Recycled foamable styrenic resin particle, recycled pre-expanded styrenic resin particle, and recycled styrenic resin foam molding

Abstract

To provide recycled foamable styrenic resin particles which have a high environmental contribution degree, and exhibit a beautiful white color tone having suppressed yellow tincture, to provide recycled pre-expanded styrenic resin particles obtained from the recycled foamable styrenic resin particles, and a recycled styrenic resin foam molding molded from the recycled pre-expanded styrenic resin particles.SOLUTION: Recycled foamable styrenic resin particles are obtained by press-fitting and impregnating a foaming agent into recycled styrenic resin particles (A), wherein in an L*a*b* colorimetric system, a color tone value calculated by L*+|a*|+(|b*|)3 is 20 or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to recycled expandable styrene-based resin particles, recycled pre-expanded styrene-based resin particles, and recycled styrene-based resin foamed articles. [Background technology]

[0002] Since foamed molded articles are lightweight and have excellent heat insulating properties and mechanical strength, they are widely used as heat insulating materials for houses and automobiles, heat retaining materials for building materials, embankment materials for polystyrene foam civil engineering, transport packaging materials for fish boxes and food containers, cushioning materials, etc. Among them, in-mold foamed molded articles manufactured from expandable particles (typically expandable polystyrene-based resin particles or pre-expanded styrene-based resin particles obtained by pre-expanding them) are widely used because of the advantage that they are easy to obtain the desired shape. Such foamed molded articles are composed of a plurality of expandable particles fused to each other.

[0003] On the other hand, the amount of plastic waste is increasing year by year. Most plastic waste is disposed of by incineration or landfilling, but it has become a major social problem, such as environmental pollution, global warming, and a lack of landfill sites. For this reason, there is a strong social demand for the reuse of plastic waste, and various methods for recycling plastic waste are being considered, such as with the enforcement of the Home Appliance Recycling Law. Among the various recycling methods proposed, material recycling, in which plastic waste is reused as plastic components of products, has attracted attention from the viewpoints of resource circulation and reducing environmental load, and such material recycling is also being considered for styrene resin foam moldings.

[0004] As a material recycling method for styrene-based resin foam moldings, several methods have been proposed for producing recycled expandable styrene-based resin particles, which are obtained by melting and extruding recovered raw materials to form recovered pellets, and then impregnating the pellets with a foaming agent.

[0005] Methods have been reported for obtaining recycled expandable styrene resin particles by impregnating or pressurizing and then impregnating with a blowing agent into recycled resin pellets molded from recovered styrene resin foam molded products (Patent Documents 1 to 4). Also, methods have been reported for obtaining recycled expandable styrene resin particles by adding styrene monomer to recycled resin pellets molded from recovered styrene resin foam molded products to cause nuclear polymerization, and then impregnating or pressurizing and then impregnating with a blowing agent (Patent Documents 5 to 9).

[0006] However, conventional recycled expandable styrene-based resin particles have a problem in that they have a noticeable yellowish tinge and poor color tone. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3044942 [Patent Document 2] Patent No. 4234832 [Patent Document 3] Patent No. 4261676 [Patent Document 4] Patent No. 6788428 [Patent Document 5] Patent No. 4052193 [Patent Document 6] JP 2006-160905 A [Patent Document 7] Patent No. 4912567 [Patent Document 8] Patent No. 5128246 [Patent Document 9] JP 2022-153315 A Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide recycled expandable styrene-based resin particles that are environmentally friendly and have a beautiful white color tone with less yellowness. It is also an object of the present invention to provide recycled pre-expanded styrene-based resin particles obtained from such recycled expandable styrene-based resin particles. It is also an object of the present invention to provide a recycled styrene-based resin foam molded article molded from such recycled pre-expanded styrene-based resin particles. [Means for solving the problem]

[0009] [1] The recycled expandable styrene resin particles according to an embodiment of the present invention are recycled expandable styrene resin particles obtained by injecting and impregnating a blowing agent into recycled styrene resin particles (A), and are L * a * b * In the color system, L * +|a * |+(|b * |) 3 The calculated color value is 20 to 800. [2] The recycled expandable styrene-based resin particles described in [1] above may be such that the recycled styrene-based resin particles (A) are obtained by nuclear polymerization of a styrene-based monomer using recycled styrene-based resin raw material particles (a) containing 10 mg / kg to 800 mg / kg of metallic zinc as a nucleus. [3] In the recycled expandable styrene-based resin particles described in the above [1], the recycled styrene-based resin particles (A) may contain 10 mg / kg to 800 mg / kg of metallic zinc element. [4] The recycled pre-expanded styrene-based resin particles according to an embodiment of the present invention are recycled pre-expanded styrene-based resin particles obtained by pre-expanding the recycled expandable styrene-based resin particles described in any one of [1] to [3] above, and the bulk expansion ratio of the pre-expanded particles is 2 to 150 times. [5] The recycled styrene-based resin foamed molded article according to the embodiment of the present invention is molded from the recycled pre-expanded styrene-based resin particles described in [4] above. Effect of the Invention

[0010] According to the present invention, it is possible to provide recycled expandable styrene-based resin particles that are environmentally friendly and exhibit beautiful white color with suppressed yellowness. It is also possible to provide recycled pre-expanded styrene-based resin particles obtained from such recycled expandable styrene-based resin particles. It is also possible to provide a recycled styrene-based resin foam molded article molded from such recycled pre-expanded styrene-based resin particles. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of an apparatus suitable for producing recycled expandable styrene-based resin particles according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0013] In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate.

[0014] <<A. Recycled expandable styrene resin particles>> The recycled expandable styrene resin particles according to the embodiment of the present invention have a particle shape as a whole. The average particle diameter 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 diameter can be measured in accordance with JIS Z 8815. Specifically, the average particle diameter is the value measured as a particle diameter of 50% of the cumulative value from the particle size distribution by the sieving test of JIS Z 8815.

[0015] The shape of the recycled expandable styrene resin particles according to the embodiment of the present invention can be any suitable shape as long as it does not impair the effects of the present invention. Specific examples of such shapes include, for example, spherical, approximately spherical, and elliptical (egg-shaped). The shape of the recycled expandable styrene resin particles according to the embodiment of the present invention is preferably spherical or approximately spherical, and more preferably spherical, in terms of achieving the effects of the present invention. However, in reality, it is difficult to distinguish between spherical and approximately spherical, so in this specification, both are collectively referred to as spherical.

[0016] The weight average molecular weight of the recycled expandable styrene-based resin particles according to the embodiment of the present invention can be any appropriate weight average molecular weight within a range that does not impair the effects of the present invention. Such a weight average molecular weight is preferably 100,000 to 510,000, more preferably 110,000 to 490,000, even more preferably 120,000 to 470,000, and particularly preferably 130,000 to 450,000.

[0017] The recycled expandable styrene resin particles according to an embodiment of the present invention are L * a * b * In the color system, L * +|a * |+(|b * |) 3 The color value calculated by the above formula is 20 to 800, preferably 25 to 800, more preferably 30 to 750, even more preferably 35 to 750, particularly preferably 40 to 700, and most preferably 45 to 700. * +|a * |+(|b * |) 3 If the color value calculated by the above formula is within the above range, the recycled expandable styrene-based resin particles according to the embodiment of the present invention can exhibit a beautiful white color with reduced yellowness. * +|a * |+(|b * |) 3 The color value calculated by L * a * b * b in color system *This is an index weighted by b * is a color dimension that reflects yellowness, and L * +|a * |+(|b * |) 3 By adjusting the color tone value calculated by the above to within the above range, a beautiful white tone with reduced yellowness can be achieved. * +|a * |+(|b * |) 3 If the color value calculated by is too small and falls outside the above range, the molded product may appear dull. * +|a * |+(|b * |) 3 If the color value calculated by |a is too large and deviates from the above range, the molded product may have a yellowish tinge and may appear to have yellowed and deteriorated. * | is a * means the absolute value of |b * | is b * means the absolute value of

[0018] Preferred embodiments of the recycled expandable styrene-based resin particles of the present invention include the following two embodiments. Embodiment (1): Recycled expandable styrene-based resin particles obtained by injecting and impregnating a blowing agent into recycled styrene-based resin particles (A), the recycled styrene-based resin particles (A) being obtained by nuclear polymerization of a styrene-based monomer using recycled styrene-based resin raw material particles (a) containing 10 mg / kg to 800 mg / kg of metallic zinc element as a nucleus. Embodiment (2): Recycled expandable styrene-based resin particles obtained by injecting and impregnating a blowing agent into recycled styrene-based resin particles (A), the recycled styrene-based resin particles (A) containing 10 mg / kg to 800 mg / kg of metallic zinc element.

[0019] The recycled expandable polystyrene resin particles according to the embodiments of the present invention have a high environmental contribution. The recycled expandable polystyrene resin particles in the above embodiment (1) preferably have a recycling rate of 10% or more, more preferably 20% or more, and even more preferably 25% or more. The recycled expandable polystyrene resin particles in the above embodiment (2) preferably have a recycling rate of 50% or more, more preferably 70% or more, even more preferably 90% or more, particularly preferably 95% or more, and most preferably 100%. The recycling rate is the ratio of the recovered styrene resin in the styrene resin contained in the recycled expandable polystyrene resin particles.

[0020] Hereinafter, first, the above embodiment (1) and embodiment (2) will be described.

[0021] ≪A-1. Preferred Embodiment (1) of Recycled Expandable Polystyrene Resin Particles≫ One preferred embodiment (1) of the recycled expandable polystyrene resin particles of the present invention is recycled expandable polystyrene resin particles obtained by press-fitting and impregnating a foaming agent into recycled styrene resin particles (A), wherein the recycled styrene resin particles (A) are obtained by subjecting recycled styrene resin raw material particles (a) containing 10 mg / kg to 800 mg / kg of a metallic zinc element as nuclei to nuclear polymerization of a styrene monomer, and are recycled expandable polystyrene resin particles.

