JP5565240B2 - Composite resin foamed particles and method for producing the same, and method for producing foamable composite resin particles - Google Patents

Description

  The present invention relates to a composite resin foamed particle comprising a olefin resin component and a styrene resin component and containing a flame retardant, a method for producing the same, and a method for producing foamable composite resin particles.

Foamed particle moldings are used in a wide range of applications such as packaging materials, building materials, and vehicle components, taking advantage of their excellent cushioning, lightness, vibration proofing, soundproofing, and heat insulation properties. Yes. The foamed particle molded body is obtained by, for example, a method in which resin particles are impregnated with a physical foaming agent such as propane, butane, and pentane to produce foamable resin particles, and the foamable resin particles are heated and foamed. Thereafter, the foamed particles are produced by fusing each other in a mold.
As the base resin of the foamed particle molded body, those made of styrene resin such as polystyrene resin and those made of olefin resin such as polypropylene resin and polyethylene resin are mainly used, but in recent years, olefin resin component and styrene are used. A composite resin with a system resin component has attracted attention.

  The foamed particle molded body using the composite resin as a base resin is excellent in toughness, oil resistance, etc., for example, compared with a polystyrene resin foamed particle molded body, and is therefore used as a packaging material for precision parts and heavy products. . Moreover, since it has sufficient compressive strength and buffering properties, it is widely used as automobile members such as bumpers and floor spacers.

However, the foamed particle molded body using the composite resin as a base resin has a drawback that it is easily burnt.
Therefore, a technique for imparting flame retardancy to a foamed particle molded body using the composite resin as a base resin has been developed. Specifically, for example, when the expansion ratio of the styrene-modified polyethylene resin foam molded article is Y times and the amount of the combustible foaming agent remaining in the molded article is X wt%, X ² × Y ≦ 5 A technique for maintaining the remaining amount of foaming agent and the expansion ratio in a specific relationship has been proposed (see Patent Document 1).
In addition, a method has been proposed for obtaining foamed particles using styrene-modified polyolefin resin as a base resin, using tetrabromocyclooctane or tris (2,3-dibromopropyl) isocyanurate as a flame retardant (Patent Literature). 2-4).

In addition, the foamed particle molded body may be desired to be colored black depending on the application. Carbon black is known as such a black colorant.
However, carbon black may cause polymerization delay or incomplete polymerization of the styrene monomer. In order to avoid such problems, a method for obtaining carbon black-containing styrene-modified expandable olefin resin particles using a polymerization initiator mainly composed of a polymerization initiator that generates tertiary alkoxy radicals has been proposed. (See Patent Document 5).

JP-A-6-57027 Japanese Patent Laid-Open No. 7-179646 Japanese Patent Laid-Open No. 7-179647 JP 2006-257150 A Japanese Patent Publication No. 5-54854

  However, in the method in which the flame retardant is impregnated in the resin particles with the aliphatic hydrocarbon or the cycloaliphatic hydrocarbon as in the above-mentioned Patent Documents 1 to 4, the foamable resin particles are briefly foamed after the preliminary foaming. When foamed particles are molded by aging, there is a problem that the residual amount of aliphatic hydrocarbons or cycloaliphatic hydrocarbons in the resulting foamed particle molded body (foamed resin molded body) increases. As a result, the flame retardancy of the foamed resin molded article is insufficient, and there is a problem that the molding cycle during molding becomes long. In addition, since the residual amount of aliphatic hydrocarbons or cycloaliphatic hydrocarbons contained in the expanded particles differs depending on the aging conditions (temperature, time) of the expanded particles, there is a problem that the dimensional shrinkage rate of the expanded material changes significantly. There is.

  In addition, the foamed particles obtained from the carbon black-containing styrene-modified foamable olefin-based resin particles as described in Patent Document 5 and the molded product thereof have a problem that they easily burn.

  The present invention has been made in view of such problems, and is a composite resin foamed particle comprising an olefin resin component and a styrene resin component capable of exhibiting excellent flame retardancy, a method for producing the same, and foaming An object of the present invention is to provide a method for producing conductive composite resin particles.

The first invention is a composite comprising a polyolefin resin particle suspended in an aqueous medium, a styrene monomer added, and the polyolefin resin particle impregnated with the styrene monomer and polymerized. 20 to 50 parts by mass of an olefin resin component and 80 to 50 parts by mass of a styrene resin component obtained by foaming resin particles (however, the total amount of the olefin resin component and the styrene resin component) Is 100 parts by mass) composite resin expanded particles,
The composite resin expanded particles include bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2-bis (4- (2,3-dibromo-2-methylpropoxy). 1 to 15% by mass of one or more halogen-based flame retardants selected from -3,5-dibromophenyl) propane ,
The composite resin foam aliphatic hydrocarbon content of 3 to 6 carbon atoms in the particle is less than 0.1 mass% (including 0) der is, styrene monomer, toluene, xylene, and the total content of ethylbenzene 200ppm or less (including 0) is the der Rukoto the composite resin foamed particles, wherein (claim 1).

In a second invention, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2 is added to a suspension of polyolefin resin particles suspended in an aqueous medium. A styrene monomer in which a halogen flame retardant containing at least one selected from -bis (4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl) propane is dissolved, Modification is obtained by adding 100 to 400 parts by mass to 100 parts by mass of polyolefin resin particles, and impregnating and polymerizing the polyolefin resin particles with the styrene monomer to obtain composite resin particles containing the halogen flame retardant. Process,
An impregnation step of impregnating a physical foaming agent containing 50 to 100% by mass of an inorganic physical foaming agent during and / or after the polymerization of the composite resin particles;
And a foaming step of heating and foaming the composite resin particles impregnated with the physical foaming agent to obtain composite resin foamed particles (claim 4 ).

In a third aspect of the invention, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2 is added to a suspension in which polyolefin resin particles are suspended in an aqueous medium. A styrene monomer in which a halogen flame retardant containing at least one selected from -bis (4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl) propane is dissolved, Modification is obtained by adding 100 to 400 parts by mass to 100 parts by mass of polyolefin resin particles, and impregnating and polymerizing the polyolefin resin particles with the styrene monomer to obtain composite resin particles containing the halogen flame retardant. Process,
An impregnation step of dispersing the composite resin particles together with a physical foaming agent containing 50 to 100% by mass of an inorganic physical foaming agent in a dispersion medium in a pressure resistant container, and impregnating the physical foaming agent;
And a foaming step of releasing the foamed composite resin particles impregnated with the physical foaming agent from the pressure vessel in a heat-softened state to foam the composite resin foamed particles. (Claim 5 ).

In a fourth aspect of the invention, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2 is added to a suspension obtained by suspending polyolefin resin particles in an aqueous medium. A styrene monomer in which a halogen flame retardant containing at least one selected from -bis (4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl) propane is dissolved, Modification is obtained by adding 100 to 400 parts by mass to 100 parts by mass of polyolefin resin particles, and impregnating and polymerizing the polyolefin resin particles with the styrene monomer to obtain composite resin particles containing the halogen flame retardant. Process,
An impregnation step of impregnating a physical foaming agent containing 50 to 100% by mass of an inorganic physical foaming agent during and / or after the polymerization of the composite resin particles. (Claim 7 ).

Composite resin foamed beads of the present invention is composed of an olefin resin component and the styrenic resin component of the specific ratio, and contains the specific amount of the specific halogenated flame retardants. Then, in the above-described composite resin foamed particles, aliphatic hydrocarbon content is less than 0.1 wt% of 3 to 6 carbon atoms (including 0) der is, the total content of styrene monomer, toluene, xylene, and ethylbenzene the amount (including 0) 200ppm or less Ru der.
Therefore, while the composite resin foam particles are made of a base resin that is difficult to be flame retardant, the foamed particle molded body obtained by molding the composite resin foam particles in a mold can exhibit excellent flame retardancy. As well as being excellent in dimensional stability and mechanical properties. Further, the composite resin foamed particles have a short molding cycle at the time of in-mold molding.

  Furthermore, the composite resin foamed particles can exhibit excellent flame retardancy even if they contain a component that deteriorates flame retardancy, such as carbon black. Therefore, in the case of producing the composite resin foam particles colored in black with carbon black or the like in addition to white, excellent flame retardancy can be exhibited.

Next, the composite resin foamed particles can be produced by performing the reforming step, the impregnation step, and the foaming step.
In the above-described modification process, the polyolefin resin particles were added into a suspension in an aqueous medium, a styrene-based monomer prepared by dissolving the above specific halogenated flame retardants in a specific ratio, polyolefin The resin particles are impregnated with the styrene monomer and polymerized to obtain composite resin particles containing the halogen flame retardant.
An impregnation step of impregnating the physical foaming agent containing the specific amount of the inorganic physical foaming agent during and / or after polymerization of the composite resin particles, and heating and foaming the composite resin particles impregnated with the physical foaming agent Or an impregnation step in which the composite resin particles are dispersed together with the physical foaming agent in a dispersion medium in a pressure resistant container and impregnated with the physical foaming agent, and the physical foaming agent is impregnated. The composite resin foamed particles are obtained by performing a foaming step in which the composite resin particles are released from the pressure-resistant container in a heat-softened state and foamed.

  In this way, it is possible to obtain a foamed particle molded body composed of an olefin resin component and a styrene resin component at a specific ratio exhibiting excellent flame retardancy, dimensional stability, and mechanical properties by in-mold molding. The composite resin foamed particles can be obtained.

