JP2008274115A - Styrenic resin extruded foam and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a styrenic resin extruded foam having an excellent heat insulating performance and an appropriate compression strength for construction materials and industrial materials. <P>SOLUTION: The styrenic resin extruded foam having an excellent heat insulating performance and an appropriate compression strength for construction materials and industrial materials can be obtained by making a cell structure having a specific average cell diameter in three directions and a specific cell anisotropy ratio in the thickness direction with the use of a blowing agent comprising a 3-5C saturated hydrocarbon and an alkyl chloride. <P>COPYRIGHT: (C)2009,JPO&INPIT

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.

  There is already known a method for continuously producing a foam by melting a styrenic resin with an extruder or the like, then adding a foaming agent, cooling it, and extruding it into a low pressure region. Styrenic resin foams are used as, for example, heat insulating materials for structures because of good workability and heat insulating properties.

  Conventionally, as blowing agents for styrene-based resin foams, so-called chlorofluorocarbons and hydrocarbons have been proposed or used industrially. For example, regarding chlorofluorocarbons, chlorofluorocarbons (CFCs) containing chlorine atoms tend to form good foams, tend to remain in the foams, and have low thermal conductivity. Sex has been used to contribute to expression. However, in recent years, the CFC has been avoided because it is a causative substance that destroys the ozone layer.

  In response to these circumstances, various attempts have been proposed to satisfy environmental compatibility. As alternatives to CFC, methods using hydrochlorofluorocarbon (HCFC) in which some of the chlorine atoms of CFC are substituted with hydrogen atoms or hydrofluorocarbons (HFC) not containing chlorine atoms have been proposed. However, chlorofluorocarbons such as HFC and HCFC have a smaller effect on the ozone layer than CFC, but on the other hand, the effect on global warming is still large, and therefore, reduction of the usage is desired.

  Under such circumstances, environmental compatibility is achieved by combining isobutane and normal butane with low permeability to styrene resin, zero ozone depletion coefficient and low global warming potential, and using as a blowing agent. Techniques for obtaining excellent foams are becoming common.

  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 order to solve the above problem, by using water as a foaming agent and adjusting the type of additive, extrusion foaming molding conditions, etc., a characteristic cell structure in which small bubbles and large bubbles are mixed in a sea-island shape is formed. Techniques for obtaining a foam having the same are disclosed (Patent Documents 1 to 3). Accordingly, a method is disclosed in which even if a hydrocarbon is used as a foaming agent, a foam having excellent heat insulation, light weight, and good extrusion foam moldability can be obtained.

However, further improvement in heat insulation performance is required, and compatibility with mechanical properties such as compressive strength is also required, and further improvement is desired.
JP 2001-854630 A Japanese Patent Laid-Open No. 2002-85918 JP 2004-175862 A

  Under such circumstances, the problem to be solved by the present invention is to obtain a styrene resin extruded foam having extremely excellent heat insulation performance and having appropriate strength for building materials and industrial materials. .

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and as a result, the three-direction average bubble diameter and thickness are not limited to the characteristic bubble structure in which large bubbles and small bubbles are mixed in a sea-island shape. By strictly controlling the bubble anisotropy rate in the direction, it is possible to obtain a styrenic resin extruded foam that can obtain extremely excellent heat insulation and can exhibit compressive strength that can be used for building materials and industrial materials. I found it. In order to obtain these characteristics, it is preferable to contain a saturated hydrocarbon having 3 to 5 carbon atoms as a foaming agent. Furthermore, in order to express these cell structures and stably perform extrusion foam molding, the foaming agent As a result, it has been found that it is desirable to include methyl chloride and alkyl chloride of ethyl chloride, and the present invention has been completed.

