Recycled foamable styrene resin particles, recycled styrene resin foam particles, and recycled styrene resin foam molded articles

Abstract

This invention provides recycled foamed styrene resin particles that contribute significantly to the environment, improve the strength of the recycled foamed styrene resin particles, and are suitable for reducing dents. It also provides recycled foamed styrene resin particles obtained from such recycled foamed styrene resin particles. Furthermore, it provides a recycled foamed molded article formed from such recycled foamed styrene resin particles. [Solution] The recycled foamable styrene resin particles according to the embodiment of the present invention are recycled foamable styrene resin particles obtained by pressurizing and impregnating recycled styrene resin particles (A) with a foaming agent, wherein the bulk density of the foamed recycled styrene resin particles obtained by foaming the recycled foamable styrene resin particles is 0.0080 g / cm³. 3 ~0.20 g / cm³ 3 Furthermore, the volume retention rate measured by a compression test of the recycled styrene-based resin foam particles is 50% or more.

Description

[Technical Field]

[0001] The present invention relates to recycled foamable styrene-based resin particles, recycled styrene-based resin foam particles, and recycled styrene-based resin foam molded articles. [Background technology]

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

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

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

[0005] A method for obtaining recycled foamable styrene-based resin particles has been reported by impregnating recycled resin pellets, molded from recovered styrene-based resin foam molded products, with a foaming agent, either by impregnation or by injection followed by impregnation (Patent Documents 1-4). Furthermore, a method for obtaining recycled foamable styrene-based resin particles has been reported by adding styrene monomers to recycled resin pellets, molded from recovered styrene-based resin foam molded products, performing nuclear polymerization, and then impregnating or by injection followed by impregnation with a foaming agent (Patent Documents 5-9).

[0006] However, conventional recycled foamed styrene resin particles have a problem in that, due to foreign matter in the recovered raw materials, kegging (a state in which the foamed particles melt and collapse or shrink) is likely to occur on the surface of the foamed molded product during molding. In addition, conventional recycled foamed styrene resin particles have a problem in that they are particularly susceptible to heat generated during foaming and molding, and tend to shrink, compared to foamed styrene resin particles that do not use recovered raw materials. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 3044942 [Patent Document 2] Patent No. 4234832 [Patent Document 3] Patent No. 4261676 [Patent Document 4] Patent No. 6788428 [Patent Document 5] Patent No. 4052193 [Patent Document 6] Japanese Patent Publication No. 2006-160905 [Patent Document 7] Patent No. 4912567 [Patent Document 8] Patent No. 5128246 [Patent Document 9] Japanese Patent Publication No. 2022-153315 [Overview of the Initiative] Problems to be Solved by the Invention

[0008] The present invention has been made to solve the above conventional problems, and its main object is to provide recycled expandable styrene-based resin particles with high environmental contribution, which improve the strength of recycled styrene-based resin expanded particles and are suitable for reducing dents. It also aims to provide recycled styrene-based resin expanded particles obtained from such recycled expandable styrene-based resin particles. Furthermore, it aims to provide a recycled styrene-based resin expanded molded article molded from such recycled styrene-based resin expanded particles. Means for Solving the Problems

[0009] [1] The recycled expandable styrene-based resin particles according to an embodiment of the present invention are recycled expandable styrene-based resin particles obtained by press-fitting and impregnating a blowing agent into recycled styrene-based resin particles (A), The bulk density of the recycled styrene-based resin expanded particles obtained by expanding the recycled expandable styrene-based resin particles is 0.0080 g / cm 3 to 0.20 g / cm 3 , and The volume retention rate of the recycled styrene-based resin expanded particles measured by the following compression test is 50% or more. (Compression Test) For the recycled styrene-based resin expanded particles of volume V1 filled in a container with an inner diameter of 50 mm, compression at a test speed of 10 mm / min, a maximum load point of 267 N, and a minimum load point of 1 N is repeated 100 times. Thereafter, the recycled styrene-based resin expanded particles are taken out of the container and allowed to stand for 24 hours. The volume V2 of the recycled styrene-based resin expanded particles after standing is measured. From the above V1 and V2, ΔV is calculated using formula (1). The average value of ΔV from three runs is taken as the volume retention rate. ΔV [%] = (V2 / V1) × 100 ··· (1) [2] In the recycled foamable styrene resin particles described in [1] above, the recycled styrene resin particles (A) are obtained by nuclear polymerization of a monomer composition (C) containing a styrene monomer, an acrylic acid ester monomer, and a polyfunctional vinyl monomer, using recycled styrene resin raw material particles (a) as a core, in the presence of a polymerization initiator, wherein the polymerization initiator may include at least one selected from the group consisting of peroxyester polymerization initiators and diacyl peroxide polymerization initiators. [3] In the recycled foamable styrene resin particles described in [2] above, the content of the acrylic acid ester monomer relative to the total amount of the recycled styrene resin raw material particles (a), the styrene monomer, and the acrylic acid ester monomer in the nuclear polymerization may be 0.1% to 5% by mass. [4] The recycled foamable styrene resin particles described in any one of [1] to [3] above may have a weight-average molecular weight of 280,000 to 1,100,000. [5] The recycled styrene-based resin foam particles according to the embodiment of the present invention are obtained by foaming the recycled foamable styrene-based resin particles described in any one of [1] to [4] above. [6] A recycled styrene-based resin foam molded article according to an embodiment of the present invention is molded from recycled styrene-based resin foam particles described in [5] above. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide recycled foamed styrene resin particles that have a high contribution to the environment, improve the strength of the recycled foamed styrene resin particles, and are suitable for reducing dents. Furthermore, it is possible to provide recycled foamed styrene resin particles obtained from such recycled foamed styrene resin particles. Moreover, it is possible to provide a recycled foamed molded article formed from such recycled foamed styrene resin particles. [Modes for carrying out the invention]

[0011] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

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

[0013] ≪≪1. Recycled foamed styrene resin particles≫≫ The recycled foamed styrene resin particles according to the embodiments of the present invention have a particle shape as a whole. The average particle diameter of the recycled foamed styrene resin particles is preferably 0.40 mm to 2.0 mm, and more preferably 0.6 mm to 1.8 mm. The average particle diameter can be measured in accordance with JIS Z 8815. Specifically, the average particle diameter is the value measured as the particle size of 50% of the cumulative value from the particle size distribution obtained by the sieving test of JIS Z 8815.

[0014] The shape of the recycled foamed styrene resin particles according to the embodiments of the present invention can be any appropriate shape, as long as it does not impair the effects of the present invention. Specific examples of such shapes include, for example, spherical, substantially spherical, and ellipsoidal (egg-shaped). In terms of exhibiting the effects of the present invention, the shape of the recycled foamed styrene resin particles according to the embodiments of the present invention is preferably spherical, substantially spherical, and more preferably spherical. However, in practice, it is difficult to distinguish between spherical and substantially spherical shapes; therefore, in this specification, both are collectively referred to as spherical.

[0015] The recycled foamable styrene resin particles according to the embodiment of the present invention are recycled foamable styrene resin particles obtained by pressurizing and impregnating recycled styrene resin particles (A) with a foaming agent, wherein the bulk density of the foamed recycled styrene resin particles obtained by foaming the recycled styrene resin particles (A) is 0.0080 g / cm³. 3 ~0.20 g / cm³ 3 Furthermore, the volume retention rate of the recycled styrene-based resin foam particles, as measured by the following compression test, is 50% or more. (Compression test) The recycled styrene foam particles, with a volume V1, filled in a container with an inner diameter of 50 mm, are compressed 100 times at a test speed of 10 mm / min, with an upper load limit of 267 N and a lower load limit of 1 N. After that, the recycled styrene foam particles are removed from the container and left to stand for 24 hours. The volume V2 of the recycled styrene foam particles after standing is measured. ΔV is calculated from V1 and V2 using equation (1). ΔV[%]=(V2 / V1)×100 ···(1) The above procedure is repeated three times, and the average value of the ΔV obtained over the three times is taken as the volume retention rate of the recycled styrene-based resin foam particles.

[0016] The volume retention rate of the recycled styrene-based resin foam particles is preferably 60% or more, and more preferably 80% or more. The upper limit of the volume retention rate of the recycled styrene-based resin foam particles is not particularly limited, and is, for example, 100%.

[0017] With the above configuration, the recycled foamed styrene-based resin particles according to the embodiment of the present invention can have their strength improved, thereby enabling the realization of recycled foamed styrene-based resin particles and molded articles thereof that are less prone to denting.

[0018] The weight-average molecular weight of the recycled foamed styrene resin particles is, for example, 250,000 to 1,200,000, preferably 280,000 to 1,100,000, more preferably 250,000 to 1,000,000, even more preferably 300,000 to 1,000,000, particularly preferably 350,000 to 1,000,000, and most preferably 350,000 to 900,000. The weight-average molecular weight of the recycled foamed styrene resin particles can be measured by gel permeation chromatography (GPC). Typically, the weight-average molecular weight of the recycled foamed styrene resin particles is substantially the same as the weight-average molecular weight of recycled styrene resin particles (A).

[0019] The recycled foamed styrene resin particles according to the embodiments of the present invention have a high environmental impact. The recycled foamed styrene resin particles in Embodiment (1) above have a recycling rate of preferably 10% or more, more preferably 20% or more, even more preferably 25% or more, and particularly preferably 30% or more. The recycling rate is the proportion of recovered styrene resin in the styrene resin contained in the recycled foamed styrene resin particles.

[0020] <1-1. Recycled styrene resin particles (A)> The recycled foamable styrene resin particles of the present invention are obtained by injecting and impregnating recycled styrene resin particles (A) with a foaming agent.

[0021] The weight-average molecular weight of the recycled styrene resin particles (A) can be any appropriate weight-average molecular weight as long as it does not impair the effects of the present invention. For example, such a weight-average molecular weight is 250,000 to 1,200,000, preferably 280,000 to 1,100,000, more preferably 250,000 to 1,000,000, even more preferably 300,000 to 1,000,000, particularly preferably 350,000 to 1,000,000, and most preferably 350,000 to 900,000. Typically, the weight-average molecular weight of the recycled styrene resin particles (A) is substantially the same as the weight-average molecular weight of the recycled foamable styrene resin particles.

[0022] Recycled styrene resin particles (A) are typically obtained by nuclear polymerization of a monomer composition (C) containing a styrene monomer, an acrylic acid ester monomer, and a polyfunctional vinyl monomer, using recycled styrene resin raw material particles (a) as a core, in the presence of a polymerization initiator.

[0023] The recycled styrene-based resin raw material particles (a) may consist of only one type or two or more types.

