JP5756003B2 - Expandable polystyrene resin particles and method for producing the same, polystyrene resin pre-expanded particles, and polystyrene resin foam molded article - Google Patents

Description

  The present invention relates to a method for producing expandable polystyrene resin particles by melt extrusion, and relates to a foamable polystyrene resin particle capable of obtaining a foamed molded article having a high expansion ratio and excellent mechanical strength, a method for producing the same, and a polystyrene type The present invention relates to resin pre-expanded particles and polystyrene-based resin foam moldings.

  A foaming agent is press-fitted and kneaded into the polystyrene resin melted in the extruder, and the foaming agent-containing molten resin is extruded directly into the cooling liquid through a small hole in the die attached to the tip of the extruder. With respect to a method for producing expandable polystyrene resin particles by a so-called melt extrusion method, the extrudate is cooled and solidified by contact with a liquid to obtain expandable polystyrene resin particles. The technique disclosed in Patent Document 1 has been proposed.

In Patent Document 1, a foaming agent is press-fitted into a thermoplastic resin melted in an extruder, and the foaming agent-containing molten resin is extruded directly into a cooling liquid from a large number of small holes in a die attached to the tip of the extruder. A method for producing thermoplastic resin expandable particles, wherein the extrudate is cut with a high-speed rotary blade at the same time as being extruded, and the extrudate is cooled and solidified by contact with a liquid to obtain expandable particles, the small holes of the die Foaming thermoplastic resin foaming property, wherein the foaming agent-containing molten resin is extruded so that the shearing rate of the foaming agent-containing molten resin is 12000 to 35000 sec ⁻¹ and the apparent melt viscosity of the resin is 100 to 700 poise A method for producing particles is disclosed.

International Publication No. 2005/028173

However, it is difficult for the expandable polystyrene resin particles produced by the above-described conventional technology to increase the bulk expansion ratio of the pre-expanded particles obtained by heating and pre-expanding, and it is difficult to increase the expansion ratio. It was difficult to get.
Also, conventional foamed polystyrene resin particles, particularly foamed molded articles produced using recycled polystyrene resin, tend to have low mechanical strength such as bending strength.

  The present invention has been made in view of the above circumstances, and expandable polystyrene resin particles capable of obtaining a foamed molded article having a high expansion ratio and excellent mechanical strength, a method for producing the same, a polystyrene resin pre-expanded particle, and a polystyrene resin It is an object to provide a foam molded article.

  In order to achieve the above object, the present invention provides a small hole in a die in which a foaming agent is press-fitted and kneaded into a polystyrene resin melted in a resin supply device, and a foamed agent-containing molten resin is attached to the tip of the resin supply device. It is manufactured by a melt extrusion method that extrudes directly into a liquid for cooling, cuts the extrudate at the same time with a high-speed rotary blade, and cools and solidifies the extrudate by contact with the liquid to obtain expandable polystyrene resin particles. In the expanded polystyrene resin particles, liquid paraffin was uniformly contained in the entire expanded polystyrene resin particles within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin. Expandable polystyrene resin particles are provided.

  In the expandable polystyrene resin particles of the present invention, it is preferable that an inorganic foam nucleating agent is uniformly contained in the entire expandable polystyrene resin particles.

  In addition, the present invention is a method in which a foaming agent is press-fitted and kneaded into a polystyrene resin melted in a resin supply apparatus, and the foaming agent-containing molten resin is directly contained in a cooling liquid from a small hole in a die attached to the tip of the resin supply apparatus. Expandable polystyrene resin manufactured by melt extrusion method, extruding the extruded product with a high-speed rotary blade at the same time as extrusion, and cooling and solidifying the extruded product by contact with a liquid to obtain expandable polystyrene resin particles In the particles, liquid paraffin is uniformly contained within the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin, and the aromatic hydrocarbon is 100 parts by mass of the polystyrene resin. It is uniformly contained within the range of 0.15 to 3.0 parts by mass with respect to 100 parts by mass of the polystyrene-based resin and the inorganic foam nucleating agent is 0.05 to 5 parts by mass. Providing expandable polystyrene resin particles characterized in that it is uniformly contained in an amount ranging portion.

  In the expandable polystyrene resin particles of the present invention, the inorganic foam nucleating agent is preferably talc.

  In the expandable polystyrene resin particles of the present invention, it is preferable that the liquid paraffin is a mixture of olefin-based saturated hydrocarbons, has an average carbon number in the range of 20 to 35, and is liquid at normal temperature.

  In addition, the present invention is a method in which a foaming agent is press-fitted and kneaded into a polystyrene resin melted in a resin supply apparatus, and the foaming agent-containing molten resin is directly contained in a cooling liquid from a small hole in a die attached to the tip of the resin supply apparatus. The extrudate is cut with a high-speed rotary blade at the same time as extrusion and the extrudate is cooled and solidified by contact with a liquid to obtain expandable polystyrene resin particles. Production of expandable polystyrene resin particles by melt extrusion In the method, foaming characterized in that liquid paraffin is uniformly contained in the entire expandable polystyrene resin particles by adding liquid paraffin within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of polystyrene resin. Provided is a method for producing conductive polystyrene resin particles.

  In the method for producing expandable polystyrene resin particles of the present invention, it is preferable to further add an inorganic foam nucleating agent to the polystyrene resin.

  In addition, the present invention is a method in which a foaming agent is press-fitted and kneaded into a polystyrene resin melted in a resin supply apparatus, and the foaming agent-containing molten resin is directly contained in a cooling liquid from a small hole in a die attached to the tip of the resin supply apparatus. The extrudate is cut with a high-speed rotary blade at the same time as extrusion and the extrudate is cooled and solidified by contact with a liquid to obtain expandable polystyrene resin particles. Production of expandable polystyrene resin particles by melt extrusion In the method, the liquid paraffin is in the range of 0.01 to 5 parts by mass, the aromatic hydrocarbon is in the range of 0.15 to 3.0 parts by mass, and the inorganic foam nucleating agent with respect to 100 parts by mass of the polystyrene-based resin. Is added in the range of 0.05 to 5 parts by mass, and liquid paraffin, aromatic hydrocarbon and inorganic foam nucleating agent are uniformly contained in the entire expandable polystyrene resin particles. To provide a process for the preparation of foam polystyrene resin particles.

  In the method for producing expandable polystyrene resin particles of the present invention, the inorganic foam nucleating agent is preferably talc.

  In the method for producing expandable polystyrene resin particles of the present invention, the liquid paraffin is a mixture of olefin-based saturated hydrocarbons and has an average carbon number in the range of 20 to 35, and is liquid at room temperature. Is preferred.

