JP2016199674A - Styrenic resin extruded foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrenic resin extruded foam containing graphite which achieves both excellent heat insulation and flame retardancy, and achieves both excellent heat insulation and flame retardancy, especially, even when the foam is recycled and used.SOLUTION: A styrenic resin extruded foam contains graphite, and contains at least 0.6 wt.% or more of a residual amount of tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropyl)ether as a flame retardant, and 1.1-6.0 wt.% of a residual amount of tetrabromobisphenol-A-bis(2,3-dibromopropyl)ether.SELECTED DRAWING: None

Description

  The present invention relates to a graphite-containing styrene resin extruded foam having both excellent heat insulation and flame retardancy, and a method for producing the same.

  The styrene resin extruded foam is used as a heat insulating material for a structure because of good workability and heat insulation. In the case of producing a styrene-based resin extruded foam, the styrene-based resin extruded foam is heated and melted in an extruder, then added with a foaming agent, cooled, and extruded into a low-pressure region. Manufacture continuously.

  In order to satisfy the flammability standard of the extrusion method polystyrene foam heat insulating plate described in JIS A9511, a flame retardant is added to the styrene resin extruded foam. The extrusion temperature of general polystyrene is around 230 ° C., and it is required that the flame retardant does not decompose around this temperature, and an additive for improving the thermal stability of the flame retardant has been studied. It is known that flame retardancy tends to conflict with thermal stability (for example, Patent Document 1).

  In the case of producing a general styrene resin extruded foam, the extruded styrene resin extruded foam is cut by using a cutting machine. The cutting waste of the foam generated at that time, or the extruded foam It is common among those skilled in the art to perform heat treatment through an extruder or the like and reuse it as a raw material for recycling.

On the other hand, in recent years, demands for energy saving of houses, buildings and the like have increased, and technical development of highly heat-insulating foams more than conventional has been desired. Various techniques have already been proposed, and a technique of adding graphite or titanium oxide as a heat ray radiation suppressor has become the mainstream for increasing the heat insulation of styrene resin extruded foam. (For example, Patent Document 2)
However, styrene resin extruded foams containing graphite are more prone to degradation of flame retardants and resins during the manufacture of foams and in the recycling process when heat treatment is performed compared to styrene resin extruded foams not containing graphite. Inferior in flame retardancy. From such a background, in the styrene resin extruded foam containing graphite, an example in which recycling and reuse of the foam is realized while maintaining excellent heat insulation and flame retardancy has not yet been shown ( For example, Patent Document 3).

  In addition, the combustion of the foam is roughly divided into resin combustion and surface gas fire spreading. However, when graphite is included, surface gas fire spreading tends to proceed easily. In general, surface gas spread can be suppressed by (i) reducing the amount of flammable gas added during foam production, (ii) increasing the amount of flame retardant, or (iii) improving the thermal stability of the flame retardant, In i), the heat insulating performance of the foam is lowered, in (ii) the economic efficiency is deteriorated, and in (iii), there is a problem that an effective stabilizer blend is not found.

  As described above, in the styrene resin extruded foam containing graphite, it is very difficult to achieve both of these performances because heat insulation, flame retardancy, and recyclability are in a trade-off relationship.

JP 2012-172140 A JP 2004-196907 A JP 2014-129449 A

  An object of the present invention is to achieve both excellent heat insulation and flame retardancy in a styrene resin extruded foam containing graphite. In particular, even when the foam is recycled and used, it is an object to achieve both excellent heat insulation and flame retardancy.

  As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.

That is, the present invention
[1] Styrenic resin extruded foam containing graphite, containing at least tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether as a flame retardant, and tetrabromobisphenol The present invention relates to a styrene resin extruded foam, wherein the residual amount of -A-bis (2,3-dibromo-2-methylpropyl) ether is 0.6% by weight or more.

  [2] The styrene resin extruded foam according to [1], further containing tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether as a flame retardant.

  [3] The styrene resin extruded foam according to [2], wherein the residual amount of the tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether is 1.1% by weight or more. About.

  [4] The amount of the graphite added is 1.0 part by weight or more and 3.5 parts by weight or less based on 100 parts by weight of the styrenic resin. It relates to the styrene resin extruded foam described.

  [5] The styrene resin extruded foam according to any one of [1] to [4], wherein the styrene resin mixture contains a recycled styrene resin mixture in an amount of 10 wt% to 50 wt%. About the body.

  [6] The styrene resin mixture contains 0.1 part by weight or more and 0.5 part by weight or less of a polyhydric alcohol partial ester compound with respect to 100 parts by weight of the styrene resin. [1] It is related with the styrene-type resin extrusion foam in any one of-[5].

  [7] The extruded polystyrene foam according to [6], wherein the polyhydric alcohol partial ester compound is a reaction product of dipentaerythritol and adipic acid.

