JP2017179138A - Foamable particle of rubber modified polystyrene-based resin, foaming particle and foaming molded body and manufacturing method and application thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foaming particle and a foaming molded body of rubber modified polystyrene-based resin having preferable impact resistance and oil resistance and a foamable resin particle for manufacturing the same.SOLUTION: A foaming particle and the foaming molded body are a foaming particle and a foaming molded body of a rubber modified polystyrene-based resin, the diene polymer rubber contains 1,4 cis structure of 70% or more, percentage content of the diene polymer rubber in the rubber modified polystyrene resin is 9 to 15 mass%, a polystyrene resin is graft bound to the diene polymer rubber, graft rate of 137 to 160% and air bubble with average diameter of 100 to 300 μm is included.SELECTED DRAWING: None

Description

  The present invention relates to a foamed molded article of resin suitable for applications requiring impact resistance and oil resistance, and expandable particles and foamed particles for producing the same. The invention also relates to a method for their production. The present invention also relates to the use of the foamed molded article and the foamed particles.

  Foam molded articles made of polystyrene resins have excellent buffering properties and heat insulation properties, and are easy to mold. Therefore, they are often used as packaging materials and heat insulation materials. However, since the impact resistance and flexibility are insufficient, cracks and chips are likely to occur, and there is a problem that it is not suitable, for example, for packaging precision instrument products. Moreover, there exists a problem that a foam will be eroded if it is an environment where machine oil, edible oil, etc. adhere.

  On the other hand, a foam molded body made of polypropylene resin is excellent in impact resistance and flexibility, but requires large facilities when molding the foam molded body. Also, due to the nature of the resin, it must be transported from the manufacturer to the molding processor in the form of expanded particles. Therefore, there has been a problem that the manufacturing cost increases.

  In recent years, a foam-molded product of a rubber-modified polystyrene resin has been developed as one that is easy to mold and has improved impact resistance and flexibility as compared with a polystyrene-based foam. A typical example of the rubber-modified polystyrene resin is a high impact polystyrene resin (also referred to as a HIPS resin) obtained by modifying a polystyrene resin with a butadiene rubber. However, the impact resistance of HIPS resin is not always sufficient, and various improved techniques have been developed.

For example, in Patent Document 1, the basic resin particles are styrene resin particles that can be obtained by graft polymerization of a high cis polybutadiene and a styrene monomer, and the blowing agent contains n-pentane as a main component, Disclosed is a styrenic resin foam molded product, wherein the molded product after foaming has a density of 0.015 to 0.040 g / cm ³ , an average cell diameter of 60 to 300 μm, and a closed cell ratio of 50% or more. ing. According to Patent Document 1, with this configuration, it is said that the bubble refinement phenomenon of pre-expanded particles after completion of aging is improved, and a highly foamed foamed molded article having excellent elasticity and impact resistance is obtained. .

  In Patent Document 2, 85 to 99% by weight of a rubber-modified styrene resin in which rubber particles of a diene polymer are dispersed in a continuous phase of a styrene resin and 1% by weight of a volatile foaming agent having a boiling point of 80 ° C. or less. The weight average molecular weight of the continuous phase is 150,000 to 300,000, the graft ratio of the styrene resin to the diene polymer is 70% to 135%, and 25% There is disclosed a foamable rubber-modified styrenic resin composition characterized in that the degree of swelling of the gel content of the diene polymer in toluene at 12 ° C. is 12-25. According to Patent Document 2, by using a foamable resin composition having this configuration, a foamed molded article having a high foaming ratio, excellent impact resistance and flexibility, and good appearance can be obtained.

JP-A-7-90105 JP 11-147970 A

  As described above, rubber-modified polystyrene resin foam molded articles with improved impact resistance have been proposed so far. However, the degree of improvement in impact resistance of conventional foamed molded products is not satisfactory.

  Patent Documents 1 and 2 do not mention any technique for improving the oil resistance of the foam molded article.

  An object of the present invention is to provide foamed particles and foamed molded articles of rubber-modified polystyrene resin having favorable impact resistance and oil resistance, and foamable resin particles for producing the same. .

As means for solving the above problems, the present inventors provide the following inventions.
The first aspect of the present invention is
Expanded particles of a rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
The present invention relates to foamed particles of a rubber-modified polystyrene resin characterized by containing bubbles having an average diameter of 100 to 300 μm.

  Since the expanded particles of the present invention are excellent in impact resistance and oil resistance, they can be suitably used for the production of a resin foam molded article that requires these characteristics. The foamed particles of the present invention are also useful as a cushion material in a cushion body.

The second aspect of the present invention is
The present invention relates to a cushion body comprising a bag body and foamed particles of the rubber-modified polystyrene resin filled in the bag body.

  The cushion body of the present invention is hardly deformed because the foamed particles of the present invention having excellent impact resistance are used as a cushion material.

The third aspect of the present invention is
A foam-molded article of a rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
The present invention relates to a foam-molded article of a rubber-modified polystyrene resin characterized by containing bubbles having an average diameter of 100 to 300 μm.

  The foamed molded product of the present invention is excellent in impact resistance and oil resistance. For this reason, the foamed molded product of the present invention is useful for applications that require impact resistance and oil resistance, for example, transportation containers such as returnable boxes.

As for this invention 4th aspect,
A rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin, and a diene polymer rubber dispersed in the continuous phase;
Expandable particles of rubber-modified polystyrene resin containing a foaming agent,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
The diene polymer rubber relates to foamable particles of a rubber-modified polystyrene resin, wherein particles having an average particle diameter of 2 to 8 μm are formed.

  The expandable particles of the present invention can be used for the production of expanded particles and expanded molded articles having excellent impact resistance and oil resistance.

The fifth aspect of the present invention is
A method for producing expandable particles of the above rubber-modified polystyrene resin,
In the extruder, the molten rubber-modified polystyrene-based resin and the foaming agent are kneaded to form a resin foaming agent mixed melt, and a mixing and melting step,
And extruding the resin foaming agent mixed melt from the extruder into a cooling liquid.

  According to this method of the present invention, it is possible to form the expandable particles impregnated with the foaming agent in such a manner that relatively large bubbles (preferably an average cell diameter of 100 to 300 μm) are easily formed during foaming.

The sixth aspect of the present invention is
The present invention relates to a method for producing foamed particles of a rubber-modified polystyrene resin, which includes a foaming step of foaming the foamable particles of the rubber-modified polystyrene resin.

  According to this method of the present invention, it is possible to produce rubber-modified polystyrene-based resin expanded particles having excellent impact resistance and oil resistance.

As for this invention 7th aspect,
A foaming step of foaming foamable particles of the rubber-modified polystyrene resin;
The present invention relates to a method for producing a foam-molded product of a rubber-modified polystyrene resin, comprising a molding step of molding foamed particles of a rubber-modified polystyrene resin obtained by the foaming step in-mold.

  According to this method of the present invention, it is possible to produce a rubber-modified polystyrene resin foam molded article having excellent impact resistance and oil resistance.

  ADVANTAGE OF THE INVENTION According to this invention, the foaming particle | grains and foaming molding of rubber-modified polystyrene resin provided with preferable impact resistance and oil resistance, and the foaming resin particle for manufacturing it are provided.

The perspective view which shows an example of the foaming resin molding container by this invention. Sectional drawing in the aa line of FIG. It is a figure which shows an example of the reinforcing material used with a foamed resin molding container, FIG. 3 a is a perspective view of the whole, FIG. 3 b is sectional drawing which follows the bb line | wire of FIG. The figure which shows the state which piled up the foamed resin molding container by this invention in multistage.

<Rubber-modified polystyrene resin>
In the present invention, the polystyrene resin is a resin containing a polymer obtained by polymerizing a styrene monomer, and may be a resin containing a polymer obtained by copolymerizing a styrene monomer and another monomer. . Examples of the styrene monomer include styrene monomers such as styrene, α-methyl styrene, vinyl toluene, ethyl styrene, i-propyl styrene, t-butyl styrene, dimethyl styrene, bromo styrene, and chloro styrene, or these And a mixture of these monomers. The styrenic monomer is preferably styrene only.

  Other monomers include, for example, (meth) acrylic acid (refers to acrylic acid or methacrylic acid; hereinafter the same), methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, ( (Meth) acrylic acid esters such as butyl (meth) acrylate and cetyl (meth) acrylate, alkyl maleates such as (meth) acrylonitrile, dimethyl maleate and diethyl maleate, dimethyl fumarate, diethyl fumarate and ethyl fumarate And alkyl fumarate, maleic anhydride, N-phenylmaleimide, (meth) acrylic acid and the like.

  The polystyrene-based resin may be a crosslinked polymer further containing a component derived from a crosslinking agent. Examples of the crosslinking agent include divinylbenzene, trivinylbenzene, divinyltoluene, divinylxylene, bis (vinylphenyl) methane, bis (vinylphenyl) ethane, bis (vinylphenyl) propane, bis (vinylphenyl) butane, and divinylnaphthalene. , Divinyl anthracene, divinyl biphenyl, and other bifunctional benzene rings, such as a compound in which a vinyl group is bonded directly, bisphenol A ethylene oxide adduct di (meth) acrylate, bisphenol A propylene oxide adduct di (meth) acrylate, etc. Examples include (poly) alkylene glycol di (meth) acrylate compounds such as (meth) acrylate, ethylene glycol di (meth) acrylate, and diethylene glycol di (meth) acrylate.

