JP6013905B2 - Foam molded body and method for producing foam molded body - Google Patents

Description

  The present invention relates to a foam molded article having excellent heat insulation (low thermal conductivity) and light resistance, and a method for producing the foam molded article.

  A foamed molded product containing polystyrene resin (hereinafter abbreviated as “foamed molded product”) forms a closed cell structure containing air, and thus has low thermal conductivity and high heat insulation. For this reason, the foaming molding has been conventionally used for various applications such as a heat insulating material for a house, a heat insulating container, a heat insulating panel for refrigeration equipment.

  In recent years, higher thermal insulation performance has been demanded for foam molded articles, and foam molded articles to which graphite, which is an infrared absorber, is added are known.

  For example, Patent Document 1 discloses an expandable styrene polymer obtained by polymerizing styrene in a suspension aqueous solution in the presence of graphite particles and adding a foaming agent before, during or after the polymerization. A polystyrene foam (foamed molded article) produced by pre-foaming (expandable particles) and then fusing them is disclosed.

  Patent Document 2 discloses a method in which granulated beads (expandable particles) obtained by kneading a resin, graphite, and a foaming agent in an extruder and cutting the resin in water simultaneously with extrusion are dried. Further, a foam molded article produced by covering with a coating, pre-foaming, and fusing is disclosed.

Japanese Patent No. 3954112 Special table 2010-527391

  By the way, the foam molded articles disclosed in Patent Documents 1 and 2 are entirely colored black by graphite contained in order to obtain heat insulation performance. For this reason, the foamed molded products disclosed in Patent Documents 1 and 2 easily absorb light such as sunlight, and when exposed to light such as sunlight, they are deformed by the influence of ultraviolet rays contained in the light. There was a risk of losing. That is, the foamed molded products disclosed in Patent Documents 1 and 2 were poor in light resistance.

  This invention is made | formed in view of such a condition, Comprising: It aims at providing the manufacturing method of a foaming molding which was excellent in heat insulation and excellent in light resistance, and this foaming molding.

  As a result of intensive studies, the inventors of the present invention have found that the light resistance can be improved by improving the whiteness of the main surface of the foamed molded product, and have completed the present invention.

The foamed molded product of the present invention is a foamed molded product containing a styrene-based resin, and has a main surface having a CIE 1976 lightness L ^* represented by an L ^* a ^* b ^* color system of 70 or more, Graphite is contained at least in the other part inside the foamed molded body than the surface layer part, and has a thermal conductivity of 0.0340 W / m · K or less.

Since the foamed molded article of the present invention has a main surface with high whiteness, specifically, a CIE 1976 brightness L ^* represented by the L ^* a ^* b ^* color system, it is sunlight. It is difficult to absorb light such as. For this reason, when exposed to light such as sunlight, deformation due to the influence of ultraviolet rays contained in the light can be suppressed. That is, the foamed molded product of the present invention has excellent light resistance. In the foamed molded product of the present invention, graphite is contained at least in the other part inside the foamed molded product than the surface layer portion, and the thermal conductivity is suppressed to 0.0340 W / m · K or less. Therefore, the foamed molded article of the present invention is excellent in heat insulation.

The method for producing a foamed molded product of the present invention includes a first step of producing foamable particles by impregnating a styrene resin particle with a foaming agent, and a second step of producing prefoamed particles by foaming the foamable particles. And the pre-expanded particles are subjected to in-mold foam molding, and have a main surface having a CIE 1976 lightness L ^* represented by L ^* a ^* b ^* color system of 70 or more and 0.0340 W / m · K or less. A third step of obtaining a foamed molded article having thermal conductivity, wherein in the first step, as the styrene resin particles, resin particles containing a styrene resin and graphite, wherein the graphite in the resin particles Resin particles satisfying the relational expressions of X = 3 to 10 and X ≧ 1.1 × Y, where X is X wt% and the graphite content in the surface layer of the resin particles is Y wt% To do And features.

  According to this manufacturing method, the above-described foamed molded article of the present invention, that is, a foamed molded article having excellent heat insulation and light resistance can be obtained.

Another method for producing a foamed molded article of the present invention produces a first foamed member containing a styrene-based resin and graphite, and having a CIE 1976 lightness L ^* represented by L ^* a ^* b ^* color system of less than 70. A second step of manufacturing a second foamed member that includes at least a styrene-based resin and has a CIE 1976 lightness L ^* represented by L ^* a ^* b ^* color system of 70 or more, The second foamed member is provided on at least the surface of one foamed member, and has a main surface having a CIE1976 lightness L ^* expressed by L ^* a ^* b ^* color system of 70 or more, and 0.0340 W / m · K And a third step of obtaining a foamed molded product having the following thermal conductivity.

  According to this manufacturing method, the above-described foamed molded article of the present invention, that is, a foamed molded article having excellent heat insulation and light resistance can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in heat insulation and can provide the foaming molding which was excellent in light resistance, and the manufacturing method of this foaming molding.

FIG. 1 is a schematic cross-sectional view showing a cross-sectional state when the foamed molded body according to Embodiment 1 of the present invention is cut along the thickness direction. FIG. 2 is a schematic cross-sectional view showing a cross-sectional state when the foamed molded product according to Embodiment 2 of the present invention is cut along the thickness direction. FIG. 3 is a schematic cross-sectional view showing a state of a cross section when the foamed molded body according to the modification of the second embodiment of the present invention is cut along the thickness direction.

  Hereinafter, the present invention will be described in detail.

[Foamed molded article of the present invention]
(Foamed molded product)
The foamed molded article of the present invention contains a styrenic resin and has a main surface having a CIE 1976 lightness L ^* (hereinafter abbreviated as lightness L ^* ) represented by L ^* a ^* b ^* color system of 70 or more. Have. In the foamed molded product of the present invention, graphite is contained at least in the other part inside the foamed molded product than the surface layer portion, and has a thermal conductivity of 0.0340 W / m · K or less. . If the thermal conductivity exceeds 0.0340 W / m · K, the heat insulation is insufficient. The thermal conductivity of the foamed molded product of the present invention is preferably 0.0280 to 0.0340 W / m · K.

In the foamed molded product of the present invention, graphite is present (locally distributed) in the surface layer portion less than the entire foamed molded product (more in the central portion). Therefore, the lightness L ^* can be improved and the color tone of the main surface of the foamed molded product can be brought close to white with respect to the foamed molded product in which the graphite exists substantially uniformly throughout.

(Main surface of foam molding)
As described above, the foamed molded article of the present invention has a main surface with a lightness L ^* of 70 or more, preferably 70 to 90.

As long as this main surface has a lightness L ^{* of} 70 or more, the foam molded article of the present invention may contain graphite in the surface layer portion or may not contain graphite in the surface layer portion. When the surface layer portion does not contain graphite, the lightness L ^{* of the} main surface can be increased (increased whiteness), so that the absorption of light such as sunlight is suppressed, and the deformation due to ultraviolet rays is suppressed. , Light resistance can be further increased. On the other hand, when the surface layer portion contains graphite, the thermal conductivity of the surface of the foam molded article can be kept low.

  In the present specification, “surface” means an interface in contact with the atmosphere (for example, air) in the foamed molded product, and “main surface” means a main surface having the largest area among the surfaces. Further, in the foamed molded product, the “surface layer portion” means a region within 2% of the thickness of the foamed molded product from the main surface as described in the Examples section described later.

(Styrene resin)
The styrene resin is not particularly limited as long as it includes a component derived from a styrene monomer.

  The styrene monomer is not particularly limited, and styrene or a styrene derivative can be used. Examples of the styrene derivative include α-methylstyrene, vinyltoluene (for example, a mixture of m-vinyltoluene and p-vinyltoluene), chlorostyrene (for example, 3-chlorostyrene, 4-chlorostyrene, etc.), ethylstyrene ( For example, 3-ethyl styrene, 4-ethyl styrene, etc., isopropyl styrene (for example, 4-isopropyl styrene, etc.), dimethyl styrene (for example, 3,5-dimethyl styrene, 2,3-dimethyl styrene, etc.), bromostyrene ( Examples thereof include 2-bromostyrene, 3-bromostyrene, 4-bromostyrene, and the like. These styrenic monomers may be used alone or in combination of two or more.