  Further, by performing the modification step and the impregnation step of impregnating a physical foaming agent containing 50 to 100% by mass of an inorganic physical foaming agent during and / or after polymerization of the composite resin particles, It is possible to obtain expandable composite resin particles comprising a halogen flame retardant and an inorganic physical foaming agent and comprising a specific ratio of an olefin resin component and a styrene resin component. The said foamable composite resin particle can manufacture the said composite resin foamed particle by performing the foaming process of heating and foaming this foamable composite resin particle. And as above-mentioned, this composite resin foamed particle is comprised from the specific ratio olefin resin component and styrene resin component which show the outstanding flame retardance, dimensional stability, and mechanical physical property by in-mold shaping | molding. It can be used to produce a foamed particle molded body.

  As described above, according to the present invention, composite resin foamed particles composed of an olefin resin component and a styrene resin component at a specific ratio capable of exhibiting excellent flame retardancy, a method for producing the same, and the composite resin The manufacturing method of the expandable composite resin particle which can obtain an expanded particle can be provided.

Next, a preferred embodiment of the present invention will be described.
In the present invention, expanded particles (hereinafter referred to as “composite resin expanded particles” as appropriate) containing a specific halogen-based flame retardant and composed of a styrene resin component and a polyolefin resin component are an olefin resin and a styrene resin. A composite resin particle containing a resin and a specific halogen flame retardant (hereinafter referred to as “composite resin particle” as appropriate) is impregnated with a physical foaming agent and foamed.
The composite resin particles include, for example, a modified resin (composite resin) in which a dispersed phase mainly composed of a styrene resin is dispersed in a continuous phase mainly composed of an olefin resin. When the internal cross section of the composite resin particle is observed with a transmission electron microscope, the cross section forms a sea-island structure in which the dispersed phase having a substantially circular shape and / or an irregular shape is dispersed in the continuous phase. Preferably it is.
In addition, the composite resin particle is a resin whose base resin is a modified resin formed by forming a co-continuous phase composed of a continuous phase mainly composed of a styrene resin and a continuous phase mainly composed of an olefin resin, The base resin includes a modified resin in which a dispersed phase mainly composed of an olefin resin is dispersed in a continuous phase mainly composed of a styrene resin.

  Examples of the olefin resin component constituting the base resin of the composite resin foamed particles of the present invention include low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene / propylene copolymer, ethylene / propylene / butene. -1 copolymer, ethylene / butene-1 copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic acid alkyl ester copolymer, ethylene / methacrylic acid alkyl ester copolymer Ethylene resins such as propylene homopolymer, propylene / ethylene copolymer, propylene / butene-1 copolymer, propylene / ethylene / butene-1 copolymer, propylene / 4-methylpentene-1 copolymer, etc. Or a mixture of two or more thereof. Preferably, linear low density polyethylene and / or ethylene-vinyl acetate copolymer are used from the viewpoint of foaming agent retention and strength significance.

  Examples of the styrene resin component constituting the base resin of the composite resin foamed particle of the present invention include a styrene monomer polymer and a copolymer of a styrene monomer and a monomer component copolymerizable with the styrene monomer. . Examples of the monomer component copolymerizable with the styrene monomer include alkyls having 1 to 10 carbon atoms of acrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Esters, etc .; Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, alkyl esters having 1 to 10 carbon atoms of methacrylic acid such as methacrylic acid-2-ethylhexyl, etc .; α-methylstyrene, o-methylstyrene , M-methylstyrene, p-methylstyrene, vinyltoluene, p-ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene 2,4-dichlorostyrene, p- -Butyl styrene, pt-butyl styrene, pn-hexyl styrene, p-octyl styrene, styrene sulfonic acid, sodium styrene sulfonate, etc .; nitrile group-containing unsaturated compounds such as acrylonitrile, methacrylonitrile, etc. . Specific examples include polystyrene, rubber-modified polystyrene, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, acrylonitrile-ethylene-styrene resin, or a mixture of two or more thereof, preferably polystyrene, styrene and butyl acrylate. And a copolymer with an acrylic monomer such as However, the copolymer of the styrene monomer and the monomer component copolymerizable with the styrene monomer preferably contains 50% by mass or more of the styrene monomer component. In the present specification, the styrene monomer and the monomer component copolymerizable with the styrene monomer are referred to as a styrene monomer.

In the composite resin foamed particles of the present invention, the base resin is composed of 20 to 50 parts by mass of an olefin resin component and 80 to 50 parts by mass of a styrene resin component (however, the olefin resin component and the styrene resin). The total amount of resin components is 100 parts by mass). Preferably, it is comprised from 25-40 mass parts olefin resin component and 75-60 mass parts styrene resin component.
When the amount of the olefin resin component is too large and the amount of the styrene resin component is too small, the mechanical strength such as compression of the base resin may be insufficient. On the other hand, when the amount of the olefin resin component is too small and the amount of the styrene resin component is too large, the chemical resistance and toughness of the base resin may be insufficient.

The composite resin foamed particles are those in which 1 to 15% by mass of the specific halogenated flame retardant containing a secondary or tertiary halide and having a 50% decomposition temperature of 290 to 350 ° C. is blended.
The inclusion of a secondary or tertiary halide in the above halogenated flame retardant generates halogen radicals that capture and stabilize active OH radicals and H radicals that promote the progress of polymer combustion. The flame retardant effect is sufficiently exerted and stable flame retardancy is imparted. Further, when the 50% decomposition temperature is 290 to 350 ° C., in the temperature range in which the thermal decomposition of the expanded foam molded body obtained from the composite resin expanded particles of the present invention having the plurality of resin components as constituents proceeds, A sufficient flame retardant effect of the flame retardant can be exhibited. From the above viewpoint, the 50% decomposition temperature of the halogen flame retardant is preferably 310 to 350 ° C, and more preferably 330 to 350 ° C.

  Moreover, when the compounding quantity of the said halogen-type flame retardant is less than 1 mass%, there exists a possibility that the flame retardance of the foamed particle molded object obtained using the said composite resin foam particle may become inadequate. On the other hand, when it exceeds 15 mass%, the moldability of the composite resin foamed particles may be deteriorated, and the mechanical properties of the obtained foamed particle molded body may be deteriorated. The blending amount of the halogen flame retardant is more preferably 3 to 10% by mass.

The composite resin foamed particles of the present invention are 50 ≦ (BA), where A (° C.) is the 50% decomposition temperature of the halogen flame retardant and B ° C. is the 50% decomposition temperature of the composite resin foam particles. It is preferable that the relationship of ≦ 150 is satisfied (claim 2). More preferably, 50 ≦ (B−A) ≦ 100.
By setting 50 ≦ (B−A) ≦ 150, it is possible to optimize the thermal decomposition timing of the composite resin foam particles and the thermal decomposition of the halogen flame retardant, and the composite resin foam particles are more excellent. It can exhibit flame retardancy. The thermal decomposition temperature of the composite resin foamed particles is mainly determined by the component ratio and type of the olefin resin component and the styrene resin component, and the gel fraction of the composite resin foam particles. It is also somewhat affected by such factors. The thermal decomposition temperature of the composite resin foam particles tends to increase by increasing the gel fraction, which is increased by the olefinic resin component.

  The 50% decomposition temperature of the halogen flame retardant is determined by the type of the halogen flame retardant. Therefore, the type of the halogen-based flame retardant is selected within the range specified in the present invention in accordance with the base resin of the composite resin expanded particles.

  The above-mentioned 50% decomposition temperature is measured with a differential thermothermal gravimetric simultaneous measurement device (TG / DTA) at a rate of temperature increase of 10 ° C./min, a measurement temperature range of 40 ° C. to 500 ° C. in an air atmosphere, sample pan material: Pt This is the temperature at which the differential heat loss curve was measured under the condition of a sample mass of 50 mg and the weight was reduced by 50% in the differential heat loss curve.

  Examples of the halogen-based flame retardant include bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2-bis (4- (2,3-dibromopropoxy) -3. , 5-dibromophenyl) propane, brominated flame retardants such as triallyl isocyanurate hexabromide, bis [3,5-dichloro-4- (2,3-dichloropropoxy) phenyl] sulfone, 2,2-bis (4 Examples include chlorine-based flame retardants such as-(2,3-dichloropropoxy) -3,5-dichlorophenyl) propane and triallyl isocyanurate hexachloride. Preferred is a brominated flame retardant, and particularly preferred is bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone. The above halogen flame retardants may be used alone or in combination of two or more.

  In addition, flame retardant aids such as antimony trioxide and 2,3-dimethyl-2,3-diphenylbutane, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl Non-halogen phosphorus flame retardants such as phosphate, triphenyl phosphate, tricresyl phosphate, tris (chloroethyl) phosphate, tris (dichloropropyl) phosphate, tris (chloropropyl) phosphate, tris (2,3-dibromopropyl) phosphate An appropriate amount of a halogen-containing phosphorus-based flame retardant other than the halogen-based flame retardant such as tris (tribromoneopentyl) phosphate can be used in combination. The flame retardant aid and phosphorus flame retardant may be used alone or in combination with the halogen flame retardant or may be used in combination of two or more.

  In the composite resin foamed particles, the content of the aliphatic hydrocarbon having 3 to 6 carbon atoms is less than 0.1% by mass (including 0% by mass). When the content of the aliphatic hydrocarbon is less than 0.1% by mass (including 0% by mass), in combination with the effect of blending the specific halogen flame retardant, stable flame retardancy is achieved. Can be demonstrated. In addition, it is possible to obtain a foamed particle molded body excellent in the effect of shortening the cooling time at the time of in-mold molding of the composite resin foamed particles and the dimensional stability at the time of curing the foamed particle molded body after in-mold molding.