[0024] As the material for the recycled styrene resin raw material particles (a), any suitable recycled styrene resin can be used, as long as it does not impair the effects of the present invention. Examples of such recycled styrene resins include expanded polystyrene (molded products such as fish boxes and agricultural product boxes, cushioning materials, block molded products, etc.), expanded polystyrene sheets (tray containers, sheet scraps, etc.), recycled plastic materials used in home appliances, packaging containers, cushion beads, and OPS (biaxially oriented polystyrene sheets). The recycled styrene resin raw material particles (a) may contain one type of recycled styrene resin from the above materials, or may contain two or more types of recycled styrene resins.

[0025] As the recycled styrene resin material for the recycled styrene resin raw material particles (a), recycled expanded polystyrene made from polystyrene resin containing acrylic acid ester may be used, to the extent that the effects of the present invention are not impaired. In other words, the recycled styrene resin raw material particles (a) may contain acrylic acid ester.

[0026] The recycled styrene-based resin raw material particles (a) may contain any other suitable recycled resins other than recycled styrene-based resins, as long as the effects of the present invention are not impaired. Examples of such other recycled resins include recycled resins of AS resin, ABS resin, HIPS (high-impact polystyrene); polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polycarbonate (PC); polyamide resins such as nylon (PA); and polyolefin resins such as polyethylene (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and high-density polyethylene (HDPE)), polypropylene (PP), and EVA (ethylene-vinyl acetate copolymer). There may be only one type of other resin, or two or more types. In this specification, recycled resins of AS resin, recycled resins of ABS resin, and recycled resins of HIPS (high-impact polystyrene) are not included in the category of recycled styrene-based resins.

[0027] As recycled styrene-based resin raw material particles (a), molded products made from the product names "Epsurem" or "Esrenbeads RNW" manufactured by Sekisui Chemical Co., Ltd. may be used.

[0028] As recycled styrene resin raw material particles (a), a pulverized product obtained by heating and / or reducing the volume of used foamed styrene resin may be used. The recycled styrene resin raw material particles may be pellets formed by extruding this pulverized product, or these pellets may be further pulverized. Alternatively, it may be recovered by reducing the volume using a solvent such as limonene.

[0029] The recycled styrene-based resin raw material particles (a) are preferably pellets obtained by a melt extrusion method. A typical melt extrusion method involves supplying crushed used styrene-based resin, ingots, or foamed particles to a resin supply device, melting them in the resin supply device, extruding them through small holes in a die attached to the tip of the resin supply device, and then cooling them to obtain pellets.

[0030] The pellets obtained by the melt extrusion method described above are preferably at least one selected from: extruded strand pellets obtained by extruding spent expanded styrene resin with an extruder and performing strand cutting; underwater cut pellets obtained by an underwater cut method in which spent expanded styrene resin is extruded with an extruder and simultaneously cut underwater; and hot cut pellets obtained by a hot cut method in which spent expanded styrene resin particles are cut and cooled immediately after coming out of the die of the extruder.

[0031] As recycled styrene-based resin raw material particles (a), pellets obtained by the above-described melt extrusion method may be used as is, or they may be made into so-called "mini-pellets" by melt extrusion or other methods to obtain smaller pellets.

[0032] The recycled styrene resin raw material particles (a) may be a shrunk or molten product of expanded styrene resin obtained by coarsely crushing used expanded styrene resin to an appropriate size as needed, and then performing processes such as thermal shrinkage, shrinkage due to bubble bursting by compression, shrinkage due to frictional heat, or melting.

[0033] Examples of used expanded polystyrene resins include molded products made by molding expanded polystyrene resin using a mold, and products made by heat-foaming these products.

[0034] The recycled styrene-based resin raw material particles (a) may contain finely powdered inorganic and / or organic lubricants. These can typically function as foam regulators.

[0035] Examples of finely powdered inorganic materials include talc, calcium carbonate, and silica. Here, talc typically refers to a mixture mainly composed of silicon dioxide and magnesium oxide, with trace amounts of aluminum oxide, iron oxide, etc.

[0036] The average particle size of the finely powdered inorganic material is preferably 100 μm or less, and more preferably 30 μm or less.

[0037] The content of finely powdered inorganic matter is preferably 0.1% to 5% by mass, and more preferably 0.5% to 2% by mass, relative to the recycled styrene-based resin raw material particles (a). If the content of finely powdered inorganic matter relative to the recycled styrene-based resin raw material particles (a) is less than 0.1% by mass, the function as a foam regulator may not be exhibited. If the content of finely powdered inorganic matter relative to the recycled styrene-based resin raw material particles (a) exceeds 5% by mass, the bubble size of the recycled styrene-based resin foam particles becomes extremely small, and the foam particles may melt during molding, potentially degrading moldability and the appearance of the molded product.

[0038] Examples of organic lubricants include liquid paraffin; polyethylene glycol; silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane; higher fatty acid bisatomids such as methylenebisstearamide, ethylenebisstearamide, and ethylenebisoleamide; and metal salts of higher fatty acids such as zinc stearate, magnesium stearate, and zinc oleate.

[0039] The content of the organic lubricant is preferably 0.01% to 2.0% by mass, more preferably 0.02% to 1.8% by mass, and in some cases even more preferably 0.02% to 0.2% by mass, and particularly preferably 0.02% to 0.1% by mass, relative to the recycled styrene resin raw material particles (a). If the content of the organic lubricant relative to the recycled styrene resin raw material particles (a) exceeds 2.0% by mass, the bubble size of the recycled styrene resin foam particles becomes extremely small, which may cause the foam particles to melt during molding, potentially degrading the moldability and appearance of the molded product.

[0040] A specific method for incorporating finely powdered inorganic and / or organic lubricants into recycled styrene-based resin raw material particles (a) is, for example, a method of kneading the finely powdered inorganic and / or organic lubricants during extrusion molding. In this case, preferably, the pulverized material and the foam regulator are mixed beforehand before extrusion molding. The method of mixing the pulverized material and the foam regulator can be any suitable method as long as it does not impair the effects of the present invention. Examples of such methods include mixing using a mixer such as a tumbler, ribbon blender, V-blender, Henschel mixer, or Readygay mixer.

[0041] The recycled styrene-based resin raw material particles (a) are preferably thermally melted for the purpose of adjusting their specific gravity. In this step, the specific gravity of the recycled styrene-based resin raw material particles (a) is preferably adjusted to 0.6 or higher, and more preferably to 0.9 or higher. If the specific gravity of the recycled styrene-based resin raw material particles (a) is less than 0.6, the dispersion of the recycled styrene-based resin raw material particles (a) is unstable, which may lead to the generation of excessive particles during the subsequent polymerization step and a decrease in yield. The thermal melting of the recycled styrene-based resin raw material particles (a) can be carried out by any suitable method that does not impair the effects of the present invention. Examples of such methods include using an extruder or a hot roll. It is preferable that the thermal melting is followed by cooling and solidification in a state where no strain remains in the obtained resin, or where the strain is small. If strain remains in the resin particles, the strain will be relieved in the subsequent step, causing shrinkage in the stretching direction, and the resulting recycled foamable styrene-based resin particles may not be spherical but flattened. Therefore, it is preferable to perform thermal melting without stretching using an extruder. If thermal melting is performed in a stretched state, there is a risk that strain will remain in the stretched resin obtained after cooling and solidification. However, even if strain remains in the resin due to thermal melting, the strain can be alleviated by curing it at a temperature above the resin's softening point for a certain period of time.

[0042] When obtaining recycled styrene-based resin raw material particles (a), any type of pulverizer can be used for grinding, as long as it does not impair the effects of the present invention. For example, a pulverizer for plastics can be used, and a pulverizer for polystyrene is preferred.

[0043] The recycled styrene-based resin raw material particles (a) can be sieved as needed and then subjected to melting again using an extruder or the like.

[0044] The average particle diameter of the recycled styrene-based resin raw material particles (a) is preferably 0.2 mm to 3.0 mm, more preferably 0.3 mm to 2.5 mm, even more preferably 0.4 mm to 2.0 mm, and particularly preferably 0.5 mm to 1.7 mm. If the average particle diameter of the recycled styrene-based resin raw material particles (a) exceeds 3 mm, the resulting recycled foamed styrene-based resin particles may not be spherical. If the average particle diameter of the recycled styrene-based resin raw material particles (a) is less than 0.2 mm, the resulting recycled foamed styrene-based resin particles may have an average particle diameter that is too small.

[0045] The L (long side) / D (short side) ratio of the recycled styrene-based resin raw material particles (a) is preferably 1.0 to 6.0, more preferably 1.0 to 5.0, even more preferably 1.0 to 4.0, particularly preferably 1.0 to 3.0, and most preferably 1.0 to 2.5. If the L (long side) / D (short side) ratio of the recycled styrene-based resin raw material particles (a) falls outside the above range, the resulting recycled foamable styrene-based resin particles may not be spherical.

[0046] It is preferable that the recycled styrene-based resin raw material particles (a) contain less than 1% by mass of particles with an average particle diameter of 200 μm or less. If the recycled styrene-based resin raw material particles (a) contain 1% or more by mass of particles with an average particle diameter of 200 μm or less, the appearance of the recycled foamed styrene-based resin particles obtained using them may deteriorate.

[0047] The weight-average molecular weight of the recycled styrene-based resin raw material particles (a) is preferably 100,000 to 450,000, and more preferably 100,000 to 300,000. By satisfying the above numerical range for the weight-average molecular weight of the recycled styrene-based resin raw material particles (a), the strength can be further improved.

[0048] Recycled styrene resin particles (A) are typically obtained by polymerizing a monomer composition (C) containing a styrene monomer, an acrylic acid ester monomer, and a polyfunctional vinyl monomer, using recycled styrene resin raw material particles (a) as a core.

[0049] The styrene monomer may be one type or two or more types.

[0050] The styrene monomer includes styrene or a styrene derivative. Examples of styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. The styrene monomer may be one type or two or more types. The styrene monomer preferably contains at least styrene. The styrene content relative to the total amount of the styrene monomer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0051] The content of styrene monomers in monomer composition (C) is preferably 60% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 100% by mass, even more preferably 80% by mass or more and less than 100% by mass, and particularly preferably 90% by mass or more and less than 100% by mass.

[0052] In nuclear polymerization, the content ratio of styrene monomers to the total amount of recycled styrene resin raw material particles (a), styrene monomers, and acrylic acid ester monomers is preferably 30% to 85% by mass, more preferably 50% to 80% by mass, even more preferably 55% to 75% by mass, and particularly preferably 60% to 75% by mass.

[0053] The acrylic acid ester monomer may be one type or two or more types.