  The present invention also provides polystyrene resin pre-expanded particles obtained by heating and foaming the expandable polystyrene resin particles.

  The present invention also provides a polystyrene resin foam molded article obtained by filling the polystyrene resin pre-expanded particles into a cavity of a molding die and heating and molding in-mold foam molding.

  Further, the present invention provides a polystyrene resin foam molded article characterized in that liquid paraffin is uniformly contained within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of polystyrene resin in the entire foam molded article. provide.

  In the present invention, liquid paraffin is uniformly contained within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin, and aromatic hydrocarbon is contained in 100 parts by mass of the polystyrene resin. On the other hand, it is uniformly contained within the range of 0.15 to 3.0 parts by mass, and the inorganic foam nucleating agent is uniformly contained within the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polystyrene-based resin. A polystyrene-based resin foam molded article is provided.

The expandable polystyrene resin particles of the present invention have a configuration in which liquid paraffin is uniformly contained in a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin throughout the expandable polystyrene resin particles. Thus, it is possible to increase the bulk expansion ratio of the pre-expanded particles obtained by heating and pre-expanding, and it is possible to obtain a foamed molded article having a high expansion ratio.
Moreover, even when manufactured using recycled polystyrene resin, a foamed molded article having excellent mechanical strength such as bending strength can be obtained.
Furthermore, the liquid paraffin is uniformly contained in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin, and the aromatic hydrocarbon is contained in 100 parts by mass of the polystyrene resin. On the other hand, it is uniformly contained within the range of 0.15 to 3.0 parts by mass, and the inorganic foam nucleating agent is uniformly contained within the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polystyrene-based resin. By setting it as the structure, the volume expansion ratio of the pre-expanded particle obtained by heating and pre-expanding can be raised further, and the foaming molding of higher expansion ratio can be obtained.

The method for producing expandable polystyrene resin particles of the present invention is a method for producing expandable polystyrene resin particles by a melt extrusion method, and liquid paraffin within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of polystyrene resin. When liquid paraffin is uniformly contained throughout the expandable polystyrene resin particles, a foamed molded product with a high expansion ratio can be obtained, and when it is manufactured using recycled polystyrene resin However, it is possible to efficiently produce expandable polystyrene resin particles capable of obtaining a foamed molded article having excellent mechanical strength such as bending strength.
Furthermore, with respect to 100 parts by mass of the polystyrene resin, the liquid paraffin is in the range of 0.01 to 5 parts by mass, the aromatic hydrocarbon is in the range of 0.15 to 3.0 parts by mass, and the inorganic foam nucleating agent is added. Addition within the range of 0.05 to 5 parts by mass, and by uniformly containing liquid paraffin, aromatic hydrocarbon and inorganic foam nucleating agent in the whole expandable polystyrene resin particles, foam molding with higher expansion ratio You can get a body.

It is a block diagram which shows an example of the manufacturing apparatus of the expandable polystyrene-type resin particle by a melt extrusion method.

(Expandable polystyrene resin particles)
The expandable polystyrene resin particles of the present invention are characterized in that liquid paraffin is uniformly contained in the entire expandable polystyrene resin particles within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin. It is said.

  The polystyrene resin used for the expandable polystyrene resin particles of the present invention is not particularly limited. For example, styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromo Examples thereof include homopolymers of styrene monomers such as styrene or copolymers thereof, and polystyrene resins containing 50% by mass or more of styrene are preferable, and polystyrene is more preferable.

  Further, the polystyrene resin may be a copolymer of the styrene monomer and a vinyl monomer copolymerizable with the styrene monomer, the main component of which is the styrene monomer. As, for example, alkyl (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cetyl (meth) acrylate, (meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl In addition to fumarate and ethyl fumarate, bifunctional monomers such as divinylbenzene and alkylene glycol dimethacrylate are exemplified.

  If a polystyrene resin is the main component, other resins may be added. Examples of the resin to be added include polybutadiene, styrene-butadiene copolymer to improve the impact resistance of the foam molded article. Examples thereof include rubber-modified polystyrene resins to which a diene rubbery polymer such as a polymer, ethylene-propylene-nonconjugated diene three-dimensional copolymer is added, so-called high impact polystyrene. Alternatively, a polyethylene resin, a polypropylene resin, an acrylic resin, an acrylonitrile-styrene copolymer, an acrylonitrile-butadiene-styrene copolymer, and the like can be given.

The polystyrene resin used as a raw material is a non-recycled polystyrene resin (virgin polystyrene) such as a commercially available ordinary polystyrene resin or a polystyrene resin newly produced by a method such as suspension polymerization. In addition, a regenerated polystyrene resin obtained by regenerating a used polystyrene resin foam molded article can be used.
As this recycled polystyrene-based resin, used polystyrene-based resin foam molded products, for example, fish boxes, household appliance cushioning materials, food packaging trays, etc. are recovered and recycled by the limonene dissolution method or heating volume reduction method. Can be used. In addition, recycled polystyrene resins that can be used are not only those obtained by reprocessing used polystyrene resin foam moldings, but also household electrical appliances (for example, televisions, refrigerators, washing machines, air conditioners, etc.) In addition, a recycled polystyrene resin obtained by pulverizing, melt-kneading, and re-pelletizing a non-foamed polystyrene resin molded product separated and collected from office equipment (for example, a copying machine, a facsimile machine, a printer, etc.) can be used.

  Examples of the foaming agent contained in the expandable polystyrene resin particles of the present invention include aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and neopentane, 1,1-dichloro-1-fluoroethane ( HCFC-141b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), chlorodifluoromethane (HCFC-22), 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) and other chlorofluorocarbons, 1,1-difluoroethane (HFC-152a), 1,1,1-trifluoroethane (HFC-143a), 1,1,1,2-tetrafluoroethane (HFC- 134a), fluorocarbons such as difluoromethane (HFC-32), various alcohols, carbon dioxide, water And physical blowing agents can be mentioned such as nitrogen, can be used in combination one or more of these. Among these, particularly preferable blowing agents include n-butane, isobutane, n-pentane, and isopentane. The addition amount of a foaming agent shall be the range of 1-15 mass parts with respect to 100 mass parts of polystyrene-type resins, More preferably, it shall be the range of 3-12 mass parts.

