JP2009120661A - Method for producing reclaimed foaming polystyrene-based resin particle and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing reclaimed foaming polystyrene-based resin particles by which the particles can be formed into a spherical shape even when resin particles having a low MFR value are used, to provide the reclaimed foaming polystyrene-based resin particles produced thereby, and to provide a molded article of the reclaimed foaming polystyrene-based resin obtained by using the particles. <P>SOLUTION: The method for producing the reclaimed foaming polystyrene-based resin particles includes suspending reclaimed polystyrene-based resin particles obtained by heating and melting a used polystyrene-based resin and pulverizing the resultant resin in an aqueous medium, impregnating the reclaimed polystyrene-based resin particles with a polymerization initiator and a styrene-based monomer, polymerizing the impregnated product, and impregnating the resultant particles with a foaming agent, wherein the reclaimed polystyrene-based resin particles are obtained by mixing an organic peroxide with the used polystyrene-based resin so as to be contained therein. The amount of the organic peroxide to be mixed is preferably 0.01-3 pts.wt. based on the 100 pts.wt. used polystyrene-based resin, and the ignition point is preferably ≥300°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing regenerated expandable polystyrene resin particles produced using regenerated polystyrene resin particles obtained by heating and melting a used polystyrene resin, regenerated expandable polystyrene resin particles, and foaming the same. The present invention relates to a recycled expanded polystyrene resin molded product obtained by molding.

  At present, foamed polystyrene resin molded products have been used once and then heat-shrinked and recovered as polystyrene lumps and reused mainly for miscellaneous goods by injection molding and building materials by extrusion molding. ing.

  The volume reduction device that thermally shrinks the expanded polystyrene-based resin molded product has been processed at a high temperature of 260 to 300 ° C., so that the thermal deterioration is large, and the MFR (melt flow rate) value is 1 to 5 g / 10 minutes before the heat reduction. In contrast, it was 10 to 30 g / 10 minutes. For this reason, there existed a problem that the physical property of the molded article at the time of reuse falls remarkably. In recent years, in order to solve this problem, a volume reduction device for processing at 230 ° C. or less by a frictional heat method or the like has been developed and widely introduced, and a recycled resin with a small deterioration of 3 to 7 g / 10 min has been made for an MFR value. Yes.

As a method for producing a recycled foamed polystyrene resin, a method of dispersing recycled polystyrene resin particles obtained by pulverizing a recycled polystyrene resin in a dispersion medium and impregnating a foaming agent (Patent Documents 1 and 2), a recycled polystyrene resin The regenerated polystyrene resin particles obtained by pulverizing are suspended, the polymerization initiator and the styrene monomer are impregnated in the regenerated polystyrene resin particles, and then the styrene monomer is added to perform polymerization. Thereafter, a method for producing recycled expandable polystyrene resin particles impregnated with a foaming agent (Patent Documents 3 and 4) has been proposed.
However, when a recycled resin having a low MFR value processed by a volume reduction device having a low processing temperature, which has been introduced in recent years, is used, the particles do not spheroidize, and blocking occurs in which the particles melt and become a lump at the time of preliminary foaming. There was a problem that the appearance of the molded product was inferior due to the occurrence or the filling property to the mold was lowered.

Japanese Patent No. 3044921 JP-A-5-320406 JP 2002-284916 A Japanese Patent Laid-Open No. 2003-064211

  The present invention relates to a process for producing regenerated expandable polystyrene resin particles that can be made spherical even when resin particles having a low MFR value are used, the regenerated expandable polystyrene resin particles obtained, and the regenerated expanded foam obtained by using the same A polystyrene-based resin molded product is provided.

  In the present invention, regenerated polystyrene resin particles obtained by heating and melting a used polystyrene resin and pulverizing it are suspended in an aqueous medium, and a polymerization initiator and a styrene monomer are added to the regenerated polystyrene resin. It is a method for producing regenerated expandable polystyrene resin particles that are impregnated into particles and polymerized, and impregnated with a foaming agent, wherein the regenerated polystyrene resin particles are mixed with an organic peroxide in the used polystyrene resin, The present invention relates to a process for producing regenerated expandable polystyrene resin particles, which is heated and melted and pulverized.

