JP2018100380A - Polystyrene-based resin foamable particle and method for producing the same, polystyrene-based resin foamed particle and method for producing the same, and polystyrene-based resin foamed molded body and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide foamable particles for producing a polystyrene-based resin foamed molded body excellent in foamed moldability and in mechanical strength even with a high foaming magnification.SOLUTION: Polystyrene-based resin foamable particles contain a polystyrene-based resin a foaming agent, where Mof the resin in measurement by GPC method is 800,000 to 3,000,000, M/Mis 1.8 or more, MFR at 200°C is 10.0 g/10 min or less, MT at 200°C is 4 cN or more, the maximum elongation viscosity in 160°C by uniaxial extension viscosity measurement is 1.0×10Pa S or more, and a strain cure index is 1.1 or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polystyrene resin foam molded article having excellent foam moldability and excellent mechanical strength even at a high expansion ratio, and a method for producing the same.

  The present invention also relates to a polystyrene resin foamable particle and a method for producing the same, and a polystyrene resin foam particle and a method for producing the same.

  The present invention also relates to a heat insulating material for living space.

  Polystyrene resin foam moldings obtained by foaming polystyrene resin foamable particles are excellent in compression resistance, light weight, heat insulation, economy, etc., and are widely used as heat insulating materials, packing materials, etc. Yes. In recent years, in the field of polystyrene-based resin foam moldings, there has been a strong demand for a high expansion ratio of the foam molding so that the amount of resin used can be reduced. Even with a high expansion ratio, molding is easy, There is an urgent need to develop a polystyrene-based resin foam molding having high strength.

  As one of the methods for producing polystyrene resin expandable particles, a foaming agent is press-fitted and kneaded into a polystyrene resin melted in an extruder, and a foaming agent-containing molten resin is supplied from a die nozzle attached to the tip of the extruder. The so-called melt-extrusion method is known in which extrudates are extruded directly into a cooling liquid, and at the same time the extrudate is cut with a high-speed rotary blade, and the extrudate is cooled and solidified by contact with the liquid to obtain expandable polystyrene resin particles. It has been.

  Conventionally, for example, techniques disclosed in Patent Documents 1 and 2 have been proposed regarding a method for producing expandable polystyrene resin particles by a melt extrusion method.

  Patent Document 1 discloses foam-containing expandable polystyrene resin particles that contain a foaming agent and bubbles in polystyrene resin particles, and are previously contained so that the bubbles have a predetermined density. Patent Document 1 discloses that the foam-containing foamable polystyrene resin particles can be directly used for in-mold foam molding without undergoing preliminary foaming, and the foam molded product obtained by in-mold foam molding has a high expansion ratio. Is also described as having excellent mechanical strength.

  Patent Document 2 discloses expandable polystyrene resin particles containing a physical foaming agent and a polystyrene resin, and the polystyrene resin has a melt flow rate (MFR) measured at 200 ° C. of 1.0 to 10. There is disclosed foamable polystyrene resin particles having a melt tension (MT) measured at 200 ° C. of 5 cN or more within a range of 0.0 g / 10 minutes. According to Patent Document 2, when the expandable polystyrene resin particles are heated and pre-expanded, the obtained pre-expanded particles are subjected to in-mold foam molding to obtain a foam molded article having a good appearance and excellent strength. Describe.

JP 2011-202078 A JP 2013-227537 A

  In the Example of patent document 1, the example which manufactured the foaming molding of 50 times expansion ratio is described as a specific example of the foaming molding of high expansion ratio. Similarly, Patent Document 2 also describes an example in which a foamed molded article having a foaming ratio of 50 times is manufactured.

  As described above, in the prior art for obtaining a foamed molded article by pre-expanding polystyrene resin expandable particles produced by the melt extrusion method, about 50 times was recognized as the upper limit of the high expansion ratio. According to the study by the present inventors, when foaming particles obtained by adding a larger amount of a foaming agent to the polystyrene-based resin foaming particles described in Patent Documents 1 and 2, the resin can hold bubbles. Therefore, it is impossible to achieve a high expansion ratio exceeding 60 times.

  Therefore, the present invention provides a polystyrene resin foamable particle capable of producing a polystyrene resin foam molded article having excellent foam moldability and excellent mechanical strength even at a high expansion ratio, and a polystyrene resin foam produced using the same. An object is to provide particles, a polystyrene-based resin foam molded article, a heat insulating material for living space, and a method for producing them.

In order to achieve the above object, the present invention provides:
A polystyrene resin expandable particle containing a polystyrene resin and a foaming agent,
The polystyrene resin has a Z + 1 average molecular weight (M _{Z + 1} ) of 800,000 to 3,000,000 in the measurement by gel permeation chromatography, and the ratio of M _{Z + 1} to the Z average molecular weight (M _Z ) (M _{Z + 1)} / M _Z ) is 1.8 or more,
The polystyrene resin has a melt flow rate (MFR) measured at 200 ° C. of 10.0 g / 10 min or less and a melt tension (MT) measured at 200 ° C. of 4 cN or more,
The polystyrene resin has a maximum elongation viscosity at 160 ° C. in a uniaxial elongation viscosity measurement of 1.0 × 10 ⁶ Pa · S or more, and a strain hardening index of 1.1 or more.
A polystyrene resin expandable particle is provided.

  In the polystyrene resin foamable particles of the present invention, preferably, the glass transition point (Tg) of the polystyrene resin is 80 to 110 ° C.

  In the polystyrene resin foamable particles of the present invention, preferably, the foaming agent is pentane.

  The polystyrene-based resin expandable particles of the present invention preferably contain a radiation heat transfer inhibiting component.

The polystyrene-based resin expandable particles of the present invention are preferably
Step 1 of injecting the foaming agent into the melted polystyrene resin to prepare a foaming agent-containing molten resin;
The foaming agent-containing molten resin is produced by a method including the step 2 of extruding the molten resin into a liquid, cutting it, and solidifying it.

The present invention also provides
A polystyrene-based resin expanded particle containing a polystyrene-based resin in which bubbles are formed,
The polystyrene resin has a Z + 1 average molecular weight (M _{Z + 1} ) of 800,000 to 3,000,000 in the measurement by gel permeation chromatography, and the ratio of M _{Z + 1} to the Z average molecular weight (M _Z ) (M _{Z + 1)} / M _Z ) is 1.8 or more,
The polystyrene resin has a melt flow rate (MFR) measured at 200 ° C. of 10.0 g / 10 min or less and a melt tension (MT) measured at 200 ° C. of 4 cN or more,
The polystyrene resin has a maximum elongation viscosity at 160 ° C. in a uniaxial elongation viscosity measurement of 1.0 × 10 ⁶ Pa · S or more, and a strain hardening index of 1.1 or more.
A polystyrene resin expanded particle is provided.

  In the polystyrene resin expanded particles of the present invention, preferably, the glass transition point (Tg) of the polystyrene resin is 80 to 110 ° C.

  The expanded polystyrene resin particles of the present invention preferably contain a radiation heat transfer inhibiting component.

The present invention also provides
A polystyrene-based resin foam molded article comprising a plurality of foamed particles containing polystyrene-based resin in which bubbles are formed and fused together,
The polystyrene resin has a Z + 1 average molecular weight (M _{Z + 1} ) of 800,000 to 3,000,000 in the measurement by gel permeation chromatography, and the ratio of M _{Z + 1} to the Z average molecular weight (M _Z ) (M _{Z + 1)} / M _Z ) is 1.8 or more,
The polystyrene resin has a melt flow rate (MFR) measured at 200 ° C. of 10.0 g / 10 min or less and a melt tension (MT) measured at 200 ° C. of 4 cN or more,
The polystyrene resin has a maximum elongation viscosity at 160 ° C. in a uniaxial elongation viscosity measurement of 1.0 × 10 ⁶ Pa · S or more, and a strain hardening index of 1.1 or more.
A polystyrene-based resin foam molded article is provided.

  In the polystyrene resin foam molded article of the present invention, preferably, the glass transition point (Tg) of the polystyrene resin is 80 to 110 ° C.

  The polystyrene-based resin foam molded article of the present invention preferably contains a radiation heat transfer suppressing component.

  This invention also provides the heat insulating material for living spaces containing the said polystyrene-type resin foaming particle of said this invention, and / or the said polystyrene-type resin foaming molding of this invention.

The present invention is also a method for producing the above polystyrene-based resin expandable particles of the present invention,
Step 1 of injecting the foaming agent into the melted polystyrene resin to prepare a foaming agent-containing molten resin;
And 2) extruding, blowing, and solidifying the foaming agent-containing molten resin into a liquid.

The present invention is also a method for producing the above polystyrene-based resin expanded particles of the present invention,
Step 3 of heating and foaming the polystyrene-based resin expandable particles produced by the above method to obtain expanded particles
A method characterized by comprising:

The present invention is also a method for producing the above polystyrene-based resin foam molded article of the present invention,
Step 3 of heating and foaming the polystyrene resin foamable particles produced by the above method to obtain foamed particles;
And a step 4 of obtaining the foamed molded body by foam-molding the foamed particles in a mold.

  According to the present invention, a polystyrene resin foamable particle capable of producing a polystyrene resin foam molded article having excellent foam moldability and excellent mechanical strength even at a high expansion ratio, and a polystyrene resin produced using the same Provided are expanded particles, a polystyrene-based resin foam molded article, a heat insulating material for living space, and a method for producing the same.

