JP2017137449A - Foamed particle compact and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed particle compact having excellent fire retardant and can prevent styrenic monomer from diffusing.SOLUTION: A compact in which with a styrenic resin obtained by emulsion polymerizing the styrenic monomer under the presence of a fire retardant as a base resin, styrenic resin foamed particles containing the fire retardant are fused with each other, and a manufacturing method thereof. The fire retardant contains a bromide of a styrene-butadiene-base copolymer. A weight average molecular weight of the styrenic resin is 150, 000 or higher. A content of the styrenic monomer in the compact is 10 ppm by mass or lower. When manufacturing the compact, foaming particles having a predetermined foaming property is used, and a predetermined control is applied during foaming.SELECTED DRAWING: None

Description

  The present invention relates to a foamed particle molded body containing a brominated product of a styrene-butadiene copolymer as a flame retardant and having a low content of unreacted styrene monomer and a method for producing the same.

  Styrenic resin expanded particle molded bodies obtained from expandable styrene resin particles have excellent heat insulation performance, and are therefore used in heat insulating materials for houses, cold boxes, and the like. In addition, since the styrene resin foamed particle molded article is excellent in light weight and cushioning performance, a styrene resin foamed particle molded article containing a flame retardant is used as an interior material such as an automobile cushioning material or a floor raising material. Has been. Since automobiles have a narrow interior space, there is a need for a molded body having a smaller amount of organic solvent than a heat insulating material for a house. Since the unreacted styrene monomer is contained in the styrene resin foam molded article, it is desired to reduce the unreacted styrene monomer.

  For example, Patent Documents 1 to 3 disclose expandable styrene resin particles containing a flame retardant and containing a small amount of unreacted styrene monomer.

Japanese Patent Laid-Open No. 2007-9018 JP2015-117282A JP 2010-195936 A

  However, the content of the styrenic monomer in Patent Documents 1 and 2 is several hundred ppm, which is insufficient for applications such as automobile interior materials. On the other hand, in Patent Document 3, once the styrene resin particles not containing the flame retardant and the foaming agent are synthesized, the styrene resin particles are impregnated with the foaming agent and the flame retardant in a separate process from this synthesis. It left a challenge in terms of efficiency.

  The present invention has been made in view of such problems, and is intended to provide a foamed particle molded body that has excellent flame retardancy and can prevent the styrene monomer from being diffused, and a method for producing the same. is there.

In one embodiment of the present invention, a styrene resin obtained by suspension polymerization of a styrene monomer in the presence of a flame retardant is used as a base resin, and the styrene resin expanded particles containing the flame retardant are fused to each other. A molded body,
The flame retardant contains a bromide of a styrene-butadiene copolymer,
The styrene resin has a weight average molecular weight of 150,000 or more,
The foamed particle molded body has a content of a styrene monomer in the molded body of 10 mass ppm or less.

Another aspect of the present invention is a polymerization step of obtaining styrene resin particles by suspension polymerization of a styrene monomer in the presence of a flame retardant containing a bromide of a styrene-butadiene copolymer,
An impregnation step of impregnating the styrenic resin particles with an organic physical foaming agent to obtain expandable styrenic resin particles;
A foaming step of obtaining foamed styrene resin particles by foaming the foamable styrene resin particles by heating with steam;
A molding step of fusing styrene resin particles with each other in a mold to obtain a foamed particle molded body,
When the foamable styrene resin particles are foamed by blowing steam with a gauge pressure of 0.03 MPa into the foamable styrene resin particles in a box-type batch pre-foaming machine, a range of steam blowing time of 200 to 400 seconds Having a foaming property such that the minimum bulk density A of the test foamed particles obtained in is 15 to 125 kg / m ³ ,
In the foaming step, the bulk density B of the foamed styrene resin particles obtained after the foaming step and the minimum bulk density A satisfy the relationship of 0.6 ≦ B / A ≦ 0.9. It exists in the manufacturing method of a foaming particle molding which foams an expandable styrene-type resin particle.

  The foamed particle molded body (hereinafter referred to as “molded body” as appropriate) contains a flame retardant composed of a brominated product of a styrene-butadiene copolymer, and contains a styrene resin having a predetermined weight average molecular weight. And content of the styrene-type monomer in a molded object is 10 mass ppm or less. Such a molded product can prevent the styrene monomer from being diffused while exhibiting excellent flame retardancy. Furthermore, the molded body is excellent in bending strength. Therefore, it is suitable for uses such as automobile interior materials that are used in a narrow space and require excellent flame retardancy.

  A molded object can be manufactured by performing a superposition | polymerization process, an impregnation process, a foaming process, and a shaping | molding process as mentioned above, for example. In the polymerization step, the styrene monomer is subjected to suspension polymerization in the presence of a flame retardant containing a bromide of a styrene-butadiene copolymer. Thereby, styrene resin particles containing a flame retardant (hereinafter, referred to as “resin particles” as appropriate) can be obtained. As in this polymerization step, the suspension polymerization of the styrene monomer is performed in the presence of the flame retardant, so that it is not necessary to provide a step for adding the flame retardant. Therefore, resin particles containing a flame retardant can be obtained with high productivity. Furthermore, in the polymerization process, since a brominated product of a styrene-butadiene copolymer that hardly inhibits the polymerization of a styrene monomer as compared with other brominated flame retardants is used as a flame retardant, Resin particles having a low body content can be obtained.

  Further, in the impregnation step, styrene resin particles are impregnated with an organic physical foaming agent to obtain expandable styrene resin particles (hereinafter referred to as “expandable particles” as appropriate). In the foaming step, foaming is performed by steam heating. Foamed styrene-based resin particles (hereinafter referred to as “foamed particles” as appropriate) are obtained by foaming the particles. In the foaming step, the minimum bulk density of the test foamed particles obtained by foaming the expandable particles under the above-mentioned predetermined conditions The foamable particles having foamability in which A is in the predetermined range are used, and in the foaming process, the bulk density B of the foamed particles obtained after the foaming process and the above-mentioned minimum bulk density A satisfy the predetermined relationship. The foaming particles are foamed so as to satisfy.The foaming satisfying this predetermined relationship is hereinafter referred to as “severe foaming” where appropriate. The body can be further reduced, and the content of the styrenic monomer in the molded body obtained after the above-described molding step can be reduced to, for example, 10 ppm by mass or less. Using a bromide of a styrene-butadiene copolymer, a molded body obtained by performing the above-described polymerization process, impregnation process, foaming process, and molding process satisfies the combustion standard of FMVSS No. 302, for example. It is possible to exhibit excellent flame retardancy to the extent that it does, and excellent bending strength.