  [8] The styrenic resin extrusion according to any one of [1] to [7], comprising an epoxy compound as a stabilizer in an amount of 4 parts by weight to 20 parts by weight with respect to 100 parts by weight of the flame retardant. Relates to foam.

  [9] Any one of [1] to [8], wherein the amount of the flame retardant added is 2.0 parts by weight or more and 6.0 parts by weight or less with respect to 100 parts by weight of the styrene resin. The styrene resin extruded foam described in 1.

  [10] Mixing ratio of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether in the flame retardant (weight) The ratio is from 25:75 to 75:25. The styrene-based resin extruded foam according to any one of [2] to [9].

  [11] The foaming agent used in the styrene resin extruded foam contains a saturated hydrocarbon having at least 3 to 5 carbon atoms, and water, carbon dioxide, nitrogen, alcohols having 1 to 4 carbon atoms, The styrene resin extruded foam according to any one of [1] to [10], comprising at least one selected from the group consisting of dimethyl ether, methyl chloride, and ethyl chloride.

  [12] The styrenic system according to any one of [1] to [11], wherein the flammability measurement method A defined in JIS A9511 is passed and the fire spread length is 10 mm or less. The present invention relates to a resin extruded foam.

  [13] The styrene resin extruded foam according to any one of [1] to [12], wherein the thermal conductivity measured by a method defined in JIS A9511 is 0.024 W / mK or less. About.

  Moreover, this invention relates to the manufacturing method of the styrene resin extruded foam in any one of [14] [1]-[13].

  According to the present invention, it is possible to achieve both excellent heat insulation and flame retardancy in a styrene resin extruded foam containing graphite. In particular, when the foam is recycled and used, both excellent heat insulation and flame retardancy can be achieved.

  Embodiments of the present invention will be described below. In addition, this embodiment is only a part of this invention, and it cannot be overemphasized that this embodiment can be suitably changed in the range which does not change the summary of this invention.

  The present invention relates to an extruded foam of a styrenic resin, containing graphite, containing at least tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether as a flame retardant, and tetrabromo A styrene resin extruded foam characterized in that the residual amount of bisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether is 0.6% by weight or more.

  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 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 acid and itaconic anhydride.

  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 styrenic resin of the present invention may be a styrenic resin having a branched structure for the purpose of adjusting the melt flow rate (hereinafter referred to as MFR), the melt viscosity at the time of molding, the melt tension, and the like.

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

  Further, the styrene resin used in the present invention is not limited to virgin styrene resin, but styrene resin foam such as fish box EPS, household appliance cushioning material, food foam polystyrene tray, or polystyrene tray as refrigerator interior material. Recycled styrene resin can also be used.

  As the styrenic resin in the present invention, one having an MFR of 0.5 to 25 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 thermoplasticity It is easy to adjust the thickness, width, density, or closed cell ratio of the resin foam to a desired value, and the foamability (the thickness, width, density, closed cell ratio, surface property, etc. of the foam is easily adjusted to the desired situation. Thermoplastic foam with excellent balance of properties such as mechanical strength such as compressive strength, bending strength or bending deflection, and toughness. From the point that a body is obtained, it is preferable. Further, the MFR of the styrenic resin is particularly 1 to 12 g / 10 minutes from the viewpoint of the balance of the shear heating value generated at the time of melt kneading in the extruder, the molding processability, the mechanical strength with respect to foamability, the toughness and the like. preferable. In addition, in this invention, MFR is measured by A method and test condition H of JISK7210 (1999).

  In the present invention, a mixture composed of a styrene resin, a heat ray radiation inhibitor, a flame retardant and the like is defined as a “styrene resin mixture”. Also, a styrene resin extruded foam produced from the styrene resin mixture and the foaming agent, cutting waste generated when cutting the styrene resin extruded foam in the manufacturing process, styrene resin generated at the start of operation, etc. An extruded foam or a styrene resin extruded foam returned from a user is heat treated and defined as a “recycled styrene resin mixture”.

  In the present invention, apart from the styrene resin mixture, a recycled styrene resin mixture can also be used as a raw material. The recycled styrene-based resin mixture may be put into the extruder as it is, but generally it is preferable to perform volume reduction or melt processing (pelletization) so that it can be easily put into the extruder. The pelletization is generally performed by melting and kneading with an extruder, and preferably includes a temperature at which molecular degradation of the resin is suppressed as much as possible, including the influence of a flame retardant, for example, about 160 to 240 ° C. . Further, it is desirable to provide a vent port in order to deaerate the foaming agent in the styrene resin extruded foam or the cutting waste of the foam.