FIG. 1 is a schematic view of a production apparatus for producing the polystyrene resin expandable particles of the present invention.

1. Polystyrene Resin Expandable Particles The polystyrene resin expandable particles of the present invention (hereinafter sometimes referred to as “expandable particles”) contain at least a polystyrene resin and a foaming agent, and form a particle shape as a whole. Although the particle size of the expandable particle | grains of this invention is not specifically limited, Usually, it is the range of 0.5 mm-3.0 mm, and the range of 0.7 mm-2.0 mm is preferable. The particle size is a value measured in accordance with JISZ8815 as a particle size having an integrated value of 50% from the particle size distribution according to the sieving test described in JISZ8815. The shape of the expandable particles is not particularly limited, and may be a spherical shape, a substantially spherical shape, a cylindrical shape, a substantially cylindrical shape, or the like.

1.1. Polystyrene resin Polystyrene resin is a polymer compound containing at least a styrene monomer component as a monomer component.

  The styrenic monomer includes styrene or a styrene derivative. A styrenic monomer may consist of only 1 type and may contain 2 or more types. Examples of the styrene derivative include α-methyl styrene, vinyl toluene, chlorostyrene, ethyl styrene, i-propyl styrene, dimethyl styrene, bromostyrene, and the like. The styrene monomer preferably contains at least styrene, and particularly preferably contains 50% or more of styrene with respect to the total amount of the styrene monomer.

  The polystyrene resin of the present invention may be a copolymer further including a vinyl monomer component copolymerizable with the styrene monomer, as long as the styrene monomer component is included as a main component of the monomer component. There may be.

  Examples of the vinyl monomer include polyfunctional monomers, (meth) acrylic acid ester monomers, maleic acid ester monomers, and fumaric acid ester monomers.

  A polystyrene resin containing a polyfunctional monomer as a monomer component contains a branched chain as a polymer chain. A polystyrene resin containing a branched chain molecule can be easily made into a resin having physical properties 1 to 3 described later, as compared with a polystyrene resin consisting only of a linear molecule. Polyfunctional monomers include o-divinylbenzene, m-divinylbenzene, p-divinylbenzene and other divinylbenzene, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate and other alkylene glycol di (meth) An acrylate etc. can be illustrated and may contain 1 type or multiple types of polyfunctional monomers. The number of polymerizable functional groups contained in one molecule of the polyfunctional monomer is usually 2 or 3, and 2 is preferable. The content of the polyfunctional monomer component among the monomer components contained in the polystyrene resin is not particularly limited, but is preferably 0.005 to 0.1% by weight, more preferably 0.01 to 0.05% by weight. %.

  The glass transition point (Tg) of a polystyrene resin containing a (meth) acrylic acid ester monomer as a monomer component is lower than the Tg of a polystyrene resin not containing a (meth) acrylic acid ester monomer. A (meth) acrylic acid ester monomer can be included for the purpose of reducing the Tg of the polystyrene resin. (Meth) acrylic acid ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth) And (meth) acrylic acid ester monomers such as 2-ethylhexyl acrylate and hexyl (meth) acrylate. The part of “(meth) acrylic acid” in each component means acrylic acid or methacrylic acid, preferably acrylic acid. As the (meth) acrylic acid ester monomer, butyl acrylate, 2-ethylhexyl acrylate, and ethyl acrylate are preferable, and butyl acrylate is particularly preferable. The content of the (meth) acrylic acid ester monomer component among the monomer components contained in the polystyrene resin is not particularly limited, but is preferably 0.1 to 3.0% by weight, more preferably 0.5 to 2.0% by weight. However, a polystyrene resin that does not contain a (meth) acrylic acid ester monomer as a monomer component is also suitable in the present invention.

  Examples of maleate monomers include dimethyl maleate.

  Examples of the fumaric acid ester monomer include dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

  The polystyrene resin may include one or more types as a polymer compound including at least a styrene monomer component as a monomer component. Examples of polystyrene resins containing a plurality of types of the polymer compounds include homopolymers of styrene monomers, copolymers of styrene monomers and (meth) acrylate monomers, and styrene resins. Examples thereof include polystyrene resins containing a copolymer of a monomer and a polyfunctional monomer.

  The polystyrene resin used as a raw material is a non-recycled polystyrene resin (virgin polystyrene) such as a commercially available polystyrene resin or a polystyrene resin newly produced by a method such as suspension polymerization described later. In addition, a regenerated polystyrene resin obtained by regenerating a used polystyrene resin foam molded article can be used.

1.2. Characteristics of Polystyrene Resin The polystyrene resin contained in the expandable particles of the present invention and the expanded particles of the present invention and the foamed molded product described later have the following characteristics 1 to 3.

(Characteristic 1)
In the measurement by the gel permeation chromatography method, the Z + 1 average molecular weight (M _{Z + 1} ) is 800,000 to 3 million, and the ratio of M _{Z + 1} to the Z average molecular weight (M _Z ) (M _{Z + 1} / M _Z ) is 1. .8 or more.

(Characteristic 2)
The melt flow rate (MFR) measured at 200 ° C. is 10.0 g / 10 min or less, and the melt tension (MT) measured at 200 ° C. is 4 cN or more.

(Characteristic 3)
The maximum extensional viscosity at 160 ° C. in the uniaxial extensional viscosity measurement is 1.0 × 10 ⁶ Pa · S or more, and the strain hardening index is 1.1 or more.

  Expandable particles containing polystyrene resin satisfying all characteristics 1 to 3 can be expanded at high multiples, producing polystyrene resin foam molded products with excellent foam moldability at high expansion multiples and excellent mechanical strength. can do. The mechanism for producing this effect is not necessarily clear, but it is presumed that the foam film formed by the polystyrene resin satisfying all the characteristics 1 to 3 is easily extended and hardly broken. The foamed particles or foam-molded product obtained by foaming the foamable particles of the present invention supports this assumption that the ratio of closed cells surrounded by a cell membrane is high and the ratio of open cells is low. The method for measuring the open cell ratio of the foamed molded product is as described in the columns of Examples and Comparative Examples.

  The physical properties 2, physical properties 3 and physical properties 4 described below of the polystyrene-based resin contained in the foamable particles, foamed particles or foamed molded product of the present invention are the foaming agent of the foamable particles, foamed particles or foamed molded product of the present invention. These are the physical properties shown by the components (referred to as “resin components”) excluding volatile components represented by. The resin component is a resin composition containing the above polystyrene-based resin as a base resin and containing other components described later as required. When the expandable particle, the expanded particle or the expanded molded article of the present invention contains other components described later in addition to the polystyrene resin, the physical properties of the resin component may be the physical properties of the polystyrene resin. The residue after the expandable particle, the expanded particle or the expanded molded article of the present invention is placed in a thermal decomposition furnace at 150 ° C. and heated for 30 minutes can be regarded as a resin component.

(About characteristic 1)
Polystyrene resins satisfying the above property 1 have good fluidity and high melt tension. Since this polystyrene-based resin is easy to form a bubble film and the bubble film is not easily broken, it is easy to multiply the foamed resin. When M _{Z + 1} is less than 800,000, the bubble film is easily broken at the time of foaming and is not suitable for high-magnification foaming. When M _{Z + 1} is larger than 3 million, the expansion ratio does not increase because the tension of the resin is too high. M _{Z + 1} is preferably 90 to 280, more preferably 100 to 250.

M _{Z + 1} / M _Z being 1.8 or more means that the proportion of the high molecular weight component is high. When M _{Z + 1} / M _Z is less than 1.8, the cell membrane is easily broken at the time of foaming and is not suitable for high-magnification foaming. M _{Z + 1} / M _Z is preferably 1.8 to 3.0, more preferably 1.8 to 2.5.

M _{Z + 1} and M _Z mean polystyrene (PS) equivalent average molecular weights measured using gel permeation chromatography (GPC). Specific measuring methods of M _{Z + 1} and M _Z of polystyrene-based resins in the form of expandable particles, expanded particles or expanded molded products are as described in Examples and Comparative Examples.

(About characteristic 2)
Polystyrene resins satisfying the above-mentioned property 2 have good fluidity and high melt tension, so that it is easy to increase the expansion of the foamed resin.

  The MFR measured at 200 ° C. of the polystyrene resin is 10.0 g / 10 min or less, preferably 8 g / 10 min or less, more preferably 6 to 1 g / 10 min. If it exceeds 10.0 g / 10 min, the cell membrane may be broken and contracted during high-magnification foaming.

  MT of polystyrene resin measured at 200 ° C. is 4 cN or more, preferably 5 cN or more, more preferably 5 to 25 cN. If the MT is less than 4 cN, the bubble film may be broken and contracted during high-magnification foaming.

  Melt flow rate (MFR) was measured in accordance with the method described in JIS K 7210: 1999 “Plastics—Test methods for melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics” B method. Say.

  The melt tension (MT) is measured using a twin-bore capillary rheometer Rheological 5000T (Chiast, Italy).

  Specific methods for measuring the melt flow rate (MFR) and melt tension (MT) of polystyrene-based resins in the form of expandable particles, expanded particles or expanded molded products are as described in the Examples and Comparative Examples columns. is there.

(About characteristic 3)
Polystyrene resin satisfying the above-mentioned property 3 has strain-hardening properties and can suppress the tearing of the bubble film during foaming, thus enabling high-magnification foaming.

