JP2012229276A - Extruded styrene resin foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extruded styrene resin foam which is excellent in thermal insulating properties and environmental compatibility.SOLUTION: The extruded styrene resin foam is obtained by extrusion foaming of a styrene resin composition prepared by melt-kneading a styrene resin and a halogen-free foaming agent, wherein (i) the styrene resin contains a multibranched polystyrene alone or together with linear polystyrene, the weight ratio of multibranched polystyrene/linear polystyrene being 100/0 to 5/95, and (ii) at least a 3-5C saturated hydrocarbon is contained as the halogen-free foaming agent.

Description

  The present invention relates to a styrene resin extruded foam excellent in heat insulation and environmental compatibility, and a method for producing the same.

  Styrenic resin extruded foam is used as, for example, a heat insulating material for a structure because of good workability and heat insulating properties. As a method for producing a styrene resin extruded foam, a styrene resin composition is heated and melted using an extruder or the like, then a foaming agent is added and cooled to a predetermined resin temperature, and this is extruded into a low pressure region. Thus, extrusion foaming for continuously producing a styrene resin extruded foam is used.

  Fluorocarbons and hydrocarbons are known as foaming agents used in the aforementioned extrusion foam molding. Examples of the chlorofluorocarbons include chlorofluorocarbons containing chlorine atoms (hereinafter also referred to as “CFC”). CFCs have been used to contribute to the development of excellent heat insulation properties because they form good foams and tend to remain in the foams and have low thermal conductivity.

However, since CFC is a causative substance that destroys the ozone layer, an attempt has been made to use a blowing agent instead of CFC. As an alternative to CFC, for example, hydrochlorofluorocarbon (hereinafter also referred to as “HCFC”) and hydrofluorocarbon (hereinafter also referred to as “HFC”) have been proposed. However, chlorofluorocarbons such as HFC and HCFC have a smaller impact on the ozone layer than CFC, but on the other hand they still have a significant impact on global warming. Therefore, it is desired to reduce the amount of HCFC and HFC used.
Patent Document 1 discloses a blowing agent in which isobutane and normal butane are combined. Isobutane and normal butane have low permeability to styrenic resins, zero ozone depletion coefficient, and low global warming coefficient. Therefore, styrene resin extruded foams using these as foaming agents are excellent in environmental compatibility.

  However, since hydrocarbons such as isobutane and normal butane have higher thermal conductivity than CFC and HCFC, there is a problem that the heat insulating property of the foam is lowered. In Patent Document 2, in order to solve the above problems, small bubbles and large bubbles are mixed in a sea-island shape by using water as a foaming agent and adjusting the type of additive, extrusion foaming molding conditions, and the like. A technique for obtaining a foam having a characteristic cell structure is disclosed. Thereby, even if hydrocarbon was used as the foaming agent, a foam having excellent heat insulating properties, light weight, and good extrusion foam moldability was obtained.

  However, in the method for producing a foam having a characteristic cell structure in which small bubbles and large cells are mixed in a sea-island shape, extrusion conditions such as resin temperature and resin pressure at the time of foaming to express the cell structure There was room for improvement in the narrow and stable manufacturing. In particular, when the styrene resin composition once foamed is pelletized again and used as a raw material for the extruded foam, the fluctuation of the extrusion conditions due to the resin deterioration due to re-pelletization is large, and stable production is concerned. There was room for improvement.

Patent Document 3 discloses a method for producing a low-density closed-cell polymer foam by using a non-linear styrene polymer as a raw material resin and mainly using carbon dioxide as a foaming agent. However, carbon dioxide has a high permeability coefficient against polystyrene, and after manufacturing the foam, it quickly dissipates out of the foam. As a result, the foam shrinks and it is difficult to obtain a low-density foam.
JP-A-1-174540 Japanese Patent Laid-Open No. 2001-200087 JP 2005-330491 A

  Under such circumstances, the problem to be solved by the present invention is to stably obtain a styrene resin extruded foam having excellent heat insulation performance and excellent environmental compatibility.

  In order to solve the above problems, the present inventors have conducted extensive research, and as a raw material resin, a multi-branched polystyrene alone or a material containing multi-branched polystyrene and linear polystyrene is used, By using at least one of water and one of saturated hydrocarbons having 3 to 5 carbon atoms as a foaming agent, it has been found that a foam having a light weight and excellent appearance can be stably obtained, and the present invention has been completed. It was.

That is,
[1] The present invention is a styrene resin extruded foam obtained by extrusion foaming a styrene resin composition obtained by melt-kneading a styrene resin and a non-halogen foaming agent,
(I) The styrene-based resin is a multi-branched polystyrene alone or containing a multi-branched polystyrene and a linear polystyrene, and the weight ratio of the multi-branched polystyrene / the linear polystyrene is 100/0. 5/95,
(Ii) A styrene resin extruded foam that contains at least one kind of saturated hydrocarbon having 3 to 5 carbon atoms and water as the non-halogen foaming agent.
[2] It is preferable that the multi-branched polystyrene is a polymer of a multi-branched macromonomer having a branched structure having a repeating unit selected from an ester bond, an ether bond, and an amide bond and a styrene monomer. .
[3] A styrene resin composition obtained by re-pelletizing a foam obtained by melting and kneading the virgin resin and a foaming agent and extrusion-foaming the styrene resin having a weight average molecular weight of MW1. When the weight average molecular weight of MW2 is MW2, those satisfying the following formula (1) are preferable.
Formula (1): 0.8 ≦ MW2 / MW1 ≦ 1.0
[4] It is preferable that the saturated hydrocarbon further contains at least one selected from the group consisting of propane, n-butane and i-butane.
[5] Examples of the non-halogen foaming agent further include ether.
[6] The bubbles forming the styrene resin extruded foam are mainly composed of bubbles having a bubble diameter of 0.20 mm or less and bubbles having a bubble diameter of 0.20 to 1.0 mm. It is preferable to have an occupied area of 10 to 90% per foam cross-sectional area.
[7] It is preferable that the thermal conductivity of the styrene resin extruded foam is 0.040 W / mK or less.
[8] It is preferable that the thermal conductivity of the styrene resin extruded foam is 0.028 W / mK or less.
[9] It is preferable that the foam density of the styrene resin extruded foam is 20 to 60 kg / m 3.
[10] It is preferable that the styrene resin extruded foam has a thickness of 10 to 150 mm.
[11] The method for producing a styrene resin foam is a method for producing a styrene resin foam in which a styrene resin is heated and melted, a foaming agent is added to the styrene resin, and extrusion foaming is performed in a low pressure region. ,
(I) The styrene-based resin is a multi-branched polystyrene alone or containing a multi-branched polystyrene and a linear polystyrene, and the weight ratio of the multi-branched polystyrene / the linear polystyrene is 100/0. 5/95,
(Ii) A method for producing a styrene-based resin foam, wherein the non-halogen-based foaming agent contains at least water and a saturated hydrocarbon having 3 to 5 carbon atoms.

  ADVANTAGE OF THE INVENTION According to this invention, the styrene-type resin extrusion foam which has the outstanding heat insulation and was excellent also in environmental compatibility, and its manufacturing method are provided. The styrenic resin foam of the present invention is useful for various uses, in particular, for a building heat insulating material and a heat insulating material for a cold storage car / cooled vehicle, because of its excellent heat insulating property.

  The styrene resin used in the present invention is not particularly limited, and examples thereof include styrene monomers such as styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, bromo styrene, chloro styrene, vinyl toluene, and vinyl xylene. Homopolymers of the above or a combination of two or more monomers, styrene monomers and divinylbenzene, butadiene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, anhydrous Examples thereof include copolymers obtained by copolymerizing one or more monomers such as maleic acid and itaconic anhydride. Monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, maleic anhydride, and itaconic anhydride to be copolymerized with styrenic monomers are the compression strength of the styrene resin extrusion foam produced The amount can be used so as not to deteriorate the physical properties.

  The styrenic resin used in the present invention is not limited to the homopolymer or copolymer of the styrenic monomer, but the homopolymer or copolymer of the styrenic monomer and the other monomer. It may be a blend with a homopolymer or a copolymer of diene rubber reinforced polystyrene or acrylic rubber reinforced polystyrene.