  The recycled styrene resin mixture in the present invention preferably contains 10% by weight or more and 50% by weight or less based on the total amount of the styrene resin mixture. From the viewpoint of the production cost of the foam and the heat insulation performance, the recycled styrene resin mixture is more preferably contained in an amount of 25% by weight to 45% by weight, more preferably 30% by weight to 40% by weight based on the total of the styrene resin mixture. More preferably, it is contained below.

  If the content of the recycled styrene resin mixture is less than 10% by weight, the use amount is insufficient with respect to the amount of the recycled material generated, and it is necessary to substantially discard the recycled material. When it exceeds%, there is a tendency to cause deterioration of heat insulation performance due to deterioration of foam formability, cell shape enlargement, and the like.

  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 fixed carbon content of graphite is preferably 80% by weight or more and 89% by weight or less from the viewpoint of heat insulation performance and production cost of the obtained styrene resin extruded foam.

  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. When 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 using a thermogravimetric measurement apparatus: TG / DTA 220U [manufactured by SII Nanotechnology Co., Ltd.] equipped with a thermal analysis system: EXSTAR6000 (I ) Temperature was raised from 40 ° C. to 600 ° C. at 20 ° C./min under a nitrogen stream of 200 mL / min and then held at 600 ° C. for 10 minutes. (II) 10 ° C. from 600 ° C. to 400 ° C. under a nitrogen stream of 200 mL / min The temperature is lowered at / min and then held at 400 ° C. for 5 minutes. (III) 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 = reduced weight at (III) / 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.

  The content of the white particles in the present invention is preferably 1.0 part by weight or more and 3.5 parts by weight or less, and 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. More preferred. 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 3.5 parts by weight, the effect of suppressing heat radiation corresponding to the content cannot be obtained, and there is no cost merit.

  The total content of the heat ray radiation inhibitor in the present invention 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 and 5.0 parts by weight or less with respect to 100 parts by weight of the styrene resin. 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.

  The addition amount of the brominated flame retardant in the styrene resin extruded foam of the present invention passes the flammability measuring method A specified in JIS A9511, and the surface gas spread length is 10 mm or less in the measuring method. In order to be able to show flame retardancy, it is 2.0 parts by weight or more, preferably 3.0 parts by weight or more with respect to 100 parts by weight of the styrenic resin. In order to maintain the thermal stability of the styrene-based resin and to hardly impair the surface properties of the foam, 6.0 parts by weight or less is desirable.

  The brominated flame retardant used in the present invention is tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether (hereinafter “flame retardant A”). Further, it preferably contains tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether (hereinafter referred to as “flame retardant B”).

  In this invention, it is preferable to use together the flame retardant A and the flame retardant B, and it is preferable that these mixing ratios (weight ratio) are 25:75 to 75:25.

  Although the reason is not clear, when the mixing ratio (weight ratio) of the flame retardant A and the flame retardant B is 25:75 to 75:25 in the styrene resin extruded foam, the flame retardant of the obtained extruded foam Regarding the performance, because the high flame retardant performance of flame retardant A has an effect, the low flame retardant performance, which was the disadvantage of flame retardant B as the mixing partner, is negated, and it is as if it is flame retardant A alone. The fuel performance can be expressed. On the other hand, regarding the thermal stability of the obtained extruded foam, the content of the flame retardant A having a low thermal stability performance can be reduced, and instead the flame retardant B having a high thermal stability can be contained. The properties can be made higher than when flame retardant A is used alone.

  In the flame retardant mixing ratio (weight ratio), when the ratio of the flame retardant A is smaller than 25:75, the flame retardant of the obtained foam tends to be inferior, and the ratio of the flame retardant A than 75:25 When is large, thermal stability at the time of foam production or recycling tends to deteriorate. In consideration of the dispersion and variation of the flame retardant in the styrene resin, when trying to stably obtain higher flame retardancy and higher thermal stability, the flame retardant A and the flame retardant B The mixing ratio (weight ratio) is more preferably in the range of 30:70 to 70:30.

  In the present invention, the amount of the flame retardant A remaining without being decomposed in the production process of the styrene resin extruded foam is set to 0.6% by weight or more, which is a problem in the case of containing graphite. (Especially surface gas spread) can be improved. In particular, if the remaining amount of flame retardant A having high flame retardancy is 0.7% by weight or more, the influence of variation in the remaining amount of the combustible gas in the foam can be suppressed, and the flame retardancy can be more stably performed. Satisfactory heat insulation. When the amount of the flame retardant A is less than 0.6% by weight, good flame retardancy cannot be obtained.

  The residual amount of the flame retardant B is preferably 1.1% by weight or more so that the thermal stability of the flame retardant A can be enhanced to stably ensure good flame retardancy. Moreover, it is preferable that it is 6.0 weight% or less.

  Further, when the total remaining amount of the flame retardants A and B is 6.0% by weight or more, the thermal stability during the production of the foam, the surface property of the foam, and the like may be impaired.