  Examples of the aliphatic hydrocarbon having 3 to 6 carbon atoms include methane, ethane, propane, normal butane, isobutane, cyclobutane, normal pentane, isopentane, neopentane, cyclopentane, normal hexane, cyclohexane, and a boiling point of 80 ° C. or less. -Methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane and the like.

Next, the composite resin foamed particles may contain a total of 0.5 to 10% by mass of one or more selected from carbon black, graphite, and carbon fiber (hereinafter collectively referred to as “carbon black etc.” as appropriate). (Claim 3).
In this case, the composite resin foamed particles can be colored black. In general, when these carbon blacks are contained, the flame retardancy is lowered. However, the composite resin foam particles contain a specific amount of the specific halogen-based flame retardant, and the composite resin foam particles have 3 carbon atoms. Since the aliphatic hydrocarbon content of ˜6 is adjusted to less than 0.1 mass% (including 0), excellent flame retardancy can be exhibited even if carbon black or the like is contained.

When the content of carbon black is less than 0.5% by mass, the effect of adding carbon black becomes insufficient, and there is a possibility that a sufficient coloring effect cannot be obtained. On the other hand, when it exceeds 10 mass%, there exists a possibility that a flame retardance may fall.
In particular, examples of carbon black include furnace black, channel black, thermal black, acetylene black, and ketjen black.

The composite resin foamed particles are obtained by impregnating the composite resin particles with a physical foaming agent and foaming.
Examples of the physical foaming agent include inorganic physical foaming agents such as carbon dioxide, nitrogen, and air, and organic compounds composed of aliphatic hydrocarbons having 3 to 6 carbon atoms such as butane and pentane as long as the objects and effects of the present invention are not impaired. System physical blowing agents can be used. In addition, it is preferable to use an inorganic physical foaming agent as a physical foaming agent in a range of 50 to 100% by mass with respect to the total amount of the physical foaming agent, and particularly carbon dioxide in a range of 50 to 100% by mass with respect to the total amount of the physical foaming agent. Is preferably used. The composite resin foamed particles of the present invention foam the composite resin particles using the physical foaming agent so that the content of aliphatic hydrocarbons having 3 to 6 carbon atoms is less than 0.1% by mass (including 0). adjust. In order to make the content of the aliphatic hydrocarbon less than 0.1% by mass, it is preferable to use an inorganic physical foaming agent as a physical foaming agent in a range of 50 to 100% by mass with respect to the total physical foaming agent. Even when the composite resin foamed particles are molded by aging for a short time, the content of the combustible aliphatic hydrocarbon remaining in the molded body can be extremely reduced, and stable flame retardancy can be exhibited.

Further, by foaming the composite resin particles impregnated with the inorganic physical foaming agent, the styrene monomer, toluene, xylene and ethylbenzene present in the base resin of the composite resin particles are extracted and removed, and the styrene monomer, toluene, xylene In addition, composite resin foamed particles having a total content of ethylbenzene of 200 ppm or less (including 0) can be obtained . Thereby, the thing which has the further outstanding flame retardance and shows nonflammability can also be obtained. Moreover, a foamed particle molded body suitable as a low VOC vehicle member or building member can be obtained.

The composite resin foamed particles are used to obtain a foamed resin particle molded body (hereinafter referred to as “foamed particle molded body” as appropriate) by filling the molded resin in a molding die and molding in the mold.
The foamed particle molded body can be used for building members, civil engineering members, vehicle members, aviation members, transport members and the like that require flame retardancy. In particular, a black expanded particle molded body containing carbon black or the like is suitable for an automobile member.

The composite resin foamed particles can be produced by performing a reforming step, an impregnation step, and a foaming step.
In the modification step, a styrene monomer in which the halogenated flame retardant is dissolved is added to a suspension in which polyolefin resin particles (hereinafter referred to as “core particles”) are suspended in an aqueous medium. The core particles are then impregnated with the styrenic monomer, and suspension polymerization is performed in the presence of a polymerization initiator. Thereby, the composite resin particle comprised from the olefin resin component and styrene resin component containing a halogenated flame retardant is obtained. A modification step for obtaining composite resin particles employing the above method is preferable from the viewpoint of preventing performance degradation due to the thermal history of the flame retardant, but the halogen flame retardant and polyolefin resin are kneaded in advance. It is also possible to employ a modification step in which composite particles are obtained by impregnating and polymerizing the styrene monomer into the core particles containing the halogenated flame retardant.

Next, in the impregnation step, an inorganic physical foaming agent is impregnated during and / or after the polymerization of the composite resin particles. In the foaming step, the composite resin particles impregnated with the inorganic physical foaming agent are impregnated. Heating and foaming to obtain composite resin foamed particles, or in the impregnation step and the foaming step, the composite resin particles are dispersed together with an inorganic physical foaming agent in a dispersion medium in a pressure resistant container, and the physical foaming is performed. The composite resin particles are impregnated, and the composite resin particles are discharged from the pressure-resistant container in a heat-softened state and foamed to obtain composite resin foam particles.
As a preferable impregnation step and foaming step, the composite resin particles and the physical foaming agent are dispersed in a dispersion medium such as water in a sealed container, and heated under stirring to soften the composite resin particles and to make the composite resin particles physically Impregnate with blowing agent. Thereafter, a softened composite resin particle impregnated with a physical foaming agent is released from the inside of the closed container under a low pressure (usually under atmospheric pressure) and foamed.

In the modification step, the core particles may contain one or more additives selected from carbon black, graphite, carbon fiber, and the like (Claim 6 ). In this case, the black composite resin foamed particles can be obtained as described above.
Further, when the core particles are suspended in the dispersion medium, a suspension agent, a surfactant, a water-soluble polymerization inhibitor, and the like can be added to the dispersion medium.

  As the olefin resin in the core particles, linear low density polyethylene and / or composite resin particles obtained from the viewpoint of the significance of mechanical properties such as compression strength of the foamed particle molded body and / or composite resin obtained From the viewpoint of moldability of the expanded particles, an ethylene-vinyl acetate copolymer is preferably included.

The linear low density polyethylene preferably has a linear polyethylene chain and a short chain branched structure having 2 to 6 carbon atoms.
The density of the linear low density polyethylene is usually from 0.88 to 0.95 g / cm ³ , but from the viewpoint of mechanical properties such as the compression strength of the foamed particle molded body, preferably the density is 0.94 g / cm ³ or less linear low density polyethylene, more preferably be used 0.93 g / cm ³ or less linear low density polyethylene.
Also, the melt mass flow rate (MFR _{190 ° C. 2.16 kgf} ) of the linear low density polyethylene is 1.5 to 4.0 g / 10 minutes, and further 1. The Vicat softening temperature is preferably 80 to 120 ° C, more preferably 90 to 100 ° C, from the viewpoint of stabilizing the particle size of the core particles. The linear low density polyethylene as described above can be obtained as a commercial product.

The ethylene - density vinyl acetate copolymer is generally a 0.90~0.96g / cm ³ or so, foaming, moldability, especially from moldability viewpoint, is 0.95 g / cm ³ or less Preferably, 0.94 g / cm ³ or less is more preferable.
The ethylene-vinyl acetate copolymer generally has a long-chain polyethylene chain branch and a short-chain branch structure derived from vinyl acetate. The content of vinyl acetate (structure ratio derived from vinyl acetate monomer in the copolymer) is usually 1 to 45% by mass, from the viewpoint of impregnation of styrene monomer and graft polymerizability, etc. The thing of 3-20 mass% is preferable, and the thing of 5-15 mass% is more preferable.

The melt mass flow rate (MFR _{190 ° C. 2.16 kgf} ) of the ethylene-vinyl acetate copolymer is 1.5 to 4.0 g / 10 min, and further 2.0 from the viewpoint of extrusion suitability during granulation extrusion of the core particles. The Vicat softening temperature is preferably 60 to 110 ° C., more preferably 60 to 90 ° C., from the viewpoint of stabilizing the particle size of the core particles.
The ethylene-vinyl acetate copolymer as described above can be obtained as a commercial product.

Suitable blending ratio and blending ratio of the resin constituting the core particles are linear low density polyethylene and ethylene-vinyl acetate copolymer of 100 mass% in total, linear low density polyethylene 60-80 mass%, And 20 to 40% by mass of an ethylene-vinyl acetate copolymer.
In addition to the halogen flame retardant, the core particle can contain a bubble adjusting agent, a pigment, a slip agent, an antistatic agent and the like as long as the effects of the present invention are not impaired.

The core particles are preferably produced by appropriately blending the above-described resin, melt-kneading with an extruder or the like, and then finely pulverizing. At this time, in order to uniformly knead the resin, it is preferable to mix each resin component in advance using a mixer such as a Henschel mixer, a ribbon blender, a V blender, or a readye mixer, and then supply the mixture to the extruder.
Further, in producing the composite resin foamed particles and the foamed particle molded body, in order to ensure excellent foam moldability and mechanical properties such as excellent compression of the foamed particle molded body, dispersion in the base resin It is preferable to uniformly disperse the resin additive for controlling the volume average diameter of the phase in the polyolefin resin of the core particles. Therefore, it is preferable to melt-knead using an extruder or a twin-screw extruder provided with a high dispersion type screw such as a dull image type, a Maddock type, or a unimelt type. The dispersion diameter of the resin additive dispersed in the core particles is preferably 10 to 1000 nm, more preferably 10 to 500 nm.

