JPH06322023A - Production of brominated polystyrene from recovered polystyrene foam - Google Patents

Abstract

PURPOSE:To effectively utilize a recovered waste polystyrene foam by pulverizing or pelletizing it or reducing its volume. dissolving it in a halogenated hydrocarbon solvent to remove impurities, and brominating the soln. to produce a brominated polystyrene. CONSTITUTION:A recovered polystyrene foam, pref. contg. 80wt.% or higher styrene units and from which foreign matters have been removed, is granulated, then pulverized or pelletized by melt extrusion with an extruder followed by cutting, and dissolved in a halogenated hydrocarbon solvent (e.g. ethylene dichloride). From the resulting soln. are removed solvent-insol. matters by filtration, etc., and pref. by further filtration after adsorbing the insol. matters with an adsorbent, e.g. diatom earth. Polystyrene dissolved in the solvent is brominated with bromine, etc., at -20 to 100 deg.C using a catalyst, e.g. anhydrous aluminum chloride. After the completion of bromination, the reaction soln. is washed with water, neutralized, and distilled to remove the solvent, thus giving a brominated polystyrene.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing brominated polystyrene useful as a flame retardant for combustible resins from recovered expanded polystyrene.

[0002]

BACKGROUND OF THE INVENTION Expanded polystyrene has excellent heat insulating properties, high hardness, small water absorption, excellent water resistance, and excellent impact absorption.
In addition, because it has a beautiful white appearance, is easy to color, and is relatively inexpensive, it is a foamed bead product used for household packaging and fish boxes for fisheries, food containers such as food trays and cup noodles. It is widely used for foamed sheets used for, foamed boards used for building materials mainly composed of heat insulating materials, and loose cushioning materials for packaging cushioning materials.

However, in the case of expanded polystyrene, like other plastics, the treatment and recycling of plastic waste has become an important environmental issue. Moreover, since expanded polystyrene has a large volume as waste, it has become a target for waste treatment, and the related industries have finally begun to start recycling activities together.

[0004]

The present invention is a method of utilizing expanded polystyrene waste, in which the recovered expanded polystyrene is pulverized or reduced in volume, or pelletized, and then dissolved in a halogenated hydrocarbon solvent. The present invention relates to a method for producing brominated polystyrene by removing insoluble matters and then brominating this solution.

The expanded polystyrene used in the present invention includes polystyrene, styrene-maleic anhydride copolymer, polyethylene-styrene graft copolymer, styrene-butanediene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene. A foam such as a copolymer can be used, and it is desirable that the foam contains at least 80% by weight of a styrene component.

The expanded polystyrene may be a molded product, such as a bead foam molded product such as a household packaging material or a fish box for fisheries,
A foam sheet such as a food tray or a tableware container such as cup noodles, a foam board used as a building material such as a heat insulating material, or a loose cushioning material is used. Foamed products that are colored or printed can also be used. Furthermore, a cut product in which the particle diameter of the expanded beads is out of the standard or a burr collected product at the time of molding can be used.

When the recovered expanded polystyrene is, for example, a packaging material or a secondary processed expanded molded article, it often contains foreign substances such as a label, a binding cord, and a rubber material. In addition, the foreign matter is often a component other than expanded polystyrene, a resin material such as polypropylene, polyethylene terephthalate, or vinyl chloride resin and its foam, or a metal body such as aluminum. Therefore, it is necessary to separate and sort the foreign matter prior to the regeneration treatment of the recovered expanded polystyrene.

The recovered expanded polystyrene used in the present invention must be pulverized, reduced in volume, or pelletized, and can be used as a raw material for the brominated polystyrene of the present invention. Although the recovered expanded polystyrene can be used as it is as a raw material for brominated polystyrene without crushing, reducing the volume, or pelletizing, it is bulky when considering transportation, storage, and industrial level production. Since it is large and difficult to handle, it is necessary to increase the specific gravity by crushing, reducing the volume, or pelletizing. The expanded polystyrene after the foreign matter is separated and sorted is roughly pulverized and then finely pulverized to obtain a pulverized product. Alternatively, after coarsely pulverizing, the resin may be melted and extruded by an extruder, and then cut into a resin pellet. Also, in the recovered expanded polystyrene, when the foreign matter as described above is not much mixed, without performing the separation and sorting work, melted in the extruder with the foreign matter mixed,
It is also possible to filter foreign matter with a wire net provided near the exit of the extruder, then extrude from a nozzle die or the like, cut and pelletize. Further, when the recovered expanded polystyrene contains less than a certain amount of foreign matter, it is mechanically coarsely pulverized as it is, and the coarsely pulverized product is finely pulverized again by mechanically applying a shearing force to the finely pulverized material. The heat raises the temperature above the softening temperature of polystyrene to soften it and degasses most of the bubbles to reduce the volume. Further, this degassed finely pulverized product can be pulverized into amorphous resin particles by an impact pulverizer at a softening temperature of polystyrene or lower. For example, 1
The recovered expanded polystyrene mixed with 0% by weight or less of foreign matter is mechanically coarsely pulverized, and the coarsely pulverized product is mechanically pulverized again by applying a shearing force to the coarsely pulverized product. The temperature of the foam is softened, and most of the bubbles are degassed to reduce the volume of the foam to about 1/5 or less.
Further, the deaerated finely pulverized product, which is pulverized into amorphous resin particles by an impact pulverizer at a softening temperature of polystyrene or lower, can be suitably used.