[0022] <A-1-1. Recycled Styrene Resin Particles (A) in Embodiment (1)> The recycled styrene resin particles (A) in embodiment (1) are obtained by subjecting recycled styrene resin raw material particles (a) containing 10 mg / kg to 800 mg / kg of a metallic zinc element as nuclei to nuclear polymerization of a styrene monomer.

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

[0024] As the material for the recycled styrene-based resin raw material particles (a), any suitable recycled styrene-based resin can be used within the scope that does not impair the effects of the present invention. Examples of such recycled styrene-based resins include recycled products of plastic materials used in polystyrene foam (molded products such as fish boxes and agricultural boxes, cushioning materials, block molded products, etc.), foamed sheets (tray containers, broken sheets, etc.), home appliances, packaging containers, cushion beads, etc.

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

[0026] As the recycled styrene-based resin raw material particles (a), molded products made from products under the trade names "EPSREM" and "ESLENE BEAD RNW" manufactured by Sekisui Plastics Co., Ltd. may be used.

[0027] The recycled styrene-based resin raw material particles (a) may be a pulverized product obtained by pulverizing a recycled resin obtained by heating and / or reducing the volume of a used expanded styrene-based resin. The recycled styrene-based resin raw material particles may be pelletized by extrusion molding the pulverized product, or may be pelletized by further pulverizing the pellets. Alternatively, the recycled styrene-based resin raw material particles may be a reduced-volume recovered product using a solvent such as limonene.

[0028] The recycled styrene resin raw material particles (a) are preferably pellets obtained by melt extrusion, which is a method in which crushed products, ingots, foamed particles, etc. of used styrene resin are fed to a resin feeder, melted in the resin feeder, extruded from small holes in a die attached to the tip of the resin feeder, and then cooled to obtain pellets.

[0029] The pellets obtained by the melt extrusion method are preferably at least one type selected from extruded strand pellets obtained by extruding used expanded styrene-based resin with an extruder and strand cutting it, underwater cut pellets obtained by an underwater cutting method in which used expanded styrene-based resin is extruded with an extruder and simultaneously cut in water, and hot cut pellets obtained by a hot cutting method in which used expanded styrene-based resin particles are cut and cooled immediately after coming out of the die of an extruder.

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

[0031] The recycled styrene-based resin raw material particles (a) may be a shrinkage or molten product of a styrene-based resin that is obtained by coarsely crushing used styrene-based resin into an appropriate size as necessary, and then subjecting the resin to heat shrinkage, bubble destruction shrinkage due to compression, shrinkage due to frictional heat, melting, or the like.

[0032] Examples of used expanded styrene resin include molded products obtained by molding expandable styrene resin into a mold and products obtained by heating and expanding the molded products.

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

[0034] Examples of fine powder inorganic substances include talc, calcium carbonate, and silica. Here, talc typically refers to a mixture mainly composed of silicon oxide and magnesium oxide, and containing trace amounts of aluminum oxide, iron oxide, etc.

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

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

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

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

[0039] A specific method for including a fine powder inorganic substance and / or an organic lubricant in the recycled styrene-based resin raw material particle (a) is, for example, a method of kneading a fine powder inorganic substance and / or an organic lubricant during extrusion molding. In this case, it is preferable to mix the pulverized material and the bubble regulator in advance, and then extrusion molding. The method for mixing the pulverized material and the bubble regulator can be any appropriate method within a range that does not impair the effects of the present invention. Examples of such methods include a mixing method using a mixer such as a tumbler, a ribbon blender, a V blender, a Henschel mixer, or a Redigay mixer.

[0040] The recycled styrene-based resin raw material particles (a) are preferably thermally melted for the purpose of adjusting the specific gravity. In this step, the specific gravity of the recycled styrene-based resin raw material particles (a) is preferably adjusted to 0.6 or more, more preferably adjusted to 0.9 or more. If the specific gravity of the recycled styrene-based resin raw material particles (a) is less than 0.6, the dispersion of the recycled styrene-based resin raw material particles (a) is unstable, so that excessively large particles may be generated during the subsequent polymerization step, resulting in a reduced yield. The recycled styrene-based resin raw material particles (a) may be thermally melted by any appropriate method within a range that does not impair the effects of the present invention. Examples of such methods include a method using an extruder or a heat roll. It is preferable that the thermal melting is performed by cooling and solidifying the resin obtained in a state in which no distortion remains in the resin obtained or in a state in which the distortion is small. If distortion remains in the resin particles, the distortion may be relaxed in the subsequent step, causing the particles to shrink in the stretching direction, and the resulting recycled expandable styrene-based resin particles may become flat rather than spherical. Therefore, it is preferable to use an extruder for the thermal melting without stretching. If the thermal melting is performed in a stretched state, there is a risk that distortion will remain in the stretched resin obtained by cooling and solidifying. Even if distortion remains in the resin due to thermal melting, it is possible to alleviate the distortion by curing the resin for a certain period of time at a temperature above the softening point of the resin.

[0041] For the pulverization to obtain the recycled styrene-based resin raw material particles (a), any pulverizer can be used as long as it does not impair the effects of the present invention. As such a pulverizer, for example, a pulverizer for plastics can be used, and a pulverizer for polystyrene is preferable.

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

[0043] The average particle diameter of the recycled styrene-based resin raw material particles (a) is preferably 0.2 mm to 3.0 mm, more preferably 0.3 mm to 2.5 mm, further preferably 0.4 mm to 2.0 mm, and particularly preferably 0.5 mm to 1.7 mm. If the average particle diameter of the recycled styrene-based resin raw material particles (a) exceeds 3 mm, the shape of the resulting recycled expandable styrene-based resin particles may be difficult to become spherical. If the average particle diameter of the recycled styrene-based resin raw material particles (a) is less than 0.2 mm, the average particle diameter of the resulting recycled expandable styrene-based resin particles may be too small.

[0044] The L (long side) / D (short side) of the recycled styrene-based resin raw material particle (a) is preferably 1.0 to 6.0, more preferably 1.0 to 5.0, even more preferably 1.0 to 4.0, particularly preferably 1.0 to 3.0, and most preferably 1.0 to 2.5. If the L (long side) / D (short side) of the recycled styrene-based resin raw material particle (a) is out of the above range, the shape of the obtained recycled expandable styrene-based resin particles may be difficult to become spherical.

[0045] The recycled styrene-based resin raw material particles (a) preferably have a content of particles with an average particle size of 200 μm or less of less than 1 mass %. Recycled styrene-based resin raw material particles (a) having a content of particles with an average particle size of 200 μm or less of 1 mass % or more may deteriorate the appearance of the recycled expandable styrene-based resin particles obtained using the recycled styrene-based resin raw material particles (a).

[0046] The weight-average molecular weight of the recycled styrene-based resin raw material particles (a) is preferably 100,000 to 510,000, and more preferably 150,000 to 490,000. If the weight-average molecular weight of the recycled styrene-based resin raw material particles (a) is less than 100,000, sufficient strength may not be obtained. If the weight-average molecular weight of the recycled styrene-based resin raw material particles (a) is more than 510,000, the recycled styrene-based resin raw material particles may not be easily spherical, or the foaming property may decrease, resulting in poor appearance of the molded product.

[0047] In embodiment (1), the recycled styrene-based resin raw material particle (a) contains 10 mg / kg to 800 mg / kg of metallic zinc element. That is, in embodiment (1), the content ratio of metallic zinc element in the recycled styrene-based resin raw material particle (a) is 10 mg / kg to 800 mg / kg, preferably 15 mg / kg to 700 mg / kg, more preferably 20 mg / kg to 600 mg / kg, even more preferably 25 mg / kg to 500 mg / kg, and particularly preferably 30 mg / kg to 450 mg / kg. In embodiment (1), if the content ratio of metallic zinc element in the recycled styrene-based resin raw material particle (a) is within the above range, the effect of the present invention can be more effectively exhibited, and the recycled expandable styrene-based resin particle according to the embodiment of the present invention can exhibit a more beautiful white tone with less yellowish tinge. In embodiment (1), if the content ratio of metallic zinc element in the recycled styrene-based resin raw material particle (a) is too small outside the above range, the molded product may look dull. In embodiment (1), if the content of metallic zinc element in the recycled styrene-based resin raw material particles (a) is too high and deviates from the above range, the molded product may have a yellowish tinge and appear to have yellowed and deteriorated, or the fusion rate between the foamed particles during molding may decrease, resulting in reduced moldability.

[0048] In the embodiment (1), the method of adjusting the content ratio of metallic zinc element in the recycled styrene-based resin raw material particle (a) to 10mg / kg to 800mg / kg can be any suitable method within the scope of not impairing the effects of the present invention. For example, when producing the recycled styrene-based resin raw material particle (a), if necessary, at least one selected from the group consisting of (i) recycled styrene-based resin with a high content ratio of metallic zinc element (e.g., more than 800mg / kg) and (ii) recycled styrene-based resin with a low content ratio of metallic zinc element (e.g., less than 10mg / kg) is used to adjust the content ratio of metallic zinc element in the obtained recycled styrene-based resin raw material particle (a) to 10mg / kg to 800mg / kg.

[0049] The styrene-based monomer used in the nuclear polymerization may be one type alone or two or more types.

[0050] The styrene monomer includes styrene or a styrene derivative. Examples of the styrene derivative include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. The styrene monomer may be one type or two or more types. The styrene monomer preferably contains at least styrene. The content ratio of styrene 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.

[0051] The styrene monomer may contain any suitable vinyl monomer other than the styrene monomer, as long as the effect of the present invention is not impaired. For example, a polyfunctional monomer, a (meth)acrylic acid ester monomer, a maleic acid ester monomer, and a fumaric acid ester monomer may be included. Such vinyl monomers may be one type only, or two or more types may be included.

