JP2015113416A - Styrenic resin extrusion foam and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-ray radiation suppression agent added highly insulative styrenic resin extrusion foam that is light-weight and that has an excellent insulative property, and that has an excellent flame retardancy better than the conventional, and to provide a production method therefor.SOLUTION: Provided is a styrenic resin extrusion foam obtained by extrusion foaming using a styrenic resin and a blowing agent, and comprising graphite, containing a bromine-type flame-retardant agent by 1.0 pt.wt. or more and 6.0 pts.wt. or less based on 100 pts.wt. of styrenic resin, having the residual amount of isobutane in an extruded foam after 4 days from production of the extruded foam, of 0.30 mol or more and 0.50 mol or less, and passing the flammability testing method A defined in JIS A 9511 and having the fire spread length of 10 mm or less.

Description

  The present invention relates to, for example, a styrene resin extruded foam used as a heat insulating material for a structure and a method for producing the same, from the viewpoint of good workability and heat insulation.

  Styrenic resin extruded foam is generally produced by heating and melting a styrene resin composition using an extruder or the like, then adding a foaming agent under high pressure conditions, cooling to a predetermined resin temperature, Manufactured continuously by extrusion foaming extrusion into the zone.

  Styrenic resin extruded foam is used as a heat insulating material for structures, for example, because of good workability and heat insulating properties. In recent years, from the viewpoint of reducing carbon dioxide emissions, there has been an increasing demand for energy saving in houses, buildings, etc., and therefore technological development of foams with higher heat insulation than ever before has been desired. Proposed.

  For example, Patent Documents 1 to 4 disclose a technique of adding a heat ray radiation inhibitor such as graphite or titanium oxide to a styrene resin.

  Patent Document 1 proposes a method for improving heat insulation by adding graphite to a styrene resin. Patent Documents 2 to 3 propose a method of using a white pigment such as titanium oxide together in order to prevent shape instability (warping due to solar radiation) due to a large amount of black pigment such as graphite or carbon black. Yes. Furthermore, in Patent Document 4, in order to obtain a styrene resin extruded foam having excellent heat insulation performance and excellent environmental compatibility, a polystyrene resin, a heat radiation inhibitor, and a halogen-containing compound are included. There has been proposed a method of extrusion-foaming a styrene resin composition obtained by melt-kneading a non-foaming agent.

  As described above, the mainstream of the heat insulation of the styrene resin extruded foam is to add graphite, titanium oxide or the like as a heat ray radiation inhibitor. However, in this technology, the heat ray radiation inhibitor to be added absorbs the flame radiation during combustion, the styrene resin extruded foam becomes high temperature, the resin constituting the foam collapses, and a large amount of foaming agent is released. May end up. For this reason, there existed a subject that there exists a tendency for a fire spread distance to extend compared with the styrene-type resin extrusion foam to which the heat ray radiation inhibitor is not added.

  Patent Document 5 discloses a foamed plate produced by using isobutane having an ozone depletion coefficient of 0 and a small global warming coefficient as a foaming agent, which has excellent flame retardancy and low thermal conductivity. In order to provide an extruded foam plate, it has been proposed that the residual amount of isobutane in the foam plate is 0.45 to 0.80 mol per kg of the foam plate. However, in this technique, since the heat ray radiation inhibitor as described above is not used, in order to ensure heat insulation, the average cell diameter in the thickness direction of the foamed plate and the bubble deformation rate (average cell diameter in the thickness direction / Since it is necessary to control the average bubble diameter in the horizontal direction, it is difficult to manufacture easily in a low density region. As for the remaining amount of isobutane, in the examples described in the literature, the target foamed plate was obtained only when the remaining amount of isobutane after 4 weeks of production was 0.61 mol or more per 1 kg of the foamed plate. Absent.

JP 2004-196907 A JP 2009-256426 A JP 2010-254780 A JP 2013-221110 A JP 2004-059595 A

  An object of the present invention is to provide a highly heat-insulating styrene resin extruded foam with a heat ray radiation inhibitor and a method for producing the same, which is lightweight and has excellent heat insulation properties and excellent flame retardancy. It is in.

  As a result of intensive studies to solve the above problems, the inventors of the present invention use graphite as a heat ray radiation suppressant, and contain a predetermined amount of a brominated flame retardant, and further 4 days after the production of the extruded foam. The present invention was completed by setting the residual amount of isobutane in the extruded foam to a predetermined range.

