JP2001138385A - Method for manufacturing composite foamed resin molding with skin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a composite foamed resin molding by which it is possible to dispense with an operation to fill a parison with prefoamed particles and various kinds of accompanying steps and also with an operation to fill up numerous open holes and further, it is easy to prepare a good-looking composite foamed resin molding with a skin using a simple device. SOLUTION: A foamed molding 4 of a thermoplastic resin which is previously formed is set between the split halves of a mold 1, then a parison 2 made up of the thermoplastic resin is suspended, covering the foamed molding 4, between the split halves of the mold 1, and the split halves are closed wrapping the periphery of the foamed molding 4 before the hardening of the parison 2 by cooling. Finally the foamed molding 4 and the parison 2 are joined together and molded in one piece. During molding, the gap between, e.g. the parison 2 and the inner wall face of the split halves of the mold 1 is vacuumized to vacuum-mold the parison 2, and thus the parison 2 is shaped to the inner configuration of the split halves of the mold 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite foamed resin molded article having a skin, which has high strength, light weight and heat insulation.

[0002]

2. Description of the Related Art Conventionally, as a method of molding a composite foamed resin molded article having a skin, a hollow parison, which is suspended in the split mold, is blow-molded in a split mold for blow molding to form a hollow molded article. None. 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 and fused, and then the hollow molded body is vacuumed. There is a method of molding by cooling and solidifying (for example, see JP-A-6-166095).

[0003]

However, in the above molding method, in the case of a thin product having a total thickness of 20 mm or less,
The thermoplastic pre-expanded resin particles (hereinafter referred to as pre-expanded particles) cannot be completely filled in the hollow molded body. Therefore, there is a problem that a cavity is generated inside the composite foamed resin molded article with a skin.

In addition, the parison is filled with the pre-expanded particles, the filling air is exhausted when the pre-expanded particles are filled, the pre-expanded particles are heated and cooled, and the condensed water of the heating steam is discharged. , Supply pipe, drain pipe,
Requires compressors, boiler equipment, etc. Therefore, the method of manufacturing the composite foamed resin molded article with the skin is complicated, and a complicated and large-sized apparatus is required.

[0005] Further, the parison needs a filling feeder opening for filling the above-mentioned pre-expanded particles. In addition, to blow the parison to form a hollow molded body, and to exhaust the air in the split mold before and during the filling of the pre-expanded particles, the flow of steam in the split mold during heating is smooth. In order to discharge some steam for cooling and to cool efficiently, to open the divided molds to discharge condensed water and heat, openings for these four working dedicated or shared pipes A hole is required in the parison. Therefore, the surface of the composite foamed resin molded article with a skin has traces of the above-mentioned many opening holes due to these, and the appearance is poor. Therefore, there is a problem that the opening hole must be closed by a post-processing. As mentioned above,
In the conventional method of manufacturing a composite foamed resin molded article with a skin, the manufacturing method and apparatus are complicated.

The present invention has been made in view of the above-mentioned conventional problems, and does not require filling of the parison with the pre-expanded particles and various operations associated therewith, and operation of filling a large number of opening holes. An object of the present invention is to provide a method for producing a composite foamed resin molded article with a skin, which is simple and excellent in appearance.

[0007]

According to a first aspect of the present invention, a foamed molded body made of a thermoplastic resin formed in advance is set between split molds, and then a thermoplastic resin is formed between the split molds. The parison is hung so as to cover the foam molded body, and then, before the parison is cooled and solidified, the split mold is closed so as to wrap around the foam molded body, and the foam molded body and the parison are joined. A method of integrally molding, wherein the parison is pressed into the inner shape of the split mold by pressing the periphery of the parison with the split mold, thereby producing a composite foamed resin molded article with a skin. Is the way.

The most notable point of the present invention is that the above-mentioned foamed molded article is used as a core material, the foamed molded article is set between divided molds, and then a skin is placed around the divided mold. Then, the parison is dropped, and then pressed by the split mold to obtain a composite foamed resin molded article with a skin.

Next, the operation and effect of the present invention will be described.
First, for example, between a pair of left and right split molds, a foam molded body previously foam-molded using a thermoplastic resin is arranged. Next, a parison extruded using a thermoplastic resin is hung between the split mold and the foamed molded body to cover the periphery of the foamed molded body. Next, the pair of split molds is closed, and the parison is pressed against the outer wall of the foam molded article. As a result, a composite foamed resin molded article with a skin in which the parison is used as the skin and the inner shape of the split mold is formed is obtained.