  Examples of the method for maintaining the residual amount of the flame retardant at a certain level include, for example, improving the thermal stability of the flame retardant by adding a stabilizer, suppressing the number of times of recycling and the ratio of the recycled styrene resin mixture, and foam production. And lowering the temperature of the extruder at the time of recycling or recycling.

  In the present invention, a polyhydric alcohol partial ester compound is preferably used in combination as a stabilizer in order to improve the thermal stability of the flame retardant and suppress the decomposition of the resin / flame retardant even during recycling.

  Examples of the polyhydric alcohol partial ester compound used in the present invention include polyhydric alcohols such as pentaerythritol, dipentaerythritol and tripentaerythritol, and monovalent carboxylic acids such as acetic acid and propionic acid, or adipic acid and glutamic acid. It is a partial ester which is a reaction product with the divalent carboxylic acid, and is a mixture of compounds having one or more hydroxyl groups in the molecule, and may contain a small amount of the starting polyhydric alcohol.

  Specific examples of the polyhydric alcohol partial ester compound include a partial ester of dipentaerythritol and adipic acid and a reaction product of a polyhydric alcohol, for example, Ajinomoto Fine Techno Co., Ltd. Plenizer ST-210, Plenizer ST-220, etc. are mentioned.

  The content of the polyhydric alcohol partial ester in the present invention is preferably 0.1 parts by weight or more and 0.5 parts by weight or less with respect to 100 parts by weight of the styrenic resin.

  When the content of the polyhydric alcohol partial ester compound is less than 0.1 parts by weight, the thermal stabilization effect tends to be small. On the other hand, if the content of the polyhydric alcohol partial ester compound exceeds 0.5 parts by weight, the stabilization effect is greatly exerted, and the inherent flame retarding effect may be reduced.

  In the present invention, it is preferable to contain an epoxy compound as a stabilizer in order to improve the thermal stability without impairing the flame retardant performance of the flame retardant. As content of the epoxy compound in this invention, 4 to 20 weight part is preferable with respect to 100 weight part of brominated flame retardants. When the content of the epoxy compound is less than 4 parts by weight, the flame retardant stabilizing effect is not sufficiently exhibited, the flame retardant and the resin are decomposed, and the molecular weight of the resin tends to decrease, resulting in foaming. The bubble diameter which forms a body enlarges, and there exists a tendency for heat insulation performance to deteriorate. Further, with the decrease in molecular weight, the smoothness of the foam surface tends to deteriorate and the moldability tends to deteriorate. Furthermore, decomposition of the flame retardant causes other additives or resins to turn black, leading to poor appearance. In addition, when recycling scraps that are generated by heat melting and kneading scraps produced during product cutting, etc., flame retardants and resin decomposition tend to occur, which tends to cause resin blackening and molecular weight reduction. As a result, recycling becomes difficult, leading to an increase in cost.

  On the other hand, when the content of the epoxy compound exceeds 20 parts by weight, the stabilizing effect of the stabilizer becomes excessive, and the flame retardant cannot be effectively decomposed when the foam is burned, and the flame retardant performance tends to be lowered. is there.

  As an epoxy compound used by this invention, it is preferable that an epoxy equivalent is less than 1000 g / eq. It is thought that the epoxy group suppresses the decomposition of the brominated flame retardant and improves the thermal stability performance of the styrene resin. Therefore, when the epoxy equivalent is 1000 g / eq or more, the decomposition suppressing effect of the flame retardant is very high. Therefore, since it is necessary to add a large amount of a flame retardant as a result, it is not practical in terms of cost. In view of the balance between cost and performance, it is more preferably less than 500 g / eq, and still more preferably less than 400 g / eq.

  The chemical structure of the epoxy compound used in the present invention is a bisphenol A diglycidyl ether type epoxy resin represented by the structural formula (1) in terms of cost, performance and supply stability.

, A cresol novolac type epoxy resin represented by the structural formula (2)

A phenol novolac epoxy resin represented by the structural formula (3)

Is desirable.
Also, bromine added to the bisphenol A skeleton represented by the structural formula (4)

May be used. These may be used singly or in combination of two or more.

  The blowing agent of the present invention contains at least a saturated hydrocarbon having 3 to 5 carbon atoms, and further from water, carbon dioxide, nitrogen, alcohols having 1 to 4 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride. It is preferable to include at least one selected from the group consisting of:

  Examples of the saturated hydrocarbon having 3 to 5 carbon atoms used in the present invention include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and the like. Among these saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, i-butane, or a mixture thereof is preferable from the viewpoint of foamability. Further, n-butane, i-butane (hereinafter sometimes referred to as “isobutane”), or a mixture thereof is preferred from the viewpoint of the heat insulating performance of the foam, and i-butane is particularly preferred.

