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

Abstract

Provided is a method for producing regenerated foamable styrene-based resin particles, which is highly environmentally friendly, and which is used for producing regenerated foamable styrene-based resin particles in which the odor, particularly the odor derived from alkylamine, is suppressed. A method for producing regenerated foamable styrene-based resin particles having an alkylamine release amount of less than Yng / g using regenerated styrene-based resin starting material particles (a) having an alkylamine release amount of Xng / g or more (wherein X > = Y, Y < = 5, Y > = 0), (1) Regenerated styrene resin particles (A) obtained by adding a styrene monomer to a suspension containing the regenerated styrene resin starting material particles (a) and polymerizing the same are pressure-injected and impregnated with a volatile foaming agent, and water having a total concentration of specific metals in a specific range is used as feed water used in the preparation of the suspension, and the total concentration of the specific metals in the feed water is within a specific range. Alternatively, (2) the regenerated styrene-based resin raw material particles (a) are used as regenerated styrene-based resin particles (A), a volatile foaming agent is pressure-injected and impregnated in a suspension containing the regenerated styrene-based resin particles (A), and water in which the total content concentration of specific metals is within a specific range is used as feed water to be used for producing the suspension.

Description

Technical Field

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

[0002] Due to their lightweight nature and excellent thermal insulation and mechanical strength, foam molded articles are widely used as thermal insulation materials used in homes and automobiles, thermal insulation materials used in building materials, fill materials used in expanded polystyrene civil engineering construction, transport packaging materials such as fish boxes and food containers, and cushioning materials. Among them, in-mold foam molded articles made from expandable particles (typically expandable styrene resin particles or pre-expanded styrene resin particles obtained by pre-expanding them) are widely used due to their advantages such as ease of obtaining the desired shape. Such foam molded articles are composed of multiple expandable particles welded together.

[0003] On the other hand, the amount of plastic waste is increasing year by year. Most of the plastic waste is disposed of by incineration and landfill, which will cause major social problems such as environmental pollution, global warming, and a shortage of landfill treatment plants. Therefore, the recycling of plastic waste has become a strong demand of society. With the implementation of the "Home Appliance Recycling Law", various discussions on the recycling of plastic waste are underway. Against the background of various recycling methods being proposed, from the perspective of resource circulation and reducing environmental load, material recycling (material recycling) of plastic waste as plastic parts for products has attracted much attention. At the same time, the recycling of materials such as styrene resin foam moldings is also being explored and studied.

[0004] As a material recycling method for styrene resin foam molded articles, several recycled foamable styrene resin particles have been proposed. These recycled foamable styrene resin particles are obtained by melting and extruding recycled raw materials to form recycled particles, and then impregnating the particles with a foaming agent.

[0005] For example, methods have been reported for obtaining recycled foamable styrene resin particles by impregnating recycled resin particles formed from recycled styrene resin foam molded products with a blowing agent or by press-injecting and then impregnating the particles (Patent Documents 1 to 4). Furthermore, methods have been reported for obtaining recycled foamable styrene resin particles by adding styrene monomer to recycled resin particles formed from recycled styrene resin foam molded products, polymerizing the particles, and then impregnating the particles with a blowing agent or by press-injecting and then impregnating the particles (Patent Documents 5 to 8).

[0006] However, conventional recycled expandable styrene resin particles, particularly those produced without recycled raw materials, have a problem of emitting a unique odor characteristic of recycled materials. Furthermore, the resulting recycled pre-expanded styrene resin particles and recycled styrene resin foamed molded articles also emit a perceptible odor characteristic of recycled materials. In particular, recycled expandable styrene resin particles produced using fish boxes as recycled raw materials have a problem of emitting a unique rancid odor characteristic of tertiary alkylamines derived from fish, etc. Prior art literature Patent Literature

[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 Application Laid-Open No. 2006-160905 Patent Document 7: Patent No. 4912567 Patent Document 8: Patent No. 5128246 Summary of the Invention Problems to be solved by the invention

[0008] The present invention was developed to address the aforementioned existing problems. Its primary objective is to provide a method for producing recycled expandable styrene resin particles with high environmental benefits. This method is used to produce recycled expandable styrene resin particles in which odor, particularly odor derived from alkylamines, is suppressed. The present invention also provides recycled expandable styrene resin particles obtained by such a production method, in which odor, particularly odor derived from alkylamines, is suppressed. Furthermore, the present invention provides recycled pre-expanded styrene resin particles obtained from such recycled expandable styrene resin particles, and recycled styrene resin foam moldings formed from such recycled pre-expanded styrene resin particles. Technical means to solve the problem

[0009] [1] According to one embodiment of the present invention, a method for producing regenerated expandable styrene resin particles is a method for producing regenerated expandable styrene resin particles having an alkylamine release of less than Yng / g using regenerated styrene resin raw material particles (a) having an alkylamine release of Xng / g or more, wherein X≥Y, 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) to polymerize the styrene monomer. As feed water used in preparing the suspension, water having a total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn of 0.01 mg / kg to 103 mg / kg is used as feed water. [2] According to another embodiment of the present invention, a method for producing recycled expandable styrene resin particles is a method for producing recycled expandable styrene resin particles having an alkylamine release of less than Yng / g using recycled styrene resin raw material particles (a) having an alkylamine release of Xng / g or more, wherein X≥Y, Y≤5, 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 water is used as feed water for preparing the suspension, and the total content concentration of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in the feed water is 0.01 mg / kg to 103 mg / kg. [3] The regenerated expandable styrene resin particles according to an embodiment of the present invention are regenerated expandable styrene resin particles having an alkylamine release amount of less than 5 ng / g, which are obtained by the production method described in [1] or [2] above. [4] In the regenerated expandable styrene resin particles described in [3] above, the amount of alkylamine released may be less than 2 ng / g. [5] The regenerated pre-foamed styrene resin particles according to an embodiment of the present invention are regenerated pre-foamed styrene resin particles obtained by pre-foaming the regenerated foamable styrene resin particles described in [3] or [4] above, wherein the volume expansion ratio of the pre-foaming is 2 to 150 times. [6] A recycled styrene resin foam molded article according to an embodiment of the present invention is molded from the recycled pre-foamed styrene resin particles described in [5] above. Effects of the Invention

[0010] According to an embodiment of the present invention, a method for producing recycled expandable styrene resin particles with high environmental benefits can be provided. This method is used to produce recycled expandable styrene resin particles in which odor, particularly odor derived from alkylamines, is suppressed. Furthermore, recycled expandable styrene resin particles obtained by such a production method and in which odor, particularly odor derived from alkylamines, is suppressed can be provided. Furthermore, recycled pre-expanded styrene resin particles obtained from such recycled expandable styrene resin particles, as well as recycled styrene resin foamed molded articles formed from such recycled pre-expanded styrene resin particles, can be provided. DETAILED DESCRIPTION

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

[0012] In the present specification, “(meth)acrylic acid” refers to acrylic acid and / or methacrylic acid, and “(meth)acrylate” refers to acrylate and / or methacrylate.

[0013] A. Method for producing regenerated expandable styrene resin particles According to an embodiment of the present invention, a method for producing recycled expandable styrene resin particles is a method for producing recycled expandable styrene resin particles having an alkylamine release amount of less than Yng / g using recycled styrene resin raw material particles (a) having an alkylamine release amount of Xng / g or more, wherein X≥Y and Y≤5.

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

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

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

[0017] The relationship between X and Y is X≥Y. From the viewpoint of further exhibiting the effects of the present invention, X>Y is preferred, XY>1 is more preferred, XY>3 is further preferred, XY>5 is further preferred, XY>7 is particularly preferred, and XY>10 is most preferred.

[0018] Y ≤ 5. From the perspective of further demonstrating the effects of the present invention, Y < 5 is preferred, Y < 4 is more preferred, Y < 3 is even more preferred, Y < 2 is particularly preferred, and Y < 1 is most preferred. Regarding the lower limit of Y, the smaller the alkylamine release from the regenerated expandable styrene resin particles obtained by the production method according to an embodiment of the present invention, the better.

[0019] Alkylamines are amines having an alkyl group, and examples include primary amines, secondary amines, and tertiary amines. Specific examples include methylamine as a primary amine, dimethylamine as a secondary amine, and trimethylamine and triethylamine as a tertiary amine. Trimethylamine, which is known for its fishy odor, is an example of an alkylamine that further enhances the effects of the present invention.

[0020] As preferred embodiments of the method for producing regenerated expandable styrene resin particles of the present invention, the following two embodiments can be cited: Embodiment (1): Regenerated styrene resin particles (A) obtained by adding a styrene monomer to a suspension containing recycled styrene resin raw material particles (a) and polymerizing the resulting particles are injected and impregnated with a volatile foaming agent, wherein water containing 0.01 mg / kg to 103 mg / kg of a metal element is used as feed water for preparing the suspension; Embodiment (2): Recycled styrene resin raw material particles (a) are used as recycled styrene resin particles (A), and a volatile foaming agent is injected and impregnated into a suspension containing the recycled styrene resin particles (A). Water containing 0.01 mg / kg to 103 mg / kg of metal elements is used as the feed water used to prepare the suspension.

[0021] A-1. Preferred embodiment of the method for producing regenerated expandable styrene resin particles (1) In a preferred embodiment (1) of the method for producing regenerated foamable styrene resin particles, a volatile foaming agent is injected and impregnated into regenerated styrene resin particles (A) obtained by adding a styrene monomer to a suspension containing regenerated styrene resin raw material particles (a) and polymerizing them, and water containing 0.01 mg / kg to 103 mg / kg of a metal element is used as the feed water used when preparing the suspension.

