Method for producing regenerated foamable styrene resin particles, regenerated foamable styrene resin particles, regenerated pre-foamed styrene resin particles, and regenerated styrene resin foam molded article

Abstract

Provided are: a method for producing regenerated foamable styrene-based resin particles which have a high degree of environmental contribution, are suppressed in undesirable odor unique to recycled materials, can exhibit good spheroidization, and have excellent moldability; and regenerated foamable styrene-based resin particles obtained by this production method. Also provided are: regenerated pre-expanded styrene-based resin particles obtained from the regenerated foamable styrene-based resin particles; and a regenerated styrene-based resin foam molded article molded from the regenerated pre-expanded styrene-based resin particles. A method for producing expandable styrene resin particles according to an embodiment of the present invention is a method for producing regenerated expandable styrene resin particles by pressing and impregnating a suspension containing a regenerated styrene resin raw material (A) and a dispersant with a foaming agent, the method being characterized in that: Tg is the glass transition temperature of the regenerated styrene resin raw material (A); when T1 is the temperature at which the blowing agent is pressed in and T2 is the temperature at which the blowing agent is impregnated, T1 is in the range of (Tg-50 DEG C) or more and (Tg + 40 DEG C) or less, and T2 is in the range of (Tg-50 DEG C) or more and (Tg + 40 DEG C) or less.

Description

Technical Field

[0001] The present invention relates to a method for producing recycled foamable styrene resin particles, recycled foamable styrene resin particles, recycled pre-foamed styrene resin particles and recycled styrene resin foamed molded products. Background Art

[0002] Foam moldings are widely used in heat insulating materials used in houses and automobiles, thermal insulation materials used in building materials, etc., filling materials (banking materials) used in foamed styrene civil engineering, and transportation packaging materials such as fish boxes and food containers, cushioning materials, etc., due to their light weight and excellent thermal insulation and mechanical strength. Among them, in-mold foam moldings made of foamable particles (representatively, foamable polystyrene resin particles or pre-foamed styrene resin particles obtained by pre-foaming) as raw materials are mostly used. This foam molding is composed of a plurality of foamable particles fused to each other.

[0003] On the other hand, the amount of plastic waste is increasing year by year. Most of the plastic waste is disposed of by incineration, landfill, etc., but environmental pollution, global warming, and the shortage of landfill treatment plants are becoming serious social problems. Therefore, there is a strong demand in society for the reuse of plastic waste, and in view of the implementation of the Home Appliance Recycling Law, various studies have been conducted on the recycling of plastic waste. At present, a variety of recycling methods have been proposed, and from the perspective of resource circulation and reducing environmental burdens, material recycling that reuses plastic waste as plastic components of products has attracted much attention, and this material recycling has also been studied for styrene resin foam moldings.

[0004] As a material recycling method for styrene resin foam molded products, several methods have been proposed in the past, in which a recycled raw material is melted and extruded to produce recycled pellets, and a foaming agent is impregnated into the pellets to obtain regenerated foamable styrene resin particles.

[0005] There have been reports of methods for obtaining regenerated foamable styrene resin particles by impregnating a recycled resin pellet molded from a recycled product of a styrene resin foam molded body with a foaming agent at a temperature of 100° C. to 140° C. (Patent Documents 1 and 2). There have also been reports of methods for obtaining regenerated foamable styrene resin particles by impregnating a recycled resin pellet molded from a recycled product of a styrene resin foam molded body with a foaming agent at a temperature of 90° C. to 130° C. (Patent Document 3).

[0006] There has been reported a method for obtaining recycled foamable styrene resin particles by pressing a foaming agent into recycled resin pellets molded from a recovered product of a styrene resin foam molding at a temperature of 95°C to 130°C, then impregnating the pellets (in the embodiment, the pressing temperature is 100°C and the impregnation temperature is 118°C), and then forming the pellets into a spherical shape at 110°C to 130°C (Patent Document 4).

[0007] A method has been reported in which a styrene monomer is added to a recycled resin pellet molded from a recycled product of a styrene resin foamed molded body, polymerized at 60°C to 105°C, and then a foaming agent is pressed into the pellet (in the example, the pressing temperature is 100°C), and then the foaming agent is impregnated at an impregnation temperature of 100°C or higher to obtain recycled foamable styrene resin particles (the content ratio of the recycled resin pellet is 70% by mass or less) (Patent Document 5). In addition, a method has been reported in which a styrene monomer is added to a recycled resin pellet molded from a recycled product of a styrene resin foamed molded body, polymerized at 60°C to 105°C, and then a foaming agent is pressed into the pellet (in the example, the pressing temperature is 100°C), and then the foaming agent is impregnated at an impregnation temperature of 100°C to 140°C to obtain recycled foamable styrene resin particles (the content ratio of the recycled resin pellet is 20% to 70% by mass) (Patent Document 6). In addition, there has been a report on a method for obtaining recycled foamable styrene resin particles (containing 30% to 70% by mass of recycled resin pellets) by adding styrene monomer to recycled resin pellets molded from a recovered product of a styrene resin foam molding, polymerizing the particles at 60°C to 105°C, and then pressing a blowing agent into the particles (in the example, the pressing temperature is 100°C), followed by impregnation of the blowing agent into the particles (in the example, the impregnation temperature is 115°C). It has been reported that a flame retardant may be impregnated when the blowing agent is impregnated (Patent Document 7). In addition, there has been reported a method of obtaining recycled foamable styrene resin particles (the content of recycled resin pellets is 20% to 70% by mass) by adding styrene monomer to recycled resin pellets molded from a recovered product of a styrene resin foam molding, polymerizing the particles at 60°C to 105°C, and then pressurizing a foaming agent (in the embodiment, the injection temperature is 100°C), and then impregnating the foaming agent at an impregnation temperature of 90°C or above (Patent Document 8).

[0008] However, conventional recycled foamable styrene resin particles, especially compared to foamable styrene resin particles that do not use recycled raw materials, have a problem of having an odor peculiar to recycled materials. Also, the recycled pre-foamed styrene resin particles and recycled styrene resin foam moldings obtained therefrom also have a problem of producing an odor peculiar to recycled materials to a degree that can be sensed by humans.

[0009] In addition, the regenerated foamable styrene resin particles obtained by the conventional method have the following problems: the particle shape deviates from the spherical shape, or the filling property into the molding die deteriorates, or the surface elongation of the molded body deteriorates, or the fusion rate between the foamed particles of the molded body decreases.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent No. 3044942

[0013] Patent Document 2: Japanese Patent No. 4234832

[0014] Patent Document 3: Japanese Patent No. 4261676

[0015] Patent Document 4: Japanese Patent No. 6788428

[0016] Patent Document 5: Japanese Patent No. 4052193

[0017] Patent Document 6: Japanese Patent Application Publication No. 2006-160905

[0018] Patent Document 7: Japanese Patent No. 4912567

[0019] Patent Document 8: Japanese Patent No. 5128246 Summary of the invention

[0020] Problem that the invention aims to solve

[0021] The present invention is made to solve the above-mentioned existing problems, and its main purpose is to provide a method for manufacturing recycled foamable styrene resin particles with high environmental contribution, suppressed peculiar odor of recycled materials, good spheroidization and excellent formability. In addition, its main purpose is to provide recycled foamable styrene resin particles obtained by this manufacturing method, with suppressed peculiar odor of recycled materials, good spheroidization and excellent formability. In addition, its main purpose is to provide recycled pre-foamed styrene resin particles obtained from such recycled foamable styrene resin particles. In addition, its main purpose is to provide a recycled styrene resin foamed molded body molded from such recycled pre-foamed styrene resin particles.

[0022] Solutions for solving problems

[0023] [1] The method for producing recycled foamable styrene resin particles according to an embodiment of the present invention is a method for producing recycled foamable styrene resin particles by injecting a foaming agent into a suspension containing a recycled styrene resin raw material (A) and a dispersant to impregnate the suspension, wherein the glass transition temperature of the recycled styrene resin raw material (A) is set to Tg, the temperature at which the foaming agent is injected is set to T1, and the temperature at which the foaming agent is impregnated is set to T2, wherein T1 is within the range of (Tg-50°C) to (Tg+40°C), and T2 is within the range of (Tg-50°C) to (Tg+40°C).

[0024] [2] In the method for producing recycled foamable styrene resin particles described in [1] above, the above T1 can be in the range of above (Tg-50°C) and below (Tg+40°C), and the above T2 can be in the range of above (Tg-50°C) and below (Tg+10°C).

[0025] [3] In the method for producing regenerated expandable styrene resin particles according to [2] above, the dispersant may be at least one selected from the group consisting of organic dispersants and sparingly soluble inorganic salts.

[0026] [4] In the method for producing recycled foamable styrene resin particles described in [1] above, the above T1 can be in the range of (Tg+10°C) to (Tg+30°C), and the above T2 can be in the range of (Tg+10°C) to (Tg+30°C).

[0027] [5] In the method for producing regenerated expandable styrene resin particles described in [4] above, the dispersant may be magnesium pyrophosphate.

[0028] [6] In the method for producing recycled foamable styrene resin particles according to any one of [1] to [5] above, the blending ratio of the dispersant to 100 parts by mass of the recycled styrene resin raw material (A) may be 0.1 parts by mass to 2 parts by mass.

[0029] [7] In the method for producing regenerated expandable styrene resin particles according to any one of [1] to [6], the suspension may contain a surfactant.

[0030] [8] In the method for producing recycled foamable styrene resin particles described in [7] above, the blending ratio of the above surfactant to 100 parts by mass of the above recycled styrene resin raw material (A) may be 0.005 to 0.1 parts by mass.

[0031] [9] In the method for producing recycled foamable styrene resin particles described in any one of [1] to [8] above, as the above-mentioned recycled styrene resin raw material (A), polymer particles obtained by adding styrene monomers to a suspension containing recycled styrene resin raw material particles (a) and polymerizing them can be used.

[0032]

[10] In the method for producing recycled expandable styrene resin particles according to any one of [1] to [8] above, the recycled styrene resin raw material particles (a) may be used as the recycled styrene resin raw material (A).

[0033]

[11] In the method for producing recycled foamable styrene resin particles described in [9] or

[10] above, the recycled styrene resin raw material particles (a) can be at least one selected from extruded strand pellets, underwater cut pellets and hot cut pellets, the extruded strand pellets are obtained by extruding used styrene resin using an extruder and cutting the strands, the underwater cut pellets are obtained by an underwater cutting method in which the used styrene resin is extruded by an extruder and cut in water at the same time, and the hot cut pellets are obtained by a hot cutting method in which the used styrene resin is cut and cooled immediately after it comes out of the die of the extruder.

[0034]

[12] The regenerated expandable styrene resin particles according to an embodiment of the present invention are obtained by the method for producing regenerated expandable styrene resin particles according to any one of [1] to

[11] .

[0035]

[13] The recycled pre-foamed styrene resin particles according to an embodiment of the present invention are recycled pre-foamed styrene resin particles obtained by pre-foaming the recycled foamable styrene resin particles described in

[12] above, wherein the volume expansion ratio of the pre-foaming is 2 to 150 times.

[0036]

[14] The recycled styrene resin foamed molded product according to an embodiment of the present invention is obtained by molding the recycled pre-foamed styrene resin particles described in

[13] above.

[0037]

[15] The recycled styrene resin foamed molded body described in

[14] above can be at least one selected from a molded body for thermal insulation material, a molded body for heat preservation material, a molded body for filling material, a molded body for food container, a molded body for industrial product container, a molded body for cushioning material and a molded body for packaging material.

[0038]

[16] The recycled pre-expanded styrene resin particles described in

[13] above may be at least one selected from the group consisting of a core material and an aggregate of a mat.

[0039] Effects of the Invention

[0040] According to the present invention, a method for producing recycled foamable styrene resin particles having high environmental contribution, suppressed peculiar smell of recycled materials, good spheroidization and excellent formability can be provided. In addition, recycled foamable styrene resin particles obtained by the production method having suppressed peculiar smell of recycled materials, good spheroidization and excellent formability can be provided. In addition, recycled pre-foamed styrene resin particles obtained from the recycled foamable styrene resin particles can be provided. In addition, a recycled styrene resin foamed molded body molded from the recycled pre-foamed styrene resin particles can be provided. DETAILED DESCRIPTION

[0041] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0042] In the present specification, the term "(meth)acrylic" refers to acrylic and / or methacrylic, and the term "(meth)acrylate" refers to acrylate and / or methacrylate.

[0043] 《《A. Method for producing recycled foamable styrene resin particles》》

[0044] In the method for producing regenerated expandable styrene resin particles according to the embodiment of the present invention, a foaming agent is pressed into and impregnated into a suspension containing a regenerated styrene resin raw material (A) and a dispersant.

[0045] 《A-1. Recycled styrene resin raw material (A)》

[0046] Examples of the recycled styrene resin raw material (A) used in the method for producing recycled foamable styrene resin particles according to the embodiment of the present invention include recycled styrene resin raw material particles, recycled foamable styrene resin particles, recycled pre-foamed styrene resin particles, and recycled styrene resin foamed molded products.

[0047] Recycled styrene resin raw material particles are used styrene resins, which may be pellets, shrinkage products, or melts thereof. Recycled foamable styrene resin particles are particles in which a foaming agent is pressed / impregnated into recycled styrene resin raw material particles. Recycled pre-foamed styrene resin particles are particles formed by pre-foaming recycled foamable styrene resin particles. Recycled styrene resin foam moldings are recycled styrene resin foam moldings formed from recycled pre-foamed styrene resin particles.

[0048] As preferred embodiments of the recycled styrene resin raw material (A) used in the method for producing recycled foamable styrene resin particles according to the embodiment of the present invention, the following two embodiments can be cited:

[0049] (Embodiment 1 of Recycled Styrene Resin Raw Material (A)) As the recycled styrene resin raw material (A), an embodiment in which polymer particles obtained by adding a styrene monomer to a suspension containing recycled styrene resin raw material particles (a) and polymerizing the resulting particles are used;

[0050] (Embodiment 2 of Recycled Styrene-Based Resin Raw Material (A)) An embodiment in which recycled styrene-based resin raw material particles (a) are used as the recycled styrene-based resin raw material (A).