  The diene polymer rubber is a rubber formed by polymerizing a diene monomer such as 1,3-butadiene and isoprene (2-methyl-1,3-butadiene). The diene polymer rubber is a high cis diene polymer rubber containing 70% or more of 1,4 cis structure, and more preferably 80% or more, more preferably 90% or more of 1,4 cis structure. When the ratio of the 1,4 cis structure is within this range, the molecular crosslinking reaction due to heating hardly occurs, and flexible foamed particles and a foamed molded product can be obtained. A high cisdiene polymer rubber containing 70% or more of 1,4 cis structure is produced by a known production method. For example, it can be produced by polymerizing a diene monomer using an organoaluminum compound and a catalyst containing cobalt or nickel.

  The rubber-modified polystyrene resin used in the present invention includes a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase. Such a rubber-modified polystyrene resin is obtained by mixing the monomer constituting the polystyrene resin (the styrene monomer and, if necessary, the other monomer described above) in the presence of the diene polymer rubber. It can be produced by graft polymerization. Specific examples include the method described in Japanese Patent Publication No. 61-11965. This method is a method in which the monomer constituting the polystyrene resin is polymerized by a bulk polymerization method or a bulk-suspension two-stage polymerization method in the presence of a diene polymer rubber, and the diene polymer rubber And a graft polymer of polystyrene resin are formed. A preferred embodiment of this method is illustrated below.

  First, the diene polymer rubber and the monomer constituting the polystyrene resin are mixed, heated and melted to 60 to 80 ° C., further heated and stirred at 90 to 120 ° C. Bulk polymerization is performed until the polymerization rate reaches 10 to 40%. This process is called a prepolymerization process. During this process, the diene polymer rubber is dispersed in the form of particles by the action of stirring.

  The average particle diameter of particles formed by the diene polymer rubber in a rubber-modified polystyrene resin, which will be described later, can be achieved by appropriately adjusting the stirring conditions in this prepolymerization step.

  After completion of the prepolymerization step, bulk polymerization may be continued, or granular polymerization may be performed by suspending in an aqueous phase containing a suspending agent such as tricalcium phosphate. The polymerization is usually carried out to a polymerization rate close to 100%, but it may be recovered by an operation such as carrying out the polymerization to a low polymerization rate, for example, a polymerization rate of 50 to 80% and distilling off the unreacted monomer. This polymerization step after the prepolymerization step is called a main polymerization step.

If necessary, a recovery step is performed after the main polymerization step.
If necessary, after the main polymerization step or the recovery step, a heating step may be performed after the heating is continued in a state where substantially no monomer is present. You may perform a post-heating process in presence of an organic peroxide as needed. Examples of the organic peroxide include dicumyl peroxide, ditertiarybutyl peroxide, 2,5-dimethyl-2,5 (dibutyltertiarybutylperoxy) hexane, and the amount used thereof is the diene heavy compound. When the total weight of the combined rubber and the monomer is 100 parts, it can be 0.01 to 0.50 part.

  The characteristics of the rubber-modified polystyrene resin, such as the graft ratio of the diene polymer rubber with the polystyrene resin and the gel swelling degree of the diene polymer rubber, as defined in the present invention, are the polymerization rate in the main polymerization step, It can be controlled by appropriately adjusting the ultimate polymerization rate, the treatment temperature in the post-heating step, the treatment time, the amount of organic peroxide to be decomposed in the post-heating step, and the like.

  When the rubber-modified polystyrene resin obtained as described above is subjected to bulk polymerization, it can be pelletized by performing an extrusion step after the above treatment. When the main polymerization step and subsequent steps are performed by suspension polymerization, the slurry is dehydrated, the beads are collected and dried. The beads may be used as they are, or may be extruded into pellets by an extruder.

  The rubber-modified polystyrene resin used in the present invention is 10 parts by weight or less with respect to 100 parts by weight of the rubber-modified polystyrene resin within a range that does not interfere with the object of the present invention. In this range, it may be added by melting and mixing. Such further rubbery materials include styrene-butadiene block copolymers, styrene-butadiene random copolymers, styrene-isoprene block copolymers, styrene-isoprene random copolymers, low cis-polybutadiene and hydrogenated products thereof. And other copolymers.

Commercially available rubber-modified polystyrene resins having the characteristics defined in the present invention may be used.
The molecular weight of the styrenic resin in the rubber-modified polystyrene resin used in the present invention is not particularly limited. Typically, the rubber content is removed by dissolving the rubber-modified polystyrene resin in chloroform and filtering to be contained in the solution. When the Z + 1 average molecular weight of the resin (considered to be a styrene resin forming a continuous phase) is measured, it is 400,000 or more and 800,000 or less, preferably 400,000 or more and 700,000 or less. When the styrenic resin has this molecular weight, it is possible to prevent the bubble film from being broken by heating during molding, and a foamed molded article having excellent buffering and chemical resistance can be obtained.

  The content of the diene polymer rubber in the rubber-modified polystyrene resin used in the present invention is preferably 9 to 15% by mass. As described in the examples, the content of the diene polymer rubber is obtained by dissolving a rubber-modified polystyrene resin in chloroform, adding a certain amount of iodine monochloride / carbon tetrachloride solution and leaving it in the dark for a predetermined time, Potassium iodide solution was added, excess iodine monochloride was titrated with a known concentration of sodium thiosulfate / ethanol aqueous solution, the amount of added iodine monochloride was determined, the rubber mass was calculated from the amount of iodine monochloride, and rubber-modified polystyrene The rubber mass relative to the mass of the resin is determined as the rubber content (% by mass). When the content of the diene polymer rubber is 9% by mass or more, the effect of improving the impact resistance and oil resistance by the diene polymer rubber is sufficiently exhibited. The double bond contained in the rubber component causes discoloration and deterioration, that is, causes deterioration in weather resistance. However, if the content of the diene polymer rubber is 15% by mass or less, it is included in the rubber-modified polystyrene resin. There are sufficiently few double bonds, and it is possible to avoid deterioration in weather resistance due to double bonds contained in the rubber component.

  In the rubber-modified polystyrene resin used in the present invention, the diene polymer rubber preferably forms particles. The particles of the diene polymer rubber may have an occlusion structure or a salami structure. The occlusion structure is a structure in which polystyrene resin particles are singly present inside the diene polymer rubber particles, and the salami structure is a plurality of small polystyrene resin particles inside the diene polymer rubber particles. Indicates a structure in which a plurality of are included.

  In a more preferred embodiment, the diene polymer rubber forms particles having an average particle diameter of 2 to 8 μm in the rubber-modified polystyrene resin used in the present invention. The diene polymer rubber particles in the rubber-modified polystyrene resin spread thinly in the film surface direction inside the resin film constituting the partition between the bubbles when the resin foam particles or the foam molded article is formed, It is thought that impact resistance, flexibility, and oil resistance are imparted to the expanded particles or the expanded molded body. When the average particle size of the diene polymer rubber particles is in this range in the rubber-modified polystyrene resin, sufficient impact resistance, flexibility, and oil resistance are imparted to the foamed particles or foamed molded product of the resin. preferable. The average particle diameter of the diene polymer rubber particles is calculated from morphological observation with a transmission electron microscope (TEM). Specifically, the average particle diameter can be determined by the procedure described in the examples.

The graft ratio of the diene polymer rubber with a polystyrene resin is preferably 137 to 160%. When the graft ratio is large, the affinity of the diene polymer rubber with the styrene resin is high, and the diene polymer rubber is likely to expand during foaming. On the other hand, if the graft ratio is too large, Since the double bond is insufficient, the stretchability and flexibility of the diene polymer rubber tend to deteriorate. By setting the graft ratio to 137 to 160%, the foamed particles or foamed molded body of the rubber-modified polystyrene resin is formed, and the inside of the resin film that forms the partition wall between the diene polymer rubber and the bubbles. It is thought that it is easy to spread thinly in the film surface direction and imparts impact resistance, flexibility and oil resistance to the foamed particles or the foamed molded product. The graft ratio is calculated by the following formula.
Graft rate (%) = 100 × (gel content rate−rubber content rate) / rubber content rate The method for calculating the rubber content rate is as described above.