That is, this invention provides the following styrene-type resin extrusion foam and its manufacturing method.
[1] A styrene resin extruded foam obtained by extruding and foaming a styrene resin composition to which a foaming agent has been added, which is obtained by the following formula (1) of the bubbles constituting the styrene resin foam 3 The directional average bubble diameter is 0.02 to 0.15 mm, the bubble anisotropy rate in the thickness direction obtained by the following formula (2) is 0.5 to 1.1, and the foam is formed by the method of JIS A9511. A styrene resin extruded foam characterized by having a measured thermal conductivity of 0.024 W / mK or less and a compressive strength of 15 N / cm ² or more.
Formula (1): 3-direction average bubble diameter = ((average bubble diameter in thickness direction) × (average bubble diameter in width direction) × (average bubble diameter in length direction)) ^(1/3)
Formula (2): Thickness direction bubble anisotropy rate = Thickness direction average cell diameter / 3 direction average cell diameter [2] The above foaming agent contains a saturated hydrocarbon having 3 to 5 carbon atoms [1] The styrene resin extruded foam described.
[3] The styrene resin extruded foam according to item [2], wherein the saturated hydrocarbon is at least one selected from the group consisting of propane, n-butane and i-butane.
[4] The styrene resin extruded foam according to any one of [1] to [3], wherein the foaming agent contains methyl chloride or alkyl chloride of ethyl chloride.
[5] The styrene resin extruded foam according to any one of [1] to [4], wherein the foaming agent further contains water or carbon dioxide.
[6] The styrene resin extruded foam according to any one of [1] to [5], wherein the foam density of the styrene resin extruded foam is 30 to 65 kg / m ³ .
[7] The styrene resin extruded foam according to any one of [1] to [6], wherein the styrene resin extruded foam has a thickness of 10 to 150 mm.
[8] The styrene resin extruded foam according to any one of [1] to [7], wherein the styrene resin extruded foam has a skin.
[9] A method for producing a styrene resin foam in which a styrene resin is heated and melted, a foaming agent is added to the styrenic resin, and extrusion foamed in a low pressure region, and the foaming agent has 3 to 5 carbon atoms. Saturated hydrocarbon and alkyl chloride are used, The manufacturing method of the styrene resin foam of any one of the items [1] to [8].

  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 styrene monomers such as styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, bromo styrene, chloro styrene, vinyl toluene, and vinyl xylene are used alone. A polymer or a copolymer comprising a combination of two or more of these monomers; the styrene monomer and divinylbenzene, butadiene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile And a copolymer obtained by copolymerizing at least one monomer such as maleic anhydride 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.

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

  Furthermore, the styrene resin used in the present invention is a styrene resin having a branched structure for the purpose of adjusting the melt flow rate (hereinafter abbreviated as “MFR”), the melt viscosity at the time of molding, the melt tension, and the like. May be.

  As a styrene resin of this invention, it is preferable from the following points to use the thing of MFR 0.1-50g / 10min. That is, it is excellent in molding processability at the time of extrusion foam molding, and it is easy to adjust the discharge amount at the time of molding process, the thickness and width, density or closed cell ratio of the obtained thermoplastic resin foam to a desired value (i.e. A thermoplastic foam with excellent extrusion foaming moldability) and appearance, etc., as well as a balance of mechanical strength such as compressive strength, bending strength or bending deflection, and properties such as toughness. What has MFR of the said range is preferable from the point from which a resin foam is obtained. Further, the MFR of the styrenic resin is more preferably 0.3 to 30 g / 10 minutes, and 0.5 to 20 g / 10 minutes from the viewpoint of the balance of molding processability and mechanical strength against foamability, toughness and the like. Further preferred. In addition, MFR of the styrene resin in this invention is measured by A method and test condition H of JIS K7210 (1999).

  In the present invention, among the styrenic resins described above, a polystyrene resin can be particularly suitably used from the viewpoint of economy and processability. 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 styrene resins may be used alone, or two or more styrene resins having different copolymerization components, molecular weight, molecular weight distribution, branched structure, MFR and the like may be used in combination.

  As the foaming agent in the present invention, (i) at least one saturated hydrocarbon selected from saturated hydrocarbons having 3 to 5 carbon atoms, and (ro) at least one selected from methyl chloride and ethyl chloride as necessary. And (c) those containing at least one selected from water and carbon dioxide.

  In the present invention, the combined use of the foaming agents (a), (b), and (c) above gives the thickness, width, density, closed cell ratio, thermal conductivity of the obtained styrene resin extruded foam. It becomes easy to adjust the rate, bubble diameter, and surface property to desired values. That is, it is excellent in the moldability of the extruded foam. In particular, it is possible to use (a) a saturated hydrocarbon having 3 to 5 carbon atoms and (b) at least one alkyl chloride blowing agent selected from the group consisting of methyl chloride and ethyl chloride. It is preferable to obtain

  Examples of the saturated hydrocarbon having 3 to 5 carbon atoms include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, and cyclopentane. At least one selected from the group consisting of n-butane and i-butane is preferred. Moreover, since the heat insulation of an extrusion foam becomes favorable, at least 1 sort (s) chosen from n-butane and i-butane is preferable, Especially preferably, it is i-butane.