[0051] The recycled styrene resin raw material particles (a) may be one kind or two or more kinds.

[0052] As the material of the recycled styrene resin raw material particles (a), any and appropriate recycled styrene resins can be used within the range that does not impair the effects of the present invention. Examples of such recycled styrene resins include recycled materials of plastic materials used in, for example, foamed styrene (molding molded articles, block molded articles, etc.), foamed sheets (tray containers, sheet scraps, etc.), home appliances, packaging containers, cushioning beads, etc.

[0053] The recycled styrene resin raw material particles (a) may contain any and appropriate other recycled resins other than the recycled styrene resin within the scope that does not impair the effect of the present invention. Examples of such other recycled resins include AS resin, ABS resin, HIPS (high impact polystyrene); polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC); polyamide resins such as nylon (PA); polyolefin resins such as polyethylene (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), EVA (ethylene-vinyl acetate copolymer); recycled resins. The other resins may be only one or more. It should be noted that in this specification, recycled resins consisting only of AS resin, recycled resins consisting only of ABS resin, and recycled resins consisting only of HIPS (high impact polystyrene) are not included in the scope of the above-mentioned recycled styrene resins.

[0054] As the recycled styrene resin raw material pellets (a), molded products produced under the trade name "EPSREM" manufactured by Sekisui Chemicals Co., Ltd. can be used.

[0055] As the recycled styrene resin raw material particles (a), a crushed product obtained by heating and / or reducing the volume of a used styrene resin and crushing a recycled resin can be used. As the recycled styrene resin raw material particles, it can be a pellet obtained by extruding and granulating the crushed product, or it can be a pellet obtained by further crushing the pellet. Alternatively, it can be a pellet obtained by reducing the volume and recovering the pellet using a solvent such as limonene.

[0056] The recycled styrene resin raw material particles (a) are preferably pellets obtained by melt extrusion. Typically, the melt extrusion method is a method in which a crushed product, an ingot, a foamed particle, etc. of a used styrene resin is supplied to a resin supply device, melted in the resin supply device, extruded from a small hole of a die provided at the front end of the resin supply device, and then cooled to obtain pellets.

[0057] The pellets obtained by the melt extrusion method are preferably at least one selected from extruded strand pellets, underwater cut pellets and hot cut pellets. The extruded strand pellets are obtained by extruding used styrene resins through an extruder and cutting them into strands. The underwater cut pellets are obtained by an underwater cutting method in which the used styrene resins are extruded through an extruder and cut in water at the same time. The hot cut pellets are obtained by a hot cutting method in which the used styrene resins are cut and cooled immediately after coming out of the die of the extruder.

[0058] As the recycled styrene resin raw material pellets (a), the pellets obtained by the above-mentioned melt extrusion method can be used directly, or in order to make pellets of a smaller size, they can be made into so-called "micro pellets" by melt extrusion method etc. again.

[0059] The recycled styrene resin raw material particles (a) may be styrene resin shrunken or melted by coarsely crushing used styrene resin to an appropriate size as required, and then subjecting the styrene resin to heat shrinkage, compression-based bubble collapse shrinkage, friction heat-based shrinkage, melting, etc. Used styrene resins include, for example, molded articles obtained by molding a foamable styrene resin, and resins obtained by heating and foaming the foamable styrene resin.

[0060] The recycled styrene resin raw material particles (a) may contain fine powder inorganic substances and / or organic lubricants, which typically function as bubble regulators.

[0061] Examples of fine powder inorganic substances include talc, calcium carbonate, and silicon dioxide. Talc is typically a mixture containing silicon oxide and magnesium oxide as main components and containing trace amounts of aluminum oxide, iron oxide, and the like.

[0062] The average particle size of the fine powder inorganic substance is preferably 100 μm or less, more preferably 30 μm or less. If the average particle size of the fine powder inorganic substance exceeds 100 μm, the effect of reducing the cell size of the regenerated pre-expanded styrene resin particles may be reduced.

[0063] The content ratio of the fine powder inorganic substance is preferably 0.1 mass % to 5 mass %, and more preferably 0.5 mass % to 2 mass % relative to the recycled styrene resin raw material particles (a). If the content ratio of the fine powder inorganic substance relative to the recycled styrene resin raw material particles (a) is less than 0.1 mass %, the effect of reducing the bubble size of the recycled pre-foamed styrene resin particles may be reduced. If the content ratio of the fine powder inorganic substance relative to the recycled styrene resin raw material particles (a) exceeds 5 mass %, the bubble size of the recycled pre-foamed styrene resin particles may be extremely reduced, and the recycled pre-foamed styrene resin particles may melt during molding, and the appearance of the molded product may deteriorate.

[0064] Examples of organic lubricants include liquid paraffin, polyethylene glycol, silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane, higher fatty acid bisamides such as methylenebisstearamide, ethylenebisstearamide, and ethylenebisoleamide, and metal salts of higher fatty acids such as zinc stearate, magnesium stearate, and zinc oleate.

[0065] The content ratio of the organic lubricant relative to the recycled styrene resin raw material particles (a) is preferably 0.01% by mass to 2.0% by mass, more preferably 0.02% by mass to 1.8% by mass, and depending on the circumstances, it is further preferably 0.02% by mass to 0.2% by mass, and particularly preferably 0.02% by mass to 0.1% by mass. If the content ratio of the organic lubricant relative to the recycled styrene resin raw material particles (a) is less than 0.01% by mass, the effect of reducing the bubble size of the recycled pre-foamed styrene resin particles may be reduced. If the content ratio of the organic lubricant relative to the recycled styrene resin raw material particles (a) exceeds 2.0% by mass, there is a tendency that the bubble size of the recycled pre-foamed styrene resin particles becomes extremely small, the recycled pre-foamed styrene resin particles melt during molding, and the appearance of the molded product is poor.

[0066] As a specific method for making the recycled styrene resin raw material particles (a) include fine powder inorganic matter and / or organic lubricant, for example, a method of mixing fine powder inorganic matter and / or organic lubricant during extrusion molding can be cited. In this case, preferably after the crushed material is mixed with the bubble regulator in advance, extrusion molding is carried out. The mixing method of the crushed material and the bubble regulator can be carried out by any and appropriate method within the scope of not damaging the effect of the present invention. As this method, for example, a mixing method using a mixer such as a rotary drum, a ribbon blender, a V-blender, a Henschel mixer, a Lodge agitator, etc. can be cited.

[0067] Regenerated styrene resin raw material particles (a) are preferably hot-melted for the purpose of adjusting specific gravity. In this process, the specific gravity of the recycled styrene resin raw material particles (a) is preferably adjusted to more than 0.6, and more preferably adjusted to more than 0.9. If the specific gravity of the recycled styrene resin raw material particles (a) is less than 0.6, the dispersion of the recycled styrene resin raw material particles (a) is unstable, and therefore, excessively large particles and reduced yields may be produced in the subsequent polymerization process. The hot melting of the recycled styrene resin raw material particles (a) can be carried out by any and appropriate method within the scope that does not damage the effect of the present invention. As such a method, for example, a method using an extruder or a hot roller can be cited. Regarding hot melting, it is preferred to cool and solidify the obtained resin in a state where there is no residual strain or the strain is small. If the resin particles have residual strain, it is possible that the strain is relaxed in the subsequent process, shrinkage occurs along the stretching direction, and the obtained recycled foamable styrene resin particles are not spherical but flat. Therefore, as hot melting, it is preferred to use an extruder for non-stretching melting. If hot melting is carried out in a stretched state, the stretched resin obtained by cooling and solidification may have residual strain. Even if strain remains in the resin due to heat melting, the strain can be relaxed by curing for a predetermined time at a temperature equal to or higher than the softening point of the resin.

[0068] The pulverization when obtaining the recycled styrene resin raw material pellets (a) can be performed using any pulverizer within the range that does not impair the effects of the present invention. As such a pulverizer, for example, a pulverizer for plastics can be used, preferably a pulverizer for polystyrene.

[0069] The recycled styrene resin raw material pellets (a) may be sieved as necessary and then subjected to melting again by an extruder or the like.

[0070] The average particle size of the recycled styrene resin raw material particles (a) is preferably 0.2 mm to 3.0 mm, more preferably 0.3 mm to 2.5 mm, further preferably 0.4 mm to 2.0 mm, and particularly preferably 0.5 mm to 1.7 mm. If the average particle size of the recycled styrene resin raw material particles (a) exceeds 3 mm, the shape of the resulting recycled foamable styrene resin particles may not be spherical. If the average particle size of the recycled styrene resin raw material particles (a) is less than 0.2 mm, the average particle size of the resulting recycled foamable styrene resin particles may be too small.

[0071] The L (long side) / D (short side) of the recycled styrene resin raw material particles (a) is preferably 1.0 to 6.0, more preferably 1.0 to 5.0, further preferably 1.0 to 4.0, particularly preferably 1.0 to 3.0, and most preferably 1.0 to 2.5. If the L (long side) / D (short side) of the recycled styrene resin raw material particles (a) deviates from the above range, the shape of the obtained recycled foamable styrene resin particles may not easily be spherical.

[0072] The content of particles having an average particle size of 200 μm or less in the recycled styrene resin raw material particles (a) is preferably less than 1% by mass. When the content of particles having an average particle size of 200 μm or less in the recycled styrene resin raw material particles (a) is 1% by mass or more, the appearance of the recycled foamable styrene resin particles obtained using the recycled styrene resin raw material particles may be deteriorated.

[0073] The weight average molecular weight of the recycled styrene resin raw material particles (a) is preferably 100,000 to 510,000, and more preferably 150,000 to 490,000. When the weight average molecular weight of the recycled styrene resin raw material particles (a) is less than 100,000, sufficient strength may not be obtained. If the weight average molecular weight of the recycled styrene resin raw material particles (a) exceeds 510,000, the recycled styrene resin raw material particles may not be easy to present a spherical shape, and the foamability may be reduced, and the appearance of the molded product may be poor.

[0074] The styrene-based monomer used in the first embodiment of the recycled styrene-based resin raw material (A) may be only one kind or two or more kinds.

[0075] Styrene monomers include styrene or styrene derivatives. Examples of styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, bromostyrene, etc. The styrene monomers may be only one or more. The styrene monomers preferably contain at least styrene. The content of styrene relative to the total amount of styrene monomers is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0076] The styrene monomer may contain any and appropriate vinyl monomers other than the styrene monomer within the scope of not impairing the effect of the present invention. Examples thereof include multifunctional monomers, (meth)acrylate monomers, maleate monomers, and fumarate monomers. Such vinyl monomers may be only one or more.

[0077] Specific examples of the multifunctional monomer include divinylbenzenes such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate. Specific examples of (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and hexyl (meth)acrylate. Maleate monomers include dimethyl maleate. Fumarate monomers include dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

[0078] In the embodiment 1 of the recycled styrene resin raw material (A), the recycled styrene resin raw material particles (a) are preferably 5% by mass to 90% by mass, more preferably 10% by mass to 85% by mass, further preferably 15% by mass to 80% by mass, particularly preferably 20% by mass to 75% by mass, and most preferably 20% by mass to 70% by mass relative to the total amount of the recycled styrene resin raw material particles (a) and the styrene monomer. If the above-mentioned content ratio deviates from the above-mentioned scope and is too little, the environmental contribution may decrease. In addition, if the above-mentioned content ratio deviates from the above-mentioned scope and is too little or too much, the recycled foamable styrene resin particles of the embodiment of the present invention may not show good spheroidization, and the moldability may be reduced.

[0079] The regenerated styrene resin raw material (A) is obtained by adding a styrene monomer to a suspension containing regenerated styrene resin raw material particles (a) and polymerizing the same. As such a polymerization method, any and appropriate method can be adopted within the scope that does not impair the effect of the present invention. As a preferred embodiment of such a polymerization method, the following method can be cited: to a suspension obtained by dispersing the regenerated styrene resin raw material particles (a) as cores in water, an emulsion containing a polymerization initiator and a styrene monomer is added, the emulsion is infiltrated into the regenerated styrene resin raw material particles (a), and then a styrene monomer is added to polymerize the suspension.

[0080] In the first embodiment of the recycled styrene resin raw material (A), when the recycled styrene resin raw material (A) is obtained, from the viewpoint of being able to further exhibit the effects of the present invention, the addition temperature when adding the styrene monomer to the recycled styrene resin raw material particles (a) is preferably 40° C. to 119° C., preferably 40° C. to 118° C., more preferably 40° C. to 117° C., further preferably 50° C. to 117° C., and particularly preferably 60° C. to 115° C. If the addition temperature when adding the styrene monomer to the recycled styrene resin raw material particles (a) is adjusted to be within the above range, the styrene monomer is incorporated while the recycled styrene resin raw material particles (a) are maintained at an appropriate hardness, so that the recycled styrene resin raw material (A) can exhibit good spheroidization, and the finally obtained recycled foamable styrene resin particles can exhibit good spheroidization and excellent moldability. If the addition temperature when adding styrene monomers to the recycled styrene resin raw material particles (a) deviates from the above range and is too low, the recycled styrene resin raw material particles (a) become too hard, and when the styrene monomers are incorporated in this state, the recycled styrene resin raw material (A) is not easy to be spheroidized, and the finally obtained recycled foamable styrene resin particles may not be easy to be spheroidized, and the moldability may be poor. If the addition temperature when adding styrene monomers to the recycled styrene resin raw material particles (a) deviates from the above range and is too high, the recycled styrene resin raw material particles (a) become too soft, and when the styrene monomers are incorporated in this state, the recycled styrene resin raw material (A) is not easy to be spheroidized, and the finally obtained recycled foamable styrene resin particles may not be easy to be spheroidized, and the moldability may be poor. It should be noted that the "addition temperature when adding styrene monomers to the recycled styrene resin raw material particles (a)" mentioned here refers to: the addition temperature when adding an emulsion containing a polymerization initiator and a styrene monomer and then adding a styrene monomer.

