Method for manufacturing recycled foamed styrene resin particles, recycled foamed styrene resin particles, recycled pre-foamed styrene resin particles, and recycled styrene resin foam molded article

Abstract

To provide a method for producing recycled expandable styrene resin particles having high environmental contribution, which produces recycled expandable styrene resin particles by suppressing odor, in particular, odor derived from alkylamine.SOLUTION: A method for producing recycled expandable styrene resin particles having an alkylamine emission amount of less than Yng / g by using recycled styrene resin raw material particles (a) having the alkylamine emission amount of Xng / g or more, wherein X≥Y, Y≤5, (1) as preparation water used when preparing a suspension by press-fitting and impregnating a volatile foaming agent to the recycled styrene resin particles (A) obtained by adding and polymerizing a styrene monomer to a suspension containing the recycled styrene resin raw material particles (a), water in which a total of contents of specific metals in the preparation water is in a specific range as a concentration is used, or (2) the recycled styrene resin raw material particles (a) are used as the recycled styrene resin particles (A), the volatile foaming agent is press-fitted and impregnated in the suspension containing the recycled styrene resin particles (A), as the preparation water used when preparing the suspension, the water in which a total of contents of the specific metals in the preparation water is within a specific range as the concentration is used.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Because foamed molded products are lightweight and have excellent thermal insulation and mechanical strength, they are widely used as insulation materials in houses and automobiles, heat-insulating materials in building materials, embankment materials in expanded polystyrene civil engineering methods, transport packaging materials for fish boxes and food containers, and cushioning materials. Among these, in-mold foamed molded products manufactured using foamed particles (typically, foamed styrene resin particles or pre-foamed styrene resin particles) as raw materials are widely used due to advantages such as the ease with which desired shapes can be obtained. Such foamed molded products are composed of multiple foamed particles that are fused together.

[0003] On the other hand, the amount of plastic waste is increasing year by year. The majority of plastic waste is disposed of by incineration or landfill, but this has become a major social problem, leading to environmental pollution, global warming, and a shortage of landfill sites. For this reason, there is a strong social demand for the reuse of plastic waste, and various studies on plastic waste recycling are being considered, such as the enforcement of the Home Appliance Recycling Law. Among the various recycling methods that have been proposed, material recycling, which reuses plastic waste as plastic components in products, is attracting attention from the perspective of resource circulation and reduction of environmental impact, and such material recycling is also being considered for styrene foam molded products.

[0004] As a material recycling method for styrene foam molded products, several recycled foamable styrene resin particles have been proposed, which are obtained by melting and extruding recovered raw materials to produce recovered pellets, and then impregnating these pellets with a foaming agent.

[0005] For example, a method has been reported for obtaining recycled foamable styrene-based resin particles by impregnating or injecting a foaming agent into recycled resin pellets molded from recovered styrene-based resin foam molded products (Patent Documents 1-4). In addition, a method has been reported for obtaining recycled foamable styrene-based resin particles by adding styrene monomers to recycled resin pellets molded from recovered styrene-based resin foam molded products and polymerizing them, and then impregnating or injecting a foaming agent into them (Patent Documents 5-8).

[0006] However, conventional recycled foamed styrene resin particles have a problem in that they have an odor characteristic of recycled materials, especially compared to foamed styrene resin particles that do not use recovered raw materials. The recycled pre-foamed styrene resin particles and recycled styrene resin foam molded articles obtained from them also have a problem in that they emit an odor characteristic of recycled materials to a noticeable degree. In particular, recycled foamed styrene resin particles obtained using fish boxes as recovered raw materials have a problem in that they have a characteristic putrid odor of tertiary alkylamines derived from fish and other sources. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 3044942 [Patent Document 2] Patent No. 4234832 [Patent Document 3] Patent No. 4261676 [Patent Document 4] Patent No. 6788428 [Patent Document 5] Patent No. 4052193 [Patent Document 6] Japanese Patent Publication No. 2006-160905 [Patent Document 7] Patent No. 4912567 [Patent Document 8] Patent No. 5128246 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a method for producing recycled foamed styrene resin particles that have a high contribution to the environment, and that suppress odors, particularly odors derived from alkylamines, in recycled foamed styrene resin particles. Furthermore, it is also to provide recycled foamed styrene resin particles obtained from such a production method that suppress odors, particularly odors derived from alkylamines. Moreover, it is also to provide recycled pre-foamed styrene resin particles obtained from such recycled foamed styrene resin particles, and recycled styrene resin foam molded articles formed from such recycled pre-foamed styrene resin particles. [Means for solving the problem]

[0009] [1] A method for producing regenerated foamable styrene resin particles according to one embodiment of the present invention is a method for producing regenerated foamable styrene resin particles with an alkylamine emission amount of less than Y ng / g using regenerated styrene resin raw material particles (a) having an alkylamine emission amount of X ng / g or more, wherein X ≥ Y and Y ≤ 5, and a volatile foaming agent is injected and impregnated into regenerated styrene resin particles (A) obtained by adding a styrene monomer to a suspension containing the regenerated styrene resin raw material particles (a) and polymerizing them, and the water used when preparing the suspension is water in which the total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in the water is 0.01 mg / kg to 103 mg / kg in terms of concentration. [2] Another embodiment of the present invention provides a method for producing recycled foamable styrene resin particles, using recycled styrene resin raw material particles (a) having an alkylamine emission of X ng / g or more, wherein the alkylamine emission is less than Y ng / g, and X ≥ Y and Y ≤ 5, wherein the recycled styrene resin raw material particles (a) are used as recycled styrene resin particles (A), a volatile foaming agent is injected and impregnated into a suspension containing the recycled styrene resin particles (A), and the water used to prepare the suspension is water in which the total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in the water is 0.01 mg / kg to 103 mg / kg in terms of concentration. [3] The recycled foamable styrene resin particles according to the embodiment of the present invention are recycled foamable styrene resin particles having an alkylamine emission amount of less than 5 ng / g, and are obtained by the manufacturing method described in [1] or [2] above. [4] In the recycled foamed styrene resin particles described in [3] above, the amount of alkylamine emitted may be less than 2 ng / g. [5] Recycled pre-expanded styrene resin particles according to embodiments of the present invention are recycled pre-expanded styrene resin particles obtained by pre-expanding the recycled expandable styrene resin particles described in [3] or [4] above, wherein the bulk expansion ratio of the pre-expanding is 2 to 150 times. [6] A recycled styrene-based resin foam molded article according to an embodiment of the present invention is molded from recycled pre-foamed styrene-based resin particles described in [5] above. [Effects of the Invention]

[0010] According to an embodiment of the present invention, there is provided a method for producing recycled expandable styrene-based resin particles with a high environmental contribution degree, which can produce recycled expandable styrene-based resin particles with suppressed odor, particularly odor derived from alkylamine. Further, there can be provided recycled expandable styrene-based resin particles obtained from such a production method, with suppressed odor, particularly odor derived from alkylamine. Furthermore, there can be provided pre-expanded recycled styrene-based resin particles obtained from such recycled expandable styrene-based resin particles, and a recycled styrene-based resin foam molded body formed from such pre-expanded recycled styrene-based resin particles.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0012] In this specification, when "(meth)acryl" is mentioned, it means acrylic and / or methacrylic, and when "(meth)acrylate" is mentioned, it means acrylate and / or methacrylate.

[0013] ≪≪A. Method for Producing Recycled Expandable Styrene-Based Resin Particles≫≫ The method for producing recycled expandable styrene-based resin particles according to an embodiment of the present invention is a method for producing recycled expandable styrene-based resin particles having an alkylamine emission amount of less than Y ng / g using recycled styrene-based resin raw material particles (a) having an alkylamine emission amount of X ng / g or more, where X ≥ Y and Y ≤ 5.

[0014] For example, when X = Y = 5, the method for producing recycled expandable styrene-based resin particles according to an embodiment of the present invention is a method for producing recycled expandable styrene-based resin particles having an alkylamine emission amount of less than 5 ng / g using recycled styrene-based resin raw material particles (a) having an alkylamine emission amount of 5 ng / g or more.

[0015] For example, when X = 50 and Y = 5, the method for producing recycled foaming styrenic resin particles according to an embodiment of the present invention is a method for producing recycled foaming styrenic resin particles having an alkylamine emission amount of less than 5 ng / g using recycled styrenic resin raw material particles (a) having an alkylamine emission amount of 50 ng / g or more.

[0016] For example, when X = 5 and Y = 2, the method for producing recycled foaming styrenic resin particles according to an embodiment of the present invention is a method for producing recycled foaming styrenic resin particles having an alkylamine emission amount of less than 2 ng / g using recycled styrenic resin raw material particles (a) having an alkylamine emission amount of 5 ng / g or more.

[0017] The relationship between X and Y is X ≥ Y. In terms of more effectively expressing the effects of the present invention, preferably X > Y, more preferably X - Y > 1, still more preferably X - Y > 3, still more preferably X - Y > 5, particularly preferably X - Y > 7, and most preferably X - Y > 10.

[0018] Y ≤ 5. In terms of more effectively expressing the effects of the present invention, preferably Y < 5, more preferably Y < 4, still more preferably Y < 3, particularly preferably Y < 2, and most preferably Y < 1. Regarding the lower limit of Y, the smaller the alkylamine emission amount of the recycled foaming styrenic resin particles obtained by the production method according to the embodiment of the present invention, the better.

[0019] The alkylamine is an amine having an alkyl group, and examples include primary amines, secondary amines, and tertiary amines. Specific examples include, as a primary amine, for example, methylamine; as a secondary amine, for example, dimethylamine; and as a tertiary amine, for example, trimethylamine and triethylamine. Particularly, trimethylamine, which is known as the odor of fish, is an alkylamine that can more effectively express the effects of the present invention.

