Expanded polystyrene resin particles, pre-expanded polystyrene resin particles, and polystyrene resin foam molded article

Abstract

To provide foamable styrenic resin particles which can suppress blocking when foamable styrenic resin particles are preliminary foamed, can express sufficient heat fusion integration between preliminarily foamed particles when preliminarily foamed styrenic resin particles are secondarily foamed, and can suppress additive peeling in piping at the time of transportation by the piping.SOLUTION: There provided foamable styrenic resin particles in which the surface of a foamable styrenic resin particle body is coated with a powder additive and a liquid additive, where an average particle diameter of the power additive is within a range of 1 μm to 50 μm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to expandable polystyrene resin particles, pre-expanded polystyrene resin particles, and a polystyrene resin foam molded article.

Background Art

[0002] Foam molded articles are lightweight, excellent in heat insulation and mechanical strength, and are therefore used as heat insulating materials for housing and automobiles, heat insulating materials for building materials, backfill materials for expanded polystyrene civil engineering methods, transport packaging materials such as fish boxes and food containers, and cushioning materials. Among them, in-mold foam molded articles produced from expandable particles (typically expandable polystyrene resin particles or pre-expanded expandable polystyrene resin particles) are widely used because of advantages such as being easy to obtain a desired shape. Such a foam molded article is composed of a plurality of expandable particles fused to each other.

[0003] The characteristics required for expandable polystyrene resin particles include, for example, when heating expandable polystyrene resin particles with steam or the like to pre-expand them, a plurality of expandable polystyrene resin particles do not coalesce into one during the pre-expansion process, that is, so-called blocking does not occur, and when secondary foaming pre-expanded expandable polystyrene resin particles, the pre-expanded particles are sufficiently heat-fused and integrated with each other.

[0004] When the above-described blocking occurs during pre-expansion of expandable polystyrene resin particles, when filling the pre-expanded expandable polystyrene resin particles into the mold of a foam molding machine, the pre-expanded expandable polystyrene resin particles clog in the feeder, and as a result, a problem occurs in that the filling of the pre-expanded expandable polystyrene resin particles into the mold of the foam molding machine is defective, and a good foam molded product cannot be obtained. In addition, when secondary foaming pre-expanded expandable polystyrene resin particles, if the pre-expanded expandable polystyrene resin particles are not sufficiently heat-fused and integrated with each other, a problem occurs in that the mechanical strength of the obtained foam molded product becomes insufficient.

[0005] For the purpose of preventing blocking between expandable polystyrene resin particles during pre - foaming of expandable polystyrene resin particles, a fatty acid metal salt (for example, zinc stearate) is adhered to the surface of the expandable polystyrene resin particles as an anti - blocking agent. Also, for the purpose of improving the heat - fusion property between pre - foamed polystyrene resin particles during the secondary foaming of pre - foamed polystyrene resin particles, the surface of the expandable polystyrene resin particles is coated with a fatty acid triglyceride. For the purpose of preventing dust and the like from adhering to the surface of the expandable polystyrene resin particles due to static electricity, the surface of the expandable polystyrene resin particles is coated with a fatty acid monoglyceride. These fatty acid metal salts, fatty acid triglycerides, and fatty acid monoglycerides are usually solid powder additives at normal temperature.

[0006] Here, in the process of manufacturing a foamed molded article by foaming expandable polystyrene resin particles, the expandable polystyrene resin particles are supplied into the pre - foaming machine through an expandable particle flow - through pipe (pipe) with one end connected to the pre - foaming machine by air transportation that sucks the particles toward the pre - foaming machine through the expandable particle flow - through pipe. At the same time, the pre - foamed polystyrene resin particles obtained by pre - foaming in this pre - foaming machine are also supplied into a silo or a foaming molding machine through a pre - foamed particle flow - through pipe (pipe) with one end connected to the silo or the foaming molding machine by air transportation that sucks the particles toward the silo or the foaming molding machine through the pre - foamed particle flow - through pipe. These expandable particle flow - through pipes and pre - foamed particle flow - through pipes are arranged in a state of being partially or entirely curved according to the arrangement of the pre - foaming machine and the foaming molding machine.

[0007] Then, when transporting expandable polystyrene resin particles added with the above - mentioned powder additive through pipes such as the above - mentioned expandable particle flow - through pipes and pre - foamed particle flow - through pipes, a problem occurs in that the powder additive peels off in the pipe due to its powder property, and deposits of the peeled - off matter accumulate in the pipe.

[0008] In order to solve the problem of peeling of such powder additives, a technique has been reported in which a predetermined amount of methylphenylpolysiloxane and dimethylpolysiloxane, which are liquid at room temperature, is applied to the surface of expandable polystyrene resin particles (Patent Document 1). However, when a predetermined amount of methylphenylpolysiloxane and dimethylpolysiloxane is applied to the surface of expandable polystyrene resin particles as described in Patent Document 1, the amount of blocking between the particles is large, and there is room for improvement.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention has been made to solve the above-described conventional problems. The main object thereof is to suppress blocking when pre-expanding expandable polystyrene resin particles, to achieve sufficient thermal fusion integration between the pre-expanded particles when secondarily expanding the pre-expanded expandable polystyrene resin particles, and to suppress additive peeling in a pipe when transporting by a pipe. An object is to provide expandable polystyrene resin particles. Another object is to provide pre-expanded expandable polystyrene resin particles obtained by pre-expanding such expandable polystyrene resin particles. Furthermore, an object is to provide a styrene resin foam molded article formed from such expandable polystyrene resin particles or pre-expanded expandable polystyrene resin particles.

Means for Solving the Problems

[0011] The present inventors have conducted intensive studies to solve the above problems. As a result, in the expandable polystyrene resin particles in which the surface of the expandable polystyrene resin particle body is coated with an additive, a powder additive and a liquid additive are used in combination as the additive, and attention is paid to the average particle diameter of the powder additive. As a result, the inventors have conceived that the effects of the present invention can be achieved by adjusting the average particle diameter of the powder additive within a predetermined narrow range. Further, the inventors have conceived that the effects of the present invention can be more effectively achieved by adjusting the quantitative ratio of the powder additive and the liquid additive within a predetermined range.

[0012] The expandable polystyrene resin particles according to an embodiment of the present invention are expandable polystyrene resin particles in which the surface of the expandable polystyrene resin particle body is coated with a powder additive and a liquid additive, wherein the average particle diameter of the powder additive is in the range of 1 μm to 50 μm.

[0013] In one embodiment, the weight of the powder additive is 1.0 to 30.0 times the weight of the liquid additive.

[0014] In one embodiment, the ratio of the powder additive to 100 parts by weight of the expandable polystyrene resin particle body is 0.050 to 1.500 parts by weight.

[0015] In one embodiment, the ratio of the liquid additive to 100 parts by weight of the expandable polystyrene resin particle body is 0.005 to 0.250 parts by weight.

[0016] In one embodiment, the powder additive is at least one selected from fatty acid metal salts, solid fatty acid esters, hydrogenated oils, carbonates, fatty acid amides, and amine compounds.