  In the present invention, among the styrene resins, a polystyrene resin can be particularly preferably used from the viewpoint of economy and workability. Further, when high heat resistance is required for the extruded foam, it is preferable to use a styrene-acrylonitrile copolymer, (meth) acrylic acid copolymer polystyrene, or maleic anhydride-modified polystyrene. Moreover, when high impact resistance is calculated | required by an extrusion foam, it is preferable to use rubber reinforced polystyrene. These styrenic resins may be used alone, or two or more different styrenic resins such as copolymerization component, molecular weight and molecular weight distribution, branched structure, and MFR may be mixed and used.

As the styrenic resin in the present invention, one having an MFR of 0.1 to 50 g / 10 min at 200 ° C. is excellent in molding processability at the time of extrusion foam molding, and the discharge amount at the molding process is obtained. It is easy to adjust the thickness, width, density, or closed cell ratio of the thermoplastic resin foam to the desired value, and foamability (foam thickness, width, density, closed cell ratio, surface properties, etc. is adjusted to the desired situation. The easier it is to foam, the better the foamability), and the appearance of a thermoplastic resin foam with excellent appearance, etc., as well as heat that balances mechanical strength such as compressive strength, bending strength or bending deflection, and properties such as toughness. This is preferable from the viewpoint of obtaining a plastic resin foam. Further, the MFR of the styrenic resin is more preferably from 0.3 to 30 g / 10 minutes, more preferably from 0.5 to 20 g / 10 minutes, from the viewpoint of the balance of molding processability and mechanical strength with respect to foamability, toughness and the like. preferable.
In addition, MFR in this invention is measured by A method and test condition H of JISK7210 (1999).

As the styrenic resin used in the present invention, a multi-branched polystyrene alone or one containing multi-branched polystyrene and linear polystyrene is used, and the weight ratio of the multi-branched polystyrene / linear polystyrene is 100 / What is 0-5 / 95 is used.
By using the styrenic resin, the extrusion operability and foam molding processability are stable, and a foam having a characteristic cell structure in which large cells and small cells are mixed can be stably obtained. Further, by mixing two or more kinds of resins, MW2 / MW1 described later can be adjusted to be within the scope of the present invention.

  In the present invention, the weight ratio of the hyperbranched polystyrene to the linear polystyrene is preferably 100/0 to 5/95, more preferably 90/10 to 10/90, as the ratio of the hyperbranched polystyrene / linear polystyrene. 80 / 20-20 / 80 is more preferable. By setting the weight ratio of the multi-branched polystyrene and the linear polystyrene within the above range, the extrusion operability and foam molding processability are stabilized, and a foam having a characteristic cell structure in which large cells and small cells are mixed is obtained. It can be obtained stably.

  The hyperbranched polystyrene in the present invention is obtained by copolymerizing a styrene monomer with a hyperbranched macromonomer, obtained by irradiating a polystyrene resin with an electron beam, a radical polymerization initiator on a polystyrene resin. And those obtained by adding a radical polymerizable monomer and melt-kneading. Among these, those obtained by copolymerizing a multi-branched macromonomer with a styrenic monomer are preferable from the viewpoint of easily obtaining a plurality of branches.

  The branched structure of the multi-branched polystyrene contained in the styrene resin composition of the present invention is not particularly limited, but all three bonds other than the electron-withdrawing group and the bond that is bonded to the electron-withdrawing group are carbon atoms. Those having a branched structure consisting of a saturated carbon atom bonded to, and those containing a branched structure consisting of a repeating structural unit selected from an ether bond, an ester bond and an amide bond are preferred.

The multi-branched macromonomer used in the present invention is not particularly limited except that it is a monomer having a multi-branched chain. As one of the preferred ones, an electron-withdrawing group in one molecule and the electron Multi-branched macromonomer containing a branched structure consisting of a saturated carbon atom in which all three bonds other than the bond bonding to the attractive group are bonded to a carbon atom, and a double bond directly bonded to the aromatic ring Can be given. This hyperbranched macromonomer is a hyperbranched macromonomer derived from AB type ₂ monomer.

  Other preferable examples of the multi-branched macromonomer used in the present invention include a branched structure composed of repeating structural units selected from an ester bond, an ether bond and an amide bond, and an ethylenic double bond at the branch end. And a multi-branched macromonomer.

  The linear polystyrene in this invention is a polystyrene comprised from the monomer unit which does not have a branched structure.

  The weight average molecular weight (Mw) of the styrenic resin in the present invention is preferably 75,000 to 600,000, more preferably 100,000 to 500,000, and further preferably 150,000 to 400,000.

  In the present invention, the weight average molecular weight Mw is determined by, for example, a so-called gel permeation chromatography method in which 5 mg of a styrene resin is dissolved in 5 ml of chloroform, and this is passed through a fractionation column to measure the molecular weight. Specifically, the molecular weight is measured using, for example, GPC-LC6AD type manufactured by Shimadzu Corporation and differential refractometer detector RID-10A type manufactured by Shimadzu Corporation, column temperature: room temperature, flow rate: 1.0 ml / min. The value measured at is adopted.

As the styrenic resin used in the present invention, a styrene resin composition obtained by re-pelletizing a foam obtained by melt-kneading the virgin resin and a foaming agent and extrusion-foaming the virgin resin has a weight average molecular weight of MW1. When the weight average molecular weight of MW2 is MW2, it is preferable to use one satisfying the following formula (1).
Formula (1): 0.8 ≦ MW2 / MW1 ≦ 1.0

Here, the styrenic resin composition obtained by re-pelletizing the foam is obtained under the following conditions.
(A) Extrusion foaming conditions: resin temperature 180 to 230 ° C. in the first extruder, resin temperature 110 to 140 ° C. in the second extruder, and discharge amount 600 to 1200 kg / hr.
(B) Re-pelletizing conditions: extruder temperature 160 to 200 ° C., discharge 150 to 300 kg / hr.

  As described above, MW2 / MW1 can be adjusted by adjusting the weight ratio between the multi-branched polystyrene and the linear polystyrene, which are raw material resins.

  In the present invention, by using a virgin resin made of a styrene resin having MW2 / MW1 within the above range, a foam having a characteristic cell structure in which extrusion operability is stabilized and large cells and small cells are mixed. Can be obtained stably.

  The foaming agent used in the present invention is preferably a non-halogen substance containing at least one selected from saturated hydrocarbons having 3 to 5 carbon atoms and water from the viewpoint of environmental compatibility and light weight. is there. Specifically, (b) one or more saturated hydrocarbons selected from saturated hydrocarbons having 3 to 5 carbon atoms, and (b) water, and (c) ether, (d) other What contains a non-halogen foaming agent is used. By using a non-halogen-based foaming agent, the environmental compatibility at the time of extrusion foaming and the obtained extruded foam is improved. In addition to (b) and (b), the thickness, width, density, or closed cell ratio of the resulting styrenic resin extruded foam is obtained by using a combination of the foaming agent (c) (d). It becomes easy to adjust thermal conductivity, bubble diameter, and surface property to desired values. That is, it is excellent in the moldability of the extruded foam.

  Examples of the (a) saturated hydrocarbon having 3 to 5 carbon atoms as the blowing agent include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, and cyclopentane. Among these, at least one selected from the group consisting of propane, n-butane and i-butane is preferable because of good foamability. Moreover, since the heat insulation of an extrusion foam becomes favorable, the 1 or more types selected from n-butane and i-butane are preferable, and i-butane is especially preferable.

  The amount of the saturated hydrocarbon having 3 to 5 carbon atoms used as the blowing agent is preferably 99 to 20% by weight, more preferably 80 to 30% by weight, and particularly preferably 60 to 60% by weight with respect to 100% by weight of the total amount of the blowing agent. 40% by weight. By making content of a C3-C5 saturated hydrocarbon into the said range, it can be made to make an extruded foam compatible with high heat insulation and a flame retardance. Further, the plasticity is set to an appropriate range, and the styrene resin and the foaming agent are uniformly kneaded in the extruder, and the pressure control of the extruder becomes easy.