About the manufacturing method of the said molded object, preferable embodiment is described.
In the polymerization step, styrene monomer particles are obtained by suspension polymerization of a styrene monomer in the presence of a flame retardant. The flame retardant contains a bromide of a styrene-butadiene copolymer. As a brominated product of a styrene-butadiene copolymer, for example, a brominated styrene-butadiene block copolymer can be used.

  As the flame retardant, a brominated flame retardant other than the brominated product of the styrene-butadiene copolymer can be used in combination as long as the intended purpose of the present invention is achieved.

  Suspension polymerization of the styrene monomer in the polymerization step can be performed in an aqueous medium containing a suspending agent, for example. The flame retardant can be supplied into the aqueous medium in a state of being previously dissolved in the styrene monomer. Moreover, a flame retardant can also be disperse | distributed in an aqueous medium with a suspending agent, for example, without melt | dissolving in a styrene-type monomer. It is preferable that the compounding quantity of a flame retardant with respect to 100 mass parts of styrene resin obtained by superposition | polymerization of a styrene monomer is 0.05-2 mass parts. In this case, the flame retardancy can be further improved, and an increase in production cost accompanying an increase in the amount of the flame retardant can be prevented. Furthermore, the polymerization inhibition of the styrene monomer can be further prevented, and the content of the styrene monomer in the molded body can be further reduced. From the viewpoint of further reducing the content of the styrene monomer, the blending amount of the flame retardant with respect to 100 parts by mass of the styrene resin is more preferably less than 1 part by mass, and less than 0.5 parts by mass. More preferably, it is particularly preferably 0.1 parts by mass or less. In addition, the compounding quantity of the above-mentioned flame retardant becomes equal to content of the flame retardant in a molded object normally.

  Styrene can be used as the styrene monomer. In addition to styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, pn-butyl Styrene compounds such as styrene, pt-butylstyrene, divinylbenzene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4,6-tribromostyrene, styrenesulfonic acid, sodium styrenesulfonate Can be used. Styrenic monomers may be used alone or in combination of two or more. From the viewpoint of production cost and ease of molding of the molded body, the main component of the styrenic monomer is preferably styrene.

  Moreover, you may use together the vinyl monomer copolymerizable with a styrene-type monomer. Such vinyl monomers include (meth) acrylic acid, (meth) acrylic acid esters, vinyl monomers containing nitrile groups, organic acid vinyl compounds, olefin compounds, diene compounds, halogenated vinyl compounds, halogenated vinylidene compounds, A maleimide compound etc. are mentioned. “(Meth) acrylic acid” is a concept including “acrylic acid” and “methacrylic acid”, and means one or both of these.

  Examples of (meth) acrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and methacrylic acid. Examples include 2-ethylhexyl, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane trimethacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and the like. Examples of the vinyl monomer containing a nitrile group include acrylonitrile and methacrylonitrile. Examples of the organic acid vinyl compound include vinyl acetate and vinyl propionate. Examples of the olefin compound include ethylene, propylene, 1-butene, 2-butene and the like. Examples of the diene compound include butadiene, isoprene, chloroprene and the like. Examples of the vinyl halide compound include vinyl chloride and vinyl bromide. Examples of the vinylidene halide compound include vinylidene chloride. Examples of maleimide compounds include N-phenylmaleimide and N-methylmaleimide.

  In the polymerization step, for example, in a closed vessel equipped with a stirrer, in the presence of a suitable suspending agent, together with a styrene monomer, a flame retardant, and an organic peroxide (specifically, a polymerization initiator). The polymerization reaction can be initiated by dispersing in an aqueous medium.

  Examples of the organic peroxide include benzoyl peroxide, stearoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxy-2-ethylhexanoate , T-amylperoxy-2-ethylhexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexa Noate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxybenzoate , T-amyl peroxyisopropyl carbonate, t-amino Peroxy-2-ethylhexyl carbonate, t-hexyl peroxyisopropyl carbonate, t-butylperoxy-3,5,5-trimethylhexanoate, 1,1-bis (t-butylperoxy) -3,3,5 -Trimethylcyclohexane, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and the like. The above organic peroxides may be used alone or in combination of two or more. The organic peroxide is preferably used in combination with an organic peroxide having a one-hour half-life temperature of 80 to 100 ° C and an organic peroxide having a one-hour half-life temperature of 100 to 130 ° C. In this case, polymerization inhibition of the styrene monomer can be prevented more efficiently, and the amount of styrene monomer in the molded product can be further reduced.

  The addition amount of the organic peroxide is preferably 0.01 to 2 parts by mass with respect to 100 parts by mass of the styrene monomer. When the addition amount is less than this range, the polymerization rate becomes slow and the productivity is lowered, and when the addition amount is more than this range, the production cost may increase. As for the addition amount of an organic peroxide, it is more preferable that it is 0.1-1 mass part with respect to 100 mass parts of styrene-type monomers.

  In the polymerization process in which the styrene monomer is subjected to suspension polymerization in the presence of the flame retardant as described above, a bromide of a styrene-butadiene copolymer as a flame retardant (hereinafter referred to as “Br-SBC” as appropriate). And the polymerization step, the pre-stage polymerization step for polymerizing most of the styrene monomer at a relatively low temperature and the post-stage polymerization for polymerizing the remaining styrene monomer at a higher temperature than the pre-stage polymerization step It is preferable to divide into multiple stages including processes. Specifically, while using Br-SBC as a flame retardant, the polymerization step is a pre-stage polymerization step in which polymerization of a styrene monomer is performed at a temperature of 110 ° C. or less until a polymerization conversion rate is 90% by mass or more, It is preferable to further include a post-stage polymerization step in which styrene monomer is further polymerized in a temperature range of more than 115 ° C and not more than 135 ° C. In this case, the amount of unreacted styrene monomer in the resin particles obtained in the polymerization step can be further reduced, and the amount of styrene monomer in the molded product can be further reduced. Br-SBC is less likely to inhibit the polymerization of styrenic monomers as compared with conventional brominated flame retardants, and enables the reduction of unreacted styrene monomers by increasing the polymerization temperature on the rear stage side, and Even if the polymerization temperature at the latter stage is increased, the molecular weight of the styrene resin is not significantly reduced. Therefore, by carrying out the multi-step polymerization process as described above, it is possible to obtain resin particles having a high molecular weight with a lower content of unreacted styrene monomer while containing a flame retardant. Hereinafter, the polymerization temperature in the subsequent polymerization step is appropriately referred to as “final polymerization temperature”.

