JP2018119109A - Foamable polystyrene resin particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamable polystyrene resin particle which prevents blocking, and is suitable for improvement of productivity by shortening a cooling time at the time of molding while obtaining a molded body having good surface property.SOLUTION: A polystyrene resin foamed body contains 0.030-0.300 pts.wt. of methylphenyl polysiloxane, 0.001-0.200 pts.wt. of dimethyl polysiloxane and a foamable polystyrene resin particle obtained by coating a resin surface with fatty acid metal salt with respect to 100 pts.wt. of a foamable polystyrene resin particle, and is obtained by in-mold molding the foamed particles. In the foamable polystyrene resin particle, viscosity at 25°C of the methylphenyl polysiloxane is 100-6,000 mm/s.SELECTED DRAWING: None

Description

  The present invention relates to expandable polystyrene resin particles.

  Expandable polystyrene resin particles are relatively useful materials, and can be foam-molded with steam or the like without using a special method, so that a high buffering / insulating effect is obtained.

  Expandable polystyrene resin particles are obtained by, for example, adding a foaming agent to polystyrene resin particles (that is, easily volatile aliphatic hydrocarbons such as butane, pentane, etc., which only slightly swell the particles) in an aqueous suspension. Manufactured by the impregnation method. The expandable styrene-based resin particles thus manufactured are used as a raw material for manufacturing a foamed styrene-based resin molded body.

  As a method for industrially and economically producing an expanded polystyrene-based resin molded article, expandable styrene-based resin particles are pre-expanded particles with water vapor or the like, and the pre-expanded particles are formed on a wall having a desired shape with a large number of small holes. Is filled in a closed mold, and a heating medium such as water vapor is ejected from a small hole of the mold, heated to a temperature higher than the softening point of the pre-foamed particles, and fused together, then cooled. There is a method for producing a foamed styrene resin molded article having a desired shape by taking it out from the mold through the steps.

  Therefore, in order to make expandable polystyrene-based resin particles into a molded body, a large amount of steam is required. However, due to the recent increase in interest in environmental problems, demand for energy saving has increased. There is a demand for a resin that can be foamed with a small amount of steam used by lowering the temperature during molding in a mold. At the same time, in order to increase productivity, it is required to shorten the cooling time, which accounts for about 50% of the molding time.

  So far, plasticizers and copolymerization techniques have been used for molding at low temperatures, but all use volatile solvents (such as cyclohexane). At the same time as reducing the amount of steam used, the cooling time could not be shortened.

  Conventionally, as a method of shortening the cooling time, the surface of the expandable polystyrene resin particles is coated with chemicals that generate cracks, and the foaming power after molding is increased by promoting the dissipation of the gas contained in the resin particles. A method of lowering was taken. However, in the method of promoting the dissipation of gas components inside the resin by adding chemicals that generate cracks on the particle surface, the amount of chemicals that generate cracks is increased in order to promote the dissipation of the blowing agent more efficiently. By increasing the number, there is a problem that pinholes are easily generated on the surface of the molded body and fusion between particles is also reduced.

  In Patent Document 1, by covering 0.0025 parts by weight of dimethylpolysiloxane and 0.0025 parts by weight of methylphenylpolysiloxane on the surface of the expandable polystyrene resin particles, the mold filling rate at the time of molding is improved, Furthermore, expandable polystyrene resin particles for obtaining a molded article having a good surface property and a method for producing the same have been proposed.

  However, in this method, since the number of coating parts of dimethylpolysiloxane and methylphenylpolysiloxane is small, the cooling time has not been shortened.

  In Patent Document 2, a molded article excellent in mechanical strength and heat insulating properties such as bending strength and compressive strength is obtained by melt-kneading dimethylpolysiloxane or methylphenylpolysiloxane with an extruder on the surface of expandable polystyrene resin particles. Expandable polystyrene resin particles and a method for producing the same have been proposed.

  However, in this method, the extruder is used to knead the resin uniformly, and dimethylpolysiloxane or methylphenylpolysiloxane single substance is kneaded. It was not reached.

  In Patent Documents 3, 4, and 5, resin particles that have an effect of shortening the cooling time during molding by coating the surface of the expandable polystyrene resin particles with dimethylpolysiloxane or methylphenylpolysiloxane and zinc stearate, And its manufacturing method has been proposed.

  However, this method has not achieved both deterioration of surface properties and shortening of the cooling time.