[0010] As described above, the air temporarily interposed between the parison and the foam molding temporarily expands the parison slightly when pressed by the split mold. As a result, the parison slightly elongates, and the parison is smoothly formed along the inner shape of the split mold, thereby obtaining a composite foamed resin molded article having a beautiful skin. Excess parison remaining above and below the composite foamed resin molded article with skin is cut off.

[0011] As described above, according to the present invention, a foam molded article molded in advance is used as a core material in a composite foamed resin molded article with a skin. Therefore, as in the conventional case, the parison is filled with the pre-expanded particles, the exhaust from the parison at that time, heating and cooling for foaming the pre-expanded particles, supply of steam for the heating, and condensation of the steam. No operation such as drainage of water is required.

Further, pipes, compressors, boiler equipment and the like for these operations are not required. Further, the opening hole used for the above operation is not required. Therefore, these opening holes are not generated in the skin, and a composite foamed resin molded article with a skin having excellent appearance can be obtained. Therefore, according to the present invention, it is not necessary to fill the parison with the pre-expanded particles and to perform various operations associated therewith, and to fill a large number of opening holes. A method for producing a composite foamed resin molded article with a skin can be provided.

Next, the parison is pressed by the split mold around the parison and the space between the parison and the inner wall surface of the split mold is vacuum-formed to form the parison. It is preferable to shape the inner mold of the split mold. In this case, the inner shape of the split mold is closely transferred to the parison and transferred by the vacuum forming. Therefore, it is possible to obtain a foam molded article having a beautiful skin surface and excellent design.

Next, as in the third aspect of the present invention, it is preferable that the parison and the foam molded body are the same type of thermoplastic resin. In this case, the adhesive strength between the parison serving as the skin and the foam molded body serving as the core material is increased.

Examples of the same type of thermoplastic resin combination (parison / foamed molding) in the parison and the foamed molding include the following. Polypropylene resin / foamed polypropylene resin ABS resin / foamed polystyrene resin, foamed ABS resin, or a mixture of these. Polystyrene resin / expanded polystyrene resin, foamed AB
Either S resin or resin mixed with them. Polyethylene resin / foamed polyethylene resin, foamed polystyrene / polyethylene copolymer resin, foamed resin with a two-layer structure composed of polyethylene and a core layer made of various resins. Or any of the resins in which these are mixed. In addition, as the foamed molded product, a polyolefin resin is preferable, and among them, a polypropylene resin is most preferable.

Next, as in the invention of claim 4, the thickness of the foam molded body before molding is Tc, the inner dimension of the split mold is T,
When the thickness of the skin obtained by the parison is Ts and the coefficient is K, the relational expression “Tc = (T−Ts × 2) /
It is preferable to use the foamed molded article having a thickness such that the value of K in “K” is in the range of 0.6 to 1.0.

In this case, a foam molded article having a smooth surface and excellent design can be obtained. That is, the foamed molded article may be thermally contracted by the heat of the parison in the molten state. In order to solve this problem, it is possible to secure in advance a thickness at which the foam molded article is thermally contracted.

When the above K is less than 0.6, the total thickness of the foamed molded article and the parison is too thicker than the inner dimension of the split mold. Prevents finishing. Further, the foamed molded article is similarly compressed and its density becomes higher than required strength, so that the molding cycle becomes longer and the cost may be increased.

On the other hand, when K exceeds 1.0, the total thickness of the foam molded article and the parison is too thin than the inner dimension thickness of the split mold. For this reason, even if the surface of the foamed molded product further foams due to the melting temperature of the parison during molding, a gap may be formed at the interface with the split mold, and “sink” or “dent” may occur on a part of the product surface. There is.

Next, it is preferable that the parison has a thickness of 0.5 to 5.0 mm and the foam molded body has a density of 0.01 to 0.10 g / cm ^3. . In this case, high fusion bonding between the foam molded article and the skin can be achieved, and the weight and heat insulation of the composite foamed resin molded article with the skin can be achieved. Also, recyclability is easy.

When the thickness of the parison is less than 0.5 mm, the strength is reduced and the parison is easily deformed by an external force.
If it exceeds 5.0 mm, it had small irregularities.
It becomes difficult to form a relatively complicated shape, the weight increases, and the cost increases.

On the other hand, when the density of the foamed molded body as the core material is less than 0.01 g / cm ³ , the strength is reduced and the foam is easily deformed by an external force. If it exceeds 0.10 g / cm ³ , the weight increases and the cost increases.

