JP2022153315A - Expandable styrene resin particle, preliminary expandable styrene resin particle, styrenic resin expandable molding, and, manufacturing method of expandable styrenic resin particle - Google Patents

Abstract

To provide expandable styrenic resin particles high in environmental contribution, capable of developing excellent spheroidizing and excellent in moldability and its manufacturing method, a pre-expanded styrenic resin particles obtained from such expandable styrenic resin particles, and a styrenic resin foam molding molded from such expandable styrenic resin particles or pre-expanded styrenic resin particles.SOLUTION: Expandable styrenic resin particles are expandable styrenic resin particles obtained by injecting a volatile blowing agent into the styrenic resin particles (A) obtained by adding a styrene-based monomer to the recycled styrenic resin particles and polymerizing them. wherein a content of the regenerated styrene resin particles with respect to a total amount of the regenerated styrene resin particles and the styrene monomer is 10 mass% to 90 mass%, an injection temperature when press fitting the volatile foaming agent is 40°C to 89°C.SELECTED DRAWING: None

Description

The present invention relates to expandable styrene-based resin particles, pre-expanded styrene-based resin particles, styrene-based resin foam molded articles, and methods for producing expandable styrene-based resin particles.

Due to its light weight, excellent heat insulation and mechanical strength, foam molded products are used as heat insulating materials for housing and automobiles, heat insulating materials for building materials, embankment materials for Styrofoam civil engineering construction methods, fish boxes and food products. It is widely used as a packing material for transportation such as containers and as a cushioning material. Among them, an in-mold expansion-molded product manufactured using expandable particles (typically, expandable polystyrene resin particles or pre-expanded styrene resin particles obtained by pre-expanding them) as a raw material can easily obtain a desired shape. It is widely used due to its advantages. Such a foamed molded product is composed of a plurality of foamed particles that are fused together.

On the other hand, the amount of plastic waste is increasing year by year. Most of the plastic waste is disposed of by incineration or landfill, but it is becoming a big social problem such as environmental pollution, global warming, and lack of landfill sites. For this reason, there is a strong social demand to reuse plastic waste, and various studies have been made on the recycling of plastic waste, such as the enactment of the Home Appliance Recycling Law. While various recycling methods have been proposed, material recycling, which reuses plastic waste as plastic components for products, is attracting attention from the viewpoint of resource circulation and environmental load reduction. , such material recycling is being considered.

As for the material recycling of styrene resin foam moldings, several methods have conventionally been proposed to obtain recycled expandable styrene resin particles by melting and extruding recovered raw materials to obtain recovered pellets, which are then impregnated with a foaming agent. It is

A method has been reported for obtaining recycled expandable styrene resin particles by impregnating recycled resin pellets formed from recovered styrene resin foam molded articles with a foaming agent at a temperature of 100° C. to 140° C. (Patent References 1, 2). There is also a report of a method of obtaining recycled expandable styrene resin particles by impregnating recycled resin pellets formed from recovered styrene resin foam molded articles with a foaming agent at a temperature of 90°C to 130°C. (Patent document 3).

A foaming agent is press-fitted into recycled resin pellets molded from recovered styrene-based resin foam molded articles at a temperature of 95°C to 130°C, then impregnated (in the example, the impregnation temperature is 118°C), and then 110°C. A method of obtaining recycled expandable styrene resin particles by spheroidizing particles at ~130° C. has been reported (Patent Document 4).

A styrene monomer is added to recycled resin pellets molded from recovered styrene resin foam molded articles, polymerized at 60° C. to 105° C., and then a foaming agent is injected (in the example, the injection temperature is 100° C.). and then impregnating with a foaming agent at an impregnation temperature of 100° C. or higher to obtain recycled expandable styrene resin particles (the content of recycled resin pellets is 70% by mass or less) has been reported (Patent Document 5). ). In addition, a styrene monomer is added to recycled resin pellets molded from recovered styrene resin foam molded products, polymerized at 60 ° C. to 105 ° C., and then a foaming agent is injected (in the example, the injection temperature is 100 ° C.), and then impregnating with a foaming agent at an impregnation temperature of 100° C. to 140° C., to obtain recycled expandable styrene resin particles (the content ratio of recycled resin pellets is 20% to 70% by mass). (Patent Document 6). In addition, a styrene monomer is added to recycled resin pellets molded from recovered styrene resin foam molded products, polymerized at 60 ° C. to 105 ° C., and then a foaming agent is injected (in the example, the injection temperature is 100 ° C.), and then impregnated with a foaming agent (in the example, the impregnation temperature is 115° C.) to obtain recycled expandable styrene resin particles (the content of recycled resin pellets is 30% by mass to 70% by mass). It has been reported that the flame retardant may be impregnated when impregnating the blowing agent (Patent Document 7). In addition, a styrene monomer is added to recycled resin pellets molded from recovered styrene resin foam molded products, polymerized at 60 ° C. to 105 ° C., and then a foaming agent is injected (in the example, the injection temperature is 100 ° C.), and then impregnating with a foaming agent at an impregnation temperature of 90° C. or higher to obtain recycled expandable styrene resin particles (the content ratio of recycled resin pellets is 20% to 70% by mass). (Patent Document 8).

However, the regenerated expandable styrene-based resin particles obtained by conventional methods have a particle shape that deviates from a spherical shape, have poor fillability into a molding die, and have poor elongation on the surface of a molded product. Also, there is a problem that the rate of fusion bonding between foamed grains of the molded article is low.

Japanese Patent No. 3044942 Japanese Patent No. 4234832 Japanese Patent No. 4261676 Japanese Patent No. 6788428 Japanese Patent No. 4052193 JP 2006-160905 A Japanese Patent No. 4912567 Japanese Patent No. 5128246

The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide expandable styrene resin particles that are highly environmentally friendly, can exhibit good spheroidization, and have excellent moldability. Another object of the present invention is to provide expandable styrene resin particles and a method for producing the same. Another object of the present invention is to provide pre-expanded styrene resin particles obtained from such expandable styrene resin particles. Another object of the present invention is to provide a styrene-based resin foam-molded article formed from such expandable styrene-based resin particles or pre-expanded styrene-based resin particles.

The expandable styrenic resin particles according to the embodiment of the present invention are
Expandable styrene resin particles obtained by injecting a volatile blowing agent into the styrene resin particles (A) obtained by adding a styrene monomer to the regenerated styrene resin particles and polymerizing them,
The content of the regenerated styrene resin particles with respect to the total amount of the regenerated styrene resin particles and the styrene monomer is 10% by mass to 90% by mass,
The injection temperature at which the volatile foaming agent is injected is 40°C to 89°C.

In one embodiment, the temperature for adding the styrene monomer is 40°C to 109°C.

In one embodiment, the recycled styrene-based resin particles are pellets obtained by a melt extrusion method.

In one embodiment, the pellets obtained by the melt extrusion method are extruded strand pellets obtained by extruding the used styrene foam resin with an extruder and cutting the strands, and extruding the used styrene foam resin with an extruder. Underwater cut pellets obtained by the underwater cutting method, which cuts the particles in water at the same time as they are extruded, and hot cuts, which are obtained by the hot cutting method in which used styrene foam resin particles are cut and cooled immediately after coming out of the extruder die. It is at least one selected from pellets.

In one embodiment, a flame retardant is added prior to injecting the volatile blowing agent.

The pre-expanded styrenic resin particles according to the embodiment of the present invention are
Pre-expanded styrene-based resin particles obtained by pre-expanding the expandable styrene-based resin particles,
The bulk expansion ratio of the pre-foaming is 2 to 150 times.

In one embodiment, the pre-expanded styrene-based resin particles are for a cushioning material.

A styrene-based resin foam molded article according to an embodiment of the present invention is formed from the expandable styrene-based resin particles.

A styrene-based resin foam molded article according to an embodiment of the present invention is formed from the pre-expanded styrene-based resin particles.

In one embodiment, the styrene-based resin foamed molded article is a molded body for embankment, a molded food container, a molded cushioning material, or a returnable box.

A method for producing expandable styrene-based resin particles according to an embodiment of the present invention comprises:
A step of adding a styrene-based monomer to the regenerated styrene-based resin particles and polymerizing them to obtain styrene-based resin particles (A), and a step of forcing a volatile blowing agent into the styrene-based resin particles (A). A method for producing expandable styrene resin particles, comprising
The content of the regenerated styrene resin particles with respect to the total amount of the regenerated styrene resin particles and the styrene monomer is 10% by mass to 90% by mass,
The injection temperature at which the volatile foaming agent is injected is 40°C to 89°C.

In one embodiment, the temperature for adding the styrene monomer is 40°C to 109°C.

In one embodiment, the recycled styrene-based resin particles are pellets obtained by a melt extrusion method.

In one embodiment, the pellets obtained by the melt extrusion method are extruded strand pellets obtained by extruding the used styrene foam resin with an extruder and cutting the strands, and extruding the used styrene foam resin with an extruder. Underwater cut pellets obtained by the underwater cutting method, which cuts the particles in water at the same time as they are extruded, and hot cuts, which are obtained by the hot cutting method in which used styrene foam resin particles are cut and cooled immediately after coming out of the extruder die. It is at least one selected from pellets.

According to the present invention, there are provided expandable styrene-based resin particles that contribute highly to the environment, can exhibit good spheroidization, and have excellent moldability, and a method for producing the same. can be done. Further, it is possible to provide pre-expanded styrene resin particles obtained from such expandable styrene resin particles. Moreover, it is possible to provide a styrene-based resin foam molded article formed from such expandable styrene-based resin particles or pre-expanded styrene-based resin particles.

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

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

≪≪A. Expandable Styrene Resin Particles>>>>
The expandable styrenic resin particles according to the embodiment of the present invention have a particle shape as a whole. The average particle size of the expandable styrene resin particles is preferably 0.40 mm to 2.0 mm, more preferably 0.6 mm to 1.8 mm. The average particle size can be measured according to JIS Z 8815. Specifically, the average particle size is a value measured as a particle size with an integrated value of 50% from the particle size distribution according to the JIS Z 8815 sieving test.