  From the viewpoint of suppressing the decrease in the weight average molecular weight of the styrene-based resin and improving the mechanical strength of the molded product, the polymerization temperature in the pre-stage polymerization step is preferably 110 ° C. or less as described above, and is 105 ° C. or less. More preferably. On the other hand, the lower limit is about 70 ° C. from the viewpoint of polymerization efficiency. Further, from the viewpoint of more sufficiently reducing the amount of unreacted styrene monomer in the subsequent polymerization step performed after the previous polymerization step, the polymerization conversion rate of the styrene monomer in the previous polymerization step is as described above. It is preferable to carry out the polymerization until 90% by mass or more, more preferably the polymerization until 95% by mass or more, and even more preferably the polymerization until 98% by mass or more.

  From the viewpoint of efficiently reducing the unreacted styrene monomer and further preventing the decrease in the weight average molecular weight of the styrene resin, the final polymerization temperature in the subsequent polymerization step is as described above. It is preferably more than 115 ° C and not more than 135 ° C, more preferably 118 to 130 ° C. Under these production conditions, the content of the styrene monomer can be further reduced while further suppressing the decrease in the weight average molecular weight of the styrene resin. Note that the amount of unreacted styrene monomer in the subsequent polymerization step can be controlled by the holding time at the final polymerization temperature.

  In the polymerization step, a flame retardant aid can be used as necessary. As the flame retardant aid, a radical generator having a one-hour half-life temperature exceeding 130 ° C. can be used. The mass ratio of the flame retardant to the flame retardant aid is preferably 1: 0.1 to 1: 5 (however, flame retardant: flame retardant aid). In this case, the flame retardancy of the molded product can be further improved. As flame retardant aids, dicumyl peroxide, di-t-butyl peroxide, cumyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenyl Hexane, poly (1,4-diisopropylbenzene) and the like can be used.

  In suspension polymerization of a styrene monomer, a suspending agent can be used. That is, the styrene monomer can be polymerized in a dispersion medium such as water to which a suspending agent is added. As the suspending agent, for example, hydrophilic polymers such as polyvinyl alcohol, methyl cellulose, polyvinyl pyrrolidone and the like can be used. Moreover, as a suspending agent, a poorly water-soluble inorganic salt such as tricalcium phosphate, magnesium pyrophosphate, hydroxyapatite, aluminum oxide, talc, kaolin, bentonite and the like can be used. Moreover, surfactant can be used together with a suspension agent as needed. In addition, when using a poorly water-soluble inorganic salt as a suspending agent, it is preferable to use together anionic surfactants, such as sodium alkylsulfonate and sodium dodecylbenzenesulfonate.

  The amount of the suspending agent used is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the styrene monomer. As described above, when the suspending agent composed of the hardly water-soluble inorganic salt and the anionic surfactant are used in combination, 0.05 to 3 parts by mass of the suspending agent is added to 100 parts by mass of the styrenic monomer. It is preferable to use 0.0001 to 0.5 parts by mass of a surfactant.

In addition, as long as the effects of the present invention are not impaired, the styrene-based monomer has a bubble nucleating agent (bubble adjusting agent), a plasticizer, a chain transfer agent, a phosphorus flame retardant, an inorganic flame retardant, an antistatic agent, an oxidation Additives such as an inhibitor, an ultraviolet absorber, a light stabilizer, a conductive filler, an organic antibacterial agent, and an inorganic antibacterial agent can be added.
As the cell nucleating agent, for example, polyethylene wax, talc, silica, ethylene bisstearylamide, methyl methacrylate copolymer, silicone and the like can be used.
As the plasticizer, for example, liquid paraffin, glycerol diacetomonolaurate, glycerol tristearate, di-2-ethylhexyl phthalate, di-2-ethylhexyl adipate and the like can be used.
As the chain transfer agent, for example, octyl mercaptan, dodecyl mercaptan, α-methylstyrene dimer and the like can be used.

As the phosphorus flame retardant, for example, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate and the like can be used.
As the inorganic flame retardant, aluminum hydroxide, magnesium hydroxide, calcium carbonate, calcium aluminate, antimony trioxide, expandable graphite, red phosphorus, or the like can be used.

As the antistatic agent, alkyl diethanolamine, glycerin fatty acid ester, sodium alkyl sulfonate and the like can be used.
As the antioxidant, a phenol-based, phosphorus-based, sulfur-based antioxidant or the like can be used.
As the ultraviolet absorber, an ultraviolet absorber such as benzotriazole or benzophenone can be used.
As the light stabilizer, a light stabilizer such as a hindered amine can be used.
As the conductive filler, conductive carbon black, graphite powder, copper zinc alloy powder, copper powder, silver powder, gold powder or the like can be used.
As the organic antibacterial agent, 3-iodo-2-propynylbutyl carbamate (IPBC), thiabendazole (TBZ), carbendazim (BCM), chlorothalonil (TPN), or the like can be used.
As the inorganic antibacterial agent, for example, a silver-based, copper-based, zinc-based or titanium oxide-based antibacterial agent can be used.
Further, rubber components such as butadiene rubber, styrene-butadiene rubber, isoprene rubber, and ethylene-propylene rubber may be added to the styrene monomer as long as the effects of the present invention are not impaired.

