JP2011093949A - Foamable polystyrene resin particles for production of banking member and process for production thereof, prefoamed particles for production of banking member, and banking member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a banking member having satisfactory flame retardant performance and excellent mechanical strength and dimensional stability with a flame retardant agent that is highly safe for environments and organisms. <P>SOLUTION: Foamable polystyrene resin particles for the production of a banking member are obtained by a melt extrusion method in which a flame retardant agent and a foaming agent are added to a polystyrene resin in a resin feed unit and kneaded, the resulting molten resin containing the flame retardant agent and foaming agent is directly extruded into a cooling liquid from small holes in a die attached to the leading end of the resin feed unit, and simultaneously with the extrusion, the extrudates are cut and solidified by cooling by contact with the liquid to obtain foamable polystyrene resin particles, wherein the flame retardant agent contains a bromine atom in the molecule, has a bromine-containing component content of <70 mass%, has a benzene ring in the molecule, and has a 5 mass% decomposition temperature of 200-300°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an embankment member excellent in environmental compatibility and flame retardancy, an expandable polystyrene resin particle for embedding member production used in the production thereof, and a production method thereof.

  Conventionally, embankment using a foamed synthetic resin block has been widely used for embankment on soft ground or sloped land, embankment in mountain building of a garden, and embedding and backfilling of underground structures. As a foam used for such a member, a polystyrene resin foam is often used from the viewpoint of strength, water resistance, etc. Among them, an expandable polystyrene resin particle (also referred to as a bead) is heated. In general, a foam molded body manufactured by an in-mold foam molding method in which pre-foamed particles are obtained, and the obtained pre-foamed particles are filled in a cavity of a molding die, and heated and foamed and molded in the die, is generally used.

The embankment member is usually required to have a certain level or more of flame retardancy from the viewpoint of preventing the occurrence of a fire or the like and preventing the ground from becoming unstable due to the spread of fire. In order to impart sufficient flame retardancy to a polystyrene resin foam molded article, a flame retardant is added to the expandable polystyrene resin particles for producing the foam molded article.
Conventionally, as a method of adding a flame retardant to a polystyrene-based resin foam molded article, a method of adding a flame retardant together with a styrene monomer at the time of polymerization (for example, see Patent Document 1), polystyrene resin particles are impregnated with a foaming agent. There is a method of adding a flame retardant (for example, see Patent Documents 2 to 4).

JP 2003-64212 A JP 2003-335891 A JP 2002-194130 A Japanese Patent No. 4035979

In the prior art disclosed in Patent Documents 1 to 4, hexabromocyclododecane (HBCD) is used as a flame retardant. Hexabromocyclododecane is a type 1 monitoring chemical substance in the Chemical Substances Control Regulation Law, and it has been pointed out that it is difficult to decompose and highly concentrated in the existing chemical substance safety inspection of the Ministry of Economy, Trade and Industry, and is also subject to European risk assessment assessment. Since there is a problem with its safety, it is desired to eliminate its use.
In the case of using an alternative flame retardant, the method disclosed in Patent Document 1 may be difficult to produce if an alternative flame retardant is used.
In addition, as disclosed in Patent Documents 2 to 4, when impregnating polystyrene resin particles with a foaming agent, a method of adding a flame retardant at the same time as the foaming agent and impregnating the polystyrene resin particles with these foaming agents is difficult. By causing secondary aggregation in the suspension of the flame retardant, the dispersion of the flame retardant in the suspension becomes non-uniform, resulting in non-uniform absorption of the powdered flame retardant into the resin particles, There is a problem that some resin particles absorb a lot of the flame retardant.
In addition, in the method of adding the polystyrene resin particles impregnated with the flame retardant as described above, the flame retardant is impregnated near the surface of the polystyrene resin particles, but the flame retardant is not present or contained near the resin particle center. Only low-resin resin particles can be obtained. Polystyrene resin foam molded products obtained by pre-foaming such resin particles and then foam-molding the obtained pre-foamed particles have poor mechanical strength and are dimensionally stable. The property becomes worse, and it is not suitable for the use for producing the material for embankment.

  The present invention was made in view of the above circumstances, and has an object to provide a banking member having sufficient flame retardancy using a flame retardant having high safety to the environment and living organisms, and excellent in mechanical strength and dimensional stability. And

In order to achieve the above object, the present invention is an expandable polystyrene resin particle for embankment member production in which a polystyrene resin containing a flame retardant and a foaming agent is in the form of particles,
The flame retardant has a bromine atom in the molecule, a bromine content of less than 70% by mass, a benzene ring in the molecule, and a 5% by mass decomposition temperature of the flame retardant of 200 to 300 ° C. Within the range of
A flame retardant and foaming agent are added to and kneaded with polystyrene resin in the resin supply device, and the molten resin containing the flame retardant / foaming agent is extruded directly into the cooling liquid through a small hole in the die attached to the tip of the resin supply device. The material for embankment is obtained by a melt extrusion method in which extrudate is cut at the same time as extrusion and the extrudate is cooled and solidified by contact with a liquid to obtain expandable polystyrene resin particles. Expandable polystyrene resin particles for use are provided.