As the shape of the expandable styrene-based resin particles according to the embodiment of the present invention, any suitable shape can be adopted as long as the effects of the present invention are not impaired. Specific examples of such shapes include a spherical shape, a substantially spherical shape, and an elliptical spherical shape (oval shape). The shape of the expandable styrene-based resin particles according to the embodiment of the present invention is preferably spherical or substantially spherical, and more preferably spherical, from the viewpoint of exhibiting the effects of the present invention. However, in reality, it is difficult to distinguish between a spherical shape and a substantially spherical shape, so in this specification, both are collectively referred to as a spherical shape.

The weight average molecular weight of the expandable styrene-based resin particles according to the embodiment of the present invention is preferably 100,000 to 450,000, more preferably 110,000 to 400,000, still more preferably 120,000 to 350,000, Particularly preferably, it is 130,000 to 320,000.

The expandable styrene-based resin particles according to the embodiment of the present invention are obtained by injecting a volatile foaming agent into the styrene-based resin particles (A).

«A-1. Styrene-based resin particles (A)>>
The styrene-based resin particles (A) are obtained by adding a styrene-based monomer to the regenerated styrene-based resin particles and polymerizing them.

The regenerated styrene-based resin particles may be of only one type, or may be of two or more types.

As the regenerated styrene-based resin, any suitable regenerated styrene-based resin can be adopted as long as the effects of the present invention are not impaired. Such recycled styrene resins include, for example, polystyrene foam (molded products, block molded products, etc.), foam sheets (tray containers, broken sheet materials, etc.), home appliances, packaging containers, and cushioning materials (inside cushions). Filled foamed pellets) and recycled plastic materials used.

The regenerated styrene-based resin may contain any appropriate regenerated resin other than the regenerated styrene-based resin within a range that does not impair the effects of the present invention. Examples of such other recycled resins include AS resin, ABS resin, HIPS (high-impact polystyrene); polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polycarbonate (PC); nylon Polyamide resins such as (PA); polyethylene (linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), EVA (ethylene-vinyl acetate copolymer) The other resins may be one kind or two or more kinds.In this specification, the above-mentioned recycled resin of AS resin and recycled ABS resin are used. Resins and recycled HIPS (high-impact polystyrene) resins are not included in the above recycled styrene-based resins.

As the regenerated styrene-based resin, a molded article made from the trade name "Epsrem" manufactured by Sekisui Plastics Co., Ltd. may be used.

As the regenerated styrene-based resin particles, a pulverized product obtained by pulverizing a regenerated resin obtained by heating and/or reducing the volume of a used expanded styrene-based resin may be employed. The recycled styrene-based resin particles may be pellets obtained by extruding and pelletizing the pulverized material, or may be obtained by further pulverizing the pellets. Alternatively, the volume may be reduced and recovered using a solvent such as limonene.

The recycled styrene resin particles are preferably pellets obtained by melt extrusion. The melt extrusion method typically involves supplying a used styrene resin pulverized product, ingot, foamed particles, etc. to a resin supply device, melting it in the resin supply device, and exposing it to the tip of the resin supply device. In this method, pellets are obtained by extruding through small holes of an attached die and then cooling.

The pellets obtained by the melt extrusion method are preferably extruded strand pellets obtained by extruding the used styrene foam resin with an extruder and cutting the strands, and extruding the used styrene foam resin with an extruder. From underwater cut pellets obtained by the underwater cutting method, which simultaneously cuts in water, and hot-cut pellets obtained by the hot-cut method, which cuts and cools the used styrene foam resin particles immediately after coming out of the die of the extruder. At least one selected.

As the regenerated styrene-based resin particles, the pellets obtained by the above-mentioned melt extrusion method may be used as they are, or in order to obtain pellets of a smaller size, they are again subjected to so-called "mini-pelletization" by a melt extrusion method or the like. good too.

As for the recycled styrene resin particles, used foamed styrene resin is coarsely pulverized to an appropriate size according to need, and then subjected to thermal shrinkage, shrinkage by compression to break air bubbles, shrinkage by frictional heat, and melting. It may be a contracted product or a melted product of expanded styrene resin.

Examples of the used foamed styrene-based resin include a molded article obtained by molding an expandable styrene-based resin with a mold, and a product obtained by heating and foaming the same.

The recycled styrene resin particles can contain finely divided inorganic substances and/or organic lubricants. These may typically function as cell control agents.

Examples of finely powdered inorganic substances include talc, calcium carbonate, and silica. Here, talc typically refers to a mixture containing silicon oxide and magnesium oxide as main components and containing trace amounts of aluminum oxide, iron oxide, and the like.

The average particle size of the finely powdered inorganic material is preferably 100 μm or less, more preferably 30 μm or less. If the average particle size of the finely powdered inorganic material exceeds 100 μm, the effect of reducing the cell size of the pre-expanded styrene resin particles may be reduced.

The content of finely divided inorganic matter is preferably 0.1% by mass to 5% by mass, more preferably 0.5% by mass to 2% by mass, relative to the recycled styrene resin particles. If the content ratio of the fine powdery inorganic material to the regenerated styrene resin particles is less than 0.1% by mass, the effect of reducing the cell size of the pre-expanded styrene resin particles may decrease. If the content ratio of the fine powder inorganic matter to the recycled styrene resin particles exceeds 5% by mass, the cell size of the pre-expanded styrene resin particles becomes extremely small, and the pre-expanded styrene resin particles melt during molding. The appearance of the molded product may deteriorate.

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

The content of the organic lubricant is preferably 0.01% by mass to 2.0% by mass, more preferably 0.02% by mass to 1.8% by mass, relative to the recycled styrene resin particles, Depending on the case, it is more preferably 0.02% by mass to 0.2% by mass, and particularly preferably 0.02% by mass to 0.1% by mass. If the content of the organic lubricant with respect to the recycled styrene resin particles is less than 0.01% by mass, the effect of reducing the cell size of the pre-expanded styrene resin particles may be reduced. If the content ratio of the organic lubricant to the recycled styrene resin particles exceeds 2.0% by mass, the cell size of the pre-expanded styrene resin particles becomes extremely small, and the pre-expanded styrene resin particles melt during molding. Mold appearance tends to be poor.

A specific method for incorporating a finely divided inorganic material and/or an organic lubricant into the regenerated styrene resin particles is, for example, a method of kneading a finely divided inorganic material and/or an organic lubricant during extrusion molding. be done. In this case, preferably, the pulverized material and the cell control agent are mixed in advance and then extruded. Any appropriate method can be used to mix the pulverized material and the cell adjustment agent within a range that does not impair the effects of the present invention. Examples of such a method include a mixing method using a mixer such as a tumbler, a ribbon blender, a V blender, a Henschel mixer, and a Roedige mixer.

The recycled styrene-based resin particles are preferably heat-melted for the purpose of adjusting the specific gravity. In this step, the specific gravity of the regenerated styrene-based resin particles is adjusted to preferably 0.6 or more, more preferably 0.9 or more. If the specific gravity of the regenerated styrene resin particles is less than 0.6, the dispersed regenerated styrene resin particles are unstable, and excessively large particles may be generated during the subsequent polymerization step, resulting in a decrease in yield. Thermal melting of the regenerated styrene-based resin particles can be performed by any appropriate method as long as the effects of the present invention are not impaired. Examples of such a method include a method using an extruder and a hot roll. Thermal melting is preferably carried out by cooling and solidifying the obtained resin in a state in which no distortion remains or the distortion is small. If the strain remains in the resin particles, the strain will be relaxed in the subsequent steps, shrinking in the drawing direction, and the resulting expandable styrene resin particles may become flat rather than spherical. Therefore, as heat melting, non-stretching melting using an extruder is preferable. If hot melting is performed in a stretched state, strain may remain in the stretched resin obtained by cooling and solidifying. Even if the resin remains strained by heat melting, the strain can be relaxed by curing for a certain period of time at a temperature higher than the softening point of the resin.

Any pulverizer may be used for the pulverization to obtain the regenerated styrene resin particles as long as the effects of the present invention are not impaired. As such a grinder, for example, a grinder for plastics can be employed, and a grinder for polystyrene is preferable.

The recycled styrene-based resin particles can be sieved as necessary and subjected to melting by an extruder or the like again.

The average particle size of the regenerated styrene resin particles is preferably 0.2 mm to 3.0 mm, more preferably 0.3 mm to 2.5 mm, still more preferably 0.4 mm to 2.0 mm, particularly It is preferably 0.5 mm to 1.7 mm. If the average particle size of the regenerated styrene resin particles exceeds 3 mm, it may be difficult for the expandable styrene resin particles to be obtained to have a spherical shape. If the average particle size of the recycled styrene-based resin particles is less than 0.2 mm, the average particle size of the expandable styrene-based resin particles obtained may be too small.

L (long side)/D (short side) of the regenerated styrene resin particles is preferably 1.0 to 6.0, more preferably 1.0 to 5.0, still more preferably 1.0. ~4.0, particularly preferably 1.0 to 3.0, most preferably 1.0 to 2.5. If the L (longer side)/D (shorter side) ratio of the recycled styrene resin particles is out of the above range, the shape of the resulting expandable styrene resin particles may not be spherical.

The recycled styrene-based resin particles preferably contain less than 1% by mass of particles having an average particle diameter of 200 μm or less. When the content of particles having an average particle size of 200 μm or less is 1% by mass or more, the appearance of the expandable styrene resin particles obtained using the recycled styrene resin particles may deteriorate.