Japanese Patent Laid-Open No. 02-003435 JP 2012-214750 A Japanese Patent Laid-Open No. 60-203647 JP 2007-246705 A JP-A-49-003966

  In view of the above situation, the object of the present invention is to improve productivity by preventing blocking, obtaining a molded article having better surface properties, and shortening the cooling time during molding. It is providing the expandable polystyrene-type resin particle suitable for.

  The present inventors have aimed at improving the drawbacks of the prior art described above, and expandable polystyrene that prevents blocking and reduces the cooling time during molding while obtaining a molded article having good surface properties. As a result of intensive studies to obtain resin particles, the present invention has been completed.

  That is, in the first aspect of the present invention, 0.030 to 0.300 parts by weight of methylphenylpolysiloxane, 0.001 to 0.200 parts by weight of dimethylpolysiloxane with respect to 100 parts by weight of expandable polystyrene resin particles, An expandable polystyrene resin particle, wherein the resin surface is coated with a fatty acid metal salt.

The second invention is the expandable polystyrene resin particles according to the first invention, wherein the methylphenylpolysiloxane has a viscosity at 25 ° C. of 100 to 6000 m ² / s.

The third invention is the expandable polystyrene resin particles according to the first or second invention, wherein the viscosity of the dimethylpolysiloxane at 25 ° C. is 100 to 15000 m ² / s.

  4th invention is 0.040-0.150 weight part of said methylphenyl polysiloxane, The expandable polystyrene-type resin particle in any one of 1st-3rd invention characterized by the above-mentioned.

  5th invention is 0.005-0.080 weight part of said dimethylpolysiloxane, The expandable polystyrene-type resin particle in any one of 1st-4th invention characterized by the above-mentioned.

  A sixth invention is characterized in that the fatty acid metal salt is zinc stearate and is 0.005 to 0.500 parts by weight with respect to 100 parts by weight of the expandable polystyrene resin particles. The expandable polystyrene resin particle according to any one of the inventions.

  A seventh aspect of the present invention is the expandable polystyrene resin according to any one of the first to sixth aspects, wherein the amount of the foaming agent contained is 3.0% by weight or more and less than 9.0% by weight. particle.

  An eighth invention is a polystyrene resin pre-expanded particle obtained by foaming the expandable polystyrene resin particle according to any one of the first to seventh inventions.

  According to a ninth invention, the polystyrene resin pre-expanded particles according to the eighth invention are characterized in that the amount of the foaming agent contained is 2.0 wt% or more and 7.0 wt% or less.

  A tenth invention is a polystyrene resin foam, wherein the polystyrene resin pre-expanded particles according to the eighth or ninth invention are molded in-mold.

  According to the present invention, expandable polystyrene resin particles suitable for shortening the cooling time during molding can be obtained while preventing blocking and obtaining a molded article having good surface properties. .

  In the present invention, when the expandable polystyrene resin particles are 100 parts by weight, 0.030 to 0.300 part by weight of methylphenylpolysiloxane, 0.001 to 0.200 part by weight of dimethylpolysiloxane, and fatty acid A metal salt is coated on the resin surface. Furthermore, it is preferable that the methylphenylpolysiloxane is 0.040 to 0.150 parts by weight because a good molded body can be obtained while efficiently reducing the cooling time. When the coating amount of methylphenylpolysiloxane is less than 0.030 parts by weight, blocking at the time of preliminary foaming increases, and the cooling time reduction rate is not efficiently exhibited. Moreover, when it exceeds 0.300 weight part, the surface property of a molded object deteriorates. Furthermore, since a favorable molded object can be obtained, it is preferable that dimethylpolysiloxane is 0.005-0.080 weight part. When the coating amount of dimethylpolysiloxane is less than 0.001 part by weight, good surface properties cannot be obtained. Moreover, when it exceeds 0.200 weight part, the increase in blocking at the time of preliminary foaming and fusion | melting will deteriorate. Furthermore, since a favorable molded object is obtained, it is preferable that a fatty-acid metal salt is a zinc stearate, and is 0.005-0.500 weight part with respect to 100 weight part of expandable polystyrene resin particles. It is preferable. When the amount of zinc stearate added is less than 0.005 parts by weight, the anti-blocking effect is not sufficiently exhibited. Moreover, when it exceeds 0.500 weight part, melt | fusion of a molded object will deteriorate.