Next, as in the invention of claim 6, the foam molded article has a positioning projection for setting the foam molded article between the split molds, while the foam molded article has a positioning protrusion. It is preferable that a holder for setting the positioning protrusion is provided between them. In this case, the foam molded body serving as the core material can be accurately and easily set at a predetermined position.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A method and an apparatus for manufacturing a composite foamed resin molded article with a skin according to an embodiment of the present invention will be described with reference to FIGS. In manufacturing the composite foamed resin molded article 40 with a skin in this example (FIG. 7), as shown in FIGS.
A foam molded body 4 made of a thermoplastic resin formed in advance is set between a pair of split molds 1 (FIG. 1), and then a parison 2 made of a thermoplastic resin is placed between the split molds 1. It is hung so as to cover the foam molded body 4 (FIG. 2). Next, before the parison 2 is cooled and solidified, the split mold 1 is closed so as to wrap around the foam molded body 4,
The foam molded body 4 and the parison 2 are integrally joined (FIGS. 3 and 4).

At the time of this molding, the periphery of the parison 2 is pressed by the split mold 1 and the space between the parison 2 and the inner wall surface of the split mold 1 is depressurized and vacuum-formed. The parison 2 is shaped into the inner shape of the split mold 1 (FIG. 3).

The foam molded article 4 has a positioning projection 41 for setting the foam molded article between the split molds 1, while below the split mold 1, Holder 15 for setting positioning projection 41
Is provided. Hereinafter, these will be described in detail.

As shown in FIG. 1 to FIG.
Is divided right and left, and a parison extruder die 21 for extruding a parison is provided above the split mold 1. The parison extruder die 21 heats and melts a desired thermoplastic resin to extrude the parison 2 so that the parison 2 can be supplied between the split mold 1 and the foam molding 4.

Below the pair of left and right split molds 1,
Two holders 15 are provided so that the foam molded body 4 serving as the core material does not come into contact with the hanging parison 2 and can be accurately set at a predetermined position between the split molds 1. Further, in order to move the holder 15 up and down, left and right, and back and forth at the opening below the split mold corresponding to the foam molded body 4 having various dimensions and shapes, a rack pinion mechanism capable of fine movement is provided. (Not shown). If a servo motor mechanism and an air or hydraulic cylinder mechanism are used instead, more efficient positioning can be achieved.

The holder 15 has a deep V-shaped 2
The positioning protrusions 41 of the molded foam 4 are inserted into the respective tip holes 150, and the molded foam 4 is erected in the split mold 1. In this example, holder 1
The shape of the tip hole 150 of No. 5 was V-shaped as shown in FIG. 1 so that the foam molded body could be held tighter. Note that the holder 15 has a structure in consideration of the stability due to the shape, size, and weight of the foam molded article. On the other hand, the foam molded body 4 is provided with two positioning projections 41 to be inserted into the distal end holes 150 of the holder 15 and to vertically stand and hold it (FIGS. 5 and 6).

Next, the split mold 1 will be described.
The split mold 1 of this embodiment is divided into a pair of left and right sides. Each split mold 1 has a vacuum (decompressed) air for shaping the parison 2 according to the inner surface shape of the split mold 1. Suction hole 11, suction hole 11 and vacuum device 3
And an open / close valve 31 for connecting the air piping.
In addition, a cooling pipe 10 for cooling and solidifying the parison 2 and the surface melted portion of the foam molded body 4 after vacuum forming is built in the split mold.

The split mold 1 has an inner thickness, that is, as shown in FIG. 1, the length t1 of the contact portion 14 of one split mold 1 and the length of the contact portion 14 of the other split mold 1. The distance from t2 is 20.0 mm. In addition, the left and right split molds 1 have abutment portions 13 and 14 at upper and lower portions that abut outside the vertical position of the foam molded body 4 and close the parison 2.

A method for molding the composite foamed resin molded article 40 with the skin using the above apparatus will be described below with reference to FIGS. First, the two positioning projections 41 of the foam molded body 4 shown in FIGS. 5 and 6 are inserted into the tip holes 150 of the holder 15, and the foam molded body 4 is held in a vertically upright state. Then, it is moved in the vertical and horizontal directions by the rack pinion mechanism that can be finely moved, and the foam molded body 4 is set at a predetermined position at the open portion of the pair of split molds 1 where the parison 2 does not come into contact later. (FIG. 1).

