JP5787358B2 - Method for producing extruded polystyrene resin foam - Google Patents

Description

  The present invention relates to a method for producing a polystyrene resin extruded foam. More specifically, the present invention relates to a polystyrene resin extruded foam having excellent flame retardancy and high heat insulation, excellent thermal stability, and excellent recyclability. The present invention relates to a method for producing a polystyrene-based resin extruded foam that is suitably used for heat insulating materials such as walls, floors, and roofs of buildings, tatami core materials, and the like and is mainly formed in a plate shape.

  Conventionally, an air conditioner is added to a polystyrene-based resin material, heated and melt-kneaded with an extruder, then a physical foaming agent is pressed into the extruder and further kneaded, and the molten mixture is extruded from a high-pressure region to a low-pressure region, A method is known in which a shaping apparatus is connected to a die outlet of an extruder to obtain a high-thickness polystyrene resin extruded foam (hereinafter also referred to as an extruded foam or foam).

In order to use the extruded foam as a heat insulating material for construction, for example, it is required to satisfy the flammability standard of an extruded polystyrene foam heat insulating plate described in JIS A 9511 (1995). For this purpose, a flame retardant is added to the extruded foam, and hexabromocyclododecane (hereinafter referred to as HBCD) has been widely used as the flame retardant. HBCD is an excellent flame retardant that is versatile and can provide a flame retardant effect with a relatively small amount of addition.
However, there is a movement of regulation by the Chemical Substances Control Law and REACH for HBCD, and it is required to develop a flame retardant alternative extrusion foam manufacturing technology that does not use HBCD flame retardant assuming that it is designated as a regulated substance. ing.

  On the other hand, chlorofluorocarbons (hereinafter referred to as CFC), such as dichlorodifluoromethane, have been widely used as a foaming agent in the process for producing extruded foams. CFCs that are suspected of being refractory are refrained from use, and hydrogen atom-containing fluorinated fluorinated hydrocarbons (hereinafter referred to as HCFC) with a low ozone depletion potential and hydrogen atom-containing fluorinated hydrocarbons with an ozone depletion potential of 0 (zero) (Hereinafter referred to as HFC) has been used instead of CFC. Furthermore, from the viewpoint of global warming, saturated hydrocarbons such as isobutane and isopentane having an ozone depletion coefficient of 0 (zero) and a small global warming coefficient have been used instead of HCFC and HFC.

  However, since saturated hydrocarbons such as butane are flammable, in order to impart sufficient flame retardancy to polystyrene-based resin extruded foams, compared to the case of using non-flammable foaming agents such as HFC. Many flame retardants had to be added. When a large amount of a flame retardant is added, there is a new problem that stability of extrusion foaming is remarkably impaired or physical properties of the obtained foamed plate are impaired.

  In the above situation, a polystyrene resin extruded foam using an excellent flame retardant other than HBCD has been studied. For example, Patent Document 1 discloses using halogenated aromatic alkyl allyl ethers such as tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) as a flame retardant. Patent Document 2 discloses, as a flame retardant, (a) a bromine-containing organic compound having a 2,3-dibromopropyl group and (b) a bromine-containing organic compound having a 2,3-dibromo-2-alkylpropyl group. And using a mixture thereof.

  However, since tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) of Patent Document 1 has insufficient thermal stability, the polystyrene resin as the base resin is decomposed. Even if there is a problem such as a decrease in molecular weight or a problem that the amount of flame retardant added must be increased on the assumption of thermal decomposition of the flame retardant, even if the recovered extruded foam is recycled, There was a problem that the polystyrene resin was decomposed to lower the molecular weight, and the recovered raw material turned yellow. In addition, the mixture of (a) a bromine-containing organic compound having a 2,3-dibromopropyl group and (b) a bromine-containing organic compound having a 2,3-dibromo-2-alkylpropyl group in Patent Document 2 Although there is some improvement in stability, there is still room for improvement. When the polystyrene resin extruded foam containing the mixture is recycled, the polystyrene resin in the recovered raw material decomposes and the molecular weight decreases, and recovery The problem of yellowing of raw materials has not been solved.

JP 2005-139356 A JP 2010-275528 A

  In view of the above-mentioned problems, the present invention improves the problems such as the flame retardant blended is excellent in thermal stability, the polystyrene resin as the base resin is decomposed during extrusion foaming and the molecular weight is reduced, and the like is recycled. An object of the present invention is to provide a method for producing a polystyrene resin extruded foam excellent in flame retardancy, in which a decrease in molecular weight and yellowing are suppressed.

