JP4975381B2 - Styrenic resin foam and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a styrene-based resin extruded foam excellent in environmental adaptability and thermal insulation, and to provide a method for producing the same. <P>SOLUTION: The styrene-based resin extruded foam meets the following requirements(a), (b) and (c): (a) The average size of cells in its first surface layer portion in the thickness direction is 0.01-0.15 mm. (b) The average size of cells in its central portion in the thickness direction is 2.5-5.0 times the above-mentioned average size. (c) The ratio of the average size of cells in its second surface layer portion in the thickness direction to that in its extrusion direction is 1.2-10. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

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

A styrenic resin composition is heated and melted in an extruder or the like, and then a low thermal conductivity blowing agent such as chlorinated hydrocarbon, fluorinated hydrocarbon, chlorinated fluorinated hydrocarbon, carbon dioxide, etc. A method of continuously producing a styrenic resin foam by adding, cooling to a predetermined resin temperature, and extruding it to a low pressure region is known. Styrenic resin extruded foam is used as a heat insulating material for structures, for example, because of good workability and heat insulating properties.
Examples of the foaming agent used in the styrene resin extruded foam include chlorofluorocarbons (hereinafter referred to as “CFC”) containing chlorine atoms. CFCs do not generate pores or voids, and form a good extruded foam that is easy to control the bubble diameter, easily remain in the extruded foam, and have low thermal conductivity. Contribute.

  By the way, in the global environment, the destruction of the ozone layer and the influence of chemical substances on the atmosphere or water quality are regarded as problems. In addition, methyl chloride and ethyl chloride are obligated to be reported as a Class 1 Designated Substance in the Chemical Substances Emission Control Management Promotion Act (PRTR Law), and their emissions are controlled. Therefore, it is desired to employ a foaming agent used for producing a styrene resin extruded foam that does not adversely affect the global environment.

  Hydrochlorofluorocarbons (hereinafter referred to as “HCFC”) in which some of the chlorine atoms of CFC are substituted with hydrogen atoms and hydrofluorocarbons that do not contain chlorine atoms (hereinafter referred to as “HFC”) Is proposed). However, although HCFC and HFC have less impact on the ozone layer than CFC, there is concern about the impact on global warming, so it is desirable to reduce the amount used. Under such circumstances, a foaming agent having a low ozone depletion coefficient such as propane, butane, pentane, etc. and having little influence on global warming has been proposed (for example, Patent Document 1).

  However, for example, since the thermal conductivity of butane is higher than that of CFC, HCFC, HFC, etc., if the blowing agent used for extrusion foaming is changed to butane, the thermal conductivity of the resulting styrene resin extruded foam can be increased. There is a problem that it is higher than before and the performance is poor in applications such as a heat insulating material.

On the other hand, for example, it is known to improve the heat insulation performance by configuring the cell structure of the styrene resin extruded foam from small cells and large cells (for example, Patent Documents 2 to 4). Further, by reheating and stretching the extruded foam after extrusion, the average cell diameter in the thickness direction with respect to the average cell diameter in the extrusion direction is set to 1 or less, that is, the heat insulation performance is improved as horizontally flat bubbles in the extrusion direction. It is known (for example, Patent Document 5). Similarly, in order to improve the heat insulation performance, it is known to orient the bubbles of the extruded foam in different directions (for example, Patent Documents 6 and 7). Further, the average cell diameter in the surface layer of the extruded foam is set to 0.05 to 0.20 mm, and the average cell size in the thickness direction of the cell in the center layer is set to the average cell size in the thickness direction of the cell in the surface layer. It is known that the magnification is 1.45 to 2.50 (for example, Patent Document 8).
WO2002-51918 JP 2004-59595 A JP 2005-528494 A Japanese Patent Laid-Open No. 2001-200087 International Publication No. 1999/33625 Pamphlet JP 2004-175862 A JP 2005-514506 A JP 2004-277673 A

  According to the above-mentioned Patent Document 8, if the average bubble diameter of the bubbles in the center layer of the extruded foam is less than 1.45 times the average bubble diameter in the thickness direction of the bubbles in the surface layer, The difference in the average cell diameter in the thickness direction with the bubbles in the surface layer is reduced, the average cell diameter in the thickness direction of the bubbles in the entire extruded foam is reduced, and if an attempt is made to obtain a thick extruded foam, extrusion It is said that the bubbles in the foam have a spindle shape that is long in the thickness direction. As a result, it has been pointed out that a thick extruded foam has a problem that the number of times of blocking by the cell walls is reduced, resulting in a decrease in heat insulation properties or shrinkage in the extrusion direction.

  Moreover, like the styrene resin extruded foam according to Patent Document 8, the average cell diameter in the thickness direction of the bubbles in the central layer of the extruded foam is set to 1. Even if it is 45 to 2.50 times, conventional styrene using HFC or the like as a foaming agent, depending on the type, composition and amount of hydrocarbon used as the foaming agent, and the state of adjustment of the cell structure of the styrene resin extruded foam It cannot be said that an extruded foam having a low thermal conductivity is necessarily obtained as compared with the resin-based extruded foam, and may have a high thermal conductivity depending on the thickness of the extruded foam.

  This invention is made | formed in view of this situation, and it aims at providing the means to obtain the styrene-type resin extrusion foam excellent in environmental compatibility and heat insulation.

As a result of intensive studies for solving the above problems, the present inventors have determined that the average cell diameter and cell diameter distribution in the thickness direction of the bubbles in a specific range of the styrene resin extruded foam , and the anisotropic ratio of the cells By controlling the above, it was found that a styrene resin extruded foam excellent in environmental compatibility and heat insulation was obtained, and the present invention was completed.

That is, the present invention relates to the following [1] to [ 12 ]. [1] A styrene resin extruded foam obtained by extrusion foaming a styrene resin composition containing a foaming agent, which satisfies all of the following conditions (a), (b), and (C):
In addition, a predetermined range of the cross section along the extrusion direction and the cross section along the width direction of the styrene-based resin extruded foam is sampled, the bubble diameter and area of each bubble in the obtained sample cross section are obtained, and the horizontal axis is 0 mm. In the bubble diameter distribution diagram in which the bubble diameter is divided into sections of 0.02 mm from the maximum bubble diameter to the maximum bubble diameter, and the vertical axis is the area ratio of each section obtained by the following formula (1), the following condition (e), A styrene resin extruded foam that satisfies all of the conditions (f) and (g) .
Condition (a): The average cell diameter in the thickness direction of the bubbles existing in the first surface layer portion from the surface perpendicular to the thickness direction of the styrene resin extruded foam to 4 mm in the thickness direction is 0.01 to 0.15 mm. is there.
Condition (b): The average cell diameter in the thickness direction of the bubbles present in the central portion in the thickness direction excluding the first surface layer portion of the styrene resin extruded foam is the average cell diameter present in the first surface layer portion. 2.50 times or more and 5.00 times or less.
Condition (c): ratio of the average cell diameter in the thickness direction to the average cell diameter in the extrusion direction in the bubbles existing in the second surface layer portion from the surface orthogonal to the thickness direction of the styrene resin extruded foam to 2 mm in the thickness direction Is 1.2-10.
Formula (1): Area ratio for each section = sum of the areas of bubbles having bubble diameters belonging to the section / sum of the areas of all bubbles
Condition (e): The maximum value of the bubble diameter section having the area ratio is 0.26 mm or more.
Condition (f): The area ratio in all sections of the bubble diameter has a plurality of peaks.
Condition (g): At least one of the plurality of peaks has a section where the bubble diameter is less than 0.26 mm.
[2] The extruded styrene resin foam according to [1], which further satisfies the following condition (d).
Condition (d): The ratio of the average bubble diameter in the thickness direction to the average bubble diameter in the extrusion direction in the bubbles existing in the central portion is 0.2-2.
[3] The styrene resin extruded foam according to [1] or [2], wherein the styrene resin extruded foam has a skin on the surface.
[4] The styrene resin extruded foam according to any one of [1] to [3], which further satisfies the following condition (h).
Condition (h): a first peak existing in a section where the bubble diameter is smaller than any of the other peaks among the sections where the bubble diameter is less than 0.26 mm, and a section where the bubble diameter is larger than the first peak The area included from the first section having the lowest area ratio present between the first peak and the second peak closest to the first peak to the second section having a bubble diameter of 0 mm or more and less than 0.02 mm. The sum of the ratios is 0.1 to 0.9.
[5] The styrenic resin composition includes, as a foaming agent, (a) one or more saturated hydrocarbons having 3 to 5 carbon atoms, and (ro) dimethyl ether, diethyl ether, methyl ethyl as necessary. The styrene resin extruded foam according to any one of [1] to [ 3 ], comprising a compound selected from ether and alkyl chloride and (c) other non-halogen foaming agent.
[6] The styrene resin extrusion according to [ 5 ], wherein the one or more saturated hydrocarbons having 3 to 5 carbon atoms are selected from the group consisting of propane, n-butane, and i-butane. Foam.
[7] The styrene resin extruded foam according to [ 5 ], wherein the other non-halogen foaming agent is selected from the group consisting of water, carbon dioxide, and alcohol.
[8] The foaming agent contains water as the other non-halogen foaming agent,
The styrenic resin composition comprises 0.01 to 10% by weight of one or more water-absorbing substances selected from the group consisting of layered silicates, silicon oxides, sulfates, carbonates, phosphates and zeolites. The styrene resin extruded foam according to any one of [ 5 ] to [ 7 ], which is contained.
[9] The styrene resin extruded foam according to any one of [1] to [ 8 ], wherein the styrene resin extruded foam has a thermal conductivity of 0.0260 W / mK or less.
[10] The styrene resin extruded foam according to any one of [1] to [ 9 ], wherein the plane compressive strength of the styrene resin extruded foam is 15 N / m ² or more.
[11] The styrene resin extruded foam according to any one of [1] to [ 10 ], wherein the foam density of the styrene resin extruded foam is 30 to 60 kg / m ³ .
[12] The styrene resin extruded foam according to any one of [1] to [ 11 ], wherein the styrene resin extruded foam has a thickness of 10 to 150 mm.

