JP2710753B2 - Thermoplastic resin bead foam and its surface melt molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for melting the surface of a thermoplastic resin bead foam at the time of bead foam molding or after bead foam molding with a heating plate, a heating mold, or the like, and applying the bead foam pressure or externally. The present invention relates to a thermoplastic resin bead foam capable of forming a non-foamed layer having a constant thickness by pressurization, improving rigidity and decorating the surface, and a method for melt-forming the surface thereof.

[0002]

2. Description of the Related Art A bead foam of a thermoplastic resin is a lightweight material excellent in energy absorption, sound insulation, vibration insulation, heat insulation and the like. Therefore, use in various fields is expected. However, such beads foam conventional thermoplastic resin, the nature of the molding process, is composed of all the foam layer of the whole uniform density throughout the surface portion from the central portion as shown in FIG. 2 , Low surface hardness, lack of scratch resistance, and low rigidity. Also, since it is an aggregate of individual foam beads, and there is a local density difference and voids on the surface, it lacks surface smoothness, and when trying to transfer the foam mold surface to the product, the gap between the beads is small. It was also said that it was difficult to obtain a design surface due to its existence.

[0003]

Therefore, in order to obtain practically satisfactory scratch resistance and rigidity, a member separately formed for a surface layer is used, and in order to obtain a design, a decorative material such as cloth is used. There was a problem that it had to be stuck or covered on the surface. For example, in a cooler box for leisure, in order to obtain scratch resistance inside and outside the box, overall rigidity, and heat insulation, a composite structure of a surface material formed by injection molding or the like and a conventional thermoplastic resin bead foam as a heat insulating material Had become.

[0004] Such a separate member for the surface layer is attached,
It goes without saying that the conventional thermoplastic resin bead foam to be covered increases production costs and material costs.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a member separately molded for a surface layer in order to obtain scratch resistance and rigidity. Another object of the present invention is to provide a thermoplastic resin bead foam which does not require a decorative material such as a cloth to be stuck or covered on the surface in order to obtain a design, and a method for melt-molding the surface of the thermoplastic resin bead.

[0006]

The invention according to claim 1 of the present invention to solve the above object, according to an aspect of includes a foam layer, and the molten layer of the surface, to form formed by melting the surface of the foam layer Thereby, the molten layer is formed of a single material,
By applying the internal pressure and melting the surface, the first molten layer and the second
Thermoplastic bead foam formed from a molten layer
It is.

[0007] The invention according to claim 2 is the first molten layer.
2. A squeezed design such as a genuine leather squeezed pattern is transferred to the stencil.
It is a thermoplastic resin bead foam as described.

[0008] The invention according to claim 3 is characterized in that the high temperature, the low temperature
The temperature of the foaming mold is adjusted to bead foaming
Immediately before the end, the temperature is adjusted to the melting temperature of the beads or higher, and
After the temperature is adjusted to below the melting temperature of the beads,
A molten layer is formed on the surface by the internal pressure due to the foaming force of the beads.
Surface molding of thermoplastic resin beads foam
is there.

[0009]

[0010]

According to the first aspect of the present invention, since the surface of the thermoplastic resin bead is a molten layer, it has relatively good scratch resistance and rigidity and is smooth. Therefore, there is no need to attach or cover a decorative material such as a member or cloth separately molded for the surface layer.

[0011] According to the thermoplastic resin foam of claim 2,
Special process for applying the design, for example,
Eliminates the process of attaching decorative materials to the surface.

According to a third aspect of the present invention , there is provided a method for heating
The surface of the foam layer is melted by the mold
Because it is melt molded, it is used for the surface layer as in the past.
Forming a separate member by attaching the separate member
Eliminating the process and reducing material costs for separate surface layer components
Reduce.

The surface melt molding method using a foaming mold such as a porous electroforming mold whose temperature can be adjusted in the foaming molding step involves adjusting the mold temperature to form a non-foamed layer on the surface by the foaming force of beads. Therefore, there is no need to provide a special pressurizing device, and the foam molding device is also a surface melt molding device as it is, and the cost of the entire device for producing a thermoplastic resin bead foam is suppressed.

[0014]

[0015]

Next , a thermoplastic resin foam according to the present invention and a method for melt-molding the same will be described . The thermoplastic resin bead foam of the present invention is made of a single material, and has a foam layer and a molten layer on the surface thereof.

The materials used include polypropylene, polyethylene, polystyrene, polyphenylene oxide, etc.
Alternatively, any material made of thermoplastic resin beads such as these alloys can be used.

As described above, the non-foamed and smooth surface has higher surface hardness, better scratch resistance and better rigidity than the conventional foamed surface. In addition, when the surface is smooth, it becomes possible to apply a design.

The method of the present invention for molding the surface of the thermoplastic resin bead foam of the present invention as described above includes:
It is as follows.

In particular, in the bead foam molding step, a porous electroforming mold whose temperature can be adjusted to a high temperature and a low temperature is used as a foaming mold, and the temperature of the foaming mold is adjusted to be equal to or higher than the melting temperature of the beads immediately before the end of bead foaming. The method is a surface melt molding method for a thermoplastic resin bead foam in which the temperature is adjusted to be lower than the melting temperature of the beads and a non-foamed layer is formed on the surface by the foaming force of the beads.

In this case, in order to obtain a molded product having a good surface, a sufficient internal pressure is ensured, and the foaming characteristics of the beads are changed and the filling amount is adjusted so as to compensate for the volume reduction of the resin due to the melting of the surface layer. It is important.