The liquid paraffin contained in the expandable polystyrene resin particles of the present invention is a mixture of olefin-based saturated hydrocarbons, and has an average carbon number in the range of 20 to 35, and is preferably liquid at normal temperature.
The amount of the liquid paraffin is in the range of 0.01 to 5 parts by mass, more preferably in the range of 0.5 to 2 parts by mass with respect to 100 parts by mass of the polystyrene resin. When the amount of the liquid paraffin is less than 0.01 parts by mass, the effect of increasing the bulk expansion ratio of the pre-expanded particles and the effect of improving the mechanical strength of the foamed molded article cannot be sufficiently obtained. When the amount of the liquid paraffin exceeds 5 parts by mass, the effect of increasing the bulk expansion ratio of the pre-expanded particles and the effect of improving the mechanical strength of the foamed molded article cannot be sufficiently obtained.
The liquid paraffin is preferably contained uniformly throughout the expandable polystyrene resin particles (in the case where bubbles are included in the particles, the region not including the bubbles). If the liquid paraffin is unevenly distributed in a local portion of the resin particle, for example, the surface layer portion of the resin particle, the effect of increasing the bulk expansion ratio of the pre-expanded particle and the effect of improving the mechanical strength of the foamed molded article cannot be obtained sufficiently.

The expandable polystyrene resin particles of the present invention preferably contain an inorganic foam nucleating agent in addition to the foaming agent and liquid paraffin. Examples of the inorganic foam nucleating agent include talc, silica, and other inorganic powders. Among these, talc is preferable.
The amount of the inorganic foam nucleating agent is preferably in the range of 0.05 to 5 parts by mass, more preferably in the range of 0.1 to 2 parts by mass with respect to 100 parts by mass of the polystyrene resin.
The average particle diameter of the inorganic foam nucleating agent to be used is preferably in the range of 0.1 to 30 μm, and more preferably in the range of 0.5 to 10 μm.
By containing an expandable polystyrene resin particle and an inorganic foam nucleating agent such as talc together with liquid paraffin, the effect of increasing the bulk expansion ratio of the pre-expanded particles and the effect of improving the mechanical strength of the foamed molded product can be enhanced.
The inorganic foam nucleating agent needs to be uniformly contained throughout the expandable polystyrene resin particles. If talc is unevenly distributed in a local portion of the resin particle, for example, a surface layer portion of the resin particle, the mechanical strength of the obtained foamed molded product may be lowered.

  In the foamable polystyrene resin particles of the present invention, additives such as a crosslinking agent, a plasticizer, a filler, a flame retardant, a flame retardant aid, a lubricant, and a colorant may be added within a range that does not impair the physical properties. Well, if powder metal soaps such as zinc stearate are applied on the surface of the expandable styrene resin particles, the polystyrene resin pre-expanded particles are bonded together in the pre-expanding step of the expandable polystyrene resin particles. Is preferable.

  The particle size of the expandable polystyrene resin particles of the present invention is not particularly limited, but is usually preferably in the range of 0.5 to 3.0 mm, more preferably in the range of 0.7 to 2.0 mm. The shape of the particles is not particularly limited, but is preferably spherical or substantially spherical.

The expandable polystyrene resin particles of the present invention have a configuration in which liquid paraffin is uniformly contained in a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin throughout the expandable polystyrene resin particles. Thus, it is possible to increase the bulk expansion ratio of the pre-expanded particles obtained by heating and pre-expanding, and it is possible to obtain a foamed molded article having a high expansion ratio.
Moreover, even when manufactured using recycled polystyrene resin, a foamed molded article having excellent mechanical strength such as bending strength can be obtained.

In a preferred embodiment of the expandable polystyrene resin particles of the present invention, liquid paraffin is uniformly contained in the entire expandable polystyrene resin particles within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin. The aromatic hydrocarbon is uniformly contained in the range of 0.15 to 3.0 parts by mass with respect to 100 parts by mass of the polystyrene resin, and the inorganic foam nucleating agent is 0.05 to 100 parts by mass with respect to 100 parts by mass of the polystyrene resin. It is preferable to make it the structure contained uniformly within the range of 5 mass parts.
According to this embodiment, the liquid paraffin is uniformly contained in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin, and the aromatic hydrocarbon is polystyrene type. It is uniformly contained within the range of 0.15 to 3.0 parts by mass with respect to 100 parts by mass of the resin, and the inorganic foam nucleating agent is uniform within the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polystyrene-based resin. By using the composition contained in the pre-expanded particles obtained by heating and pre-expanding, the bulk expansion ratio of the pre-expanded particles can be further increased, and a foamed molded article having a higher expansion ratio can be obtained.

The liquid paraffin to be included in the expandable polystyrene resin particles of the present embodiment is a mixture of olefin-based saturated hydrocarbons, has an average carbon number in the range of 20 to 35, and is preferably liquid at normal temperature. .
The amount of liquid paraffin is in the range of 0.01 to 5 parts by mass, and more preferably in the range of 0.1 to 2 parts by mass with respect to 100 parts by mass of the polystyrene resin. When the amount of the liquid paraffin is less than 0.01 parts by mass, the effect of increasing the bulk expansion ratio of the pre-expanded particles and the effect of improving the mechanical strength of the foamed molded article cannot be sufficiently obtained. When the amount of the liquid paraffin exceeds 5 parts by mass, the effect of increasing the bulk expansion ratio of the pre-expanded particles and the effect of improving the mechanical strength of the foamed molded article cannot be sufficiently obtained.
The liquid paraffin is preferably contained uniformly throughout the expandable polystyrene resin particles (in the case where bubbles are included in the particles, the region not including the bubbles). If the liquid paraffin is unevenly distributed in a local portion of the resin particle, for example, the surface layer portion of the resin particle, the effect of increasing the bulk expansion ratio of the pre-expanded particle and the effect of improving the mechanical strength of the foamed molded article cannot be obtained sufficiently.

Examples of the aromatic hydrocarbon contained in the expandable polystyrene resin particles of the present embodiment include styrene, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, n-propylbenzene, and i-propylbenzene. Among these, styrene and toluene are preferable.
The amount of the aromatic hydrocarbon is in the range of 0.15 to 3.0 parts by mass, more preferably in the range of 0.2 to 2 parts by mass with respect to 100 parts by mass of the polystyrene resin. If the amount of the aromatic hydrocarbon is within the above range, it is possible to further increase the bulk expansion ratio of the pre-expanded particles obtained by heating and pre-expanding to obtain a foamed molded article having a higher expansion ratio. it can.
The aromatic hydrocarbon is preferably contained uniformly throughout the expandable polystyrene resin particles (in the case where bubbles are included in the particles, the region not including the bubbles). If aromatic hydrocarbons are unevenly distributed in the local part of the resin particles, for example, the surface layer part of the resin particles, the effect of increasing the bulk expansion ratio of the pre-expanded particles and the effect of improving the mechanical strength of the foamed molded article cannot be obtained sufficiently.