  The amount of (b) water used as the foaming agent is preferably 1 to 80% by weight, more preferably 3 to 70% by weight, and particularly preferably 3 to 30% by weight with respect to 100% by weight of the total amount of the foaming agent. %, Most preferably 5 to 20% by weight. By setting the water content in the above range, high heat insulation and moldability are used in combination, and an extruded foam having a good surface can be obtained. By using water as the foaming agent, a cell structure having a plurality of peaks can be obtained in the type, composition, amount of use of the foaming agent, and a bubble diameter distribution diagram to be described later. Thereby, compared with the bubble structure which has a single peak, the styrene resin extrusion foam excellent in heat insulation can be obtained.

  When water is used, it is preferable to add a water-absorbing substance in order to stably perform extrusion foaming. The water-absorbing substance means a compound that absorbs water, absorbs, adsorbs, swells with water, or a compound that reacts with water to form a hydrate. The water-absorbing substance absorbs, adsorbs, or reacts with water having low compatibility with the styrene resin to form a gel, and is uniformly dispersed in the styrene resin in the gel state. It is considered that stable extrusion foaming can be realized without causing any voids or voids.

  Examples of (c) ether as the blowing agent include dimethyl ether, diethyl ether and methyl ethyl ether, isopropyl ether, n-butyl ether, diisoamyl ether, furan, furfural, 2-methyl furan, tetrahydrofuran, tetrahydropyran and the like. Among these, at least one selected from the group consisting of dimethyl ether, diethyl ether, and methyl ethyl ether is preferable because of good foamability.

  The amount of ether used as the blowing agent is preferably 0 to 80% by weight, more preferably 20 to 70% by weight, and particularly preferably 40 to 60% by weight with respect to 100% by weight of the total amount of the blowing agent. By making content of the said compound into the said range, high heat insulation, a flame retardance, and a moldability can be made parallel to an extrusion foam. In addition, other ethers used as a blowing agent in the same manner as the above compound include isopropyl ether, n-butyl ether, diisoamyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, tetrahydropyran and the like.

  Examples of other non-halogen blowing agents include those selected from the group consisting of carbon dioxide and alcohol. By using these as foaming agents, (a) the amount of saturated hydrocarbons having 3 to 5 carbon atoms and (c) the amount of ether used, that is, the use of flammable foaming agents is reduced, and the flame retardant of the obtained foaming agent Is improved.

  When carbon dioxide is used as the other non-halogen-based blowing agent, it is preferably 3 to 40% by weight, more preferably 5 to 30% by weight with respect to 100% by weight of the total amount of the blowing agent. By making the content of carbon dioxide within the above range, the heat insulating property and moldability of the extruded foam are improved, which is preferable.

  In the present invention, other foaming agents may be used. As other foaming agents, specifically, formic acid methyl ester, formic acid ethyl ester, formic acid propyl ester, formic acid butyl ester, formic acid amyl ester, propionic acid methyl ester, carboxylic acid esters such as propionic acid ethyl ester, methanol, Alcohols exemplified by ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol, dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, methyl i -Butyl ketone, methyl n-amyl ketone, methyl n-hexyl ketone, ethyl n-propyl ketone, ketones exemplified by ethyl n-butyl ketone, alkyl halides such as methyl chloride, ethyl chloride, etc. Organic blowing agents, nitrogen, argon, inorganic blowing agents, such as helium, azo compounds, and chemical blowing agents such as tetrazoles.

  The amount of other foaming agent added to the styrene resin extruded foam may be appropriately determined in consideration of heat insulation, foam moldability, and foam density, but it is 0 to 4% by weight with respect to 100% by weight of the total amount of foaming agent. Is preferable, and more preferably 0 to 3% by weight.

  The total amount of the foaming agent for the styrene resin in the present invention is preferably 4.5 to 10 parts by weight with respect to 100 parts by weight of the styrene resin.

  The content of the foaming agent contained in the styrene-based resin extruded foam is the gas extracted by heating a test piece obtained by excising 2 mm or more of the entire surface from the obtained extruded foam in a closed container, or Depending on the type of styrene-based resin, measurement can be performed using gas chromatography using a gas extracted by dissolving in a solvent as a sample.

  Specific examples of the water-absorbing substance used in the present invention include anhydrous silica (silicon oxide) having a silanol group on the surface [for example, AEROSIL manufactured by Nippon Aerosil Co., Ltd. is commercially available] and the like. Fine powder having a hydroxyl group particle size of 1000 nm or less; water-absorbing or water-swelling layered silicates such as smectite, swellable fluorine mica, or organically treated products thereof; zeolite, activated carbon, alumina, silica gel, porous glass, activity Porous materials such as white clay and diatomaceous earth; sulfates such as sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, barium sulfate, aluminum sulfate, zinc sulfate, ammonium sulfate, sodium carbonate, sodium bicarbonate, magnesium carbonate, carbonate Carbonates such as ammonium, sodium phosphate, phosphoric acid Phosphate such as gnesium, aluminum phosphate, ammonium phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, triammonium phosphate, calcium dihydrogen phosphate, calcium hydrogen phosphate, Calcium salt, trisodium citrate, tripotassium citrate, calcium lactate, ammonium oxalate, potassium oxalate, disodium succinate, sodium acetate, sodium pyrophosphate, magnesium chloride, barium chloride and other metal salts, boron oxide, boron Boron compounds such as sodium acid, polyacrylate polymer, starch-acrylic acid graft copolymer, polyvinyl alcohol polymer, vinyl alcohol-acrylate copolymer, ethylene-vinyl alcohol copolymer, Polyacrylonitrile Methyl methacrylate - butadiene copolymer, such as water-absorbing polymers such as polyethylene oxide copolymer and derivatives thereof. The water-absorbing substance may be used alone or in combination of two or more.

  Among the water-absorbing substances described above, water-absorbing or water-swelling layered silicates such as anhydrous silica, polyacrylate polymers, smectites, and swellable fluorine mica, metal sulfates, metal carbonates, and metal phosphates Metallic salts such as salts, porous materials such as zeolite suppress the generation of pores and voids during extrusion foam molding, a characteristic cellular structure with a sea-island structure in which small bubbles and large bubbles are mixed It is more preferable to form a film and to exhibit excellent heat insulation performance.

  The amount of the water-absorbing substance used in the present invention is appropriately adjusted depending on the amount of water added and the like, but is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the composition. -8 parts by weight is more preferable, and 0.2-7 parts by weight is more preferable. When the content of the water-absorbing substance is less than 0.1 parts by weight, the effect of stabilizing the water dispersion by the water-absorbing substance is insufficient, and pores and voids are generated due to poor water dispersion in the extruder, leading to defective foam. There is a case. On the other hand, if the amount exceeds 10 parts by weight, poor dispersion of the water-absorbing substance in the extruder may occur, resulting in bubble unevenness, which may lead to foam failure, deterioration of the heat insulation performance of the foam, variation in quality, etc. Problems such as enlargement may occur.

  The layered silicate is mainly composed of a tetrahedral sheet of silicon oxide and an octahedral sheet of mainly metal hydroxide. The tetrahedral sheet and the octahedral sheet form a unit layer. A plurality of layers may be laminated through ions or the like to form primary particles, or aggregated particles of primary particles (secondary particles) may be present. Examples of layered silicates include smectite clay and swellable mica.

The smectite group clay is represented by chemical formula (1): X _0.2-0.6 Y _2-3 Z ₄ O ₁₀ (OH) ₂ .nH ₂ O (wherein X is from K, Na, 1 / 2Ca and 1 / 2Mg). Y is one or more selected from the group consisting of Mg, Fe, Mn, Ni, Zn, Li, Al, and Cr, and Z is a group consisting of Si and Al. In addition, H ₂ O represents a water molecule bonded to an interlayer ion, and n is about 0.5 to 10, but n is remarkably dependent on the interlayer ion and relative humidity. Natural or synthetic) represented by, but not limited to: Specific examples of the smectite group clay include, for example, montmorillonite, beidellite, nontronite, saponite, iron saponite, hectorite, soconite, stevensite, bentonite, and the like, substitutions thereof, derivatives thereof, and mixtures thereof.