According to the present invention, the styrene resin extruded foam satisfies the conditions (a), (b), (c) , (e), (f), and (g) described above , Excellent heat insulation and environmental compatibility. Such a styrene resin extruded foam is particularly useful as a building material, a heat insulating material for a cold box or a cold car.

  The styrene resin used in the present invention is not particularly limited, and specific examples include, for example, a styrene homopolymer obtained only from a styrene monomer; Random copolymer, block copolymer or graft copolymer obtained from the polymer or a derivative thereof; modified polystyrene such as brominated polystyrene or rubber-reinforced polystyrene; and styrene resin having a branched structure.

  Examples of the monomer copolymerizable with styrene include styrene such as methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene. Derivatives; polyfunctional vinyl compounds such as divinylbenzene; (meth) acrylic compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylonitrile; diene compounds such as budadiene Or derivatives thereof; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride. These may be used alone or in combination of two or more.

  The styrenic resin used in the present invention preferably has a melt flow rate (hereinafter referred to as “MFR”) in the range of 0.1 to 50 g / 10 min from the following points. That is, it is easy to adjust the discharge amount at the time of extrusion foam molding processing, the thickness and width, density or closed cell ratio of the obtained styrene resin foam, and the surface property (that is, excellent in extrusion foam moldability), In addition to obtaining a styrenic resin foam excellent in appearance and the like, it is possible to obtain a styrenic resin foam that balances mechanical strength such as compressive strength, bending strength or bending deflection, and properties such as toughness. ,preferable. Further, the MFR of the styrenic resin is more preferably 0.3 to 30 g / 10 min from the viewpoint of the balance of extrusion foamability and mechanical strength and toughness of the obtained foam, and 0.5 to 20 g / 10 minutes is particularly preferred. In addition, MFR is measured by A method of JISK7210 (1999), and test conditions are set according to the composition of styrene resin. For example, for polystyrene, it is measured under test condition H.

Of the styrene resins, styrene homopolymer (polystyrene) is preferable from the viewpoints of economy and extrusion foamability. Moreover, when high heat resistance is requested | required by an extrusion foam, a styrene-acrylonitrile copolymer, (meth) acrylic acid copolymer polystyrene, and a maleic anhydride modified polystyrene are preferable. Also, rubber reinforced polystyrene is preferred when high impact resistance is required for the extruded foam.
These styrene resins may be used alone, or two or more styrene resins having different molecular weight, MFR, composition, branching degree, etc. may be mixed and used.

  In the present invention, the blowing agent is selected from (i) one or more saturated hydrocarbons having 3 to 5 carbon atoms, and (ro) dimethyl ether, diethyl ether, methyl ethyl ether, and alkyl chloride as necessary. The compound and (c) those containing other non-halogen foaming agents are used.

  By using a combination of (i) a saturated hydrocarbon having 3 to 5 carbon atoms and, if necessary, (b) a compound selected from dimethyl ether, diethyl ether, methyl ethyl ether, and alkyl chloride as a blowing agent, It becomes easy to adjust the thickness, width, or closed cell ratio, thermal conductivity, cell diameter, and surface property of the resulting styrene resin extruded foam to desired values. That is, the moldability of the extruded foam is excellent. Moreover, a styrenic resin foam having a good appearance can be obtained. Here, examples of the alkyl chloride include methyl chloride and ethyl chloride. However, from the viewpoint of environmental compatibility, it is more preferable to use the ether.

  In the present invention, as the foaming agent, other non-halogen foaming agents may be combined with these. As a result, the amount of flammable foaming agent such as a compound selected from saturated hydrocarbons having 3 to 5 carbon atoms, dimethyl ether, diethyl ether, methyl ethyl ether, and alkyl chloride can be reduced. The combustibility of the foam can be improved.

  Examples of the one or more saturated hydrocarbons having 3 to 5 carbon atoms include those selected from the group consisting of propane, n (normal) -butane, and i (iso) -butane. Other non-halogen foaming agents include those selected from the group consisting of water, carbon dioxide and alcohol.

  The total amount of the foaming agent is appropriately adjusted according to the setting value of the expansion ratio of the styrene resin extruded foam, but the total amount of the foaming agent is usually based on 100 parts by weight of the styrene resin. By setting it as 1-20 weight part, since the moldability of an extrusion foam is excellent, it is preferable, More preferably, it is 2-15 weight part, Especially preferably, it is 2-10 weight part.

  (I) The amount of the saturated hydrocarbon having 3 to 5 carbon atoms used as the foaming agent is 0.1 to 10 parts by weight with respect to 100 parts by weight of the styrenic resin. It is preferable from the point of balance of combustibility and thermal conductivity, more preferably 0.5 to 8 parts by weight, and particularly preferably 1 to 5 parts by weight.

  The amount of the compound selected from (b) dimethyl ether, diethyl ether, methyl ethyl ether, and alkyl chloride used as a blowing agent is 0.1 to 10 parts by weight with respect to 100 parts by weight of the styrene resin. It is preferable from the point of the moldability of a foam, More preferably, it is 0.2-7 weight part, Most preferably, it is 0.5-5 weight part.

  For example, if the amount of other halogen-based foaming agent used as the foaming agent is water, it may be 0.05 to 5 parts by weight with respect to 100 parts by weight of the styrenic resin. It is preferable from the viewpoint, and it is preferable from the viewpoint that a good foam can be obtained without causing defects such as pores and voids in the extruded foam. More preferably, it is 0.1-4 weight part, Most preferably, it is 0.15-3 weight part.

  The foaming agent added to the styrene resin composition remains in the extruded styrene resin foam and contributes to the reduction of thermal conductivity. The amount of the remaining foaming agent depends on the styrene resin of each foaming agent. Varies depending on permeability. The foaming agent having low permeability to the styrene resin remains in the styrene resin extruded foam for a relatively long time, and contributes to the reduction and maintenance of the thermal conductivity. A foaming agent having a high transmittance with respect to the styrenic resin improves the moldability of the extruded foam, and the appearance thereof is good. However, such a foaming agent is diffused to the outside immediately after the production of the extruded foam, and hardly remains in the extruded foam depending on the type of the foaming agent. Such a foaming agent is a compound having high compatibility with the styrene resin or high solubility in the styrene resin.