[0054] Examples of acrylic acid ester monomers include alkyl acrylates such as methyl acrylate and butyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and cetyl methacrylate, with butyl acrylate being preferred. The content of butyl acrylate relative to the total amount of acrylic acid ester monomer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0055] The content of acrylic acid ester monomers in monomer composition (C) is preferably 0.01% to 20% by mass, more preferably 0.01% to 18% by mass, even more preferably less than 0.03% to 15% by mass, particularly preferably 0.05% to 10% by mass, and most preferably 0.08% to 10% by mass.

[0056] In nuclear polymerization, the content of acrylic acid ester monomers relative to the total amount of recycled styrene resin raw material particles (a), styrene monomers, and acrylic acid ester monomers is preferably 0.005% to 20% by mass, more preferably 0.01% to 15% by mass, even more preferably 0.01% to less than 12% by mass, even more preferably 0.03% to 10% by mass, particularly preferably 0.05% to 5% by mass, and most preferably 0.1% to 5% by mass.

[0057] A polyfunctional vinyl monomer is a monomer having two or more vinyl groups. A polyfunctional vinyl monomer may consist of only one type or two or more types.

[0058] The polyfunctional vinyl monomer is preferably a polyfunctional vinyl aromatic compound. A polyfunctional vinyl aromatic compound is an aromatic compound having two or more vinyl groups. The vinyl group may have a structure in which the hydrogen atom bonded to the carbon atom constituting it is substituted by another group (e.g., a methyl group). When the hydrogen atom of the carbon atom where the vinyl group's bond is located is substituted by another group, the vinyl group is also called a vinylidene group. The vinyl groups in the polyfunctional vinyl aromatic compound may be contained within the (meth)acryloyl group located at the molecular terminal.

[0059] By including a polyfunctional vinyl monomer, particularly a polyfunctional vinyl aromatic compound, in monomer composition (C) the strength of recycled foamed styrene resin particles and the recycled styrene resin foam particles can be improved, thereby suppressing dents. Furthermore, moldability can be improved.

[0060] Polyfunctional vinyl aromatic compounds are preferably difunctional vinyl aromatic compounds. Difunctional vinyl aromatic compounds are aromatic compounds having two vinyl groups. Specific examples of polyfunctional vinyl aromatic compounds include, for example, divinylbenzenes such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; diisopropenylbenzenes such as 1,2-diisopropenylbenzene, 1,3-diisopropenylbenzene, and 1,4-diisopropenylbenzene; 1,3-divinylnaphthalene, 1,8-divinylnaphthalene, 1,4-divinylnaphthalene, 1,5-divinylnaphthalene, 2,3-divinylnaphthalene, 2,7-divinylnaphthalene, and 2,6 Examples include divinylnaphthalenes such as -divinylnaphthalene; divinylbiphenyls such as 4,4'-divinylbiphenyl, 4,3'-divinylbiphenyl, 4,2'-divinylbiphenyl, 3,2'-divinylbiphenyl, 3,3'-divinylbiphenyl, 2,2'-divinylbiphenyl, and 2,4-divinylbiphenyl; 1,2-divinyl-3,4-dimethylbenzene; 1,3-divinyl-4,5,8-tributylnaphthalene; and 2,2'-divinyl-4-ethyl-4'-propylbiphenyl.

[0061] Examples of polyfunctional vinyl monomers other than polyfunctional vinyl aromatic compounds include alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate.

[0062] The polyfunctional vinyl monomer preferably contains divinylbenzene. The content of divinylbenzene relative to the total amount of the polyfunctional vinyl monomer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0063] The content of the polyfunctional vinyl monomer in monomer composition (C) is preferably 0.001% to 10% by mass, more preferably 0.005% to 1% by mass, even more preferably less than 0.005% to 0.5% by mass, particularly preferably 0.01% to 0.1% by mass, and most preferably 0.01% to 0.05% by mass.

[0064] In nuclear polymerization, the content of polyfunctional vinyl monomers relative to the total amount of styrene monomers and acrylic acid ester monomers is preferably 0.0005% to 5% by mass, more preferably 0.001% to 1% by mass, even more preferably less than 0.005% to 0.5% by mass, particularly preferably 0.01% to 0.1% by mass, and most preferably 0.01% to 0.05% by mass.

[0065] The monomer composition (C) may contain any suitable vinyl monomer other than the polyfunctional vinyl monomer, such as any suitable styrene monomer, acrylic acid ester monomer, and polyfunctional vinyl monomer, as long as it does not impair the effects of the present invention. Examples of such vinyl monomers include (meth)acrylic acid ester monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and hexyl (meth)acrylate.

[0066] From the viewpoint of environmental contribution, the higher the content of recycled styrene-based resin raw material particles (a) relative to the total amount of recycled styrene-based resin raw material particles (a), styrene monomers, and acrylic acid ester monomers, the better. However, from the viewpoint of producing recycled styrene-based resin particles (A) by nuclear polymerization, the content of recycled styrene-based resin raw material particles (a) relative to the total amount of recycled styrene-based resin raw material particles (a), styrene monomers, and acrylic acid ester monomers, is preferably 5% to 70% by mass, more preferably 10% to 65% by mass, even more preferably 15% to 60% by mass, even more preferably 20% to 60% by mass, and particularly preferably 25% to 55% by mass.

[0067] Recycled styrene resin particles (A) are obtained by nucleation polymerization of a monomer composition (C) with recycled styrene resin raw material particles (a) as the nucleus. Any suitable method can be used as such a nucleation polymerization method, as long as it does not impair the effects of the present invention. One preferred embodiment of such a nucleation polymerization method is to add an emulsion containing a polymerization initiator and styrene monomers, acrylic acid ester monomers, and polyfunctional vinyl monomers ("styrene monomers, etc.") to a suspension obtained by dispersing recycled styrene resin raw material particles (a) in an aqueous medium with recycled styrene resin raw material particles (a) as the nucleus, thereby impregnating the recycled styrene resin raw material particles (a), and then proceeding with polymerization by adding styrene monomers and polyfunctional vinyl monomers as appropriate.

[0068] When obtaining recycled styrene-based resin particles (A), the addition temperature when adding styrene monomers, etc. 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, in order to better exhibit the effects of the present invention. By adjusting the addition temperature when adding styrene monomers, etc. to recycled styrene-based resin raw material particles (a) to the above range, the styrene monomers can be incorporated while maintaining the recycled styrene-based resin raw material particles (a) at an appropriate hardness, thereby enabling good spheroidization of recycled styrene-based resin particles (A), and ultimately resulting in recycled foamable styrene-based resin particles with good spheroidization and excellent moldability. If the addition temperature when adding styrene monomers, etc., to the recycled styrene resin raw material particles (a) is too low and outside the above range, the recycled styrene resin raw material particles (a) will become too hard. When styrene monomers, etc., are incorporated in this state, the recycled styrene resin particles (A) will have difficulty becoming spherical, and the resulting recycled foamed styrene resin particles may have difficulty becoming spherical or have poor moldability. If the addition temperature when adding styrene monomers, etc., to the recycled styrene resin raw material particles (a) is too high and outside the above range, the recycled styrene resin raw material particles (a) will become too soft. When monomer composition (C) is incorporated in this state, the recycled styrene resin particles (A) will have difficulty becoming spherical, and the resulting recycled foamed styrene resin particles may have difficulty becoming spherical or have poor moldability.

[0069] When obtaining a suspension by dispersing recycled styrene-based resin raw material particles (a) in an aqueous medium with the particles acting as nuclei, any suitable method can be used for dispersing the recycled styrene-based resin raw material particles (a) in the aqueous medium, as long as it does not impair the effects of the present invention. Preferably, such a dispersion method involves using a device equipped with a stirring blade. A method for even finer dispersion can be achieved by using a homomixer.

[0070] When obtaining a suspension by dispersing recycled styrene-based resin raw material particles (a) in an aqueous medium with the particles as a nucleus, it is preferable to use a dispersant in the dispersion of the recycled styrene-based resin raw material particles (a) in the aqueous medium. Any suitable dispersant can be used as long as it can be used in suspension polymerization and does not impair the effects of the present invention. Examples of such dispersants include organic dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, and methylcellulose; and sparingly soluble inorganic salts such as magnesium pyrophosphate and tricalcium phosphate. Among these, magnesium pyrophosphate is preferred as a dispersant because it can better express the effects of the present invention.

[0071] The blending ratio of the dispersant to 100 parts by mass of recycled styrene resin particles (A) is preferably 0.05 parts by mass to 2 parts by mass, more preferably 0.1 parts by mass to 1.5 parts by mass, and even more preferably 0.1 parts by mass to 1.0 part by mass.

[0072] When obtaining a suspension by dispersing recycled styrene resin raw material particles (a) in an aqueous medium with the particles as nuclei, it is preferable to use a surfactant in the dispersion of the recycled styrene resin raw material particles (a) in the aqueous medium. Any suitable surfactant can be used as long as it can be used in suspension polymerization and does not impair the effects of the present invention. Examples of such surfactants include sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylsulfonate, sodium alkyldiphenyl ether disulfonate, and sodium α-olefin sulfonate. Among these, sodium dodecylbenzenesulfonate is preferred as the surfactant because it can better express the effects of the present invention.

[0073] The blending ratio of surfactant to 100 parts by mass of recycled styrene resin particles (A) is preferably 0.001 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.

[0074] When obtaining an emulsion containing a polymerization initiator and styrene monomers, any suitable method can be used for emulsion formation, as long as it does not impair the effects of the present invention. Preferably, such dispersion is performed using a device equipped with stirring blades. A method for finer dispersion is to use a homomixer. In this case, it is preferable to disperse the styrene monomers until the oil droplet diameter of the dispersion is less than or equal to the particle diameter of the nucleus. This is because if the oil droplet diameter is larger than the particle diameter of the nucleus when added to an aqueous medium, multiple recycled styrene resin raw material particles (a) will be incorporated into the oil droplets of the dispersion, causing adhesion, plasticization, and coalescence of the recycled styrene resin raw material particles (a), which can easily lead to the generation of excessively large particles.

[0075] When obtaining an emulsion containing a polymerization initiator and a styrene monomer, any suitable polymerization initiator can be used as the polymerization initiator, provided that it is used in suspension polymerization and does not impair the effects of the present invention. Examples of polymerization initiators include organic peroxides and azo compounds such as azobisisobutyronitrile. The polymerization initiator preferably contains at least one selected from the group consisting of peroxyester polymerization initiators and diacyl peroxide polymerization initiators, and more preferably contains a peroxyester polymerization initiator. Examples of peroxyester polymerization initiators include t-butylperoxy-2-ethylhexyl monocarbonate, t-butylperoxy-2-ethylhexanoate, and t-butyl perbenzoate. An example of a diacyl peroxide polymerization initiator is benzoyl peroxide. There may be only one polymerization initiator or two or more.