[0017] In one embodiment, the liquid additive is at least one selected from polyethers, polyhydric alcohols, liquid paraffins, liquid fatty acid esters, and liquid polysiloxanes.

[0018] The pre-expanded polystyrene resin particles according to an embodiment of the present invention are pre-expanded polystyrene resin particles obtained by pre-expanding the above expandable polystyrene resin particles, wherein the bulk expansion ratio of the pre-expansion is 2 to 150 times.

[0019] The polystyrene resin foam molded article according to an embodiment of the present invention is molded from the above expandable polystyrene resin particles.

[0020] The polystyrene resin foam molded article according to an embodiment of the present invention is molded from the above pre-expanded polystyrene resin particles.

Effect of the Invention

[0021] According to the present invention, it is possible to suppress blocking when pre-expanding expandable polystyrene resin particles, to exhibit sufficient thermal fusion integration between the pre-expanded polystyrene resin particles when secondary expanding the pre-expanded polystyrene resin particles, and to suppress additive peeling in the pipe during transportation by the pipe. It is possible to provide expandable polystyrene resin particles. Further, it is possible to provide pre-expanded polystyrene resin particles obtained by pre-expanding such expandable polystyrene resin particles. Furthermore, it is possible to provide a polystyrene resin foam molded article molded from such expandable polystyrene resin particles or pre-expanded polystyrene resin particles.

Brief Description of the Drawings

[0022]

Figure 1

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0024] In this specification, when "(meth)acryl" is mentioned, it means acrylic and / or methacrylic, and when "(meth)acrylate" is mentioned, it means acrylate and / or methacrylate. "Weight" in this specification is synonymous with "mass" in the SI unit system and may be read as "mass".

[0025] ≪≪A. Expansible polystyrene resin particles≫≫ The expansible polystyrene resin particles according to an embodiment of the present invention are those in which the surface of the expansible polystyrene resin particle body is coated with a powder additive and a liquid additive.

[0026] The powder additive is an additive that is solid at normal temperature (typically 23°C). In the present invention, the powder additive is an externally added powder additive added to the expansible polystyrene resin particle body. The powder additive may be only one kind or two or more kinds.

[0027] The liquid additive is an additive that is liquid at normal temperature (typically 23°C). In the present invention, the liquid additive is an externally added liquid additive added to the expansible polystyrene resin particle body. The liquid additive may be only one kind or two or more kinds.

[0028] The powder additive can exhibit the effects of the present invention when its average particle size is in the range of 1 μm to 50 μm, preferably in the range of 3 μm to 45 μm, more preferably in the range of 5 μm to 40 μm, still more preferably in the range of 7 μm to 35 μm, and particularly preferably in the range of 8 μm to 30 μm. By adjusting the average particle size of the powder additive within the narrow range as described above, the effects of the present invention can be exhibited. When the average particle size of the powder additive is outside the above range, it becomes difficult to exhibit the effects of the present invention. In particular, when transporting expandable polystyrene resin particles through a pipe, the powder additive may peel off and deposits of the peeled-off material may accumulate in the pipe. The average particle size is measured as follows: 0.001 g of the powder additive and one drop of a 0.6% sodium linear dodecylbenzenesulfonate solution are preliminarily dispersed on a slide glass and covered with a cover glass. Then, using a digital microscope VHX-6000 manufactured by Keyence Corporation, the particle sizes of 20 randomly selected powder additive particles are measured at a magnification of 1000 times, and the average of the 20 particle sizes is taken as the measured value of the average particle size of the powder additive.

[0029] Here, the definition of the above range of the average particle size means that when there are multiple powder additives, the average particle size of each powder additive is within that range.

[0030] In terms of being able to exhibit the effects of the present invention, the weight of the powder additive is preferably 1.0 to 30.0 times, more preferably 1.5 to 30.0 times, still more preferably 1.5 to 25.0 times, and particularly preferably 1.5 to 22.5 times the weight of the liquid additive. If the ratio of the weight of the powder additive to the weight of the liquid additive is too small and outside the above range, the stickiness of the expandable polystyrene resin particles becomes strong, and when they collide with the inner surface of the flow pipe during suction transportation, the skin layer of the expandable polystyrene resin particles may easily adhere to the inner surface of the flow pipe, possibly causing blockage of the flow pipe. If the ratio of the weight of the powder additive to the weight of the liquid additive is too large and outside the above range, when the expandable polystyrene resin particles are circulated in the particle flow pipe (pipe), the powder additive may peel off and deposits of the peeled-off material may accumulate in the pipe.

[0031] The ratio of the powder additive to 100 parts by weight of the expandable polystyrene resin particle body is preferably 0.050 to 1.500 parts by weight, more preferably 0.100 to 1.500 parts by weight, still more preferably 0.100 to 1.000 parts by weight, and particularly preferably 0.150 to 1.000 parts by weight in terms of more effectively expressing the effects of the present invention. If the ratio of the powder additive to 100 parts by weight of the expandable polystyrene resin particle body is less than the above range, the effect of the powder additive cannot be obtained, and there is a risk of blocking when pre-expanding the expandable polystyrene resin particles, or a risk of poor fusion when molding the pre-expanded polystyrene resin particles. If the ratio of the powder additive to 100 parts by weight of the expandable polystyrene resin particle body is more than the above range, when the expandable polystyrene resin particles or the pre-expanded polystyrene resin particles obtained by pre-expanding them are circulated in the particle flow pipe (pipe), the powder additive may peel off and deposits of the peeled-off matter may accumulate in the pipe.

[0032] As the powder additive, any suitable powder-like external additive can be adopted as long as the effects of the present invention are not impaired. In terms of more effectively expressing the effects of the present invention, such a powder additive is preferably at least one selected from fatty acid metal salts, solid fatty acid esters, hydrogenated oils, carbonates, fatty acid amides, and amine compounds, and more preferably contains a fatty acid metal salt as an essential component and at least one selected from solid fatty acid esters, hydrogenated oils, carbonates, and amine compounds.

[0033] As the fatty acid metal salt, any appropriate fatty acid metal salt can be adopted as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, such fatty acid metal salts preferably include zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, lithium stearate, barium stearate, zinc laurate, calcium laurate, and barium laurate. More preferably, they are zinc stearate and magnesium stearate. Usually, the fatty acid constituting the commercially available fatty acid metal salt is a mixture of stearic acid as the main component and palmitic acid, myristic acid, lauric acid, arachidic acid, behenic acid, etc. In the present invention as well, such commercially available products can be used as the fatty acid metal salt.

[0034] When using a fatty acid metal salt as the powder additive, the ratio of the fatty acid metal salt to 100 parts by weight of the expandable styrene resin particle body is preferably 0.005 part by weight to 1.000 part by weight, more preferably 0.050 part by weight to 1.000 part by weight, still more preferably 0.050 part by weight to 0.800 part by weight, and particularly preferably 0.080 part by weight to 0.800 part by weight in terms of being able to more effectively exhibit the effects of the present invention. If the ratio of the fatty acid metal salt to 100 parts by weight of the expandable styrene resin particle body is too low outside the above range, there is a risk of blocking when pre-expanding the expandable styrene resin particles. If the ratio of the fatty acid metal salt to 100 parts by weight of the expandable styrene resin particle body is too high outside the above range, when the expandable styrene resin particles are circulated in the particle flow pipe (pipe), the powder additive may peel off, and there is a risk of the peeled matter accumulating in the pipe.