  The foaming agent having a low transmittance with respect to the styrene resin is the above-described saturated hydrocarbon having 3 to 5 carbon atoms. Among these, it is preferable to use n-butane and i-butane from the balance between the moldability of the extruded foam and the effect of reducing the thermal conductivity. Further, from the balance between the effect of reducing the thermal conductivity and the improvement of combustibility, the content of the saturated hydrocarbon is preferably 1 to 5% by weight, more preferably 100% by weight of the styrene resin extruded foam. 1.5 to 4.5% by weight. The foaming agent having high permeability to the styrene resin is the above-mentioned compound such as dimethyl ether, carbon dioxide or the like.

  The content of the foaming agent contained in the styrene-based resin extruded foam is the gas extracted from the obtained extruded foam by heating a test piece with all surfaces cut out by 2 mm or more in a closed container, or styrene Depending on the type of the system resin, it can be measured by gas chromatography using a gas extracted by dissolving in a solvent as a sample.

  When water is used as the other non-halogen foaming agent, it is preferable to add a water-absorbing substance in order to stably perform extrusion foam molding. A water-absorbing substance refers to a compound that itself absorbs water, absorbs, adsorbs, swells with water, or a compound that reacts with water to form a hydrate. The water-absorbing material absorbs, absorbs, or reacts with water having low compatibility with the styrenic resin to form a gel, and is uniformly dispersed in the styrenic resin in the gel state. It is considered that stable extrusion foaming can be realized without generating pores or voids in the foam.

  The water-absorbing substance used in the present invention is at least selected from the group consisting of silicon oxide, layered silicate, porous substance, sulfate, carbonate, phosphate, other metal salts, boron compounds, and water-absorbing polymers. One type. Specific examples thereof include fine powder having a particle diameter of 1000 nm or less having a hydroxyl group on the surface, such as anhydrous silica having a silanol group (silicon oxide) on the surface. Examples of such anhydrous silica include AEROSIL (trade name) manufactured by Nippon Aerosil Co., Ltd., DSL. Carplex (trade name) manufactured by Japan Co., Ltd. is commercially available. Examples of layered silicates include layered silicates that are water-absorbing such as smectite and swellable fluorinated mica, or water-swellable, or organically treated products thereof. Examples of the porous material include zeolite, activated carbon, alumina, silica gel, porous glass, activated clay, diatomaceous earth, and the like. Examples of the sulfate include sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, barium sulfate, aluminum sulfate, zinc sulfate, and ammonium sulfate. Examples of the carbonate include sodium carbonate, sodium hydrogen carbonate, magnesium carbonate, and ammonium carbonate. Examples of phosphates include sodium phosphate, magnesium phosphate, aluminum phosphate, ammonium phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, triammonium phosphate, calcium dihydrogen phosphate, And calcium hydrogen phosphate. Other metal salts include calcium citrate, trisodium citrate, tripotassium citrate, calcium lactate, ammonium oxalate, potassium oxalate, disodium succinate, sodium acetate, sodium pyrophosphate, magnesium chloride, barium chloride, etc. Is mentioned. Examples of the boron compound include boron oxide and sodium borate. As the water-absorbing polymer, polyacrylate polymer, starch-acrylic acid graft copolymer, polyvinyl alcohol polymer, vinyl alcohol-acrylate copolymer, ethylene-vinyl alcohol copolymer, Examples thereof include polyacrylonitrile-methyl methacrylate-butadiene copolymer, polyethylene oxide copolymer, and derivatives thereof. These water-absorbing substances may be used alone or in combination of two or more.

  Among the water-absorbing substances described above, anhydrous layered silica, polyacrylate polymer, smectite, swellable fluorinated mica and other layered silicates, sulfate metal salts, carbonate carbonate salts, phosphorus Metallic salts such as acid metal salts and porous materials such as zeolite are stable in extrusion foaming, the generation of pores and voids is suppressed, and a cell structure having a characteristic cell diameter distribution described later is formed. Desirable in that the desired heat insulation performance is expressed and the quality is stabilized.

  The amount of the water-absorbing substance used in the present invention is appropriately adjusted according to the amount of water added as a foaming agent, but is 0.1 to 10 parts by weight with respect to 100 parts by weight of the styrenic resin. Preferably, 0.1 to 8 parts by weight is more preferable, and 0.2 to 7 parts by weight is particularly preferable. By setting the amount of the water-absorbing substance in the above range, extrusion foaming is stabilized, generation of pores and voids is suppressed, and a cell structure having a characteristic cell diameter distribution described later is formed, and a desired structure is formed. There is an advantage that the heat insulation performance is expressed and the quality is stabilized.

  The layered silicate will be described in more detail. 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 has the chemical formula (1):
X _0.2 to _0.6 Y ₂ to ₃ Z ₄ O ₁₀ (OH) ₂ .nH ₂ O (1)
(In the formula, X is at least one selected from the group consisting of K, Na, 1 / 2Ca and 1 / 2Mg, and Y is composed of Mg, Fe, Mn, Ni, Zn, Li, Al and Cr. One or more selected from the group, and Z is one or more selected from the group consisting of Si and Al, where H2O represents a water molecule bonded to an interlayer ion, and n = 0.5 to Although n is about 10, n is not limited to these because it varies significantly depending on interlayer ions and relative humidity, and is natural or synthesized. Specific examples of the smectite group clay include, for example, montmorillonite, beidellite, nontronite, saponite, iron saponite, hectorite, soconite, stevensite and bentonite, and substitution products, derivatives, or mixtures thereof.

The swelling mica has the chemical formula (2):
X _0.5 to _1.0 Y ₂ to ₃ (Z ₄ O ₁₀ ) (F, OH) ₂ (2)
(Wherein X is one or more selected from the group consisting of Li, Na, K, Rb, Ca, Ba and Sr, and Y is from the group consisting of Mg, Fe, Ni, Mn, Al and Li) One or more selected, and Z is one or more selected from the group consisting of Si, Ge, Al, 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 swellable mica have a structure similar to vermiculites, and such vermiculite equivalents can also be used. The vermiculite-equivalent product has 3 octahedron type and 2 octahedron type, 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 (3)
(Wherein, M is an exchangeable cation of an alkali or alkaline earth metal such as Na and Mg, x = 0.6 to 0.9, and n = 3.5 to 5). It is done.
In the layered silicate, smectite clay and swellable mica are preferred from the viewpoint of dispersibility in the obtained foam, stability of extrusion foam molding when water is used as a foaming agent, and more preferably montmorillonite, It is a swellable mica having sodium ions between layers such as bentonite, hectorite, smectite group clay such as synthetic smectite, and 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. The smectite also includes montmorillonite-modified products such as anionic polymer-modified montmorillonite, silane-treated montmorillonite, and highly polar organic solvent composite montmorillonite.

  A layered silicate may be used independently and may be used in combination of 2 or more type.

  The content of the layered silicate is appropriately adjusted according to the amount of water added as a foaming agent, but is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the styrenic resin composition, 0.2-7 weight part is further more preferable. The mixing ratio (weight ratio) of water / layered silicate is preferably 0.02 to 20, more preferably 0.1 to 10, and particularly preferably 0.15 to 5. By setting the content of the layered silicate in the above range, the water absorption or adsorption amount of the layered silicate is sufficiently greater than the amount of water added, and the water dispersibility is improved. Is stabilized, the generation of pores and voids is suppressed, and a bubble structure having a characteristic bubble diameter distribution, which will be described later, is formed, thereby providing the desired heat insulation performance.

  In the present invention, for example, a flame retardant may be added to a styrene resin in order to answer the use of a styrene resin extruded foam such as a heat insulating material for buildings. Examples of the flame retardant include a halogen-based flame retardant. Examples of the halogen flame retardant include tetrabromocyclooctane, hexabromocyclododecane, dibromoethyldibromocyclohexane, tetrabromobisphenol A, tetrabromobisphenol S, tetrabromobisphenol A bis (2,3-dibromopropyl ether), tetra Bromobisphenol S bis (2,3-dibromopropyl ether), tetrabromobisphenol A diallyl ether, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis (2- Methyl allyl ether), tetrabromobisphenol A-bis (3-methylallyl ether), tris (2,3-dibromopropyl) isocyanurate, tris (tribromoneopenti) ) Such as phosphate, and the like. These compounds may be used alone or in combination of two or more.