  In the expandable polystyrene resin particles for embankment member production of the present invention, the flame retardant is preferably one or more selected from the group consisting of tetrabromobisphenol A or a derivative thereof.

  In the foamable polystyrene resin particles for producing embankment members of the present invention, the flame retardant is tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis (2, 3-dibromopropyl ether) and tetrabromobisphenol A-bis (allyl ether) are preferably selected from the group consisting of one or more.

  The present invention also provides pre-expanded particles for producing embankment members obtained by heating the expandable polystyrene resin particles for producing embankment members.

Further, the present invention is an embankment obtained by filling the pre-expanded particles for producing embankment members in a cavity of a mold, heating and foaming, and having a density in the range of 0.010 to 0.050 g / cm ³ . Providing a member.

  Further, the present invention is obtained by filling the above-mentioned pre-expanded particles for producing embankment members into a cavity of a mold and heating and foaming. An embankment member having a range of 200 μm is provided.

  The present invention also provides a banking member having an oxygen index of 26 or more obtained by filling the pre-expanded particles for manufacturing a banking member in a cavity of a mold, heating and foaming.

  Further, the present invention provides a polystyrene resin in a resin supply apparatus having a bromine atom in the molecule, a bromine content of less than 70% by mass, a benzene ring in the molecule, and the flame retardant. A flame retardant and a foaming agent having a 5 mass% decomposition temperature in the range of 200 to 300 ° C. are added and kneaded. Extruding into a cooling liquid, cutting the extrudate at the same time as extruding, and cooling and solidifying the extrudate by contact with the liquid to obtain expandable polystyrene resin particles for embankment production according to the present invention Provided is a method for producing expandable polystyrene resin particles for embankment member production.

  In the method for producing expandable polystyrene resin particles for producing embankment members according to the present invention, the flame retardant is preferably one or more selected from the group consisting of tetrabromobisphenol A or a derivative thereof.

  In the method for producing expandable polystyrene resin particles for producing a member for embankment of the present invention, the flame retardant is tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis. It is preferable that it is 1 type, or 2 or more types selected from the group consisting of (2,3-dibromopropyl ether) and tetrabromobisphenol A-bis (allyl ether).

  In the method for producing expandable polystyrene resin particles for producing embankment members according to the present invention, a master batch material containing the flame retardant at a predetermined concentration in a resin is supplied together with the polystyrene resin into a resin supply device, It is preferable to melt-knead with.

The expandable polystyrene resin particles for producing embankment members of the present invention have a bromine atom in the molecule, a bromine content of less than 70% by mass, a benzene ring in the molecule, and the flame retardant. It contains a flame retardant having a 5 mass% decomposition temperature of 200 to 300 ° C. The flame retardant is highly safe for the environment and organisms. In particular, the tetrabromobisphenol A derivative can impart sufficient flame retardant performance when added to a polystyrene resin foamed molded article, and is safe for the environment and organisms. Since the safety is high, it is possible to provide an embankment member that is excellent in safety.
The expandable polystyrene resin particles for embankment material production according to the present invention are prepared by adding a flame retardant and a foaming agent to a polystyrene resin in a resin supply device, kneading, and adding a flame retardant / foaming agent-containing molten resin to the tip of the resin supply device. Extruded directly from the small hole of the die attached to the cooling liquid and simultaneously extruded, cutting the extrudate, and cooling and solidifying the extrudate by contact with the liquid to obtain expandable polystyrene resin particles Since the flame retardant is uniformly present in the resin particles, the mechanical strength of the resulting embankment member is higher than that in which the flame retardant is unevenly present in the resin particles. Moreover, the embankment member excellent in moldability and dimensional stability can be obtained.

  The embankment member of the present invention heats and expands the expandable polystyrene resin particles for producing the embankment member, and further fills the obtained pre-expanded particles in a cavity of a mold and heats and expands the foamed polystyrene resin particles. Therefore, it is possible to provide an embankment member that has sufficient flame retardancy and is excellent in mechanical strength and dimensional stability by using a flame retardant having high safety to the environment and living organisms.

According to the method for producing expandable polystyrene resin particles for producing embankment members of the present invention, as described above, expandable polystyrene resin particles for producing embankment members can be efficiently produced.
In the method for producing expandable polystyrene resin particles for embankment member production of the present invention, a master batch material containing the flame retardant at a predetermined concentration in the resin is supplied together with the polystyrene resin into a resin supply device, By melt-kneading in the apparatus, the flame retardant can be more uniformly contained in the resin particles.