  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 another foaming agent, a plasticizing effect and an auxiliary foaming effect at the time of foam production can be obtained, the extrusion pressure can be reduced, and the foam can be stably produced.

  Examples of other foaming agents include ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methyl furan, tetrahydrofuran, and 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. A saturated alcohol having 1 to 4 carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol; Carboxylic acid esters such as acid methyl ester, formic acid ethyl ester, formic acid propyl ester, formic acid butyl ester, formic acid amyl ester, propionic acid methyl ester, propionic acid ethyl ester; alkyl halides such as methyl chloride and ethyl chloride, trans-1 Organic foaming agents such as 3,3,3-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 other foaming agents, from the viewpoints of foamability, foam formability, etc., saturated alcohols having 1 to 4 carbon atoms, dimethyl ether, diethyl ether, methyl ethyl ether, methyl chloride, ethyl chloride, etc. are preferable. From the viewpoints of the flammability of the foam, the flame retardancy of the foam, the heat insulation properties described later, and the like, water and carbon dioxide are preferred. Among these, dimethyl ether is particularly preferable from the viewpoint of the plasticizing effect, and water is particularly preferable from the viewpoint of the effect of improving the heat insulation by controlling the cost and the bubble diameter.

  The blowing agent used in the present invention contains at least isobutane, and at least one selected from the group consisting of water, carbon dioxide, nitrogen, alcohols having 2 to 5 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride. The inclusion of the above is preferable in that the heat insulation performance, foamability, foam moldability and the like 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 parts by weight or more and 20 parts by weight or less, and more preferably 2 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the styrene resin. When the 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, by passing the residual amount of isobutane in the extruded foam one week after the production of the styrene resin extruded foam to a predetermined amount, the combustion test method according to JIS A9511 measuring method A is passed. In addition, it is possible to obtain a styrene-based extruded foam having a fire spread length of 10 mm or less and having excellent heat insulation.
The residual amount of isobutane in the extruded foam one week after the production of the styrene resin extruded foam is preferably 0.30 mol or more and 0.60 mol or less, and 0.40 mol or more and 0.50 mol or less per kg of the extruded foam. More preferred. If it is less than 0.30 mol, there is little isobutane in a foam within a foam in which heat conductivity is lower than air, and the heat insulation which was excellent in the extrusion foam cannot be provided. On the other hand, if the amount of isobutane having high combustibility exceeds 0.60 mol, the combustion test method according to JIS A9511 may be rejected.

  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] etc. Fine powder with a particle size of 1000 nm or less having a hydroxyl group on the surface; water absorption or water swellability such as smectite, swellable fluorine mica, bentonite Layered silicates and their organically treated products: zeolite, activated carbon, Lumina, silica gel, porous glass, activated clay, porous material or the like, such as diatomaceous earth and the like.

  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. Preferably, it is 0.1 to 3 parts by weight.

  In the present invention, if necessary, processing aids such as fatty acid metal salts, fatty acid amides, fatty acid esters, liquid paraffin, and olefinic wax, flame retardants other than those described above, and flame retardant, as long as the effects of the present invention are not impaired. Additives such as auxiliaries, antioxidants, antistatic agents, and colorants such as pigments can be contained.

  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 styrenic resin to form a fluid gel, cooled to a temperature suitable for extrusion foaming, and then extruded and foamed through a die into a low pressure region to form a foam.

  As a form of heat melting of styrene resin, flame retardant, stabilizer, and other additives, the flame retardant and additive are mixed with styrene resin and then heated and melted; the styrene resin is heated and melted. After adding a brominated flame retardant and other additives, the styrene resin is previously mixed with a brominated flame retardant, stabilizer, and other additives, and then a heated and melted composition is prepared. It is supplied to an extruder and heated and melted.

There are no particular limitations on the heating temperature, melt kneading time, and melt kneading means when the styrene resin and additives such as a foaming agent are heated and melt kneaded.
The heating temperature may be equal to or higher than the temperature at which the styrenic resin to be used is melted, but preferably includes a temperature at which molecular degradation of the resin is suppressed as much as possible, including the influence of a flame retardant, for example, about 160 to 240 ° C. Preferably it is 230 degrees C or less.
The melt-kneading time varies depending on the amount of extrusion per unit time, the melt-kneading means, etc., and thus cannot be determined unconditionally. However, the time required for uniformly dispersing and mixing the styrene resin and the foaming agent is appropriately selected.

  Examples of the melt-kneading means include a screw-type extruder, but there is no particular limitation as long as it is 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.

  The thickness of the styrene-based resin extruded foam according to the present invention is not particularly limited, but for example, heat insulation, bending strength, and compressive strength in consideration of functioning as a heat insulator for a building, a cold storage, or a cold car. In view of the above, it is preferably 10 mm or more and 160 mm or less, and more preferably 20 mm or more and 100 mm or less.