Examples of the inorganic foam nucleating agent to be contained in the expandable polystyrene resin particles of the present embodiment include talc, silica, calcium salt, magnesium salt, clay mineral, and the like. Among these, talc is preferable. Moreover, the range of 0.1-30 micrometers is preferable and, as for the average particle diameter of the talc to be used, the inside of the range of 0.5-10 micrometers is more preferable.
The amount of the inorganic foam nucleating agent is in the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin, and preferably in the range of 0.5 to 10 μm. If the amount of the inorganic foam nucleating agent is within the above range, the bulk foaming factor of the prefoamed particles obtained by heating and prefoaming can be further increased, and a foamed molded product having a higher foaming factor can be obtained. it can.
The inorganic foam nucleating agent is preferably contained uniformly over the entire expandable polystyrene resin particles (in the case where bubbles are included in the particles, the region not including the bubbles). If the inorganic foam nucleating agent is unevenly distributed in the local part of the resin particles, for example, the surface layer part of the resin particles, the effect of increasing the bulk expansion factor of the pre-expanded particles and the effect of improving the mechanical strength of the foamed molded article cannot be obtained sufficiently.

(Method for producing expandable polystyrene resin particles)
The method for producing expandable polystyrene resin particles according to the present invention includes a die in which a foaming agent is press-fitted and kneaded into a polystyrene resin melted in a resin supply device, and a foamed agent-containing molten resin is attached to the tip of the resin supply device. Extrusion into the cooling liquid directly from the small holes of the glass, and simultaneously extruding, the extrudate is cut with a high-speed rotary blade, and the extrudate is cooled and solidified by contact with the liquid to obtain expandable polystyrene resin particles. In the method for producing expandable polystyrene resin particles by the method, liquid paraffin is added within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of polystyrene resin, and the liquid paraffin is uniformly distributed throughout the expandable polystyrene resin particles. It is characterized by the inclusion.

  In a preferred embodiment of the production method of the present invention, a foaming agent is press-fitted and kneaded into a polystyrene-based resin melted in a resin supply device, and a small hole in a die provided with a foaming agent-containing molten resin at the tip of the resin supply device The melt is extruded directly into the cooling liquid, and at the same time, the extrudate is cut with a high-speed rotary blade, and the extrudate is cooled and solidified by contact with the liquid to obtain expandable polystyrene resin particles. In the method for producing polystyrene resin particles, liquid paraffin is in the range of 0.01 to 5 parts by mass and aromatic hydrocarbon is in the range of 0.15 to 3.0 parts by mass with respect to 100 parts by mass of the polystyrene resin. In addition, 0.05 to 5 parts by mass of an inorganic foam nucleating agent is added, and liquid paraffin, aromatic hydrocarbons and inorganic foam nucleating agent are averaged over the entire expandable polystyrene resin particles. It is preferable to obtain expandable polystyrene resin particles are contained in. Here, the liquid paraffin, aromatic hydrocarbon and inorganic foam nucleating agent may be the same as those described above.

  FIG. 1 is a configuration diagram showing an example of a production apparatus used in the method for producing expandable polystyrene resin particles of the present invention. The production apparatus of this example includes an extruder 1 as a resin supply apparatus, and an extruder 1. A die 2 having a large number of small holes attached to the tip of the resin, a raw material supply hopper 3 for introducing a resin raw material or the like into the extruder 1, and a foaming agent through the foaming agent supply port 5 to the molten resin in the extruder 1. A high pressure pump 4 to be press-fitted, a cutting chamber 7 provided so that cooling water is brought into contact with a resin discharge surface in which a small hole of the die 2 is formed, and cooling water is circulated and supplied into the chamber, and a small hole of the die 2 The cutter 6 is rotatably provided in the cutting chamber 7 so as to cut the resin extruded from the resin, and the expandable polystyrene resin particles carried along with the flow of cooling water from the cutting chamber 7 are separated from the cooling water. And dehydration Dehydration dryer 10 with a solid-liquid separation function to obtain expandable polystyrene resin particles by drying, a water tank 8 for storing cooling water separated by the dehydration dryer 10 with a solid-liquid separation function, and cooling in the water tank 8 A high-pressure pump 9 for sending water to the cutting chamber 7 and a storage container 11 for storing expandable polystyrene resin particles dehydrated and dried by a dehydration dryer 10 with a solid-liquid separation function are configured.

  As the extruder 1, either an extruder using a screw or an extruder not using a screw can be used. Examples of the extruder using a screw include a single-screw extruder, a multi-screw extruder, a vent-type extruder, and a tandem extruder. Examples of the extruder that does not use a screw include a plunger type extruder and a gear pump type extruder. Moreover, any extruder can use a static mixer. Among these extruders, an extruder using a screw is preferable from the viewpoint of productivity. Moreover, the conventionally well-known thing used in the granulation method by melt extrusion of resin can also be used for the cutting chamber 7 which accommodated the cutter 6. FIG.

  In order to produce expandable polystyrene resin particles using the production apparatus shown in FIG. 1, first, the raw material polystyrene resin, liquid paraffin, aromatic hydrocarbon, inorganic foam nucleating agent and, if necessary, are added. A desired additive such as a foam nucleating agent is weighed and charged into the extruder 1 from the raw material supply hopper 3. The raw polystyrene resin may be pelletized or granulated and mixed well in advance and then fed from one raw material supply hopper. For example, when multiple lots are used, the supply amount for each lot may be reduced. A plurality of adjusted raw material supply hoppers may be charged and mixed in an extruder. Also, when using a combination of recycled materials from multiple lots, mix the raw materials from multiple lots in advance and remove foreign matter using appropriate sorting methods such as magnetic sorting, sieving, specific gravity sorting, and air blowing sorting. It is preferable to keep it.

  After supplying polystyrene resin, liquid paraffin, aromatic hydrocarbon, inorganic foam nucleating agent and other additives into the extruder 1, the resin is heated and melted, and the molten resin is transferred to the die 2 side while blowing the foaming agent. A foaming agent is injected from the supply port 5 by a high-pressure pump 4 to mix the foaming agent with the molten resin, and passes through a screen for removing foreign substances provided in the extruder 1 as necessary, while further kneading the melt, And the melted material to which the foaming agent has been added is extruded through a small hole in the die 2 attached to the tip of the extruder 1.