It is a block diagram which shows an example of the manufacturing apparatus used for the manufacturing method of the expandable polystyrene-type resin particle for member production for embankment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The method for producing expandable polystyrene resin particles for embankment production according to the present invention has a bromine atom in the molecule in the polystyrene resin in the resin supply apparatus, and the bromine content is less than 70% by mass, A flame retardant having a benzene ring in the molecule and a 5 mass% decomposition temperature of the flame retardant within a range of 200 to 300 ° C. and a foaming agent are added and kneaded to obtain a flame retardant / foaming agent-containing molten resin. Extruded directly into the cooling liquid through a small hole in the die attached to the tip of the resin supply device, and at the same time, extrudate is cut, and the extrudate is cooled and solidified by contact with the liquid. It is characterized by obtaining polystyrene resin particles.

  FIG. 1: is a block diagram which shows an example of the manufacturing apparatus used for the manufacturing method of the expandable polystyrene-type resin particle for embankment member manufacture of this invention, and the manufacturing apparatus of this example is the extruder 1 as a resin supply apparatus. A die 2 having a large number of small holes attached to the tip of the extruder 1, a raw material supply hopper 3 for introducing a resin raw material into the extruder 1, and a blowing agent supply port for the molten resin in the extruder 1 A high pressure pump 4 for press-fitting a foaming agent through 5, a cutting chamber 7 provided so that cooling water is brought into contact with a resin discharge surface in which a small hole of the die 2 is formed, and cooling water is circulated and supplied into the room; A cutter 6 rotatably provided in the cutting chamber 7 so that the resin extruded from the small hole of the die 2 can be cut, and foaming particles carried along with the flow of cooling water from the cutting chamber 7 And dehydrated and dried A dehydrating dryer 10 with a solid-liquid separation function to obtain expandable particles, a water tank 8 for storing cooling water separated by the dehydrating dryer 10 with a solid-liquid separation function, and a cutting chamber for cooling water in the water tank 8 7 and a storage container 11 for storing expandable particles dehydrated and dried by a dehydration dryer 10 with a solid-liquid separation function.

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

  In the foamable polystyrene resin particles for producing embankment members of the present invention, the polystyrene resin is not particularly limited, and examples thereof include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, Examples include homopolymers of styrene monomers such as dimethylstyrene and bromostyrene, copolymers thereof, and the like. Polystyrene resins containing 50% by mass or more of styrene are preferable, and polystyrene is more preferable.

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

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

  In the expandable polystyrene resin particles for embankment production of the present invention, the polystyrene resin as a raw material is a polystyrene resin newly produced by a method such as a commercially available ordinary polystyrene resin or suspension polymerization method. In addition to a polystyrene-based resin (virgin polystyrene) that is not a recycled material, a recycled material obtained by regenerating a used polystyrene-based resin foam molding can be used. As this recycled material, used polystyrene-based resin foam moldings such as fish boxes, household appliance cushioning materials, food packaging trays, etc. are collected and recycled from the recycled materials recovered by the limonene dissolution method or heating volume reduction method. A raw material having a weight average molecular weight Mw in the range of 120,000 to 400,000 can be appropriately selected, or a plurality of recycled raw materials having different weight average molecular weights Mw can be used in appropriate combination.

In the foamable polystyrene resin particles for producing embankment members of the present invention, the flame retardant has a bromine atom in the molecule, a bromine content of less than 70% by mass, and a benzene ring in the molecule. In addition, a flame retardant having a 5% by mass decomposition temperature of the flame retardant within a range of 200 to 300 ° C. is used, or one or more of the flame retardants are mixed, or the flame retardant is mainly used. In addition, other flame retardants may be used in combination.
A flame retardant with a bromine content of more than 70% by mass and no benzene ring in the molecule is unlikely to be a flame retardant that is highly safe for the environment and organisms, and has excellent mechanical strength, moldability, and dimensional stability. It becomes difficult to achieve the effect of the present invention that provides a member for embankment. The lower limit of the bromine content is not particularly limited, but 50% by mass or more is preferable because the flame retardancy is good. A more preferable range of bromine content is 55 to 69 mass%.
Further, when the 5 mass% decomposition temperature of the flame retardant is less than 200 ° C., when the flame retardant and polystyrene resin are melt-kneaded in the extruder 1, the flame retardant decomposes and a flame retardant effect is obtained. There is a risk of disappearing. When a flame retardant having a 5 mass% decomposition temperature exceeding 300 ° C. is used, the flame retardancy of the resulting embankment member is lowered. The preferable range of 5 mass% decomposition temperature of this flame retardant is 230-300 degreeC, The more preferable range is 240-295 degreeC, The most preferable range is 265-290 degreeC.