  The content of the saturated hydrocarbon having 3 to 5 carbon atoms as the foaming agent is preferably 100 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 foaming agent. 40% by weight. By making content of C3-C5 saturated hydrocarbon into the said range, it can be made to use together with high heat insulation and appropriate intensity | strength to an extrusion foam. When the amount of the saturated hydrocarbon having 3 to 5 carbon atoms is less than the above range, the heat insulating property of the obtained foam may be inferior.

The content of the alkyl chloride compound as the foaming 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 foaming agent. By making content of an alkyl chloride compound into the said range, high heat insulation, a flame retardance, and a moldability can be used together for an extrusion foam.
When the amount of alkyl chloride exceeds the above range, the plasticity is too high, the kneading state of the styrene resin and the foaming agent in the extruder becomes non-uniform, and the pressure control of the extruder tends to be difficult.
On the other hand, if the amount of alkyl chloride is less than the above range, the plasticity tends to be insufficient and the extrusion tends to become unstable.

  In the present invention, by using at least one selected from the group consisting of water and carbon dioxide as a foaming agent, it becomes easy to obtain a preferable fine-cell foam.

  The content of water as the foaming agent is preferably 0 to 80% by weight, more preferably 3 to 70% by weight, still more preferably 3 to 30% by weight based on 100% by weight of the total amount of the foaming agent. ˜20% by weight is particularly preferred. By setting the water content in the above range, high heat insulating properties and moldability can be combined, and an extruded foam having a good surface can be obtained.

  When water is used as the foaming agent, it is preferable to add a water-absorbing substance in order to stably perform extrusion foaming. A water-absorbing substance refers to 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.

  As a specific example of the water-absorbing substance, a particle diameter of 1000 nm or less having a hydroxyl group on the surface such as anhydrous silica (silicon oxide) having a silanol group on the surface (for example, AEROSIL manufactured by Nippon Aerosil Co., Ltd. is commercially available). Fine powder; water-absorbing or water-swelling layered silicates such as smectite, swellable fluorinated mica, or organically treated products thereof; zeolite, activated carbon, alumina, silica gel, porous glass, activated clay, diatomaceous earth, etc. Porous substances; sulfates such as sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, barium sulfate, aluminum sulfate, zinc sulfate, ammonium sulfate; carbonates such as sodium carbonate, sodium hydrogen carbonate, magnesium carbonate, ammonium carbonate; phosphoric acid Sodium, magnesium phosphate, phosphate Phosphate such as minium, ammonium phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, triammonium phosphate, calcium dihydrogen phosphate, calcium hydrogen phosphate; calcium citrate, citric acid Metal salts such as trisodium, tripotassium citrate, calcium lactate, ammonium oxalate, potassium oxalate, disodium succinate, sodium acetate, sodium pyrophosphate, magnesium chloride, barium chloride; boron such as boron oxide and sodium borate Compound: Polyacrylate polymer, starch-acrylic acid graft copolymer, polyvinyl alcohol polymer, vinyl alcohol-acrylate copolymer, ethylene-vinyl alcohol copolymer, polyacrylonitrile-methacrylic acid Methyl-bu Diene-based copolymer, such as water-absorbing polymers such as polyethylene oxide copolymer and derivatives thereof. A water absorbing substance may be used independently and may use 2 or more types together.

  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 styrene-based resin composition, 0.1-8 weight part is more preferable, and 0.2-7 weight part is further 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 it 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.

  When carbon dioxide is used as the foaming agent, the content of carbon dioxide is preferably 3 to 40% by weight and more preferably 5 to 30% by weight with respect to 100% by weight of the total amount of foaming 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 in combination as the foaming agent. 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 -Ketones exemplified by butyl ketone, methyl n-amyl ketone, methyl n-hexyl ketone, ethyl n-propyl ketone, ethyl n-butyl ketone, inorganic foaming agents such as nitrogen, argon and helium, azo compounds Include chemical blowing agents such as tetrazoles.