The polystyrene crushed, reduced in volume, or pelletized as described above can be dissolved in a halogenated hydrocarbon solvent and then brominated as it is, but a brominated polystyrene excellent in heat resistance as a flame retardant. In order to obtain the above, it is necessary to remove the solvent insoluble matter by a method such as filtration or centrifugal sedimentation. After dissolution, it is more desirable to add an adsorbent such as diatomaceous earth, silica gel, activated clay, or activated carbon to adsorb the insoluble matter, and then remove by filtration. Halogenated hydrocarbon solvents include methylene chloride, chloroform, carbon tetrachloride, ethylene dichloride, 1,1,
Chlorinated hydrocarbons such as 1-trichloroethane, trichloroethylene, tetrachloroethylene and monochlorobenzene, and brominated hydrocarbons such as methylene bromide and ethylene dibromide are used. When subjected to bromination without removing insoluble matter, anti-adhesion agent at the time of pre-foaming production, which is contained in the recovered expanded polystyrene, a surface treatment agent such as a fusion accelerator and an antistatic agent at the time of molding, A thermally unstable compound is generated by an additive such as a bubble control agent, a bubble stabilizer, a lubricant, and a foaming agent, and the obtained brominated polystyrene becomes inferior in heat resistance, and when blended in a resin as a flame retardant, It causes decomposition and coloring phenomena and reduces the commercial value of molded products.

Next, polystyrene dissolved in the solvent is brominated by a general method. For example, as the brominating agent, bromine, bromine chloride or the like can be used. As the bromination catalyst, anhydrous aluminum chloride, anhydrous ferric chloride, Lewis acid such as antimony trichloride, or aluminum,
Metals such as iron and antimony can be used. The reaction temperature is preferably -20 to 100 ° C. The brominated polystyrene solution after the bromination reaction is neutralized by washing with water to remove the acid component and the inorganic salt, and then the solvent is distilled off or dropped into a poor solvent such as methanol or ethanol to obtain a powder or a solid. Brominated polystyrene can be obtained.

The bromine content of the brominated polystyrene obtained by the method of the present invention is preferably 20 to 70% by weight in consideration of the use of the flammable resin as a flame retardant.

Examples of combustible resins include polystyrene and AB
Examples thereof include styrene resins such as S, polyolefins such as polyethylene and polypropylene, thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyamides such as nylon 66 and nylon 46.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Synthesis of Brominated Polystyrene (Example 1) In a 1 L glass reactor equipped with a stirrer, a condenser, a thermometer, a dropping funnel and a gas absorbing device, 75 g of a volume-reduced polystyrene foam product was recovered. It was dissolved in 750 g of dichloride (hereinafter referred to as EDC), 20 g of diatomaceous earth was further added, the insoluble matter was adsorbed with stirring, and the insoluble matter and diatomaceous earth were removed by Nutsche filtration. After adding 6 g of antimony trichloride to the filtrate and stirring to dissolve it, while maintaining the internal temperature at 15 to 25 ° C. with stirring,
Preconditioned 70% by weight EDC solution of bromine chloride 370
g was added dropwise over 2 hours and further aged at 15 to 25 ° C for 1 hour. After completion of aging, excess bromine chloride was reduced, the EDC solution of brominated polystyrene was neutralized, washed with water, and then dropped into methanol for crystallization. After filtration and drying, 205 g of powdered brominated polystyrene was obtained. The bromine content of the obtained brominated polystyrene was 68.5%. Table 1 shows the results of analysis of the bromine content, thermogravimetric analysis (5%, 10% weight loss temperature), appearance hue, and amount of HBr generated by heating. The analysis was conducted by the following method.

The bromine content is determined by the flask combustion method (JIS
K-7299).・ Thermogravimetric analysis uses Thermoflex 81 as a measuring device.
00 (manufactured by Rigaku) was used. The atmosphere is air (about 5
0 ml / min), and the heating rate was 10 ° C./min.・ Appearance hue is a color difference meter (Minolta camera, CR-
100 type) and determined as values for L, a, and b display systems.・ For the amount of HBr generated by heating, set a heating tube in the electric furnace, connect it to a gas absorption bottle (distilled water 100 ml) equipped with a blowing tube, and pass nitrogen gas (about 50 ml / min) through the electric furnace to sample 3 g. Put in a heating tube and heat at 200 ℃ for 1 hour,
The amount of bromine in the gas absorption water was quantitatively analyzed by the Volhard method.