[0081] When the regenerated styrene resin raw material particles (a) are dispersed in an aqueous medium to obtain a suspension as a core, any and appropriate method can be adopted within the scope of not damaging the effect of the present invention as a method for dispersing the regenerated styrene resin raw material particles (a) in an aqueous medium. As such a dispersion method, it is preferred to use a device with a stirring blade to disperse. As a method for more finely dispersing, a method using a homogenizer can be cited.

[0082] When the regenerated styrene resin raw material particles (a) are used as cores and dispersed in an aqueous medium to obtain a suspension, it is preferred to use a dispersant when dispersing the regenerated styrene resin raw material particles (a) in an aqueous medium. As long as the dispersant is a substance that can be used for suspension polymerization, any and appropriate dispersant can be used within the scope that does not damage the effect of the present invention. As such a dispersant, organic dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone, and methylcellulose can be listed; and sparingly soluble inorganic salts such as magnesium phosphate, magnesium pyrophosphate, and tricalcium phosphate. Among these, from the viewpoint of being able to further demonstrate the effect of the present invention, as a dispersant, magnesium pyrophosphate is preferably used.

[0083] The blending ratio of the dispersant to 100 parts by mass of the recycled styrene resin raw material (A) is preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.1 to 1.0 parts by mass.

[0084] When the regenerated styrene resin raw material particles (a) are used as the core and dispersed in an aqueous medium to obtain a suspension, it is preferred to use a surfactant when dispersing the regenerated styrene resin raw material particles (a) in an aqueous medium. As long as the surfactant is a material that can be used for suspension polymerization, any and appropriate surfactant can be used within the scope of not damaging the effect of the present invention. As such a surfactant, for example, sodium dodecylbenzene sulfonate, sodium alkane sulfonate, sodium alkyl sulfonate, sodium alkyl diphenyl ether disulfonate and sodium α-olefin sulfonate can be listed. Among these, from the viewpoint of being able to further show the effect of the present invention, as a surfactant, sodium dodecylbenzene sulfonate is preferably used.

[0085] The blending ratio of the surfactant to 100 parts by mass of the recycled styrene resin raw material (A) is preferably 0.005 to 0.1 parts by mass, more preferably 0.005 to 0.08 parts by mass, and even more preferably 0.005 to 0.06 parts by mass.

[0086] As an emulsification method for obtaining an emulsion containing a polymerization initiator and a styrene-based monomer, any and appropriate method can be adopted within the scope that does not impair the effect of the present invention. As such a dispersion method, it is preferred to use a device equipped with a stirring blade for dispersion. As a method for more fine dispersion, a method using a homogenizer can be cited. At this time, it is preferred to disperse until the oil droplet diameter of the dispersion dispersed with the styrene-based monomer becomes less than the particle size of the core. This is because: if the oil droplet diameter is added to the aqueous medium in a state larger than the particle size of the core, a plurality of recycled styrene-based resin raw material particles (a) are incorporated into the oil droplets of the dispersion dispersed with the styrene-based monomer, and it is easy for the recycled styrene-based resin raw material particles (a) to be bonded, plasticized, and fused, and it is easy to produce oversized particles.

[0087] As the polymerization initiator used when obtaining the emulsion containing the polymerization initiator and the styrene-based monomer, any and appropriate polymerization initiator can be used within the scope that does not impair the effect of the present invention as long as it can be used for the suspension polymerization method. As such polymerization initiator, for example, organic peroxides such as benzoyl peroxide, tert-butyl peroxy-2-ethylhexyl carbonate, and tert-butyl perbenzoate; and azo compounds such as azobisisobutyronitrile can be listed. The polymerization initiator may be only one kind or two or more kinds.

[0088] The amount of the polymerization initiator used is preferably 0.1% by mass to 1.0% by mass, more preferably 0.1% by mass to 0.8% by mass, based on the styrene-based monomer.

[0089] The polymerization initiator is preferably dissolved and added to the styrene monomer or solvent. Examples of the solvent include aromatic hydrocarbons such as ethylbenzene and toluene; and aliphatic hydrocarbons such as heptane and octane. When a solvent is used, it is usually used in an amount of 10% by mass or less relative to the styrene monomer.

[0090] As a method of adding a styrene monomer after adding an emulsion containing a styrene monomer to a suspension containing recycled styrene resin raw material particles (a) and impregnating it, any and appropriate method can be adopted within the scope that does not damage the effect of the present invention. As such a method, for example, batch addition and continuous addition can be listed. The addition rate is appropriately selected according to the capacity, shape, polymerization temperature, etc. of the polymerization device.

[0091] After the emulsion containing the styrene monomer is added to the suspension containing the recycled styrene resin raw material particles (a) to impregnate it, the styrene monomer is added, and then the polymerization reaction is continued at an arbitrary and appropriate temperature and time as required.

[0092] The suspension containing the recycled styrene resin raw material particles (a) and the emulsion containing the styrene monomer may contain a bubble regulator. Examples of such bubble regulators include fatty acid monoamides such as oleic acid amide, stearic acid amide, and hydroxystearic acid amide; and fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide.

[0093] 《A-2. Pressing and impregnation of blowing agent》

[0094] Typical methods of pressure-injection and impregnation of the blowing agent include a method in which the regenerated styrene resin raw material (A) and a dispersant are placed in a reactor such as an autoclave, and the blowing agent is pressure-injected and impregnated.

[0095] The blending ratio of the dispersant to 100 parts by mass of the recycled styrene resin raw material (A) is preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.1 to 1.0 parts by mass.

[0096] The foaming agent may be only one kind or two or more kinds.

[0097] As a foaming agent, any and appropriate foaming agent can be used within the scope that does not impair the effect of the present invention. As a foaming agent, a volatile foaming agent can be preferably listed. As a volatile foaming agent, an organic compound having a boiling point below the softening point of a styrene resin and being gaseous or liquid at normal pressure is preferred. As a specific example, aliphatic hydrocarbons such as propane, n-butane, isobutane, pentane (n-pentane, isopentane, neopentane), and n-hexane; alicyclic hydrocarbons such as cyclopentane and cyclopentadiene; ketones such as acetone and methyl ethyl ketone; alcohols such as methanol, ethanol, and isopropanol; ether compounds with low boiling points such as dimethyl ether, diethyl ether, dipropyl ether, and methyl ethyl ether; halogen-containing hydrocarbons such as trichloromonofluoromethane and dichlorodifluoromethane, etc. As a volatile foaming agent, inorganic gases such as carbon dioxide, nitrogen, and ammonia can be used. Among these, from the viewpoint of further expressing the effect of the present invention, the volatile blowing agent is preferably at least one selected from n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane and cyclopentadiene, and more preferably at least one selected from n-butane, isobutane, n-pentane and isopentane.

[0098] The content of the blowing agent can be appropriately set according to the purpose as long as it is an amount sufficient for forming the recycled pre-foamed styrene resin particles and the recycled styrene resin foamed molded product. When the amount of the recycled styrene resin raw material (A) is set to 100 parts by mass, the content of the blowing agent is preferably 2 to 15 parts by mass.

[0099] As a dispersant, any and appropriate dispersant can be used within the scope that does not impair the effect of the present invention. The dispersant may be only one kind or may be two or more kinds. As such a dispersant, organic dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose, and sparingly soluble inorganic salts such as metal phosphates can be cited. Among these, from the viewpoint of being able to further demonstrate the effect of the present invention, a sparingly soluble inorganic salt is preferably used as a dispersant. As sparingly soluble inorganic salts, for example, monocalcium phosphate, dicalcium phosphate, tricalcium phosphate, monomagnesium phosphate, dimagnesium phosphate, trimagnesium phosphate, magnesium pyrophosphate, and magnesium metaphosphate can be cited.

[0100] The blending ratio of the dispersant to 100 parts by mass of the recycled styrene resin raw material (A) is preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.1 to 1.0 parts by mass.

[0101] As the surfactant, any and appropriate surfactant can be used within the scope that does not impair the effect of the present invention. It can be only one kind or two or more kinds. As such surfactant, for example, sodium dodecylbenzene sulfonate, sodium alkane sulfonate, sodium alkyl sulfonate, sodium alkyl diphenyl ether disulfonate and sodium α-olefin sulfonate can be listed. Among these, sodium dodecylbenzene sulfonate is preferably used as the surfactant from the viewpoint of being able to further demonstrate the effect of the present invention.

[0102] The blending ratio of the surfactant to 100 parts by mass of the recycled styrene resin raw material (A) is preferably 0.005 to 0.1 parts by mass, more preferably 0.005 to 0.08 parts by mass, and even more preferably 0.005 to 0.06 parts by mass.

[0103] In the method for producing recycled foamable styrene resin particles according to an embodiment of the present invention, when the glass transition temperature of the recycled styrene resin raw material (A) is set to Tg, the temperature of the foaming agent is set to T1, and the temperature of the foaming agent is set to T2, T1 is within the range of (Tg-50°C) to (Tg+40°C), and T2 is within the range of (Tg-50°C) to (Tg+40°C). By making T1 and T2 within the above range, it is possible to produce recycled foamable styrene resin particles that have suppressed peculiar odor of recycled materials, can exhibit good spheroidization, and have excellent moldability. In the present invention, representatively, by adjusting the glass transition temperature of the recycled styrene resin raw material (A) to a specific range as a reference for the temperature of the foaming agent and the temperature of the foaming agent, it is possible to produce recycled foamable styrene resin particles that have suppressed peculiar odor of recycled materials, can exhibit good spheroidization, and have excellent moldability.

[0104] From the viewpoint of further demonstrating the effects of the present invention, the glass transition temperature Tg of the recycled styrene resin raw material (A) is preferably 85°C to 115°C, more preferably 88°C to 111°C, further preferably 91°C to 109°C, particularly preferably 93°C to 107°C, and most preferably 95°C to 105°C.

[0105] As described above, the lower limit of T1 is (Tg-50°C) or more, and from the viewpoint of being able to further express the effect of the present invention, it is preferably (Tg-40°C) or more, more preferably (Tg-30°C) or more, further preferably (Tg-20°C) or more, further preferably (Tg-10°C) or more, further preferably (Tg-7°C) or more, particularly preferably (Tg-5°C) or more, and most preferably (Tg-3°C) or more. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the lower limit of T1 is 50°C or more, preferably 60°C or more, more preferably 70°C or more, further preferably 75°C or more, further preferably 80°C or more, further preferably 85°C or more, further preferably 90°C or more, particularly preferably 93°C or more, and most preferably 95°C or more.

[0106] As described above, the lower limit of T2 is (Tg-50°C) or more, and from the viewpoint of being able to further express the effect of the present invention, it is preferably (Tg-40°C) or more, more preferably (Tg-30°C) or more, further preferably (Tg-20°C) or more, further preferably (Tg-10°C) or more, further preferably (Tg-7°C) or more, particularly preferably (Tg-5°C) or more, and most preferably (Tg-3°C) or more. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the lower limit of T2 is 50°C or more, preferably 60°C or more, more preferably 70°C or more, further preferably 75°C or more, further preferably 80°C or more, further preferably 85°C or more, further preferably 90°C or more, particularly preferably 93°C or more, and most preferably 95°C or more.

[0107] As described above, the upper limit value of T1 is (Tg+40°C) or less, and from the viewpoint of being able to further demonstrate the effect of the present invention, the viewpoint of reducing the manufacturing cost, etc., it is preferably (Tg+35°C) or less, more preferably (Tg+30°C) or less, further preferably (Tg+25°C) or less, and particularly preferably (Tg+20°C) or less. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the upper limit value of T1 is 140°C or less, preferably 135°C or less, more preferably 130°C or less, further preferably 125°C or less, and particularly preferably 120°C or less.

[0108] As described above, the upper limit of T2 is (Tg+40°C) or less, and from the viewpoint of being able to further demonstrate the effect of the present invention, the viewpoint of reducing the manufacturing cost, etc., it is preferably (Tg+35°C) or less, more preferably (Tg+30°C) or less, further preferably (Tg+25°C) or less, and particularly preferably (Tg+20°C) or less. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the upper limit of T2 is 140°C or less, preferably 135°C or less, more preferably 130°C or less, further preferably 125°C or less, and particularly preferably 120°C or less.

[0109] In a preferred embodiment (sometimes referred to as "embodiment 1"), T1 is in the range of (Tg-50°C) to (Tg+40°C), and T2 is in the range of (Tg-50°C) to (Tg+10°C). As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, in embodiment 1, T1 is in the range of 50°C to 140°C, and T2 is in the range of 50°C to 110°C.

[0110] In another preferred embodiment (sometimes referred to as "embodiment 2"), T1 is in the range of (Tg+10°C) to (Tg+30°C), and T2 is in the range of (Tg+10°C) to (Tg+30°C). As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, in embodiment 2, T1 is 110°C to 130°C, and T2 is 110°C to 130°C.

[0111] When selecting embodiment 1, as a dispersant, any and appropriate dispersant can be used within the scope of not damaging the effect of the present invention. As such a dispersant, from the viewpoint of being able to further show the effect of the present invention, it is preferred to use at least one selected from the group consisting of an organic dispersant and a sparingly soluble inorganic salt. As an organic dispersant, as described above, for example, polyvinyl alcohol, polyvinyl pyrrolidone, and methylcellulose can be cited. As a sparingly soluble inorganic salt, as described above, for example, monocalcium phosphate, dicalcium phosphate, tricalcium phosphate, monomagnesium phosphate, dimagnesium phosphate, trimagnesium phosphate, magnesium pyrophosphate, and magnesium metaphosphate can be cited.

[0112] Therefore, a preferred embodiment of the method for producing recycled foamable styrene resin particles of the present invention is the case of selecting embodiment 1, which is a method for producing recycled foamable styrene resin particles by pressing a foaming agent into a suspension containing a recycled styrene resin raw material (A) and a dispersant to impregnate it, the glass transition temperature of the recycled styrene resin raw material (A) is set to Tg, the temperature for pressing the foaming agent is set to T1, and the temperature for impregnating the foaming agent is set to T2, T1 is in the range of above (Tg-50°C) and below (Tg+40°C), T2 is in the range of above (Tg-50°C) and below (Tg+10°C), and the dispersant is at least one selected from the group consisting of an organic dispersant and a sparingly soluble inorganic salt.