The polystyrene resin has a maximum elongation viscosity at 160 ° C. in a uniaxial elongation viscosity measurement of 1.0 × 10 ⁶ Pa · S or more, and more preferably 1.3 × 10 ⁶ Pa · S or more. Although there is no particular upper limit, it is about 1.0 × 10 ⁷ Pa · S. When the maximum elongation viscosity at 160 ° C. in the uniaxial elongation viscosity measurement is less than 1.0 × 10 ⁶ Pa · S, the polystyrene-based resin is easily broken during foaming and is not suitable for high-magnification foaming. Further, even if the upper limit is exceeded, the viscosity of the resin is so high that it may not be suitable for high-magnification foaming.

  The polystyrene resin is further characterized by having a strain hardening index of 1.1 or more. When the strain hardening index is 1.1 or more, the bubble film is not easily broken during foaming and is suitable for high-magnification foaming. The upper limit of the strain hardening index of the polystyrene resin is not particularly limited, but is usually 2.0 or less.

  Specific measurement methods of the maximum elongation viscosity at 160 ° C. and the strain hardening index of the polystyrene-based resin in the form of expandable particles, expanded particles, or foamed molded products are shown in Examples and Comparative Examples. It is as described in the column.

  It is preferable that the polystyrene resin satisfying the characteristics 1 to 3 further satisfy the following characteristic 4.

(Characteristic 4)
The glass transition point (Tg) is 80-110 ° C.

  Expandable particles containing a polystyrene-based resin having a Tg of 110 ° C. or lower are easily softened during heating and foaming, and thus easily foam. Moreover, even when the resin is softened and heated and foamed by satisfying the characteristics 1 to 3, bubbles are hard to break and high foaming is possible.

  On the other hand, expandable particles containing a polystyrene-based resin having a Tg of 80 ° C. or higher are preferable because they are not excessively softened during heating and foaming.

The Tg of the polystyrene-based resin is more preferably 90 to 105 ° C. The glass transition point (Tg) is a differential scanning calorimeter based on the method described in JIS K7121: 1987 “Method for measuring the transition temperature of plastics”. It can be measured using a device (DSC).

  The specific measuring method of the glass transition point (Tg) of the polystyrene-based resin in the form of expandable particles, expanded particles or expanded molded products is as described in the Examples and Comparative Examples.

  In order to make the Tg of the polystyrene resin in the above range in the expandable particle, the expanded particle or the foamed molded product of the present invention, the polystyrene resin is added as a monomer component to the styrene monomer. It is preferable to include a copolymer containing the (meth) acrylic acid ester monomer. The preferred content of the (meth) acrylate monomer is as described above.

  In another embodiment in which the Tg of the polystyrene resin in the expandable particle, foam particle or foam molded article of the present invention is in the above range, the expandable particle, foam particle or foam molded article of the present invention is plastic other than the polystyrene resin. The aspect containing the component which carries out a chemical conversion action is mentioned. The component having a plasticizing action includes not only a component blended as a plasticizer but also a component having a plasticizing action although blended as a flame retardant. As the plasticizer, high-boiling plasticizers are preferable, and specific examples include diisobutyl adipate and di-2-ethylhexyl adipate. Specific examples of the flame retardant having a plasticizing action include tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromocyclooctane, hexabromocyclododecane, trisdibromopropyl phosphate, tetra Examples thereof include bromobisphenol A and tetrabromobisphenol A-bis (2,3-dibromopropyl ether).

1.3. The foaming agent is not particularly limited, and any known foaming agent can be used. In particular, a gaseous or liquid organic compound having a boiling point equal to or lower than the softening point of the styrene resin is suitable. For example, hydrocarbons such as propane, n-butane, isobutane, pentane (n-pentane, isopentane or neopentane), cyclopentane, cyclopentadiene, n-hexane, petroleum ether, ketones such as acetone and methyl ethyl ketone, methanol, ethanol, isopropyl Alcohols such as alcohol, low boiling point ether compounds such as dimethyl ether, diethyl ether, dipropyl ether and methyl ethyl ether, halogen-containing hydrocarbons such as trichloromonofluoromethane and dichlorodifluoromethane, inorganics such as carbon dioxide, nitrogen and ammonia Gas etc. are mentioned. These 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. Since pentane (n-pentane, isopentane or neopentane) has a plastic effect, the polystyrene resin has a low Tg in a state containing pentane. For this reason, expandable resin particles containing a polystyrene resin having a relatively low molecular weight and pentane are easy to break when heated and foamed, and it may be difficult to foam at a high multiple, but the polystyrene resin having the characteristics of the present invention. If it is used, even when pentane is used, foaming at a high multiple is possible.

  The content of the foaming agent in the expandable particles may be an amount sufficient for the formation of the expanded particles, for example, in the range of 2 to 13% by weight with respect to the total amount of the components other than the foaming agent of the expandable particles. It can be. The total amount of components other than the foaming agent of the expandable particles of the present invention can be measured by determining the total amount of the residue after heating the expandable particles of the present invention in a 150 ° C. pyrolysis furnace for 30 minutes. It is.

  Moreover, the expandable particle | grains of this invention may also contain a foaming adjuvant with a foaming agent. Examples of the foaming aid include isobutyl adipate, toluene, cyclohexane, and ethylbenzene.

1.4. Other Components In addition to the above polystyrene-based resin and foaming agent, the foamable particles of the present invention preferably contain one or both of an inorganic foam nucleating agent and a chemical foaming agent.

  Examples of the inorganic foam nucleating agent include talc, silica, silicate mineral powder, mica, clay, zeolite, calcium carbonate, etc. Among them, one kind selected from talc, silica, silicate mineral powder, among others. Or 2 or more types are preferable.

  The amount of the inorganic foam nucleating agent is preferably in the range of 0.05 to 5.0 parts by weight and more preferably in the range of 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the polystyrene-based resin.

  Examples of the chemical foaming agent include azodicarbonamide, N, N′-dinitrosopentamethylenetetramine, 4,4′-oxybis (benzenesulfonylhydrazide), sodium hydrogen carbonate, a mixture of sodium hydrogen carbonate and citric acid, and the like. Among these, one or more selected from azodicarbonamide, sodium bicarbonate, a mixture of sodium bicarbonate and citric acid are preferable.

  The amount of the chemical foaming agent is preferably in the range of 0.05 to 5.0 parts by weight, more preferably in the range of 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the polystyrene resin.

  The foamable particle of the present invention, the foamed particle obtained from the foamable particle of the present invention, and the foamed molded product, within a range that does not impair the physical properties, other components other than the radiant heat transfer inhibitor, polystyrene-based resin, cross-linked Additives such as plasticizers, plasticizers, fillers, flame retardants, flame retardant aids, lubricants, and colorants may be added, and powder metal soaps such as zinc stearate may be added to the surface of the expandable particles. If it is applied, the bond between the expanded particles can be reduced in the pre-expanding step of the expandable particles, which is preferable. In addition, the polystyrene resin may contain unavoidable impurities such as a component derived from a polymerization initiator used for polymerization of the polystyrene resin.

  The resin component containing the polystyrene-based resin may be a polystyrene-based resin as a main component, and may further include another resin (polymer compound). Examples of the other resin include diene rubbers such as polybutadiene, styrene-butadiene copolymer, and ethylene-propylene-nonconjugated diene three-dimensional copolymer, which have a function of improving the impact resistance of the foam molded article. Examples of the polymer include a polyethylene polymer, a polypropylene resin, a (meth) acrylic resin, a (meth) acrylonitrile-styrene copolymer, and a (meth) acrylonitrile-butadiene-styrene copolymer.

  In the case where the foamed particles or foamed molded article to be produced is used as a heat insulating material, the foamable particles preferably further contain a radiation heat transfer inhibiting component.

  The radiation heat transfer suppression component refers to a component having a characteristic of reflecting, scattering, or absorbing light in the near infrared to infrared region (for example, a wavelength region of about 800 to 3000 nm). Examples of radiation heat transfer inhibiting components having such functions include carbon black (Ketjen black, acetylene black, furnace black, thermal black, etc.), carbon nanofibers, carbon nanotubes, carbon nanohorns, activated carbon, graphite, graphene, Carbon materials such as coke, mesoporous carbon, glassy carbon, hard carbon, and soft carbon; titanium compounds such as titanium, titanium oxide, and strontium titanate; aluminum compounds such as aluminum and aluminum oxide; zinc compounds such as zinc aluminate; hydro Magnesium compounds such as talcite; silver compounds such as silver; heat of stainless steel, nickel, tin, silver, copper, bronze, shirasu balloon, ceramic balloon, microballoon, pearl mica, etc. Reflective components: sulfate metal salts such as barium sulfate, strontium sulfate, calcium sulfate, mercalite, halothrite, alumite, iron alumite; antimony compounds such as antimony trioxide, antimony oxide, anhydrous zinc antimonate; tin oxide, Metal oxides such as indium oxide, zinc oxide, and indinium tin oxide; ammonium, urea, imonium, aminium, cyanine, polymethine, anthraquinone, dithiol, copper ion, phenylenediamine, phthalocyanine , Benzotriazole series, benzophenone series, oxalic acid anilide series, cyanoacrylate series, benzotriazole series and the like.

  The expandable particle of the present invention may contain one kind alone or two or more kinds as a radiation heat transfer inhibiting component.

  The content of the radiation heat transfer inhibiting component in the expandable particles of the present invention can be appropriately adjusted in consideration of various circumstances such as the intended effect of suppressing radiation heat transfer. For example, the content of the radiation heat transfer inhibiting component in the expandable particles of the present invention is, for example, 0.5 to 25 parts by weight, preferably 0.5 to 15 parts by weight, more preferably 0, per 100 parts by weight of the polystyrene resin. .5 to 10 parts by weight. This content is particularly suitable when the radiant heat transfer inhibiting component is a carbon material.