That is, the present invention is as follows.
[1] A styrene resin extruded foam obtained by extrusion foaming using a styrene resin and a foaming agent, including graphite, and containing 1.0 part by weight of a brominated flame retardant with respect to 100 parts by weight of the styrene resin. The remaining amount of isobutane in the extruded foam after 4 days from the production of the extruded foam is 0.30 mol or more and 0.50 mol or less per kg of the extruded foam, A styrene-based resin extruded foam characterized by passing the test method A for flammability specified in 9511 and having a fire spread length of 10 mm or less.
[2] The residual amount of isobutane in the extruded foam 4 days after the production of the styrene resin extruded foam is 0.40 mol or more and 0.50 mol or less per kg of the extruded foam, [1 ] The styrene-type resin extrusion foam of description.
[3] The styrenic resin extruded foam according to [1] or [2], wherein the thermal conductivity measured by a method according to JIS A9511 is 0.0245 W / mK or less.
[4] The styrene resin according to any one of [1] to [3], wherein the graphite is contained in an amount of 1.0 to 3.5 parts by weight with respect to 100 parts by weight of the styrene resin. Extruded foam.
[5] The styrene resin extruded foam according to any one of [1] to [4], further comprising titanium oxide.
[6] The extruded styrene resin foam according to [5], wherein the titanium oxide is contained in an amount of 1.0 to 4.0 parts by weight with respect to 100 parts by weight of the styrene resin.
[7] The brominated flame retardant is contained in an amount of 1.0 part by weight or more and 4.0 parts by weight or less based on 100 parts by weight of the styrene resin, according to any one of [1] to [6]. Styrene resin extruded foam.
[8] The styrene resin extruded foam according to any one of [1] to [7], wherein the apparent density is 20 kg / m ³ or more and less than 50 kg / m ³ .
[9] A method for producing an extruded foam of a styrene resin by extrusion foaming using a styrene resin and a foaming agent, comprising graphite and containing a bromine-based flame retardant in an amount of 1. A styrenic resin composition containing 0 parts by weight or more and 6.0 parts by weight or less is heated and melted, and then a foaming agent containing at least isobutane is added under high pressure conditions. The extruded foam is molded into an extruded foam, and the remaining amount of isobutane in the extruded foam after 4 days from the production of the extruded foam is 0.30 mol or more and 0.50 mol or less per kg of the extruded foam. Thus, the extruded foam passes the flammability test method A defined in JIS A9511 and has a fire spread length of 10 mm or less, and is a styrene resin extruded foam. Body manufacturing method.

  According to the present invention, a styrene resin containing graphite and containing a predetermined amount of a brominated flame retardant as a flame retardant is subjected to extrusion foam molding, and the residual amount of isobutane in the extruded foam is controlled within a predetermined range. It is possible to provide a highly heat-insulating styrene-based resin extrusion foam molded article having excellent flammability.

  Embodiments of the present invention will be described below. It should be noted that the following embodiments are only some of the embodiments of the present invention, and it is needless to say that these embodiments can be appropriately changed without departing from the gist of the present invention.

  The styrene resin extruded foam according to the present invention is a styrene resin extruded foam obtained by extrusion foaming using a styrene resin and a foaming agent, containing graphite as a heat ray radiation inhibitor, and serving as a flame retardant. A flammability test as defined in JIS A 9511, which contains a certain amount of brominated flame retardant, and further, the remaining amount of isobutane in the extruded foam after 4 days from the production of the extruded foam is within a predetermined range. The method is characterized in that the method A is passed and the fire spread length is within a predetermined range.

  In this styrene resin extruded foam, a styrene resin composition containing a brominated flame retardant and other additives as needed is heated and melted using an extruder or the like, and then the foaming agent is subjected to high pressure conditions. And after cooling to a predetermined resin temperature, it is continuously produced by extruding it to a low pressure region.

  The styrene resin used in the present invention is not particularly limited, and the single weight of a styrene monomer such as styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, bromo styrene, chloro styrene, vinyl toluene, and vinyl xylene. A copolymer comprising a combination or a combination of two or more monomers, the styrene monomer and divinylbenzene, butadiene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride And a copolymer obtained by copolymerizing one or more monomers such as 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. Also good.

  As the styrenic resin in the present invention, a resin having an MFR of 0.1 to 50 g / 10 min is excellent in molding processability at the time of extrusion foam molding, the discharge amount at the molding process, and the obtained styrenic resin It is easy to adjust the thickness, width, density, or closed cell ratio of the extruded resin foam to desired values, and foamability (foam thickness, width, density, closed cell ratio, surface properties, etc. is easily adjusted to the desired situation. Styrene resin extruded foam with excellent appearance etc. was obtained, as well as mechanical strength such as compressive strength, bending strength or bending deflection, and balance of characteristics such as toughness, It is preferable from the point that a styrene resin extruded foam is obtained. Further, the MFR of the styrenic resin is more preferably 0.3 to 30 g / 10 minutes, particularly 0.5 to 25 g / 10 minutes, from the viewpoint of the balance of mechanical strength and toughness with respect to moldability and foamability. preferable. In addition, in this invention, MFR is measured by A method and test condition H of JISK7210 (1999).

  In the present invention, among the styrene resins described above, a polystyrene resin is particularly suitable from the viewpoint of economy and workability. Moreover, when higher 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 higher impact resistance is required for the extruded foam, it is preferable to use rubber-reinforced polystyrene. These styrenic resins may be used alone, or two or more different styrenic resins such as copolymerization component, molecular weight, molecular weight distribution, branched structure, and MFR may be mixed and used.

  Although it does not specifically limit as a foaming agent used by this invention except containing at least isobutane, By using a C3-C5 saturated hydrocarbon, the outstanding environmental compatibility can be provided. .

  Examples of the saturated hydrocarbon having 3 to 5 carbon atoms other than isobutane used in the present invention include propane, n-butane, n-pentane, i-pentane, neopentane and the like. Among these saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, or a mixture thereof is preferable from the viewpoint of foamability. However, depending on various properties of the foam, such as the desired foaming ratio and flame retardancy, the amount used may be limited, and the extrusion foam moldability may not be sufficient.

  In the present invention, by using a foaming agent other than the saturated hydrocarbon having 3 to 5 carbon atoms, a plasticizing effect and an auxiliary foaming effect at the time of foam production can be obtained, and the extrusion pressure is reduced and stable. In addition, the foam can be manufactured.