A gel content rate can be calculated | required by the procedure as described in an Example. Specifically, a rubber-modified polystyrene resin is precisely weighed (W), 50% methyl ethyl ketone / 50% acetone mixed solution is added and dissolved in a volume ratio, and the solution is centrifuged to precipitate insolubles. The supernatant liquid is removed by nitriding to obtain an insoluble matter, the insoluble matter is dried, the mass G of the dried insoluble matter is measured, and the gel content can be obtained by the following formula.
Gel content (mass%) = (G / W) × 100

In the rubber-modified polystyrene resin used in the present invention, the gel swelling degree of the diene polymer rubber is preferably 13-20. The degree of gel swelling means the ease of swelling of the diene polymer rubber with toluene, and reflects the high flexibility of the diene polymer rubber and the small number of double bonds in the rubber. The higher the degree of gel swelling, the higher the flexibility of the diene polymer rubber, so the diene polymer rubber tends to spread thinly in the film surface direction inside the resin film constituting the partition between the bubbles, It is thought that impact resistance, flexibility, and oil resistance are imparted to the foamed molded product. On the other hand, if the degree of gel swelling is too high, it means that there are too many double bonds in the diene polymer rubber, which causes deterioration of weather resistance. When the gel swelling degree of the diene polymer rubber in the rubber-modified polystyrene resin is 13 to 20, the foamed particles or the foamed molded body formed using the resin has sufficient impact resistance, flexibility, and oil resistance. It is considered to have high weather resistance and sufficient weather resistance. The degree of gel swelling is the swelling ratio of gel with toluene at room temperature of 25 ° C. The degree of gel swelling can be determined according to the method described in the examples. That is, a rubber-modified polystyrene resin is precisely weighed, a sufficient amount of toluene (25 ° C.) is added and dissolved, the solution is centrifuged to precipitate insolubles, and the supernatant is removed by decantation. The mass S of the insoluble matter swollen in is measured. The operation so far is performed at 25 ° C. Subsequently, after drying the insoluble matter swollen with toluene at 25 ° C., the dry mass D of the insoluble matter can be measured and determined as follows.
Swelling degree SI = S / D

  The rubber-modified polystyrene resin used in the present invention preferably has a residual monomer of preferably 1000 ppm or less, and more preferably 500 ppm or less. When the residual monomer is within this range, the heat resistance of the foamed molded product is further improved, the bubble film can be prevented from being broken during molding, and a foamed molded product having excellent impact resistance can be obtained.

  The melt index (MI) of the rubber-modified polystyrene resin used in the present invention is preferably 2 or more and 5 or less, and more preferably 3 or more and 4 or less. When the MI is within this range, a good foamed molded product that does not shrink or the like can be obtained even if the density of the foamed molded product is reduced. MI is a weight (g / 10 minutes) that flows from an orifice diameter of 2.09 mm in 10 minutes when a rubber-modified polystyrene resin is dissolved at 200 ° C. and a weight of 5 kg is applied.

  The Vicat softening point of the rubber-modified polystyrene resin used in the present invention is preferably 95 ° C. or lower, and more preferably 90 ° C. or lower. When the Vicat softening point is within this range, shrinkage during molding can be prevented.

<Expandable particles of rubber-modified polystyrene resin>
The foamable particles of the rubber-modified polystyrene resin of the present invention include the above-described rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase, and a foaming agent. Including. The foamable particles according to the present invention can be foamed to produce foamed resin particles and foamed resin molded articles having impact resistance and oil resistance.

  The particle diameter of the expandable particles of the present invention is not particularly limited, but the average particle diameter is preferably 0.2 mm or more and 4 mm or less, and more preferably 0.5 mm or more and 2.5 mm or less. About the said average particle diameter, it classifies using a sieve of JISZ8801-1 standard sieve opening, Based on a cumulative weight distribution curve, the particle diameter from which cumulative mass becomes 50% is made into the average particle diameter.

  In the present invention, the foaming agent is not particularly limited, and any known one can be used. As the foaming agent, a physical foaming agent or a chemical foaming agent can be used, and two or more physical foaming agents and / or chemical foaming agents may be used in combination. A particularly preferred foaming agent is a foaming agent containing at least a physical foaming agent, and may further contain a chemical foaming agent.

  As the physical foaming agent, in particular, a gaseous or liquid organic compound having a boiling point below the softening point of the styrene resin and normal pressure is suitable. For example, hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, cyclopentadiene, n-hexane, petroleum ether, ketones such as acetone and methyl ethyl ketone, methanol, ethanol, isopropyl alcohol, etc. Low boiling point ether compounds such as alcohols, dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, halogen-containing hydrocarbons such as trichloromonofluoromethane, dichlorodifluoromethane, inorganic gases such as carbon dioxide, nitrogen, ammonia, etc. Can be mentioned. These physical foaming agents may be used alone or in combination of two or more. Among these, it is preferable to use hydrocarbons from the viewpoint of preventing the destruction of the ozone layer and from the viewpoint of quickly replacing with the air and suppressing the time-dependent change of the foamed molded product. Of the hydrocarbons, hydrocarbons having a boiling point of −45 to + 40 ° C. are more preferable, and propane, n-butane, isobutane, n-pentane, isopentane and the like are more preferable. A particularly preferred physical blowing agent is n-pentane or isopentane, which may be a mixture of n-pentane and isopentane. The mixing mass ratio is not particularly limited.

  The content of the physical foaming agent is preferably in the range of 3 to 15% by mass with respect to the entire foamable particles. If it is 3 mass% or more, a foamed molded article having a desired density can be easily obtained from the expandable particles. In addition, the effect of increasing the secondary foaming force at the time of in-mold foam molding is sufficient, and the appearance of the foam molded product tends to be good. If it is 15 mass% or less, the time which the cooling process in the manufacturing process of a foaming molding requires will be short enough and productivity is good. A more preferable content is 4 to 12% by mass, and a still more preferable content is 4 to 10% by mass.

  Examples of the chemical foaming agent include azodicarbonamide, dinitrosopentamethylenetetramine, hydrazoyl dicarbonamide, sodium bicarbonate, and sodium bicarbonate citric acid derivative.

  A foaming aid may be used in combination with a foaming agent. Examples of the foaming aid include diisobutyl adipate, styrene, toluene, cyclohexane, and ethylbenzene.

  The foamable particles may contain other additives as necessary. Other additives include plasticizers, flame retardants, flame retardant aids, antistatic agents, spreading agents, bubble regulators, infrared attenuators, fillers, colorants, weathering agents, anti-aging agents, lubricants, anti-proofing agents. Examples include clouding agents, fragrances, dyes, and pigments.

  Plasticizers include aromatic hydrocarbons such as styrene, toluene and xylene, aliphatic hydrocarbons such as cyclohexane, hexane and heptane, adipic acid esters such as diisobutyl adipate, dioctyl adipate and diisononyl adipate, and glycerin diacetomono Examples thereof include glycerin fatty acid esters such as laurate, dioctyl phthalate, diisononyl phthalate, diisobutyl phthalate and the like, phthalic acid esters such as liquid paraffin, and white oil.

  Flame retardants include tetrabromocyclooctane, hexabromocyclododecane, trisdibromopropyl phosphate, tetrabromobisphenol A, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis. (2,3-dibromopropyl ether) and the like.

  Examples of flame retardant aids include 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, dicumyl peroxide, cumene hydroperoxide organic peroxide, biscumyl, etc. Is mentioned.

  Examples of the antistatic agent include polyoxyethylene alkylphenol ether, stearic acid monoglyceride, polyethylene glycol, glycerin, propylene glycol and the like.

  Examples of the spreading agent include polybutene, polyethylene glycol, glycerin, silicone oil, propylene glycol and the like.

  As the air conditioner, talc, mica, silica, diatomaceous earth, aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, potassium sulfate, Barium sulfate, glass beads, polytetrafluoroethylene, tribasic calcium phosphate, magnesium pyrophosphate, zinc stearate, magnesium stearate and other metal soaps, ethylene bis stearamide, bisamide compounds such as methylene bis stearamide, stearamide Amide compounds such as 12-hydroxystearic acid amide, and fatty acid glycerides such as stearic acid triglyceride and stearic acid monoglyceride.

  Examples of the lubricant include metal soaps such as zinc stearate and magnesium stearate, bisamide compounds such as ethylenebisstearic acid amide and methylenebisstearic acid amide, amide compounds such as stearic acid amide and 12-hydroxystearic acid amide, stearic acid triglyceride, Examples include fatty acid glycerides such as stearic acid monoglyceride and hydroxystearic acid triglyceride, polyethylene wax, liquid paraffin, and white oil.

  The infrared attenuating agent may be an infrared reflecting material, an infrared absorbing material, or both of them, and can be added as long as the object of the present invention is not impaired. Examples include metal powders such as aluminum, copper, silver, and gold, carbon materials such as graphite, graphene, activated carbon, and carbon black, metal oxides such as titanium oxide and tin oxide, or silica, scaly Examples include mica.

Examples of the method for producing expandable particles include a melt extrusion method and a suspension method.
(1) Melt extrusion method
In the extruder, kneading the melted rubber-modified polystyrene resin and the foaming agent to form a resin foaming agent mixed melt, a mixing and melting step,
At least an extrusion step of extruding and cooling the resin foaming agent mixed melt from the extruder into a cooling liquid.

  The present inventors have surprisingly found that expandable particles produced by a melt extrusion method tend to form relatively large bubbles during foaming.

  In the mixing and melting step, a foaming agent is preferably press-fitted into the melted rubber-modified polystyrene resin and kneaded in an extruder to form a resin foaming agent mixed melt.