Next, heating is performed from a parison extruder die 21 disposed above the split mold 1 (for example, 180 to 220 ° C. for a polypropylene resin, 1 ° C. for a polyethylene resin).
(60-200 ° C.) The molten parison 2 is extruded into the opened split mold 1 without contacting the foam molded body 4 and supplied until the parison 2 has a length covering the entire outer surface of the foam molded body 4 ( (See FIG. 2).

Next, before the parison 2 is cooled and solidified, the pair of split molds 1 is closed, and the foam molded body 4 and the parison 2 are sealed. At this time, the surface of the foam molded article 4 melts while slightly foaming due to the heat melting heat of the parison 2 and the pressing force at the time of mold clamping. And are integrated as a composite. At the same time, the vacuum between the outer surface of the parison 2 and the split mold 1 is reduced by the vacuum device 3 connected to the air suction hole 11 provided on the inner surface of the split mold 1. As a result, the air between them is exhausted, and the parison 2 is suction-contacted to the inner surface of the split mold, and is shaped along the shape of the split mold (see FIGS. 3 and 4).

At the time of the above molding, the positioning projections 41 are formed on the parting line below the foamed molded body 4.
Are sandwiched between the parisons 2 shown in FIGS. 3 and 4.
As shown in (1), it is pressed by the contact portion 14 at the lower part of the split mold 1. As a result, they are fused and joined in a thin solid state. Therefore, there is no problem in strength and appearance at the parting line. Also,
The parison 2 above the foam molding 4 is fused by the contact portion 13 on the upper part of the split mold 1 (FIGS. 3 and 4).

As shown in FIG. 3, the molded foamed composite foamed resin molded article is cooled and solidified by passing cooling water through a cooling pipe 10 in the split mold 1.
At this time, since the core material is a foam molded article that has been molded in advance, heating by steam is unnecessary, and condensed water is not generated. Therefore, as a cooling method, a conventional cooling method using only a split mold is sufficient. Therefore, there is no need for a step of sucking out condensed water from the inside of the skin. Finally, the split mold 1 is opened to take out the composite foamed resin molded article 40 with a skin, which is a product. The composite foamed resin molded article with a skin 4
Numeral 0, as shown in FIGS. 4 and 7, comprises a foam molded body 4 serving as a core material and a skin 20 covering the periphery thereof and formed by the parison 2. Excess parison remaining above and below the composite foamed resin molded article 40 with the skin is cut off.

Next, the operation and effect of this embodiment will be described. As described above, according to the present embodiment, the foam molded article 4 molded in advance is used as the core material in the composite foamed resin molded article 40 with a skin. Therefore, as in the conventional case, the parison is filled with the pre-expanded particles, the exhaust from the parison at that time, heating and cooling for foaming the pre-expanded particles, supply of steam for the heating, and condensation of the steam. No operation such as drainage of water is required. Further, since the holder 15 is used, the foam molded body 4 serving as a core material can be accurately and easily set at a predetermined position.

Further, pipes, compressors, boiler equipment and the like for these operations are not required. Further, the opening hole used for the above operation is not required. Therefore, these opening holes are not generated in the skin, and a composite foamed resin molded article with a skin having excellent appearance can be obtained. Therefore, according to this example, it is not necessary to fill the parison with the pre-expanded particles and various operations associated therewith, and to fill a large number of opening holes, and it is easy to manufacture, the apparatus is simple, and the appearance is excellent. A method for producing a composite foamed resin molded article with a skin can be provided.

Embodiment 2 As shown in FIG. 8, this embodiment is different from Embodiment 1 in that the corner 17 of the internal shape (cavity) in the split mold is different from that of Embodiment 1.
In this example, an exhaust passage 18 is provided. That is, as shown in the lower left and upper left of FIG.
An exhaust passage 18 penetrating through the inside of the split mold 1 is opened at the corner 17 of the cavity. Exhaust passage 18
Is connected to the vacuum device 5 via a valve 51.

In this embodiment, at the time of the vacuum forming, the valve 51 is opened, and the vacuum device 5 sucks and discharges the air between the parison 2 at the corner 17 and the inner wall of the split mold. Therefore, the shaping at the corner portion 17 can be performed sharply.

That is, from the moment the parison 2 comes into contact with the entire periphery of the parting line of the split mold 1 during the mold clamping process, the air in the space sealed by the split mold 1 and the parison 2 is exhausted. become unable. For this reason, when molded as it is, there are cases where a recess is generated in the skin due to residual air, and it is difficult to obtain a composite foamed resin molded article with a beautiful skin.

