JP2017132971A - Styrenic resin foamed particle and styrenic resin foamed molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrenic resin foamed particle that can give a foamed molding having excellent heat insulation.SOLUTION: A styrenic resin foamed particle comprises a styrenic resin and a carbon material and also comprises foam of 0.2-1 mm and foam of 0.15 mm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a styrene resin expanded particle and a styrene resin expanded molded article. More specifically, the present invention relates to a styrene resin foam molded article having excellent heat insulating properties and styrene resin foam particles for producing the same.

  Conventionally, foamed molded products are lightweight and excellent in heat insulation and mechanical strength. Therefore, heat insulating materials used in houses and automobiles, heat insulating materials used in building materials, packing materials for transportation such as fish boxes and food containers, and cushioning materials. Etc. are used. Among them, in-mold foam molded articles produced using foamable particles as raw materials are often used because of the advantage that a desired shape is easily obtained.

As the foam molded article, a styrene resin foam molded article derived from styrene resin foamable particles is widely used. The styrenic resin foam molded body heats and expands styrene resin foamable particles to obtain prefoamed particles, and then heats the prefoamed particles obtained while secondary foaming in the mold cavity. It is obtained by integrating by fusing.
Styrenic resin foam moldings have various properties, for example, excellent thermal insulation properties. Excellent heat insulation is required for various applications from the viewpoint of energy saving. Specific applications include wall insulation, floor insulation, roof insulation, automotive insulation, hot water tank insulation, piping insulation, solar system insulation, water heater insulation, food And containers for industrial products, packing materials for fish and agricultural products, embankment materials, core materials for tatami mats, and the like.

  It is desired that the heat insulating property required for the foam molded body is further improved from the viewpoint of energy saving. As methods for improving the heat insulation properties, various methods such as higher magnification, change of resin composition, use of additives, operation of cell structure, etc. are known. For example, in Japanese Patent Application Laid-Open No. 2004-292489 (Patent Document 1), heat insulation is excellent from foamable particles in which microbubbles having a bubble diameter of 0.2 mm or less and coarse bubbles having a bubble diameter of 0.35 mm or more are randomly mixed. It is described that a foam can be obtained.

Japanese Patent Laid-Open No. 2004-292489

  With the technique described in the above publication, it is difficult to obtain a foamed molded article having sufficient heat insulating properties that has been required in recent years, and provision of a foamed molded article having higher heat insulating properties is desired.

  The inventors of the present invention have intensively studied to solve the above problems. As a result, the inventors have surprisingly found that a foamed article having improved heat insulation can be obtained by including a carbon material in expanded particles containing large bubbles and small bubbles, and the present invention has been completed.

Thus, according to the present invention, there is provided a styrenic resin foamed particle comprising a styrenic resin and a carbon material, comprising large bubbles of 0.2 to 1 mm and small bubbles of 0.15 mm or less. Is done.
In addition, according to the present invention, there is provided styrene resin expanded particles in which the small bubbles of 0.15 mm or less have an occupancy of 10 to 90% per the cross-sectional area of the styrene resin expanded particles.
In addition, according to the present invention, there is provided a styrene resin expanded particle in which the carbon material is conductive carbon black having a volume resistivity of 1.0 × 10 ⁴ Ω · cm or less.

Furthermore, according to the present invention, there is provided a styrene-based resin foamed molded article comprising a plurality of styrene-based resin foam particles that are fused together, including a styrene-based resin and a carbon material. Provided is a styrenic resin foam molded article in which each of the foamed particles contains large bubbles of 0.2 to 1 mm and small bubbles of 0.15 mm or less.
In addition, according to the present invention, there is provided a styrene resin foam molded article in which the small bubbles of 0.15 mm or less have an occupancy of 10 to 90% per sectional area of the styrene resin foam molded article. .
In addition, according to the present invention, there is provided a styrene-based resin foam molded body in which the carbon material is conductive carbon black having a volume resistivity of 1.0 × 10 ⁴ Ω · cm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the styrene resin foamed particle for manufacturing the styrene resin foaming molding excellent in heat insulation can be provided.

In any of the following cases, it is possible to provide styrene-based resin foamed particles for producing a styrene-based resin foam-molded article having better heat insulation.
(1) The small bubbles of 0.15 mm or less have an occupation ratio of 10 to 90% per the cross-sectional area of the styrene resin expanded particles.
(2) The carbon material is a conductive carbon black having a volume resistivity of 1.0 × 10 ⁴ Ω · cm or less.

In any of the following cases, a styrenic resin foam molded article having better heat insulation can be provided.
(1) The small bubbles of 0.15 mm or less have an occupation ratio of 10 to 90% per the cross-sectional area of the styrene resin expanded particles.
(2) The carbon material is a conductive carbon black having a volume resistivity of 1.0 × 10 ⁴ Ω · cm or less.

2 is a photograph showing a cross section of a styrene resin foam molded article produced in Example 1. FIG. It is an electron micrograph of the carbon material which formed the aggregate.

(Styrene resin foam particles)
Styrene-based resin expanded particles (hereinafter referred to as expanded particles) include large bubbles and small bubbles. FIG. 1 illustrates expanded particles containing such large bubbles and small bubbles.

(1) Bubbles In the present specification, large bubbles refer to bubbles having a bubble diameter of 0.2 to 1 mm. Foam that gives a styrenic resin foam molded article (hereinafter referred to as a foam molded article) having sufficient heat insulation properties, regardless of whether the large bubble diameter is less than 0.2 mm or the large bubble diameter exceeds 1 mm. It becomes difficult to obtain particles. The bubble diameter of the large bubbles is preferably 0.25 to 0.7 mm, more preferably 0.3 to 0.5 mm.

  In this specification, a small bubble means the bubble which has a bubble diameter of 0.15 mm or less. When the bubble diameter of the small bubbles exceeds 0.15 mm, it is difficult to obtain expanded particles that give a foamed molded article having sufficient heat insulation. The bubble diameter of the small bubbles is preferably 0.13 mm or less, more preferably 0.10 mm or less.

On the cut surface of the expanded particles or the expanded molded body, the bubbles are mainly composed of large bubbles of 0.2 to 1 mm and small bubbles of 0.15 mm or less. On the other hand, there are a small number of bubbles having an intermediate bubble diameter, that is, a bubble diameter of more than 0.15 mm and less than 0.2 mm. There are a small number of bubbles exceeding 1 mm.
The occupation ratio of the small bubbles is preferably 10 to 90% per cross-sectional area of the styrene resin expanded particle. In any case where the occupancy of the small bubbles is less than 10% or more than 90%, it is difficult to obtain expanded particles that give a foamed molded article having sufficient heat insulation. The occupation ratio of small bubbles is more preferably 20 to 80%, still more preferably 30 to 70%.
The occupation ratio of the large bubbles is preferably 10 to 90% per cross-sectional area of the styrene resin expanded particle. In any case where the occupation ratio of the large bubbles is less than 10% or more than 90%, it is difficult to obtain expanded particles that give a foamed molded article having sufficient heat insulation. The occupation ratio of the large bubbles is more preferably 20 to 80%, still more preferably 30 to 70%.

(2) Styrene resin Foamed particles contain a styrene resin. The styrenic resin is not particularly limited as long as it is a resin capable of obtaining a foam molded article. For example, styrene monomers such as styrene, α-methyl styrene, vinyl toluene, ethyl styrene, i-propyl styrene, t-butyl styrene, dimethyl styrene, bromo styrene, chloro styrene, or a mixture of these monomers The resin derived from is mentioned.
The styrene resin may contain 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. A (meth) acrylate compound etc. are mentioned.

  The styrenic resin may be a copolymer of another monomer and the styrenic monomer in an amount that does not impair the characteristics of the present invention. Examples of other monomers include (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth) acrylate. Esters, alkyl maleates such as (meth) acrylonitrile, dimethyl maleate and diethyl maleate, alkyl fumarates such as dimethyl fumarate, diethyl fumarate and ethyl fumarate, maleic anhydride, N-phenylmaleimide, (meth) acrylic An acid etc. are mentioned.

