JP3580317B2 - Method for producing flame-retardant expanded styrene resin molded article having voids - Google Patents

Description

【００１８】
なお圧縮強度はＪＩＳ−Ａ９５１１に準拠して測定し、難燃性の発現までの日数は、ＪＩＳ−Ｋ７２０１に準拠して測定し、空隙率は、製造された上記ポリスチレン発泡成形体から１００ｍｍ×１００ｍｍ×３００ｍｍの大きさに切り出し、内寸法が縦１５０ｍｍ×横４００ｍｍの水槽の水面下に沈めた際の水面が上昇した高さｈｍｍを測定し、
（３００×１００×１００−１５０×４００×ｈ）÷（３００×１００×１００）×１００（％）
により算出した。
【００１９】
（実施例２〜８）
予備発泡前の発泡性ポリスチレン樹脂小片中の揮発分含有量及び成形圧力を表１のように変更した以外は実施例１と同様に行った。結果を表１に示す。
（比較例１〜８）
予備発泡前の発泡性ポリスチレン樹脂小片中の揮発分含有量、及び成形圧力を表１のように変更した以外は実施例１と同様に行った。結果を表１に示す。
【００２０】
【発明の効果】
本発明は上記の如くであって、予備発泡体小片の予備発泡前の揮発分含有量を一定範囲におさえるため、高い空隙率を有すると共に空隙率のコントロールが行いやすく、かつ、難燃性の発現が早い発泡成形体を製造することができる。
【図面の簡単な説明】
【図１】本発明で用いられる予備発泡体小片の変形例である。（ａ）鞍状、（ｂ）リング状、（ｃ）十字架状、（ｄ）リング状、（ｅ）波打った棒状、（ｆ）曲玉状[0001]
[Industrial applications]
The present invention relates to a method for producing a flame-retardant expanded styrene resin molded article having voids used as civil engineering and building materials such as a cushioning material for packaging, a drainage material, a heat insulating material, a sound absorbing material, and the like. The present invention relates to a method for producing a flame-retardant expanded styrenic resin molded article having a high porosity, easy to control the porosity, and exhibiting a flame-retardant effect quickly.
[0002]
[Prior art]
Conventionally, foamed styrene with voids formed by heating and fusing non-spherical foam pieces made of styrene resin such as polystyrene as civil engineering and building materials such as cushioning materials for packing, drainage materials, heat insulation materials, sound absorbing materials, etc. A resin-based molded body is used.
[0003]
[Problems to be solved by the invention]
In these applications, the molded article preferably has flame retardancy, but the foaming agent (usually 6.5 to 8% by weight before prefoaming) required to fuse the foam pieces is difficult. There is a problem that the onset of the effect of the fuel agent is delayed, and the porosity is extremely low because the foam pieces prefoamed by the foaming agent are further foamed, and it is difficult to control the porosity.
[0004]
The present invention solves the conventional problems as described above, has a high porosity and is easy to control the porosity, and has a fast expression of a flame-retardant effect. It is an object of the present invention to provide a method for manufacturing a molded article.
[0005]
[Means for Solving the Problems]
The present inventors have conducted extensive studies and found that, even if the content of the foaming agent before the prefoaming of the prefoamed pieces is reduced, if the content is within a specific range, the foamed pieces are unexpectedly fused together. The inventor has found that it is possible to produce a molded article having a high porosity without lowering the degree, and has achieved the above object by adopting the following constitution.
[0006]
That is, the production method of the present invention fills a non-spherical pre-foamed small piece made of a styrene-based resin containing a flame retardant into a cavity of a mold, and then heats after performing mold clamping to form a pre-foamed small piece. in the method and the surface together are fused together to produce foamed molded article having voids, volatile content before prefoaming of the preliminary foam pieces is 3.5 to 5.0 wt%, the foamed molded product Is characterized by producing a foam molded article having a porosity of 15 to 45% .
[0007]
The styrene resin used in the present invention means a styrene homopolymer and a copolymer of at least 50% by weight, preferably at least 75% by weight of styrene and another copolymerizable monomer. I do. Examples of the copolymerizable monomer include ethylenically unsaturated monomers such as α-methylstyrene, nuclear halogenated styrene, nuclear alkylated styrene having 1 to 4 carbon atoms in the alkyl group, acrylonitrile, N-vinyl compounds such as methacrylonitrile, esters of alcohols having 10 to 10 carbon atoms with acrylic acid, methacrylic acid or fumaric acid, butadiene, N-vinylcarbazole, N-vinylpyridine, or butanediol Examples include divinyl compounds such as acrylate and divinylbenzene.
[0008]
The styrene resin used in the present invention contains a flame retardant. As the flame retardant, a halogen compound such as bromine or chlorine, an inorganic compound, or the like is used. Further, a known flame retardant auxiliary such as peroxide and antimony trioxide may be used in combination. The amount of the flame retardant to be contained is preferably 0.4 to 3% by weight, and if it is less than 0.4% by weight, a sufficient flame retardant effect cannot be obtained. In other words, there is a problem that the material is melted at the time of molding and the molding becomes difficult.
[0009]
The blowing agent used in the present invention may be any of those used in the production of ordinary expanded polystyrene, that is, aliphatic or alicyclic hydrocarbons having a boiling point of up to about 90 ° C. Used are those which do not dissolve but can be uniformly dispersed therein, for example, propane, n- or i-butane, n-, i- or neopentane, hexane, cyclohexane, or a mixture thereof.
[0010]
The foaming agent may be added by any means at any time, for example, during the polymerization of the styrene monomer, or may be added to and mixed with the styrene resin in an extruder. It is essential to add the small pieces so that the volatile content before prefoaming is 3.5 to 5.0% by weight, preferably 4.0 to 5.0% by weight. If the volatile matter content is less than 3.5% by weight, the foamed molded article does not have the strength to be practically used, and if it exceeds 5.0% by weight, the expression of the flame retardant effect is delayed, and a sufficient porosity cannot be obtained. .
[0011]
The volatile matter content (VC%) in the foamable styrene-based resin pieces before preliminary foaming refers to the weight (W ₁ g) of the foamable styrene-based resin pieces and heating the small pieces at 120 ° C. for 5 hours. Then, the mixture was allowed to cool in a desiccator (2 hours), dried, and the weight (W ₂ g) was measured. The loss on drying (A%) was calculated as A = (W ₁ −W ₂ ) / W ₁ × 100. And a value obtained by subtracting the water content (WC%) calculated by the known Karl Fischer method from the loss on drying (A%).
[0012]
The styrenic resin may further contain other additives such as dyes, pigments, fillers, and stabilizers.
The flame retardant, foaming agent and other additives may be added during suspension polymerization of a known styrene resin, or may be post-impregnated in a styrene resin, or an extruder for producing a non-spherical foamable styrene resin small piece. And kneaded in the styrene resin.
[0013]
The foamable styrene-based resin small pieces in the present invention are formed into a non-spherical shape using a normal extruder, that is, a disc shape, a column shape, a saddle shape as shown in FIG. (FIGS. (B) and (d)), a cross (FIG. (C)), a wavy rod (FIG. (E)), and a curved ball (FIG. (F)). Extruded and molded. In order to further increase the porosity, the length of the longest portion is preferably 2 cm or more.
[0014]
In addition, when adding a foaming agent in an extruder, it is preferable to use a two-stage tandem system in which mixing and cooling of the foaming agent are performed by separate extruders from the viewpoint of production efficiency.
The extruded non-spherical expandable styrene-based resin pieces are pre-foamed by a normal pre-foaming method to form pre-foamed pieces, and the pre-foamed pieces are filled into a cavity of a normal foam molding die. Next, after performing mold clamping, heating is performed using steam at 100 to 150 ° C., and the surfaces of the pre-foamed pieces are fused to each other to produce a foam molded article having voids.
[0015]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.
(Example 1)
Flame retardant-containing foam obtained by adding 3.1 parts by weight of n-butane as a foaming agent and 0.6 parts by weight of hexabromocyclododecane as a flame retardant to 100 parts by weight of a styrene monomer and subjecting to suspension polymerization. Is melt-kneaded with an extruder having a diameter of 65 mm, a foamed polystyrene resin strand is extruded into cooling water from a die nozzle attached to the tip of the extruder, and subsequently cut by a rotating cutter blade. In this way, a large number of elliptic plate-like foamable polystyrene resin pieces were produced. At that time, n-butane was supplied from the middle of the extruder in an amount corresponding to 2.2 parts by weight with respect to 100 parts by weight of the resin, so that the volatile matter content of the expandable polystyrene resin pieces became 5.0% by weight. Adjusted to be.
[0016]
This foamable polystyrene resin piece is foamed to 25 g / 1 using a preliminary foaming machine (YB-IB manufactured by Mie Kikai Tekko Co., Ltd.) to form a saddle-shaped piece. After aging for 24 hours, a 400 mm × 400 mm × 100 mm cavity is formed. The foamed molded product was manufactured by heating with steam of 0.4 kg / cm ² for 60 seconds in a foamed molding machine having a shape.
The compression strength, porosity, and days until expression of flame retardancy of the foamed molded article were measured. The results are shown in Table 1.
[0017]
[Table 1]