[0052] Specific examples of polyfunctional monomers 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 (meth)acrylic acid ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and hexyl (meth)acrylate. Examples of maleic acid ester monomers include dimethyl maleate. Examples of fumaric acid ester monomers include dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

[0053] In embodiment (1), the content ratio of the recycled styrene resin raw material particle (a) to the total amount of the recycled styrene resin raw material particle (a) and the styrene monomer is the higher from the viewpoint of environmental contribution. However, from the viewpoint of producing the recycled styrene resin particle (A) by nuclear polymerization, the content ratio of the recycled styrene resin raw material particle (a) to the total amount of the recycled styrene resin raw material particle (a) and the styrene monomer is preferably 5% by mass to 90% by mass, more preferably 10% by mass to 85% by mass, even more preferably 15% by mass to 80% by mass, even more preferably 20% by mass to 75% by mass, and particularly preferably 25% by mass to 70% by mass.

[0054] In embodiment (1), the recycled styrene-based resin particles (A) are obtained by nuclear polymerization of a styrene-based monomer with the recycled styrene-based resin raw material particles (a) as the nucleus. Any suitable method can be adopted as the nuclear polymerization method as long as it does not impair the effects of the present invention. One preferred embodiment of such a nuclear polymerization method is a method in which an emulsion containing a polymerization initiator and a styrene-based monomer is added to a suspension obtained by dispersing the recycled styrene-based resin raw material particles (a) as the nucleus in an aqueous medium to impregnate the recycled styrene-based resin raw material particles (a), and then a styrene-based monomer is added to carry out polymerization.

[0055] When obtaining the recycled styrene-based resin particles (A), the addition temperature when adding the styrene-based monomer to the recycled styrene-based resin raw material particles (a) is preferably 40 ° C. to 119 ° C., more preferably 40 ° C. to 118 ° C., even more preferably 40 ° C. to 117 ° C., particularly preferably 50 ° C. to 117 ° C., and most preferably 60 ° C. to 115 ° C. If the addition temperature when adding the styrene-based monomer to the recycled styrene-based resin raw material particles (a) is adjusted within the above range, the styrene-based monomer can be incorporated while maintaining the recycled styrene-based resin raw material particles (a) at a moderate hardness, so that the recycled styrene-based resin particles (A) can be well spheroidized, and the finally obtained recycled expandable styrene-based resin particles can be well spheroidized and have excellent moldability. If the addition temperature when adding the styrene monomer to the recycled styrene resin raw material particle (a) is too low outside the above range, the recycled styrene resin raw material particle (a) becomes too hard, and when the styrene monomer is incorporated in this state, the recycled styrene resin particle (A) becomes difficult to be spherical, and the finally obtained recycled expandable styrene resin particle may be difficult to be spherical or may have poor moldability. If the addition temperature when adding the styrene monomer to the recycled styrene resin raw material particle (a) is too high outside the above range, the recycled styrene resin raw material particle (a) becomes too soft, and when the styrene monomer is incorporated in this state, the recycled styrene resin particle (A) becomes difficult to be spherical, and the finally obtained recycled expandable styrene resin particle may be difficult to be spherical or may have poor moldability. In addition, the "addition temperature when adding a styrene monomer to the recycled styrene resin raw material particles (a)" means the addition temperature during the addition of the emulsion containing the polymerization initiator and the styrene monomer, and the subsequent addition of the styrene monomer.

[0056] When dispersing the recycled styrene-based resin raw material particles (a) as nuclei in an aqueous medium to obtain a suspension, any suitable method can be adopted as a method for dispersing the recycled styrene-based resin raw material particles (a) in an aqueous medium, as long as it does not impair the effects of the present invention. As a method for such dispersion, a preferred method is dispersion using a device equipped with stirring blades. As a method for more fine dispersion, a method using a homomixer can be mentioned.

[0057] When dispersing the recycled styrene-based resin raw material particles (a) as nuclei in an aqueous medium to obtain a suspension, it is preferable to use a dispersant in dispersing the recycled styrene-based resin raw material particles (a) in the aqueous medium. Any suitable dispersant can be used as long as it can be used in suspension polymerization, as long as it does not impair the effects of the present invention. Examples of such dispersants include organic dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, and methylcellulose; and poorly soluble inorganic salts such as magnesium pyrophosphate and calcium triphosphate. Among these, magnesium pyrophosphate is preferred as the dispersant in that it can further express the effects of the present invention.

[0058] The blending ratio of the dispersant per 100 parts by mass of the recycled styrene-based resin particles (A) is preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.1 to 1.0 part by mass.

[0059] When dispersing the recycled styrene-based resin raw material particles (a) as nuclei in an aqueous medium to obtain a suspension, it is preferable to use a surfactant in dispersing the recycled styrene-based resin raw material particles (a) in the aqueous medium. Any appropriate surfactant may be used as long as it can be used in suspension polymerization, as long as it does not impair the effects of the present invention. Examples of such surfactants include sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylsulfonate, sodium alkyldiphenyletherdisulfonate, and sodium α-olefinsulfonate. Among these, sodium dodecylbenzenesulfonate is preferable as the surfactant in that it can further express the effects of the present invention.

[0060] The blending ratio of the surfactant per 100 parts by mass of the recycled styrene-based resin particles (A) is preferably 0.005 parts by mass to 0.1 parts by mass, more preferably 0.005 parts by mass to 0.08 parts by mass, and even more preferably 0.005 parts by mass to 0.06 parts by mass.

[0061] As the emulsification method for obtaining an emulsion containing a polymerization initiator and a styrene-based monomer, any appropriate method can be adopted as long as it does not impair the effects of the present invention. As such a dispersion method, a preferred dispersion method is one using an apparatus equipped with an agitator. As a method for more fine dispersion, a method using a homomixer can be mentioned. At this time, it is preferable to disperse until the oil droplet diameter of the dispersion in which the styrene-based monomer is dispersed becomes equal to or smaller than the particle diameter of the nucleus. If the oil droplet diameter is larger than the particle diameter of the nucleus when added to an aqueous medium, a plurality of recycled styrene-based resin raw material particles (a) are taken into the oil droplets of the dispersion in which the styrene-based monomer is dispersed, and adhesion, plasticization, and coalescence of the recycled styrene-based resin raw material particles (a) occur, which makes it easy for excessively large particles to be generated.

[0062] As the polymerization initiator used in obtaining an emulsion containing a polymerization initiator and a styrene-based monomer, any suitable polymerization initiator can be used as long as it is used in a 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, t-butylperoxy-2-ethylhexyl carbonate, and t-butylperbenzoate; and azo compounds such as azobisisobutyronitrile. The polymerization initiator may be one type only or two or more types.

[0063] 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, and further preferably 0.1% by mass to 0.5% by mass, based on the styrene monomer.

[0064] The polymerization initiator is preferably added after being dissolved in a styrene monomer or a solvent. Examples of the solvent include aromatic hydrocarbons such as ethylbenzene and toluene; and aliphatic hydrocarbons such as heptane and octane. When a solvent is used, it is usually used in an amount of 10% by mass or less based on the styrene monomer.

[0065] As a method of adding the styrene monomer after impregnating the suspension containing the recycled styrene resin raw material particles (a) with the emulsion containing the styrene monomer, any suitable method can be adopted within the scope that does not impair the effects of the present invention. Such a method includes, for example, divisional addition and continuous addition. The addition speed is appropriately selected according to the capacity, shape, polymerization temperature, etc. of the polymerization apparatus.

[0066] After impregnating the suspension containing the recycled styrene-based resin raw material particles (a) with an emulsion containing a styrene-based monomer, the styrene-based monomer may be added and then the polymerization reaction may be continued at any appropriate temperature and time, as necessary.

[0067] 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 a bubble regulator include fatty acid monoamides such as oleic acid amide, stearic acid amide, and hydroxystearic acid amide; fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide.

[0068] <A-1-2. Pressurization and impregnation of the foaming agent in Embodiment (1)> The recycled foamed styrene resin particles in Embodiment (1) are obtained by pressurizing and impregnating the recycled styrene resin particles (A) with a foaming agent.

[0069] Typical methods for the pressurization and impregnation of the foaming agent in Embodiment (1) include putting the recycled styrene resin particles (A) into a reactor such as an autoclave and pressurizing and impregnating the foaming agent.

[0070] The foaming agent may be only one kind or two or more kinds.

[0071] As the foaming agent, any suitable foaming agent can be used as long as it does not impair the effects of the present invention. The foaming agent referred to here is preferably a volatile foaming agent. The foaming agent is preferably an organic compound whose boiling point is equal to or lower than the softening point of the styrene-based resin and is in a gaseous or liquid state at normal pressure. Specific examples include aliphatic hydrocarbons such as propane, n-butane, isobutane, pentane (n-pentane, isopentane, neopentane), and n-hexane; alicyclic hydrocarbons such as cyclopentane and cyclopentadiene; ketones such as acetone and methyl ethyl ketone; alcohols such as methanol, ethanol, and isopropyl alcohol; low-boiling ether compounds such as dimethyl ether, diethyl ether, dipropyl ether, and methyl ethyl ether; halogen-containing hydrocarbons such as trichloromonofluoromethane and dichlorodifluoromethane; and the like. As the foaming agent, inorganic gases such as carbon dioxide, nitrogen, and ammonia may be used. Among these, in terms of further exerting the effects of the present invention, the blowing agent is preferably at least one selected from n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, and cyclopentadiene, and more preferably at least one selected from n-butane, isobutane, n-pentane, and isopentane.

[0072] The content of the blowing agent can be appropriately set according to the purpose as long as it is a sufficient amount to form the recycled pre-expanded styrene-based resin particles and the recycled styrene-based resin foamed molded article. The content of the blowing agent is preferably 2 to 15 parts by mass when the total amount of the recycled styrene-based resin raw material particles (a) and the styrene-based monomer is 100 parts by mass.