  More specifically, in the melt extrusion method, as the mixing and melting step, a rubber-modified polystyrene resin is supplied to an extruder, a foaming agent is press-fitted and kneaded into the resin melted in the extruder, and then the extrusion process is performed. As a process, a foamed particle is obtained by extruding a molten resin containing a foaming agent into a cooling liquid from a small hole of a die attached to the tip of the extruder and solidifying by cooling.

In the extrusion process, a method of directly extruding into a cooling liquid from a small hole of a die, cutting the extrudate with a rotary blade immediately after the extrusion, and cooling the cut particles in the cooling liquid is called a hot cut method. . According to the hot cut method, there is an advantage that substantially spherical expandable particles can be obtained.
A typical example of the cooling liquid is water.

  In the hot cut method, for example, the following manufacturing apparatus can be used. That is, an extruder, a die having a large number of small holes attached to the tip of the extruder, a raw material supply hopper for charging the raw material into the extruder, and press-fitting the foaming agent through the foaming agent supply port into the molten resin in the extruder A high pressure pump, a cutting chamber in which cooling liquid is brought into contact with the resin discharge surface in which a small hole of the die is formed, and the cooling liquid is circulated and supplied into the chamber, and is extruded from the small hole of the die. A cutter (high-speed rotary blade) that is rotatably provided in the cutting chamber so that the resin can be cut, and the foamable particles carried along with the flow of the cooling liquid from the cutting chamber are separated from the cooling liquid and dried. A solid-liquid separation function dryer for obtaining expandable particles, a tank for storing the cooling liquid separated by the solid-liquid separation function dryer, and a high-pressure pot for sending the cooling liquid in the tank to the cutting chamber. Flop and include manufacturing apparatus and a storage container for storing the dried effervescent grains at the solid-liquid separation function dryer.

  An example of a procedure for producing expandable particles using the production apparatus will be described. First, a raw material rubber-modified polystyrene resin is introduced into an extruder from a raw material supply hopper. The raw rubber-modified polystyrene resin may be put into a pellet or granule and mixed well in advance and then fed from one raw material supply hopper, or supplied for each lot when multiple lots are used, for example. A plurality of raw material supply hoppers whose amounts are adjusted 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 means such as magnetic sorting, sieving, specific gravity sorting, and air blowing sorting. It is preferable to keep it.

  After supplying the raw material into the extruder, the rubber-modified polystyrene resin is heated and melted, and while the molten resin is transferred to the die side, the foaming agent is injected from the foaming agent supply port with a high-pressure pump and mixed with the molten resin. Then, through a foreign matter removing screen provided in the extruder as necessary, the melt is moved to the tip side while further kneading, and the small hole of the die attached to the tip of the extruder with the melt added with the blowing agent Extrude from.

  The resin discharge surface in which the small hole of the die is drilled is disposed in the cutting chamber in which the cooling liquid is circulated and supplied into the chamber, and the resin extruded from the small hole of the die can be cut in the cutting chamber. A cutter is rotatably provided. When extruding the melt with the blowing agent added through a small hole in the die attached to the tip of the extruder, the melt is cut into granules and simultaneously cooled by contact with the cooling liquid, solidifying while suppressing foaming. To become expandable particles.

  In addition, when adding another additive to an expandable particle, although an addition time is not specifically limited, Preferably it is added to an extruder with a raw material.

(2) Suspension method Impregnation of a foaming agent into a rubber-modified polystyrene resin by the suspension method is a state in which the rubber-modified polystyrene resin is suspended in an aqueous medium during or after the polymerization of the rubber-modified polystyrene resin in a pressure-resistant airtight container. In this method, the foaming agent is press-fitted.

  The impregnation of the foaming agent using an aqueous medium in the suspension method is usually performed at a temperature of 100 ° C to 150 ° C, preferably 110 ° C to 130 ° C.

In the suspension method, the impregnation time of the foaming agent varies depending on the size (volume) of the raw rubber-modified polystyrene resin, and is not particularly limited. For example, in the case of particles having a particle volume of about 1.0 mm ³ , it is 4 hours or more, preferably 6 hours or more. If the impregnation time is short, an unimpregnated part called a core is formed in the center part of the resin particle, and when the foamed particle is formed, the foamed part and the unfoamed part are mixed in one foamed particle. The obtained foamed molded product may not have the desired physical properties.

  In the suspension method, it can be added to the expandable particles by including the above-mentioned other additives as necessary in the aqueous medium.

  A suspension stabilizer may be included in the aqueous medium to stabilize the dispersion of monomer droplets and seed particles. The suspension stabilizer is not particularly limited as long as it is conventionally used for monomer suspension polymerization.

<Rubber particles of rubber-modified polystyrene resin>
The expanded particles of the present invention are
Expanded particles of a rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
It contains air bubbles having an average diameter of 100 to 300 μm.

  The expanded particles of the present invention can be produced by expanding (pre-expanding) the expandable particles of the present invention. The foamed particles of the present invention can be used not only as pre-foamed particles for producing the foamed molded product of the present invention, which will be described later, but also as a cushion material for the cushioned body of the present invention.

  The rubber-modified polystyrene resin contained in the expanded particles of the present invention can be the same as the rubber-modified polystyrene resin in the expandable particles of the present invention. However, the shape of the diene polymer rubber in the rubber-modified polystyrene resin is different before and after foaming. In the state before foaming, that is, when the diene polymer rubber having the above particle shape is contained in the rubber-modified polystyrene resin in the foamable particles of the present invention, the foamable particles are obtained by foaming. In the expanded particles, the diene polymer rubber is stretched and spreads into a thin sheet. As a result, the sheet-like diene polymer rubber spreads in the direction of the film surface inside the resin film that forms the partition walls between the bubbles, and the foam particles or foam molded article have impact resistance, flexibility, and oil resistance. It is thought to grant.

  The expanded particles of the present invention are characterized by containing bubbles having an average diameter of 100 to 300 μm. Assuming that the size and expansion ratio of the expanded particles are the same, the smaller the bubble diameter in the expanded particles, the thinner the partition between the bubbles, and the lower the impact resistance and oil resistance. In the foamed particles of the present invention, when the average diameter of the bubbles (hereinafter sometimes referred to as “average bubble diameter”) is 100 μm or more, the partition walls between the bubbles are sufficiently thick, and the impact resistance and oil resistance are excellent. On the other hand, even if the bubble diameter is too large, the impact resistance of the bubbles tends to be poor. The expanded particles of the present invention have sufficient impact resistance when the average cell diameter is 300 μm or less. The average cell diameter is more preferably 110 to 300 μm, more preferably 130 to 300 μm, and more preferably 170 to 300 μm.

Here, the average bubble diameter can be measured according to the test method of ASTM D3576-77.
Specifically, a cross section of the expanded particles is obtained from an arbitrary portion of the expanded particles using a razor blade. An image obtained by enlarging (for example, enlarging by 30 times) the cut surface using a scanning electron microscope (JSM-6360LV manufactured by NEC Corporation) is created.

Next, a straight line of 60 mm is drawn at an arbitrary position in the cross section of the expanded particle on the image of the cut surface. The number of bubbles on the straight line is counted, and the average chord length (t) of the bubbles is calculated by the following equation.
Average chord length t (mm) = 60 / (number of bubbles × magnification multiple of image)

  When drawing a straight line, the straight line should be penetrated as much as possible without making point contact with the bubbles. Also, if some of the bubbles come into point contact with a straight line, this bubble is included in the number of bubbles, and if both ends of the straight line are located in the bubble without penetrating the bubbles Includes the bubbles in which both ends of the straight line are located in the number of bubbles.

The average bubble diameter (D) of this bubble is calculated by the following formula.
Average bubble diameter D (mm) = t / 0.616
The above operation is performed with N number of 5 or more, and the average value is defined as the average bubble diameter.

  The expanded particles of the present invention themselves have high impact resistance and oil resistance. In addition, the foamed molded product obtained by molding the foamed particles of the present invention also has high impact resistance and oil resistance. These advantageous properties of the expanded particles of the present invention are caused by a combination of the above-described effects based on the properties of the rubber-modified polystyrene resin and the above-described effects based on the range of the average cell diameter.

  The method for producing the expanded particles by foaming the expandable particles of the present invention is not particularly limited. Typically, the expandable particles of the present invention are accommodated in a pre-expanding apparatus, and water vapor is contained in the apparatus. This can be done by press-fitting.

For example, the pressure of the water vapor is preferably 0.03 to 0.07 MPa, more preferably 0.04 to 0.06 MPa. In the present invention, the pressure means a gauge pressure. The heating time is preferably 60 to 180 seconds, more preferably 90 to 120 seconds.
The above average bubble diameter can be achieved by appropriately adjusting the pressure of water vapor and the heating time.

  The particle diameter of the expanded particles of the present invention is not particularly limited, but the average particle diameter is preferably 0.5 mm or more and 15 mm or less, more preferably 2 mm or more and 10 mm or less. About the said average particle diameter, it classifies using a sieve of JISZ8801-1 standard sieve opening, Based on a cumulative weight distribution curve, the particle diameter from which cumulative mass becomes 50% is made into the average particle diameter.