Furthermore, resins other than those described above may be included. Other than the above, polyolefin-modified resins such as polyethylene and polypropylene, rubber modified with addition of diene rubbery polymers such as polybutadiene, styrene-butadiene copolymer, ethylene-propylene-nonconjugated diene three-dimensional copolymer Examples thereof include impact-resistant polystyrene resins, polycarbonate resins, polyester resins, polyamide resins, polyphenylene ethers, acrylonitrile-butadiene-styrene copolymers, and polymethyl methacrylate. The proportion of these other resins is preferably less than 50% by mass, more preferably 30% by mass or less, and still more preferably 10% by mass or less based on the total amount of the base resin.
The styrenic resin preferably has a weight average molecular weight of 100,000 to 1,000,000. When the weight average molecular weight is less than 100,000, the strength of the foamed molded product may be lowered. When larger than 1 million, foamability may fall and it may be inferior to lightness. A weight average molecular weight of 150,000 to 800,000 is more preferable, and 200,000 to 500,000 is more preferable.

  The content ratio of the styrene resin in the expanded particles is preferably 50% by mass or more. If it is less than 50% by mass, sufficient foamability may not be obtained. A more preferable content rate is 60 mass% or more, and a still more preferable content rate is 80 mass% or more.

(3) Carbon material Foamed particles contain a carbon material. The carbon material is not particularly limited as long as it does not hinder the characteristics of the present invention, but carbon materials such as carbon black, activated carbon, graphite, graphene, coke, carbon nanofiber, mesoporous carbon, glassy carbon, hard carbon, and soft carbon. Preferably, conductive carbon black such as acetylene black, ketjen black, carbon nanofiber, and carbon nanotube is used.

  Content of a carbon material is 0.5-25 mass parts with respect to 100 mass parts of styrene resin. When content is less than 0.5 mass part, heat insulation may not fully be improved. On the other hand, when the content exceeds 25 parts by mass, the foam film may be broken, so that the moldability may be reduced and the heat insulation may be inferior. The preferable carbon material content is 0.5 to 15 parts by mass, and the more preferable carbon material content is 0.5 to 10 parts by mass. Specific contents include 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.01, 2, 2.56, 3, 3.13, 4, 5, 5.26, 6, 7, 7.52, 7.69, 8, 9, 10, 11, 11.11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts by mass, etc. It is done.

The carbon material preferably has a volume resistivity of 1.0 × 10 ⁴ Ω · cm or less. When the volume resistivity is higher than 1.0 × 10 ⁴ Ω · cm, the heat insulation 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 more preferred volume resistivity is 2.0 × 10 ^3. The most preferable 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. Specific values of volume resistivity are 1.0 × 10 ³ , 2.0 × 10 ³ , 3.0 × 10 ³ , 4.0 × 10 ³ , 5.0 × 10 ³ , 6.0 × 10 ³ , 7.0 × 10 ³ , 8.0 × 10 ³ , 9.0 × 10 ³ , 1.0 × 10 ⁴ Ω · cm and the like.

  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 expanded particles and the foamed molded article with an organic solvent is melt-kneaded with a polyethylene resin or a polystyrene resin (carbon material: polyethylene resin or polystyrene resin = 1). : 4 (mass ratio)), and means a value obtained by measuring the surface of the kneaded plate-like molded body. Detailed volume resistivity measurement methods are described in the Examples.

In addition, even if it uses any of a polyethylene-type resin and 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.

  In addition, when measuring volume resistivity using a polystyrene-based resin, for the procedure of taking out the carbon material by removing the styrene-based resin in the master batch, expandable particles, expanded particles, and foamed molded product with an organic solvent, When the carbon material: polystyrene resin = 1: 4 (mass ratio), the removal of the styrene resin is stopped halfway, or the carbon material: polystyrene resin = 1: 4 (mass ratio). You may take the method of adding (dilution) resin. In the case of adopting a method of stopping the removal of the styrene resin halfway, in order to adjust the carbon material: polystyrene resin = 1: 4 (mass ratio), the masterbatch, expandable particles, expanded particles, carbon in the expanded molded body You may measure the amount of materials, and the amount of styrene resin. Although it does not specifically limit as a measuring method of the amount of carbon materials, For example, the method etc. which use a differential thermothermal weight simultaneous measuring apparatus are mentioned.

The carbon material may be contained in a form in which primary particles of the carbon material are dispersed in the styrene resin, or in the form of an agglomerate in which a plurality of primary particles of the carbon material are aggregated in the styrene resin. May be. Preferably, the primary particles of the carbon material are contained as agglomerates that are agglomerated in the styrene resin.
FIG. 2 shows an example of a carbon material in which aggregates observed using an electron microscope are formed. The primary particle of the carbon material means each of the substantially circular particles as observed in FIG. By agglomerate is meant a mass of primary particles that appears to overlap at least two substantially circular primary particles, as observed in FIG.

The primary particles preferably have an average primary particle size 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. Specific numerical ranges of the average primary particle diameter include 18 to 120 nm, 18 to 110 nm, 18 to 100 nm, 18 to 90 nm, 18 to 80 nm, 18 to 73 nm, 18 to 66 nm, 18 to 60 nm, 20 to 100 nm, 25 -80 nm, 32-66 nm, 20-125 nm, 25-125 nm, 32-125 nm, 40-125 nm, 50-125 nm, 60-125 nm, 66-125 nm, 73-125 nm, 80-125 nm and the like. Specific values of the average primary particle diameter include 18, 20, 25, 32, 40, 50, 60, 66, 73, 80, 90, 100, 110, 120, 125 nm, and the like.

The agglomerates preferably have (i) an average value of the longest diameter of 180 to 500 nm.
The longest diameter means the longest distance between any two points on the outer edge of the aggregate. For example, in FIG. 1, the diameter indicated by the solid line is defined as the longest diameter of the aggregate. . 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. Specific numerical ranges of the average value of the longest diameter are 180 to 450 nm, 180 to 400 nm, 180 to 370 nm, 180 to 300 nm, 180 to 240 nm, 200 to 450 nm, 220 to 400 nm, 240 to 370 nm, 200 to 500 nm, 220-500 nm, 240-500 nm, 300-500 nm, 370-500 nm, 400-500 nm etc. are mentioned. Specific examples of the average value of the longest diameter include 180, 200, 220, 230, 240, 250, 300, 350, 370, 400, 420, 450, 460, 470, 480, 490, and 500 nm.
The longest diameter of the aggregate is set so as to always overlap the aggregate. In other words, the longest diameter does not pass through the background (styrene resin). For example, in FIG. 2, the line indicated by the broken line has a portion overlapping the background, and thus cannot be set as the longest diameter.

  In addition, the agglomerates preferably have (ii) a ratio of “average value of longest diameter” to “average primary particle diameter” of 4.0 to 10.0. When the ratio is less than 4.0, the heat insulating property may not be improved. When the ratio is more than 10.0, bubbles may be broken during foaming and a good molded product may not be obtained. Specific numerical ranges of the above ratio are 4.0 to 9.0, 5.0 to 9.0, 5.0 to 8.9, 5.0 to 8.5, 5.0 to 8. 0, 5.0-7.0, 5.0-6.0, 5.2-8.9, 5.5-8.5, 6.0-8.0, 4.0-10.0, 5.0-10.0, 5.2-10.0, 5.5-10.0, 6.0-10.0 etc. are mentioned. The ratio of the average value of the longest diameter to the specific average primary particle diameter is 4.0, 4.5, 5.0, 5.2, 5.5, 6.0, 7.0, 8. 0, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, etc. are mentioned. Detailed measurement methods of the average value of the longest diameter and the average primary particle diameter are described in Examples.

The carbon material 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. For example, as a specific numerical range of the specific surface ^{area, 100~3000m 2 / g, 200~3000m 2} / g, 210~3000m 2 / g, 220~3000m 2 / g, 15~2500m 2 / g, 100~ ^{2500m 2 / g, 210~2500m 2 /} g, 10~2000m 2 / g, 60~2000m 2 / g, 210~2000m 2 / g, 10~1500m 2 / g, 70~1500m 2 / g, 200~1500m ² / g, 210-1500m < ² > / g, etc. are mentioned. 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. As specific surface area values, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 400, 500, 700, 1000, 1500, 2000, 2500, 3000 m ² / g and the like.