[0021] In addition, in the surface melt molding a thermoplastic resin beads foam above SL of the present invention, to transfer the design of Shiboto the surface of the bead foam, design to be transferred to the metal plate or mold If irregularities are provided, a non-foamed layer is formed on the surface and a design such as squeezing is transferred.

Next, an embodiment of the present invention will be described together with a comparative example by taking up one specific material of the thermoplastic resin bead foam of the present invention and the surface melt molding method thereof.

An experiment was conducted using polypropylene as a specific material. Using a nickel electroformed plate, the squeezed leather is transferred to the surface layer of polypropylene 15-fold bead foam to form a thermoplastic resin bead foam. The factors at that time were the electroformed plate temperature A and the pressure B, and each factor was divided into three levels shown in Table 1 and tried. Common to each of the examples, the pressurization time was 15 seconds, and the cooling time was 30 minutes from the end of pressurization by applying tap water to the electroformed plate. Table 2 shows the results.

[0024]

[Table 1]

[0025]

[Table 2]

In the level terms shown in Table 2, A1, A2,
A3 indicates that the level of the electroformed plate temperature A is 1, 2, and 3, respectively, and B1, B2, and B3 indicate that the pressure B is the level 1, 2, and 3, respectively. The surface porosity of the evaluation item is indicated by x when there is a porosity on the surface, ○ when there is no porosity on the surface, and △ when the porosity is almost completed. The transferability of the squeezed skin was all good and is indicated by ○. Fig.
Means unnatural irregularities formed by inappropriate molding conditions as shown in 1 ; O indicates no irregularities, X indicates irregularities, and indicates irregularities. ing.

The diagram shown in FIG. 1 is a diagram showing one model of the experiment, in which unnatural irregularities 5 are formed on the surface layer. When the melt molding of the present invention is performed, a first molten layer 3 and a second molten layer 4 are formed on the surface of the foamed layer 1. This is the surface layer of the thermoplastic resin bead foam of the present invention, but in the case of the model shown in FIG. 1 , the molding conditions were inappropriate, so that the second molten layer 4 became an uneven foam layer and the surface was uneven. It is considered that No. 5 was formed. Such irregularities 5 can be eliminated by correcting the molding conditions to the following optimum levels.

Next, it can be seen from the results shown in Table 2 that the thermoplastic resin bead foam of the present invention has an A1B3 and A2B3 level having a smooth surface without any porosity or unevenness. That is, electroformed plate 250 ° C
And a pressure of 1.0 kgf / cm ² and an electroformed plate 26
It is understood that the one at 5 ° C. and the pressure of 1.0 kgf / cm ² is optimal. In addition, this optimal level is 15
The optimal level when melt molded on the surface layer of double bead foam, depending on the material used and the expansion ratio,
The optimal level is different.

In addition, it can be seen from the results shown in Table 2 that the thickness of the surface layer of the thermoplastic resin bead foam of the present invention formed by the surface melt molding method of the present invention is at an optimum level. As described above, even if the first and second molten layers are combined, it is a relatively thin layer of 0.9 mm to 1.1 mm. Since the thermoplastic resin bead foam of the present invention has a surface layer and a foam layer formed of a single material, the surface layer can be formed to be thin as described above when there is a certain restriction on the thickness of the entire foam. This means that the reduction in the thickness of the foam layer is small, and the original function of the foam is not impaired.

[0030]

As described above, in the thermoplastic resin foam of the present invention, the surface layer is non-foamed and smooth, and it is necessary to attach another member for the surface layer in order to obtain scratch resistance, rigidity and design. As a result, the thermoplastic resin bead foam, which does not require the surface layer member to be attached to the surface, reduces the material cost of the entire product and improves the practicality of the foam itself. Further, since the non-foamed layer and the foamed layer, which are the surface layers, are formed of a single material, they can be recycled and resources can be saved.

[0031] The surface melt molding method of the present invention is to melt the surface of the foam layer by applying <br/> mold heated, expanded bead pressure
And more by forming the non-foamed layer having a constant thickness, to improve the scratch resistance and rigidity of the surface, and because it is intended to obtain a design, working process for forming a separate member as in the prior art for the surface layer and, The step of attaching the separate member is eliminated, and the material cost of the separate member for the surface layer is reduced to reduce the manufacturing cost of the entire product.

[Brief description of the drawings]

FIG. 1 is a diagram showing a model of a thermoplastic resin bead foam.
is there.

FIG. 2 is a view showing a conventional thermoplastic resin bead foam.
You.

[Explanation of symbols]

1 foam layer 3 first molten layer 4 second molten layer

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takahiro Yamaguchi 11 Kasamatsu, Ogawa, Higashiura-cho, Chita-gun, Aichi Prefecture (56) References JP-A-5-124142 (JP, A) JP-A-60-190335 (JP, A) )

Claims (3)

(57) [Claims] 1. A foamed layer and a molten layer on the surface thereof are formed of a single material by forming a surface of the foamed layer by melting, and the molten layer is formed by applying an internal pressure by foaming to the surface of the foamed layer. A thermoplastic resin bead foam formed from a first molten layer and a second molten layer by melting. 2. The thermoplastic resin bead foam according to claim 1, wherein a squeezed design such as squeezed leather is transferred to the first molten layer. 3. A foaming mold capable of controlling the temperature at a high temperature and a low temperature, wherein the temperature of the foaming mold is adjusted to a temperature equal to or higher than the melting temperature of the beads immediately before the end of bead expansion, and thereafter adjusted to a temperature equal to or lower than the melting temperature of the beads. A method for melt-forming a thermoplastic resin bead foam by molding a molten layer on the surface by internal pressure due to the foaming force of the beads, without using external pressure.