[0113] When the second embodiment is selected, it is preferred to use a sparingly soluble inorganic salt as the dispersant from the viewpoint of being able to further demonstrate the effects of the present invention. As the sparingly soluble inorganic salt, as described above, for example, monocalcium phosphate, dicalcium phosphate, tricalcium phosphate, monomagnesium phosphate, dimagnesium phosphate, trimagnesium phosphate, magnesium pyrophosphate, and magnesium metaphosphate can be cited, and magnesium pyrophosphate is particularly preferred.

[0114] Therefore, another preferred embodiment of the method for producing recycled foamable styrene resin particles of the present invention is the case of selecting embodiment 2, which is a method for producing recycled foamable styrene resin particles by pressing a foaming agent into a suspension containing a recycled styrene resin raw material (A) and a dispersant to impregnate it, wherein the glass transition temperature of the recycled styrene resin raw material (A) is set to Tg, the temperature for pressing the foaming agent is set to T1, and the temperature for impregnating the foaming agent is set to T2, T1 is in the range of above (Tg+10°C) and below (Tg+30°C), and the above-mentioned T2 is in the range of above (Tg+10°C) and below (Tg+30°C), and the dispersant is a sparingly soluble inorganic salt, particularly preferably magnesium pyrophosphate.

[0115] As described above, the lower limit of T1 in Embodiment 1 is (Tg-50°C) or more, and from the viewpoint of being able to further express the effect of the present invention, it is preferably (Tg-40°C) or more, more preferably (Tg-30°C) or more, further preferably (Tg-20°C) or more, further preferably (Tg-10°C) or more, further preferably (Tg-7°C) or more, particularly preferably (Tg-5°C) or more, and most preferably (Tg-3°C) or more. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the lower limit of T1 in Embodiment 1 is 50°C or more, preferably 60°C or more, more preferably 70°C or more, further preferably 75°C or more, further preferably 80°C or more, further preferably 85°C or more, further preferably 90°C or more, particularly preferably 93°C or more, and most preferably 95°C or more.

[0116] As described above, the lower limit of T2 in Embodiment 1 is (Tg-50°C) or more, and from the viewpoint of being able to further express the effect of the present invention, it is preferably (Tg-40°C) or more, more preferably (Tg-30°C) or more, further preferably (Tg-20°C) or more, further preferably (Tg-10°C) or more, further preferably (Tg-7°C) or more, particularly preferably (Tg-5°C) or more, and most preferably (Tg-3°C) or more. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the lower limit of T2 in Embodiment 1 is 50°C or more, preferably 60°C or more, more preferably 70°C or more, further preferably 75°C or more, further preferably 80°C or more, further preferably 85°C or more, further preferably 90°C or more, particularly preferably 93°C or more, and most preferably 95°C or more.

[0117] As described above, the upper limit value of T1 in Embodiment 1 is (Tg+40°C) or less, and from the viewpoint of being able to further express the effect of the present invention, it is preferably (Tg+35°C) or less, more preferably (Tg+30°C) or less, further preferably (Tg+27°C) or less, particularly preferably (Tg+25°C) or less, and most preferably (Tg+23°C) or less. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the upper limit value of T1 in Embodiment 1 is 140°C or less, preferably 135°C or less, more preferably 130°C or less, further preferably 127°C or less, particularly preferably 125°C or less, and most preferably 123°C or less.

[0118] As described above, the upper limit value of T2 in Embodiment 1 is lower than (Tg+10°C), and from the viewpoint of being able to further express the effect of the present invention, it is preferably (Tg+9°C) or lower, more preferably (Tg+8°C) or lower, further preferably (Tg+7°C) or lower, particularly preferably (Tg+6°C) or lower, and most preferably (Tg+5°C) or lower. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the upper limit value of T2 in Embodiment 1 is lower than 110°C, preferably 109°C or lower, more preferably 108°C or lower, further preferably 107°C or lower, particularly preferably 106°C or lower, and most preferably 105°C or lower.

[0119] As described above, the lower limit of T1 in Embodiment 2 is (Tg+10°C) or more. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the lower limit of T1 in Embodiment 2 is 110°C or more.

[0120] As described above, the lower limit of T2 in Embodiment 2 is (Tg+10°C) or more. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the lower limit of T2 in Embodiment 2 is 110°C or more.

[0121] As described above, the upper limit of T1 in Embodiment 2 is (Tg+30°C) or less. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the upper limit of T1 in Embodiment 2 is 130°C or less.

[0122] As described above, the upper limit of T2 in Embodiment 2 is (Tg+30°C) or less. As a representative example, when the glass transition temperature Tg of the recycled styrene resin raw material (A) is 100°C, the upper limit of T2 in Embodiment 2 is 130°C or less.

[0123] The impregnation time of the blowing agent into the recycled styrene resin raw material (A) may be any appropriate time within the range not impairing the effects of the present invention, and such an impregnation time is preferably 1 to 10 hours.

[0124] In the manufacturing method of the regenerated foamable styrene resin particles of the embodiment of the present invention, in order to improve the flame retardancy of the obtained regenerated foamable styrene resin particles, a flame retardant can be added at any and appropriate time. From the viewpoint of being able to further show the effect of the present invention, the flame retardant is preferably added before the foaming agent is pressed into the regenerated styrene resin raw material (A). By adding the flame retardant before pressing the foaming agent, the flame retardant can be added at a low temperature equal to the temperature of pressing the foaming agent, and therefore, the good spheroidization and excellent moldability of the obtained regenerated foamable styrene resin particles can be shown.

[0125] The flame retardant may be used alone or in combination of two or more.

[0126] As a flame retardant, any and appropriate flame retardant can be used within the scope of not damaging the effect of the present invention. As such a flame retardant, a bromine compound compatible with polystyrene is preferred, and examples thereof include tetrabromoethane, tetrabromocyclooctane, hexabromocyclododecane, hexabromocyclohexane, tris(dibromopropyl)phosphate, tetrabromobisphenol A, tetrabromobisphenol F, tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tetrabromobisphenol A-diglycidyl ether, 2,2-bis[4'(2",3"-dibromoalkoxy)-3',5'-dibromophenyl]-propane, tris(tribromophenoxy)triazine, 2,2-bis(4-allyloxy-3,5-dibromo)propane, and hexabromobenzene.

[0127] When a flame retardant is used, a flame retardant auxiliary agent may be used in combination. Examples of the flame retardant auxiliary agent include cumene hydroperoxide, dicumyl peroxide, tert-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and 3,4-dimethyl-3,4-diphenylhexane.

[0128] The total amount of the flame retardant and the flame retardant auxiliary agent used may be any appropriate amount within the range not impairing the effects of the present invention, and is preferably 0.5 to 5.0% by mass based on the recycled styrene resin raw material (A).

[0129] From the viewpoint of further exhibiting the effects of the present invention, the temperature for adding the flame retardant is preferably 5°C to 89°C, more preferably 5°C to 87°C, further preferably 5°C to 85°C, particularly preferably 5°C to 83°C, and most preferably 5°C to 80°C.

[0130] In the method for producing the regenerated foamable styrene resin particles of the embodiment of the present invention, a bubble regulator can be used. The bubble regulator can be only one kind or two or more kinds. As the bubble regulator, for example, higher fatty acid amides, partial esters of higher fatty acids and alcohols, talc, calcium carbonate, mica, citric acid, and sodium bicarbonate can be listed. As higher fatty acid amides, for example, fatty acid monoamides such as oleamide, stearamide, and hydroxystearamide can be listed; fatty acid bisamides such as methylene bisstearamide and ethylene bisstearamide can be listed. As higher fatty acids in the partial esters of higher fatty acids and alcohols, for example, fatty acids with more than 15 carbon atoms such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and behenic acid can be listed. As partial esters of higher fatty acids and alcohols, for example, stearic acid monoglyceride and stearic acid diglyceride can be listed.

[0131] The amount of the bubble regulator is preferably 0 to 3.0 parts by mass, more preferably 0.03 to 1.0 parts by mass, relative to 100 parts by mass of the recycled styrene resin raw material (A). The bubble regulator may be added by a commonly used method such as adding it together with the foaming agent, or by dry blending, masterbatch method, or melt pressing method.

[0132] In the method for producing the regenerated foamable styrene resin particles according to the embodiment of the present invention, a foaming aid may be used. The foaming aid may be only one kind or two or more kinds. Examples of the foaming aid include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, and coconut oil.

[0133] In the method for producing the regenerated foamable styrene resin particles of the embodiment of the present invention, other additives may be used. Other additives may be only one kind or more than two kinds. Other additives include, for example, pigments, radiation heat conduction inhibiting components, crosslinking agents, plasticizers, stabilizers, fillers, lubricants, colorants, antistatic agents, spreading agents, weathering agents, antioxidants, antifogging agents, and fragrances.

[0134] 《《B. Recycled foamable styrene resin particles》》

[0135] Typically, the regenerated expandable styrene resin particles according to the embodiment of the present invention are obtained by the method for producing regenerated expandable styrene resin particles according to the embodiment of the present invention.

[0136] The regenerated foamable styrene resin particles of the embodiment of the present invention have a particle shape as a whole. The average particle size of the regenerated foamable styrene resin particles is preferably 0.40 mm to 2.0 mm, and more preferably 0.6 mm to 1.8 mm. The average particle size can be measured according to JIS Z 8815. Specifically, the average particle size is set to a value measured in the form of a particle size distribution based on a sieve test according to JIS Z 8815 and a cumulative value of 50%.

[0137] As the shape of the regenerated foamable styrene resin particles of the embodiment of the present invention, any and appropriate shape can be adopted within the scope of not damaging the effect of the present invention. As the specific example of this shape, for example, spherical, roughly spherical, ellipsoidal spherical (egg-shaped) etc. can be listed. As the shape of the regenerated foamable styrene resin particles of the embodiment of the present invention, from the viewpoint of showing the effect of the present invention, preferably spherical, roughly spherical, more preferably spherical. However, it is actually difficult to distinguish between spherical and roughly spherical, therefore, both are considered as spherical together in this specification.

[0138] The weight average molecular weight of the regenerated foamable styrene resin particles of the embodiment of the present invention can be any and appropriate weight average molecular weight within the range that does not impair the effect of the present invention. As such weight average molecular weight, it is preferably 100,000 to 510,000, more preferably 110,000 to 490,000, further preferably 120,000 to 470,000, and particularly preferably 130,000 to 460,000.

[0139] 《B-1. Surface treatment》

[0140] The regenerated foamable styrene resin particles according to the embodiment of the present invention may be subjected to a surface treatment, preferably a surface treatment using at least one selected from silicone oil, an antistatic agent, a fatty acid metal salt, and a fusion accelerator.

[0141] In the case of surface treatment of regenerated foamable styrene resin particles using silicone oil, the amount of silicone oil relative to 100 parts by mass of regenerated foamable styrene resin particles before surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.003 to 0.28 parts by mass, further preferably 0.005 to 0.25 parts by mass, particularly preferably 0.008 to 0.23 parts by mass, and most preferably 0.01 to 0.23 parts by mass. If the amount of silicone oil deviates from the above range and is too little, then, for example, when an antistatic agent is used, it is possible that the affinity with the antistatic agent is insufficient during pre-foaming, and static electricity is easily generated. If the amount of silicone oil deviates from the above range and is too much, it is possible to lose surface properties due to surface dissolution during molding.

[0142] The silicone oil may be used alone or in combination of two or more.

[0143] As the silicone oil, any appropriate silicone oil can be used within the range that does not impair the effect of the present invention. From the viewpoint of further demonstrating the effect of the present invention, the silicone oil includes common silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane, preferably dimethylpolysiloxane.

[0144] In the case of surface treatment of the regenerated foamable styrene resin particles by an antistatic agent, the amount of the antistatic agent relative to 100 parts by mass of the regenerated foamable styrene resin particles before the surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, further preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of the antistatic agent deviates from the above range and is too little, static electricity may be easily generated during pre-foaming. If the amount of the antistatic agent deviates from the above range and is too much, the surface of the regenerated pre-foamed styrene resin particles and the regenerated styrene resin foamed molded body may be sticky.

[0145] The antistatic agent may be used alone or in combination of two or more.

[0146] As the antistatic agent, any and appropriate antistatic agent can be adopted within the scope that does not damage the effect of the present invention. From the viewpoint that the effect of the present invention can be further demonstrated, as the antistatic agent, at least one selected from nonionic surfactants and fatty acid glycerides can be listed, and nonionic surfactants and fatty acid glycerides are preferably used in combination.

[0147] The nonionic surfactant may be used alone or in combination of two or more.

[0148] As a nonionic surfactant, any and appropriate nonionic surfactant can be used within the scope of not damaging the effect of the present invention. From the viewpoint of being able to further show the effect of the present invention, as a nonionic surfactant, for example, polyethylene glycol, glycerol, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyol, 1-amino-2-hydroxy compound can be listed. As polyoxyethylene alkyl ether, specifically, for example, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether can be listed. As polyoxyethylene alkyl ester, specifically, for example, polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, polyoxyethylene oleate can be listed. As a polyol, specifically, for example, glycerol and propylene glycol can be listed. Specific examples of the 1-amino-2-hydroxy compound include N-hydroxyethyl-N-(2-hydroxyalkyl)amine, N,N-bis(hydroxyethyl)dodecylamine, N,N-bis(hydroxyethyl)tetradecylamine, N,N-bis(hydroxyethyl)hexadecylamine, N,N-bis(hydroxyethyl)octadecylamine, N-hydroxyethyl-N-(2-hydroxytetradecyl)amine, N-hydroxyethyl-N-(2-hydroxyhexadecyl)amine, N-hydroxyethyl-N-(2-hydroxyoctadecyl)amine, N-hydroxypropylamine, The nonionic surfactant is preferably N-(2-hydroxytetradecyl)amine, N-hydroxybutyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxyhexadecyl)amine, N-hydroxypentyl-N-(2-hydroxyoctadecyl)amine, N,N-bis(2-hydroxyethyl)dodecylamine, N,N-bis(2-hydroxyethyl)tetradecylamine, N,N-bis(2-hydroxyethyl)hexadecylamine, N,N-bis(2-hydroxyethyl)octadecylamine, or salts thereof. From the viewpoint of further demonstrating the effects of the present invention, polyethylene glycol is preferred as the nonionic surfactant.