For this reason, the exhaust passage 18 is provided in the corner portion 17 where air is particularly likely to stay and the parison is difficult to form, and forced exhaust is performed until the mold clamping is completed. By attracting to the mold side, a more beautiful product can be obtained. Other configurations are the same as those of the first embodiment. Further, the same function and effect as those of the first embodiment can be obtained.

Third Embodiment Next, in the first and second embodiments, the parison 2 serving as the skin is made of a polypropylene resin having a thickness of 3.0 mm, and the foam molded body 4 constituting the core is made of the parison 2. A foamed polypropylene resin having a density of 0.05 g / cm ³ , which is a resin of the same type as that of No. 2, was used.

In the above relational expression, the inner dimension thickness of the split mold (that is, the shortest distance between the inner walls of the left and right split molds 1) is 20.0 mm, and the coefficient K is set to 0. 90
Therefore, the thickness of the foam molded body 4 before molding is
It was 15.6 mm. For this reason, there is no gap or expansion at the interface between the foam molded body 4 and the parison 2, and the two are fused and integrated to form the entire thickness 2.
A composite foamed resin molded article having a skin of 0.0 mm was obtained.

[0045]

According to the present invention, it is not necessary to fill the parison with the pre-expanded particles and to carry out the various operations and the operation of filling a large number of opening holes. An excellent method for producing a composite foamed resin molded article with a skin can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the present invention, in which a split mold and a foam molded body are installed therein.

FIG. 2 is a cross-sectional view illustrating a parison according to the first embodiment when it is suspended.

FIG. 3 is a cross-sectional view showing a vacuum forming and cooling process in the first embodiment.

FIG. 4 is a sectional view showing a product take-out step in the first embodiment.

FIG. 5 is a perspective view of a foam molded article according to the first embodiment.

FIG. 6 is a sectional view taken along line AA of FIG. 5;

FIG. 7 is a cross-sectional perspective view of the composite foamed resin molded article with a skin obtained in the first embodiment.

FIG. 8 is a cross-sectional view of Embodiment 2 when a composite foamed resin molded article with a skin is formed.

[Explanation of symbols]

 1. . . Split mold, 10. . . 10. cooling piping, . . 14. air suction holes, . . Holder, 2. . . Parison, 20. . . 3. parison extruder dies, . . Foam molded article, 3,5. . . Vacuum device, 40. . . Composite foamed resin molded article with skin, 41, 415. . . Positioning projection,

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhide Hattori 653-2, Ryomi, Yokkaichi-shi, Mie F-term in Mitsubishi Chemical Foam Plastic Co., Ltd. (reference) 4F208 AA04 AA11 AD05 AD17 AD18 AG03 AG20 AR12 AR15 LA01 LB01 LB12 LB13 LG01 LG22 LJ01 LJ05 LJ09 LJ22 LJ23 LJ29 LN15

Claims (6)

[Claims] 1. A foam molded article made of a thermoplastic resin molded in advance is set between split molds, and then a parison made of a thermoplastic resin is covered between the split molds to cover the foam molded article. And then, before the parison cools and solidifies, closes the split mold so as to wrap around the foam molded article, and integrally forms the foam molded article and the parison. A method for manufacturing a composite foamed resin molded article with a skin, wherein the parison is shaped into the inner shape of the split mold by pressing the periphery of the parison with the split mold. 2. The parison according to claim 1, wherein the parison is pressed by the split mold while the space between the parison and the inner wall of the split mold is depressurized and vacuum-formed. A method for producing a composite foamed resin molded article with a skin, wherein the molded article is shaped into a shape. 3. The method according to claim 1, wherein the parison and the foamed molded article are thermoplastic resins of the same system. 4. The method according to claim 1, wherein:
The thickness of the foam molded body before molding is Tc, the inner dimension of the split mold is T, the thickness of the skin obtained by the parison is Ts,
And a coefficient K, the relational expression “Tc = (T−Ts
× 2) / K ”, a method for producing a composite foamed resin molded article having a skin, wherein the foamed molded article having a thickness such that the value of K in the range of 0.6 to 1.0 is used. 5. The method according to claim 1, wherein:
A method for producing a composite foamed resin molded article having a skin, wherein the thickness of the parison is 0.5 to 5.0 mm, and the density of the foamed molded article is 0.01 to 0.10 g / cm ³ . 6. The method according to claim 1, wherein:
The foam molded article has a positioning projection for setting the foam molded article between the split molds, and a holder for setting the positioning projection between the split molds. A method for producing a composite foamed resin molded article with a skin, comprising: