JPH06166114A - Molding method for foamed body with skin - Google Patents

Abstract

PURPOSE:To foam uniformly filled foaming beads in the molding method for a foamed body with skin by using the foaming beads. CONSTITUTION:A parison 2 is lowered and fed into a blow molding die 5 and blow molded to form a hollow molded body. Then, foaming beads 3 foamed preliminarily are filled into the hollow molded body before the hollow molded body is cooled and solidified, and the foaming beads 3 are heated and fusion bonded by hot water vapor to mold a foamed body with skin. In the molding method, two pipes 8 and 9 are inserted into the hollow molded body, and hot water vapor is fed from one pipe 8 and exhausted out of the other pipe 9, and the hot water vapor is prevailing all over the foaming beads 3 smoothly to foam the foaming beads 3 uniformly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a foam with skin.

[0002]

2. Description of the Related Art As is well known, foamed plastics (also simply referred to as foams) are used in a wide range of applications such as heat insulating materials, sound absorbing materials, floats, etc. The "molded foam molding method" is known. This mold foam molding method is a method in which pre-expanded resin particles are placed in a mold, and heated steam is blown into the mold to heat and fuse it (see, for example, Japanese Patent Publication No. 3-56905).

On the other hand, there is known a foam with a skin in which the surface of a thermoplastic resin foam is dense (for example, Japanese Patent Publication No. 42-42).
No. 10752). This is, for example, a hollow non-foamed body filled with pre-foamed resin particles for foaming. With the appearance of the foamed body with skin, the foamed plastic has further expanded its applications.

A method for molding such a foam with skin will be described. The non-foaming parison that constitutes the skin is blow-molded in a blow mold and then cooled and solidified into a hollow body, which is blown.
Take out from the mold, put pre-expanded resin particles (hereinafter sometimes simply referred to as foam beads) into the hollow body, and further,
Insert a heated steam injection pipe into this, blow heated steam from this injection pipe to heat the foam beads, further foam, and remove the injection pipe before the beads are fused to each other. Therefore, a method for producing a foam with skin is known (for example, Japanese Patent Publication No. 62-19239,
JP-B-58-10217, JP-B-62-9073
No.

However, in such a method for molding a foam with skin, 1) since the hollow body and the foam in the hollow body are molded in separate steps, separate equipment such as a mold is required. Becomes complicated. In particular, since the cooling and solidifying time of the hollow body and the heating / fusion of the foam beads and the cooling and solidifying time are separately required, the productivity is deteriorated. 2) The foamed beads are cooled on the cooled hollow body. Since the molding is carried out by inserting the mold, there is a problem that the hollow body and the foamed body are not completely fused.

In order to solve such a problem, a reaction system foaming liquid such as urethane is injected into the parison forming the hollow body while the parison forming the hollow body is kept sealed in the blow mold, and the parison is blown into the inner surface of the blow mold. Has been proposed, a method is proposed in which the parison is cooled and solidified in the mold clamped state, and the foam material is reactively solidified to obtain a foam with skin (for example, Japanese Patent Publication No. 58-10217, Kaihei 3-
29311).

In the proposed foam molding method, however, since the parison is blow-molded along the inner surface of the mold by the foaming pressure of the foam material, the parison blow pressure tends to be insufficient. Therefore, there was a problem that the parison could not be sufficiently followed especially for a complicated inner surface shape, and the expansion ratio of the parison was not uniform.

On the other hand, after putting the heated parison into the blow molding die and closing the die, the blow molding air is blown and the foam beads are pneumatically fed to fill the blow parison. There has been proposed a method for molding a foamed body with a skin, in which the foamed beads are foamed by the heat of a parison to mold a foamed molded body (see JP-A-59-145125).

However, in the proposed foam molding method, since the heat of the parison is used for foaming the foam beads, the foaming is not carried out uniformly, and thus the quality of the foam with skin is deteriorated. There was a problem.

Therefore, the inventors of the present invention have combined a mold for performing ordinary blow molding with a mold for performing foam molding of a mold,
Ordinary blow molding of a parison into a hollow body, foam beads are placed in the molded hollow body, and heated steam is supplied from a pipe inserted into the hollow body to enable uniform foaming of the foam beads. And a method for molding a foam with a skin that shortens the molding cycle as much as possible (Japanese Patent Application No. 3-252111).
No.) was found.

The present invention has been made on the basis of such findings, but even in this method, since the skin is not formed when the foam beads are heated and fused, they are different from those in ordinary foam molding. There is an unsolved problem that it is not possible to heat the entire surface of the mold and heating is performed from the pipe inserted into the hollow body, so that the foam beads cannot be sufficiently fused.

[0012]

Therefore, the present invention has been made to solve such an unsolved problem, and the gist of the present invention is to provide a blow molding die in the die. The suspended parison is blow-molded to form a hollow molded body, and subsequently, before the hollow molded body is cooled and solidified, the hollow molded body is filled with thermoplastic pre-expanded resin particles and the particles are heated. In a method for molding a foam with skin, which is formed by fusion bonding to form a foamed molded body, the heating is performed by supplying heated steam from one of the pipes by at least two pipes inserted into the hollow molded body, The method is for forming a foam with a skin, which is performed while exhausting air from the other pipe.