  The resin discharge surface in which the small holes of the die 2 are drilled is disposed in the cutting chamber 7 in which cooling water is circulated and supplied into the chamber, and the resin extruded from the small holes of the die 2 is placed in the cutting chamber 7. A cutter 6 is provided so as to be rotatable. Extruding the melt with the blowing agent added through a small hole in the die 2 attached to the tip of the extruder 1 causes the melt to be cut into granules, and at the same time, brought into contact with cooling water and rapidly cooled to solidify while suppressing foaming. Thus, expandable polystyrene resin particles are obtained.

  The formed expandable polystyrene resin particles are transferred from the cutting chamber 7 to the dewatering dryer 10 with a solid-liquid separation function along with the flow of the cooling water, where the expandable polystyrene resin particles are separated from the cooling water. And dehydrated and dried. The dried expandable polystyrene resin particles are stored in the storage container 11.

The method for producing a polystyrene resin foam molded article of the present invention is a liquid paraffin within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of polystyrene resin in the production method of expandable polystyrene resin particles by melt extrusion. When liquid paraffin is uniformly contained throughout the expandable polystyrene resin particles, a foamed molded product with a high expansion ratio can be obtained, and when it is manufactured using recycled polystyrene resin However, it is possible to efficiently produce expandable polystyrene resin particles capable of obtaining a foamed molded article having excellent mechanical strength such as bending strength.
Furthermore, with respect to 100 parts by mass of the polystyrene resin, the liquid paraffin is in the range of 0.01 to 5 parts by mass, the aromatic hydrocarbon is in the range of 0.15 to 3.0 parts by mass, and the inorganic foam nucleating agent is added. Addition within the range of 0.05 to 5 parts by mass, and by uniformly containing liquid paraffin, aromatic hydrocarbon and inorganic foam nucleating agent in the whole expandable polystyrene resin particles, foam molding with higher expansion ratio You can get a body.

(Polystyrene resin pre-expanded particles and polystyrene resin foam molding)
The expandable polystyrene resin particles of the present invention are pre-expanded by heating with water vapor heating or the like using a well-known apparatus and method in the field of manufacturing foamed resin molded articles, and then polystyrene-based resin pre-expanded particles (hereinafter referred to as pre-expanded particles). ). The pre-expanded particles are pre-expanded so as to have a bulk density equivalent to the density of the foamed molded product to be manufactured. In the present invention, its bulk density is not limited, usually in the range of 0.010~0.10g / cm ^3, preferably in the range of 0.015~0.050g / cm ^3.

In the present invention, the bulk density of the pre-expanded particles refers to those measured in accordance with JIS K6911: 1995 “General Test Method for Thermosetting Plastics”.
<Bulk density of pre-expanded particles>
First, Wg was sampled from pre-expanded particles as a measurement sample, this measurement sample was naturally dropped into a graduated cylinder, and the volume Vcm ³ of the measurement sample dropped into the graduated cylinder was measured using an apparent density measuring instrument based on JIS K6911. The bulk density of the pre-expanded particles is measured based on the following formula.
Bulk density (g / cm ³ ) = mass of measurement sample (W) / volume of measurement sample (V)

<Bulk expansion ratio of pre-expanded particles>
Moreover, the bulk expansion ratio of the pre-expanded particles is a numerical value calculated by the following equation.
Bulk foaming factor = 1 / bulk density (g / cm ³ )

The pre-expanded particles are filled in a cavity of a mold using a well-known apparatus and method in the field of manufacturing a foamed resin molded article, heated by steam heating or the like, and subjected to in-mold foam molding. -Based resin foam molded body (hereinafter referred to as foam molded body) is produced.
Although the density of the foamed molded article of the present invention is not particularly limited, usually in the range of 0.010~0.10g / cm ^3, preferably in the range of 0.015~0.050g / cm ^3.

In the present invention, the density of the foamed molded product refers to the density of the foamed molded product measured by the method described in JIS K7122: 1999 “Measurement of foamed plastic and rubber-apparent density”.
<Density of foam molding>
A test piece of 50 cm ³ or more (100 cm ³ or more in the case of semi-rigid and soft materials) was cut so as not to change the original cell structure of the material, its mass was measured, and calculated by the following formula.
Density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ )
Test piece condition adjustment and measurement test pieces were cut out from samples that had passed 72 hours or more after molding, and were subjected to atmospheric conditions of 23 ° C. ± 2 ° C. × 50% ± 5% or 27 ° C. ± 2 ° C. × 65% ± 5%. It has been left for more than an hour.

<Folding multiple of foamed molded product>
Further, the expansion factor of the foamed molded product is a numerical value calculated by the following equation.
Foaming factor = 1 / density (g / cm ³ )

The foamed molded product of the present invention is obtained by heating and foaming the expandable polystyrene resin particles according to the present invention, and the resulting pre-foamed particles are obtained by in-mold foam molding. You can get a body.
Moreover, even when manufactured using recycled polystyrene resin, a foamed molded article having excellent mechanical strength such as bending strength can be obtained.

[Example 1]
(Production of expandable polystyrene resin particles)
To 100 parts by mass of polystyrene resin (trade name “HRM-10N” manufactured by Toyo Styrene Co., Ltd.), 0.5 parts by mass of liquid paraffin (Matsumura Oil Co., Ltd., Sumoyle P70) having an average carbon number of 22 is added, and these have a diameter of 90 mm. Were continuously fed at 130 kg per hour. As the temperature inside the extruder, the maximum temperature was set at 210 ° C., and after dissolving the resin, 6 parts by mass of pentane (isopentane: normal pentane = 20: 80 (mass ratio)) with respect to 100 parts by mass of the resin as a foaming agent. Was press-fitted from the middle of the extruder. The resin and the foaming agent are kneaded and cooled in the extruder, the resin temperature at the tip of the extruder is maintained at 170 ° C., the pressure at the resin introduction part of the die is maintained at 12 MPa, the diameter is 0.6 mm, and the land length is 3 High speed with 10 blades at the same time as extruding the foaming agent-containing molten resin into a cutting chamber connected to the discharge side of this die and 200 ° C. water circulated from 200 dies with small holes of 0.0 mm The extrudate was cut with a rotary cutter. While the cut particles were cooled with circulating water, they were conveyed to a particle separator, and the particles were separated from the circulating water. Furthermore, the collected particles were dehydrated and dried to obtain pentane-containing expandable polystyrene resin particles. The obtained pentane-containing expandable polystyrene resin particles were almost perfect spheres without deformation and beard, and the average particle size was about 1.1 mm.
With respect to 100 parts by mass of the obtained pentane-containing expandable polystyrene resin particles, 0.03 part by mass of polyethylene glycol, 0.15 part by mass of zinc stearate, 0.05 part by mass of monoglyceride stearate, triglyceride hydroxystearate 05 parts by mass were uniformly coated on the entire surface of the resin particles.