  The addition amount of the other foaming agent in the styrene resin extruded foam may be appropriately determined in consideration of heat insulation, foam moldability, and foam density, but 0 to 4 with respect to 100 parts by weight of the styrene resin composition. Part by weight is preferable, and 0 to 3 parts by weight is more preferable.

  The total amount of the foaming agent relative to the styrene resin is preferably 4.5 to 10 parts by weight with respect to 100 parts by weight of the styrene resin composition.

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

Examples of the halogen-based 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, pentabromodipentaerythritol, Brominated aliphatic compounds such as hexabromodipentaerythritol, hexabromotripentaerythritol, polybrominated polypentaerythritol, etc. Is a derivative thereof, or a brominated alicyclic compound or a derivative thereof; (b) hexabromobenzene, pentabromotoluene, ethylenebispentabromodiphenyl, decabromodiphenyl ether, octabromodiphenyl ether, bis (2,4,6-tribromo Brominated aromatic compounds such as phenoxy) 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 Tribromophenol adduct of tetrabromobisphenol A diglycidyl ether, 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 brominated bisphenols and derivatives thereof; (d) tetrabromobisphenol A polycarbonate Oligomers, brominated bisphenol derivatives oligomers such as tetrabromobisphenol A diglycidyl ether and brominated bisphenol adduct epoxy oligomers; (e) pentabromoben Brominated acrylic resins such as diacrylate polymers; (f) ethylene bistetrabromophthalimide, ethylene bisdibromonorbornane dicarboximide, 2,4,6-tris (2,4,6-tribromophenoxy) 1,3,5 Bromine and nitrogen atom containing compounds such as triazine, tris (2,3-dibromopropyl) isocyanurate; (g) bromine and phosphorus atom containing compounds such as tris (tribromoneopentyl) phosphate, tris (bromophenyl) phosphate; (H) Chlorinated compounds such as chlorinated paraffin, chlorinated naphthalene, perchloropentadecane, chlorinated aromatic compounds, chlorinated alicyclic compounds; (i) brominated inorganic compounds such as ammonium bromide, etc. It is done.
These compounds may be used alone or in combination of two or more. 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 that it contains.

  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. More preferably, the amount is more preferably 1 to 20 parts by weight, still more preferably 1 to 15 parts by weight, and particularly preferably 2 to 8 parts by weight with respect to 100 parts by weight of the styrenic resin. When the content of the halogen-based flame retardant is less than 0.1 parts by weight, the foam tends to have poor properties such as intended flame retardancy. On the other hand, when the content exceeds 20 parts by weight, In some cases, the heat resistance and surface properties of the resulting foam, stability during foam production, and the like 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 the flame retardant aid that exhibits a synergistic effect with the halogen flame retardant include iron-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, sulfur-containing compounds, and the like, specifically, 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 and isocyanuric acid and their derivatives as the nitrogen-containing compound, boron oxide as the boron-containing compound and sulfur-containing compound as Sulfanilic acid and its derivatives are preferred.

  The content of the flame retardant auxiliary that shows a synergistic effect with the halogen flame retardant in the styrene resin foam depends on the type of the flame retardant auxiliary that shows a synergistic effect with the halogen flame retardant, but is 100 parts by weight of the styrene resin. On the other hand, 0.0001-10 weight part is preferable, 0.001-8 weight part is more preferable, 0.01-5 weight part is further more preferable. When the content of the flame retardant aid is outside these ranges, the synergistic effect with the halogen flame retardant tends to be poor.

In the present invention, various silica, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate, etc., as necessary, within a range not inhibiting the effects of the present invention. Processing aids such as inorganic compounds, sodium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin wax, stearylamide compound, phenolic antioxidant, phosphorus stabilizer, nitrogen stabilizer, sulfur It may contain additives such as stabilizers, light-resistant stabilizers such as benzotriazoles and hindered amines, flame retardants other than those mentioned above, antistatic agents, and coloring agents such as pigments.
The extruded foam of the styrenic resin according to the present invention has either a uniform bubble structure or a characteristic bubble structure in which small bubbles (small bubbles) and large bubbles (large bubbles) are mixed in a sea-island shape. However, if the specified parameter range is satisfied, extremely excellent heat insulation performance and appropriate compressive strength can be exhibited.