[0018]
The compressive strength was measured in accordance with JIS-A9511, the number of days until the development of flame retardancy was measured in accordance with JIS-K7201, and the porosity was 100 mm × 100 mm from the manufactured polystyrene foam molded article. Cut out to a size of × 300 mm, the height of the water surface when it was submerged under the surface of a water tank of 150 mm in length × 400 mm in width was measured, hmm,
(300 × 100 × 100-150 × 400 × h) ÷ (300 × 100 × 100) × 100 (%)
Was calculated by
[0019]
(Examples 2 to 8)
The procedure was performed in the same manner as in Example 1 except that the volatile content and the molding pressure in the foamable polystyrene resin pieces before the prefoaming were changed as shown in Table 1. Table 1 shows the results.
(Comparative Examples 1 to 8)
The procedure was performed in the same manner as in Example 1 except that the volatile content in the foamable polystyrene resin pieces before the prefoaming and the molding pressure were changed as shown in Table 1. Table 1 shows the results.
[0020]
【The invention's effect】
The present invention is as described above, in order to keep the volatile content before the pre-foaming of the pre-foamed pieces in a certain range, it is easy to control the porosity while having a high porosity, and flame-retardant It is possible to produce a foamed molded article having a rapid expression.
[Brief description of the drawings]
FIG. 1 is a modified example of a pre-foamed piece used in the present invention. (A) saddle shape, (b) ring shape, (c) cross shape, (d) ring shape, (e) wavy rod shape, (f) curved ball shape

Claims (1)

A non-spherical pre-foamed small piece made of a styrene-based resin containing a flame retardant is filled in the cavity of the mold, and then heated after performing mold clamping to fuse the surfaces of the pre-foamed small pieces to each other to form a void. Wherein the volatile content of the pre-foamed pieces before the pre-foaming is 3.5 to 5.0% by weight, and the porosity of the foamed product is 15 to 45%. A method for producing a flame-retardant expanded styrenic resin molded article having voids.

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