In the present invention, it is preferable that the viscosity of methylphenylpolysiloxane at 25 ° C. is 100 to 6000 mm ² / s. When the viscosity of methylphenylpolysiloxane at 25 ° C. is less than 100 mm ² / s, the characteristics as siloxane are not exhibited. Moreover, when it exceeds 6000 mm < ² > / s, it does not fully penetrate into particles due to the large molecular weight.

In the present invention, the viscosity of dimethylpolysiloxane at 25 ° C. is preferably 100 to 15000 mm ² / s. When the viscosity at 25 ° C. of dimethylpolysiloxane is less than 100 mm ² / s, the characteristics as siloxane are not exhibited. Moreover, when exceeding 15000 mm < ² > / s, it does not fully osmose | permeate particle | grains due to the large molecular weight.

  The methylphenyl polysiloxane of the present invention is preferably a polysiloxane having a structure represented by the general formula (1).

  M and n of the repeating unit of methylphenylpolysiloxane represented by the above general formula are arbitrary natural numbers (1, 2, 3, etc.). The methylphenyl polysiloxane represented by the general formula (1) used in the present invention may be one in which dimethyl portions and diphenyl portions are bonded at random or may be regularly arranged.

  The expandable polystyrene resin particles of the present invention may further contain, as an external additive, an anti-blocking agent, a fusion accelerator or the like as long as the effects of the present invention are not impaired.

  Specific examples of the external additive include, for example, fatty acid triglycerides such as lauric acid triglyceride, stearic acid triglyceride, linoleic acid triglyceride, lauric acid diglyceride, stearic acid diglyceride, linoleic acid diglyceride, and the like, lauric acid monoglyceride, stearic acid monoglyceride, and the like. , Fatty acid monoglycerides such as linoleic acid monoglyceride, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, polyoxyethylene oleate Nonionic surfactants such as These external additives may be used alone or in combination of two or more. These external additives and attachments may be added to the aqueous system when impregnated with the foaming agent, or may be added and coated after dehydration or after drying, regardless of the coating method. A preferable coating method is a method of attaching by drying and coating by mixing and stirring.

  In the present invention, the time required for coating the expandable polystyrene resin particles with methylphenylpolysiloxane, dimethylpolysiloxane, and fatty acid metal salt, and the stirring time are any time as long as the surface can be uniformly coated without uneven coating. Minutes are fine. Further, the charging time is preferably 1 to 120 seconds, and more preferably 10 to 60 seconds for efficient coating. As stirring time, it is good to stir for 1 to 150 seconds, and in order to coat | cover without coating unevenness, it is more preferable to stir for 20 to 120 seconds.

  Examples of the mixing equipment used in the present invention include a super mixer, a nauter mixer, a universal mixer, a Henschel mixer, a Ladige mixer, a ribbon blender, a tumbler type blender, a Henschel type mixer and the like that can be uniformly coated. Any mixing machine of the above type can be coated uniformly by adjusting the mixing time in consideration of the mixing ability and the coating amount and viscosity of methylphenylpolysiloxane, dimethylpolysiloxane and fatty acid metal salt. Expandable polystyrene resin particles can be obtained.

  As the styrene-based foaming resin constituting the expandable polystyrene-based resin particles of the present invention, a polymer containing 60 parts by weight or more of styrene as a monomer component is preferable, specifically, a styrene homopolymer, a styrene-ethylene system. Examples include copolymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, and styrene-acrylate copolymers.

  Among these, the base resin constituting the expandable polystyrene resin particles may be obtained by copolymerizing a styrene monomer and an acrylate monomer.

  Examples of the styrene raw material used for the expandable polystyrene resin particles of the present invention include styrene derivatives such as styrene, α-methyl styrene, paramethyl styrene, t-butyl styrene, and chlorostyrene. These styrene monomers may be used alone or in combination of two or more.

  Examples of the acrylate ester monomer constituting the expandable polystyrene resin particles of the present invention include alkyl acrylate esters such as methyl acrylate and butyl acrylate. These acrylate monomers may be used alone or in admixture of two or more.

  In addition, regarding the monomer composition in the base resin, when the seed suspension polymerization method is performed as the polymerization method, the monomer composition in the resin particles serving as a seed is also reflected in the monomer composition.

  The monomer component contained in the expandable polystyrene resin particles of the present invention is less than 0.3% by weight. The contained monomer component tends to volatilize from the foamed molded product obtained by foaming the expandable polystyrene resin particles. Particularly, when the contained monomer component is 0.3% by weight or more, the medical field Or it is unpreferable for the field of the packaging material which contacts a foodstuff directly, or for the components of a motor vehicle or a building.