[0073] In the embodiment (1), the temperature of the blowing agent injected into the recycled styrene-based resin particles (A) is preferably 40°C to 150°C, more preferably 50°C to 140°C, even more preferably 60°C to 130°C, even more preferably 70°C to 123°C, even more preferably 80°C to 115°C, particularly preferably 90°C to 110°C, and most preferably 95°C to 105°C. The temperature of the blowing agent injected into the recycled styrene-based resin particles (A) may be changed within the above range. If the temperature of the blowing agent injected into the recycled styrene-based resin particles (A) is within the above range, the blowing agent is prevented from being rapidly impregnated into the recycled styrene-based resin particles (A), and uniform impregnation is possible. For example, the number of parts that shrink and melt when molded into a recycled styrene-based resin foamed molded product can be reduced, and the odor peculiar to the recycled raw material can be easily removed. If the temperature at which the blowing agent is injected into the recycled styrene-based resin particles (A) is too low outside the above range, the blowing agent is difficult to impregnate into the recycled styrene-based resin particles (A) when the blowing agent is injected, and for example, the blowing agent is rapidly impregnated when the temperature is increased, and the blowing agent is not uniformly impregnated into the recycled styrene-based resin particles (A), which is likely to cause bubble variations and surface shrinkage during molding. If the temperature at which the blowing agent is injected into the recycled styrene-based resin particles (A) is too high outside the above range, the blowing agent is rapidly impregnated into the recycled styrene-based resin particles (A) when the blowing agent is injected, and the blowing agent is not uniformly impregnated into the recycled styrene-based resin particles (A), which is likely to cause bubble variations and surface shrinkage during molding.

[0074] In embodiment (1), one embodiment of the impregnation temperature of the blowing agent into the recycled styrene-based resin particles (A) is preferably 40°C to 150°C, more preferably 40°C to 140°C, even more preferably 40°C to 130°C, even more preferably 40°C to 123°C, even more preferably 40°C or higher and less than 110°C, particularly preferably 40°C to 105°C, and most preferably 40°C to 102°C.

[0075] In embodiment (1), another embodiment of the impregnation temperature of the blowing agent into the recycled styrene-based resin particles (A) is preferably a temperature equal to or higher than the injection temperature of the blowing agent into the recycled styrene-based resin particles (A) (which may be the same as the injection temperature of the blowing agent into the recycled styrene-based resin particles (A)), preferably 93°C to 130°C, more preferably 94°C to 129°C, even more preferably 95°C to 128°C, particularly preferably 96°C to 127°C, and most preferably 97°C to 126°C.

[0076] The temperature of impregnation of the blowing agent into the recycled styrene-based resin particles (A) may be changed within the above range. If the impregnation temperature of the blowing agent into the recycled styrene-based resin particles (A) is within the above range, in combination with the adjustment of the above-mentioned pressure-in temperature, the blowing agent is prevented from being rapidly impregnated into the recycled styrene-based resin particles (A), enabling uniform impregnation, and for example, reducing the number of areas that shrink and melt when molded into a recycled styrene-based resin foamed molded product. If the impregnation temperature of the blowing agent into the recycled styrene-based resin particles (A) is too low outside the above range, the blowing agent may not be impregnated to the center of the recycled styrene-based resin particles (A), leaving non-foamed areas, and it may not be possible to obtain a good molded product. If the impregnation temperature of the blowing agent into the recycled styrene-based resin particles (A) is too high outside the above range, the blowing agent may be impregnated too much into the recycled styrene-based resin particles (A), causing it to melt during molding.

[0077] In embodiment (1), a particularly representative embodiment of the impregnation temperature of the blowing agent into the recycled styrene-based resin particles (A) is preferably 40°C to 150°C, more preferably 50°C to 130°C, even more preferably 60°C to 120°C, even more preferably 70°C or more and less than 110°C, even more preferably 80°C or more and less than 110°C, particularly preferably 90°C or more and less than 110°C, and most preferably 95°C to 105°C.

[0078] The time for impregnating the recycled styrene-based resin particles (A) with the blowing agent can be any appropriate time within the range that does not impair the effects of the present invention, and is preferably 1 hour to 10 hours.

[0079] <A-1-3. Other Components in Embodiment (1)> The recycled expandable styrene resin particles in Embodiment (1) may contain any appropriate other components as long as the effects of the present invention are not impaired. Such other components may be only one type or two or more types.

[0080] The recycled expandable styrene resin particles in Embodiment (1) may contain a flame retardant in order to enhance flame retardancy. The flame retardant may be only one type or two or more types.

[0081] As the flame retardant, any appropriate flame retardant can be adopted as long as the effects of the present invention are not impaired. As such a flame retardant, a bromine compound compatible with polystyrene is preferable. For example, 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, hexabromobenzene can be mentioned.

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

[0083] The total amount of the flame retardant and the flame retardant auxiliary may be any appropriate amount within the range that does not impair the effects of the present invention. The total amount is preferably 0.1% to 15% by mass, more preferably 0.2% to 10% by mass, even more preferably 0.2% to 5% by mass, and particularly preferably 0.2% to 3% by mass, based on the recycled styrene-based resin raw material particles (a).

[0084] The flame retardant may be added at any appropriate timing as long as the effect of the present invention is not impaired. In order to more effectively demonstrate the effect of the present invention, it is preferable that the flame retardant is added before the blowing agent is injected. By adding the flame retardant before the blowing agent is injected, the flame retardant can be added at a low temperature equivalent to the temperature at which the blowing agent is injected, and therefore the resulting recycled expandable styrene-based resin particles can be well spherical and have excellent moldability.

[0085] The addition temperature when adding the flame retardant is preferably 5°C to 120°C, more preferably 5°C to 118°C, even more preferably 5°C to 115°C, even more preferably 5°C to 113°C, even more preferably 5°C to 110°C, even more preferably 40°C to 89°C, even more preferably 40°C to 87°C, even more preferably 40°C to 85°C, particularly preferably 40°C to 83°C, and most preferably 40°C to 80°C, in order to better exhibit the effects of the present invention.

[0086] In producing the recycled expandable styrene-based resin particles in the embodiment (1), a partial ester of a higher fatty acid and an alcohol may be used as the cell regulator. That is, the recycled expandable styrene-based resin particles in the embodiment (1) may contain a partial ester of a higher fatty acid and an alcohol. The partial ester of a higher fatty acid and an alcohol may be only one type or two or more types. Examples of the higher fatty acid include fatty acids having 15 or more carbon atoms such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and behenic acid, and monoglycerides and diglycerides thereof can be used. Examples of the partial ester of a higher fatty acid and an alcohol include preferably stearic acid monoglyceride and stearic acid diglyceride. The content ratio of the partial ester of a higher fatty acid and an alcohol is preferably 0 to 3.0 parts by mass, more preferably 0.5 to 3.0 parts by mass, relative to 100 parts by mass of the recycled styrene-based resin particles (A). The partial ester of higher fatty acid and alcohol may be added by, for example, adding it together with a foaming agent, or by any commonly used method such as a dry blend method, a master batch method, or a melt injection method.

[0087] In producing the recycled expandable styrene-based resin particles in embodiment (1), a foaming assistant may be used. That is, the recycled expandable styrene-based resin particles in embodiment (1) may contain a foaming assistant. The foaming assistant may be only one type, or may be two or more types. Examples of the foaming assistant include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, and coconut oil.

[0088] In the production of the recycled expandable polystyrene resin particles in Embodiment (1), a cell regulator may be used. That is, the recycled expandable polystyrene resin particles in Embodiment (1) may contain a cell regulator. The cell regulator may be only one kind or two or more kinds. Examples of the cell regulator include fatty acid monoamides such as oleic acid amide, stearic acid amide, and hydroxystearic acid amide; and fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide.

[0089] As the amount of the cell regulator used, any appropriate amount can be adopted as long as the effects of the present invention are not impaired. Such an amount is preferably 0 parts by mass to 5.0 parts by mass, more preferably 0.02 parts by mass to 3.0 parts by mass, still more preferably 0.02 parts by mass to 2.0 parts by mass, and particularly preferably 0.02 parts by mass to 1.0 parts by mass with respect to 100 parts by mass of the recycled polystyrene resin particles (A).

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

[0091] Examples of other additives include pigments, radiation heat transfer suppressing components, crosslinking agents, plasticizers, stabilizers, fillers, lubricants, colorants, antistatic agents, spreading agents, weathering agents, antioxidants, antifogging agents, and fragrances in addition to these.

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

[0093] When the recycled expandable styrene resin particles in embodiment (1) are surface-treated with silicone oil, the amount of silicone oil used relative to 100 parts by mass of recycled expandable styrene resin particles before surface treatment is preferably 0.001 parts by mass to 0.3 parts by mass, more preferably 0.003 parts by mass to 0.28 parts by mass, even more preferably 0.005 parts by mass to 0.25 parts by mass, particularly preferably 0.008 parts by mass to 0.23 parts by mass, and most preferably 0.01 parts by mass to 0.23 parts by mass. If the amount of silicone oil used is too small outside the above range, for example, when an antistatic agent is used, the affinity with the antistatic agent during pre-foaming may be insufficient, and static electricity may be easily generated. If the amount of silicone oil used is too large outside the above range, the surface may melt during molding, resulting in loss of surface properties.

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

[0095] As the silicone oil, any suitable silicone oil can be adopted as long as it does not impair the effect of the present invention.In terms of being able to more effectively exhibit the effect of the present invention, the silicone oil can be, for example, straight silicone oil such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, etc., and preferably methylphenylpolysiloxane.

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

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

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

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

[0100] As the nonionic surfactant, any suitable nonionic surfactant may be adopted as long as it does not impair the effects of the present invention. In terms of being able to more effectively express the effects of the present invention, examples of the nonionic surfactant include polyethylene glycol, glycerin, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyhydric alcohol, and 1-amino-2-hydroxy compound. Specific examples of the polyoxyethylene alkyl ether include polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. Specific examples of the polyoxyethylene alkyl ester include polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, and polyoxyethylene oleate. Specific examples of the polyhydric alcohol include glycerin and propylene glycol. 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 Examples of the hydroxyethyl amine include 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.As the nonionic surfactant, polyethylene glycol is preferred in that the effects of the present invention can be more effectively exhibited.