[0022] <A-1-1. Regenerated styrene resin particles (A) in embodiment (1)> In the embodiment (1), the regenerated styrene-based resin particles (A) are obtained by adding a styrene-based monomer to a suspension containing regenerated styrene-based resin raw material particles (a) and polymerizing the mixture.

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

[0024] The recycled styrene resin raw material particles (a) may be any suitable recycled styrene resin, provided that the effects of the present invention are not impaired. Examples of such recycled styrene resins include recycled plastic materials used in expanded polystyrene (e.g., molded products, block-shaped products), foamed sheet materials (e.g., pallets, sheet scraps), household appliances, packaging containers, and cushioning particles. The present invention is particularly effective in recycling styrene resin foam moldings that have a strong alkylamine odor, such as fish boxes.

[0025] The recycled styrene resin raw material particles (a) may contain any appropriate recycled resin other than the recycled styrene resin, within the scope of not impairing the effects of the present invention. Examples of such other recycled resins include the following: 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). The other resins may be one or more. In this specification, the recycled AS resin, recycled ABS resin, and recycled HIPS (high impact polystyrene) are not included in the scope of the recycled styrene resin.

[0026] As the recycled styrene-based resin raw material particles (a), molded products produced by Sekisui Chemicals Co., Ltd. under the trade names of "EPSREM" or "ESLEN Beads RNW" can be used.

[0027] The recycled styrene resin raw material particles (a) may be obtained by pulverizing recycled resin (ingots, etc.) obtained by heating and / or reducing the volume of waste expanded styrene resin (e.g., fish boxes). The recycled styrene resin raw material particles (a) may be pellets formed by extrusion molding the pulverized material, or may be pellets obtained by further pulverizing the pellets. Alternatively, the recycled styrene resin raw material particles may be recovered by volume reduction using a solvent such as limonene.

[0028] The recycled styrene resin raw material particles (a) are preferably obtained by melt extrusion. The melt extrusion method typically involves feeding crushed waste styrene resin, ingots, foamed particles, etc., to a resin supply device, melting the resin within the resin supply device, extruding the resin from a small orifice in a die attached to the front end of the resin supply device, and then cooling the resin to obtain pellets.

[0029] The particles obtained by the above-mentioned melt extrusion method are preferably at least one selected from the following particles: extruded strand particles obtained by extruding waste expanded styrene resin (fish boxes, mixtures of fish boxes and other waste expanded styrene resins, mixtures of fish boxes and other waste expanded styrene resins, etc.) through an extruder and cutting the strands, underwater cut particles obtained by extruding waste expanded styrene resin through an extruder and cutting it underwater by an underwater cutting method, and hot-cut particles obtained by cutting waste expanded styrene resin particles immediately after extruding them from the extruder die head by a hot cutting method and cooling them.

[0030] The recycled styrene resin raw material particles (a) may be directly obtained by the melt extrusion method described above to obtain pellets. Alternatively, in order to obtain pellets of smaller size, the pellets may be further melt extruded to obtain so-called "micro pellets."

[0031] The recycled styrene resin raw material particles (a) may be shrinkage products or melts of foamed styrene resins, which are obtained by coarsely crushing waste foamed styrene resins into appropriate sizes as needed, and then subjecting them to thermal shrinkage, compression-based bubble destruction shrinkage, frictional heat-based shrinkage, melting, etc.

[0032] Examples of the waste foamed styrene resin include molded articles obtained by molding a foamable styrene resin and articles obtained by heat-foaming the resin.

[0033] The recycled styrene resin raw material particles (a) may contain finely powdered inorganic substances and / or organic lubricants, which are generally used as bubble regulators.

[0034] Examples of fine powder inorganic substances include talc, calcium carbonate, and silicon dioxide. Talc generally refers to a mixture containing silicon oxide and magnesium oxide as main components and trace amounts of aluminum oxide, iron oxide, and the like.

[0035] The average particle size of the fine inorganic powder is preferably 100 μm or less, more preferably 30 μm or less. If the average particle size of the fine inorganic powder exceeds 100 μm, the effect of reducing the cell size of the regenerated pre-expanded styrene resin particles may be reduced.

[0036] The content of the fine powder inorganic material relative to the recycled styrene resin raw material particles (a) is preferably 0.1% to 5% by mass, and more preferably 0.5% to 2% by mass. If the content of the fine powder inorganic material relative to the recycled styrene 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 resin particles may be reduced. If the content of the fine powder inorganic material relative to the recycled styrene resin raw material particles (a) exceeds 5% 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 may be deteriorated.

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

[0038] The content of the organic lubricant relative to the recycled styrene resin raw material particles (a) is preferably 0.01% to 2.0% by mass, more preferably 0.02% to 1.8% by mass, and depending on the circumstances, further preferably 0.02% to 0.2% by mass, and particularly preferably 0.02% to 0.1% by mass. 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 cell size of the recycled pre-expanded styrene resin particles may be reduced. If the content of the organic lubricant relative to the recycled styrene resin raw material particles (a) exceeds 2.0% by mass, the cell size of the recycled pre-expanded styrene resin particles becomes extremely small, the recycled pre-expanded styrene resin particles melt during molding, and the appearance of the molded product tends to deteriorate.

[0039] As the specific method containing micronized inorganic matter and / or organic lubricant in recycled styrene resin raw material particle (a), the method for mixing micronized inorganic matter and / or organic lubricant during extrusion molding can be enumerated.At this moment, preferably carry out extrusion molding after premixing crushed material and bubble regulator.Within the scope of not damaging the effect of the present invention, the mixing method of crushed material and bubble regulator can be carried out by any appropriate method.As this type of method, the mixing method of the mixers such as rotary drum, ribbon mixer, V-type mixer, Henschel mixer, Roediger mixer can be enumerated.

[0040] The recycled styrene resin raw material particles (a) are preferably hot-melted for the purpose of adjusting the specific gravity. In this process, the specific gravity of the recycled styrene resin raw material particles (a) is preferably adjusted to 0.6 or more, more preferably adjusted to 0.9 or more. When the specific gravity of the recycled styrene resin raw material particles (a) is less than 0.6, the dispersion of the recycled styrene resin raw material particles (a) is unstable, so that excessively large particles may be produced in the subsequent polymerization process, reducing the yield rate. Within the scope of not damaging the effect of the present invention, the hot melting of the recycled styrene resin raw material particles (a) can be carried out by any appropriate method. As such methods, for example, methods using an extruder or a hot roller can be cited. Hot melting is preferably carried out in a state where there is no residual strain in the obtained resin or the strain is small, and cooling and solidification is carried out. When strain remains in the resin particles, the strain will be relieved in the subsequent process, shrinking in the stretching direction, and the obtained recycled foamable styrene resin particles may not become spherical but become flat. Therefore, as hot melting, it is preferred to use an extruder for non-stretching melting. If hot melting is carried out in a stretched state, it is possible that residual strain will remain in the stretched resin obtained by cooling and solidification. Even if strain remains in the resin due to heat melting, the strain can be relieved by aging the resin for a certain period of time at a temperature equal to or higher than the softening point of the resin.

[0041] The pulverization of the regenerated styrene resin raw material particles (a) can be carried out using any pulverizer as long as the effects of the present invention are not impaired. Examples of such pulverizers include pulverizers for plastics, preferably pulverizers for polystyrene.

[0042] The recycled styrene-based resin raw material particles (a) may be sieved as needed and melted again by passing through an extruder or the like.

[0043] The average particle size of the recycled styrene resin raw material particles (a) is preferably 0.2 mm to 3.0 mm, more preferably 0.3 mm to 2.5 mm, further preferably 0.4 mm to 2.0 mm, and particularly preferably 0.5 mm to 1.7 mm. If the average particle size of the recycled styrene resin raw material particles (a) exceeds 3 mm, the resulting recycled foamable styrene resin particles may have difficulty in becoming spherical. If the average particle size of the recycled styrene resin raw material particles (a) is less than 0.2 mm, the average particle size of the resulting recycled foamable styrene resin particles may be too small.

[0044] The ratio L (long side) / D (short side) of the recycled styrene resin raw material particles (a) is preferably 1.0 to 6.0, more preferably 1.0 to 5.0, 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 ratio L (long side) / D (short side) of the recycled styrene resin raw material particles (a) is outside the above range, the resulting recycled expandable styrene resin particles may have difficulty in achieving a spherical shape.

[0045] The recycled styrene resin raw material particles (a) preferably contain particles having an average particle size of 200 μm or less in an amount of less than 1% by mass. Using recycled styrene resin raw material particles (a) containing particles having an average particle size of 200 μm or less in an amount of 1% by mass or more may deteriorate the appearance of the resulting recycled expandable styrene resin particles.

[0046] The weight average molecular weight of the recycled styrene resin raw material particles (a) is preferably 100,000 to 510,000, more preferably 150,000 to 490,000. If the weight average molecular weight of the recycled styrene resin raw material particles (a) is less than 100,000, sufficient strength may not be obtained. If the weight average molecular weight of the recycled styrene resin raw material particles (a) exceeds 510,000, the recycled styrene resin raw material particles may have difficulty in forming a spherical shape, or the foaming properties may be reduced, resulting in a poor appearance of the molded article.