The weight average molecular weight of the recycled styrene resin particles is preferably 100,000 to 510,000, more preferably 100,000 to 490,000, still more preferably 100,000 to 400,000, and particularly preferably 150,000 to 35,000. Ten thousand. If the weight-average molecular weight of the recycled styrene-based resin particles is less than 100,000, sufficient strength may not be obtained. If the weight-average molecular weight of the recycled styrene-based resin particles exceeds 510,000, the recycled styrene-based resin particles may be difficult to form a spherical shape, or the appearance of the molded product may be deteriorated due to a decrease in expandability.

Only one type of styrene-based monomer may be used, or two or more types may be used.

Styrenic monomers include styrene or styrene derivatives. Examples of styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromostyrene and the like. Only one type of styrene-based monomer may be used, or two or more types may be used. The styrenic monomer preferably contains at least styrene. The content of styrene with respect to the total amount of styrene-based monomers is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. is.

The styrene monomer may contain any appropriate vinyl monomer other than the styrene monomer as long as the effects of the present invention are not impaired. Examples thereof include polyfunctional monomers, (meth)acrylic acid ester monomers, maleic acid ester monomers, and fumaric acid ester monomers. Only one such vinyl monomer may be used, or two or more thereof may be used.

Specific examples of polyfunctional monomers include divinylbenzenes such as o-divinylbenzene, m-divinylbenzene and p-divinylbenzene; alkylenes such as ethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate; glycol di(meth)acrylate; Specific examples of (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylic acid. Examples include pentyl, 2-ethylhexyl (meth)acrylate, and hexyl (meth)acrylate. Maleic ester monomers include, for example, dimethyl maleate. Examples of fumarate ester monomers include dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

The content of the regenerated styrene resin particles with respect to the total amount of the regenerated styrene resin particles and the styrene monomer is preferably 10% by mass to 90% by mass, more preferably 15% by mass to 85% by mass. , more preferably 20% to 80% by mass, particularly preferably 25% to 80% by mass, and most preferably 30% to 80% by mass. If the content is too small outside the above range, the environmental contribution may be lowered. On the other hand, if the content is outside the above range and is too small or too large, the expandable styrene-based resin particles according to the embodiment of the present invention may not exhibit good spheroidization, resulting in a decrease in moldability. There is a risk.

The styrene-based resin particles (A) are obtained by adding a styrene-based monomer to the regenerated styrene-based resin particles and polymerizing them. As such a polymerization method, any appropriate method can be adopted as long as the effects of the present invention are not impaired. As one preferred embodiment of such a polymerization method, an emulsion containing a polymerization initiator and a styrenic monomer is added to a suspension obtained by dispersing regenerated styrenic resin particles as nuclei in an aqueous medium. A method of adding a liquid to impregnate the regenerated styrene-based resin particles, then adding a styrene-based monomer, and conducting polymerization can be mentioned.

When the styrenic resin particles (A) are obtained, the addition temperature when adding the styrenic monomer to the regenerated styrenic resin particles is preferably 40° C. to 109° C., in order to further express the effects of the present invention. °C, more preferably 60°C to 108°C, still more preferably 65°C to 107°C, and particularly preferably 70°C to 106°C. If the addition temperature when adding the styrene-based monomer to the regenerated styrene-based resin particles is adjusted within the above range, the styrene-based monomer can be incorporated while maintaining the appropriate hardness of the regenerated styrene-based resin particles. , good spheroidization of the styrene-based resin particles (A) can be achieved, and good spheroidization and excellent moldability of the finally obtained expandable styrene-based resin particles can be exhibited. If the addition temperature when adding the styrene-based monomer to the regenerated styrene-based resin particles is too low outside the above range, the regenerated styrene-based resin particles become too hard, and the styrene-based monomer is taken in in this state. In this case, the styrene-based resin particles (A) are difficult to be sphericalized, and the expandable styrene-based resin particles finally obtained may be difficult to be spherically-shaped and may be inferior in moldability. If the addition temperature when adding the styrene-based monomer to the regenerated styrene-based resin particles is too high outside the above range, the regenerated styrene-based resin particles become too soft, and the styrene-based monomer is taken in in this state. In this case, the styrene-based resin particles (A) are difficult to be sphericalized, and the expandable styrene-based resin particles finally obtained may be difficult to be spherically-shaped and may be inferior in moldability. It should be noted that the "addition temperature when adding the styrene monomer to the regenerated styrene resin particles" here refers to the addition of the emulsion containing the polymerization initiator and the styrene monomer, and the subsequent addition of the styrene monomer. It means the addition temperature throughout the addition of the monomer.

When a suspension is obtained by dispersing the regenerated styrene-based resin particles as nuclei in an aqueous medium, the method for dispersing the regenerated styrene-based resin particles in the aqueous medium may be as long as the effects of the present invention are not impaired. Any suitable method can be adopted. A preferred method for such dispersion is dispersion using a device equipped with a stirring blade. As a method for finer dispersion, a method using a homomixer may be mentioned.

When the regenerated styrene-based resin particles are dispersed in the aqueous medium as nuclei to obtain a suspension, it is preferable to use a dispersant in dispersing the regenerated styrene-based resin particles in the aqueous medium. Any appropriate dispersant can be employed as long as it can be used in suspension polymerization, as long as it does not impair the effects of the present invention. Examples of such dispersants include organic dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, and methyl cellulose; sparingly soluble inorganic salts such as magnesium phosphate, magnesium pyrophosphate, and tricalcium phosphate; interface dispersants such as sodium dodecylbenzenesulfonate. active agents; Among these, magnesium pyrophosphate is preferable as the dispersant in that the effects of the present invention can be exhibited more effectively.

Any appropriate method can be adopted as the method of emulsification when obtaining an emulsion containing a polymerization initiator and a styrenic monomer as long as the effects of the present invention are not impaired. A preferred method for such dispersion is dispersion using a device equipped with a stirring blade. As a method for finer dispersion, a method using a homomixer may be mentioned. At this time, it is preferable to disperse until the diameter of the oil droplets in the dispersion liquid in which the styrene-based monomer is dispersed is equal to or less than the particle diameter of the core. When the oil droplets are added to the aqueous medium in a state in which the diameter of the oil droplets is larger than the particle diameter of the core, a plurality of recycled styrene resin particles are incorporated into the oil droplets of the dispersed styrene-based monomer dispersion, resulting in a regenerated styrene-based resin. This is because adhesion, plasticization, and coalescence of resin particles occur, and excessively large particles tend to occur.

As the polymerization initiator used to obtain the emulsion containing the polymerization initiator and the styrenic monomer, any appropriate polymerization initiator can be used as long as it is used in the suspension polymerization method, as long as it does not impair the effects of the present invention. Any polymerization initiator can be employed. Examples of such polymerization initiators include organic peroxides such as benzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate and t-butyl perbenzoate; azo compounds such as azobisisobutyronitrile; mentioned. Only one polymerization initiator may be used, or two or more polymerization initiators may be used.

The amount of the polymerization initiator used is preferably 0.1% by mass to 0.8% by mass, more preferably 0.1% by mass to 0.5% by mass, based on the styrene monomer.

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

As a method of adding the styrene-based monomer after impregnating the suspension containing the regenerated styrene-based resin particles with the emulsion containing the styrene-based monomer, as long as the effect of the present invention is not impaired, Any suitable method can be adopted. Such methods include, for example, divided addition and continuous addition. The rate of addition is appropriately selected according to the capacity, shape, polymerization temperature, etc. of the polymerization apparatus.

An emulsion containing a styrene-based monomer is added to a suspension containing regenerated styrene-based resin particles for impregnation, and then a styrene-based monomer is added. The polymerization reaction may continue for hours.

The suspension containing the regenerated styrene resin particles and the emulsion containing the styrene monomer may contain a cell control agent. Examples of such foam control agents include fatty acid monoamides such as oleic acid amide, stearic acid amide and hydroxystearic acid amide; fatty acid bisamides such as methylenebisstearic acid amide and ethylenebisstearic acid amide;

«A-2. Injection and impregnation of volatile blowing agent≫
The expandable styrene-based resin particles according to the embodiment of the present invention are obtained by injecting a volatile foaming agent into the styrene-based resin particles (A).

Only one kind of volatile foaming agent may be used, or two or more kinds thereof may be used.

As the volatile foaming agent, any suitable volatile foaming agent can be used as long as the effects of the present invention are not impaired. The volatile foaming agent is preferably an organic compound that has a boiling point below the softening point of the styrene resin and is gaseous or liquid at normal pressure. Specific examples include, for example, propane, n-butane, isobutane, pentane (n-pentane, isopentane, neopentane), n-hexane and other aliphatic hydrocarbons; cyclopentane, cyclopentadiene and other aliphatic hydrocarbons; acetone; , methyl ethyl ketone and other ketones; methanol, ethanol, isopropyl alcohol and other alcohols; dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether and other low-boiling ether compounds; trichloromonofluoromethane, dichlorodifluoromethane and other halogen-containing compounds hydrocarbon; and the like. Inorganic gases such as carbon dioxide, nitrogen, and ammonia may be used as the volatile foaming agent. Among these, the volatile foaming agent is preferably at least one selected from n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, and cyclopentadiene, in terms of being able to express the effects of the present invention more. It is one, more preferably at least one selected from n-butane, isobutane, n-pentane, and isopentane, and still more preferably at least one selected from n-pentane and isopentane.

The content of the volatile foaming agent can be appropriately set according to the purpose, as long as it is sufficient to form the pre-expanded styrene resin particles and the styrene resin foam molded article. The content of the volatile foaming agent is preferably 2 parts by mass to 15 parts by mass when the total amount of the recycled styrene resin particles and the styrene-based monomer is 100 parts by mass.