[0076] The amount of polymerization initiator used is preferably 0.1% to 1.0% by mass, more preferably 0.1% to 0.8% by mass, and even more preferably 0.1% to 0.5% by mass, relative to the monomer composition (C) (total amount of styrene monomer, acrylic acid ester monomer, and polyfunctional vinyl monomer). The amount of polymerization initiator used relative to the total amount of styrene monomer and acrylic acid ester monomer is 0.1% to 1.0% by mass, more preferably 0.1% to 0.8% by mass, and even more preferably 0.1% to 0.5% by mass.

[0077] The polymerization initiator is preferably added in a solution of a styrene monomer or solvent. Examples of solvents include aromatic hydrocarbons such as ethylbenzene and toluene; and aliphatic hydrocarbons such as heptane and octane. When a solvent is used, it is usually used in an amount of 20% by mass or less relative to the styrene monomer or solvent.

[0078] After impregnating a suspension containing recycled styrene resin raw material particles (a) with an emulsion containing styrene monomers, etc., styrene monomers or polyfunctional vinyl monomers may be added as appropriate, and the polymerization reaction may be continued at any appropriate temperature and time as needed.

[0079] A suspension containing recycled styrene resin raw material particles (a) or an emulsion containing styrene monomers may contain a foam regulator. Examples of such foam regulators include fatty acid monoamides such as oleamide, stearamide, and hydroxystearamide; and fatty acid bisamides such as methylenebisstearamide and ethylenebisstearamide.

[0080] <1-2. Injection and impregnation of foaming agent> In embodiments of the present invention, recycled foamable styrene resin particles are obtained by pressurizing and impregnating recycled styrene resin particles (A) with a foaming agent.

[0081] Typical methods for injecting and impregnating the foaming agent in embodiments of the present invention include placing recycled styrene resin particles (A) in a reactor such as an autoclave and injecting and impregnating them with the foaming agent.

[0082] The foaming agent may be one type or two or more types.

[0083] Any suitable blowing agent can be used as the blowing agent, as long as it does not impair the effects of the present invention. The blowing agent referred to herein is preferably a volatile blowing agent. Preferably, the blowing agent is an organic compound that has a boiling point below the softening point of the styrene resin and is gaseous or liquid at atmospheric pressure. Specific examples include, for example, aliphatic hydrocarbons such as propane, n-butane, isobutane, pentane (n-pentane, isopentane, neopentane), and n-hexane; alicyclic hydrocarbons such as cyclopentane and cyclopentadiene; ketones such as acetone and methyl ethyl ketone; alcohols such as methanol, ethanol, and isopropyl alcohol; low-boiling point ether compounds such as dimethyl ether, diethyl ether, dipropyl ether, and methyl ethyl ether; halogen-containing hydrocarbons such as trichloromonofluoromethane and dichlorodifluoromethane; and others. Inorganic gases such as carbon dioxide, nitrogen, and ammonia may also be used as the blowing agent. Among these, the foaming agent is preferably at least one selected from propane, n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, and cyclopentadiene, in order to better exhibit the effects of the present invention, and more preferably at least one selected from propane, n-butane, isobutane, n-pentane, and isopentane.

[0084] The amount of foaming agent can be appropriately set depending on the purpose, as long as it is in an amount sufficient to form recycled styrene-based resin foam particles and recycled styrene-based resin foam molded articles. The amount of foaming agent is preferably 2 to 15 parts by mass when the total amount of recycled styrene-based resin raw material particles (a) and monomer composition (C) is 100 parts by mass.

[0085] The injection temperature of the foaming agent into the recycled styrene 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 to 110°C, and most preferably 40°C to 105°C. The injection temperature of the foaming agent into the recycled styrene resin particles (A) may be varied within the above range. If the injection temperature of the foaming agent into the recycled styrene resin particles (A) is within the above range, the foaming agent can be injected at a lower temperature. By injecting the foaming agent at such a low temperature and then raising the temperature, the rapid impregnation of the foaming agent into the recycled styrene resin particles (A) is suppressed, enabling uniform impregnation. For example, areas that shrink and melt when molded into a recycled styrene resin foam molded article can be reduced. If the injection temperature of the foaming agent into the recycled styrene resin particles (A) is too low and outside the above range, the foaming agent will not easily impregnate the recycled styrene resin particles (A) during injection. When the temperature rises, the foaming agent will be impregnated rapidly, resulting in uneven impregnation of the recycled styrene resin particles (A), which can easily lead to variations in bubbles and surface shrinkage during molding. If the injection temperature of the foaming agent into the recycled styrene resin particles (A) is too high and outside the above range, the foaming agent will be impregnated rapidly into the recycled styrene resin particles (A) during injection. This can result in uneven impregnation of the recycled styrene resin particles (A), which can easily lead to variations in bubbles and surface shrinkage during molding.

[0086] One embodiment of the impregnation temperature of the foaming agent into the recycled styrene 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 more and less than 110°C, particularly preferably 40°C to 105°C, and most preferably 40°C to 102°C.

[0087] Another embodiment of the impregnation temperature of the foaming agent into the recycled styrene resin particles (A) is preferably a temperature above the injection temperature of the foaming agent into the recycled styrene resin particles (A) (which may be the same as the injection temperature of the foaming agent into the recycled styrene 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.

[0088] The impregnation temperature of the foaming agent into the recycled styrene resin particles (A) may be varied within the above range. If the impregnation temperature of the foaming agent into the recycled styrene resin particles (A) is within the above range, in conjunction with the adjustment of the injection temperature, the rapid impregnation of the foaming agent into the recycled styrene resin particles (A) is suppressed, enabling uniform impregnation. For example, areas that shrink and melt when molded into a foamed recycled styrene resin molded product can be reduced. If the impregnation temperature of the foaming agent into the recycled styrene resin particles (A) is too low and outside the above range, the foaming agent may not be impregnated to the center of the recycled styrene resin particles (A), leaving non-foamed areas, which may prevent the acquisition of a good molded product. If the impregnation temperature of the foaming agent into the recycled styrene resin particles (A) is too high and outside the above range, the foaming agent may be too deeply impregnated into the recycled styrene resin particles (A), potentially causing them to melt during molding.

[0089] A particularly representative embodiment of the impregnation temperature of the foaming agent into the recycled styrene 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, especially preferably 90°C or more and less than 110°C, and most preferably 95°C to 105°C.

[0090] The impregnation time of the foaming agent into the recycled styrene resin particles (A) can be any appropriate time, as long as it does not impair the effects of the present invention. Such an impregnation time is preferably 1 to 10 hours.

[0091] <1-3. Other ingredients> The recycled foamable styrene resin particles in embodiments of the present invention may contain any other suitable components, as long as they do not impair the effects of the present invention. Such other components may be one or two or more.

[0092] The recycled foamed styrene resin particles in embodiments of the present invention may contain a flame retardant to enhance flame retardancy. The flame retardant may be one type or two or more types.

[0093] As a flame retardant, any suitable flame retardant can be used as long as it does not impair the effects of the present invention. Preferred flame retardants include bromine compounds that are compatible with polystyrene, such as tetrabromoethane, tetrabromocyclooctane, hexabromocyclododecane, hexabromocyclohexane, trisdibromopropyl phosphate, tetrabromobisphenol A, tetrabromobisphenol F, tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tetrabromobisphenol A-diglycidyl ether, 2,2-bis[4'(2'',3''-dibromoalkoxy)-3',5'-dibromophenyl]-propane, tris(tribromophenoxy)triazine, 2,2-bis(4-alyroxy-3,5-dibromo)propane, and hexabromobenzene.

[0094] When using flame retardants, flame retardant additives may be used in combination. Examples of flame retardant additives include cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and 3,4-dimethyl-3,4-diphenylhexane.

[0095] The total amount of flame retardant and flame retardant aid used can be any appropriate amount, as long as it does not impair the effects of the present invention. Such an amount is preferably 0.1% to 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, relative to the recycled styrene-based resin raw material particles (a).

[0096] The flame retardant can be added at any appropriate time, as long as it does not impair the effects of the present invention. Preferably, the flame retardant is added before the foaming agent is injected. By adding the flame retardant before the foaming agent is injected, the flame retardant can be added at a temperature as low as that at which the foaming agent is injected, thereby enabling good spheroidization and excellent moldability of the resulting recycled foamable styrene resin particles.

[0097] The temperature at which the flame retardant is added is preferably 5°C to 120°C, more preferably 5°C to 118°C, even more preferably 5°C to 115°C, 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.

[0098] In producing recycled foamable styrene resin particles, a partial ester of a higher fatty acid and an alcohol may be used as a foam regulator. That is, the recycled foamable styrene resin particles in the embodiments of the present invention may contain a partial ester of a higher fatty acid and an alcohol. There may be only one type of partial ester of a higher fatty acid and an alcohol, or there may be two or more types. Examples of higher fatty acids include fatty acids with 15 or more carbon atoms, such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and behenic acid, and monoglycerides and diglycerides of these can be used. Preferably, the partial ester of a higher fatty acid and an alcohol is monoglyceride stearate or diglyceride stearate. The content ratio of the partial ester of a higher fatty acid and an alcohol is preferably 0 to 3.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of recycled styrene resin particles (A). Methods for adding partial esters of higher fatty acids and alcohols include, for example, adding them together with a foaming agent, or employing commonly used methods such as dry blending, masterbatch, or melt injection.

[0099] Plasticizers may be used in the production of recycled foamed styrene resin particles. That is, recycled foamed styrene resin particles may contain plasticizers. There may be only one type of plasticizer or two or more types. Examples of plasticizers include diisobutyl adipate, dioctyl adipate, dibutyl sebacate, glycerin tristearate, glycerin tricaprylate, toluene, xylene, coconut oil, palm oil, rapeseed oil, and liquid paraffin.

[0100] The amount of plasticizer used can be any appropriate amount, as long as it does not impair the effects of the present invention. Such an amount is preferably 0.1% to 5.0% by mass, more preferably 0.2% to 4.0% by mass, and even more preferably 0.5% to 3.0% by mass, relative to the recycled styrene resin particles (a).

[0101] The plasticizer can be added at any appropriate timing, as long as it does not impair the effects of the present invention. It is preferable to add the plasticizer before injecting the blowing agent, and more preferable to add it after the polymerization process (nuclear polymerization) but before injecting the blowing agent. By adding the plasticizer before injecting the blowing agent, the plasticizer can be added at a temperature as low as that at which the blowing agent is injected, thereby enabling good spheroidization and excellent moldability of the resulting recycled foamable styrene resin particles.

[0102] The temperature at which the plasticizer is added is preferably 5°C to 120°C, more preferably 20°C to 118°C, even more preferably 25°C to 115°C, and particularly preferably 40°C to 110°C.