[0047] The styrene-based monomer may be used alone or in combination of two or more.

[0048] Styrene monomers include styrene or styrene derivatives. Examples of styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, and bromostyrene. The styrene monomer may be one or more. The styrene monomer preferably contains at least styrene. The content of styrene relative to the total amount of the styrene monomer is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0049] In the range that does not impair the effect of the present invention, the styrene monomer may contain any appropriate vinyl monomer other than the styrene monomer. For example, a multifunctional monomer, a (meth)acrylate monomer, a maleate monomer, and a fumarate monomer may be mentioned. Such vinyl monomers may be only one kind or two or more kinds.

[0050] Specific examples of the multifunctional monomer include 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 the (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and hexyl (meth)acrylate. Maleate monomers include dimethyl maleate. Fumarate monomers include dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

[0051] Relative to the total amount of the recycled styrene resin raw material particles (a) and the styrene monomer, the content ratio of the recycled styrene resin raw material particles (a) is preferably 10% to 90% by mass, more preferably 15% to 85% by mass, further preferably 20% to 80% by mass, particularly preferably 23% to 80% by mass, and most preferably 25% to 80% by mass. When the above-mentioned content ratio is lower than the above-mentioned range, it is possible to reduce environmental benefits. In addition, when the above-mentioned content ratio is lower or higher than the above-mentioned range, the recycled foamable styrene resin particles according to the embodiment of the present invention may not exhibit good spheroidization, and may have reduced moldability.

[0052] The regenerated styrene resin particles (A) are obtained by adding a styrene monomer to a suspension containing regenerated styrene resin raw material particles (a) and polymerizing the mixture. Any appropriate method can be used as such a polymerization method without compromising the effects of the present invention. As a preferred embodiment of such a polymerization method, the following method can be cited: to a suspension obtained by dispersing the regenerated styrene resin raw material particles (a) as cores in water, an emulsion containing a polymerization initiator and a styrene monomer is added, the suspension is immersed in the regenerated styrene resin raw material particles (a), and then the styrene monomer is added for polymerization.

[0053] In the present invention, the feed water used to prepare the suspension containing the recycled styrene resin raw material particles (a) is preferably water having a total content of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn of 0.01 mg / kg to 103 mg / kg. By using water containing the metal elements at these specific concentrations as the feed water for preparing the suspension, recycled expandable styrene resin particles can be obtained in which odor, particularly odor derived from alkylamine, is suppressed.

[0054] From the viewpoint of being able to further reflect the effect of the present invention, the above-mentioned concentration in the above-mentioned feeding water is preferably 0.01 mg / kg to 100 mg / kg, more preferably 0.01 mg / kg to 95 mg / kg, further preferably 0.01 mg / kg to 90 mg / kg, further 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.

[0055] If the concentration in the feed water is below the above range, the effects of the present invention may not be achieved, and in particular, the odor from the alkylamine may become stronger. If the concentration in the feed water is above the above range, the effects of the present invention may not be achieved, and in particular, the metallic odor may become stronger.

[0056] When obtaining recycled styrene resin particles (A), from the viewpoint of further exhibiting the effects of the present invention, the temperature for adding the styrene monomer to the recycled styrene resin raw material particles (a) is preferably 40° C. to 119° C., preferably 40° C. to 118° C., more preferably 40° C. to 117° C., further preferably 50° C. to 117° C., and particularly preferably 60° C. to 115° C. When the temperature for adding the styrene monomer to the recycled styrene resin raw material particles (a) is adjusted within the above range, the recycled styrene resin raw material particles (a) can absorb the styrene monomer while maintaining an appropriate hardness, thereby achieving good spheroidization of the recycled styrene resin particles (A), and the resulting recycled expandable styrene resin particles can exhibit good spheroidization and excellent moldability. If the temperature for adding the styrene monomer to the recycled styrene resin raw material particles (a) is lower than the above range, the recycled styrene resin raw material particles (a) become too hard. When absorbing the styrene monomer in this state, the recycled styrene resin particles (A) become difficult to spheroidize, and the resulting recycled foamable styrene resin particles may be difficult to spheroidize or have poor moldability. If the temperature for adding the styrene monomer to the recycled styrene resin raw material particles (a) is higher than the above range, the recycled styrene resin raw material particles (a) become too soft. When absorbing the styrene monomer in this state, the recycled styrene resin particles (A) become difficult to spheroidize, and the resulting recycled foamable styrene resin particles may be difficult to spheroidize or have poor moldability. The "temperature for adding the styrene monomer to the recycled styrene resin raw material particles (a)" refers to the temperature for adding the emulsion containing the polymerization initiator and the styrene monomer and the subsequent addition of the styrene monomer.

[0057] When the regenerated styrene resin raw material particles (a) are dispersed in an aqueous medium as a core to obtain a suspension, any suitable method can be used as the method for dispersing the regenerated styrene resin raw material particles (a) in an aqueous medium, without damaging the effects of the present invention. As such a method for dispersion, it is preferred to use a device having a stirring wing for dispersion. As a method for more finely dispersing, a method using a homomixer can be enumerated.

[0058] When the regenerated styrene resin raw material particles (a) are dispersed in an aqueous medium to obtain a suspension, a dispersant is preferably used in the dispersion of the regenerated styrene resin raw material particles (a) into the aqueous medium. As long as the dispersant can be used for suspension polymerization, any appropriate dispersant can be used without damaging the effects of the present invention. Examples of such dispersants include organic dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone, and methylcellulose; and sparingly soluble inorganic salts such as magnesium pyrophosphate and tricalcium phosphate. Among them, magnesium pyrophosphate is preferred as a dispersant from the viewpoint of being able to further embody the effects of the present invention.

[0059] The dispersant is added in an amount of preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.1 to 1.0 parts by mass, relative to 100 parts by mass of the regenerated styrene-based resin particles (A).

[0060] When the regenerated styrene resin raw material particles (a) are dispersed in an aqueous medium as a core to obtain a suspension, a surfactant is preferably used in the dispersion of the regenerated styrene resin raw material particles (a) into the aqueous medium. As long as the surfactant can be used for suspension polymerization, any appropriate surfactant can be used without damaging the effect of the present invention. As such a surfactant, for example, sodium dodecylbenzene sulfonate, sodium alkane sulfonate, sodium alkyl sulfonate, sodium alkyl diphenyl ether disulfonate and sodium α-olefin sulfonate can be enumerated. Wherein, from the viewpoint of being able to further embody the effect of the present invention, as a surfactant, sodium dodecylbenzene sulfonate is preferred.

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

[0062] As the emulsification method when obtaining an emulsion containing a polymerization initiator and a styrene monomer, any appropriate method can be adopted within the scope of not damaging the effect of the present invention. As such a dispersed method, it is preferred to use a device equipped with a stirring wing for dispersion. As a more finely dispersed method, a method using a homogenizer can be cited. At this time, it is preferred to disperse until the oil droplet diameter of the dispersion liquid dispersed with the styrene monomer becomes below the particle size of the core. This is because, when added to an aqueous medium under a state where the oil droplet diameter is greater than the core particle size, a plurality of regenerated styrene resin raw material particles (a) are wrapped in the oil droplets of the dispersion liquid dispersed with the styrene monomer, resulting in adhesion, plasticization, and agglomeration of the regenerated styrene resin raw material particles (a), making it easy to produce oversized particles.

[0063] As the polymerization initiator used to obtain the emulsion containing the polymerization initiator and the styrene monomer, any appropriate polymerization initiator can be used, as long as it is suitable for the suspension polymerization method and does not impair the effects of the present invention. Examples of such polymerization initiators include organic peroxides such as benzoyl peroxide, tert-butyl peroxy-2-ethylhexyl carbonate, and tert-butyl perbenzoate; and azo compounds such as azobisisobutyronitrile. The polymerization initiator may be a single species or two or more species.

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

[0065] The polymerization initiator is preferably dissolved in the styrene monomer or a solvent before addition. Examples of the solvent include aromatic hydrocarbons such as ethylbenzene and toluene; and aliphatic hydrocarbons such as heptane and octane. When a solvent is used, it is generally used in an amount of 10% by mass or less relative to the styrene monomer.

[0066] In the suspension containing the regenerated styrene resin raw material particles (a), an emulsion containing a styrene monomer is added and impregnated, and as a method for adding the styrene monomer, any appropriate method can be adopted without prejudice to the effect of the present invention. As such methods, for example, addition in portions and continuous addition can be cited. The addition rate can be appropriately selected according to the capacity, shape, polymerization temperature, etc. of the polymerization unit.

[0067] After adding an emulsion containing a styrene-based monomer to a suspension containing recycled styrene-based resin raw material particles (a) to allow the particles to be immersed, the styrene-based monomer is added and the polymerization reaction is continued at any appropriate temperature and time as required.

[0068] The suspension containing the recycled styrene resin raw material particles (a) or the emulsion containing the styrene monomer may contain a bubble regulator. Examples of such bubble regulators include fatty acid monoamides such as oleamide, stearamide, and hydroxystearamide; and fatty acid bisamides such as methylenebisstearamide and ethylenebisstearamide.

[0069] <A-1-2. Pressure injection and impregnation of blowing agent in embodiment (1)> In embodiment (1), the regenerated expandable styrene resin particles are obtained by impregnating the regenerated styrene resin particles (A) with a blowing agent by injection.

[0070] A representative method of injection and impregnation of the blowing agent in embodiment (1) is a method of placing the regenerated styrene resin particles (A) in a reactor such as an autoclave and injecting and impregnating the blowing agent therein.