<Measurement of expansion ratio>
The expandable polystyrene resin particles obtained above are heated in a box-type foaming tank with water vapor blown at a vapor pressure of 0.02 MPa for 3 minutes, and the bulk expansion ratio of the resulting pre-expanded particles is as described above. Measure and evaluate the following criteria:
The best foam expansion ratio is 65 times or more (◎◎),
Especially good when the bulk foaming ratio is 60 times or more and less than 65 times (◎),
Good bulk foaming ratio 50 times or more and less than 60 times (○)
The foaming magnification was evaluated by illuminating a bulk foaming factor of less than 50 times with a defect (x). The results are shown in Table 1.

(Manufacture of foam moldings)
Next, the expandable polystyrene resin particles produced as described above are supplied to a cylindrical batch-type pre-foaming machine without being stored in a cool box, and heated with steam having a blowing pressure of 0.05 MPa. Obtained. The obtained pre-expanded particles had a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times).
Subsequently, the pre-expanded particles obtained were allowed to stand at room temperature for 24 hours, and then the pre-expanded particles were filled into a mold having a rectangular cavity of length 400 mm × width 300 mm × height 50 mm. Thereafter, the inside of the cavity of the mold is heated with water vapor at a gauge pressure of 0.08 MPa for 20 seconds, and then cooled until the pressure in the cavity of the mold reaches 0.01 MPa. Opened, a rectangular foam molded body having a length of 400 mm, a width of 300 mm, and a height of 50 mm was taken out.
The obtained foamed molded article had a density of 0.020 g / cm ³ (foaming factor: 50 times).

<Average bubble diameter>
The average cell diameter of the foamed molded product refers to that measured according to the test method of ASTM D2842-69. Specifically, the foam molded body obtained in the examples (and comparative examples) is cut with a razor blade, and the cut surface is enlarged and photographed with a scanning electron microscope (S-3000N, manufactured by Hitachi, Ltd.). The photographed image was printed on A4 paper, and the average chord length (t) of the bubbles was calculated from the number of bubbles on an arbitrary straight line (length: 60 mm) by the following formula. However, the arbitrary straight lines were made so that the bubbles did not contact only at the contact points as much as possible (included in the number of bubbles if contacted). The measurement was performed at 10 locations, and after obtaining the average chord length, the bubble diameter was calculated to obtain the average bubble diameter D (μm). The results are shown in Table 1.
Average string length t = 60 / (number of bubbles × photo magnification)
Bubble diameter D = t / 0.616 × 1000

<Evaluation of bending strength>
About the foaming molding obtained in the Example (and comparative example), bending strength was measured according to the method of JIS A9511: 2006 "foaming plastic heat insulating material".
That is, using a Tensilon universal testing machine UCT-10T (manufactured by Orientec Co., Ltd.), the specimen size is 75 mm × 300 mm × 50 mm, the compression speed is 10 mm / min, the tip jig is a pressure wedge 10R, and a support base 10R. Measurement was performed under the condition of a distance between fulcrums of 200 mm, and the bending strength was calculated by the following formula. The number of test pieces was three, and the average value was obtained.
Bending strength (MPa) = 3FL / 2bh ²
[Where F represents the maximum bending load (N), L represents the distance between supporting points (mm), b represents the width (mm) of the test piece, and h represents the thickness (mm) of the test piece. ]
In this way, the average value of the bending strength is obtained, and the following evaluation criteria:
Particularly good when the bending strength is 0.28 MPa or more (◎),
Bending strength is 0.25 MPa or more and less than 0.28 MPa concave (O),
The bending strength of less than 0.25 MPa was illuminated with x, and the strength was evaluated. The results are shown in Table 1.

<Judgment>
The evaluation results in <Measurement of foaming ratio> and the results of <Evaluation of bending strength> were evaluated according to the following criteria. The results are shown in Table 1.
Good (O): When the evaluation result in <Measurement of foaming ratio> and the result of <Evaluation of bending strength> are both O, A or A.
Defect (x): When either or both of the evaluation result in <Measurement of foaming ratio> and the result of <Evaluation of bending strength> or both are X.

<Measurement of liquid paraffin>
Sample preparation:
(1) Measurement of residual gas amount by heat loss method Let A (g) be the mass of a sample (expandable polystyrene resin particles, pre-expanded particles, foamed molded product), wrap in aluminum foil, and weigh it again. (G). Heat treatment was performed in an oven at 145 ° C. for 1 hour to completely remove the gas in the sample. After that, the sample is allowed to stand for 10 minutes with a desiccator to adsorb the gas component adhering to the sample surface from which gas has been released, and the sample from which gas has been released is weighed again in an aluminum foil, and this is measured as C (g). And the amount of residual gas remaining in the sample was calculated by the following formula.
Residual gas amount (%) = (B (g) −C (g)) / A (g) × 100
(2) Measurement of liquid paraffin in resin After dissolving sample A (g) containing 2.0 g of resin calculated by the following formula in 15 ml of methyl ethyl ketone, 15 ml of ethanol was added and further dissolved. 10 ml of the supernatant was collected, 10 ml of tetrahydrofuran (THF) was added and stirred, and the liquid paraffin content with respect to 100 parts by mass of the resin was measured by high performance liquid chromatography under the following conditions.
Sample addition amount: A (g)
= Resin 2.0 g / [1- [Residual gas amount calculated by (1) (%)] / 100]
Measurement conditions Equipment: High performance liquid chromatograph HLC-802A
Column: JASCO Finepak GEL 101 2 Solvent: Tetrahydrofuran (THF)
Temperature: Column thermostat 38 ° C
RI detector 38 ℃
Devolatilization tank 45 ℃
Flow rate: 0.6 ml / min Injection volume: 500 μl

About Example 1, as a result of measuring content (mass part) of the liquid paraffin with respect to 100 mass parts of resin,
Expandable polystyrene resin particles: 0.5 parts by mass Pre-expanded particles: 0.5 parts by mass Foamed molded product: 0.5 parts by mass.

