JPS58119831A - Method of making rigid synthetic resin foamed body pliable - Google Patents

Abstract

PURPOSE:To improve the pliability, flexing properties, and cushioning properties, by compressing a rigid synthetic resin foamed body under a temperature at or below its softening point and a high compression rate, and thereafter stopping the compression so as to allow it to be restored spontaneously. CONSTITUTION:First, a rigid synthetic resin foamed body (preferably of a polystyrene foamed at a high forming rate of 20-50) is compressed at a temperature <= its softening point until the length thereof in the direction of the compression becomes 60%, preferably, 40% <= the original length, and after stopping the compression, the foamed body is allowed to stand under atmospheric pressure to be restored spontaneously. It is preferable that the compression is gradually performed at a compression speed of 1-50mm..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for making a foam made of a hard synthetic resin flexible.

BACKGROUND ART Hard synthetic resins, such as styrene resin foams, exhibit good thermal insulation and have high mechanical strength 5, so they are widely used as thermal insulation materials at low temperatures and as cushioning materials for packaging. However, the use of this foam has been found to be limited due to its tendency to buckle. In other words, this foam has poor flexibility, so if you try to bend the foam, it may break, or it may warp when used as a cushioning material for packaging. It becomes impossible to protect the contents. Therefore, it was found that the uses of this foam were limited.◇Therefore, the inventor tried to make this foam flexible and easy to bend.

This inventor describes a foam obtained by impregnating polystyrene with a foaming agent in an extruder and extruding and foaming the polystyrene.
We investigated ways to make it easier to bend. As a polystyrene foam, it foams uniformly and finely, and the foaming ratio is
20 to 50 times the magnification was used. - At that time, the inventor Jin attempted to compress the foam board in the thickness direction at room temperature. For example, an attempt was made to compress a foam board at a rate of 10 wx/min until the thickness was about 1/2 inch, then remove the pressure and leave it as it was. As a result, the inventor has found that upon compression in this manner, the thickness of the foamed board is recovered to such an extent that the foamed board exhibits good flexibility. That is, it has been found that the foamed board thus obtained does not break even if it is bent significantly. This invention was made based on such knowledge.

This invention is characterized in that a hard synthetic resin foam is compressed at a temperature below its softening temperature until its length in the compression direction becomes equal to or less than the original length Δθ, and then the compression is stopped and the material is allowed to recover naturally. The present invention relates to a method of making a rigid synthetic resin foam flexible.

The hard synthetic resin foam used as the material for the method of this invention is foamed using a foaming agent. For example, a low-boiling aliphatic saturated hydrocarbon such as butane and butane is used as a blowing agent, polystyrene is melted in an extruder, and the blowing agent is added to the resin in the extruder. This creates polystyrene containing a blowing agent)
This is extruded into a plate shape from an extruder and foamed to a foaming ratio of 5 times or more, thereby forming a foam board.

It is desirable to use a material whose expansion ratio is within the range of 20 times to 50 times.

In the method of this invention, a plate made of acidic synthetic resin foam as described above is used as a material and is compressed at room temperature. It is convenient to compress the material in the direction of its thickness. For compression, this is sandwiched between presses and compressed for several minutes until the thickness becomes 10% or less of the original thickness. Then, immediately remove the pressure and leave it in the atmosphere. Then, the foam recovers to more than half its original thickness, 2θ to 20%, after several minutes. The 9-foamed material thus obtained is a flexible foamed material that is easy to bend and has rich cushioning properties, and is the object of the method of this invention.

It is already known to compress rigid synthetic resin foam boards. For example, compression is also performed during the continuous production of rigid foam boards. However, in known compression methods, the degree of compression is small. For example, a foam board obtained by an extrusion method is compressed by being sandwiched between a pair of rolls 8, and the foam board is advanced. Since the compression is to prevent the foam board from slipping on the roll surface, the thickness of the shrinkage due to compression is at most Wk% of the original thickness, about 0s. If compressed too much, the hard foam board would be soaked, and it was thought that the foam KL would be meaningless, so conventionally the shrinkage margin was at most the same as that of the KL. Since the method of this invention makes the shrinkage margin greater than 7ζ, it is completely different from conventional compression.

In this invention method, various hard resins can be used as the hard synthetic resin. Among them, polystyrene shows the most remarkable effect. Next to that, styrene copolymers obtained by graft polymerizing or block copolymerizing styrene to polyolefins exhibit remarkable effects. This effect is not observed in soft synthetic resin foams.

The foam is obtained by extrusion molding and has a remarkable effect.For the foam, foam beads are placed in a perforated mold and steam is blown into the mold to expand the foam. There is also a method of forming a foam into a foam, but the effect of the method of this invention is not as noticeable in the foam obtained in this way as in the foam #1 obtained by extrusion molding.