In the present invention, preferred flame retardants include one or more selected from the group consisting of tetrabromobisphenol A or derivatives thereof. Among these flame retardants, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A- It is preferable that it is 1 type, or 2 or more types selected from the group consisting of bis (allyl ether). Tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) having a high 5% decomposition temperature are more preferred, and tetrabromobisphenol A- Bis (2,3-dibromopropyl ether) is most preferred.
In the expandable polystyrene resin particles for producing embankment members of the present invention, the amount of the flame retardant added is 0.5 to 8.8 based on 100 parts by mass of the resin content of the expandable polystyrene resin particles for embankment member production. It is preferable to set it as the range of 0 mass%, and the range of 1.0-6.0 mass% is still more preferable. When the addition amount of the flame retardant is less than the above range, the flame retardancy of the obtained embankment member is lowered. If the amount of the flame retardant added exceeds the above range, the mechanical strength, formability, and dimensional change rate of the resulting embankment member may be deteriorated.

  In the foamable polystyrene resin particles for embankment production according to the present invention, the foaming agent is not particularly limited. For example, normal pentane, isopentane, cyclopentane, cyclopentadiene, etc. are used alone or in admixture of two or more. can do. Further, normal butane, isobutane, propane and the like can be mixed and used with the pentane as a main component. In particular, pentanes are preferably used because they easily suppress foaming of the resin particles when discharged into the water stream from the small holes of the die. The amount of the foaming agent contained in the polystyrene resin is in the range of 3 to 10 parts by mass, more preferably in the range of 4 to 7 parts by mass with respect to 100 parts by mass of the polystyrene resin.

  In addition to the flame retardant and foaming agent, the foamable polystyrene resin particles for producing embankment members according to the present invention may be added to other additives generally used in the production of expandable polystyrene resin particles. For example, talc, calcium silicate, synthetic or naturally produced silicon dioxide, ethylene bisstearic acid amide, foaming nucleating agent such as methacrylic acid ester copolymer, flame retardant aid such as diphenylalkane and diphenylalkene, carbon Colorants such as black, iron oxide and graphite, phenolic antioxidants, sulfur antioxidants, antioxidants such as phosphorus antioxidants, stabilizers such as hindered amines, UV absorbers, antioxidants, etc. Additives can be added to the polystyrene-based resin.

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

  In a preferred embodiment of the present invention, when the flame retardant is added, a masterbatch material containing a flame retardant at a predetermined concentration in the resin is used, and this is supplied into the resin supply apparatus together with the polystyrene-based resin. It is preferable to melt and knead. A master batch material containing the flame retardant at a predetermined concentration in the resin is supplied into the resin supply apparatus together with the polystyrene resin, and melt-kneaded in the apparatus so that the flame retardant is more uniformly contained in the resin particles. Can do.

  After supplying polystyrene-based resin and flame retardant, further foaming aid and other additives into the extruder 1, the resin is heated and melted, and the flame retardant-containing molten resin is transferred to the die 2 side while supplying the foaming agent supply port. The foaming agent is press-fitted with a high-pressure pump 4 from 5, the foaming agent is mixed with the flame retardant-containing molten resin, and the melt is further kneaded through a foreign matter removing screen provided in the extruder 1 as necessary. The melted material added with the blowing agent is pushed out from the small hole of the die 2 attached to the tip of the extruder 1.

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

  The formed expandable polystyrene resin particles for producing embankment members are transported from the cutting chamber 7 to the flow of cooling water and carried to the dehydrating dryer 10 with a solid-liquid separation function. The polystyrene resin particles are separated from the cooling water and dehydrated and dried. The dried expandable polystyrene resin particles for producing embankment members are stored in the storage container 11.

  Expandable polystyrene resin particles for embankment member production as described above are made into a particulate polystyrene resin containing a flame retardant and a foaming agent, and the flame retardant has a bromine atom in the molecule. The bromine content is less than 70% by mass, the molecule has a benzene ring, and the flame retardant has a 5% by mass decomposition temperature in the range of 200 to 300 ° C.

  In the expandable polystyrene resin particles for producing embankment members of the present invention, the flame retardant is uniformly contained in the resin particles. If the foamable polystyrene resin particles for producing embankment members of the present invention are not evenly contained, the mechanical strength, moldability, dimensional stability and flame retardancy of the obtained foamed molded product (embankment member) are poor. There is a fear.

The flame retardant used in the expandable polystyrene resin particles for producing embankment members according to the present invention is highly safe for the environment and living organisms. In particular, the tetrabromobisphenol A derivative is added to the polystyrene resin foam molded article. In this case, sufficient flame retardancy can be imparted, and the environment and organisms are highly safe.
The expandable polystyrene resin particles for producing embankment members of the present invention are obtained in comparison with those in which the flame retardant is uniformly present in the resin particles and the flame retardant is non-uniformly present in the resin particles. The embedding member has high mechanical strength, and an embedding member having excellent moldability and dimensional stability can be obtained.