  As the radiant heat transfer inhibiting component that can be contained in the expandable particles of the present invention, a carbon material is particularly preferable because sufficient heat insulating properties can be imparted to the manufactured expanded particles or expanded molded article.

  In the expandable particle, the expanded particle and the expanded molded article of the present invention, the carbon material is preferably present as an aggregate obtained by agglomerating a plurality of primary particles of the carbon material in the polystyrene resin.

  Examples of the primary particles of the carbon material used as the radiation heat transfer suppressing component include an average primary particle diameter of 18 to 125 nm. An average primary particle diameter means the average value of the longest diameter of a primary particle, and can take the value of 18-125 nm. However, this does not restrict the primary particles from taking a shape other than spherical and substantially spherical, and the primary particles may take other shapes such as a cylindrical shape and a prismatic shape. When the primary particles have a shape other than a spherical shape or a substantially spherical shape, the average primary particle size means an average value of the longest diameters obtained by approximating the primary particles to a spherical shape. If the average primary particle size is less than 18 nm, moldability may be reduced due to finer bubbles, and if it is greater than 125 nm, moldability may be reduced due to tearing of the bubble film.

Agglomerates formed by the primary particles of the carbon material are:
(I) having an average value of the longest diameter of 180 to 500 nm, and
(Ii) It is preferable to have a ratio of “average value of longest diameter” to “average primary particle diameter” of 4.0 to 10.0.

  The longest diameter of the aggregate is the longest distance between any two points on the outer edge of the aggregate that are opposed to each other with only the inside of the aggregate on the outer edge of the aggregate. means. When the average value of the longest diameter is less than 180 nm, the heat insulating property may not be improved, and when it is larger than 500 nm, bubbles may be broken at the time of foaming and the heat insulating property may not be improved and a good molded product may not be obtained.

  In addition, when the ratio specified in (ii) is less than 4.0, the agglomerates may not improve the heat insulating property. May not be obtained.

Another preferred embodiment of the carbon material used as the radiation heat transfer suppression component is a carbon material having a volume resistivity of 1.0 × 10 ⁴ Ω · cm or less. When the volume resistivity of the carbon material is higher than 1.0 × 10 ⁴ Ω · cm, the heat insulating property may not be sufficiently improved. A more preferred volume resistivity is 7.0 × 10 ³ Ω · cm or less, a further preferred volume resistivity is 4.0 × 10 ³ Ω · cm or less, and a most preferred volume resistivity is 2.0 × 10 ^3. The volume resistivity is 1.0 × 10 ³ Ω · cm or less. A lower limit value of the volume resistivity is not particularly provided, but is, for example, about 1.0 × 10 ⁻¹ Ω · cm or more.

  Here, the volume resistivity refers to the raw material carbon material, or when the raw material carbon material is added to the master batch, expandable particles, expanded particles, and expanded molded article, the master batch, expandable particles, The carbon material taken out by removing the styrene resin in the foamed particles and the foamed molded article with an organic solvent is melt kneaded with the polystyrene resin (carbon material: polystyrene resin = 1: 4 (mass ratio)), It means a value obtained by measuring the surface of a kneaded plate-like molded body. The detailed volume resistivity measurement method is as described in International Publication WO2016 / 017813. In addition, even if it uses resin (for example, polyethylene-type resin) other than a polystyrene-type resin, a volume resistivity becomes a comparable value. In addition, even when using a carbon material as a raw material, even if a carbon material taken out by removing the styrene resin in the master batch, expandable particles, expanded particles, and foamed molded article with an organic solvent is used, the volume resistivity is The value is about the same.

  Although it does not specifically limit as a measuring method of a carbon material, For example, the method etc. which use a differential thermothermal weight simultaneous measuring apparatus are mentioned.

  Examples of the carbon material include conductive carbon black as the conductive carbon material having the above volume resistivity. As the conductive carbon black, ketjen black, acetylene black, carbon nanofiber, and carbon nanotube are particularly preferable.

The carbon material used as the radiation heat transfer suppressing component preferably has a specific surface area of 10 to 3000 m ² / g. When the specific surface area is less than 10 m ² / g, the desired heat insulating performance may not be obtained. On the other hand, when the specific surface area exceeds 3000 m ² / g, workability may be reduced. When the carbon material is acetylene black, a more preferable specific surface area is 20 to 300 m ² / g. When the carbon material is ketjen black, a more preferable specific surface area is 500 to 2000 m ² / g.

1.5. Production Method of Polystyrene Resin Expandable Particles The expandable particles of the present invention can be produced by a conventionally known method for producing expandable particles, such as a melt extrusion method or a suspension polymerization method. In particular, the melt extrusion method can easily produce expandable particles from recycled raw materials, can easily produce expandable particles containing a radiation heat transfer inhibiting component, and can uniformize the composition at each position in the expandable particles. Advantageous and preferred. Hereinafter, the melt extrusion method, the suspension polymerization method, and other methods will be described in order.

1.5.1. Melt extrusion method
Step 1 of injecting a foaming agent into the melted polystyrene resin to prepare a foaming agent-containing molten resin;
And the step 2 of extruding, cutting and solidifying the foaming agent-containing molten resin into a liquid.

  More specifically, in the melt-extrusion method, in the step 1, the polystyrene resin pellets are supplied to a resin supply device, and a foaming agent is press-fitted and kneaded into the melted polystyrene resin in the resin supply device. A step of preparing an agent-containing molten resin, wherein the step 2 extrudes the foaming agent-containing molten resin from a die nozzle (small hole) attached to the tip of the resin supply device into a cooling liquid and cuts it; It is a method that is a step of solidifying and obtaining expandable particles.

  Among the melt extrusion methods, in step 2, the foaming agent-containing molten resin is directly extruded from the die nozzle into the cooling liquid, and immediately after the extrusion, the extrudate is cut with a rotary blade, and the cut particles are cooled. The method of cooling inside is called the hot cut method. In step 2, the foaming agent-containing molten resin is once extruded in the form of a strand from the die nozzle into the air, guided into the cooling liquid before the strand foams, the strand is cooled in the cooling liquid, and then cut into circles. The method of forming columnar particles is called a strand cut method (cold cut method). The expandable particles of the present invention can be produced by either a hot cut method or a strand cut method (cold cut method). In addition, any method has an advantage that an arbitrary amount of the radiation heat transfer suppressing component can be easily contained in the particles. There is also an advantage that the composition in the expandable particles can be made uniform. A preferable production method includes a hot cut method. According to the hot cut method, there is an advantage that substantially spherical expandable particles can be obtained.

  Hereinafter, although hot cut method among melt extrusion methods is explained in detail, this embodiment is not limited to conditions etc. which are described below.

1.5.1.1. The hot-cut method of the melt extrusion method Specifically, this method is a method of preparing a foaming agent-containing molten resin by press-fitting and kneading a foaming agent into a polystyrene resin melted in a resin supply apparatus, and then melting the foaming agent. Resin is transferred to the die attached to the tip of the resin supply device, extruded directly into the cooling liquid from the nozzle formed on the die, and the extrudate (foaming agent-containing molten resin) extruded into the cooling liquid is cooled. In this method, the extrudate is cooled and solidified by contact with a liquid while being cut with a rotary blade in the working liquid to obtain expandable particles.

  In this method, for example, a manufacturing apparatus shown in FIG. 1 can be used. That is, an extruder 1 as a resin supply device, a die 2 having a large number of nozzles attached to the tip of the extruder 1, a raw material supply hopper 3 for feeding raw materials into the extruder 1, A high pressure pump 4 for injecting the foaming agent into the molten resin through the foaming agent supply port 5 is provided so that the cooling water comes into contact with the resin discharge surface in which the nozzle of the die 2 is drilled, and the cooling water is circulated and supplied into the room A cutting chamber 7, a cutter 6 (high-speed rotating blade) rotatably provided in the cutting chamber 7 so as to cut the resin extruded from the nozzle of the die 2, and a cooling water flow accompanying the cutting chamber 7. The foamable particles carried in this manner are separated from the cooling water and dehydrated and dried to obtain foamable particles. The dehydrating dryer 10 with a solid-liquid separation function, and the cooling water separated by the dehydrating dryer 10 with a solid-liquid separation function Accumulate A tank 8, a high-pressure pump 9 that sends the cooling water in the water tank 8 to the cutting chamber 7, and a storage container 11 that stores foamable particles dehydrated and dried in the dehydrator 10 with a solid-liquid separation function. The manufacturing apparatus 100 is mentioned.

  An example of a procedure for producing expandable particles using the production apparatus 100 will be described. First, raw material polystyrene-based resin and other components (for example, radiation heat transfer suppressing component) other than the foaming agent are charged into the extruder 1 from the raw material supply hopper 3. The raw polystyrene resin may be mixed in advance in the form of pellets or granules and then charged from one raw material supply hopper 3 or, for example, when a plurality of lots are used, the supply amount for each lot May be introduced from a plurality of raw material supply hoppers 3 adjusted to be mixed in the extruder 1. 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 1, the polystyrene-based resin is heated and melted, and the blowing resin is pressed into the molten resin from the blowing agent supply port 5 by the high-pressure pump 4 while the molten resin is transferred to the die side. A die in which a foaming agent-containing molten resin is attached to the tip of the extruder 1 through a foreign matter removing screen provided in the extruder 1 as necessary and moving the melt to the tip side while further kneading. Extrude from No. 2 nozzle.