[0020] As a preferred embodiment of the method for producing the expandable recycled styrene resin particles of the present invention, Embodiment (1): A form in which a volatile foaming agent is press-fitted and impregnated into recycled styrene resin particles (A) obtained by adding and polymerizing a styrene monomer to a suspension containing recycled styrene resin raw material particles (a), and water containing 0.01 mg / kg to 103 mg / kg of a metal element is used as the charged water used when preparing the suspension. Embodiment (2): A form in which recycled styrene resin raw material particles (a) are used as recycled styrene resin particles (A), a volatile foaming agent is press-fitted and impregnated into a suspension containing the recycled styrene resin particles (A), and water containing 0.01 mg / kg to 103 mg / kg of a metal element is used as the charged water used when preparing the suspension. Two embodiments are mentioned.

[0021] ≪A-1. Preferred Embodiment (1) of the Method for Producing Expandable Recycled Styrene Resin Particles≫ In the preferred embodiment (1) of the method for producing expandable recycled styrene resin particles, a volatile foaming agent is press-fitted and impregnated into recycled styrene resin particles (A) obtained by adding and polymerizing a styrene monomer to a suspension containing recycled styrene resin raw material particles (a), and water containing 0.01 mg / kg to 103 mg / kg of a metal element is used as the charged water used when preparing the suspension.

[0022] <A-1-1. Recycled Styrene Resin Particles (A) in Embodiment (1)> In Embodiment (1), the recycled styrene resin particles (A) are obtained by adding and polymerizing a styrene monomer to a suspension containing recycled styrene resin raw material particles (a).

[0023] The recycled styrene resin raw material particles (a) may be only one kind or two or more kinds.

[0024] As the material for the recycled styrene resin raw material particles (a), any suitable recycled styrene resin can be used, as long as it does not impair the effects of the present invention. Examples of such recycled styrene resins include expanded polystyrene (molded products, block molded products, etc.), foamed sheets (tray containers, sheet waste, etc.), and recycled plastic materials used in home appliances, packaging containers, cushion beads, etc. The present invention is particularly effective in using recovered raw materials for styrene resin foam molded products that have a strong odor derived from alkylamines, such as fish boxes.

[0025] The recycled styrene-based resin raw material particles (a) may contain any other suitable recycled resins other than recycled styrene-based resins, as long as the effects of the present invention are not impaired. Examples of such other recycled resins include recycled resins of AS resin, ABS resin, HIPS (high-impact polystyrene); polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polycarbonate (PC); polyamide resins such as nylon (PA); and polyolefin resins such as polyethylene (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and EVA (ethylene-vinyl acetate copolymer)). There may be only one type of other resin, or two or more types. In this specification, recycled resins of AS resin, recycled resins of ABS resin, and recycled resins of HIPS (high-impact polystyrene) are not included in the category of recycled styrene-based resins.

[0026] As recycled styrene-based resin raw material particles (a), molded products made from the product names "Epsurem" or "Esrenbeads RNW" manufactured by Sekisui Chemical Co., Ltd. may be used.

[0027] As recycled styrene resin raw material particles (a), a pulverized product obtained by heating and / or reducing the volume of used expanded styrene resin (such as fish boxes) to obtain recycled resin (such as ingots) may be used. As recycled styrene resin raw material particles (a), this pulverized product may be pelletized by extrusion molding, or these pellets may be further pulverized. Alternatively, it may be recovered by reducing the volume using a solvent such as limonene.

[0028] The recycled styrene-based resin raw material particles (a) are preferably pellets obtained by a melt extrusion method. A typical melt extrusion method involves supplying crushed used styrene-based resin, ingots, or foamed particles to a resin supply device, melting them in the resin supply device, extruding them through small holes in a die attached to the tip of the resin supply device, and then cooling them to obtain pellets.

[0029] The pellets obtained by the melt extrusion method described above are preferably at least one selected from the following: extruded strand pellets obtained by extruding used expanded polystyrene resin (fish boxes, a mixture of fish boxes and other used expanded polystyrene resins, a mixture of fish boxes and other used polystyrene resins, etc.) with an extruder and performing strand cutting; underwater cut pellets obtained by an underwater cut method in which used expanded polystyrene resin is cut underwater at the same time as being extruded with an extruder; and hot cut pellets obtained by a hot cut method in which used expanded polystyrene resin particles are cut and cooled immediately after coming out of the die of the extruder.

[0030] As recycled styrene-based resin raw material particles (a), pellets obtained by the above-described melt extrusion method may be used as is, or they may be made into so-called "mini-pellets" by melt extrusion or other methods to obtain smaller pellets.

[0031] The recycled styrene resin raw material particles (a) may be a shrunk or molten product of expanded styrene resin obtained by coarsely crushing used expanded styrene resin to an appropriate size as needed, and then performing processes such as thermal shrinkage, shrinkage due to bubble bursting by compression, shrinkage due to frictional heat, or melting.

[0032] Examples of used expanded polystyrene resins include molded products made by molding expanded polystyrene resin using a mold, and products made by heat-foaming these products.

[0033] The recycled styrene-based resin raw material particles (a) may contain finely powdered inorganic and / or organic lubricants. These can typically function as foam regulators.

[0034] Examples of finely powdered inorganic materials include talc, calcium carbonate, and silica. Here, talc typically refers to a mixture mainly composed of silicon dioxide and magnesium oxide, with trace amounts of aluminum oxide, iron oxide, etc.

[0035] The average particle size of the finely powdered inorganic material is preferably 100 μm or less, and more preferably 30 μm or less. If the average particle size of the finely powdered inorganic material exceeds 100 μm, the effect of reducing the bubble size of the recycled pre-expanded styrene resin particles may decrease.

[0036] The content of finely powdered inorganic matter is preferably 0.1% to 5% by mass, and more preferably 0.5% to 2% by mass, relative to the recycled styrene-based resin raw material particles (a). If the content of finely powdered inorganic matter relative to the recycled styrene-based resin raw material particles (a) is less than 0.1% by mass, the effect of reducing the bubble size of the recycled pre-expanded styrene-based resin particles may decrease. If the content of finely powdered inorganic matter relative to the recycled styrene-based resin raw material particles (a) exceeds 5% by mass, the bubble size of the recycled pre-expanded styrene-based resin particles becomes extremely small, and the recycled pre-expanded styrene-based resin particles may melt during molding, potentially degrading the appearance of the molded product.

[0037] Examples of organic lubricants include liquid paraffin; polyethylene glycol; silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane; higher fatty acid bisatomids such as methylenebisstearylamide, ethylenebisstearylamide, and ethylenebisoleamide; and metal salts of higher fatty acids such as zinc stearate, magnesium stearate, and zinc oleate.

[0038] The content of the organic lubricant is preferably 0.01% to 2.0% by mass, more preferably 0.02% to 1.8% by mass, and in some cases even more preferably 0.02% to 0.2% by mass, and particularly preferably 0.02% to 0.1% by mass, relative to the recycled styrene resin raw material particles (a). If the content 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-expanded styrene resin particles may decrease. If the content of the organic lubricant relative to the recycled styrene resin raw material particles (a) exceeds 2.0% by mass, the bubble size of the recycled pre-expanded styrene resin particles becomes extremely small, the recycled pre-expanded styrene resin particles may melt during molding, and the appearance of the molded product tends to be poor.

[0039] A specific method for incorporating finely powdered inorganic and / or organic lubricants into recycled styrene-based resin raw material particles (a) is, for example, a method of kneading the finely powdered inorganic and / or organic lubricants during extrusion molding. In this case, preferably, the pulverized material and the foam regulator are mixed beforehand before extrusion molding. The method of mixing the pulverized material and the foam regulator can be any suitable method as long as it does not impair the effects of the present invention. Examples of such methods include mixing using mixers such as tumblers, ribbon blenders, V-blenders, Henschel mixers, and Readygay mixers.

[0040] The recycled styrene-based resin raw material particles (a) are preferably thermally melted for the purpose of adjusting their specific gravity. In this step, the specific gravity of the recycled styrene-based resin raw material particles (a) is preferably adjusted to 0.6 or higher, and more preferably to 0.9 or higher. If the specific gravity of the recycled styrene-based resin raw material particles (a) is less than 0.6, the dispersion of the recycled styrene-based resin raw material particles (a) is unstable, which may lead to the generation of excessive particles during the subsequent polymerization step and a decrease in yield. The thermal melting of the recycled styrene-based resin raw material particles (a) can be carried out by any suitable method that does not impair the effects of the present invention. Examples of such methods include using an extruder or a hot roll. It is preferable that the thermal melting is followed by cooling and solidification in a state where no strain remains in the obtained resin, or where the strain is small. If strain remains in the resin particles, the strain will be relieved in the subsequent step, causing shrinkage in the stretching direction, and the resulting recycled foamable styrene-based resin particles may not be spherical but flattened. Therefore, it is preferable to perform thermal melting without stretching using an extruder. If thermal melting is performed in a stretched state, there is a risk that strain will remain in the stretched resin obtained after cooling and solidification. However, even if strain remains in the resin due to thermal melting, the strain can be alleviated by curing it at a temperature above the resin's softening point for a certain period of time.

[0041] When obtaining recycled styrene-based resin raw material particles (a), any type of pulverizer can be used for grinding, as long as it does not impair the effects of the present invention. For example, a pulverizer for plastics can be used, and a pulverizer for polystyrene is preferred.

[0042] The recycled styrene-based resin raw material particles (a) can be sieved as needed and then subjected to melting again using an extruder or the like.

[0043] The average particle diameter of the recycled styrene-based resin raw material particles (a) is preferably 0.2 mm to 3.0 mm, more preferably 0.3 mm to 2.5 mm, even more preferably 0.4 mm to 2.0 mm, and particularly preferably 0.5 mm to 1.7 mm. If the average particle diameter of the recycled styrene-based resin raw material particles (a) exceeds 3 mm, the resulting recycled foamed styrene-based resin particles may not be spherical. If the average particle diameter of the recycled styrene-based resin raw material particles (a) is less than 0.2 mm, the resulting recycled foamed styrene-based resin particles may have an average particle diameter that is too small.