  In the present invention, a flame retardant aid may be added for the purpose of further improving the combustibility of the styrene resin extruded foam. Flame retardant aids include, for example, phosphates, phosphonates, phosphinates, phosphites, phosphoric acids, phosphonic acids, phosphinic acids or derivatives thereof, metal salts, melamine salts, ammonium salts, and phosphazenes or derivatives thereof, phosphonitriles or Examples thereof include phosphorus-containing compounds such as derivatives thereof. Examples thereof include nitrogen-containing compounds such as triazine skeleton-containing compounds, cyanuric acid or isocyanuric acid and derivatives thereof, guanidine compounds, azo compounds, and tetrazole compounds. Further, for example, boron-containing compounds such as boric acid, borax, metal borate, boron oxide, boron phosphate and borosilicates, for example, sulfur-containing compounds such as sulfate, sulfonate, sulfanilic acid and the like can be mentioned. Examples thereof include 2,3-dimethyl-2,3-diphenylbutane.

  In the present invention, a phosphate ester may be added in order to improve the extrusion foam moldability of the styrene resin foam. Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri (2-ethylhexyl) phosphate, tributoxyethyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate. Aliphatic hydrocarbon monophosphates such as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris (isopropylphenyl) phosphate, tris (phenylphenyl) phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl Diphenyl phosphate, diphenyl (2-ethylhexyl) phosphate, di (isopropyl A) Aromatic hydrocarbon monophosphates such as phenyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, resorcinol diphenyl phosphate, resorcinol dixylenyl phosphate, resorcinol dicresyl phosphate, Bisphenol A / diphenyl phosphate, bisphenol A / dixylenyl phosphate, bisphenol A / dicresyl phosphate, hydroquinone / diphenyl phosphate, hydroquinone / dixylenyl phosphate, hydroquinone / dicresyl phosphate, resorcinol / polyphenyl phosphate, resorcinol / poly (di -2,6-Xylyl) phosphate bisphenol A Condensed phosphate esters such as cresyl phosphate, hydroquinone poly (2,6-xylyl) phosphate, and halogenated phosphate ester compounds such as tris (tribromoneopentyl) phosphate and tris (bromophenyl) phosphate can give.

  Furthermore, in the present invention, various compounds can be added as necessary within a range not inhibiting the effects of the present invention. Specifically, inorganic compounds such as silica, talc, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate, sodium bicarbonate, sodium stearate, magnesium stearate, stearic acid Processing aids such as barium, liquid paraffin, olefin wax, stearylamide compound, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6- Hexanediol-bis {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate}, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di -T-butylanilino) -1,3,5-triazine, pentaerythrityl-tetraki [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-t-butyl-4-hydroxyphenyl) propionate, 3,5-di-t- Butyl-4-hydroxy-benzyl phosphate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris (3,5 -Di-t-butyl-4-hydroxybenzyl) isocyanurate and other hindered phenol antioxidants, triphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, bis (2, 4-di-t-butylphenyl) pentaerythritol diphosphite, bisstearyl pentaerythritol diphosphite, bis ( , 4-Di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite Phosphorus stabilizers such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer, amines such as alkylated diphenylamine, octylated diphenylamine, 4,4'-bis (α, α-dimethylbenzyl) diphenylamine Stabilizers, sulfur stabilizers such as 3,3-thiobispropionic acid didecyl ester, 3,3'-thiobispropionic acid dioctadecyl ester, light-resistant stabilizers such as benzotriazoles and hindered amines, antistatic Additives such as colorants such as additives, plasticizers, and pigments can be included.

The styrene resin extruded foam according to the present invention satisfies all of the following conditions (a), (b), and (c).
Condition (a): The average cell diameter in the thickness direction of the bubbles existing in the first surface layer portion from the surface perpendicular to the thickness direction of the styrene resin extruded foam to 4 mm in the thickness direction is 0.01 to 0.15 mm. is there.
Condition (b): The average cell diameter in the thickness direction of the bubbles existing in the central portion excluding the first surface layer portion of the styrene resin extruded foam is 2 of the average cell diameter existing in the first surface layer portion. It is 50 times or more and 5.00 times or less (hereinafter, this magnification is referred to as “the bubble diameter magnification at the center”).
Condition (c): ratio of the average cell diameter in the thickness direction to the average cell diameter in the extrusion direction in the bubbles existing in the second surface layer portion from the surface orthogonal to the thickness direction of the styrene resin extruded foam to 2 mm in the thickness direction Is 1.2 to 10 (hereinafter, this ratio is referred to as “bubble flatness ratio in the second surface layer portion”).

  When the styrene resin extruded foam satisfies the condition (a), even if the foaming agent contains a hydrocarbon such as butane, the extruded foam can have a low thermal conductivity and a low density. In consideration of the ease of adjusting the thickness and density of the extruded foam and the stability of thermal conductivity, the average cell diameter in the thickness direction in the first surface layer portion is preferably 0.06 to 0.20 mm. preferable.

By satisfying the condition (b), the styrene resin extruded foam has a low thermal conductivity and a low density extruded foam even when the foaming agent contains a hydrocarbon such as butane. In view of the ease of adjusting the thickness and density of the extruded foam and the stability of thermal conductivity, the cell diameter magnification at the center is more preferably 2.60 times to 4.00 times.
In order to obtain a lower thermal conductivity, the average bubble diameter of the bubbles at the center is preferably 0.01 to 0.3 mm, more preferably 0.02 to 0.2 mm, and particularly preferably 0. 0.03 to 0.15 mm.

  By satisfying the condition (c), the styrene resin extruded foam has a low thermal conductivity and a low density extruded foam even when the foaming agent contains a hydrocarbon such as butane.

  In addition, the average bubble diameter of the bubble in a 1st surface layer part, a center part, and a 2nd surface layer part is calculated | required based on the method mentioned later.

The styrene resin extruded foam according to the present invention may further satisfy the following condition (d).
Condition (d): The ratio of the average bubble diameter in the thickness direction to the average bubble diameter in the extrusion direction in the bubbles existing in the center portion is 0.2 to 2 (hereinafter, this ratio is referred to as “bubble flatness ratio in the center portion”). Called).

  When the styrene resin extruded foam satisfies the condition (d), an extruded foam having a low thermal conductivity can be obtained stably. Further, from the viewpoint of the balance between the thermal conductivity and the strength of the extruded foaming agent, the bubble flatness at the central portion is more preferably 0.7-2, and particularly preferably 0.8-1.5.

  In the present invention, the average cell diameter is determined by the following method. The cross section along the thickness direction of the styrene resin extruded foam and the predetermined range of the cross section along the extrusion direction are sampled. Here, the section along the thickness direction is a direction (width direction) orthogonal to the extrusion direction of the extruded foam and is a section extending in the thickness direction. The cross section along the extruding direction is the extruding direction of the extruded foam and is a cross section extending in the thickness direction. Each predetermined range of this cross section is sampled. The predetermined range to be sampled is the first surface layer portion, the second surface layer portion, and the center portion described above. In addition, when a predetermined number of bubbles to be described later cannot be obtained with one sample, a plurality of locations may be sampled.

  Each sampled sample is photographed using a scanning electron microscope (SEM) to obtain an SEM image. The photographing magnification of the SEM image is set to about 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, product name: PIAS-II, manufactured by Pierce Co., Ltd.) with the thickness direction as the vertical direction and the extrusion direction as the horizontal direction. The bubble area (hereinafter referred to as “bubble area”) (a) is obtained. Further, the maximum diameter (Feret diameter) in the longitudinal direction (thickness direction: zf) and lateral direction (extrusion direction or width direction: xf) of the bubbles is determined. Note that the notation area and the maximum diameter are measured only for the bubbles in which the entire view of the bubbles is projected in the SEM image, and some of the bubbles are missing at the edges of the SEM image, or the edges 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.

Each bubble in the SEM image is assumed to be elliptical, and the bubble diameter Z in the thickness direction of each bubble and the bubble diameter X in the extrusion direction or the width direction are obtained according to the following formulas (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 and the bubble diameter X in the extrusion direction or the width direction according to the equation (4).
Formula (4): D = (X × Z) ^1/2

  In the present invention, the average bubble diameter in the thickness direction in the bubbles present in the first surface layer portion is the number average of the respective bubble diameters Z in the thickness direction determined in the first surface layer portion. The average bubble diameter in the extrusion direction of the existing bubbles is the number average of the respective bubble diameters X in the extrusion direction determined in the first surface layer portion. The average bubble diameter in the thickness direction in the bubbles existing in the second surface layer portion is the number average of the respective bubble diameters Z in the thickness direction obtained in the second surface layer portion, and in the bubbles existing in the second surface layer portion. The average cell diameter in the extrusion direction is the number average of each cell diameter X in the extrusion direction obtained in the second surface layer portion. The average bubble diameter in the thickness direction of the bubbles present in the central portion is the number average of the respective bubble diameters Z in the thickness direction obtained in the central portion, and the average bubble diameter in the extrusion direction of the bubbles present in the central portion. Is the number average of the respective bubble diameters X in the extrusion direction obtained at the central portion. Moreover, the average bubble diameter calculated | required from the bubble diameter of the thickness direction in the center part, the bubble diameter of the width direction, and the bubble diameter of an extrusion direction says what averaged the representative bubble diameter D calculated | required in the center part.