[0149] When a nonionic surfactant is used as at least a part of the antistatic agent, the amount of the nonionic surfactant relative to 100 parts by mass of the recycled foamable styrene resin particles before the surface treatment is preferably 0.001 to 2.0 parts by mass, more preferably 0.001 to 1.5 parts by mass, further preferably 0.001 to 1.0 parts by mass, further preferably 0.001 to 0.5 parts by mass, further preferably 0.001 to 0.3 parts by mass, further preferably 0.005 to 0.28 parts by mass, further preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of the nonionic surfactant deviates from the above range and is too small, static electricity may be easily generated during pre-foaming. If the amount of the nonionic surfactant deviates from the above range and is too much, the surface of the recycled pre-foamed styrene resin particles and the recycled styrene resin foamed molded body may be sticky.

[0150] The fatty acid glycerides may be used alone or in combination of two or more.

[0151] As the fatty acid glyceride, any and appropriate fatty acid glyceride can be adopted within the range that does not impair the effect of the present invention. From the viewpoint of being able to further demonstrate the effect of the present invention, as the fatty acid glyceride, specifically, for example, stearic acid monoglyceride and linoleic acid monoglyceride can be cited. From the viewpoint of being able to further demonstrate the effect of the present invention, as the fatty acid glyceride, stearic acid monoglyceride is preferred.

[0152] When using fatty acid glyceride as at least a part of the antistatic agent, the amount of the fatty acid glyceride relative to 100 parts by mass of the recycled foamable styrene resin particles before the surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, further preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of fatty acid glyceride deviates from the above range and is too little, static electricity may be easily generated during pre-foaming. If the amount of fatty acid glyceride deviates from the above range and is too much, the surface of the recycled pre-foamed styrene resin particles and the recycled styrene resin foamed molded body may be sticky.

[0153] In the case of surface treatment of regenerated foamable styrene resin particles by fatty acid metal salt, the amount of fatty acid metal salt relative to 100 parts by mass of regenerated foamable styrene resin particles before surface treatment is preferably 0.005 to 0.5 parts by mass, more preferably 0.007 to 0.45 parts by mass, further preferably 0.01 to 0.4 parts by mass, particularly preferably 0.015 to 0.35 parts by mass, and most preferably 0.02 to 0.3 parts by mass. If the amount of fatty acid metal salt deviates from the above range and is too little, it is possible that adhesion during pre-foaming occurs in large quantities and good styrene resin foam moldings cannot be obtained. If the amount of fatty acid metal salt deviates from the above range and is too much, there is a worry that metal salts are present in large quantities during pre-foaming, it is easy to be charged, it is easy to generate static electricity, and the fusion of molded products is deteriorated.

[0154] The fatty acid metal salt may be used alone or in combination of two or more.

[0155] As the fatty acid metal salt, any and appropriate fatty acid metal salt can be used within the scope that does not impair the effect of the present invention. From the viewpoint of being able to further demonstrate the effect of the present invention, as the fatty acid metal salt, for example, stearic acid metal salts and lauric acid metal salts can be listed. As the stearic acid metal salt, specifically, for example, magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate can be listed. As the lauric acid metal salt, specifically, for example, zinc laurate and barium laurate can be listed. From the viewpoint of being able to further demonstrate the effect of the present invention, as the fatty acid metal salt, magnesium stearate and zinc stearate are preferred.

[0156] In the case of surface treatment of recycled foamable styrene resin particles by using a fusion promoter, the amount of the fusion promoter relative to 100 parts by mass of recycled foamable styrene resin particles before surface treatment is preferably 0.01 to 0.8 parts by mass, more preferably 0.01 to 0.7 parts by mass, further preferably 0.01 to 0.6 parts by mass, particularly preferably 0.01 to 0.55 parts by mass, and most preferably 0.013 to 0.5 parts by mass. If the amount of the fusion promoter deviates from the above range and is too little, it is possible that the fusion property is reduced during molding and a good recycled styrene resin foam molding cannot be obtained. If the amount of the fusion promoter deviates from the above range and is too much, it is possible to stick during pre-foaming.

[0157] The fusion promoter may be only one kind or two or more kinds.

[0158] As a fusion promoter, any and appropriate fusion promoter can be used within the scope that does not impair the effect of the present invention. From the viewpoint of being able to further show the effect of the present invention, as a fusion promoter, for example, fatty acid triglycerides, fatty acid diglycerides, fatty acid monoglycerides, and vegetable oils can be listed. As fatty acid triglycerides, specifically, for example, lauric acid triglycerides, stearic acid triglycerides, linoleic acid triglycerides, and hydroxystearic acid triglycerides can be listed. As fatty acid diglycerides, specifically, for example, lauric acid diglycerides, stearic acid diglycerides, and linoleic acid diglycerides can be listed. As fatty acid monoglycerides, specifically, for example, lauric acid monoglycerides can be listed. As vegetable oils, specifically, for example, hydrogenated castor oil can be listed. From the viewpoint of being able to further show the effect of the present invention, as a fusion promoter, stearic acid triglycerides and hydroxystearic acid triglycerides are preferred.

[0159] 《《C. Recycled pre-foamed styrene resin particles》》

[0160] The recycled pre-foamed styrene resin particles according to the embodiment of the present invention are obtained by pre-foaming the recycled foamable styrene resin particles according to the embodiment of the present invention.

[0161] The average bubble diameter of the regenerated pre-foamed styrene resin particles is preferably 0.01 mm to 0.80 mm, more preferably 0.01 mm to 0.70 mm, further preferably 0.01 mm to 0.60 mm, particularly preferably 0.01 mm to 0.50 mm, and most preferably 0.01 mm to 0.40 mm. If the average bubble diameter of the regenerated pre-foamed styrene resin particles is within the above range, the following regenerated pre-foamed styrene resin particles can be provided, which can further prevent adhesion during foaming and molding, and further, can further inhibit the charging during foaming and molding and show better fusion and surface properties, and can mold a regenerated styrene resin foamed molded body with less static electricity. If the average bubble diameter of the regenerated pre-foamed styrene resin particles is less than 0.01 mm, the surface may dissolve and shrink during molding.

[0162] Pre-foaming includes using water vapor or the like to foam the regenerated foamable styrene resin particles to a desired volume expansion ratio (volume density). The volume expansion ratio of the regenerated pre-foamed styrene resin particles is preferably 2 to 150 times, more preferably 2 times or more and less than 100 times, more preferably 5 to 90 times, further preferably 10 to 85 times, and particularly preferably 15 to 83 times. The volume density is the reciprocal of the volume expansion ratio. By making the volume expansion ratio of the regenerated pre-foamed styrene resin particles within the above range, the following regenerated pre-foamed styrene resin particles can be provided, which can further prevent adhesion during foaming and molding, and further, can further suppress the charge during foaming and molding and show better fusion and surface properties, and can mold a regenerated styrene resin foam molding with less static electricity.

[0163] In a representative embodiment, the regenerated pre-foamed styrene resin particles can be used for the molding of the regenerated styrene resin foamed molded body. In another embodiment, the regenerated pre-foamed styrene resin particles can be directly used as a cushioning material, a heat insulating material, an aggregate of concrete, etc. In the case of directly using the regenerated pre-foamed styrene resin particles, the regenerated pre-foamed styrene resin particles can preferably be used in the form of a filling body obtained by filling a plurality of regenerated pre-foamed styrene resin particles into a bag body. Such regenerated pre-foamed styrene resin particles are suitable for, for example, being selected from at least one of the core material of the cushion (the foamed particles filled into the interior of the cushion) and the aggregate.

[0164] 《《D. Recycled styrene resin foam molding》》

[0165] The recycled styrene resin foam molded article of one embodiment of the present invention is a recycled styrene resin foam molded article molded from the recycled foamable styrene resin particles of the embodiment of the present invention. The recycled styrene resin foam molded article of another embodiment of the present invention is a recycled styrene resin foam molded article molded from the recycled pre-foamed styrene resin particles of the embodiment of the present invention.

[0166] Typically, the recycled styrene resin foam molded article includes recycled foamed styrene resin particles (hereinafter, sometimes simply referred to as “foamed particles”) obtained by further foaming recycled pre-foamed styrene resin particles.

[0167] Typically, the recycled styrene resin foamed molded product is composed of a plurality of foamed particles fused together.

[0168] Typically, a recycled styrene resin foamed body can be produced by placing recycled pre-foamed styrene resin particles into a mold having a predetermined shape that matches the purpose, and performing in-mold foaming molding. In more detail, in-mold foaming molding includes: (i) filling recycled pre-foamed styrene resin particles into a closed mold having a plurality of small holes; (ii) using a heat medium (such as pressurized steam, etc.) to heat and foam the recycled pre-foamed styrene resin particles to obtain foamed particles; (iii) by the heating and foaming, while filling the gaps between the foamed particles, the foamed particles are fused with each other, thereby integrating them. The density of the recycled styrene resin foamed body can be appropriately set according to the purpose. The density of the recycled styrene resin foamed body can be adjusted by, for example, pre-adjusting the volume expansion ratio of the pre-foamed styrene resin particles filled into the mold or adjusting the amount of the recycled pre-foamed styrene resin particles filled into the mold.

[0169] The temperature of heating and foaming (substantially the temperature of the heat medium) is preferably 90°C to 150°C, and more preferably 110°C to 130°C. The heating and foaming time is preferably 5 seconds to 50 seconds, and more preferably 10 seconds to 50 seconds. The molding steam pressure (blowing gauge pressure of the heat medium) of heating and foaming is preferably 0.04MPa to 0.1MPa, and more preferably 0.04MPa to 0.08MPa. If the heating and foaming are under such conditions, the foamed particles can be well fused with each other.

[0170] As required, the regenerated pre-foamed styrene resin particles may be aged before forming the regenerated styrene resin foamed molded body. The aging temperature of the regenerated pre-foamed styrene resin particles is preferably 20° C. to 60° C. If the aging temperature is too low, an excessively long aging time may be required. If the aging temperature is too high, the foaming agent in the regenerated pre-foamed styrene resin particles may escape and the moldability may be reduced.

[0171] The expansion ratio of the foamed particles in the recycled styrene resin foam molded product is preferably 2 times or more and less than 110 times, more preferably 5 times to 90 times, further preferably 10 times to 85 times, particularly preferably 15 times to 80 times.

[0172] 《《E. Use of recycled styrene resin foamed molded products》》

[0173] The recycled styrene resin foam molded body according to the embodiment of the present invention is lightweight and excellent in heat insulation and mechanical strength, and thus can be preferably used for at least one selected from molded bodies for heat insulating materials, molded bodies for heat preservation materials, molded bodies for filling materials, molded bodies for food containers, molded bodies for industrial product containers, molded bodies for cushioning materials, and molded bodies for packaging materials. As the molded body for heat insulating materials, for example, heat insulating materials for walls, heat insulating materials for floors, heat insulating materials for roofs, and heat insulating materials for automobiles can be cited. As the molded body for heat preservation materials, for example, heat preservation materials for hot water tanks, heat preservation materials for pipes, heat preservation materials for solar systems, and heat preservation materials for water heaters can be cited. As the molded body for food containers, for example, food containers such as fish boxes can be cited. As the molded body for industrial product containers, for example, turnover boxes can be cited. As the molded body for cushioning materials, for example, cushioning materials, buoys, and bricks can be cited. As the molded body for packaging materials, for example, packaging materials for fish and agricultural products can be cited. In addition, it can also be used for the core material of tatami mats.

[0174] Examples

[0175] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. It should be noted that the measurement methods and evaluation methods for each property are as follows.

[0176] <Measurement method of Tg>

[0177] The glass transition temperature Tg is measured by the methods described in JIS K7121:1987 and JIS K7121:2012. Among them, regarding the sampling method / temperature conditions, it is carried out as follows. After filling 5.5 ± 0.5 mg of the recycled styrene resin raw material as a sample into the bottom of an aluminum measurement container without gaps, an aluminum lid is covered. Then, using a differential scanning calorimeter "DSC7000X, AS-3" manufactured by Hitachi High-Tech Science Corporation, differential scanning calorimetry is performed. Under a nitrogen flow rate of 20 mL / minute, the sample is heated / cooled according to the following steps to obtain a DSC curve.

[0178] (Step 1) Heat from 30°C to 200°C at a rate of 20°C / minute and hold for 10 minutes.

[0179] (Step 2) Quickly take out the sample and naturally cool it in an environment of 25 ± 10°C.

[0180] (Step 3) Heat from 30°C to 200°C at a rate of 20°C / minute.

[0181] Based on the obtained DSC curve, the analysis software attached to the device is used to calculate the midpoint glass transition temperature observed in the second heating process (step 3). At this time, aluminum oxide is used as the reference substance. The midpoint glass transition temperature is obtained according to JIS K7121:1987 (9.3 item).

[0182] <Evaluation of odor>

[0183] The odor of the expandable styrene resin particles or styrene resin particles, the pre-expanded styrene resin particles thereof, and the molded articles obtained therefrom were evaluated by a sensory evaluation test based on the sense of smell as follows.

[0184] ×: Strong odor

[0185] △: Easily detectable odor

[0186] ○: Slight odor

[0187] ◎: Barely perceptible odor

[0188] <Moldability>

[0189] Comprehensive evaluation is performed based on the elongation of the molded body surface and the fusion rate when the molded body breaks. In the evaluation of the elongation of the molded body surface, the evaluation is performed by visually observing the appearance of the obtained foamed molded body. Specifically, the evaluation is performed by visually observing the state of the boundary portion where the foamed particles on the surface of the foamed molded body are combined. In addition, in the evaluation of the fusion rate between the foamed particles when the molded body breaks, the obtained plate-like foamed molded body is broken by impact, and the total number of foamed particles (A) and the number of particles that break within the particles (B) in the cross section are counted, and the fusion rate (%) is calculated using the following formula.