In the present invention, the amount of the organic peroxide to be mixed is 0.01 to 3 parts by weight with respect to 100 parts by weight of the used polystyrene resin. Regarding the law.
The present invention also relates to a method for producing regenerated expandable polystyrene resin particles, wherein the organic peroxide to be mixed has an ignition temperature of 300 ° C. or higher.
Moreover, this invention relates to the reproduction | regeneration expandable polystyrene resin particle obtained by the manufacturing method of each said reproduction | regeneration expandable polystyrene resin particle.
Furthermore, the present invention relates to a regenerated expanded polystyrene resin molded product obtained by foam molding of the regenerated polystyrene expanded beads obtained by expanding the regenerated expandable polystyrene resin particles.

  According to the present invention, particles can be spheroidized even if a regenerated polystyrene resin having a low MFR value is used, and regenerated expandable polystyrene resin particles with little blocking at the time of prefoaming can be obtained. Recycled expanded polystyrene-based resin molded products with excellent resistance can be obtained.

The production method of regenerated expandable polystyrene resin particles of the present invention, the regenerated expandable polystyrene resin particles obtained, and the regenerated expanded polystyrene resin molded product obtained by foam molding thereof will be described in detail.
The regenerated polystyrene resin particles of the present invention are obtained by thermally reducing the volume of a used expanded polystyrene resin and then mixing the organic peroxide with the used polystyrene resin. For example, together with the organic peroxide It can be produced by crushing a recycled polystyrene resin containing an organic peroxide by hot melt mixing. The used polystyrene-based resin is not limited to what is actually used for some purpose, but includes one that is once molded and not actually used. In the present invention, the polystyrene-based resin is not only a homopolymer of styrene but also a resin mainly composed of styrene, and other monomers such as alkyl acrylates, alkyl methacrylates, vinyl cyanide, etc. Including those copolymerized.

  The method for producing regenerated expandable polystyrene resin particles according to the present invention comprises the steps of suspending regenerated polystyrene resin particles obtained by heat-melting and crushing a used polystyrene resin in an aqueous medium, a polymerization initiator and styrene. The regenerated polystyrene resin particles are impregnated with a polymer monomer to perform polymerization, and a foaming agent is impregnated. At this time, the recycled polystyrene resin particles are characterized in that an organic peroxide is mixed with the used polystyrene resin, heated and melted and pulverized.

  The amount of the organic peroxide used in the production method of the present invention is preferably 0.01 to 3 parts by weight and more preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the used polystyrene resin. If the blending amount is less than 0.01 part by weight, the effect of increasing the MFR value cannot be obtained sufficiently, and if it exceeds 3 parts by weight, it tends to be difficult to adjust the MFR value. From the viewpoint of ease of handling, the organic peroxide is preferably in the form of powder at room temperature (25 ° C.).

The ignition temperature of the organic peroxide used in the present invention is preferably 300 ° C. or higher, more preferably 350 ° C. or higher. If the ignition temperature is less than 300 ° C., there is a risk of ignition due to heat at the time of melting, which is dangerous. The ignition temperature can be measured in accordance with ASTM E659.
Examples of such organic peroxides include dicumyl peroxide (ignition temperature 481 ° C., manufactured by NOF Corporation, trade name Park Mill D, solid), di (2-t-butylperoxyisopropyl) benzene (ignition temperature). 479 ° C., manufactured by NOF Corporation, trade name Perbutyl P, solid), di-t-butyl peroxide (ignition temperature 475 ° C., manufactured by NOF Corporation, trade name Perbutyl D, liquid), t-butyl kumi Dialkyl peroxides with an ignition temperature of 300 ° C. or higher, such as ruperoxide (ignition temperature 490 ° C., manufactured by NOF Corporation, trade name Perbutyl C, liquid form), t-butylperoxy-2-ethylhexanoate (ignition temperature 442 ° C, manufactured by NOF Corporation, trade name perbutyl O, liquid), t-butylperoxy-3,5,5-trimethylhexanoate Peroxy such as ignition temperature 460 ° C., manufactured by NOF Corporation, trade name Perbutyl 355, liquid), t-butyl peroxybenzoate (ignition temperature 490 ° C., manufactured by NOF Corporation, trade name Perbutyl Z, liquid) Esters are preferred, and solids are preferred from the viewpoint of handleability.
The upper limit of the ignition temperature is not limited, but is preferably about 2 to 3 times the decomposition temperature (300 to 400 ° C.) of the used polystyrene resin used, and is about 1000 ° C. or less.

