JPH05254032A - Method of molding foam synthetic resin molding - Google Patents

Abstract

PURPOSE:To enable a resin film to be formed by a method wherein a synthetic resin molding raw material is once melted at least on part of the molding surface, and it is then hardened again in the molding process. CONSTITUTION:An internal foaming mold comprising of a pair of molds is permitted to open prior to foam molding, and the other mold 2 is heated higher than the melting temperature of a synthetic resin molding raw material 5. Next, the molding space 3 side of the other mold 2 is allowed to be in contact with the molding material 5 within a resin bath 4 and, virile being stuck with a molten resin layer formed by making the molding raw material be in contact with the molding space 3 side, a pair of the molds are closed, and particles of the foam synthetic resin raw material are filled into the molding space 3, to hence a molding is made through foam-molding which is formed with a resin film at least on a part of the surface from the molten resin layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed synthetic resin molded article capable of forming a resin film which is obtained by once melting a synthetic resin molding raw material on at least a part of the surface of the molded article in the molding process and then again solidifying the resin film. Molding method.

[0002]

2. Description of the Related Art Conventionally, a foamed synthetic resin molded article has been molded by an in-mold foam molding mold composed of a pair of molds.

In such an in-mold foam molding mold, after closing the mold and filling the molding space with the expandable synthetic resin raw material particles, the mold is heated with steam and then with cooling water or the like. The mold is cooled and the raw material particles are foamed and fused to form a molded product.

[0004]

However, in such a foamed synthetic resin molded article, since the surface is formed of a thin film in which the surface skin of each raw material particle is connected in a hexagonal pattern, other products are When it rubs or hits, a peeling phenomenon or a depression phenomenon easily occurs on the surface.

Under these circumstances, it is conceivable to form a resin film on a portion where another object may be rubbed or hit and a peeling phenomenon or a depression phenomenon may occur. However, in order to provide such a resin film, a troublesome work such as attaching a non-foamed synthetic resin sheet is required in a later step.

In view of these problems, the method for molding a foamed synthetic resin molded article according to the present invention was devised. In the molding process, the synthetic resin molding raw material is once melted on at least a part of the molded article surface. The purpose is to be able to form a solidified resin coating again after the above.

[0007]

In order to achieve such an object, according to claim 1 of the present invention, a synthetic resin molding raw material in which at least a molding space side is retained in a resin tank after one mold is opened. The mold for in-mold foam molding composed of a pair of molds that can be contacted with the mold is opened before foam molding of the foamed synthetic resin molded product, and one mold is heated to the melting temperature of the molding raw material or higher. Heat and then contact at least the molding space side of one mold with the molding raw material that stays in the resin tank, and melt the molding raw material that has contacted this molding space side to attach a molten resin layer formed While keeping the above, the pair of molds are closed, the expandable synthetic resin raw material particles are filled in the molding space, and the molded product in which the resin coating is formed from the molten resin layer on at least a part of the surface is foam-molded. Molding method for foamed synthetic resin moldings The the gist. Further, in claim 2,
As the synthetic resin molding raw material, a non-foamed synthetic resin body in the form of pellets, flakes, powders, or the like is used. In claim 3, the molding space is filled with the expandable synthetic resin raw material particles and then heated. Cooling one mold and then heating the other mold, and claim 4 exemplifies forming the resin tank into a fluidized immersion tank. According to a fifth aspect of the present invention, separately, after the mold is opened, at least the molding space side is composed of a pair of molds that can be immersed in the molten synthetic resin molding raw material placed in the resin tank. The in-mold foam molding mold is opened prior to foam molding of the foamed synthetic resin molded product, and then at least the molding space side of one mold is immersed in the molten molding raw material placed in the resin tank. Then, while the molten resin layer or the solidified resin layer which is solidified is attached to the molding space side thereof, the mold pair is closed, and the expandable synthetic resin raw material particles are filled in the molding space. The gist is a method of molding a foamed synthetic resin molded article, in which a molded article having a resin coating formed from a molten resin layer or a solidified resin layer on at least a part of the surface is foam-molded.

