JPH08183082A - Thermoplastic resin foam body - Google Patents

Abstract

PURPOSE: To easily manufacture a thick-wall foam body by a method wherein a large number of band-form foam plates having a vertically long cross section are arranged in a lateral line adjacently to each other with the side faces facing each other, and the side faces of adjacent foam plates are integrally fused to each other. CONSTITUTION: A plurality of band-form foam plates 2 are obtained by extruding and foam molding a resin in a band plate form of a vertically long cross section from a die having a plurality of vertical slits. The foam plates 2 in a softened state are arranged in a lateral line adjacently to each other with the side faces facing each other, thereafter being molded into a planar or columnar thick-wall article having a predetermined thickness by roll molding vertically or crosswise. At this time, esp. fusion parts 3 between the foam plates 2, 2 are fused to each other so as to be approximately straight in a vertical direction (a thickness direction) in a cross section by being vertically compressed by roll molding. Alternatively, the respective foam plates 2 are bent in a zigzag or corrugated form to be integrally fused to each other by being vertically more compressed by roll molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin foam, and more particularly to an extrusion foam for a thick foam.

[0002]

2. Description of the Related Art Thick foams made of polyethylene or the like by extrusion foam molding have a method of molding a shape with a sizing die through a die of a T die, and a large number of strands extruded and foamed through a die having a large number of small holes. A method of converging and fusing at adjacent portions of each other (for example, Japanese Utility Model Publication No. 61-2).
No. 6030 gazette and special table 1-502252 gazette)
There is.

[0003]

However, in the case of the former method using the T-die, there is a problem in molding, and if the thickness exceeds a certain value, extrusion molding becomes difficult.
When molding thick foams of mm or more, a considerable free thickness of the foam is required. However, if the slit gap is increased for this reason, it will be difficult to maintain the resin pressure required for foaming, and Foaming starts in the mold before the resin is extruded, a good foaming state does not occur, and a good quality molded product cannot be obtained.

The latter method for focusing the extruded and foamed strands has been known in the past, and is generally called the strand extrusion method. The problem with this method is that when the material is a polyethylene resin, the temperature dependence of the viscosity suitable for extrusion foam molding is extremely large, so the appropriate temperature that shows the viscosity range suitable for extrusion foaming is extremely narrow, and the resin temperature If the temperature is lowered below the proper temperature, some of the numerous small holes in the die will be clogged, and a good molded product cannot be obtained.

In addition, in the case of this strand extrusion, it is difficult to form a foam of a strand from polyethylene resin alone, and particularly when a foam having a foaming ratio of 25 times or more is produced, adhesion failure of each strand is likely to occur. Molding is almost impossible. Therefore, in order to improve the adhesiveness of the resin itself used in this type of foam, it is common practice to mix an ionomer, EVA or the like.

However, in the case of mixing such resins,
Reuse becomes very difficult, and there is a problem in terms of recyclability.

The present invention has been made in view of the above, and in particular, a resin material having a relatively low adhesiveness such as a recyclable polyethylene resin alone is used, and a foaming ratio is large. However, the object of the present invention is to obtain a good quality thick thermoplastic resin foam in which the foamed state of the entire foam is good and the integrity is excellent.

[0008]

A thermoplastic resin foam of the present invention for solving the above-mentioned problems is a strip-shaped foamed plate of thermoplastic resin having a vertically long cross section extruded and foamed from a plurality of vertical slits. In a softened state, the side surfaces are arranged side by side in a row so as to be adjacent to each other, and the adjacent portions are fused together to form a relatively thick foam.

Further, in the above, it is particularly preferable that a large number of adjacent strip-shaped foam plates are bent in a zigzag shape or a wavy shape and are fused and integrated with each other.

For the thermoplastic resin foam, an extruder equipped with a die having a plurality of vertical slits arranged in a row at predetermined intervals in a row is used, and a material containing a foaming agent from each slit of the die is used. The resin is extruded in the form of a strip having a vertically long section to foam, and a plurality of the extruded foamed strip-shaped foam plates are adjoined so that their side faces are brought together through a sizing die while in a softened state, and the adjoining portion. In the above, the side surfaces are fused and integrated with each other, and further pressed by means such as roll molding from the upper and lower sides and the left and right sides to form a shape having a predetermined thickness so as not to create a gap between the foam plates. It can be obtained by

[0011]

According to the above thermoplastic resin foam of the present invention,
Since a large number of vertically elongated strip-shaped foam plates are arranged in rows and adjacent to each other so that their side faces are aligned, and the side faces of the adjacent foam plates are fused and integrated with each other, they are extruded from a vertical slit. By increasing the vertical dimension of the strip-shaped foam plate, a thick foam can be easily obtained as compared with the conventional one.