  Examples of the other blowing agent include ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methyl furan, tetrahydrofuran, tetrahydropyran; dimethyl ketone, Methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl-n-butyl ketone, methyl-i-butyl ketone, methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl ketone, ethyl-n-butyl ketone, etc. Ketones; saturated alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, and t-butyl alcohol; Carboxylic acid esters such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate and ethyl propionate; alkyl halides such as methyl chloride and ethyl chloride, trans-1, 3, 3 Organic foaming agents such as 3-tetrafluoroprop-1-ene, inorganic foaming agents such as water and carbon dioxide, chemical foaming agents such as azo compounds and tetrazole, and the like can be used. These other blowing agents may be used alone or in combination of two or more.

  Among the foaming agents other than the saturated hydrocarbons having 3 to 5 carbon atoms as described above, saturated alcohols having 1 to 4 carbon atoms, dimethyl ether, diethyl ether, methyl ethyl, etc., from the viewpoints of foamability and foam formability Ether, methyl chloride, ethyl chloride and the like are preferable. From the viewpoint of the flammability of the foaming agent, the flame retardancy of the foam or the heat insulation described later, water and carbon dioxide are preferable, and dimethyl ether is particularly preferable from the viewpoint of the plasticizing effect. preferable.

  The blowing agent used in the present invention contains at least isobutane, and is further selected from the group consisting of water, carbon dioxide, nitrogen, alcohols having 2 to 5 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride. It is preferable that one or more types are included in that the heat insulating performance, foamability, foam moldability, etc. of the foam can be compatible.

  The pressure when adding or injecting the foaming agent is not particularly limited as long as it is higher than the internal pressure of an extruder or the like.

  The amount of the foaming agent used in the present invention is preferably 2 to 20 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the styrene resin. When the addition amount of the foaming agent is less than 2 parts by weight, the foaming ratio is low, and the characteristics such as light weight and heat insulation as the resin foam may be difficult to be exhibited. Therefore, defects such as voids may occur in the foam.

  In the present invention, the flammability test method defined in JIS A9511 is made by setting the residual amount of isobutane in the extruded foam after 4 days from the production of the styrene resin extruded foam and further 28 days later to a predetermined amount. After passing A and suppressing the fire spread length to 10 mm or less, a styrene resin extruded foam having excellent heat insulation can be obtained. The remaining amount of isobutane in the extruded foam after 4 days and 28 days from the production of the styrene resin extruded foam is preferably 0.30 mol or more and 0.50 mol or less, and 0.40 mol or more and 0.50 mol per kg of the extruded foam. The following is more preferable, and 0.45 mol or more and 0.50 mol or less is still more preferable. If it is less than 0.30 mol, the amount of isobutane having a thermal conductivity lower than that of air in the extruded foam is small, and excellent heat insulating properties cannot be imparted to the extruded foam. On the other hand, if the amount of isobutane having high flammability is more than 0.50 mol, it may not pass the flammability test method A defined in JIS A9511, or gas surface combustion may occur and the fire spread length may exceed 10 mm. is there.

  Improving the gas surface combustion of the foam cannot be solved by increasing the flame retardant alone. The mechanism of gas surface combustion is not limited to this, but when the fire source ignites the foam, the bubbles are destroyed, and the combustible gas present in the bubble structure is released to the atmosphere. Thus, it is considered that gas combustion occurs together with oxygen in the air. Therefore, if the foam is a structure that is weak against heat, it is considered that gas emission from the foam is facilitated and gas combustion is promoted. Furthermore, when a heat ray radiation inhibitor having a heat ray radiation absorption effect is added for the purpose of imparting excellent heat insulation like the graphite of the present invention, heat ray radiation generated from a fire source is also absorbed, and the foam is more High heat will be applied. Therefore, in the conventional method, the foam added with the heat ray radiation inhibitor has a problem that the gas surface combustion is more likely to occur than the foaming agent not added with the heat ray radiation inhibitor. Gas combustion generally occurs only in the surface layer portion of the JIS combustion test piece, and the fire spread of the fire source may reach the top in an instant.

  According to the present invention, by controlling the remaining amount of isobutane in the foam as described above, gas surface combustion is improved and the fire spread length can be 10 mm.

  In order to control the remaining amount of isobutane in the extruded foam after 4 days from the production of the styrene resin extruded foam, and further 28 days later, within the range of the predetermined amount defined in the present invention, the extrusion temperature, What is necessary is just to adjust foaming pressure, the compounding quantity of isobutane, etc. In order to increase the residual amount of isobutane by adjusting the extrusion temperature and foaming pressure, the extrusion temperature should be kept low and the foaming pressure kept high. Conversely, to reduce the residual amount of isobutane, the extrusion temperature was increased and foaming was performed. What is necessary is just to make pressure low.

  In the present invention, when water or alcohol is used as the other foaming agent, it is preferable to add a water-absorbing substance in order to stably perform extrusion foaming. Specific examples of water-absorbing substances used in the present invention include polyacrylate polymers, starch-acrylic acid graft copolymers, polyvinyl alcohol polymers, vinyl alcohol-acrylate copolymers, ethylene- In addition to water-absorbing polymers such as vinyl alcohol copolymers, acrylonitrile-methyl methacrylate-butadiene copolymers, polyethylene oxide copolymers and derivatives thereof, anhydrous silica (silicon oxide) having silanol groups on the surface [For example, AEROSIL manufactured by Nippon Aerosil Co., Ltd. is commercially available. ] Fine powder having a particle size of 1000 nm or less having a hydroxyl group on the surface; water-absorbing or water-swelling layered silicates such as smectite and swellable fluorine mica, and organically treated products thereof; zeolite, activated carbon, alumina, Examples thereof include porous substances such as silica gel, porous glass, activated clay, and diatomaceous earth.