According to this invention, the manufacturing method of the polystyrene-type resin extrusion foam shown below is provided.
[1] In a process for producing an extruded foam in which a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant and a foaming agent is extruded and foamed,
The flame retardant comprises (1) an organic compound having a 2,3-dibromo-2-methylpropyl group, (2) an organic compound having a 2,3-dibromopropyl group, and (3) a brominated epoxy resin,
(1) 0.5 to 4.5 parts by weight of an organic compound having 2,3-dibromo-2-methylpropyl group, and (2) 2,3-dibromopropyl group, relative to 100 parts by weight of the polystyrene resin A method for producing a polystyrene-based resin extruded foam, comprising blending 0.5 to 4.5 parts by weight of an organic compound having a content of (3) and 0.05 to 1 part by weight of a brominated epoxy resin.
[2] One or more heat stabilizers selected from a hindered phenol stabilizer, a phosphorus stabilizer, and a hindered amine stabilizer are blended in the polystyrene resin together with the flame retardant. 2. A process for producing a polystyrene resin extruded foam according to 1.
[3] A halogen different from any of (1) an organic compound having a 2,3-dibromo-2-methylpropyl group, (2) an organic compound having a 2,3-dibromopropyl group, and (3) a brominated epoxy resin 3. The method for producing a polystyrene-based resin extruded foam according to 1 or 2, wherein a flame retardant is further blended.
[4] The blowing agent comprises (A) 10 to 80 mol% of a saturated hydrocarbon having 3 to 5 carbon atoms, and (B) methyl chloride, ethyl chloride, dimethyl ether, diethyl ether, methyl ethyl ether, methanol, ethanol, water And 90 to 20 mol% of one or more blowing agents selected from carbon dioxide (however, the total amount of the blowing agent (A) and the blowing agent (B) is 100 mol%). The manufacturing method of the polystyrene-type resin extrusion foam in any one of said 1-3 characterized by these.
[5] The polystyrene resin comprises (1) an organic compound having a 2,3-dibromo-2-methylpropyl group, (2) an organic compound having a 2,3-dibromopropyl group, and (3) a brominated epoxy resin. 2. A method for producing a polystyrene resin extruded foam according to 1 above, comprising a recycled polystyrene resin composition obtained by heating and melting a polystyrene resin extruded foam comprising:

  In the present invention, (1) an organic compound having a 2,3-dibromo-2-methylpropyl group, (2) an organic compound having a 2,3-dibromopropyl group, and (3) a brominated epoxy resin are in a specific amount. The blended mixture is used as a flame retardant, and a polystyrene resin extruded foam blended with the flame retardant is excellent in flame retardancy. In addition, the flame retardant is excellent in thermal stability, and the polystyrene resin as a base resin is decomposed at the time of extrusion foaming, and the problems such as reduction in molecular weight are improved, and a polystyrene resin extruded foam having stable mechanical properties. Is obtained. In addition, the flame retardant has an effect of suppressing a decrease in molecular weight and yellowing of the recycled raw material when the obtained polystyrene resin extruded foam is heated and melted and reused as a recycled raw material.

Hereinafter, the manufacturing method of the polystyrene-type resin extrusion foam of this invention is demonstrated in detail.
The manufacturing method of the polystyrene-type resin extrusion foam of this invention employ | adopts the manufacturing method of the extrusion foam which extrude-foams the foamable molten resin composition obtained by knead | mixing a polystyrene-type resin, a flame retardant, and a foaming agent. As a specific example, polystyrene resin, flame retardant, if necessary, bubble regulator and other additives are supplied to an extruder, heated and kneaded, and a foaming agent is press-fitted into the extruder and kneaded. The foamable polystyrene resin melt obtained in this way is extruded through a flat die into a low-pressure region from the inside of a high-pressure extruder and foamed, and a mold placed at the outlet of the die (parallel or gently from the inlet toward the outlet). Polystyrene resin by passing through a molding tool such as a sheet made of two or more upper and lower polytetrafluoroethylene resins (hereinafter also referred to as guiders) and molding rolls installed so as to expand to Examples thereof include a method for producing an extruded foam (hereinafter also simply referred to as an extruded foam). In the production method of the present invention, a conventionally known method for producing an extruded foam can be used as a basic production method other than using a specific flame retardant described later.

  Examples of the polystyrene resin supplied to the extruder in the present invention include a styrene homopolymer, a styrene-acrylic acid copolymer containing styrene as a main component, a styrene-methyl acrylate copolymer, and a styrene-ethyl acrylate copolymer. Polymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-maleic anhydride copolymer, styrene-polyphenylene ether copolymer, styrene-butadiene copolymer Polymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-methylstyrene copolymer, styrene-dimethylstyrene copolymer, styrene-ethylstyrene copolymer, styrene-diethylstyrene copolymer Etc. The styrene unit component content in the styrenic copolymer is preferably 50 mol% or more, particularly preferably 80 mol% or more.