The expanded particles of the present invention preferably have a flatness of 0.6 to 0.8. Here, the flatness is calculated by the following method from the short diameter and long diameter of the expanded particles.
Flatness = average short diameter of expanded particles / average long diameter of expanded particles

  The average minor axis and average major axis of the foamed particles can be calculated as an average value by measuring the minor axis and major axis of an appropriate number (for example, 50 or more) of the foamed particles.

  When the flatness is in the above range, it is excellent in immobilization of an object when used as a cushion core material while maintaining good filling of the foamed particles into the mold during molding.

The bulk density of the expanded beads of the present invention is preferably in a range of 0.010~0.100g / cm ^3, more preferably in the range of 0.012~0.050g / cm ^3, 0.014~0 More preferably within the range of 0.025 g / cm ³ .
The bulk expansion ratio of the expanded particles of the present invention is preferably 10 to 100 times, more preferably 20 to 80 times, and even more preferably 40 to 70 times.

  In the present invention, the bulk density of the expanded particles refers to those measured in accordance with JIS K6911: 1995 “General Test Method for Thermosetting Plastics”. For example, it can be measured as follows.

Method for measuring the bulk density of expanded particles:
The mass (W) g of the expanded particles is weighed to the second decimal place. Next, the foamed particles weighed in the graduated cylinder are filled by natural dropping, and the volume (V) cm ³ of the foamed particles dropped in the graduated cylinder is measured using an apparent density measuring instrument in accordance with JIS K6911. . Then, the bulk density of the expanded particles is obtained 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 expanded particles is a numerical value calculated by the following formula.
Bulk foaming factor = 1 / bulk density (g / cm ³ )

<Foamed molded product of rubber-modified polystyrene resin>
The foamed molded article of the present invention is
A foam-molded article of a rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
It contains air bubbles having an average diameter of 100 to 300 μm.

  The foamed molded product of the present invention can be produced by a molding process in which the foamed particles of the present invention are molded in-mold. Specifically, in the molding step, the above-mentioned foamed particles of the present invention are filled in a closed mold having a large number of small holes, heated and foamed with a heat medium (for example, pressurized steam), and the space between the foamed particles. In this step, the voids are filled and the foamed particles are integrated by fusing each other. At that time, the density of the foamed molded product can be adjusted, for example, by adjusting the filling amount of the foamed particles in the mold.

  Heating foaming can be performed, for example, by heating for 5 to 50 seconds with a heat medium of 110 to 150 ° C. Under these conditions, good fusing property between the expanded particles can be secured. More preferably, the heat-foaming molding can be performed by heating for 10 to 50 seconds with a heating medium (for example, water vapor) at a molding vapor pressure (gauge pressure) of 0.06 to 0.08 MPa and 90 to 120 ° C. .

  The rubber-modified polystyrene resin contained in the expanded particles of the present invention can be the same as the rubber-modified polystyrene resin in the expandable particles of the present invention. However, the shape of the diene polymer rubber in the rubber-modified polystyrene resin is different before and after foaming. When the diene polymer rubber having the particle shape as described above is contained in the rubber-modified polystyrene resin in the foamable particles of the present invention, the foamable particles are foamed and molded in-mold. In the foamed molded product thus obtained, the diene polymer rubber is stretched and spreads into a thin sheet. As a result, the sheet-like diene polymer rubber spreads in the film surface direction inside the resin film constituting the partition between the bubbles, and it is considered that the foam molded article is given impact resistance, flexibility and oil resistance. It is done.

  In the foamed molded article of the present invention, the average cell diameter is 100 to 300 μm. If the size and expansion ratio of the foamed molded product are the same, the smaller the bubble diameter in the foamed molded product, the thinner the partition between the bubbles, and the lower the impact resistance and oil resistance. In the foamed molded product of the present invention, when the average cell diameter is 100 μm or more, the partition walls between the cells are sufficiently thick, and the impact resistance and oil resistance are excellent. On the other hand, even if the bubble diameter is too large, the impact resistance of the bubbles tends to be poor. The foamed molded article of the present invention has sufficient impact resistance when the average cell diameter is 300 μm or less. The average cell diameter is more preferably 130 to 300 μm, more preferably 150 to 300 μm, and more preferably 200 to 300 μm.

  Here, the average bubble diameter can be measured according to the test method of ASTM D3576-77. Specifically, a cross section of the foam molded body is obtained from an arbitrary portion of the foam molded body using a razor blade. An image obtained by enlarging (for example, enlarging by 30 times) the cut surface using a scanning electron microscope (JSM-6360LV manufactured by NEC Corporation) is created. Using this image, the average chord length and the average cell diameter are determined according to the same procedure as described for the average cell diameter of the expanded particles. N number is 5 or more, and the average value is the average bubble diameter.

  The foamed molded product of the present invention has high impact resistance and oil resistance. These advantageous properties of the foamed molded product of the present invention are caused by the combination of the above-described effect due to the properties of the rubber-modified polystyrene resin and the above-described effect due to the range of the average cell diameter.

The density of the foamed molded article of the present invention is preferably in a range of 0.010~0.100g / cm ^3, more preferably in the range of 0.012~0.050g / cm ^3, 0.014~0.025g More preferably within the range of / cm ³ .

  The expansion ratio of the foamed molded product of the present invention is preferably 10 to 100 times, more preferably 20 to 80 times, and even more preferably 40 to 70 times.

<Density of foam molding>
In the present invention, the density of the foamed molded product is a density measured by the method described in JIS K7122: 1999 “Measurement of foamed plastic and rubber-apparent density”, and specifically, it can be measured by the following method. it can.

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.

<Foaming multiple>
The “foaming multiple” of the foamed molded product is a numerical value calculated by the following equation.
Foaming factor = 1 / density (g / cm ³ )

  In the embodiment in which the foamed molded article of the present invention is composed of thermally fused foamed particles, the fusion rate between the foamed particles is preferably 90% or more. The fusion rate is expressed as a percentage of the number of foam particles broken inside the particles out of the total number of foam particles appearing on the cross-section when the foam molded body is bent and broken. is there. Specifically, the fusion rate can be measured by the following procedure. Prepare a 400 mm x 300 mm x 50 mm rectangular foam molded body sample, and use a cutter knife to create a cutting line with a depth of about 5 mm along the line connecting the centers of a pair of long sides of one of the 400 mm x 300 mm faces. Put in. Thereafter, the foamed molded product is manually divided into two along the cut line. Regarding the expanded particles in the fracture surface, the number of all particles (A) and the number of particles broken within the particles (B) are counted in an arbitrary range of 100 to 150. A value obtained by substituting the result into the formula [(B) / (A)] × 100 is defined as a fusion rate (%).

<Cushion body>
Further embodiments of the present invention are:
A bag,
The present invention relates to a cushion body comprising the foamed particles of the present invention filled in the bag body.

  Since the foamed particles of the present invention are excellent in impact resistance as described above, the cushion body of the present invention containing the foamed particles as a cushioning material has an effect that it is hardly deformed even when used for a long period of time. The cushion body of the present invention having this effect is particularly useful when used in a mode in which a load is applied to the cushion body, such as a bed, mattress, pillow, cushion, chair or the like.

  The foamed particles of the present invention filled in the cushion body preferably contain a lubricant for promoting flow. Specific examples of the lubricant are as described for the expandable particles. This lubricant functions to suppress noise generated by rubbing when the foamed particles flow. Examples of the content of the lubricant include 0.4 to 1.5 parts by weight per 100 parts by weight of the expanded particles of the present invention.

  The bag body may or may not have elasticity, but preferably has elasticity. Examples of stretchable bags include 30 to 300% stretchable bags. As the material having elasticity, for example, spandex (polyurethane elastic yarn) having elasticity is most preferable. Stretchability can be determined by the following method.

A test piece having a tensile interval of 10 cm and a width of 2.5 cm is stretched at a speed of 30 cm / min using a Tensilon universal testing machine UCT-10T (manufactured by ORIENTEC CORPORATION), and the elongation at a load of 9.8 N is measured. This measurement is performed in the vertical direction and the horizontal direction of the test piece, and the average value of the elongation is taken as the elasticity.
Elongation (%) = {9.8 specimen length at load of 9.8 N (cm) −10} ÷ 10 × 100

  If the said bag is used, there exist the following effects. That is, by using a stretchable material for the bag body, when a part of the cushion body is compressed, the filled particles move from the compression site to another site, and the volume of the moved particles is reduced to the other volume. Since it can accept | permit when the bag body located in a site | part extends and deform | transforms, the tolerance | permissible_range of a movement of particle | grains can be enlarged more. The synergistic effect of these effects of the foamed particles and the bag of the present invention can provide a more pleasant cushion body.

  In the cushion body of the present invention, it is preferable that the foamed particles are enclosed so as to have a volume 1.1 to 3.5 times the inner volume of the stretchable bag body. By encapsulating foam particles having a volume larger than the inner volume as a filler in a bag made of a stretchable material, it is possible to further improve the sitting comfort and the effect of preventing deformation of the cushion. Here, when the foamed particles are less than 1.1 times the internal volume of the bag, a feeling of bottoming is generated at the time of sitting, which is not preferable, and when it is more than 3.5 times, the seating comfort is deteriorated. A more preferable range is 1.3 to 2.5 times. Here, the filling magnification indicates a multiple of the bulk volume of the foam particles to be filled when the inner volume of the bag is 1. The inner volume of the bag body is the same size as the cushion body bag body, cut out from a 0.05 mm thick polyethylene bag made by Yamagics, and air is applied to the polyethylene bag at an internal pressure of 0.01 MPa. After that, the air in the bag body is put into a graduated cylinder submerged in water, and the amount of air can be set as the inner volume of the bag body.