  Next, in the impregnation step, expandable styrene resin particles are obtained by impregnating the styrene resin particles with an organic physical foaming agent. The impregnation of the foaming agent in the impregnation step may be performed on the resin particles in the middle of the polymerization, may be performed on the resin particles after the polymerization, or both of them. That is, the “resin particles” in the impregnation step is a concept including at least one of resin particles during polymerization and resin particles after polymerization. It is preferable to add a foaming agent when the polymerization conversion of the styrene monomer is 80% by mass or more. In this case, the content of unreacted styrene monomer can be further reduced. From the same viewpoint, the foaming agent is more preferably added at a timing when the polymerization conversion of the styrene monomer is 88% by mass or more.

  As the organic physical blowing agent, hydrocarbon having 3 to 6 carbon atoms such as propane, n-butane, isobutane, n-pentane, isopentane, cyclopentane, n-hexane, cyclohexane and the like can be used. These foaming agents can be used alone or in combination of two or more. The foaming agent content in the expandable styrenic resin particles is preferably 2 to 10% by mass. An amount such that the foaming agent content in the expandable particles is 1 to 20% by mass is supplied into the sealed container. For example, the foaming agent can be obtained by adding the foaming agent in a closed container.

The foamable particles are the smallest of the test foamed particles obtained in the range of the steam blowing time of 200 to 400 seconds when steam with a gauge pressure of 0.03 MPa is blown into the foamable particles in a box-type batch pre-foaming machine. It is preferable to have a foaming property with a bulk density A of 15 to 125 kg / m ³ . The test foamed particles are used for measurement of the minimum bulk density A, and are foamed under the above-mentioned predetermined conditions, and are different from the foamed particles obtained by an actual foaming process. The minimum bulk density A of the expandable particles is within the above range by adjusting, for example, the type and content of the organic physical foaming agent in the expandable particles, the type and content of the plasticizer, and the molecular weight of the styrene resin. Can be adjusted in.

  As a box-type batch pre-foaming machine, a well-known and commonly used technology collection published by the Japan Patent Office on August 3, 1982. The same type as described in 38 can be used. A box-type batch pre-foaming machine generally has a box having a steam chamber whose front surface can be opened and closed by a door. A large number of steam holes are opened in the inner wall of the box, and steam is introduced into the steam chamber from a steam pipe leading to the box. It has the structure supplied. For the measurement of the minimum bulk density A, for example, a foam box (with a wire mesh stretched on the bottom of the cello) in which foam particles are dispersed is placed in the steam chamber, the door is closed, and the blowing steam pressure is 0.03 MPa (G: gauge pressure). Send steam. The door does not need to be airtight and little pressure is applied to the box. The steam blowing time is determined in the range of 200 to 400 seconds so that the bulk density of the test foamed particles obtained by foaming of the foamable particles is minimized. The minimum value of the bulk density of the test foamed particles is defined as the minimum bulk density A. Since almost no pressure is applied in the box-type batch foaming machine, the minimum bulk density A indicates the minimum bulk density obtained by foaming under atmospheric pressure.

  The content of the styrene monomer in the expandable particles obtained after the impregnation step is preferably 50 ppm by mass or less. In this case, it becomes easy to reduce the content of the styrenic monomer in the molded product obtained through the foaming step and the molding step to, for example, 10 mass ppm or less. From the viewpoint of more surely reducing the content of the styrene monomer in the molded body to 10 ppm by mass or less and further reducing the amount of styrene monomer emitted from the molded body, styrene in the expandable particles. As for content of a system monomer, it is more preferred that it is 30 mass ppm or less, and it is still more preferred that it is 20 mass ppm or less. Moreover, even if the content of the styrene monomer in the expandable particle exceeds 10 mass ppm or more by performing severe foaming, the content of the styrene monomer in the molded body is effectively reduced. It can be reduced to 10 mass ppm or less. The styrenic monomer in the expandable particles can be measured using a head space method gas chromatograph mass spectrometer. As a measurement sample, a dissolved product obtained by dissolving expandable particles in dimethylformamide can be used.

  The water content in the expandable particles is preferably 1.5% by mass or less. In this case, it becomes easier to suppress the coarsening of the bubbles of the expanded particles obtained using the expandable particles, and the aging period until the size of the bubbles becomes uniform can be further shortened. And even if the aging period of expandable particle | grains is shortened, it becomes possible to suppress the fall of the mechanical strength of a foaming molding more, or to improve the external appearance of a foaming molding. The aging period is a period for storing the expandable styrene resin particles in a sealed container under a low temperature environment of, for example, 10 ° C. or less. The water content of the expandable particles is more preferably 1% by mass or less. The amount of moisture in the expandable styrene resin particles can be determined by a Karl Fischer moisture meter equipped with a heating vaporizer.

  Next, in the foaming step, the foamable particles are foamed by heating with steam to obtain foamed particles. The expanded particles are generally called pre-expanded particles. The foaming step can be performed, for example, by supplying steam to expandable particles introduced into a batch type pre-foaming machine equipped with a stirrer.

  Usually, the foamability of the foamable particles is adjusted so that the relationship between the bulk density B of the foamed particles and the above-mentioned minimum bulk density A satisfies B / A ≧ 1. That is, the expandable particles are expanded within a range not exceeding the maximum expansion capability at normal pressure. On the other hand, in the foaming step, the bulk density B of the foamed particles and the above-described minimum bulk density A satisfy the relationship of 0.6 ≦ B / A ≦ 0.9, that is, at normal pressure. Foam the expandable particles beyond the maximum foaming capacity. When B / A increases beyond this range, the content of the styrene monomer contained in the molded product obtained after the molding step may not be sufficiently reduced. From the viewpoint of further reducing the content of the styrenic monomer, B / A ≦ 0.85 is preferable. On the other hand, when B / A is lower than the above range, there is a possibility that the foamed particles may adhere to each other during the foaming process. In order to further avoid this, B / A ≧ 0.7 is preferable.

The bulk density B of the expanded particles can be controlled by adjusting the expansion conditions of the expandable particles. Examples of foaming conditions include steam pressure (specifically, gauge pressure), heating time by steam, and the like. If the bulk density B of the foamed particles is low, the strength of the molded product is insufficient, and if the bulk density B is high, the cost may increase. Therefore, the bulk density B of the foamed particles may be 12 to 100 kg / m ^3. preferable.