[0044] The L (long side) / D (short side) ratio of the recycled styrene-based resin raw material particles (a) is preferably 1.0 to 6.0, more preferably 1.0 to 5.0, even more 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) ratio of the recycled styrene-based resin raw material particles (a) falls outside the above range, the resulting recycled foamable styrene-based resin particles may not be spherical.

[0045] It is preferable that the recycled styrene-based resin raw material particles (a) contain less than 1% by mass of particles with an average particle diameter of 200 μm or less. If the recycled styrene-based resin raw material particles (a) contain 1% or more by mass of particles with an average particle diameter of 200 μm or less, the appearance of the recycled foamed styrene-based resin particles obtained using them may deteriorate.

[0046] The weight-average molecular weight of the recycled styrene-based resin raw material particles (a) is preferably 100,000 to 510,000, and more preferably 150,000 to 490,000. If the weight-average molecular weight of the recycled styrene-based 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-based resin raw material particles (a) exceeds 510,000, the recycled styrene-based resin raw material particles may not form spherical shapes easily, and the foaming properties may decrease, resulting in a poor appearance of the molded product.

[0047] The styrene monomer may be one type or two or more types.

[0048] The styrene monomer includes styrene or a styrene derivative. Examples of styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. The styrene monomer may be one type or two or more types. The styrene monomer preferably contains at least styrene. The styrene content relative to the total amount of the styrene monomer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0049] The styrene monomer may contain any suitable vinyl monomer other than the styrene monomer, as long as it does not impair the effects of the present invention. Examples include polyfunctional monomers, (meth)acrylic acid monomers, maleic acid monomers, and fumaric acid monomers. Such vinyl monomers may be one type or two or more types.

[0050] Specific examples of polyfunctional monomers include, for example, divinylbenzenes such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; and alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate. Specific examples of (meth)acrylic acid ester monomers include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and hexyl (meth)acrylate. An example of a maleic acid ester monomer is dimethyl maleate. An example of a fumarate ester monomer is dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

[0051] The content ratio of recycled styrene-based resin raw material particles (a) to the total amount of recycled styrene-based resin raw material particles (a) and styrene monomers is preferably 10% to 90% by mass, more preferably 15% to 85% by mass, even more preferably 20% to 80% by mass, particularly preferably 23% to 80% by mass, and most preferably 25% to 80% by mass. If the above content ratio is too low and falls outside the above range, the environmental contribution may be reduced. Also, if the above content ratio is too low or too high and falls outside the above range, good spheroidization may not occur in the recycled foamable styrene-based resin particles according to the embodiment of the present invention, and moldability may be reduced.

[0052] Recycled styrene resin particles (A) are obtained by adding styrene monomers to a suspension containing recycled styrene resin raw material particles (a) and polymerizing them. Any suitable polymerization method can be used as long as it does not impair the effects of the present invention. One preferred embodiment of such polymerization is a method in which recycled styrene resin raw material particles (a) are dispersed in water with the recycled styrene resin raw material particles (a) as nuclei, an emulsion containing a polymerization initiator and styrene monomers is added to the suspension to impregnate the recycled styrene resin raw material particles (a), and then styrene monomers are added to carry out polymerization.

[0053] In the present invention, when preparing the suspension containing recycled styrene-based resin raw material particles (a), it is preferable to use water in which the total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in the water is 0.01 mg / kg to 103 mg / kg in terms of concentration. By using water containing metal elements at such specific concentrations as the water used when preparing the suspension, recycled foamable styrene-based resin particles can be obtained with suppressed odors, particularly odors derived from alkylamines.

[0054] The above concentration in the brewing water is preferably 0.01 mg / kg to 100 mg / kg, more preferably 0.01 mg / kg to 95 mg / kg, even more preferably 0.01 mg / kg to 90 mg / kg, even more preferably 0.01 mg / kg to 85 mg / kg, particularly preferably 0.01 mg / kg to 80 mg / kg, and most preferably 0.01 mg / kg to 75 mg / kg, in order to better exhibit the effects of the present invention.

[0055] If the concentration in the brewing water is too low and outside the above range, the effects of the present invention may not be easily realized, and in particular, the odor derived from alkylamine may become stronger. If the concentration in the brewing water is too high and outside the above range, the effects of the present invention may not be easily realized, and in particular, the metallic odor may become stronger.

[0056] When obtaining recycled styrene-based resin particles (A), the addition temperature when adding styrene monomers to recycled styrene-based 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, even more preferably 50°C to 117°C, and particularly preferably 60°C to 115°C, in order to better exhibit the effects of the present invention. By adjusting the addition temperature when adding styrene monomers to recycled styrene-based resin raw material particles (a) within the above range, the styrene monomers can be incorporated while maintaining the recycled styrene-based resin raw material particles (a) at an appropriate hardness, thereby enabling good spheroidization of recycled styrene-based resin particles (A), and ultimately resulting in recycled foamable styrene-based resin particles with good spheroidization and excellent moldability. If the addition temperature when adding styrene monomers to recycled styrene resin raw material particles (a) is too low and outside the above range, the recycled styrene resin raw material particles (a) will become too hard. When styrene monomers are incorporated in this state, the recycled styrene resin particles (A) will have difficulty becoming spherical, and the resulting recycled foamed styrene resin particles may have difficulty becoming spherical or have poor moldability. If the addition temperature when adding styrene monomers to recycled styrene resin raw material particles (a) is too high and outside the above range, the recycled styrene resin raw material particles (a) will become too soft. When styrene monomers are incorporated in this state, the recycled styrene resin particles (A) will have difficulty becoming spherical, and the resulting recycled foamed styrene resin particles may have difficulty becoming spherical or have poor moldability. Furthermore, the "addition temperature when adding styrene monomers to recycled styrene resin raw material particles (a)" as used herein refers to the addition temperature during the addition of the emulsion containing the polymerization initiator and styrene monomers, and the subsequent addition of styrene monomers.

[0057] When obtaining a suspension by dispersing recycled styrene-based resin raw material particles (a) in an aqueous medium with the particles acting as nuclei, any suitable method can be used for dispersing the recycled styrene-based resin raw material particles (a) in the aqueous medium, as long as it does not impair the effects of the present invention. Preferably, such a dispersion method involves using a device equipped with a stirring blade. A method for even finer dispersion can be achieved by using a homomixer.

[0058] When obtaining a suspension by dispersing recycled styrene-based resin raw material particles (a) in an aqueous medium with the particles as a nucleus, it is preferable to use a dispersant in the dispersion of the recycled styrene-based resin raw material particles (a) in the aqueous medium. Any suitable dispersant can be used as long as it can be used in suspension polymerization and does not impair the effects of the present invention. Examples of such dispersants include organic dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, and methylcellulose; and sparingly soluble inorganic salts such as magnesium pyrophosphate and tricalcium phosphate. Among these, magnesium pyrophosphate is preferred as a dispersant because it can better express the effects of the present invention.

[0059] The blending ratio of the dispersant to 100 parts by mass of recycled styrene resin particles (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 part by mass.

[0060] When obtaining a suspension by dispersing recycled styrene resin raw material particles (a) in an aqueous medium with the particles as nuclei, it is preferable to use a surfactant in the dispersion of the recycled styrene resin raw material particles (a) in the aqueous medium. Any suitable surfactant can be used as long as it can be used in suspension polymerization and does not impair the effects of the present invention. Examples of such surfactants include sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylsulfonate, sodium alkyldiphenyl ether disulfonate, and sodium α-olefin sulfonate. Among these, sodium dodecylbenzenesulfonate is preferred as the surfactant because it can better express the effects of the present invention.

[0061] The blending ratio of surfactant to 100 parts by mass of recycled styrene resin particles (A) is preferably 0.005 parts by mass to 0.1 parts by mass, more preferably 0.005 parts by mass to 0.08 parts by mass, and even more preferably 0.005 parts by mass to 0.06 parts by mass.

[0062] As for the method of emulsion when obtaining an emulsion containing a polymerization initiator and styrene monomers, any suitable method can be used as long as it does not impair the effects of the present invention. Preferably, such a dispersion method is dispersion using an apparatus equipped with a stirring blade. As a method for finer dispersion, a homomixer can be used. In this case, it is preferable to disperse until the oil droplet diameter of the dispersion containing the styrene monomers is less than or equal to the particle diameter of the nucleus. This is because if the oil droplet diameter is larger than the particle diameter of the nucleus when added to an aqueous medium, multiple recycled styrene resin raw material particles (a) will be incorporated into the oil droplets of the dispersion containing the styrene monomers, causing adhesion, plasticization, and coalescence of the recycled styrene resin raw material particles (a), which can easily lead to the generation of excessively large particles.

[0063] When obtaining an emulsion containing a polymerization initiator and a styrene monomer, any suitable polymerization initiator can be used as the polymerization initiator, as long as it is used in suspension polymerization and does not impair the effects of the present invention. Examples of such polymerization initiators include organic peroxides such as benzoyl peroxide, t-butyl peroxy-2-ethylhexyl carbonate, and t-butyl perbenzoate; and azo compounds such as azobisisobutyronitrile. There may be only one polymerization initiator or two or more.

[0064] The amount of polymerization initiator used is preferably 0.1% to 1.0% by mass, and more preferably 0.1% to 0.8% by mass, relative to the styrene monomer.

[0065] The polymerization initiator is preferably added dissolved in a styrene monomer or a solvent. Examples of solvents 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.

[0066] As for the method of adding styrene monomers after impregnating a suspension containing recycled styrene resin raw material particles (a) with an emulsion containing styrene monomers, any suitable method can be used as long as it does not impair the effects of the present invention. Examples of such methods include partial addition and continuous addition. The addition rate is appropriately selected according to the capacity and shape of the polymerization apparatus, polymerization temperature, etc.

[0067] After impregnating a suspension containing recycled styrene resin raw material particles (a) with an emulsion containing styrene monomers, the polymerization reaction may be continued at any appropriate temperature and time as needed.

[0068] The suspension containing the recycled styrene-based resin raw material particles (a) or the emulsion containing the styrene-based monomer may contain a bubble regulator. Examples of such a bubble regulator include fatty acid monoamides such as oleic acid amide, stearic acid amide, and hydroxystearic acid amide; fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide.