  The styrene resin extruded foam according to the present invention preferably has a composite cell (bubble) structure in which “small bubbles” having a small bubble diameter and “large bubbles” having a large bubble diameter are mixed in a sea-island shape. Thereby, the heat insulation and the mechanical characteristic which were excellent in the extrusion foam can be provided. Specifically, if the extruded foam has a single cell (bubble) structure composed of bubbles having a substantially uniform diameter, the heat insulating property of the extruded foam can be improved by reducing the bubble diameter. A large amount of resin is required to obtain a thick extruded foam by reducing the bubble diameter. As a result, the pressure at the time of extrusion molding increases, and the moldability may deteriorate. On the other hand, in the composite cell structure, heat insulation is improved by the presence of small bubbles, and a thick extruded foam can be easily formed at a low resin density by the presence of large bubbles.

The composite cell structure preferably has a structure specified by a bubble meridian diagram shown below. The bubble distribution diagram samples a predetermined range of a cross section along the extrusion direction and a cross section along the width direction of the styrene resin extruded foam. The cross section along the extrusion direction is a cross section extending in the thickness direction in the extrusion direction of the extruded foam. The cross section along the width direction is a cross section that extends in the thickness direction in the width direction of the extruded foam, and the cross section is a plane orthogonal to the extrusion direction. A predetermined range of each of these two cross sections is sampled. The bubble diameter and area of each bubble in the obtained sample cross section are obtained, the horizontal axis is the bubble diameter divided into sections of 0.02 mm from 0 mm to the maximum bubble diameter, and the vertical axis is obtained by the following formula (1). This is the area ratio for each section.
Formula (1): Area ratio for each section = sum of the areas of bubbles having bubble diameters belonging to the section / sum of the areas of all bubbles

  In the range from zero to the section including the maximum bubble diameter, the horizontal axis represents the representative bubble diameter D divided into sections every 0.02 mm, and the vertical axis represents the area ratio for each section represented by Equation (1). Created and used as a bubble distribution chart in the present invention. The classification of the representative bubble diameter D in the bubble distribution chart is, for example, that the representative bubble diameter D is zero or more and less than 0.02 mm in the smallest section. In addition, when it is simply described as “bubble diameter” at the very beginning, it will indicate the representative bubble diameter D unless otherwise specified. In addition, the vertical axis of the bubble diameter distribution chart, that is, the range of each section of the representative bubble diameter D includes the minimum representative bubble diameter D of the section, and the bubble diameter larger by 0.02 mm than the minimum representative bubble diameter D is Not included. That is, the bubble diameter belonging to the section is not less than the minimum bubble diameter of the section and less than the minimum bubble diameter of the section + 0.02 mm.

  In the bubble diameter distribution diagram, from the section where the bubble diameter is zero to less than 0.02 mm, the area ratio in the section is compared with the area ratio of the adjacent section. In the present invention, when the area ratio is larger than the area ratio in one section (the section where the bubble diameter is 0.02 mm smaller and 0.02 mm larger), the peak is recognized in the present invention, the area ratio of the section is the peak area ratio, and the section is It is called the peak section. When the area ratio in one or both of the two adjacent sections is equal, the area ratio of the next adjacent section of the uniform field sum is compared. The plurality of sections are combined to be a peak section. When the area ratio in either one or both adjacent sections is larger, it is not determined as a peak.

The extruded styrene resin foam according to the present invention preferably satisfies all of the following conditions (e), (f), and (g) in this bubble diameter distribution diagram.
Condition (e): The maximum value of the bubble diameter section having the area ratio is 0.26 mm or more.
Condition (f): The area ratio in all sections of the bubble diameter has a plurality of peaks.
Condition (g): At least one of the plurality of peaks is present in a section where the bubble diameter is less than 0.26 mm.

  When the styrene-based resin extruded foam satisfies the condition (e), that is, when the maximum cell diameter is 0.26 mm or more in the cell diameter distribution diagram, the styrene-based resin extruded with a predetermined thickness at a low foam density. A foam can be obtained, and the heat insulating property of the styrene resin extruded foam is excellent. More preferably, the maximum bubble diameter is 0.26 to 0.60 mm, and particularly preferably 0.27 to 0.50 mm. In the present invention, the maximum bubble diameter refers to the maximum value of the representative bubble diameter D obtained by the above-described equation (3).

  When the styrene resin extruded foam satisfies the condition (f), that is, in the cell diameter distribution diagram, the area ratio in all the sections of the cell diameter has a plurality of peaks, so that the heat insulating property of the styrene resin extruded foam is As a result, it is possible to obtain a styrene resin extruded foam having a predetermined thickness with a low foam density, and the moldability during extrusion foaming is improved.

  When the styrene resin extruded foam satisfies the condition (g), that is, when at least one of the plurality of peaks is present in a section having a cell diameter of less than 0.26 mm, the styrene resin extruded foam The heat insulation of the body is improved. Due to the presence of a peak in the section where the bubble diameter is less than 0.26 mm, bubbles having a relatively small bubble diameter exist in the styrene-based resin extruded foam, and the bubble wall that suppresses heat conduction by radiation is present. As it increases, the heat insulation is improved. Moreover, it is more preferable that the peak exists in a section between 0.04 and 0.26 mm, and it is particularly preferable that the peak exists in a section between 0.06 and 0.20 mm.

The styrene resin extruded foam according to the present invention preferably further satisfies the following condition (h).
Condition (h): a first peak existing in a section where the bubble diameter is smaller than any of the other peaks among the sections where the bubble diameter is less than 0.26 mm, and a section where the bubble diameter is larger than the first peak The area included from the first section having the lowest area ratio present between the first peak and the second peak closest to the first peak to the second section having a bubble diameter of 0 mm or more and less than 0.02 mm. The sum of the ratios is 0.1 to 0.9.

  When the styrene resin extruded foam satisfies the condition (h), the balance between the foam density and the heat insulating property of the styrene resin extruded foam becomes good. More preferably, the area ratio constituting the minimum bubble diameter is 0.15 to 0.8.

The styrene resin extruded foam according to the present invention may further satisfy the following condition (i).
Condition (i): Among the peaks existing in the section where the bubble diameter is less than 0.26 mm, the third peak existing in the section where the bubble diameter is larger than any other peak, and the section where the bubble diameter is 0.26 mm or more Among the existing peaks, there is a peak from the third section having the lowest area ratio existing between the fourth peak having a smaller bubble diameter than any other peak or in the section having a bubble diameter of 0.26 mm or more. If it does not exist, it is included from the fourth section with the smallest bubble diameter where the area ratio that can exist in the section where the bubble diameter is 0.26 mm or more is zero to the second section where the bubble diameter is zero to 0.02 mm. The total area ratio is 0.1 or more.
When the styrene resin extruded foam satisfies the condition (i), the balance between the foam density and the heat insulating property of the styrene resin extruded foam becomes good. More preferably, the sum of the area ratios is 0.2 or more, and particularly preferably 0.3 or more.

The styrene resin extruded foam according to the present invention may further satisfy the following condition (j).
Condition (j): Among the plurality of peaks, at least one peak (fifth peak) is present in a section where the bubble diameter is 0.10 mm or more and the bubble diameter is larger than the peak (fifth peak). There is another peak (sixth peak) different from the peak (fifth peak) in the section.

  When the styrene resin extruded foam satisfies the condition (j), the balance between the foam density and the heat insulating property of the styrene resin extruded foam becomes good. More preferably, the area ratio of the fifth peak is present in a section of less than 0.20 mm, and the sixth peak is present in a section having a bubble diameter of 0.15 mm or more.