[0035] As the solid fatty acid ester, any appropriate solid fatty acid ester can be employed as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, such a solid fatty acid ester is preferably a polyhydric alcohol fatty acid ester, and preferably an ester of a higher fatty acid having 10 to 24 carbon atoms and a polyhydric alcohol such as ethylene glycol, glycerin, 1,2,4-butanetriol, diglycerin, pentaerythritol, sorbitol, erythritol, hexanetriol, etc. More preferably, it is an ester of a higher fatty acid having 10 to 24 carbon atoms and glycerin (glycerin fatty acid ester). Such glycerin fatty acid esters include esters of fatty acids with monoglycerin, esters of fatty acids with diglycerin, esters of fatty acids with triglycerin, and esters of fatty acids with tetraglycerin.

[0036] Examples of glycerin fatty acid esters include monoglyceride laurate, diglyceride laurate, triglyceride laurate, monoglyceride palmitate, diglyceride palmitate, triglyceride palmitate, monoglyceride stearate, diglyceride stearate, triglyceride stearate, tetraglyceride stearate, monoglyceride behenate, diglyceride behenate, triglyceride behenate, monoglyceride 12-hydroxystearate, diglyceride 12-hydroxystearate, triglyceride 12-hydroxystearate, triglyceride linoleate, diglyceride linoleate, monoglyceride linoleate, glyceryl myristate, glyceryl palmitate, glyceryl behenate, glyceryl oleate.

[0037] When using a solid fatty acid ester as a powder additive, the ratio of the solid fatty acid ester to 100 parts by weight of the expandable styrene resin particle body is preferably 0.005 to 1.000 parts by weight, more preferably 0.050 to 1.000 parts by weight, still more preferably 0.050 to 0.500 parts by weight, and particularly preferably 0.050 to 0.150 parts by weight, in terms of more effectively expressing the effects of the present invention. If the ratio of the solid fatty acid ester to 100 parts by weight of the expandable styrene resin particle body is less than the above range, there is a risk of poor fusion when molding the pre-expanded styrene resin particles. If the ratio of the solid fatty acid ester to 100 parts by weight of the expandable styrene resin particle body is more than the above range, when the expandable styrene resin particles are circulated in a particle flow pipe (pipe), the powder additive may peel off, and there is a risk of deposition of the peeled material in the pipe.

[0038] As the hydrogenated oil, any suitable hydrogenated oil can be employed as long as the effects of the present invention are not impaired. When using a hydrogenated oil as a powder additive, the ratio of the hydrogenated oil to 100 parts by weight of the expandable styrene resin particle body can be set at any appropriate ratio as long as the effects of the present invention are not impaired.

[0039] As the carbonate, any suitable carbonate can be employed as long as the effects of the present invention are not impaired. In terms of more effectively expressing the effects of the present invention, such carbonates preferably include calcium carbonate, sodium carbonate, potassium carbonate, and magnesium carbonate, and more preferably calcium carbonate.

[0040] When using a carbonate as a powder additive, the ratio of calcium carbonate to 100 parts by weight of the expandable styrene resin particle body is preferably 0.010 to 0.100 parts by weight, more preferably 0.010 to 0.090 parts by weight, still more preferably 0.020 to 0.090 parts by weight, and particularly preferably 0.020 to 0.040 parts by weight in terms of more effectively expressing the effects of the present invention. If the ratio of the carbonate to 100 parts by weight of the expandable styrene resin particle body is too low outside the above range, there is a risk of blocking when pre-expanding the expandable styrene resin particles. If the ratio of the carbonate to 100 parts by weight of the expandable styrene resin particle body is too high outside the above range, when the expandable styrene resin particles are circulated in the particle flow pipe (pipe), the powder additive may peel off, and there is a risk that the peeled matter will accumulate in the pipe.

[0041] As the amine compound, any appropriate amine compound can be employed as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, typically, hydroxyalkylamine can be employed as such an amine compound. In terms of being able to more effectively exhibit the effects of the present invention, examples of such hydroxyalkylamine 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, and N-hydroxypentyl-N-(2-hydroxyoctadecyl)amine. Preferably, it is N-hydroxyethyl-N-(2-hydroxyalkyl)amine.

[0042] Here, for N-hydroxyethyl-N-(2-hydroxyalkyl)amine, N-hydroxyethyl-N-(2-hydroxyalkyl)amine having 2-hydroxyalkyl groups with various carbon numbers is available. Examples of such N-hydroxyethyl-N-(2-hydroxyalkyl)amine typically include those mainly composed of N-hydroxyethyl-N-(2-hydroxyalkyl)amine having a 2-hydroxyalkyl group with 8 to 16 carbon atoms. For example, those mainly composed of N-hydroxyethyl-N-(2-hydroxyalkyl)amine having a 2-hydroxyalkyl group with 14 carbon atoms can be mentioned.

[0043] When a hydroxyalkylamine is used as the powder additive, the ratio of the hydroxyalkylamine to 100 parts by weight of the expandable styrene resin particle body is preferably 0.010 to 1.500 parts by weight, more preferably 0.010 to 1.000 parts by weight, still more preferably 0.010 to 0.500 parts by weight, and particularly preferably 0.050 to 0.500 parts by weight in terms of more effectively expressing the effects of the present invention. If the ratio of the hydroxyalkylamine to 100 parts by weight of the expandable styrene resin particle body is less than the above range, the styrene resin foam molded body may be charged with electricity, and dust may easily adhere to the surface of the styrene resin foam molded body. If the ratio of the hydroxyalkylamine to 100 parts by weight of the expandable styrene resin particle body exceeds the above range, when the expandable styrene resin particles are circulated in the particle flow pipe (pipe), the powder additive may peel off, and there is a risk that the peeled matter will accumulate in the pipe.

[0044] The ratio of the liquid additive to 100 parts by weight of the expandable styrene resin particle body is preferably 0.005 to 0.500 parts by weight, more preferably 0.010 to 0.500 parts by weight, still more preferably 0.010 to 0.200 parts by weight, and particularly preferably 0.020 to 0.200 parts by weight in terms of more effectively expressing the effects of the present invention. If the ratio of the liquid additive to 100 parts by weight of the expandable styrene resin particle body is less than the above range, the effect of the liquid additive cannot be obtained, and blocking and static electricity are likely to occur when the expandable styrene resin particles are pre-expanded, and there is also a risk of poor fusion when the pre-expanded polystyrene resin particles are molded. If the ratio of the liquid additive to 100 parts by weight of the expandable styrene resin particle body exceeds the above range, the surfaces of the pre-expanded styrene resin particles and the styrene resin foam molded body may become sticky.

