JPS6260255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synthetic resin foam and aims to provide a foam with high impact resistance and less deflection.

Conventionally, there have been various types of foams made by extruding and bonding a large number of foamed resin strips, but they have had the following problems.

In other words, in the case of a polyfoam made only of polystyrene, it is easy to increase the expansion ratio, and the fusion of the strips is good, but it is weak against impact and cannot be bent, and even if V-grooves are cut into the plate, the hinge It has the disadvantage that it cannot be processed. Next, when using high-impact polystyrene, although it is strong against impact, the hinge processability is still insufficient, and as the rubber content increases, the deflection becomes too large and foaming becomes difficult, resulting in poor fusion of the strips. It was hot. Furthermore, in the case of polypropylene foam, although good in terms of impact resistance, it had the disadvantage of extremely large flexure.

As is clear from such conventional technology, improving impact resistance and reducing deflection are fundamentally contradictory performances, and it is difficult to demand both performances from a single material. It was considered a thing.

Based on the above-mentioned technical background, the inventor of the present invention conducted extensive research and succeeded in imparting the necessary functions to each strip separately and further increasing the strength of the fusion bond between the strips.

That is, the structure of the present invention is a multifoam body made by extruding and converging a large number of foamed styrene-based thermoplastic resin strips, and at least a group of strips located at the outermost periphery is composed of all or a part of the strips. is made of a foamed styrene thermoplastic resin containing 5% by weight or more of a rubbery polymer, and the density of the strips constituting the multifoam is made of a foamed styrene thermoplastic resin containing a rubbery polymer. is large, and the remaining portions are formed to become gradually smaller as they move away from the group of strips.

The foamed styrene thermoplastic resin containing the above-mentioned rubbery polymer may be a mechanical mixture of polystyrene and various rubbers such as butadiene, isoprene, chloroprene, natural rubber, chlorinated polyethylene, or Although a copolymerized material can be used, it is preferable to use a thermoplastic elastomer obtained by copolymerizing styrene and butadiene and/or isoprene.

On the other hand, as a styrene resin with strong bending rigidity,
Single or copolymers of styrene, α-methylstyrene, p-methylstyrene, etc., and resins obtained by copolymerizing 50% or more of these with (meth)acrylic acid, maleic anhydride, etc. may also be used.

The above two types of resin are extruded and foamed as separate strips and then fused and integrated.Although the two types of resin are from the same system, fusion is when molding the completely identical pieces. The problem arises that it is not as strong as it should be. In particular, when foaming occurs, the resin cools during foaming and micro-contact occurs between the cell membranes, making the fusion bond even weaker. Furthermore, the greater the difference in density (expansion ratio) between adjacent strips, the more likely interlayer failure will occur, and as a result, only products in which strips can easily peel off can be obtained.

However, the fusion force of the strips, that is, the adhesive force, can be strengthened by increasing the amount of resin on the bonding surface and by reducing the difference in density between the bonding side and the bonded side.

Therefore, in the present invention, we focused on this point, and assuming that the strips containing the rubbery polymer located at the outermost periphery of the multifoam are the first group, the average density of the strips constituting these groups is calculated as follows: the largest (low foaming), the adjacent second group of strips made of highly rigid styrene resin has a medium density (medium foaming), and the adjacent third group of strips has a medium density. When the average density was reduced (high foaming) and the process was repeated with such density differences, it was confirmed that the fusion strength between individual strips was improved.

At this time, the group of strips containing the rubbery polymer with the highest density may be present all around the outermost periphery of the molded product, or may be present only on a part of the desired surface of the molded product. .

If it is present in a part of this outermost periphery, it is preferably 20% by volume or more of all the strips in the outermost periphery.

In order to adjust the density of the target strips provided by this invention, it is necessary not only to adjust the amount of blowing agent in each resin composition, but also to adjust the distribution, depth, and diameter of the small holes in the extrusion molding device. It can be adjusted by heating or cooling the strip locally near the outlet of the mouthpiece.

Next, embodiments of the present invention will be illustrated below with reference to the drawings.

10 refers to the whole multi-foam body made by extruding and converging a large number of expanded styrene resin strips, and 11
12, 13, . . . indicate the remaining strip groups, 12 is adjacent to 11, and 13 is adjacent to 12. It is.