  Examples of the resin additive include acrylonitrile-styrene copolymer, methyl methacrylate-styrene copolymer, polystyrene, rubber-modified polystyrene, ABS resin, AES resin and other styrene resins, SBS, SIS, hydrogenated products thereof, and the like. Examples thereof include vinyl chloride resins such as styrene elastomers, polyvinyl chloride, and polyvinylidene chloride. Moreover, it is preferable that the said resin additive is 1-10 mass parts with respect to 100 mass parts of polyolefin resin, More preferably, 3-7 mass parts is added.

Moreover, it is preferable to add a bubble regulator to the core particles in order to make the bubble diameter of the composite resin expanded particles uniform and fine and to improve the expansion ratio.
Examples of the bubble regulator include inorganic bubble regulators such as talc, calcium carbonate, silica, titanium oxide, gypsum, zeolite, zinc borate, aluminum hydroxide, and carbon, as well as phosphate nucleating agents and phenolic nucleating agents. Organic bubble regulators such as amine nucleating agents can be used. In addition, a bubble regulator can be added individually or in combination of 2 or more types.
The bubble regulator is preferably 3 parts by mass or less, more preferably 1.5 parts by mass or less, still more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass with respect to 100 parts by mass of the core particles. It can be added in the following.

Fine-grained core particles are melt-kneaded with the polyolefin resin constituting the core particles and various additives blended as necessary in the extruder, and then extruded from a porous die attached to the tip of the extruder. Although it can be obtained by pelletizing into small particles by a cut method, a hot cut method, an underwater cut method, etc., other methods may be used as long as a particle having a desired particle diameter and particle mass can be obtained.
From the viewpoint of adjusting the composite resin particles obtained using the core particles to an appropriate size, the average particle diameter is 0.1 to 3.0 mm, and further 0.3 to 1.5 mm. The average mass is preferably 0.000625 to 20 mg / piece, more preferably 0.02 to 2.5 mg / piece.
When adjusting the particle diameter and particle mass by an extruder, for example, extruding from a die provided with holes having a diameter within the range of the particle diameter, adjusting the discharge amount, cutter speed, etc., the target particle diameter And by cutting into length resin particles.

  The polyolefin resin particles (core particles) are usually suspended in a dispersion medium such as water together with a suspending agent. Dispersion in an aqueous medium is usually performed using a polymerization apparatus comprising a pressure vessel equipped with a stirrer. Examples of the aqueous medium include deionized water.

  Examples of the suspension include tricalcium phosphate, hydroxyapatite, magnesium pyrophosphate, magnesium phosphate, aluminum hydroxide, ferric hydroxide, titanium hydroxide, magnesium hydroxide, barium phosphate, calcium carbonate, magnesium carbonate. Fine particulate inorganic suspending agents such as barium carbonate, calcium sulfate, barium sulfate, talc, kaolin and bentonite can be used. Moreover, organic suspending agents such as polyvinyl pyrrolidone, polyvinyl alcohol, ethyl cellulose, and hydroxypropyl methyl cellulose can also be used. Preferred are tricalcium phosphate, hydroxyapatite, and magnesium pyrophosphate. These suspending agents may be used alone or in combination of two or more.

  The amount of the suspending agent used in the suspension polymerization is 100 parts by mass with respect to 100 parts by mass of the aqueous medium of the suspension polymerization system (referring to all water in the system including water such as the reaction product-containing slurry). Usually, the solid content is 0.05 to 10 parts by mass, preferably 0.3 to 5 parts by mass. If the amount is less than 0.05 parts by mass, the styrene monomer cannot be suspended and stabilized, and a lump of resin may be generated. If the amount exceeds 10 parts by mass, it is not preferable from the viewpoint of production cost. However, the problem that the particle size distribution becomes wide is likely to occur.

  Examples of the surfactant added to the dispersion medium as described above include anionic interfaces such as sodium alkyl sulfonate, sodium alkylbenzene sulfonate, sodium lauryl sulfate, sodium α-olefin sulfonate, sodium dodecylphenyl oxide disulfonate, and the like. Activators: Nonionic surfactants such as polyoxyethylene dodecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether; alkylamine salts such as coconut amine acetate and stearylamine cetate, lauryltrimethylammonium chloride, stearyl Cationic surfactants such as quaternary ammonium such as trimethylammonium chloride; alkyls such as lauryl betaine and stearyl betaine Amphoteric surfactants such as alkyl amine oxides, such as tines or lauryl dimethylamine oxide. An anionic surfactant is preferable. More preferably, it is an alkylsulfonic acid alkali metal salt (preferably sodium salt) having 8 to 20 carbon atoms. Thereby, the effect of the outstanding suspension stabilization is acquired.

  Further, if necessary, in order to adjust the number of voids in the composite resin particles described later, for example, sodium acetate, lithium chloride, potassium chloride, sodium chloride, sodium sulfate, sodium nitrate, sodium carbonate, sodium bicarbonate, etc. An electrolyte composed of an inorganic salt or the like is usually added in a solid content of 0.01 with respect to 100 parts by mass of a suspension polymerization aqueous medium (referring to all water in the system including water such as a reaction product-containing slurry). -0.5 parts by weight, preferably 0.05-0.2 parts by weight can be added.

In addition, in order to obtain a foamed particle molded body that is tenacious and excellent in bending and compressive strength by molding the composite resin foam particles in a mold, water-soluble polymerization is performed in a dispersion medium composed of an aqueous medium in which the core particles are suspended. It is preferable to add an inhibitor.
Examples of the water-soluble polymerization inhibitor include sodium nitrite, potassium nitrite, ammonium nitrite, L-ascorbic acid, citric acid and the like.

  As the water-soluble polymerization inhibitor, it is possible to employ a water-soluble polymerization inhibitor that does not easily impregnate into the core particles and dissolves in an aqueous medium. In this case, polymerization of the styrenic monomer impregnated in the core particles is performed, but near the particle surface being absorbed by the styrene monomer microdroplets or the core particles in the aqueous medium not absorbed by the core particles. Polymerization of the styrene monomer can be suppressed. As a result, it is surmised that the surface portion of the obtained composite resin particles has a smaller amount of polystyrene-based resin component than the center portion of the particles.

  The addition amount of the water-soluble polymerization inhibitor is 0.001 to 0.1 parts by mass with respect to 100 parts by mass of an aqueous medium (referring to all water in the system including water such as reaction product-containing slurry), preferably 0.002 to 0.02 parts by mass. If it exceeds 0.1 parts by mass, there is a possibility that good composite resin foamed particles and foamed particle molded bodies cannot be obtained due to an increase in the residual styrene-based monomer.

As described above, the styrenic monomer is one or more of a styrene monomer and a monomer component copolymerizable with the styrene monomer. Examples of the monomer component copolymerizable with the styrene monomer include monomer components such as butyl acrylate copolymerizable with the styrene monomer.
When a monomer other than a styrene monomer is used during suspension polymerization using core particles, the ratio of the styrene monomer in the mixed monomer of the styrene monomer and the monomer other than the styrene monomer is based on the total monomers. Preferably, it is 50 mass% or more, More preferably, it is 80 mass% or more, More preferably, it is 90 mass% or more.

  As a preferable mixed monomer, styrene and butyl acrylate can be used. In this case, butyl acrylate is preferably contained in an amount of 0.5 to 10% by mass, more preferably 1 to 8% by mass, and particularly preferably 2 to 5% by mass with respect to the entire composite resin particle from the viewpoint of high foamability.

In order to uniformly polymerize the styrene monomer in the core particle, it is preferable to polymerize the core particle by impregnating the styrene monomer or a mixed monomer thereof. When the core particles are impregnated and polymerized, crosslinking occurs with polymerization. For the polymerization, a polymerization initiator and, if necessary, a crosslinking agent are used. The polymerization initiator and / or crosslinking agent is preferably dissolved in advance in a styrene monomer or a mixed monomer thereof.
In the polymerization process of the monomer, the olefin-based resin may be cross-linked. In the present specification, “polymerization” may include “cross-linking”.

  In addition, the halogen-based flame retardant is dissolved in the styrene-based monomer. In addition to the halogen-based flame retardant, glycerin tristearate, glycerin trioctate, glycerin trilaurate, sorbitan tristearate may be used as necessary. Rate, fatty acid esters such as sorbitan monostearate, butyl stearate, acetylated monoglycerides such as glycerin diacetomonolaurate, fats and oils such as hardened beef tallow and hardened castor oil, plasticizer materials such as organic compounds such as cyclohexane and liquid paraffin, Oil-soluble polymerization inhibitors such as para-t-butylcatechol, hydroquinone, and benzoquinone can be added.

  The polymerization initiator is not particularly limited as long as it is used in the suspension polymerization method of a styrene monomer. For example, the polymerization initiator is soluble in a vinyl monomer and has a 10-hour half-life temperature of 50 to 120 ° C. Cumene hydroxy peroxide, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2- Organic peroxides such as ethyl hexyl carbonate, hexyl peroxy-2-ethyl hexyl carbonate, lauroyl peroxide, and benzoyl peroxide, and azo compounds such as azobisisobutyronitrile can be used. These polymerization initiators can be used alone or in combination of two or more.