[0101] When a nonionic surfactant is used as at least a part of the antistatic agent, the amount of the nonionic surfactant used relative to 100 parts by mass of recycled expandable styrene-based resin particles before surface treatment is preferably 0.001 parts by mass to 2.0 parts by mass, more preferably 0.001 parts by mass to 1.5 parts by mass, even more preferably 0.001 parts by mass to 1.0 parts by mass, even more preferably 0.001 parts by mass to 0.5 parts by mass, even more preferably 0.001 parts by mass to 0.3 parts by mass, even more preferably 0.005 parts by mass to 0.28 parts by mass, even more preferably 0.01 parts by mass to 0.27 parts by mass, particularly preferably 0.015 parts by mass to 0.26 parts by mass, and most preferably 0.02 parts by mass to 0.25 parts by mass. If the amount of the nonionic surfactant is too small outside the above range, static electricity may be easily generated during pre-expansion. If the amount of the nonionic surfactant is too large and deviates from the above range, the surfaces of the recycled pre-expanded styrene-based resin particles and the recycled styrene-based resin foamed molded article may become sticky.

[0102] The fatty acid glyceride may be of only one type, or of two or more types.

[0103] As the fatty acid glyceride, any suitable fatty acid glyceride can be adopted as long as it does not impair the effects of the present invention.Specific examples of the fatty acid glyceride that can further demonstrate the effects of the present invention include stearic acid monoglyceride and linoleic acid monoglyceride.As the fatty acid glyceride, stearic acid monoglyceride is preferred in terms of further demonstrating the effects of the present invention.

[0104] When fatty acid glyceride is used as at least a part of the antistatic agent, the amount of the fatty acid glyceride relative to 100 parts by mass of the recycled expandable styrene-based resin particles before surface treatment is preferably 0.001 parts by mass to 0.3 parts by mass, more preferably 0.005 parts by mass to 0.28 parts by mass, even more preferably 0.01 parts by mass to 0.27 parts by mass, particularly preferably 0.015 parts by mass to 0.26 parts by mass, and most preferably 0.02 parts by mass to 0.25 parts by mass. If the amount of fatty acid glyceride is too small outside the above range, static electricity may be easily generated during pre-expansion. If the amount of fatty acid glyceride is too large outside the above range, the surface of the recycled pre-expanded styrene-based resin particles or the recycled styrene-based resin foamed molded article may become sticky.

[0105] When the recycled expandable styrene resin particles in the embodiment (1) are surface-treated with a fatty acid metal salt, the amount of fatty acid metal salt used relative to 100 parts by mass of recycled expandable styrene resin particles before surface treatment is preferably 0.005 parts by mass to 0.5 parts by mass, more preferably 0.007 parts by mass to 0.45 parts by mass, even more preferably 0.01 parts by mass to 0.4 parts by mass, particularly preferably 0.015 parts by mass to 0.35 parts by mass, and most preferably 0.02 parts by mass to 0.3 parts by mass. If the amount of fatty acid metal salt is too small outside the above range, blocking may occur frequently during pre-expansion, and a good styrene resin foam molded article may not be obtained. If the amount of fatty acid metal salt is too large outside the above range, a large amount of metal salt is present during pre-expansion, which makes it easy to be charged, which makes it easy to generate static electricity, and the fusion of the molded article may be poor.

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

[0107] As the fatty acid metal salt, any suitable fatty acid metal salt may be adopted as long as it does not impair the effects of the present invention. In terms of being able to more effectively express the effects of the present invention, examples of the fatty acid metal salt include metal stearates and metal laurates. Specific examples of the metal stearates include magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate. Specific examples of the metal laurate include zinc laurate and barium laurate. In terms of being able to more effectively express the effects of the present invention, magnesium stearate and zinc stearate are preferred as fatty acid metal salts.

[0108] In the case where the recycled expandable styrene resin particles in the embodiment (1) are surface-treated with a fusion accelerator, the amount of the fusion accelerator used relative to 100 parts by mass of the recycled expandable styrene resin particles before the surface treatment is preferably 0.01 parts by mass to 0.8 parts by mass, more preferably 0.01 parts by mass to 0.7 parts by mass, even more preferably 0.01 parts by mass to 0.6 parts by mass, particularly preferably 0.01 parts by mass to 0.55 parts by mass, and most preferably 0.013 parts by mass to 0.5 parts by mass. If the amount of the fusion accelerator is too small outside the above range, the fusion property during molding may decrease, and it may not be possible to obtain a good recycled styrene resin foamed molded product. If the amount of the fusion accelerator is too large outside the above range, blocking may occur during pre-expansion.

[0109] The fusion promoter may be of only one type, or of two or more types.

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

[0111] ≪A-2. Preferred Embodiment (2) of Recyclable Expanded Styrene-Based Resin Particles≫ One preferred embodiment (2) of the recyclable expanded styrene-based resin particles of the present invention is recyclable expanded styrene-based resin particles obtained by press-fitting and impregnating a foaming agent into recycled styrene-based resin particles (A), wherein the recycled styrene-based resin particles (A) contain 10 mg / kg to 800 mg / kg of metallic zinc element.

[0112] <A-2-1. Recycled Styrene-Based Resin Particles (A) in Embodiment (2)> The recycled styrene-based resin particles (A) in Embodiment (2) are typically recycled styrene-based resin raw material particles (a). That is, in Embodiment (2), recycled styrene-based resin raw material particles (a) are used as the recycled styrene-based resin particles (A). Regarding the recycled styrene-based resin raw material particles (a) that can be adopted as the recycled styrene-based resin particles (A) in Embodiment (2), the description of the recycled styrene-based resin raw material particles (a) in the item of <A-1-1. Recycled Styrene-Based Resin Particles (A) in Embodiment (1)> described above can be incorporated by reference.

[0113] In Embodiment (2), the recycled styrene resin particles (A) contain 10 mg / kg to 800 mg / kg of metallic zinc element. That is, in Embodiment (2), the content ratio of the metallic zinc element in the recycled styrene resin particles (A) is 10 mg / kg to 800 mg / kg, preferably 15 mg / kg to 700 mg / kg, more preferably 20 mg / kg to 600 mg / kg, still more preferably 25 mg / kg to 500 mg / kg, and particularly preferably 30 mg / kg to 450 mg / kg. In Embodiment (2), if the content ratio of the metallic zinc element in the recycled styrene resin particles (A) is within the above range, the effects of the present invention can be more manifested, and the recycled foaming styrene resin particles according to the embodiment of the present invention can exhibit a more beautiful white color with less yellowing. In Embodiment (2), if the content ratio of the metallic zinc element in the recycled styrene resin particles (A) is too small outside the above range, the molded article may appear as a dull molded article. In Embodiment (2), if the content ratio of the metallic zinc element in the recycled styrene resin particles (A) is too large outside the above range, the molded article will have a yellowish tint, may appear to have yellowing degradation, or the fusion rate between the foamed particles during molding may deteriorate, and the moldability may decrease.

[0114] In Embodiment (2), any appropriate method can be adopted to adjust the content ratio of the metallic zinc element in the recycled styrene resin particles (A) to 10 mg / kg to 800 mg / kg as long as the effects of the present invention are not impaired. Such methods include, for example, when preparing the recycled styrene resin particles (A), if necessary, using at least one selected from the group consisting of (i) a recycled styrene resin having a high content ratio of metallic zinc element (for example, exceeding 800 mg / kg) and (ii) a recycled styrene resin having a low content ratio of metallic zinc element (for example, less than 10 mg / kg) to adjust the content ratio of the metallic zinc element in the obtained recycled styrene resin particles (A) to 10 mg / kg to 800 mg / kg.

[0115] <A-2-2. Pressurization and impregnation of foaming agent in Embodiment (2)> The expandable recycled styrene resin particles in Embodiment (2) are obtained by press-fitting and impregnating a foaming agent into recycled styrene resin particles (A) that use recycled styrene resin raw material particles (a) as they are.

[0116] Typical methods for the press-fitting and impregnation of the foaming agent in Embodiment (2) include: Press-fitting and impregnation method (1): A suspension containing recycled styrene resin particles (A) (using recycled styrene resin raw material particles (a) as they are) is placed in a reactor such as an autoclave, and the foaming agent is press-fitted and impregnated. Press-fitting and impregnation method (2): Recycled styrene resin particles (A) (using recycled styrene resin raw material particles (a) as they are) are put into an extruder, the foaming agent is press-fitted and impregnated in the middle in the extruder, and at the same time as being extruded from the extruder, it is cut in water. may be mentioned.

[0117] Regarding the press-fitting and impregnation method (1), the description in the item of <A-1-2. Press-fitting and impregnation of the foaming agent in Embodiment (1)> mentioned above can be cited. However, the press-fitting temperature and impregnation temperature of the foaming agent into the recycled styrene resin particles (A) are as follows.

[0118] Regarding the injection / impregnation method (1) in the embodiment (2), the injection temperature of the blowing agent into the recycled styrene-based resin particles (A) is preferably 40°C to 150°C, more preferably 60°C to 145°C, even more preferably 80°C to 140°C, particularly preferably 100°C to 135°C, and most preferably 110°C to 130°C. The injection temperature of the blowing agent into the recycled styrene-based resin particles (A) may be changed within the above range. If the injection temperature of the blowing agent into the recycled styrene-based resin particles (A) is within the above range, for example, even if the recycled styrene-based resin particles (A) are irregularly shaped particles, it becomes easy to make them spherical, the adhesion of the particles can be reduced, and the odor peculiar to the recycled raw material can be easily removed. If the injection temperature of the blowing agent into the recycled styrene-based resin particles (A) is too low outside the above range, it may be difficult to make them spherical. If the temperature at which the blowing agent is injected into the recycled styrene-based resin particles (A) is too high and deviates from the above range, the particles may become flattened or the number of coalesced particles may increase.