[0103] When manufacturing recycled foamable styrene resin particles, foaming aids may be used. That is, recycled foamable styrene resin particles may contain foaming aids. There may be only one type of foaming aid, or there may be two or more types. Examples of foaming aids include diisobutyl adipate, styrene monomer, toluene, cyclohexane, ethylbenzene, liquid paraffin, and coconut oil.

[0104] In producing recycled foamable styrene resin particles, a foam regulator may be used. That is, the recycled foamable styrene resin particles in the embodiments of the present invention may contain a foam regulator. There may be only one type of foam regulator, or there may be two or more types. Examples of foam regulators include fatty acid monoamides such as oleamide, stearamide, and hydroxystearamide; and fatty acid bisamides such as methylenebisstearamide and ethylenebisstearamide.

[0105] The amount of foam regulator used can be any appropriate amount, as long as it does not impair the effects of the present invention. Such an amount is preferably 0 to 5.0 parts by mass, more preferably 0.02 to 3.0 parts by mass, even more preferably 0.02 to 2.0 parts by mass, and particularly preferably 0.02 to 1.0 parts by mass, per 100 parts by mass of recycled styrene resin particles (A).

[0106] Recycled foamed styrene resin particles may contain foam regulators such as talc, calcium carbonate, mica, citric acid, and sodium bicarbonate. Only one type of foam regulator may be used. And there may be two or more types.

[0107] Other additives include, for example, pigments, radiant heat transfer inhibitors, crosslinking agents, stabilizers, fillers, lubricants, colorants, antistatic agents, spreading agents, weathering agents, anti-aging agents, anti-fogging agents, and fragrances.

[0108] <1-4. Surface Treatment> The recycled foamed styrene resin particles may be surface-treated. Such surface treatment is preferably performed using at least one selected from silicone oil, antistatic agents, fatty acid metal salts, and fusion accelerators.

[0109] When surface treatment with silicone oil is performed on recycled foamed styrene resin particles, the amount of silicone oil used per 100 parts by mass of recycled foamed styrene resin particles before surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.003 to 0.28 parts by mass, even more preferably 0.005 to 0.25 parts by mass, particularly preferably 0.008 to 0.23 parts by mass, and most preferably 0.01 to 0.23 parts by mass. If the amount of silicone oil used is too little and falls outside the above range, for example, when an antistatic agent is used, the affinity with the antistatic agent during foaming may not be sufficient, and static electricity may be easily generated. If the amount of silicone oil used is too much and falls outside the above range, the surface may be lost due to the surface melting during molding, etc.

[0110] The silicone oil may be of one type or two or more types.

[0111] Any suitable silicone oil can be used as the silicone oil, as long as it does not impair the effects of the present invention. In terms of being able to better express the effects of the present invention, examples of straight silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane are used, and methylphenylpolysiloxane is preferred.

[0112] When recycled foamed styrene resin particles are surface-treated with an antistatic agent, the amount of antistatic agent used per 100 parts by mass of recycled foamed styrene resin particles before surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, even more preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of antistatic agent is too small and outside the above range, static electricity may be easily generated during foaming. If the amount of antistatic agent is too large and outside the above range, the surface of the recycled styrene resin foam particles or the recycled styrene resin foam molded product may become sticky.

[0113] The antistatic agent may be one type or two or more types.

[0114] As an antistatic agent, any suitable antistatic agent can be used as long as it does not impair the effects of the present invention. In terms of being able to better exhibit the effects of the present invention, at least one selected from nonionic surfactants and fatty acid glycerides can be used as an antistatic agent, and preferably a combination of a nonionic surfactant and a fatty acid glyceride.

[0115] The nonionic surfactant may be one type or two or more types.

[0116] As the nonionic surfactant, any suitable nonionic surfactant can be used as long as it does not impair the effects of the present invention. Examples of nonionic surfactants that can better express the effects of the present invention include polyethylene glycol, glycerin, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyhydric alcohols, and 1-amino-2-hydroxy compounds. Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. Specific examples of polyoxyethylene alkyl esters include polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, and polyoxyethylene oleate. Specific examples of polyhydric alcohols include glycerin and propylene glycol. Examples of 1-amino-2-hydroxy compounds include, for example, N-hydroxyethyl-N-(2-hydroxyalkyl)amine, N,N-bis(hydroxyethyl)dodecylamine, N,N-bis(hydroxyethyl)tetradecylamine, N,N-bis(hydroxyethyl)hexadecylamine, N,N-bis(hydroxyethyl)octadecylamine, N-hydroxyethyl-N-(2-hydroxytetradecyl)amine, N-hydroxyethyl-N-(2-hydroxyhexadecyl)amine, N-hydroxyethyl-N-(2-hydroxyoctadecyl)amine, and N-hydroxypropyl-N Examples include -(2-hydroxytetradecyl)amine, N-hydroxybutyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxyhexadecyl)amine, N-hydroxypentyl-N-(2-hydroxyoctadecyl)amine, N,N-bis(2-hydroxyethyl)dodecylamine, N,N-bis(2-hydroxyethyl)tetradecylamine, N,N-bis(2-hydroxyethyl)hexadecylamine, N,N-bis(2-hydroxyethyl)octadecylamine, and their salts.Polyethylene glycol is preferred as the nonionic surfactant in terms of being able to better exhibit the effects of the present invention.

[0117] When a nonionic surfactant is used as at least a part of the antistatic agent, the amount of the nonionic surfactant used per 100 parts by mass of regenerated foamable styrene-based resin particles before surface treatment is preferably 0.001 to 2.0 parts by mass, more preferably 0.001 to 1.5 parts by mass, even more preferably 0.001 to 1.0 parts by mass, even more preferably 0.001 to 0.5 parts by mass, even more preferably 0.001 to 0.3 parts by mass, even more preferably 0.005 to 0.28 parts by mass, even more preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of nonionic surfactant is too small and falls outside the above range, static electricity may be easily generated during foaming. If the amount of nonionic surfactant exceeds the above range, the surface of the recycled styrene-based resin foam particles or the recycled styrene-based resin foam molded product may become sticky.

[0118] The fatty acid glycerides may be one type or two or more types.

[0119] Any suitable fatty acid glyceride can be used as the fatty acid glyceride, as long as it does not impair the effects of the present invention. Specifically, examples of fatty acid glycerides that can better express the effects of the present invention include monoglyceride stearate and monoglyceride linoleate. Monoglyceride stearate is preferred as the fatty acid glyceride in terms of better expressing the effects of the present invention.

[0120] When fatty acid glycerides are used as at least a part of the antistatic agent, the amount of fatty acid glycerides per 100 parts by mass of recycled foamable styrene-based resin particles before surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, even more preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of fatty acid glycerides is too small and outside the above range, static electricity may be easily generated during foaming. If the amount of fatty acid glycerides is too large and outside the above range, the surface of the recycled styrene-based resin foam particles or the recycled styrene-based resin foam molded article may become sticky.

[0121] When recycled foamable styrene-based resin particles are surface-treated with a fatty acid metal salt, the amount of fatty acid metal salt used per 100 parts by mass of recycled foamable styrene-based resin particles before surface treatment is preferably 0.005 to 0.5 parts by mass, more preferably 0.007 to 0.45 parts by mass, even more preferably 0.01 to 0.4 parts by mass, particularly preferably 0.015 to 0.35 parts by mass, and most preferably 0.02 to 0.3 parts by mass. If the amount of fatty acid metal salt is too small and outside the above range, a lot of blocking may occur during foaming, and it may not be possible to obtain a good styrene-based resin foamed molded product. If the amount of fatty acid metal salt is too large and outside the above range, a large amount of metal salt will be present during foaming, making it easier to become charged, which may lead to the generation of static electricity and poor fusion of the molded product.

[0122] The fatty acid metal salt may be one type or two or more types.

[0123] As the fatty acid metal salt, any suitable fatty acid metal salt can be used as long as it does not impair the effects of the present invention. Examples of fatty acid metal salts that can better express the effects of the present invention include stearate metal salts and laurate metal salts. Specific examples of stearate metal salts include magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate. Specific examples of laurate metal salts include zinc laurate and barium laurate. Magnesium stearate and zinc stearate are preferred as fatty acid metal salts that can better express the effects of the present invention.

[0124] When recycled foamable styrene resin particles are surface-treated with a fusion accelerator, the amount of fusion accelerator used per 100 parts by mass of recycled foamable styrene resin particles before surface treatment is preferably 0.01 to 0.8 parts by mass, more preferably 0.01 to 0.7 parts by mass, even more preferably 0.01 to 0.6 parts by mass, particularly preferably 0.01 to 0.55 parts by mass, and most preferably 0.013 to 0.5 parts by mass. If the amount of fusion accelerator is too small and outside the above range, the fusion properties will decrease during molding, and it may not be possible to obtain a good recycled styrene resin foam molded article. If the amount of fusion accelerator is too large and outside the above range, there is a risk of blocking during foaming.

[0125] The fusion accelerator may be one type or two or more types.

[0126] As a fusion accelerator, any suitable fusion accelerator can be used as long as it does not impair the effects of the present invention. Examples of fusion accelerators that can better express the effects of the present invention include fatty acid triglycerides, fatty acid diglycerides, fatty acid monoglycerides, and vegetable oils. Specific examples of fatty acid triglycerides include lauric acid triglyceride, stearate triglyceride, linoleic acid triglyceride, and hydroxystearate triglyceride. Specific examples of fatty acid diglycerides include lauric acid diglyceride, stearate diglyceride, and linoleic acid diglyceride. Specific examples of fatty acid monoglycerides include lauric acid monoglyceride. Specific examples of vegetable oils include hydrogenated castor oil. Stearic acid triglyceride and hydroxystearate triglyceride are preferred as fusion accelerators that can better express the effects of the present invention.

[0127] ≪≪2. Recycled Styrene-Based Resin Foam Particles≫≫ The recycled styrene-based resin foam particles according to the embodiment of the present invention are obtained by foaming the recycled foamable styrene-based resin particles according to the embodiment of the present invention.

[0128] The recycled styrene-based resin foam particles preferably have an average bubble diameter of 0.01 mm to 1.10 mm, more preferably 0.01 mm to 1.00 mm, even more preferably 0.01 mm 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 bubble diameter of the recycled styrene-based resin foam particles is within the above range, blocking during foaming and molding can be better prevented, and furthermore, while suppressing electrostatic charge during foaming and molding, better fusion properties and surface properties can be exhibited, and recycled styrene-based resin foam molded articles with less static electricity can be molded. If the average bubble diameter of the recycled styrene-based resin foam particles is smaller than 0.01 mm, there is a risk that the surface will melt and shrink during molding.