  Those skilled in the art can appropriately set the conditions for injecting the foaming agent into the molten resin obtained by melt kneading. The addition amount of the foaming agent can be adjusted so as to be approximately the same value as the content described for the expandable particles. Further, as described above, a foaming aid may be used in combination with a foaming agent.

  The resin discharge surface in which the nozzle of the die 2 is drilled is disposed in the cutting chamber 7 in which cooling water is circulated and supplied into the chamber, and the cutting chamber 7 contains a foaming agent extruded from the nozzle of the die 2. A cutter 6 is rotatably provided so that the molten resin can be cut. When the foaming agent-containing molten resin is extruded from the nozzle of the die 2 attached to the tip of the extruder 1, the foaming agent-containing molten resin is cut into granules and simultaneously cooled in contact with cooling water to solidify while suppressing foaming. And become expandable particles.

  The formed expandable particles are transferred from the cutting chamber 7 to the flow of cooling water and carried to the dehydrating dryer 10 with a solid-liquid separation function, where the expandable particles are separated from the cooling water and dehydrated and dried. The dried expandable particles are stored in the storage container 11.

  When the expandable particles contain a radiant heat transfer suppressing component and other components, other components are supplied into the resin supply device as necessary, and kneaded with the molten polystyrene resin, and the kneaded molten resin Inject foaming agent.

1.5.2. Suspension polymerization method Suspension polymerization method is a method in which a polymerization initiator is dissolved in a monomer for forming a polystyrene-based resin. Thus, this is a method for obtaining expandable particles. The method of adding a foaming agent during the polymerization and / or after the polymerization is called a one-stage method. The particles obtained by polymerization without adding a blowing agent are screened, and only the particles in the required particle size range are heated in water in which the suspending agent in the reaction vessel is dispersed, and the blowing agent is added here. The method of impregnating the particles is called a two-stage method (post-impregnation method). Also, small polystyrene particles (seed particles) are put into a reaction vessel containing water in which a suspending agent is dispersed, and after raising the temperature, the monomer in which the polymerization initiator is dissolved is continuously added to the reaction vessel. The method of supplying to the polymer and polymerizing it to grow to the target particle size is called seed polymerization. In the seed polymerization method, the foaming agent is added during the polymerization and / or after the completion of the polymerization. The expandable particles of the present invention can be produced by any one of the one-stage method, the two-stage method (post-impregnation method), and the seed polymerization method. In addition, any method has an advantage that true spherical expandable particles can be obtained. A preferable production method includes a seed polymerization method.

  Hereinafter, the seed polymerization method of the suspension polymerization method will be described in more detail. However, the present embodiment is not limited to the conditions described below.

1.5.2.1. Seed polymerization method of suspension polymerization method As this method , seed resin particles containing polystyrene resin are absorbed and polymerized to obtain polystyrene resin particles, and foamed during and / or after polymerization. A method of obtaining expandable particles by injecting an agent is mentioned.

1.5.2.1. (I) Seed particles Seed particles produced by a known method can be used. For example, a polystyrene resin is melt-kneaded with an extruder, extruded into a strand shape, and the strand is cut to obtain seed particles. An extrusion method may be mentioned. In addition, the resin particles can be used for part or all of the seed particles. In the case of using a recovered product, production of seed particles by an extrusion method is suitable.

  The average particle size of the seed particles can be adjusted as appropriate according to the average particle size of the resin particles. Furthermore, although the weight average molecular weight of the polystyrene-type resin which comprises seed | species particle | grains is not specifically limited, 100,000-500,000 are preferable, More preferably, it is 150,000-400,000.

  When the foamable particles include a radiation heat transfer suppressing component, it is preferable to use seed particles including a radiation heat transfer suppressing agent and a polystyrene resin. The content of the radiant heat transfer suppressing component in the seed particles can be appropriately adjusted so that the radiant heat transfer suppressing component has the above-described content in the finally obtained expandable particles.

1.5.2.1. (Ii) Polymerization process In a dispersion obtained by dispersing seed particles in an aqueous medium, the monomer is absorbed into the seed particles by supplying a monomer that forms a polystyrene-based resin. Polystyrene resin particles can be obtained by polymerization.

  The addition amount of the monomer is preferably 50 parts by weight or more with respect to 100 parts by weight of the total addition amount of the seed particles and the supplied monomer.

  Examples of the aqueous medium include water and a mixed medium of water and a water-soluble solvent (for example, alcohol).

  The monomer to be supplied may contain a polymerization initiator. The polymerization initiator is not particularly limited as long as it is used for polymerization of a polystyrene resin from a monomer. For example, benzoyl peroxide, t-butyl peroxybenzoate, t-butyl peroxy-2-ethylhexanoate, lauryl peroxide, t-butyl peroxide, t-butyl peroxypivalate, t-butyl peroxyisopropyl Carbonate, t-butyl peroxyacetate, 2,2-t-butylperoxybutane, t-butylperoxy-3,3,5-trimethylhexanoate, di-t-butylperoxyhexahydroterephthalate, 2, Examples thereof include organic peroxides such as 5-dimethyl-2,5-di (benzoylperoxy) hexane and dicumyl peroxide, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile. Among these initiators, in order to reduce the residual monomer, two or more different polymerization initiators having a decomposition temperature of 80 to 120 ° C. for obtaining a half-life of 10 hours may be used in combination. In addition, a polymerization initiator may be used independently or 2 or more types may be used together.

  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. Examples thereof include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyacrylamide, and polyvinyl pyrrolidone, and poorly soluble inorganic compounds such as tricalcium phosphate, magnesium pyrophosphate, magnesium oxide, and hydroxyapatite. And when using a sparingly soluble inorganic compound as said suspension stabilizer, it is preferable to use an anionic surfactant together, and as such anionic surfactant, for example, fatty acid soap, N-acylamino acid or its Salts, carboxylates such as alkyl ether carboxylates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, sulfonates such as dialkylsulfosuccinates, alkylsulfoacetates, α-olefinsulfonates; higher alcohol sulfates Ester salts, secondary higher alcohol sulfates, sulfates such as alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, etc .; phosphates such as alkyl ether phosphates, alkyl phosphates, etc. Is mentioned.

  Although a polymerization process changes with monomer types to be used, a polymerization initiator seed | species, superposition | polymerization atmosphere, etc., it is normally performed by maintaining 70-130 degreeC heating for 3 to 10 hours. The polymerization step may be performed while impregnating the monomer. In the polymerization step, the total amount of the monomers used may be polymerized in one step, or may be polymerized in two or more steps (including polymerization during the production of seed particles).

1.5.2.1. (Iii) Foaming agent impregnation step The foamable particles can be obtained by impregnating the above styrene resin particles with a foaming agent.

  The impregnation may be performed wet simultaneously with the polymerization, or may be performed wet or dry after the polymerization. When it is carried out in a wet manner, it may be carried out in the presence of a suspension stabilizer and a surfactant exemplified in the polymerization step. The impregnation temperature of the foaming agent is preferably 60 to 120 ° C. When the temperature is lower than 60 ° C., the time required for impregnating the resin particles with the foaming agent becomes long, and the production efficiency may decrease. On the other hand, when the temperature is higher than 120 ° C., the resin particles may be fused to generate bonded particles. A more preferable impregnation temperature is 70 to 110 ° C.

  The amount of the foaming agent to be impregnated can be adjusted so that the amount of the foaming agent to be impregnated is approximately the same value as the content described for the expandable particles. Further, as described above, a foaming aid may be used in combination with a foaming agent. The types of foaming aids and the like are as described above, and the amount added can be appropriately set by those skilled in the art.

1.5.3. Other methods As an example of other methods, in the melt extrusion method, after obtaining styrene resin particles without press-fitting a foaming agent, the particles are foamed by a suspension polymerization two-stage method (post-impregnation method). Examples thereof include a method for producing expandable particles of styrene resin by impregnating an agent, and a method for producing expandable particles in the seed polymerization method of suspension polymerization using the particles as seed particles. The foamable particles of the present invention can also be produced by these methods. A preferable production method includes a method in which polystyrene resin particles not containing a foaming agent are obtained by a melt extrusion method, and then expandable particles are produced by seed polymerization using the particles as seed particles.

2. Polystyrene resin expanded particles The polystyrene resin expanded particles of the present invention (sometimes referred to as “expanded particles” in the present specification) are polystyrene resin expanded particles containing a polystyrene resin in which bubbles are formed. The polystyrene resin has the characteristics described in 1.2 above. The polystyrene-based resin contained in the expanded particles of the present invention has the same characteristics as the polystyrene-based resin included in the expandable particles of the present invention described in 1.1 above. It may be present as a mixture with the components.

  The expanded particles of the present invention can be obtained by expanding the expandable particles of the present invention to a desired bulk expansion ratio (bulk density) using water vapor or the like. The volume expansion ratio of the expanded particles is, for example, 3 to 100 times, more preferably 65 to 100 times, and particularly preferably 70 to 85 times. Expanded particles containing a polystyrene-based resin satisfying characteristics 1 to 3 are excellent in foam moldability when performing in-mold foam molding and excellent in mechanical strength while having a high expansion ratio. Moreover, since the closed cell ratio is high, heat insulation is high.