[0071] The dispersant is added in an amount of preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.1 to 1.0 parts by mass, relative to 100 parts by mass of the regenerated styrene-based resin particles (A).

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

[0073] As a foaming agent, any appropriate foaming agent can be used within the scope that does not impair the effect of the present invention. As a foaming agent, an organic compound having a boiling point below the softening point of the styrene resin and being gaseous or liquid at normal pressure is preferred. As specific examples, there can be mentioned: aliphatic hydrocarbons such as propane, n-butane, isobutane, pentane (n-pentane, isopentane, neopentane), and n-hexane; alicyclic hydrocarbons such as cyclopentane and cyclopentadiene; ketones such as acetone and methyl ethyl ketone; alcohols such as methanol, ethanol, and isopropanol; 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, etc. As a foaming agent, inorganic gases such as carbon dioxide, nitrogen, and ammonia can also be used. Among them, from the viewpoint of further exhibiting the effects of the present invention, 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.

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

[0075] The injection temperature of the foaming agent into the regenerated styrene resin particles (A) may be any appropriate temperature as long as the effects of the present invention are not impaired. Such an injection temperature is preferably 50°C to 150°C, particularly preferably 55°C to 140°C.

[0076] The temperature for impregnating the regenerated styrene resin particles (A) with the blowing agent may be any appropriate temperature within a range not impairing the effects of the present invention. Such an impregnation temperature is preferably 50°C to 150°C, particularly preferably 55°C to 140°C.

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

[0078] Any appropriate time may be used for the impregnation time of the foaming agent into the regenerated styrene-based resin particles (A) as long as the effects of the present invention are not impaired. Such an impregnation time is preferably 1 to 10 hours.

[0079] <A-1-3. Other components in embodiment (1)> In embodiment (1), the regenerated expandable styrene resin particles may contain any appropriate other components within a range not impairing the effects of the present invention. Such other components may be one or more.

[0080] The regenerated expandable styrene resin particles may contain a flame retardant as another component in order to improve flame retardancy. The flame retardant may be one type or two or more types.

[0081] As the flame retardant, any appropriate flame retardant can be used within the scope that does not impair the effects of the present invention. As such flame retardants, bromine compounds compatible with polystyrene are preferred, and examples thereof include tetrabromoethane, tetrabromocyclooctane, hexabromocyclododecane, hexabromocyclohexane, tris(dibromopropyl)phosphate, tetrabromobisphenol A, tetrabromobisphenol F, tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tetrabromobisphenol A-diglycidyl ether, 2,2-bis[4'(2",3"-dibromoalkoxy)-3',5'-dibromophenyl]-propane, tris(tribromophenoxy)triazine, 2,2-bis(4-allyloxy-3,5-dibromo)propane, and hexabromobenzene.

[0082] When a flame retardant is used, a flame retardant auxiliary agent may be used in combination. Examples of the flame retardant auxiliary agent include cumene hydroperoxide, dicumyl peroxide, tert-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and 3,4-dimethyl-3,4-diphenylhexane.

[0083] The total amount of the flame retardant and the flame retardant auxiliary used may be any appropriate amount within the range that does not impair the effects of the present invention. Such an amount is preferably 0.1% to 5% by mass, more preferably 0.2% to 3% by mass, relative to the regenerated styrene resin particles (A).

[0084] The flame retardant may be added at any appropriate time, provided that the effects of the present invention are not impaired. To further enhance the effects of the present invention, it is preferably added before the injection of the volatile blowing agent. By adding the flame retardant before the injection of the volatile blowing agent, the flame retardant can be added at a low temperature, equivalent to the injection temperature of the volatile blowing agent, resulting in the regenerated expandable styrene resin particles exhibiting good spheroidization and excellent moldability.

[0085] From the viewpoint of further demonstrating the effects of the present invention, the temperature for adding the flame retardant is preferably 5°C to 120°C, more preferably 5°C to 118°C, further preferably 5°C to 115°C, particularly preferably 5°C to 113°C, and most preferably 5°C to 110°C.

[0086] In embodiment (1), a bubble regulator may also be used when manufacturing the regenerated foamable styrene resin particles. The bubble regulator may be only one or more. Examples of bubble 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 methylene bisstearamide and ethylene bisstearamide. Examples of higher fatty acids in the partial esters of higher fatty acids and alcohols include fatty acids having 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 glyceryl monostearate and glyceryl distearate.

[0087] The amount of the cell control agent used is preferably 0 to 5.0 parts by mass, more preferably 0.03 to 3.0 parts by mass, relative to 100 parts by mass of the recycled styrene resin raw material (A). The cell control agent can be added by, for example, adding it together with the foaming agent, or by conventional methods such as dry blending, masterbatch method, and melt injection method.

[0088] In embodiment (1), a foaming aid may be used when producing the regenerated foamable styrene resin particles. That is, in embodiment (1), the regenerated foamable styrene resin particles may also contain a foaming aid. The foaming aid may be only one type or two or more types. Examples of the foaming aid include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, and coconut oil.

[0089] In embodiment (1), a bubble regulator may also be used when producing the regenerated expandable styrene resin particles. That is, in embodiment (1), the regenerated expandable styrene resin particles may also contain a bubble regulator. The bubble regulator may be only one type or two or more types. Examples of the bubble regulator include fatty acid monoamides such as oleamide, stearamide, and hydroxystearamide; and fatty acid bisamides such as methylene bisstearamide and ethylene bisstearamide.

[0090] In embodiment (1), the regenerated expandable styrene resin particles may contain a cell control agent such as talc, calcium carbonate, mica, citric acid, sodium bicarbonate, etc. The cell control agent may be one or more.

[0091] Examples of other components include pigments, radiant heat transfer inhibitors, crosslinking agents, plasticizers, stabilizers, fillers, lubricants, colorants, antistatic agents, spreading agents, weathering agents, anti-aging agents, anti-fogging agents, and fragrances.

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

[0093] In embodiment (1), when silicone oil is used to surface-treat the recycled expandable styrene resin particles, the amount of silicone oil used is preferably 0.001 to 0.3 parts by mass, more preferably 0.003 to 0.28 parts by mass, more preferably 0.005 to 0.25 parts by mass, particularly preferably 0.008 to 0.23 parts by mass, and most preferably 0.01 to 0.23 parts by mass. When the amount of silicone oil used is below the above range, for example, when an antistatic agent is used, the affinity with the antistatic agent during pre-foaming becomes insufficient, and static electricity may be easily generated. When the amount of silicone oil used is above the above range, the surface may lose its surface properties due to melting during molding.

[0094] The silicone oil may be used alone or in combination of two or more.

[0095] As the silicone oil, any appropriate silicone oil can be used within the scope that does not impair the effects of the present invention. In order to further demonstrate the effects of the present invention, the silicone oil includes common silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane, with methylphenylpolysiloxane being preferred.

[0096] In embodiment (1), when the surface of the recycled foamable styrene resin particles is treated with an antistatic agent, the amount of the antistatic agent used is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, 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, relative to 100 parts by mass of the recycled foamable styrene resin particles before the surface treatment. If the amount of the antistatic agent is below the above range, static electricity may be easily generated during pre-foaming. If the amount of the antistatic agent is above the above range, the surface of the recycled pre-foamed styrene resin particles or the recycled styrene resin foamed molded article may become sticky.

[0097] The antistatic agent may be used alone or in combination of two or more.

[0098] As the antistatic agent, any appropriate antistatic agent can be used within the scope of not damaging the effect of the present invention. From the perspective of being able to further exert the effect of the present invention, the antistatic agent can include at least one selected from nonionic surfactants and fatty acid glycerides, preferably a combination of nonionic surfactants and fatty acid glycerides.

[0099] The nonionic surfactant may be used alone or in combination of two or more.

[0100] As the nonionic surfactant, any appropriate nonionic surfactant can be used within the scope of not damaging the effects of the present invention. From the viewpoint of being able to further exert the effects of the present invention, as the nonionic surfactant, for example, polyethylene glycol, glycerol, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyvalent alcohol, 1-amino-2-hydroxy compound can be mentioned. As the polyoxyethylene alkyl ether, specifically, for example, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether can be mentioned. As the polyoxyethylene alkyl ester, specifically, for example, polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, polyoxyethylene oleate can be mentioned. As the polyol, specifically, for example, glycerol, propylene glycol can be mentioned. Specific examples of the 1-amino-2-hydroxy compound include N-hydroxyethyl-N-(2-hydroxyalkyl)amine, N,N-bis(hydroxyethyl)dodecylamine, N,N-bis(hydroxyethyl)tetradecylamine, N,N-bis(hydroxyethyl)hexadecylamine, N,N-bis(hydroxyethyl)octadecylamine, N-hydroxyethyl-N-(2-hydroxytetradecyl)amine, N-hydroxyethyl-N-(2-hydroxyhexadecyl)amine, N-hydroxyethyl-N-(2-hydroxyoctadecyl)amine, N-hydroxypropyl N-(2-hydroxytetradecyl)amine, N-hydroxybutyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxyhexadecyl)amine, N-hydroxypentyl-N-(2-hydroxyoctadecyl)amine, N,N-bis(2-hydroxyethyl)dodecylamine, N,N-bis(2-hydroxyethyl)tetradecylamine, N,N-bis(2-hydroxyethyl)hexadecylamine, N,N-bis(2-hydroxyethyl)octadecylamine, and salts thereof. From the viewpoint of further exhibiting the effects of the present invention, polyethylene glycol is preferred as the nonionic surfactant.