  The addition amount of the water-absorbing substance used in the present invention is appropriately adjusted depending on the addition amount of water and the like, but is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the styrenic resin. 0.1 to 3 parts by weight is more preferable.

  In this invention, a flame retardance can be provided to the styrene resin foam obtained by containing a brominated flame retardant as a flame retardant.

  Specific examples of the brominated flame retardant in the present invention include hexabromocyclododecane, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether, tetrabromobisphenol A-bis (2,3 -Dibromopropyl) ether, tris (2,3-dibromopropyl) isocyanurate, and aliphatic bromine-containing polymers such as brominated styrene-butadiene block copolymers. These may be used alone or in combination of two or more.

  Of these, a mixed bromine system consisting of hexabromocyclododecane, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether, and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether A flame retardant and a brominated styrene-butadiene block copolymer are preferably used because they have good extrusion operation and do not adversely affect the heat resistance of the foam. These flame retardants may be used alone or as a mixture.

  The content of the brominated flame retardant in the present invention is preferably 1.0 part by weight or more and 6.0 parts by weight or less, and 1.0 part by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the styrene resin. More preferably, 1.0 part by weight or more and 4.0 part by weight or less is further preferable, and 1.5 part by weight or more and 4.0 part by weight or less is particularly preferable. If the content of brominated flame retardant is less than 1.0 part by weight, good properties such as flame retardancy tend to be difficult to obtain. On the other hand, if the content exceeds 6.0 parts by weight, the foam It may impair the stability and surface quality during production. However, the content of the flame retardant is the type or content of the foaming agent content, the foam density, an additive having a flame retardant synergistic effect, etc. so that the flame retardancy specified in JIS A9511 measurement method A can be obtained. It is more preferable to adjust appropriately according to the above.

  In the present invention, a radical generator can be used in combination for the purpose of improving the flame retardancy of the styrene resin extruded foam. Specifically, 2,3-dimethyl-2,3-diphenylbutane, poly-1,4-diisopropylbenzene, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4- Examples include diphenylhexane, 3,4-diethyl-3,4-diphenylhexane, 2,4-diphenyl-4-methyl-1-pentene, and 2,4-diphenyl-4-ethyl-1-pentene. Peroxides such as dicumyl peroxide are also used. Among them, those that are stable under the resin processing temperature conditions are preferable, specifically 2,3-dimethyl-2,3-diphenylbutane and poly-1,4-diisopropylbenzene, and the preferable addition range is The amount is 0.05 to 0.5 parts by weight based on 100 parts by weight of the styrene resin.

  Furthermore, for the purpose of improving the flame retardancy, a phosphorus flame retardant such as phosphate ester and phosphine oxide can be used in combination as long as the thermal stability performance is not impaired. Examples of phosphoric acid esters include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate, Examples thereof include tris (butoxyethyl) phosphate, condensed phosphate ester and the like, and triphenyl phosphate is particularly preferable. As the phosphine oxide-type phosphorus flame retardant, triphenylphosphine oxide is preferable. These phosphate esters and phosphine oxides may be used alone or in combination of two or more. A preferable addition range is 0.1 to 2 parts by weight with respect to 100 parts by weight of the styrene resin.

  In the present invention, if necessary, a resin and / or a flame retardant stabilizer can be used. Although not particularly limited, specific examples of the stabilizer include epoxy compounds such as bisphenol A diglycidyl ether type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin; dipentaerythritol and adipine Polyhydric alcohol esters such as partial esters with acids and reactants with polyhydric alcohols; triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, pentaerythritol tetrakis [3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate], octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol Tetrakis [3- 3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate]; 3,9-bis (2,4-di-tert-butylphenoxy) -2,4, 8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane, 3,9-bis (2,6-di-tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa- Phosphite stabilizers such as 3,9-diphosphaspiro [5.5] undecane, and tetrakis (2,4-di-tert-butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite); Are preferably used because they do not reduce the flame retardancy of the foam and improve the thermal stability of the foam.

  In the present invention, a foam having high heat insulating properties can be obtained by adding graphite as a heat ray radiation inhibitor. The said heat ray radiation inhibitor means the substance which has the characteristic to reflect, scatter, and absorb the light of near infrared or infrared region (for example, wavelength range of about 800-3000 nm).

  Examples of the graphite used in the present invention include scale-like graphite, earthy graphite, spherical graphite, and artificial graphite. Among these, it is preferable to use the one whose main component is scale-like graphite from the viewpoint of a high heat ray radiation suppressing effect. The graphite preferably has a fixed carbon content of 80% or more, and more preferably 85% or more. The foam which has high heat insulation is obtained by making fixed carbon content into the said range.

  The dispersed particle diameter of graphite is preferably 15 μm or less, and more preferably 10 μm or less. By setting the particle size within the above range, the specific surface area of graphite is increased, and the probability of collision with heat radiation is increased, so that the effect of suppressing heat radiation is enhanced. In order to make the dispersed particle diameter within the above range, a particle having a primary particle diameter of 15 μm or less may be selected.

  The dispersed particle size is an arithmetic average value based on the number of particles dispersed in the foam plate, and the particle size is measured by enlarging the cross section of the foam plate with a microscope or the like. The primary particle size means a volume average particle size (d50).