  In addition, it is preferable to apply powder metal soaps such as zinc stearate to the surface of the expandable particles before foaming. By applying, the bonding between the foamed particles can be reduced in the foaming process of the foamable particles.

  The expanded particles of the present invention can be used as pre-expanded particles for forming expanded molded articles. The expanded particles of the present invention can also be used as a buffer or a heat insulating material. When the expanded particles of the present invention are used as a cushioning material or a heat insulating material, it is preferable to use the expanded particles as a filling material in which a large number of expanded particles are filled in a bag. Insulating materials can be used for wall insulation, floor insulation, roof insulation, automotive insulation, hot water tank insulation, piping insulation, solar system insulation, water heater insulation, etc. . In particular, it can be suitably used as a heat insulating material for living spaces such as a heat insulating material for walls, a heat insulating material for floors, a heat insulating material for roofs, and a heat insulating material for automobiles.

<Bulk expansion ratio and bulk density of expanded particles>
First, Wg was collected as a measurement sample of foamed particles, and this measurement sample was naturally dropped into a graduated cylinder, and the volume Vcm ³ of the measurement sample dropped into the graduated cylinder was measured using an apparent density measuring instrument in accordance with JIS K6911. Measure and measure the bulk expansion ratio and the bulk density of the expanded particles based on the following formula.

Bulk foaming multiple (times = cm ³ / g) = volume of measurement sample (V) / mass of measurement sample (W)
Bulk density (g / cm ³ ) = mass of measurement sample (W) / volume of measurement sample (V)

3. Polystyrene resin foam molded article The polystyrene resin foam molded article of the present invention (sometimes referred to as “foam molded article” in this specification) contains a plurality of polystyrene-based resins in which bubbles are formed and fused together. A polystyrene-based resin foam molded article composed of expanded particles, wherein the polystyrene-based resin has the characteristics described in 1.2 above. The polystyrene resin contained in the foamed molded product of the present invention has the same characteristics as the polystyrene resin contained in the expandable particles of the present invention described in 1.1 above, and further described in 1.4 above. May be present as a mixture with the other components.

  The expansion ratio of the foamed molded product is, for example, 3 to 100 times, more preferably 65 to 100 times, and particularly preferably 70 to 85 times. A foamed molded article containing a polystyrene-based resin that satisfies characteristics 1 to 3 is excellent in mechanical strength while having a high expansion ratio. Moreover, since the closed cell ratio is high, heat insulation is high.

  The foamed molded product of the present invention can be used for various uses such as a heat insulating material, a container, and a packing material. The foamed molded product can take a shape corresponding to the intended use. Insulating materials can be used for wall insulation, floor insulation, roof insulation, automotive insulation, hot water tank insulation, piping insulation, solar system insulation, water heater insulation, etc. . In particular, it can be suitably used as a heat insulating material for living spaces such as a heat insulating material for walls, a heat insulating material for floors, a heat insulating material for roofs, and a heat insulating material for automobiles.

  The foam molded article can be obtained, for example, by the following method. Fill the foamed particles of the present invention into a closed mold having a large number of small holes, heat and foam with a heat medium (for example, pressurized water vapor) to fill the gaps between the foamed particles, and fuse the foamed particles to each other By making it integral, a foaming molding can be manufactured. At that time, the density of the foamed molded product can be adjusted, for example, by adjusting in advance the bulk expansion ratio of the foamed particles to be filled in the mold, or by adjusting the filling amount of the foamed particles in the mold.

  The heating and 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 particles can be ensured. More preferably, the heat foaming can be performed by heating for 10 to 50 seconds with a heat 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 foamed particles may be aged, for example, at normal pressure before molding the foamed molded product. The aging temperature of the expanded particles is preferably 20 to 60 ° C. When the aging temperature is low, the aging time of the expanded particles may be long. On the other hand, if it is high, the foaming agent in the foamed particles may dissipate and the moldability may deteriorate.

<Folding factor and density of foamed molded product>
In the present invention, the density of the foamed molded product is a density measured by the method described in JIS K7222: 2005 “Measurement of foamed plastic and rubber-apparent density”. Specifically, the expansion ratio and density of the foamed molded product can be measured by the following method.

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.

Foaming factor (times = cm ³ / g) = test piece volume (cm ³ ) / test piece mass (g)
Density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ )

  Condition adjustment of test piece: A test piece for measurement was cut out from a sample that had passed 72 hours or more after molding, and was subjected to atmospheric conditions of 23 ° C ± 2 ° C x 50% ± 5% or 27 ° C ± 2 ° C x 65% ± 5% It has been left for more than an hour.

4). Heat insulating material for living space The foamed particles and the foamed molded product of the present invention preferably have a total content of aromatic organic compounds composed of styrene monomer, ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, toluene, benzene of 2000 ppm. It is used as a heat insulating material for living space that is less than. If the total content of the aromatic organic compound is less than 2000 ppm, it is possible to cope with sick house syndrome, which has been recently requested, and to provide a more comfortable living space. More preferably, it is 1750 ppm or less, More preferably, it is 1500 ppm or less, Most preferably, it is 500 ppm or less, Most preferably, it is 300 ppm or less. By selecting a resin raw material with a low content of aromatic organic compounds consisting of styrene monomer, ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, toluene, and benzene as the raw material polystyrene resin, Thus, it is possible to obtain styrene resin foamable particles, foamed particles, foamed molded products, and heat insulating materials for living spaces without mixing the aromatic organic compound. A melt extrusion method is preferred as a production method for obtaining styrene resin expandable particles having a small total content of the aromatic organic compound.

[Examples and Comparative Examples]
<Measurement method of M _{Z + 1} and M _Z >
3 mg of a sample (expandable particles, expanded particles, foamed molded product) was allowed to stand for 72 hours in 10 mL of tetrahydrofuran (THF) for dissolution (complete dissolution), and the resulting solution was non-aqueous 0.45 μm made by Kurashiki Boseki Co., Ltd. Measured by filtration through a chromatodisc (13N). The average molecular weight of the sample is determined from a standard polystyrene calibration curve measured and prepared in advance. The chromatographic conditions are as follows.

(Molecular weight measurement conditions)
Equipment used: High-speed GPC equipment: HLC-8320GPC EcoSEC system manufactured by Tosoh Corporation (with built-in RI detector)
Guard column: Tosoh TSK guard column SuperHZ-H (4.6 mm ID × 2 cmL) × 1 Column: Tosoh TSKgel SuperHZM-H (4.6 mm ID × 15 cmL) × 2 Column temperature: 40 ° C.
System temperature: 40 ° C
Mobile phase: Tetrahydrofuran Mobile phase flow rate: Sample side 0.175 mL / min, Reference side 0.175 mL / min Detector: RI detector Sample concentration: 0.3 g / L
Injection volume: 50 μL
Measurement time: 0-25 minutes Runtime: 25 minutes Sampling pitch: 200 msec

(Create a calibration curve)
As standard polystyrene samples for calibration curves, the weight average molecular weights of trade names “TSK standard POLYSTYRENE” manufactured by Tosoh Corporation are 5,480,000, 3,840,000, 355,000, 102,000, 37,900, 9 , 100, 2,630, and 500, and standard polystyrene samples having a weight average molecular weight of 1,030,000 with a trade name “Shodex STANDARD” manufactured by Showa Denko KK are used.

The method of creating a calibration curve is as follows. The above standard polystyrene samples for calibration curves are group A (with a weight average molecular weight of 1,030,000), group B (weight average molecular weights of 3,840,000, 102,000, 9,100, 500) and group C. (The weight average molecular weight is 5,480,000, 355,000, 37,900, 2,630). Group A was weighed 5 mg and then dissolved in 20 mL of tetrahydrofuran, Group B was also weighed 5 mg to 10 mg each and then dissolved in 50 mL of tetrahydrofuran, and Group C was also weighed 1 mg to 5 mg and then dissolved in 40 mL of tetrahydrofuran. The standard polystyrene calibration curve was prepared by injecting 50 μL of the prepared A, B and C solutions, and using the retention time obtained after measurement, a calibration curve (third-order equation) was sent to the data analysis program GPC workstation (EcoSEC-WS) dedicated to HLC-8320 obtained by creating Te, its using a calibration curve carried out GPC measurement of the _{sample, M z + 1, M z} , and the curves of LogM the integral molecular weight distribution of the obtained molecular weight M M _{z + 1} or more The content of the component is calculated.

<Measuring method of melt flow rate>
Melt flow rate (MFR) was measured in accordance with the method described in JIS K 7210: 1999 “Plastics—Test methods for melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics” B method. Say. Specifically, for example, using a measuring device commercially available from Toyo Seiki Seisakusho Co., Ltd. under the trade name “semi-auto melt indexer”, a sample (expandable particles, expanded particles, foamed molded product) is placed in the cylinder of this measuring device. 3 to 8 g is packed and the sample is compressed using a filling rod, and the melt flow rate of the polystyrene resin is measured under the measurement conditions of a test temperature of 200 ° C., a load of 49.03 N, and a preheating time of 4 minutes. And let the number of tests be 3 or more, and let the arithmetic average value of the melt flow rate of the polystyrene resin obtained by each measurement be the melt flow rate of the polystyrene resin.