  The styrenic resin may contain a component derived from a vinyl monomer copolymerizable with the styrenic monomer (a vinyl monomer excluding the styrenic monomer). Examples of the vinyl monomer include divinylbenzene such as o-divinylbenzene, m-divinylbenzene and p-divinylbenzene, alkylene glycol di (meth) acrylate such as ethylene glycol di (meth) acrylate and polyethylene glycol di (meth) acrylate. And polyfunctional vinyl monomers such as (meth) acrylate; monofunctional vinyl monomers such as (meth) acrylonitrile and (meth) acrylate esters such as methyl (meth) acrylate. These vinyl monomers may be used alone or in combination of two or more. In the present specification, “vinyl monomer” means a compound having at least one ethylenically unsaturated group (in a broad sense, vinyl group), and “polyfunctional vinyl monomer” means two or more. And a “monofunctional vinyl monomer” means a vinyl monomer having one ethylenically unsaturated group. In the present specification, “(meth) acrylate” means acrylate or methacrylate, “(meth) acrylonitrile” means acrylonitrile or methacrylonitrile, and “(meth) acryl” means acryl or methacryl. Shall mean.

  Among the vinyl monomers, the polyfunctional vinyl monomer can improve the appearance of the foamed molded article. As a polyfunctional vinyl monomer for improving the appearance of the foamed molded article, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate (the number of ethylene glycol repeats is 4 to 16), and Divinylbenzene is preferred, and divinylbenzene and ethylene glycol di (meth) acrylate are more preferred.

  When the styrene resin contains the vinyl monomer, the content of the component derived from the vinyl monomer in the styrene resin is derived from the styrene monomer in the styrene resin. It is preferable that the amount of the component to be a main component of the polymer component (the sum of the component derived from the styrene monomer and the component derived from the vinyl monomer), that is, less than 50% by weight. .

(Graphite)
In the foamed molded product of the present invention, graphite is contained at least in the other part inside the foamed molded product than the surface layer portion.

  The graphite is not particularly limited, and any known natural and artificial graphite can be used. As the graphite, graphite having various shapes can be used, and among these, graphite having a scaly shape, a flake shape, or a soil shape is preferable.

(Average particle diameter of graphite)
The average particle size of the graphite is preferably 1 to 100 μm, and more preferably 5 to 80 μm. When the average particle diameter of graphite is smaller than 1 μm, the thermal conductivity of the foamed molded product exceeds 0.0340 W / m · K, and there is a possibility that heat insulation cannot be secured. On the other hand, if the average particle diameter of graphite is larger than 100 μm, the bubble film in the foamed molded product may be broken, and the closed cell structure may be collapsed, and thus stable heat insulation may not be obtained. .

Moreover, when the said graphite is contained in the said surface layer part, it is preferable that the average particle diameter of the graphite in the said surface layer part is 30-100 micrometers. When the average particle diameter of graphite in the surface layer portion is smaller than 30 μm, the lightness L ^* of the surface layer portion (the surface of the foam molded body) is less than 70, and the foam molded body may not have sufficient light resistance. There is. On the other hand, if the average particle diameter of the graphite contained in the surface layer portion exceeds 100 μm, the bubble film in the foamed molded product is torn and may cause shrinkage during molding.

(Graphite content)
The graphite content in the foamed molded product of the present invention (the ratio of the weight of graphite contained in the foamed molded product to the weight of the foamed molded product) is not particularly limited, but for example, 3 to 10% by weight, more preferably When the content is 5 to 10% by weight, the foamed molded product can be provided with a thermal conductivity of 0.0340 W / m · K or less.

  Further, when graphite is included in the surface layer portion, the graphite content in the foamed molded article is X wt%, and the graphite content in the surface layer portion (the weight of the graphite included in the surface layer portion relative to the weight of the surface layer portion). It is preferable that the relational expression of X = 3 to 10 and X ≧ 1.1 × Y is satisfied when the weight ratio) is Y wt%. That is, in the foam molded body, it is preferable that the graphite is unevenly distributed in the central portion of the foam molded body.

In the case where graphite is included in the surface layer portion, if the graphite content (X wt%) in the foam molded body is less than 3 wt%, the heat insulating property of the foam molded body may be inferior, and it is more than 10 wt%. In this case, the lightness L ^{* of the} main surface may be less than 70. The graphite content in the foamed molded product is more preferably 5 to 10% by weight.

When graphite is included in the surface layer portion, the graphite content (X wt%) in the foamed molded product and the graphite content (Y wt%) in the foamed molded product are X <1.1 ×. When satisfying the relationship of Y, the uneven distribution of the graphite at the center portion becomes insufficient, and the color tone of the main surface of the foamed molded product approaches black due to the graphite existing in the surface layer portion (specifically, the lightness L ^* is (Under 70). If the color tone of the main surface of the foam molded product approaches black, the foam molded product may be deformed by the influence of ultraviolet rays contained in the light when exposed to light such as sunlight (that is, light resistance). May be damaged). A more preferable relational expression between X weight% and Y weight% is X ≧ 1.2 × Y, and a more preferable relational expression is X ≧ 1.5 × Y.

(Other ingredients)
The foamed molded article of the present invention may contain additives such as a flame retardant, a flame retardant aid, a plasticizer, an antistatic agent, a filler, and a colorant, as long as the physical properties are not impaired.

  Flame retardants include tetrabromocyclooctane, hexabromocyclododecane, tris (2,3-dibromopropyl) phosphate, tetrabromobisphenol A, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) And flame retardants such as tetrabromobisphenol A-bis (2,3-dibromopropyl ether).

  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. It is done.

  Examples of the plasticizer include glycerin fatty acid esters such as phthalic acid ester, glycerin diacetomonolaurate, glycerin tristearate and diacetylated glycerin monostearate, and adipic acid esters such as diisobutyl adipate.

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

As long as the foamed molded article according to the present invention contains the styrenic resin and graphite, and the lightness L ^{* of the} main surface is 70 or more and has a thermal conductivity of 0.0340 W / m · K or less, It may have any configuration. In the following, two embodiments are shown as embodiments of the above-described foamed molded product according to the present invention, but the foamed molded product of the present invention is not limited to the foamed molded product according to the following embodiments.

[Embodiment 1]
(Foamed molded product 1)
The foam molded body 1 according to Embodiment 1 is the above-described foam molded body of the present invention, and has the configuration and characteristics of the above-described foam molded body of the present invention. For this reason, in this section, a configuration unique to the foamed molded product according to Embodiment 1 will be mainly described, and description of other configurations will be omitted.

  FIG. 1 is a schematic cross-sectional view showing a state of a cross section when the foamed molded body 1 according to Embodiment 1 of the present invention is cut along the thickness direction.

  As shown in FIG. 1, the foamed molded body 1 according to Embodiment 1 is formed by fusing a plurality of foamed particles 2. Each of the expanded particles 2 is a surface layer portion in which a styrene resin particle (hereinafter referred to as styrene resin particle A) containing the styrene resin and the graphite is expanded by a foaming agent, and the lightness L * is 70 or more. 21 (specifically, the main surface). That is, the main surface 11 of the foam molded body 1 according to Embodiment 1 is composed of a continuous body of the surface layer portion 21 of the foamed particles 2 (more specifically, the surface of the foamed particles 2). It has a lightness L *.

(Styrene resin particles A)
In Embodiment 1, the styrenic resin particles A contain the styrenic resin and the graphite. When the graphite is unevenly distributed in the center of the particle and foamed, the L * a * b * color system is used. The CIE 1976 lightness L * represented is not particularly limited as long as it has the surface layer portion 21 of 70 or more.

  In the expanded particles 2 formed by expanding the styrene resin particles A, the dispersed state of graphite in the styrene resin particles A is maintained. Therefore, even in the foamed molded body 1 composed of the fused body of the foamed particles 2, the dispersed state of graphite in the styrene resin particles A is maintained. For this reason, the graphite content in the surface layer portion of the foam molded body 1 obtained from the styrene resin particles A in which the graphite is unevenly distributed in the particle central portion is smaller than the graphite content in the entire foam molded body.

  For example, when the styrene resin particle A has a graphite content of X wt% in the entire styrene resin particle A and a Y content of graphite in the surface layer portion of the styrene resin particle A, It is preferable that the relational expression of X = 3 to 10 and X ≧ 1.1 × Y is satisfied. In addition, since it is difficult to measure the graphite content in the surface layer portion of the styrene resin particle A from the styrene resin particle A itself, in this specification, the foam molding obtained from the styrene resin particle A is used. The graphite content measured from the surface layer of the body 1 is replaced. This utilizes the fact that the surface layer portion of the foam molded body 1 is a continuous body of the surface layer portion 21 of the foamed particles 2 formed by foaming the styrenic resin particles A. The method for measuring the graphite content in the surface layer portion of the foam molded article 1 is described in the Example section. According to this measurement method, about 30% of the radius from the surface of the styrenic resin particle A is obtained. It is considered that the amount of graphite corresponding to the region is being measured.