  In one embodiment, the carbon material is conductive carbon black (eg, acetylene black, ketjen black). Such conductive carbon black is preferable except for the volume resistivity, the average value of the longest diameter of the agglomerates, the average primary particle diameter, the (average value of the longest diameter of the agglomerates) / (average primary particle diameter) ratio and the specific surface area. Examples of physical property values include the following.

The mass ratio of the carbon material and the styrene resin is as follows: carbon material: styrene resin = 1: 2-1
: 1000 (mass ratio) is preferable. When the mass ratio of the styrene resin is less than 2,
When the bubble film is broken, the moldability may be lowered and the heat insulation may be inferior. If the mass ratio is greater than 1000, the heat insulation may not be sufficiently improved. A more preferable mass ratio is 1: 4 to 1: 2.
00, a more preferred mass ratio is 1: 9 to 1:99, and a most preferred mass ratio is 1: 9.
It is 13 to 1:39, and a very preferable mass ratio is 1:13 to 1:32.

The expanded particles preferably have a bulk density of 0.009 to 0.400 g / cm ³ . When the bulk density is larger than 0.400 g / cm ³ , the lightness of the foamed molded product may be lowered. When the bulk density is less than 0.009 g / cm ³ , the heat insulating performance and mechanical strength of the foamed molded product may be deteriorated. More preferred bulk density of 0.010~0.100g / cm ^3, even more preferred bulk density of 0.01-0.04 / cm ^3, more preferred bulk density 0.011～0.032G / cm ^3, and most preferred bulk density is 0.014~0.029g / cm ^3. Specific bulk density values are 0.009, 0.010, 0.011, 0.012, 0.0125, 0.013, 0.014, 0.015, 0.02, 0.03, It may be 0.033, 0.035, 0.04, 0.1, 0.2, 0.3, 0.4 g / cm ³ or the like.

(4) Method for Producing Expanded Particles The scope of the present invention includes the above-described method for producing expanded particles. The above expanded particles are obtained by, for example, obtaining styrenic resin expandable particles (hereinafter referred to as expandable particles) according to a method known to those skilled in the art, and heat-treating the obtained expandable particles under a specific temperature and pressure. Can be obtained by foaming (pre-foaming) according to a known method.

(Process for obtaining expandable particles)
Expandable particles can be obtained according to methods known to those skilled in the art. For example,
Impregnating the seed particles with a styrene monomer in a dispersion obtained by dispersing seed particles containing a styrene resin and a carbon material in an aqueous medium;
A step of polymerizing the styrenic monomer simultaneously with or after impregnation;
Impregnating a foaming agent simultaneously with or after polymerization;
It can obtain by the manufacturing method of the styrene resin expandable particle containing.

The aqueous medium is not particularly limited as long as it is a liquid that can dissolve a water-soluble substance at room temperature, and examples thereof include water, lower alcohols having 1 to 4 carbon atoms, and mixtures thereof. Water is particularly preferable. The amount of the aqueous medium used can be appropriately set by those skilled in the art.
Resins other than styrenic resins may be contained in the resin obtained by polymerization. The kind, physical property, and content of such a resin are as described above.

  It does not specifically limit as a foaming agent, All can use a well-known thing. 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, 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 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.

The content of the foaming agent is preferably in the range of 2 to 12% by mass. If it is less than 2% by mass, a foamed molded article having a desired density may not be obtained from the expandable particles. In addition, since the effect of increasing the secondary foaming power at the time of in-mold foam molding is reduced, the appearance of the foam molded article may not be good. When the amount is more than 12% by mass, the time required for the cooling step in the production process of the foamed molded product becomes long, and the productivity may decrease. A more preferable content is 3 to 10% by mass, a still more preferable content is 4 to 9% by mass, and a most preferable content is 5 to 8% by mass.
A foaming aid may be used in combination with a foaming agent. Examples of the foaming aid include isobutyl adipate, 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, foam control agents, fillers, colorants, weathering agents, anti-aging agents, lubricants, antifogging agents, and fragrances. Etc.
Plasticizers include aromatic hydrocarbons such as 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 diacetomonolaurate. Glycerin fatty acid esters such as glycerin fatty acid esters, 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. Examples thereof include brominated flame retardants such as (2,3-dibromopropyl ether) and phosphoric flame retardants such as phosphate ester compounds and phosphazene compounds.
Examples of phosphate ester compounds include phosphate ester compounds such as trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate.
Examples of the phosphazene compound include hexaphenoxycyclotriphosphazene, octaphenoxycyclotetraphosphazene, decaffeoxycyclopentaphosphazene, dodecaffenoxycyclohexaphosphazene, tetradecaffenoxycycloheptaphosphazene, hexadecaffenoxycyclooctaphosphazene, and other cyclic phenoxyphosphazene compounds. Linear di (bisphenoxy) phosphazene, linear tri (bisphenoxy) phosphazene, linear tetra (bisphenoxy) phosphazene, linear penta (bisphenoxy) phosphazene, linear hexa (bisphenoxy) phosphazene, straight Examples include chain phenoxyphosphazene compounds such as chain hepta (bisphenoxy) phosphazene.

Examples of the flame retardant aid include organic peroxides such as 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, dicumyl peroxide, and cumene hydroperoxide. .
Examples of the antistatic agent include polyoxyethylene alkylphenol ether, stearic acid monoglyceride, polyethylene glycol and the like.
Examples of the spreading agent include polybutene, polyethylene glycol, glycerin, and silicone oil.

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 lubricants include metal soaps such as zinc stearate and magnesium stearate, bisamide compounds such as ethylenebisstearic acid amide and methylenebisstearic acid amide, stearic acid amides, amide compounds such as 12-hydroxystearic acid amide, stearic acid triglycerides, Examples include fatty acid glycerides such as stearic acid monoglyceride and hydroxystearic acid triglyceride, polyethylene wax, liquid paraffin, and white oil.
Examples of other additives include phenolic antioxidants, sulfur-based antioxidants, antioxidants such as phosphorus-based antioxidants, stabilizers such as hindered amines, and ultraviolet absorbers.

  This embodiment is an embodiment in which expandable particles are produced using a suspension polymerization method, which is one of the typical methods for producing expandable particles in the art. Hereinafter, the suspension polymerization method will be described in more detail. However, the present embodiment is not limited to the conditions described below.

1. Suspension polymerization method In the suspension polymerization method, a polymerization initiator is dissolved in a styrene monomer, and together with water in which the suspending agent is dispersed, the temperature is increased in a reaction tank, polymerized, and then cooled to produce styrene resin foamable particles. Is the way to get. 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). Further, small polystyrene particles (seed particles) are put into a reaction vessel containing water in which a suspending agent is dispersed, and after the temperature is raised, styrene monomer in which a polymerization initiator is dissolved is continuously added to the reaction vessel. The method of supplying and polymerizing and growing to the target particle size is called a seed polymerization method. In the seed polymerization method, the foaming agent is added during the polymerization and / or after the completion of the polymerization. Styrenic resin expandable particles 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. According to the seed polymerization method, polystyrene particles (master batch) containing a carbon material at a high concentration (for example, 20% by mass) can be used as seed particles, and there is an advantage that polymerization inhibition hardly occurs.

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.
(A) Seed polymerization method of suspension polymerization method As this method, seed particles containing a carbon material and a styrene resin are absorbed into a styrene monomer and polymerized to obtain styrene resin particles, and polymerization is performed. A method of obtaining expandable particles by injecting a foaming agent in the middle of and / or after completion of the polymerization may be mentioned. In this method, it is easy to obtain expandable particles containing a large amount of carbon material at the center.

(I) Seed particles The seed particles produced by a known method can be used. For example, by melting and kneading a carbon material and a styrene resin with an extruder, the seed particles are extruded into strands, and the strands are cut. An extrusion method for obtaining seed particles 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.
Further, the weight average molecular weight of the seed particles is not particularly limited, but is preferably 100,000 to 500,000, and more preferably 150,000 to 400,000.