[0045] As the liquid additive, any suitable liquid external additive can be employed as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, such a liquid additive is preferably at least one selected from polyethers, polyhydric alcohols, liquid paraffin, liquid fatty acid esters, and liquid polysiloxanes, and more preferably contains polyether as an essential component and at least one selected from polyhydric alcohols, liquid paraffin, liquid fatty acid esters, and liquid polysiloxanes.

[0046] As the polyether, any suitable polyether can be employed as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, such a polyether includes, for example, polyethylene glycol.

[0047] When using polyether as the liquid additive, the proportion of polyether relative to 100 parts by weight of the expandable styrene resin particle body is preferably 0.010 to 0.200 parts by weight, more preferably 0.010 to 0.150 parts by weight, still more preferably 0.020 to 0.150 parts by weight, and particularly preferably 0.040 to 0.100 parts by weight in terms of being able to more effectively exhibit the effects of the present invention. If the proportion of polyether relative to 100 parts by weight of the expandable styrene resin particle body is less than the above range, static electricity is likely to be generated during pre-expansion. If the proportion of polyether relative to 100 parts by weight of the expandable styrene resin particle body is more than the above range, the surfaces of the pre-expanded styrene resin particles and the styrene resin foam molded article may become sticky.

[0048] As the polyhydric alcohol, any suitable polyhydric alcohol can be employed as long as the effects of the present invention are not impaired. When using a polyhydric alcohol as the liquid additive, the proportion of the polyhydric alcohol relative to 100 parts by weight of the expandable styrene resin particle body can be set to any suitable proportion as long as the effects of the present invention are not impaired.

[0049] As the liquid paraffin, any appropriate liquid paraffin can be adopted as long as the effects of the present invention are not impaired. When using liquid paraffin as the liquid additive, the ratio of the liquid paraffin to 100 parts by weight of the expandable styrene resin particle body can be set to any appropriate ratio as long as the effects of the present invention are not impaired.

[0050] As the liquid fatty acid ester, any appropriate liquid fatty acid ester can be adopted as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, examples of such liquid fatty acid esters include polyethylene glycol monooleate, 2-ethylhexyl oleate, neopentyl glycol, polyoxyethylene monolaurate, polyoxyethylene coconut oil fatty acid glyceryl, sorbitan monolaurate, and medium-chain fatty acid triglyceride.

[0051] When using a liquid fatty acid ester as the liquid additive, the ratio of the liquid fatty acid ester to 100 parts by weight of the expandable styrene resin particle body is preferably 0.001 part by weight to 1.000 part by weight, more preferably 0.002 part by weight to 1.000 part by weight, still more preferably 0.002 part by weight to 0.100 part by weight, and particularly preferably 0.005 part by weight to 0.050 part by weight in terms of being able to more effectively exhibit the effects of the present invention. If the ratio of the liquid fatty acid ester to 100 parts by weight of the expandable styrene resin particle body is less than the above range, there is a risk of poor fusion when molding the pre-expanded polystyrene resin particles. If the ratio of the liquid fatty acid ester to 100 parts by weight of the expandable styrene resin particle body is more than the above range, the surfaces of the pre-expanded styrene resin particles and the styrene resin foam molded body may become sticky.

[0052] As the liquid polysiloxane, any appropriate liquid polysiloxane can be adopted as long as the effects of the present invention are not impaired. In terms of being able to more effectively exhibit the effects of the present invention, examples of such liquid polysiloxanes include dimethylpolysiloxane and methylphenylpolysiloxane.

[0053] When using liquid polysiloxane as the liquid additive, the ratio of the liquid polysiloxane to 100 parts by weight of the expandable styrene resin particle body is preferably 0.005 to 0.500 parts by weight, more preferably 0.005 to 0.250 parts by weight, still more preferably 0.010 to 0.250 parts by weight, and particularly preferably 0.010 to 0.100 parts by weight in terms of more effectively expressing the effects of the present invention. If the ratio of the liquid polysiloxane to 100 parts by weight of the expandable styrene resin particle body is less than the above range, there is a risk of blocking during pre-foaming. If the ratio of the liquid polysiloxane to 100 parts by weight of the expandable styrene resin particle body is more than the above range, the surfaces of the pre-foamed styrene resin particles and the styrene resin foam molded body may become sticky.

[0054] The expandable styrene resin particles as a whole have the shape of particles. The average particle diameter of the expandable styrene resin particles is preferably 0.1 mm to 2.0 mm, more preferably 0.1 mm to 1.7 mm, still more preferably 0.2 mm to 1.7 mm, and particularly preferably 0.2 mm to 1.5 mm. The average particle diameter can be measured in accordance with JIS Z 8815. Specifically, the average particle diameter is the particle diameter at the 50% integrated value measured from the particle size distribution by the sieving test of JIS Z 8815. As the specific shape of the expandable styrene resin particles, any appropriate shape can be adopted as long as the effects of the present invention are not impaired. Such shapes include, for example, spherical, substantially spherical, ellipsoidal (oval), cylindrical, and substantially cylindrical.

[0055] The expandable styrene resin particles preferably have a weight average molecular weight of 190,000 to 490,000.

[0056] ≪A-1. Expandable Styrene Resin Particle Body≫ The expandable styrene resin particle body contains a styrene resin and a foaming agent.

[0057] <A-1-1. Styrene Resin> A styrene resin is a polymer compound containing a styrene monomer as a monomer component constituting the styrene resin. The styrene monomer includes styrene or a styrene derivative. Examples of the styrene derivative include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromostyrene, and the like. The styrene monomer may be only one kind or two or more kinds. The styrene monomer preferably contains at least styrene. The content ratio of styrene to the total amount of the styrene monomer is preferably 50% by weight or more, more preferably 70% by weight or more, still more preferably 90% by weight or more, and particularly preferably 95% by weight or more.

[0058] The styrene resin only needs to contain a styrene monomer as a main component of the monomer component constituting the styrene resin, and may be a copolymer of the styrene monomer and a copolymerization component. Representative examples of the copolymerization component typically include vinyl monomers. In this specification, the "main component" means that the content ratio of the component in all components is preferably 50% by weight or more, more preferably 70% by weight or more, still more preferably 90% by weight or more, and particularly preferably 95% by weight or more.

[0059] Examples of the vinyl monomer include polyfunctional monomers, (meth)acrylic acid ester monomers, maleic acid ester monomers, fumaric acid ester monomers, and the like. The vinyl monomer may be only one kind or two or more kinds.

[0060] Specific examples of the polyfunctional monomer include, for example, divinylbenzenes such as o-divinylbenzene, m-divinylbenzene, p-divinylbenzene; alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate; and the like. By using the polyfunctional monomer, a branched structure can be imparted to the polystyrene resin. The content of the polyfunctional monomer in all the monomer components constituting the polystyrene resin is preferably 0 wt% to 0.1 wt%, more preferably 0.005 wt% to 0.05 wt%.