Although the usage-amount of a polymerization initiator changes with kinds of polymerization initiator, 0.01-3 mass parts is preferable with respect to 100 mass parts of styrene-type monomers or its mixed monomer.
A preferred crosslinking agent is one that does not decompose at the polymerization temperature but decomposes at the crosslinking temperature. Examples thereof include peroxides such as dicumyl peroxide, 2,5-t-butyl perbenzoate, 1,1-bis-t-butyl peroxycyclohexane, and these are used alone or in combination of two or more. . It is preferable that the compounding quantity of a crosslinking agent is 0.1-5 mass% with respect to a styrene-type monomer or its mixed monomer. The polymerization initiator and the crosslinking agent can be the same compound.

  In addition, bubbles are adjusted for methyl methacrylate copolymers, aliphatic monoamides such as polyethylene wax, oleic acid amide and stearic acid amide, fatty acid bisamides such as methylene bisstearic acid and ethylene bisstearic acid amide, talc, silica and silicone. As an agent, it can be used by dissolving in a styrene monomer or a mixed monomer thereof. In this case, it is preferable to use 0.01 to 2 parts by mass with respect to 100 parts by mass of the styrene monomer or a mixed monomer thereof.

Addition of the styrenic monomer or a mixed monomer thereof (including a polymerization initiator and / or a crosslinking agent as necessary) to the suspension may be performed all at once or separately.
Moreover, although superposition | polymerization temperature changes with kinds of polymerization initiator to be used, 60-105 degreeC is preferable. Moreover, although a crosslinking temperature changes with kinds of crosslinking agent to be used, 100-150 degreeC is preferable.

For the method of producing the composite resin expanded particles, for example, known foaming methods described in JP-B-49-2183, JP-B-56-1344, JP-B-62-61227 and the like are referred to. be able to.
In the foaming step for obtaining composite resin foam particles preferably exemplified, when the contents in the sealed container are released from the sealed container to the low pressure region, the contents are sealed with the used physical foaming agent or an inorganic gas such as nitrogen or air. It is preferable to discharge the contents in such a manner that back pressure is applied to the container so that the pressure in the container does not drop rapidly. In this case, the apparent density of the resulting composite resin foamed particles can be made more uniform.

  As the physical foaming agent, an inorganic physical foaming agent is preferably used. The inorganic physical foaming agent has a heat insulation coefficient of 1.1 to 1.7 as a ratio of its constant pressure molar specific heat (Cp) and constant volume molar specific heat (Cv), and a gas body that can be used as a gas is used. it can. Specific examples include nitrogen, carbon dioxide, argon, air, helium, water, and the like, and a mixture of two or more of these may be used. Among inorganic physical foaming agents, carbon dioxide is preferable. In addition, when obtaining the composite resin foamed particles, if water is used as a dispersion medium together with the composite resin particles in a sealed container, a mixture of the composite resin particles with a water absorbent resin or the like should be used. Therefore, when water is used as a dispersion medium, water can also be used as a foaming agent.

  As the physical foaming agent, as described above, a physical foaming agent containing an aliphatic hydrocarbon having 3 to 6 carbon atoms can also be used. Specific examples of such aliphatic hydrocarbons are as described above.

  The amount of the physical foaming agent used is determined in consideration of the apparent density of the target composite resin foamed particles, the composition of the base resin, the type of physical foaming agent, and the like. In general, it is preferable to use 0.5 to 30 parts by mass of a physical foaming agent per 100 parts by mass of the composite resin particles.

  The composite resin foam particles obtained by the above method can be subjected to a normal curing step under atmospheric pressure. Next, after adjusting the pressure in the composite resin foamed particles to 0.01 to 0.6 MPa (G) by pressurizing with a pressurized gas such as air filled in a pressurized airtight container as necessary, The composite resin foam particles are taken out from the container and heated using saturated water vapor, hot air, a mixture of saturated water vapor and air, hot water, or the like. Thereby, it can be set as the composite resin foaming particle whose apparent density is lower (this process may be called two-stage foaming hereafter).

In the production of the composite resin foam particles, as a dispersion medium for dispersing the composite resin particles, a dispersion medium that does not dissolve the composite resin particles can be used. As such a dispersion medium, for example, ethylene glycol, glycerin, methanol, ethanol and the like can be used, but water is preferably used.
In the dispersion medium, if necessary, a poorly water-soluble inorganic substance such as aluminum oxide, tricalcium phosphate, magnesium pyrophosphate, zinc oxide, and kaolin so that the composite resin particles are uniformly dispersed in the dispersion medium. It is preferable to disperse a dispersing aid such as a dispersing agent such as a substance and an anionic surfactant such as sodium dodecylbenzenesulfonate and sodium alkanesulfonate.

The amount of the dispersant added to the dispersion medium when producing the composite resin foam particles can be determined based on the mass of the composite resin particles, and the mass of the composite resin particles and the mass of the dispersant The ratio (mass of composite resin particles / mass of dispersant) is preferably 20 to 2000, and more preferably 30 to 1000.
The ratio of the mass of the dispersant to the mass of the dispersion aid (the mass of the dispersant / the mass of the dispersion aid) is preferably 0.1 to 500, and more preferably 1 to 50.

The composite resin foamed particles preferably have an apparent density of 10 to 500 kg / m ³ and an average cell diameter of 50 to 500 μm. More preferably, the average cell diameter is 80 to 300 μm, and more preferably 100 to 250 μm.
When the average bubble diameter is less than 50 μm, although depending on the apparent density of the expanded particles, the thickness of the bubble film constituting the bubbles tends to be small. And depending on the morphology of the base resin, when the base resin is a modified resin in which a dispersed phase mainly composed of a styrene resin is dispersed in a continuous phase mainly composed of an olefin resin, The probability that the styrene-based resin is exposed on the surface of the cell membrane is increased. When the styrenic resin is exposed, foam breakage is likely to occur due to heating during molding of the foamed particles. This tendency becomes more prominent as the expanded particles have a higher expansion ratio. When the expanded particles have a low expansion ratio, molding may be possible even if the average cell diameter is less than 50 μm. However, in order to stabilize the mold transfer performance, the average cell diameter is low even at a low expansion ratio. It is preferable that it is 50 micrometers or more.
On the other hand, when the average cell diameter exceeds 500 μm, the strength of the resulting modified resin foamed particle molded body may be reduced, or the flame retardancy may be deteriorated.

  The apparent density can be controlled, for example, by adjusting the composition of the base resin, foaming conditions (temperature, pressure), the amount of foaming agent, and the like.

  In addition, the average cell diameter of the composite resin foamed particles is comprehensively determined based on the foaming temperature, the amount of impregnation of the physical foaming agent, the number of voids in the composite resin particles, and the type and amount of the air conditioner dispersed in the core particles. It can be controlled by adjusting. For example, setting the foaming temperature high basically acts in the direction of increasing the bubble diameter, and increasing the amount of impregnation of the physical foaming agent acts in the direction of decreasing the bubble diameter. Further, the smaller the number of voids in the composite resin particles, the larger the bubbles tend to be, but the foaming ratio tends to be smaller. On the other hand, when the number of voids increases, it becomes easy to obtain composite resin foam particles having a high expansion ratio, but the bubbles tend to be fine. With respect to the bubble regulator added to the core particles, the bubbles tend to become finer when the amount added is increased.

The average cell diameter of the composite resin expanded particles can be measured as follows.
First, the composite resin foam particles are roughly divided into two parts, and a photograph of the cut surface is taken with a scanning electron microscope. In the obtained cross-sectional photograph, draw straight lines at equal intervals in the eight directions from the vicinity of the center of the foamed particle cut surface, count all the number of bubbles intersecting the straight line, the total length of the straight line is the number of counted bubbles The value obtained by dividing is taken as the cell diameter of the expanded particles. This operation is performed for a large number (at least 30 or more) of foamed particles, and the arithmetic average value of the bubble diameters of the foamed particles is defined as the average bubble diameter. In the measurement of the bubble diameter of each expanded particle, the bubbles that intersect even part of the straight line are counted. Further, in the above measurement, the reason why the straight lines are drawn at equal intervals in the eight directions from the vicinity of the center of the expanded surface of the foamed particle is measured if the straight lines are drawn at equal intervals in the eight directions from the vicinity of the center of the expanded surface of the expanded particle. This is because even if the shape of the bubbles to be generated varies depending on the direction on the cut surface of the expanded particles, an average value of the bubble diameter can be stably obtained.

In this example, composite resin foamed particles are manufactured by performing a reforming step, an impregnation step, and a foaming step.
In the reforming step, a styrene monomer in which a halogen-based flame retardant is dissolved is added to a suspension in which polyolefin resin particles (core particles) are suspended in an aqueous medium, and the styrene monomer is nucleated. The particles are impregnated and subjected to suspension polymerization in the presence of a polymerization initiator to obtain composite resin particles containing a halogen-based flame retardant and composed of an olefin resin component and a styrene resin component.
In the impregnation step and the foaming step, the composite resin particles are dispersed together with a physical foaming agent in a dispersion medium in a pressure resistant container, impregnated with the physical foaming agent, and the composite resin particles are heated and softened in a high temperature and high pressure resistance. The composite resin foam particles are obtained by discharging from the container to the low pressure region and foaming.
Examples of the present invention and comparative examples will be described in detail below.