[0008]

First, the in-mold foam molding mold used here is composed of a pair of cavity mold and core mold as in the conventional case. When the mold is closed, foam molding is performed between them. A molding space for the resin molded product is formed. Then, for example, the core mold can be laterally opened with respect to the cavity mold, and further, after the core mold is opened, the molding space side can be turned downward and can be further moved downward. Arrange. Further, the resin tank in which the synthetic resin molding raw material is retained is arranged in the moving direction of the core mold downward so as to be able to contact at least the molding raw material on the side of the molding space, for example, the entire molding raw material retained inside.

Then, the pair of cavity mold and core mold are retracted to the side of the cavity mold to open the mold, and the core mold is heated to a temperature above the melting temperature of the molding raw material. After that, the core die is rotated so that the molding space side faces downward, and is moved downward as it is, and at least the entire molding space side is brought into contact with the molding raw material staying in the resin tank, and the entire molding space side is moved. A molten resin layer formed by melting the forming raw material that has come into contact with is attached. Next, the core mold is moved in the opposite direction, and the mold is closed while leaving a usual cracking gap between the core mold and the cavity mold. After that, in the molding space formed between the pair of cavity molds and the core mold, for example, a foamable synthetic resin raw material which is the same as or can be fused with the molding raw material from the raw material filling feeder provided on the cavity mold side. Fill the particles. At this time, the molten resin layer attached to the molding space side of the core mold is fused with the raw material particles behind. Then, after completely closing the pair of cavity mold and core mold, the heated core mold is cooled by supplying, for example, cooling water to the heating chamber in the back. In this way, the resin coating in which the molten resin layer is solidified is formed on the entire molding space side of the core mold. Next, steam is supplied to the heating chamber behind the cavity mold and heated to a normal foam molding temperature to foam and fuse the raw material particles in the molding space. After this,
The cavity mold is cooled by supplying cooling water, for example, to the heating chamber behind it. The molded product thus molded is taken out of the molding space by laterally opening the core mold from the cavity mold. Then, by repeating such operations, the molded products are sequentially foam-molded.

Separately, it is also possible to put the molten forming raw material in the resin tank. At this time, for example, in the moving direction of the resin tank downward of the core mold, at least the entire molding space side is inside. It is arranged so that it can be immersed in the molten forming raw material. In this case, the core mold may be heated in advance to the melting temperature of the molding raw material or higher, the normal foam molding temperature, or may not be heated prior to foam molding. Then, the foam molding process is performed in the same manner as described above. When this core mold is not heated, a solidified resin layer is formed after it is immersed in a resin tank and before foam molding, but this is fused with the raw material particles behind by the heating step during foam molding and the resin coating film is formed. Becomes

[0011]

EXAMPLE A method for molding a foamed synthetic resin molded article according to the present invention will be further described with reference to the accompanying drawings.

First, the in-mold foam molding die used here is composed of a pair of a cavity die shown as 1 in FIG. 1 and a core die shown as 2 in the same manner as in the prior art. In this case, as shown in the drawing, the molding space 3 for the foamed synthetic resin molded product is formed between the two. And
The core mold 2 can be opened laterally on the right side of the drawing with respect to the cavity mold 1, and after the core mold 2 is opened,
As shown in FIG. 2, the molding space 3 side is arranged to be rotatable downward and movable downward. Furthermore, 4 in the figure
Is a resin layer in which a non-foamed synthetic resin body in the form of pellets, flakes, powders or the like is put as a synthetic resin molding raw material 5 inside. In the moving direction, at least the entire molding space 3 side is arranged so as to be able to contact the molding raw material 5 placed inside. In the figure, 6 is a molding space 3 formed between the cavity mold 1 and the core mold 2 which are provided on the side of the cavity mold 1 and are closed.
A raw material filling feeder that fills the same type of raw material as the molding raw material or the fusible synthetic resin raw material particles that can be fused, and 7 and 8 are heating chambers provided behind the cavity mold 1 and the core mold 2 on the molding space 3 side. . In addition to these, the mold includes a pair of cavity mold 1, a steam pipe for supplying steam to the heating chambers 7, 8 of the core mold 2, a water pipe for supplying cooling water, a drain pipe for draining the inside, and the like. Further, although a release pin for releasing the molded product is provided, the illustration is omitted.