[0129] The foaming includes foaming recycled expandable styrene-based resin particles to a desired bulk expansion ratio (bulk density) using steam or the like. The bulk expansion ratio of the recycled styrene-based resin expanded particles is 5 to 125 times, more preferably 5 to 100 times, still more preferably 5 to 90 times, particularly preferably 10 to 85 times, and most preferably 15 to 83 times. The bulk density of the recycled styrene-based resin expanded particles is preferably 0.0080 g / cm 3 ~0.20 g / cm 3 more preferably 0.010 g / cm 3 ~0.20 g / cm 3 still more preferably 0.011 g / cm 3 ~0.20 g / cm 3 particularly preferably 0.012 g / cm 3 ~0.10 g / cm 3 most preferably 0.012 g / cm 3 ~0.060 g / cm 3 The bulk density is the reciprocal of the bulk expansion ratio. When the bulk expansion ratio of the recycled styrene-based resin expanded particles is within the above range, blocking during foaming and molding can be further prevented, and further, while the electrostatic property during foaming and molding is further suppressed, better fusion property and surface property are exhibited, and the recycled styrene-based resin expanded particles capable of molding a recycled styrene-based resin expanded molded article with less static electricity can be provided. In addition, according to the recycled styrene-based resin expanded particles according to the embodiment of the present invention, by being in the bulk expansion ratio range of 60 to 125 times as described above, the strength is improved and the occurrence of dents can be suppressed.

[0130] In one representative embodiment, the recycled styrene-based resin expanded particles can be used for molding a recycled styrene-based resin expanded molded article. In another embodiment, the recycled styrene-based resin expanded particles can be used as they are as a cushioning material, a heat insulating material, an aggregate for concrete, or the like. When the recycled styrene-based resin expanded particles are used as they are, the recycled styrene-based resin expanded particles can preferably be used as a filled body in which a large number of recycled styrene-based resin expanded particles are filled in a bag body. Such recycled styrene-based resin expanded particles are suitable for, for example, a core material of a cushion (expanded particles filled inside the cushion).

[0131] ≪≪3. Recycled styrene-based resin foam molded product≫≫ A recycled styrene-based resin foam molded article according to one embodiment of the present invention is a recycled styrene-based resin foam molded article formed from recycled styrene-based resin foam particles according to an embodiment of the present invention. A recycled styrene-based resin foam molded article according to another embodiment of the present invention is a recycled styrene-based resin foam molded article formed from recycled foamable styrene-based resin particles according to an embodiment of the present invention.

[0132] The recycled styrene-based resin foam molded article typically includes particles obtained by further foaming the recycled styrene-based resin foam particles in the present invention (hereinafter sometimes simply referred to as "foamed particles").

[0133] Recycled styrene-based foamed molded articles are typically composed of multiple foamed particles that are fused together.

[0134] A recycled styrene foam molded article can typically be produced by placing recycled expandable styrene particles or recycled styrene foam particles into a mold having a predetermined shape according to the purpose, and then molding or foam molding within the mold. In this case, the recycled styrene foam particles are used as pre-foamed particles. More specifically, in-mold molding / in-mold foam molding includes (i) filling a closed mold having a large number of small holes with recycled expandable styrene particles and / or recycled styrene foam particles, (ii) heating and foaming the recycled expandable styrene particles and / or recycled styrene foam particles with a heat transfer medium (e.g., pressurized steam) to obtain foamed particles, and (iii) filling the gaps between the foamed particles and fusing the foamed particles together to form a single integrated product through this heating and foaming. The density of the recycled styrene foam molded article can be appropriately set according to the purpose. The density of the recycled styrene foam molded product can be adjusted, for example, by pre-adjusting the bulk expansion ratio of the recycled styrene foam particles filled into the mold, or by adjusting the amount of recycled styrene foam particles filled into the mold.

[0135] The temperature for heat foaming (essentially the temperature of the heat transfer medium) is preferably 90°C to 150°C, and more preferably 110°C to 130°C. The heat foaming time is preferably 5 seconds to 50 seconds, and more preferably 10 seconds to 50 seconds. The molding vapor pressure (gauge pressure of the heat transfer medium) for heat foaming is preferably 0.04 MPa to 0.1 MPa, and more preferably 0.06 MPa to 0.08 MPa. Under these conditions, the foamed particles can be well fused together.

[0136] If necessary, the recycled styrene foam particles may be aged before molding the recycled styrene foam molded product. The preferred aging temperature for the recycled styrene foam particles is 20°C to 60°C. If the aging temperature is too low, an excessively long aging time may be required. If the aging temperature is too high, the foaming agent in the recycled styrene foam particles may dissipate, reducing moldability.

[0137] The foaming ratio of the foamed particles in the recycled styrene-based resin foam molded article is 5 to 150 times, more preferably 2 to 100 times, more preferably 5 to 90 times, even more preferably 10 to 85 times, and particularly preferably 15 to 83 times.

[0138] The recycled styrene-based resin foam molded articles according to embodiments of the present invention are lightweight and have excellent heat insulation and mechanical strength, making them suitable for use as wall insulation, floor insulation, roof insulation, automobile insulation, hot water tank insulation, pipe insulation, solar system insulation, water heater insulation, containers for food and industrial products (e.g., food containers such as fish boxes, returnable containers), cushioning materials, floats, blocks, packaging materials for fish and agricultural products, molded articles for embankments, core materials for tatami mats, core materials for cushions, aggregates for concrete, and the like. [Examples]

[0139] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement and evaluation methods for each characteristic are as follows.

[0140] <Calculation of volume retention rate and strength evaluation of recycled styrene-based foamed particles> The volume retention rate of recycled styrene foam particles was calculated and their strength evaluated using the following compression tests. (Compression test) 120 mL of recycled styrene foam particles were measured using a graduated cylinder and placed in a cylindrical container with an inner diameter of 50 mm and a height of 61 mm. The recycled styrene foam particles in the container were subjected to 100 compression cycles using a universal testing machine (Shimadzu Corporation, "Autograph AG-X plus 100kN") at a test speed of 10 mm / min, with an upper load limit of 267 N and a lower load limit of 1 N. After repeated compression, the recycled styrene-based resin foam particles were removed from the container and left to stand for 24 hours under conditions of room temperature (23±2°C) and humidity (50±10%). The volume V2 of the recycled styrene foam particles after standing was measured using the same graduated cylinder used to measure the volume of the recycled styrene foam particles before the test. ΔV was calculated from the pre-test volumes V1 and V2 [mL] using the following formula (1). ΔV[%]=(V2 / V1)×100 ···(1) In the following examples and comparative examples, V1 is 120 mL. (Calculation of volume retention rate) The above compression test was performed three times, and the average value of the ΔV from the three tests was used as the volume retention rate for each example and comparative example. Based on the volume retention rate results, the strength of the recycled styrene-based resin foam particles was evaluated according to the following criteria. (Evaluation Criteria) ◎: Volume retention rate is between 80% and 100%. ○: Volume retention rate is 60% or more but less than 80% △: Volume retention rate is 50% or more but less than 60% ×: Volume retention rate is less than 50%

[0141] <Measurement of weight-average molecular weight> The weight-average molecular weight (Mw) was measured using GPC (gel permeation chromatography). Here, weight-average molecular weight refers to the weight-average molecular weight on a polystyrene basis. Specifically, it was measured using the following procedure. 3 mg of the sample was dissolved completely in 10 mL of tetrahydrofuran (THF) at room temperature for 72 hours, and then filtered through a non-aqueous 0.45 μm chromatographic disk. The filtrate was measured using a chromatograph under the following measurement conditions. The weight-average molecular weight was determined from a pre-prepared calibration curve of standard polystyrene. (Measurement conditions) Equipment: High speed GPC equipment Product Name: Tosoh HLC-8320GPC EcoSEC System (with built-in RI detector) Analysis conditions: Guard column: TSKguardcolumn SuperHZ-H (4.6mm ID x 2cm L) x 1 Column: TSKgel SuperHZM-H (4.6mm I.D × 15cm L) × 2 tubes Column temperature: 40℃ Temperature: 40°C Mobile phase: THF Mobile phase flow rate: Sample-side pump = 0.175 mL / min Reference pump = 0.175 mL / min Detector: RI detector Sample concentration: 0.3g / L Injection volume: 50μL Measurement time: 0 min ~ 25 min Runtime: 25 min Sampling pitch: 200 msec (Creating a calibration curve) For the calibration curve, standard polystyrene samples were used, manufactured by Tosoh Corporation and marketed as "TSK standard POLYSTYRENE," with weight-average molecular weights of 5,480,000, 3,480,000, 1,090,000, 377,000, 110,000, 37,900, 9,100, 2,630, and 589. The standard polystyrene samples for the calibration curve described above were divided into three groups: Group A (weight-average molecular weight of 1,090,000), Group B (weight-average molecular weights of 3,480,000, 110,000, 9,100, and 589), and Group C (weight-average molecular weights of 5,480,000, 377,000, 37,900, and 2,630). 5 mg of the standard polystyrene sample belonging to Group A with a weight-average molecular weight of 1,090,000 was weighed and dissolved in 20 mL of THF, and 50 μL of the resulting solution was injected into the sample column. 5 mg, 5 mg, 5 mg, and 10 mg of the standard polystyrene samples belonging to Group B with weight-average molecular weights of 3,480,000, 110,000, 9,100, and 589 were weighed in the order described above, dissolved in 50 mL of THF, and 50 μL of the resulting solution was injected into the sample column. Standard polystyrene samples belonging to Group C, with weight-average molecular weights of 5,480,000, 377,000, 37,900, and 2,630, were weighed in the order listed above (1 mg, 5 mg, 5 mg, and 5 mg respectively). These were then dissolved in 40 mL of THF, and 50 μL of the resulting solution was injected into the sample column. A calibration curve (cubic equation) was created from the retention times of these standard polystyrene samples using the HLC-8320GPC dedicated data analysis program GPC Workstation (EcoSEC-WS), and this was used as the calibration curve for measuring the weight-average molecular weight in polystyrene equivalent.

[0142] [Manufacturing Example 1]: Manufacturing of recycled styrene-based resin raw material particles (a) Recycled styrene resin raw material particles (a) were produced by feeding recycled polystyrene foam pellets into a single-screw extruder, heating and melting them at 200°C, extruding them from a mold, and cutting them underwater to achieve an average particle size of 0.75 mm (approximately spherical). The weight-average molecular weight of the recycled styrene resin raw material particles (a) was 150,000.