  Next, in the molding step, the foamed particles are fused with each other in a molding die to obtain a foamed particle molded body. The molding step can be performed by an in-mold molding method. Specifically, for example, a molded body can be obtained by supplying steam to the foamed particles filled in the mold and heating.

  Next, a preferred embodiment of the molded body will be described. The molded body uses a styrene resin obtained by suspension polymerization of a styrene monomer in the presence of a flame retardant as described above as a base resin. In the molded body, a large number of expanded particles containing a flame retardant are fused to each other. The flame retardant contained in the molded body is as described above, and contains at least a brominated product of a styrene-butadiene copolymer.

  Expanded particles using a styrene resin obtained by suspension polymerization of a styrene monomer in the presence of a flame retardant as a base resin have the flame retardant uniformly distributed in the expanded particles. Therefore, a molded body in which the flame retardant is uniformly distributed in the molded body can be obtained by molding the expanded particles in the mold. That is, the mass-based flame retardant concentration is uniform between the surface layer portion and the inside of the molded body. When the flame retardant is uniformly distributed in the molded body, the molded body exhibits flame retardancy more stably.

  The weight average molecular weight of the styrene resin in the molded body is preferably 150,000 or more. If it is less than 150,000, the strength of the molded product may be reduced. From the viewpoint of further improving the strength of the molded article, the weight average molecular weight is more preferably 180,000 or more, and further preferably 200,000 or more. Moreover, from a viewpoint that the foamability of an expandable particle can be improved, 350,000 or less are preferable and, as for a weight average molecular weight, 300,000 or less are more preferable. The weight average molecular weight is a standard polystyrene equivalent value measured by a gel permeation chromatography method (that is, GPC method).

  The content of the styrene monomer in the molded body is preferably 10 mass ppm or less. In this case, the amount of styrene monomer emitted from the molded body can be sufficiently reduced. Therefore, a molded object becomes suitable by the use in narrow spaces, such as a car interior material. From the same viewpoint, the content of the styrene monomer in the molded body is more preferably 5 ppm by mass or less. The content of the styrenic monomer in the molded body can be measured using a head space method gas chromatograph mass spectrometer in the same manner as the above-mentioned expandable particles. As a measurement sample, a melt obtained by dissolving a test piece collected from a molded body in dimethylformamide can be used.

The apparent density of the molded body is preferably 12 to 100 kg / m ³ . In this case, the molded product can achieve both physical properties such as strength and flammability and light weight.

  Below, the Example and comparative example of a foaming particle molded object are demonstrated.

Example 1
The manufacturing method of the molded body of this example will be described below. First, 16 kg of deionized water, 14.4 g of tribasic calcium phosphate (suspending agent), 0.6 g of sodium α-olefin sulfonate (surfactant), alkylbiphenyl, in an autoclave with an internal volume of 50 L equipped with a stirrer 0.2 g of disodium disulfonate (surfactant) and 24.4 g of sodium acetate (electrolyte) were added. Next, benzoyl peroxide, an organic peroxide having a one-hour half-life temperature of 92 ° C. (“NIPER BW” manufactured by NOF Corporation, water-diluted powder product, polymerization initiator) 43.2 g, half-hour for one hour T-butyl peroxy-2-ethylhexyl monocarbonate (“Perbutyl E” manufactured by NOF Corporation, polymerization initiator), 25.6 g, an organic peroxide having an initial temperature of 119 ° C., brominated styrene-butadiene block Copolymer ("Emerald Innovation 3000" manufactured by Chemtura Japan Co., Ltd., flame retardant) 12.8g, manufactured by Dicumyl Peroxide NOF Co., Ltd., an organic oxide with a one-hour half-life temperature of 136 ° C "Park Mill D", flame retardant aid) 51.2g, liquid paraffin ("Moresco White P-60" manufactured by MORESCO, 128g plasticizer), and polyethylene wax Zehnder (TOYO ADL Co. Ltd. "Polywax 1000", nucleating agent) 3.2g were mixed in styrene 16 kg, were put into the autoclave with stirring the mixture at a rotational speed 210 rpm. The flame retardant used in this example is hereinafter referred to as “flame retardant A” as appropriate. The bromine content of flame retardant A and the 5% weight loss temperature are shown in Table 1 below.

  Next, after the air in the autoclave was replaced with nitrogen, the temperature was raised to 90 ° C. over 1 hour and a half, and after reaching that temperature 90 ° C., the temperature inside the autoclave was further increased to 100 ° C. over 6 hours 30 minutes. Allowed to warm. Thereafter, the temperature inside the autoclave was further raised to a temperature of 120 ° C. over 2 hours, and the autoclave was maintained at the temperature of 120 ° C. for 5 hours. Then, it cooled over about 6 hours to the temperature of 30 degreeC. Pentane (a mixture of n-pentane 80% and isopentane 20%) is used as a foaming agent when the temperature rises from 90 ° C. to 100 ° C. and 5 hours and 30 minutes elapses after reaching 90 ° C. 320 g and 880 g of butane (a mixture of 70% n-butane and 30% isobutane) were pressed into the autoclave over 30 minutes. The polymerization conversion of styrene at the start of addition of the blowing agent, that is, 5 hours and 30 minutes after reaching 90 ° C., was 89% by mass. Moreover, the polymerization conversion rate of styrene at the time of completion | finish of a pre-stage polymerization process, ie, at the time of reaching | attaining 100 degreeC, was 99 mass%. The method for measuring each polymerization conversion rate is as described later.

  After cooling, take out the contents (expandable particles) from the autoclave, add nitric acid to the expandable particles to remove tricalcium phosphate adhering to the surface of the expandable particles, dehydrate in a centrifuge, and fluid dry The water | moisture content adhering to the surface was removed with the apparatus. In this way, expandable particles having an average particle diameter of about 1.0 mm were obtained.

  Next, the foamable particles were sieved to select particles of 0.5 to 1.4 mm. Thereafter, 0.005 parts by mass of N, N-bis (2-hydroxyethyl) alkylamine (antistatic agent) is added to 100 parts by mass of the expandable particles to coat the expandable particles with the antistatic agent. did. Further, 0.1 part by mass of zinc stearate, 0.05 part by mass of glycerin tristearate, and 0.05 part by mass of glycerin monostearate are added to 100 parts by mass of expandable particles, and a mixture thereof. The expandable particles were coated with. Thereafter, the expandable particles were put in a sealed container and aged by storing in a 6 ° C. cool box.