  The addition amount of the carbon material is 0.5 to 25 parts by mass with respect to a total of 100 parts by mass of the addition amount of the styrene resin and the styrene monomer in the seed particles. That is, seed particles are added so that the amount of carbon material added is 0.5 to 25 parts by mass. When the addition amount is less than 0.5 parts by mass, the heat insulating property may not be sufficiently improved. On the other hand, when the addition amount exceeds 25 parts by mass, the foam film may be broken, so that the moldability may be reduced and the heat insulation may be inferior. A preferable addition amount of the carbon material is 0.5 to 15 parts by mass, and a more preferable addition amount of the carbon material is 0.5 to 10 parts by mass. Specific addition amounts include 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.01, 2, 2.56, 3, 3.13, 4, 5, 5.26, 6, 7, 7.52, 7.69, 8, 9, 10, 11, 11.11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts by mass, etc. It is done. In addition, the addition amount can be adjusted so as to have a value approximately the same as the content described for the expandable particles.

(Ii) Polymerization step Each monomer is absorbed by seed particles by supplying a monomer mixture into a dispersion obtained by dispersing seed particles in an aqueous medium, and then each monomer is polymerized. Styrenic resin particles can be obtained.
It is preferable that the addition amount of a styrene-type monomer is 50 mass parts or more with respect to 100 mass parts in total of the addition amount of a seed particle and a styrene-type monomer. When the amount is less than 50 parts by mass, sufficient foamability may not be obtained. A more preferable content rate is 60 mass parts or more, and a still more preferable content rate is 80 mass parts or more. In addition, the addition amount can be adjusted so as to have a value approximately the same as the content described for the expandable particles.
Examples of the aqueous medium include water and a mixed medium of water and a water-soluble solvent (for example, alcohol).

  Each monomer to be used may contain a polymerization initiator. The polymerization initiator is not particularly limited as long as it is conventionally used for monomer polymerization. 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).

(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 is preferably in the range of 2 to 12 parts by mass with respect to 100 parts by mass of the styrene resin obtained by polymerization. When the amount is less than 2 parts by mass, a foamed molded article having a desired density may not be obtained from the expandable particles. In addition, since the effect of increasing the secondary foaming power at the time of in-mold foam molding is reduced, the appearance of the foam molded article may not be good. When the amount is more than 12 parts by mass, the time required for the cooling step in the production process of the foamed molded product may become long and the productivity may decrease. A more preferable content is 3 to 10 parts by mass, a still more preferable content is 4 to 9 parts by mass, and a most preferable content is 5 to 8 parts by mass. In addition, the quantity of the foaming agent to be impregnated can be adjusted so as to have a value almost the same as the content described for the foamable 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.

In another embodiment, the expandable particles are
A step of melt-kneading the carbon material and the styrene resin;
Injecting a foaming agent into the molten resin obtained in the melt-kneading step;
The molten resin obtained in the blowing agent injecting step can be obtained by a method for producing styrene resin expandable particles, which includes a step of extruding, cutting, and then solidifying the molten resin obtained in a liquid.

  This embodiment is an embodiment in which expandable particles are produced using a melt extrusion method which is one of the typical methods for producing expandable particles in the technical field. Hereinafter, although the melt extrusion method will be described in more detail, the present embodiment is not limited to the conditions described below.

2. Melt extrusion method In the melt extrusion method, polystyrene pellets are supplied to a resin supply device, a foaming agent is press-fitted and kneaded into the polystyrene resin melted in the resin supply device, and the molten resin containing the foaming agent is added to the tip of the resin supply device. It extrudes from the small hole of the die | dye attached to, and it cools after that, and obtains a styrene-type resin foamable particle. A method of directly extruding from a small hole of a die into a cooling liquid, 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. The strand is extruded from the small holes of the die into air in the form of strands, guided into the cooling water tank before the strands are foamed, and after the strands are cooled in the cooling water tank, they are cut into columnar particles. This is called the method (cold cut method). Styrenic resin foamable particles can be produced by any of the hot cut method and the strand cut method (cold cut method). In addition, any method has an advantage that an arbitrary amount of carbon material can be easily contained in the particles. Further, the carbon material can be uniformly contained in the expandable particles. 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, the hot-cut method of the melt extrusion method will be described in more detail, but the present embodiment is not limited to the conditions described below.
(B) Hot cut method of melt extrusion method As this method, a foaming agent is press-fitted and kneaded into a polystyrene resin melted in a resin supply device, and a molten resin containing the foaming agent is attached to the tip of the resin supply device. The extrudate extruded into the cooling liquid directly from the small holes of the die and cut into the cooling liquid is cut with a rotating blade in the cooling liquid, and the extrudate is cooled and solidified by contact with the liquid to foam. This is a method for obtaining a conductive particle.
In this method, for example, the following manufacturing apparatus can be used. That is, an extruder as a resin supply device, 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 a blowing agent supply port for the molten resin in the extruder A high-pressure pump for press-fitting the foaming agent through, a cutting chamber in which cooling water is provided in contact with the resin discharge surface provided with a small hole in the die, and the cooling water is circulated and supplied into the chamber, and a small hole in the die A cutter (high-speed rotating blade) that is rotatably provided in the cutting chamber so as to cut the resin extruded from the cutting chamber, and the foaming particles carried along with the flow of cooling water from the cutting chamber are separated from the cooling water. A dehydration dryer with a solid-liquid separation function that obtains foamable particles by dehydration and drying, a water tank for storing cooling water separated by the dehydration dryer with a solid-liquid separation function, and a cooling chamber for cooling water in this water tank A high pressure pump to send, include manufacturing apparatus and a storage container for storing the dewatered dried effervescent grains at the solid-liquid separation function dehydrating dryer.

  An example of a procedure for producing expandable particles using the production apparatus will be described. First, raw polystyrene resin and carbon material are put into an extruder from a raw material supply hopper. 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. For example, when multiple lots are used, the supply amount for each lot may be reduced. A plurality of adjusted raw material supply hoppers may be charged and mixed in an extruder. Also, when using a combination of recycled materials from multiple lots, mix the raw materials from multiple lots in advance and remove foreign matter using appropriate sorting means such as magnetic sorting, sieving, specific gravity sorting, and air blowing sorting. It is preferable to keep it. The carbon material may be fed into the extruder as a master batch prepared by melt-mixing with a polystyrene resin in advance.

  The addition amount of the carbon material is 0.5 to 25 parts by mass with respect to 100 parts by mass of the addition amount of the styrene resin. When the addition amount is less than 0.5 parts by mass, the heat insulating property may not be sufficiently improved. On the other hand, when the addition amount exceeds 25 parts by mass, the foam film may be broken, so that the moldability may be reduced and the heat insulation may be inferior. A preferable addition amount of the carbon material is 0.5 to 15 parts by mass, and a more preferable addition amount of the carbon material is 0.5 to 10 parts by mass. Specific addition amounts include 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.01, 2, 2.56, 3, 3.13, 4, 5, 5.26, 6, 7, 7.52, 7.69, 8, 9, 10, 11, 11.11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts by mass, etc. It is done. In addition, the addition amount can be adjusted so as to have a value approximately the same as the content described for the expandable particles.

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

  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 is preferably in the range of 2 to 12 parts by mass with respect to 100 parts by mass of the molten resin. When the amount is less than 2 parts by mass, a foamed molded article having a desired density may not be obtained from the expandable particles. In addition, since the effect of increasing the secondary foaming power at the time of in-mold foam molding is reduced, the appearance of the foam molded article may not be good. When the amount is more than 12 parts by mass, the time required for the cooling step in the production process of the foamed molded product may become long and the productivity may decrease. A more preferable content is 3 to 10 parts by mass, a still more preferable content is 4 to 9 parts by mass, and a most preferable content is 5 to 8 parts by mass. In addition, the quantity of the foaming agent to inject | pour can be adjusted so that it may become a value substantially comparable as content described about the expandable particle. Further, as described above, a foaming aid may be used in combination with a foaming agent. The type of foaming aid is as described above, and the amount of foaming aid to be added can be appropriately set by those skilled in the art.

