JPH05254031A - Method of molding foam synthetic resin molding - Google Patents

Abstract

PURPOSE:To enable a molding to be molded by a simple apparatus and, moreover, an easy operation, wherein such a molding has a resin film that is formed by allowing a molding raw material to be heat-melted at least in particular on a part of the surface in the molding process. CONSTITUTION:After one mold 2 is opened, an internal foaming mold being composed of a pair of molds 1, 2 where the forming space 3 side is designed to be in contact with a heat medium 5 staying within a heating bath 4 is permitted to open prior to the foam molding of a foam synthetic resin molding, and at least a forming space 3 side of the other mold 2 is heated by a heating medium 5 staying within the heating bath 4, and subsequently the mold is closed, and then particles of foam synthetic resin raw material are filled into the molding space 3, with the result that a molding is made by foam molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a foamed product which can be molded by a simple apparatus and a simple operation, particularly, a molded product having a resin coating film formed by heating and melting a molding raw material on at least a part of the surface. The present invention relates to a method for molding a synthetic resin molded product.

[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, since such a foamed synthetic resin molded article has a surface composed of a thin film in which the surface of each foamable synthetic resin raw material particle is continuous in a hexagonal shape, When another object rubs or hits, a peeling phenomenon or a depression phenomenon easily occurs on the surface.

Under these circumstances, the raw material particles are heated and melted in the in-mold foam molding process to form a resin coating on a portion where another object may be rubbed or hit and a peeling phenomenon or a depression phenomenon may occur. Can be considered. However, since heating of the mold is usually performed by supplying steam, when a conventional mold is used, high-pressure steam is required, which is problematic in terms of equipment and operation.

In view of the above problems, it was invented by the method for molding a foamed synthetic resin molded article according to the present invention, in particular, a resin formed by heating and melting molding atoms in at least a part of the surface in the molding process. It is an object of the present invention to be able to form a molded article having a coating film with a simple device and a simple operation.

[0007]

In order to achieve such an object, according to claim 1 of the present invention, after one mold is opened, at least the molding space side is contacted with a heating medium staying in the heating tank. A mold for in-mold foam molding composed of a pair of enabled molds is opened prior to foam molding of a foamed synthetic resin molded product, and at least the molding space side of one mold is placed in the heating tank. A method of molding a foamed synthetic resin molded article is described, in which a molded article is foamed by heating with a heating medium that stays, then closing the mold, and filling the molding space with foamable synthetic resin raw material particles. To do. Further, in claim 2, the heating medium is heated to a temperature not lower than the melting temperature of the expandable synthetic resin raw material particles,
The molding space side of one mold is heated to a temperature not lower than the melting temperature of the raw material particles. In claim 3, one mold is filled with the expandable synthetic resin raw material particles and then heated with a heating medium. Cooling the mold and then heating the other mold were each illustrated.

[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. Furthermore, a heating tank that heats at least the entire molding space side of the core mold is placed in the downward moving direction of the core mold.
The molding space side is arranged so that it can be dipped in a heating medium such as heating oil stored inside. At this time, the heating medium is heated above the melting temperature of the expandable synthetic resin raw material particles.

Then, after the pair of cavity mold and core mold are retracted to the side of the cavity mold and the mold is opened, the core mold is rotated so that the molding space side faces downward. It is moved and moved downward as it is, and at least the molding space side is immersed in a heating medium such as heating oil stored in a heating tank to heat the entire molding space side to the melting temperature of the raw material particles or higher. Next, the core mold is moved in the opposite direction to close the mold leaving a required gap between the core mold and the cavity mold. After that, raw material particles are filled into a molding space formed between the pair of cavity molds and the core mold, for example, from a raw material filling feeder provided on the cavity mold side. At this time, the raw material particles in contact with the molding space side of the core die are heated and melted and fused with the raw material particles behind. Then, after the pair of cavity mold and core mold are completely closed, the core mold heated with a heating medium such as heating oil is cooled by supplying, for example, cooling water to the heating chamber behind. In this way, the raw material particles are once melted to the entire molding space side of the core mold,
The solidified resin film is formed again. Next, steam is supplied to the heating chamber behind the cavity mold to heat it, and the raw material particles in the molding space are foamed and fused. 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.

[0010]

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. Further, as shown in the drawing, the heating tank 4 for heating at least the entire molding space 3 side of the core mold 2 is moved in the downward moving direction of the core mold 2, and the heating oil stored inside the molding space 3 side. It is arranged so that it can be immersed in the heating medium 5 such as. At this time, the heating medium 5 is heated above the melting temperature of the expandable synthetic resin raw material particles. Reference numeral 6 in the figure is a raw material filling feeder for filling raw material particles into a molding space 3 formed between a pair of closed cavity molds 1 provided on the side of the cavity mold 1 and a core mold 2, 7 , 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 molds, a steam pipe that supplies steam to the heating chambers 7 and 8 of the cavity mold 1 and the core mold 2, a water pipe that supplies cooling water, a drain pipe that drains internal water, and molding. Although a release pin for releasing the 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.
After retracting to the side of the mold and opening the mold, the core mold 2 is rotated so that the molding space 3 side faces downward, and is moved downward as it is, and at least the molding space 3 side is heated as shown in the drawing. It is immersed in a heating medium 5 such as heating oil stored in 4 to heat the entire molding space 3 side to the melting temperature of the raw material particles or higher. Next, the core mold 2 is moved in the opposite direction to close the mold with a required gap left between the core mold 2 and the cavity mold 1 as shown in FIG. After that, raw material particles are filled from a raw material filling feeder 6 provided on the cavity mold 1 side into a molding space 3 formed between the pair of cavity mold 1 and the core mold 2. At this time, the molding space 3 of the core mold 2
The raw material particles in contact with the side are heated and melted and fused with the raw material particles behind. Then, after the pair of cavity mold 1 and core mold 2 are completely closed, the core mold 2 heated by the heating medium 5 such as heating oil is cooled by supplying cooling water to the heating chamber 8 behind. . In this way, the raw material particles are once melted on the molding space 3 side of the core mold 2 to form a solidified resin coating again. Next, steam is supplied to the heating chamber 7 behind the cavity mold 1 to heat it, and the raw material particles in the molding space 3 are foamed and fused. After this, the cavity mold 1 is cooled by supplying cooling water to the heating chamber 7 behind it. The molded product molded in this manner is taken out from the molding space 3 by the operation of the mold release pin 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 molded article 10 having the structure in which the raw material particles 12 are foamed and fused and integrated is formed behind this. .