  In the production method according to the present invention, a resin raw material having a low content of an aromatic organic compound composed of a styrene monomer, ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, toluene, and benzene is selected as a polystyrene resin as a raw material. For example, since it is possible to obtain expandable polystyrene resin particles for embedding member production without mixing the aromatic organic compound in the production process, the obtained expandable polystyrene resin particles for embedding member production are: The total content of the aromatic organic compound can be less than 500 ppm. The total content of the aromatic organic compound is more preferably 450 ppm or less, and still more preferably 400 ppm or less. If the total content of the aromatic organic compound is low, the resulting embankment member has high mechanical strength and a low dimensional change rate. In addition, it is possible to cope with sick house syndrome which has been requested in recent years, and it is possible to ensure safety when storing the embankment member.

In the present invention, the total content of the aromatic organic compound is a value measured by the following <Measurement method of volatile organic compound (VOC) content>.
<Measurement method of volatile organic compound (VOC) content>
Weigh accurately 1 g of expandable polystyrene resin particles, add 1 ml of a dimethylformamide solution containing 0.1% by volume of cyclopentanol as an internal standard solution, and then add dimethylformamide to the dimethylformamide solution to measure 25 ml. A solution was prepared, and 1.8 μl of this measurement solution was supplied to a 230 ° C. sample vaporization chamber to obtain a chart of each volatile organic compound detected by a gas chromatograph. And based on the calibration curve of each volatile organic compound measured beforehand, the amount of volatile organic compounds was calculated from each chart, and the amount of volatile organic compounds in the expandable polystyrene resin particles was calculated.
In the present invention, among the volatile organic compound (VOC) contents described above, the total amount of each volatile organic compound corresponding to the aromatic organic compound is defined as “total amount of aromatic organic compound”.

The foamable polystyrene resin particles for embankment member production obtained by the production method according to the present invention described above are pre-foamed by heating by steam heating or the like using a well-known apparatus and method in the field of foamed resin molding production. And pre-expanded particles for embankment member production (hereinafter referred to as pre-expanded particles). The pre-expanded particles are pre-expanded so as to have a bulk density equivalent to the density of the foam molded body (filling member) to be manufactured. In the present invention, its bulk density is not limited, preferably in a range of 0.010~0.050g / cm ^3, within the scope of 0.015~0.033g / cm ³ is more preferable.

In the present invention, the bulk density of the pre-expanded particles is measured as follows.
<Bulk density and bulk expansion ratio of pre-expanded particles>
First, Wg was sampled from pre-expanded particles as a measurement sample, and this measurement sample was allowed to fall naturally into a graduated cylinder, and then the apparent volume (V) cm ³ of the sample was made constant by tapping the bottom of the graduated cylinder. And the volume is measured, and the bulk density of the pre-expanded particles is measured based on the following formula.
Bulk density (g / cm ³ ) = mass of measurement sample (W) / volume of measurement sample (V)
The bulk expansion ratio of the pre-expanded particles is a numerical value calculated by the following formula.
Bulk foam multiple (times) = 1 / bulk density (g / cm ³ )

The pre-expanded particles can be obtained by filling the pre-expanded particles into a cavity of a molding die using a well-known apparatus and technique in the field of manufacturing a foamed resin molded body, and heating them by steam heating or the like to perform in-mold foam molding. The embankment member which consists of a flame-retardant polystyrene type resin foam molding is manufactured.
Although the density of the embankment member of the present invention is not particularly limited, but is preferably in the range of 0.010~0.050g / cm ^3, within the scope of 0.015~0.033g / cm ³ is more preferable.
In addition, the shape, dimensions, etc. of the embankment member are not particularly limited, and are appropriately determined according to the embedding method to be carried out, the scale, etc. The size and shape can be made.

In the present invention, the density of the embankment member is the density of the foamed molded product measured by the method described in JIS K7122: 1999 “Measurement of foamed plastic and rubber-apparent density”.
<Density and expansion ratio of foamed molded product>
A test piece of 50 cm ³ or more (100 cm ³ or more in the case of semi-rigid and soft materials) was cut so as not to change the original cell structure of the material, its mass was measured, and calculated by the following formula.
Density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ )
Test piece condition adjustment and measurement test pieces were cut out from samples that had passed 72 hours or more after molding, and were subjected to atmospheric conditions of 23 ° C. ± 2 ° C. × 50% ± 5% or 27 ° C. ± 2 ° C. × 65% ± 5%. It has been left for more than an hour.
Further, the expansion factor of the foamed molded product is a numerical value calculated by the following equation.
Foaming multiple (times) = 1 / density (g / cm ³ )

