JPH0970845A - Integral molding of foam having resin piping built therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily mold a foamed resin integrally molded product having resin piping built therein. SOLUTION: In producing a foam molded object having resin piping P built therein, the resin piping P to be built in is arranged in a foaming mold (cavity 30) for foaming foamable resin particles and the mold is filled with a foamable resin and a cooling medium such as water is continuously discharged to the inner surface of the resin piping P from a cooling medium discharge pipe 40 to perform foam molding while forcibly cooling the resin piping P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for integrally molding a resin-made foam having a built-in pipe, and more particularly to a foam having a through hole defined by a tubular member as a strength material used as a common pipe for communication cables and the like. The present invention relates to an integral molding method capable of easily integrally molding a resin molded body by using a resin pipe as a tubular member. The resin-made pipe-containing foam produced by the method of the present invention is particularly effectively used as a protective pipe for various pipes and wiring such as water pipes and gas pipes buried in the ground, power lines and communication cables. To be

[0002]

2. Description of the Related Art In the case of producing a foamed resin molding having a through hole defined by a tubular member as a strength material as described above, a through hole is conventionally formed in a foamed molded article by a suitable means. Either drilling and inserting a tubular member into it,
Form a concave groove for arranging the tubular member in the foam molded product,
After arranging a tubular member there, two foam-molded articles were superposed and integrated. Since such a method has a large number of work steps and the work is complicated, recently, a cylindrical member is arranged in a molding die and foamable resin particles such as expanded polystyrene are filled in the mold. An integral molding method for performing foam molding (bead molding) is being studied.

[0003]

In foam molding, the inside of the cavity of the molding die is exposed to high temperature and high pressure depending on the temperature and pressure of the supplied steam and the foaming pressure of the expandable resin particles. Therefore, when a tubular member is placed in a molding die and foaming integral molding is performed, if a material that can withstand the temperature and pressure during molding, such as a metal tube, causes a particular problem. However, since the resin pipe material lacks pressure resistance at high temperatures and is easily deformed, it is necessary to take some measures to prevent deformation.

As one of the related techniques, a hollow molded article having a hollow portion inside is mounted in a foam molding die, and then expanded polystyrene resin particles are filled and heat-foamed to mold the foam molded article. In the method of integrally molding a foamed molded product and a hollow molded product, a pressurized fluid (gas or liquid) is applied to the hollow molded product in order to prevent the hollow molded product from being deformed by heating and pressure during molding. A molding method has been proposed in which injection is performed and the cavity is pressurized (Japanese Patent Application Laid-Open No. 62-167030).

In order to apply this method to an integral molding method of a foamed resin molding having a through hole defined by a tubular member, in order to maintain a predetermined pressure inside the resinous pipe which is the tubular member. It is necessary to seal both ends, and also a seal between the end of the pipe and the inner surface of the cavity so that the high pressure formed inside the resin pipe does not affect the molding pressure inside the cavity. Will be needed. Since such a sealing or sealing means is required in addition to the use of the pressurizing means, the method for producing the foam integrally molded product having the tubular pipes having the both ends open requires a lot of man-hours and a high cost. Become. As another related technique, a method of filling the hollow molded article with a non-compressible medium having fire resistance instead of a pressurized fluid has been proposed (Japanese Patent Laid-Open No. 5-237590).
Issue). Even in this case, it is necessary to close both ends of the tubular member, and the special work of uniformly filling the incompressible medium is required, so that a special product with high added value is manufactured. Even if the method is highly effective, it is inevitable that the cost will be high as a method for producing a foam integrally molded product having a tubular pipe with both ends open.

[0006] As still another related technique, a steam made of iron having a large number of openings throughout the entire length of the resin pipe is made to pass through a resin pipe having a large number of pores in styrene filled in a molding die. There has been proposed a method for producing a float in which a pipe is arranged and styrene is foamed by the steam ejected from the steam pipe (JP-A-49-24786).
Issue). This method is intended to prevent deformation of the resin pipe due to heating and pressure during molding by using an iron steam pipe as an attitude holding material, but it is exposed to high pressure steam ejected from the steam pipe. It is unavoidable that the resin pipe deforms in the direction of diameter reduction, which causes the steam pipe and the resin pipe to partially adhere to each other, resulting in insufficient steam ejection, and at the same time, the steam pipe after foam molding. However, the above method is not always a method for practical use.