  In addition, double fasteners that can be opened and closed to prevent leakage of these fillers from the bag body are provided in order to suppress the generation of abnormal noise, to produce a suitable feel, and to satisfy the permanent cushioning properties. It is a more preferable embodiment to have a structure. It is also effective to make the bag itself a double structure.

  Furthermore, it is also possible to adopt a configuration in which a plurality of bags each containing the foamed particles of the present invention are contained in one large bag. In this case, the fillers in the plurality of bags may have different tactile sensations.

<Transport container>
Since the foamed molded article of the present invention is excellent in impact resistance and oil resistance, it is suitable for use as a transport container that may be subjected to impact and may come into contact with edible oil or machine oil. Yes. That is, the foamed molded product of the present invention is preferably in the form of a transport container. The foamed molded product of the present invention which is in the form of a transport container may be referred to as “the transport container of the present invention” in the following description.

  Since the transport container of the present invention is excellent in impact resistance and oil resistance, it is particularly suitable for use as a returnable box that is used repeatedly over a long period of time.

  The transport container of a preferred embodiment of the present invention is more preferably a foamed molded product container of the present invention in which a stepped portion as a handle is formed on the outer surface of the peripheral wall, and at least the upper end region portion of the stepped portion. Is covered with a reinforcing material formed in advance in its shape, and a portion continuous with the covering surface of the reinforcing material is embedded in the peripheral wall.

More preferably, the upper end surface of the stepped portion is an inclined surface whose outer surface becomes lower from the outer surface of the peripheral wall toward the inner side.
It is preferable that the reinforcing material is provided with a convex portion or a concave portion serving as a locking portion to the mold.

  The reinforcing material includes a surface region portion covering the upper end region portion of the step portion of the container of the foam molded article of the present invention, a peripheral surface portion that enters the peripheral wall of the container from the surface region portion, and an end portion of the peripheral surface portion. It is preferable that the skirt portion is widened, and the peripheral surface portion and the skirt portion are embedded in the peripheral wall.

The resin type of the foamed molded product of the present invention and the resin type of the reinforcing material are preferably the same rubber-modified polystyrene resin.
This preferred embodiment of the transport container of the present invention will be described more specifically with reference to the drawings.

  Hereinafter, preferred embodiments of the transport container of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of the transport container of the present invention, and FIG. 2 is a cross-sectional view taken along the line aa of FIG. FIG. 3 shows an example of a reinforcing material used in the transport container of the present invention. FIG. 4 shows a state in which shipping containers according to a preferred embodiment of the present invention are stacked.

  In this example, the transport container 1 is composed of a container body 2 and a lid 3 which are the above-described foamed molded article of the present invention. The container body 2 has a stepped portion 22 as a handle on the outer surface of two opposing side walls 21 constituting a peripheral wall (side peripheral wall) (in FIG. 1, only the stepped portion 22 formed on one side wall 21 is provided. Indicated). The step portion 22 includes an upper end surface 23, left and right side wall portions 24 and 25, and a bottom wall portion 26, and the container bottom surface 27 side of the step portion 22 is open downward. Further, the periphery of the bottom surface of the container body 2 is a notch 28.

  And the upper end area part of the said level | step-difference part 22 in the container main body 2, ie, the upper end surface 23 of the level | step-difference part 22, the upper and lower side wall parts 24 and 25 following the upper-end surface 23 vicinity of the bottom wall part 26, and the side wall 21 The peripheral portion is covered with the reinforcing material 4 referred to in the present invention.

  In this example, the reinforcing material 4 is formed by molding a non-foamed sheet of polystyrene resin in advance, and the thickness is about 0.3 mm. As shown in FIG. 3, the reinforcing member 4 includes a surface region portion 41 that is shaped along the upper end region portion of the step portion 22 formed in the container body 2, a peripheral surface portion 42 that enters the rear from the periphery thereof, The skirt portion 43 extends from the rear end of the peripheral surface portion 42 in substantially the same direction as the surface region portion 41.

  In FIG. 3, 41a is a portion covering the upper end surface 23 of the surface region portion 41, 41b is a portion covering the left and right side walls 24, 25, 41c is a portion covering the bottom wall portion 26, and 41d. Is a portion covering the peripheral portion of the side wall 21. Further, in this example, a concave hole 41e is formed in the portion 41a and is used for temporarily fixing in a mold as will be described later. As shown in FIG. 2, the other part excluding the surface region part 41, that is, the peripheral surface part 42 entering the rear from the periphery of the surface region part 41 and the skirt part 43 subsequent thereto are formed in the side wall 21 of the container body 2. The reinforcing material 4 is integrated with the container body 2 in a state of being embedded in the container body 2.

  The lid 3 has a convex portion (not shown) that fits in the container main body 2 on the back surface, a surrounding bank portion 31 corresponding to the notch 28 on the bottom surface of the container main body 2, and a peripheral wall (side A stepped portion 33 as a handle is formed on the outer surface of the two opposing side walls 32 constituting the peripheral wall. In this example, the step portion 33 is not specially coated, but a reinforcing material may be provided in the same manner as the step portion 22 of the container body 2.

  Since the transport container 1 according to a preferred embodiment of the present invention is covered with the reinforcing material 4 at the stepped portion thereof, as shown in FIG. 4, when stacked in multiple stages or transported in stages. Even when an operator puts a palm or a finger on the stepped portion, particularly the upper end region portion when separating the containers 1 individually, it is possible to effectively avoid the destruction or breakage of the portion. The reinforcing member 4 is in a state in which the peripheral surface portion 42 and the skirt portion 43 subsequent thereto are embedded in the side wall 21 of the container body 2, so that the reinforcing member 4 can be used even if the container body 2 is handled somewhat roughly. No peeling occurs. Therefore, repeated use over a long period of time as a returnable box or the like can be performed in a stable state.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these. Each operation described below was performed at a room temperature of 23 ° C. unless otherwise specified.
<Example 1>
(Manufacture of expandable rubber-modified polystyrene resin particles)
The base resin is a high cis structure in which the ratio of 1,4 cis structure of diene rubber particles is 93%, the rubber content is 12% by mass, the average particle diameter of the rubber particles is 5 μm, the graft ratio of styrene is 140%, the gel swelling A rubber-modified polystyrene resin having a degree of 16 was used. A mixture of 100 parts by mass of this rubber-modified polystyrene resin and 0.5 parts by mass of Polyslen ES405 (manufactured by Eiwa Kasei Co., Ltd.) as a chemical foaming agent was continuously supplied to a single screw extruder having a diameter of 90 mm at 150 kg per hour. As the temperature inside the extruder, the maximum temperature was set to 210 ° C., and after melting the resin, 6 parts by mass of pentane (isopentane: normal pentane = 20: 80 (mass ratio)) with respect to 100 parts by mass of the resin as a foaming agent. Was press-fitted from the middle of the extruder. The resin and foaming agent are kneaded and cooled in the extruder, the resin temperature at the tip of the extruder is kept at 180 ° C., the pressure at the resin introduction part of the die is kept at 15 MPa, the diameter is 0.6 mm, and the land length is 3 From the die having 200 small holes of 0.0 mm, the foaming agent-containing molten resin is extruded into a cutting chamber connected to the discharge side of this die and circulating water at 40 ° C. The extrudate was cut with a high-speed rotary cutter having a blade. While the cut particles were cooled with circulating water, they were conveyed to a particle separator, and the particles were separated from the circulating water. Further, the collected particles were dehydrated and dried to obtain expandable polystyrene resin particles. The obtained expandable polystyrene resin particles were free from deformation, whiskers, etc., and obtained expandable rubber-modified polystyrene resin particles having an approximately spherical shape and an average particle diameter of approximately 1.1 mm.

  The obtained foamed rubber-modified polystyrene resin particles were measured to be a high cis structure with a 1,4 cis structure ratio of 93%, a rubber content of 12% by mass, a styrene graft ratio of 140%, and a gel swelling of 16 Met.

10 kg of the foamable rubber-modified polystyrene resin particles were coated with 5 g of zinc stearate, 5 g of 12-hydroxystearic acid triglyceride, 5 g of stearic acid monoglyceride, and 5 g of polyethylene glycol. Subsequently, the expandable polystyrene resin particles were supplied to a cylindrical batch type pre-foaming machine and heated with water vapor having a blowing pressure of 0.05 MPa to obtain expanded particles. The obtained expanded particles had a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 202 μm, and a flatness of 0.66.

  When the obtained expanded particles were measured, the ratio of the 1,4 cis structure was a high cis structure of 93%, the rubber content was 12% by mass, the styrene grafting rate was 140%, and the gel swelling was 16.