<Measuring method of melt tension>
The melt tension (MT) is measured using a twin-bore capillary rheometer Rheological 5000T (Chiast, Italy). Specifically, first, a measurement sample resin (expandable particles, expanded particles, foamed molded product) is filled in a 15 mm diameter barrel heated to a test temperature of 200 ° C., and then preheated for 5 minutes. Next, the piston descending speed (0.07730 mm / s) is kept constant from the orifice (2.095 mm diameter, 8 mm length, inflow angle 90 degrees (conical)) of the piston extrusion type plastometer of the above measuring device, and the string shape The resulting string is passed through a tension detecting pulley located 27 cm below the orifice. Then, the said string-like thing is wound up using the winding roll, gradually increasing the winding speed at the initial speed of 3.94388 mm / s and the acceleration of 12 mm / s ² . Then, the average tension of the maximum value and the minimum value immediately before the point at which the string-like material is cut is defined as the melt tension (MT) of the sample resin.

<Measurement method of maximum elongation viscosity at 160 ° C. and strain hardening index in uniaxial elongation viscosity measurement>
(Sample preparation)
A polystyrene resin sample (expandable particles, expanded particles, foamed molded product) is weighed with a 5 to 6 g balance, and the measured polystyrene resin is sandwiched between polytetrafluoroethylene sheets and pressed under the following conditions.
Press machine: Small heat press machine manufactured by Toyo Seiki Co., Ltd. Trade name “Lab Press 10T”
Temperature: Upper heater 180 ° C, Lower heater 180 ° C
Press pressure: Low pressure 0.54 MPa, High pressure 15.5 MPa
Pressing process: Press for 3 minutes at low pressure → Press 5 times at low pressure (2 seconds up, 2 seconds down 5 times) → Press under high pressure for 2 minutes

(Measurement of uniaxial elongational viscosity)
The measurement of the uniaxial elongation viscosity with respect to a polystyrene-type resin can be implemented on condition of the following.
Measuring device: Viscoelasticity measuring device “PHYSICAMCR301” (manufactured by Anton Paar)
Measurement mode: Oscillation measurement (temperature dependence)
Measurement conditions: Frequency (1 Hz) distortion 0.5 sec ⁻¹
Temperature condition: 160 ° C constant number of tests: 2
Geometry: Parallel plate φ25mm, GAP2.0mm (auto compression)
Atmospheric gas: Nitrogen test piece creation: Plate formation 190 ° C Thickness 3mm diameter 25mm Plate test procedure: Sample is preheated on the plate (measurement temperature) for 5 minutes, then GAP is 2.0mm, the resin is scraped, and 5 minutes after reaching the measurement temperature The measurement starts later.

  In the case of a sample in which the polystyrene resin exhibits strain hardening properties, strain hardening appears on the logarithmic graph of the extension viscosity and time measured in the uniaxial extension viscosity measurement and shows a rapid increase in the extension viscosity. In particular, the maximum elongational viscosity is shown in the vicinity where breakage of the sample is observed.

  In the case of a sample that does not exhibit strain hardening, after forming a peak of elongational viscosity on a logarithmic graph of elongational viscosity and time, the peak value of the peak becomes the maximum elongational viscosity because it gradually decreases.

  The strain hardening index is a linear approximation of the area where the logarithmic graph shows the maximum extensional viscosity in the above range before the increase in extensional viscosity. Is extended to a region where the maximum elongation viscosity is rapidly increased, the elongation viscosity value of the approximate straight line at the time when the maximum elongation viscosity is indicated, and the maximum elongation viscosity value is divided by the elongation viscosity value of the approximate straight line. Can be obtained as a value.

  When the value of the maximum elongation viscosity is the same as the value of the extension viscosity on the approximate straight line at the time showing the maximum elongation viscosity, it can be determined that strain hardening is not recognized. In this case, the strain hardening index is 1.0.

<Method of measuring glass transition point of polystyrene resin>
The glass transition point (Tg) of the polystyrene resin can be measured using a differential scanning calorimeter (DSC) based on the method described in JIS K7121: 1987 “Method for Measuring Transition Temperature of Plastic”. More specifically, for example, a model name “DSC6220 type” manufactured by SII Nanotechnology Co., Ltd. is used, and a polystyrene-based resin is used so that there is as little gap as possible on the bottom of an aluminum measurement container on the sample side of the DSC. A sample filled with about 6.5 mg of a sample (expandable particles, expanded particles, foamed molded product) is placed, and an aluminum measuring container containing alumina is placed on the reference side, and a nitrogen gas flow rate of 25 ml / min is used at 20 ° C. The temperature was increased from 30 ° C. to 200 ° C. at a temperature increase rate of / min, held for 10 minutes, quickly removed, allowed to cool in an environment of 25 ± 10 ° C., and then again at a rate of 20 ° C./min The glass transition temperature of the polystyrene resin can be obtained by calculating the midpoint glass transition temperature from the DSC curve obtained when the temperature is raised to 200 ° C. The midpoint glass transition temperature can be determined according to “9.3 Determination of Glass Transition Temperature” of the same standard.

<Method for measuring open cell ratio of foamed molded article>
The open cell ratio of the foam molded article is measured by the following method.
First, the polystyrene resin foam molded body was cut out so that all six surfaces of the molded body did not have a molding surface skin, and the surface of the cut surface was finished with a pan slicer to produce five 25 mm × 25 mm × 25 mm cubic test pieces. To do. Each test piece is conditioned in a JIS K7100-1999 symbol 23/50, second grade environment for 16 hours, and then measured in a JIS K7100-1999 symbol 23/50, second grade environment. First, the outer dimension of the obtained test piece is measured to 1/100 mm using “Digimatic Caliper” manufactured by Mitutoyo Corporation, and the apparent volume (cm ³ ) is obtained. Next, the volume (cm ³ ) of the measurement sample is determined by the 1-1 / 2-1 atmospheric pressure method using an air comparison type hydrometer 1000 type (manufactured by Tokyo Science Co., Ltd.). The open cell ratio (%) is calculated by the following formula, and the average value of the open cell ratio of the five test pieces is obtained. The air-comparing hydrometer corrects with a standard sphere (large 28.9 cc, small 8.5 cc).

  Open cell ratio (%) = 100 × (apparent volume−volume measured with an air-based hydrometer) / apparent volume

<Measurement method of foamable minimum bulk density of polystyrene resin foamable particles>
The polystyrene resin expandable particles are expanded by heating to become expanded particles. The bulk density of the expanded particles decreases as the heating time increases, but if the heating time is too long, the expanded particles contract and the bulk density starts to increase. The minimum bulk density at this time is defined as the minimum foamable foam density of the polystyrene resin foamable particles, and is measured by the following method.

  Foaming is performed by heating the polystyrene resin foamable particles with water vapor of 0.06 MPa. At this time, the heating time is extended by 60 seconds, 75 seconds, 90 seconds,..., 270 seconds, 285 seconds, and 300 seconds by 15 seconds. The bulk density at each heating time is measured, and the minimum bulk density is defined as the minimum foamable bulk density.

<Example 1>
To 100 parts by mass of virgin hyperbranched polystyrene having a weight average molecular weight of 400,000 (trade name “HP-555”, manufactured by DIC), 0.5 part by mass of fine powder talc is added as an inorganic foam nucleating agent. The single screw extruder was continuously fed at 150 kg per hour. The extruder internal temperature was set to a maximum temperature of 220 ° C., and after the resin was melted, 9 parts by mass of isopentane was injected from the middle of the extruder as a foaming agent to 100 parts by mass of the resin. 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. Furthermore, the collected particles were dehydrated and dried to obtain styrene resin foamable particles. The obtained styrenic resin expandable particles were almost spherical without deformation and beard, and the average particle size was about 1.1 mm.

  Polyethylene glycol 0.03 parts by mass, zinc stearate 0.15 parts by mass, stearic acid monoglyceride 0.05 parts by mass, hydroxystearic acid triglyceride 0.05 parts by mass with respect to 100 parts by mass of the obtained styrenic resin expandable particles. The portion was uniformly coated on the entire surface of the styrene resin expandable particles.

By heating the styrene resin expandable particles produced as described above, pre-expanded particles were obtained by pre-expanding to a bulk density of 0.0125 g / cm ³ (bulk expansion ratio: 80 times). The pre-expanded particles were aged at 20 ° C. for 24 hours.

Next, the pre-expanded particles were filled in a mold and heated and foamed to obtain a foamed molded product having a length of 400 mm × width of 300 mm × thickness of 30 mm. The foamed molded product was dried in a drying chamber at 50 ° C. for 6 hours, and then the density of the foamed molded product was measured. As a result, the density was 0.0125 g / cm ³ (expansion factor 80 times). This foamed molded article was excellent in appearance without shrinkage.

<Example 2>
Into a polymerization vessel equipped with a stirrer with an internal volume of 100 liters, 40000 parts by mass of water, 100 parts by mass of magnesium pyrophosphate as a suspension stabilizer and 5.0 parts by mass of sodium dodecylbenzenesulfonate as an anionic surfactant are fed and stirred. After adding 40,000 parts by mass and 120 parts by mass of benzoyl peroxide and 28.0 parts by mass of t-butylperoxybenzoate as polymerization initiators, the temperature was raised to 90 ° C. to polymerize. And it hold | maintained at this temperature for 6 hours, and also, after heating up to 125 degreeC, it cooled after 2 hours, and obtained the seed particle (b) of the styrene resin particle | grains of the weight average molecular weight 300,000.

  Next, 2350 g of seed particles (b), 30 g of magnesium pyrophosphate and 10 g of sodium dodecylbenzenesulfonate were supplied to a polymerization vessel equipped with a stirrer having an internal volume of 25 L and heated to 72 ° C. while stirring to prepare a dispersion. Then 28 g of benzoyl peroxide, t-butyl peroxybenzoate 6. A solution prepared by dissolving 1 g in a monomer mixture of 850 g of styrene and 150 g of butyl acrylate was supplied to the dispersion while stirring. And it maintained for 60 minutes, after supplying the said solution in a dispersion liquid (1st process).