As for the compression method, it can be done continuously, or it can be done discontinuously. Continuously, the butterfly can be rotated in pairs in opposite directions, or the foam can be compressed by passing it through the gate. To compress discontinuously, press the foam between compression presses. Compression is performed below the softening temperature of the foam. This is to give the foam as much elastic deformation as possible. In addition, it is necessary to perform compression in at least seven directions, but it may be performed in two or more directions. Also, compression is performed until the length in the compression direction becomes 30% or less of the original length. Preferably, it is compressed until it becomes less than 100 ml. In other words, it is compressed so that the shrinkage margin due to compression extends to more than yO of the original length, preferably more than to-.

It is desirable to perform compression as gradually as possible. Specifically, it is desirable that the compression be carried out gradually so that the compression speed is about 7 minutes to about 30 pieces per minute. Further, the time required for compression may be from several seconds to several minutes. too long,
For example, if the foam is left in a compressed state 11 for a long time, the foam loses its ability to return to its original state, which is inconvenient.

When the compression described above is stopped and the foam is left under atmospheric pressure,
The foam gradually returns to its original state.

The speed of this recovery is related to the compression time required. That is, when compression is performed for a long time, KFi returns slowly, but when compression is performed only for a short time, KFi returns quickly. As mentioned above, when compressed for only a few seconds or minutes, a considerable amount of restoration is already observed immediately after the compression is stopped and left at atmospheric pressure. Immediately after being placed down, it becomes a small shrinkage area that is less than Da θ attack.

As mentioned above, once a foam is compressed, its length in the compression direction does not completely return to its original length. The rate of restoration is usually 20-10%. When the restoration rate is close to 10%, it appears that the hair has almost returned to its original length.

The above-mentioned compression may be performed not only #-1/times but also twice or more. However, the most remarkable effect is achieved at the first compression, and after the -th compression, the effect of improving elasticity gradually decreases.

Therefore, the number [[? A moth that repeatedly compresses for lK,
It doesn't make much sense.

After being compressed according to the method of the invention, the foam is released and restored, and the foam is flexible and very bendable. Thus, the foam thus made flexible can be bent into an arc without buckling. Therefore, since it can be formed into a flat plate at first and then bent into any shape, soft foam is similar to semi-rigid foam and can be used as a cushioning material, insulation material for bending, and as a filler. In this respect, the method of this invention has great utility value.

Examples are given below to explain that the products obtained by the method of this invention are highly flexible and easy to bend. The product was extruded, molded into a plate shape, and foamed to obtain a polystyrene foam having a thickness of 35 mm.

The polystyrene foam was placed in a Tensilon UTM-/box (manufactured by Toyo Bold Line Co., Ltd.) and compressed at a rate of 10 vm/min at 0°C until the thickness was 30% of the original thickness. The relationship between strain and stress at this time is shown by the curve in Figure 1.Next, the pressure on the foam compressed in this way was removed, and then it was left to stand for a while. Then, the foam Fi/7. ．． has been restored to the depth of the proverb. The thus restored foam was put into the Tensilon UTM-/ mold again and heated to 10wx at θ°C.
It was compressed at a speed of /min. Curve 1 in FIG. 1 shows the relationship between strain and stress at this time.

Comparing curve M and curve B, we can see that while curve M buckles, curve B does not buckle and is a gentle curve. It turns out that there are some flexible things.

Also, to see the improvement in bendability, 1 tensilon U! Senior
9. Conduct a bending test at 0°C using a / type device. The test conditions were as follows:
Cut out a piece of Ltm size and use a jig tip of 10Rws.
Spanco θOms speed was 30 W/min. As a result, the amount of deflection at break was 6 at /1.7 mm for the curved foam.
However, for the curve 10 foam, it became lJ and Jm, and it was recognized that the deflection amount was improved by three times.

Example A copolymer obtained by graft polymerizing styrene onto copolyethylene (Bio-Shichiran, manufactured by Tanemizu Kaseihin Co., Ltd.) was used to obtain a material with a thickness of 1. A foam board that was expanded 35 times as much as Koko was made by extrusion molding. This foam board was used as material 2, and a compressive stress strain curve was prepared in the same manner as in Example/9, and curve O in FIG. 2 was drawn for the foam board after extrusion. The thus compressed foam board was allowed to stand for 9 minutes, and the thickness returned to 23.0 wg1. When the compressive stress strain curve was prepared again in the same manner as in Example 9 for the nine samples whose thickness had been restored, the curve shown in Figure 1 was obtained. Comparing songs io and D in FIG. 2, it can be seen that the songs processed by the method of this invention are extremely flexible.

In addition, the amount of fracture deflection was measured in the same manner as in Example 1 for a foam board that draws a curve O and a foam board that draws a curve. I noticed that the quantity has improved significantly.

[Brief explanation of the drawing]

FIG. 7 and FIG. 2 show the foam board used in the example.
This is a graph showing the relationship between compressive stress and strain. Applicant: Sekisui Plastics Co., Ltd.

Claims (1)

[Claims] The hard gold T & resin foam is compressed at a temperature below its softening temperature until the length in the compression direction becomes 1% or less of the original length, and then the compression is stopped and the material is allowed to recover naturally. , a method for making rigid synthetic resin foam flexible.