Example 1
(1) Production of polyolefin resin particles (core particles) 5 kg of ethylene-vinyl acetate copolymer (“Ultrasen 626” manufactured by Tosoh Corporation) containing 15% by mass of vinyl acetate, linear low density polyethylene resin (Tosoh Corporation) "Nipolon 9P51A" 15 kg, 0.144 kg of zinc borate as a foam regulator, and carbon black ("Black SPEMD-8A1615HCAL-K (master batch containing 40% furnace black)" manufactured by Sumika Color Co., Ltd.) 7 kg was put into a Henschel mixer (Mitsui Miike Chemical Co., Ltd .; Model FM-75E) and mixed for 5 minutes.
Next, this resin mixture was melted and kneaded at 230 to 250 ° C. in an extruder (manufactured by Icage; model MS50-28; 50 mmφ single screw extruder, Maddock type screw), and 0.4 to 0.6 mg by an underwater cutting method. / Piece (average 0.5 mg / piece) to obtain polyethylene resin particles (core particles).

(2) Preparation of composite resin particles composed of an olefin resin component containing a halogen-based flame retardant and a styrene resin component 1000 g of deionized water is placed in an autoclave with a 3 L internal volume equipped with a stirrer. After 6.0 g of sodium pyrophosphate was added and dissolved, 12.9 g of powdered magnesium nitrate hexahydrate was added and stirred at room temperature for 30 minutes to synthesize a magnesium pyrophosphate slurry as a suspending agent.
After synthesizing the magnesium pyrophosphate slurry, 1.0 g of sodium lauryl sulfonate (10% by mass aqueous solution) as a surfactant, 0.5 g of sodium nitrite as a water-soluble polymerization inhibitor, and the above nucleus were added to the reaction product slurry. 150 g of particles were charged.

  Next, 1.75 g of t-butylperoxy-2-ethylhexanoate (“Perbutyl O” manufactured by NOF Corporation) and 4.2 g of t-butylperoxy-2-ethylhexyl monocarbonate (NOF Corporation) as polymerization initiators “Perbutyl E”), 0.14 g of dicumyl peroxide (Nippon Yushi Co., Ltd. “Park Mill D”), and bis [3,5-dibromo-4- (2) as a halogen flame retardant , 3-dibromopropoxy) phenyl] sulfone (Suzuhiro Chemical Co., Ltd. “Firecut P-65CN (FCP-65CN)”; 50% decomposition temperature 336 ° C.) 25 g, styrene 335 g and butyl acrylate as a styrenic monomer It was dissolved in 15 g and charged into the autoclave while stirring at 500 rpm.

  Next, after the inside of the autoclave was purged with nitrogen, the temperature was raised and the temperature was raised to 80 ° C. over 1 hour and a half. After the temperature increase, this temperature was maintained at 80 ° C. for 30 minutes, and then the stirring speed was lowered to 450 rpm. After the stirring speed was lowered, this temperature was maintained at 80 ° C. for 11 hours and 30 minutes. Next, the temperature was raised to 125 ° C. over 2 hours, and kept at this temperature of 125 ° C. for 2 hours and 30 minutes. Then, it cooled over about 6 hours to the temperature of 30 degreeC.

  After cooling, the contents were taken out and nitric acid was added to dissolve the magnesium pyrophosphate adhering to the surface of the composite resin particles. After that, it is dehydrated and washed with a centrifugal separator, and water adhering to the surface is removed with an air flow dryer. Black composite resin particles having an average particle diameter (d63) of about 1.5 mm (30 parts by mass of an olefin resin component) And composite resin particles containing a halogen-based flame retardant composed of 70 parts by mass of a styrene resin component.

Next, the 50% decomposition temperature of the obtained composite resin particles and the halogen-based flame retardant used for the production thereof was measured.
Specifically, about 10 mg each of the composite resin particles and the halogen-based flame retardant are weighed and thermogravimetric analysis (TG / DTA6200) made by Seiko Instruments Inc. is used. The temperature when the weight decreased by 50% was obtained from the differential heat loss curve obtained by the temperature increase rate of 10 ° C./min, the measurement temperature range of 40 ° C. to 500 ° C., in an air atmosphere, and the material of the sample pan: Pt). Was taken as the 50% decomposition temperature. The results are shown in Table 1 below.

(3) Production of Composite Resin Foamed Particles 1 kg of composite resin particles produced as described above was charged into 3.5 liter (L) of water as a dispersion medium and a 5 L sealed container (pressure vessel) equipped with a stirrer. Then, 5 g of kaolin as a dispersant and 0.6 g of sodium alkylbenzene sulfonate as a surfactant were added to the dispersion medium.
Next, 4 parts by mass of carbon dioxide as a blowing agent is injected into 100 parts by mass of the composite resin particles in a sealed container while stirring at a rotation speed of 300 rpm, and the temperature is increased to an impregnation temperature of 165 ° C. with stirring. For 20 minutes. Thereafter, by releasing the contents under atmospheric pressure, black composite resin foam particles having an apparent density of 53.3 kg / m ³ (from 30 parts by mass of the olefin resin component and 70 parts by mass of the styrene resin component). A composite resin foamed particle containing a halogenated flame retardant was obtained.

  The 50% decomposition temperature of the obtained composite resin expanded particles was measured by the same method as the measurement of the 50% decomposition temperature of the composite resin particles described above. The results are shown in Table 1 below.

  About the composite resin foamed particles thus obtained, the content (mass%) of carbon black, the type and amount of the foaming agent and halogen-based flame retardant used for preparation, 50% decomposition temperature A of the halogen-based flame retardant, Presence or absence of secondary or tertiary halide in halogenated flame retardant, type of base resin, 50% decomposition temperature of composite resin particles, content of aliphatic hydrocarbon having 3 to 6 carbon atoms (butane in this embodiment) ( Mass%), total content of styrene monomer, toluene, xylene and ethylbenzene (aromatic hydrocarbon content) (ppm), 50% decomposition temperature B of expanded particles, 50% decomposition of expanded particles and halogen flame retardant The temperature difference B-A is shown in Table 1 described later. In Table 1, “PE” in the column of the type of base resin indicates “polyethylene”, and “PS” indicates “polystyrene”.

(4) Production of foamed particle molded body Next, a foamed particle molded body was produced using the composite resin foamed particles produced as described above.
Specifically, first, composite resin foamed particles (apparent density was 53.3 kg / m ³ ) were aged at a temperature of 23 ° C. for 1 day. Then, it was put into a molding machine (VS-500 manufactured by Daisen Kogyo Co., Ltd .; mold dimensions were 300 × 75 × 25 mm) and molded. Thereby, a foamed particle molded body was obtained.

Next, the content (mass%) of the C3-C6 aliphatic hydrocarbon (butane in this example) in the foamed particle molded body was measured.
The measurement of the aliphatic hydrocarbon content of 3 to 6 carbon atoms of the composite resin foamed particles and the foamed particle molded body was performed as follows.
23 was aged for one day at ° C., the composite resin foamed particles (apparent density of 53.3kg / m ^3, a bulk density of 33.3 kg / m ³⁾ and PP bead molding (bulk density 33.3 kg / m ³⁾ About 1 g of a sample piece was weighed, and this sample piece was dissolved in 25 ml of dimethylformamide, and the content of an aliphatic hydrocarbon having 3 to 6 carbon atoms (butane in this example) was measured by gas chromatography. . The results are shown in Table 1 below.
The specific measurement conditions for gas chromatography are as follows.
Equipment used: Gas chromatograph GC-8A manufactured by Shimadzu Corporation, column filler: [Liquid phase name] DOP-B, [Liquid phase impregnation rate] 30% by weight, [Carrier particle size] 60/80 mesh, carrier treatment Method], column material: glass column having an inner diameter of 3 mm and a length of 4000 mm, carrier gas: N2, detector: FID (hydrogen flame ionization detector), quantification: internal standard method.

Moreover, the amount (ppm) of aromatic hydrocarbons in the composite resin foamed particles and the foamed particle molded body was measured.
Measurement of the total content (aromatic hydrocarbon content) of styrene monomer, toluene, xylene, and ethylbenzene of the resin foam particles and the above-mentioned foamed particle molded body was performed as follows.
Approximately 1 g of a sample piece is weighed from the composite resin foam particles (apparent density is 53.3 kg / m ³ , bulk density is 33.3 kg / m ³ ) and foam particle compact (bulk density is 33.3 kg / m ³ ). The sample piece was dissolved in 25 ml of dimethylformamide, and the respective contents of styrene monomer, toluene, xylene, and ethylbenzene were measured by gas chromatography, and the total amount thereof was defined as the aromatic hydrocarbon content. The results are shown in Table 1 below.
The specific measurement conditions for gas chromatography are as follows.
Equipment used: Gas chromatograph GC-9A manufactured by Shimadzu Corporation, column filler: [liquid phase name] PEG-20M, [liquid phase impregnation rate] 25% by weight, [carrier particle size] 60/80 mesh, carrier treatment Method], column material: glass column with an inner diameter of 3 mm and a length of 3000 mm, carrier gas: N2, detector: FID (hydrogen flame ionization detector), quantification: internal standard method.

Moreover, about the foamed particle molded object, the combustion rate was measured according to the combustion test of FMVSS 302, and the flame retardance was evaluated according to the following criteria.
That is, the case where the burning speed was 80 mm / min or less was evaluated as “◎”, the case where it exceeded 80 mm / min but 100 mm / min or less was evaluated as “◯”, and the case where it exceeded 100 mm / min was evaluated as “x”. The results are shown in Table 1 below. In Table 1, the numbers in parentheses next to the evaluation results of flame retardancy indicate the burning rate (mm / min). Marked as fire extinguishing.