In the styrene resin extruded foam according to the present invention, the three-direction average cell system obtained by the following formula (1) is preferably 0.02 to 0.15 mm, more preferably 0.05 to 0.12 mm, 0.05-0.1 mm is more preferable. By setting the three-direction average bubble diameter in the above range, the heat insulation can be greatly improved.
Formula (1): 3-direction average bubble diameter = ((average bubble diameter in thickness direction) × (average bubble diameter in width direction) × (average bubble diameter in length direction)) ^(1/3)

The styrene resin extruded foam according to the present invention preferably has a cell anisotropy ratio in the thickness direction of 0.5 to 1.1 determined by the following formula (2), and is 0.6 to 1.1. Is more preferable, and 0.7 to 1.1 is more preferable. By setting the bubble anisotropy rate within the above range, both heat insulation and balance can be achieved without reducing the compressive strength.
Formula (2): Thickness direction bubble anisotropy rate = Thickness direction average bubble diameter / 3 direction average bubble diameter

  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.

  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 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 used styrenic resin is melted, but the temperature at which the 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. 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. 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, that 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 molding is in close contact with or in contact with the slit die. A method of molding 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. The desired cross-sectional shape of the foam, the surface property of the foam, and the foam quality can be obtained by adjusting the flow surface shape and the mold temperature of the molding die.

  As a method for adjusting the cell diameter of the styrene resin extruded foam, a saturated hydrocarbon having 3 to 5 carbon atoms, particularly methyl chloride, alkyl chloride of ethyl chloride, and water and carbon dioxide are used as a foaming agent. It can be adjusted by the amount of each foaming agent used, molding conditions for extrusion foaming (for example, pressure conditions during foaming), and the like.

  As a method for controlling the bubble anisotropy rate, for example, a method of adjusting the thickness expansion rate when foaming the molten resin into the atmosphere at the time of extrusion foaming, that is, a slit thickness and a molding die for rectangularization There is a method of adjusting the clearance. Or the method of extending | stretching, heating an extruded foam is mentioned. Specifically, while heating the extruded foam with heated air, the roll is rotated faster than the rotation speed of the take-up machine while heating the resulting extruded foam using a heating and stretching device that performs stretching with a roll. Then, a stretching process is performed. Thereby, an extrusion foam is extended | stretched in an extrusion direction and the said bubble anisotropic rate becomes small.

  The styrene resin extruded foam according to the present invention is measured according to JIS A9511 on the seventh day after production, considering that it functions as, for example, a heat insulating material for buildings, a cold storage or a cold car. The thermal conductivity is preferably 0.028 W / mK or less, more preferably 0.026 W / mK or less, and still more preferably 0.024 W / mK or less.

The density of the styrene-based resin extruded foam according to the present invention is foamed from the viewpoint of heat insulation and light weight, for example, when considering that it functions as a heat insulator for a building, a cold storage or a cold car, preferably the density of the body is 30~65kg / ^{m 3,} more preferably 35~55kg / ^{m 3.}

  The thickness of the styrene-based resin extruded foam according to the present invention is, for example, in view of functioning as a heat insulating material for a building, a cold storage or a cold car, in terms of heat insulating properties, bending strength, and compressive strength. Therefore, it is preferably 10 to 150 mm, more preferably 15 to 120 mm, and particularly preferably 20 to 100 mm.

  The styrene-based resin extruded foam according to the present invention has a skin on the surface from the viewpoint of heat insulation considering that it functions as, for example, a heat insulating material for buildings, a cold storage or a cold storage vehicle. Is preferred.

  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 foaming agents such as butane are 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.

  As a method of attaching the skin to the foam surface in the present invention, a molding die installed in close contact with or in contact with the slit die, a molding roll installed adjacent to the downstream side of the molding die, and the like are used. There is a method of cooling and solidifying the foam surface layer while smoothening the elongation of the resin on the foam surface layer when molding the plate-like foam. Specifically, surface treatment is applied to the flow surface of the molding die so as to reduce the frictional resistance generated between the foam and the molding die as much as possible, or by appropriately setting the molding die temperature. be able to.

  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.