  Thereafter, 2650 g of styrene was supplied to the dispersion over 1 hour, and then a dispersion of 1.2 g of divinylbenzene dissolved in 4000 g of styrene was supplied at a constant rate in 90 minutes. The temperature was maintained at 90 ° C. for 90 minutes (second step). Thereafter, by cooling, multi-branched polystyrene particles (a) having a weight average molecular weight of 300,000 were obtained.

Thereafter, the polystyrene raw material supplied to the extruder was changed to the multi-branched polystyrene particles (a), and the density was changed in the same manner as in Example 1 except that the amount of isopentane injected into 100 parts by mass of resin was changed to 7.5 parts by mass. A foamed molded article of 0.0125 g / cm ³ (expansion factor 80 times) was obtained. This foamed molded article was excellent in appearance without shrinkage.

<Example 3>
A density of 0.0125 g / cm ³ was obtained in the same manner as in Example 2 except that HP-555 was changed to 50 parts by mass of the polystyrene raw material supplied to the extruder and 50 parts by mass of the multi-branched polystyrene particles (a) of Example 2. A foamed molded product having an expansion ratio of 80 times was obtained. This foamed molded article was excellent in appearance without shrinkage.

<Example 4>
As the polystyrene raw material supplied to the extruder, 95 parts by mass of the multi-branched polystyrene particles (a) of Example 2, conductive carbon black (average primary particle diameter 35 nm, specific surface area 80 m ² / g), and inorganic foam nucleating agent A density of 0.0125 g in the same manner as in Example 1 except that 0.5 parts by mass of fine powder talc and 5 parts by mass of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) as a flame retardant are added. A foamed molded article of / cm ³ (expansion factor 80 times) was obtained. This foamed molded article was excellent in appearance without shrinkage.

<Comparative Example 1>
Styrene resin in the same manner as in Example 1 except that the polystyrene raw material supplied to the extruder is changed to 100 parts by mass of virgin polystyrene having a weight average molecular weight of 200,000 (trade name “HRM-10N” manufactured by Toyo Styrene Co., Ltd.). Expandable particles were obtained. Polyethylene glycol 0.03 parts by mass, zinc stearate 0.15 parts by mass, stearic acid monoglyceride 0.05 parts by mass, hydroxystearic acid triglyceride 0.05 parts by mass with respect to 100 parts by mass of the obtained styrenic resin expandable particles. The portion was uniformly coated on the entire surface of the styrene resin expandable particles.
Although it was tried to obtain pre-expanded particles having a bulk density of 0.0125 g / cm ³ (bulk expansion factor: 80 times) by heating the styrene resin expandable particles produced as described above, the bulk density was 0.0167 g / Only pre-expanded particles of cm ³ (bulk expansion ratio 60 times) were obtained. The pre-expanded particles were aged at 20 ° C. for 24 hours.

Next, the pre-expanded particles were filled in a mold and heated and foamed to obtain a foamed molded product having a length of 400 mm × width of 300 mm × thickness of 30 mm. The foamed molded product was dried in a drying chamber at 50 ° C. for 6 hours, and then the density of the foamed molded product was measured. As a result, the density was 0.0167 g / cm ³ (expansion factor 60 times). This foamed molded article was excellent in appearance without shrinkage.

The details of an attempt to obtain pre-expanded particles having a bulk density of 0.0125 g / cm ³ (bulk foaming factor 80 times) are as follows: bulk density less than 0.0167 g / cm ³ (bulk foaming factor exceeding 60 times) When the styrene resin foamable particles were continuously heated to obtain the prefoamed particles, the prefoamed particles contracted, and the prefoamed particles having a bulk density of less than 0.0167 g / cm ³ (bulk foaming ratio exceeding 60 times). Could not get.

<Measurement results>
According to the above procedure, GPC measurement, MFR measurement, MT measurement, uniaxial extensional viscosity measurement, and Tg measurement were performed on the expandable particles, expanded particles, and foamed molded products obtained in Examples 1 to 4 and Comparative Example 1, and the foamed molded product was measured. The foaming particles were further measured for the foamable minimum bulk density.

  The measurement results are shown in Tables 1 to 3 below.

  1: Extruder (resin supply device), 2: Die, 3: Raw material supply hopper, 4: High pressure pump, 5: Foaming agent supply port, 6: Cutter (high-speed rotary blade), 7: Cutting chamber, 8: Water tank, 9: High-pressure pump, 10: Dehydration dryer, 11: Storage container, 100: Manufacturing equipment

Claims (15)

A polystyrene resin expandable particle containing a polystyrene resin and a foaming agent,
The polystyrene resin has a Z + 1 average molecular weight (M _{Z + 1} ) of 800,000 to 3,000,000 in the measurement by gel permeation chromatography, and the ratio of M _{Z + 1} to the Z average molecular weight (M _Z ) (M _{Z + 1)} / M _Z ) is 1.8 or more,
The polystyrene resin has a melt flow rate (MFR) measured at 200 ° C. of 10.0 g / 10 min or less and a melt tension (MT) measured at 200 ° C. of 4 cN or more,
The polystyrene resin has a maximum elongation viscosity at 160 ° C. in a uniaxial elongation viscosity measurement of 1.0 × 10 ⁶ Pa · S or more, and a strain hardening index of 1.1 or more.
A polystyrene resin foamable particle, characterized in that.   The polystyrene resin expandable particle according to claim 1, wherein the polystyrene resin has a glass transition point (Tg) of 80 to 110 ° C.   The polystyrene resin foamable particles according to claim 1 or 2, wherein the foaming agent is pentane.   The polystyrene-based resin foamable particles according to any one of claims 1 to 3, comprising a radiation heat transfer inhibiting component. Step 1 of injecting the foaming agent into the melted polystyrene resin to prepare a foaming agent-containing molten resin;
The polystyrene-based resin foamable particles according to any one of claims 1 to 4, produced by a method comprising a step 2 of extruding, cutting and solidifying the foaming agent-containing molten resin into a liquid. A polystyrene-based resin expanded particle containing a polystyrene-based resin in which bubbles are formed,
The polystyrene resin has a Z + 1 average molecular weight (M _{Z + 1} ) of 800,000 to 3,000,000 in the measurement by gel permeation chromatography, and the ratio of M _{Z + 1} to the Z average molecular weight (M _Z ) (M _{Z + 1)} / M _Z ) is 1.8 or more,
The polystyrene resin has a melt flow rate (MFR) measured at 200 ° C. of 10.0 g / 10 min or less and a melt tension (MT) measured at 200 ° C. of 4 cN or more,
The polystyrene resin has a maximum elongation viscosity at 160 ° C. in a uniaxial elongation viscosity measurement of 1.0 × 10 ⁶ Pa · S or more, and a strain hardening index of 1.1 or more.
Polystyrene-based resin expanded particles, characterized in that.   The polystyrene resin expanded particles according to claim 6, wherein the polystyrene resin has a glass transition point (Tg) of 80 to 110 ° C.   The polystyrene-based resin expanded particles according to claim 6 or 7, comprising a radiation heat transfer inhibiting component. A polystyrene-based resin foam molded article comprising a plurality of foamed particles containing polystyrene-based resin in which bubbles are formed and fused together,
The polystyrene resin has a Z + 1 average molecular weight (M _{Z + 1} ) of 800,000 to 3,000,000 in the measurement by gel permeation chromatography, and the ratio of M _{Z + 1} to the Z average molecular weight (M _Z ) (M _{Z + 1)} / M _Z ) is 1.8 or more,
The polystyrene resin has a melt flow rate (MFR) measured at 200 ° C. of 10.0 g / 10 min or less and a melt tension (MT) measured at 200 ° C. of 4 cN or more,
The polystyrene resin has a maximum elongation viscosity at 160 ° C. in a uniaxial elongation viscosity measurement of 1.0 × 10 ⁶ Pa · S or more, and a strain hardening index of 1.1 or more.
A polystyrene-based resin foam molded article, characterized in that.   The polystyrene resin foam molded article according to claim 9, wherein the polystyrene resin has a glass transition point (Tg) of 80 to 110 ° C.   The polystyrene resin foam molded article according to claim 9 or 10, comprising a radiation heat transfer inhibiting component.   The heat insulation for living spaces containing the polystyrene-type resin expanded particle of any one of Claims 6-8, and / or the polystyrene-type resin foam molded object of any one of Claims 9-11. Wood. A method for producing the polystyrene-based resin expandable particles according to any one of claims 1 to 5,
Step 1 of injecting the foaming agent into the melted polystyrene resin to prepare a foaming agent-containing molten resin;
And 2) extruding, blowing, and solidifying the foaming agent-containing molten resin into a liquid. A method for producing the polystyrene-based resin expanded particles according to any one of claims 6 to 8,
Process 3 for obtaining foamed particles by heating and foaming polystyrene-based resin foamable particles produced by the method according to claim 13.
A method comprising the steps of: A method for producing the polystyrene-based resin foam molded article according to any one of claims 9 to 11,
Step 3 of heating and foaming the polystyrene resin foamable particles produced by the method according to claim 13 to obtain foamed particles;
And a step 4 for obtaining a foamed molded product by foam-molding the foamed particles in a mold.

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