In the embankment member of the present invention, the average chord length of the bubbles is preferably in the range of 40 to 200 μm, more preferably in the range of 50 to 150 μm, with respect to the foamed molded product having a foaming factor of 50 times. In addition, in this invention, the average chord length of a bubble is an average chord length of the bubble of a foaming molding measured by the following method.
<Average string length>
The average chord length of the bubbles of the foam molded article refers to that measured according to the test method of ASTM D2842-69. Specifically, the foamed molded body is cut into approximately equal halves, and the cut surface is photographed at a magnification of 100 times using a scanning electron microscope (trade name “S-3000N” manufactured by Hitachi, Ltd.). The photographed image is printed on A4 paper, and a straight line having a length of 60 mm is drawn at an arbitrary position, and the average chord length (t) of the bubbles is calculated from the following formula from the number of bubbles existing on the straight line.
Average string length t = 60 / (number of bubbles × photo magnification)
When drawing a straight line, if the straight line is in point contact with the bubble, this bubble is included in the number of bubbles, and both ends of the straight line are not penetrating the bubble and are in the bubble. In this case, the bubbles in which both ends of the straight line are positioned are included in the number of bubbles. Further, the average chord length is calculated in the same manner as described above at any five locations in the photographed image, and the arithmetic mean value of these average chord lengths is set as the average chord length of the bubbles of the foam molded body.
The embankment member of the present invention preferably has an oxygen index of 26 or more. If the oxygen index is less than 26, sufficient flame retardancy may not be obtained.

[Example 1]
(Manufacture of expandable polystyrene resin particles)
Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) as a flame retardant with respect to 100 parts by mass of a polystyrene resin (trade name “HRM-10N” manufactured by Toyo Styrene Co., Ltd.) as a base resin 7 parts by mass of a polystyrene resin masterbatch (made by Daiichi Kogyo Seiyaku Co., Ltd.) containing 50% by mass (corresponding to 3.5 parts by mass of flame retardant) and 0.7 parts by mass of fine powder talc are uniformly mixed in advance using a tumbler mixer. After being fed into a single-screw extruder with a diameter of 90 mm at a rate of 160 kg / hr per hour, the resin is heated and melted, and then 6 parts by mass of isopentane as a foaming agent is added to the resin in the middle of the extruder. More press fit. Then, while kneading the resin and the foaming agent in the extruder, while cooling so that the resin temperature at the tip of the extruder is 190 ° C., it is connected to the extruder and held at 320 ° C. by a heater, diameter 0.6 mm Then, through a granulation die having 200 nozzles with a land length of 3.0 mm, it is extruded into a chamber in which cooling water at 30 ° C. circulates, and at the same time, a high-speed rotary cutter having 10 blades in the circumferential direction is used as the die Adhered, cut at 3000 rpm, dehydrated and dried to obtain spherical expandable polystyrene resin particles. The obtained expandable resin particles had no average deformation and no whisker, and had an average particle size of 1.1 mm.
Polyethylene glycol 0.03 parts by mass, zinc stearate 0.15 parts by mass, stearic acid monoglyceride 0.05 parts by mass, hydroxystearic acid triglyceride 0.05 parts by mass with respect to 100 parts by mass of the obtained expandable polystyrene resin particles. The part was uniformly coated on the entire surface of the expandable polystyrene resin particles.

(Manufacture of foam moldings)
The expandable polystyrene resin particles produced as described above are placed in a 15 ° C. cool box and allowed to stand for 72 hours, and then supplied to a cylindrical batch type pre-foaming machine to generate steam with a blowing pressure of 0.05 MPa. To obtain pre-expanded particles. The obtained pre-expanded particles had a bulk density of 0.015 g / cm ³ (bulk expansion ratio: 67 times). Subsequently, the pre-expanded particles obtained were allowed to stand at room temperature for 24 hours, and then the pre-expanded particles were filled into a mold having a rectangular cavity of length 400 mm × width 300 mm × height 50 mm. Thereafter, the inside of the cavity of the mold is heated with water vapor at a gauge pressure of 0.08 MPa for 20 seconds, and then cooled until the pressure in the cavity of the mold reaches 0.01 MPa. Opened, a rectangular foam molded body having a length of 400 mm, a width of 300 mm, and a height of 50 mm was taken out. The obtained foamed molded product had a density of 0.015 g / cm ³ (foaming factor 67 times).

  The following evaluation tests were performed on the expandable polystyrene resin particles, pre-expanded particles, and expanded molded articles of Example 1 produced as described above.