[0069] <A-1-2. Pressurization and impregnation of the foaming agent in Embodiment (1)> In Embodiment (1), the recycled foamed styrene-based resin particles are obtained by pressurizing and impregnating the recycled styrene-based resin particles (A) with a foaming agent.

[0070] Typical examples of the method for pressurizing and impregnating the foaming agent in Embodiment (1) include a method in which the recycled styrene-based resin particles (A) are placed in a reactor such as an autoclave and the foaming agent is pressurized and impregnated.

[0071] The blending ratio of the dispersant with respect to 100 parts by mass of the recycled styrene-based resin particles (A) is preferably 0.1 part by mass to 2 parts by mass, more preferably 0.1 part by mass to 1.5 parts by mass, and even more preferably 0.1 part by mass to 1.0 part by mass.

[0072] The foaming agent may be only one kind or two or more kinds.

[0073] Any suitable blowing agent can be used as the blowing agent, as long as it does not impair the effects of the present invention. Preferably, the blowing agent is an organic compound that has a boiling point below the softening point of the styrene resin and is gaseous or liquid at atmospheric pressure. Specific examples include, for 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 isopropyl alcohol; low-boiling point ether compounds such as dimethyl ether, diethyl ether, dipropyl ether, and methyl ethyl ether; halogen-containing hydrocarbons such as trichloromonofluoromethane and dichlorodifluoromethane; and others. Inorganic gases such as carbon dioxide, nitrogen, and ammonia may also be used as blowing agents. Among these, the foaming 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, in order to better exhibit the effects of the present invention.

[0074] The amount of foaming agent can be appropriately set according to the purpose, as long as it is in an amount sufficient to form recycled pre-foamed styrene resin particles and recycled styrene resin foam molded articles. The amount of foaming agent is preferably 2 to 15 parts by mass when the total amount of recycled styrene resin raw material particles (a) and styrene monomers is 100 parts by mass.

[0075] The injection temperature of the foaming agent into the recycled styrene resin particles (A) can be any suitable temperature within a range that does not impair the effects of the present invention. Such an injection temperature is preferably 50°C to 150°C, and particularly preferably 55°C to 140°C.

[0076] The impregnation temperature of the foaming agent into the recycled styrene-based resin particles (A) can be any appropriate temperature as long as the effects of the present invention are not impaired. Such an impregnation temperature is preferably 50°C to 150°C, particularly preferably 55°C to 140°C.

[0077] The pressure injection temperature and the impregnation temperature of the foaming agent into the recycled styrene-based resin particles (A) may be the same or different.

[0078] The impregnation time of the foaming agent into the recycled styrene-based resin particles (A) can be any appropriate time as long as the effects of the present invention are not impaired. Such an impregnation time is preferably 1 hour to 10 hours.

[0079] <A-1-3. Other components in Embodiment (1)> In Embodiment (1), the recycled foamed styrene-based resin particles may contain any appropriate other components as long as the effects of the present invention are not impaired. Such other components may be only one kind or two or more kinds.

[0080] The recycled foamed styrene-based resin particles may contain a flame retardant as another component in order to enhance the flame retardancy. The flame retardant may be only one kind or two or more kinds.

[0081] As a flame retardant, any suitable flame retardant can be used as long as it does not impair the effects of the present invention. Preferred flame retardants include bromine compounds that are compatible with polystyrene, such as tetrabromoethane, tetrabromocyclooctane, hexabromocyclododecane, hexabromocyclohexane, trisdibromopropyl 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-alyroxy-3,5-dibromo)propane, and hexabromobenzene.

[0082] When using flame retardants, flame retardant additives may be used in combination. Examples of flame retardant additives include cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and 3,4-dimethyl-3,4-diphenylhexane.

[0083] The total amount of flame retardant and flame retardant aid used can be any appropriate amount, as long as it does not impair the effects of the present invention. Such an amount is preferably 0.1% to 5% by mass, and more preferably 0.2% to 3% by mass, relative to the recycled styrene resin particles (A).

[0084] The flame retardant can be added at any appropriate time, as long as it does not impair the effects of the present invention. It is preferable that the flame retardant be added before the volatile blowing agent is injected, as this allows for better expression of the present invention's effects. By adding the flame retardant before the volatile blowing agent is injected, the flame retardant can be added at a temperature as low as that at which the volatile blowing agent is injected, thereby enabling good spheroidization and excellent moldability of the resulting regenerated foamable styrene-based resin particles.

[0085] The temperature at which the flame retardant is added is preferably 5°C to 120°C, more preferably 5°C to 118°C, even more preferably 5°C to 115°C, particularly preferably 5°C to 113°C, and most preferably 5°C to 110°C, in order to better exhibit the effects of the present invention.

[0086] In Embodiment (1), when producing recycled foamable styrene-based resin particles, a foam regulator may be used. There may be only one type of foam regulator, or there may be two or more types. Examples of foam regulators include higher fatty acid amides, partial esters of higher fatty acids and alcohols, talc, calcium carbonate, mica, citric acid, and sodium bicarbonate. Examples of higher fatty acid amides include fatty acid monoamides such as oleamide, stearamide, and hydroxystearamide; and fatty acid bisamides such as methylenebisstearamide and ethylenebisstearamide. Examples of higher fatty acids in partial esters of higher fatty acids and alcohols include fatty acids with 15 or more carbon atoms such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and behenic acid. Examples of partial esters of higher fatty acids and alcohols include monoglyceride stearate and diglyceride stearate.

[0087] The amount of foam regulator used is preferably 0 to 5.0 parts by mass, and more preferably 0.03 to 3.0 parts by mass, per 100 parts by mass of recycled styrene-based resin raw material (A). Methods for adding the foam regulator include, for example, adding it together with a foaming agent, or using commonly used methods such as dry blending, masterbatch, or melt injection.

[0088] In Embodiment (1), when producing the recycled expandable styrene resin particles, a foaming aid may be used. That is, in Embodiment (1), the recycled expandable styrene resin particles may contain a foaming aid. 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.

[0089] In Embodiment (1), when producing the recycled expandable styrene resin particles, a cell regulator may be used. That is, in Embodiment (1), the recycled expandable styrene resin particles may contain a cell regulator. The cell regulator may be only one kind or two or more kinds. Examples of the cell regulator include fatty acid monoamides such as oleic acid amide, stearic acid amide, and hydroxystearic acid amide; fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide.

[0090] In Embodiment (1), the recycled expandable styrene resin particles may contain a cell regulator such as talc, calcium carbonate, mica, citric acid, and sodium bicarbonate. The cell regulator may be only one kind or two or more kinds.

[0091] Other components include, in addition to these, for example, pigments, radiant heat suppression components, crosslinking agents, plasticizers, stabilizers, fillers, lubricants, colorants, antistatic agents, spreading agents, weathering agents, antioxidants, antifogging agents, and fragrances.

[0092] <A-1-4. Surface Treatment> In Embodiment (1), the recycled expandable styrene resin particles may be subjected to surface treatment. Such surface treatment is preferably surface treatment with at least one selected from silicone oil, antistatic agent, fatty acid metal salt, and fusion promoter.

[0093] In Embodiment (1), when surface treatment with silicone oil is performed on recycled foamable styrene resin particles, the amount of silicone oil used per 100 parts by mass of recycled foamable styrene resin particles before surface treatment is preferably 0.001 parts by mass to 0.3 parts by mass, more preferably 0.003 parts by mass to 0.28 parts by mass, even more preferably 0.005 parts by mass to 0.25 parts by mass, particularly preferably 0.008 parts by mass to 0.23 parts by mass, and most preferably 0.01 parts by mass to 0.23 parts by mass. If the amount of silicone oil used is too little and outside the above range, for example, when an antistatic agent is used, the affinity with the antistatic agent may not be sufficient during pre-foaming, which may make it easier for static electricity to be generated. If the amount of silicone oil used is too much and outside the above range, the surface may be lost due to the surface melting during molding, etc.

[0094] The silicone oil may be of one type or two or more types.

[0095] Any suitable silicone oil can be used as the silicone oil, as long as it does not impair the effects of the present invention. In terms of being able to better express the effects of the present invention, examples of straight silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane are used, and methylphenylpolysiloxane is preferred.

[0096] In Embodiment (1), when the recycled foamed styrene resin particles are surface-treated with an antistatic agent, the amount of antistatic agent used per 100 parts by mass of recycled foamed styrene resin particles before surface treatment is preferably 0.001 parts by mass to 0.3 parts by mass, more preferably 0.005 parts by mass to 0.28 parts by mass, even more preferably 0.01 parts by mass to 0.27 parts by mass, particularly preferably 0.015 parts by mass to 0.26 parts by mass, and most preferably 0.02 parts by mass to 0.25 parts by mass. If the amount of antistatic agent is too small and outside the above range, static electricity may be easily generated during pre-foaming. If the amount of antistatic agent is too large and outside the above range, the surface of the recycled pre-foamed styrene resin particles or the recycled styrene resin foam molded article may become sticky.

[0097] The antistatic agent may be one type or two or more types.

[0098] As an antistatic agent, any suitable antistatic agent can be used as long as it does not impair the effects of the present invention. In terms of being able to better exhibit the effects of the present invention, at least one selected from nonionic surfactants and fatty acid glycerides can be used as an antistatic agent, and preferably a combination of a nonionic surfactant and a fatty acid glyceride.

[0099] The nonionic surfactant may be one type or two or more types.

[0100] As the nonionic surfactant, any suitable nonionic surfactant can be used as long as it does not impair the effects of the present invention. Examples of nonionic surfactants that can better express the effects of the present invention include polyethylene glycol, glycerin, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyhydric alcohols, and 1-amino-2-hydroxy compounds. Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. Specific examples of polyoxyethylene alkyl esters include polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, and polyoxyethylene oleate. Specific examples of polyhydric alcohols include glycerin and propylene glycol. Examples of 1-amino-2-hydroxy compounds include, for example, 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, and N-hydroxypropyl-N Examples include -(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, and their salts.Polyethylene glycol is preferred as the nonionic surfactant in terms of being able to better exhibit the effects of the present invention.