[0119] Regarding the press-in / impregnation method (1) in the embodiment (2), the temperature for impregnating the recycled styrene-based resin particles (A) with the foaming agent is preferably 40°C to 150°C, more preferably 60°C to 130°C, even more preferably 80°C to 120°C, even more preferably 90°C or more and less than 110°C, particularly preferably 95°C or more and less than 110°C, and most preferably 100°C or more and less than 110°C. The temperature for impregnating the recycled styrene-based resin particles (A) with the foaming agent may be changed within the above range. If the temperature for impregnating the recycled styrene-based resin particles (A) with the foaming agent is within the above range, for example, the foaming agent is efficiently impregnated into the recycled styrene-based resin particles (A) and the foaming agent is uniformly absorbed, making it easier to control the subsequent foaming and molding, and also easier to remove the odor peculiar to the recycled raw material. If the temperature for impregnating the recycled styrene-based resin particles (A) with the blowing agent is too low outside the above range, the blowing agent may not be absorbed to the center of the recycled styrene-based resin particles (A) or only a portion of the blowing agent injected may be absorbed into the recycled styrene-based resin particles (A). If the temperature for impregnating the recycled styrene-based resin particles (A) with the blowing agent is too high outside the above range, the particles may become flattened or the number of coalesced particles may increase.

[0120] The press-in / impregnation method (2) in Embodiment (2) is a method (water cutting method) in which recycled styrene resin particles (A) (using recycled styrene resin raw material particles (a) as they are) are put into an extruder, a foaming agent is press-in / impregnated midway in the extruder, and at the same time as being extruded from the extruder, it is cut in water.

[0121] More specifically, the press-in / impregnation method (2) in Embodiment (2) supplies recycled styrene resin particles (A) (using recycled styrene resin raw material particles (a) as they are) to an extruder, heats and melts them, press-in a foaming agent from midway in the extruder, extrudes the resulting resin composition from a porous die into water, and cuts it in water simultaneously with the extrusion to obtain resin particles.

[0122] As the foaming agent, the description of the foaming agent in the item of <A-1-2. Press-in / impregnation of foaming agent> described above can be cited.

[0123] Regarding the press-in / impregnation method (2) in Embodiment (2), the press-in temperature of the foaming agent into the recycled styrene resin particles (A) is preferably 40°C to 150°C, more preferably 60°C to 130°C, still more preferably 80°C to 120°C, particularly preferably 90°C to 115°C, and most preferably 95°C to 110°C. The press-in temperature of the foaming agent into the recycled styrene resin particles (A) may be changed within the above range. If the press-in temperature of the foaming agent into the recycled styrene resin particles (A) is within the above range, for example, the foaming agent is likely to be efficiently impregnated into the recycled styrene resin particles (A), and the foaming agent is uniformly absorbed, so it becomes easier to control subsequent foaming and molding, and it also becomes easier to remove the odor peculiar to the recycled raw material. If the press-in temperature of the foaming agent into the recycled styrene resin particles (A) is too low outside the above range, there is a risk that the foaming agent will not be absorbed to the center of the recycled styrene resin particles (A). If the press-in temperature of the foaming agent into the recycled styrene resin particles (A) is too high outside the above range, there is a risk that the particles will adhere more.

[0124] Regarding the press-in / impregnation method (2) in the embodiment (2), the temperature of impregnation of the blowing agent into the recycled styrene-based resin particles (A) is preferably 40°C to 150°C, more preferably 40°C to 140°C, even more preferably 40°C to 130°C, even more preferably 40°C to 123°C, particularly preferably 40°C or more and less than 110°C, and most preferably 40°C to 105°C. The temperature of impregnation of the blowing agent into the recycled styrene-based resin particles (A) may be changed within the above range. If the temperature of impregnation of the blowing agent into the recycled styrene-based resin particles (A) is within the above range, the blowing agent is efficiently impregnated into the recycled styrene-based resin particles (A) and the blowing agent is uniformly absorbed, making it easier to control the subsequent foaming and molding, and also easier to remove the odor peculiar to the recycled raw material. If the temperature of impregnation of the blowing agent into the recycled styrene-based resin particles (A) is too low outside the above range, there is a risk that only a part of the blowing agent injected can be absorbed into the recycled styrene-based resin particles (A). If the temperature for impregnating the recycled styrene-based resin particles (A) with the blowing agent is too high and deviates from the above range, the particles may become flattened or the number of coalesced particles may increase.

[0125] When cutting in water simultaneously with extrusion, the temperature of the water is preferably 15°C to 60°C, more preferably 20°C to 50°C. If the water temperature is lower than 15°C, the die surface is cooled more intensely, the holes in the die are more likely to be blocked, and the pressure inside the die increases, which may make extrusion difficult. If the water temperature is higher than 60°C, it may be difficult to suppress foaming, and if the water temperature exceeds 80°C, the resin particles obtained by cutting may be more likely to coalesce.

[0126] The temperature of the water is preferably 100° C. to 200° C. lower than the temperature of the resin composition at the time of flowing into the die. If the temperature difference between the water temperature and the resin composition temperature is less than 100° C., the resulting resin particles may not be sufficiently cooled, making it difficult to suppress foaming, and if the temperature difference between the water temperature and the resin composition temperature exceeds 200° C., the resulting resin particles may deform due to the temperature difference between the surface and the interior of the resin particles, and may not become perfectly spherical.

[0127] In the underwater cutting method, a mold having 50 to 500 discharge holes of a multi-hole die is used, and the water pressure is preferably adjusted to 0 MPa to 2.00 MPa and the discharge amount is preferably adjusted to 50 kg / hour to 300 kg / hour. In the underwater cutting method, the water pressure corresponds to the resistance force when the resin is extruded from the die into the water, and the discharge amount corresponds to the force in the extrusion direction when the resin composition is extruded from the die into the water. Therefore, in the underwater cutting method, expandable styrene-based resin particles can be produced well by appropriately adjusting the water pressure and the discharge amount. In particular, when a recycled styrene-based resin is used as a resin component, the molecular weight tends to decrease and the fluidity increases due to the heat history that the recycled styrene-based resin received during the regeneration, and the fluidity and viscoelasticity change because the additive derived from the recycled raw material contains an arbitrary amount, and therefore strict adjustment of the water pressure and the discharge amount in the underwater cutting method is required.

[0128] The water pressure in the underwater cutting method is preferably 0.12 MPa to 1.90 MPa, more preferably 0.13 MPa to 1.85 MPa, further preferably 0.15 MPa to 1.80 MPa, and particularly preferably 0.20 MPa to 1.60 MPa.

[0129] The discharge rate in the underwater cutting method is preferably 60 kg / hour to 280 kg / hour, more preferably 80 kg / hour to 270 kg / hour, still more preferably 100 kg / hour to 260 kg / hour, and particularly preferably 120 kg / hour to 250 kg / hour.

[0130] Fig. 1 shows an example of an apparatus suitable for producing the expandable polystyrene resin particles in Embodiment (2) by the underwater cutting method of the press-fitting / impregnation method (2). This production apparatus includes a raw material supply hopper 11 for introducing the resin component (B) upstream in the resin flow direction (the direction from left to right in Fig. 1), a blowing agent supply port 12 having a high-pressure pump 13 downstream of the resin flow direction from the raw material supply hopper 11, an extruder 1 provided with a porous die 2 at the end in the resin flow direction, a cutting chamber 3 provided so as to cover the outlet of the porous die 2, in which a cutter 31 is rotatably arranged and which is configured to circulate water inside, a water tank 6 and a water pump 4 for supplying water to the cutting chamber 3, a dehydration dryer 5 for introducing the expandable polystyrene resin particles cut in the cutting chamber 3 together with water and separating the water and the expandable polystyrene resin particles, and a container 7 for storing the expandable polystyrene resin particles separated by the dehydration dryer 5.

[0131] As the extruder 1, a known extruder used in the extrusion molding of a resin composition can be used. Examples of such an extruder include a single-screw extruder, a twin-screw extruder, and a tandem extruder. The extruder 1 introduces the resin component (B) from the raw material supply hopper 11, heats and kneads it in the extruder 1, and transfers the melt-kneaded product downstream in the resin flow direction. When the melt-kneaded product reaches the blowing agent supply port 12, the blowing agent pumped by the high-pressure pump 13 is mixed with the melt-kneaded product. Thereafter, the obtained resin composition is extruded from the porous die 2 into the cutting chamber 3, comes into contact with water, and is cut by the cutter 31 in water. The cut resin composition becomes spherical particles with substantially uniform particle size and is conveyed from the cutting chamber 3 to the dehydration dryer 5 by the circulating water flow. The expandable polystyrene resin particles obtained by separating and drying from water in the dehydration dryer 5 are stored in the container 7, while the water is sent to the water tank 6.

[0132] <A-2-3. Other Components in Embodiment (2)> The recycled expandable polystyrene resin particles in Embodiment (2) may contain any appropriate other components as long as the effects of the present invention are not impaired. Such other components may be only one type or two or more types.

[0133] As for other components, the descriptions in the item of <A-1-3. Other components in Embodiment (1)> described above can be cited.

[0134] <A-2-4. Surface treatment> The recycled expandable polystyrene resin particles in Embodiment (2) may be subjected to surface treatment. As such surface treatment, the descriptions in the item of <A-1-4. Surface treatment> described above can be cited.

[0135] ≪≪B. Recycled pre-expanded polystyrene resin particles≫≫ The recycled pre-expanded polystyrene resin particles according to the embodiment of the present invention are obtained by pre-expanding the recycled expandable polystyrene resin particles according to the embodiment of the present invention.

[0136] The average cell diameter of the recycled pre-expanded polystyrene resin particles is preferably 0.01 mm to 1.10 mm, more preferably 0.01 mm to 1.00 mm, still more preferably 0.01 to 0.90 mm, particularly preferably 0.01 mm to 0.80 mm, and most preferably 0.01 mm to 0.70 mm. If the average cell diameter of the recycled pre-expanded polystyrene resin particles is within the above range, blocking during foaming and molding can be more effectively prevented. Furthermore, while suppressing the chargeability during foaming and molding, better fusion properties and surface properties can be exhibited, and a recycled polystyrene resin foam molded body with less static electricity can be molded, thus providing recycled pre-expanded polystyrene resin particles. When the average cell diameter of the recycled pre-expanded polystyrene resin particles is less than 0.01 mm, the surface may melt and shrink during molding.