The swellable mica has the chemical formula (2): X _0.5-1.0 Y _2-3 (Z ₄ O ₁₀ ) (F, OH) ₂ (wherein X is Li, Na, K, Rb, Ca, One or more selected from the group consisting of Ba and Sr, Y is one or more selected from the group consisting of Mg, Fe, Ni, Mn, Al, and Li, and Z is Si, Ge, Al, It is a natural or synthetic material represented by one or more selected from the group consisting of Fe and B. These are water, a polar organic compound that is compatible with water at an arbitrary ratio, and a substance that has a property of swelling in a mixed solvent of water and the polar organic compound. For example, lithium type teniolite, sodium type Examples thereof include teniolite, lithium-type tetrasilicon mica, and sodium-type tetrasilicon mica, or substituted products, derivatives, or mixtures thereof.

Some of the above swellable mica have a structure similar to vermiculites, and such vermiculite equivalents can also be used. The said vermiculite such equivalent has three octahedral type and dioctahedral, chemical formula (3) :( Mg, Fe, Al) 2~3 (Si 4-x Al x) O 10 (OH) 2 · ( M ⁺ , M ²⁺ _1/2 ) _x · nH ₂ O (wherein M is an exchangeable cation of an alkali or alkaline earth metal such as Na and Mg, x = 0.6 to 0.9, n = 3.5-5).

These layered silicates may be used alone or in combination of two or more.
In the layered silicate, smectite clay and swellable mica are preferable from the viewpoint of dispersibility in the obtained foam and stability of extrusion foam molding when water is used, and more preferably montmorillonite, bentonite, hectorite. Smectite group clay such as synthetic smectite, and swellable mica having sodium ions between layers such as swellable fluorine mica.

  Typical examples of bentonite include natural bentonite and purified bentonite. Also, organic bentonite can be used. A representative example of hectorite is synthetic hectorite. Smectites also include montmorillonite-modified products such as anionic polymer-modified montmorillonite, silane-treated montmorillonite, and highly polar organic solvent composite montmorillonite.

  The content of the layered silicate is appropriately adjusted depending on the amount of water added, etc., but is 0.1 to 10 parts by weight, more preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the composition. Part. When the content of the layered silicate is less than 0.1 parts by weight, the amount of water absorbed or adsorbed by the layered silicate is insufficient with respect to the amount of water injected, and pores are generated due to poor dispersion of water. Tends to be difficult to obtain. On the other hand, when the amount exceeds 10 parts by weight, the amount of the inorganic powder present in the styrene resin becomes excessive, so that uniform dispersion in the styrene resin becomes difficult and bubble unevenness tends to occur. Furthermore, it tends to be difficult to maintain closed cells, which tends to cause deterioration and variations in the heat insulating performance of the foam. The mixing ratio (weight ratio) of water and layered silicate is preferably in the range of 0.02 to 20, more preferably 0.1 to 10, particularly preferably 0.15 to 5, most preferably 0.25 to 2. It is.

  The styrene resin extruded foam according to the present invention has a cell structure having a uniform cell diameter, or mainly small bubbles (small bubbles) of 0.20 mm or less and large bubbles (large bubbles) having a bubble diameter of 0.20 to 1.0 mm. It has a characteristic bubble structure in which bubbles are mixed in the shape of sea islands.

  From the viewpoint of heat insulation performance and weight reduction of the extruded foam, a characteristic cell structure in which small bubbles and large cells are mixed in a sea-island shape is preferable. That is, in the case where the extruded foam is made of only bubbles having a regular uniform diameter, it is possible to improve the heat insulation performance to some extent by reducing the bubble diameter. Therefore, more resin is required, and as a result, the density increases, the pressure during extrusion increases, the discharge rate decreases, and the moldability deteriorates. In contrast, the characteristic bubble structure in which small bubbles and large bubbles are mixed in a sea-island shape can improve heat insulation performance due to the presence of small bubbles, and can easily increase the thickness due to the presence of large bubbles. Thus, a low density foam is obtained.

  When the foam having a cellular structure composed of large and small bubbles is used in the present invention, the occupied area ratio of small bubbles per cross-sectional area of the foam is preferably 10 to 90%, more preferably 20 to 90%, still more preferably. 30 to 80%.

In the present invention, the average bubble diameter and the occupied area ratio of small bubbles are defined by the following measurement method.
A predetermined range of the cross section along the extrusion direction of the styrene resin extruded foam is sampled. The cross section along the extrusion direction is a cross section extending in the thickness direction, which is the extrusion direction of the foam. Each predetermined range of this cross section is sampled. The predetermined range to be sampled may be sampled anywhere in the extruded foam except for the special cell structure at the end of the extruded foam, but preferably at the center of the width of each cross section. Sampling is performed at about 3 points at the center of the height and the vertically symmetrical position.
Each sampled material is photographed using a scanning electron microscope (SEM) to obtain an SEM image. The SEM image photographing magnification is set to about 30 to 40 times. The imaging range is, for example, about several mm to several cm in length × width. Each SEM image is processed using an image processing apparatus (for example, PIAS-II, manufactured by Pierce Co., Ltd.) with the thickness direction as the vertical direction and the extrusion direction as the horizontal direction, and the area of individual bubbles in the SEM image (Hereinafter referred to as “bubble area”) (a) is obtained. Moreover, the maximum diameter (Feret diameter) of the vertical direction (thickness direction: Zf) and horizontal direction (extrusion direction: Xf) of each bubble is calculated | required. Note that the measurement of the bubble area and the maximum diameter is for only the bubble in which the entire view of the bubble is projected in the SEM image, and a part of the bubble is missing at the edge of the SEM image or the edge of the SEM image. Even if it is not a part, a part of the bubble wall is missing, or a bubble integrated with an adjacent bubble or the like is excluded. This excluded portion is also excluded from the total measurement area. The number of bubbles to be measured is preferably at least 200. Accordingly, in some cases, 200 or more bubbles can be measured with one SEM image, but in other cases, two or more SEM images may be used.
Assuming that each bubble in the SEM image is elliptical, the thickness direction bubble diameter (Z) and extrusion direction bubble diameter (X) of each bubble are determined according to the following equations (2) and (3).
Formula (2): X = [{(4 × a) / (π × Xf × Zf)} ^1/2 ] × Xf
Formula (3): Z = [{(4 × a) / (π × Xf × Zf)} ^1/2 ] × Zf
The representative bubble diameter (D) of each bubble is obtained by geometrically averaging the obtained bubble diameter Z in the thickness direction of each bubble and the bubble diameter X in the extrusion direction according to Equation (4).
Formula (4): D = (X × Z) ^1/2
The average bubble diameter is obtained by arithmetically averaging the representative bubble diameters of all the bubbles that are the objects of measurement. The small bubble occupation area ratio is obtained according to the equation (5).
Formula (5): Ratio of occupied area of small bubbles (%) = (sum of bubble areas having a representative bubble diameter of 0.20 mm or less / sum of bubble areas) × 100

  In the present invention, for example, a flame retardant may be added to the styrene resin in order to meet the demand in the use of a styrene resin extruded foam such as a building heat insulating material. Examples of the flame retardant include a halogen-based flame retardant, a phosphate ester compound, and a nitrogen-containing compound.