In the present invention, the mixing of the organic peroxide with the used polystyrene resin is performed by, for example, blending the organic peroxide with the coarsely pulverized product of the used polystyrene resin, and then mixing the ribbon blender, V blender, Henschel mixer, and ready-made mixer. It can be carried out by once mixing with a mixer such as a mixer and then melt mixing using a melt extruder or the like.
In the present invention, when used polystyrene resin is melted, air bubbles are adjusted for fatty acid monoamides such as oleic acid amide and stearic acid amide, fatty acid bisamides such as methylene bis stearic acid amide and ethylene bis stearic acid amide, and talc. It can be kneaded as an agent. In this case, the pulverized product and the air bubble adjusting agent are mixed in advance and then extruded. Mixing of the reduced product pulverized product and the air bubble adjusting agent can be performed by a conventionally known means. For example, a blender such as a ribbon blender, a V blender, a Henschel mixer, or a ready game mixer can be used.
The mixing of the bubble regulator can be performed simultaneously with the organic peroxide.

The volume-reduced product of polystyrene resin in the present invention is heat-melted for the purpose of adjusting specific gravity. In this step, the specific gravity of the recycled polystyrene resin is preferably adjusted to 0.6 or more, and more preferably adjusted to 0.9 or more. When the specific gravity is less than 0.6, the dispersion of the resin particles is unstable, so that excessive particles are generated during the polymerization process, and the yield tends to be lowered. Conventionally known means such as an extruder and a hot roll can be used for the thermal melting of the styrene resin.
In the thermal melting of the styrene resin, it is important that the obtained resin is cooled and solidified with no strain remaining or with a small strain. If the resin particles remain strained, the strain is relaxed in the polymerization step and the foaming agent impregnation step and contracts in the stretching direction, and the obtained regenerated expandable styrene resin particles may not be spherical but flat. is there. Therefore, for example, when heat melting is performed using an extruder, it is preferable to melt and extrude while drawing the sheet at approximately the same speed as the extrusion speed.

Although the thing for plastics can apply the grinder used for this invention, if it can grind | pulverize in the range of 0.3-2 mm aiming at polystyrene, the kind of grinder will not necessarily be restrict | limited. .
Recycled polystyrene resin particles having a size other than the purpose obtained by pulverization can be screened and again subjected to a melting step using an extruder or the like.

  In the production method of the present invention, the average diameter of the regenerated polystyrene resin particles used as the core is preferably 0.3 to 2 mm, and more preferably 0.4 to 1.0 mm. If the size of the regenerated polystyrene resin particles exceeds 2 mm, the product shape tends to be difficult to be spherical. If it is less than 0.3 mm, the particle diameter is too small even after polymerization, and regenerated expandable styrene resin particles are obtained. When demand is low.

  The ratio of the regenerated polystyrene resin particles as the core is preferably 20% by weight or more and 70% by weight or less, and preferably 25% by weight or more and 50% by weight or less, with respect to the total amount with the styrene monomer added. More preferably. If the ratio of the regenerated styrene resin particles is less than 20% by weight, the particles are easily united in the polymerization process, and if it exceeds 70% by weight, the strength of the molded product tends to be insufficient.

  In the method for producing regenerated expandable polystyrene resin particles of the present invention, first, the regenerated polystyrene resin particles are suspended in an aqueous medium as a core. Suspension and dispersion in an aqueous medium are usually performed using an apparatus equipped with a stirring blade, and there are no restrictions on the conditions. Moreover, it is preferable from the point of dispersion stability to disperse | distribute with a dispersing agent.

  The dispersant used in the present invention is not particularly limited as long as it is used for suspension polymerization. Examples thereof include organic dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone, and methyl cellulose, and poorly soluble inorganic salts such as magnesium phosphate and tricalcium phosphate. Further, a surfactant can also be used. As this surfactant, any of sodium oleate, sodium dodecylbenzenesulfonate, and other anionic surfactants and nonionic surfactants generally used in suspension polymerization can be used. Among these dispersants, it is preferable to use an organic dispersant from the viewpoint of the stability of the oil droplets of the styrene monomer.