  For the expandable particles, the amount of foaming agent, the amount of styrene monomer, the amount of water, and foamability (specifically, the minimum bulk density A of the test foam particles) were measured. The results are shown in Table 2. Moreover, the measuring method of a polymerization conversion rate is shown below.

"Polymerization conversion rate at the end of the pre-stage polymerization process"
A separate pre-polymerization step was performed under the same conditions as the pre-polymerization step performed when producing the expandable particles. Simultaneously with the completion of this prepolymerization step, the temperature of the contents of the autoclave was rapidly cooled to 30 ° C. or less within 10 minutes to stop the polymerization reaction. After cooling, the styrene resin particles in the middle of polymerization were taken out from the autoclave, dehydrated with a centrifugal separator, and water adhering to the surface was removed with a fluid dryer. In this way, styrene resin particles at the end of the previous polymerization step were obtained. The content of unreacted styrene monomer in the obtained styrene resin particles was determined by gas chromatography. The measuring method will be described later. And the polymerization conversion rate was calculated | required from the following Formula (1). This operation was performed 3 times, and the arithmetic average value of each polymerization conversion rate was obtained.
Polymerization conversion rate (mass%) = 100-styrene monomer content (mass%) (1)

"Polymerization conversion rate when impregnated with foaming agent"
Polymerization was carried out separately under the same conditions as in the preparation of the expandable particles, and immediately before the addition of the foaming agent was started, the temperature of the autoclave contents was rapidly cooled to 30 ° C. or less within 10 minutes to stop the polymerization reaction. . And the polymerization conversion rate at the time of a foaming agent impregnation was calculated | required by performing operation similar to the measurement of the polymerization conversion rate at the time of completion | finish of the above-mentioned pre-stage polymerization process. This operation was performed 3 times, and the arithmetic average value of each polymerization conversion rate was obtained.

"Content of foaming agent"
The content of the blowing agent was measured by gas chromatography of the dissolved product obtained by dissolving the expandable particles in dimethylformamide (DMF). Specifically, first, about 5 g of cyclopentanol was precisely weighed to the third decimal place in a 100 mL volumetric flask. This weight is hereinafter referred to as Wi (unit: g). Further, DMF was added to the volumetric flask to make the total volume 100 mL. This DMF solution was further diluted 100 times with DMF. This was used as an internal standard solution. Next, about 1 g of expandable particles to be measured was precisely weighed to the third decimal place. This weight is hereinafter referred to as Ws (unit: g). A precisely weighed sample of expandable particles was dissolved in about 18 mL of DMF, and 2 mL of the internal standard solution was accurately added using a whole pipette. 1 μL of the solution thus obtained was collected with a microsyringe and introduced into gas chromatography to obtain a chromatogram. The foaming agent component and the peak area of the internal standard were determined from the obtained chromatogram, and the concentration of each component was determined from the following equation (1).
Component concentration (unit: mass%) = (Wi / 10000) ² × (An / Ai) × Fn ÷ Ws × 100 (1)
Here, Wi: weight of cyclopentanol when the internal standard solution was prepared (g), Ws: weight of sample dissolved in DMF (unit: g), An: peak area of each component at the time of gas chromatograph measurement, Ai : Peak area of internal standard substance at the time of gas chromatograph measurement, Fn: Correction coefficient of each component obtained from calibration curve prepared in advance. The conditions of gas chromatographic analysis were as follows. Equipment used: Gas Chromatograph GC-6AM manufactured by Shimadzu Corporation, Detector: FID (Hydrogen Flame Ionization Detector), Column material: Glass column with an inner diameter of 3 mm and a length of 5000 mm, Column packing: [Liquid phase name] FFAP (free fatty acid), [liquid phase impregnation rate] 10% by mass, [carrier name] diatomaceous earth Chomasorb W for gas chromatograph, [carrier particle size] 60/80 mesh, [carrier treatment method] AW-DMCS (water washing / calcination / acid Treatment / silane treatment), [packing amount] 90 mL, inlet temperature: 100 ° C., column temperature: 40 ° C., detector temperature: 100 ° C., carrier gas: N ₂ , flow rate 40 ml / min.

"Styrene monomer content"
The content of unreacted styrene in the expandable particles was measured with a head space method gas chromatograph mass spectrometer. As a sample, a dissolved material obtained by dissolving expandable particles in dimethylformamide (that is, DMF) was used. Specifically, first, a standard solution is prepared so that the styrene concentration in DMF is 5 mass ppm, 50 mass ppm, and 500 mass ppm. Next, 0.2 g of the standard solution was precisely weighed into a vial with a volume of 20 ml, and sealed with 1 ml of DMF. The temperature was kept with a headspace sampler, the gas phase portion was measured with a gas chromatograph mass spectrometer, and a calibration curve was created from the obtained chromatogram. Next, 0.2 g of the sample was precisely weighed in a 20 ml vial, sealed with 1 ml of DMF, and kept at room temperature for 1 day for complete dissolution. The temperature was kept with a headspace sampler, the gas phase was measured with a gas chromatograph mass spectrometer, and the content of unreacted styrene monomer was determined from the obtained chromatogram and a calibration curve prepared in advance.
The conditions for gas chromatograph mass spectrometry were as follows.
Gas chromatograph mass spectrometer: GCMS-QP2020 manufactured by Shimadzu Corporation
Headspace sampler: HS-20 manufactured by Shimadzu Corporation
Capillary column: GL Science Co., Ltd. Stabilwax, inner diameter 0.32 mm, length 30 m
Headspace sampler heat retention conditions: 90 ° C., 1 hour Column temperature: 50 ° C. × 2 minutes → (10 ° C./minute)→90° C. → (5 ° C./minute)→120° C. → (20 ° C./minute)→230° C. × 2 minutes Ion source temperature: 200 ° C
Carrier gas: helium, column flow rate 2 ml / min Split ratio: 1/10

"amount of water"
The water content of the expandable particles was measured with a Karl Fischer moisture meter. Specifically, about 0.28 g of a sample of expandable particles was precisely weighed. Next, the moisture was vaporized by heating the sample at a temperature of 160 ° C. with a moisture vaporizer CHK-501 manufactured by Kyoto Electronics Industry Co., Ltd. Titration method) Measured using MKC-610.