[0101] When a nonionic surfactant is used as at least a part of the antistatic agent, the amount of the nonionic surfactant used per 100 parts by mass of regenerated foamable styrene-based resin particles before surface treatment is preferably 0.001 to 2.0 parts by mass, more preferably 0.001 to 1.5 parts by mass, even more preferably 0.001 to 1.0 parts by mass, even more preferably 0.001 to 0.5 parts by mass, even more preferably 0.001 to 0.3 parts by mass, even more preferably 0.005 to 0.28 parts by mass, even more 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 nonionic surfactant is too small and falls outside the above range, static electricity may easily be generated during pre-foaming. If the amount of nonionic surfactant exceeds the above range, the surface of the recycled pre-expanded styrene resin particles or the recycled styrene resin foam molded product may become sticky.

[0102] The fatty acid glycerides may be one type or two or more types.

[0103] Any suitable fatty acid glyceride can be used as the fatty acid glyceride, as long as it does not impair the effects of the present invention. Specifically, examples of fatty acid glycerides that can better express the effects of the present invention include monoglyceride stearate and monoglyceride linoleate. Monoglyceride stearate is preferred as the fatty acid glyceride in terms of better expressing the effects of the present invention.

[0104] When fatty acid glycerides are used as at least a part of the antistatic agent, the amount of fatty acid glycerides per 100 parts by mass of recycled foamable styrene resin particles before surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, even more 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 glycerides is too small and outside the above range, static electricity may be easily generated during pre-foaming. If the amount of fatty acid glycerides is too large and outside the above range, the surface of the recycled pre-foamed styrene resin particles or the recycled styrene resin foam molded product may become sticky.

[0105] In Embodiment (1), when surface treatment with a fatty acid metal salt is performed on recycled foamable styrene resin particles, the amount of fatty acid metal salt used per 100 parts by mass of recycled foamable styrene resin particles before surface treatment is preferably 0.005 parts by mass to 0.5 parts by mass, more preferably 0.007 parts by mass to 0.45 parts by mass, even more preferably 0.01 parts by mass to 0.4 parts by mass, particularly preferably 0.015 parts by mass to 0.35 parts by mass, and most preferably 0.02 parts by mass to 0.3 parts by mass. If the amount of fatty acid metal salt is too small and outside the above range, a lot of blocking may occur during pre-foaming, and a good styrene resin foam molded article may not be obtainable. If the amount of fatty acid metal salt is too large and outside the above range, a large amount of metal salt will be present during pre-foaming, making it easier to become charged and generating static electricity, which may result in poor fusion of the molded article.

[0106] The fatty acid metal salt may be one type or two or more types.

[0107] As the fatty acid metal salt, any suitable fatty acid metal salt can be used as long as it does not impair the effects of the present invention. Examples of fatty acid metal salts that can better express the effects of the present invention include stearate metal salts and laurate metal salts. Specific examples of stearate metal salts include magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate. Specific examples of laurate metal salts include zinc laurate and barium laurate. Magnesium stearate and zinc stearate are preferred as fatty acid metal salts that can better express the effects of the present invention.

[0108] In Embodiment (1), when the recycled foamable styrene resin particles are surface-treated with a fusion accelerator, the amount of fusion accelerator used per 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, even more 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 fusion accelerator is too small and outside the above range, the fusion properties will decrease during molding, and it may not be possible to obtain a good recycled styrene resin foam molded article. If the amount of fusion accelerator is too large and outside the above range, blocking may occur during pre-foaming.

[0109] The fusion accelerator may be one type or two or more types.

[0110] As the fusion promoter, any appropriate fusion promoter can be adopted as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, examples of the fusion promoter include fatty acid triglycerides, fatty acid diglycerides, fatty acid monoglycerides, and vegetable oils. Specific examples of the fatty acid triglycerides include, for example, lauric acid triglyceride, stearic acid triglyceride, linoleic acid triglyceride, and hydroxystearic acid triglyceride. Specific examples of the fatty acid diglycerides include, for example, lauric acid diglyceride, stearic acid diglyceride, and linoleic acid diglyceride. Specific examples of the fatty acid monoglycerides include, for example, lauric acid monoglyceride. Specific examples of the vegetable oils include, for example, hydrogenated castor oil. In terms of being able to more effectively exhibit the effects of the present invention, stearic acid triglyceride and hydroxystearic acid triglyceride are preferred as the fusion promoter.

[0111] ≪A-2. Preferred Embodiment (2) of Method for Producing Recyclable Foamed Styrene Resin Particles≫ In the preferred embodiment (2) of the method for producing recyclable foamed styrene resin particles, recycled styrene resin raw material particles (a) are used as recycled styrene resin particles (A), and a volatile foaming agent is press-fitted and impregnated into the suspension containing the recycled styrene resin particles (A). As the charged water used when preparing the suspension, water containing 0.01 mg / kg to 103 mg / kg of metal elements is used.

[0112] <A-2-1. Recycled Styrene Resin Particles (A) in Embodiment (2)> In embodiment (2), the recycled styrene resin particles (A) are directly used as the recycled styrene resin raw material particles (a). For the recycled styrene resin raw material particles (a), the description of the recycled styrene resin raw material particles (a) in the item of <A-1-1. Recycled Styrene Resin Particles (A) in Embodiment (1)> described above can be incorporated.

[0113] <A-2-2. Press-Fitting and Impregnation of Volatile Foaming Agent in Embodiment (2)> In Embodiment (2), the recycled expandable styrenic resin particles are obtained by press-fitting and impregnating a volatile foaming agent into a suspension containing recycled styrenic resin particles (A) obtained by directly using recycled styrenic resin raw material particles (a).

[0114] As a method for press-fitting and impregnating the volatile foaming agent in Embodiment (2), typically, a method of press-fitting and impregnating a volatile foaming agent into a suspension containing recycled styrenic resin particles (A) (directly using recycled styrenic resin raw material particles (a)) in a reactor such as an autoclave can be mentioned.

[0115] Regarding the press-fitting and impregnation method, the description in the item of <A-1-2. Press-fitting and impregnation of the volatile foaming agent in Embodiment (1)> described above can be incorporated.

[0116] By incorporating the description in the item of <A-1-2. Press-fitting and impregnation of the volatile foaming agent in Embodiment (1)> described above, in Embodiment (2), as the charged water used when preparing a suspension containing recycled styrenic resin particles (A) (directly using recycled styrenic resin raw material particles (a)), preferably, water in which the total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, Zn is 0.01 mg / kg to 103 mg / kg as a concentration is used. By using water containing metal elements at the above specific concentrations as the charged water when preparing the above suspension, recycled expandable styrenic resin particles with suppressed odor, particularly the odor derived from alkylamine, can be obtained.

[0117] The above concentration in the charged water is preferably 0.01 mg / kg to 100 mg / kg, more preferably 0.01 mg / kg to 95 mg / kg, still more preferably 0.01 mg / kg to 90 mg / kg, still more preferably 0.01 mg / kg to 85 mg / kg, particularly preferably 0.01 mg / kg to 80 mg / kg, and most preferably 0.01 mg / kg to 75 mg / kg in terms of more effectively expressing the effects of the present invention.

[0118] If the concentration in the charged water is too low outside the above range, the effects of the present invention may be difficult to be manifested, and in particular, the odor derived from alkylamine may become strong. If the concentration of the metal element in the charged water is too high outside the above range, the effects of the present invention may be difficult to be manifested, and in particular, the metallic odor may become strong.

[0119] <A-2-3. Other components in Embodiment (2)> In Embodiment (2), the recycled expandable styrene resin particles may contain any suitable other components as long as the effects of the present invention are not impaired. Such other components may be only one kind or two or more kinds. Regarding other components, the description of other components in the item of <A-1-3. Other components in Embodiment (1)> described above can be incorporated.

[0120] <C <A-2-4. Surface treatment> In Embodiment (2), the recycled expandable styrene resin particles may be subjected to surface treatment. Regarding the surface treatment, the description in the item of <A-1-4. Surface treatment> described above can be incorporated.

[0121] ≪≪B. Recycled expandable styrene resin particles≫≫ The recycled expandable styrene resin particles according to the embodiment of the present invention are obtained by the method for producing the recycled expandable styrene resin particles according to the embodiment of the present invention.

[0122] Since the recycled expandable styrene resin particles according to the embodiment of the present invention are obtained by the method for producing the recycled expandable styrene resin particles according to the embodiment of the present invention, the odor, particularly the odor derived from alkylamine, is effectively suppressed, and the alkylamine emission amount is preferably less than 5 ng / g, more preferably less than 4 ng / g, still more preferably less than 3 ng / g, particularly preferably less than 2 ng / g, and most preferably less than 1 ng / g. The lower the alkylamine emission amount, the better, and preferably it is 0 ng / g.

[0123] The recycled foamed styrene resin particles according to the embodiments of the present invention have a particle shape as a whole. The average particle diameter of the recycled foamed 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 diameter can be measured in accordance with JIS Z 8815. Specifically, the average particle diameter is the value measured as the particle size of 50% of the cumulative value from the particle size distribution obtained by the sieving test of JIS Z 8815.

[0124] The shape of the recycled foamed styrene resin particles according to the embodiments of the present invention can be any appropriate shape, as long as it does not impair the effects of the present invention. Specific examples of such shapes include, for example, spherical, substantially spherical, and ellipsoidal (egg-shaped). In terms of exhibiting the effects of the present invention, the shape of the recycled foamed styrene resin particles according to the embodiments of the present invention is preferably spherical, substantially spherical, and more preferably spherical. However, in practice, it is difficult to distinguish between spherical and substantially spherical shapes; therefore, in this specification, both are collectively referred to as spherical.