The temperature at which the volatile foaming agent is injected into the styrenic resin particles (A) is preferably 40°C to 89°C, more preferably 40°C to 88°C, still more preferably 40°C to 87°C, Especially preferred is 40°C to 86°C, most preferred is 40°C to 85°C. The temperature at which the volatile foaming agent is injected into the styrenic resin particles (A) may be varied within the above range. If the injection temperature of the volatile blowing agent into the styrene-based resin particles (A) is within the above range, the volatile blowing agent can be injected at a low temperature, and the volatile blowing agent is injected at such a low temperature. By raising the temperature later, the rapid impregnation of the styrene resin particles (A) with the volatile foaming agent is suppressed, and uniform impregnation becomes possible. It is possible to reduce the portions that shrink and melt. If the temperature at which the volatile blowing agent is injected into the styrene resin particles (A) is too low outside the above range, the styrene resin particles (A) will not be easily impregnated with the volatile blowing agent when the volatile blowing agent is injected. However, when the temperature is raised, the volatile blowing agent is rapidly impregnated, and the styrene resin particles (A) are not uniformly impregnated with the volatile blowing agent. There is a possibility that it may occur easily. If the injection temperature of the volatile blowing agent into the styrene resin particles (A) is too high outside the above range, the styrene resin particles (A) are rapidly impregnated with the volatile blowing agent when the volatile blowing agent is injected. As a result, the styrenic resin particles (A) are not uniformly impregnated with the volatile foaming agent, and air bubbles are likely to vary, and surface shrinkage during molding is likely to occur.

The temperature at which the volatile blowing agent is impregnated into the styrene resin particles (A) is preferably a temperature equal to or higher than the temperature at which the volatile blowing agent is injected into the styrene resin particles (A), preferably 93°C to 130°C. , more preferably 94°C to 129°C, still more preferably 95°C to 128°C, particularly preferably 96°C to 127°C, and most preferably 97°C to 126°C. The temperature at which the styrene resin particles (A) are impregnated with the volatile foaming agent may be varied within the above range. If the impregnation temperature of the styrene-based resin particles (A) with the volatile blowing agent is within the above range, the styrene-based resin particles (A) are rapidly impregnated with the volatile blowing agent in conjunction with the adjustment of the injection temperature. It is possible to suppress the squeezing and uniform impregnation, and for example, it is possible to reduce the portions that shrink and melt when molded into a styrenic resin foam molded article. If the impregnation temperature of the styrene-based resin particles (A) with the volatile blowing agent is too low outside the above range, the volatile blowing agent will not be impregnated to the center of the styrene-based resin particles (A), leaving a non-expanded portion. It may remain and it may not be possible to obtain a good molded product. If the temperature at which the styrene resin particles (A) are impregnated with the volatile foaming agent is too high outside the above range, the styrene resin particles (A) are too impregnated with the volatile foaming agent and melt during molding. There is a risk.

Any appropriate time can be adopted as the impregnation time of the styrene-based resin particles (A) with the volatile foaming agent as long as the effects of the present invention are not impaired. Such impregnation time is preferably 1 hour to 10 hours.

<<A-3. Other ingredients≫
The expandable styrene-based resin particles according to the embodiment of the invention may contain any appropriate other component within a range that does not impair the effects of the invention. Only one such component may be used, or two or more components may be used.

The expandable styrenic resin particles according to the embodiment of the present invention may contain a flame retardant in order to enhance flame retardancy. Only one kind of flame retardant may be used, or two or more kinds thereof may be used.

As the flame retardant, any appropriate flame retardant can be adopted as long as it does not impair the effects of the present invention. As such a flame retardant, a bromine compound compatible with polystyrene is preferable. bisphenol F, tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tetrabromobisphenol A-diglycidyl ether, 2, 2-bis[4′(2″,3″-dibromoalkoxy)-3′,5′-dibromophenyl]-propane, tris(tribromophenoxy)triazine, 2,2-bis(4-allyloxy-3 ,5-dibromo)propane and hexabromobenzene.

When using a flame retardant, you may use a flame-retardant adjuvant together. Examples of flame retardant aids include cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenyl Hexane is mentioned.

Any appropriate amount can be adopted as the total amount of the flame retardant and the auxiliary flame retardant to be used as long as the effects of the present invention are not impaired. The amount used is preferably 0.1% by mass to 5% by mass, more preferably 0.2% by mass to 3% by mass, based on the recycled styrene resin particles.

The flame retardant may be added at any suitable timing as long as the effects of the present invention are not impaired. The flame retardant is preferably added before the volatile foaming agent is injected, in order to make the effects of the present invention more manifest. By adding the flame retardant before injecting the volatile blowing agent, the flame retardant can be added at a temperature as low as the temperature at which the volatile blowing agent is injected. Good spheroidization and excellent moldability can be expressed.

The temperature at which the flame retardant is added is preferably 40° C. to 89° C., more preferably 40° C. to 87° C., and still more preferably 40° C. to 89° C., from the viewpoint that the effects of the present invention can be further exhibited. 85°C, particularly preferably 40°C to 83°C, most preferably 40°C to 80°C.

In producing the expandable styrene-based resin particles according to the embodiment of the present invention, a partial ester of a higher fatty acid and an alcohol may be used as a cell control agent. That is, the expandable styrene-based resin particles according to the embodiment of the present invention may contain partial esters of higher fatty acids and alcohols. Partial esters of higher fatty acids and alcohols may be of one type or two or more types. Examples of higher fatty acids include fatty acids having 15 or more carbon atoms such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and behenic acid, and their monoglycerides and diglycerides can be used. Preferred partial esters of higher fatty acids and alcohols include monoglyceride stearate and diglyceride stearate. The content of the partial ester of higher fatty acid and alcohol is preferably 0 parts by mass to 3.0 parts by mass, more preferably 0.5 parts by mass to 3.0 parts by mass, based on 100 parts by mass of the expandable styrene resin particles. It is 0 parts by mass. As a method of adding the higher fatty acid and alcohol partial ester, for example, addition together with a volatile foaming agent, or a commonly used method such as a dry blending method, a masterbatch method, or a melt injection method can be employed.

A foaming aid may be used in producing the expandable styrene-based resin particles according to the embodiment of the present invention. That is, the expandable styrene-based resin particles according to the embodiment of the present invention may contain a foaming aid. The number of foaming assistants may be one, or two or more may be used. Foaming aids include, for example, diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, and coconut oil.

In producing the expandable styrenic resin particles according to the embodiment of the present invention, a cell control agent may be used. That is, the expandable styrenic resin particles according to the embodiment of the present invention may contain a cell control agent. Only one kind of cell adjusting agent may be used, or two or more kinds thereof may be used. Examples of foam control agents include fatty acid monoamides such as oleic acid amide, stearic acid amide and hydroxystearic acid amide; fatty acid bisamides such as methylenebisstearic acid amide and ethylenebisstearic acid amide;

Expandable styrenic resin particles according to embodiments of the present invention may contain cell modifiers such as talc, calcium carbonate, mica, citric acid, sodium bicarbonate, and the like. Only one kind of cell adjusting agent may be used, or two or more kinds thereof may be used.

Other additives include, in addition to these, pigments, radiation heat transfer suppressing components, cross-linking agents, plasticizers, stabilizers, fillers, lubricants, coloring agents, antistatic agents, spreading agents, weathering agents, Anti-aging agents, anti-fogging agents, perfumes.

«A-4. Surface treatment≫
The expandable styrene-based resin particles according to the embodiment of the present invention may be subjected to surface treatment. Such surface treatment is preferably surface treatment with at least one selected from silicone oil, antistatic agent, fatty acid metal salt, and fusion promoter.

When the expandable styrene resin particles according to the embodiment of the present invention are surface-treated with silicone oil, the amount of silicone oil used relative to 100 parts by mass of the expandable styrene resin particles before the surface treatment is preferably 0.5 parts by mass. 001 parts by mass to 0.3 parts by mass, more preferably 0.003 parts by mass to 0.28 parts by mass, still more preferably 0.005 parts by mass to 0.25 parts by mass, particularly preferably 0 0.008 to 0.23 parts by weight, most preferably 0.01 to 0.23 parts by weight. If the amount of silicone oil used is too small outside the above range, for example, when an antistatic agent is used, the affinity with the antistatic agent will be insufficient during preliminary foaming, and static electricity may easily occur. If the amount of silicone oil used is too large outside the above range, the surface properties may be lost due to melting of the surface during molding.

Only one type of silicone oil may be used, or two or more types may be used.

As the silicone oil, any appropriate silicone oil can be adopted as long as the effects of the present invention are not impaired. From the point of view that the effects of the present invention can be more expressed, the silicone oil includes, for example, straight silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane, preferably methylphenylpolysiloxane. be.

When the expandable styrene resin particles according to the embodiment of the present invention are surface-treated with an antistatic agent, the amount of the antistatic agent used relative to 100 parts by mass of the expandable styrene resin particles before the surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, still more preferably 0.01 to 0.27 parts by mass, particularly preferably is 0.015 to 0.26 parts by weight, most preferably 0.02 to 0.25 parts by weight. If the amount of the antistatic agent is too small outside the above range, static electricity may be likely to be generated during prefoaming. If the amount of the antistatic agent is out of the above range and is too large, the surface of the pre-expanded styrene resin particles or the styrene resin foam molded product may become sticky.

Only one kind of antistatic agent may be used, or two or more kinds thereof may be used.

As the antistatic agent, any appropriate antistatic agent can be employed as long as the effects of the present invention are not impaired. The antistatic agent includes at least one selected from nonionic surfactants and fatty acid glycerides, preferably in combination with nonionic surfactants and fatty acid glycerides, from the viewpoint that the effects of the present invention can be more expressed. be.

Only one type of nonionic surfactant may be used, or two or more types may be used.