Subsequently, the foamed particles obtained were allowed to stand for 24 hours in a room temperature atmosphere, and then the foamed particles were filled into a mold having a rectangular cavity of length 400 mm × width 300 mm × height 50 mm. Molding was performed under the conditions of a pressure of 0.07 MPa (gauge pressure), mold heating for 5 seconds, one heating for 10 seconds, double-sided heating for 10 seconds, water cooling for 10 seconds, and set extraction surface pressure of -0.02 MPa. The obtained foamable form had a density of 0.020 g / cm ³ (50 times the expansion ratio) and an average cell diameter of 230 μm.

  When the obtained foamed molded article was measured, it was a high cis structure with a 1,4 cis structure ratio of 93%, a rubber content of 12% by mass, a styrene graft ratio of 140%, and a gel swelling of 16.

(Rubber content)
The foamed particles or foamed molded product was allowed to stand in a thermostat at 70 ° C. for 24 hours to remove the foaming agent contained in the foamed particles or foamed molded product, and then used as a rubber-modified polystyrene resin sample.

  Dissolve the rubber-modified polystyrene resin in chloroform, add a certain amount of iodine monochloride / carbon tetrachloride solution, leave it in the dark for about 1 hour, add potassium iodide solution, and add 0.1N thiol excess iodine monochloride. Titrate with sodium sulfate / ethanol aqueous solution to determine the amount of iodine monochloride added. The rubber mass was calculated from the amount of iodine monochloride, and the mass of the rubber relative to the mass of the rubber-modified polystyrene resin was determined as the rubber content (% by mass).

(1,4 cis structure ratio)
The foamed particles or foamed molded product was allowed to stand in a thermostat at 70 ° C. for 24 hours to remove the foaming agent contained in the foamed particles or foamed molded product, and then used as a rubber-modified polystyrene resin sample.

About 0.1 g of rubber-modified polystyrene resin was dissolved in about 20 mL of toluene, a film was formed on a hot plate, and infrared analysis was performed. The peak height was obtained from the obtained chart, and the ratio (mass%) of the 1,4-trans structure to the mass of the rubber-modified polystyrene resin was calculated from the calibration curve.
Apparatus: Thermo Fourier Fourier transform infrared spectrophotometer Resolution: 4 cm ⁻¹
Number of scans: 32
Detector: DTGS KBr

The ratio (%) of 1,4 cis structure was calculated by the following formula.
Ratio of 1,4 cis structure (%) = [[Rubber content (mass%)] − [Proportion of 1,4 transformer structure (mass%)]] / [Rubber content (mass%)] × 100

(Rubber particle diameter)
The average particle size of the dispersed particles of butadiene rubber in the present invention is a value obtained by measuring the particle size of 100 to 200 rubber particles (the longest width of each particle) in a transmission electron micrograph and calculating the following equation.
Average particle size = ΣN _i D ² / ΣN _i D
(Note that _Ni is the number of rubber particles, and D is the particle size of the rubber particles.)

(Gel content)
The foamed particles or foamed molded product was allowed to stand in a thermostat at 70 ° C. for 24 hours to remove the foaming agent contained in the foamed particles or foamed molded product, and then used as a rubber-modified polystyrene resin sample.

A rubber-modified polystyrene resin having a mass of 1.00 g is precisely weighed (W), 35 ml of a 50% methyl ethyl ketone / 50% acetone mixed solution is added and dissolved in a volume ratio, and the resulting solution is centrifuged (H-2000B manufactured by Kokusan). (Rotor: H)), centrifuged at 10,000 rpm for 30 minutes to settle the insoluble matter, removed the supernatant by decantation to obtain the insoluble matter, pre-dried at 90 ° C. for 2 hours in a safety oven, Furthermore, after drying under reduced pressure at 120 ° C. for 1 hour in a vacuum dryer and cooling in a desiccator for 20 minutes, the mass G of the dried insoluble matter can be measured and determined as follows.
Gel content (mass%) = (G / W) × 100

(Graft rate)
The foamed particles or foamed molded product was allowed to stand in a thermostat at 70 ° C. for 24 hours to remove the foaming agent contained in the foamed particles or foamed molded product, and then used as a rubber-modified polystyrene resin sample.

The graft ratio of rubber-like dispersed particles of rubber-modified polystyrene resin is determined as follows from the gel content (mass%) in the rubber-modified polystyrene resin and the rubber content (mass%) in the rubber-modified polystyrene resin. be able to.
Graft rate = 100 × (gel content rate−rubber content rate) / rubber content rate

(Gel swelling degree)
The foamed particles or foamed molded product was allowed to stand in a thermostat at 70 ° C. for 24 hours to remove the foaming agent contained in the foamed particles or foamed molded product, and then used as a rubber-modified polystyrene resin sample.

1.00 g of rubber-modified polystyrene resin is precisely weighed, and 30 ml of toluene at 25 ° C. is added and dissolved. The solution is centrifuged at 10,000 rpm with a centrifugal separator (H-2000B (rotor: H) manufactured by Kokusan Co., Ltd.). Centrifugation was performed for a minute to settle the insoluble matter, the supernatant was removed by decantation, and the mass S of the insoluble matter swollen with toluene was measured. The operation so far was performed at 25 ° C. Subsequently, the insoluble matter swollen with toluene at 25 ° C. is preliminarily dried in a safety oven at 90 ° C. for 2 hours, further dried under reduced pressure at 120 ° C. for 1 hour in a vacuum dryer, dried in a desiccator for 20 minutes, and then insoluble. The dry mass D of the minute can be measured and determined as follows.
Swelling degree SI = S / D

(Evaluation of fusion rate)
Insert a cutting line with a depth of about 5 mm with a cutter knife along a straight line connecting the centers of a pair of long sides into a molded product having a length of 400 mm, a width of 300 mm, and a height of 50 mm. , And by counting the total number of particles (A) and the number of particles broken within the particles (B) for an arbitrary range including 100 to 150 foamed particles on the fracture surface, The fusion rate (%) was calculated by the following formula.
Fusing rate = (B) × 100 / (A)
The following evaluation criteria: 90% or more was evaluated as ○, and less than 90% was evaluated as defective (×).

(Evaluation of average bubble diameter)
Using a scanning electron microscope “JSM-6360LV” manufactured by Scanning Electron Microscope JOEL as a measuring device, measurement was performed in accordance with the test method of ASTM D3576-77. Specifically, it cuts with a razor tooth in the plane which passes through the arbitrary places of a foaming molding, and expands a cut surface 30 times using a scanning electron microscope (JOEL company brand name "JSM-6360LV"). Take a picture.

Next, the photographed image is printed on A4 paper, and a straight line having a length of 60 mm is drawn at an arbitrary position in the cross section of the foam molded body, and the average chord length (t) of the bubbles is calculated from the number of bubbles existing on the straight line. Is calculated by the following equation.
Average chord length t (mm) = 60 / (number of bubbles × photo magnification)

  When drawing a straight line, the straight line should be penetrated as much as possible without making point contact with the bubbles. Also, if some of the bubbles come into point contact with a straight line, this bubble is included in the number of bubbles, and if both ends of the straight line are located in the bubble without penetrating the bubbles Includes the bubbles in which both ends of the straight line are located in the number of bubbles.

Based on the calculated average chord length t, the average bubble diameter (D) can be calculated by the following equation.
Average bubble diameter D (mm) = t / 0.616

Further, the average cell diameter is calculated in the same manner as described above at any five locations in the photographed image, and the arithmetic average value of these average cell diameters is taken as the average cell diameter of the foam molded article.
The average cell diameter of the expanded particles was determined in the same procedure.

(50% breaking height)
In accordance with JISK-7111, a foam molded body was adjusted to a size of 200 mm in length, 40 mm in width, and 25 mm in thickness, and 255 g of a steel ball was dropped to obtain a 50% fracture height (cm).
Evaluations were made with a circle of 45 cm or more as ◯ and a dot of less than 45 cm as x.

(Solvent resistance)
Salad oil was applied to the surface of the foamed particles or foamed molded article, and allowed to stand at room temperature for 1 hour, and then the appearance was visually evaluated.
The case where there was no change was rated as ○, and the case where there was a change such as depression, or x.

(Flatness of expanded particles)
The short diameter and long diameter of 100 arbitrary foamed particles were measured, and the average value was calculated by the following formula.
Flatness = average short diameter of expanded particles / average long diameter of expanded particles Each example and comparative example were evaluated by the above-described methods.

<Example 2>
The base resin is a high cis structure in which the ratio of 1,4 cis structure of diene rubber particles is 93%, the rubber content is 12% by mass, the average particle diameter of the rubber particles is 3 μm, the graft ratio of styrene is 144%, the gel swelling Expanded particles and a molded foam were obtained in the same manner as in Example 1 except that a rubber-modified polystyrene resin having a degree of 15 was used.

The obtained expanded particles had a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 219 μm, a flatness of 0.72, a high cis structure with a 1,4 cis structure ratio of 93%, and rubber content The rate was 12% by mass, the grafting rate of styrene was 144%, and the degree of gel swelling was 15.

The obtained foamed molded article had a density of 0.020 g / cm ³ (50 times the expansion ratio), an average cell diameter of 250 μm, a high cis structure with a ratio of 1,4 cis structure of 93%, a rubber content of 12% by mass, and a styrene graft. The rate was 144% and the degree of gel swelling was 15.