When the content of graphite in the styrene resin particles A as a whole is less than 3% by weight, the heat insulating property of the foam molded article 1 obtained from the styrene resin particles A may be inferior. When the content is more than 10% by weight, the surface layer 21 of the expanded particle 2 obtained from the styrene-based resin particle A, in other words, the lightness L ^* of the main surface of the expanded molded body 1 obtained by fusing the expanded particle 2 is obtained ^. May decrease. The preferable content rate of the graphite in the said styrene-type resin particle A whole is 5 to 10 weight%.

  When X weight% and Y weight%, which are graphite contents, satisfy the relationship of X <1.1 × Y, the uneven distribution of graphite in the central portion becomes insufficient, and the surface layer portion of the styrene-based resin particle A is not present. The existing graphite may inhibit the fusion of the expanded particles 2 during the in-mold foam molding. A preferable relational expression between X weight% and Y weight% is X ≧ 1.2 × Y, and a more preferable relational expression is X ≧ 1.5 × Y.

  The shape of the styrene resin particles A is not particularly limited, but is preferably spherical from the viewpoint of ease of molding. Further, the particle diameter of the styrene-based resin particles A is preferably 0.3 to 2.0 mm in consideration of the filling property in the mold in the manufacturing method of the foam molded body 1 described later, and 0.3 to 1. 4 mm is more preferable.

  Styrenic resin particles A include a flame retardant, a flame retardant aid, a plasticizer, a lubricant, a binding inhibitor, a fusion accelerator, an antistatic agent, a spreading agent, a cell conditioner, and the like within a range that does not impair physical properties. Additives such as cross-linking agents, fillers, and colorants may be included. As the flame retardant, the flame retardant aid, the plasticizer, the antistatic agent, the filler, and the colorant, the same as those exemplified in the description of the foamed molded article of the present invention can be used.

  Examples of the lubricant include paraffin wax and zinc stearate.

  Examples of the binding inhibitor include calcium carbonate, silica, zinc stearate, aluminum hydroxide, ethylene bis-stearic acid amide, tricalcium phosphate, and dimethyl silicone.

  Examples of the fusion accelerator include stearic acid, stearic acid triglyceride, hydroxystearic acid triglyceride, stearic acid sorbitan ester, and polyethylene wax.

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

  Examples of the bubble regulator include methacrylic acid ester copolymer, ethylene bis stearamide, polyethylene wax, ethylene-vinyl acetate copolymer, and the like.

(Method for producing styrene resin particles A)
The styrenic resin particles A may be produced by any method as long as graphite is unevenly distributed at the particle central portion. For example, the styrenic resin containing graphite in an aqueous suspension is used. It can be easily produced by a so-called seed polymerization method including a step of absorbing the monomer mixture in the produced seed particles and a step of polymerizing the monomer mixture after absorption or absorption. The monomer mixture is a mixture composed of the above-described styrene monomer and optionally other vinyl monomers.

  In addition, when using the particle | grains made from a styrene resin for a seed particle, the quantity of a seed particle is also contained in content of a styrene resin component.

(A) Seed particles The styrene resin constituting the seed particles is the same as the styrene resin contained in the above-described foamed molded article of the present invention. In addition, a part of or all of the seed particles may be a styrene resin recovered product.

  The average particle size of the seed particles can be appropriately adjusted according to the average particle size of the styrene resin particles A to be produced. For example, the average particle size of the seed particles can be 40 to 70% of the average particle size of the styrene resin particles A. Specifically, when producing the styrene resin particles A having an average particle diameter of 1.0 mm, it is preferable to use seed particles having an average particle diameter of about 0.4 to 0.7 mm.

  The weight average molecular weight of the seed particles is not particularly limited, but is preferably 150,000 to 700,000, more preferably 200,000 to 500,000.

  The seed particles are not particularly limited and can be produced by a known method. For example, a suspension polymerization method in which graphite is dispersed in a monomer and an aqueous suspension is used, or a method in which a raw material resin and graphite are melt-kneaded by an extruder, extruded into a strand shape, and cut with a desired particle diameter, Alternatively, a method of cutting graphite while granulating it in extruded water from a die after melt kneading can be mentioned.

  The seed particles may be particles obtained by impregnating and polymerizing the above-described styrenic monomer in an aqueous medium to particles obtained by a suspension polymerization method or a cutting method. Examples of the aqueous medium include water and a mixed medium of water and a water-soluble solvent (for example, lower alcohol).

  Polymerization of the styrenic monomer can be performed, for example, by heating at 60 to 150 ° C. for 2 to 20 hours.

  The styrenic monomer is usually polymerized in the presence of a polymerization initiator. The polymerization initiator is usually impregnated into particles obtained by a suspension polymerization method or a cutting method simultaneously with a styrene monomer. The polymerization initiator is not particularly limited as long as it is conventionally used for the polymerization of styrene monomers. 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-butylperoxyacetate, 2,2-t-butylperoxybutane, t-butylperoxy-3,3,5-trimethylhexanoate, di-t-butylperoxyhexahydroterephthalate, dicumyl Examples thereof include organic peroxides such as peroxides, azo compounds such as azobisisobutyronitrile, azobisdimethylvaleronitrile, etc. Among them, in order to prevent polymerization delay due to graphite, t-butylperoxy-2- Ethyl hexanoate or dicumylper And organic peroxides to generate a tertiary alkoxy radicals such Kisaido, azo compounds are preferred. More preferably, t-butyl peroxy-2-ethylhexanoate is used. The usage-amount of a polymerization initiator is the range of 0.01-2.00 weight part with respect to 100 weight part of styrene-type monomers, for example.

  In addition, suspension stabilizers may be used to disperse styrenic monomer droplets and seed particles in an aqueous medium. The suspension stabilizer is not particularly limited as long as it is conventionally used for suspension polymerization of a styrene monomer. 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 and magnesium pyrophosphate. The usage-amount of a suspension stabilizer is the range of 0.1-5.0 weight part with respect to 100 weight part of seed particles.

  And when using a sparingly soluble inorganic compound as a suspension stabilizer, it is preferable to use an anionic surfactant together. Examples of such an anionic surfactant include fatty acid soaps; N-acyl amino acids or salts thereof; carboxylates such as alkyl ether carboxylates; alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkylsulfosuccinates Sulfonates such as alkyl sulfoacetates and α-olefin sulfonates; sulfates such as higher alcohol sulfates, secondary higher alcohol sulfates, alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, etc. Salt: Phosphate ester salts such as alkyl ether phosphate ester salts and alkyl phosphate ester salts. The usage-amount of surfactant is the range of 0.5-20.0 weight part with respect to 100 weight part of suspension stabilizers, for example.

(B) Absorption / polymerization process of monomer mixture In the aqueous medium, the monomer mixture is absorbed by the seed particles. The polymerization of the monomer mixture is preferably performed while absorbing the monomer mixture. Styrene resin particles A are obtained by polymerization. When carrying out the polymerization while absorbing the monomer mixture, it is preferable to raise the temperature stepwise, the polymerization initiation temperature is in the range of ± 5 ° C. from the 10-hour half-life temperature of the polymerization initiator, It is desirable that the monomer addition end temperature is 25 ° C. or more higher than the 10-hour half-life temperature of the polymerization initiator.

  Examples of the aqueous medium include water and a mixed medium of water and a water-soluble solvent (for example, lower alcohol). Moreover, you may use a polymerization initiator, a suspension stabilizer, and surfactant similarly to the said item (a).

  The amount of the styrenic monomer used can be in the range of 80 to 900 parts by weight with respect to 100 parts by weight of the seed particles. If it is less than 80 parts by weight, it is difficult to make the graphite unevenly distributed in the center of the particle, and if it exceeds 900 parts by weight, the foamability may be lowered.

(Manufacturing method of foaming molding 1)
The foam molded body 1 of the first embodiment includes, for example, (1) a step of producing expandable particles by impregnating a styrene resin particle A with a foaming agent (first step: expandable particle manufacturing step), and (2 ) It has a step of producing pre-foamed particles by foaming expandable particles (second step: pre-foamed particle production step) and a step of foam-molding the pre-foamed particles (third step: molding step). It can be obtained by a manufacturing method.