As the nonionic surfactant, any suitable nonionic surfactant can be adopted as long as the effects of the present invention are not impaired. Examples of nonionic surfactants that can further express the effects of the present invention include polyethylene glycol, glycerin, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyhydric alcohols, 1-amino-2-hydroxy compound. 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. Specific examples of 1-amino-2-hydroxy compounds include N-hydroxyethyl-N-(2-hydroxyalkyl)amine, N,N-bis(hydroxyethyl)dodecylamine, N,N-bis (Hydroxyethyl)tetradecylamine, N,N-bis(hydroxyethyl)hexadecylamine, N,N-bis(hydroxyethyl)octadecylamine, N-hydroxyethyl-N-(2-hydroxytetradecyl)amine, N- Hydroxyethyl-N-(2-hydroxyhexadecyl)amine, N-hydroxyethyl-N-(2-hydroxyoctadecyl)amine, N-hydroxypropyl-N-(2-hydroxytetradecyl)amine, N-hydroxybutyl- N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxyhexadecyl)amine, N-hydroxypentyl-N- (2-hydroxyoctadecyl)amine, N,N-bis(2-hydroxyethyl)dodecylamine, N,N-bis(2-hydroxyethyl)tetradecylamine, N,N-bis(2-hydroxyethyl)hexadecyl amines, N,N-bis(2-hydroxyethyl)octadecylamine, salts thereof; Polyethylene glycol is preferable as the nonionic surfactant in that the effects of the present invention can be expressed more effectively.

When a nonionic surfactant is employed as at least part of the antistatic agent, the amount of the nonionic surfactant used relative to 100 parts by mass of the expandable styrene resin particles before surface treatment is preferably 0.001 parts by mass to 2.0 parts by mass, more preferably 0.001 to 1.5 parts by mass, still more preferably 0.001 to 1.0 parts by mass, still more preferably 0.001 parts by mass 0.5 parts by mass, more preferably 0.001 parts by mass to 0.3 parts by mass, more preferably 0.005 parts by mass to 0.28 parts by mass, still more preferably 0.01 parts by mass parts to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of the nonionic surfactant is too small outside the above range, static electricity may be likely to be generated during prefoaming. If the amount of the nonionic surfactant is outside the above range and is too large, the surface of the pre-expanded styrene resin particles or the styrene resin foam molded article may become sticky.

Only one type of fatty acid glyceride may be used, or two or more types may be used.

As the fatty acid glyceride, any appropriate fatty acid glyceride can be adopted as long as the effects of the present invention are not impaired. Specific examples of the fatty acid glyceride include stearic acid monoglyceride and linoleic acid monoglyceride in that the effects of the present invention can be expressed more effectively. As the fatty acid glyceride, stearic acid monoglyceride is preferable in that the effect of the present invention can be expressed more effectively.

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

When the expandable styrene resin particles according to the embodiment of the present invention are surface-treated with a fatty acid metal salt, the amount of the fatty acid metal salt used relative to 100 parts by mass of the expandable styrene resin particles before the surface treatment is preferably 0.005 parts by mass to 0.5 parts by mass, more preferably 0.007 parts by mass to 0.45 parts by mass, still more preferably 0.01 parts by mass to 0.4 parts by mass, particularly preferably is 0.015 to 0.35 parts by weight, most preferably 0.02 to 0.3 parts by weight. If the amount of the fatty acid metal salt is outside the above range and is too small, a large amount of blocking occurs during pre-foaming, and there is a risk that a good styrene-based resin foam-molded article cannot be obtained. If the amount of the fatty acid metal salt is out of the above range and is too large, a large amount of the metal salt will be present during pre-foaming, which will tend to cause electrification and static electricity to occur, possibly resulting in poor fusion of the molded product. .

Fatty acid metal salts may be used alone or in combination of two or more.

As the fatty acid metal salt, any appropriate fatty acid metal salt can be adopted as long as the effect of the present invention is not impaired. Examples of the fatty acid metal salt include metal stearate and metal laurate, since the effects of the present invention can be expressed more effectively. Specific examples of metal stearates include magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate. Specific examples of metal laurate include zinc laurate and barium laurate. Magnesium stearate and zinc stearate are preferable as the fatty acid metal salt in that the effect of the present invention can be more expressed.

When the expandable styrene-based resin particles according to the embodiment of the present invention are surface-treated with a fusion promoter, the amount of the fusion promoter used with respect to 100 parts by mass of the expandable styrene-based resin particles before the surface treatment is preferably 0.01 to 0.8 parts by mass, more preferably 0.01 to 0.7 parts by mass, still more preferably 0.01 to 0.6 parts by mass, Especially preferred is 0.01 to 0.55 parts by mass, most preferred is 0.013 to 0.5 parts by mass. If the amount of the fusion promoter is too small, outside the above range, the fusion bondability may deteriorate during molding, and it may not be possible to obtain a good styrenic resin foam molded article. If the amount of the fusion promoter is too large outside the above range, blocking may occur during prefoaming.

The fusion accelerator may be used alone or in combination of two or more.

As the fusion promoter, any suitable fusion promoter can be employed as long as the effects of the present invention are not impaired. Examples of the fusion promoter include fatty acid triglycerides, fatty acid diglycerides, fatty acid monoglycerides, and vegetable oils from the viewpoint that the effects of the present invention can be more expressed. Specific examples of fatty acid triglycerides include lauric acid triglyceride, stearic acid triglyceride, linoleic acid triglyceride, and hydroxystearic acid triglyceride. Specific examples of fatty acid diglycerides include lauric acid diglyceride, stearic acid diglyceride, and linoleic acid diglyceride. Specific examples of fatty acid monoglycerides include lauric acid monoglyceride. Specific examples of vegetable oils include hydrogenated castor oil. As the fusion promoter, stearic acid triglyceride and hydroxystearic acid triglyceride are preferable in that the effect of the present invention can be expressed more effectively.

<<A-5. Method for Producing Expandable Styrenic Resin Particles>>
The expandable styrene-based resin particles according to the embodiment of the invention can be produced by any suitable method as long as the effects of the invention are not impaired. In the point that the effect of the present invention can be further expressed, the method for producing expandable styrene resin particles according to the embodiment of the present invention includes adding a styrene monomer to the recycled styrene resin particles and polymerizing the styrene resin. A method for producing expandable styrene-based resin particles, comprising a step of obtaining particles (A) and a step of forcing a volatile foaming agent into the styrene-based resin particles (A), wherein the recycled styrene-based resin particles and the content of the recycled styrene resin particles with respect to the total amount of the styrene monomer is 10% by mass to 90% by mass, and the injection temperature when the volatile blowing agent is injected is 40°C to 89°C. be.

The step of adding a styrene-based monomer to the regenerated styrene-based resin particles and polymerizing them to obtain the styrene-based resin particles (A) is typically described in <<A-1. The description in the section of styrene-based resin particles (A)>> may be used.

The step of injecting the volatile foaming agent into the styrene-based resin particles (A) is typically described in <<A-2. The description in the section "Injection and Impregnation of Volatile Blowing Agents" can be used.

≪≪B. Pre-expanded styrene resin particles>>>>
The pre-expanded styrene resin particles are obtained by pre-expanding expandable styrene resin particles.

The pre-expanded styrene resin particles have an average cell diameter of preferably 0.02 mm to 0.80 mm, more preferably 0.03 mm to 0.70 mm, still more preferably 0.03 mm to 0.60 mm. , particularly preferably 0.03 mm to 0.50 mm, most preferably 0.03 mm to 0.40 mm. If the average cell diameter of the pre-expanded styrene-based resin particles is within the above range, blocking during foaming and molding can be further prevented, and electrification properties during foaming and molding can be further suppressed while providing better fusion bondability. It is possible to provide pre-expanded styrenic resin particles that exhibit surface properties and are capable of molding styrenic resin foamed articles with less static electricity. If the average cell diameter of the pre-expanded styrene resin particles is less than 0.02 mm, the surface may melt and shrink during molding.

The pre-expanded styrene resin particles according to the embodiment of the present invention are obtained by pre-expanding expandable styrene resin particles. Pre-expansion includes expanding expandable styrene-based resin particles to a desired bulk expansion ratio (bulk density) using steam or the like. The bulk expansion ratio of the pre-expanded styrene resin particles is preferably 2 to 150 times, more preferably 2 to less than 100 times, more preferably 5 to 90 times, still more preferably 10 times. to 85 times, particularly preferably 15 to 83 times. Bulk density is the reciprocal of bulk expansion ratio. When the bulk expansion ratio of the pre-expanded styrene resin particles is within the above range, blocking during foaming and molding can be further prevented, and electrification during foaming and molding can be further suppressed while achieving better melting. It is possible to provide pre-expanded styrene resin particles that exhibit adhesiveness and surface properties and can be used to form styrene resin foam molded articles with less static electricity.

In one representative embodiment, the pre-expanded styrene-based resin particles can be used for molding a styrene-based resin foam molded article. In another embodiment, the pre-expanded styrene-based resin particles can be used as they are as a cushioning material, a heat insulating material, or the like. When the pre-expanded styrene-based resin particles are used as they are, the pre-expanded styrene-based resin particles can preferably be used as a filling body in which a large number of pre-expanded styrene-based resin particles are filled in a bag. Such pre-expanded styrene-based resin particles are suitable for, for example, a cushion material (expanded particles filling the inside of the cushion). That is, one embodiment of the pre-expanded styrene-based resin particles according to the embodiment of the present invention is for cushion materials.

<<<C. Styrene-based resin foam molded products>>>>
A styrene resin foam molded article according to one embodiment of the present invention is a styrene resin foam molded article formed from expandable styrene resin particles. A styrene-based resin foam molded article according to another embodiment of the present invention is a styrene-based resin foam-molded article molded from pre-expanded styrene-based resin particles obtained by pre-expanding expandable styrene-based resin particles.

A styrene-based resin foam molded article typically contains expanded styrene-based resin particles (hereinafter sometimes simply referred to as "expanded particles") obtained by further expanding pre-expanded styrene-based resin particles.

A styrene-based resin foam molded article is typically composed of a plurality of foamed particles that are fused together.