  For Examples 1 to 4 and Comparative Examples 1 to 2, the foam density, thermal conductivity, compressive strength, three-direction average bubble diameter, and thickness direction bubble anisotropy rate were evaluated according to the following methods.

(1) Foam density (kg / m ³ )
A styrene resin extruded foam is cut into a rectangular parallelepiped shape of about 200 mm (extrusion direction) × 100 mm (width direction) × extrusion thickness (thickness direction), and the weight is measured. The dimension was measured. The foam density was determined from the measured weight and each dimension based on the following formula, and the unit was converted to kg / m ³ .
Foam overall density (g / cm ³ ) = foam weight (g) / foam volume (cm ³ )

(2) Thermal conductivity (W / mK)
The thermal conductivity of the styrene resin extruded foam 7 days after production was measured according to JIS A9511.

(3) Compressive strength The compressive strength of the styrene resin extruded foam 7 days after production was measured according to JIS A9511.

(4) Three-direction average cell diameter Cross section (hereinafter referred to as a transverse section) of the foam cut vertically (thickness direction) along the width direction and a cross section cut perpendicularly (thickness direction) along the length direction An appropriate part (hereinafter referred to as a longitudinal section) is sampled, the part is magnified 30 times with a scanning electron microscope (SEM), a photograph is taken, and an average bubble diameter (mm) in the thickness direction is taken from this photograph. ), The average cell diameter in the width direction (mm) and the average cell diameter in the length direction (mm) were measured according to ASTM D-3576. The actual size of the photographed part was about 5 mm × 5 mm. The average cell (mm) in the thickness direction was determined from both the cross section and the vertical section. The sampling position may be sampled anywhere in the foam, except for the special cell structure at the end of the foam. From the numerical value, the three-direction average bubble diameter (mm) was obtained based on the formula (1).
Formula (1): 3-direction average bubble diameter = ((average bubble diameter in thickness direction) × (average bubble diameter in width direction) × (average bubble diameter in length direction)) ^(1/3)

(5) Bubble anisotropy rate in the thickness direction Based on the formula (2), using the numerical values of the average bubble diameter (mm) and the three-direction average bubble diameter (mm) in the thickness direction of the foam bubbles obtained as described above. The thickness direction bubble anisotropy was determined.
Formula (2): Thickness direction bubble anisotropy rate = Thickness direction average bubble diameter / 3 direction average bubble diameter

Example 1
Hexabromocyclododecane (Albemarle Corporation, trade name: SAYTEX HP-900) as a halogen-based flame retardant with respect to 100 parts by weight of polystyrene (PS Japan Corporation, trade name: G9401, MFR = 2.5 g / 10 min) ) 4.5 parts by weight, talc (Hayashi Kasei Co., Ltd., trade name: Talcan powder) 1.0 part by weight, barium stearate (Sakai Chemical Industry Co., Ltd., trade name: barium stearate) 0.5 part by weight and epoxy A mixture of 0.2 parts by weight of a resin (Asahi Denka Kogyo Co., Ltd., trade name: EP-13) was dry blended to obtain a styrene resin composition. The styrenic resin composition is fed into a two-stage extruder in which a first extruder, which is a single-screw extruder having a diameter of 65 mm, and a second extruder, which is a single-screw extruder having a diameter of 90 mm, are connected in series to a 50 kg / Feeded with Hr. The styrenic resin composition supplied to the first extruder is heated and kneaded at about 200 ° C., and polystyrene is used as a foaming agent in the vicinity of the tip of the first extruder (side connected to the second extruder). 2 parts by weight of carbon dioxide, 4 parts by weight of isobutane and 3 parts by weight of ethyl chloride were press-fitted into the melted styrene-based resin composition with respect to 100 parts by weight of the resin. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 8-20 MPa, and the press injection pressure of the foaming agent was set to this resin pressure + 0.5-3 MPa. In the second extruder connected to the first extruder, the resin temperature of the molten styrene resin composition containing the foaming agent is cooled to about 110 to 130 ° C., and the styrene is removed from the die lip provided at the tip of the second extruder. A cross-sectional shape having a thickness of about 40 mm and a width of about 150 mm, using a molding die placed in close contact with a die and a molding roll placed downstream of the molding die. Extruded foam having an outer skin was obtained.
Table 1 shows the evaluation results of the obtained extruded foam.
As shown in Table 1, the foam density of the obtained extruded foam was 42 kg / m ³ , the thermal conductivity measured according to JIS A9511 was 0.023 W / mK, and the compressive strength was 20 N / cm. ² . Further, from the measurement result that the average bubble diameter in the thickness direction is 0.04 mm, the average bubble diameter in the width direction is 0.04 mm, and the average bubble diameter in the length direction is 0.07 mm, the three-direction average bubble diameter is 0.05 mm. The bubble anisotropy rate in the thickness direction was 0.83.