  Specific examples of the halogen flame retardant include (a) tetrabromoethane, tetrabromocyclooctane, hexabromocyclododecane, dibromoethyldibromocyclohexane, dibromodimethylhexane, 2- (bromomethyl) -2- (hydroxymethyl). ) -1,3-propanediol, dibromoneopentyl glycol, tribromoneopentyl alcohol, pentaerythrityl tetrabromide, monobromodipentaerythritol, dibromodipentaerythritol, tribromodipentaerythritol, tetrabromodipentaerythritol, pentabromo Brominated aliphatics such as dipentaerythritol, hexabromodipentaerythritol, hexabromotripentaerythritol, polybrominated polypentaerythritol, etc. Compound or derivative thereof, or brominated alicyclic compound or derivative thereof, (b) hexabromobenzene, pentabromotoluene, ethylenebispentabromodiphenyl, decabromodiphenyl ether, octabromodiphenyl ether, bis (2,4,6- Brominated aromatic compounds such as (tribromophenoxy) ethane, tetrabromophthalic anhydride, octabromotrimethylphenylindane, pentabromobenzyl acrylate, tribromophenyl allyl ether, 2,3-dibromopropyl pentabromophenyl ether or derivatives thereof ( c) Tetrabromobisphenol A, tetrabromobisphenol A diallyl ether, tetrabromobisphenol A dimethallyl ether, tetrabromobisphenol A diglycidyl Ether, tetrabromobisphenol A diglycidyl ether tribromophenol adduct, tetrabromobisphenol A bis (2,3-dibromopropyl ether), tetrabromobisphenol A bis (2-bromoethyl ether), tetrabromobisphenol A bis ( 2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol S bis (2,3-dibromopropyl ether), tetrabromobisphenol S, and the like, and (d) tetrabromobisphenol A Brominated bisphenol derivatives oligomers such as polycarbonate oligomer, tetrabromobisphenol A diglycidyl ether and brominated bisphenol adduct epoxy oligomer, (e) pen tab Brominated acrylic resins such as lomobenzyl acrylate polymer, (f) ethylene bistetrabromophthalimide, ethylene bisdibromonorbornane dicarboximide, 2,4,6-tris (2,4,6-tribromophenoxy) 1,3, Bromine and nitrogen atom-containing compounds such as 5-triazine and tris (2,3-dibromopropyl) isocyanurate, (g) Bromine and phosphorus atom-containing compounds such as tris (tribromoneopentyl) phosphate and tris (bromophenyl) phosphate (H) chlorine-containing compounds such as chlorinated paraffin, chlorinated naphthalene, perchloropentadecane, chlorinated aromatic compounds, chlorinated alicyclic compounds, (i) brominated inorganic compounds such as ammonium bromide, etc. Can be mentioned. These compounds can be used individually or in mixture of 2 or more types. Furthermore, a brominated polystyrene resin which is a kind of styrene resin in the present invention can also be used as a flame retardant.

  Among these, from the viewpoint of flame retardancy, any of hexabromocyclododecane, tetrabromocyclooctane, tetrabromobisphenol A bis (2,3-dibromopropyl ether), and tris (2,3-dibromopropyl) isocyanurate It is more preferable to contain.

  The content of the halogen-based flame retardant in the styrene resin foam is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the styrene resin. However, in order to obtain the flame retardancy specified in JIS A9511 measurement method A, it is appropriately adjusted according to the type or amount of the additive having the foaming agent addition amount, the foam density, and the flame retardant synergistic effect. The amount is preferably 1 to 20 parts by weight, more preferably 1 to 15 parts by weight, and still more preferably 2 to 8 parts by weight with respect to 100 parts by weight of the styrene resin. If the amount of the halogen-based flame retardant is less than 0.1 parts by weight, it is difficult to obtain good properties such as intended flame retardancy as a foam, while if it exceeds 20 parts by weight, In some cases, the heat resistance and surface properties of the foams produced and the stability during the production of the foams may be impaired.

  In the present invention, for the purpose of improving the flame retardancy of the styrene resin foam, a flame retardant aid exhibiting a synergistic effect with the halogen flame retardant described above may be added. Examples of flame retardant aids that have a synergistic effect with such halogen flame retardants include iron-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, sulfur-containing compounds, and the like. A phosphorus compound, a nitrogen-containing compound, a boron-containing compound, a sulfur-containing compound (aromatic sulfonic acid compound), or the like may be used. Among these, from the viewpoint of flame retardancy, iron oxide as the iron-containing compound, triphenyl phosphate and tris (tribromoneopentyl) phosphate as the phosphorus-containing compound, cyanuric acid, isocyanuric acid and their derivatives, boron-containing compounds as the nitrogen-containing compound Most preferred are boron oxide as the sulfur-containing compound and sulfanilic acid as the sulfur-containing compound and derivatives thereof. In addition, as a cyanuric acid derivative and an isocyanuric acid derivative, the thing of Unexamined-Japanese-Patent No. 2002-30174 ([0069] paragraph-[0079] paragraph) can be used, for example. The content of the flame retardant aid having a synergistic effect with such a halogen flame retardant in the styrene resin foam depends on the kind of the flame retardant aid having a synergistic effect with the halogen flame retardant, but the styrene resin 100 0.0001-10 weight part is preferable with respect to weight part.

  In the present invention, various inorganic substances such as silica, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate and the like, as long as they do not inhibit the effects of the present invention. Compounds, processing aids such as sodium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin wax, stearylamide compound, phenolic antioxidant, phosphorus stabilizer, nitrogen stabilizer, sulfur stabilizer It may contain additives such as a light-resistant stabilizer such as an agent, a benzotriazole, a hindered amine, a flame retardant other than the above, an antistatic agent, and a colorant such as a pigment.

  The present styrene resin extruded foam supplies a styrene resin to a melt kneading means, and also supplies an additive containing a nucleating agent and a foaming agent to the melt kneading means and kneads them with the styrene resin. A composition is obtained by extruding and foaming the styrenic resin composition from a high pressure region through a die lip to a low pressure region.

  To adjust the cell diameter and cell structure of the styrene resin extruded foam, water is used as the foaming agent, the type and amount of other foaming agents, the type and amount of water-absorbing substances, and the molding conditions for extrusion foaming. It can be adjusted by. The molding conditions for extrusion foaming include, for example, adjustment of the thickness enlargement ratio when the molten styrene-based resin composition is discharged into the atmosphere, that is, the die lip slit thickness and the height of the molding die for making a rectangle. Adjustment of the height. Moreover, the method of adjusting molding resistance is mentioned.

As a procedure for adding various additives to the styrenic resin, for example, after adding and mixing various additives to the styrenic resin, the mixture is supplied to an extruder, heated and melted, and further added with a foaming agent and mixed. The timing for adding various additives to the styrenic resin and the kneading time are not particularly limited.
The heating temperature of the styrenic resin may be higher than the temperature at which the styrenic resin used melts, but the temperature at which molecular degradation of the resin due to the influence of additives and the like is suppressed as much as possible, for example, about 150 to 260 ° C. Is preferred. The melt-kneading time varies depending on the amount of styrene-based resin extruded per unit time and the type of extruder used as the melt-kneading means, so it cannot be uniquely defined. The styrene-based resin and the blowing agent or additive are uniform. The time required for the dispersion and mixing is appropriately set.
Examples of the melt-kneading means include a screw type extruder, but are not particularly limited as long as they are used for ordinary extrusion foaming. However, in order to suppress the molecular deterioration of the resin as much as possible, the screw shape of the extruder is preferably a low shear type.

  The foam molding method is, for example, a method in which an extruded foam obtained by opening from a high pressure region to a low pressure region through a slit die having a linear slit shape used for extrusion shaping is in close contact with or in contact with the slit die. In other words, a method of forming a plate-like foam having a large cross-sectional area is used, using a molding die placed in the middle and a molding roll placed adjacent to the downstream side of the molding die. By adjusting the flow surface shape of the molding die and the mold temperature, the desired cross-sectional shape of the foam, the surface property of the foam, and the quality of the foam can be obtained.

  When considering that the styrene resin extruded foam according to the present invention functions as, for example, a heat insulating material for buildings, a cold storage or a cold car, the thermal conductivity measured according to JIS A9511 is 0. It is preferably 040 W / mK or less, more preferably 0.034 W / mK or less, and still more preferably 0.028 W / mK or less.

The styrene-based resin extruded foam according to the present invention has a density of the foam from the viewpoint of heat insulation and lightness considering that it functions as, for example, a heat insulating material for buildings, a cold storage or a cold car, and the like. is preferably 25~65kg / ^{m 3,} more preferably from 30~55kg / ^{m 3.}

  The thickness of the styrene-based resin extruded foam according to the present invention is not particularly limited, but for example, heat insulation, bending strength, and compressive strength in consideration of functioning as a heat insulator for a building, a cold storage, or a cold car. From this viewpoint, the thickness is preferably 10 to 150 mm, more preferably 15 to 120 mm, and particularly preferably 20 to 100 mm.