[0101] When a nonionic surfactant is used as at least part of the antistatic agent, the amount of the nonionic surfactant used is preferably 0.001 to 2.0 parts by mass, more preferably 0.001 to 1.5 parts by mass, further preferably 0.001 to 1.0 parts by mass, 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, relative to 100 parts by mass of the recycled foamable styrene resin particles before surface treatment. If the amount of the nonionic surfactant is below the above range, static electricity may be easily generated during pre-foaming. If the amount of the nonionic surfactant is above the above range, the surface of the recycled pre-foamed styrene resin particles or the recycled styrene resin foamed molded article may become sticky.

[0102] The fatty acid glycerides may be used alone or in combination of two or more.

[0103] As the fatty acid glyceride, any appropriate fatty acid glyceride can be used within the scope that does not impair the effects of the present invention. From the viewpoint of further embodying the effects of the present invention, specific examples of the fatty acid glyceride include stearic acid monoglyceride and linoleic acid monoglyceride. From the viewpoint of further embodying the effects of the present invention, stearic acid monoglyceride is preferred as the fatty acid glyceride.

[0104] When a fatty acid glyceride is used as at least a portion of the antistatic agent, the amount of the fatty acid glyceride relative to 100 parts by mass of the recycled foamable styrene resin particles before 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 the fatty acid glyceride is below the above range, static electricity may be easily generated during pre-foaming. If the amount of the fatty acid glyceride is above the above range, the surface of the recycled pre-foamed styrene resin particles or the recycled styrene resin foam molded article may become sticky.

[0105] In embodiment (1), when the surface treatment of the regenerated expandable styrene resin particles is performed using a fatty acid metal salt, the amount of the fatty acid metal salt used is preferably 0.005 to 0.5 parts by mass, more preferably 0.007 to 0.45 parts by mass, more preferably 0.01 to 0.4 parts by mass, particularly preferably 0.015 to 0.35 parts by mass, and most preferably 0.02 to 0.3 parts by mass, relative to 100 parts by mass of the regenerated expandable styrene resin particles before the surface treatment. If the amount of the fatty acid metal salt is less than the above range, a large amount of agglomeration occurs during pre-foaming, and a good styrene resin foam molded product may not be obtained. If the amount of the fatty acid metal salt is greater than the above range, a large amount of metal salt is present during pre-foaming, which easily causes charging and static electricity, and may deteriorate the welding of the molded product.

[0106] The fatty acid metal salt may be used alone or in combination of two or more.

[0107] As the fatty acid metal salt, any appropriate fatty acid metal salt can be adopted within the scope of not damaging the effect of the present invention. From the viewpoint of being able to further embody the effect of the present invention, as the fatty acid metal salt, for example, stearic acid metal salts and lauric acid metal salts can be mentioned. As the stearic acid metal salt, for example, magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate can be mentioned. As the lauric acid metal salt, for example, zinc laurate and barium laurate can be mentioned specifically. From the viewpoint of being able to further embody the effect of the present invention, as the fatty acid metal salt, magnesium stearate and zinc stearate are preferred.

[0108] In embodiment (1), when the recycled foamable styrene resin particles are surface-treated with a melting accelerator, the amount of the melting accelerator used is preferably 0.01 to 0.8 parts by mass, more preferably 0.01 to 0.7 parts by mass, 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 the melting accelerator is less than the above range, the melting properties during molding may be reduced, and a good recycled styrene resin foam molded product may not be obtained. If the amount of the melting accelerator is greater than the above range, agglomeration may occur during pre-foaming.

[0109] The welding accelerator may be used alone or in combination of two or more.

[0110] As a welding accelerator, any appropriate welding accelerator can be used within the scope of not damaging the effects of the present invention. From the viewpoint of being able to further reflect the effects of the present invention, as a fusion accelerator, for example, fatty acid triglycerides, fatty acid diglycerides, fatty acid monoglycerides, and vegetable oils can be mentioned. As fatty acid triglycerides, specifically, for example, lauric acid triglyceride, stearic acid triglyceride, linoleic acid triglyceride, and hydroxystearic acid triglyceride can be mentioned. As fatty acid diglycerides, specifically, for example, lauric acid diglyceride, stearic acid diglyceride, and linoleic acid diglyceride can be mentioned. As fatty acid monoglyceride, specifically, for example, lauric acid monoglyceride can be mentioned. As vegetable oil, specifically, for example, hydrogenated castor oil can be mentioned. From the viewpoint of being able to further reflect the effects of the present invention, as a welding accelerator, stearic acid triglyceride and hydroxystearic acid triglyceride are preferred.

[0111] A-2. Preferred embodiment of the method for producing regenerated expandable styrene resin particles (2) In a preferred embodiment (2) of the method for producing regenerated foamable styrene resin particles, regenerated styrene resin raw material particles (a) are used as regenerated styrene resin particles (A), a volatile foaming agent is injected and impregnated into a suspension containing the regenerated styrene resin particles (A), and water containing 0.01 mg / kg to 103 mg / kg of a metal element is used as feed water for preparing the suspension.

[0112] <A-2-1. Regenerated styrene resin particles (A) in embodiment (2)> In embodiment (2), the recycled styrene resin particles (A) are directly recycled styrene resin raw material particles (a). The description of the recycled styrene resin raw material particles (a) in the above-mentioned <A-1-1. Recycled styrene resin particles (A) in embodiment (1)> can be cited.

[0113] <A-2-2. Injection and impregnation of volatile blowing agent in embodiment (2)> In embodiment (2), the regenerated expandable styrene resin particles are obtained by injecting and impregnating a volatile foaming agent into a suspension containing regenerated styrene resin particles (A) directly using regenerated styrene resin raw material particles (a).

[0114] As a method for injection and impregnation of a volatile foaming agent in embodiment (2), the following method can be representatively cited: in a reactor such as an autoclave, a volatile foaming agent is injected and impregnated into a suspension containing recycled styrene resin particles (A) (recycled styrene resin raw material particles (a) are directly used).

[0115] Regarding the injection and impregnation method, the description in the above-mentioned section <A-1-2. Injection and impregnation of volatile blowing agent in embodiment (1)> can be cited.

[0116] Referring to the description in the section <A-1-2. Injection and impregnation of volatile blowing agent in embodiment (1)>, in embodiment (2), it is preferred that water containing a total concentration of 0.01 mg / kg to 103 mg / kg of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn be used as the feed water for preparing a suspension containing recycled styrene resin particles (A) (using recycled styrene resin raw material particles (a) as they are). By using water containing the metal elements at the above-specified concentrations as the feed water for preparing the suspension, recycled expandable styrene resin particles can be obtained in which odor, particularly odor derived from alkylamine, is suppressed.

[0117] From the viewpoint of further embodying the effects of the present invention, the above-mentioned concentration in the above-mentioned feeding water is preferably 0.01 mg / kg to 100 mg / kg, more preferably 0.01 mg / kg to 95 mg / kg, further preferably 0.01 mg / kg to 90 mg / kg, further 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.

[0118] If the concentration in the feed water is below the above range, the effects of the present invention may be difficult to achieve, and in particular, the odor from the alkylamine may become stronger. If the concentration of the metal element in the feed water is above the above range, the effects of the present invention may be difficult to achieve, and in particular, the metallic odor may become stronger.

[0119] <A-2-3. Other components in embodiment (2)> In embodiment (2), the regenerated expandable styrene resin particles may contain any appropriate other components, provided that the effects of the present invention are not impaired. Such other components may be one or more. Regarding the other components, the description of the other components in the above-mentioned section <A-1-3. Other components in embodiment (1)> can be cited.

[0120] <A-2-4. Surface treatment> In embodiment (2), the regenerated expandable styrene resin particles may be subjected to surface treatment. Regarding the surface treatment, the description in the above section <A-1-4. Surface treatment> can be cited.

[0121] B. Recycled Expandable Styrene Resin Particles The regenerated expandable styrene resin particles according to the embodiment of the present invention are obtained by the method for producing regenerated expandable styrene resin particles according to the embodiment of the present invention.

[0122] The regenerated expandable styrene resin particles according to an embodiment of the present invention are obtained by the method for producing regenerated expandable styrene resin particles according to an embodiment of the present invention. Therefore, odor, particularly odor derived from alkylamines, is effectively suppressed. The alkylamine emission level is preferably less than 5 ng / g, more preferably less than 4 ng / g, even 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 level, the better, and preferably 0 ng / g.

[0123] The recycled expandable styrene resin particles according to an embodiment of the present invention have a particle shape as a whole. The average particle size of the recycled expandable styrene resin particles is preferably 0.40 mm to 2.0 mm, more preferably 0.6 mm to 1.8 mm. The average particle size can be measured according to JIS Z 8815. Specifically, the average particle size is a value measured by a particle size distribution based on a sieve test according to JIS Z 8815, with the particle size at the cumulative value of 50%.

[0124] As the shape of the regenerated foamable styrene resin particles according to an embodiment of the present invention, in the scope of not damaging the effect of the present invention, any appropriate shape can be adopted. As the concrete example of this shape, for example spherical, roughly spherical, ellipsoidal spherical (oval) etc. can be enumerated. As the shape of the regenerated foamable styrene resin particles according to an embodiment of the present invention, from the viewpoint of embodying the effect of the present invention, preferably spherical, roughly spherical, more preferably spherical. But, in reality, be difficult to distinguish spherical and roughly spherical, therefore in this manual, both are combined as spherical.