  The graphite content in the present invention is preferably 1.0 part by weight or more and 3.5 parts by weight or less, and more preferably 1.5 parts by weight or more and 3.0 parts by weight or less with respect to 100 parts by weight of the styrene resin. When the content is less than 1.0 part by weight, a sufficient heat ray radiation suppressing effect cannot be obtained. On the other hand, if the content exceeds 3.5 parts by weight, the effect of suppressing heat radiation corresponding to the content cannot be obtained and there is no cost merit.

In addition, content of the graphite in this invention can be measured according to JISK6226-2: 2003. Specifically, about 10 mg of a test piece was cut out from the foam, and the thermogravimetric measurement apparatus equipped with EXSTAR6000: TG / DTA 220U [manufactured by SII Nanotechnology Co., Ltd.] was used. The temperature was raised from 40 ° C. to 600 ° C. at 20 ° C./min under a nitrogen stream of 200 mL / min, and held at 600 ° C. for 10 minutes. [2] 10 from 600 ° C. to 400 ° C. under a nitrogen stream of 200 mL / min The temperature is lowered at deg. C / min and then held at 400 ° C. for 5 minutes. [3] The temperature is raised from 400 ° C. to 800 ° C. at 20 ° C./min under an air stream of 200 mL / min and then held at 800 ° C. for 15 minutes. Hereinafter, the graphite content can be calculated from the formulas (1) and (2).
Carbon content = weight reduced at [3] / total amount of test piece × 100 (1)
Graphite content = carbon content / fixed carbon content of graphite used (2)

  As a heat ray radiation inhibitor that can be used in the present invention, white particles such as titanium oxide, barium sulfate, zinc oxide, aluminum oxide, and antimony oxide can be used in combination with graphite. These may be used alone or in combination of two or more. Among these, titanium oxide and barium sulfate are preferable, and titanium oxide is more preferable because the effect of suppressing radiation radiation is large. The dispersed particle diameter of the white particles is not particularly limited, but is preferably 0.1 μm to 10 μm, for example, in the case of titanium oxide, in view of effectively reflecting infrared rays and considering color developability to the resin. 0.15 μm to 5 μm is more preferable.

  In the present invention, the content of white particles such as titanium oxide is preferably 1.0 part by weight or more and 4.0 parts by weight or less, and 1.0 part by weight or more and 3.0 parts by weight or less with respect to 100 parts by weight of the styrene resin. Part by weight or less is more preferable, and 1.5 parts by weight or more and 2.5 parts by weight or less is more preferable. The white particles have a smaller heat ray radiation suppressing effect than graphite, and if the content is less than 1.0 part by weight, even if the white particles are contained, there is almost no heat ray radiation suppressing effect. If it exceeds 4.0 parts by weight, the heat ray radiation suppressing effect corresponding to the content cannot be obtained, and the extrusion stability and moldability are inferior, and the flame retardancy of the foam tends to deteriorate.

  In the present invention, the total content of heat ray radiation suppressors such as graphite and titanium oxide is preferably 1.0 part by weight or more and 6.0 parts by weight or less, and 2.0 parts by weight or more with respect to 100 parts by weight of the styrene resin. 5.0 parts by weight or less is more preferable. When the total content of the heat ray radiation suppressor is less than 1.0 part by weight, high heat insulation cannot be obtained, and when it exceeds 6.0 parts by weight, the extrusion stability and formability are inferior or the combustibility is impaired. Tend.

  In the styrene resin extruded foam of the present invention, if necessary, silica, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, as long as the effects of the present invention are not impaired. , Inorganic compounds such as calcium carbonate, processing aids such as sodium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin waxes, stearylamide compounds, phenolic antioxidants, phosphorus stabilizers, nitrogenous Additives such as stabilizers, sulfur-based stabilizers, light-resistant stabilizers such as benzotriazoles and hindered amines, flame retardants other than those described above, antistatic agents, and coloring agents such as pigments may be contained.

  As a procedure for adding various additives to the styrenic resin, for example, after adding and mixing various additives to the styrenic resin, the mixture is supplied to an extruder, heated and melted, and further added with a foaming agent and mixed. The timing for adding various additives to the styrenic resin and the kneading time are not particularly limited.

  As a method for producing a styrene resin extruded foam of the present invention, a styrene resin, a flame retardant, other additives and the like are supplied to a heating and melting means such as an extruder, and the foaming agent is subjected to a high pressure condition at any stage. Is added to a styrene resin to form a fluid gel, cooled to a temperature suitable for extrusion foaming, and then the fluid gel is extruded and foamed into a low pressure region through a die to form a foam.

  The heating temperature may be equal to or higher than the temperature at which the styrenic resin used melts, but a temperature at which molecular degradation of the resin due to the influence of additives and the like is suppressed as much as possible, for example, about 150 to 260 ° C is 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 the foam molding method of the present invention, for example, an extrusion foam obtained by opening 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 is used as a slit die. A method of forming a plate-like foam having a large cross-sectional area using a molding die placed in close contact with or in contact with a molding roll placed adjacent to the downstream side of the molding die is used. By adjusting the flow surface shape of the molding die and the mold temperature, the desired cross-sectional shape of the foam, the surface property of the foam, and the quality of the foam can be obtained.

  In the present invention, an extruded foam with a beautiful appearance can be obtained by setting the resin pressure inside the die immediately before foaming (hereinafter referred to as “foaming pressure”) to 2.5 MPa or more. When the foaming pressure is lower than 2.5 MPa, foaming occurs inside the die, and an extruded foam having a beautiful surface cannot be obtained, and stable extrusion foaming cannot be performed. In the present invention, the term “immediately before foaming” means within 300 mm from the die outlet.