<Measurement of flame retardant decomposition temperature>
20 mg of the flame retardant composition was sampled and used as a sample, using a differential heat and calorie simultaneous measurement device TG / DTA 300 type (manufactured by Seiko Denshi Kogyo Co., Ltd.), a nitrogen gas amount of 30 ml / min, a heating temperature of 10 ° C./min, The mass reduction rate of the sample is measured at a measurement temperature of 30 to 800 ° C., and a graph is obtained with the mass reduction rate of the sample on the vertical axis and the temperature on the horizontal axis. And based on the obtained graph, the temperature when the mass reduction rate of the sample reached 5% was defined as “5 mass% decomposition temperature”.

<Evaluation of bead foamability>
After the expandable polystyrene resin particles obtained in the examples (and comparative examples) were stored in a 15 ° C. cool box for 72 hours, this was supplied to a cylindrical batch type pre-foaming machine, and the blowing vapor pressure was 0.05 MPa. The pre-expanded particles obtained were heated for 2 minutes with water vapor and the bulk expansion ratio of the pre-expanded particles was measured as follows, and the following evaluation criteria:
○ (good) when the foam expansion ratio is 60 times or more
△ (slightly good) when the bulk expansion ratio is 50 times or more and less than 60 times,
The bead foaming property was evaluated in light of x (defective) when the bulk expansion ratio was less than 50 times.

<Evaluation of flame retardancy>
A test piece having a thickness of 10 mm, a length of 150 mm, and a width of 10 mm was cut out from the obtained foamed molded article with a vertical cutter, cured in a 50 ° C. oven for 7 days, and then adjusted to a temperature of 23 ° C. and a relative humidity of 50%. The condition was adjusted for 4 days, the oxygen index was measured according to JIS K7201, and the flame retardancy was evaluated based on the following criteria.
○ (Good): Oxygen index is 26 or more x (Poor): Oxygen index is less than 26

<Appearance evaluation of foam molding>
The polystyrene resin pre-expanded particles were filled into a mold of a foam molding machine and subjected to secondary foaming using water vapor to obtain a rectangular foam-shaped foam molded body having a length of 400 mm, a width of 300 mm, and a thickness of 50 mm.
The appearance of the foamed molded product was visually observed and evaluated based on the following criteria.
A (very good): There is no gap between the expanded particles, and the surface is very smooth.
○ (good): There is no gap between the expanded particles, and the surface is smooth.
Δ (slightly good): There are few gaps between the expanded particles, and the surface smoothness is slightly inferior.
X (Poor): The gap between the expanded particles is large, and the smoothness of the surface is considerably inferior.

<Comprehensive evaluation>
Regarding each of the evaluation items of <Bead Foaming Evaluation>, <Flame Retardancy Evaluation>, and <Foam Molded Body Appearance Evaluation> Those having x) were comprehensively evaluated as defective (x).

[Example 2]
As the flame retardant, foam molding with an expansion ratio of 67 times was performed in the same manner as in Example 1 except that the same amount of tetrabromobisphenol A-bis (2,3-dibromopropyl ether) (Daiichi Kogyo Seiyaku Co., Ltd.) was used. The body was manufactured.

[Example 3]
A foamed molded article having a foam expansion factor of 67 times was produced in the same manner as in Example 1 except that the same amount of tetrabromobisphenol A-bis (allyl ether) (Daiichi Kogyo Seiyaku Co., Ltd.) was used as the flame retardant.

[Example 4]
Except that 3.2 parts by mass of tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and 0.3 parts by mass of tetrabromobisphenol A-bis (allyl ether) were used as flame retardants, In the same manner as in Example 1, a foamed molded article having a foam multiple of 67 times was produced.

[Example 5]
A foamed molded article having a foam multiple of 67 times was produced in the same manner as in Example 1 except that the blending amount of the flame retardant A was 5.0 parts by mass.

[Comparative Example 1]
A foamed molded article was produced in the same manner as in Example 1 except that the same amount of hexabromocyclododecane (Daiichi Kogyo Seiyaku Co., Ltd.) was used as the flame retardant.

[Comparative Example 2]
A foamed molded article was produced in the same manner as in Example 1 except that the same amount of tris- (2,3-dibromopropyl) isocyanurate (Nihon Kasei Co., Ltd.) was used as the flame retardant.

[Comparative Example 3]
A foamed molded article was produced in the same manner as in Example 1 except that the same amount of pentabromobenzyl acrylate (Daiichi Kogyo Seiyaku Co., Ltd.) was used as the flame retardant.

[Comparative Example 4]
A foamed molded article was produced in the same manner as in Example 1 except that the same amount of tris (tribromoneopentyl) phosphate (manufactured by Daihachi Chemical Co., Ltd.) was used as a flame retardant.

Table 1 summarizes the bromine content of the flame retardants used in Examples 1 to 5 and Comparative Examples 1 to 4, the presence or absence of a benzene ring in the flame retardant molecule, and the 5 mass% decomposition temperature.
Moreover, the measurement and evaluation results of Examples 1 to 5 and Comparative Examples 1 to 4 are summarized in Table 2.