Therefore, the present invention is a novel molding method capable of integrally molding a foam molded article having a resin pipe as a through hole at a low cost and without making a large change to a conventional molding die. To provide.

[0008]

In order to solve the above-mentioned problems, the inventors of the present invention repeated many experiments to radiate water, for example, on the inner surface side of the resin pipe arranged in the molding die. When performing foam molding while actively cooling with, the resin pipe may be deformed without pressurizing the inner surface side of the resin pipe with a pressurized fluid or filling the incompressible medium. I found that an integrally molded product that can withstand practical use was obtained. The present invention is based on the above-mentioned perception. Basically, when manufacturing a molded product in which a resin pipe is embedded in a foamed molded product, the built-in resin foam is contained in a foam molding die for foaming resin particles. After arranging the resin pipe to be formed, a foaming resin is filled, and the inner surface of the resin pipe is foam-molded while being forcibly cooled by the flow of the refrigerant.

As the refrigerant, water is most preferable from the viewpoint of cost, but it is not limited to this, and any material capable of radiating the heat quantity of the resin pipe from the inner surface side thereof, such as fluorocarbon and a high latent heat of vaporization of alcohol, can be used. It may be a medium having a gas or a gas such as cooled air. In addition, it is the most preferable mode that the refrigerant is radially discharged from the water discharge pipe inserted into the internal space of the resin pipe toward the inner surface of the resin pipe from the viewpoint of the balance between the ease of configuration and the heat absorption efficiency. , Inserting a tubular body having an outer diameter slightly smaller than the inner diameter of the resin pipe, and by appropriate means, to supply cooling water to the annular space between the inner surface of the resin pipe and the outer surface of the tubular body. It may be supplied.

The amount of refrigerant to be supplied depends on the type of resin in the resin pipe to be built in, the pipe diameter and wall thickness, the steam temperature and pressure to be supplied, the foaming pressure in the cavity, etc. Although determined experimentally accordingly, it is necessary that at least the temperature of the resin pipe during foam molding be maintained below the softening temperature of the resin. Therefore, the present invention is applicable to a resin pipe having mechanical strength that cannot withstand the pressure in the cavity expected at the time of foam molding at room temperature (this depends on the resin material or the pipe diameter, wall thickness, etc.). It will be understood that it is not done.

In other words, the present invention is not applicable to a manufacturing method for manufacturing a molded product in which a resin-made pipe having mechanical strength capable of withstanding the pressure in the cavity generated at the time of foam molding at room temperature is incorporated. All are applicable, and the type of foam molding resin and the type of resin of the resin pipe are arbitrary, provided that the conditions are complied with. The number of resin pipes arranged in the foaming mold may be one or plural. In the case of arranging a plurality of refrigerants, a refrigerant discharge pipe for supplying a refrigerant to each of them is inserted. Further, a jig for positioning the resin pipe at a predetermined position in the foam molding die may be used. The jig may be removed from the molding die after the resin pipe is arranged, or may be left in the die and integrally molded if the integrally molded product to be molded permits. In the latter case, an integrally molded product having stable strength can be obtained by using the same material as the foaming resin as the molding material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The method for integrally molding a resin-made pipe-containing foam according to the present invention will be described below in more detail with reference to the preferred embodiments. FIG. 1 is a cross-sectional view illustrating one embodiment for carrying out the method of the present invention, and FIG. 2 is a perspective view showing the inside of the cavity of the foam molding apparatus at that time.

