JP3960052B2 - Foam board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a synthetic resin foam board used for, for example, a track board.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a polypropylene extruded board (conventional product 1) is known as a synthetic resin foam board used for a track board or the like. This foam board includes a shell layer formed on the outer periphery of the board and a foam part formed integrally with the shell layer on the inner side of the shell layer. Both the foamed portion and the shell layer are made of polypropylene.
[0003]
When manufacturing the foam board of the conventional product 1, the shell layer is formed by supplying a polypropylene material and a foaming agent to an extrusion molding machine, and extruding the molten material into the mold from the nozzle of the extrusion molding machine. At the same time, the foamed portion is formed by foaming the material inside the shell layer. Therefore, in the conventional product 1, the shell layer and the foamed portion are completely integrated, and the boundary between the shell layer and the foamed portion is not clear.
[0004]
On the other hand, as another example of a polypropylene foam board, a two-layer foam board (conventional product 2) composed of a shell layer and an internal foam layer has been proposed. In this case, both the shell layer and the internal foam layer are made of polypropylene.
[0005]
The extrusion machine for producing the foam board of the conventional product 2 has a first nozzle for forming the shell layer and a second nozzle for forming the internal foam layer, and the polypropylene for the shell layer is the first. While extruding from the nozzle into the inside of the mold, the polypropylene for the internal foam layer added with the foaming agent is extruded from the second nozzle into the inside of the mold.
[0006]
In this way, the inner foamed layer is formed by foaming the material supplied to the inside of the shell layer at the same time as forming the shell layer. In this conventional product 2, the shell layer and the internal foam layer are integrally adhered to each other, but the shell layer and the internal foam layer can be distinguished.
[0007]
[Problems to be solved by the invention]
The conventional product 1 is excellent in impact resistance at room temperature, and is used, for example, as a twist plate for a medium-sized truck or the like. However, this conventional product 1 has low impact resistance at low temperatures because polypropylene becomes brittle at low temperatures (for example, minus 30 ° C. or lower). For this reason, the conventional product 1 cannot be used in places where impact resistance is required, such as a front plate of a truck (a plate standing on the foremost part of the loading platform and extending in the vehicle width direction) and a twist plate.
[0008]
On the other hand, the conventional product 2 also has a problem of low impact resistance at low temperatures as in the conventional product 1, since the shell layer and the internal foam layer are made of polypropylene. It can be considered that the internal foam layer of the conventional product 2 is made of polyethylene. However, in such a configuration, since the compatibility between the shell layer made of polypropylene and the internal foam layer made of polyethylene is not good, the interface between the shell layer and the internal foam layer easily peels off. For this reason, there were problems such as low rigidity and deformation at high temperatures.
[0009]
Further, although it is conceivable to use polyethylene as the material for the shell layer in the conventional product 2, polyethylene is inferior in weather resistance because it tends to deteriorate over time due to the influence of the external environment such as ultraviolet rays. For this reason, stress cracks may occur in the shell layer, and there are difficulties in durability. In addition, since polyethylene cannot be painted or bonded, there is a problem in that it cannot be painted by a general user or adhered to a seal on a track board.
[0010]
Accordingly, an object of the present invention is to provide a foam board that is excellent in impact resistance and durability, and further provides a foam board that can be painted and sealed.
[0011]
[Means for Solving the Problems]
The foamed board of the present invention is a foamed board having a three-layer structure having a shell layer, an internal foamed layer formed inside the shell layer, and a skin layer covering the shell layer. The shell layer and the internal foamed layer are both made of high-density polyethylene, and have the skin layer made of ethylene vinyl acetate on the outer surface of the shell layer, and are extruded so as to have a rectangular cross section. It is characterized by this. In this invention, since the shell layer and the internal foam layer are both made of high-density polyethylene, the impact resistance at low temperature is excellent, and the compatibility of the interface between the shell layer and the internal foam layer is good. The internal foam layer can be fully integrated.
[0012]
In the present invention, in order to improve the weather resistance of the previous SL shell layer, to one side or the entire surface of the outer surface of the shell layer, that have provided ethylene vinyl acetate tape DOO or Ranaru skin layer.
[0013]
According to the invention, the outer surface of the foam board having a shell layer and an internal foam layer made of high density polyethylene, covered by ethylene vinyl acetate tape DOO or Ranaru epidermal layer allows painting and sealing adhesive, durable The nature will increase. The foam board of the present invention is used for a track board .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.
A foam board 10 shown in FIG. 1 can be used as a cover plate for a transportation vehicle such as a truck, and includes a shell layer 11 formed on the entire circumference of the foam board 10 and an interior formed inside the shell layer 11. A foam layer 12 and a skin layer 13 covering one or all of the outer surfaces of the shell layer 11 are provided. In addition, in order to reduce the linear expansion coefficient of the shell layer 11, you may contain glass fiber.
[0015]
Both the shell layer 11 and the internal foam layer 12 are made of HDPE (high density polyethylene). The expansion ratio of the internal foam layer 12 is 1 to 4 times, more preferably about 1.5 to 3 times. If the expansion ratio is less than 1.5 times, the specific gravity of the foam board 10 becomes larger than that of the existing plywood or the conventional foam board, which is not preferable because the weight of the vehicle increases. When the expansion ratio exceeds 4 times, the weight reduction rate is large, but the impact resistance is deteriorated, which is not preferable.