<Measurement of aromatic hydrocarbons>
Sample preparation:
(1) Measurement of residual gas amount by heat loss method The mass of the sample (expandable polystyrene resin particles) was set to A (g), wrapped in aluminum foil and weighed again, and this was set to B (g). Heat treatment was performed in an oven at 145 ° C. for 1 hour to completely remove the gas in the sample. After that, the sample is allowed to stand for 10 minutes with a desiccator to adsorb the gas component adhering to the sample surface from which gas has been released, and the sample from which gas has been released is weighed again in an aluminum foil, and this is measured as C (g). And the amount of residual gas remaining in the sample was calculated by the following formula.
Residual gas amount (%) = (B (g) −C (g)) / A (g) × 100
(2) Measurement of aromatic hydrocarbon in resin Sample A (g) containing 0.2 g of resin calculated by the following formula was dissolved in 20 mL vial with 1 mL of diethylbenzene (DEB) -containing dimethylformamide (DMF), and 90 The mixture was heated at 1 ° C. for 1 hour, and then the gas phase was sampled, and the content (mass part) of the aromatic hydrocarbon relative to 100 parts by mass of the resin was measured by gas chromatography (manufactured by Shimadzu Corporation, GC-18A).
Sample addition amount: A (g)
= Resin 0.2 g / [1- [Residual gas amount calculated by (1) (%)] / 100]
Measurement conditions Equipment: Gas chromatograph (Shimadzu Corporation, GC-18A)
Column: J & W, DB-WAX (φ0.25 mm × 30 m, film thickness 0.25 μm)
Detector: FID
Column temperature condition: After holding at 50 ° C. for 2 minutes, the temperature was raised to 100 ° C. at 10 ° C./minute, held at 100 ° C. for 5 minutes, then heated to 220 ° C. at 40 ° C./minute and held at 220 ° C. for 2 minutes.
Inlet temperature: 150 ° C
Detector temperature: 250 ° C
Measurement sample injection volume: 2 mL
Split ratio = 70: 1
Column flow rate: 1.6 mL / min (He)
Gas pressure: 122 kPa

[Example 2]
Except that the liquid paraffin was changed to 1.0 part by mass, expandable polystyrene resin particles, pre-expanded particles and foamed molded articles were produced in the same manner as in Example 1, and the average cell diameter, expansion ratio, bending strength, flow The amount of paraffin and the amount of aromatic hydrocarbon were measured. The results are shown in Table 1.

[Example 3]
Except for the addition of 0.5 parts by mass of talc, expandable polystyrene resin particles, pre-expanded particles and foamed molded articles were produced in the same manner as in Example 1, and the average cell diameter, expansion ratio, bending strength, The amount of liquid paraffin and the amount of aromatic hydrocarbons were measured. The results are shown in Table 1.

[Example 4]
In Example 1, polystyrene resin particles containing only liquid paraffin were prepared without adding a foaming agent. Next, the obtained polystyrene resin particles were put into an extruder, and expandable polystyrene resin particles, pre-expanded particles and a foamed molded article were produced in the same manner as in Example 1 except that talc and pentane were added. The average cell diameter, expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Example 5]
(Production of expandable polystyrene resin particles)
For 100 parts by mass of polystyrene resin (trade name “HRM-10N” manufactured by Toyo Styrene Co., Ltd.), 0.3 parts by mass of styrene, 0.3 parts by mass of talc, and liquid paraffin (Smoyl P70, manufactured by Matsumura Oil Co., Ltd.) Mass parts were added, and these were continuously fed to a single screw extruder having a diameter of 90 mm at 130 kg per hour. As the temperature inside the extruder, the maximum temperature was set at 210 ° C., and after dissolving the resin, 6 parts by mass of pentane (isopentane: normal pentane = 20: 80 (mass ratio)) with respect to 100 parts by mass of the resin as a foaming agent. Was press-fitted from the middle of the extruder. The resin and foaming agent are kneaded and cooled in the extruder, the resin temperature at the tip of the extruder is maintained at 170 ° C., the pressure at the resin introduction part of the die is maintained at 15 MPa, the diameter is 0.6 mm, and the land length is 3 High speed with 10 blades at the same time as extruding the foaming agent-containing molten resin into a cutting chamber connected to the discharge side of this die and 200 ° C. water circulated from 200 dies with small holes of 0.0 mm The extrudate was cut with a rotary cutter. While the cut particles were cooled with circulating water, they were conveyed to a particle separator, and the particles were separated from the circulating water. Furthermore, the collected particles were dehydrated and dried to obtain pentane-containing expandable polystyrene resin particles. The obtained pentane-containing expandable polystyrene resin particles were almost perfect spheres without deformation and beard, and the average particle size was about 1.1 mm.
With respect to 100 parts by mass of the obtained pentane-containing expandable polystyrene resin particles, 0.03 part by mass of polyethylene glycol, 0.15 part by mass of zinc stearate, 0.05 part by mass of monoglyceride stearate, triglyceride hydroxystearate 05 parts by mass were uniformly coated on the entire surface of the resin particles.

(Manufacture of foam moldings)
Next, the expandable polystyrene resin particles produced as described above are supplied to a cylindrical batch-type pre-foaming machine without being stored in a cool box, and heated with steam having a blowing pressure of 0.05 MPa. Obtained. The obtained pre-expanded particles had a bulk density of 0.0167 g / cm ³ (bulk expansion ratio: 60 times).
Subsequently, the pre-expanded particles obtained were allowed to stand at room temperature for 24 hours, and then the pre-expanded particles were filled into a mold having a rectangular cavity of length 400 mm × width 300 mm × height 50 mm. Thereafter, the inside of the cavity of the mold is heated with water vapor at a gauge pressure of 0.08 MPa for 20 seconds, and then cooled until the pressure in the cavity of the mold reaches 0.01 MPa. Opened, a rectangular foam molded body having a length of 400 mm, a width of 300 mm, and a height of 50 mm was taken out.
The obtained foamed molded product had a density of 0.0167 g / cm ³ (expansion factor: 60 times).
In the same manner as in Example 1, the average cell diameter, expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Example 6]
Except that 0.3 parts by mass of toluene was added instead of styrene, expandable polystyrene resin particles, pre-expanded particles and foamed molded articles were produced in the same manner as in Example 5, and the same as in Example 1. The average cell diameter, expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Example 7]
Except that 1.0 part by mass of styrene was added, expandable polystyrene-based resin particles, pre-expanded particles and a foamed molded article were produced in the same manner as in Example 5. The expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Example 8]
Except that 0.1 part by mass of styrene was added, expandable polystyrene resin particles, pre-expanded particles and a foamed molded product were produced in the same manner as in Example 5. The expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Example 9]
Except that 0.16 parts by mass of styrene was added, expandable polystyrene-based resin particles, pre-expanded particles and a foamed molded product were produced in the same manner as in Example 5. The expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Example 10]
Except that 2.5 parts by mass of styrene was added, expandable polystyrene resin particles, pre-expanded particles and a foamed molded product were produced in the same manner as in Example 5. The expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Example 11]
Except that 3.5 parts by mass of styrene was added, expandable polystyrene-based resin particles, pre-expanded particles and a foamed molded product were produced in the same manner as in Example 5. The expansion ratio, bending strength, liquid paraffin amount and aromatic hydrocarbon amount were measured. The results are shown in Table 1.