The foam molding apparatus shown is known in the art except that it has an opening for inserting a water discharge pipe, which will be described later. That is, the foam molding device has a female mold 10 and a male mold 20, and the steam holes 12,
A molding female Naka mold 11 and a molding male Naka mold 22 having 25 are arranged. A molding steam introducing port 13 is formed on one side wall side of the female mold 10 and a drain port 14 is formed on the other side wall side of the female mold 10, and the thermoplastic resin is formed so as to penetrate the side wall and the female Naka mold for molding 11. A feeder 15 is arranged for the supply of pre-expanded particles. The male die 20 is also provided with a forming steam introducing port 23 on one end side and a drain port 2 on the other end side.
4 is formed. Reference numeral 16 is a support rod for preventing deformation of the molding Naka mold due to molding pressure during foam molding.
Then, as shown in FIG. 1, the female mold 10 and the male mold 2 are formed at the time of molding.
By molding 0 and 0, a cavity 30 is formed by the molding female Naka mold 11 and the molding male Naka mold 22, and foam molding is performed in the cavity 30.

In carrying out the method of the present invention in such a conventionally known foam molding apparatus, two communication holes 31a, 31b are formed in the side wall portion of the female mold 10 for communicating the space inside the cavity 30 with the outside of the mold. Is formed. Then, the communication holes 31a and 31b are provided with the pipes 32a and 32b reaching from the side wall portion of the female die 10 to the side wall portion of the female molding die 11, thereby forming a space inside the female die which is a forming steam supply chamber. And are partitioned.

When molding the resin-made pipe-containing foam using the foam molding apparatus described above, with the mold open,
The resin pipe P to be incorporated is arranged so that the communication holes 31a and 31b are located inside the open both ends. At that time, the length of the resin pipe P to be built in is substantially the same as the width of the molding female Naka die 11, and both open ends of the resin pipe P are on the inner surface of the molding female Naka die 11. To be able to work closely. When the length of the resin pipe P is shorter than the width of the female molding die 11 for molding, sealing is performed so that no gap is formed between the open end of the resin pipe P and the inner surface of the female molding die 11 for molding. Take steps. For example, it is effective to prepare a thin resin or metal vip in advance and to insert it into the gap between the resin pipe P and the molding female mold 11 by the thickness of the gap. .

After arranging the resin pipe P to be built in the molding female mold 11, the female mold 10 and the male mold 20 are clamped in accordance with a usual method, and the thermoplastic resin is fed from the feeder 15 to the mold. Supply pre-expanded particles. In the method of the present invention, in the method of the present invention, the pre-expanded thermoplastic resin particles supplied in this state are subjected to a normal forming operation such as a heating process. The supply of the refrigerant is started toward the inner surface of the resin pipe P arranged at.

That is, in this embodiment, after the mold is clamped, it has a length reaching almost the entire length of the arranged resin pipe P from the communicating hole 31a, which is preferably located above, and a large number of resin pipes P are arranged around the communicating hole 31a. Water discharge pipe 4 with a water ejection hole 4
0 is inserted. The water discharge pipe 40 is connected to a cooling water supply source (not shown) via a hose 41, and by opening a valve (not shown), the water from the cooling water supply source is arranged from the ejection hole of the water discharge pipe 40. It is discharged toward the inner peripheral surface of the resin pipe P. If necessary, interpose a water supply pump and discharge it as pressurized water.

From the start of the supply of high-pressure steam to the end of foam molding, cooling water is continuously discharged from the water discharge pipe 40, preferably until the mold is opened. The released water absorbs the heat of the resin pipe P, flows down, and flows out of the mold through the communication hole 31b below. The temperature rise of the resin pipe P is suppressed by the heat absorption of water, and the deformation is prevented. Since the heat absorption amount changes depending on the amount of water discharged (that is, the amount of water flowing down in contact with the inner surface of the resin pipe P), the resin pipe can be changed by the temperature and molding pressure in the cavity 30 under given foam molding conditions. A water discharge pipe 40 supplies an amount of water that does not deform P.

After the foam molding for a predetermined time, the discharge of the cooling water from the water discharge pipe 40 is stopped, the cooling process is performed, and the mold is opened, so that the resin pipe P and the thermoplastic resin reserve are arranged. It is possible to obtain a foam-molded article that is integrated with the foam of the foam particles. In the above example, one straight pipe is described as an example of the resin pipe P to be incorporated, but it is also possible to simultaneously incorporate and mold a plurality of resin pipes P. At that time, the number of the communication holes 31 corresponding to the position and the number of the resin pipes P to be arranged are formed in the female mold 10, and the water discharge pipes 40 are inserted into the respective communication holes 31 for cooling.
Further, the resin pipe P does not need to be a straight pipe,
It may be a curved pipe. In that case, the communication hole 31 is formed at a position where both open ends of the curved pipe are located, and the water discharge pipe 40 also has a shape capable of passing through the curved resin pipe P. Things are used.