  The amount of the monomer component contained can be controlled by a combination of the amount of initiator used when polymerizing the polystyrene resin particles and the polymerization temperature. For example, the content of the monomer component can be lowered by increasing the amount of the initiator used and increasing the polymerization temperature.

  The expandable polystyrene resin particles of the present invention may contain a solvent having a boiling point of 50 ° C. or higher and a plasticizer as long as the effects of the present invention are not impaired.

  Specific examples of the solvent and plasticizer having a boiling point of 50 ° C. or higher include, for example, C6 or higher aliphatic hydrocarbons such as hexane and heptane, C6 or higher alicyclic hydrocarbons such as cyclohexane and cyclooctane, and diisobutyl. Examples include adipate, dioctyl adipate, dibutyl sebacate, glycerin tristearate, glycerin tricaprylate, coconut oil, palm oil, and rapeseed oil.

  The content of the foaming agent in the expandable polystyrene resin particles in the present invention is preferably 3.0% by weight or more and less than 9.0% by weight with respect to 100% by weight of the expandable polystyrene resin particles. It is more preferably 3.5% by weight or more and less than 8.5% by weight, and particularly preferably 4.0% by weight or more and less than 7.0% by weight.

  When the content of the foaming agent is less than 3.0% by weight, the pre-foaming time becomes long and the fusion rate at the time of molding tends to decrease, resulting in an increase in production cost and economical disadvantage. When the content of the foaming agent is 9.0% by weight or more, the molded body shrinks and the appearance of the molded body tends to be impaired.

  Examples of the blowing agent used in the present invention include aliphatic hydrocarbons such as propane, butane and pentane, alicyclic hydrocarbons such as cyclobutane and cyclopentane, methyl chloride, dichlorodifluoromethane and dichlorotetrafluoroethane. And halogenated hydrocarbons. These foaming agents may be used alone or in combination of two or more. Of these foaming agents, butane is preferred because of its good foaming power.

  The amount of the foaming agent used in the present invention is preferably 3.0 parts by weight or more and less than 9.0 parts by weight, more preferably 6.0 parts by weight or more and 8.0 parts by weight or less with respect to 100 parts by weight of the polystyrene resin particles. preferable.

  The content of the foaming agent in the polystyrene-based prefoamed resin particles in the present invention is preferably 2.0% by weight or more and 7.0% by weight or less, and 3.0% by weight with respect to 100% by weight of the polystyrene-based prefoamed resin particles. The content is more preferably 4.3% by weight or less.

  When the content of the foaming agent is less than 2.0% by weight, the pre-foaming time becomes long and the fusion rate at the time of molding tends to decrease, resulting in high production costs and economical disadvantages. When the content of the foaming agent exceeds 7.0% by weight, the molded product shrinks and the appearance of the molded product tends to be impaired.

  In the expandable polystyrene resin particles of the present invention, the average chord length of the cells on the cut surface of the expanded molded article obtained from the expandable polystyrene resin particles is 50 μm or more and less than 200 μm. Preferably they are 80 micrometers or more and less than 120 micrometers.

  If the average chord length is less than 50 μm, the film thickness of the cell constituting the foam tends to be thin, and the internal fusion and surface properties tend to decrease. When the average chord length is 200 μm or more, the breaking point displacement of the breaking strength (for example, the bending strength of JIS A9511, the box-shaped molded body bottom splitting strength, etc.) tends to be short, and the brittle molded body tends to be formed.

  The average chord length of the bubbles on the cut surface of the foam can be controlled by the amount of the nucleating agent. For example, when the nucleating agent is increased, the average string length is decreased, and when the nucleating agent is decreased, the average string length is increased.

  The expandable polystyrene resin particles of the present invention may contain flame retardants, flame retardant aids and the like as additives within a range that does not impair the effects of the present invention.