[Comparative Example 1]
Except that liquid paraffin was not added, expandable polystyrene resin particles, pre-expanded particles and a foamed molded article were produced in the same manner as in Example 1, and the average cell diameter, expansion ratio and bending strength were measured. The results are shown in Table 1.

[Comparative Example 2]
Except that the amount of liquid paraffin was 0.005 parts by mass, expandable polystyrene resin particles, pre-expanded particles and foamed molded articles were produced in the same manner as in Example 1, and the average cell diameter, expansion ratio and bending strength were measured. did. The results are shown in Table 1.

[Comparative Example 3]
Except that the amount of liquid paraffin was 7.0 parts by mass, expandable polystyrene resin particles, pre-expanded particles and foamed molded articles were produced in the same manner as in Example 1, and the average cell diameter, expansion ratio and bending strength were measured. . The results are shown in Table 1.

From the results of Table 1, in Examples 1 to 11 according to the present invention, the liquid paraffin is uniformly distributed in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin in the entire expandable polystyrene resin particles. By using the contained structure, it is possible to increase the bulk expansion ratio of the pre-expanded particles obtained by heating and pre-expanding, and to obtain a foamed molded article having a high expansion ratio. Moreover, the foaming molding excellent in mechanical strength, such as bending strength, can be obtained.
Moreover, the liquid paraffin is uniformly contained in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin, and the aromatic hydrocarbon is contained in 100 parts by mass of the polystyrene resin. On the other hand, it was uniformly contained within the range of 0.15 to 3.0 parts by mass, and the inorganic foam nucleating agent was uniformly contained within the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin. In Examples 5 to 11, a higher expansion ratio was obtained than in Examples 1 to 4, and a foamed molded article having a high expansion ratio and good bending strength was obtained.
However, Examples 1-4, 8, and 11 are reference examples.

On the other hand, Comparative Example 1 to which liquid paraffin was not added was inferior in foaming ratio and bending strength as compared with Examples 1 to 4.
Further, Comparative Example 2 in which the amount of liquid paraffin added was less than the range of the present invention and Comparative Example 3 exceeding the range of the present invention were inferior in foaming ratio and bending strength as compared with Examples 1 to 4. .

  The present invention relates to a method for producing expandable polystyrene resin particles by melt extrusion, and relates to a foamable polystyrene resin particle capable of obtaining a foamed molded article having a high expansion ratio and excellent mechanical strength, a method for producing the same, and a polystyrene type The present invention relates to resin pre-expanded particles and polystyrene-based resin foam moldings.

  DESCRIPTION OF SYMBOLS 1 ... Extruder (resin supply apparatus), 2 ... Die, 3 ... Raw material supply hopper, 4 ... High pressure pump, 5 ... Foam supply port, 6 ... Cutter, 7 ... Cutting chamber, 8 ... Water tank, 9 ... High pressure pump, 10: Dehydration dryer with solid-liquid separation function, 11: Storage container.

Claims (9)

When a foaming agent is press-fitted and kneaded into the polystyrene resin melted in the resin supply device, the molten resin containing the foaming agent is extruded directly into the cooling liquid through a small hole in the die attached to the tip of the resin supply device. At the same time, the extrudate is cut with a high-speed rotary blade, and the extrudate is cooled and solidified by contact with a liquid to obtain expandable polystyrene resin particles.
Liquid paraffin is uniformly contained within the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of polystyrene resin, and aromatic hydrocarbons are 0 with respect to 100 parts by mass of polystyrene resin. It is uniformly contained within the range of 15 to 3.0 parts by mass, and the inorganic foam nucleating agent is uniformly contained within the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin. Characteristic foamable polystyrene resin particles. The expandable polystyrene resin particles according to claim 1 , wherein the inorganic foam nucleating agent is talc. The foaming property according to claim 1 or 2 , wherein the liquid paraffin is a mixture of olefin-based saturated hydrocarbons, has an average carbon number in the range of 20 to 35, and is liquid at normal temperature. Polystyrene resin particles. When a foaming agent is press-fitted and kneaded into the polystyrene resin melted in the resin supply device, the molten resin containing the foaming agent is extruded directly into the cooling liquid through a small hole in the die attached to the tip of the resin supply device. At the same time, the extrudate is cut with a high-speed rotary blade, and the extrudate is cooled and solidified by contact with a liquid to obtain expandable polystyrene resin particles. In the method for producing expandable polystyrene resin particles by melt extrusion,
With respect to 100 parts by mass of the polystyrene resin, the liquid paraffin is in the range of 0.01 to 5 parts by mass, the aromatic hydrocarbon is in the range of 0.15 to 3.0 parts by mass, and the inorganic foam nucleating agent is in the range of 0.005. An expandable polystyrene resin particle characterized by being added within a range of from 5 to 5 parts by mass and uniformly containing liquid paraffin, aromatic hydrocarbon and inorganic foam nucleating agent throughout the expandable polystyrene resin particle. Production method. The method for producing expandable polystyrene resin particles according to claim 4 , wherein the inorganic foam nucleating agent is talc. 6. The foaming property according to claim 4 or 5 , wherein the liquid paraffin is a mixture of olefin-based saturated hydrocarbons, has an average carbon number in the range of 20 to 35, and is liquid at room temperature. A method for producing polystyrene resin particles. Polystyrene resin pre-expanded particles obtained by heating and foaming the expandable polystyrene resin particles according to any one of claims 1 to 3 . A polystyrene-based resin foam molded article obtained by filling the polystyrene-based resin pre-expanded particles according to claim 7 into a cavity of a molding die and heating and molding in-mold foam molding.   Liquid paraffin is uniformly contained within the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polystyrene resin, and the aromatic hydrocarbon is 0.15 to 100 parts by mass of the polystyrene resin. It is uniformly contained within a range of 3.0 parts by mass, and the inorganic foam nucleating agent is uniformly contained within a range of 0.05 to 5 parts by mass with respect to 100 parts by mass of a polystyrene resin. Polystyrene resin foam molding.

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