Moreover, since a plurality of strip-shaped foam plates are arranged in a row and adjacent to each other, it is not necessary to increase the gap between the slits for extruding the foam plates. Therefore, the foaming degree of each foam plate is made uniform and a single slit is formed. As a result, it is possible to obtain a foamed body in a uniform foamed state as a whole as compared with the case of extrusion molding.

Further, adjacent strip-shaped foam plates having a vertically long cross section,
Since the fusion is performed over a wide surface over the entire side surface, the fusion area is increased and the adhesive strength between the foam plates is increased as compared with the case where the strand type aggregate is formed.

In particular, when the strip-shaped foam plates are refracted into a zigzag shape or a wavy shape and are fused and integrated as described in claim 2,
Since the fused portion between the adjacent foam plates is bent to increase the fused area, the adhesive strength between the foam plates is further increased.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

1 and 2 show one embodiment of a thick thermoplastic resin foam according to the present invention, and FIG. 3 shows a front view of a die used for extrusion foam molding of the same. .

The thick thermoplastic resin foam (1) shown in FIG. 1 is extruded and foamed from a die (11) having a plurality of vertical slits (12) shown in FIG. The plurality of strip-shaped foamed plates (2) are arranged in a row in a softened state and are adjacent to each other so that their side surfaces are aligned with each other. It is formed in a columnar shape, and in particular, the fused portion (3) between the foam plates (2) and (2) becomes substantially straight in the vertical direction (thickness direction) in the cross section depending on the degree of compression from the upper and lower sides by roll forming. It shows the case of molding so as to be fused.

In this case, the adjacent strip-shaped foam plates (2)
Since (2) is fused on the wide side surface, the fusion area is larger than in the case of the conventional strand fusion, and the adhesive strength between the foam plates (2) is increased.

In addition, each strip-shaped foam plate (2) is bent into a zigzag shape or a wavy shape as shown in FIG. 2 by means such as increasing the compression by roll forming from above and below.
The side surfaces of the bent foam plate (2) may be fused and integrated with each other.

In this case, since the fused portion (3) has a bent shape, the fused area is increased and the adhesive strength between the foam plates (2) is increased, and the fused portion (3) of the foam plate (2) is increased. ) Is less likely to occur, and the unity is further improved.

As the material resin of the thermoplastic resin foam (1), in addition to polyolefin resins such as polyethylene, polypropylene and copolymers mainly composed of olefins, polystyrene resins such as styrene and methylstyrene are generally used. Various thermoplastic resins capable of extrusion foam molding can be used.

A polyolefin resin having particularly low adhesiveness,
Above all, a resin of low density polyethylene alone having a density of 0.91 to 0.93 g / cm @ 2 can be used as a raw material, and in this case, sufficient adhesive strength can be secured between the foam plates.

The thickness and width of the thermoplastic resin foam of the present invention,
The density and the expansion ratio can be appropriately set depending on the vertical and horizontal dimensions of the band-plate-shaped foam plate to be fused, the number of sheets to be fused, the degree of foaming, among others, the density is 0.18 to 0.018 g / cm 2, and the expansion ratio is 50.
It can be suitably applied to a relatively thick foam having a thickness of 50 to 200 mm and a foam structure having an open cell ratio of 50% or less.

The number of slits (12) of the die (11) in the extruder for vertically extruding the strip-shaped foam plate, the gap (w),
The lengthwise dimension (h) and the slit spacing (s) can be appropriately set according to the thickness and width of the thermoplastic resin foam to be obtained, the density (foaming ratio), etc., but the slit gap (w) is 3 mm. Below, it is preferably 0.5 to 2 mm. That is, if the slit gap (w) is larger than the above, the foam density obtained by extrusion foam molding tends to be non-uniform, which is not preferable. Further, if the gap (w) is 0.5 mm or less, it becomes difficult to hold the foam in a vertical shape in a softened state, which is not preferable. It is also possible to form the vertical slit in a zigzag shape or a wavy shape.

When the width of the thermoplastic resin foam to be obtained is large, a plurality of extruders are installed side by side so that the strip-shaped foam plates extruded from the slits of the respective caps are fused and integrated. Good.

Since a large number of strip-plate foam plates (2) extruded and foam-molded as described above are arranged in rows and fused to each other, the longitudinal dimension of the strip-plate foam plates (2) should be large. Thereby, a thick foamed product having a large thickness as a whole can be obtained.