(Example 2)
The composition of the resin composition is 4 parts by weight of hexabromocyclododecane as a halogen-based flame retardant, 1.0 part by weight of talc, 0.5 part by weight of barium stearate, 100 parts by weight of polystyrene, tris (tributyl neopentyl). ) Phosphate (Daihachi Chemical Co., Ltd., trade name: CR-900) 1 part by weight and epoxy resin 0.2 parts by weight. The foaming agent composition is 100 parts by weight of polystyrene resin and carbon dioxide 1 Extruded foam was obtained in the same manner as in Example 1, except that the content was 0.5 parts by weight, 4 parts by weight of isobutane, and 2.5 parts by weight of ethyl chloride. The evaluation results are shown in Table 1.
As shown in Table 1, the foam density of the obtained extruded foam is 46 kg / m ³ , the thermal conductivity measured according to JIS A9511 is 0.024 W / mK, and the compressive strength is 26 N / cm. ² . Further, from the measurement results that the average bubble diameter in the thickness direction is 0.05 mm, the average bubble diameter in the width direction is 0.04 mm, and the average bubble diameter in the length direction is 0.07 mm, the three-direction average bubble diameter is 0.05 mm. The bubble direction anisotropy rate in the thickness direction was 0.96.

(Example 3)
The composition of the resin composition is 4 parts by weight of hexabromocyclododecane as a halogen flame retardant, 0.5 parts by weight of talc, 0.5 parts by weight of barium stearate, 100% by weight of polystyrene, bentonite (Hojun Co., Ltd.) , Trade name: Bengel 23) 1 part by weight, tris (tributylneopentyl) phosphate 1 part by weight and epoxy resin 0.2 part by weight, and the foaming agent composition is water based on 100 parts by weight of polystyrene resin. Extruded foam was obtained in the same manner as in Example 1, except that 0.6 part by weight, 4.5 parts by weight of isobutane and 3 parts by weight of ethyl chloride were used. The evaluation results are shown in Table 1.
As shown in Table 1, the foam density of the obtained extruded foam is 50 kg / m ³ , the thermal conductivity measured in accordance with JIS A9511 is 0.023 W / mK, and the compressive strength is 28 N / cm. ² . In addition, from the measurement result that the average bubble diameter in the thickness direction is 0.08 mm, the average bubble diameter in the width direction is 0.11 mm, and the average bubble diameter in the length direction is 0.14 mm, the three-direction average bubble diameter is 0.11 mm. The bubble anisotropy rate in the thickness direction was 0.75.

Example 4
The composition of the resin composition is 4 parts by weight of hexabromocyclododecane as a halogen-based flame retardant, 0.5 parts by weight of talc, 0.5 parts by weight of barium stearate, 1 part by weight of bentonite and 100 parts by weight of polystyrene. The mixture was composed of 0.2 parts by weight of an epoxy resin, and the blowing agent composition was 0.6 parts by weight of water, 1.5 parts by weight of carbon dioxide, 4 parts by weight of isobutane and 3 parts of ethyl chloride with respect to 100 parts by weight of polystyrene resin. Extruded foam was obtained in the same manner as in Example 1 except that the amount was changed to 5 parts by weight. The evaluation results are shown in Table 1.
As shown in Table 1, the foam density of the obtained extruded foam is 47 kg / m ³ , the thermal conductivity measured according to JIS A9511 is 0.023 W / mK, and the compressive strength is 30 N / cm. ² . Further, from the measurement results of the average cell diameter in the thickness direction of 0.11 mm, the average cell diameter in the width direction of 0.13 mm, and the average cell diameter in the length direction of 0.09 mm, the three-direction average cell diameter is 0.11 mm. The bubble direction anisotropy rate in the thickness direction was 1.01.