  Styrenic resin extruded foam is a foamable molten styrene by supplying a styrene resin to a melt kneading means and supplying an additive containing a nucleating agent and a foaming agent to the melt kneading means and kneading with the styrene resin. It is obtained by extruding and foaming the expandable molten styrene resin composition from a high pressure region to a low pressure region through a die lip.

  As a method of adjusting the cell diameter distribution of the styrene resin extruded foam, water is used as a foaming agent, and depending on the type and amount of other foaming agent, the type and amount of water-absorbing substance, the molding conditions for extrusion foaming, etc. Can be adjusted. As such molding conditions, for example, adjustment of the enlargement ratio of the thickness when the molten styrene resin composition is discharged into the atmosphere, that is, the die lip slit thickness and the molding die for making a rectangle The height can be adjusted. Moreover, the method of adjusting molding resistance is mention | raise | lifted.

  As a procedure for adding various additives to the styrene resin, for example, after adding and mixing various additives to the styrene resin, the mixture is supplied to an extruder and melted by heating, and further a foaming agent is added. There are procedures for mixing, but the timing of 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 a temperature at which the degradation 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. preferable. 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. In addition, in order to suppress degradation and degradation of the resin as much as possible, the screw shape of the extruder is preferably a low shear type.

  The foam molding method includes, for example, an extrusion foam obtained by releasing pressure from a high pressure region to a low pressure region through a slit die having an opening used for extrusion molding having a straight slit shape. A method of molding a plate-like foam having a large cross-sectional area is used by using a molding die placed in contact and a molding roll installed adjacent to the downstream side of the molding die. By adjusting the flow surface shape of the molding die and the mold temperature, a desired foam cross-sectional shape, foam surface property, and foam quality can be obtained.

  Methods for controlling the average cell diameter of extruded foam include silica, talc, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate, sodium bicarbonate, and other inorganic compounds. There is a method of adding a representative nucleating agent or the above-mentioned layered silicate to a styrenic resin and adjusting the addition amount thereof. The average cell diameter is also adjusted by the type, composition and addition amount of the foaming agent. Also, depending on the screw shape of the extruder that is the melt kneading means, the heating temperature, the pressure, the amount of the melt-kneaded styrene resin composition discharged from the die lip, the die shape, the resin temperature at the time of discharge, etc. The bubble diameter is adjusted.

  Examples of a method for controlling the bubble flatness ratio in the second surface layer portion include a method of stretching an extruded foam while heating. Specifically, while heating the extruded foam with heated air, the roll is rotated faster than the rotational speed of the take-up machine, and the stretching process is performed. The rotation speed of the roll is preferably 1.01 to 1.50 times the take-up speed from the die lip by the take-up machine.

  The styrene resin extruded foam according to the present invention preferably has a skin on the surface. In the present invention, the surface of the extruded foam means a surface orthogonal to the thickness direction of the styrene resin extruded foam. The thickness direction of the extruded foam is a direction in which heat flows when used as a heat insulating material. That is, in the present invention, the surface is a surface perpendicular to the direction in which heat flows. By having a skin on the surface of the extruded foam, heat conduction is further suppressed, and a foaming agent such as butane is dissipated from the extruded foam and air is prevented from entering the extruded foam. The change in the thermal conductivity of the extruded foam over time is suppressed, and stable heat insulation without change over time is exhibited. The skin may be formed only on one surface of the extruded foam, but it is preferable to have the skin on both the upper and lower surfaces.

  Considering that the styrene-based 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 on the 30th day after manufacture is 0.0260 W. / MK or less is preferable. This thermal conductivity is measured according to JIS A9511.

In consideration of the function of the styrene-based resin extruded foam according to the present invention as, for example, a heat insulating material for a building, a cold storage or a cold car, the plane compressive strength may be 15 N / m ² or more. preferable. This plane compressive strength is measured according to JIS A9511.
The styrene-based resin extruded foam according to the present invention is, for example, from the viewpoint of heat insulation, strength and light weight considering that it functions as a heat insulator for construction, a cold storage or a cold car, and the density of the foam preferably it is 30~60kg / m ^3, more preferably a 35~50kg / m ^3. In addition, the foam density of the second surface layer portion is higher than the overall foam density described above and is 45 to 105 kg / m ³ , from the viewpoint of improving the heat insulating property because the thermal conductivity of the extruded foam is low. preferable. The foam density of this extruded foam is measured according to the method described in JIS K7222-1999 “Foamed plastics and rubbers—Measurement of apparent density”.

  The thickness of the styrene-based resin extruded foam in the present invention is 10 to 150 mm from the viewpoint of heat insulation, bending strength and compressive strength considering that it functions as a heat insulating material for buildings, a cold storage or a cold storage vehicle. It is preferable that it is, It is more preferable that it is 15-120 mm, It is especially preferable that it is 20-100 mm.

  Thus, according to the present invention, an extruded foam excellent in heat insulation and environmental compatibility by satisfying the conditions (a), (b), and (c) described above for the styrene resin extruded foam. You can get a body. Such a styrene resin extruded foam is particularly useful as a building material, a heat insulating material for a cold box or a cold car.

  Next, the styrenic resin foam of the present invention will be described in more detail based on examples, but the present invention is not limited only to such examples. Unless otherwise specified, “%” represents wt%.

  Evaluation methods for Examples and Comparative Examples are as follows.

(1) Foam dimensions (unit: mm)
Thickness: For three foams sampled at different times, the thickness in the center in the width direction (horizontal direction orthogonal to the extrusion direction) was measured, and the average value was calculated.
Width: For three foams sampled at different times, the center width in the thickness direction was measured, and an average value was calculated.

(2) Foam density (unit: kg / m ³ )
Density of the entire styrenic resin foam:
The styrene-based resin extruded foam was cut into a rectangular parallelepiped shape so that the test piece volume was 50 cm ³ or more in the full width and the full thickness in the width direction (horizontal direction orthogonal to the extruding direction) to obtain a test piece. With respect to this test piece, the foam density was measured according to the method described in JIS K7222-1999 “Foamed Plastics and Rubber—Measurement of Apparent Density”.
Foam density of the first surface layer portion:
A styrene resin extruded foam was cut into a thin plate shape with a thickness of 2 mm from the surface and a full width in the width direction (horizontal direction orthogonal to the extrusion direction) so that the volume of the test piece was 50 cm ³ or more. did. With respect to this test piece, the foam density was measured according to the method described in JIS K7222-1999 “Foamed Plastics and Rubber—Measurement of Apparent Density”.

(3) Residual foaming agent amount (unit: parts by weight)
About 1 g of a test piece having all surfaces cut off by 2 mm or more was precisely weighed from a styrene resin foam 30 days after the production, placed in a sealed container, and heated at 200 ° C. for 15 minutes. The gas in the container was collected, and the content of foaming agent (the amount of residual foaming agent) was measured using gas chromatography (Shimadzu Corporation, trade name: GC-14A).

(4) Thermal conductivity (unit: W / mK)
The thermal conductivity of the styrene resin extruded foam 30 days after the trial production was measured according to JIS A9511 (1995).

(5) Bubble structure:
The average bubble diameter in the first surface layer portion corresponding to the condition (a), the bubble diameter magnification in the central portion corresponding to the condition (b), and the bubble flatness ratio in the second surface layer portion corresponding to the condition (c) were described above. Determined based on the method.
For the styrene resin extruded foam, a bubble size distribution diagram was prepared according to the method described above, the maximum value of the bubble size corresponding to the condition (e), the number of peaks in all sections corresponding to the condition (f), and the conditions The peak present in the section where the bubble diameter corresponding to (g) is less than 0.26 mm, the sum of the area ratios included in the first section to the second section corresponding to the condition (h) (hereinafter referred to as “small bubble area ratio”). ), The sum of the area ratios included in the third section corresponding to condition (i) or from the fourth section to the second section (hereinafter referred to as “minimum bubble area ratio”), condition (j) The positions of the fifth peak and the sixth peak corresponding to were obtained.