  As the flame retardant and flame retardant auxiliary contained in the present invention, known and conventional ones can be used. Specific examples of the flame retardant include, for example, halogenated aliphatic hydrocarbon compounds such as hexabromocyclododecane, tetrabromobutane, hexabromocyclohexane, tetrabromobisphenol A, tetrabromobisphenol F, 2,4,6-tri Brominated phenols such as bromophenol, tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A- Brominated phenol derivatives such as diglycidyl ether, 2,2-bis [4 ′ (2 ″, 3 ″ -dibromoalkoxy) -3 ′, 5′-dibromophenyl] -propane, brominated styrene / butadiene block copolymers , Brominated random styrene / butadiene Brominated butadiene / vinyl aromatic hydrocarbon copolymers such as coalesced, brominated styrene / butadiene graphs and copolymers (for example, disclosed in Chemera's EMERALD 3000 or JP-T 2009-516019) Is mentioned. These flame retardants may be used alone or in combination of two or more.

  Specific examples of the flame retardant aid include, for example, initiators such as cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, and 2,3-dimethyl-2,3-diphenylbutane. Good.

  The expandable polystyrene resin particles of the present invention are pre-foamed and then heated and foamed to obtain a foamed molded product.

  As the pre-foaming method, for example, an ordinary method such as foaming by heating with steam or the like using a cylindrical pre-foaming apparatus can be employed.

  As a method for foam-molding the pre-foamed particles, for example, a conventional method such as a so-called in-mold foam molding method, in which pre-foamed particles are filled in a mold and a foam molded body is obtained by blowing and heating steam or the like. Can be adopted.

  Examples and Comparative Examples are given below, but the present invention is not limited by these.

  The measurement evaluation method was performed as follows.

<Measurement of foaming agent content>
The foaming agent content and the monomer component in the obtained expandable polystyrene resin particles were prepared by dissolving 1.0 g of expandable polystyrene resin particles in 20 mL of dichloromethane and adding 0.005 g of an internal standard solution (cyclopentanol). After adding, it measured on condition of the following using gas chromatography (GC).
GC: Shimadzu Corporation GC-14B
Column: PEG-20M 25%
Chromosorb W 60/80 (3.0 m × 3.0 mm ID)
Column temperature: 110 ° C
Detector (FID) temperature: 170 ° C.

<Pre-foaming>
The expandable polystyrene resin particles were put into a pre-foamed gas equipped with a stirrer, and foamed by heating with water vapor to obtain expandable polystyrene resin particles having an apparent magnification of 5 to 80 times. For blocking, the crushing machine is stopped when pre-expanded particles are discharged, and after unpreliminary pre-expanded particles are sent, the proportion of the pre-expanded particles recovered and weighed and collected with respect to the input resin is expressed as% by weight. And evaluated.
A: The blocking ratio is 0.05% or less.
○: Blocking ratio is more than 0.05% and 0.10% or less.
Δ: Blocking ratio is over 0.10% and 0.20% or less.
X: Ratio of blocking is more than 0.20%. <Formability evaluation>
Using a molding machine [manufactured by Daisen, KR-57], a box-shaped mold having a bottom thickness of 30 mm, a side thickness of 25 mm, a length of 550 mm, a width of 350 mm, and a height of 120 mm is filled. In-mold molding was performed under molding conditions varied within a range of 3 to 0.8 kgf / cm ² to obtain a box-shaped foam molded product.

The obtained thermoplastic resin foam was dried at room temperature for 24 hours and then subjected to the following evaluation. Table 1 shows the results of evaluating the cooling time, fusing property and surface property at a blowing vapor pressure of 0.45 kgf / cm ² .

(1) Evaluation of fusing property The obtained thermoplastic resin foam was broken, the fracture surface was observed, and the ratio of the broken particles rather than the particle interface was determined. Sex was judged.
A: The ratio of particle breakage is 90% or more.
○: The ratio of particle breakage is 80% or more and less than 90%.
(Triangle | delta): The ratio of particle | grain fracture | rupture is 70% or more and less than 80%.
X: The ratio of particle breakage is less than 70%.

(2) Surface property evaluation The surface state of the obtained thermoplastic resin foam was visually observed, and the surface property was evaluated according to the following criteria.
A: There is no melting of the surface, no intergranularity, and it is very beautiful.
○: Melting of the surface, little intergranularity, and beautiful.
Δ: Surface melted, intergranular, appearance somewhat poor.
X: Surface melting, intergranularity, and poor appearance.

(Example 1) <Addition of external additive to expandable polystyrene resin particles>
As the base resin on which methylphenylpolysiloxane and dimethylpolysiloxane are applied, expandable polystyrene resin particles (product name Kanepal SG: Kaneka Corporation) were used.