Next, a polymerization initiator and a styrenic monomer are added to the suspension to polymerize. In this case, it is preferable to carry out the polymerization by adding a styrene monomer in which a polymerization initiator is dissolved in advance, impregnating the regenerated polystyrene resin particles as the core, and subsequently adding the styrene monomer.
The styrenic monomer used in the present invention is not only one or two or more styrene derivatives such as styrene, α-methylstyrene, and vinyltoluene, and these and alkyl methacrylates such as methyl methacrylate and ethyl methacrylate. And mixtures with other polymerizable monomers such as vinyl cyanide, vinyl chloride such as acrylic acid alkyl ester having a corresponding alkyl group, acrylonitrile, methacrylonitrile and the like. Further, a crosslinking agent such as divinylbenzene and diallyl phthalate may be used in combination, and these are also included.

  The polymerization initiator used in the polymerization reaction is not particularly limited as long as it is used in the suspension polymerization method. For example, t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, t -One or more organic peroxides such as butyl perbenzoate and azo compounds such as azobisisobutyronitrile can be used.

The polymerization initiator may be added after being dissolved in a solvent, and the regenerated styrene resin particles may be impregnated. In this case, as a solvent for dissolving the polymerization initiator, aromatic hydrocarbons such as ethylbenzene and toluene, aliphatic hydrocarbons such as heptane and octane, and the like are used. When these are used, they are usually used at 3% by weight or less based on the styrene monomer. Although the usage-amount of a polymerization initiator changes with kinds of polymerization initiator, generally the range of 0.1 to 0.5 weight% is preferable with respect to a monomer.
The total molecular weight can be adjusted by adjusting the concentration of the polymerization initiator, using a chain transfer agent together, or both. As the chain transfer agent, conventionally known ones such as octyl mercaptan, dodecyl mercaptan, α-methylstyrene dimer can be used.

As a method of impregnating a styrene monomer into a core composed of regenerated polystyrene resin particles suspended and dispersed in an aqueous medium, a method in which a styrene monomer is added alone, or a styrene monomer in an aqueous medium is used. There is a method in which a monomer, a dispersant, and the like are added and added as a finely dispersed dispersion. Moreover, you may combine these methods.
A method of adding a styrenic monomer, a dispersant, or the like to an aqueous medium to finely disperse is usually performed using an apparatus equipped with a stirring blade. The conditions are not limited, but it is preferable to use a homomixer as a method for finer dispersion. At this time, it is preferable to disperse until the oil droplet diameter of the dispersion liquid in which the styrene monomer is dispersed is equal to or smaller than the particle diameter of the core. When added to an aqueous medium in a state where the oil droplet size is larger than the core particle size, a plurality of resin particles are taken into the oil droplets of the dispersion liquid in which the styrenic monomer is dispersed, and the resin particles are adhered and plasticized. This is because crystallization and coalescence occur and excessive particles are easily generated.

  The addition of the styrenic monomer may be performed separately or continuously. Further, the addition rate varies depending on the capacity, shape, polymerization temperature and the like of the polymerization apparatus and is appropriately selected. The polymerization temperature is preferably in the range of 60 to 105 ° C.

In the present invention, the foaming agent is impregnated by press-fitting the foaming agent into the container during or after the polymerization, raising the temperature to a temperature above the softening point of the regenerated styrene resin particles, and impregnating the resin particles. As the foaming agent, those that do not dissolve or slightly swell resin particles are preferable. Specifically, aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, cyclohexane, cyclopentane, etc. An alicyclic hydrocarbon such as is used. These foaming agents are usually used in an amount of 3 to 15% by weight based on the regenerated styrene resin particles.
The impregnation temperature of the foaming agent is generally 90 ° C. or higher, preferably 100 to 140 ° C., more preferably 100 to 120 ° C. When the impregnation temperature of the foaming agent is less than 90 ° C., the particles are difficult to spheroidize. If it exceeds 140 ° C., coalescence beads are likely to be generated, which is not preferable. After the impregnation with the foaming agent is completed, the expandable styrene resin particles can be obtained by discharging from the polymerization system.

  The regenerated expandable polystyrene resin particles can be coated with a surface coating agent as necessary after impregnation with the foaming agent, discharged from the polymerization system, and dehydrated and dried. As such a coating agent, those used for conventionally known expandable polystyrene resin particles can be applied. For example, zinc stearate, stearic acid triglyceride, stearic acid monoglyceride, castor hardened oil, beef tallow hardened oil, silicones, antistatic agent and the like.