(Example 2) In Example 1, the solvent E
Bromination in the same manner as in Example 1 except that 750 g of DC was changed to 1,500 g of methylene bromide, antimony trioxide as a catalyst was changed to anhydrous aluminum chloride, and 370 g of an EDC solution of bromine chloride as a brominating agent was changed to 359 g of bromine. 208 g of polystyrene powder was obtained. The analysis results are shown in Table 1.

(Comparative Example 1) In the same manner as in Example 1, except that the EDC solution of polystyrene before bromination was used for bromination without adsorbing and filtering insoluble matter. 213 g of brominated polystyrene powder was obtained. The analysis results are shown in Table 1.

[0018]

[Table 1]

Evaluation of Flame Retardancy and Mechanical Properties of Resin Molded Articles (Examples 3, 4 and Comparative Example 2) Polyethylene terephthalate (TR-4550BH manufactured by Teijin) was obtained in Examples 1, 2 and Comparative Example 1. After mixing brominated polystyrene, antimony trioxide (ATOX-S manufactured by Nippon Mining Co., Ltd.), and glass fiber (3MA429-A manufactured by Asahi Fiber Glass) at the compounding ratio shown in Table 2, a twin-screw extruder (RY-30 manufactured by Rikua). -30-
Immediately after extruding from a nozzle die attached to the tip of the extruder, the extruded strand was cooled in water and pelletized by a pelletizer. After drying the pellets at 120 ° C. for 24 hours, a cylinder temperature of 240 to 265 ° C. and a mold temperature of 140 to 15 are used by using an injection molding machine (F85 made by Crokner).
A test piece was obtained by molding at 0 ° C. The physical properties of the obtained test piece were tested by the following methods. Table 2 shows the test results. -The heat distortion temperature was measured by a method according to JIS K7207. Bending strength was measured by a method according to JIS K7203. -Tensile strength was measured by a method according to JIS K7113. -The combustion test was measured by a method according to UL94 (1/16 inch). The oxygen index was measured by a method according to JIS K7201.

[0020]

[Table 2]

(Examples 5 and 6 and Comparative Example 3) Nylon 6
6 resin (Aramin CM3001N manufactured by Toray), brominated polystyrene obtained in Examples 1 and 2 and Comparative Example 1, antimony trioxide (ATOX-S manufactured by Nihon Seiko Co., Ltd.), glass fiber (03MAFT-2A manufactured by Asahi Fiber Glass) ) To Table 3
After mixing with the compounding ratio shown in, set temperature 2 with a twin-screw extruder.
Immediately after being kneaded at 40 to 260 ° C. and extruded from a nozzle die attached to the tip of the extruder, the extruded strand was cooled in water and pelletized by a pelletizer. After vacuum-drying the obtained pellets at 80 ° C. for 5 hours, using an injection molding machine, the cylinder temperature is 255 to 265 ° C. and the mold temperature is 1
A test piece was obtained by molding at 00 ° C. The obtained test pieces were subjected to a physical property test by the same test method as in Examples 3 and 4 and Comparative Example 2. The results are shown in Table 3.

[0022]

[Table 3]

[0023]

The brominated polystyrene obtained according to the present invention uses recovered expanded polystyrene as a raw material and contributes to society as an effective method of utilizing these wastes. Further, the obtained bromine polystyrene is excellent in appearance hue and heat resistance, and in particular, molded articles obtained from a resin composition in which brominated polystyrene is mixed with a flammable resin have excellent flame retardancy, heat resistance, and mechanical properties. It can be That is, since various additives contained in the recovered expanded polystyrene are removed before bromination,
Since a thermally unstable compound is not generated by bromination, a molded product can be obtained excellently even when it is used as a flame retardant, and the commercial value can be improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinichi Kadono Shinichi Kadano 92 Minohoki-cho, Fukuyama-shi, Hiroshima Manac Co., Ltd.Minooki Plant (72) Inventor Kiyoshi Mishima 92 Minohoki-cho, Fukuyama-shi, Hiroshima Manac Co., Ltd. Minokioki Plant ( 72) Inventor Atsushi Sakabayashi 92 Minooki-cho, Fukuyama-shi, Hiroshima Manac Co., Ltd.Minooki Plant (72) Inventor Akihisa Takahashi 92 Minohoki-cho, Fukuyama-shi, Hiroshima Manac Co., Ltd.

Claims (1)

[Claims] 1. The recovered expanded polystyrene is crushed, reduced in volume, or pelletized, and then dissolved in a halogenated hydrocarbon solvent to remove insolubles, and then this solution is brominated to produce brominated polystyrene. how to.