(Comparative Example 1)
The composition of the resin composition was 4.5 parts by weight of hexabromocyclododecane as a halogen-based flame retardant, 1.0 part by weight of talc, 0.5 part by weight of barium stearate, and epoxy resin 0 with respect to 100 parts by weight of polystyrene. Extrusion was carried out in the same manner as in Example 1, except that the mixture was 2 parts by weight and the foaming agent composition was 4 parts by weight of isobutane and 3 parts by weight of ethyl chloride with respect to 100 parts by weight of polystyrene resin. A foam was obtained. The evaluation results are shown in Table 1.
As shown in Table 1, the foam density of the obtained extruded foam is 43 kg / m ³ , the thermal conductivity measured according to JIS A9511 is 0.026 W / mK, and the compressive strength is 25 N / cm. ² . Further, from the measurement results of the average bubble diameter in the thickness direction of 0.36 mm, the average bubble diameter in the width direction of 0.34 mm, and the average bubble diameter in the length direction of 0.34 mm, the three-direction average bubble diameter is 0.35 mm, The thickness direction bubble anisotropy was 1.04.

(Comparative Example 2)
The composition of the resin composition is 4 parts by weight of hexabromocyclododecane, 0.5 parts by weight of talc, 0.5 parts by weight of barium stearate, 1.0 part by weight of bentonite and 0.1 parts by weight of epoxy resin with respect to 100 parts by weight of polystyrene. 2 parts by weight of the mixture, and the foaming agent composition was 1.0 part by weight of water, 1.5 parts by weight of carbon dioxide, 4 parts by weight of isobutane and 3.5 parts by weight of ethyl chloride with respect to 100 parts by weight of polystyrene resin. Except that, an extruded foam was obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.
As shown in Table 1, the foam density of the obtained extruded foam is 39 kg / m ³ , the thermal conductivity measured according to JIS A9511 is 0.024 W / mK, and the compressive strength is 13 N / cm. ² . In addition, from the measurement results that the average bubble diameter in the thickness direction is 0.04 mm, the average bubble diameter in the width direction is 0.16 mm, and the average bubble diameter in the length direction is 0.15 mm, the three-direction average bubble diameter is 0.10 mm. The bubble direction anisotropy rate in the thickness direction was 0.41.

Claims (9)

A styrene resin extruded foam obtained by extrusion foaming a styrene resin composition to which a foaming agent has been added,
The three-direction average cell diameter determined by the following formula (1) of the bubbles constituting the styrene resin foam is 0.02 to 0.15 mm,
Thickness direction bubble anisotropy ratio calculated | required by following formula (2) is 0.5-1.1,
A styrenic resin extruded foam, wherein the foam has a thermal conductivity of 0.024 W / mK or less and a compressive strength of 15 N / cm ² or more measured by the method of JIS A9511.
Formula (1): 3-direction average bubble diameter = ((average bubble diameter in thickness direction) × (average bubble diameter in width direction) × (average bubble diameter in length direction)) ^(1/3)
Formula (2): Thickness direction bubble anisotropy rate = Thickness direction average bubble diameter / 3 direction average bubble diameter   The styrene resin extruded foam according to claim 1, wherein the foaming agent contains a saturated hydrocarbon having 3 to 5 carbon atoms.   The styrene resin extruded foam according to claim 2, wherein the saturated hydrocarbon is 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 3, wherein the foaming agent contains at least one alkyl chloride selected from the group consisting of methyl chloride and ethyl chloride.   The styrene resin extruded foam according to any one of claims 1 to 4, wherein the foaming agent further comprises at least one selected from the group consisting of water and carbon dioxide. The styrene resin extruded foam according to any one of claims 1 to 5, wherein a foam density of the styrene resin extruded foam is 30 to 65 kg / m ³ .   The styrene resin extruded foam according to any one of claims 1 to 6, wherein the styrene resin extruded foam has a thickness of 10 to 150 mm.   The styrene resin extruded foam according to any one of claims 1 to 7, wherein the styrene resin extruded foam has a skin.   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, and the saturated hydrocarbon having 3 to 5 carbon atoms is used as the foaming agent. The method for producing a styrenic resin foam according to any one of claims 1 to 8, wherein an alkyl chloride is used.