  As described above, in the styrene-based resin extruded foam according to the present invention, the residual amount of isobutane in the extruded foam after 4 days from the production of the extruded foam is 0.30 mol or more per 1 kg of the extruded foam. It is a styrene resin extruded foam of 50 mol or less, passes the flammability test method A specified in JIS A 9511, and has a fire spread length of 10 mm or less. Furthermore, the extruded styrene resin foam according to the present invention is one week after production, considering that the long-term thermal conductivity after 25 years satisfies 0.028 W / mK defined in JIS A 9511. The thermal conductivity is preferably 0.0245 W / mK or less.

  As described above, in order to set the thermal conductivity after one week from the production of the styrene resin extruded foam to 0.0245 W / mK or less, the type and amount of the heat radiation inhibitor and the foaming agent, the foam structure ( (Bubble diameter) may be adjusted. In order to reduce the thermal conductivity, the heat ray radiation inhibitor may be increased or the bubble diameter of the foam may be reduced within the range specified in the present invention.

  The cell diameter of the styrene resin extruded foam according to the present invention is preferably 0.05 mm to 1 mm, more preferably 0.06 mm to 0.5 mm, and still more preferably 0.07 mm to 0.3 mm. The bubble diameter can be measured by, for example, a method based on ASTM D 3567. If the bubble diameter is larger than 1 mm, a sufficient effect of reducing thermal conductivity may not be obtained. On the other hand, when the bubble diameter is smaller than 0.05 mm, the shape stability is inferior, and it may be difficult to obtain an extruded foam having a desired thickness.

Moreover, the styrene resin extruded foam according to the present invention is an extruded foam from the viewpoint of heat insulation and lightness considering that it functions as, for example, a heat insulating material for buildings, a cold storage or a cold car. preferably the apparent density of less than 20 kg / m ³ or more 50 kg / m ^3, more preferably 25 kg / m ³ or more 45 kg / m of less than ^3, more preferably less than 25 kg / m ³ or more 35 kg / m ^3.

  Although the thickness of the styrene resin extruded foam according to the present invention is not particularly limited, for example, heat insulation, bending strength, and compressive strength in consideration of functioning as a heat insulator for a building, a cold storage, or a cold car. In view of the above, it is preferably 10 mm or more and 150 mm or less, more preferably 15 mm or more and 120 mm or less, and particularly preferably 20 mm or more and 100 mm or less.

  Thus, according to the present invention, it is possible to easily obtain a high-performance and economical styrene resin extruded foam having light weight, excellent heat insulation and flame retardancy.

  Examples of the present invention will be described below. Needless to say, the present invention is not limited to the following examples.

  The raw materials used in the examples and comparative examples are as follows.

○ Base resin / styrene resin A [manufactured by PS Japan, G9401; MFR 2.2 g / 10 min]
Styrenic resin B [manufactured by PS Japan, 680; MFR 7.0 g / 10 min]

○ Heat radiation inhibitor / graphite [manufactured by Maruhyo Casting Mfg. Co., Ltd., M-885; scale-like graphite, primary particle size 5.5 μm, fixed carbon content 89%]
Titanium oxide [manufactured by Sakai Chemical Industry, R-7E; primary particle size 0.23 nm]

○ Flame retardants • Mixed brominated flame retardants [Daiichi Kogyo] (tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether) Co., Ltd., GR-125P]
-Brominated styrene-butadiene block polymer [Chemura, EMERALD INNOVATION # 3000]
-Hexabromocyclododecane [Albemarle, HP900]

○ Flame retardant aids, triphenylphosphine oxide [Sumitomo Corporation Chemical]
・ Poly-1,4-diisopropylbenzene [manufactured by UNITED INITIATORS, CCPIB]
Tris (tributyl neopentyl) phosphate [Daihachi Chemical Industry Co., Ltd., CR-900]

○ Stabilizer, bisphenol-A-glycidyl ether [manufactured by ADEKA, EP-13]
-Cresol novolac epoxy resin [manufactured by Huntsman Japan, ECN-1280]
Dipentaerythritol-adipic acid reaction mixture [Ajinomoto Fine-Techno, Pleniser ST210]
Pentaerythritol tetrakis [3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] [manufactured by Chemtura, ANOX20]
・ 3,9-bis (2,4-di-tert-butylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane [manufactured by Chemtura, Ultranox 626]
Triethylene glycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate [Songwon Japan, Sonnox 2450FF]

○ Other additives, talc [Talcan Powder PK-Z, Hayashi Kasei Co., Ltd.]
・ Calcium stearate [manufactured by Sakai Chemical Industry Co., Ltd., SC-P]
Bentonite [Hogel Jungle, Wengel Bright K11]
Silica [Evonik Degussa Japan Co., Ltd., Carplex BS-304F]

○ Foaming agent, isobutane [Mitsui Chemicals, Inc.]
・ Dimethyl ether [Made by Iwatani Corporation]
・ Water [Taptsu City, Osaka Prefecture]

  About an Example and a comparative example, apparent density, thermal conductivity, isobutane residual amount, JIS combustion property, fire spread length, and moldability were evaluated according to the following methods.