According to the illustrated example, in the case shown in FIG. 1, the rubbery polymer-containing strip group 11 of the multifoam 10 is a foamed styrene thermoplastic containing 5% by weight or more of a rubbery polymer. It is made of resin. Also, the strip groups 11, 12, 13 of the multi-foam foam 10
The density of ...... is the strip group 1 containing rubbery polymer.
1 is the largest, and the remaining strips gradually become smaller as they move away from the strip group 11.
For example, styrene containing 27% strip group 11-butadiene, strip group 12-polystyrene made by foaming butadiene resin (for example, K resin manufactured by Phillips Pet. Co., Ltd.) to a density of 0.6 g/cc (for example, Asahi Kasei Corporation) Thread group 13 made of Styron #666) foamed to a density of 0.45 g/cc - Thread group 13 of the same quality as Thread group 12 with a density of 0.3
Consists of strips foamed to g/cc.

Next, what is shown in FIG. 2 is a case where the protrusion group 11 containing the rubbery polymer of the multifoam body 10 is present over the entire outermost periphery of the molded product. For example, strip group 11 - styrenic resin containing 7% rubber (e.g. Cariflex manufactured by Shell Chemical Company)
and polystyrene (for example, the Styron #666 mentioned above) at a weight ratio of 20:80 and foamed to a density of 0.5 g/cc. Group 12 - Polystyrene (for example, the Styron #666 mentioned above) was foamed to a density of 0.35 g/cc. Composed of strips foamed to cc.

Furthermore, in the case of FIG. 3, a part of the group of strips located at the outermost periphery of the multifoam body 10 has a strip 1 made of foamed styrene thermoplastic resin containing a rubbery polymer.
1 and strips 12 that do not contain a rubbery polymer are present alternately, and in the case of FIG.
When the rubbery polymer-containing portion is present without being mixed in a part of each strip 1', in the case of FIG. 5, the strip group 11 located at the outermost periphery is composed of a rubbery polymer. , shows the case where the rubbery polymer is present without being mixed in a portion of each strip of the strip group 11' at a different position.

In the case of these FIGS. 3 to 5, the density of the strips containing the rubbery polymer is large, and the density of the remaining strips is reduced substantially stepwise as described above.

In either case, the foam material had high impact resistance due to its structure, and was able to be implemented as a multifoam material with high fusion strength and little deflection.

The multifoam body according to the present invention having the above-mentioned structure is formed as a plate-shaped peripheral frame A as shown in FIG. forming, utilizing the side of the group of strips containing the rubbery polymer at the outermost periphery, which is the outside of this groove, as a hinge portion h, further forming a bottom plate fitting groove b, and fitting the bottom plate B into this groove b, A box that can be assembled freely can be constructed.

When the polyfoam of the present invention is utilized for the above-mentioned applications, the thin hinge part h, which is outside the bending groove a, is made of strips containing a rubbery polymer, which is unique to polystyrene resin. The rigidity is reduced, the impact resistance is increased, the hinge strength is increased, and it is suitable for preventing cracks from occurring when bent. In addition, the outermost surface is not only less susceptible to scratches, but also convenient in terms of preventing the outermost surface from slipping.
Furthermore, when strips containing a rubbery polymer are alternately present on the outermost periphery (particularly in the third
(Figure), it can produce a very elegant and unique wood texture, and it can provide a novel and good appearance.

In addition, the multifoamed material can be used for various purposes to take advantage of the above-mentioned effects of enhanced impact resistance, less deflection, and high mutual adhesion of the strips.

[Brief explanation of the drawing]

FIGS. 1 to 5 are cutaway perspective views showing embodiments of the multifoam according to the present invention, FIG. 6 is a perspective view showing a peripheral frame as an example of the use of the multifoam according to the present invention, and FIG. It is a perspective view of the box using the peripheral side frame of the previous figure. 11, 11'... Strip group having strips containing a rubbery polymer, 12, 13, 14... Other strip groups.

Claims (1)

[Scope of Claims] 1. A multi-foam body formed by extrusion foaming a large number of styrene-based thermoplastic resin strips and converging them together, in which at least all or some of the strips located on the outermost periphery are It is made of a foamed styrene thermoplastic resin containing 5% by weight or more of a rubbery polymer, and the density of the strips constituting the multifoam is that the foamed styrene thermoplastic resin contains a rubbery polymer. 1. A synthetic resin foam body characterized in that the remaining portion is formed to become smaller in steps as it gets farther away from the group of strips. 2 The rubbery polymer in the strip group located at the outermost periphery is
The synthetic resin foam according to claim 1, which contains butadiene and/or isoprene.