Example 1 Low-density polyethylene resin (manufactured by Nippon Unicar Co., Ltd., trade name:
DFDJ-6776, melt index: 0.3 g /
Heat seal strength 0.9 at 10 min at 115 ° C
5N) to 100 parts, a bubble regulator (Boehringer
Ingelheim, trade name Hydrocelol) 0.2
The mixture to which 0 part was added was supplied from the hopper of the first extruder so that the amount thereof was 110 kg per hour, and butane as a foaming agent was supplied at the tip part at 3.6 kg / hr.
There are 8 slits 40mm long and 1mm wide as shown in Fig. 3.
When extrusion molding is performed from a die (11) arrayed at mm intervals, and immediately after that, roll molding is performed, a thickness of 60 mm,
A foam having a width of 160 mm, a foam density of 0.18 g / cm 3 (foaming ratio of 5 to 6), and an open cell ratio of 18% could be obtained. This foam had a uniform foaming state and a uniform cross section, and was a foam with good integrity.

Example 2 Example 1 is the same as Example 1 except that the injection amount of butane was changed to 10.8 g / hr and hydrocerol was changed to 0.16 parts.
Under the same conditions as above (40 mm in length and m in width with the same structure as in Example 1)
When using a die with slits of 0.6 mm arranged at 5 mm intervals, the thickness is 60 mm and the width is 200 m.
m, foam density 0.023 g / cm3 (foaming ratio about 30
It was possible to obtain a foam having an open cell ratio of 38%.
This foam was also good in foaming state and integrity.

Example 3 The same composition as in Example 1 was supplied from the hopper of the first extruder so that the amount was 130 kg per hour, and butane as a foaming agent was supplied at the tip portion at 4.3 kg / hr. Then, when a slit having a length of 10 mm and a width of 1 mm is extruded from a die having 8 mm intervals, a thickness of 150 mm and a width of 150 m.
m, foam density of 0.18 g / cm 3, and open cell rate of 28% could be obtained. This foam was also good in foaming state and integrity.

Example 4 The same composition as in Example 2 was supplied from the hopper of the first extruder so that the amount was 130 kg per hour, and butane as a foaming agent was supplied at the tip portion at 12.8 kg / hr. Then, from a die in which slits having a length of 10 mm and a width of 0.6 mm are arranged at intervals of 5 mm, the die is extruded and molded for a thick material, and a thickness of 150 mm, a width of 180 mm, and a foam density of 0.0
A foam having a rate of 23 g / cm @ 3 and an open cell rate of 38 g could be obtained. The foamed state and the integrity of this foam were both good.

Comparative Example 1 A product having the same thickness and foam density as in Example 4 was extruded and foamed using a T-die, but a good thick foam could not be obtained.

COMPARATIVE EXAMPLE 2 The same product as in Comparative Example 1 was extruded by using a strand. However, when the temperature at the tip of the extruder was lowered in order to attain a foaming-appropriate temperature, several holes for strand extrusion of the die were found. Since it was clogged and the adhesiveness of each strand was deteriorated, a good foam could not be obtained.

[0033]

As described above, according to the thermoplastic resin foam of the present invention, since a plurality of strip-shaped foam plates extruded in a vertical form are arranged in a row and are fused and integrated with each other,
It is possible to obtain a foam that is thicker than before. Moreover, since each strip-shaped foam plate is extruded and foam-molded, a uniform foaming state can be obtained as a whole, and the adhesive strength between adjacent strip-plate foam plates is higher than that of a strand type aggregate. Even if a resin made of a resin having high adhesiveness and low adhesiveness such as polyethylene resin is formed by fusion bonding, good integration can be obtained.

Particularly, when the adjacent strip-shaped foamed plates are bent in a zigzag shape or a wavy shape to be fused and integrated as described in claim 2, the fused portion has a refraction shape and the fused area is Due to the increase, the adhesive strength between the foam plates is further increased,
Even if the material is one with low adhesion such as polyethylene,
Has sufficiently high adhesive strength.

[Brief description of drawings]

FIG. 1 is a perspective view showing one embodiment of a thermoplastic resin foam of the present invention.

FIG. 2 is a sectional view showing another embodiment of the thermoplastic resin foam of the present invention.

FIG. 3 is a front view showing a die of an extruder used for producing the thermoplastic resin foam of the present invention.

[Explanation of symbols]

 (1) Thermoplastic resin foam (2) Extruded foam plate (3) Fusion part

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Claims (2)

[Claims] 1. A strip-plate foam plate made of a thermoplastic resin having a vertically long section extruded and foamed from a plurality of vertical slits is arranged in a row in a softened state so that the side faces thereof are adjacent to each other and adjacent to each other. A thermoplastic resin foam, which is formed by being fused and formed into a relatively thick foam. 2. The thermoplastic resin foam according to claim 1, wherein a plurality of adjoining strip-shaped foam plates are bent in a zigzag shape or a wavy shape so as to be fused and integrated with each other.