  The regenerated expanded polystyrene resin molded article of the present invention is produced by expansion molding regenerated expandable polystyrene resin particles. In general, regenerated expandable polystyrene resin particles are heated with steam or the like to be pre-foamed to a predetermined bulk density, filled with foam beads that have undergone an aging process, and again heated and foamed with steam or the like, Manufacture foam molded products.

  The molded product of the present invention is excellent in appearance and fusion, has high strength, and can be suitably used for food containers, packing materials, cushioning materials and the like.

Next, the present invention will be described in more detail by way of examples.
Example 1
[Manufacture of nuclei made of regenerated styrene resin particles]
As used polystyrene molded products, foamed styrene resin molded products (molded products obtained from Hitachi Chemical Co., Ltd. High Beads 3SB-TX-7) were shrunk with hot air at 210 ° C., and apparent specific gravity 0.8, large A shrinkage having a thickness of 500 mm × 400 mm × 100 mm and a weight of about 16 kg was obtained. The shrinkage was roughly pulverized with a pulverizer (ZA-560 type pulverizer, trade name of Horai Co., Ltd.) equipped with a 10 mm screen. The coarsely pulverized product obtained at this time had an MFR value of 3.9 g / 10 min, a maximum length of about 10 mm, and a bulk specific gravity of 0.65. Next, 1800 g of this coarsely pulverized product and 5.4 g of dicumyl peroxide (Park Mill D, ignition temperature 481 ° C., manufactured by Nippon Oil & Fats Co., Ltd.) and talc (Hayashi Hayashi) with an average particle diameter of 10 μm were added to a Henschel mixer (FM10B, Mitsui Miike). 18 g of Micro white # 5000) manufactured by Kasei Co., Ltd. and 9.0 g of ethylenebisstearylamide were added and mixed at 2000 rpm for 2 minutes.
Next, 1800 g of this coarsely pulverized product was melt-extruded while pulling the sheet at a cylinder temperature of 230 ° C. and at almost the same speed as the extrusion speed using a vented 30 mm extruder (T-type die, sheet width 300 mm, sheet wall pressure 1 mm).
Furthermore, before cooling and solidification, a slit having a 1 mm interval and a depth of 0.5 mm was provided by a roll horizontally with respect to the extrusion direction. Subsequently, the cut piece of the obtained sheet-like styrene resin was finely pulverized by a pulverizer (VM-16 type pulverizer, Orient product name) equipped with a 1.5 mm screen. The finely pulverized product was classified with a sieve in the range of 0.4 to 1.0 mm to obtain recycled polystyrene resin particles. The regenerated polystyrene resin particles had an MFR value of 15.4 g / 10 minutes.

[Manufacture of regenerated expandable polystyrene resin particles]
In a 5 liter pressure-resistant stirring vessel, 1900 g of deionized water, 1100 g of regenerated polystyrene resin particles (core) obtained by the above method, 12.0 g of tricalcium phosphate, and 0.09 g of sodium dodecylbenzenesulfonate were charged. Subsequently, the inside of the pressure-resistant stirring vessel was purged with nitrogen to adjust the oxygen concentration to 0.5 to 1% by volume. Then, it heated up at 75 degreeC, stirring.
Next, 400 g of deionized water and 1.3 g of polyvinyl alcohol are mixed in a monomer dispersion container, and 200 g of styrene monomer in which 0.2 g of t-butyl peroxide and 2.9 g of benzoyl peroxide are dissolved is added. The styrene monomer was finely dispersed (average monomer oil droplet diameter of 10 to 100 μm) by stirring at 5800 rpm for 120 seconds using a homomixer (made by Tokushu Kika Kogyo Co., Ltd. (Primics Co., Ltd.)). . This styrene monomer dispersion was added to the container over 30 minutes, and then kept warm for 60 minutes, and then heated to 90 ° C.
Thereafter, 900 g of styrene monomer was continuously added at a constant rate (3.0 g / min) over 5 hours. At this time, the inside of the pressure-resistant stirring vessel was purged with nitrogen to keep the oxygen concentration at 0.5 to 1% by volume. At this time, the polymerization rate was 90%.
Next, after adding 2.2 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Subsequently, it was cooled to 100 ° C., and 150 g of pentane (i / n ratio = 2/8, the same as the weight ratio below) as a blowing agent was injected in two portions and held for 10 hours to impregnate the blowing agent.
After cooling to room temperature (25 ° C.), the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. Next, the resin particles are classified with a sieve having an aperture of 0.6 mm to 1.7 mm, and 0.1% by weight of zinc stearate and 0.1% by weight of hardened castor oil are added to the obtained resin particles to cover the surface and regenerate foaming. Styrenic resin particles were obtained.