Then, as shown in FIG. 2, the pair of the cavity mold 1 and the core mold 2 is replaced by the core mold 2 and the cavity mold 1.
The core mold 2 while retracting to the side of the mold and opening the mold
Is heated above the melting temperature of the synthetic resin molding raw material 5. This operation may be performed one before the other or simultaneously. After that, the core die 2 is rotated so that the molding space 3 side faces downward as shown by the one-dot chain line state in the figure, and moved downward as it is, and at least the entire molding space 3 side is put in the resin tank 4. The molding raw material 5 brought into contact with the entire molding space 3 side by contacting with the molding raw material 5
A molten resin layer formed by melting is attached. Next, the core mold 2 is moved in the opposite direction, and the mold is closed with a usual cracking gap left between the core mold 2 and the cavity mold 1 as shown in FIG. After that, the expandable synthetic resin raw material particles are filled in the molding space 3 formed between the pair of cavity mold 1 and the core mold 2 from the raw material filling feeder 6 provided on the cavity mold 1 side. At this time, the molten resin layer attached to the molding space 3 side of the core mold 2 is fused with the raw material particles behind. After the pair of cavity mold 1 and core mold 2 are completely closed, the heated core mold 2 is cooled by supplying cooling water to the heating chamber 8 behind it. In this way, a resin coating in which the molten resin layer is solidified is formed on the entire molding space 3 side of the core mold 2. Next, steam is supplied to the heating chamber 7 behind the cavity mold 1 to heat the same to a normal foam molding temperature, and the raw material particles in the molding space 3 are foam-melted. After this, the cavity mold 1 is cooled by supplying cooling water to the heating chamber 7 behind it. The molded product thus molded is taken out from the molding space 3 by laterally opening the core mold 2 from the cavity mold 1. Then, by repeating such operations, the molded products are sequentially foam-molded.

In this way, the resin coating 11 is formed on the surface as schematically shown in FIG. 4, and the raw material particles 12 are foamed and fused behind this to form the molded article 10 having a unified structure. .

By the way, the core mold 2 to be brought into contact with the molding raw material 5 in the resin tank 4 has a molding space 3 like a conventional mold.
It is not always necessary to provide a communication hole for communicating the side with the heating chamber 8 side. However, it does not prevent provision of such a communication hole in the core mold 2.

Here, as synthetic resin molding raw materials and expandable synthetic resin raw material particles, styrene resins represented by polystyrene, polyolefin resins represented by polyethylene and polypropylene, and various synthetic resin bodies of other copolymers. What is formed from is available.

The core mold 2 may be heated to, for example, 185 ° C. or higher, preferably about 185 to 200 ° C. Further, in the cavity mold 1 for performing ordinary foam molding,
The mold temperature may be set to, for example, about 105 to 110 ° C.

Next, FIG. 5 shows another example of the in-mold foam molding die used in the molding method according to the present invention and the resin tank provided on its side. This is because a pair of cavity mold 1 and a core mold 2 are arranged so that the core mold 2 can be opened upward as shown in the drawing, and a pair of cavity mold 1 and core mold 2 can be opened. The resin tank 4 is arranged so as to correspond to the lateral position of the mold 2 while the mold is opened. Then, here, the pair of cavity mold 1 and core mold 2 is retracted from the core mold 2 above the cavity mold 1 to open the mold, and the core mold 2 is heated to the melting temperature of the molding raw material 5 or higher. After heating and then moving the resin tank 4 between them, the core mold 2 is moved downward or the resin tank 4 is moved upward, and the molding space 3 side thereof is retained in the resin tank 4. It is brought into contact with the forming raw material 5.

Further, FIG. 6 shows an example in which the heating means for the core mold 2 is provided outside of the pair of cavity mold 1 and core mold 2. This is a heating means for the core mold 2 between a pair of cavity mold 1, core mold 2 and the resin tank 4 on its side, or on a further side of the resin tank 4 (not shown). A heating tank in which a heating medium 14 such as heating oil is stored is provided inside shown as 13. In this case, the heating tank 13 may be disposed between the pair of cavity mold 1 and core mold 2 shown in FIG. 5 and the resin tank 4 on its side, or on a further side of the resin tank 4. Then, here, before the molding space 3 side of the core mold 2 is brought into contact with the molding raw material 5 staying in the resin tank 4, it is immersed in a heating medium 14 such as heating oil in the heating tank 13, This is heated above the melting temperature of the forming raw material.

In the illustrated embodiment, the resin tank 4 can be formed as a fluidized immersion tank.