A resin discharge surface with a small hole in the die is placed in a cutting chamber in which cooling water is circulated and supplied into the chamber, and a cutter is provided in the cutting chamber so that the resin extruded from the small hole in the die can be cut. Is rotatably provided. When the melted product with foaming agent added is extruded through a small hole in the die attached to the tip of the extruder, the melt is cut into granules and simultaneously cooled in contact with cooling water to solidify while suppressing foaming. It becomes an expandable particle.
The formed expandable particles are transferred from the cutting chamber along with the flow of cooling water to the dehydrating dryer 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 a storage container.
In addition, when adding a flame retardant, the addition time is not particularly limited, but it is preferably added to the extruder together with the raw material.

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 of producing a styrene resin foamable particle by impregnating an agent, or a method of producing a styrene resin foamable particle by a seed polymerization method of a suspension polymerization method using this particle as a seed particle. Also by these methods, styrene resin expandable particles can be produced. In addition, any method has an advantage that an arbitrary amount of carbon material can be easily contained in the particles by the melt extrusion method. As a preferable production method, there is a method in which particles containing no foaming agent are obtained by a melt extrusion method, and then styrene resin foamable particles are produced by seed polymerization using the particles as seed particles. According to this method, polystyrene particles (masterbatch) containing a carbon material at a high concentration (for example, 20% by mass) can be used as seed particles, and there is an advantage that polymerization inhibition is unlikely to occur. There is an advantage that particles can be obtained.

(Heat treatment process)
The heat treatment can be performed by placing the expandable particles obtained as described above under a specific temperature and pressure in an aqueous medium.
The heat treatment temperature is 40 to 80 ° C. In any case where the heat treatment temperature is lower than 40 ° C. or higher than 80 ° C., it is difficult to obtain expanded particles that give a foamed molded article having sufficient heat insulation. The heat treatment temperature is preferably 45 to 75 ° C, more preferably 45 to 70 ° C.

The pressure in the heat treatment is preferably 0.5 MPa or more, more preferably 0.7 MPa or more, and further preferably 1.0 MPa or more.
An aqueous medium is as above-mentioned in the acquisition process of an expandable particle.

(Pre-foaming process)
Pre-foaming can be performed according to methods known to those skilled in the art. For example, it is performed by foaming the heat-treated particles to a desired bulk density using water vapor or the like.
The foamed particles obtained through the preliminary foaming step may be aged, for example, at normal pressure before the subsequent foam molding step. 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.

(Styrenic resin foam molding)
A styrene resin foam molded body (hereinafter referred to as a foam molded body) is composed of a plurality of styrene resin foam particles fused together and containing a styrene resin and a carbon material, and has large bubbles and small bubbles. This foam-molded product can be obtained by foam-molding the foamed particles.
The styrenic resin and the carbon material constituting the foamed molded product and the volume resistivity thereof are as described above for the foamed particles. Further, the large bubbles, the small bubbles, and the occupancy ratio of the small bubbles to the large bubbles are as described above for the expanded particles.

Preferably, the foamed molded product is obtained by the following formula in the surface color difference measurement based on JIS Z8729-2004 “Color Display Method—L ^* a ^* b ^* Color System”:
31 ≦ ΔE ′ = L ^* + | a ^* | + | b ^* | ≦ 50
(Where ΔE ′ is blackness, L ^* is lightness, a ^* and b ^* are color coordinates)
Satisfies the relational expression indicated by. More preferable ΔE ′ is 32 ≦ ΔE ′ ≦ 45, and still more preferable ΔE ′ is 32 ≦ ΔE ′ ≦ 35. In the case of ΔE ′ <31, the heat insulating property may be lowered. On the other hand, in the case of ΔE ′> 50, the heat insulating property may be lowered. (1) In order to reduce ΔE ′, depending on whether a carbon material closer to black is selected, the content of the carbon material in the foam molded body is increased, or the density of the foam molded body is increased. Can be achieved. (2) In order to increase ΔE ′, depending on whether a carbon material closer to gray is selected, the content of the carbon material in the foam molded body is reduced, or the density of the foam molded body is reduced. Can be achieved. Specific blackness values include 31, 32, 33, 34, 35, 38, 40, 43, 44, 45, 46, 47, 48, 49, 50, and the like. Detailed blackness measurement methods are described in the Examples.

  The foamed molded product may further contain a flame retardant. As the flame retardant, the same ones as described above can be used, but tetrabromocyclooctane or tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) is particularly preferable. Content of a flame retardant is 0.5-10 mass parts with respect to 100 mass parts of foaming moldings, Preferably it is 2-8 mass parts. Specific values of the flame retardant content include 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by mass, and the like.

  Preferably, the foam-molded article is a heat insulating material for a living space in which the total content of aromatic organic compounds composed of a styrene monomer, ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, toluene, and benzene is less than 2000 ppm. 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. In the case of foamed particles, foamed molded products, and heat insulating materials for living spaces obtained from the same styrenic resin foamable particles, the total content of the aromatic organic compounds is a comparable value. Styrenic resin expandable particles having a total content of the aromatic organic compound of less than 2000 ppm are suitable for producing a heat insulating material for living spaces. In addition, a melt extrusion method is preferable as a production method for obtaining styrene resin expandable particles having a small total content of the aromatic organic compound. Detailed methods for measuring the total content of aromatic organic compounds are described in the Examples.

The foamed molded body preferably has a density of 0.010 to 0.400 g / cm ³ . If the density is greater than 0.400 g / cm ³ , the lightness may be reduced. When the density is less than 0.010 g / cm ³ , the heat insulating performance and mechanical strength may be lowered. A more preferable density is 0.011 to 0.100 g / cm ³ , an even more preferable density is 0.012 to 0.04 g / cm ³ , and a still more preferable density is 0.0125 to 0.033 g / cm ³ . The most preferable density is 0.015 to 0.030 g / cm ³ . Specific bulk density values are 0.009, 0.010, 0.011, 0.012, 0.0125, 0.013, 0.014, 0.015, 0.02, 0.03, It may be 0.033, 0.035, 0.04, 0.1, 0.2, 0.3, 0.4 g / cm ³ or the like.

  The foamed molded article preferably exhibits a thermal conductivity of 0.034 W / mk or less. When the thermal conductivity exceeds 0.034 W / mk, it may not be possible to provide a foamed molded article having sufficient heat insulation. More preferable thermal conductivity is 0.033 W / mk or less, and still more preferable thermal conductivity is 0.032 W / mk or less. Specific values of thermal conductivity are 0.034, 0.0339, 0.0338, 0.0337, 0.0336, 0.0335, 0.0334, 0.0333, 0.0332, 0.0331. 0.033, 0.0329, 0.0328, 0.0327, 0.0326, 0.0325, 0.0324, 0.0323, 0.0322, 0.0321, 0.032, 0.0319, 0 0.0318, 0.0317, 0.0316, 0.0315, 0.0314, 0.0313, 0.0312, 0.0311, 0.031, 0.0309, 0.0308, 0.0307, 0.0306 , 0.0305, 0.0304, 0.0303, 0.0302, 0.0301, 0.030, and the like.

The foamed molded product preferably exhibits a water absorption of less than 0.5 g / 100 cm ² . When the amount of water absorption exceeds 0.5 g / 100 cm ² , the heat insulating property may be lowered. More preferable water absorption is less than 0.4 g / 100 cm ² , still more preferable water absorption is less than 0.3 g / 100 cm ² , and even more preferable water absorption is less than 0.2 g / 100 cm ² . Specific water absorption values include 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.05, etc. Is mentioned.