In the examples and comparative examples, the following compounds were used.
Styrene resin / polystyrene A: manufactured by PS Japan Co., Ltd., G9401: MFR, 2.5 g / 10 minutes, polystyrene B: manufactured by Toyo Styrene Co., Ltd., HRM-18
Foaming agent / butane: Iwatani Sangyo Co., Ltd., a mixture of 60% by weight of isobutane and 40% by weight of normal butane / isobutane: manufactured by Mitsui Chemicals, Ltd., isobutane / dimethyl ether: manufactured by Mitsui Chemicals, Inc. Carbon dioxide: manufactured by Showa Carbon Co., Ltd., carbon dioxide water-absorbing substance, silicon oxide: DSL. Japan Corp., Carplex Bentonite: Wilber Ellis, Gel White H
Synthetic mica: manufactured by Co-op Chemical Co., Ltd., ME100
Flame retardant, hexabromocyclododecane: SAYTEXHP-900, manufactured by Albemarle Corporation
Tris (2,3-dibromopropyl) isocyanurate: manufactured by Nippon Kasei Co., Ltd., TAIC-6B
Phosphate ester tris (tribromoneopentyl) phosphate: manufactured by Daihachi Chemical Co., Ltd., CR-900
・ Triphenyl phosphate: Ajinomoto Fine Techno Co., Ltd., Leophos TPP
Others: Talc: Hayashi Kasei, TALCAN PAWDER PK-Z
Barium stearate: Sakai Chemical Co., Ltd., SB
-Liquid paraffin: Wako Pure Chemical Industries, Ltd. Reagent: Stabilizer: Ciba Specialty Chemicals, IRGANOX B911
(Hindered phenol antioxidant IRGANOX1076: octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and phosphorus stabilizer IRGAFOS168: Tris (2,4-di-t-butylphenyl) ) 1: 1 mixture of phosphites).

Example 1
For 100 parts by weight of polystyrene A, 0.3 parts by weight of silicon oxide as a water-absorbing substance, 1.5 parts by weight of bentonite, 4 parts by weight of hexabromocyclododecane as a flame retardant, 1 part by weight of tris (tribromoneopentyl) phosphate, A blend of 0.2 parts by weight of talc, 0.2 parts by weight of barium stearate, 0.2 parts by weight of stabilizer and 0.2 parts by weight of liquid paraffin was dry blended, and the resulting styrenic resin composition had a diameter of 65 mm. The first extruder and a second extruder having a diameter of 90 mm were fed at a rate of 60 kg / hour to a two-stage extruder connected in series. The styrene-based resin composition supplied to the first extruder is heated to 200 ° C. and melt-kneaded, and polystyrene 100 is used as a foaming agent near the tip of the first extruder (side connected to the second extruder). With respect to parts by weight, 3.5 parts by weight of isobutane, 1.5 parts by weight of dimethyl ether and 1.0 part by weight of water were press-fitted into the melted styrene resin composition. In the second extruder connected to the first extruder, the resin temperature was cooled to 110 ° C., and the styrenic resin composition was extruded into the atmosphere from a die lip provided at the tip of the second extruder. The temperature of the die lip was set to 75 ° C., and the gap was a rectangular cross section having a thickness direction of 1 mm and a width direction of 50 mm. The extruded foam was pulled at a speed 1.11 times the take-off speed to obtain a rectangular solid foam having a thickness of 25 mm and a width of 200 mm.
The obtained foam was evaluated as having a width of 160 mm in which the upper and lower surfaces were provided with a skin, and the portions up to 20 mm in the width direction were cut from both side surfaces.
The evaluation results of the obtained extruded foam are shown in Table 1. Moreover, the SEM image of the cross section along the extrusion direction of an extrusion foam is shown in FIG. 1, and a bubble diameter distribution map is shown in FIG.

As shown in Table 1, since the average bubble diameter in the thickness direction in the bubbles present in the first surface layer portion is 0.04 mm, the condition (a) is satisfied. Since the bubble diameter magnification in the central portion is 3.2 times, the condition (b) is satisfied. Since the bubble aspect ratio in the second surface layer portion is 5, the condition (c) is satisfied. Since the bubble flatness ratio in the central portion is 0.8, the condition (d) is satisfied.
Further, as shown in Table 1, in the bubble diameter distribution chart, the maximum bubble diameter is 0.48 mm, so the condition (e) is satisfied. Since five peaks are confirmed in all sections, the condition (f) is satisfied. Since two of the five peaks are present in a section of less than 0.26 mm, the condition (g) is satisfied. Since the minimum bubble area ratio sum is 0.74, the condition (h) is satisfied. Since the small bubble area ratio sum is 0.77, the condition (i) is satisfied. Among the five peaks, four peaks exist in the section where the bubble diameter is 0.10 mm or more, and three peaks exist in the section where the bubble diameter is larger than the peak where the bubble diameter is the smallest among the four peaks. Condition (j) is satisfied.

  In Example 1, the peak existing in the section where the bubble diameter is 0.06 mm or more and less than 0.08 mm is the first peak in the present invention, and the bubble diameter is present in the section where the bubble diameter is 0.24 mm or more and less than 0.26 mm. The peak is the second peak in the present invention. The peak existing in the section where the bubble diameter is 0.20 mm or more and less than 0.22 mm is the first section in the present invention, and the peak existing in the section where the bubble diameter is 0 mm or more and less than 0.02 mm is the second section in the present invention. It is a section. In addition, the peak existing in the section where the bubble diameter is 0.24 mm or more and less than 0.26 mm is the third peak in the present invention, and the peak existing in the section where the bubble diameter is 0.30 mm or more and less than 0.32 mm is used in the present invention. This is the fourth peak. And the peak which exists in the area where a bubble diameter is 0.26 mm or more and less than 0.28 mm is the 3rd area in the present invention, and the 4th area does not correspond.

Further, as shown in Table 1, the foam density of the entire extruded foam obtained was 41 kg / m ³ , and the foam density in the second surface layer portion was 80 kg / m ³ . The thermal conductivity was 0.0256 W / mK. The amount of foaming agent remaining in the extruded foam was 3.1% by weight of isobutane.

(Example 2)
For 100 parts by weight of polystyrene A, 0.3 parts by weight of silicon oxide as a water-absorbing substance, 1.0 part by weight of bentonite, 5 parts by weight of tris (2,3-dibromopropyl) isocyanurate as a flame retardant, 1 part by weight of triphenyl phosphate Parts of talc, 0.5 parts by weight of talc, 0.2 parts by weight of barium stearate, 0.2 parts by weight of stabilizer and 0.2 parts by weight of liquid paraffin were dry blended, and the resulting styrenic resin composition was obtained. A first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were supplied to a two-stage extruder connected in series at a rate of 60 kg / hour. The styrene-based resin composition supplied to the first extruder is heated to 200 ° C. and melt-kneaded, and polystyrene 100 is used as a foaming agent near the tip of the first extruder (side connected to the second extruder). 4 parts by weight of isobutane, 3 parts by weight of dimethyl ether and 1.0 part by weight of water were press-fitted into the melted styrene resin composition with respect to parts by weight. In the second extruder connected to the first extruder, the resin temperature was cooled to 120 ° C., and the styrene resin composition was extruded into the atmosphere from a die lip provided at the tip of the second extruder. The die lip was set to a temperature of 80 ° C., and was formed as a void having a rectangular cross section with a thickness of 1 mm and a width of 50 mm. The extruded foam was pulled at a rate of 1.20 times the take-off speed to obtain a rectangular parallelepiped foam having a thickness of 25 mm and a width of 200 mm.
The obtained foam was evaluated as having a width of 160 mm in which the upper and lower surfaces were provided with a skin, and the portions up to 20 mm in the width direction were cut from both side surfaces.
The evaluation results of the obtained extruded foam are shown in Table 1. Moreover, the SEM image of the cross section along the extrusion direction of an extrusion foam is shown in FIG. 3, and a bubble diameter distribution map is shown in FIG.

As shown in Table 1, since the average bubble diameter in the thickness direction in the bubbles existing in the first surface layer portion is 0.06 mm, the condition (a) is satisfied. Since the bubble diameter magnification in the central portion is 2.7 times, the condition (b) is satisfied. Since the bubble aspect ratio in the second surface layer portion is 7, the condition (c) is satisfied. Since the bubble flatness ratio in the central portion is 1.3, the condition (d) is satisfied.
Further, as shown in Table 1, in the bubble diameter distribution chart, the maximum bubble diameter is 0.60 mm, which satisfies the condition (e). Since 8 peaks are confirmed in all sections, the condition (f) is satisfied. Since 3 of the 8 peaks are present in a section of less than 0.26 mm, the condition (g) is satisfied. Since the minimum bubble area ratio sum is 0.13, the condition (h) is satisfied. Since the small bubble area ratio sum is 0.55, the condition (i) is satisfied. Among the above 8 peaks, the 8 peak exists in the section where the bubble diameter is 0.10 mm or more, and the 7 peak exists in the section where the bubble diameter is larger than the peak where the bubble diameter is the smallest among the 8 peaks. Condition (j) is satisfied.