From the results of Tables 1 and 2, the examples have bromine atoms in the molecule, the bromine content is less than 70% by mass, the molecule has a benzene ring, and the flame retardant has a 5% by mass decomposition temperature. In Examples 1 to 5 according to the present invention using the flame retardants A to C in the range of 200 to 300 ° C., the bead foamability, flame retardancy, and the appearance of the foam were all good.
On the other hand, Comparative Example 1 using the flame retardant D having a high bromine content of 75% by mass and having no benzene ring in the molecule had poor bead foaming properties.
In Comparative Example 2 using the flame retardant E having no benzene ring in the molecule, the bead foaming property and the appearance of the foam were poor.
In addition, Comparative Example 3 using the flame retardant F having a high bromine content of 75% by mass and a 5% by mass decomposition temperature exceeding 300 ° C. had poor flame retardancy.
Comparative Example 4 using a flame retardant G having a high bromine content of 75% by mass, no benzene ring in the molecule and a 5% by mass decomposition temperature exceeding 300 ° C. All of the foam appearances were poor.

  The present invention relates to a flame-retardant polystyrene resin foam molded article having sufficient flame retardancy using a flame retardant having high safety to the environment and living organisms and excellent in mechanical strength, moldability and appearance, and the molded article The present invention relates to an expandable polystyrene resin particle for use in the production of embankment members and a method for producing the same. The embankment member of the present invention is suitably used for embankment on soft ground or on sloping ground, embankment in the construction of gardens, and embedding and backfilling of underground structures.

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

Claims (11)

Expandable polystyrene resin particles for producing a material for embankment in which a polystyrene resin containing a flame retardant and a foaming agent is in the form of particles,
The flame retardant has a bromine atom in the molecule, a bromine content of less than 70% by mass, a benzene ring in the molecule, and a 5% by mass decomposition temperature of the flame retardant of 200 to 300 ° C. Within the range of
Add and knead the flame retardant and foaming agent to the polystyrene resin in the resin supply unit, and extrude the flame retardant / foaming agent-containing molten resin directly into the cooling liquid from the small hole in the die attached to the tip of the resin supply unit The material for embankment is obtained by a melt extrusion method in which extrudate is cut at the same time as extrusion and the extrudate is cooled and solidified by contact with a liquid to obtain expandable polystyrene resin particles. Expandable polystyrene resin particles.   2. The expandable polystyrene resin particles for embankment material production according to claim 1, wherein the flame retardant is one or more selected from the group consisting of tetrabromobisphenol A or a derivative thereof.   The flame retardant is tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (allyl ether) The expandable polystyrene resin particles for producing embankment members according to claim 2, which are one or more selected from the group consisting of:   Pre-expanded particles for producing a member for embankment obtained by heating the expandable polystyrene resin particles for producing a member for embankment according to claim 1. The pre-expanded particles for producing embankment members according to claim 4 are filled in a cavity of a mold and heated and foamed, and the density is in the range of 0.010 to 0.050 g / cm ³ . Element.   An average chord length of bubbles is about 40 to 40 for a foamed molded article obtained by filling the pre-expanded particles for producing embankment members according to claim 4 into a cavity of a mold and heating and foaming. Filling member in the range of 200 μm.   A banking member having an oxygen index of 26 or more, which is obtained by filling pre-expanded particles for producing a banking member according to claim 4 into a cavity of a mold, heating and foaming.   In the resin feeder, the polystyrene-based resin has a bromine atom in the molecule, a bromine content of less than 70% by mass, a benzene ring in the molecule, and a 5% by mass decomposition temperature of the flame retardant. Add and knead the flame retardant and foaming agent in the range of 200 to 300 ° C., and add the flame retardant / foaming agent-containing molten resin directly into the cooling liquid from the small hole of the die attached to the tip of the resin feeder Extruding, cutting the extrudate at the same time as extruding, and cooling and solidifying the extrudate by contact with a liquid to obtain expandable polystyrene resin particles for embankment member production according to claim 1. For producing expandable polystyrene-based resin particles for use in manufacturing components.   The method for producing expandable polystyrene resin particles for embankment material production according to claim 8, wherein the flame retardant is one or more selected from the group consisting of tetrabromobisphenol A or a derivative thereof.   The flame retardant is tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (allyl ether) The method for producing expandable polystyrene resin particles for embankment member production according to claim 9, which is one or more selected from the group consisting of:   The embankment according to any one of claims 8 to 10, wherein a master batch material containing the flame retardant at a predetermined concentration in a resin is supplied into a resin supply apparatus together with the polystyrene resin and melt-kneaded in the apparatus. The manufacturing method of the expandable polystyrene-type resin particle for member manufacture.

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