  Thus, according to the present invention, it is possible to easily obtain a styrene resin extruded foam having excellent heat insulation.

  Examples of the present invention will be described below. Needless to say, the present invention is not limited to the following examples. In the following examples and comparative examples, “%” represents “% by weight” unless otherwise specified.

  For Examples 1 to 4 and Comparative Examples 1 to 3, foam density, closed cell ratio, residual foaming agent amount, thermal conductivity, and bubble diameter distribution were evaluated according to the following evaluation methods.

(1) Weight average molecular weight MW of styrene resin
Using a sample obtained by dissolving 5 mg of resin in 5 ml of chloroform, using a gel permeation chromatograph [Shimadzu Corporation, GPC-LC6AD type] and a differential refractometer detector [Shimadzu Corporation, RID-10A type] The weight average molecular weight was measured under the measurement conditions of column temperature: room temperature, flow rate: 1.0 ml / min.

(2) Whole foam density (kg / m ³ )
The obtained styrene-based resin extruded foam was cut into a rectangular parallelepiped shape of 300 mm (extrusion direction) × 100 mm (width direction) × 30 mm (thickness direction) and measured for weight, and using vertical calipers, vertical and horizontal dimensions. The height dimension was measured. From the measured weight and each dimension, the foam density was calculated | required based on the following formula | equation, and the unit was converted into kg / m < ³ >.
Foam overall density (g / cm ³ ) = foam weight (g) / foam volume (cm ³ )

(3) Foam appearance The obtained foam was visually observed and evaluated according to the following criteria.
○: The skin is smooth, there are no voids such as voids and unevenness of bubbles, and shrinkage of the foam is not observed.
X: The skin is not smooth, giant bubbles such as voids or bubble irregularities are observed, and shrinkage of the foam is observed.

(4) Closed cell ratio (%)
Using a multi-pynometer [manufactured by Yuasa Ionics Co., Ltd.], measurement was performed according to ASTM D-2856.

(5) Thermal conductivity (W / mK)
The thermal conductivity of the styrene resin extruded foam 30 days after the production was measured according to JIS A9511.

(6) Average cell diameter and small cell occupation area ratio In the cross section along the extrusion direction of the styrene resin extruded foam, an SEM image was obtained by the method described above. The average bubble diameter and small bubble occupation area ratio in the obtained SEM image were determined according to the method described above.

Example 1
[Method for producing extruded foam]
As the styrene resin (virgin resin), multi-branched polystyrene [manufactured by DIC Corporation, trade name: HP-500M, MFR = 2.5 g / 10 min] is used, and the halogen-based resin is used for 100 parts by weight of the resin Hexabromocyclododecane [trade name: SAYTEX HP-900] 4.0 parts by weight as a flame retardant, Tris (tributyl neopentyl) phosphate [Daihachi Chemical Industry Co., Ltd., trade name: CR-900 ] 1 part by weight, talc [manufactured by Hayashi Kasei Co., Ltd., trade name: Talcan powder] 0.2 parts by weight, barium stearate [manufactured by Sakai Chemical Industry Co., Ltd., trade name: barium stearate] 0.5 parts by weight Bentonite [manufactured by Hojun Co., Ltd., trade name: Bengel 23] 1 part by weight, hydrous amorphous silicon dioxide [DSL Japan Co., Ltd., trade name: Carplex] 0.1 part by weight, epoxy resin [Asahi Denka Kogyo Co., Ltd., trade name: EP-13] 0.2 part by weight, stabilizer [Ciba Specialty Chemicals Co., Ltd., trade name: IRGANOX 245FF, chemical name : A mixture of 0.2 parts by weight of ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate]] was dry blended to obtain a styrenic resin composition. .
The styrenic resin composition was fed into a two-stage extruder in which a first extruder (single screw extruder having a diameter of 90 mm) and a second extruder (single screw extruder having a diameter of 65 mm) were connected in series at 50 kg / hour. The styrene resin composition supplied to the first extruder was heated to about 200 ° C. and kneaded, and as a foaming agent near the tip of the first extruder (side connected to the second extruder). , 0.7 parts by weight of water [tap water], 3.5 parts by weight of i-butane [manufactured by Mitsui Chemicals, Inc.], 2 parts by weight of dimethyl ether [manufactured by Mitsui Chemicals, Inc.] with respect to 100 parts by weight of polystyrene resin The composition of the foaming agent used was 11% water, 57% i-butane, and 32% dimethyl ether based on the total amount of the foaming agent. The resin pressure at the tip of the extruder is 8-20 MPa. In contrast, the press-fitting pressure of the blowing agent was set to +0.5 to 3 MPa.In the second extruder and the cooler connected to the first extruder, the resin temperature was cooled to about 120 ° C. From the die lip provided at the tip, the styrene resin composition was extruded into the atmosphere to obtain an extruded foam (virgin resin foam) having a thickness of about 25 to 40 mm and a width of about 200 mm.
[Re-pelletization]
Next, the obtained extruded virgin resin foam was pulverized and supplied to a single-stage extruder (single screw extruder having a diameter of 120 mm) at about 200 kg / hour. The mixture is heated and kneaded at about 180 ° C. in the extruder, the foaming agent is removed, the styrenic resin composition is extruded from a die lip provided at the tip of the extruder into a water bath at about 50 ° C., re-pelletized by a pelletizer, and recycled pellets (MW2 = 3.6 × 10 ⁵ ).
[Manufacture of extruded foam using recycled pellets]
Using the obtained recycled pellets, the same amount of additive and foaming agent were added in the same manner as in the case of virgin resin to obtain an extruded foam (regenerated pellet resin foam).
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 3.8 × 10 ⁵ , and the weight average molecular weight MW2 of the re-pellet resin was 3.6 × 10 ⁵ . Therefore, the ratio of weight average molecular weight MW2 / MW1 was 0.95.
The density of the obtained extruded virgin resin foam was 33 kg / m ³ and the closed cell ratio was 97%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 45%, the average bubble diameter was 0.24 mm, and the thermal conductivity measured according to JIS A9511 was 0.027 W / mK.
The density of the obtained re-pellet resin extruded foam was 32 kg / m ³ and the closed cell ratio was 95%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 45%, the average bubble diameter was 0.22 mm, and the thermal conductivity measured according to JIS A9511 was 0.028 W / mK.

(Example 2)
As the styrene resin (virgin resin), multi-branched polystyrene and linear polystyrene [manufactured by PS Japan Co., Ltd., trade name: G9401, MFR = 2.5 g / 10 min] are used, and multi-branched polystyrene / linear A virgin resin extruded foam and a recycled pellet resin extruded foam were obtained in the same manner as in Example 1 except that polystyrene was mixed at a ratio of 70/30%.
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 3.9 × 10 ⁵ , and the weight average molecular weight MW2 of the recycled pellet resin was 3.52 × 10 ⁵ . Therefore, the weight average molecular weight ratio MW2 / MW1 was 0.90.
The density of the obtained extruded virgin resin foam was 34 kg / m ³ and the closed cell ratio was 96%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 46%, the average bubble diameter was 0.22 mm, and the thermal conductivity measured according to JIS A9511 was 0.026 W / mK.
Moreover, the density of the obtained recycled pellet resin extruded foam was 33 kg / m ³ and the closed cell ratio was 94%. The evaluation of the appearance of the foam was “◯”. The small cell area ratio of the foam was 43%, the average cell diameter was 0.23 mm, and the thermal conductivity measured according to JIS A9511 was 0.027 W / mK.