[0190] Fusion rate (%) = {(B) / (A)}×100

[0191] Evaluation was performed based on the following criteria.

[0192] ◎: Smooth appearance, fusion rate is more than 80%.

[0193] 〇: Smooth appearance, fusion rate is more than 70%.

[0194] △: The appearance is mostly smooth, but there are local irregularities at the boundary portion, and the fusion rate is 60% or more and less than 70%.

[0195] ×: The boundary portion of the appearance has unevenness, the smoothness is poor, and the fusion rate is less than 60%.

[0196] <Shape of Resin Particles>

[0197] Take any 10 particles of foamable styrene resin particles or styrene resin particles, and calculate the value (L / D) obtained by dividing the long side (L) by the short side (D). When L / D is 1.0, it can be considered to be a true sphere, and the closer L / D is to 1.0, the closer it is to a true sphere.

[0198] <Determination of Bulk Density and Volume Expansion Ratio of Pre-Expanded Styrene Resin Particles>

[0199] The bulk density and volume expansion ratio of the pre-expanded styrene-based resin particles are measured as follows.

[0200] (Determination method of bulk density)

[0201] Pre-expanded styrene resin particles are used as a sample. After being naturally dropped in a measuring cylinder, the bottom of the measuring cylinder is knocked to make the sample volume constant. The volume and mass are measured and calculated using the following formula.

[0202] Bulk density (g / mL) = sample mass (g) / sample volume in the measuring cylinder (mL)

[0203] (Measurement method of volume expansion ratio)

[0204] Pre-expanded styrene resin particles were used as a sample, and after being naturally dropped in a measuring cylinder, the bottom of the measuring cylinder was tapped to make the sample volume constant, and the volume and mass were measured and calculated using the following formula: In the case of styrene resin, the resin specific gravity was assumed to be 1.0.

[0205] Volume expansion ratio (times) = sample volume in the measuring cylinder (mL) / sample mass (g) × resin specific gravity

[0206] It should be noted that the volume expansion ratio can be calculated as the inverse of the volume density.

[0207] <Determination of Density and Expansion Ratio of Styrene Resin Foam Molded Article>

[0208] (Determination method of density)

[0209] The density of the styrene-based resin foam molded product was calculated by measuring the size and mass of a test piece so that the number of significant figures was 3 or more and using the following formula.

[0210] Density (g / cm 3 ) = mass of test piece (g) / volume of test piece (cm 3 )

[0211] (Measurement method of foaming ratio)

[0212] The expansion ratio of the styrene-based resin foam molded product is calculated by measuring the size and mass of a test piece so that the number of significant figures is 3 or more and using the following formula: In the case of a styrene-based resin, the resin specific gravity is set to 1.0.

[0213] Foaming ratio (times) = test piece volume (cm 3 ) / test piece mass (g) × resin specific gravity

[0214] [Production Example 1]

[0215] <Production of Recycled Styrene Resin Raw Material Pellets (a)>

[0216] A used styrene resin (recycled styrene resin formed from foamed styrene) is supplied to a single-screw extruder, heated and melted at 200°C, and then cut underwater from a die in a manner such that the average particle size becomes 0.75 mm (approximately spherical), thereby obtaining recycled styrene resin raw material particles (a).

[0217] [Example 1]

[0218] <Production of Regenerated Expandable Styrene Resin Particles>

[0219] 36 kg of pure water, 3 g of sodium dodecylbenzenesulfonate and 150 g of tricalcium phosphate were placed in a 100-liter reactor equipped with a stirrer, and 12.6 kg of the regenerated styrene resin raw material particles (a) were further added and stirred at 140 rpm to suspend the particles to prepare a suspension (1).

[0220] Separately, 125 g of benzoyl peroxide (purity: 75%) as a polymerization initiator and 1.9 kg of styrene monomer in which 21 g of tert-butyl peroxy-2-ethylhexyl monocarbonate was dissolved were added to a dispersion of 2.5 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, and the mixture was stirred with a homogenizer to emulsify the mixture, thereby preparing an emulsion (1).

[0221] The suspension (1) in a 100-liter reactor equipped with a stirrer was maintained at 75° C., and the emulsion (1) was added.

[0222] Then, the temperature was maintained at 75°C for 30 minutes so that the styrene monomer and the polymerization initiator were fully absorbed into the recycled styrene resin raw material particles (a), and immediately after the maintenance, 27.5 kg of styrene monomer was continuously added dropwise over 130 minutes. The addition temperature was gradually increased from 75°C to 105°C.

[0223] Thereafter, the temperature was raised to 125°C over 30 minutes, maintained at 125°C for 1 hour, and then cooled to 60°C over 1 hour. Thus, regenerated styrene resin particles (1) were prepared in the reactor. The Tg of the regenerated styrene resin particles (1) was 100°C.

[0224] Separately, 50 g of ethylenebisstearamide and 150 g of dicumyl peroxide were added to a dispersion of 3.2 kg of pure water, 1.7 g of sodium dodecylbenzenesulfonate as a surfactant, and 20 g of tricalcium phosphate as a dispersant, and stirred with a homomixer to emulsify the mixture to prepare an emulsion (2). The emulsion (2) was added to the reactor cooled to 60° C. 10 minutes after the addition, 660 g of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) was added. After the addition, stirring was continued at 60° C. for 30 minutes.

[0225] Next, 3410 g of pentane (isopentane / normal pentane = 20% by mass / 80% by mass) as a blowing agent was injected at an injection temperature of the Tg of the regenerated styrene resin particles (1) minus 50°C, and this state was maintained for 5 hours to allow the blowing agent to be gradually impregnated. That is, the injection temperature of the blowing agent was set to be the Tg of the regenerated styrene resin particles (1) minus 50°C, and the impregnation temperature of the blowing agent was set to be the Tg of the regenerated styrene resin particles (1) minus 50°C. Thereafter, the temperature in the reactor was cooled to 30°C.

[0226] Thereafter, the contents were taken out from the reactor, dehydrated, dried, and classified to obtain regenerated expandable styrene resin particles (1).

[0227] <Surface Treatment of Regenerated Foamable Styrene Resin Particles>

[0228] 40 kg of the obtained recycled foamable styrene resin particles (1), 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglyceride and 16 g of fatty acid monoglyceride were added to a drum agitator and stirred for 30 minutes for surface treatment to obtain surface-treated recycled foamable styrene resin particles (1').

[0229] <Production of Recycled Pre-foamed Styrene Resin Particles>

[0230] The obtained regenerated foamable styrene resin particles (1') were stored in a refrigerator at 15°C for 15 days, and then placed in a cylindrical batch foaming machine with a volume of 25 liters and heated with steam for 2 minutes to obtain regenerated pre-foamed styrene resin particles (1). The bulk density of the regenerated pre-foamed styrene resin particles (1) was 0.02 g / cm 3 , the volume foaming ratio is 50 times.

[0231] <Production of Recycled Styrene Resin Foam Molded Product>

[0232] After the obtained regenerated pre-foamed styrene resin particles (1) are placed at room temperature for 24 hours, the regenerated pre-foamed styrene resin particles (1) are filled into the cavity of the molding die using a molding machine having a molding die with a cavity size of 300 mm in width, 400 mm in length and 30 mm in thickness, and heated at a steam pressure of 0.08 MPa (gauge pressure) for 30 seconds. Then, the molding die is cooled until the pressure in the molding die reaches 0.03 MPa, and then the mold is released from the molding die to obtain a plate-shaped regenerated styrene resin foamed molded body (1) corresponding to the molding die. The density of the regenerated styrene resin foamed molded body (1) is 0.02 g / cm 3 , the expansion ratio was 50. Thereafter, the regenerated styrene resin foamed molded product (1) was stored in a drying room at 50° C. for 1 day.

[0233] Table 1 shows various evaluation results.

[0234] It should be noted that the foamable styrene resin particles, foamable styrene resin particles, pre-foamed styrene resin particles, and styrene resin foamed molded bodies described in Examples 2 to 58 and Comparative Examples 1 to 8 are also respectively recycled foamable styrene resin particles, recycled foamable styrene resin particles, recycled pre-foamed styrene resin particles, and recycled styrene resin foamed molded bodies.

[0235] [Example 2]

[0236] Regenerated foamable styrene resin particles (2), surface-treated recycled foamable styrene resin particles (2'), recycled pre-foamed styrene resin particles (2), and recycled styrene resin foamed molded products (2) were obtained in the same manner as in Example 1, except that 150 g and 20 g of magnesium pyrophosphate were used as dispersants in the preparation of the suspension (1) and the emulsion (2) instead of 150 g and 20 g of tricalcium phosphate.

[0237] Table 1 shows various evaluation results.

[0238] [Example 3]

[0239] Except that the injection temperature and impregnation temperature of the blowing agent were changed to Tg-25°C of the recycled styrene resin particles (1), the same procedure as in Example 1 was carried out to obtain recycled foamable styrene resin particles (3), surface-treated recycled foamable styrene resin particles (3'), recycled pre-foamed styrene resin particles (3), and recycled styrene resin foamed molded products (3).

[0240] Table 1 shows various evaluation results.

[0241] [Example 4]

[0242] Regenerated foamable styrene resin particles (4), surface-treated recycled foamable styrene resin particles (4'), recycled pre-foamed styrene resin particles (4), and recycled styrene resin foamed molded products (4) were obtained in the same manner as in Example 3, except that 150 g and 20 g of magnesium pyrophosphate were used as the dispersant in the preparation of the suspension (1) and the emulsion (2) instead of 150 g and 20 g of tricalcium phosphate.

[0243] Table 1 shows various evaluation results.

[0244] [Example 5]

[0245] Regenerated foamable styrene resin particles (5), surface-treated recycled foamable styrene resin particles (5'), recycled pre-foamed styrene resin particles (5), and recycled styrene resin foamed molded products (5) were obtained in the same manner as in Example 1 except that the impregnation temperature of the foaming agent was changed to the Tg of the recycled styrene resin particles (1).

[0246] Table 1 shows various evaluation results.

[0247] [Example 6]

[0248] Regenerated foamable styrene resin particles (6), surface-treated recycled foamable styrene resin particles (6'), recycled pre-foamed styrene resin particles (6), and recycled styrene resin foamed molded products (6) were obtained in the same manner as in Example 5, except that 150 g and 20 g of magnesium pyrophosphate were used as the dispersant in the preparation of the suspension (1) and the emulsion (2) instead of 150 g and 20 g of tricalcium phosphate.

[0249] Table 1 shows various evaluation results.

[0250] [Example 7]

[0251] Except that the injection temperature of the foaming agent is changed to Tg-30°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg of the recycled styrene resin particles (1), the same procedure as in Example 1 is carried out to obtain recycled foamable styrene resin particles (7), surface-treated recycled foamable styrene resin particles (7'), recycled pre-foamed styrene resin particles (7), and recycled styrene resin foamed molded bodies (7).

[0252] Table 1 shows various evaluation results.

[0253] [Example 8]

[0254] Regenerated foamable styrene resin particles (8), surface-treated recycled foamable styrene resin particles (8'), recycled pre-foamed styrene resin particles (8), and recycled styrene resin foamed molded products (8) were obtained in the same manner as in Example 7, except that 150 g and 20 g of magnesium pyrophosphate were used as the dispersant in the preparation of the suspension (1) and the emulsion (2) instead of 150 g and 20 g of tricalcium phosphate.

[0255] Table 1 shows various evaluation results.

[0256] [Example 9]

[0257] Except that the injection temperature of the foaming agent is changed to Tg-10°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg of the recycled styrene resin particles (1), the same procedure as in Example 1 is carried out to obtain recycled foamable styrene resin particles (9), surface-treated recycled foamable styrene resin particles (9'), recycled pre-foamed styrene resin particles (9), and recycled styrene resin foamed molded bodies (9).

[0258] Table 1 shows various evaluation results.

[0259] [Example 10]

[0260] Regenerated foamable styrene resin particles (10), surface-treated recycled foamable styrene resin particles (10'), recycled pre-foamed styrene resin particles (10), and recycled styrene resin foamed molded products (10) were obtained in the same manner as in Example 9, except that 150 g and 20 g of magnesium pyrophosphate were used as dispersants in the preparation of the suspension (1) and the emulsion (2) instead of 150 g and 20 g of tricalcium phosphate.

[0261] Table 1 shows various evaluation results.

[0262] [Example 11]

[0263] Except for changing the injection temperature of the foaming agent to Tg-5°C of the recycled styrene resin particles (1), and changing the impregnation temperature of the foaming agent to Tg of the recycled styrene resin particles (1), the same procedure as in Example 1 is carried out to obtain recycled foamable styrene resin particles (11), surface-treated recycled foamable styrene resin particles (11'), recycled pre-foamed styrene resin particles (11), and recycled styrene resin foamed molded products (11).

[0264] Table 1 shows various evaluation results.

[0265] [Example 12]

[0266] Regenerated foamable styrene resin particles (12), surface-treated recycled foamable styrene resin particles (12'), recycled pre-foamed styrene resin particles (12), and recycled styrene resin foamed molded products (12) were obtained in the same manner as in Example 11, except that 150 g and 20 g of magnesium pyrophosphate were used as the dispersant in the preparation of the suspension (1) and the emulsion (2).

[0267] Table 1 shows various evaluation results.

[0268] [Example 13]

[0269] Except for changing the injection temperature of the foaming agent to the Tg of the recycled styrene resin particles (1), and changing the impregnation temperature of the foaming agent to the Tg of the recycled styrene resin particles (1), the same procedure as in Example 1 is carried out to obtain recycled foamable styrene resin particles (13), surface-treated recycled foamable styrene resin particles (13'), recycled pre-foamed styrene resin particles (13), and recycled styrene resin foamed molded products (13).

[0270] Table 1 shows various evaluation results.

[0271] [Example 14]

[0272] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 13 was carried out to obtain recycled foamable styrene resin particles (14), surface-treated recycled foamable styrene resin particles (14'), recycled pre-foamed styrene resin particles (14), and recycled styrene resin foamed molded products (14).

[0273] Table 1 shows various evaluation results.