"Minimum bulk density A of test foamed particles"
In a box-type batch pre-foaming machine, steam with a gauge pressure of 0.03 MPa was blown into the foamed particles after aging to produce foamed test foamed particles. And the minimum value (minimum bulk density A) of the bulk density of the test foamed particle obtained in the range of 200 to 400 seconds of steam blowing time was calculated | required. The measurement of the bulk density was performed on the expanded particles which had been air-dried all day and night. After air drying, the foamed particles were filled to a 1 L mark position in a 1 L graduated cylinder and weighed, and the mass W _P (unit: g) of the 1 L bulk volume of foam particles was weighed to the first decimal place. And bulk density (unit: kg / m < ³ >) was calculated | required by performing unit conversion.

  Next, 3.6 kg of the expandable styrenic resin particles after aging are put into a pressure batch foaming machine (DYHL-500U, manufactured by Daisen Kogyo Co., Ltd.), and the pressure inside the foaming machine (however, the gauge pressure) becomes 0.023 MPa. Steam with a gauge pressure of 0.15 MPa was supplied and heated for 130 seconds to obtain expanded particles having an expansion ratio of about 50 times. The bulk density B of the obtained expanded particles was measured in the same manner as the above test expanded particles. Further, the ratio (B / A) of the bulk density B of the foamed particles to the minimum bulk density A of the test foamed particles was calculated. The results are shown in Table 2.

  Next, the foamed particles were aged at room temperature for 1 day, then filled in a mold of a molding machine manufactured by DABO, and heated at a steam pressure (however, a gauge pressure) of 0.08 MPa for 15 seconds. Subsequently, after cooling for a predetermined time, it was taken out from the mold, and a 300 mm × 300 mm × 25 mm plate-like molded body in which a large number of expanded particles were fused to each other was obtained. Next, for the molded body, the molecular weight of the styrene resin, the content of unreacted styrene monomer, the amount of styrene monomer diffused, and the bending strength were measured, and the combustion test was evaluated. The results are shown in Table 2.

"Molecular weight"
The molecular weight (number average molecular weight, weight average molecular weight, Z average molecular weight) of the styrene resin in the molded body was measured by a gel permeation chromatography method using polystyrene as a standard substance. Specifically, using HLC-8320GPC EcoSEC manufactured by Tosoh Corporation, measurement was performed under the measurement conditions of eluent: tetrahydrofuran (THF), THF flow rate: 0.6 ml / min, and sample concentration: 0.1 wt%. As the column, a column in which TSK guard column Super H-H × 1 and TSK-GEL Super HM-H × 2 were connected in series was used. That is, the test piece collected from the molded body was dissolved in tetrahydrofuran, and the molecular weight was measured by gel permeation chromatography. And the measured value was calibrated with standard polystyrene and the number average molecular weight, the weight average molecular weight, and the Z average molecular weight were calculated | required, respectively.

"Styrene monomer content"
As a sample, measurement was performed in the same manner as the above-mentioned expandable particles except that a dissolved material obtained by dissolving a part of the molded body in dimethylformamide (that is, DMF) was used.

“Emission of styrene monomer”
A foamed molded product was obtained under the same conditions as the above molding conditions except that a molding die for molding a plate-shaped molded product having dimensions of 100 mm × 80 mm × 15 mm was used. The molded body was dried at 40 ° C. for 1 day, and further allowed to stand for 1 day or longer under conditions of a temperature of 23 ° C. and a humidity of 50%, thereby adjusting the state of the molded body. Thereafter, the molded body was put in a 10 L tedlar bag and heat sealed. Next, after purging the inside of the Tedlar bag with nitrogen three times, 4 L of nitrogen was injected into the bag and maintained at a temperature of 40 ° C. for 2 hours. 1.0 L of styrene monomer generated from the molded body was collected in a Tenax-TA collection tube at a flow rate of 0.1 ml / min. Subsequently, the styrene-type monomer in a collection tube was quantified with the heat | fever desorption-gas chromatograph mass spectrometer, and the amount (unit: microgram / m < ³ >) of styrene-type monomers per 1 m < ³ > gas was calculated | required.

"Flammability test"
The evaluation of combustibility was performed according to FMVSS No302. Specifically, the molded body was cured by leaving it at a temperature of 40 ° C. for 3 days and then leaving it at room temperature for 1 day. Next, a plate-like test piece of 355 mm × 100 mm × 12.7 mm was cut out from the molded body. Two lines are drawn from one end of the test piece at positions of 38 mm (combustion time measurement start line) and 292 mm (combustion time measurement end line). Dimensions: 381 mm × 203 mm × 356 mm FMVSS No302 A test piece was fixed to a metal U-shaped frame in a dedicated chamber and held horizontally. The flame height of a Bunsen burner having an inner diameter of 9 mm using natural gas was adjusted to 38 mm. The air intake of the burner was fully closed, and the flame height was adjusted according to the amount of gas. Both were arrange | positioned so that the distance of a burner front-end | tip and the lower end of a test piece might be set to 19 mm. After 15 seconds of indirect flame at the open end of the test piece, the flame was moved away, and timing was started when the flame reached the combustion time measurement start line. The time taken to pass between the combustion time measurement start line and the combustion time measurement end line (ie, combustion time, unit: second) was measured. In case of fire extinguishing on the way, the time until fire extinguishing was counted. The distance between the combustion time measurement start line and the combustion time measurement end line is defined as the combustion distance (unit: mm). When the fire was extinguished halfway, the distance from the combustion time measurement start line to the point where the fire was extinguished was measured, and the combustion speed was determined from the combustion distance and the combustion time based on the following equation (2).
Burning rate (unit: mm / min) = burning distance (unit: mm) ÷ burning time (unit: second) × 60 (2)
When the combustion speed is 102 mm / min or less, or when the fire is extinguished within 51 mm and within 60 seconds from the combustion time measurement start line, it shall conform to FMVSS No 302.