[0137] Pre-expansion involves expanding the recycled expandable styrene-based resin particles to a desired bulk expansion ratio (bulk density) using water vapor or the like. The bulk expansion ratio of the recycled pre-expanded styrene-based resin particles is preferably 2 to 150 times, more preferably 2 to less than 100 times, more preferably 5 to 90 times, even more preferably 10 to 85 times, and particularly preferably 15 to 83 times. The bulk density is the reciprocal of the bulk expansion ratio. By having the bulk expansion ratio of the recycled pre-expanded styrene-based resin particles within the above range, it is possible to provide recycled pre-expanded styrene-based resin particles that can better prevent blocking during expansion and molding, and can further suppress electrostatic charge during expansion and molding while exhibiting better fusion properties and surface properties, thereby enabling the molding of a recycled styrene-based resin foam molded article with less static electricity.

[0138] In one representative embodiment, the recycled pre-expanded styrene-based resin particles can be used to form a recycled styrene-based resin foamed molding. In another embodiment, the recycled pre-expanded styrene-based resin particles can be used as they are as a cushioning material, a heat insulating material, a concrete aggregate, and the like. When the recycled pre-expanded styrene-based resin particles are used as they are, the recycled pre-expanded styrene-based resin particles can be preferably used as a filler in which a large number of recycled pre-expanded styrene-based resin particles are filled in a bag. Such recycled pre-expanded styrene-based resin particles are suitable, for example, for the core material of a cushion (foam particles filled inside the cushion).

[0139] <<C. Recycled styrene resin foam molding>> The recycled styrene-based resin foam molded product according to one embodiment of the present invention is a recycled styrene-based resin foam molded product molded from the recycled expandable styrene-based resin particles according to an embodiment of the present invention. The recycled styrene-based resin foam molded product according to another embodiment of the present invention is a recycled styrene-based resin foam molded product molded from the recycled pre-expanded styrene-based resin particles according to an embodiment of the present invention.

[0140] The recycled styrene-based resin foamed molded article typically contains recycled expandable styrene-based resin particles (hereinafter sometimes simply referred to as "expanded particles") obtained by further expanding recycled pre-expanded styrene-based resin particles.

[0141] A recycled styrene-based resin foamed molded article is typically composed of a plurality of foamed particles fused to one another.

[0142] The recycled styrene-based resin foam molded article can be typically produced by charging recycled pre-expanded styrene-based resin particles into a mold having a predetermined shape according to the purpose and performing in-mold foam molding. More specifically, in-mold foam molding includes (i) filling recycled pre-expanded styrene-based resin particles into a closed mold having a large number of small holes, (ii) heating and foaming the recycled pre-expanded styrene-based resin particles with a heat medium (e.g., pressurized steam, etc.) to obtain foamed particles, and (iii) filling the voids between the foamed particles by the heating and foaming, and fusing the foamed particles together to integrate them. The density of the recycled styrene-based resin foam molded article can be appropriately set according to the purpose. The density of the recycled styrene-based resin foam molded article can be adjusted, for example, by previously adjusting the bulk expansion ratio of the pre-expanded styrene-based resin particles filled in the mold, or by adjusting the amount of recycled pre-expanded styrene-based resin particles filled in the mold.

[0143] The heat-foaming temperature (substantially the temperature of the heat transfer medium) is preferably 90°C to 150°C, more preferably 110°C to 130°C. The heat-foaming time is preferably 5 seconds to 50 seconds, more preferably 10 seconds to 50 seconds. The molding vapor pressure of the heat-foaming (gauge pressure of the heat transfer medium blowing in) is preferably 0.04 MPa to 0.1 MPa, more preferably 0.06 MPa to 0.08 MPa. If the heat-foaming is performed under such conditions, the expanded particles can be well fused to each other.

[0144] If necessary, the recycled pre-expanded styrene resin particles may be aged before molding into a recycled styrene resin foamed molded article. The aging temperature of the recycled pre-expanded styrene resin particles is preferably 20°C to 60°C. If the aging temperature is too low, an excessively long aging time may be required. If the aging temperature is too high, the blowing agent in the recycled pre-expanded styrene resin particles may dissipate, resulting in a decrease in moldability.

[0145] The expansion ratio of the expanded beads in the recycled styrene-based resin foamed molded product is preferably 2 times or more and less than 110 times, more preferably 5 times to 90 times, further preferably 10 times to 85 times, and particularly preferably 15 times to 80 times.

[0146] The recycled styrene-based resin foam molded product according to the embodiment of the present invention is lightweight and has excellent heat insulation properties and mechanical strength, and is therefore suitable for use as wall insulation material, floor insulation material, roof insulation material, automobile insulation material, heat insulation material for hot water tanks, heat insulation material for piping, heat insulation material for solar systems, heat insulation material for water heaters, containers for food and industrial products (e.g., food containers such as fish boxes, return boxes), cushioning material, floats, blocks, packaging material for fish and agricultural products, etc., molded bodies for embankments, core material for tatami mats, core material for cushions, aggregate for concrete, etc. EXAMPLES

[0147] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring and evaluating each property are as follows.

[0148] <L * +|a * |+(|b * |) 3 Color value calculated by A Konica Minolta Sensing Co., Ltd. color difference meter (product name "CR-400") and a standard white plate calibration plate (Y: 84.6, x: 0.318, y: 0.3224) were used for standard alignment. * Value (lightness: white>black), a * Value (hue: red>green), b *Specifically, about 2 g of the particles to be measured was filled (up to the brim) in a measurement container (powder cell manufactured by Konica Minolta Sensing Co., Ltd., product name "CR-A50"), and the filled part was measured with a measurement diameter of φ8 mm, L * Value, a * Value, b * The values ​​were measured. From the obtained value, L * +|a * |+(|b * |) 3 The color value was calculated according to the following formula.

[0149] <Analysis of metallic zinc element content> The amount of metallic zinc contained in the recycled styrene-based resin raw material particles or recycled styrene-based resin particles was measured as follows. Approximately 0.5g of a precisely weighed measurement sample was heated at 475°C for 3 hours and incinerated. The resulting ash was mixed with 2mL of concentrated hydrochloric acid (Ultrapur-100, ultra-high purity reagent, manufactured by Kanto Chemical Co., Ltd.). The insoluble matter in the mixture was filtered through ADAVANTEC No. 7 filter paper, and the filtrate was diluted to 50mL with pure water to prepare a test solution. The metallic zinc element concentration of the test solution was measured under the following conditions. The metallic zinc element concentration was determined from a calibration curve. The amount of metallic zinc element in the sample was calculated from the following formula. The lower limit of measurement was 1mg / kg. Amount of metallic zinc (mg / kg) = concentration of metallic zinc (μg / mL) × 50 (mL) ÷ mass of measured sample (g) (ICP measurement conditions) Measurement equipment: Shimadzu Corporation's "ICPE-9000" multi-type ICP optical emission spectrometer Measured element = Zn (202.548nm) Observation direction = Axial 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 Calibration curve standard solution = SPEX Corporation "XSTC-13" general-purpose mixed standard solution 31 elements mixed (base 5% HNO3): approx. 10 mg / L each, SPEX Corporation "XSTC-8" general-purpose mixed standard solution 13 elements mixed (base H2O / trace HF): approx. 10 mg / L each The standard solution for the calibration curve was diluted with pure water to prepare standard solutions of 5 ppm, 2.5 ppm, 1 ppm, and 0.25 ppm for measurement. (ashing conditions) Measurement equipment: Yamato Scientific Co., Ltd. "Muffle furnace FP-410" Ashing conditions: 475℃ x 3hr (sample weight: approx. 0.5g)

[0150] <Aesthetic Evaluation> The aesthetics were evaluated by a sensory test conducted by five people. 〇: Three or more people feel that it is a "warm color" △: 3 or more people feel it is "dull" ×: 3 or more people felt that the product was yellowing

[0151] [Production Example 1]: Production of recycled styrene-based resin raw material particles (a) Pellets recovered from used fish boxes and, if necessary, zinc stearate were fed into a single-screw extruder, heated and melted at 200°C, extruded through a die, and cut underwater to give an average particle size of 0.75 mm (approximately spherical), to produce various recycled styrene-based resin raw material particles (a) containing a specified amount of metallic zinc element. The recycled styrene-based resin raw material particles (a) produced were the following 12 types. Recycled styrene resin raw material particles (a10): Metallic zinc content = 10 mg / kg Recycled styrene resin raw material particles (a25): Metallic zinc content = 25 mg / kg Recycled styrene resin raw material particles (a60): Metallic zinc content = 60mg / kg Recycled styrene resin raw material particles (a85): Metallic zinc content = 85mg / kg Recycled styrene resin raw material particles (a120): Metallic zinc content = 120mg / kg Recycled styrene resin raw material particles (a140): Metallic zinc content = 140mg / kg Recycled styrene resin raw material particles (a200): Metallic zinc content = 200mg / kg Recycled styrene resin raw material particles (a450): Metallic zinc content = 450mg / kg Recycled styrene resin raw material particles (a650): Metallic zinc content = 650mg / kg Recycled styrene resin raw material particles (a750): Metallic zinc content = 750mg / kg Recycled styrene resin raw material particles (a5): Metallic zinc content = 5 mg / kg Recycled styrene resin raw material particles (a805): Metallic zinc content = 805mg / kg