A styrene-based resin foam-molded product can typically be produced by charging pre-expanded styrene-based resin particles into a mold having a predetermined shape according to the purpose and performing in-mold foam molding. More specifically, in-mold foam molding includes (i) filling pre-expanded styrene resin particles into a closed mold having a large number of small holes, (ii) heating with a heat medium (for example, pressurized steam). (iii) filling the voids between the expanded particles by heating and expanding the expanded styrenic resin particles to obtain the expanded particles, and by fusing the expanded particles to each other to integrate them; . The density of the styrenic resin foam molded article can be appropriately set according to the purpose. The density of the styrene resin foam molded product can be adjusted, for example, by adjusting the bulk expansion ratio of the pre-expanded styrene resin particles filled in the mold in advance, or by adjusting the filling amount of the pre-expanded styrene resin particles in the mold. can be adjusted by adjusting

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

If necessary, the pre-expanded styrene resin particles may be aged before molding the styrene resin foam molded article. The aging temperature of the pre-expanded styrene resin particles is preferably 20°C to 60°C. If the aging temperature is too low, excessively long aging times may be required. If the aging temperature is too high, the foaming agent in the pre-expanded styrene-based resin particles may dissipate and the moldability may deteriorate.

The expansion ratio of the expanded particles in the styrene-based resin foamed article is preferably 2 times or more and less than 110 times, more preferably 5 times to 90 times, still more preferably 10 times to 85 times, and particularly preferably 15 times. ~80 times.

The styrenic resin foam molded product according to the embodiment of the present invention is lightweight and excellent in heat insulation and mechanical strength. Insulation materials, insulation materials for piping, insulation materials for solar systems, insulation materials for water heaters, containers for food and industrial products (e.g. food containers such as fish boxes, returnable boxes), cushioning materials, floats, blocks, fish and agricultural products etc., embankment materials (embankment moldings, embankment blocks, etc.), core materials of tatami mats, core materials of cushions, concrete aggregates, and the like. Preferred examples of the styrene-based resin foam molded article according to the embodiment of the present invention are embankment molded articles, food container molded articles, cushioning material molded articles, and returnable box molded articles.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. The measurement method and evaluation method for each characteristic are as follows.

<Evaluation of spheroidization>
Take any 10 expandable styrene resin particles or styrene resin particles, calculate the ratio of the long side (L) and the short side (D), and calculate the sphericity with respect to the ratio by the following formula. and evaluated according to the following criteria.
Sphericality = 1/(L/D)
○: 1 / (L / D) = 0.9 or more △: 1 / (L / D) = 0.7 or more and less than 0.9 ×: 1 / (L / D) = less than 0.7

<Moldability>
Comprehensive judgment was made based on the elongation of the surface of the molded body and the rate of fusion bonding between foamed grains when the molded body was broken. The surface elongation of the molded article was evaluated by visually observing the appearance of the obtained foamed molded article. Specifically, the state of the boundary portion where the foamed particles were joined on the surface of the foamed molding was visually evaluated. In addition, evaluation of the fusion rate between foamed particles when the molded article was broken was performed by breaking the plate-shaped foamed molded article obtained by impact, and measuring the total number of expanded particles (A) on the fracture surface and the The number of broken particles (B) was counted, and the fusion rate (%) was calculated by the following formula.
Fusion rate (%) = {(B)/(A)} x 100
Evaluation was made according to the following criteria.
◯: Appearance is smooth and fusion rate is 70% or more.
Δ: Appearance is mostly smooth, but the boundary part is partially uneven, and the fusion rate is 60% or more and less than 70%.
x: The boundary portion of the appearance has unevenness, the smoothness is poor, and the fusion rate is less than 60%.

<Environmental Contribution>
Based on the content ratio of the regenerated styrenic resin particles to the total amount of the regenerated styrenic resin particles and the styrenic monomer as raw materials of the expandable styrenic resin particles, evaluation was made as follows.
○: The content of recycled styrene resin particles is 20% by mass or more △: The content of recycled styrene resin particles is 10% by mass or more and less than 20% by mass ×: The content of recycled styrene resin particles is less than 10% by mass

<Criteria for Comprehensive Evaluation>
Particularly good (◯): All items of evaluation of spheroidization, moldability, and degree of environmental contribution are ◯.
Good (Δ): One or more items of evaluation of spheroidization, moldability, and degree of environmental contribution have Δ, but no x.
Poor (×): Even one of the items of evaluation of spheroidization, formability, and degree of environmental contribution has an X.

<Measurement of bulk density and bulk expansion ratio of pre-expanded styrene resin particles>
The bulk density and bulk expansion ratio of the pre-expanded styrene resin particles were measured as follows.
(Method for measuring bulk density)
Pre-expanded styrene resin particles were used as a sample and allowed to fall naturally into a graduated cylinder, and then the bottom of the graduated cylinder was struck to keep the volume of the sample constant.
Bulk density (g/mL) = sample mass (g)/sample volume in graduated cylinder (mL)
(Method for measuring bulk expansion ratio)
Pre-expanded styrene resin particles were used as a sample and allowed to fall naturally into a graduated cylinder, and then the bottom of the graduated cylinder was struck to keep the volume of the sample constant. The resin specific gravity was set to 1.0 in the case of styrene resin.
Bulk expansion ratio (times)=Sample volume in measuring cylinder (mL)/Sample mass (g)×Resin specific gravity Note that the bulk expansion ratio may be calculated as the reciprocal of the bulk density.

<Measurement of Density and Expansion Magnification of Styrene-Based Resin Foam Mold>
(Method for measuring density)
The density of the styrene-based resin foam molding was calculated by the following formula after measuring the dimensions and mass of the test piece so that the dimensions and mass were three significant digits or more.
Density (g/cm ³ )=specimen mass (g)/specimen volume (cm ³ )
(Measurement method of expansion ratio)
The expansion ratio of the styrene-based resin foam molded product was calculated by the following formula after measuring the dimensions and mass of the test piece so that the size and mass were three significant digits or more. The resin specific gravity was set to 1.0 in the case of styrene resin.
Expansion ratio (times) = test piece volume (cm ³ )/test piece mass (g) x resin specific gravity

[Production Example 1]: Production of recycled styrene-based resin particles (A) using used polystyrene-based resin from home appliances as a raw material The used polystyrene-based resin from home appliances is supplied to a short-screw extruder and heated and melted at 200°C. Then, the regenerated styrene resin particles (A) were obtained by underwater cutting from the mold so as to have an average particle size of 0.95 mm (substantially spherical).

[Example 1]
<Production of expandable styrene resin particles>
38.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (1).
Separately, in a dispersion of 2 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 143 g of benzoyl peroxide (75% purity) as a polymerization initiator and 41 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 2 kg of the monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (1).
The above suspension (1) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (1) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80° C. for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after holding, 39 kg of styrene monomer was applied over 179 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
Separately, 23 g of ethylenebisstearic acid amide and 160 g of dicumyl peroxide were added to a dispersion of 3.5 kg of pure water, 0.8 g of sodium dodecylbenzenesulfonate, and 19 g of magnesium pyrophosphate, and the mixture was stirred with a homomixer to form an emulsion. An emulsion was prepared and this emulsion was added to the reactor cooled to 60°C. Ten minutes after this addition, 710 g of tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) were added. Stirring was continued at 60° C. for 30 minutes after the addition.
Subsequently, 2760 g of pentane (isopentane/normal pentane = 20% by mass/80% by mass) as a foaming agent was injected at an injection temperature of 60°C, held in that state for 15 minutes, and then heated to 100°C over 30 minutes. After that, the foaming agent was slowly impregnated by holding at 100° C. for 5 hours. After that, the temperature in the reactor was cooled to 30°C.
Thereafter, the content was taken out from the reactor, dehydrated, dried and classified to obtain expandable styrene resin particles (1).
<Surface treatment of expandable styrene resin particles>
40 kg of the obtained expandable styrene-based resin particles (1), 8 g of polyethylene glycol, 44 g of zinc stearate, 12 g of fatty acid triglyceride, and 16 g of fatty acid monoglyceride were put into a tumbler mixer, stirred for 30 minutes, and subjected to surface treatment. The treated expandable styrene resin particles (1') were obtained.
<Production of pre-expanded styrene resin particles>
The obtained expandable styrene-based resin particles (1′) were stored in a refrigerator at 15° C. for 7 days, then put into a cylindrical batch-type pressure foaming machine having a volume of 340 liters, and steamed for 2 minutes. It was heated to obtain pre-expanded styrene resin particles (1). The pre-expanded styrene resin particles (1) had a bulk density of 0.02 g/cm ³ and a bulk expansion ratio of 50 times.
<Preparation of styrene-based resin foam molding>
After leaving the obtained pre-expanded styrene resin particles (1) under room temperature for 24 hours, using a molding machine having a mold with a cavity size of 400 mm in height, 500 mm in width and 300 mm in depth, the cavity of the mold was The pre-expanded styrene resin particles (1) are filled inside, heated at a steam pressure of 0.04 MPa (gauge pressure) for 40 seconds, and then cooled until the pressure inside the mold reaches -0.002 MPa, The mold was released from the mold to obtain a block-shaped styrene-based resin foam molded article (1) corresponding to the mold. The styrene-based resin foam molded article (1) had a density of 0.02 g/cm ³ and an expansion ratio of 50 times. After that, the styrene-based resin foam molded article (1) was stored in a drying room at 50°C for one day.
Various evaluation results are shown in Table 1.

[Example 2]
36.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (2).
Separately, in a dispersion of 4 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 127 g of benzoyl peroxide (75% purity) as a polymerization initiator and 37 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 4 kg of the monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (3).
The above suspension (2) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (2) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80° C. for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after holding, 33 kg of styrene monomer was applied over 149 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (2), the surface-treated expandable styrene resin particles (2′), the pre-expanded styrene resin particles (2), and the expanded styrene resin particles A compact (2) was obtained.
Various evaluation results are shown in Table 1.