Instead of inserting the water discharge pipe 40, as shown in FIG. 3, a cylindrical body 45 having an outer diameter somewhat smaller than the inner diameter of the resin pipe P and having its upper end closed is provided in the resin pipe P. Alternatively, the water may be discharged from the water discharge pipe 46 so that the water flows down in the annular space Sa formed therein. The material of the cylindrical body 45 is arbitrary.

[0021]

EXAMPLE A resin-made foam with a built-in pipe was manufactured using the foam molding apparatus of the form shown in FIG. The cavity 30 in the state of being matched with each other had a size of 400 × 300 × 100 (mm). The resin pipe P was made of vinyl chloride having an outer diameter of 60 mm and a wall thickness of 4.5 mm, and its length was 300 mm, which was the same as the width of the cavity 30. After opening the mold and arranging the resin pipe P at a predetermined position, the mold is closed, and eslen beads (product name of Sekisui Plastics Co., Ltd., foaming ratio: 50 times) are cavities from the feeder 15 as pre-expanded particles. Filled in 30.

The water discharge pipe 40 has an inner diameter of 20 m with one end closed.
1,500 m diameter copper pipe with 1,500 mm spout holes
Pieces / m²The one drilled in 1. was used. The other end of the water discharge pipe 40
Was connected to a water tank via a pump. Connect the water discharge pipe 40
After inserting the resin pipe P through the through hole 31a,
In the state of operating and continuously contacting the inner surface of the resin pipe P
Water release started. In that state, the steam introduction of the female mold 10
Water vapor from the mouth 13 (vapor pressure 0.8 kg / cm²・ G, warm
Temperature (105 ° C) for 10 seconds into the cavity 30 and then
From the steam inlet 23 of the male die 20, steam (vapor pressure
0.4 kg / cm ²・ G, temperature 100 ℃) for 20 seconds
After entering, steam (vapor pressure of 0.
8kg / cm²・ G, temperature 105 ° C) in molding chamber 30
Introduced for 15 seconds.

Next, after cooling water was introduced from both inlets 13 and 23 to cool it, the mold was opened to obtain an in-mold foam molded article.
When this molded product was visually observed, no deformation of the resin pipe P was observed, and the resin pipe P and the foamed resin were in good contact. Comparative Example Molding was performed under the same conditions as in Example 1 except that water was not discharged from the water discharge pipe 40. This molded body was greatly deformed by the foaming pressure so that the PVC pipe could not be provided with a communication cable or the like.

[0024]

According to the present invention, it is possible to obtain a foam-molded article in which resin pipes are integrally built in relatively easily and at low cost.

[Brief description of drawings]

FIG. 1 is a diagram illustrating one mode for carrying out the method of the present invention.

FIG. 2 is a perspective view of the inside of a cavity illustrating one embodiment for carrying out the method of the present invention.

FIG. 3 is a diagram illustrating another mode for carrying out the method of the present invention.

[Explanation of symbols]

10 ... Female mold, 20 ... Male mold, 11 ... Female molding mold, 22
... Female Naka mold for molding, 30 ... Cavity, 31a, b ... Communication hole, 40 ... Water (refrigerant) discharge pipe, 41 ... Hose.

Claims (2)

[Claims] 1. When producing a molded product in which a resin pipe is embedded in a foam molded product, after arranging the resin pipe to be incorporated in a foam molding die for foaming expandable resin particles, A method for integrally molding a foam made of a resin-made pipe, which comprises filling a foamable resin and performing foaming while forcibly cooling the inner cylindrical surface of the resin-made pipe with a refrigerant. 2. The integral molding of a resin-made pipe-equipped foam according to claim 1, wherein forced cooling with a refrigerant is performed by cooling water discharged from a water discharge pipe inserted into the internal space of the resin pipe. Method.