(1) Expandable particle manufacturing process In the expandable particle manufacturing process, the styrenic resin particles A are impregnated with a foaming agent to obtain expandable particles.

  The foaming agent is not particularly limited as long as it is conventionally used for foaming the styrene resin particles A. Examples thereof include volatile foaming agents (physical foaming agents) such as aliphatic hydrocarbons having 5 or less carbon atoms such as propane, isobutane, n-butane, isopentane, neopentane, and n-pentane. Of these, butane-based blowing agents such as isobutane and n-butane are preferred.

  If the content of the foaming agent in the foamable particles is small, it may not be possible to obtain a foamed molded article having a desired density, and the effect of increasing the secondary foaming power during in-mold foaming will be small. The appearance of the molded product may deteriorate. Moreover, since the time which the cooling process in the manufacturing process of a foaming molding body requires will become long when there are many, productivity may fall. From these viewpoints, the content is preferably in the range of 2.5 to 8.0% by weight, and more preferably in the range of 2.7 to 7.0% by weight.

  The content of the foaming agent in the expandable particles can be obtained by placing the expandable particles in a 150 ° C. pyrolysis furnace and measuring the amount of hydrocarbon generated in the pyrolysis furnace with a chromatograph.

  The impregnation with the foaming agent may be performed after polymerizing the monomer mixture in the step of producing the styrene resin particles A, or may be performed while polymerizing the monomer mixture.

  Impregnation can be performed by a method known per se. For example, the impregnation during the polymerization can be performed by performing the polymerization reaction in a closed container and press-fitting a foaming agent into the container. Impregnation after completion of the polymerization can be performed by press-fitting a foaming agent in a closed container.

  A known foaming aid may be used in combination with a foaming agent.

  If the temperature at which the styrene resin particles A are impregnated with the foaming agent and optionally the foaming aid is low, the time required for impregnating the styrene resin particles A with the foaming agent and the foaming aid becomes longer and the production efficiency is increased. If it is high, the styrene resin particles A may be fused with each other to produce bonded particles. Therefore, 60-120 degreeC is preferable and 70-100 degreeC is more preferable.

  Further, powder metal soaps such as zinc stearate and hydroxystearic acid triglyceride may be applied to the surface of the expandable particles. By applying, the bonding between the pre-expanded particles can be reduced in the foaming step of the expandable particles.

(2) Pre-expanded particle manufacturing process In the pre-expanded particle manufacturing process, the expandable particles are expanded by a known method to obtain pre-expanded particles. Steam can be suitably used as the heating medium for foaming.

  In the pre-expanded particles obtained, the dispersed form of graphite in the styrene resin particles A is maintained.

  The shape of the pre-expanded particles is preferably spherical or substantially spherical. Moreover, it is preferable that an average particle diameter is 0.8-4.0 mm. Furthermore, the bulk expansion ratio of the pre-expanded particles is preferably 20 to 60 times. In addition, in this specification, a bulk multiple means the reciprocal number of the bulk density obtained by the measuring method mentioned later.

(3) Molding process For example, the foamed molded body is prepared by filling pre-expanded particles in a closed mold having a large number of small holes, and again heating and foaming with water vapor or the like to form expanded particles (pre-expanded particles are further expanded). It can be manufactured by filling the voids between the expanded particles) and integrating the expanded particles by fusing them together. At that time, the bulk multiple of the foamed molded product can be adjusted by adjusting the amount of pre-expanded particles filled in the mold, for example.

[Embodiment 2]
(Foamed molded product 3)
The foamed molded product 3 according to Embodiment 2 is the above-described foamed molded product of the present invention, and has the configuration and characteristics of the above-described foamed molded product of the present invention. For this reason, in this section, a configuration unique to the foamed molded product according to Embodiment 2 will be mainly described, and description of other configurations will be omitted.

  FIG. 2 is a schematic cross-sectional view showing a cross-sectional state when the foamed molded product 3 according to Embodiment 2 of the present invention is cut along the thickness direction.

  As shown in FIG. 2, the foam molded body 3 according to the second embodiment includes a second foam member on the front surface (front surface) and the back surface (back surface) of the first foam member 5 (first foam layer). 4 (second foam layer) is provided, and the surface layer portion including the main surface 31 of the foam molded body 3 is constituted by the second foam member 4.

(First foam member 5)
The first foam member 5 includes the styrenic resin and the graphite. The first foam member 5 is formed by fusing a plurality of first foam particles 51. Each of the first foamed particles 51 is obtained by foaming a styrene resin particle (hereinafter referred to as styrene resin particle B) containing the styrene resin and the graphite with a foaming agent, and is black (specifically, The lightness L ^* is less than 70).

(Styrene resin particles B)
The styrenic resin particles B contain the styrenic resin and the graphite, and are black (that is, the lightness L ^* is less than 70). In the styrene resin particles B, it is preferable that the graphite is dispersed almost uniformly throughout the styrene resin particles B. In addition, the dispersion state of the graphite in the styrene resin particles B is also maintained in the first foamed particles 51 formed by foaming the styrene resin particles B.

  The graphite content in the styrene-based resin particles B is not particularly limited, but is preferably 5 to 15% by weight, more preferably 5 to 12% by weight, and the foamed molded body 3 has 0.0340 W / m · K or less. Thermal conductivity can be obtained reliably.

  The shape of the styrenic resin particles B is not particularly limited, but is preferably spherical from the viewpoint of ease of molding. Further, the particle diameter of the styrene resin particles B is preferably 0.3 to 2.0 mm in consideration of the filling property in the mold in the manufacturing method of the first foamed member 5 to be described later. 1.4 mm is more preferable.

  For the styrene resin particles B, the same flame retardant, flame retardant aid, plasticizer, lubricant, anti-bonding agent, adhesion promoter, antistatic as in the styrene resin particle A described above, as long as the physical properties are not impaired. Additives such as an agent, a spreading agent, a bubble regulator, a crosslinking agent, a filler, and a colorant may be contained.

(Method for producing styrene resin particles B)
The manufacturing method of the styrene resin particle B is not particularly limited, and a known method can be applied. For example, a suspension polymerization method in which graphite is dispersed in a monomer and an aqueous suspension is used, or a method in which a raw material resin and graphite are melt-kneaded by an extruder, extruded into a strand shape, and cut with a desired particle diameter, Alternatively, a method of cutting graphite while granulating it in extruded water from a die after melt kneading can be mentioned.

(Second foam member 4)
Moreover, the 2nd foaming member 4 contains the said styrene resin. The second foam member 4 is formed by fusing a plurality of second foam particles 41. Each of the second foamed members 4 is obtained by foaming styrene resin particles (hereinafter referred to as styrene resin particles C) containing the styrene resin with a foaming agent, and white (specifically, lightness L ^* 70 or more). The second foam member 4 may contain the graphite as long as the lightness L ^* is 70 or more.

(Styrene resin particles C)
The styrenic resin particles C contain the styrenic resin and have a white color (specifically, lightness L ^* is 70 or more). As long as the lightness L ^{* of} 70 or more is obtained, the styrene resin particles C may contain the above graphite. In addition, when the styrene resin particle C contains the graphite, it is preferable that the graphite is dispersed almost uniformly over the entire styrene resin particle C. In addition, the dispersion state of the graphite in the styrene resin particles C is also maintained in the second foamed particles 41 formed by foaming the styrene resin particles C.

When graphite is contained in the styrenic resin particles C, the content of the graphite is not particularly limited as long as the styrenic resin particles C have a lightness L ^{* of} 70 or more, preferably 1 to 5% by weight, more preferably Is 1 to 3% by weight, it is possible to reduce the thermal conductivity of the main surface of the foam molded article 3 while obtaining a lightness L ^{* of} 70 or more.

  The shape of the styrene resin particles C is not particularly limited, but is preferably spherical from the viewpoint of ease of molding. In addition, the particle diameter of the styrene resin particles B is preferably 0.3 to 2.0 mm in consideration of the filling properties in the mold in the method for manufacturing the second foamed member 4 described later, 1.4 mm is more preferable.

  The styrene resin particles C have the same flame retardant, flame retardant aid, plasticizer, lubricant, anti-bonding agent, adhesion promoter, antistatic as in the above-described styrene resin particles A within the range where physical properties are not impaired. Additives such as an agent, a spreading agent, a bubble regulator, a crosslinking agent, a filler, and a colorant may be contained.