[0274] [Example 15]

[0275] Except that the impregnation temperature of the blowing agent was changed to Tg+10°C of the recycled styrene resin particles (1), the same procedure as in Example 13 was carried out to obtain recycled foamable styrene resin particles (15), surface-treated recycled foamable styrene resin particles (15'), recycled pre-foamed styrene resin particles (15), and recycled styrene resin foamed molded products (15).

[0276] Table 1 shows various evaluation results.

[0277] [Example 16]

[0278] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 15 was carried out to obtain recycled foamable styrene resin particles (16), surface-treated recycled foamable styrene resin particles (16'), recycled pre-foamed styrene resin particles (16), and recycled styrene resin foamed molded products (16).

[0279] Table 1 shows various evaluation results.

[0280] [Example 17]

[0281] The same procedure as in Example 13 was followed except that the injection temperature of the foaming agent was changed to Tg+5°C of the recycled styrene resin particles (1) to obtain recycled foamable styrene resin particles (17), surface-treated recycled foamable styrene resin particles (17'), recycled pre-foamed styrene resin particles (17), and recycled styrene resin foamed molded bodies (17).

[0282] Table 1 shows various evaluation results.

[0283] [Example 18]

[0284] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 17 was carried out to obtain recycled foamable styrene resin particles (18), surface-treated recycled foamable styrene resin particles (18'), recycled pre-foamed styrene resin particles (18), and recycled styrene resin foamed molded body (18).

[0285] Table 1 shows various evaluation results.

[0286] [Example 19]

[0287] The injection temperature of the foaming agent is changed to Tg+10°C of the recycled styrene resin particles (1). The same procedure as in Example 15 is carried out to obtain recycled foamable styrene resin particles (19), surface-treated recycled foamable styrene resin particles (19'), recycled pre-foamed styrene resin particles (19), and recycled styrene resin foamed molded products (19).

[0288] Table 1 shows various evaluation results.

[0289] [Example 20]

[0290] Regenerated foamable styrene resin particles (20), surface-treated recycled foamable styrene resin particles (20'), recycled pre-foamed styrene resin particles (20), and recycled styrene resin foamed molded products (20) were obtained in the same manner as in Example 19, except that 150 g and 20 g of magnesium pyrophosphate were used as the dispersant in the preparation of the suspension (1) and the emulsion (2).

[0291] Table 1 shows various evaluation results.

[0292] [Example 21]

[0293] The injection temperature of the foaming agent is changed to Tg+15°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg+15°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 13 is carried out to obtain recycled foamable styrene resin particles (21), surface-treated recycled foamable styrene resin particles (21'), recycled pre-foamed styrene resin particles (21), and recycled styrene resin foamed molded bodies (21).

[0294] Table 2 shows various evaluation results.

[0295] [Example 22]

[0296] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 21 was carried out to obtain recycled foamable styrene resin particles (22), surface-treated recycled foamable styrene resin particles (22'), recycled pre-foamed styrene resin particles (22), and recycled styrene resin foamed molded products (22).

[0297] Table 2 shows various evaluation results.

[0298] [Example 23]

[0299] The injection temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 13 is carried out to obtain recycled foamable styrene resin particles (23), surface-treated recycled foamable styrene resin particles (23'), recycled pre-foamed styrene resin particles (23), and recycled styrene resin foamed molded bodies (23).

[0300] Table 2 shows various evaluation results.

[0301] [Example 24]

[0302] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 23 was carried out to obtain recycled foamable styrene resin particles (24), surface-treated recycled foamable styrene resin particles (24'), recycled pre-foamed styrene resin particles (24), and recycled styrene resin foamed molded products (24).

[0303] Table 2 shows various evaluation results.

[0304] [Example 25]

[0305] Except for changing the injection temperature of the foaming agent to Tg+25°C of the recycled styrene resin particles (1), and changing the impregnation temperature of the foaming agent to Tg+25°C of the recycled styrene resin particles (1), the same procedure as in Example 13 is carried out to obtain recycled foamable styrene resin particles (25), surface-treated recycled foamable styrene resin particles (25'), recycled pre-foamed styrene resin particles (25), and recycled styrene resin foamed molded bodies (25).

[0306] Table 2 shows various evaluation results.

[0307] [Example 26]

[0308] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 25 was carried out to obtain recycled foamable styrene resin particles (26), surface-treated recycled foamable styrene resin particles (26'), recycled pre-foamed styrene resin particles (26), and recycled styrene resin foamed molded products (26).

[0309] Table 2 shows various evaluation results.

[0310] [Example 27]

[0311] The injection temperature of the foaming agent is changed to Tg+30°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg+30°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 14 is carried out to obtain recycled foamable styrene resin particles (27), surface-treated recycled foamable styrene resin particles (27'), recycled pre-foamed styrene resin particles (27), and recycled styrene resin foamed molded bodies (27).

[0312] Table 2 shows various evaluation results.

[0313] [Example 28]

[0314] The injection temperature of the foaming agent is changed to Tg+40°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg+40°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 14 is carried out to obtain recycled foamable styrene resin particles (28), surface-treated recycled foamable styrene resin particles (28'), recycled pre-foamed styrene resin particles (28), and recycled styrene resin foamed molded bodies (28).

[0315] Table 2 shows various evaluation results.

[0316] [Example 29]

[0317] The injection temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg+8°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 13 is carried out to obtain recycled foamable styrene resin particles (29), surface-treated recycled foamable styrene resin particles (29'), recycled pre-foamed styrene resin particles (29), and recycled styrene resin foamed molded bodies (29).

[0318] Table 2 shows various evaluation results.

[0319] [Example 30]

[0320] Regenerated foamable styrene resin particles (30), surface-treated recycled foamable styrene resin particles (30'), recycled pre-foamed styrene resin particles (30), and recycled styrene resin foamed molded products (30) were obtained in the same manner as in Example 29, except that 150 g and 20 g of magnesium pyrophosphate were used as the dispersant for the preparation of the suspension (1) and the emulsion (2).

[0321] Table 2 shows various evaluation results.

[0322] [Example 31]

[0323] The injection temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg+10°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 13 is carried out to obtain recycled foamable styrene resin particles (31), surface-treated recycled foamable styrene resin particles (31'), recycled pre-foamed styrene resin particles (31), and recycled styrene resin foamed molded bodies (31).

[0324] Table 2 shows various evaluation results.

[0325] [Example 32]

[0326] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 31 was followed to obtain recycled foamable styrene resin particles (32), surface-treated recycled foamable styrene resin particles (32'), recycled pre-foamed styrene resin particles (32), and recycled styrene resin foamed molded products (32).

[0327] Table 2 shows various evaluation results.

[0328] [Example 33]

[0329] Except that the impregnation temperature of the foaming agent was changed to Tg+18°C of the recycled styrene resin particles (1), the same procedure as in Example 13 was carried out to obtain recycled foamable styrene resin particles (33), surface-treated recycled foamable styrene resin particles (33'), recycled pre-foamed styrene resin particles (33), and recycled styrene resin foamed molded bodies (33).

[0330] Table 2 shows various evaluation results.

[0331] [Example 34]

[0332] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 150 g and 20 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 33 was followed to obtain recycled foamable styrene resin particles (34), surface-treated recycled foamable styrene resin particles (34'), recycled pre-foamed styrene resin particles (34), and recycled styrene resin foamed molded products (34).

[0333] Table 2 shows various evaluation results.

[0334] [Example 35]

[0335] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 37 g and 5 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 14 was followed to obtain recycled foamable styrene resin particles (35), surface-treated recycled foamable styrene resin particles (35'), recycled pre-foamed styrene resin particles (35), and recycled styrene resin foamed molded products (35).

[0336] Table 2 shows various evaluation results.

[0337] [Example 36]

[0338] As the dispersant used in the preparation of the suspension (1) and the emulsion (2), 757 g and 103 g of magnesium pyrophosphate were used instead of 150 g and 20 g of tricalcium phosphate. The same procedure as in Example 14 was carried out to obtain recycled foamable styrene resin particles (36), surface-treated recycled foamable styrene resin particles (36'), recycled pre-foamed styrene resin particles (36), and recycled styrene resin foamed molded products (36).

[0339] Table 2 shows various evaluation results.

[0340] [Example 37]

[0341] As the surfactant used in the preparation of the suspension (1) and the emulsion (1) and (2), the amount of sodium dodecylbenzene sulfonate was changed to 1.2 g, 0.3 g and 0.6 g instead of 3 g, 0.8 g and 1.7 g, respectively. The same procedure as in Example 14 was carried out to obtain recycled foamable styrene resin particles (37), surface-treated recycled foamable styrene resin particles (37'), recycled pre-foamed styrene resin particles (37) and recycled styrene resin foamed molded products (37).

[0342] Table 2 shows various evaluation results.

[0343] [Example 38]

[0344] As the surfactant used in the preparation of the suspension (1) and the emulsion (1) and (2), the amount of sodium dodecylbenzene sulfonate was changed to 22.9 g, 6.1 g and 13 g instead of 3 g, 0.8 g and 1.7 g, respectively. The same procedure as in Example 14 was carried out to obtain recycled foamable styrene resin particles (38), surface-treated recycled foamable styrene resin particles (38'), recycled pre-foamed styrene resin particles (38) and recycled styrene resin foamed molded products (38).

[0345] Table 2 shows various evaluation results.

[0346] [Example 39]

[0347] <Production of Regenerated Expandable Styrene Resin Particles>

[0348] Into a 100-liter reactor equipped with a stirrer, 42 kg of pure water, 5.5 g of sodium dodecylbenzene sulfonate, and 170 g of tricalcium phosphate were added, 42 kg of regenerated styrene resin raw material particles (a) were added, and 34 g of ethylene bisstearamide was further added, and stirred at 145 rpm to suspend the particles to prepare a suspension (2). Thus, regenerated styrene resin particles (39) were obtained in the reactor. It should be noted that the Tg of the regenerated styrene resin particles (39) is 100°C.

[0349] The suspension (2) in a 100-liter reactor equipped with a stirrer was maintained at 60° C., and 150 g of dicumyl peroxide was added. Ten minutes after the addition, 650 g of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) was added. After the addition, stirring was continued at 60° C. for 30 minutes.

[0350] Thereafter, the temperature was raised to 100° C. over 30 minutes, and then 3360 g of pentane (isopentane / normal pentane=20% by mass / 80% by mass) as a blowing agent was injected at the injection temperature of the Tg of the regenerated styrene resin particles (39), and this state was maintained for 5 hours, thereby allowing the blowing agent to be gradually impregnated. That is, the injection temperature of the blowing agent was set to be the Tg of the regenerated styrene resin particles (39), and the impregnation temperature of the blowing agent was set to be the Tg of the regenerated styrene resin particles (39). Thereafter, the temperature in the reactor was cooled to 30° C.

[0351] Thereafter, the contents are taken out from the reactor, dehydrated, dried, and classified to obtain regenerated expandable styrene resin particles (39).

[0352] <Surface Treatment of Regenerated Foamable Styrene Resin Particles>

[0353] 40 kg of the obtained recycled foamable styrene resin particles (39), 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglyceride and 16 g of fatty acid monoglyceride were added to a drum agitator and stirred for 30 minutes for surface treatment to obtain surface-treated recycled foamable styrene resin particles (39').

[0354] <Production of Recycled Pre-foamed Styrene Resin Particles>

[0355] The obtained regenerated foamable styrene resin particles (39') were stored in a cold storage at 15°C for 15 days, and then placed in a cylindrical batch foaming machine with a volume of 25 liters and heated with steam for 2 minutes to obtain regenerated pre-foamed styrene resin particles (39). The bulk density of the regenerated pre-foamed styrene resin particles (39) was 0.02 g / cm 3 , the volume foaming ratio is 50 times.

[0356] <Production of Styrene Resin Foam Molded Product>

[0357] After the obtained regenerated pre-foamed styrene resin particles (39') are placed at room temperature for 24 hours, the pre-foamed styrene resin particles (39') are filled into the cavity of the molding die using a molding machine having a molding die with a cavity size of: width 300mm, length 400mm, and thickness 30mm, and heated at a steam pressure of 0.08MPa (gauge pressure) for 40 seconds, then cooled until the pressure in the molding die reaches 0.03MPa, and then demolded from the molding die to obtain a block-shaped regenerated styrene resin foamed molded body (39) corresponding to the molding die. The density of the regenerated styrene resin foamed molded body (39) is 0.02g / cm 3 , the expansion ratio was 50. Thereafter, the regenerated styrene resin foamed molded body (39) was stored in a drying room at 50°C for 1 day.

[0358] Table 3 shows various evaluation results.

[0359] [Example 40]

[0360] As the dispersant used in the preparation of the suspension (2), 170 g of magnesium pyrophosphate was used instead of 170 g of tricalcium phosphate. The same procedure as in Example 39 was carried out to obtain recycled foamable styrene resin particles (40), surface-treated recycled foamable styrene resin particles (40'), recycled pre-foamed styrene resin particles (40), and recycled styrene resin foamed molded bodies (40).

[0361] Table 3 shows various evaluation results.

[0362] [Example 41]

[0363] The impregnation temperature of the foaming agent is changed to Tg+10°C of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (41), surface-treated recycled foamable styrene resin particles (41'), recycled pre-foamed styrene resin particles (41), and recycled styrene resin foamed molded bodies (41).

[0364] Table 3 shows various evaluation results.

[0365] [Example 42]

[0366] As the dispersant used in the preparation of the suspension (2), 170 g of magnesium pyrophosphate was used instead of 170 g of tricalcium phosphate. The same procedure as in Example 41 was carried out to obtain recycled foamable styrene resin particles (42), surface-treated recycled foamable styrene resin particles (42'), recycled pre-foamed styrene resin particles (42), and recycled styrene resin foamed molded bodies (42).

[0367] Table 3 shows various evaluation results.

[0368] [Example 43]

[0369] Except that the impregnation temperature of the foaming agent is changed to Tg+18°C of the recycled styrene resin particles (39), the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (43), surface-treated recycled foamable styrene resin particles (43'), recycled pre-foamed styrene resin particles (43), and recycled styrene resin foamed molded bodies (43).