Moreover, the cooling time at the time of shaping | molding at the time of obtaining a foamed-particles molded object by in-mold shaping | molding from composite resin foamed particles was measured.
Specifically, after the composite resin foam particles were aged at 23 ° C. for one day, a foam particle molded body having a diameter of 300 mm and a thickness of 50 mm was molded by a mold molding machine (manufactured by Erlenbach). The in-mold molding conditions were: heating for 20 seconds at a steam pressure of 0.07 MPa, water cooling for 5 seconds, and then allowing to cool in a vacuum at a reduced pressure of -0.08 MPa, and the surface pressure gauge was adjusted to 0.00 MPa (gauge pressure). When it reached, the mold was opened and the foamed particle molded body was released. Then, the cooling time (seconds) required from the start of pressure reduction of the mold cavity until the surface pressure reached 0.00 MPa (gauge pressure) was measured, and this was taken as the molding cycle (seconds). The results are shown in Table 1 below.

Further, the compression strength (MPa) of the foamed particle molded body was measured.
Specifically, a test piece having a length of 50 mm, a width of 50 mm, and a thickness of 25 mm was cut out from a foamed particle molded body having dimensions of 300 mm × 75 mm × 25 mm and subjected to a compression test according to JIS K 7220 (2006). The compressive stress when the compressive strain is 10% is 10% compressive stress, and the compressive stress when the compressive strain is 50% is 50% compressive stress.

Moreover, the dimensional stability of the foamed particle molded body was evaluated.
Specifically, first, composite resin expanded particles aged at a temperature of 23 ° C. for 1 day and composite resin expanded particles aged at a temperature of 23 ° C. for 30 days were prepared.
Next, two types of composite resin expanded particles having different aging conditions were molded in-mold using a molding machine (VS-500 manufactured by Daisen Kogyo Co., Ltd .; mold dimensions were 300 × 75 × 25 mm), and dimensions 300 mm × 75 mm × A 25 mm expanded particle molded body was obtained. As a result, “foamed particle molded body produced using composite resin foam particles aged at 23 ° C. for 1 day” and “foamed particle molded body produced using composite resin foam particles aged at 23 ° C. for 30 days”. Got a "body".
Next, the lengthwise direction (direction of 300 mm in length) of each expanded particle molded body was measured, and the expanded particle molded body was allowed to stand at a temperature of 60 ° C. for 3 hours, and then allowed to stand at a temperature of 23 ° C. for 60 days. Thereafter, the lengthwise direction was measured again, the dimensional change rate when left at a temperature of 23 ° C. for 60 days was determined, and the dimensional stability was evaluated according to the following criteria.
“Dimensional change rate of foamed particle molded body produced using composite resin foam particles aged at 23 ° C. for 30 days” / “Expanded particles produced using composite resin foam particles aged at 23 ° C. for 1 day The case where the “dimensional change rate of the molded body” was 1.5 or less was evaluated as “◯”, and the case where it exceeded 1.5 was evaluated as “×”. The results are shown in Table 1 below.

( Comparative Example 7)
In this example, 2,2-bis (4- (2,3-dibromopropoxy) -3,5-dibromophenyl) propane (Suzuhiro Chemical Co., Ltd. “Firecut P-680G (FCP- 680 G) ”; 50% decomposition temperature 324 ° C.) Except for the use of 25 g, composite resin foam particles and foam particle molded bodies using the same were prepared in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 1 below.

( Comparative Example 8 )
In this example, except that 25 g of triallyl isocyanurate hexabromide (“Fire Cut P-660CN (FCP-660CN)”; 50% decomposition temperature 326 ° C.) manufactured by Suzuhiro Chemical Co., Ltd. was used as a halogenated flame retardant. Produced composite resin foamed particles and a foamed particle molded body using the same in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 1 below.

(Example 4)
In this example, as a halogenated flame retardant, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone ("Fire Cut P-65CN" manufactured by Suzuhiro Chemical Co., Ltd.); 50% decomposition temperature Except for using 12.5 g (336 ° C.), composite resin expanded particles and expanded particle molded bodies using the same were prepared in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 1 below.

(Example 5)
In this example, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (“Firecut P-65CN” manufactured by Suzuhiro Chemical Co., Ltd.); 50% decomposition temperature 336 as a halogenated flame retardant C.) Except for the point of using 50 g, composite resin expanded particles and expanded particle molded bodies using the same were prepared in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 1 below.

(Example 6)
In this example, at the time of preparation of the core particles, 5 kg of an ethylene-vinyl acetate copolymer (“Ultrasen 626” manufactured by Tosoh Corporation) containing 15% by mass of vinyl acetate, a linear low density polyethylene resin (“Tosoh Corporation” Nipolon 9P51A ") 15 kg, 0.157 kg of zinc borate as a foam regulator, and carbon black (" Black SPEMD-8A1615HCAL-K (master batch containing 40% furnace black) "manufactured by Sumika Color Co., Ltd.)) 5.88 kg A polyethylene resin particle (core particle) prepared by mixing in a Henschel mixer (Mitsui Miike Kako Co., Ltd .; Model FM-75E) and mixed for 5 minutes was used as a flame retardant for composite resin particles. 5-Dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (“Suzuhiro Chemical Co., Ltd.“ Firecut P- 65CN ”; 50% decomposition temperature 336 ° C.) Except for the use of 50 g, composite resin expanded particles and expanded particle molded bodies were produced in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 1 below.

(Example 7)
In this example, when producing the core particles, first, 5 kg of an ethylene-vinyl acetate copolymer (“Ultrasen 626” manufactured by Tosoh Corporation) containing 15% by mass of vinyl acetate, a linear low density polyethylene resin (Tosoh Corporation) "Nipolone 9P51A") 15 kg, 0.137 kg of zinc borate as a foam regulator, and carbon black ("Black SPEMD-8A1615HCAL-K (master batch containing 40% furnace black)" manufactured by Sumika Color Co., Ltd.) 85 kg of a composite resin foamed particle is obtained in the same manner as in Example 1 except that core particles prepared by mixing for 5 minutes are used in a Henschel mixer (manufactured by Mitsui Miike Chemical Co., Ltd .; model FM-75E). And the foaming particle molded object was produced. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 1 below.

(Example 8)
In this example, at the time of preparation of the core particles, 5 kg of an ethylene-vinyl acetate copolymer (“Ultrasen 626” manufactured by Tosoh Corporation) containing 15% by mass of vinyl acetate, a linear low density polyethylene resin (“Tosoh Corporation” Nipolon 9P51A ") 15 kg, 0.157 kg of zinc borate as a foam regulator, and carbon black (" Black SPEMD-8A1615HCAL-K (master batch containing 40% furnace black) "manufactured by Sumika Color Co., Ltd.)) 5.88 kg A polyethylene resin particle (core particle) prepared by mixing in a Henschel mixer (Mitsui Miike Kako Co., Ltd .; Model FM-75E) and mixed for 5 minutes was used as a flame retardant for composite resin particles. 5-Dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (“Suzuhiro Chemical Co., Ltd.“ Firecut P- 65CN ”; 50% decomposition temperature 336 ° C.) Except for the use of 17.5 g, composite resin expanded particles and expanded particle molded bodies using the same were prepared in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

Example 9
In this example, as in Example 1, except that 0.42 g of t-butyl peroxy-2-ethylhexyl monocarbonate (“Perbutyl E” manufactured by NOF Corporation) was used as the polymerization initiator. Composite resin foam particles and foam particle molded bodies using the same were produced. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

(Example 10)
In this example, with respect to 100 parts by weight of the composite resin particles, as a blowing agent, carbon dioxide 4 parts by weight of butane was used (normal butane about 20 wt% isobutane mixture of about 80 wt%) 0.5 parts by weight Except for the points, composite resin expanded particles and expanded particle molded bodies using the same were prepared in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

(Example 11)
In this example, core particles were prepared without using carbon black, and bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (Suzuhiro Kagaku “Fire Cut” was used as a flame retardant. P-65CN ”; 50% decomposition temperature 336 ° C.) Except for the use of 5 g, composite resin expanded particles and expanded particle molded bodies were produced in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

(Example 12)
In this example, the core particles prepared without the use of carbon black, when making the composite resin foamed particles, the halogen-based flame retardant, 2, 2- bis (4- (2,3-dibromo-2-methylpropoxy ) -3,5-dibromophenyl) propane (“SR130” manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; 50% decomposition temperature 297 ° C.) 5 g was used in the same manner as in Example 1 except that 5 g were used. A foamed particle molded body was produced. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

(Example 13)
In this example, core particles were prepared without using carbon black, core particles 125 g, sodium nitrite 1.5 g as a water-soluble polymerization inhibitor, styrene 360 g and butyl acrylate 15 g as a styrenic monomer, flame retardant Except that 10 g of bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (Suzuhiro Chemical Co., Ltd. “Firecut P-65CN”; 50% decomposition temperature 336 ° C.) was used. In the same manner as in Example 1, composite resin foamed particles and foamed particle molded bodies were produced. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