(Method for producing styrene resin particles C)
The production method of the styrene resin particles C is not particularly limited, and a known method can be applied. For example, if necessary, graphite is dispersed in the monomer and suspension polymerization is performed in an aqueous suspension, or the raw material resin and graphite are melt-kneaded with an extruder, and then extruded into a strand shape with a desired particle size. A method of cutting, or a method of cutting graphite while granulating it in extruded water from a die after melt-kneading. Moreover, the manufacturing method of the styrene-type resin particle C can apply the method similar to the manufacturing method of the above-mentioned styrene-type resin particle A except using a graphite as needed.

(Method for producing foamed molded article 3)
The foamed molded body 3 of the second embodiment includes, for example, (1) a process of manufacturing the first foamed member 5 (first process: first foamed member manufacturing process) and (2) a second foamed member 4. It can be manufactured by a manufacturing method including a step (second step: second foaming member manufacturing step) and (3) a step of connecting the first foaming member 5 and the second foaming member 4 (third step: connecting step). .

(1) First foam member production process In the first foam member production process, the first foam member 5 is obtained using the styrene resin particles B. The 1st foaming member 5 can be manufactured by the manufacturing process similar to the foaming molding 1 of Embodiment 1 mentioned above except using the styrene resin particle B instead of the styrene resin particle A.

(2) Second Foaming Member Manufacturing Process In the second foaming member manufacturing process, the second foaming member 4 is obtained using the styrene resin particles C. The 2nd foaming member 4 can be manufactured by the manufacturing process similar to the foaming molding 1 of Embodiment 1 mentioned above except using the styrene resin particle C instead of the styrene resin particle A.

(3) Connection process Two 2nd foaming members 4 obtained by the 2nd foaming member manufacturing process are prepared, and these 2nd foaming members 4 are the surface (surface of the front side) and the back, respectively, of the 1st foaming member 5. The foamed molded body 3 is obtained by pasting to the (back surface) with an adhesive.

  As the adhesive, an adhesive using alcohol as a solvent is preferably used. For example, a vinyl acetate resin adhesive (solvent adhesive) for Bond (registered trademark) polystyrene foam manufactured by Konishi Co., Ltd. can be used.

(Modification of Embodiment 2)
As shown in FIG. 2, the foamed molded body 3 according to Embodiment 2 described above is configured by providing the second foamed member 4 on the front surface (front surface) and the back surface (back surface) of the first foamed member 5. As shown in FIG. 3, in addition to the front surface (front surface) and the back surface (back surface) of the first foam member 5, the second foam member is formed on all side surfaces of the first foam member 5. 4 may be provided to form the foam molded body 3 ′.

  Hereinafter, specific examples of the present invention will be described by way of examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited to the following examples. In addition, Examples 1 to 5 described later are specific examples of the foam molded body 1 (see FIG. 1) according to the first embodiment, and Example 6 is a foam molded body according to the second embodiment described above. 3 (see FIG. 2).

First, a method for measuring the average particle diameter of graphite contained in the surface layer portion of the foam molded article, a method for measuring the graphite content, a method for measuring the bulk density of the pre-foamed particles used in the production of the foam molded article, Measuring method of bulk density, measuring method of thermal conductivity of foamed molded product, measuring method of lightness L ^* of main surface of foamed molded product, evaluation method of light resistance of foamed molded product, measurement of fusion rate of foamed molded product The method and the evaluation method of the flame retardancy of the foamed molded product will be described.

[Method for measuring the average particle diameter of graphite contained in the surface layer portion of the foam molded article]
The foamed molded product is sliced to a thickness of 2% of the thickness of the foamed molded product with a slicer (manufactured by Fujishima Koki Co., Ltd., “FK-4N”), and this is treated as the surface layer portion of the foamed molded product. In addition, about the foaming molding (size: 300mmx400mmx30mm) of the Example and comparative example which are shown below, it slices into thickness 0.6mm, length 200mm, and width 200mm, and this is the surface layer of foaming molding Treat as part.

  About 0.1 g of the sliced surface layer is precisely weighed in a centrifuge tube, 5 mL of toluene is added, and the mixture is stirred for 30 minutes at room temperature to dissolve. After dissolution, the mixture is centrifuged for 30 minutes at a rotational speed of 10,000 rpm, the supernatant is removed, 5 mL of toluene is added, and the mixture is stirred again at room temperature for 30 minutes. Further, the mixture is centrifuged at a rotational speed of 10,000 rpm for 30 minutes, and after removing the supernatant, the centrifuge tube is washed with acetone, transferred to a 20 ml beaker and dried to obtain graphite.

  The dried graphite is magnified 100 to 300 times with a scanning electron microscope S-3000N (manufactured by Hitachi, Ltd.). For graphite (particles) in the photographed image, the length measured to maximize the length connecting the outer ends is the diameter of the graphite, and the same is true for 10 randomly selected graphite particles. Repeat the operation. The average value of the obtained diameters is defined as the average particle diameter of graphite.

[Method for measuring the content of graphite]
(1) Method for Measuring Content Ratio of Graphite in Surface Layer Portion The graphite content rate (concentration) is measured for the surface layer portion of the foam molded body obtained by slicing the foam molded body in the same manner as described above. The graphite content (concentration) is measured using a differential thermothermal gravimetric simultaneous measurement apparatus TG / DTA6200 type (manufactured by SII Nano Technology Co., Ltd.). The sampling method and temperature conditions are as follows. That is, about 15 mg of a sample is collected from the sliced surface layer portion and weighed accurately, and the sample is filled in the bottom of a platinum measurement container without any gaps. Measure with a measuring device. As temperature conditions, the temperature was raised from 30 ° C. to 520 ° C. at a rate of 10 ° C./min and a nitrogen gas flow rate of 250 mL / min, and then from 520 ° C. to 900 ° C. at a rate of 10 ° C./min and Air flow rate of 200 mL / min. Let the temperature rise. The graphite content (% by weight) (concentration) is calculated by the following method using dedicated data analysis software Muse. That is, from the TG curve obtained by the above measurement (vertical axis: TG (% by weight), horizontal axis: temperature (° C.)), the weight loss (% by weight) of the sample weight when the temperature is raised from 520 ° C. to 900 ° C. And the calculated weight loss (wt%) was defined as the graphite content (wt%) (concentration).

(2) Method for measuring the content ratio of graphite in the foamed molded product When the foamed molded product is composed of one kind of foamed particles (for example, when the configuration of the foamed molded product is the configuration shown in FIG. 1), foaming is performed. About 15 mg of a sample is taken from a test piece in which the fused particles (foamed particles) in the molded body are cut out so as to include the entire particles as much as possible, and precisely weighed, similar to the above-described measurement of the graphite content in the surface layer portion. By carrying out the measurement, the graphite content in the fused particles (foamed particles) is obtained. And let the content rate of the graphite in the obtained fusion | melting particle | grains (foamed particle) be the content rate of the graphite in a foaming molding.

  When the foamed molded product is composed of two or more types of foamed particles (for example, when the foamed molded product has the configuration shown in FIG. 2 or 3), various fused particles (foamed) in the foamed molded product are used. Particles) are cut out so as to include the entire particles as much as possible to obtain test pieces corresponding to various fused particles (foamed particles). Then, a sample of about 15 mg is collected from each obtained test piece and precisely weighed. And about each sample obtained from the test piece of various fusion | melting particle | grains (foaming particle), the same measurement as the measurement of the content rate of the graphite in the above-mentioned surface layer part was implemented, and in various fusion | melting particle | grains (foaming particle) Obtain the graphite content. And from the content rate of the graphite in the obtained various fused particles (foamed particles) and the ratio of the content of the various fused particles (foamed particles) contained in the foamed molded product, the graphite content in the foamed molded product Determine the content.

[Method for measuring bulk density of pre-expanded particles]
The bulk density of the pre-expanded particles is measured according to JIS K6911 “General Test Method for Thermosetting Plastics”. Specifically, first, Wg is collected using pre-expanded particles as a measurement sample, and this 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 pre-expanded particles is calculated.

Bulk density of pre-expanded particles (g / cm ³ ) = weight of measurement sample (W) / volume of measurement sample (V)

[Method for measuring bulk density of foamed molded article]
The weight (a) and volume (b) of a test piece (example 75 mm × 300 mm × 35 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. And the density (kg / m ³ ) of the foamed molded product is obtained from the formula (a) / (b).