[0061] Specific examples of the (meth)acrylic acid ester monomer include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, and the like. Among these (meth)acrylic acid ester monomers, butyl acrylate, 2-ethylhexyl acrylate, and ethyl acrylate are preferred, and butyl acrylate is more preferred. By using the (meth)acrylic acid ester monomer, the glass transition temperature (Tg) of the styrene resin can be lowered. The content of the acrylic acid ester monomer in all the monomer components constituting the polystyrene resin is preferably 0 wt% to 4.0 wt%, more preferably 0.1 wt% to 3.0 wt%.

[0062] Examples of the maleic acid ester monomer include dimethyl maleate and the like.

[0063] Examples of the fumaric acid ester monomer include dimethyl fumarate, diethyl fumarate, ethyl fumarate, and the like.

[0064] In one embodiment, the styrenic resin may be a composite resin of a styrenic resin and an olefinic resin. The content ratio of the styrenic resin to the olefinic resin in the composite resin (styrenic resin / olefinic resin: weight ratio) is preferably 50 / 50 to 90 / 10, more preferably 60 / 40 to 85 / 15. If the content of the styrenic resin is too low, the foamability and / or the moldability may be insufficient. If the content of the styrenic resin is too high, the impact resistance and / or the flexibility may be insufficient.

[0065] As the olefinic resin, any suitable olefinic resin can be employed as long as the effects of the present invention are not impaired. The olefinic resin may be only one kind or two or more kinds. Specific examples include, for example, polyethylene resins such as branched low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, and cross-linked products of these polymers; polypropylene resins such as propylene homopolymer, propylene-vinyl acetate copolymer, ethylene-propylene random copolymer, propylene-1-butene copolymer, ethylene-propylene-butene random copolymer; and the like. Among these olefinic resins, preferably, ethylene-vinyl acetate copolymer, high density polyethylene, linear low density polyethylene, and mixtures thereof. The low density is preferably 0.91 g / cm 3 ~0.94 g / cm 3 and more preferably 0.91 g / cm 3 ~0.93 g / cm 3 The high density is preferably 0.95 g / cm 3 ~0.97 g / cm 3 and more preferably 0.95 g / cm 3 ~0.96 g / cm 3 The medium density is the density between the low density and the high density.

[0066] <A-1-2. Blowing Agent> The foaming agent may be only one kind or two or more kinds.

[0067] As the foaming agent, any appropriate foaming agent can be used as long as the effects of the present invention are not impaired. The foaming agent is preferably an organic compound having a boiling point below the softening point of the styrene resin and being gaseous or liquid at normal pressure. Specific examples include aliphatic hydrocarbons such as propane, n-butane, isobutane, pentane (n-pentane, isopentane or neopentane), n-hexane, etc.; alicyclic hydrocarbons such as cyclopentane, cyclopentadiene, etc.; ketones such as acetone, methyl ethyl ketone, etc.; alcohols such as methanol, ethanol, isopropyl alcohol, etc.; low-boiling ether compounds such as dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, etc.; halogen-containing hydrocarbons such as trichloromonofluoromethane, dichlorodifluoromethane, etc. Inorganic gases such as carbon dioxide gas, nitrogen, ammonia, etc. may be used as the foaming agent. Among these, aliphatic hydrocarbons are preferred as the foaming agent. This is because it can prevent the destruction of the ozone layer and can quickly replace the air, so that the change over time of the foamed molded article can be suppressed. More preferably, the foaming agent is propane, n-butane, isobutane, n-pentane, isopentane, and combinations thereof.

[0068] The content of the foaming agent in the foaming styrene resin particle body can be appropriately set according to the purpose as long as it is an amount sufficient to form the pre-expanded styrene resin particles and the styrene resin foamed molded article. The content of the foaming agent is preferably 2 parts by weight to 16 parts by weight, more preferably 3 parts by weight to 8 parts by weight, based on 100 parts by weight of the polystyrene resin.

[0069] <A-1-3. Others> The foaming styrene resin particle body may contain a foaming aid together with the foaming agent. Examples of the foaming aid include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, coconut oil, etc. The foaming aid may be only one kind or two or more kinds.

[0070] The expandable polystyrene resin particle body may contain a flame retardant and a flame retardant aid together with a foaming agent. Examples of the flame retardant include tetrabromocyclooctane, hexabromocyclododecane, hexabromocyclohexane, tris(dibromopropyl) phosphate, tetrabromobisphenol A, tetrabromobisphenol F, tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tetrabromobisphenol A-diglycidyl ether, 2,2-bis[4’(2’’,3’’-dibromoalkoxy)-3’,5’-dibromophenyl]-propane, and the like. Examples of the flame retardant aid include cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, and the like.

[0071] The expandable polystyrene resin particle body may further contain an additive. The additive here is different from the powder additive and the liquid additive as the external additive referred to in the present invention. Examples of the additive include a radiant heat suppression component, a resin other than the polystyrene resin, a crosslinking agent, a plasticizer, a filler, a lubricant, a coloring agent, an antistatic agent, a spreading agent, a bubble regulator, a weathering agent, an antioxidant, an antifogging agent, a fragrance, and the like. The type, number, combination, content, etc. of the additive can be appropriately set according to the purpose. The additive may be only one type or two or more types.

[0072] ≪A-2. Method for Producing Expandable Polystyrene Resin Particles≫ As one embodiment of the method for producing expandable polystyrene resin particles, it includes a step (I) of producing an expandable polystyrene resin particle body and a step (II) of adding a powder additive and a liquid additive to the expandable polystyrene resin particle body.

[0073] <Step (I) of Producing Expandable Polystyrene Resin Particle Body> The process (I) for manufacturing the expandable polystyrene resin particle body typically includes a step of polymerizing a styrene-based monomer and a step of impregnating a blowing agent during or after the polymerization.

[0074] Typical methods for polymerizing the styrene-based monomer include suspension polymerization. The suspension polymerization method is a method in which a polymerization initiator is dissolved in the styrene-based monomer, and together with water in which a suspending agent is dispersed, the temperature is raised in a reaction tank for polymerization and then cooled to obtain an expandable polystyrene resin particle body.

[0075] The method of adding a blowing agent during and / or after the polymerization is called the one-step method. A method in which particles obtained by polymerizing without adding a blowing agent are sieved to obtain only particles in a required particle size range, and the temperature is raised in water in which the suspending agent of the reaction tank is dispersed, and a blowing agent is added here to impregnate the particles is called the two-step method (post-impregnation method). Also, a method in which small styrene-based resin particles (seed particles) are put into a reaction tank containing water in which a suspending agent is dispersed, the temperature is raised, and then a monomer in which a polymerization initiator is dissolved is continuously supplied to the reaction tank for polymerization and grown to a target particle size is called the seed polymerization method. In the seed polymerization method, a blowing agent is added during and / or after the polymerization. By any of the one-step method, the two-step method (post-impregnation method), and the seed polymerization method, expandable polystyrene resin particles can be manufactured. Also, any of the methods has the advantage that a spherical expandable polystyrene resin particle body can be obtained.