[0016]
The skin layer 13 is made of EVA (ethylene vinyl acetate) or ionomer and has a thickness of about 0.1 mm to 1.5 mm. As will be described later, the skin layer 13 may be formed integrally with the shell layer 11 and the inner foam layer 12 by providing an adhesive layer as necessary, or the outer surface of the formed shell layer 11 may be EVA. A material or ionomer material may be applied and cured. Alternatively, an EVA film or an ionomer film may be adhered or welded to the outer surface of the shell layer 11.
[0017]
When the skin layer 13 made of ionomer is provided on the entire outer surface of the foam board 10, the foam board 10 can be manufactured by an extrusion molding machine 20 shown in FIG. The extrusion molding machine 20 includes a mold 21, a first nozzle 22, a second nozzle 23, a third nozzle 24, material supply mechanisms 25, 26, 27, and the like. The mold 21 has a cavity 28 corresponding to the cross-sectional shape of the foam board 10 to be molded.
[0018]
The first nozzle 22 has a function of discharging the HDPE material 12 a for the inner foam layer 12 sent by the first material supply mechanism 25 to a region near the center of the cavity 28 in the mold 21. The second nozzle 23 has a function of supplying the HDPE material 11 a for the shell layer 11 sent by the second material supply mechanism 26 to the vicinity of the peripheral wall of the cavity 28.
[0019]
Further, the third nozzle 24 has a function of discharging the EVA material or ionomer material 13 a for the skin layer 13 sent by the third material supply mechanism 27 to the peripheral wall of the cavity 28.
[0020]
The foamed board 10 has an internal foamed layer 12 made of HDPE formed inside an HDPE shell 11 that constitutes both the front and back surfaces 10a and 10b and the both side surfaces 10c and 10d of the board. For this reason, the impact resistance at the time of the low temperature of the shell layer 11 and the internal foaming layer 12 can be improved. For example, at around minus 30 ° C., high-density polyethylene can obtain impact resistance (Charby impact value) three times or more that of low-density polyethylene.
[0021]
Further, the outer side of the shell layer 11 is covered with a skin layer 13 made of EVA or ionomer. Since EVA or ionomer can be painted and sealed, it can be painted and sealed as desired by the user. In addition, EVA or ionomer is less likely to deteriorate over time due to the external environment such as ultraviolet rays, so even if high density polyethylene is used for the shell layer 11, it is difficult to cause deterioration over time due to the external environment such as ultraviolet rays and stress cracks occur. Excellent weather resistance.
[0022]
For this reason, the foam board 10 of this embodiment has both low-temperature impact characteristics and weather resistance, and can be used as a rack plate or a front plate of a truck bed that may be used in a cold region or the like. . Moreover, the high-density polyethylene, which is the material of the shell layer 11 and the internal foam layer 12, can recycle the waste material of the bottle container (for example, a case used for storage and transportation of bottled beer etc.).
[0023]
In the foam board 10 of this embodiment, since the shell layer 11 and the internal foam layer 12 are both made of high-density polyethylene, the compatibility and adhesion at the interface between the shell layer 11 and the internal foam layer 12 are high. And the internal foam layer 12 can be firmly integrated. For this reason, compared with the conventional foam board which consists of a single material (for example, only polypropylene), the equivalent rigidity was acquired and the thermal deformation could also be suppressed to the same extent.
[0024]
FIG. 3 shows an extrusion molding machine 20 ′ used when manufacturing the foam board 10 having the skin layer 13 on one side. The extrusion molding machine 20 ′ includes a mold 21, a first nozzle 22 ′, a second nozzle 23 ′, a third nozzle 24 ′, material supply mechanisms 25, 26, 27, and the like. The mold 21 has a cavity 28 corresponding to the cross-sectional shape of the foam board 10 to be molded.
[0025]
The second nozzle 23 ′ has a function of discharging the HDPE material 12 a for the internal foam layer 12 sent by the second material supply mechanism 26 to a region near the center of the cavity 28. The third nozzle 24 ′ has a function of supplying the HDPE material 11 a for the shell layer 11 sent by the third material supply mechanism 27 to the vicinity of the peripheral wall of the cavity 28.
[0026]
The first nozzle 22 ′ has a function of discharging the EVA material or ionomer material 13 a for the skin layer 13 sent by the first material supply mechanism 25 to the peripheral wall on one side of the cavity 28, that is, the shell layer 11 on one side. Have.
[0027]
In addition, when a foam board is used in an environment where the low temperature impact characteristic is not so required, the material of the shell layer 11 and the internal foam layer 12 is, for example, a waste film of an agricultural greenhouse instead of high-density polyethylene. By using LDPE (low density polyethylene), it may be part of environmental measures.
[0028]
【The invention's effect】
According to the invention described in claim 1, excellent in impact resistance at low temperatures and can provide a high foam board adhesion between the shell layer and the inner foam layer, a shell layer by the skin layer made of EVA The weather resistance can be increased, and a highly durable foam board can be obtained. Also, painting and seal bonding are possible.
[0029]
ADVANTAGE OF THE INVENTION According to this invention , the impact resistance at the time of low temperature is high, generation | occurrence | production of a stress crack can be suppressed, and the rigging board for trucks with high durability can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view of a part of a foam board according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing an extrusion molding machine for forming the foam board shown in FIG. 1. FIG.
FIG. 3 is a cross-sectional view schematically showing an extrusion molding machine used when a skin layer is provided on one side of a foam board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Foam board 11 ... Shell layer 12 ... Internal foam layer 13 ... Skin layer

Claims (1)

A three-layer foam board having a shell layer, an inner foam layer formed inside the shell layer, and a skin layer covering the shell layer ;
The shell layer and the internal foam layer are both made of high-density polyethylene, and have the skin layer made of ethylene vinyl acetate on the outer surface of the shell layer, and are extruded so as to have a rectangular cross section. foam board for tilting plate, characterized.

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