"Bending strength"
The molded body was cut to prepare a test piece having a length of 300 mm, a width of 75 mm, and a thickness of 25 mm. In accordance with JIS K 7221-2: 2006, the distance between the fulcrums was 200 mm, the pressure wedge 10R and the support base 10R, A three-point bending test was performed under the condition of a pressure wedge descent rate of 10 mm / min, and the bending strength was measured.

(Example 2)
The foaming agent was added in the same manner as in Example 1 except that 320 g of pentane (a mixture of 80% n-pentane and 20% isopentane) and 928 g of butane (a mixture of 70% n-butane and 30% isobutane) were used.

(Example 3)
The same procedure as in Example 1 was conducted except that the amount of the blowing agent added was 320 g of pentane (a mixture of 80% n-pentane and 20% isopentane) and 976 g of butane (a mixture of 70% n-butane and 30% isobutane).

Example 4
After the air in the autoclave is replaced with nitrogen, the temperature is raised to 90 ° C. over 1 hour and a half, and after the polymerization temperature reaches 90 ° C., the temperature in the autoclave is raised to 100 ° C. over 6 hours 30 minutes. Was carried out in the same manner as in Example 1. Next, the temperature was further raised to 115 ° C. over 2 hours, and the temperature was maintained at 115 ° C. for 5 hours. Then, it cooled over 30 hours to 30 degreeC. The operation after cooling was performed in the same manner as in Example 1.

(Comparative Example 1)
The same procedure as in Example 1 was carried out except that the amount of the blowing agent added was 400 g of pentane (a mixture of 80% n-pentane and 20% isopentane) and 1200 g of butane (a mixture of 70% n-butane and 30% isobutane). .

(Comparative Example 2)
As in Example 1, except that 160 g of 2,2-bis (4 ′-(2 ″, 3 ″ -dibromo-2 ″ -methylpropoxy-3 ′, 5′-dibromophenyl) propane was used as the flame retardant. The flame retardant used in this example is hereinafter appropriately referred to as “flame retardant B.” The bromine content of the flame retardant B and the 5% weight loss temperature are shown in Table 1 below.

As shown in Table 2, since the molded bodies of Examples 1 to 4 have a low content of styrene monomer, it is understood that the amount of styrene monomer emitted is as low as 100 μg / m ³ or less. In addition, since the weight average molecular weight of the styrene resin is maintained at 150,000 or more, it has excellent bending strength, contains bromide of styrene-butadiene copolymer as a flame retardant, and conforms to the flammability test of FMVSS No302 doing. In Example 4, since the final polymerization temperature was lowered to 115 ° C., the molecular weight of the obtained polymer was increased, and the bending strength of the molded body was improved. On the other hand, the content of the styrene monomer in the molded body is slightly increased. Further, as is known from Table 2, the molded article of the example uses a bromide of at least a styrene-butadiene copolymer as a flame retardant, and has a foaming property having a foaming property in which the minimum bulk density A is in a predetermined range. It can be produced by using particles and performing at least the above-mentioned severe foaming in which B / A falls within a predetermined range.

On the other hand, Comparative Example 1 is an example in which the addition amounts of butane and pentane as foaming agents were increased as compared with Example 1. As a result, the ratio B / A of the bulk density B to the minimum bulk density A was increased to 1.28, and the reduction of the styrene monomer during the foaming process was insufficient. The content is as high as 11.4 mass ppm. Thereby, it turns out that the diffusion amount of the styrene monomer of a molded object is as large as 127 microgram / m < ³ >.

  In Comparative Example 2, a brominated styrene-butadiene copolymer was not used as a flame retardant, but instead flame retardant B shown in Table 1, ie, 2,2-bis (4 ′-(2 ″, 3 ″ -dibromo). -2 ″ -methylpropoxy-3 ′, 5′-dibromophenyl) propane. In this case, the polymerization of the styrenic monomer in the polymerization process is likely to be inhibited, The content of the styrene monomer was increased, and the content of the styrene monomer in the molded product obtained after the foaming step and the molding step was also increased. Since it was as low as 50,000, only a molded article having inferior bending strength was obtained.

Claims (6)

A molded body in which a styrene resin obtained by suspension polymerization of a styrene monomer in the presence of a flame retardant is used as a base resin, and the styrene resin expanded particles containing the flame retardant are fused to each other.
The flame retardant contains a bromide of a styrene-butadiene copolymer,
The styrene resin has a weight average molecular weight of 150,000 or more,
The foamed particle molded body, wherein the content of the styrene monomer in the molded body is 10 mass ppm or less. The expanded particle molded body according to claim 1, wherein the apparent density of the molded body is 12 to 100 kg / m ³ . A polymerization step of suspension polymerization of a styrene monomer in the presence of a flame retardant containing a bromide of a styrene-butadiene copolymer to obtain styrene resin particles;
An impregnation step of impregnating the styrenic resin particles with an organic physical foaming agent to obtain expandable styrenic resin particles;
A foaming step of obtaining foamed styrene resin particles by foaming the foamable styrene resin particles by heating with steam;
A molding step of fusing styrene resin particles with each other in a mold to obtain a foamed particle molded body,
When the foamable styrene resin particles are foamed by blowing steam with a gauge pressure of 0.03 MPa into the foamable styrene resin particles in a box-type batch pre-foaming machine, a range of steam blowing time of 200 to 400 seconds Having a foaming property such that the minimum bulk density A of the test foamed particles obtained in is 15 to 125 kg / m ³ ,
In the foaming step, the bulk density B of the foamed styrene resin particles obtained after the foaming step and the minimum bulk density A satisfy the relationship of 0.6 ≦ B / A ≦ 0.9. A method for producing a foamed particle molded body, wherein foamable styrene resin particles are foamed. The manufacturing method of the foaming particle molding of Claim ³ whose bulk density B of the said foaming styrene-type resin particle is 12-100 kg / m < ³ >.   The method for producing a foamed particle molded body according to claim 3 or 4, wherein the content of the styrene monomer in the foamed particle molded body is 10 mass ppm or less.   The method for producing a foamed particle molded body according to any one of claims 3 to 5, wherein the content of the styrene monomer in the expandable styrene resin particles is 50 mass ppm or less.