<Example 3>
The base resin has a high cis structure in which the ratio of 1,4 cis structure of diene rubber particles is 93%, the rubber content is 12% by mass, the average particle diameter of the rubber particles is 7 μm, the graft ratio of styrene is 155%, the gel swelling Expanded particles and a molded foam were obtained in the same manner as in Example 1 except that a rubber-modified polystyrene resin having a degree of 16 was used.

The obtained expanded particles had a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 215 μm, a flatness of 0.71, a high cis structure with a ratio of 1,4 cis structure of 93%, and rubber content The rate was 12% by mass, the grafting rate of styrene was 155%, and the degree of gel swelling was 16.

The obtained foamed molded article had a density of 0.020 g / cm ³ (50 times the expansion ratio), an average cell diameter of 245 μm, a high cis structure with a ratio of 1,4 cis structure of 93%, a rubber content of 12% by mass, and a styrene graft. The rate was 155% and the degree of gel swelling was 16.

<Example 4>
The base resin has a high cis structure in which the ratio of 1,4 cis structure of diene rubber particles is 93%, the rubber content is 12% by mass, the average particle diameter of the rubber particles is 7 μm, the graft ratio of styrene is 155%, the gel swelling Expanded particles and a molded foam were obtained in the same manner as in Example 1 except that a rubber-modified polystyrene resin having a degree of 16 was used and 1.0 part by mass of Polyslen ES405 was used.

The obtained expanded particles have a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 114 μm, a flatness of 0.78, a high cis structure with a ratio of 1,4 cis structure of 93%, and rubber content The rate was 12% by mass, the grafting rate of styrene was 155%, and the degree of gel swelling was 16.

The obtained foamed molded article has a density of 0.020 g / cm ³ (50 times the expansion ratio), an average cell diameter of 130 μm, a high cis structure with a ratio of 1,4 cis structure of 93%, a rubber content of 12% by mass, and a styrene graft. The rate was 155% and the degree of gel swelling was 16.
The average bubble diameter obtained was as small as 130 μm.

<Comparative Example 1>
The base resin has a low cis structure in which the proportion of 1,4 cis structure of diene rubber particles is 60%, the rubber content is 6% by mass, the average particle diameter of the rubber particles is 0.1 μm, the graft ratio of styrene is 120%, Expanded particles and a molded foam were obtained in the same manner as in Example 1 except that a rubber-modified polystyrene resin having a gel swelling degree of 15 was used.

The obtained expanded particles have a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 79 μm, a flatness of 0.54, a low cis structure with a 1,4 cis structure ratio of 60%, and rubber content The rate was 6% by mass, the graft rate of styrene was 120%, and the degree of gel swelling was 15.

The obtained foamed molded product has a density of 0.020 g / cm ³ (50 times the expansion ratio), an average cell diameter of 90 μm, a low-cis structure with a ratio of 1,4 cis structure of 60%, a rubber content of 6% by mass, and a styrene graft. The rate was 120% and the degree of gel swelling was 15.
The obtained foam had a small average cell diameter, 50% fracture height, and poor solvent resistance.

<Comparative example 2>
The base resin is a high cis structure in which the ratio of 1,4 cis structure of diene rubber particles is 85%, the rubber content is 10% by mass, the average particle diameter of the rubber particles is 3 μm, the graft ratio of styrene is 133%, the gel swelling Expanded particles and a molded foam were obtained in the same manner as in Example 1 except that a rubber-modified polystyrene resin having a degree of 9 was used.

The obtained expanded particles had a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 82 μm, a flatness of 0.85, a high cis structure with a 1,4 cis structure ratio of 85%, and rubber content The ratio was 10% by mass, the graft ratio of styrene was 133%, and the degree of gel swelling was 9.

The obtained foamed molded article has a density of 0.020 g / cm ³ (50 times the expansion ratio), an average cell diameter of 94 μm, a high cis structure with a ratio of 1,4 cis structure of 85%, a rubber content of 10% by mass, and a styrene graft. The rate was 133% and the degree of gel swelling was 9.
The obtained foam had a small average cell diameter, 50% fracture height, and poor solvent resistance.

<Comparative Example 3>
The base resin is a high cis structure in which the proportion of 1,4 cis structure of diene rubber particles is 80%, the rubber content is 10% by mass, the average particle diameter of the rubber particles is 1 μm, the graft ratio of styrene is 167%, the gel swelling Expanded particles and a molded foam were obtained in the same manner as in Example 1 except that a rubber-modified polystyrene resin having a degree of 12 was used.

The obtained expanded particles have a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 75 μm, a flatness of 0.56, a high cis structure with a ratio of 1,4 cis structure of 80%, and rubber content The ratio was 10% by mass, the graft ratio of styrene was 167%, and the degree of gel swelling was 12.

The obtained foamed molded article has a density of 0.020 g / cm ³ (50 times the expansion ratio), an average cell diameter of 85 μm, a high cis structure with a ratio of 1,4 cis structure of 80%, a rubber content of 10% by mass, and a styrene graft. The rate was 167% and the degree of gel swelling was 12.
The obtained foam had a small average cell diameter and was inferior in fusion rate, 50% fracture height, and solvent resistance.

<Comparative Example 4>
The base resin is a high cis structure in which the ratio of 1,4 cis structure of diene rubber particles is 93%, the rubber content is 12% by mass, the average particle diameter of the rubber particles is 3 μm, the graft ratio of styrene is 144%, the gel swelling Foamed particles and a foamed molded article were obtained in the same manner as in Example 1 except that a rubber-modified polystyrene resin having a degree of 15 was used and no polyslen ES405 was used.

The obtained expanded particles have a bulk density of 0.020 g / cm ³ (bulk expansion ratio: 50 times), an average cell diameter of 307 μm, a flatness of 0.53, a high cis structure with a ratio of 1,4 cis structure of 93%, and rubber content The rate was 12% by mass, the grafting rate of styrene was 144%, and the degree of gel swelling was 15.

The obtained foamed molded article had a density of 0.020 g / cm ³ (50 times the expansion ratio), an average cell diameter of 350 μm, a high cis structure with a ratio of 1,4 cis structure of 93%, a rubber content of 12% by mass, and a styrene graft. The rate was 144% and the degree of gel swelling was 15.
The obtained foam had a large average cell diameter of 350 μm and was inferior in 50% fracture height.

<Result>
The evaluation results of Examples 1 to 4 and Comparative Examples 1 to 4 are summarized in the following table.

Claims (12)

Expanded particles of a rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
A foamed particle of a rubber-modified polystyrene-based resin, comprising bubbles having an average diameter of 100 to 300 μm.   The expanded particle of rubber-modified polystyrene resin according to claim 1, wherein the gel swelling degree of the diene polymer rubber is 13-20.   The expanded particle of rubber-modified polystyrene resin according to claim 1 or 2, wherein the flatness is 0.6 to 0.8. A bag,
The cushion body characterized by including the foam particle | grains of the rubber modified polystyrene resin of any one of Claims 1-3 with which the said bag body was filled. A foam-molded article of a rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin and a diene polymer rubber dispersed in the continuous phase,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
A foam-molded article of rubber-modified polystyrene-based resin, comprising bubbles having an average diameter of 100 to 300 μm.   The foam-molded article of rubber-modified polystyrene resin according to claim 5, wherein the diene polymer rubber has a gel swelling degree of 13 to 20.   The foam-molded article of rubber-modified polystyrene resin according to claim 5 or 6, which is in the form of a transport container. A rubber-modified polystyrene resin containing a continuous phase containing a polystyrene resin, and a diene polymer rubber dispersed in the continuous phase;
Expandable particles of rubber-modified polystyrene resin containing a foaming agent,
The diene polymer rubber contains 70% or more of 1,4 cis structure,
The content of the diene polymer rubber in the rubber-modified polystyrene resin is 9 to 15% by mass,
The diene polymer rubber is grafted with a polystyrene resin, and the graft ratio is 137 to 160%.
The diene polymer rubber forms particles having an average particle diameter of 2 to 8 μm, and is an expandable particle of a rubber-modified polystyrene resin.   The expandable particle | grains of the rubber modified polystyrene resin of Claim 8 whose gel swelling degree of the said diene polymer rubber is 13-20. A method for producing expandable particles of the rubber-modified polystyrene resin according to claim 8 or 9,
In the extruder, the molten rubber-modified polystyrene-based resin and the foaming agent are kneaded to form a resin foaming agent mixed melt, and a mixing and melting step,
And extruding the resin foaming agent mixed melt from the extruder into a cooling liquid and cooling. A method for producing foamed particles of a rubber-modified polystyrene resin, comprising a foaming step of foaming the foamable particles of the rubber-modified polystyrene resin according to claim 8 or 9. A foaming step of foaming the foamable particles of the rubber-modified polystyrene resin according to claim 8 or 9,
A method for producing a foam-molded product of a rubber-modified polystyrene resin, comprising a molding step of molding foamed particles of the rubber-modified polystyrene resin obtained by the foaming step in-mold.

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