(Example 3)
The same as Example 1 except that multi-branched polystyrene and linear polystyrene were used as the styrenic resin (virgin resin), and the multi-branched polystyrene / linear polystyrene was mixed and used at a ratio of 50/50%. Thus, a virgin resin extruded foam and a recycled pellet resin extruded foam were obtained.
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 4.0 × 10 ⁵ , and the weight average molecular weight MW2 of the recycled pellet resin was 3.6 × 10 ⁵ . Therefore, the ratio MW2 / MW1 of the weight average molecular weight was 0.90.
The density of the obtained extruded virgin resin foam was 32 kg / m ³ and the closed cell ratio was 95%. The evaluation of the appearance of the foam was “◯”. The small cell area ratio of the foam was 42%, the average cell diameter was 0.23 mm, and the thermal conductivity measured according to JIS A9511 was 0.027 W / mK.
Moreover, the density of the obtained recycled pellet resin extruded foam was 32 kg / m ³ and the closed cell ratio was 95%. The evaluation of the appearance of the foam was “◯”. The small cell area ratio of the foam was 42%, the average cell diameter was 0.23 mm, and the thermal conductivity measured according to JIS A9511 was 0.027 W / mK.

Example 4
The same as Example 1 except that multi-branched polystyrene and linear polystyrene are used as the styrenic resin (virgin resin), and the multi-branched polystyrene / linear polystyrene is mixed at a ratio of 30/70%. Thus, a virgin resin extruded foam and a recycled pellet resin extruded foam were obtained.
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 4.1 × 10 ⁵ , and the weight average molecular weight MW2 of the recycled pellet resin was 3.5 × 10 ⁵ . Therefore, the ratio MW2 / MW1 of the weight average molecular weight was 0.85.
The density of the obtained extruded virgin resin foam was 33 kg / m ³ and the closed cell ratio was 92%. The evaluation of the appearance of the foam was “◯”. The small cell area ratio of the foam was 43%, the average cell diameter was 0.21 mm, and the thermal conductivity measured according to JIS A9511 was 0.028 W / mK.
The density of the obtained extruded pellet resin extruded foam was 32 kg / m ³ and the closed cell ratio was 92%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 40%, the average bubble diameter was 0.22 mm, and the thermal conductivity measured according to JIS A9511 was 0.028 W / mK.

(Example 5)
The same as Example 1 except that multi-branched polystyrene and linear polystyrene were used as the styrene resin (virgin resin), and the multi-branched polystyrene / linear polystyrene was mixed at a ratio of 10/90%. Thus, a virgin resin extruded foam and a recycled pellet resin extruded foam were obtained.
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 4.3 × 10 ⁵ , and the weight average molecular weight MW2 of the recycled pellet resin was 3.5 × 10 ⁵ . Therefore, the ratio MW1 / MW2 of the weight average molecular weight was 0.81.
The density of the obtained extruded virgin resin foam was 31 kg / m ³ and the closed cell ratio was 98%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 41%, the average bubble diameter was 0.23 mm, and the thermal conductivity measured according to JIS A9511 was 0.027 W / mK.
Moreover, the density of the obtained recycled pellet resin extruded foam was 30 kg / m ³ , and the closed cell ratio was 95%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 36%, the average bubble diameter was 0.23 mm, and the thermal conductivity measured according to JIS A9511 was 0.028 W / mK.

(Example 6)
Add 4.5 parts by weight of hexabromocyclododecane as a flame retardant, add 0.5 parts by weight of bentonite as other additives, and add tris (tributylneopentyl) phosphate and hydrous amorphous silicon dioxide Without blowing, 0.8 parts by weight of water, 1.0 part by weight of isobutane, 2.6 parts by weight of normal butane, and 3 parts by weight of dimethyl ether were press-fitted as a foaming agent. Except for water 11 weight%, isobutane 14 weight%, normal butane 35 weight%, dimethyl ether weight 40%), virgin resin extruded foam and recycled pellet resin extruded foam are the same as in Example 1. Got the body.
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the virgin resin had a weight average molecular weight of 3.8 × 10 ⁵ , and the recycled pellet resin had a weight average molecular weight of 3.3.6 × 10 ⁵ . Therefore, the ratio of weight average molecular weight was 0.95.
The density of the obtained extruded virgin resin foam was 26 kg / m ³ and the closed cell ratio was 92%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 10%, the average bubble diameter was 0.36 mm, and the thermal conductivity measured according to JIS A9511 was 0.031 W / mK.
Moreover, the density of the obtained recycled pellet resin extruded foam was 26 kg / m ³ and the closed cell ratio was 90%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 10%, the average bubble diameter was 0.40 mm, and the thermal conductivity measured according to JIS A9511 was 0.031 W / mK.

(Example 7)
Implemented except that multi-branched polystyrene and linear polystyrene were used as the styrene resin (virgin resin), and the multi-branched polystyrene / linear polystyrene was mixed at a ratio of 50/50% and used as the raw material resin. Virgin resin extruded foam and recycled pellet resin extruded foam were obtained in the same manner as in Example 6.
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 4.0 × 10 ⁵ , and the weight average molecular weight MW2 of the re-pellet resin was 3.5 × 10 ⁵ . Therefore, the ratio MW1 / MW2 of the weight average molecular weight was 0.88.
The density of the obtained extruded virgin resin foam was 27 kg / m ³ and the closed cell ratio was 91%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 10%, the average bubble diameter was 0.35 mm, and the thermal conductivity measured according to JIS A9511 was 0.030 W / mK.
Further, the density of the obtained re-pellet resin extruded foam was 26 kg / m ³ and the closed cell ratio was 90%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 10%, the average bubble diameter was 0.38 mm, and the thermal conductivity measured according to JIS A9511 was 0.031 W / mK.

(Example 8)
2.5 parts by weight of hexabromocyclododecane is added as a flame retardant, 0.5 parts by weight of bentonite is added as an additive, and talc, tris (tributylneopentyl) phosphate and water-containing amorphous silicon dioxide are not added. And 0.6 parts by weight of isobutane, 1.4 parts by weight of normal butane, 3 parts by weight of dimethyl ether, and 2 parts by weight of carbon dioxide [manufactured by Showa Carbon Co., Ltd.] as a foaming agent (note that the composition of the foaming agent used was Except for isobutane 8.5% by weight, normal butane 20% by weight, dimethyl ether 43.9% by weight and carbon dioxide 28.6% by weight, the total amount is 100% by weight. Foam and recycled pellet resin extruded foam were obtained.
Table 1 shows the evaluation results of the raw resin and the extruded foam. As shown in Table 1, the virgin resin had a weight average molecular weight of 3.8 × 10 ⁵ , and the recycled pellet resin had a weight average molecular weight of 3.6 × 10 ⁵ . Therefore, the ratio of weight average molecular weight was 0.89.
The density of the obtained extruded virgin resin foam was 28 kg / m ³ and the closed cell ratio was 91%. The evaluation of the appearance of the foam was “◯”. Further, the foam has a structure having a single bubble diameter, the small bubble area ratio is 100%, the average bubble diameter is 0.18 mm, and the thermal conductivity measured in accordance with JIS A9511 is 0.032 W / mK. Met.
Further, the density of the obtained recycled pellet resin extruded foam was 27 kg / m ³ and the closed cell ratio was 95%. The evaluation of the appearance of the foam was “◯”. The foam has a structure having a single bubble diameter, the small bubble area ratio is 100%, the average bubble diameter is 0.20 mm, and the thermal conductivity measured in accordance with JIS A9511 is 0.033 W / mK. Met.

Example 9
Implemented except that multi-branched polystyrene and linear polystyrene were used as the styrene resin (virgin resin), and the multi-branched polystyrene / linear polystyrene was mixed at a ratio of 50/50% and used as the raw material resin. Virgin resin extruded foam and recycled pellet resin extruded foam were obtained in the same manner as in Example 8.
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 4.0 × 10 ⁵ , and the weight average molecular weight MW2 of the recycled pellet resin was 3.5 × 10 ⁵ . Therefore, the ratio MW1 / MW2 of the weight average molecular weight was 0.88.
The density of the obtained extruded virgin resin foam was 29 kg / m ³ and the closed cell ratio was 91%. The evaluation of the appearance of the foam was “◯”. In addition, the foam has a structure having a single bubble diameter, the small bubble area ratio is 100%, the average bubble diameter is 0.17 mm, and the thermal conductivity measured according to JIS A9511 is 0.032 W / mK. Met.
Moreover, the density of the obtained recycled pellet resin extruded foam was 28 kg / m ³ and the closed cell ratio was 88%. The evaluation of the appearance of the foam was “◯”. In addition, the foam has a single cell diameter, the small cell area ratio is 100%, the average cell size is 0.19 mm, and the thermal conductivity measured according to JIS A9511 is 0.033 W / mK. Met.