[0076] As the polymerization initiator in the polymerization of styrene monomers, any suitable radical-generating polymerization initiator can be used as long as the effects of the present invention are not impaired. Examples of such polymerization initiators include organic peroxides such as benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxybenzoate, t-butyl peroxy-2-ethylhexyl monocarbonate, dicumyl peroxide, t-butyl peroxy pivalate, t-butyl peroxyisopropyl carbonate, 2,2-t-butyl peroxybutane, t-butyl peroxy-3,3,5-trimethylhexanoate, di-t-butyl peroxyhexahydroterephthalate; azo compounds such as azobisdimethylvaleronitrile; and the like. These polymerization initiators may be used alone or in combination of two or more.

[0077] As the polymerization initiator, in order to adjust the molecular weight and reduce the amount of residual monomers, a polymerization initiator having a decomposition temperature in the range of 50 to 80 °C for obtaining a half-life of 10 hours and a polymerization initiator having a decomposition temperature in the range of 80 to 120 °C for obtaining a half-life of 10 hours may be used in combination. Since the polymerization initiator needs to be uniformly absorbed by the seed particles, it is preferably added as a liquid. When the polymerization initiator is directly added to the aqueous suspension, it becomes difficult to be uniformly absorbed by the seed particles. Therefore, the polymerization initiator is preferably added in a state of being suspended or emulsified in an aqueous medium, or dissolved in a small amount of styrene monomer and added as an aqueous suspension by adding an inorganic suspension stabilizer and / or an anionic surfactant.

[0078] The expandable polystyrene resin particle body may be manufactured by a melt extrusion method. The melt extrusion method is a method of supplying polystyrene resin pellets to a resin supply device, injecting and kneading a foaming agent into the polystyrene resin melted in the resin supply device, extruding the molten resin containing the foaming agent from small holes of a die attached to the tip of the resin supply device, and then cooling to obtain expandable polystyrene resin particles. A method of directly extruding from the small holes of the die into a cooling liquid, cutting the extrudate with a rotary blade immediately after extrusion, and cooling the cut particles in the cooling liquid is called the hot cut method. A method of once extruding in a strand shape into the air from the small holes of the die, guiding the strand into a cooling water tank before the strand foams, cooling the strand in the cooling water tank, and then cutting it into cylindrical particles is called the strand cut method (cold cut method). The expandable polystyrene resin particle body can be manufactured by either the hot cut method or the strand cut method (cold cut method). According to the hot cut method, there is an advantage that an expandable polystyrene resin particle body substantially in a spherical shape can be obtained.

[0079] <Step (II) of adding a powder additive and a liquid additive to the expandable polystyrene resin particle body> In step (II) of adding a powder additive and a liquid additive to the expandable polystyrene resin particle body, typically, the expandable polystyrene resin particle body manufactured in step (I), the powder additive, and the liquid additive are mixed using a mixer or stirrer such as a Lodige mixer, a tumbler, a ribbon blender, a Nauta mixer.

[0080] ≪≪B. Pre-expanded polystyrene resin particles≫≫ The pre-expanded polystyrene resin particles are obtained by pre-expanding the expandable polystyrene resin particles.

[0081] The expandable polystyrene resin particles have an average cell diameter on the surface layer of 0.01 mm to 0.15 mm, preferably 0.01 mm to 0.14 mm, more preferably 0.01 mm to 0.13 mm, particularly preferably 0.01 mm to 0.12 mm, and most preferably 0.01 mm to 0.11 mm. If the average cell diameter on the surface layer of the expandable polystyrene resin particles is within the above range, blocking during foaming and molding can be further prevented, and furthermore, while suppressing the chargeability during foaming and molding, better fusion properties and surface properties can be exhibited, and an expandable polystyrene resin foam molded article with less static electricity can be molded, and expandable polystyrene resin particles can be provided.

[0082] That is, the expandable polystyrene resin particles according to the embodiment of the present invention are obtained by pre-expanding the expandable styrenic resin particles described in the above item A. Pre-expansion includes expanding the expandable styrenic resin particles to a desired bulk expansion ratio (bulk density) using steam or the like. The bulk expansion ratio of the expandable polystyrene resin particles is preferably 2 to 150 times, more preferably 5 to 78 times, and even more preferably 10 to 75 times. The bulk density is the reciprocal of the bulk expansion ratio. The bulk expansion ratio and the bulk density can be determined, for example, as follows. When the bulk expansion ratio of the expandable polystyrene resin particles is within the above range, blocking during foaming and molding can be further prevented, and furthermore, while suppressing the chargeability during foaming and molding, better fusion properties and surface properties can be exhibited, and an expandable polystyrene resin foam molded article with less static electricity can be molded, and expandable polystyrene resin particles can be provided.

[0083] Collect W (g) of the expandable styrenic resin particles as a measurement sample. Let this measurement sample fall naturally into a graduated cylinder, and measure the volume V (cm 3 ) of the measurement sample dropped into the graduated cylinder using an apparent density measuring device conforming to JIS K 6911. From the weight and volume of the measurement data, the bulk expansion multiple and the bulk density can be determined based on the following formula. Bulk expansion multiple (times = cm 3 / g) = volume of the measurement sample (V) / weight of the measurement sample (W) Bulk density (g / cm3 ) = Weight (W) of the measurement sample / Volume (V) of the measurement sample

[0084] In one representative embodiment, the pre-expanded polystyrene resin particles can be used for molding a polystyrene resin foam molded article. In another embodiment, the pre-expanded polystyrene resin particles can be used as a buffer, a heat insulator, etc. as they are. When using the pre-expanded polystyrene resin particles as they are, the pre-expanded polystyrene resin particles can preferably be used as a filled body in which a large number of pre-expanded polystyrene resin particles are filled in a bag body.

[0085] ≪≪C. Polystyrene Resin Foam Molded Article≫≫ The polystyrene resin foam molded article according to one embodiment of the present invention is a polystyrene resin foam molded article formed from expandable polystyrene resin particles. The polystyrene resin foam molded article according to another embodiment of the present invention is a polystyrene resin foam molded article formed from pre-expanded polystyrene resin particles obtained by pre-expanding expandable polystyrene resin particles.

[0086] The polystyrene resin foam molded article typically includes expanded polystyrene resin particles (hereinafter, may be simply referred to as "expanded particles") obtained by further expanding the pre-expanded polystyrene resin particles.

[0087] The polystyrene resin foam molded article typically consists of a plurality of expanded particles fused to each other.

[0088] Styrene resin foam molded articles can typically be produced by charging pre-expanded styrene 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 and foaming the pre-expanded styrene resin particles with a heat medium (e.g., pressurized steam, etc.) to obtain foamed particles; (iii) filling the voids between the foamed particles and fusing the foamed particles to each other by the heating and foaming to integrate them. The density of the styrene resin foam molded article can be appropriately set according to the purpose. The density of the styrene resin foam molded article can be adjusted, for example, by preliminarily adjusting the bulk foaming ratio of the pre-expanded styrene resin particles filled into the mold or by adjusting the filling amount of the pre-expanded styrene resin particles into the mold.