[Method for measuring thermal conductivity of foamed molded article]
The thermal conductivity is measured by using a thermal conductivity measuring device HC-074 / 200 (Auto Λ) manufactured by Eihiro Seiki Co., Ltd. JIS A1412-2 “Measurement Method of Thermal Resistance and Thermal Conductivity of Thermal Insulating Material—Part 2 : Heat flow meter method (HFM method) ”. A test piece having a length of 200 mm, a width of 200 mm, and a thickness of 30 mm cut out from the foam molded article was allowed to stand under standard conditions of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5% for 24 hours. The thermal conductivity is measured by the above thermal conductivity measuring device under the conditions of a temperature of 23 ° C. (a high temperature side plate temperature of 38 ° C., a low temperature side plate temperature of 8 ° C.) and a plate temperature difference of 30 ° C. A NIST (National Institute of Standards and Technology) SRM1450B registered in the thermal conductivity measuring device is adopted as a reference value for calibration.

[Measurement method of lightness L ^* of the main surface of the foamed molded product]
The lightness L ^* of the main surface of the foamed molded product is measured according to the method described in JIS Z8722 “Color Measurement Method—Reflection and Transmission Object Color”. Specifically, a test piece having a size of 100 mm × 100 mm × thickness 30 mm was cut out from the foamed molded product, and the lightness L ^* of the main surface of the test piece was measured using a spectral colorimeter SE-2000 (Nippon Denshoku Industries Co., Ltd.). Measured by a reflection method using a data processing color mate 5 (manufactured by Nippon Denshoku Industries Co., Ltd.) and a D65 light source and a 10 ° visual field using a white plate dedicated to the back. The reference color is the color of the standard plate. Further, after the test piece is left at a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5% for 24 hours or more, the lightness L ^* is measured in an environment of a temperature of 20 ± 2 ° C. and a humidity of 65 ± 5%. A standard plate having tristimulus values (C / 2), Y = 96.09, X = 94.13, and Z = 113.36 is used.

[Method for evaluating light resistance of foamed molded article]
Conforms to JIS A1415 “Accelerated exposure test method for laboratory building light sources of polymer building materials WX-B” (cited standard JIS K7350-2 “Plastic—Exposure test method for laboratory light sources—Part 2: Xenon lamp”) And conduct an accelerated exposure test. The test piece is set on a Super Xenon Weather Meter SX75 type (manufactured by Suga Test Instruments Co., Ltd.) so that light is irradiated onto the main surface of a 60 mm × 150 mm × thickness 5 mm test piece (foamed molded article). Xenon lamp (water-cooled), inner filter (quartz), outer filter (# 275), black panel set temperature (63 ° C), no spray (no spraying), no dark turnover, irradiance (180 W / m ² : wavelength range 300 to 400 nm ), The accelerated exposure test is performed under the test tank set temperature (30 ° C.), the test tank set humidity (50%), and the irradiation condition of the irradiation time of 3 minutes. And the state of the test piece (foaming molding) after an accelerated exposure test is observed, and the light resistance of the foaming molding is evaluated according to the following evaluation criteria.

<Evaluation criteria>
A (good): The main surface of the foam molded article is not melted, and the foam molded article is not deformed.
X (Bad): Melting occurred on the main surface of the foam molded article, or the foam molded article was deformed.

[Flame retardancy evaluation method]
Five rectangular parallelepiped test pieces having a length of 200 mm, a width of 25 mm, and a thickness of 10 mm are cut out from the foamed molded article with a vertical cutter. In addition, when a foaming molding is comprised from several types of expanded particles (for example, in the case of the structure shown in FIG. 2 or FIG. 3), a test piece is used so that a plurality of types of expanded particles are included in one test piece. cut. After the test piece is cured in an oven at 60 ° C. for 1 day, the test piece is measured for flame retardancy according to flammability measurement method A of JIS A9511. The average value of the five test pieces is regarded as the flame extinction time, and the flame retardancy of the foamed molded product is evaluated based on the following evaluation criteria. In the JIS standard, the flame extinguishing time needs to be within 3 seconds, preferably within 2 seconds, and more preferably within 1 second.

<Evaluation criteria>
Extremely good (）): Flame extinguishing time is within 1 second, and all five samples have no residue and do not burn beyond the combustion limit indicating line.
Good (O): The extinguishing time is within 3 seconds, and all five samples have no residue and do not burn beyond the combustion limit indicator line.
Poor (x): The flame extinguishing time exceeds 3 seconds, or at least one test piece has residue or burns beyond the flammability limit indicating line.

[Measurement method of fusion rate and evaluation method of fusion property]
After the foamed molded product is dried for 24 hours, it is broken in half at the center in the length direction. With respect to the expanded particles in the fracture surface, the number (a) of particles broken in the particles and the number (b) of particles broken at the interface between the particles in an arbitrary range of 100 to 150, A value obtained by substituting into the formula [(a) / ((a) + (b))] × 100 is defined as a fusion rate (%). Then, the obtained fusion rate (%) is evaluated according to the following evaluation criteria.

<Evaluation criteria>
Very good (（): The fusion rate is 85% or more.
Good (O): The fusion rate is 80% or more and less than 85%.
Poor (x): The fusion rate is less than 80%.

  Next, the foam molded articles of Examples 1 to 6 and Comparative Examples 1 to 4 will be described below.

[Example 1]
(Seed particle manufacturing process)
8000 g of a styrene resin having a weight average molecular weight of 180,000 and 2000 g of scaly graphite having an average particle diameter of 70 μm (manufactured by Nippon Graphite Industry Co., Ltd., trade name “F # 3”) are supplied to a twin-screw extruder and 230 Melted and kneaded at 0 ° C., extruded into a strand from an extruder, and this strand was cut into predetermined lengths to produce seed particles made of a cylindrical styrene resin (diameter: 0.8 mm, length: 0.8 mm) Was made.

  Next, 2000 g of water, 500 g of seed particles, 6.0 g of magnesium pyrophosphate as a suspension stabilizer and 0.3 g of calcium dodecylbenzenesulfonate as an anionic surfactant are placed in a polymerization vessel equipped with a stirrer having an internal volume of 5 liters. The temperature was raised to 75 ° C. while feeding and stirring.

(Polymerization process)
Next, 13.5 g of t-butylperoxy-2-ethylhexanoate and 1.5 g of dicumyl peroxide as a polymerization initiator and 3.0 g of α-methylstyrene dimer as a chain transfer agent were converted into styrene. What was dissolved in 210 g of styrene monomer as a system monomer was supplied to the polymerization vessel, and the internal temperature of the polymerization vessel was maintained at 75 ° C. for 30 minutes.

  After 60 minutes, while the internal temperature of the polymerization vessel was raised to 110 ° C. over 150 minutes, 1290 g of styrene monomer was dropped into the polymerization vessel by a predetermined amount in 150 minutes. Next, after the internal temperature of the polymerization vessel was raised to 130 ° C., the contents of the polymerization vessel were cooled after 2 hours to obtain styrene-based resin particles A containing graphite.

(Process for producing expandable particles)
Subsequently, in another polymerization vessel equipped with a stirrer having an internal volume of 5 liters, 2200 g of water, 1800 g of styrene resin particles A obtained in the polymerization step, 6.0 g of magnesium pyrophosphate as a suspension stabilizer and dodecylbenzenesulfonic acid 0.4 g of calcium was supplied, and the internal temperature of the polymerization vessel was raised to 70 ° C. while stirring the contents in the polymerization vessel. Next, 18.0 g of diisobutyl adipate as a foaming aid, 19.8 g of tetrabromocyclooctane as a flame retardant, and 5.4 g of dicumyl peroxide as a flame retardant aid are placed in the polymerization vessel. And the internal temperature of the polymerization vessel was raised to 90 ° C. Next, 162 g of n-butane as a foaming agent was press-fitted into the polymerization vessel containing the styrene resin particles A, the internal temperature of the polymerization vessel was maintained at this temperature for 8 hours, and then cooled to 30 ° C. or lower. . The styrenic resin particles A impregnated with the foaming agent were taken out from the polymerization vessel and dried, and then left in a thermostatic chamber at 13 ° C. for 5 days to obtain expandable particles.

(Pre-expanded particle manufacturing process)
Subsequently, the surface of the expandable particles was coated with zinc stearate and hydroxystearic acid triglyceride as surface treatment agents. Next, the foamable particles whose surface was coated were prefoamed to a bulk density of 0.02 g / cm ³ using a prefoaming apparatus, and then aged at 20 ° C. for 24 hours to obtain prefoamed particles.