[0143] [Example 1] <Preparation of recycled foamed styrene-based resin particles (1)> In a 100-liter reactor with a stirrer, 33.2 kg of water, 2.9 g of sodium dodecylbenzenesulfonate, and 146 g of magnesium pyrophosphate were added. Then, 12.6 kg of recycled styrene resin raw material particles (a) obtained in Production Example 1 were added, and the mixture was stirred at 150 rpm to suspend it and prepare suspension (1). Separately, 1.658 kg of styrene, 0.042 kg of butyl acrylate, and 1.0 g of divinylbenzene (81% purity) were added to a dispersion of 3.0 kg of water, 0.8 g of sodium dodecylbenzenesulfonate, and 22 g of magnesium pyrophosphate. The mixture was stirred with a homomixer to create an emulsion, and emulsion (1) was prepared. Furthermore, separately, 2.3 kg of styrene containing 102.9 g of t-butyl peroxy-2-ethylhexanoate and 19.4 g of t-butyl peroxy-2-ethylhexyl monocarbonate, used as polymerization initiators, was added to a dispersion of 2.5 kg of water and 0.8 g of sodium dodecylbenzenesulfonate, and the mixture was stirred with a homomixer to emulsify it and prepare emulsion (2). The above suspension (1) in a 100-liter reactor with a stirrer was maintained at 75°C, and the above emulsion (1) was added. After 30 minutes, the above emulsion (2) was added, and the mixture was maintained at 75°C for 30 minutes so that the styrene and polymerization initiator would be well absorbed into the recycled styrene resin raw material particles (a). Immediately after this period, a mixed solution of 25.40 kg of styrene and 6.3 g of divinylbenzene (81% purity) was continuously added dropwise over 120 minutes. The addition temperature was gradually increased from 75°C to 105°C. The temperature was then increased to 125°C over 30 minutes, maintained at 125°C for 30 minutes, and then cooled to 100°C to produce recycled styrene resin particles (A1) in the reactor. Table 1 shows the mass percentages [%] of recycled styrene resin raw material particles (a), styrene monomer (styrene), and acrylic ester monomer (butyl acrylate) used in the preparation of recycled styrene resin particles (A1), with the total amount of recycled styrene resin raw material particles (a), styrene monomer, and acrylic ester monomer set to 100%. Table 1 also shows the mass percentage [%] of divinylbenzene added when the total amount of styrene monomer and acrylic ester monomer is set to 100%. Furthermore, Table 1 shows the mass percentage [%] of each polymerization initiator when the total amount of styrene monomer and acrylic ester monomer is set to 100%. Next, to a dispersion of 3.3 kg of water, 1.5 g of sodium dodecylbenzenesulfonate, and 22 g of magnesium pyrophosphate, 21 g of ethylenebisstearate and 21 g of 12-hydroxystearate were added. Furthermore, a mixed solution of 1.5% by mass of cyclohexane, 0.7% by mass of diisobutyl adipate, and 0.2% by mass of styrene was added to the recycled styrene resin particles (A1), and the mixture was stirred with a homomixer to emulsify and prepare emulsion (3). Emulsion (3) was added to the reactor cooled to 100°C. Fifteen minutes after the addition was completed, 9.0% by mass of butane (isobutane / n-butane = 30% by mass / 70% by mass) was injected into the recycled styrene resin particles (A1) as a blowing agent, and the mixture was held in this state for 5 hours to allow the blowing agent to slowly impregnate the particles. After that, the temperature inside the reactor was cooled to 25°C. Subsequently, the contents were removed from the reactor, dehydrated, dried, and classified to obtain recycled foamable styrene-based resin particles (1). The weight-average molecular weight of recycled foamed styrene resin particles (1) was measured by the method described above.

[0144] <Surface treatment of recycled foamed styrene resin particles (1)> To recycled foamed styrene resin particles (1), 0.05% by mass of polyethylene glycol, 0.1% by mass of zinc stearate, 0.05% by mass of fatty acid triglycerides, and 0.05% by mass of fatty acid monoglycerides were added to a tumbler mixer, stirred for 30 minutes, and surface treatment was performed to obtain surface-treated recycled foamed styrene resin particles (1').

[0145] <Preparation of recycled styrene-based foamed particles (pf1)> 417 g of the obtained surface-treated recycled foamable styrene resin particles (1') were placed in a cylindrical batch-type pressurized foaming machine with a volume of 25 liters and heated with steam for 3 minutes to obtain recycled styrene resin foam particles (pf1). The bulk density of the recycled styrene resin foam particles (pf1) was 0.017 g / cm³. 3 The expansion ratio was 60 times. Compression tests were conducted on these recycled styrene-based foam particles (pf1), and the volume retention rate was calculated to evaluate their strength. The results are shown in Table 1.

[0146] <Preparation of recycled styrene-based foamed molded product (f1)> A molding machine with a cavity measuring 300 mm (length) x 400 mm (width) x 30 mm (thickness) was used. Recycled styrene-based foam particles (pf1) were left at room temperature for 24 hours, then filled into the cavity of the molding machine's mold, heated at a vapor pressure of 0.06 MPa (gauge pressure) for 30 seconds, and then cooled until the internal pressure of the mold reached 0.03 MPa. After release from the mold, a plate-shaped recycled styrene-based foam molded body (f1) corresponding to the mold was obtained. Thus, it was confirmed that the recycled styrene-based foam particles (pf1) of Example 1 could be molded. The density of the recycled styrene-based foam molded body (f1) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0147] [Example 2] In the preparation of recycled styrene-based resin particles (A), the procedure was carried out in the same manner as in Example 1, except that the amount of styrene in emulsion (1) was changed to 1.49 kg and the amount of butyl acrylate was changed to 0.21 kg. Recycled styrene-based resin particles (A2), recycled foamable styrene-based resin particles (2), and recycled foamed styrene-based resin particles (pf2) were obtained. The results are shown in Table 1. Furthermore, recycled styrene-based resin foam particles (pf2) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f2) could be obtained. The density of the recycled styrene-based resin foam molded article (f2) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0148] [Example 3] In the preparation of recycled styrene-based resin particles (A), the procedure was carried out in the same manner as in Example 1, except that the amount of styrene in emulsion (1) was changed to 1.28 kg and the amount of butyl acrylate to 0.42 kg. Recycled styrene-based resin particles (A3), recycled foamable styrene-based resin particles (3), and recycled foamed styrene-based resin particles (pf3) were obtained. The results are shown in Table 1. Furthermore, recycled styrene-based resin foam particles (pf3) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f3) could be obtained. The density of the recycled styrene-based resin foam molded article (f3) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0149] [Example 4] In the preparation of recycled styrene-based resin particles (A), the procedure was carried out in the same manner as in Example 1, except that the amount of styrene in emulsion (1) was changed to 1.07 kg and the amount of butyl acrylate was changed to 0.63 kg. Recycled styrene-based resin particles (A4), recycled foamable styrene-based resin particles (4), and recycled foamed styrene-based resin particles (pf4) were obtained. The results are shown in Table 1. Furthermore, recycled styrene-based resin foam particles (pf4) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f4) could be obtained. The density of the recycled styrene-based resin foam molded article (f4) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0150] [Example 5] In the preparation of recycled styrene-based resin particles (A), the procedure was carried out in the same manner as in Example 1, except that the amount of styrene in emulsion (1) was changed to 0.86 kg and the amount of butyl acrylate to 0.84 kg. Recycled styrene-based resin particles (A5), recycled foamable styrene-based resin particles (5), and recycled foamed styrene-based resin particles (pf5) were obtained. The results are shown in Table 1. Furthermore, recycled styrene-based resin foam particles (pf5) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f5) could be obtained. The density of the recycled styrene-based resin foam molded article (f5) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0151] [Example 6] In the preparation of recycled styrene-based resin particles (A), the procedure was carried out in the same manner as in Example 1, except that the amount of styrene in emulsion (1) was changed to 0.44 kg and the amount of butyl acrylate to 1.26 kg. Recycled styrene-based resin particles (A6), recycled foamable styrene-based resin particles (6), and recycled foamed styrene-based resin particles (pf6) were obtained. The results are shown in Table 2. Furthermore, recycled styrene-based resin foam particles (pf6) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f6) could be obtained. The density of the recycled styrene-based resin foam molded article (f6) was 0.017 g / cm³.3 The expansion ratio was 60 times.