[0013]

EXAMPLES An example of a molding apparatus that can be used in the present invention will be illustrated below with reference to the drawings.

In FIGS. 1 to 4, 5 is a blow molding die (one split die shown with the other of the blow molding die consisting of a pair of split dies removed). Is blow
It is shown in a sectional view along a parting line of the molding die 5. Further, 4 is a parison extruder installed above the blow molding die 5. The parison extruder 4
The desired resin is heated and melted to form parison 2 and blown.
It can be supplied to the molding die 5.

Below the blow molding die 5, pipes 8 and 9 and a filling feeder 7 are provided on the parting line of the blow molding die 5 in the guide grooves 8a and 9a. , And 7a are installed so that their tips can slide in and out of the blow molding die 5, respectively. The other ends of the pipes 8 and 9 and the filling feeder 7 are fixed to a mount 6 that can be moved up and down with the filling feeder 7 as the center. The mounting base 6 is provided with an elevating device 11 and the like on its legs 10 so as to be movable up and down, and the pipes 8 and 9 and the filling feeder 7 are provided.
Is designed to be able to move in and out of the blow molding die 5.
A rack and pinion mechanism, a servo motor mechanism, an air or hydraulic cylinder lifting mechanism, etc. are used for the lifting device 11.

When the mounting base 6 is moved forward, the pipes 8 and 9 penetrate deeply into the blow molding die 5 to a certain degree so that air or the like can be uniformly blown, and the filling feeder 7 is inserted.
Touches or approaches the inner wall surface of the blow molding die 5,
Alternatively, the lengths of the pipes 8 and 9 and the length of the filling feeder 7 are provided so as to be slightly protruded.

The figure shows an example in which two pipes are provided, but in the case of molding a large product, more pipes may be provided.

The pipes 8 and 9 each have a diameter smaller than that of the foam bead 3 and have open ends, and a plurality of pores or slits 8 "and 9" having the same size on the side walls thereof. A perforated pipe or a pipe having its tip closed 8 ', 9', etc. is used. Further, these pipes are configured to be expandable and contractible to control the vertical positions of the pores or slits 8 ", 9". You may do it.

These pipes 8 and 9 are blown with blow molding air, the vacuum in the hollow molded body before and / or during the filling of the foam beads 3 and the heating of the foam beads 3 are carried out. The air source 18 and the heating steam source are supplied through the pressure reducing valve 23 and the blower air pipe 19, and also serve as the supply of the steam and the exhaust during the supply of the heating steam, which will be described later, and the function of the vacuum and the vacuum during cooling. 20, the vacuum device 21, and the drain pipe 25 are valves 22, 22, 2 respectively.
, 2, ..., but the pipes may of course be provided separately according to each application.

The filling feeder 7 communicates with an inlet 12 for introducing the foam beads 3 and an air source 18, and the foam beads
And an inlet 12 for filling the blow mold 3 into the blow molding die 5 by air pressure feeding.
And a piston type valve 14 for opening and closing the air injector port 13. And this inlet 12
A bead storage box 15 is communicated with this via a flexible pipe 16. In this beads storage box 15,
Pressurizing device 17 for effectively filling the foam beads 3
Is provided.

Reference numeral 24 is an upper corner of the blow molding die 5.
It is a needle pin having a hole smaller than the diameter of the foam bead 3 provided in the portion.

A method of molding the foam with skin of the present invention using the above apparatus will be described below with reference to FIGS.

The parison 2 (for example, 180 to 220 ° C. for polypropylene type resin and 160 to 200 ° C. for polyethylene type resin) heated and melted is opened from the extruder 4 arranged above the blow molding die 5. It is extruded and supplied to the mold 5. At this time, the mold 5 is set to 40 to 80 ° C. (see FIG. 2).

After or before supplying the parison 2 to the mold 5, the mounting table 6 is raised to insert the filling feeder 7 and the pipes 8 and 9 into the parison 2. When the supply of the parison 2 is completed, the mold 5 is closed and the parison 2 is sealed. Next, each valve 22 of the blow air pipes 19 and 19 is opened, and air having a pressure of ^{2 to} 7 kg / cm ² (gauge pressure) is supplied from the air source 18 through the pressure reducing valve 23 to the pipes 8 and 9 to 10. It is blown into the parison 2 for 20 seconds to blow the parison 2 to mold the hollow molded body 2a.

Thereafter, the valves 22 of the blow air pipes 19 and 19 are closed, the piston type valve 14 is opened during the cooling of the hollow molded body 2a, and the air is supplied from the air source 18 to the air injector port 13. Then, the foam beads 3 are pneumatically fed to the hollow molding 2a through the inlet 12 (see FIG. 3).

At the time of filling the foam beads 3, a large deformation is applied to the foam beads 3 by using a pressurizing device 17 attached to the beads storage box 15 in order to improve the filling efficiency. It may be filled by pressurizing to a pressure not exceeding 0.5 to ³ kg / cm ² , preferably 0.8 to 1.2 kg / cm ² (gauge pressure).