[Example 3]
34.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (3).
Separately, styrene prepared by dissolving 111 g of benzoyl peroxide (75% purity) as a polymerization initiator and 32 g of t-butylperoxy-2-ethylhexyl monocarbonate in a dispersion of 6 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate. 6 kg of the monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (3).
The above suspension (3) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (3) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after holding, 26 kg of the styrene monomer was added over 119 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (3), the surface-treated expandable styrene resin particles (3′), the pre-expanded styrene resin particles (3), and the expanded styrene resin particles A compact (3) was obtained.
Various evaluation results are shown in Table 1.

[Example 4]
32.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (4).
Separately, styrene prepared by dissolving 95 g of benzoyl peroxide (purity 75%) and 28 g of t-butylperoxy-2-ethylhexyl monocarbonate as a polymerization initiator in a dispersion of 8 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate. Emulsion (4) was prepared by adding 8 kg of a monomer and stirring with a homomixer to emulsify.
The above suspension (4) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (4) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80° C. for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after holding, 20 kg of the styrene monomer was applied over 90 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (4), the surface-treated expandable styrene resin particles (4′), the pre-expanded styrene resin particles (4), and the expanded styrene resin particles A compact (4) was obtained.
Various evaluation results are shown in Table 1.

[Example 5]
30.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (5).
Separately, in a dispersion of 10 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 79 g of benzoyl peroxide (75% purity) as a polymerization initiator and 23 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 10 kg of the monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (5).
The above suspension (5) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (5) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after holding, 13 kg of styrene monomer was added over 60 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (5), the surface-treated expandable styrene resin particles (5′), the pre-expanded styrene resin particles (5), and the expanded styrene resin particles A compact (5) was obtained.
Various evaluation results are shown in Table 1.

[Example 6]
28.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer. ) was added and suspended by stirring at 160 rpm to prepare a suspension (6).
Separately, in a dispersion of 12 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 63 g of benzoyl peroxide (purity 75%) as a polymerization initiator and 18 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 12 kg of the monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (6).
The above suspension (6) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (6) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after holding, 7 kg of the styrene monomer was added over 30 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (6), the surface-treated expandable styrene resin particles (6′), the pre-expanded styrene resin particles (6), and the expanded styrene resin particles A compact (6) was obtained.
Various evaluation results are shown in Table 1.

[Example 7]
26.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer. ) was added and suspended by stirring at 160 rpm to prepare a suspension (7).
Separately, in a dispersion of 14 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 48 g of benzoyl peroxide (purity 75%) as a polymerization initiator and 14 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 14 kg of monomer was added and stirred with a homomixer to emulsify to prepare emulsion (7).
The above suspension (7) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (7) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and then held at 80°C for 30 minutes for polymerization.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (7), the surface-treated expandable styrene resin particles (7′), the pre-expanded styrene resin particles (7), and the expanded styrene resin particles A compact (7) was obtained.
Various evaluation results are shown in Table 1.

[Example 8]
31.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (8).
Separately, in a dispersion of 9 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 32 g of benzoyl peroxide (purity 75%) as a polymerization initiator and 9 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 9 kg of monomer was added and stirred with a homomixer to emulsify to prepare emulsion (8).
The above suspension (8) in a 100 liter stirred reactor was maintained at 80° C. and the above emulsion (8) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and then held at 80°C for 30 minutes for polymerization.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (8), the surface-treated expandable styrene resin particles (8′), the pre-expanded styrene resin particles (8), and the styrene resin expanded A compact (8) was obtained.
Various evaluation results are shown in Table 1.

[Example 9]
35.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (9).
Separately, in a dispersion of 5 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 16 g of benzoyl peroxide (75% purity) as a polymerization initiator and 5 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 5 kg of the monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (9).
The above suspension (9) in a 100 liter stirred reactor was kept at 80° C. and the above emulsion (9) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and then held at 80°C for 30 minutes for polymerization.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
After that, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (9), the surface-treated expandable styrene resin particles (9′), the pre-expanded styrene resin particles (9), and the expanded styrene resin particles A compact (9) was obtained.
Various evaluation results are shown in Table 1.

[Comparative Example 1]
39.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and stirred at 160 rpm for suspension to prepare a suspension (C1).
Separately, in a dispersion of 1 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 150 g of benzoyl peroxide (75% purity) as a polymerization initiator and 44 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 1 kg of a monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (C1).
The above suspension (C1) in a 100 liter stirred reactor was kept at 80° C. and the above emulsion (C1) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80° C. for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after holding, 43 kg of styrene monomer was applied over 194 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
Thereafter, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (C1), the surface-treated expandable styrene resin particles (C1′), the pre-expanded styrene resin particles (C1), and the expanded styrene resin were A compact (C1) was obtained.
Various evaluation results are shown in Table 1.

[Comparative Example 2]
39.5 kg of pure water, 5 g of sodium dodecylbenzenesulfonate, and 180 g of magnesium pyrophosphate are placed in a 100-liter reactor equipped with a stirrer, and then recycled styrene-based resin particles (A) (used polystyrene-based resin from household appliances as a raw material) are added. ) was added and suspended by stirring at 160 rpm to prepare a suspension (C2).
Separately, in a dispersion of 1 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, 8 g of benzoyl peroxide (75% purity) as a polymerization initiator and 2 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in styrene. 1 kg of the monomer was added and stirred with a homomixer to emulsify to prepare an emulsion (C2).
The suspension (C2) in a 100 liter stirred reactor was kept at 80° C. and the emulsion (C2) was added.
Thereafter, the regenerated styrene resin particles (A) were held at 80°C for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and immediately after the holding, 1 kg of styrene monomer was applied over 5 minutes. was added dropwise continuously. The addition temperature was kept constant at 80°C.
Then, the temperature was raised to 125° C. over 30 minutes, held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour.
Thereafter, the procedure was carried out in the same manner as in Example 1, and the expandable styrene resin particles (C2), the surface-treated expandable styrene resin particles (C2′), the pre-expanded styrene resin particles (C2), and the expanded styrene resin particles A compact (C2) was obtained.
Various evaluation results are shown in Table 1.

[Example 10]
The procedure of Example 5 was repeated except that the injection temperature of the blowing agent was changed to 40° C., and the expandable styrene resin particles (10), the surface-treated expandable styrene resin particles (10′), the pre-expanded styrene A resin particle (10) and a styrene resin expansion molding (10) were obtained.
Various evaluation results are shown in Table 2.

[Example 11]
The procedure of Example 5 was repeated except that the injection temperature of the blowing agent was changed to 80° C., and the expandable styrene resin particles (11), the surface-treated expandable styrene resin particles (11′), the pre-expanded styrene A resin particle (11) and a styrene resin expansion molding (11) were obtained.
Various evaluation results are shown in Table 2.

[Example 12]
The procedure was carried out in the same manner as in Example 5 except that the injection temperature of the blowing agent was changed to 89° C., and the expandable styrene resin particles (12), the surface-treated expandable styrene resin particles (12′), the pre-expanded styrene A resin particle (12) and a styrene resin expansion molding (12) were obtained.
Various evaluation results are shown in Table 2.

[Comparative Example 3]
The procedure of Example 5 was repeated except that the injection temperature of the blowing agent was changed to 35° C., and the expandable styrene resin particles (C3), the surface-treated expandable styrene resin particles (C3′), the pre-expanded styrene A resin particle (C3) and a styrene resin foam molded product (C3) were obtained.
Various evaluation results are shown in Table 2.

[Comparative Example 4]
The procedure of Example 5 was repeated except that the injection temperature of the blowing agent was changed to 90° C., and the expandable styrene resin particles (C4), the surface-treated expandable styrene resin particles (C4′), the pre-expanded styrene A resin particle (C4) and a styrene resin foam molded product (C4) were obtained.
Various evaluation results are shown in Table 2.

[Comparative Example 5]
The procedure of Example 5 was repeated except that the injection temperature of the blowing agent was changed to 95° C., and the expandable styrene resin particles (C5), the surface-treated expandable styrene resin particles (C5′), the pre-expanded styrene A resin particle (C5) and a styrene resin foam molded product (C5) were obtained.
Various evaluation results are shown in Table 2.

[Example 13]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 40° C., emulsion (5) is added, and then styrene monomer and polymerized in regenerated styrene resin particles (A). It was held at 40°C for 30 minutes so that the initiator and the initiator were well absorbed, and immediately after holding, 13 kg of styrene monomer was continuously added dropwise at 40°C over 60 minutes, and then over 60 minutes. The procedure was carried out in the same manner as in Example 5, except that the temperature was raised to 125 ° C. by heating, held at 125 ° C. for 1 hour, and then cooled to 60 ° C. over 1 hour. Expandable styrene resin particles (13'), pre-expanded styrene resin particles (13), and styrene resin expansion molding (13) were obtained.
Various evaluation results are shown in Table 3.

[Example 14]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 60° C., emulsion (5) is added, and then styrene monomer and polymerized in regenerated styrene resin particles (A). It was held at 60°C for 30 minutes so that the initiator and the initiator were well absorbed, and immediately after holding, 13 kg of styrene monomer was continuously added dropwise at 60°C over 60 minutes, and then over 60 minutes. The same procedure as in Example 5 was carried out, except that the temperature was raised to 125° C., held at 125° C. for 1 hour, and then cooled to 60° C. over 1 hour. Expandable styrene resin particles (14'), pre-expanded styrene resin particles (14) and styrene resin expansion molding (14) were obtained.
Various evaluation results are shown in Table 3.

[Example 15]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 100° C., emulsion (5) is added, and then styrene monomer and polymerized in regenerated styrene resin particles (A). It was held at 100°C for 30 minutes so that the initiator and the initiator were well absorbed. The same procedure as in Example 5 was carried out, except that the temperature was raised to 125 ° C., held at 125 ° C. for 1 hour, and then cooled to 60 ° C. over 1 hour, and the expandable styrene resin particles (15) and surface treatment Expandable styrene resin particles (15'), pre-expanded styrene resin particles (15), and styrene resin expansion molding (15) were obtained.
Various evaluation results are shown in Table 3.