[0125] The weight-average molecular weight of the regenerated foamable styrene-based resin particles according to the embodiments of the present invention can be any appropriate weight-average molecular weight, as long as it does not impair the effects of the present invention. Such a weight-average molecular weight is preferably 100,000 to 510,000, more preferably 110,000 to 490,000, even more preferably 120,000 to 470,000, and particularly preferably 130,000 to 460,000.

[0126] <<<C. Recycled Pre-Expanded Styrene Resin Particles>>> 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.

[0127] Since the recycled pre-foamed styrene resin particles according to the embodiment of the present invention are obtained by pre-foaming the recyclable foamable styrene resin particles according to the embodiment of the present invention, odors, particularly those derived from alkylamines, can be effectively suppressed.

[0128] The recycled pre-expanded styrene resin particles preferably have an average bubble diameter of 0.01 mm to 0.80 mm, more preferably 0.01 mm to 0.70 mm, even more 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 recycled pre-expanded styrene resin particles is within the above range, blocking during foaming and molding can be better prevented, and furthermore, while suppressing electrostatic charge during foaming and molding, better fusion properties and surface properties can be exhibited, making it possible to mold recycled styrene resin foam molded articles with less static electricity. If the average bubble diameter of the recycled pre-expanded styrene resin particles is smaller than 0.01 mm, there is a risk that the surface will melt and shrink during molding.

[0129] Pre-foaming involves foaming recycled foamable styrene-based resin particles to a desired bulk expansion ratio (bulk density) using water vapor or the like. The bulk expansion ratio of the recycled pre-foamed styrene-based 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, even more preferably 10 to 85 times, and particularly preferably 15 to 83 times. The bulk density is the reciprocal of the bulk expansion ratio. By having the bulk expansion ratio of the recycled pre-foamed styrene-based resin particles within the above range, blocking during foaming and molding can be further prevented, and furthermore, recycled pre-foamed styrene-based resin particles can be provided that exhibit better fusion properties and surface properties while further suppressing electrostatic charge during foaming and molding, and that recycled styrene-based resin foam molded articles with less static electricity can be molded.

[0130] In one representative embodiment, recycled pre-expanded styrene resin particles can be used in the molding of recycled styrene resin foam molded articles. In another embodiment, recycled pre-expanded styrene resin particles can be used as is as a cushioning material, heat insulating material, concrete aggregate, etc. When recycled pre-expanded styrene resin particles are used as is, they can preferably be used as a filler in which a large number of recycled pre-expanded styrene resin particles are filled into a bag. Such recycled pre-expanded styrene resin particles are suitable, for example, as a core material for cushions (foamed granules filled inside cushions).

[0131] <<<D. Recycled styrene-based resin foam molded product>>> The recycled styrene-based resin foam molded article according to the embodiment of the present invention is molded from recycled pre-expanded styrene-based resin particles according to the embodiment of the present invention. Since the recycled styrene-based resin foam molded article according to the embodiment of the present invention is molded from recycled pre-expanded styrene-based resin particles according to the embodiment of the present invention, odors, particularly those derived from alkylamines, can be effectively suppressed.

[0132] Furthermore, the recycled styrene-based resin foam molded article according to the embodiment of the present invention may be molded from recycled foamable styrene-based resin particles according to the embodiment of the present invention.

[0133] Recycled styrene-based foam molded articles typically include recycled expanded styrene-based resin particles (hereinafter sometimes simply referred to as "foamed particles") which are obtained by further foaming recycled pre-expanded styrene-based resin particles.

[0134] Recycled styrene-based foamed molded articles are typically composed of multiple foamed particles that are fused together.

[0135] A recycled styrene foam molded article can typically be produced by placing recycled pre-expanded styrene resin particles into a mold having a predetermined shape according to the purpose, and performing in-mold foam molding. More specifically, in-mold foam molding includes (i) filling a closed mold having a large number of small holes with recycled pre-expanded styrene resin particles, (ii) heating and foaming the recycled pre-expanded styrene resin particles with a heat transfer medium (e.g., pressurized steam) to obtain foamed particles, and (iii) filling the gaps between the foamed particles and fusing the foamed particles together to form a single integrated product through this heating and foaming. The density of the recycled styrene foam molded article can be appropriately set according to the purpose. The density of the recycled styrene foam molded article can be adjusted, for example, by pre-adjusting the bulk expansion ratio of the pre-expanded styrene resin particles to be filled into the mold, or by adjusting the amount of recycled pre-expanded styrene resin particles to be filled into the mold.

[0136] The heating foaming temperature (essentially the temperature of the heat transfer medium) is preferably 90°C to 150°C, more preferably 110°C to 130°C. The heating foaming time is preferably 5 seconds to 50 seconds, more preferably 10 seconds to 50 seconds. The molding vapor pressure (gauge pressure of the heat transfer medium) during heating foaming is preferably 0.04 MPa to 0.1 MPa, more preferably 0.04 MPa to 0.09 MPa. Under these conditions, the foamed particles can be well fused together.

[0137] If necessary, the recycled pre-expanded styrene resin particles may be aged before molding the recycled styrene resin foam molded product. The aging temperature of the recycled pre-expanded 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 recycled pre-expanded styrene resin particles may dissipate, reducing moldability.

[0138] The foaming ratio of the foamed particles in the recycled styrene-based resin foam molded article is preferably 2 times or more and less than 110 times, more preferably 5 times to 90 times, even more preferably 10 times to 85 times, and particularly preferably 15 times to 80 times.

[0139] The recycled styrene-based resin foam molded articles according to embodiments of the present invention are lightweight and have excellent heat insulation and mechanical strength, making them suitable for use as wall insulation, floor insulation, roof insulation, automobile insulation, hot water tank insulation, pipe insulation, solar system insulation, water heater insulation, containers for food and industrial products (e.g., food containers such as fish boxes, returnable containers), cushioning materials, floats, blocks, packaging materials for fish and agricultural products, molded articles for embankments, core materials for tatami mats, core materials for cushions, aggregates for concrete, and the like. [Examples]

[0140] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement and evaluation methods for each characteristic are as follows.

[0141] <Measurement of trimethylamine emission levels> The amount of trimethylamine emitted from resin particles was measured as follows: Approximately 250 g of the sample was accurately weighed and placed in a 10 L Tedlar bag. The Tedlar bag was then purged with nitrogen (4 L of nitrogen filling) and sealed with a heat seal. After heating at 65°C for 2 hours, 2000 mL of gas from the Tedlar bag was collected at a rate of 200 mL per minute into a solid-phase cartridge (Waters Oasis WCX). The solid-phase cartridge was eluted with 4 mL of 2% acetonitrile formate, and then LC / MS / MS analysis was performed. The LC / MS / MS measurement conditions were as shown below, and the peak area value of trimethylamine detected in the resulting chromatogram was determined. A pre-prepared calibration curve was used for the quantification of trimethylamine. Next, an empty 10L Tedlar bag was purged with nitrogen (4L nitrogen filling), and then heat-sealed. The same measurements were taken and subtracted as an operating blank value. The emission amount per gram of sample was then calculated using the following formula. The detection limit was 1 ng / g. Trimethylamine emission amount (ng / g) = Trimethylamine concentration in test solution (μg / mL) × Extraction volume (mL) ÷ Sample volume (g) × 1000 × Collected gas volume (L) ÷ Gas volume in Tedlar bag (L) (Collection conditions) Sample quantity = approximately 250g Test temperature = 65℃ Heating time=2hr Solid phase cartridge = Waters, Oasis WCX Gas extraction amount = approximately 2000 mL Gas collection rate = 200 mL / min (LC / MS / MS measurement conditions) Measurement device: UHPLC ACCELA (manufactured by Thermo Fisher Scientific) Column: ACQUITY BEH C18 (Waters, inner diameter 2.1 mm, length 50 mm, particle size 1.7 μm) Column temperature: 40℃ Mobile phase conditions: (A: 10 mM ammonium acetate / B: acetonitrile = 15 / 85) Flow rate: 0.3mL / min Pump temperature: Room temperature (25℃) Injection volume: 5μL Measurement time: 5 min (MS measurement conditions) Measurement device: Linear Ion Trap LC / MSn LXQ (manufactured by Thermo Fisher Scientific) Ionization method (ESI / positive) Sheath Gas: 30 arb Auxiliary gas: 5 arb Sweep Gas: 0 arb Spray Voltage: 4.0kV Capillary temperature: 120°C Capillary voltage: 15V Tube lens voltage: 80V Monitor ion: Trimethylamine (m / z=60.1) (Standard solution preparation method) A 1000 ppm intermediate standard solution was prepared by diluting and dissolving a trimethylamine standard in methanol. The intermediate standard solution was further diluted with 2% acetonitrile formate to prepare six standard solutions at concentrations of 5 ppm, 2 ppm, 1 ppm, 0.5 ppm, 0.2 ppm, and 0.1 ppm.

[0142] <Measurement of the concentration of specific metal elements in water> The total concentrations of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in water were measured as follows. If the measurement result was below the detection limit of the measuring instrument, the concentration was considered to be 0. (Measurement method) The concentrations of metallic elements in the collected water were measured under the following conditions. The concentrations of metallic elements were determined from a pre-prepared calibration curve. (ICP measurement conditions) Measurement device: Shimadzu Corporation "ICPE-9000" multi-type ICP emission spectrometer Measured elements = Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, Zn Observation direction = Axis High-frequency output = 1.20kW Carrier flow rate = 0.7 L / min Plasma flow rate = 10.0 L / min Auxiliary flow rate=0.6L / min Exposure time = 30 seconds Calibration standard solutions: SPEX "XSTC-13" general-purpose mixed standard solution, 31 elements (base 5% HN3): approximately 10 mg / L each; "XSTC-8" general-purpose mixed standard solution, 13 elements (base H2O / traceHF): approximately 10 mg / L each.