(1) Apparent density (kg / m ³ )
While measuring the weight of the obtained styrene resin extruded foam, the length dimension, the width dimension, and the thickness dimension were measured.
From the measured weight and each dimension, the foam density was calculated | required based on the following formula | equation, and the unit was converted into kg / m < ³ >.
Apparent density (g / cm ³ ) = foam weight (g) / foam volume (cm ³ )

(2) Thermal conductivity (W / mK)
The thermal conductivity of the foam was measured by a method based on JIS A 9511.
In consideration of the fact that the long-term thermal conductivity after 25 years satisfies 0.028 W / mK specified in JIS A 9511, the thermal conductivity of the foam is a standard temperature state 3 specified in JIS K 7100. grade (23 ℃ ± 5 ℃), and standard humidity conditions tertiary ^{(50 +20, -. 10%} R.H) was allowed to stand under the conditions of, after one week from the production, the thermal conductivity definitive foam below Evaluation based on the criteria.
○ (Pass): Thermal conductivity is 0.0245 W / mK or less.
Δ (pass): Thermal conductivity is 0.0254 W / mK or less.
X (failure): Thermal conductivity is larger than 0.0254 W / mK.

(3) Residual amount of isobutane The obtained styrene resin extruded foam was classified into standard temperature state class 3 (23 ° C. ± 5 ° C.) and standard humidity state class 3 (50 ^{+ 20, −10} %) as defined in JIS K 7100 (R.H.), and the remaining amount of isobutane was evaluated by the following equipment and procedure after 4 and 28 days from the production.
a) Equipment used: Gas chromatograph GC-2014 [manufactured by Shimadzu Corporation]
b) Column used: G-Column G-950 25UM [Chemicals Evaluation and Research Institute]
c) Measurement conditions;
・ Inlet temperature: 65 ℃
-Column temperature: 80 ° C
-Detector temperature: 100 ° C
Carry gas: High purity helium Carry gas flow rate: 30 mL / min Detector: TCD
・ Current: 120mA
An approximately 130 cc glass container (hereinafter referred to as “sealed container”) is filled with about 1.2 g of a test piece, which varies depending on the apparent density cut out from the foam, and is evacuated by a vacuum pump. It was. Thereafter, the sealed container was heated at 170 ° C. for 10 minutes, and the foaming agent in the foam was taken out into the sealed container. After the airtight container returns to room temperature, helium is introduced into the airtight container to return to atmospheric pressure, and then 40 μL of a mixed gas of helium, isobutane, dimethyl ether, and air is taken out by a microsyringe, and a) to c) above. Evaluation was performed using the equipment used and the measurement conditions.

(4) JIS flammability and fire spread length JIS flammability was evaluated according to the following criteria using a test piece having a thickness of 10 mm, a length of 200 mm, and a width of 25 mm in accordance with JIS A 9511. Measurements were made after manufacturing a styrene-based resin extruded foam, and cut into a test piece having the above dimensions, and the standard temperature state class 3 (23 ° C. ± 5 ° C.) and standard humidity state class 3 (50 ^{+20, -10} % RH) and carried out 4 days after production.
○ (Pass): Satisfies the standard that the flame disappears within 3 seconds, there is no residue, and the combustion limit indicator line is not combusted.
X (failed): The above criteria are not satisfied.

  In addition, regarding the gas surface combustion, which is a phenomenon in which only the foam surface is spread by the combustible gas contained in the foam (in the bubbles), the length (mm) of the flame spread beyond the combustion limit indicating line is expressed as “fire spread length”. Was measured. The measurement of the “fire spread length” was also made an average value after measuring five test pieces in the same manner as the JIS flammability. When the fire was extinguished without exceeding the combustion limit indicating line (without reaching the combustion limit indicating line), the remaining distance from the combustion limit indicating line was obtained as a negative value. In general, this minus amount is regarded as zero, but in order to clarify the effect of the present invention, it is shown in the minus direction.

(5) Formability The extruded foam was visually observed and evaluated according to the following evaluation criteria.
◯: Extruded foam with a beautiful appearance, with no voids, wrinkles, protrusions or foreign matter seen on the surface of the extruded foam.
Δ: The surface of the extruded foam has voids, wrinkles, protrusions, and foreign matters remarkably, and the extruded foam has a poor appearance, but the physical properties can be evaluated.
×: Voids, wrinkles, protrusions and foreign matter are remarkably present on the surface of the extruded foam, and the extruded foam has a poor appearance, and the physical properties cannot be evaluated.

(Example 1)
[Preparation of resin mixture]
Styrenic resin A [manufactured by PS Japan Co., Ltd., G9401] 100 parts by weight, graphite [manufactured by Marufyo Casting Mfg. Co., Ltd., M-885] 3.0 parts by weight, as a flame retardant, tetrabromobisphenol Mixed brominated flame retardant of A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A-bis (2,3-dibromopropyl) ether [Daiichi Kogyo Co., Ltd., GR-125P ] 3.0 parts by weight, triphenylphosphine oxide [Sumitomo Corporation Chemical] 1.0 parts by weight as a flame retardant auxiliary, and bisphenol-A-glycidyl ether [manufactured by ADEKA, EP-13] as a stabilizer. 20 parts by weight, triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate [Son Won Japan Co., Ltd., Sonnox 2450FF] 0.20 parts by weight, dipentaerythritol-adipic acid reaction mixture [Ajinomoto Fine Techno Co., Ltd., Plenizer ST210] 0.10 parts by weight, as a cell diameter regulator, Talc [manufactured by Hayashi Kasei Co., Ltd., Talcan powder PK-Z] 0.50 parts by weight, calcium stearate as a lubricant [manufactured by Sakai Chemical Industry Co., Ltd., SC-P] 0.20 parts by weight, as a water-absorbing medium, bentonite [ 0.40 part by weight of Hojun Co., Ltd., Wengerbright K11] and silica [Evonik Degussa Japan Co., Ltd., Carplex BS-304F] 0.40 part by weight were dry blended. However, the graphite was charged in advance as a master batch of styrene resin. The mixing concentration of the master batch was 50% by weight / 50% by weight of styrene resin / graphite.