[0125] The weight average molecular weight of the regenerated expandable styrene resin particles according to the embodiment of the present invention may be any appropriate weight average molecular weight as long as the effects of the present invention are not impaired. Such a weight average molecular weight is preferably 100,000 to 510,000, more preferably 110,000 to 490,000, further preferably 120,000 to 470,000, and particularly preferably 130,000 to 460,000.

[0126] C. Recycled Pre-expanded Styrene Resin Particles The regenerated pre-expanded styrene-based resin particles according to an embodiment of the present invention are obtained by pre-expanding the regenerated expandable styrene-based resin particles according to an embodiment of the present invention.

[0127] Since the regenerated pre-expanded styrene resin particles according to the embodiment of the present invention are obtained by pre-expanding the regenerated expandable styrene resin particles according to the embodiment of the present invention, odor, particularly odor derived from alkylamine, can be effectively suppressed.

[0128] The average cell diameter of the recycled pre-expanded styrene resin particles is preferably 0.01 mm to 0.80 mm, more preferably 0.01 mm to 0.70 mm, further preferably 0.01 mm to 0.60 mm, particularly preferably 0.01 mm to 0.50 mm, and most preferably 0.01 mm to 0.40 mm. If the average cell diameter of the recycled pre-expanded styrene resin particles is within the above range, it can further prevent agglomeration during foaming or molding, further suppress charging during foaming and molding, and simultaneously exhibit better weldability or surface properties, resulting in recycled pre-expanded styrene resin particles that can be molded into a recycled styrene resin foam molded article with less static electricity. If the average cell diameter of the recycled pre-expanded styrene resin particles is less than 0.01 mm, the surface may melt and shrink during molding.

[0129] Pre-foaming includes using water vapor or the like to foam the regenerated foamable styrene resin particles at a desired volume expansion ratio (volume density). The volume expansion ratio of the regenerated pre-foamed styrene resin particles is preferably 2 to 150 times, more preferably 2 times or more and less than 100 times, more preferably 5 to 90 times, further preferably 10 to 85 times, and particularly preferably 15 to 83 times. The volume density is the reciprocal of the volume expansion ratio. By making the volume expansion ratio of the regenerated pre-foamed styrene resin particles within the above range, it is possible to provide a regenerated pre-foamed styrene resin particle that can further prevent agglomeration during foaming or molding, and further, can further suppress the charge during foaming and molding, while exhibiting better weldability or surface properties, and can mold regenerated pre-foamed styrene resin foam moldings with less static electricity.

[0130] In a representative embodiment, the regenerated pre-foamed styrene resin particles can be used to form a regenerated styrene resin foam molding. In another embodiment, the regenerated pre-foamed styrene resin particles can be directly used as a cushioning material, a thermal insulation material, a concrete aggregate, etc. When the regenerated pre-foamed styrene resin particles are used directly, the regenerated pre-foamed styrene resin particles are preferably used as a filler for filling a plurality of regenerated pre-foamed styrene resin particles in a bag. Such regenerated pre-foamed styrene resin particles are suitable, for example, for the core material of a cushion (foamed particles filled inside the cushion).

[0131] D. Recycled Styrene Resin Foam Molding The recycled styrene resin foam molded article according to an embodiment of the present invention is molded from recycled pre-expanded styrene resin particles according to an embodiment of the present invention. The recycled styrene resin foam molded article according to an embodiment of the present invention is molded from recycled pre-expanded styrene resin particles according to an embodiment of the present invention, and thus odors, particularly odors derived from alkylamines, can be effectively suppressed.

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

[0133] The recycled styrene resin foam molded article typically contains recycled foamed styrene resin particles (hereinafter, sometimes simply referred to as “foamed particles”) obtained by further foaming recycled pre-foamed styrene resin particles.

[0134] The recycled styrene-based resin foam molded article is typically composed of a plurality of foamed particles fused to each other.

[0135] Recycled styrene resin foam moldings can be typically produced by loading recycled pre-foamed styrene resin particles into a mold having a predetermined shape corresponding to the purpose and performing in-mold foam molding. In more detail, in-mold foam molding includes: (i) filling recycled pre-foamed styrene resin particles into a closed mold having a plurality of small holes; (ii) using a heat medium (such as pressurized steam, etc.) to heat and foam the recycled pre-foamed styrene resin particles to obtain foamed particles; (iii) filling the gaps between the foamed particles through the heating and foaming, and integrating the foamed particles by fusing them to each other. The density of the recycled styrene resin foam molding can be appropriately set according to the purpose. The density of the recycled styrene resin foam molding can be adjusted, for example, by pre-adjusting the volume expansion ratio of the pre-foamed styrene resin particles filled into the mold or by adjusting the filling amount of the recycled pre-foamed styrene resin particles filled into the mold.

[0136] The temperature for heating and foaming (substantially the temperature of the heat medium) is preferably 90°C to 150°C, more preferably 110°C to 130°C. The heating and foaming time is preferably 5 seconds to 50 seconds, more preferably 10 seconds to 50 seconds. The molding vapor pressure (the blown gauge pressure of the heat medium) for heating and foaming is preferably 0.04 MPa to 0.1 MPa, more preferably 0.04 MPa to 0.09 MPa. If the heating and foaming are carried out under these conditions, the expanded particles can be well fused together.

[0137] If necessary, the regenerated pre-expanded styrene resin particles may be aged before forming the regenerated styrene resin foam molded article. The aging temperature for the regenerated 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 blowing agent in the regenerated pre-expanded styrene resin particles may dissipate, thereby reducing moldability.

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

[0139] The recycled styrene resin foam molding according to the embodiment of the present invention is lightweight and has excellent thermal insulation and mechanical strength. Therefore, it can be used in wall insulation materials, floor insulation materials, roof insulation materials, automobile insulation materials, hot water storage tank insulation materials, pipe insulation materials, solar energy system insulation materials, water heater insulation materials, containers for food and industrial products (for example, food containers such as fish boxes, turnover boxes), cushioning materials, floating bodies, building blocks, packaging materials for fish and agricultural products, molded bodies for fill, tatami core materials, cushion core materials, concrete aggregates, etc. Example

[0140] The present invention will be described in detail below by way of examples, but the present invention is not limited thereto. The measurement and evaluation methods of the various properties are as follows.

[0141] <Measurement of trimethylamine release> The release of trimethylamine in the resin particles is measured as follows. About 250g of the measurement sample is accurately weighed in a 10L Tedler bag, and the Tedler bag is purged with nitrogen (nitrogen filling volume 4L) and sealed by heat sealing. Then, after heating at 65°C for 2 hours, 2000mL of gas in the Tedler bag is collected at 200mL per minute in a solid phase column (Waters, Oasis WCX). The solid phase column is eluted with 4mL of 2% formic acid acetonitrile and then measured by LC / MS / MS. In addition, the LC / MS / MS measurement conditions are as follows, and the peak area value of trimethylamine detected by the obtained chromatogram is obtained. The quantification of trimethylamine uses a pre-made standard curve. Next, the empty 10L Tedler bag is purged with nitrogen (nitrogen filling volume 4L), sealed by heat sealing, and then measured in the same way. After deducting the operating blank value, the release amount per gram of sample is calculated according to the following formula. In addition, the lower limit of measurement was 1 ng / g. Trimethylamine release (ng / g) = Trimethylamine concentration in test solution (μg / mL) × extract volume (mL) ÷ sample volume (g) × 1000 × collected gas volume (L) ÷ gas volume in Tedler bag (L) (Collection conditions) Sample size = about 250g Test temperature = 65°C Heating time = 2 hours Solid phase column = Waters, Oasis WCX Gas collection volume = about 2000mL Gas collection rate = 200 mL / min (LC / MS / MS measurement conditions) Measuring equipment: UHPLC ACCELA (manufactured by Thermo Fisher Scientific) Column: ACQUITY BEH C18 (manufactured by Waters, inner diameter 2.1 mm, length 50 mm, particle size 1.7 μm) Column temperature: 40°C Mobile phase conditions: (A: 10 mM ammonium acetate / B: acetonitrile = 15 / 85) Flow rate: 0.3mL / min Pump temperature: room temperature (25℃) Injection volume: 5 μL Measurement time: 5 minutes (MS measurement conditions) Measuring equipment: Linear Ion Trap LC / MSn LXQ (manufactured by Thermo Fisher Scientific) Ionization method: (ESI / positive) Sheath Gas: 30arb Auxiliary gas (AUX Gas): 5arb Sweep Gas: 0arb 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) Prepare a 1000 ppm intermediate standard solution by diluting the trimethylamine standard with methanol. Then, dilute the intermediate standard solution with 2% formic acid in acetonitrile to prepare six standard solutions 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 concentration of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn contained in water was measured as follows. If the measured result was less than the quantitative limit of the measuring device, the concentration was set to 0. (Measurement method) The concentrations of metal elements in the collected water were measured under the following conditions. The concentrations of metal elements were calculated using a pre-created calibration curve. (ICP measurement conditions) Measuring device: ICPE-9000 multi-type ICP emission spectrometer manufactured by Shimadzu Corporation Measured elements: Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, Zn View direction = axis direction 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 Standard solutions for calibration curve: SPEX, USA, "XSTC-13" universal mixed standard solution, 31 elements mixed (base 5% HN3): approximately 10 mg / L each; "XSTC-8" universal mixed standard solution, 13 elements mixed (matrix H2O / trace HF): approximately 10 mg / L each

[0143] Odor evaluation Odor evaluation was performed as follows. 500 g of regenerated expandable styrene resin particles were placed in a 25-liter cylindrical batch foaming machine and heated for 2 minutes. The odor of the steam discharged from the foaming machine was sensory tested. The odor of the fractured surface of the molded article was also sensory tested. The sensory test was conducted by five odor control panelists, who evaluated odors that are generally perceived as fishy, ​​putrid, and metallic. The evaluation criteria are as follows. ○: One or fewer people noticed the odor. △: 2 to 3 people noticed the smell. ×: Four people felt the odor. XX: There are 5 people (all members) who feel the stench.

