foamed synthetic resin into a cavity of a mold, filling the cavity with the cavity, and then rapidly expanding the cavity to promote foaming inside the molded article. Foam promotion method. 2. A foamed synthetic resin molded product according to claim 1, wherein after expanding the cavity to promote foaming inside the product, the cavity is quickly contracted to press the molded product. Promotion method. 3. A foamed synthetic resin molded article according to claim 1, wherein when the foamed synthetic resin is filled in the mold cavity, a pressure gas for suppressing foaming is placed in the cavity. Foam promotion method. 4. A foaming-promoting molded article characterized in that a structure in which the front and back skin layers are bonded by fine fibers is obtained by promoting internal foaming which expands the cavity after full filling. 5. A foaming-promoting molded article, wherein a structure having cavities between the front and back skin layers is obtained by promoting internal foaming that expands the cavities after full filling.