[0152] [Example 1] <Preparation of Recycled Expandable Styrenic Resin Particles (1)> A 100-liter reactor equipped with a stirrer was charged with 36 kg of water, 3.5 g of sodium dodecylbenzenesulfonate, and 150 g of magnesium pyrophosphate, and then 12.6 kg of the recycled styrene-based resin raw material particles (a10) obtained in Production Example 1 as recycled styrene-based resin raw material particles (a) was added. The mixture was stirred at 150 rpm to form a suspension, thereby preparing suspension (1). Separately, 2.3 kg of styrene monomer in which 125 g of benzoyl peroxide (75% purity) as a polymerization initiator and 20 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved was added to a dispersion of 2.5 kg of water and 0.8 g of sodium dodecylbenzenesulfonate, and the mixture was emulsified by stirring with a homomixer to prepare emulsion (1). The above suspension (1) in a 100-liter reactor equipped with a stirrer was kept at 75°C, and the above emulsion (1) was added. Thereafter, the temperature was kept at 75°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed in the recycled styrene-based resin raw material particles (a), and immediately after that, 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. Thereafter, the temperature was increased to 125° C. over 30 minutes, and the temperature was maintained at 125° C. for 30 minutes, and then the temperature was cooled to 60° C. over 1 hour. In this way, recycled styrene-based resin particles (A1) were prepared in the reaction vessel. Next, 189 g of dicumyl peroxide and 35 g of ethylene bisstearic acid amide were added to a dispersion of 3.5 kg of water, 1.5 g of sodium dodecylbenzenesulfonate, and 20 g of magnesium pyrophosphate, and the mixture was emulsified by stirring with a homomixer to prepare emulsion (2). This emulsion (2) was added to the reactor cooled to 60°C. 10 minutes after this addition, 756 g of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) was added. After the addition, stirring was continued at 60°C for 30 minutes. Next, the temperature was raised to 100°C, and 3200 g of pentane (isopentane / normal pentane = 20% by mass / 80% by mass) was injected as a blowing agent, and the blowing agent was slowly impregnated by maintaining the state for 5.5 hours. After that, the temperature inside the reactor was cooled to 30°C. Thereafter, the contents were removed from the reactor, dehydrated, dried and classified to obtain regenerated expandable styrene-based resin particles (1).

[0153] <Surface treatment of recycled expandable styrene resin particles (1)> The obtained recycled expandable styrene-based resin particles (1) (40 kg), 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 tumbler mixer and stirred for 30 minutes to perform a surface treatment, thereby obtaining surface-treated recycled expandable styrene-based resin particles (1').

[0154] <Preparation of Recycled Pre-Expanded Styrenic Resin Particles (1)> The obtained surface-treated recycled expandable styrene resin particles (1') were stored in a refrigerated box at 15°C for 20 days, then placed in a cylindrical batch type pressure foaming machine with a volume of 340 liters and heated with steam for 2 minutes to obtain recycled pre-expanded styrene resin particles (1). The bulk density of the recycled pre-expanded styrene resin particles (1) was 0.02 g / cm. 3 The bulk expansion ratio was 50 times.

[0155] <Preparation of Recycled Styrene-Based Resin Foam Molding (1)> A molding machine having a mold with a cavity of 400 mm height x 500 mm width x 300 mm depth was used. The recycled pre-expanded styrene resin particles (1) were left for 24 hours in a room temperature atmosphere, then filled into the cavity of the mold of the above molding machine, heated at a vapor pressure of 0.04 MPa (gauge pressure) for 40 seconds, and then cooled until the pressure inside the mold became -0.002 MPa. The mold was then released from the mold to obtain a plate-shaped recycled styrene resin foamed molded product (1) corresponding to the mold. The density of the recycled styrene resin foamed molded product (1) was 0.02 g / cm. 3 The expansion ratio was 50. Thereafter, this recycled styrene-based resin foamed molded product (1) was stored in a drying room at 50° C. for one day. The results are shown in Table 1.

[0156] [Examples 2 to 10] The same procedure as in Example 1 was repeated, except that the recycled styrene-based resin raw material particles shown in Table 1 were used as the recycled styrene-based resin raw material particles (a), to obtain recycled styrene-based resin particles (A2) to (A10), recycled expandable styrene-based resin particles (2) to (10), recycled pre-expanded styrene-based resin particles (2) to (10), and recycled styrene-based resin foamed molded articles (2) to (10). The results are shown in Table 1.

[0157] [Comparative Examples 1 to 2] The same procedure as in Example 1 was repeated, except that the recycled styrene-based resin raw material particles shown in Table 1 were used as the recycled styrene-based resin raw material particles (a), to obtain recycled styrene-based resin particles (AC1) to (AC2), recycled expandable styrene-based resin particles (C1) to (C2), recycled pre-expanded styrene-based resin particles (C1) to (C2), and recycled styrene-based resin foamed moldings (C1) to (C2). The results are shown in Table 1.

[0158] [Example 11] <Preparation of Recycled Expandable Styrenic Resin Particles (11)> A 100-liter reactor equipped with a stirrer was charged with 42 kg of water, 5.7 g of sodium dodecylbenzenesulfonate, and 295 g of magnesium pyrophosphate, and then 42 kg of the recycled styrene-based resin raw material particles (a10) obtained in Production Example 1 as recycled styrene-based resin particles (A) was added thereto. The mixture was stirred at 150 rpm to form a suspension, thereby preparing suspension (3). The above suspension (3) in a 100-liter reactor equipped with a stirrer was kept at 60° C., and 189 g of dicumyl peroxide and 34 g of ethylene bisstearic acid amide were added. 10 minutes after the addition, 756 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. After that, the temperature was raised to 120°C over 60 minutes, and then 4200 g of pentane (isopentane / normal pentane = 20% by mass / 80% by mass) was pressed in as a blowing agent, and the temperature was raised to 108°C over 10 minutes, and the state was maintained for 5 hours to slowly impregnate the blowing agent. 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 recycled expandable styrene-based resin particles (11).

[0159] <Surface treatment of recycled expandable styrene resin particles (11)> The obtained recycled expandable styrene-based resin particles (11) (40 kg), 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 tumbler mixer and stirred for 30 minutes to perform a surface treatment, thereby obtaining surface-treated recycled expandable styrene-based resin particles (11').

[0160] <Preparation of Recycled Pre-Expanded Styrenic Resin Particles (11)> The obtained surface-treated recycled expandable styrene resin particles (11') were stored in a refrigerated box at 15°C for 20 days, and then placed in a cylindrical batch type pressure foaming machine with a volume of 340 liters and heated with steam for 2 minutes to obtain recycled pre-expanded styrene resin particles (11). The bulk density of the recycled pre-expanded styrene resin particles (11) was 0.02 g / cm. 3 The bulk expansion ratio was 50 times.

[0161] <Preparation of Recycled Styrene-Based Resin Foam Molded Body (11)> A molding machine having a mold with a cavity of 400 mm height x 500 mm width x 300 mm depth was used. The recycled pre-expanded styrene resin particles (11) were left for 24 hours in a room temperature atmosphere, then filled into the cavity of the mold of the above molding machine, heated at a vapor pressure of 0.04 MPa (gauge pressure) for 40 seconds, and then cooled until the pressure inside the mold became -0.002 MPa. The mold was then released from the mold to obtain a plate-shaped recycled styrene resin foamed molded product (11) corresponding to the mold. The density of the recycled styrene resin foamed molded product (11) was 0.02 g / cm. 3 The expansion ratio was 50. Thereafter, this recycled styrene-based resin foamed molded product (11) was stored in a drying room at 50° C. for one day. The results are shown in Table 2.

[0162] [Examples 12 to 20] The same procedure as in Example 11 was carried out except that the recycled styrene-based resin raw material particles shown in Table 2 were used as the recycled styrene-based resin particles (A), to obtain recycled expandable styrene-based resin particles (12) to (20), recycled pre-expanded styrene-based resin particles (12) to (20), and recycled styrene-based resin foamed molded articles (12) to (20). The results are shown in Table 2.

[0163] [Comparative Examples 3 to 4] The same procedure as in Example 11 was repeated to produce recycled expandable styrene-based resin particles (C3) to (C4), recycled pre-expanded styrene-based resin particles (C3) to (C4), and recycled styrene-based resin foamed moldings (C3) to (C4), except that the recycled styrene-based resin raw material particles shown in Table 2 were used as the recycled styrene-based resin particles (A). The results are shown in Table 2.

[0164] [Table 1]

[0165] [Table 2] [Industrial Applicability]

[0166] The recycled expandable styrene resin particles, recycled pre-expanded styrene resin particles, and recycled styrene resin foam molded bodies according to the embodiment of the present invention are preferably used as insulation materials for houses and automobiles, heat-retaining materials for building materials, 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 bodies according to the embodiment of the present invention are preferably used as wall insulation materials, floor insulation materials, roof insulation materials, automobile insulation materials, hot water tank insulation materials, piping insulation materials, solar system insulation materials, water heater insulation materials, containers for food and industrial products (e.g., food containers such as fish boxes, commuter boxes), cushioning materials, floats, blocks, packaging materials for fish and agricultural products, embankment materials (embankment blocks, etc.), tatami mat core materials, cushion core materials, concrete aggregates, etc. [Explanation of symbols]

[0167] 1. Extruder 2 Multi-hole die 3 Cutting Room 4. Water Pump 5 Dehydration dryer 6. Aquarium 7 containers 11 Raw material supply hopper 12 Blowing agent supply port 13 High pressure pump 31 Cutter

Claims

1. Regenerated expandable styrene-based resin particles obtained by pressurizing and impregnating a blowing agent into recycled styrene-based resin particles (A), L ＊ a ＊ b ＊ In the color system, L ＊ + | a ＊ |+(|b ＊ |) 3 The color value calculated by is 20 to 800. Recycled expandable styrene resin particles.

2. The recycled expandable styrene-based resin particles according to claim 1, wherein the recycled styrene-based resin particles (A) are obtained by nuclear polymerization of a styrene-based monomer using recycled styrene-based resin raw material particles (a) containing 10 mg / kg to 800 mg / kg of metallic zinc element as a nucleus.

3. The recycled expandable styrene-based resin particles according to claim 1, wherein the recycled styrene-based resin particles (A) contain 10 mg / kg to 800 mg / kg of metallic zinc element.

4. A recycled pre-expanded styrene-based resin particle obtained by pre-expanding the recycled expandable styrene-based resin particle according to any one of claims 1 to 3, The bulk expansion ratio of the pre-expanded foam is 2 to 150 times. Recycled pre-expanded styrene-based resin particles.

5. A recycled styrene-based resin foamed molded article produced from the recycled pre-expanded styrene-based resin particles according to claim 4.

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