[0144] <Measurement of Bulk Density and Volume Expansion Ratio of Recycled Pre-Expanded Styrene Resin Particles> The bulk density and volume expansion ratio of the recycled pre-expanded styrene-based resin particles are measured as follows. (Measurement method of bulk density) After the recycled pre-expanded styrene resin particles as a sample naturally fall into the measuring cylinder, knock the bottom of the measuring cylinder to make the sample volume constant, measure its volume and mass, and calculate according to the following formula: Bulk density (g / mL) = sample mass (g) / sample volume in the graduated cylinder (mL) (Measurement method of volume expansion ratio) After the recycled pre-expanded styrene resin particles as a sample naturally fall into the measuring cylinder, the bottom of the measuring cylinder is knocked to make the sample volume constant, and its volume and mass are measured and calculated according to the following formula: The resin specific gravity is set to 1.0 in the case of styrene resin. Volume expansion ratio (times) = sample volume in the measuring cylinder (mL) / sample mass (g) × resin specific gravity In addition, the volume expansion ratio can also be calculated as the inverse of the bulk density.

[0145] <Measurement of density and expansion ratio of recycled styrene resin foam moldings> (Density measurement method) The density of recycled styrene resin foam moldings must be calculated by measuring the size and mass of the test piece with an accuracy of more than three significant figures and using the following formula: Density (g / cm 3 ) = mass of test piece (g) / volume of test piece (cm 3 ) (Measurement method of foaming ratio) The expansion ratio of recycled styrene resin foam moldings must be calculated using the following formula by measuring the dimensions and mass of the test piece with an accuracy of at least three significant figures. For styrene resins, the resin specific gravity is assumed to be 1.0. Foaming ratio (times) = volume of test piece (cm 3 ) / test piece mass (g)×resin specific gravity

[0146] [Production Example 1]: Production of Recycled Styrene Resin Raw Material Particles (a) Recycled pellets from waste fish boxes (expanded styrene) were fed into a short-shaft extruder, heated and dissolved at 200°C, and then cut underwater from a die to an average particle size of 0.75 mm (approximately spherical). These recycled styrene resin raw material particles (a) for fish boxes were obtained. The trimethylamine emission of the resulting recycled styrene resin raw material particles (a) was 10 ng / g.

[0147] [Example 1] <Production of Regenerated Expandable Styrene Resin Particles (A1)> In a 100-liter reactor equipped with a stirrer, 36 kg of water, 3.5 g of sodium dodecylbenzenesulfonate, and 150 g of magnesium pyrophosphate were added, and further, 12.6 kg of the recycled styrene resin raw material particles (a) obtained in Production Example 1 were added and stirred at 150 rpm to suspend the mixture to prepare a suspension (1). The water used was water having 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 lower limit of measurement>) 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%) as a polymerization initiator and 20 g of tert-butyl peroxy-2-ethylhexyl carbonate were dissolved were added to 2.5 kg of the above-mentioned dispersion of the same water quality (metal element concentration = 101 mg / kg) and 0.8 g of sodium dodecylbenzenesulfonate, and the mixture was stirred and emulsified with a homogenizer to prepare an emulsion (1). The suspension (1) in a 100-liter reactor equipped with a stirrer was maintained at 75°C, and the emulsion (1) was added. The temperature was then maintained at 75°C for 30 minutes to allow the styrene monomer and polymerization initiator to be fully absorbed into the recycled styrene resin raw material particles (a). Immediately after this maintenance, 27.1 kg of styrene monomer was continuously added dropwise over 120 minutes. The addition temperature was gradually increased from 75°C to 105°C. Then, the temperature was raised to 125° C. over 30 minutes, maintained at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour. Thus, regenerated styrene-based resin particles (1) were obtained in the reaction container. Separately, 147 g of dicumyl peroxide and 35 g of ethylene bisstearamide were added to 3.5 kg of a dispersion of the same water (metal element concentration = 101 mg / kg), 1.5 g of sodium dodecylbenzenesulfonate, and 20 g of magnesium pyrophosphate. The mixture was stirred and emulsified using a homomixer to prepare an emulsion (2). This emulsion (2) was added to the reactor cooled to 60°C. After 10 minutes of this addition, 690 g of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) was added. After this addition, stirring was continued at 60°C for 30 minutes. Next, the temperature was raised to 100°C, 3200 g of pentane (isopentane / n-pentane = 20% by mass / 80% by mass) as a blowing agent was injected, and this state was maintained for 5 hours to allow the blowing agent to gradually permeate. The temperature inside the reactor was then cooled to 30°C. Next, the contents were taken out from the reactor, dehydrated, dried, and classified to obtain regenerated expandable styrene resin particles (A1). The amount of trimethylamine released from the obtained regenerated expandable styrene resin particles (A1) was measured and found to be below the lower limit of measurement (lower limit of measurement = 1 ng / g).

[0148] <Surface treatment of regenerated foamable styrene resin particles (A1)> 40 kg of the obtained regenerated expandable styrene resin particles (A1), 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglyceride, and 16 g of fatty acid monoglyceride were placed in a drum mixer and stirred for 30 minutes for surface treatment to obtain surface-treated regenerated expandable styrene resin particles (A1').

[0149] <Production of Recycled Pre-Expanded Styrene Resin Particles (1)> The surface-treated regenerated foamable styrene resin particles (A1') were stored in a cold storage at 15°C for 20 days, and then placed in a 340-liter cylindrical batch-type pressurized foaming machine and heated with steam for 2 minutes to obtain regenerated pre-foamed styrene resin particles (1). The bulk density of the regenerated pre-foamed styrene resin particles (1) was 0.02 g / cm 3 , the volume foaming ratio is 50 times. In addition, odor evaluation was performed separately by the above-mentioned method.

[0150] <Production of recycled styrene resin foamed molded article (1)> After the obtained regenerated pre-foamed styrene resin particles (1) were placed at room temperature for 24 hours, a molding machine having a molding die with a cavity size of 400 mm in height, 500 mm in width, and 300 mm in depth was used to fill the mold cavity with the above-mentioned regenerated pre-foamed styrene resin particles (1), and heated at a steam pressure of 0.04 MPa (gauge pressure) for 40 seconds. Then, after cooling to a pressure in the molding die of -0.002 MPa, the mold was demolded from the molding die to obtain a plate-shaped regenerated styrene resin foamed molded body (1) corresponding to the molding die. The density of the regenerated styrene resin foamed molded body (1) was 0.02 g / cm 3 The expansion ratio was 50. Then, the regenerated styrene resin foamed molded product (1) was stored in a drying room at 50° C. for 1 day. The obtained regenerated styrene-based resin foamed molded product (1) was broken and subjected to odor evaluation by the above-mentioned method. The various evaluation results are shown in Table 1.

[0151] [Examples 2 to 12] Except that water having a metal element concentration of 105 mg / kg was diluted with distilled water (metal element concentration = less than 0.01 mg / kg <below the lower limit of measurement>) and the metal element concentration was adjusted to the concentration shown in Table 1 as the feed water used for preparing the suspension containing recycled styrene resin raw material particles, the remaining operations were carried out in the same manner as in Example 1 to prepare recycled styrene resin raw material particles (a2) to (a12), recycled foamable styrene resin particles (A2) to (A12), recycled pre-foamed styrene resin particles (2) to (12), and recycled styrene resin foam moldings (2) to (12). The various evaluation results are shown in Table 1.

[0152] [Comparative Example 1] Except for using distilled water (metal element concentration = less than 0.01 mg / kg <below the lower limit of measurement>) as the feed water for preparing the suspension containing recycled styrene resin raw material particles, the remaining operations were carried out in the same manner as in Example 1 to produce recycled styrene resin particles (aC1), recycled foamable styrene resin particles (AC1), recycled pre-foamed styrene resin particles (C1), and recycled styrene resin foam moldings (C1). The various evaluation results are shown in Table 1.

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

[0154] [Example 13] <Production of Regenerated Expandable Styrene Resin Particles (A13)> In a 100-liter reactor equipped with a stirrer, 48 kg of water, 5.7 g of sodium dodecylbenzenesulfonate, and 280 g of magnesium pyrophosphate were added, and 40 kg of the recycled styrene resin raw material particles (a) obtained in Production Example 1 were added and stirred at 150 rpm to suspend the particles to prepare a suspension (3). The water used was water having a metal element concentration of 105 mg / kg diluted with distilled water (metal element concentration = less than 0.01 mg / kg <below the lower limit of measurement>) to adjust the metal element concentration to 101 mg / kg. The suspension (3) in a 100-liter reactor equipped with a stirrer was maintained at 60°C, and 140 g of dicumyl peroxide was added. Ten minutes after the addition, 660 g of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) was added. After the addition, stirring was continued at 60°C for 30 minutes. The temperature was then raised to 120°C over 60 minutes. Then, 4000 g of pentane (isopentane / n-pentane = 20% by mass / 80% by mass) as a blowing agent was injected. After reaching 108°C over 10 minutes, the temperature was maintained at that level for 5 hours to allow the blowing agent to gradually permeate. The temperature inside the reactor was then cooled to 30°C. The contents were then removed from the reactor, dehydrated, dried, and classified to obtain regenerated expandable styrene resin particles (A13). The amount of trimethylamine released from the obtained regenerated expandable styrene resin particles (A13) was measured and found to be below the lower limit of measurement (lower limit of measurement = 1 ng / g).