By the way, the core mold 2 to be heated by the heating medium 5 such as the heating oil in the heating tank 4 communicates the molding space 3 side, the heating chamber 8 side and the heating chamber 8 side like a conventional mold. The communication hole is not necessarily provided, but such a communication hole may be provided as long as the heating medium 5 such as the heating oil flowing into the heating chamber 8 can be discharged.

Here, as the expandable synthetic resin synthetic resin raw material particles, a styrene resin represented by polystyrene,
Raw material particles formed from polyolefin resins represented by polyethylene and polypropylene, and various synthetic resins of copolymers can be used.

In these raw material particles, the heating medium 5 such as heating oil is, for example, 185 ° C. or higher, preferably 185 to 185 ° C.
It may be heated to about 200 ° C. Further, in ordinary foam molding, the mold temperature may be set to, for example, about 105 to 110 ° C.

As the heating oil, silicone oil, alkyldiphenyl, wax or the like can be used.

The gap left between the pair of cavity mold 1 and core mold 2 when the raw material particles are filled in the molding space 3 depends on the expansion ratio of the raw material particles and the thickness of the resin coating film to be formed. Normally, when the foaming ratio of the raw material particles is 30 times and a resin film having a thickness of about 0.5 mm is provided on the surface, such a gap may be about 15 mm. This is a large gap compared to the case of the usual cracking filling of about 5 mm,
It can be said that the length of the abutting portion formed between the pair of cavity mold 1 and the core mold 2 is preferably set to be larger than that in the normal foam molding.

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 heating 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 heating tank 4 is arranged so as to correspond to the lateral position of the mold 2 while the mold is opened. Then, here, after the pair of the cavity mold 1 and the core mold 2 are retracted above the cavity mold 1 to open the mold, the pair of the cavity mold 1 and the core mold 2 The heating bath 4 is moved in between, and then the core die 2 is moved downward or the heating bath 4 is moved upward to heat the core die 2.

In the illustrated embodiment, after a pair of cavity mold 1 and core mold 2 are closed with a required gap left therebetween, non-foaming synthetic resin powder, flakes, pellets, etc. are placed in the molding space 3. Is supplied to melt the core resin 2 on the molding space 3 side of the core mold 2, and then the remaining raw resin not adhered thereto is discharged to the outside, and then the foam molding is performed as described above. It is also possible to do so.

As described above, in the case of forming the resin coating from the raw resin in the form of powder, flakes, pellets or the like of the non-foaming synthetic resin in the molding process, as shown in FIG.
It is appropriately considered to dispose a resin tank in which a molding raw material 14 containing a raw material resin or raw material particles is stored inside at the side of FIG. In this case, the resin tank 13 may be arranged on the side of the heating tank 4 shown in FIG. Then, here, after the core mold 2 is heated in the heating tank 4, the molding space 3 side of the core mold 2 is brought into contact with the molding raw material 14 in the resin tank 13.

In addition to the illustrated embodiment, ordinary foam molding can be carried out by setting the heating temperature of the heating medium 5 such as heating oil to be equal to or lower than the melting temperature of the raw material particles.

Similarly, the cavity mold 1 can be heated by a heating medium 5 such as heating oil. In this case, a molded product having a resin coating on the entire surface is molded.

Further, a part of the cavity mold 1 or the core mold 2 can be heated by a heating medium 5 such as heating oil.

As the heating medium 5, a liquid one such as heating oil or a gaseous one such as steam can be used.

[0026]

As described above, in the method for molding a foamed synthetic resin molded article according to the present invention, a molded article having a resin coating film formed by heating and melting the molding raw material in at least a part of the surface of the molded article, Molding is possible with a simple device and simple operation. Further, the heating medium for heating one of the molds effectively acts as a release agent for releasing the molded product after molding.

[Brief description of drawings]

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

FIG. 6 is an explanatory view showing the outline of an example in which a resin tank is further provided on the side of the heating tank.

[Explanation of symbols]

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

Claims (3)

[Claims] 1. An in-mold foam molding mold composed of a pair of molds, which is capable of contacting at least a molding space side with a heating medium staying in a heating tank after opening one mold. Prior to foam molding of a foamed synthetic resin molded product, the mold is opened, at least the molding space side of one mold is heated with a heating medium staying in the heating tank, and then the mold is closed, A method for molding a foamed synthetic resin molded article, which comprises filling foamable synthetic resin raw material particles into a molding space to foam-mold a molded article. 2. The foamed synthetic resin molding according to claim 1, wherein the heating medium is heated to a temperature equal to or higher than the melting temperature of the expandable synthetic resin raw material particles, and the molding space side of one mold is heated to a temperature equal to or higher than the melting temperature of the raw material particles. Molding method. 3. After filling the expandable synthetic resin raw material particles into the molding space, one mold heated with a heating medium is cooled,
Next, the method for molding a foamed synthetic resin molded article according to claim 1, wherein the other mold is heated.