Preferably, the foamed molded article exhibits a ratio A / B of 0.8 to 2.0 in absorbance A at a wave number of 1000 cm ⁻¹ and absorbance B at a wave number of 500 cm ⁻¹ obtained by transmission infrared analysis. When the absorbance ratio A / B <0.8 or when the absorbance ratio A / B> 2.0, sufficient heat insulation may not be obtained. (1) The absorbance ratio A / B can be reduced by increasing the amount of carbon material added. (2) Increasing the absorbance ratio A / B can be achieved by increasing the amount of carbon material added, reducing the bubble diameter, or the like. A more preferred absorbance ratio A / B is 0.81 to 1.80, and a further preferred absorbance ratio A / B is 0.82 to 1.75. Specific values of the absorbance ratio A / B are 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.9, 0.95, 1.0, 1 .1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75, 1.76, 1.77, 1.78, 1.79, 1.8 1.85, 1.9, 1.95, 2.0 and the like.

Absorbance A means the absorbance at a wave number of 1000 cm ⁻¹ obtained by transmission infrared analysis. The preferred absorbance A is 0.8 or more. When the absorbance A is less than 0.8, the heat insulation is poor. More preferable absorbance A is 0.95 or more. Specific values of absorbance A include 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 and the like.

Further, the absorbance B means the absorbance at a wave number of 500 cm ⁻¹ obtained by transmission infrared analysis. The preferred absorbance B is 0.5 or more. When the absorbance B is less than 0.5, the heat insulating property is lowered. More preferable absorbance B is 0.55 or more. Specific values of absorbance B include 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.65, 0.7 and the like.
Detailed methods for measuring absorbances A and B are described in the Examples.

For example, the foamed molded body is filled with foamed particles in a closed mold having a large number of small holes, heated and foamed with a heat medium (for example, pressurized water vapor) to fill the voids between the foamed particles, and It can manufacture by fusing together and integrating. At that time, the density of the foamed molded product can be adjusted, for example, by adjusting the filling amount of the pre-expanded 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 foamed molded product can be used for various applications that require heat insulation. For example, wall insulation, floor insulation, roof insulation, automotive insulation, warm water tank insulation, piping insulation, solar system insulation, water heater insulation, food and industrial products, etc. It can be used for containers, packing materials for fish and agricultural products, embankment materials, tatami core materials, etc. The foamed molded product can take a shape corresponding to the intended use. 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.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.
<Volume resistivity of carbon material measured using polyethylene resin>
Volume resistivity here is the raw material carbon material, or when the raw material carbon material is added to the masterbatch, expandable particles, expanded particles, and foamed molded product, the masterbatch, expandable particles, The carbon material taken out by removing the styrene resin in the foamed particles and the foamed molded article with toluene as an organic solvent was melt kneaded with the polyethylene resin (carbon material: polyethylene resin = 1: 4 (mass ratio). )), The value obtained by measuring the surface of the kneaded product.
Specifically, a polyethylene resin and a carbon material that are sufficiently melt-kneaded using an extruder and formed into a film shape are measured by the method described in JIS K6911: 1995 “General Test Method for Thermosetting Plastics”. To do. That is, using a test apparatus (advantest digital ultra-high resistance / microammeter R8340 and resiliency chamber R12702A), an electrode is crimped to a sample sample with a load of about 30 N, and the resistance after charging at 500 V for 1 minute. The value is measured and calculated by the following formula. The sample sample has a width of 100 × length of 100 × original thickness (10 or less) mm. After conditioning for 24 hours or more at a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5%, the test environment is measured at a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5%. The number of test pieces is five, and the average value is the volume resistivity (Ω · cm) of the carbon material.
ρv = (πd ² / 4t) × Rv
ρv: Volume resistivity (Ω · cm)
d: outer diameter of inner circle of surface electrode (cm)
t: thickness of test specimen (cm)
Rv: Volume resistance (Ω)

<Volume resistivity of carbon material measured using polystyrene resin>
Volume resistivity here is the raw material carbon material, or when the raw material carbon material is added to the masterbatch, expandable particles, expanded particles, and foamed molded product, the masterbatch, expandable particles, The carbon material taken out by removing the styrene resin in the foamed particles and the foamed molded article with toluene as an organic solvent was melt kneaded with the polystyrene resin (carbon material: polystyrene resin = 1: 4 (mass ratio). )), The value obtained by measuring the surface of the kneaded product.
Specifically, a resistivity test using a four-probe method of conductive plastic is performed on a plate-like molded body of a kneaded product of carbon material and polystyrene resin (carbon material: polystyrene resin = 1: 4 (mass ratio)). Measurement is performed in accordance with the method (JIS K7194). The test apparatus uses a low resistivity meter Lorester GP MCP-T600 manufactured by Mitsubishi Chemical Corporation, and the sample sample has a width of 80 × length of 50 × original thickness (20 or less) mm. The sample sample is conditioned at a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5% for 24 hours or more, and then measured as a test environment at a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5%. The volume resistivity is calculated from the following equation by measuring the resistance values at five measurement positions according to JIS K 7194 on the surface of the sample. The average value is defined as the volume resistivity (Ω · cm) of the carbon material.
ρv = V / I × RCF × t
ρv: Volume resistivity (Ω · cm)
V / I: Resistance (Ω)
RCF: Correction coefficient depending on measurement position and sample thickness t: Test piece thickness (cm)

<Weight average molecular weight>
A weight average molecular weight means the polystyrene (PS) conversion average molecular weight measured using gel permeation chromatography (GPC). Specifically, 3 mg of the sample was allowed to stand and dissolved in 10 mL of tetrahydrofuran (THF) for 72 hours (complete dissolution), and the resulting solution was subjected to a non-aqueous 0.45 μm chromatodisc (13N) manufactured by Kurashiki Boseki Co., Ltd. Filter and measure. 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.

(Measurement condition)
Equipment used: High-speed GPC equipment: HLC-8320GPC EcoSEC system manufactured by Tosoh Corporation (with built-in RI detector)
Guard column: Tosoh TSKguardcolumn 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: 0.175 mL / min on the sample side, 0.175 mL / min on the reference side 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 a standard polystyrene sample for a calibration curve, the weight average molecular weight of the trade name “TSK standard POLYSTYRENE” manufactured by Tosoh Corporation is 5,480,000, 3,840,000, 355,000, 102,000, 37,900, 9, Standard polystyrene samples having a weight average molecular weight of 1,3030,000 are 100, 2,630, and 500 and a trade name “Shodex STANDARD” manufactured by Showa Denko KK.

  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 is weighed 5 mg and then dissolved in 20 mL of tetrahydrofuran, Group B is also weighed 5 to 10 mg each and then dissolved in 50 mL of tetrahydrofuran, and Group C is also weighed 1 to 5 mg each 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. From the retention time obtained after measurement, a calibration curve (tertiary equation) was transferred to the HLC-8320GPC dedicated data analysis program GPC workstation (EcoSEC-WS). The measurement curve is obtained by using the calibration curve.

<Measurement method of average primary particle size>
Using a cutter knife, the center of the expandable particles is cut out, and the skin portion of the expanded particles and the expanded molded body is cut out as a measurement sample. After the cut sample is fixed to the cryosample table with an adhesive, it is ultrathin using an ultramicrotome (LEICA ULTRACUT UCT manufactured by Leica Microsystems) and a frozen section preparation system (LEICA EM FCS manufactured by Leica Microsystems). A section (thickness 90 nm) is prepared. Next, using a transmission electron microscope (H-7600, manufactured by Hitachi High-Technologies Corporation), an ultrathin section is photographed (photographing magnification: 50,000 times). At least 200 carbon materials are photographed per sample, the diameter of each particle is measured, and the average value thereof is calculated. In addition, it is desirable to measure the part which can be recognized clearly as a primary particle, without an outer edge missing.