[Example 16]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 109° C., emulsion (5) is added, and then styrene monomer and polymerized in regenerated styrene resin particles (A). The temperature was maintained at 109° C. for 30 minutes so that the initiator was well absorbed, and immediately after the maintenance, 13 kg of styrene monomer was continuously added dropwise at 109° C. over 60 minutes, and then over 30 minutes. The procedure was carried out in the same manner as in Example 5, except that the temperature was raised to 125 ° C. by heating, held at 125 ° C. for 1 hour, and then cooled to 60 ° C. over 1 hour. Expandable styrene resin particles (16'), pre-expanded styrene resin particles (16), and styrene resin expansion molding (16) were obtained.
Various evaluation results are shown in Table 3.

[Example 17]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 80° C., emulsion (5) is added, and then styrene monomer and polymerized in regenerated styrene resin particles (A). The temperature was maintained at 80°C for 30 minutes so that the initiator was well absorbed, and immediately after the temperature was maintained, the styrene monomer addition temperature was increased from 80°C to 109°C at a rate of 0.48°C/min. 13 kg of styrene monomer was continuously added dropwise over 60 minutes, then heated to 125°C over 30 minutes, held at 125°C for 1 hour, and then cooled to 60°C over 1 hour. The procedure of Example 5 was repeated except that the expandable styrene resin particles (17), the surface-treated expandable styrene resin particles (17′), the pre-expanded styrene resin particles (17), the styrene resin A foam molded article (17) was obtained.
Various evaluation results are shown in Table 3.

[Comparative Example 6]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 35° C., emulsion (5) is added, and then styrene monomer and polymerization are carried out in regenerated styrene resin particles (A). It was held at 35°C for 30 minutes so that the initiator and the initiator were well absorbed, and immediately after holding, 13 kg of styrene monomer was continuously added dropwise at 35°C over 60 minutes, and then over 60 minutes. The procedure was carried out in the same manner as in Example 5, except that the temperature was raised to 125 ° C., held at 125 ° C. for 1 hour, and then cooled to 60 ° C. over 1 hour, and the expandable styrene resin particles (C6) and surface treatment Expandable styrene resin particles (C6′), pre-expanded styrene resin particles (C6), and styrene resin expansion molding (C6) were obtained.
Various evaluation results are shown in Table 3.

[Comparative Example 7]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 110° C., emulsion (5) is added, and then styrene monomer and polymerized in regenerated styrene resin particles (A). It was held at 110°C for 30 minutes so that the initiator and the initiator were well absorbed, and immediately after holding, 13 kg of styrene monomer was continuously added dropwise at 110°C over 60 minutes, and then over 30 minutes. The procedure was carried out in the same manner as in Example 5, except that the temperature was raised to 125 ° C. by heating, held at 125 ° C. for 1 hour, and then cooled to 60 ° C. over 1 hour. Expandable styrene resin particles (C7'), pre-expanded styrene resin particles (C7), and styrene resin expansion molding (C7) were obtained.
Various evaluation results are shown in Table 3.

[Comparative Example 8]
Suspension (5) in a 100 liter reactor equipped with a stirrer is maintained at 115° C., emulsion (5) is added, and then styrene monomer and polymerized in regenerated styrene resin particles (A). The temperature was maintained at 115°C for 30 minutes so that the initiator and the initiator were well absorbed, and immediately after the temperature was maintained, 13 kg of styrene monomer was continuously added dropwise at 115°C over 60 minutes, and then over 30 minutes. The procedure was carried out in the same manner as in Example 5, except that the temperature was raised to 125 ° C., held at 125 ° C. for 1 hour, and then cooled to 60 ° C. over 1 hour, and the expandable styrene resin particles (C8) and surface treatment Expandable styrene resin particles (C8'), pre-expanded styrene resin particles (C8), and styrene resin expansion molding (C8) were obtained.
Various evaluation results are shown in Table 3.

[Example 18]
The procedure was carried out in the same manner as in Example 17, except that the flame retardant auxiliary (dicumyl peroxide) and the flame retardant (tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) were not used. A polystyrene resin particle (18), a surface-treated expandable styrene resin particle (18'), a pre-expanded styrene resin particle (18), and a styrene resin expansion molding (18) were obtained.
Various evaluation results are shown in Table 3.

[Example 19]
The procedure of Example 17 was repeated except that the amount of pentane (isopentane/normal pentane = 20% by mass/80% by mass) used as a foaming agent was changed to 4150 g. Expandable styrene resin particles (19'), pre-expanded styrene resin particles (19), and styrene resin expansion molding (19) were thus obtained.
The pre-expanded styrene resin particles (19) had a bulk density of 0.0125 g/cm ³ and a bulk expansion ratio of 80 times. A styrene-based resin foam molded article (19) was also molded in the same manner as in Example 17, and had a density of 0.0125 g/cm ³ and an expansion ratio of 80 times.
Various evaluation results are shown in Table 4.

[Example 20]
The same procedure as in Example 17 was carried out, except that the recycled styrene resin particles (A) (made from used polystyrene resin of home electric appliances) were replaced with the recycled styrene resin particles (B) as the recycled styrene resin particles. Expandable styrene resin particles (20), surface-treated expandable styrene resin particles (20'), pre-expanded styrene resin particles (20), and styrene resin expansion molding (20) were obtained.
Various evaluation results are shown in Table 4.

The expandable styrene resin particles, the pre-expanded styrene resin particles, and the styrene resin foam molded product according to the embodiment of the present invention are heat insulating materials used in houses and automobiles, heat insulating materials used in building materials, etc., fish boxes, and food products. It is suitably used for packing materials for transportation such as containers, cushioning materials and the like. The pre-expanded styrene resin particles according to the embodiment of the present invention are preferably used as a filling body in which a large number of pre-expanded styrene resin particles are filled in a bag, and are used as a cushioning material (expanded grains filled inside the cushion). ) is preferably used. More specifically, the styrene-based resin foam molded product according to the embodiment of the present invention is a heat insulating material for walls, a heat insulating material for floors, a heat insulating material for roofs, a heat insulating material for automobiles, a heat insulating material for hot water tanks, and a heat insulating material for piping. , Thermal insulation materials for solar systems, Thermal insulation materials for water heaters, Containers for food and industrial products (e.g. food containers such as fish boxes, returnable boxes), cushioning materials, floats, blocks, packing materials for fish and agricultural products, embankment materials (formed body for embankment, embankment block, etc.), the core material of tatami mats, the core material of cushions, the aggregate of concrete, and the like.

Claims (13)

Expandable styrene resin particles obtained by injecting a volatile blowing agent into the styrene resin particles (A) obtained by adding a styrene monomer to the regenerated styrene resin particles and polymerizing them,
The content of the regenerated styrene resin particles with respect to the total amount of the regenerated styrene resin particles and the styrene monomer is 10% by mass to 90% by mass,
The injection temperature at which the volatile blowing agent is injected is 40° C. to 89° C.
Expandable styrene resin particles. The expandable styrenic resin particles according to claim 1, wherein the styrenic monomer is added at an addition temperature of 40°C to 109°C. The expandable styrene resin particles according to claim 1 or 2, wherein the recycled styrene resin particles are pellets obtained by a melt extrusion method. The pellets obtained by the melt extrusion method are extruded strand pellets obtained by extruding the used styrene foam resin with an extruder and cutting the strands, and extruding the used styrene foam resin with the extruder and cutting it in water at the same time. At least one selected from underwater cut pellets obtained by an underwater cutting method, and hot cut pellets obtained by a hot cut method in which used styrene foam resin particles are cut immediately after coming out of the extruder die and cooled. The expandable styrene resin particles according to claim 3, wherein Pre-expanded styrene resin particles obtained by pre-expanding the expandable styrene resin particles according to any one of claims 1 to 4,
The bulk expansion ratio of the pre-foaming is 2 to 150 times,
Pre-expanded styrene resin particles. 6. The pre-expanded styrene resin particles according to claim 5, which are used as a cushioning material. A styrene-based resin foam molded article molded from the expandable styrene-based resin particles according to any one of claims 1 to 4. A styrenic resin foam molded article molded from the pre-expanded styrene resin particles according to claim 5 . 9. The styrene-based resin foam molded article according to claim 7 or 8, which is a molded article for embankment, a molded article for food containers, a molded article for cushioning material, or a molded article for returnable boxes. A step of adding a styrene-based monomer to the regenerated styrene-based resin particles and polymerizing them to obtain styrene-based resin particles (A), and a step of forcing a volatile blowing agent into the styrene-based resin particles (A). A method for producing expandable styrene resin particles, comprising
The content of the regenerated styrene resin particles with respect to the total amount of the regenerated styrene resin particles and the styrene monomer is 10% by mass to 90% by mass,
The injection temperature at which the volatile blowing agent is injected is 40° C. to 89° C.
A method for producing expandable styrene resin particles. The method for producing expandable styrenic resin particles according to claim 10, wherein the temperature for adding the styrenic monomer is 40°C to 109°C. The method for producing expandable styrene resin particles according to claim 10 or 11, wherein the recycled styrene resin particles are pellets obtained by a melt extrusion method. The pellets obtained by the melt extrusion method are extruded strand pellets obtained by extruding the used styrene foam resin with an extruder and cutting the strands, and extruding the used styrene foam resin with the extruder and cutting it in water at the same time. At least one selected from underwater cut pellets obtained by an underwater cutting method, and hot cut pellets obtained by a hot cut method in which used styrene foam resin particles are cut immediately after coming out of the extruder die and cooled. The method for producing expandable styrene-based resin particles according to claim 12, wherein