[0089] The temperature of the 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 steam pressure of the heating and foaming (the blowing gauge pressure of the heat medium) is preferably 0.04 MPa to 0.1 MPa, more preferably 0.06 MPa to 0.08 MPa. If the heating and foaming are under such conditions, the foamed particles can be well fused to each other.

[0090] 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, an excessively long aging time may be required. If the aging temperature is too high, the blowing agent in the pre-expanded styrene resin particles may dissipate and the moldability may decrease.

[0091] The bulk foaming ratio of the foamed particles in the styrene resin foam molded article is preferably 2 to 150 times, more preferably 5 to 78 times, and even more preferably 10 to 75 times.

Examples

[0092] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement methods and evaluation methods for each characteristic are as follows.

[0093] <Measurement of average particle diameter of powder additive> The average particle diameter of the powder additive was measured as follows. 0.001 g of the powder additive and 1 drop of a 0.6% sodium linear dodecylbenzenesulfonate solution were dropped onto a slide glass for preliminary dispersion, and then covered with a cover glass. Thereafter, using a digital microscope VHX-6000 manufactured by Keyence Corporation, the particle diameters of 20 randomly selected powder additives were measured at a magnification of 1000 times, and the average of the 20 particle diameters was taken as the average particle diameter of the powder additive. Also, the average particle diameter to be measured was the average particle diameter of all the powder additives coating the expanded polystyrene resin particles, measured for each type.

[0094] <Measurement and evaluation of pipe adhesion amount> Using a suction transport device ML-5500CB manufactured by ML Engineering Co., Ltd., the pipe adhesion amount of the expandable polystyrene resin particles was measured. Figure 1 is a schematic diagram showing a suction and transportation device ML-5500CB manufactured by ML Engineering Co., Ltd. In Figure 1, 1 is a hopper, and 2 is a suction part provided above it. The hopper 1 is provided with a discharge pipe 11, and the suction part 2 is provided with an introduction pipe 21 having an inner diameter of 46 mm. 5 is a blower that sucks through the suction pipe 3 from the suction part 2, passes through the bag filter 4, and sucks. 6 is a tank provided directly below the discharge pipe 11. The tank 6 is provided with a suction pipe 61 having an inner diameter of 46 mm. 7 is a metal pipe with an inner diameter of 46 mm and a length of 1.4 m arranged perpendicular to the ground. Resin hoses 8 with an inner diameter of 50 mm and a length of 1 m are attached to both ends of the metal pipe 7, and the other ends of the resin hoses 8 are attached to the introduction pipe 21 and the suction pipe 61, respectively. In this state, 10 kg of expandable polystyrene resin particles A were put into the tank 6 and sucked for 30 seconds at a flow rate of 200 g / second. During the 15-second suction stop, the expandable polystyrene resin particles A filled in the hopper 1 were dropped 8 m and received by the tank 6. After repeating this suction cycle for 1 hour, the resin hose 8 was removed and weighed, and the amount of resin hose adhesion was determined from the weight difference before and after the evaluation. The evaluation of the pipe adhesion amount was as follows. Pipe adhesion amount less than 0.50 g: ◎ Pipe adhesion amount 0.50 g or more and less than 0.75 g: 〇 Pipe adhesion amount 0.75 g or more: ×

[0095] <Measurement and evaluation of the blocking generation rate during pre-expansion> During the production of pre-expanded polystyrene resin particles, so-called blocking particles in which the resin particles aggregated were separated using a sieve with a mesh size of 10 mm, weighed, and divided by the weight of the total amount input to obtain the blocking generation rate. The evaluation of the blocking generation rate was as follows. Blocking generation rate less than 0.03%: ◎ Blocking generation rate 0.03% or more and less than 0.05%: ○ Blocking generation rate 0.05% or more: ×

[0096] <Measurement and evaluation of the fusion rate of the polystyrene resin foam molded body> On the surface of a styrene resin foam molded body in a flat plate shape with a width of 300 mm, a length of 400 mm, and a thickness of 30 mm, after making a cut line with a depth of about 2 mm along a straight line connecting the centers of a pair of long sides with a cutter knife, the styrene resin foam molded body was manually bisected along this cut line. Regarding the foam particles on the fracture surface, for an arbitrary range of 100 to 150 particles, the number of particles (a) broken inside the particles and the number of particles (b) broken at the interface between the particles were counted, and the value obtained by substituting into the formula [(a) / ((a) + (b))]×100 was taken as the fusion rate (%). The evaluation of the fusion rate was as follows. Fusion rate of 70% or more: 〇 Fusion rate less than 70%: ×

[0097] <List of powder additives> The following powder additives were used. A1: Zinc stearate sieved to have an average particle size of 9 μm. A2: Zinc stearate sieved to have an average particle size of 51 μm. B1: 12-Hydroxystearic acid triglyceride sieved to have an average particle size of 22 μm. B2: 12-Hydroxystearic acid triglyceride sieved to have an average particle size of 78 μm. C1: Fatty acid triglyceride sieved to have an average particle size of 18 μm. C2: Fatty acid triglyceride sieved to have an average particle size of 60 μm. D1: Stearic acid monoglyceride sieved to have an average particle size of 17 μm. D2: Stearic acid monoglyceride sieved to have an average particle size of 96 μm. E1: Calcium carbonate sieved to have an average particle size of 8 μm. E2: Calcium carbonate sieved to have an average particle size of 60 μm. F1: Magnesium stearate sieved to have an average particle size of 10 μm. F2: Magnesium stearate sieved to have an average particle size of 55 μm. G1: N-hydroxyethyl-N-(2-hydroxyalkyl)amine sieved to have an average particle diameter of 27 μm. G2: N-hydroxyethyl-N-(2-hydroxyalkyl)amine sieved to have an average particle diameter of 90 μm.

[0098] <List of Liquid Additives> H: Polyethylene glycol I: Dimethylpolysiloxane J: Polyethylene glycol monooleate