  60 parts of methylphenylpolysiloxane (product name KF-54: Shin-Etsu Chemical Co., Ltd.) 0.100 part by weight was added to 100 parts by weight of the expandable polystyrene resin particles previously introduced into a super mixer [manufactured by Kawata, SMV-20]. Charged for 2 seconds, blended for 60 seconds, then charged with 0.050 parts by weight of dimethylpolysiloxane (product name KF-96-500: Shin-Etsu Chemical) over 60 seconds, blended for 60 seconds, then zinc stearate. 100 parts by weight was added and blended for 60 seconds to obtain expandable polystyrene resin particles.

<Production of pre-expanded particles>
The obtained expandable polystyrene resin particles were sieved to obtain expandable polystyrene resin particles having a particle diameter of 0.6 mm to 1.12 mm.

The expanded polystyrene-based resin particles thus separated were pre-expanded to a bulk magnification of 65 times using a pressure type pre-foaming machine [manufactured by Daikai Kogyo Co., Ltd., BHP] under the condition of a blowing vapor pressure of 0.8 kgf / cm ² . . At this time, air was cut into the blown steam to adjust the blown steam temperature. Then, it was left to stand at room temperature for 1 day, and curing drying was performed.

<Manufacture of in-mold foam molding>
The obtained polystyrene resin pre-expanded particles are filled into a box-shaped mold having a thickness of 25 mm, a length of 530 mm, a width of 330 mm, and a height of 120 mm, using a molding machine [manufactured by Daisen, KR-57]. Then, in-mold molding was performed under molding conditions of a blowing vapor pressure of 0.3 to 0.8 kgf / cm ² to obtain a box-shaped foam molded body.

  Evaluation was performed using the obtained expandable polystyrene resin particles and the foamed molded product, and the results are shown in Table 1.

(Example 2)
In <Addition of external additive to expandable polystyrene resin particles>, expandable polystyrene resin particles, pre-expanded in the same manner as in Example 1 except that zinc stearate was changed to 0.600 parts by weight. Particles and an in-mold foam molding were obtained. The evaluation results are shown in Table 1.

(Example 3)
<Addition of external additive to expandable polystyrene resin particles>, except that the amount of silicone-based external additive applied was changed to 0.035 parts by weight of methylphenylpolysiloxane (product name KF-54: Shin-Etsu Chemical) In the same manner as in Example 1, expandable polystyrene resin particles, pre-expanded particles, and in-mold foam-molded bodies were obtained. The evaluation results are shown in Table 1.

Example 4
<Addition of external additive to expandable polystyrene resin particles>, except that the amount of silicone external additive applied was changed to 0.200 parts by weight of methylphenylpolysiloxane (product name KF-54: Shin-Etsu Chemical) In the same manner as in Example 1, expandable polystyrene resin particles, pre-expanded particles, and in-mold foam-molded bodies were obtained. The evaluation results are shown in Table 1.

(Example 5)
In <Addition of external additive to expandable polystyrene resin particles>, the amount of silicone-based external additive applied was changed to 0.003 parts by weight of dimethylpolysiloxane (product name KF-96-500: Shin-Etsu Chemical). Were the same operations as in Example 1 to obtain expandable polystyrene resin particles, pre-expanded particles, and in-mold foam molded articles. The evaluation results are shown in Table 1.

(Example 6)
In <Addition of external additive to expandable polystyrene resin particles>, except that the coating amount of the silicone external additive was changed to 0.150 parts by weight of dimethylpolysiloxane (product name KF-96-500: Shin-Etsu Chemical) Were the same operations as in Example 1 to obtain expandable polystyrene resin particles, pre-expanded particles, and in-mold foam molded articles. The evaluation results are shown in Table 1.

(Comparative Example 1)
In <Addition of external additives to expandable polystyrene resin particles>, except that the amount of silicone-based external additive applied was changed to only 0.050 parts by weight of methylphenylpolysiloxane (product name KF-54: Shin-Etsu Chemical) Were the same operations as in Example 1 to obtain expandable polystyrene resin particles, pre-expanded particles, and in-mold foam molded articles. The evaluation results are shown in Table 1.

(Comparative Example 2)
In <Addition of External Additive to Expandable Polystyrene Resin Particles>, the amount of silicone external additive applied was changed to only 0.005 parts by weight of dimethylpolysiloxane (product name KF-96-500: Shin-Etsu Chemical). Except for the above, expandable polystyrene resin particles, pre-expanded particles, and in-mold foam-molded bodies were obtained by the same operation as in Example 1. The evaluation results are shown in Table 1.