When the foam beads 3 are filled, the valves 22 of the drain pipes 25, 25 are opened before and during the filling of the foam beads 3 into the hollow molded body 2a. And / or by making a hole in the hollow molded body 2a molded by the needle pins 24, 24 to open the inside of the hollow molded body 2a to the atmosphere, open each valve 22 of the vacuum devices 21, 21, and Alternatively, the inside of the hollow body 2a may be vacuumed by inserting the needle pins 24, 24 connected to a vacuum device (not shown) into the hollow body 2a. This needle pin 24
In addition to the upper corner portion of the blow molding die 5,
It can be provided at an appropriate place, and it is particularly effective to provide it at a position facing the filling direction of the filling feeder 7.

Next, each valve is closed, one valve 22 of the heated steam source 20 is opened, and the pipe 8 connected to this is opened.
0.1 to 1.2 in the filled foam beads 3 using
kg / cm ^2, preferably 0.8~1.0kg / cm ² (gate - di pressure), i.e. blowing heated water vapor of 115 to 120 ° C. 2 to 20 seconds. As a result, the pre-expanded foam beads 3 are further foamed and fused with each other to form a foam molded body. At this time, the other pipe 9 is exhausted, that is, opened to the atmosphere or vacuumed. As a result, the flow of heated steam in the filled foam beads 3 becomes smooth, and heating and fusion are sufficiently performed. Furthermore, depending on the shape of the foam with skin to be molded, the pipes 8 and 9 may be alternately communicated with the heating steam source 20 and the vacuum device 21 at regular intervals.

After that, the molded skinned foam is cooled. As the cooling method, a conventional cooling method from a mold, a method of sucking condensed water by vacuuming from the pipes 8 and 9 through the vacuum devices 21 and 21, or a combination thereof may be used.

Finally, the mount 6 is lowered and the filling
The duct 7 and the pipes 8 and 9 are pulled out, the blow molding die 5 is opened, and the foamed body 1 with leather as a product is taken out (see FIG. 4).

The skinned foam 1 according to this embodiment comprises a hollow molded body 2a made of polyolefin resin such as polyethylene and polypropylene, polystyrene resin, polyvinyl chloride resin, ABS resin and the like, and a diameter of about 1 ^{mm to} 3 ^mm. The foamed molded article is obtained by heating and fusing pre-expanded resin particles 3 such as polystyrene type or polyethylene type.

[0032]

According to the present invention, since the mold for blow molding and the mold for mold foam molding are combined into one mold, the molding process becomes one step, the molding apparatus is simplified, and the equipment cost is reduced. Not only can it be cheaper, but the production cost of the foam with skin can be reduced, and since heated steam is supplied from one pipe and exhausted from the other pipe, the heated steam smoothly flows in the foam beads. The foam beads can be uniformly foamed to obtain a sufficiently fused product, and the molding cycle can be shortened.

[Brief description of drawings]

FIG. 1 is a sectional view taken along a parting line of a mold in an example of an apparatus used in the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the foam with skin of the present invention.

FIG. 3 is a cross-sectional view showing a manufacturing process of the foam with skin of the present invention.

FIG. 4 is a cross-sectional view showing a manufacturing process of the foam with skin of the present invention.

[Explanation of symbols]

1 ... Foam with skin, 2 ... Parison, 2a ... Hollow molded body,
3 ... Thermoplastic pre-expanded resin particles, 5 ... Blow molding die, 7 ... Filling feeder, 8, 9 ... Pipe, 20 ... Heating steam source, 21 ... Vacuum device, 22 ... Valve, 25 ...
Drain pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Yamaji, Inventor Hiroyuki Yamaji, 1000, Kawajiri-cho, Yokkaichi-shi, Mie Mitsubishi Petrochemical Vardeche Co., Ltd. No. 6-1 Sanko Sogyo Co., Ltd. (72) Inventor Yoshiyuki Shida No. 86-1, Minamiyokkamachi, Sanjo City, Niigata Sanko Sogyo Co., Ltd. (72) Inventor Atsushi Tamura Shinagawa-ku, Tokyo 1-14, Gotanda Aron Kasei Co., Ltd. (72) Inventor Kitaoka Takumi 1-14, Higashi-Gotanda, Shinagawa-ku, Tokyo 1-14 Aron Kasei Co., Ltd. (72) Takashi Obama 1 Higashi-Gotanda, Shinagawa-ku, Tokyo 14-chome Aron Kasei Co., Ltd. Inside the company

Claims (1)

[Claims] 1. In a blow molding die, a parison suspended in the die is blow molded to form a hollow molded body, and subsequently, before the hollow molded body is cooled and solidified, A method for forming a foam with skin, comprising filling thermoplastic pre-expanded resin particles in the hollow molded body, heating and fusing the particles to form a foamed molded body, wherein the heating is inserted into the hollow molded body. A method for molding a foam with a skin, characterized in that heating steam is supplied from one of the at least two pipes and exhausted from the other pipe.