[0143] <Odor Evaluation> The odor was evaluated using the following method. A sensory evaluation was conducted on the odor of the vapor emitted from a cylindrical batch foaming machine with a volume of 25 liters, after 500 g of recycled foaming styrene resin particles were placed in the machine and heated for 2 minutes. A sensory evaluation was also conducted on the odor of the fracture surface when the molded product was fractured. The sensory evaluation was conducted by five odor assessors. Here, "odor" refers to odors that people generally perceive as unpleasant, such as fishy, ​​putrid, or metallic smells, and was evaluated subjectively. The evaluation criteria were as follows: ○: One or fewer people found it smelly. △: 2-3 people found it smelly. ×: Four people found it to be smelly. XX: Five people (all of them) found it to be smelly.

[0144] <Measurement of bulk density and expansion ratio of recycled pre-expanded styrene resin particles> The bulk density and expansion ratio of recycled pre-expanded styrene resin particles were measured as follows. (Method for measuring bulk density) Recycled pre-expanded styrene resin particles were allowed to fall naturally into a graduated cylinder as a sample. The bottom of the graduated cylinder was then tapped to stabilize the sample volume, and its volume and mass were measured and calculated using the following formula. Bulk density (g / mL) = Sample mass (g) / Sample volume in graduated cylinder (mL) (Method for measuring the expansion ratio) Recycled pre-expanded styrene resin particles were allowed to fall naturally into a graduated cylinder as a sample. The bottom of the graduated cylinder was then tapped to stabilize the sample volume, and its volume and mass were measured and calculated using the following formula. The specific gravity of the resin was assumed to be 1.0 for styrene resins. Expanding ratio (times) = Sample volume in graduated cylinder (mL) / Sample mass (g) × Resin specific gravity The bulk expansion ratio may also be calculated as the reciprocal of the bulk density.

[0145] <Measurement of density and foaming ratio of recycled styrene-based resin foam molded products> (Method for measuring density) The density of the recycled styrene-based foam molded product was calculated using the following formula, after measuring the dimensions and mass of the test specimen to at least three significant figures. Density (g / cm 3 ) = Mass of test specimen (g) / Volume of test specimen (cm³) 3 ) (Method for measuring foaming ratio) The foaming ratio of the recycled styrene-based resin foam molded product was calculated using the following formula, after measuring the dimensions and mass of the test specimen to at least three significant figures. The resin specific gravity was assumed to be 1.0 for styrene-based resins. Expansion ratio (times) = Test specimen volume (cm³) 3 ) / Test specimen mass (g) × Resin specific gravity

[0146] [Manufacturing Example 1]: Manufacturing of recycled styrene-based resin raw material particles (a) Recycled styrene resin raw material particles (a) from used fish boxes were obtained by feeding recovered pellets from used fish boxes (expanded polystyrene) into a short-screw extruder, heating and melting them at 200°C, and then cutting them underwater from the mold to an average particle size of 0.75 mm (approximately spherical). The trimethylamine emission amount of the obtained recycled styrene resin raw material particles (a) was 10 ng / g.

[0147] [Example 1] <Preparation of recycled foamed styrene resin particles (A1)> In a 100-liter reactor with a stirrer, 36 kg of water, 3.5 g of sodium dodecylbenzenesulfonate, and 150 g of magnesium pyrophosphate were added. Then, 12.6 kg of recycled styrene resin raw material particles (a) obtained in Production Example 1 were added, and the mixture was stirred at 150 rpm to suspend it and prepare suspension (1). The water used was prepared by diluting water with a metal element concentration of 105 mg / kg with distilled water (metal element concentration = less than 0.01 mg / kg <below the detection limit>) to adjust the metal element concentration to 101 mg / kg. Separately, 2.3 kg of styrene monomer, in which 125 g of benzoyl peroxide (purity 75%) and 20 g of t-butyl peroxy-2-ethylhexyl monocarbonate were dissolved, was added to a dispersion of 2.5 kg of water (concentration of metal elements = 101 mg / kg) and 0.8 g of sodium dodecylbenzenesulfonate, as polymerization initiators. The mixture was stirred with a homomixer to create an emulsion, and emulsion (1) was prepared. The above suspension (1) in a 100-liter reactor with a stirrer was maintained at 75°C, and the above emulsion (1) was added. Then, the mixture was maintained at 75°C for 30 minutes so that the styrene monomer and polymerization initiator could be well absorbed into the recycled styrene resin raw material particles (a). Immediately after this period, 27.1 kg of styrene monomer was added dropwise over 120 minutes. The addition temperature was gradually increased from 75°C to 105°C. Subsequently, the temperature was raised to 125°C over 30 minutes, held at 125°C for 1 hour, and then cooled to 60°C over 1 hour. This prepared recycled styrene-based resin particles (1) in the reaction vessel. Separately, 147 g of dicumyl peroxide and 35 g of ethylenebisstearate were added to a dispersion of 3.5 kg of water (concentration of metal element = 101 mg / kg), 1.5 g of sodium dodecylbenzenesulfonate, and 20 g of magnesium pyrophosphate, the mixture was stirred with a homomixer to prepare emulsion (2). Emulsion (2) was added to the reactor cooled to 60°C. Ten minutes after this addition, 690 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. Next, the temperature was raised to 100°C, and 3200g of pentane (isopentane / n-pentane = 20% by mass / 80% by mass) was injected under pressure as a blowing agent. This state was maintained for 5 hours to allow the blowing agent to slowly impregnate the material. After that, the temperature inside the reactor was cooled to 30°C. Subsequently, the contents were removed from the reactor, dehydrated, dried, and classified to obtain recycled foamable styrene-based resin particles (A1). When the amount of trimethylamine emitted from the obtained recycled foamed styrene resin particles (A1) was measured, it was below the detection limit (detection limit = 1 ng / g).

[0148] <Surface treatment of recycled foamed styrene resin particles (A1)> 40 kg of the obtained recycled foamed styrene resin particles (A1), along with 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglycerides, and 16 g of fatty acid monoglycerides, were placed in a tumbler mixer and stirred for 30 minutes to perform surface treatment, thereby obtaining surface-treated recycled foamed styrene resin particles (A1').

[0149] <Preparation of recycled pre-expanded styrene resin particles (1)> The surface-treated recycled foamable styrene resin particles (A1') obtained were stored in a refrigerated storage facility at 15°C for 20 days. They were then placed in a cylindrical batch-type pressurized foaming machine with a volume of 340 liters and heated with steam for 2 minutes to obtain recycled pre-foamed styrene resin particles (1). The bulk density of the recycled pre-foamed styrene resin particles (1) was 0.02 g / cm³. 3 The expansion ratio was 50 times. The odor was evaluated separately using the method described above.

[0150] <Preparation of recycled styrene-based foamed molded body (1)> The obtained recycled pre-expanded styrene resin particles (1) were left in a room temperature atmosphere for 24 hours. Then, using a molding machine with a mold having a cavity size of 400 mm in height, 500 mm in width, and 300 mm in depth, the recycled pre-expanded styrene resin particles (1) were filled into the cavity of the mold, heated at a vapor pressure of 0.04 MPa (gauge pressure) for 40 seconds, and then cooled until the internal pressure of the mold was -0.002 MPa. After that, the material was released from the mold to obtain a plate-shaped recycled styrene resin foam molded body (1) corresponding to the mold. The density of the recycled styrene resin foam molded body (1) was 0.02 g / cm³. 3 The foaming ratio was 50 times. Subsequently, this recycled styrene-based resin foam molded product (1) was stored in a drying chamber at 50°C for one day. The obtained recycled styrene-based resin foam molded body (1) was fractured, and its odor was evaluated using the method described above. The results of various evaluations are shown in Table 1.

[0151] [Examples 2-12] Except for using water with a metal element concentration of 105 mg / kg diluted with distilled water (metal element concentration = less than 0.01 mg / kg <below the detection limit>) as the starting water when preparing a suspension containing recycled styrene-based resin raw material particles, the procedure was carried out in the same manner as in Example 1, and recycled styrene-based resin raw material particles (a2) to (a12), recycled foamable styrene-based resin particles (A2) to (A12), recycled pre-foamed styrene-based resin particles (2) to (12), and recycled styrene-based resin foam molded articles (2) to (12) were produced. The results of various evaluations are shown in Table 1.

[0152] [Comparative Example 1] Except for using distilled water (concentration of metal elements = less than 0.01 mg / kg <below the detection limit>) as the water used when preparing the suspension containing recycled styrene-based resin raw material particles, the procedure was carried out in the same manner as in Example 1, and recycled styrene-based resin particles (aC1), recycled foamable styrene-based resin particles (AC1), recycled pre-foamed styrene-based resin particles (C1), and recycled styrene-based resin foam molded articles (C1) were produced. The results of various evaluations are shown in Table 1.

[0153] [Comparative Example 2] Except for using water with a metal element concentration of 105 mg / kg to prepare a suspension containing recycled styrene resin raw material particles, the procedure was carried out in the same manner as in Example 1, and recycled styrene resin raw material particles (aC2), recycled foamable styrene resin particles (AC2), recycled pre-foamed styrene resin particles (C2), and recycled styrene resin foam molded articles (C2) were produced. The odor evaluation revealed that while there was no triethylamine odor, there was a strong metallic odor. The results of various evaluations are shown in Table 1.

[0154] [Example 13] <Preparation of recycled foamed styrene resin particles (A13)> In a 100-liter reactor with a stirrer, 48 kg of water, 5.7 g of sodium dodecylbenzenesulfonate, and 280 g of magnesium pyrophosphate were added. Then, 40 kg of recycled styrene resin raw material particles (a) obtained in Production Example 1 were added, and the mixture was stirred at 150 rpm to suspend it and prepare suspension (3). The water used was water with a metal element concentration of 105 mg / kg, which was diluted with distilled water (metal element concentration = less than 0.01 mg / kg <below the detection limit>) to adjust the metal element concentration to 101 mg / kg. The above suspension (3) in a 100-liter reactor with a stirrer was maintained at 60°C, and 140 g of dicumyl peroxide was added. Ten minutes after this 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. Subsequently, the temperature was raised to 120°C over 60 minutes, and then 4000g of pentane (isopentane / n-pentane = 20% by mass / 80% by mass) was injected under pressure as a blowing agent. The temperature was raised to 108°C over 10 minutes, and then held at that temperature for 5 hours to allow the blowing agent to slowly impregnate the material. After that, the temperature inside the reactor was cooled to 30°C. The contents were then removed from the reactor, dehydrated, dried, and classified to obtain recycled blowable styrene resin particles (A13). When the amount of trimethylamine emitted from the obtained recycled foamed styrene resin particles (A13) was measured, it was below the detection limit (detection limit = 1 ng / g).