(Comparative Example 3)
In <Addition of external additives to expandable polystyrene resin particles>, the amount of silicone-based external additive applied was 0.020 parts by weight of methylphenylpolysiloxane (product name KF-54: Shin-Etsu Chemical) and dimethylpolysiloxane. (Product name KF-96-500: Shin-Etsu Chemical) Expandable polystyrene resin particles, pre-expanded particles, and in-mold foam-molded articles were obtained in the same manner as in Example 1 except for changing to 0.050 parts by weight. It was. The evaluation results are shown in Table 1.

(Comparative Example 4)
In <Addition of External Additive to Expandable Polystyrene Resin Particles>, the amount of silicone external additive applied is 0.100 part by weight of methylphenylpolysiloxane (product name KF-54: Shin-Etsu Chemical) and dimethylpolysiloxane (Product name KF-96-500: Shin-Etsu Chemical Co., Ltd.) Expandable polystyrene resin particles, pre-expanded particles, and in-mold foam molded articles were obtained by the same operation as in Example 1 except that the amount was changed to 0.300 parts by weight. It was. The evaluation results are shown in Table 1.

(Comparative Example 5)
In <Addition of external additives to expandable polystyrene resin particles>, the amount of silicone-based external additive applied was changed to 0.0005 parts by weight of dimethylpolysiloxane (product name KF-96-500: Shin-Etsu Chemical). Were the same operations as in Example 1 to obtain expandable polystyrene resin particles, pre-expanded particles, and in-mold foam molded articles. The evaluation results are shown in Table 1.

(Comparative Example 6)
In <Addition of external additive to expandable polystyrene resin particles>, the amount of silicone-based external additive applied is 0.350 parts by weight of methylphenylpolysiloxane (product name KF-54: Shin-Etsu Chemical) and dimethylpolysiloxane. (Product name KF-96-500: Shin-Etsu Chemical) Expandable polystyrene resin particles, pre-expanded particles, and in-mold foam-molded articles were obtained in the same manner as in Example 1 except that the amount was changed to 0.090 parts by weight. It was. The evaluation results are shown in Table 1.

(Comparative Example 7)
In <Addition of external additive to expandable polystyrene resin particles>, the silicone external additive is not applied, but 0.200 parts by weight of zinc stearate and 0.050 parts by weight of castor wax (hydroxystearic acid triglyceride) Except that it was changed to, by the same operation as in Example 1, expandable polystyrene resin particles, pre-expanded particles, and in-mold foam-molded bodies were obtained. The evaluation results are shown in Table 1. In (Comparative Example 13), blocking can be suppressed and good molded article physical properties can be obtained. On the other hand, in this method, it is difficult to shorten the cooling time during molding.

Claims (10)

0.030 to 0.300 parts by weight of methylphenylpolysiloxane, 0.001 to 0.200 parts by weight of dimethylpolysiloxane, and fatty acid metal salt are coated on the resin surface with respect to 100 parts by weight of expandable polystyrene resin particles. Expandable polystyrene resin particles characterized by having been made. ^2. The expandable polystyrene resin particles according to claim 1, wherein the methylphenylpolysiloxane has a viscosity at 25 ° C. of 100 to 6000 mm ² / s. 3. The expandable polystyrene resin particles according to claim 1, wherein the dimethylpolysiloxane has a viscosity at 25 ° C. of 100 to 15000 mm ² / s. The expandable polystyrene resin particles according to any one of claims 1 to 3, wherein the methylphenylpolysiloxane is 0.040 to 0.150 parts by weight. The expandable polystyrene resin particles according to any one of claims 1 to 4, wherein the dimethylpolysiloxane is 0.005 to 0.080 parts by weight. 6. The fatty acid metal salt is zinc stearate, and is 0.005 to 0.500 parts by weight with respect to 100 parts by weight of expandable polystyrene resin particles. Expandable polystyrene resin particles. The expandable polystyrene resin particles according to any one of claims 1 to 6, wherein the amount of the foaming agent contained is 3.0% by weight or more and less than 9.0% by weight. Polystyrene resin pre-expanded particles, wherein the expandable polystyrene resin particles according to claim 1 are expanded. The polystyrene resin pre-expanded particles according to claim 8, wherein the amount of the foaming agent contained is 2.0 wt% or more and 7.0 wt% or less. A polystyrene resin foam, wherein the polystyrene resin pre-expanded particles according to claim 8 or 9 are molded in a mold.