(Example 14)
In this example, at the time of preparation of the core particles, 5 kg of an ethylene-vinyl acetate copolymer (“Ultrasen 626” manufactured by Tosoh Corporation) containing 15% by mass of vinyl acetate, a linear low density polyethylene resin (“Tosoh Corporation” Nipolon 9P51A ") 15 kg, 0.157 kg of zinc borate as a foam regulator, and carbon black (" Black SPEMD-8A1615HCAL-K (master batch containing 40% furnace black) "manufactured by Sumika Color Co., Ltd.)) 5.88 kg Using polyethylene resin particles (core particles) prepared by mixing in a Henschel mixer (made by Mitsui Miike Chemical Industry Co., Ltd .; Model FM-75E) for 5 minutes, 100 g of core particles, nitrous acid as a water-soluble polymerization inhibitor 5.0 g of sodium, 385 g of styrene as a styrenic monomer and 15 g of butyl acrylate, Point of using 50 g of bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (“Firecut P-65CN” manufactured by Suzuhiro Chemical Co., Ltd .; 50% decomposition temperature 336 ° C.) as a flame retardant Except for, composite resin foamed particles and foamed particle molded bodies were produced in the same manner as in Example 1. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

(Example 15)
In this example, at the time of preparation of the core particles, 5 kg of an ethylene-vinyl acetate copolymer (“Ultrasen 626” manufactured by Tosoh Corporation) containing 15% by mass of vinyl acetate, a linear low density polyethylene resin (“Tosoh Corporation” Nipolon 9P51A ”) 15 kg, 0.036 kg of zinc borate as a foam regulator, and carbon black (“ Black SPEMD-8A1615HCAL-K (master batch containing furnace black 40%) ”manufactured by Sumika Color Co., Ltd.)) 2.7 kg Put into a Henschel mixer (Mitsui Miike Kako Co., Ltd .; Model FM-75E) and use polyethylene resin particles (nuclear particles) prepared by mixing for 5 minutes, and when preparing composite resin particles, halogenated flame retardant As bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (manufactured by Suzuhiro Chemical Co., Ltd.) A composite resin foam particle and a foamed particle molded body were produced in the same manner as in Example 1 except that 50 g of “Fire Cut P-65CN”; 50% decomposition temperature 336 ° C.) was used. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 2 below.

(Comparative Example 1)
In this example, the same procedure as in Example 1 was conducted except that 25 g of polypentabromobenzyl acrylate (“FR-1025” manufactured by ICL-IP JAPAN; 50% decomposition temperature 367 ° C.) was used as a flame retardant. Composite resin foam particles and foam particle molded bodies were produced. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 3 below.

(Comparative Example 2)
In this example, except that 25 g of ethylene bispentabromobenzene (“Fire Cut P-801 (FCP-801)” manufactured by Suzuhiro Chemical Co., Ltd .; 50% decomposition temperature 431 ° C.) 25 g was used as a flame retardant, In the same manner as in Example 1, composite resin foam particles and foam particle molded bodies were produced. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 3 below.

(Comparative Example 3)
In this example, as a flame retardant, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (“Firecut P-65CN” manufactured by Suzuhiro Chemical Co., Ltd.); 50% decomposition temperature 336 ° C. ) Was used in the same manner as in Example 1 except that 2.5 g was used. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 3 below.

(Comparative Example 4)
In this example, as a flame retardant, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone (“Firecut P-65CN” manufactured by Suzuhiro Chemical Co., Ltd.); 50% decomposition temperature 336 ° C. ) Was used in the same manner as in Example 1 except that 100 g) was used, but a molded article that was severely shrinkable and could be evaluated for flame retardancy, compressive strength, and the like was obtained. I couldn't.

(Comparative Example 5)
In this example, core particles were prepared without using carbon black, and polypentabromobenzyl acrylate (“FR-1025” manufactured by ICL-IP Japan); 50% decomposition temperature as a flame retardant when preparing composite resin foamed particles. 367 ° C.) 25 g, and 100 parts by mass of the composite resin particles, except that 10 parts by mass of butane (a mixture of about 20% by mass of normal butane and about 80% by mass of isobutane) is used as a foaming agent. In the same manner as in Example 1, composite resin foam particles and foam particle molded bodies were produced. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 3 below.

(Comparative Example 6)
In this example, with respect to 100 parts by mass of the composite resin particles, 10 parts by mass of butane (a mixture of about 20% by mass of normal butane and about 80% by mass of isobutane) as a foaming agent, and polypentabromobenzyl acrylate (ICL) as a flame retardant A composite resin foam particle and a foamed particle molded body using the same were prepared in the same manner as in Example 1 except that 25 g of “FR-1025” manufactured by IP Japan Co., Ltd .; 50% decomposition temperature 367 ° C.) was used. did. Evaluation similar to Example 1 was performed also about the composite resin foamed particle and foamed-particle molded object obtained in this example. The results are shown in Table 3 below.

  The composite resin particles obtained in the above examples were obtained by observing the internal cross section of the composite resin particles with a transmission electron microscope. As a result, the styrene resin was the main component in the continuous phase mainly containing the olefin resin. The modified resin in which the dispersed phase is dispersed is used as a base resin, and an irregular-shaped granular dispersed phase is dispersed in the continuous phase to form a sea-island structure.

As is known from Tables 1 to 3, when the composite resin foamed particles of Examples 1 to 15 are used, excellent flame retardancy and dimensional stability are obtained while maintaining good rigidity, and residual aromatic carbonization. It turns out that the expanded particle molded object which reduced hydrogen content significantly can be manufactured. In Examples 1 to 10, Example 14 and Example 15, black composite resin foamed particles and foamed particle molded bodies were prepared by containing carbon. However, even if carbon black was contained, it was good. It can be seen that the flame retardancy can be secured. Furthermore, in Example 10, composite resin foamed particles and foamed particle molded bodies were produced using a foaming agent containing combustible butane. Even in this case, the butane content was extremely small (0.1% by mass). It is understood that good flame retardancy can be secured.
On the other hand, when the composite resin foamed particles of Comparative Examples 1 to 6 were used, a stable flame-retardant foamed particle molded body could not be produced.

Claims (7)

A styrene monomer is added to a suspension in which polyolefin resin particles are suspended in an aqueous medium, and the composite resin particles obtained by impregnating and polymerizing the styrene monomer in the polyolefin resin particles are expanded. A composite composed of 20 to 50 parts by mass of an olefin resin component and 80 to 50 parts by mass of a styrene resin component (the total amount of the olefin resin component and the styrene resin component is 100 parts by mass) Resin foam particles,
The composite resin expanded particles include bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2-bis (4- (2,3-dibromo-2-methylpropoxy). 1 to 15% by mass of one or more halogen-based flame retardants selected from -3,5-dibromophenyl) propane ,
The composite resin foam aliphatic hydrocarbon content of 3 to 6 carbon atoms in the particle is less than 0.1 mass% (including 0) der is, styrene monomer, toluene, xylene, and the total content of ethylbenzene 200ppm or less (including 0) composite resin foamed particles, characterized in der Rukoto.   2. The composite resin foamed particle according to claim 1, wherein a 50% decomposition temperature of the halogen-based flame retardant is A (° C.) and a 50% decomposition temperature of the composite resin foam particle is B (° C.). Composite resin foamed particles, wherein the particles satisfy a relationship of 50 ≦ (B−A) ≦ 150.   The composite resin foamed particle according to claim 1 or 2, wherein the composite resin contains one or more additives selected from carbon black, graphite, and carbon fiber in a total amount of 0.5 to 10% by mass. Resin foam particles. In a suspension of polyolefin resin particles suspended in an aqueous medium, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2-bis (4- ( A styrene monomer in which a halogen-based flame retardant containing one or more selected from 2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl) propane is dissolved in 100 mass of the polyolefin resin particles. 100 to 400 parts by mass with respect to part, and the above-mentioned polyolefin resin particles are impregnated with the styrene monomer and polymerized to obtain composite resin particles containing the halogen flame retardant, and
An impregnation step of impregnating a physical foaming agent containing 50 to 100% by mass of an inorganic physical foaming agent during and / or after the polymerization of the composite resin particles;
A foaming step of heating and foaming the composite resin particles impregnated with the physical foaming agent to obtain composite resin foam particles. In a suspension of polyolefin resin particles suspended in an aqueous medium, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2-bis (4- ( A styrene monomer in which a halogen-based flame retardant containing one or more selected from 2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl) propane is dissolved in 100 mass of the polyolefin resin particles. 100 to 400 parts by mass with respect to part, and the above-mentioned polyolefin resin particles are impregnated with the styrene monomer and polymerized to obtain composite resin particles containing the halogen flame retardant, and
An impregnation step of dispersing the composite resin particles together with a physical foaming agent containing 50 to 100% by mass of an inorganic physical foaming agent in a dispersion medium in a pressure resistant container, and impregnating the physical foaming agent;
And a foaming step of releasing the foamed composite resin particles impregnated with the physical foaming agent from the pressure vessel in a heat-softened state to foam the composite resin foamed particles. . 6. The production method according to claim 4 or 5 , wherein, in the reforming step, the polyolefin resin particles include one or more additives selected from carbon black, graphite, and carbon fiber. A method for producing composite resin foamed particles. In a suspension of polyolefin resin particles suspended in an aqueous medium, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfone, 2,2-bis (4- ( A styrene monomer in which a halogen-based flame retardant containing one or more selected from 2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl) propane is dissolved in 100 mass of the polyolefin resin particles. 100 to 400 parts by mass with respect to part, and the above-mentioned polyolefin resin particles are impregnated with the styrene monomer and polymerized to obtain composite resin particles containing the halogen flame retardant, and
An impregnation step of impregnating a physical foaming agent containing 50 to 100% by mass of an inorganic physical foaming agent during and / or after the polymerization of the composite resin particles.