[0370] Table 3 shows various evaluation results.

[0371] [Example 44]

[0372] As the dispersant used in the preparation of the suspension (2), 170 g of magnesium pyrophosphate was used instead of 170 g of tricalcium phosphate. The same procedure as in Example 43 was carried out to obtain recycled foamable styrene resin particles (44), surface-treated recycled foamable styrene resin particles (44'), recycled pre-foamed styrene resin particles (44), and recycled styrene resin foamed molded products (44).

[0373] Table 3 shows various evaluation results.

[0374] [Example 45]

[0375] The injection temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (39), and the impregnation temperature of the foaming agent is changed to Tg+8°C of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (45), surface-treated recycled foamable styrene resin particles (45'), recycled pre-foamed styrene resin particles (45), and recycled styrene resin foamed molded bodies (45).

[0376] Table 3 shows various evaluation results.

[0377] [Example 46]

[0378] As the dispersant used in the preparation of the suspension (2), 170 g of magnesium pyrophosphate was used instead of 170 g of tricalcium phosphate. The same procedure as in Example 45 was carried out to obtain recycled foamable styrene resin particles (46), surface-treated recycled foamable styrene resin particles (46'), recycled pre-foamed styrene resin particles (46), and recycled styrene resin foamed molded products (46).

[0379] Table 3 shows various evaluation results.

[0380] [Example 47]

[0381] The injection temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (39), and the impregnation temperature of the foaming agent is changed to Tg+10°C of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (47), surface-treated recycled foamable styrene resin particles (47'), recycled pre-foamed styrene resin particles (47), and recycled styrene resin foamed molded bodies (47).

[0382] Table 3 shows various evaluation results.

[0383] [Example 48]

[0384] As the dispersant used in the preparation of the suspension (2), 170 g of magnesium pyrophosphate was used instead of 170 g of tricalcium phosphate. The same procedure as in Example 47 was carried out to obtain recycled foamable styrene resin particles (48), surface-treated recycled foamable styrene resin particles (48'), recycled pre-foamed styrene resin particles (48), and recycled styrene resin foamed molded products (48).

[0385] Table 3 shows various evaluation results.

[0386] [Example 49]

[0387] The injection temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (39), and the impregnation temperature of the foaming agent is changed to Tg+20°C of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (49), surface-treated recycled foamable styrene resin particles (49'), recycled pre-foamed styrene resin particles (49), and recycled styrene resin foamed molded bodies (49).

[0388] Table 3 shows various evaluation results.

[0389] [Example 50]

[0390] As the dispersant used in the preparation of the suspension (2), 170 g of magnesium pyrophosphate was used instead of 170 g of tricalcium phosphate. The same procedure as in Example 49 was carried out to obtain recycled foamable styrene resin particles (50), surface-treated recycled foamable styrene resin particles (50'), recycled pre-foamed styrene resin particles (50), and recycled styrene resin foamed molded products (50).

[0391] Table 3 shows various evaluation results.

[0392] [Example 51]

[0393] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropylbenzene peroxide) were not used, the same procedure as in Example 13 was carried out to obtain recycled foamable styrene resin particles (51), surface-treated recycled foamable styrene resin particles (51'), recycled pre-foamed styrene resin particles (51), and recycled styrene resin foamed molded products (51).

[0394] Table 4 shows various evaluation results.

[0395] [Example 52]

[0396] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropylbenzene peroxide) were not used, the same procedure as in Example 14 was carried out to obtain recycled foamable styrene resin particles (52), surface-treated recycled foamable styrene resin particles (52'), recycled pre-foamed styrene resin particles (52), and recycled styrene resin foamed molded products (52).

[0397] Table 4 shows various evaluation results.

[0398] [Example 53]

[0399] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropylbenzene peroxide) are not used, the same procedure as in Example 29 is carried out to obtain recycled foamable styrene resin particles (53), surface-treated recycled foamable styrene resin particles (53'), recycled pre-foamed styrene resin particles (53), and recycled styrene resin foamed molded products (53).

[0400] Table 4 shows various evaluation results.

[0401] [Example 54]

[0402] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropylbenzene peroxide) are not used, the same procedure as in Example 30 is carried out to obtain recycled foamable styrene resin particles (54), surface-treated recycled foamable styrene resin particles (54'), recycled pre-foamed styrene resin particles (54), and recycled styrene resin foamed molded products (54).

[0403] Table 4 shows various evaluation results.

[0404] [Example 55]

[0405] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropylbenzene peroxide) are not used, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (55), surface-treated recycled foamable styrene resin particles (55'), recycled pre-foamed styrene resin particles (55), and recycled styrene resin foamed molded products (55).

[0406] Table 4 shows various evaluation results.

[0407] [Example 56]

[0408] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropyl peroxide) are not used, the same procedure as in Example 40 is carried out to obtain recycled foamable styrene resin particles (56), surface-treated recycled foamable styrene resin particles (56'), recycled pre-foamed styrene resin particles (56), and recycled styrene resin foamed molded products (56).

[0409] Table 4 shows various evaluation results.

[0410] [Example 57]

[0411] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropylbenzene peroxide) are not used, the same procedure as in Example 45 is carried out to obtain recycled foamable styrene resin particles (57), surface-treated recycled foamable styrene resin particles (57'), recycled pre-foamed styrene resin particles (57), and recycled styrene resin foamed molded products (57).

[0412] Table 4 shows various evaluation results.

[0413] [Example 58]

[0414] Except that the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether)) and the flame retardant auxiliary (diisopropylbenzene peroxide) are not used, the same procedure as in Example 46 is carried out to obtain recycled foamable styrene resin particles (58), surface-treated recycled foamable styrene resin particles (58'), recycled pre-foamed styrene resin particles (58), and recycled styrene resin foamed molded products (58).

[0415] Table 4 shows various evaluation results.

[0416] [Comparative Example 1]

[0417] The injection temperature of the foaming agent is changed to Tg-60°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg-30°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 1 is carried out to obtain recycled foamable styrene resin particles (C1), surface-treated recycled foamable styrene resin particles (C1'), recycled pre-foamed styrene resin particles (C1), and recycled styrene resin foamed molded products (C1).

[0418] Table 4 shows various evaluation results.

[0419] [Comparative Example 2]

[0420] The injection temperature of the foaming agent is changed to Tg-60°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg of the recycled styrene resin particles (1). The same procedure as in Example 1 is carried out to obtain recycled foamable styrene resin particles (C2), surface-treated recycled foamable styrene resin particles (C2'), recycled pre-foamed styrene resin particles (C2), and recycled styrene resin foamed molded products (C2).

[0421] Table 4 shows various evaluation results.

[0422] [Comparative Example 3]

[0423] The same procedure as in Example 1 is carried out except that the injection temperature of the foaming agent is changed to the Tg of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to the Tg-60°C of the recycled styrene resin particles (1), to obtain recycled foamable styrene resin particles (C3), surface-treated recycled foamable styrene resin particles (C3'), recycled pre-foamed styrene resin particles (C3), and recycled styrene resin foamed molded products (C3).

[0424] Table 4 shows various evaluation results.

[0425] [Comparative Example 4]

[0426] The injection temperature of the foaming agent is changed to Tg+50°C of the recycled styrene resin particles (1), and the impregnation temperature of the foaming agent is changed to Tg+50°C of the recycled styrene resin particles (1). Except for this, the same procedure as in Example 1 is carried out to obtain recycled foamable styrene resin particles (C4), surface-treated recycled foamable styrene resin particles (C4'), recycled pre-foamed styrene resin particles (C4), and recycled styrene resin foamed molded products (C4).

[0427] Table 4 shows various evaluation results.

[0428] [Comparative Example 5]

[0429] The injection temperature of the foaming agent is changed to Tg-60°C of the recycled styrene resin particles (39), and the impregnation temperature of the foaming agent is changed to Tg-30°C of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (C5), surface-treated recycled foamable styrene resin particles (C5'), recycled pre-foamed styrene resin particles (C5), and recycled styrene resin foamed molded bodies (C5).

[0430] Table 4 shows various evaluation results.

[0431] [Comparative Example 6]

[0432] The injection temperature of the foaming agent is changed to Tg-60°C of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (C6), surface-treated recycled foamable styrene resin particles (C6'), recycled pre-foamed styrene resin particles (C6), and recycled styrene resin foamed molded bodies (C6).

[0433] Table 4 shows various evaluation results.

[0434] [Comparative Example 7]

[0435] The injection temperature of the foaming agent is changed to the impregnation temperature Tg-60°C of the foaming agent of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (C7), surface-treated recycled foamable styrene resin particles (C7'), recycled pre-foamed styrene resin particles (C7), and recycled styrene resin foamed molded bodies (C7).

[0436] Table 4 shows various evaluation results.

[0437] [Comparative Example 8]

[0438] The injection temperature of the foaming agent is changed to Tg+50°C of the recycled styrene resin particles (39), and the impregnation temperature of the foaming agent is changed to Tg+50°C of the recycled styrene resin particles (39). Except for this, the same procedure as in Example 39 is carried out to obtain recycled foamable styrene resin particles (C8), surface-treated recycled foamable styrene resin particles (C8'), recycled pre-foamed styrene resin particles (C8), and recycled styrene resin foamed molded bodies (C8).

[0439] Table 4 shows various evaluation results.

[0440] [Table 1]

[0441]

[0442] [Table 2]

[0443]

[0444] [Table 3]

[0445]

[0446] [Table 4]

[0447]

[0448] Industrial Applicability

[0449] The recycled foamable styrene resin particles, recycled pre-foamed styrene resin particles and recycled styrene resin foamed molded bodies according to the embodiments of the present invention can be suitably used for heat insulating materials used in houses and automobiles, heat insulating materials used in building materials, etc., packaging materials for transport such as fish boxes and food containers, cushioning materials, etc. More specifically, the recycled foamable styrene resin particles, recycled pre-foamed styrene resin particles and recycled styrene resin foamed molded bodies according to the embodiments of the present invention can be suitably used for heat insulating materials for walls, heat insulating materials for floors, heat insulating materials for roofs, heat insulating materials for automobiles, heat insulating materials for hot water tanks, heat insulating materials for pipes, heat insulating materials for solar energy systems, heat insulating materials for water heaters, containers for food and industrial products (e.g., food containers such as fish boxes, turnover boxes), cushioning materials, buoys, blocks, packaging materials for fish and agricultural products, etc., fill materials (fill blocks, etc.), core materials for tatami, core materials for mats, aggregates for concrete, etc.

Claims

1. A method for producing regenerated foamable styrene resin particles, wherein: A blowing agent is pressed into a suspension containing a recycled styrene resin raw material (A) and a dispersant to impregnate the suspension, When the glass transition temperature of the regenerated styrene resin raw material (A) is Tg, the temperature of the blowing agent injected is T1, and the temperature of the blowing agent impregnated is T2, T1 is in the range of (Tg-50°C) to (Tg+40°C), and T2 is in the range of (Tg-50°C) to (Tg+40°C).

2. The method for producing regenerated foamable styrene resin particles according to claim 1, wherein: The T1 is in the range of (Tg-50°C) to (Tg+40°C), and the T2 is in the range of (Tg-50°C) to (Tg+10°C).

3. The method for producing regenerated foamable styrene resin particles according to claim 2, wherein: The dispersant is at least one selected from the group consisting of organic dispersants and poorly soluble inorganic salts.

4. The method for producing regenerated foamable styrene resin particles according to claim 1, wherein: The T1 is in the range of (Tg+10°C) to (Tg+30°C), and the T2 is in the range of (Tg+10°C) to (Tg+30°C).

5. The method for producing regenerated foamable styrene resin particles according to claim 4, wherein: The dispersant is magnesium pyrophosphate.

6. The method for producing regenerated foamable styrene resin particles according to claim 1, wherein: The blending ratio of the dispersant is 0.1 to 2 parts by mass based on 100 parts by mass of the recycled styrene resin raw material (A).

7. The method for producing regenerated foamable styrene resin particles according to claim 1, wherein: The suspension comprises a surfactant.

8. The method for producing regenerated foamable styrene resin particles according to claim 7, wherein: The blending ratio of the surfactant is 0.005 to 0.1 parts by mass based on 100 parts by mass of the recycled styrene resin raw material (A).

9. The method for producing regenerated foamable styrene resin particles according to claim 1, wherein: As the recycled styrene resin raw material (A), polymer particles obtained by adding a styrene monomer to a suspension containing recycled styrene resin raw material particles (a) and polymerizing the resulting mixture are used.

10. The method for producing regenerated foamable styrene resin particles according to claim 1, wherein: As the recycled styrene-based resin raw material (A), recycled styrene-based resin raw material pellets (a) are used as they are.

11. The method for producing regenerated foamable styrene resin particles according to claim 9 or 10, wherein: The recycled styrene resin raw material particles (a) are at least one selected from extruded strand pellets, underwater cut pellets and thermal cut pellets. The extruded strand pellets are obtained by extruding used styrene resin through an extruder and cutting the strands, the underwater cut pellets are obtained by an underwater cutting method in which the used styrene resin is extruded through an extruder and cut in water at the same time, and the hot cut pellets are obtained by a hot cutting method in which the used styrene resin is cut and cooled immediately after it comes out of the die of the extruder. 12 . Regenerated expandable styrene resin particles obtained by the production method according to claim 1 .

13. Regenerated pre-foamed styrene resin particles, which are obtained by pre-foaming the regenerated foamable styrene resin particles according to claim 12, The volume expansion ratio of the pre-foaming is 2 to 150 times.

14. A recycled styrene resin foamed molded product obtained by molding the recycled pre-foamed styrene resin particles according to claim 13.

15. The recycled styrene resin foamed molded body according to claim 14, which is at least one selected from the group consisting of a molded body for thermal insulation materials, a molded body for heat preservation materials, a molded body for filling materials, a molded body for food containers, a molded body for industrial product containers, a molded body for cushioning materials, and a molded body for packaging materials. 16 . The recycled pre-expanded styrene-based resin particles according to claim 13 , which are at least one selected from the group consisting of a core material and an aggregate of a mat.

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