(Comparative Example 1)
A virgin resin extruded foam and a recycled pellet resin extruded foam were obtained in the same manner as in Example 1 except that only linear polystyrene was used as the styrene resin (virgin resin).
The evaluation results of the resin and the extruded foam are shown in Table 1. As shown in Table 1, the weight average molecular weight MW1 of the virgin resin was 4.3 × 10 ⁵ , and the weight average molecular weight MW2 of the recycled pellet resin was 3.2 × 10 ⁵ . Therefore, the ratio MW2 / MW1 of the weight average molecular weight was 0.74.
The density of the obtained extruded virgin resin foam was 34 kg / m ³ , and the closed cell ratio was 94%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 47%, the average bubble diameter was 0.20 mm, and the thermal conductivity measured according to JIS A9511 was 0.027 W / mK.
Moreover, the density of the obtained recycled pellet resin extruded foam was 34 kg / m ³ and the closed cell ratio was 89%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 12%, the average bubble diameter was 0.30 mm, and the thermal conductivity measured according to JIS A9511 was 0.032 W / mK.

(Comparative Example 2)
A virgin resin extruded foam and a recycled pellet resin extruded foam were obtained in the same manner as in Example 6 except that only linear polystyrene was used as the styrene resin (virgin resin).
The evaluation results of the resin and the extruded foam are shown in Table 1. The weight average molecular weight MW1 of the virgin resin was 4.3 × 10 ⁵ , and the weight average molecular weight of the recycled pellet resin MW2 was 3.1 × 10 ⁵ . Therefore, the ratio MW2 / MW1 of the weight average molecular weight was 0.72.
The density of the obtained extruded virgin resin foam was 27 kg / m ³ and the closed cell ratio was 92%. The evaluation of the appearance of the foam was “◯”. Moreover, the small bubble area ratio of the foam was 10%, the average bubble diameter was 0.34 mm, and the thermal conductivity measured according to JIS A9511 was 0.033 W / mK.
Moreover, the density of the obtained recycled pellet resin extruded foam was 26 kg / m ³ , and the closed cell ratio was 85%. The evaluation of the appearance of the foam was “x”. Moreover, the small bubble area ratio of the foam was 5%, the average bubble diameter was 0.40 mm, and the thermal conductivity measured according to JIS A9511 was 0.036 W / mK.

(Comparative Example 3)
A virgin resin extruded foam and a recycled pellet resin extruded foam were obtained in the same manner as in Example 8, except that only linear polystyrene was used as the styrene resin (virgin resin).
The evaluation results of the resin and the extruded foam are shown in Table 1. The weight average molecular weight MW1 of the virgin resin was 4.3 × 10 ⁵ , and the weight average molecular weight of the recycled pellet resin MW2 was 3.2 × 10 ⁵ . Therefore, the ratio MW2 / MW1 of the weight average molecular weight was 0.74.
The density of the obtained extruded virgin resin foam was 28 kg / m ³ and the closed cell ratio was 85%. The evaluation of the appearance of the foam was “◯”. Further, the foam has a structure having a single bubble diameter, the small bubble area ratio is 100%, the average bubble diameter is 0.18 mm, and the thermal conductivity measured in accordance with JIS A9511 is 0.035 W / mK. Met.
Moreover, the density of the obtained recycled pellet resin extruded foam was 28 kg / m ³ and the closed cell ratio was 85%. The evaluation of the appearance of the foam was “x”. Further, the foam has a structure having a single bubble diameter, the small bubble area ratio is 100%, the average bubble diameter is 0.18 mm, and the thermal conductivity measured in accordance with JIS A9511 is 0.037 W / mK. Met.

(Comparative Example 4)
A virgin resin extruded foam and a recycled pellet resin extruded foam were obtained in the same manner as in Example 8 except that 2 parts by weight of dimethyl ether and 4 parts by weight of carbon dioxide were injected as foaming agents.
The evaluation results of the resin and the extruded foam are shown in Table 1. The weight average molecular weight MW1 of the virgin resin was 3.8 × 10 ⁵ , and the weight average molecular weight of the recycled pellet resin MW2 was 3.6 × 10 ⁵ . Therefore, the ratio MW2 / MW1 of the weight average molecular weight was 0.95.
The density of the obtained extruded virgin resin foam was 27 kg / m ³ and the closed cell ratio was 85%. The evaluation of the appearance of the foam was “x”. Further, the foam has a structure having a single bubble diameter, the small bubble area ratio is 100%, the average bubble diameter is 0.15 mm, and the thermal conductivity measured according to JIS A9511 is 0.037 W / mK. Met.
Moreover, the density of the obtained recycled pellet resin extruded foam was 26 kg / m ³ , and the closed cell ratio was 75%. The evaluation of the appearance of the foam was “x”. Further, the foam has a structure having a single bubble diameter, the small bubble area ratio is 100%, the average bubble diameter is 0.17 mm, and the thermal conductivity measured according to JIS A9511 is 0.038 W / mK. Met.

Claims (11)

A styrene resin extruded foam obtained by extrusion foaming a styrene resin composition obtained by melt-kneading a styrene resin and a non-halogen foaming agent,
(I) The styrene-based resin is a multi-branched polystyrene alone or containing a multi-branched polystyrene and a linear polystyrene, and the weight ratio of the multi-branched polystyrene / the linear polystyrene is 100/0. 5/95,
(Ii) A styrene resin extruded foam containing at least one kind of saturated hydrocarbon having 3 to 5 carbon atoms and water as the non-halogen foaming agent.   The styrenic polymer according to claim 1, wherein the multibranched polystyrene is a polymer of a multibranched macromonomer having a repeating structure having a repeating unit selected from an ester bond, an ether bond and an amide bond and a styrenic monomer. Resin extruded foam. The weight of the styrene resin composition in which the weight average molecular weight of the styrene resin is MW1 and the foam obtained by extruding and foaming the styrene resin and the foaming agent is re-pelletized. The styrene resin extruded foam according to claim 1 or 2, which satisfies the following formula (1) when the average molecular weight is MW2.
Formula (1): 0.8 ≦ MW2 / MW1 ≦ 1.0   The styrene resin extruded foam according to claim 1, wherein the saturated hydrocarbon contains at least one selected from the group consisting of propane, n-butane, and i-butane.   The styrene resin extruded foam according to any one of claims 1 to 4, wherein the non-halogen foaming agent further contains ether.   The bubbles forming the foam are mainly composed of bubbles having a bubble diameter of 0.25 mm or less and bubbles having a bubble diameter of 0.25 to 1.0 mm, and bubbles having a bubble diameter of 0.25 mm or less are 10 to 10 per cross-sectional area of the foam. The styrene resin extruded foam according to any one of claims 1 to 5, which has an occupied area of 90%.   The styrene resin extruded foam according to any one of claims 1 to 6, wherein the styrene resin extruded foam has a thermal conductivity of 0.040 W / mK or less.   The styrene resin extruded foam according to any one of claims 1 to 7, wherein the thermal conductivity of the styrene resin extruded foam is 0.028 W / mK or less. The styrene resin extruded foam according to any one of claims 1 to 8, wherein the foam density of the styrene resin extruded foam is 20 to 60 kg / m ³ .   The styrene resin extruded foam according to any one of claims 1 to 9, wherein the styrene resin extruded foam has a thickness of 10 to 150 mm. A method for producing a styrene resin extruded foam in which a styrene resin is heated and melted, a foaming agent is added to the styrene resin, and extrusion foaming is performed in a low pressure region,
(I) The styrene-based resin is a multi-branched polystyrene alone or containing a multi-branched polystyrene and a linear polystyrene, and the weight ratio of the multi-branched polystyrene / the linear polystyrene is 100/0. 5/95,
(Ii) A method for producing a styrene resin extruded foam, which contains at least one kind of saturated hydrocarbon having 3 to 5 carbon atoms and water as the non-halogen foaming agent.