  The styrene resin extruded foam according to the present invention has a thermal conductivity of 0 measured by the method defined in JIS A9511 from the viewpoint of excellent heat insulation by sufficiently exhibiting the effect of suppressing the heat ray radiation derived from graphite. It is preferably 0.024 W / mK or less.

  The density of the styrene resin extruded foam of the present invention is preferably 15 to 50 kg / m 3, preferably 25 to 40 kg / m 3 in order to give light weight and excellent heat insulating properties, bending strength, and compressive strength. It is more preferable that

  Thus, according to the present invention, the heat conductivity measured by the method specified in JIS A9511 is shown, which has passed the flammability measuring method A specified in JIS A9511 and exhibits flame retardancy with a fire spread length of 10 mm or less. A styrene-based resin extruded foam having both excellent flame retardancy and heat insulation properties, with a rate of 0.024 W / mK or less, can be easily obtained.

  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.
(A) Base resin / styrene resin [manufactured by PS Japan Co., Ltd., G9401; MFR 2.2 g / 10 min]
(B) Heat-ray radiation inhibitor / graphite [Maruho Foundry Mfg. Co., Ltd., M-885; scale (flaky) graphite, primary particle size 5.5 μm, fixed carbon content 89%]
Titanium oxide [manufactured by Sakai Chemical Industry Co., Ltd., R-7E; primary particle size 0.23 nm]
(C) Flame retardant, tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether (about 39% by weight, abbreviated as “flame retardant A”), tetrabromobisphenol-A-bis (2, 3-dibromopropyl) ether (about 59% by weight; abbreviated “flame retardant B”), phosphite compound and hindered amine compound (total about 2% by weight) mixed brominated flame retardant [Daiichi Kogyo Seiyaku Co., Ltd., GR -125P]
(D) Flame retardant aid, triphenylphosphine oxide [Sumitomo Corporation Chemical]
(E) Polyhydric alcohol partial ester compound / dipentaerythritol-adipic acid reaction mixture [manufactured by Ajinomoto Fine-Techno, Pleniser ST210]
(F) Epoxy compound / bisphenol-A-glycidyl ether [manufactured by ADEKA, EP-13]
-Cresol novolac epoxy resin [manufactured by Huntsman Japan, ECN-1280]
(G) Stabilizer / Triethylene glycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate [Songwon Japan Co., Ltd., Sonnox 2450FF]
(H) Foaming agent, isobutane [Mitsui Chemicals, Inc.]
・ Dimethyl ether [Made by Iwatani Corporation]
・ Water [Tap water]
(I) Other additives
・ Talc [Hayashi Kasei Co., Ltd., Talcan powder PK-Z]
・ 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].

  The evaluation methods implemented in the examples and comparative examples are as follows.

(1) Apparent density (kg / m3)
The weight and volume of the obtained styrene resin extruded foam were measured, the foam density was determined based on the following formula (3), and the unit was converted to kg / m3.
Apparent density (g / cm3) = foam weight (g) / foam volume (cm3) (3).

(2) Residual amount of isobutane Extruded styrene resin foam obtained was classified into standard temperature state class 3 (23 ° C. ± 5 ° C.) and standard humidity state class 3 (50 + 20, −10% RH) as defined in JIS K7100. The remaining amount of isobutane after 7 days from the production of the foam was evaluated by the following equipment and procedure.

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
Put about 1.2g of test piece into an approximately 130cc sealable glass container (hereinafter referred to as "sealed container"), depending on the apparent density cut out from the foam, and evacuate the sealed container with 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.

(3) Weight average molecular weight retention of foam (hereinafter abbreviated as “Mw retention”)
In order to evaluate the degree of resin deterioration associated with the heat history in the extruder, the weight average molecular weight Mw of the obtained foam was determined by the gel permeation chromatography method according to the following procedure.

a) Sample concentration: 2.5 mg / mL (solvent; chloroform)
b) Equipment used: Waters e2695
c) Column used: GPC-K-806M (manufactured by SHODEX) 2 directly connected d) Measurement conditions: temperature: 40 ° C., solvent: chloroform, sample injection amount: 50 μL, flow rate: 1.0 mL / min, detection method: UV (254 nm), standard polystyrene; SHODEX STANDARD SM-105
The value obtained by dividing the weight average molecular weight Mw of the obtained foam by the weight average molecular weight Mw of the foam whose number of recycles was zero was evaluated as the Mw retention rate of the foam.