[0152] [Example 7] In the preparation of recycled styrene-based resin particles (A), the procedure was carried out in the same manner as in Example 1, except that the amount of styrene in emulsion (1) was changed to 0.020 kg and the amount of butyl acrylate to 1.68 kg. Recycled styrene-based resin particles (A7), recycled foamable styrene-based resin particles (7), and recycled foamed styrene-based resin particles (pf7) were obtained. The results are shown in Table 2. Furthermore, recycled styrene-based resin foam particles (pf7) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f7) could be obtained. The density of the recycled styrene-based resin foam molded article (f7) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0153] [Example 8] In the preparation of recycled styrene-based resin particles (A), the procedure was the same as in Example 1, except that no styrene was used in emulsion (1) (i.e., the amount of styrene was 0.00 kg), the amount of butyl acrylate was changed to 1.89 kg, and the amount of styrene in emulsion (2) was changed to 2.11 kg. Recycled styrene-based resin particles (A8), recycled foamable styrene-based resin particles (8), and recycled foamed styrene-based resin particles (pf8) were obtained. The results are shown in Table 2. Furthermore, recycled styrene-based resin foam particles (pf8) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f8) could be obtained. The density of the recycled styrene-based resin foam molded article (f8) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0154] [Example 9] In the preparation of recycled styrene-based resin particles (A), the procedure was the same as in Example 1, except that the amount of styrene in emulsion (1) was omitted (i.e., the amount of styrene was 0.00 kg), the amount of butyl acrylate was changed to 2.10 kg, and the amount of styrene in emulsion (2) was changed to 1.90 kg. Recycled styrene-based resin particles (A9), recycled foamable styrene-based resin particles (9), and recycled foamed styrene-based resin particles (pf9) were obtained. The results are shown in Table 2. Furthermore, recycled styrene-based resin foam particles (pf9) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f9) could be obtained. The density of the recycled styrene-based resin foam molded article (f9) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0155] [Example 10] In the preparation of recycled styrene resin particles (A), the procedure was carried out in the same manner as in Example 3, except that the amount of divinylbenzene (81% purity) in emulsion (1) was changed to 2.4 g, and the amount of divinylbenzene (81% purity) in the mixed solution, which was added dropwise while gradually increasing the temperature from 75°C to 105°C, was changed to 15.7 g. Recycled styrene resin particles (A10), recycled foamable styrene resin particles (10), and recycled foamed styrene resin particles (pf10) were obtained. The results are shown in Table 3. Furthermore, recycled styrene-based resin foam particles (pf10) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f10) could be obtained. The density of the recycled styrene-based resin foam molded article (f10) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0156] [Example 11] In the preparation of recycled styrene resin particles (A), the procedure was carried out in the same manner as in Example 3, except that the amount of divinylbenzene (81% purity) in emulsion (1) was changed to 2.0 g, and the amount of divinylbenzene (81% purity) in the mixed solution, which was added dropwise while gradually increasing the temperature from 75°C to 105°C, was changed to 12.5 g. Recycled styrene resin particles (A11), recycled foamable styrene resin particles (11), and recycled foamed styrene resin particles (pf11) were obtained. The results are shown in Table 3. Furthermore, recycled styrene-based resin foam particles (pf11) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f11) could be obtained. The density of the recycled styrene-based resin foam molded article (f11) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0157] [Example 12] In the preparation of recycled styrene resin particles (A), the procedure was carried out in the same manner as in Example 3, except that the amount of t-butyl peroxy-2-ethylhexanoate in emulsion (2) was changed to 88.2 g. Recycled styrene resin particles (A12), recycled foamable styrene resin particles (12), and recycled foamed styrene resin particles (pf12) were obtained. The results are shown in Table 3. Furthermore, recycled styrene-based resin foam particles (pf12) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f12) could be obtained. The density of the recycled styrene-based resin foam molded article (f12) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0158] [Example 13] In the preparation of recycled styrene resin particles (A), the procedure was carried out in the same manner as in Example 3, except that the amount of t-butyl peroxy-2-ethylhexanoate in emulsion (2) was changed to 82.3 g. Recycled styrene resin particles (A13), recycled foamable styrene resin particles (13), and recycled foamed styrene resin particles (pf13) were obtained. The results are shown in Table 3. Furthermore, recycled styrene-based resin foam particles (pf13) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f13) could be obtained. The density of the recycled styrene-based resin foam molded article (f13) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0159] [Example 14] In the preparation of recycled styrene resin particles (A), the procedure was carried out in the same manner as in Example 3, except that the amount of divinylbenzene in emulsion (1) was changed to 1.5 g, the t-butyl peroxy-2-ethylhexanoate in emulsion (2) was changed to 122.7 g of benzoyl peroxide (75.5% purity), and the amount of divinylbenzene in the mixed solution, which was added dropwise while gradually increasing the temperature from 75°C to 105°C, was changed to 9.4 g. Recycled styrene resin particles (A14), recycled foamable styrene resin particles (14), and recycled foamed styrene resin particles (pf14) were obtained. The results are shown in Table 3. Furthermore, recycled styrene-based resin foam particles (pf14) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f14) could be obtained. The density of the recycled styrene-based resin foam molded article (f14) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0160] [Example 15] In the preparation of recycled styrene resin particles (A), the procedure was carried out in the same manner as in Example 3, except that t-butyl peroxy-2-ethylhexanoate in emulsion (2) was replaced with 122.7 g of benzoyl peroxide (75.5% purity). Recycled styrene resin particles (A15), recycled foamable styrene resin particles (15), and recycled foamed styrene resin particles (pf15) were obtained. The results are shown in Table 3. Furthermore, recycled styrene-based resin foam particles (pf15) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f15) could be obtained. The density of the recycled styrene-based resin foam molded article (f15) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0161] [Example 16] In the same manner as in Example 3, recycled styrene resin particles (A16), recycled foamed styrene resin particles (16), and surface-treated recycled foamed styrene resin particles (16') were obtained. The expansion ratio is 10 times (bulk density 0.10 g / cm³). 3 Recycled styrene foam particles (pf16) were obtained in the same manner as in Example 1, except that 2500g of recycled foamable styrene resin particles (16') were placed in a foamer and heated with steam for 1 minute to induce foaming. The results are shown in Table 4. Furthermore, recycled styrene-based resin foam particles (pf16) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f16) could be obtained. The density of the recycled styrene-based resin foam molded article (f16) was 0.10 g / cm³. 3 The expansion ratio was 10 times.

[0162] [Example 17] In the same manner as in Example 3, recycled styrene resin particles (A17), recycled foamed styrene resin particles (17), and surface-treated recycled foamed styrene resin particles (17') were obtained. The expansion ratio is 40 times (bulk density 0.025 g / cm³). 3 Recycled styrene foam particles (pf17) were obtained in the same manner as in Example 1, except that 625g of recycled foamable styrene resin particles (17') were placed in a foamer and heated with steam for 2.5 minutes to induce foaming. The results are shown in Table 4. Furthermore, recycled styrene-based resin foam particles (pf17) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f17) could be obtained. The density of the recycled styrene-based resin foam molded article (f17) was 0.025 g / cm³. 3 The expansion ratio was 40 times.

[0163] [Example 18] In the same manner as in Example 3, recycled styrene resin particles (A18), recycled foamed styrene resin particles (18), and surface-treated recycled foamed styrene resin particles (18') were obtained. The bulk expansion ratio is 80 times (bulk density 0.013 g / cm³).3 Recycled styrene foam particles (pf18) were obtained in the same manner as in Example 1, except that 313g of recycled foamable styrene resin particles (18') were placed in a foamer and heated with steam for 4.5 minutes to induce foaming. The results are shown in Table 4. Furthermore, recycled styrene-based resin foam particles (pf18) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f18) could be obtained. The density of the recycled styrene-based resin foam molded article (f18) was 0.013 g / cm³. 3 The expansion ratio was 80 times.

[0164] [Example 19] In the same manner as in Example 3, recycled styrene resin particles (A19), recycled foamed styrene resin particles (19), and surface-treated recycled foamed styrene resin particles (19') were obtained. The expansion ratio is 100 times (bulk density 0.010 g / cm³). 3 Recycled styrene foam particles (pf19) were obtained in the same manner as in Example 1, except that 250g of recycled foamable styrene resin particles (19') were placed in a foamer and heated with steam for 5.5 minutes to induce foaming. The results are shown in Table 4. Furthermore, recycled styrene-based resin foam particles (pf19) were molded in the same manner as in Example 1, and it was confirmed that a recycled styrene-based resin foam molded article (f19) could be obtained. The density of the recycled styrene-based resin foam molded article (f19) was 0.010 g / cm³. 3 The expansion ratio was 100 times.

[0165] [Comparative Example 1] In the preparation of recycled styrene-based resin particles (A), the procedure was the same as in Example 3, except that butyl acrylate was not used in emulsion (1) (i.e., the amount of butyl acrylate was 0.00 kg) and the amount of styrene was changed to 1.7 kg. Recycled styrene-based resin particles (AC1), recycled foamable styrene-based resin particles (C1), and recycled foamed styrene-based resin particles (pfC1) were obtained. The results are shown in Table 4. Furthermore, recycled styrene-based resin foam particles (pfC1) were molded in the same manner as in Example 1 to obtain a recycled styrene-based resin foam molded article (fC1). The density of the recycled styrene-based resin foam molded article (fC1) was 0.017 g / cm³. 3 The expansion ratio was 60 times.

[0166] [Comparative Example 2] Except for not using divinylbenzene in the preparation of recycled styrene resin particles (A) (i.e., the amount of divinylbenzene in emulsion (1) was 0.00 g, and the amount of divinylbenzene in the above mixed solution added dropwise while gradually increasing the temperature from 75°C to 105°C was also 0.00 g), and the t-butyl peroxy-2-ethylhexanoate in emulsion (2) was changed to 122.7 g of benzoyl peroxide (purity 75.5%), the procedure was carried out in the same manner as in Example 3, and recycled styrene resin particles (AC2), recycled foamable styrene resin particles (C2), and recycled foamed styrene resin particles (pfC2) were obtained. The results are shown in Table 4. Furthermore, recycled styrene-based resin foam particles (pfC2) were molded in the same manner as in Example 1 to obtain a recycled styrene-based resin foam molded article (fC2). The density of the recycled styrene-based resin foam molded article (fC2) was 0.017 g / cm³. 3 The expansion ratio was 60 times. The results are shown in Table 4.

[0167] [Table 1]

[0168] [Table 2]

[0169] [Table 3]

[0170] [Table 4]

[0171] The abbreviations used in Tables 1-4 are as follows: TBEH: t-butylperoxy-2-ethylhexanoate TBEC: t-butylperoxy-2-ethylhexyl monocarbonate BPO: Benzoyl peroxide [Industrial applicability]

[0172] The recycled foamable styrene-based resin particles, recycled styrene-based resin foam particles, and recycled styrene-based resin foam molded articles according to embodiments of the present invention are suitably used as insulation materials for houses and automobiles, heat-insulating materials for building materials, transport packaging materials for fish boxes and food containers, cushioning materials, etc. More specifically, the recycled foamable styrene-based resin particles, recycled styrene-based resin foam particles, and recycled styrene-based resin foam molded articles according to embodiments of the present invention are suitably used as insulation materials for walls, floors, roofs, automobiles, hot water tanks, pipes, solar systems, water heaters, containers for food and industrial products (e.g., food containers such as fish boxes, returnable containers), cushioning materials, floats, blocks, packaging materials for fish and agricultural products, embankment materials (embankment blocks, etc.), tatami mat core materials, cushion core materials, concrete aggregates, etc.

Claims

1. Recycled foamable styrene resin particles obtained by pressurizing and impregnating recycled styrene resin particles (A) with a foaming agent, The bulk density of the regenerated styrene resin foam particles obtained by foaming the aforementioned regenerated foamable styrene resin particles is 0.0080 g / cm³. 3 ~0.20 g / cm 3 And, The volume retention rate of the recycled styrene-based resin foam particles, as measured by the following compression test, is 50% or more. Recycled foamed styrene resin particles. (Compression test) The recycled styrene foam particles, with a volume V1, filled in a container with an inner diameter of 50 mm, are compressed 100 times at a test speed of 10 mm / min, with an upper load limit of 267 N and a lower load limit of 1 N. After that, the recycled styrene foam particles are removed from the container and left to stand for 24 hours. The volume V2 of the recycled styrene foam particles after standing is measured. ΔV is calculated from V1 and V2 using equation (1). The average value of the ΔV measured over three times is taken as the volume retention rate. ΔV[%]=(V2 / V1)×100...(1)

2. The recycled styrene resin particles (A) are obtained by nuclear polymerization of a monomer composition (C) containing a styrene monomer, an acrylic acid ester monomer, and a polyfunctional vinyl monomer, using recycled styrene resin raw material particles (a) as a core, in the presence of a polymerization initiator. The polymerization initiator comprises at least one selected from the group consisting of peroxyester-based polymerization initiators and diacyl peroxide-based polymerization initiators. Recycled foamable styrene-based resin particles according to claim 1.

3. In the nuclear polymerization described above, the content of the acrylic acid ester monomer relative to the total amount of the recycled styrene resin raw material particles (a), the styrene monomer, and the acrylic acid ester monomer is 0.1% to 5% by mass. Recycled foamable styrene-based resin particles according to claim 2.

4. The weight-average molecular weight is between 280,000 and 1,100,000. Recycled foamable styrene-based resin particles according to claim 1.

5. Recycled styrene resin foamed particles obtained by foaming the recycled foamable styrene resin particles described in claim 1.

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

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