<Measurement method of amount of carbon material in resin>
The amount of carbon material in the resin is measured using a differential thermothermal gravimetric simultaneous measurement apparatus TG / DTA6200 (manufactured by SII Nano Technology). For example, in the case of foamable particles, foamed particles, foamed molded products, etc. containing a foaming agent or an organic solvent in the resin, the foaming agent in the resin can be left in a constant temperature bath at 120 ° C. for 2 hours. Samples from which organic solvents have been removed are used as measurement samples. About 15 mg of the sample is filled so that there is no gap at the bottom of the platinum measurement container, and the measurement is performed using alumina as a reference material. As temperature conditions, the temperature is raised from 30 ° C. to 520 ° C. at a rate of 10 ° C./min and a nitrogen gas flow rate of 230 mL / min, and then raised from 520 ° C. to 800 ° C. at a rate of 10 ° C./min and an Air flow rate of 160 mL / min. A TG curve (vertical axis: TG (%), horizontal axis: temperature (° C)) is obtained, and based on this, the weight loss of the sample when the temperature is raised from 520 ° C to 800 ° C is calculated, and the carbon material amount w (mass%) ).
At this time, the mass ratio between the carbon material and the styrene resin has the following relationship.
Carbon material: Styrenic resin = 1: (100 / w-1)
w: The value of mass% of the carbon material obtained from the measurement result In addition, if the foamed particles, the foamed molded product, and the heat insulating material for living space obtained from the same styrenic resin foamable particles, the carbon material and the styrenic resin The mass ratio is a similar value.

<Bulk density of expanded particles>
The bulk density of the expanded particles is measured according to JIS K6911: 1995 “General Test Method for Thermosetting Plastics”. Specifically, first, Wg is collected using the expanded particles as a measurement sample, and the measurement sample is naturally dropped into a measuring cylinder. The volume Vcm ³ of the measurement sample dropped into the graduated cylinder is measured using an apparent density measuring instrument based on JIS K6911. By substituting Wg and Vcm ³ into the following formula, the bulk density of the expanded particles is calculated.
Bulk density of expanded particles (g / cm ³ ) = mass of measurement sample (W) / volume of measurement sample (V)

<Density of foam molding>
The mass (a) and volume (b) of a test piece (example 75 × 300 × 30 mm) cut out from a foamed molded product (after being molded and dried at 40 ° C. for 20 hours or more) each have three or more significant figures. Then, the density (g / cm ³ ) of the foamed molded product is obtained by the formula (a) / (b).

<Bubble diameter of large bubbles or small bubbles>
The cell diameter of the cut surface of the expanded particle or the expanded molded product is measured in the following manner. First, the center part of the expanded particles or the expanded molded body is cut. Then, the cut surface is magnified 50 times using a scanning electron microscope (JSM-6360LV manufactured by NEC Corporation) and photographed to obtain an enlarged photograph. Next, the bubble to be measured is identified from the bubbles that appear on the enlarged photograph, the major diameter distance and the minor diameter distance of the identified bubbles are measured, and the bubble diameter distance is calculated from the average value thereof. Is the bubble diameter of the specified bubble divided by the magnification of the photograph.

<Occupancy rate of bubbles>
The ratio of the total area of the bubbles to be measured with respect to the cross-sectional area (the occupancy ratio of the bubbles) on the cut surface of the expanded particle or the expanded molded article is measured in the following manner. In the bubbles appearing on the enlarged photograph, the total area of the bubbles to be measured painted black, that is, the total area occupied by the bubbles to be measured is obtained. Here, the total area filled in black can be calculated using, for example, a measuring instrument commercially available from Tamaya Measurement System under the trade name “PLANIX5000”.
The ratio of the total area of small bubbles having a bubble diameter of 0.15 mm or less to the cross-sectional area (occupation ratio of small bubbles) is calculated by the following formula.
(Ratio of the total area of small bubbles to the cross-sectional area [%])
= 100 × total area of small bubbles / cross-sectional area Similarly, the ratio of the total area of large bubbles having a bubble diameter of 0.2 to 1 mm to the cross-sectional area (occupation ratio of large bubbles) is calculated by the following equation.
(Ratio of the total area of large bubbles to the cross-sectional area [%])
= 100 x total area of large bubbles / cross-sectional area

<Thermal conductivity>
A test piece having a rectangular parallelepiped shape having a length of 200 mm, a width of 200 mm, and a thickness of 30 mm is cut out from the foamed molded body. Next, the cut out test piece is allowed to stand for 72 hours in a constant temperature bath at 60 ° C. to remove the foaming agent contained in the foamed molded product. Thereafter, curing is performed for 24 hours or more at a temperature of 23 ° C. ± 1 ° C. and a humidity of 50 ± 10% to obtain a test piece for measuring thermal conductivity. The thermal conductivity (W / m · K) of the test specimen for measurement is measured at a measurement temperature of 23 ° C. by a flat plate heat flow meter method according to JIS A1412-2 (1999 “Foamed plastic insulation material”). The rate is an index of heat insulation, and the heat insulation is evaluated according to the following criteria from the obtained value of thermal conductivity (W / m · K).
0.0310 (W / m · K) or less: better heat insulation (A)
0.0310 and 0.0320 or less: better heat insulation (B)
More than 0.0320 and 0.0340 or less: excellent heat insulation (C)
Exceeds 0.0340 (W / m · K): poor heat insulation (D)
In the present invention, the value of the thermal conductivity of the foamed molded product is a value after removing the foaming agent contained in the foamed molded product. When measured without removing the foaming agent in the foamed molded product, the thermal conductivity of the foaming agent such as butane and pentane is lower than the thermal conductivity of air, so the value of the thermal conductivity of the foamed molded product is , About 0.002 (W / m · K).

<Specific surface area>
The specific surface area (m ² / g) of the carbon material is measured according to ASTM D-6556.

<Longest diameter of agglomerates of carbon material in foamable particles, foamed particles and foamed molded product>
Using a cutter knife, the expandable particles are cut out at the center of the particles, and the expanded particles and the expanded molded body are cut out of the skin portion to be used as a measurement sample. After the cut sample is fixed to the cryosample table with an adhesive, it is ultrathin using an ultramicrotome (LEICA ULTRACUT UCT manufactured by Leica Microsystems) and a frozen section preparation system (LEICA EM FCS manufactured by Leica Microsystems). A section (thickness 90 nm) is prepared. Subsequently, using a transmission electron microscope (H-7600, manufactured by Hitachi High-Technologies Corporation), an ultrathin section is photographed (imaging magnification: 10,000 times). Photograph at least 200 independent separate aggregates per sample. In the photographed image, the longest diameter of the distance between any two points on the outer edge of the aggregate that the primary particles of the carbon material appear to overlap was taken as the longest diameter of the aggregate, and the average value thereof was calculated. The longest diameter connecting the two points is set so as to always overlap the primary particles on the photograph. That is, the longest diameter does not pass through the background of the photograph.

<Blackness of foam molding>
The blackness ΔE ′ of the foamed molded product is evaluated by color difference measurement based on JIS Z8729-2004 “Color Display Method—L ^* a ^* b ^* Color System”.
For the measurement, a color difference meter (manufactured by Konica Minolta, model: CR-400) and a standard white plate calibration plate (Y: 94.3, x: 0.3144, y: 0.3208) are used for standardization.
Specifically, from any 10 points on the vertical and horizontal surfaces of the foamed molded product, the measurement area was measured as φ8 mm, and the average value was calculated from the lightness L ^* value, color coordinate a ^* value, and b ^* value. ΔE ′ is calculated as the degree.
ΔE ′ = L ^* + | a ^* | + | b ^* |
From the obtained ΔE ′, the blackness is evaluated according to the following criteria.
31 ≦ ΔE ′ ≦ 50: Good (◯)
ΔE ′ <31 and 50 <ΔE ′: Defect (×)

<Measurement method of absorbance>
A sample having a thickness of 1.0 mm ± 0.1 mm is obtained from an arbitrary portion of the obtained foamed molded article. Next, the absorbance of the transmitted infrared of the sample is measured by the following method.
・ Fourier transform infrared spectroscopic analyzer NICOLET iS5 (manufactured by Thermo Fisher Scientific)
Measurement method: Transmission method Measurement wave number region: 4000 cm ^{−1 to} 400 cm ⁻¹
-Wave number dependence of measurement depth: No correction-Detector: DTGSKBr
・ Resolution: 4cm ^-1
・ Number of integration: 16 times (same for background measurement)