(4) Flame retardant residual amount and flame retardant residual rate In order to evaluate the degree of flame retardant degradation accompanying thermal history in the extruder, the amount of flame retardants A and B contained in the obtained foam was measured by liquid chromatography. It was determined by the following procedure using the graph method. However, since the flame retardant B may not be able to be accurately measured due to the deterioration of the flame retardant, the evaluation value of the flame retardant B is a reference value.

a) Sample concentration: 10.0 mg / mL (solvent; chloroform: methanol = 1: 1 (volume ratio))
b) Equipment used: Waters e2695
c) Column used: Hypercarb 35003-052130 [manufactured by Thermo Fisher Scientific Co.]
d) Measurement conditions: temperature; 40 ° C., solvent; chloroform: methanol = 1: 1 (volume ratio), sample injection amount: 10 μL, flow rate; 0.5 mL / min, detection method; UV (254 nm)
The amount of flame retardant remaining in the foam was evaluated as “the amount of flame retardant remaining in the foam after production” in the formula (4) defined below.
Flame retardant residual ratio [%] = Amount of flame retardant remaining in the foam after production [wt%] / Amount of flame retardant added [wt%] × 100 (4).

(5) JIS flammability, fire spread length Based on JIS A9511: 2006R (measurement method A is adopted), a test piece having a thickness of 10 mm, a length of 200 mm, and a width of 25 mm is used. After being manufactured, the test piece having the above dimensions was cut, and the standard temperature state class 3 (23 ° C. ± 5 ° C.) and the standard humidity state class 3 (50 + 20, −10% RH) defined in JIS K7100 were cut. The test was carried out after 7 days had passed since the foam was produced.

As an evaluation standard for JIS flammability, the extinction time was an average value of the measurement results of five test pieces, and the pass / fail criterion was as follows.
○ (Pass): Satisfies the criteria 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 spread of the surface gas in which only the surface of the foam is combusted by the spread of the combustible gas contained in the foam, the length (mm) of the fire that exceeds the combustion limit indicator line was measured as the “fire spread length”. . “Fire spread length” was an average value of the measurement results of five test pieces.

  In addition, when the gas surface combustion was extinguished without exceeding the combustion limit indicating line, the “fire spread length” was regarded as zero.

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

Example 1
[Preparation of styrene resin mixture]
With respect to 100 parts by weight of styrene resin, 2.5 parts by weight of graphite (M-885), 1.5 parts by weight of titanium oxide (R-7E) as a heat ray radiation inhibitor, flame retardant A and flame retardant as flame retardants B mixed brominated flame retardant (GR-125P) 3.0 parts by weight, triphenylphosphine oxide 1.0 part by weight as a flame retardant aid, dipentaerythritol-adipic acid reaction mixture (polyhydric alcohol partial ester compound ( (Plenizer ST210) 0.1 part by weight, 0.2 parts by weight of bisphenol-A-glycidyl ether (EP-13) as a stabilizer (corresponding to 6.7 parts by weight with respect to 100 parts by weight of flame retardant), Triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (Sonnox 2450FF) 0. Parts by weight, 0.5 parts by weight of talc (Talcan powder PK-Z) as a bubble diameter adjusting agent, 0.2 parts by weight of calcium stearate (SC-P) as a lubricant, bentonite (Wengerbright K11) 0. 4 parts by weight and 0.4 parts by weight of silica (Carplex BS-304F) were dry blended. The dry blended styrenic resin mixture is referred to as “GP”.

  However, the graphite and titanium oxide were added in advance as a master batch of a styrene resin. The mixing concentration of the master batch was 50% by weight / 50% by weight of styrene resin / graphite and 40% / 60% by weight of styrene resin / titanium oxide.

[Production of extruded foam]
About 900 kg of the resulting styrene-based resin mixture is fed 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 cooler is connected in series. / Hr.

  The styrene resin mixture supplied to the first extruder is heated to a resin temperature of 230 ° C. to be melted or plasticized, kneaded, and foaming agent (3.3 parts by weight of isobutane, 100 parts by weight of styrene ether resin, dimethyl ether). 2.4 parts by weight and 0.7 part of water were press-fitted into the resin near the tip of the first extruder, and then the resin temperature in the second extruder and the cooler connected to the first extruder. And a molding die placed in close contact with the die after being extruded and foamed into the atmosphere from a rectangular cross-section die (slit die) of 6 mm thickness x 400 mm width 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 was obtained by a forming roll installed on the downstream side, and was cut into a thickness of 50 mm × width of 910 mm × length of 1820 mm with a cutter. And 0-th of the foam.

[Production of recycled styrene resin mixture]
The obtained foam was pulverized with a crusher, and the cut waste generated when the foam was cut into a predetermined size with a cutter was supplied to a single-screw extruder having a diameter of 120 mm, and the resin temperature was about 230 ° C. The mixture was heated, melted or plasticized, kneaded, the foaming agent remaining in the foam was removed under open vent conditions, then discharged from a die, and pelletized by sheet cutting. The recycled styrene resin mixture is referred to as “RP”.