[0155] <Surface treatment of recycled foamed styrene resin particles (A13)> 40 kg of the obtained recycled foamed styrene resin particles (A13), along with 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglycerides, and 16 g of fatty acid monoglycerides, were placed in a tumbler mixer and stirred for 30 minutes to perform surface treatment, thereby obtaining surface-treated recycled foamed styrene resin particles (A13').

[0156] <Preparation of recycled pre-expanded styrene resin particles (13)> The surface-treated recycled foamable styrene resin particles (A13') obtained were stored in a refrigerated storage facility at 15°C for 20 days. They were then placed in a cylindrical batch-type pressurized foaming machine with a volume of 340 liters and heated with steam for 2 minutes to obtain recycled pre-foamed styrene resin particles (13). The bulk density of the recycled pre-foamed styrene resin particles (13) was 0.02 g / cm³. 3 The expansion ratio was 50 times. The odor was evaluated separately using the method described above.

[0157] <Preparation of recycled styrene-based foamed molded articles (13)> The obtained recycled pre-expanded styrene resin particles (13) were left in a room temperature atmosphere for 24 hours. Then, using a molding machine with a mold having a cavity size of 400 mm in height, 500 mm in width, and 300 mm in depth, the recycled pre-expanded styrene resin particles (13) were filled into the cavity of the mold, heated at a vapor pressure of 0.04 MPa (gauge pressure) for 40 seconds, and then cooled until the internal pressure of the mold was -0.002 MPa. After that, the material was released from the mold to obtain a plate-shaped recycled styrene resin foam molded body (13) corresponding to the mold. The density of the recycled styrene resin foam molded body (13) was 0.02 g / cm³. 3 The foaming ratio was 50 times. Subsequently, this recycled styrene-based resin foam molded product (13) was stored in a drying chamber at 50°C for one day. The obtained recycled styrene-based resin foam molded body (13) was fractured, and the odor was evaluated using the method described above. The results of various evaluations are shown in Table 2.

[0158] [Examples 14-24] Except for using water with a metal element concentration of 105 mg / kg diluted with distilled water (metal element concentration = less than 0.01 mg / kg <below the detection limit>) as the starting water when preparing a suspension containing recycled styrene-based resin raw material particles, the procedure was carried out in the same manner as in Example 13, and recycled styrene-based resin raw material particles (a14) to (a24), recycled foamable styrene-based resin particles (A14) to (A24), recycled pre-foamed styrene-based resin particles (14) to (24), and recycled styrene-based resin foam molded articles (14) to (24) were produced. The results of various evaluations are shown in Table 2.

[0159] [Comparative Example 3] Except for using distilled water (concentration of metal elements = less than 0.01 mg / kg <below the detection limit>) as the water used when preparing the suspension containing recycled styrene-based resin raw material particles, the procedure was carried out in the same manner as in Example 13, and recycled styrene-based resin particles (aC3), recycled foamable styrene-based resin particles (AC3), recycled pre-foamed styrene-based resin particles (C3), and recycled styrene-based resin foam molded articles (C3) were produced. The results of various evaluations are shown in Table 2.

[0160] [Comparative Example 4] Except for using water with a metal element concentration of 105 mg / kg to prepare a suspension containing recycled styrene-based resin raw material particles, the procedure was carried out in the same manner as in Example 13, and recycled styrene-based resin raw material particles (aC4), recycled foamable styrene-based resin particles (AC4), recycled pre-foamed styrene-based resin particles (C4), and recycled styrene-based resin foam molded articles (C4) were produced. The odor evaluation revealed that while there was no triethylamine odor, there was a strong metallic odor. The results of various evaluations are shown in Table 2.

[0161] [Comparative Example 5] <Preparation of recycled foamed styrene-based resin particles (AC5)> The recovered pellets of used fish boxes (foamed styrene) were supplied to a short-axis extruder, heated and melted at 200 °C, and then 4 parts by mass of pentane (normal pentane / isopentane = 80% by mass / 20% by mass) was press-fitted into 100 parts by mass of the recovered pellets of used fish boxes (foamed styrene), and melt-kneaded and mixed. Next, the resin composition melted in the short-axis extruder was kneaded and cooled, and extruded into a cutting chamber filled with water at 30 °C through a porous die with an extrusion hole of φ0.6 mm × 200 at a resin temperature of 180 °C of the resin composition, immediately cut in water, dehydrated through a stretching dehydrator, and had a bulk density of 0.6 g / cm 3 , and recycled foamed styrene resin particles (AC5) with an average particle diameter of about 1.2 mm were obtained. When the amount of trimethylamine released in the obtained recycled foamed styrene resin particles (AC5) was measured, it was 10 ng / g. The extrusion conditions were as follows. Discharge rate = 180 kg / hour Screw rotation speed = 70 rpm Extruder pressure = 14 MPa Cutter rotation speed = 3000 rpm Water pressure = 0.50 MPa

[0162] <Surface treatment of recycled foamed styrene resin particles (AC5)> 40 kg of the obtained recycled foamed styrene resin particles (AC5), 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglyceride, and 16 g of fatty acid monoglyceride were put into a tumbler mixer, stirred for 30 minutes, and surface-treated to obtain surface-treated recycled foamed styrene resin particles (AC5’).

[0163] <Production of pre-expanded recycled styrene resin particles (C5)> The obtained surface-treated recycled foamed styrene resin particles (AC5’) were stored in a cold storage at 15 °C for 20 days, and then put into a cylindrical batch-type pressure foaming machine with a volume of 340 liters, heated with steam for 2 minutes to obtain pre-expanded recycled styrene resin particles (C5). The bulk density of the pre-expanded recycled styrene resin particles (C5) was 0.02 g / cm 3The expansion ratio was 50 times. The odor was evaluated separately using the method described above. The odor evaluation revealed a strong complex odor, including a triethylamine odor.

[0164] <Preparation of recycled styrene-based foamed molded articles (C5)> The obtained recycled pre-expanded styrene resin particles (C5) were left at room temperature for 24 hours. Then, using a molding machine with a mold having a cavity size of 400 mm in height, 500 mm in width, and 300 mm in depth, the recycled pre-expanded styrene resin particles (C5) were filled into the cavity of the mold, heated at a vapor pressure of 0.04 MPa (gauge pressure) for 40 seconds, and then cooled until the internal pressure of the mold was -0.002 MPa. After that, the material was demolded from the mold to obtain a plate-shaped recycled styrene resin foam molded body (C5) corresponding to the mold. The density of the recycled styrene resin foam molded body (C5) was 0.02 g / cm³. 3 The foaming ratio was 50 times. Subsequently, this recycled styrene-based resin foam molded product (C5) was stored in a drying chamber at 50°C for one day. The obtained recycled styrene-based resin foam molded product (C5) was fractured, and its odor was evaluated using the method described above. The results of various evaluations are shown in Table 3.

[0165] [Table 1]

[0166] [Table 2]

[0167] [Table 3] [Industrial applicability]

[0168] Recycled foamable styrene resin particles obtained by the manufacturing method according to the embodiments of the present invention, recycled pre-foamed styrene resin particles containing the recycled foamable styrene resin particles, and recycled styrene resin foam molded articles containing the recycled pre-foamed styrene resin particles are suitably used as insulation materials for houses and automobiles, heat-insulating materials for building materials, transport packaging materials for 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 foam molded articles according to the embodiments of the present invention are suitably used as insulation materials for walls, floors, roofs, automobiles, hot water tanks, pipes, solar systems, water heaters, containers for food and industrial products (e.g., food containers such as fish boxes, returnable containers), cushioning materials, floats, blocks, packaging materials for fish and agricultural products, embankment materials (embankment blocks, etc.), tatami mat core materials, cushion core materials, concrete aggregates, etc.

Claims

1. A method for producing recycled foamable styrene resin particles with an alkylamine emission amount of less than Yng / g using recycled styrene resin raw material particles (a) having an alkylamine emission amount of Xng / g or more, X ≥ Y, Y ≤ 5, A volatile foaming agent is injected and impregnated into a suspension containing recycled styrene resin raw material particles (a) by adding a styrene monomer and polymerizing it, When preparing the suspension, the water used is one in which the total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in the water is 0.01 mg / kg to 103 mg / kg in terms of concentration. A method for producing recycled foamed styrene-based resin particles.

2. A method for producing recycled foamable styrene resin particles with an alkylamine emission amount of less than Yng / g using recycled styrene resin raw material particles (a) having an alkylamine emission amount of Xng / g or more, X ≥ Y, Y ≤ 5, The recycled styrene-based resin raw material particles (a) are used as recycled styrene-based resin particles (A), and a volatile foaming agent is injected and impregnated into a suspension containing the recycled styrene-based resin particles (A). When preparing the suspension, the water used is one in which the total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in the water is 0.01 mg / kg to 103 mg / kg in terms of concentration. A method for producing recycled foamed styrene-based resin particles.

3. Regenerated foamable styrene-based resin particles obtained by the manufacturing method described in claim 1 or 2, having an alkylamine emission amount of less than 5 ng / g.

4. Regenerated foamable styrene-based resin particles according to claim 3, wherein the alkylamine emission amount is less than 2 ng / g.

5. Recycled pre-foamed styrene resin particles obtained by pre-foaming the recycled foamable styrene resin particles described in claim 3, The bulk expansion ratio of the pre-foaming is 2 to 150 times. Recycled, pre-expanded styrene-based resin particles.

6. A recycled styrene-based resin foam molded article formed from recycled pre-expanded styrene-based resin particles as described in claim 5.

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