[Production of extruded foam]
About 900 kg / hr of the obtained resin mixture to a single screw extruder (first extruder) having a diameter of 150 mm, a single screw extruder (second extruder) having a diameter of 200 mm, and an extruder in which a cooling machine is connected in series. Supplied with.
The resin mixture supplied to the first extruder is heated to a resin temperature of 240 ° C. to be melted or plasticized, kneaded, and foaming agent (0.7 parts by weight of water (tap water) with respect to 100 parts by weight of styrene resin) Then, 3.3 parts by weight of isobutane and 2.4 parts by weight of dimethyl ether were pressed into the resin near the tip of the first extruder, and then in a second extruder and a cooler connected to the first extruder, The resin temperature was cooled to 122 ° C., and extruded and foamed into the atmosphere at a foaming pressure of 3.4 MPa from a die having a rectangular cross section (slit die) having a thickness of 6 mm × width of 400 mm provided at the tip of the cooler. An extruded foam plate having a cross-sectional shape having a thickness of 60 mm × width of 1000 mm is obtained by a molding die placed in close contact with a molding roll installed downstream thereof, and cut into a thickness of 50 mm × width of 910 mm × length of 1820 mm with a cutter. And. Table 1 shows the evaluation results of the resulting foam.

(Examples 2 to 13)
As shown in Table 1, a foam was obtained by the same operation as in Example 1 except that the types, addition amounts and production conditions of various compounding agents were changed. However, the titanium oxide was added in advance as a master batch of a styrene resin. The mixing concentration of the master batch was 40% by weight / 60% by weight of styrene resin / titanium oxide. The evaluation results of the obtained foam are shown in Table 1.

(Comparative Examples 1-7)
As shown in Table 2, a foam was obtained by the same operation as in Example 1 except that the types, addition amounts and production conditions of various compounding agents were changed. However, the titanium oxide was added in advance as a master batch of a styrene resin. The mixing concentration of the master batch was 40% by weight / 60% by weight of styrene resin / titanium oxide. The evaluation results of the obtained foam are shown in Table 2.

  As is clear from the comparison between Examples 1 to 13 shown in Table 1 and Comparative Examples 1 to 7 shown in Table 2, in accordance with the present invention, a styrene resin containing a predetermined amount of brominated flame retardant was extruded and foamed. By molding and controlling the remaining amount of isobutane within a predetermined range, it is possible to easily obtain a high-performance and economical extruded styrene resin foam having excellent heat insulation and flame retardancy.

Claims (9)

  A styrene resin extruded foam obtained by extrusion foaming using a styrene resin and a foaming agent, comprising graphite, and containing 1.0 part by weight or more of brominated flame retardant for 100 parts by weight of styrene resin The residual amount of isobutane in the extruded foam after 4 days from the production of the extruded foam is 0.30 mol or more and 0.50 mol or less per kg of the extruded foam, and is specified in JIS A 9511. A styrene-based resin extruded foam, which passes the flammability test method A and has a fire spread length of 10 mm or less.   The residual amount of isobutane in the extruded foam after 4 days from the production of the extruded styrenic resin foam is 0.40 mol or more and 0.50 mol or less per 1 kg of the extruded foam. Styrene resin extruded foam.   The styrene resin extruded foam according to claim 1 or 2, wherein the thermal conductivity measured by a method according to JIS A9511 is 0.0245 W / mK or less.   The styrene resin extruded foam according to any one of claims 1 to 3, wherein the graphite is contained in an amount of 1.0 to 3.5 parts by weight with respect to 100 parts by weight of the styrene resin. .   The styrene resin extruded foam according to any one of claims 1 to 4, further comprising titanium oxide.   The styrene resin extruded foam according to claim 5, wherein the titanium oxide is contained in an amount of 1.0 to 4.0 parts by weight with respect to 100 parts by weight of the styrene resin.   The styrenic resin according to any one of claims 1 to 6, wherein the brominated flame retardant is contained in an amount of 1.0 to 4.0 parts by weight with respect to 100 parts by weight of the styrenic resin. Extruded foam. The styrene resin extruded foam according to any one of claims 1 to 7, wherein an apparent density is 20 kg / m ³ or more and less than 50 kg / m ³ .   A method for producing a styrene resin extruded foam by extrusion foaming using a styrene resin and a foaming agent, comprising graphite and containing 1.0 part by weight of a brominated flame retardant with respect to 100 parts by weight of a styrene resin A styrenic resin composition containing 6.0 parts by weight or less is heated and melted, and then a blowing agent containing at least isobutane is added under high pressure conditions. After cooling to a predetermined resin temperature, this is extruded into a low pressure region. By forming an extruded foam, and the residual amount of isobutane in the extruded foam after 4 days from the production of the extruded foam is 0.30 mol or more and 0.50 mol or less per kg of the extruded foam, A styrene resin extruded foam characterized in that the extruded foam passes the flammability test method A specified in JIS A9511 and has a fire spread length of 10 mm or less. Production method.