(Molding process)
And in the cavity of the foam bead automatic molding machine (made by Sekisui Koki Co., Ltd., trade name “ACE 3 type”) having a mold having a rectangular parallelepiped cavity with an inner dimension of 300 mm × 400 mm × 30 mm, the spare The pre-expanded particles obtained in the expanded particle production process were filled and subjected to heat molding (foam molding) with water vapor having a gauge pressure of 0.07 Mpa for 15 seconds. Next, the foam in the cavity of the mold was water-cooled for 5 seconds and then allowed to cool under reduced pressure (cooling step) to obtain a foam-molded body (density 0.02 g / cm ³ ).

The obtained foamed molded article did not shrink and had good fusion properties. Further, the obtained foamed molded article had a thermal conductivity of 0.0316 W / m · K and a low thermal conductivity. Further, the lightness L ^* of the main surface of the obtained foamed molded product was 78.7, and the obtained foamed molded product was hardly deformed by light and had good light resistance.

[Example 2]
In the seed particle manufacturing process, instead of scaly graphite having an average particle diameter of 70 μm (trade name “F # 3” manufactured by Nippon Graphite Industries Co., Ltd.), scaly graphite having an average particle diameter of 40 μm (Nippon Graphite Industries Co., Ltd.) A foamed molded article was obtained in the same manner as in Example 1 except that a product name “CB-100”) was used.

The obtained foamed molded article did not shrink and had good fusion properties. Further, the obtained foamed molded article had a thermal conductivity of 0.0312 W / m · K and a low thermal conductivity. Further, the lightness L ^* of the main surface of the obtained foamed molded product was 71.6, and the obtained foamed molded product was hardly deformed by light and had good light resistance.

Example 3
In the seed particle manufacturing process, instead of scaly graphite having an average particle diameter of 70 μm (trade name “F # 3” manufactured by Nippon Graphite Industries Co., Ltd.), scaly graphite having an average particle diameter of 93 μm (Nippon Graphite Industries Co., Ltd.) A foamed molded article was obtained in the same manner as in Example 1 except that a product name “F # 1873” manufactured by company was used.

The obtained foamed molded article did not shrink and had good fusion properties. Further, the obtained foamed molded article had a thermal conductivity of 0.0321 W / m · K and a low thermal conductivity. Further, the lightness L ^* of the main surface of the obtained foamed molded product was 84.3, and the obtained foamed molded product was hardly deformed by light and had good light resistance.

Example 4
In the polymerization step, except that the amount of t-butylperoxy-2-ethylhexanoate used as a polymerization initiator was 7.0 g and the amount of styrene monomer dropped into the polymerization vessel was changed from 1290 g to 540 g. In the same manner as in Example 1, a foamed molded product was obtained.

The obtained foamed molded article did not shrink and had good fusion properties. Further, the obtained foamed molded article had a thermal conductivity of 0.0294 W / m · K and a low thermal conductivity. Further, the lightness L ^* of the main surface of the obtained foamed molded product was 72.4, and the obtained foamed molded product was hardly deformed by light and had good light resistance.

Example 5
In the seed particle manufacturing process, the amount of styrene resin having a weight average molecular weight of 180,000 is 8800 g, and the scale-like graphite having an average particle diameter of 40 μm (trade name “CB100” manufactured by Nippon Graphite Industries Co., Ltd.) is used. A foamed molded product was obtained in the same manner as in Example 2 except that the amount was 1200 g.

The obtained foamed molded article did not shrink and had good fusion properties. Further, the obtained foamed molded article had a thermal conductivity of 0.0330 W / m · K and a low thermal conductivity. Further, the lightness L ^* of the main surface of the obtained foamed molded product was 80.5, and the obtained foamed molded product was hardly deformed by light and had good light resistance.

Example 6
(Manufacturing process of expandable particle A)
91.4% by weight of polystyrene resin (trade name “Toyostyrene (registered trademark) HRM10N” manufactured by Toyo Styrene Co., Ltd.) and 8.6 weight of graphite powder (trade name “J-CPB” manufactured by Nippon Graphite Industry Co., Ltd.) % Of the composition containing 50% by weight of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) (Daiichi Kogyo Seiyaku Co., Ltd.) as a flame retardant 7 parts by mass of a styrene resin master batch (corresponding to 3.5 parts by weight of flame retardant) was uniformly mixed with a tumbler mixer. This mixture was supplied to a single screw extruder having a diameter of 90 mm (L / D = 35) at a rate of 150 kg per hour. After the maximum temperature in the extruder was set to 220 ° C. and the composition was melted, isopentane as a volatile blowing agent (with a vapor pressure at 170 ° C. of 2.44 MPa) was added to 100 parts by weight of the composition. ) A resin composition was obtained by press-fitting 6 parts by weight from the middle of the extruder.

  A diverter (extruder and die) held at 185 ° C. while kneading the resin composition in the extruder and cooling so that the temperature of the resin composition becomes 180 ° C. at the tip of the extruder. The resin composition is placed on the circumference of the resin discharge surface with eight granulation dies (nozzle unit) having 25 nozzles having a diameter of 0.6 mm and a land length of 3.0 mm. Transported to the die). The transported resin composition is extruded into a chamber in which cooling water having a water temperature of 40 ° C. and a water pressure of 1.2 MPa circulates, and at the same time, a high-speed rotary cutter (10 blades in the circumferential direction) closely attached to the die. And a high-speed rotating cutter that rotates 3000 rpm. The cut resin composition was dehydrated and dried, and allowed to stand in a thermostatic chamber at room temperature of 15 ° C. for 3 days to obtain spherical expandable particles A (expandable styrene resin particles B).

(Process for producing pre-expanded particles A)
Subsequently, the surface of the expandable particles A was coated with zinc stearate and hydroxystearic acid triglyceride as surface treatment agents. Next, the foamable particles A whose surfaces were coated were prefoamed to a bulk density of 0.02 g / cm ³ using a prefoaming apparatus, and then aged at 20 ° C. for 24 hours to obtain prefoamed particles A. .

(Manufacturing process of the first foam member)
And in the cavity of the foam bead automatic molding machine (trade name “ACE 3 type” manufactured by Sekisui Koki Co., Ltd.) equipped with a molding die having a rectangular parallelepiped cavity with an inner dimension of 300 mm × 400 mm × 20 mm, The pre-expanded particles A were filled and heat-molded (foamed) for 15 seconds with water vapor having a gauge pressure of 0.07 Mpa. Next, the foam in the cavity of the mold was water-cooled for 5 seconds and then allowed to cool under reduced pressure (cooling step) to obtain a first foamed member (density 0.02 g / cm ³ ).

(Manufacturing process of expandable particle B)
Expandable particles (expandable particles B) were obtained by the same production process as that of Example 1 except that graphite was not used.

(Process for producing pre-expanded particles B)
Subsequently, the surface of the expandable particle B was coated with zinc stearate and hydroxystearic acid triglyceride as a surface treatment agent. Next, the foamable particles B whose surface was coated were prefoamed to a bulk density of 0.02 g / cm ³ using a prefoaming apparatus, and then aged at 20 ° C. for 24 hours to obtain prefoamed particles B. .

(Manufacturing process of second foam member)
And it pre-foams in the cavity of a foam bead automatic molding machine (trade name “Ace 3 type” manufactured by Sekisui Koki Co., Ltd.) equipped with a mold having a rectangular parallelepiped cavity with inner dimensions of 300 mm × 400 mm × 10 mm. The particles B were filled and heat-molded (foamed) for 12 seconds with water vapor having a gauge pressure of 0.07 Mpa. Next, the foam in the cavity of the mold was water-cooled for 5 seconds and then allowed to cool under reduced pressure (cooling step) to obtain a second foamed member (density 0.02 g / cm ³ ).

(Linking process)
The second foamed member was equally divided in the thickness direction to obtain two foamed molded members B each having a size of 300 mm × 400 mm × 5 mm. The obtained two second foamed members are bonded to the front and back surfaces of the first foamed member using a vinyl acetate resin solvent adhesive (for Bond (registered trademark) foamed polystyrene manufactured by Konishi Co., Ltd.), respectively. A foamed molded product was obtained.