  In Example 1, the peak existing in the section where the bubble diameter is 0.10 mm or more and less than 0.12 mm is the first peak in the present invention, and the bubble diameter is present in the section where the bubble diameter is 0.16 mm or more and less than 0.18 mm. The peak is the second peak in the present invention. The peak existing in the section where the bubble diameter is 0.12 mm or more and less than 0.14 mm is the first section in the present invention, and the peak existing in the section where the bubble diameter is 0 mm or more and less than 0.02 mm is the second section in the present invention. It is a section. In addition, the peak existing in the section where the bubble diameter is 0.24 mm or more and less than 0.26 mm is the third peak in the present invention, and the peak existing in the section where the bubble diameter is 0.32 mm or more and less than 0.34 mm is used in the present invention. This is the fourth peak. And the peak which exists in the area where a bubble diameter is 0.26 mm or more and less than 0.28 mm is the 3rd area in the present invention, and the 4th area does not correspond.

Further, as shown in Table 1, the foam density of the entire extruded foam obtained was 36 kg / m ³ , and the foam density in the second surface layer portion was 61 kg / m ³ . The thermal conductivity was 0.0256 W / mK. The amount of foaming agent remaining in the extruded foam was 3.5% by weight of isobutane.

(Comparative Example 1)
A blend of 1.5 parts by weight of synthetic mica as a water-absorbing substance, 3 parts by weight of hexabromocyclododecane as a flame retardant, and 1.0 part by weight of talc was dry blended with 100 parts by weight of polystyrene B, and the resulting styrene system The resin composition was supplied at a rate of 35 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series. The styrene-based resin composition supplied to the first extruder is heated to 200 ° C. and melt-kneaded, and polystyrene 100 is used as a foaming agent near the tip of the first extruder (side connected to the second extruder). 3 parts by weight of butane, 6 parts by weight of dimethyl ether and 1.0 part by weight of water were press-fitted into the melted styrene resin composition with respect to parts by weight. In the second extruder connected to the first extruder, the resin temperature is cooled to 120 ° C., and the styrenic resin composition is extruded into the atmosphere from a die lip provided at the tip of the second extruder. A rectangular parallelepiped foam having a width of 200 mm was obtained. The temperature of the die lip was set to 85 ° C., and the gap was a rectangular cross section having a thickness direction of 1.2 mm and a width direction of 50 mm.
The obtained foam was evaluated as having a width of 160 mm in which the upper and lower surfaces were provided with a skin, and the portions up to 20 mm in the width direction were cut from both side surfaces.
The evaluation results of the obtained extruded foam are shown in Table 1. As shown in Table 1, since the bubble diameter magnification at the center is 2, the condition (b) is not satisfied. The obtained extruded foam had a thermal conductivity of 0.0284 W / mK.

  Extrusion foam molding was performed in the same manner as in Example 1 except that no water-absorbing substance was added, but a good extruded foam was not obtained.

  When the styrene resin extruded foam is used as, for example, a heat insulating material for a building material, a cold box or a cold car, the thermal conductivity is preferably 0.0260 W / mK or less. In Examples 1 and 2, it was confirmed that such heat insulation performance was satisfied, and that in Comparative Example 1 was not satisfied.

1 is a view showing an SEM image of a cross section along the extrusion direction in Example 1. FIG. FIG. 2 is a bubble diameter distribution diagram in the first embodiment. 3 is a view showing an SEM image of a cross section along the extrusion direction in Example 2. FIG. FIG. 4 is a bubble diameter distribution diagram in the second embodiment.

Claims (12)

A styrene resin extruded foam obtained by extrusion foaming a styrene resin composition containing a foaming agent, which satisfies all of the following conditions (a), (b), and (C):
In addition, a predetermined range of the cross section along the extrusion direction and the cross section along the width direction of the styrene-based resin extruded foam is sampled, the bubble diameter and area of each bubble in the obtained sample cross section are obtained, and the horizontal axis is 0 mm. In the bubble diameter distribution diagram in which the bubble diameter is divided into sections of 0.02 mm from the maximum bubble diameter to the maximum bubble diameter, and the vertical axis is the area ratio of each section obtained by the following formula (1), the following condition (e), A styrene resin extruded foam that satisfies all of the conditions (f) and (g) .
Condition (a): The average cell diameter in the thickness direction of the bubbles existing in the first surface layer portion from the surface perpendicular to the thickness direction of the styrene resin extruded foam to 4 mm in the thickness direction is 0.01 to 0.15 mm. is there.
Condition (b): The average cell diameter in the thickness direction of the bubbles present in the central portion in the thickness direction excluding the first surface layer portion of the styrene resin extruded foam is the average cell diameter present in the first surface layer portion. 2.50 times or more and 5.00 times or less.
Condition (c): ratio of the average cell diameter in the thickness direction to the average cell diameter in the extrusion direction in the bubbles existing in the second surface layer portion from the surface orthogonal to the thickness direction of the styrene resin extruded foam to 2 mm in the thickness direction Is 1.2-10.
Formula (1): Area ratio for each section = sum of the areas of bubbles having bubble diameters belonging to the section / sum of the areas of all bubbles
Condition (e): The maximum value of the bubble diameter section having the area ratio is 0.26 mm or more.
Condition (f): The area ratio in all sections of the bubble diameter has a plurality of peaks.
Condition (g): At least one of the plurality of peaks has a section where the bubble diameter is less than 0.26 mm. Furthermore, the styrene-type resin extrusion foam of Claim 1 which satisfy | fills the following conditions (d).
Condition (d): The ratio of the average bubble diameter in the thickness direction to the average bubble diameter in the extrusion direction in the bubbles existing in the central portion is 0.2-2.   The styrene resin extruded foam according to claim 1 or 2, wherein the styrene resin extruded foam has a skin on the surface. Furthermore, the styrene resin extrusion foam in any one of Claims 1-3 which satisfy | fills the following conditions (h).
Condition (h): a first peak existing in a section where the bubble diameter is smaller than any of the other peaks among the sections where the bubble diameter is less than 0.26 mm, and a section where the bubble diameter is larger than the first peak The area included from the first section having the lowest area ratio present between the first peak and the second peak closest to the first peak to the second section having a bubble diameter of 0 mm or more and less than 0.02 mm. The sum of the ratios is 0.1 to 0.9. The styrenic resin composition comprises, as a foaming agent, (a) one or more saturated hydrocarbons having 3 to 5 carbon atoms, and (ro) dimethyl ether, diethyl ether, methyl ethyl ether, chloride, as necessary. The styrene resin extruded foam according to any one of claims 1 to 4 , which comprises a compound selected from alkyl and (c) other non-halogen foaming agent. One or more of the above-mentioned saturated hydrocarbon carbon number of 3 to 5, propane, n- butane, are those selected from the group consisting of i- butane, styrene resin extruded foam according to claim 5. The styrene resin extruded foam according to claim 5 , wherein the other non-halogen foaming agent is selected from the group consisting of water, carbon dioxide, and alcohol. The foaming agent contains water as the other non-halogen-based foaming agent,
The styrenic resin composition comprises 0.01 to 10% by weight of one or more water-absorbing substances selected from the group consisting of layered silicates, silicon oxides, sulfates, carbonates, phosphates and zeolites. The styrene resin extruded foam according to any one of claims 5 to 7 , which is contained. The styrene resin extruded foam according to any one of claims 1 to 8 , wherein the styrene resin extruded foam has a thermal conductivity of 0.0260 W / mK or less. The styrene resin extruded foam according to any one of claims 1 to 9 , wherein the styrene resin extruded foam has a plane compressive strength of 15 N / m ² or more. The styrene resin extruded foam according to any one of claims 1 to 10 , wherein the foam density of the styrene resin extruded foam is 30 to 60 kg / m ³ . The styrene resin extruded foam according to any one of claims 1 to 11 , wherein the styrene resin extruded foam has a thickness of 10 to 150 mm.