<Measurement method of water absorption>
The amount of water absorption of the foamed molded product was measured according to JIS A9511: 2006R foamed plastic insulation material measuring method B. Three test pieces having a 100 × 100 × 25 mm full-cut surface were immersed in fresh water for 10 seconds, then immersed in ethanol for 10 seconds, and further allowed to stand at room temperature (23 ° C.) for 60 minutes. The reference mass (m0) And Next, after immersing in fresh water again and allowing it to absorb water for 24 hours, the mass (m1) is measured by the same method as the reference mass measurement.
About three test pieces, W is calculated with the following formula | equation, respectively, and let the average value be water absorption (g / 100cm < ² >).
W = (m1-m0) / A × 100
m1 (g): Mass after absorbing water for 24 hours m0 (g): Reference mass A (cm ² ): Total surface area

<Measurement method and evaluation of flame retardancy>
Five test pieces having a rectangular parallelepiped shape having a length of 200 mm, a width of 25 mm, and a height of 10 mm are cut out from the obtained foamed molded article with a vertical cutter. After the cut material is cured in an oven at 60 ° C. for 1 day, the individual flame-out time is measured according to the measurement method A of JIS A9511-2006. The average value of the individual flame extinguishing times of 5 test pieces is taken as the flame extinguishing time. In addition, the flame retardance was evaluated according to the following criteria from the flame extinguishing time.
Good (○) ・ ・ ・ Extinguishing time 1.5 seconds or more to less than 3.0 seconds Very good (◎) ・ ・ ・ Extinguishing time less than 1.5 seconds Unmeasured (-) ・ ・ ・ Measured Absent

<Total content of aromatic organic compound>
The total content of the aromatic organic compound is a value measured by the following << Method for measuring volatile organic compound (VOC) content >>.
<< Measurement Method of Volatile Organic Compound (VOC) Content >>
Weigh accurately 1 g of foamed molded product, add 1 mL of dimethylformamide solution containing 0.1% by volume of cyclopentanol as an internal standard solution, and then add dimethylformamide to the dimethylformamide solution to prepare 25 mL of the measurement solution. Then, 1.8 μL of this measurement solution was supplied to a 230 ° C. sample vaporization chamber, and a gas chromatograph (manufactured by Shimadzu Corporation, trade name “GC-14A”) was detected for each volatile organic compound under the following measurement conditions. Based on the calibration curve of each volatile organic compound measured in advance, the amount of volatile organic compound is calculated from each chart, and the amount of volatile organic compound in the foamed molded product is calculated. When calculating the amount of the volatile organic compound in the expandable particles, 1 g of the expandable particles is precisely weighed and measured in the same manner.
Detector: FID
Column: GL Sciences (3mmφ × 2.5m)
Liquid phase: PEG-20M PT 25%
Carrier; Chromosorb W AW-DMCS
Mesh: 60/80
Column temperature: 100 ° C
Detector temperature: 230 ° C
DET temperature: 230 ° C
Carrier gas (nitrogen)
Carrier gas flow rate (40mL / min)
In addition, among the volatile organic compound (VOC) content described above, the total amount of each volatile organic compound corresponding to the aromatic organic compound is defined as “total content of aromatic organic compound”.

Example 1
Acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd .: Denka Black granular grade, average primary particle size 35 nm, specific surface area) with respect to 95 parts by mass of virgin polystyrene (trade name “HRM-10N”, manufactured by Toyo Styrene Co., Ltd.) having a weight average molecular weight of 200,000 69 m ² / g), 5 parts by mass of fine powder talc as an inorganic foam nucleating agent, 5 parts by mass of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) as a flame retardant, These were continuously supplied to a single screw extruder having a diameter of 90 mm at 150 kg per hour. The temperature inside the extruder was set to a maximum temperature of 220 ° C., and after the resin was melted, 6 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 maintained at 170 ° C., the pressure at the resin introduction part of the die is maintained 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 the cutting chamber connected to the discharge side of this die and circulating water at 30 ° 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 styrene resin expandable particles were acetylene black: styrene resin = 1: 19 (mass ratio). The obtained styrenic resin expandable particles were almost spherical without deformation and beard, and the average particle size was about 1.1 mm.

Next, 2000 g of the obtained styrene resin foamable particles, 2000 g of water, 6 g of magnesium pyrophosphate, and 0.3 g of sodium dodecylbenzenesulfonate were supplied to a polymerization vessel equipped with a stirrer with an internal volume of 5 L, sealed, and heated to 30 ° C. Nitrogen was injected until the internal pressure of the polymerization vessel reached 1.0 MPa. Next, the mixture was heated to 60 ° C. with stirring and held for 1 hour, and then cooled to 25 ° C. or lower. Thereafter, 0.03 parts by mass of polyethylene glycol, 0.15 parts by mass of zinc stearate, 0.05 parts by mass of monoglyceride stearate, and 0.05 parts by mass of triglyceride hydroxystearate are added to the entire surface of the particles with respect to 100 parts by mass of the particles. Uniformly coated. The obtained particles were heated to be prefoamed to a bulk density of 0.019 g / cm ³ to obtain prefoamed particles. 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 and found to be 0.020 g / cm ³ . This foamed molded article is excellent in appearance without shrinkage, and is formed from large bubbles having a bubble diameter of 0.2 to 1 mm and small bubbles having a diameter of 0.15 mm or less. The small bubbles of 0.15 mm or less had an occupation ratio of 55%. Moreover, the thermal conductivity of this foam was 0.028 w / mk.

(Example 2)
Pre-expanded particles were obtained in the same manner as in Example 1 except that the styrene resin expandable particles were heated at 50 ° C. under a nitrogen pressure of 1.0 MPa in a polymerization vessel equipped with a stirrer having an internal volume of 5 L. The density of the obtained foamed molded product is 0.020 g / cm ^3, which is formed from large bubbles having a bubble diameter of 0.2 to 1 mm and small bubbles having a size of 0.15 mm or less. Small bubbles of 0.15 mm or less per area had an occupancy of 22%. Moreover, the thermal conductivity of this foam was 0.029 w / mk.

(Example 3)
Pre-expanded particles were obtained in the same manner as in Example 1 except that the styrene resin expandable particles were heated at 70 ° C. under a nitrogen pressure of 1.0 MPa in a polymerization vessel equipped with a stirrer having an internal volume of 5 L. The density of the obtained foamed molded product is 0.020 g / cm ³ , and the foam is formed from large bubbles having a bubble diameter of 0.2 mm to 1 mm and small bubbles of 0.15 mm or less. Small bubbles of 0.15 mm or less per area had an occupancy of 75%. Moreover, the thermal conductivity of this foam was 0.029 w / mk.

  Table 2 below shows the results of Examples 1 to 3.

  From the above results, it becomes clear that when the expandable particles containing the carbon material are heat-treated at 50, 60 or 70 ° C. before the pre-expansion, a foamed molded article having good thermal conductivity can be obtained. It was.

  Tables 3 and 4 below show various physical properties of the styrenic resin expandable particles, pre-expanded particles, and foamed molded products obtained in Examples 1 to 3 above.

Claims (6)

Including a styrenic resin and a carbon material,
A styrene-based resin expanded particle comprising large bubbles of 0.2 to 1 mm and small bubbles of 0.15 mm or less.   The styrene resin foamed particles according to claim 1, wherein the small bubbles of 0.15 mm or less have an occupancy of 10 to 90% per cross-sectional area of the styrene resin foamed particles. The styrene resin expanded particle according to claim 1 or 2, wherein the carbon material is conductive carbon black having a volume resistivity of 1.0 x 10 ⁴ Ω · cm or less. A styrene resin foam molded article comprising a plurality of styrene resin foam particles fused together, including a styrene resin and a carbon material,
Each of the fused styrene-based resin expanded particles includes large bubbles of 0.2 to 1 mm and small bubbles of 0.15 mm or less.   The styrene resin foam molded article according to claim 4, wherein the small bubbles of 0.15 mm or less have an occupancy of 10 to 90% per sectional area of the styrene resin foam molded article. The styrene-based resin foam molded article according to claim 4 or 5, wherein the carbon material is conductive carbon black having a volume resistivity of 1.0 × 10 ⁴ Ω · cm or less.