The obtained foamed molded article did not shrink and had good fusion properties. Further, the obtained foamed molded article had a thermal conductivity of 0.0330 W / m · K and a low thermal conductivity. Moreover, the lightness L ^* of the main surface (namely, foam molded member A) of the obtained foam molded article is 95.0, and the obtained foam molded article is not easily deformed by light and has good light resistance. Met.

[Comparative Example 1]
Polystyrene resin (made by Toyo Styrene Co., Ltd., trade name “Toyostyrene (registered trademark) HRM10N) 94.6% by weight and graphite powder (made by Nippon Graphite Industry Co., Ltd., trade name“ F # 3 ”) 5.4% by weight Styrene containing 50% by weight of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) (Daiichi Kogyo Seiyaku Co., Ltd.) as a flame retardant with respect to 100 parts by weight of the composition containing 7 parts by mass of resin master batch (corresponding to 3.5 parts by weight of flame retardant) was uniformly mixed with a tumbler mixer. This mixture was supplied to a single screw extruder having a diameter of 90 mm (L / D = 35) at a rate of 150 kg per hour. After the maximum temperature in the extruder was set to 220 ° C. and the composition was melted, 6 parts by weight of isopentane as a volatile blowing agent (with a vapor pressure at 170 ° C. of 100 parts by weight) was used. 2.44 MPa) was pressed from the middle of the extruder to obtain a resin composition.

  Then, while kneading the resin composition in the extruder, the diverter (the connection between the extruder and the die) held at 185 ° C. while cooling the resin composition at 180 ° C. at the tip of the extruder. Part), a die for granulating the resin composition (8 nozzles) having 25 nozzles with a diameter of 0.6 mm and a land length of 3.0 mm arranged on the circumference of the resin discharge surface ). The transported resin composition is extruded into a chamber in which cooling water having a water temperature of 40 ° C. and a water pressure of 1.2 MPa circulates, and at the same time, a high-speed rotary cutter (10 blades in the circumferential direction) closely attached to the die. And a high-speed rotating cutter that rotates 3000 rpm. The cut resin composition was dehydrated and dried, and left in a constant temperature room at 15 ° C. for 3 days to obtain spherical expandable particles.

  Except for using the obtained spherical expandable particles, a foamed molded article was obtained through the same pre-expanded particle production process and molding process as in Example 1.

The obtained foamed molded article was inferior in fusion property. Further, the obtained foamed molded article had a thermal conductivity of 0.0318 W / m · K and a low thermal conductivity. Moreover, the lightness L ^* of the main surface (namely, foam molded member A) of the obtained foam molded article is 65.3, and the obtained foam molded article is easily deformed by light and has poor light resistance. there were.

[Comparative Example 2]
Instead of using graphite powder (made by Nippon Graphite Industry Co., Ltd., trade name “F # 3”), scaly graphite having an average particle diameter of 5 μm (made by Nippon Graphite Co., Ltd., trade name “J-CPB”). In the same manner as in Comparative Example 1, to obtain a foam molded article.

The obtained foamed molded article was inferior in fusion property. Further, the obtained foamed molded article had a thermal conductivity of 0.0310 W / m · K and a low thermal conductivity. Moreover, the lightness L ^* of the main surface (namely, foam molding member A) of the obtained foam molded article is 53.8, and the obtained foam molded article is easily deformed by light and has poor light resistance. there were.

[Comparative Example 3]
A foam molded article was obtained in the same manner as in Example 1 except that graphite was not used in the seed particle production process.

The obtained foamed molded article did not shrink and had good fusion properties. Further, the obtained foamed molded article had a thermal conductivity of 0.0362 W / m · K and a high thermal conductivity. Further, the lightness L ^* of the main surface of the obtained foamed molded product was 94.4, and the obtained foamed molded product was hardly deformed by light and had good light resistance.

[Comparative Example 4]
In the seed particle production process, the amount of styrene resin having a weight average molecular weight of 180,000 is 9600 g, and the average particle diameter is 70 μm. Scalar graphite (trade name “F # 3” manufactured by Nippon Graphite Industries Co., Ltd.) A foamed molded article was obtained in the same manner as in Example 1 except that the amount used was 400 g.

The obtained foamed molded article was inferior in fusion property. Further, the obtained foamed molded article had a thermal conductivity of 0.0348 W / m · K and a high thermal conductivity. Further, the lightness L ^* of the main surface of the obtained foamed molded product was 88.2, and the obtained foamed molded product was hardly deformed by light and had good light resistance.

About the foam molded articles of Examples 1 to 6 and Comparative Examples 1 to 4, the shape and average particle diameter of graphite used for production, the average particle diameter of graphite in the surface layer part, the content of graphite in the foam molded article, the surface layer part Table 1 summarizes the graphite content, thermal conductivity, lightness L ^{* of the} main surface, fusion rate, fusion property, and flame retardancy.

表１より、実施例１〜６に係る発泡成形体の熱伝導率は、０．０２８０〜０．０３４０Ｗ／ｍ・Ｋ（具体的には、０．０２９４〜０．０３３０Ｗ／ｍ・Ｋ）の範囲内にあり、比較例３及び４の発泡成形体と比べて、断熱性に優れることが認められた。加えて、実施例１〜６に係る発泡成形体の主表面の明度Ｌ^*は７０以上であり、実施例１〜６に係る発泡成形体は、主表面の明度Ｌ^*が７０未満である比較例１及び２の発泡成形体と比べて、耐光性に優れることが認められた。つまり、実施例１〜６に係る発泡成形体は、断熱性と耐光性の両方に優れることが認められた。

From Table 1, the thermal conductivity of the foam molded articles according to Examples 1 to 6 is 0.0280 to 0.0340 W / m · K (specifically, 0.0294 to 0.0330 W / m · K). It was in the range, and it was recognized that the heat insulating properties were excellent as compared with the foamed molded products of Comparative Examples 3 and 4. In addition, the lightness L ^* of the main surface of the foamed molded products according to Examples 1 to 6 is 70 or more, and the foamed molded products according to Examples 1 to 6 are comparative in which the lightness L ^{* of the} main surface is less than 70. Compared to the foamed molded products of Examples 1 and 2, it was confirmed that the light resistance was excellent. That is, it was recognized that the foamed molded products according to Examples 1 to 6 are excellent in both heat insulation and light resistance.

  Moreover, it was recognized that the foaming molding which concerns on Examples 1-6 shows a favorable meltability and a flame retardance.

  The foamed molded product of the present invention can be used for a wide range of applications such as a heat insulating material used for a heat insulating container or the like, an automobile member, a heat insulating material for a house, a heat insulating panel for a refrigerator.

DESCRIPTION OF SYMBOLS 1 Foam molded object 11 Main surface 2 Foamed particle 21 Surface layer part 3, 3 'Foam molded object 31 Main surface 4 2nd foam member 41 2nd foam particle 5 1st foam member 51 1st foam particle

Claims (4)

A foamed molded article containing a styrene resin,
CIE 1976 brightness L ^* represented by L ^* a ^* b ^* color system has a main surface of 70 or more,
Graphite is contained at least in the other part inside the foamed molded product than the surface layer part, and the surface layer part contains graphite,
When the graphite content in the foamed molded product is X wt% and the graphite content in the surface layer portion is Y wt%, the relational expression of X = 3 to 10 and X ≧ 1.1 × Y is satisfied. ,
A foamed molded product having a thermal conductivity of 0.0340 W / m · K or less. The foam molded article according to claim 1,
A foamed molded product comprising graphite having an average particle size of 30 to 100 μm in the surface layer portion. It is a foaming molding according to claim 1 or 2 ,
A plurality of expanded particles containing the styrenic resin and the graphite are fused,
Each of the plurality of expanded particles has a main surface having a CIE 1976 brightness L * expressed by L ^* a ^* b ^* color system of 70 or more. A method for producing a foam molded article,
A first step of producing expandable particles by impregnating styrene resin particles with a foaming agent;
A second step of producing pre-expanded particles by foaming the expandable particles;
The pre-expanded particles are subjected to in-mold foam molding, and have a main surface having a CIE 1976 lightness L ^* expressed by L ^* a ^* b ^* color system of 70 or more, and a heat conduction of 0.0340 W / m · K or less. A third step of obtaining a foamed molded article having a rate,
In the first step, as the styrenic resin particles,
Resin particles containing styrenic resin and graphite,
When the graphite content in the resin particles is X wt% and the graphite content in the surface layer of the resin particles is Y wt%, the relationship of X = 3 to 10 and X ≧ 1.1 × Y is satisfied. A method for producing a foamed molded article, comprising using resin particles.

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