As the molding raw material 5 to be placed in the resin tank 4, expandable synthetic resin raw material particles can be used.

Further, the molding raw material 5 in the resin tank 4 of the core mold 2
It is also possible to adjust the contact depth to the molding raw material 5 so that the molding raw material 5 is attached only to the front end side of the molding space 3 side.

Further, similarly, the cavity mold 1 can be brought into contact with the molding raw material 5 in the resin tank 4 separately provided, for example. In this case, a molded product having a resin coating on the entire surface can be molded.

Separately, it is also possible to put the molten forming raw material 5 in the resin tank 4, and at this time also, FIG.
As shown in FIG. 3, the resin tank 4 is disposed in the relative moving direction of the core mold 2 so that at least the molding space 3 side thereof can be immersed in the molten molding raw material 5 inside. In this case, core mold 2
Prior to foam molding, it may be heated in advance to a melting temperature of the molding raw material 5 or higher, a normal foam molding temperature, or may not be heated. Then, the foam molding process is performed in the same manner as described above. When this core mold 2 is not heated, a solidified resin layer is formed after it is immersed in the resin tank 4 and before foam molding, but this is fused with the raw material particles behind by the heating step during foam molding. It becomes a resin film.

[0025]

As described above, in the method of molding a foamed synthetic resin molded article according to the present invention, after the synthetic resin molding raw material is once melted on at least a part of the surface of the molded article in the molding process,
The solidified resin coating can be formed again.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of an in-mold foam molding mold used in a molding method of a foam synthetic resin molded product according to the present invention and a resin tank provided on its side.

FIG. 2 is an explanatory diagram showing the operating state of the device.

FIG. 3 is an explanatory diagram showing an operating state of this.

FIG. 4 is an explanatory view schematically showing a cross section of a molded product molded by the molding method according to the present invention.

FIG. 5 is an explanatory view showing the outline of another example of the in-mold foam molding die used in the molding method according to the present invention and the resin tank provided at the side position thereof.

FIG. 6 is an explanatory view showing an outline of a mold for in-mold foam molding and a heating means for the core mold provided on the side of the mold.

[Explanation of symbols]

 1 cavity mold 2 core mold 3 molding space 4 resin tank 5 molding raw material 6 raw material filling feeder 7 heating chamber 8 heating chamber 10 molded product 11 resin coating 12 raw material particles 13 heating tank 14 heating medium

Claims (5)

[Claims] 1. An in-mold foam molding metal mold comprising a pair of metal molds, which can be brought into contact with a synthetic resin molding raw material that remains in a resin tank at least on the molding space side after one mold is opened. The mold is opened prior to foam molding of the foamed synthetic resin molded product, and one mold is heated above the melting temperature of the molding raw material, and then at least the molding space side of one mold is placed in the resin tank. With a molten resin layer formed by contacting the stagnant molding raw material and melting the molding raw material that has come into contact with the molding space side, the pair of molds are closed and placed in the molding space. A method for molding a foamed synthetic resin molded article, which comprises filling raw material particles of a foamable synthetic resin and foam-molding a molded article having a resin coating formed from a molten resin layer on at least a part of the surface. 2. A pellet-shaped synthetic resin molding raw material,
The method for molding a foamed synthetic resin molded article according to claim 1, wherein a non-foamed synthetic resin body in the form of flakes or powder is used. 3. The foamed synthetic resin molding according to claim 1, wherein after the foamable synthetic resin raw material particles are filled in the molding space, one heated mold is cooled and then the other mold is heated. Molding method. 4. The resin bath is formed as a fluidized dipping bath.
Alternatively, the method for molding the foamed synthetic resin molded article according to 2 or 3. 5. In-mold foaming composed of a pair of molds which can be immersed in a molten synthetic resin molding raw material in which at least a molding space side is placed in a resin tank after one mold is opened. The molding die is opened prior to foam molding of the foamed synthetic resin molded product, and then at least the molding space side of one mold is dipped in the molten molding raw material placed in the resin tank, While the molten resin layer or the solidified resin layer obtained by solidifying the molten resin layer is attached to the molding space side, the pair of molds are closed, and the foamable synthetic resin raw material particles are filled in the molding space, and at least one surface A method for molding a foamed synthetic resin molded article, which comprises foam-molding a molded article having a resin coating formed from a molten resin layer or a solidified resin layer on its part.