[0099] [Production Example 1] (Production of Styrene-Based Polymer Seeds) Into a polymerization vessel with a stirrer having an internal volume of 100 liters, 40,000 g of water, 141 g of tricalcium phosphate as a suspension stabilizer, and 2.8 g of sodium dodecylbenzenesulfonate as an anionic surfactant were supplied. While stirring, 40,000 g of styrene, 101 g of benzoyl peroxide as a polymerization initiator, and 20 g of t-butylperoxy-2-ethylhexyl monocarbonate were added. The temperature was raised to 90 °C for polymerization. Then, it was maintained at this temperature for 6 hours, and further, after raising the temperature to 125 °C, it was cooled 2 hours later to obtain styrene-based polymer particles. The obtained styrene-based polymer particles were sieved to obtain styrene-based polymer seed particles having a particle diameter of 0.5 mm to 0.71 mm (average particle diameter 0.63 mm). The rotation speed of stirring was adjusted so as to obtain the above particle diameter. (Production of Expandable Styrene-Based Resin Particle Bodies) Into a polymerization vessel with a stirrer having an internal volume of 100 liters, 10,800 g of the styrene-based polymer seed particles obtained above, 42,000 g of distilled water, 169 g of magnesium pyrophosphate, and 4 g of sodium dodecylbenzenesulfonate were supplied. While stirring, it was heated to 72 °C to prepare a dispersion. Subsequently, a solution in which 155 g of benzoyl peroxide and 24 g of t-butylperoxy-2-ethylhexyl monocarbonate were dissolved in a monomer mixture of 3,950 g of styrene and 690 g of butyl acrylate was supplied to the above dispersion while stirring. After finishing the supply of the above solution into the dispersion, it was maintained at 72 °C for 60 minutes. Next, while raising the temperature to 87°C over 1 hour, 12,240 g of styrene was supplied at a constant rate. Then, while maintaining the temperature at 87°C for 1 hour and 30 minutes, a monomer mixture in which 11 g of divinylbenzene was dissolved in 18,310 g of styrene was supplied at a constant rate, and the mixture was further maintained for 30 minutes. Next, the temperature was raised to 125°C and maintained for 30 minutes to react unreacted monomers. Then, the temperature was cooled to 100°C, and 460 g of cyclohexane, 391 g of diisobutyl adipate, and 2,852 g of mixed butane were press-fitted into the polymerization vessel and held for 2 hours. After that, the inside of the polymerization vessel was cooled to 25°C to obtain a foamed styrene-based resin particle body.

[0100] [Example 1] (Production of foamed styrene-based resin particles) 10 kg of the foamed styrene-based resin particle body obtained in Production Example 1 was put into a Lodige mixer M20 type (internal volume: 20 liters) manufactured by Matsuzaka Trading Co., Ltd. Next, as shown in Table 1, with respect to 100% by weight of the foamed styrene-based resin particle body, 0.130% by weight of powder additive A1, 0.050% by weight of powder additive B1, 0.030% by weight of powder additive C1, and 0.050% by weight of powder additive D1 were sequentially added and stirred at 230 rpm for 5 minutes. Then, with respect to 100% by weight of the foamed styrene-based resin particle body, 0.070% by weight of liquid additive H and 0.020% by weight of liquid additive I were added and stirred at 230 rpm for 5 minutes to obtain foamed styrene-based resin particles (1) whose surface of the foamed styrene-based resin particle body was coated with the powder additive and the liquid additive. (Production of pre-expanded styrene-based resin particles) The obtained foamed styrene-based resin particles (1) were supplied to a cylindrical batch-type pre-expander and heated with steam at an injection pressure of 0.07 MPa to obtain pre-expanded styrene-based resin particles (1). The obtained pre-expanded styrene-based resin particles (1) had a bulk density of 0.017 g / cm 3 (Bulk foaming multiple: 60 times). (Production of styrene-based resin foamed molded article) The obtained pre-expanded polystyrene resin particles (1) were left standing for 24 hours in a room temperature atmosphere, and then filled into a mold having a rectangular cavity with a length of 400 mm × width of 300 mm × height of 30 mm, and molding was performed under the conditions of a molding steam pressure of 0.06 MPa (gauge pressure), heating for 26 seconds, water cooling for 5 seconds, and a set take-out surface pressure of 0.03 MPa. The obtained polystyrene resin foam molded body (1) had a density of 0.017 g / cm 3 (expansion ratio: 60 times). (Various measurements and evaluations) For the expandable polystyrene resin particles (1), pre-expanded polystyrene resin particles (1), and polystyrene resin foam molded body (1) thus obtained, various measurements and evaluations were performed. The results are shown in Table 2.

[0101] [Examples 2 to 8] Except that the types and addition amounts of the powder additive and liquid additive were changed as shown in Table 1, the same procedures as in Example 1 were carried out to obtain expandable polystyrene resin particles (2) to (8), pre-expanded polystyrene resin particles (2) to (8), and polystyrene resin foam molded bodies (2) to (8). The results are shown in Table 2.

[0102] [Comparative Examples 1 to 4] Except that the types and addition amounts of the powder additive and liquid additive were changed as shown in Table 1, the same procedures as in Example 1 were carried out to obtain expandable polystyrene resin particles (C1) to (C4), pre-expanded polystyrene resin particles (C1) to (C4), and polystyrene resin foam molded bodies (C1) to (C4). The results are shown in Table 2.

[0103]

Table 1

[0104]

Table 2

Industrial Applicability

[0105] The expandable polystyrene resin particles, pre-expanded polystyrene resin particles, and polystyrene resin foam molded article according to the embodiments of the present invention are suitably used as heat insulating materials for use in housing, automobiles, etc., heat insulating materials for use in building materials, etc., packaging materials for transportation such as fish boxes and food containers, cushioning materials, and the like. More specifically, the expandable polystyrene resin particles, pre-expanded polystyrene resin particles, and polystyrene resin foam molded article are suitably used as cushioning materials, heat insulating materials for walls, heat insulating materials for floors, heat insulating materials for roofs, heat insulating materials for automobiles, heat insulating materials for hot water tanks, heat insulating materials for pipes, heat insulating materials for solar systems, heat insulating materials for water heaters, containers for foods and industrial products, etc., packaging materials for fish and agricultural products, etc., earth retaining materials, core materials for tatami mats, and the like.

Explanation of symbols

[0106] 1 Hopper 11 Discharge pipe 2 Suction part 3 Suction pipe 4 Bag filter 5 Blower 6 Tank 7 Metal pipe 8 Resin hose

Claims

1. Expandable polystyrene resin particles in which the surface of the expandable polystyrene resin particle body is coated with a powder additive and a liquid additive, wherein the liquid additive is at least one selected from polyethers, polyhydric alcohols, liquid paraffin, liquid fatty acid esters, and liquid polysiloxanes, the average particle diameter of the powder additive is in the range of 1 μm to 50 μm, Expandable polystyrene resin particles.

2. The expandable polystyrene resin particles according to claim 1, wherein the weight of the powder additive is 1.0 times to 30.0 times the weight of the liquid additive.

3. The expandable polystyrene resin particles according to claim 1 or 2, wherein the ratio of the powder additive to 100 parts by weight of the expandable polystyrene resin particle body is 0.050 parts by weight to 1.500 parts by weight.

4. The expandable polystyrene resin particles according to any one of claims 1 to 3, wherein the ratio of the liquid additive to 100 parts by weight of the expandable polystyrene resin particle body is 0.005 parts by weight to 0.250 parts by weight.

5. The expandable polystyrene resin particles according to any one of claims 1 to 4, wherein the powder additive is at least one selected from fatty acid metal salts, solid fatty acid esters, hydrogenated oils, carbonates, fatty acid amides, and amine compounds.

6. Pre-expanded polystyrene resin particles obtained by pre-expanding the expandable polystyrene resin particles according to any one of claims 1 to 5, wherein the bulk expansion ratio of the pre-expansion is 2 to 150 times, Pre-expanded polystyrene resin particles.

7. A styrenic resin foam molded article formed from the expandable polystyrene resin particles according to any one of claims 1 to 5.

8. A styrenic resin foam molded article formed from the pre-expanded polystyrene resin particles according to claim 6.

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