  The regenerated foamable styrene resin particles obtained were prefoamed to 50 ml / g, and after aging for about 18 hours, molded using a foamed styrene resin molding machine VS-300 manufactured by Daisen Industry Co., Ltd. at a molding pressure of 0.08 MPa. As a result, a molded product was obtained.

(Example 2)
[Manufacture of nuclei made of regenerated styrene resin particles]
Recycled polystyrene resin particles were obtained in the same manner as in Example 1 except that 5.4 g of dicumyl peroxide used in Example 1 was changed to 2.7 g.
The regenerated polystyrene resin particles had an MFR value of 7.1 g / 10 minutes.
[Manufacture of regenerated expandable polystyrene resin particles]
Regenerated expandable polystyrene resin particles and molded products thereof were obtained in the same manner as in Example 1 using the regenerated polystyrene resin particles (nuclei) obtained by the above method.

(Comparative Example 1)
[Manufacture of nuclei made of recycled polystyrene resin particles]
Recycled polystyrene resin particles were obtained in the same manner as in Example 1 except that dicumyl peroxide was not used in Example 1.
The regenerated polystyrene resin particles had an MFR value of 4.6 g / 10 minutes.
[Manufacture of regenerated expandable polystyrene resin particles]
Regenerated expandable polystyrene resin particles and molded products thereof were obtained in the same manner as in Example 1 using the regenerated polystyrene resin particles (nuclei) obtained by the above method.

Table 1 shows the evaluation results of the regenerated expandable polystyrene resin particles obtained in Examples 1 and 2 and Comparative Example 1. The characteristic evaluation method in Table 1 is as follows.
(1) MFR
Conforms to JIS K7210, measuring temperature 200 ° C
(2) Ignition temperature Compliant with ASTM E659 method A 500 ml flask was set to an appropriate temperature with an electric furnace, 0.1 ml of a sample was added, and the lowest temperature at which ignition was observed was defined as the ignition temperature.
(3) Blocking Blocking (wt%)
= (Weight of lump where particles are united / Weight of beads put into foaming machine) × 100
(4) Surface smoothness The surface smoothness of a molded product is as follows. First, the surface of the molded product is thinly coated with printing ink with a roller, and this surface portion is applied to an image processing apparatus to determine the area of the black portion relative to the total area. Rate.
(5) Particle Shape The shape of the obtained recycled polystyrene resin particles was observed with a microscope, and the spherical one was evaluated as “spherical” and the flat one was evaluated as “flat”.

  As can be seen from Table 1, according to the present invention, the regenerated expandable polystyrene resin particles can be made spherical even if a regenerated resin having a low MFR value is used, and the regenerated expandable polystyrene resin particles have little blocking during pre-foaming, and are regenerated with excellent appearance. A polystyrene resin foam molded product is obtained.

Claims (5)

Recycled polystyrene resin particles obtained by heat-melting and pulverizing used polystyrene resin are suspended in an aqueous medium, and the recycled polystyrene resin particles are impregnated with a polymerization initiator and a styrene monomer. Is a method for producing regenerated expandable polystyrene resin particles that are polymerized and impregnated with a foaming agent, wherein the regenerated polystyrene resin particles are mixed with an organic peroxide in the used polystyrene resin, heated and melted, A method for producing regenerated expandable polystyrene resin particles, characterized by being pulverized and contained. The amount of the organic peroxide to be mixed is 0.01 to 3 parts by weight with respect to 100 parts by weight of the used polystyrene resin, The production of regenerated expandable polystyrene resin particles according to claim 1, Law. The method for producing regenerated expandable polystyrene resin particles according to claim 1 or 2, wherein the organic peroxide to be mixed has an ignition temperature of 300 ° C or higher. Regenerated expandable polystyrene resin particles obtained by the method for producing regenerated expandable polystyrene resin particles according to claim 1, 2 or 3. A regenerated expanded polystyrene resin molded product obtained by expansion molding of regenerated polystyrene expanded beads obtained by expanding the regenerated expandable polystyrene resin particles according to claim 4.