[0155] <Surface treatment of regenerated foamable styrene resin particles (A13)> 40 kg of the obtained regenerated expandable styrene resin particles (A13), 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglyceride, and 16 g of fatty acid monoglyceride were placed in a drum mixer and stirred for 30 minutes for surface treatment to obtain surface-treated regenerated expandable styrene resin particles (A13').

[0156] <Production of Recycled Pre-foamed Styrene Resin Particles (13)> The surface-treated regenerated foamable styrene resin particles (A13') were stored in a cold storage at 15°C for 20 days, and then placed in a 340-liter cylindrical batch-type pressurized foaming machine and heated with steam for 2 minutes to obtain regenerated pre-foamed styrene resin particles (13). The bulk density of the regenerated pre-foamed styrene resin particles (13) was 0.02 g / cm 3 , the volume foaming ratio is 50 times. In addition, odor evaluation was performed separately by the above-mentioned method.

[0157] <Production of recycled styrene resin foam molding (13)> After the obtained regenerated pre-foamed styrene resin particles (13) were placed at room temperature for 24 hours, a molding machine having a molding die with a cavity size of 400 mm in height, 500 mm in width, and 300 mm in depth was used to fill the mold cavity with the above-mentioned regenerated pre-foamed styrene resin particles (13). The mold cavity was heated at a steam pressure of 0.04 MPa (gauge pressure) for 40 seconds. After cooling to a pressure in the molding die of -0.002 MPa, the mold was demolded from the molding die to obtain a plate-shaped regenerated styrene resin foamed molded body (13) corresponding to the molding die. The density of the regenerated styrene resin foamed molded body (13) was 0.02 g / cm 3 The expansion ratio was 50. The regenerated styrene resin foamed molded body (13) was then stored in a drying room at 50°C for 1 day. The obtained regenerated styrene resin foamed molded product (13) was broken and subjected to odor evaluation by the above-mentioned method. The various evaluation results are shown in Table 2.

[0158] [Examples 14 to 24] Except that water having a metal element concentration of 105 mg / kg was diluted with distilled water (metal element concentration = less than 0.01 mg / kg <below the lower limit of measurement>) and the metal element concentration was adjusted to the concentration shown in Table 1 as the feed water used for preparing the suspension containing recycled styrene resin raw material particles, the remaining operations were carried out in the same manner as in Example 13 to prepare recycled styrene resin raw material particles (a14) to (a24), recycled foamable styrene resin particles (A14) to (A24), recycled pre-foamed styrene resin particles (14) to (24), and recycled styrene resin foam moldings (14) to (24). The various evaluation results 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 lower limit of measurement>) as the feed water for preparing the suspension containing recycled styrene resin raw material particles, the remaining operations were carried out in the same manner as Example 13 to obtain recycled styrene resin particles (aC3), recycled foamable styrene resin particles (AC3), recycled pre-foamed styrene resin particles (C3), and recycled styrene resin foam moldings (C3). The various evaluation results are shown in Table 2.

[0160] [Comparative Example 4] Except for using water with a metal element concentration of 105 mg / kg as the water for preparing the suspension containing recycled styrene resin raw material particles, the remaining operations were carried out in the same manner as Example 13 to obtain recycled styrene resin raw material particles (aC4), recycled foamable styrene resin particles (AC4), recycled pre-foamed styrene resin particles (C4), and recycled styrene resin foamed moldings (C4). The odor evaluation results showed that the odor was strong in metallic odor, although there was no triethylamine odor. The various evaluation results are shown in Table 2.

[0161] [Comparative Example 5] <Production of Recycled Expandable Styrene Resin Particles (AC5)> The recycled pellets of waste fish box (expanded styrene) were fed into a short-spindle extruder and heated at 200°C to dissolve them. Then, 4 parts by mass of pentane (n-pentane / isopentane = 80% by mass / 20% by mass) was injected into 100 parts by mass of the recycled pellets of waste fish box (expanded styrene) and melt-kneaded for mixing. Next, the resin composition melted in the short-spindle extruder was kneaded and cooled. The resin composition was passed through a sieve having a resin temperature of 180°C. The product was extruded into a cutting chamber filled with 30°C water through a porous die head with 10 extrusion holes, cut immediately in water, and dehydrated by a stretching dehydrator to obtain a bulk density of 0.6 g / cm 3 , recycled foamable styrene resin particles (AC5) with an average particle size of about 1.2 mm. The trimethylamine release amount in the obtained regenerated expandable styrene resin particles (AC5) was measured and found to be 10 ng / g. The extrusion conditions were as follows. Discharge rate = 180kg / hour Screw speed = 70 rpm Extruder pressure = 14 MPa Tool speed = 3000 rpm Water pressure = 0.50 MPa

[0162] Surface treatment of recycled foamable styrene resin particles (AC5) 40 kg of the obtained recycled expandable 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 placed in a drum mixer and stirred for 30 minutes for surface treatment to obtain surface-treated recycled expandable styrene resin particles (AC5').

[0163] <Production of Recycled Pre-Expanded Styrene Resin Particles (C5)> The surface-treated regenerated foamable styrene resin particles (AC5') were stored in a cold storage at 15°C for 20 days and then placed in a 340-liter cylindrical batch-type pressurized foaming machine and heated with steam for 2 minutes to obtain regenerated pre-foamed styrene resin particles (C5). The bulk density of the regenerated pre-foamed styrene resin particles (C5) was 0.02 g / cm 3 , the volume foaming ratio is 50 times. In addition, odor evaluation was performed separately by the above-mentioned method. The odor evaluation results showed that the compound odor containing triethylamine was stronger.

[0164] <Production of recycled styrene resin foam molding (C5)> After the obtained regenerated pre-foamed styrene resin particles (C5) were placed at room temperature for 24 hours, a molding machine having a molding die with a cavity size of 400 mm in height, 500 mm in width, and 300 mm in depth was used to fill the mold cavity with the above-mentioned regenerated pre-foamed styrene resin particles (C5). The mold cavity was heated at a steam pressure of 0.04 MPa (gauge pressure) for 40 seconds. After cooling to a pressure in the molding die of -0.002 MPa, the mold was demolded from the molding die to obtain a plate-shaped regenerated styrene resin foamed molded body (C5) corresponding to the molding die. The density of the regenerated styrene resin foamed molded body (C5) was 0.02 g / cm 3 The expansion ratio was 50. Then, the regenerated styrene-based resin foamed molded product (C5) was stored in a drying room at 50° C. for 1 day. The obtained regenerated styrene-based resin foamed molded product (C5) was subjected to a fracture treatment and odor evaluation was performed by the above-mentioned method. The various evaluation results are shown in Table 3.

[0165]

Table 1

[0166]

Table 2

[0167]

Table 3

[0168] The recycled expandable styrene resin particles, recycled pre-expanded styrene resin particles containing the recycled expandable styrene resin particles, and recycled styrene resin foam molded articles containing the recycled pre-expanded styrene resin particles obtained by the production method according to an embodiment of the present invention can be used in thermal insulation materials used in homes and automobiles, thermal insulation materials used in building materials, etc., transport packaging materials such as fish boxes and food containers, cushioning materials, etc. More specifically, the recycled expandable styrene resin particles, recycled pre-expanded styrene resin particles, and recycled styrene resin foam molded articles according to an embodiment of the present invention can be used in thermal insulation materials for walls, floors, roofs, automobiles, hot water tanks, pipes, solar energy systems, water heaters, containers for food and industrial products (e.g., fish boxes and other food containers, turnover boxes), cushioning materials, floats, blocks, packaging materials for fish and agricultural products, fill materials (fill blocks), tatami core materials, cushion core materials, concrete aggregates, etc.

Claims

1. A method for producing recycled expandable styrene resin particles having an alkylamine release of less than Yng / g using recycled styrene resin raw material particles (a) having an alkylamine release of Xng / g or more, wherein: X ≥ Y, Y≤5， A volatile foaming agent is injected and impregnated into the 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 the resulting particles. As the feed water used for preparing the suspension, water with a total content concentration of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Zn in the feed water of 0.01 mg / kg to 103 mg / kg is used.

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

3. Regenerated expandable styrene resin particles obtained by the production method according to claim 1 or 2, wherein the alkylamine release amount is less than 5 ng / g.

4. The regenerated expandable styrene resin particles according to claim 3, wherein The release of alkylamines is less than 2 ng / g.

5. Regenerated pre-foamed styrene resin particles obtained by pre-foaming the regenerated foamable styrene resin particles according to claim 3, wherein the pre-foaming volume expansion ratio is 2 to 150 times. A recycled styrene resin foamed molded article, which is molded from the recycled pre-foamed styrene resin particles according to claim 5.

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