[Production of extruded foam containing recycled styrene resin mixture]
The obtained RP and GP were connected in series at a ratio of 50:50, 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 a cooler. Extruded foam was obtained by the same operation as the above-mentioned extruded foam production conditions except that it was supplied to the extruder at about 900 kg / hr. The obtained foam was used as the first foam for recycling.

  Thereafter, recycling was performed 2 to 5 times under the same conditions for producing a recycled resin and a recycled resin-containing extruded foam. Table 1 shows the physical properties of the obtained foam.

(Examples 2 to 4)
As shown in Table 1, a foam was obtained in the same manner as in Example 1 except that the types and addition amounts of various compounding agents and the production conditions were changed. Table 1 shows the physical properties of the obtained foam.

(Comparative Examples 1-4)
As shown in Table 2, a foam was obtained in the same manner as in Example 1 except that the types and addition amounts of various compounding agents and the production conditions were changed. Table 2 shows the physical properties of the obtained foam.

  From Examples 1 to 4, by adding graphite and managing the remaining amount of flame retardant within the scope of the claims, a foam having excellent heat insulation and excellent flame retardancy can be obtained. I understand.

  On the other hand, it can be seen from Comparative Example 1 that the flame retardant residual amount that does not reach the scope of the claims is inferior in flame retardancy. From Comparative Example 2, it can be seen that when no radiation inhibitor is used (= addition amount of the radiation inhibitor does not reach the range of the claims), the flame retardancy is satisfied but the heat insulation is inferior. From Comparative Example 3, it can be seen that when the GP / RP ratio exceeds the scope of the claims, an increase in thermal conductivity due to cell enlargement of the foam and a deterioration in flame retardancy due to a decrease in the residual ratio of the flame retardant are observed. From the comparative example 4, in the case of the addition amount of the polyhydric alcohol partial ester compound which does not reach the scope of the claims, the residual amount of the flame retardant decreases due to the decrease in the thermal stability of the flame retardant during the production of the foam. It turns out that it is inferior to flammability.

  From the above, it can be seen that the present invention makes it possible to easily obtain a styrene resin extruded foam having excellent heat resistance while maintaining heat insulation. Moreover, since the said performance can be maintained also at the time of recycling, it can be said that it is excellent also in environmental performance and economical efficiency.

Claims (14)

A styrenic resin extruded foam containing graphite, containing at least tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether as a flame retardant, and tetrabromobisphenol-A- A styrene-based resin extruded foam, wherein the residual amount of bis (2,3-dibromo-2-methylpropyl) ether is 0.6% by weight or more. The styrene resin extruded foam according to claim 1, further comprising tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether as a flame retardant. The styrenic resin according to claim 2, wherein the residual amount of the tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether is 1.1 wt% or more and 6.0 wt% or less. Extruded foam. The styrene resin according to any one of claims 1 to 3, wherein an amount of the graphite added is 1.0 part by weight or more and 3.5 parts by weight or less with respect to 100 parts by weight of the styrene resin. Extruded foam. The styrene resin extruded foam according to any one of claims 1 to 4, wherein the styrene resin mixture contains 10% by weight or more and 50% by weight or less of a recycled styrene resin mixture. The styrenic resin mixture contains 0.1 to 0.5 parts by weight of a polyhydric alcohol partial ester compound with respect to 100 parts by weight of a styrenic resin. The styrene resin extruded foam according to any one of the above. The styrene resin extruded foam according to claim 6, wherein the polyhydric alcohol partial ester compound is a reaction product of dipentaerythritol and adipic acid. The styrene resin extruded foam according to any one of claims 1 to 7, comprising an epoxy compound as a stabilizer in an amount of 4 parts by weight to 20 parts by weight with respect to 100 parts by weight of the flame retardant. The amount of the flame retardant added is 2.0 parts by weight or more and 6.0 parts by weight or less with respect to 100 parts by weight of the styrenic resin. Resin extruded foam. The mixing ratio (weight ratio) of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol-A-bis (2,3-dibromopropyl) ether in the flame retardant is The styrene resin extruded foam according to any one of claims 2 to 9, characterized in that the ratio is from 25:75 to 75:25. The foaming agent used in the styrene resin extruded foam contains at least a saturated hydrocarbon having 3 to 5 carbon atoms, water, carbon dioxide, nitrogen, alcohols having 1 to 4 carbon atoms, dimethyl ether, and chloride. The styrene resin extruded foam according to any one of claims 1 to 10, comprising at least one selected from the group consisting of methyl and ethyl chloride. The styrene-based resin extruded foam according to any one of claims 1 to 11, which passes the flammability measurement method A defined in JIS A9511 and has a fire spread length of 10 mm or less. The styrenic resin extruded foam according to any one of claims 1 to 12, wherein the thermal conductivity measured by a method defined in JIS A9511 is 0.024 W / mK or less. The manufacturing method of the styrene resin extrusion foam in any one of Claims 1-13.