  As said polystyrene-type resin, what mixed the other polymer may be used in the range in which the objective of this invention, an effect | action, and an effect are achieved. Other polymers include polyethylene resins (ethylene homopolymers and one or a mixture of two or more selected from the group of ethylene copolymers having an ethylene unit component content of 50 mol% or more), polypropylene-based resins Resin (one or a mixture of two or more selected from the group of propylene homopolymer and propylene copolymer having a propylene unit component content of 50 mol% or more), polyphenylene ether resin, styrene-butadiene-styrene block copolymer Polymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer hydrogenated product, styrene-isoprene-styrene block copolymer hydrogenated product, styrene-ethylene copolymer, and the like. These other polymers will be less than 50% by weight in the polystyrene resin. The, preferably such that 30 wt% or less, more preferably such that 10 wt% or less, can be mixed according to the purpose.

  In this invention, it is preferable from the viewpoint described in background art to use the mixed foaming agent containing C3-C5 saturated hydrocarbon (A) and the other foaming agent (B) shown below.

Examples of the saturated hydrocarbon having 3 to 5 carbon atoms (A) include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and the like.
Said saturated hydrocarbon (A) can be used individually or in mixture of 2 or more types.
Among the saturated hydrocarbons (A), propane, n-butane, i-butane or a mixture thereof is preferable from the viewpoint of foamability. Moreover, n-butane, i-butane or a mixture thereof is preferable from the viewpoint of the heat insulating performance of the foam, and i-butane is particularly preferable.

As another foaming agent (B), an organic physical foaming agent and an inorganic physical foaming agent can be used.
Examples of the organic physical foaming agent include ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i -Alcohols such as butyl alcohol and t-butyl alcohol, formic acid esters such as methyl formate, ethyl formate, propyl formate and butyl formate, and alkyl chlorides such as methyl chloride and ethyl chloride. In addition, trans-1,3,3,3-tetrafluoropropene, cis-1,3,3,3-tetrafluoropropene, 1,1,1,2 having a low ozone depletion coefficient and a low global warming potential Fluorinated hydrocarbons such as tetrafluoropropene can also be used.
Examples of the inorganic physical foaming agent include water and carbon dioxide.
Said other foaming agent (B) can be used individually or in mixture of 2 or more types.

  Among the other foaming agents (B), methyl chloride, ethyl chloride, dimethyl ether, diethyl ether, methyl ethyl ether, methanol, ethanol, water, and carbon dioxide are preferable from the viewpoint of foamability and foam moldability. .

  In the mixed foaming agent, the blending ratio of the saturated hydrocarbon (A) is 10 to 80 mol%, and the blending ratio of the other foaming agent (B) is 90 to 20 mol% [provided that the foaming agent (A) and The total amount with the foaming agent (B) is preferably 100 mol%]. By using a mixed foaming agent having a blending ratio within this range, an extruded foam having a high expansion ratio can be produced safely and stably, and at the same time, an extruded foam excellent in heat insulation and flame retardancy. Is preferable in manufacturing. From this point of view, saturated hydrocarbon (A) 30-70 mol% and other blowing agent (B) 70-30 mol% [however, the total amount of blowing agent (A) and blowing agent (B) is 100 mol% And a mixed foaming agent containing

  The amount of the foaming agent injected 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 polystyrene resin. When there is too little addition amount of a foaming agent, the density of the extrusion foam obtained will become high and it will become difficult to exhibit the characteristics, such as a lightweight and heat insulation as a foam. When there is too much addition amount of a foaming agent, there exists a possibility that defects, such as a void, may arise easily in an extrusion foam.

The flame retardant used in the present invention is
(1) an organic compound having a 2,3-dibromo-2-methylpropyl group (hereinafter also simply referred to as a flame retardant (1));
(2) an organic compound having a 2,3-dibromopropyl group (hereinafter also simply referred to as a flame retardant (2));
(3) A brominated epoxy resin (hereinafter also simply referred to as a flame retardant (3)).

The mixture of flame retardants (1) to (3) in the present invention is excellent in flame retardancy and thermal stability. If the flame retardant (1) is not blended in the mixture, the flame retardancy is lowered, and for example, there is a possibility that the flammability standard described in JIS A 9511 (1995) cannot be satisfied.
Further, if the flame retardant (2) is not blended, the thermal stability of the composite flame retardant is lowered, and the flame retardant effect of the extruded foam obtained by extrusion foaming may be less than expected, or the extrusion obtained There exists a possibility that the physical property of a foam may fall.
Further, if the flame retardant (3) is not blended, the thermal stability of the composite flame retardant will be insufficiently strengthened. When the flame retardant (2) is not blended, there is a possibility that a problem may occur, and when the recovered material of the obtained extruded foam is heated and melted to obtain a recycled material, the molecular weight of the obtained recycled material is There is a risk that the material properties will decrease too much and the problem of yellowing of the recycled material will occur.

  Examples of the organic compound having the (1) 2,3-dibromo-2-methylpropyl group include tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S—. And bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether), and the like, preferably tetrabromobisphenol-A-bis ( 2,3-dibromopropyl ether).

  Examples of the organic compound (2) having a 2,3-dibromopropyl group include tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), tetrabromobisphenol-S-bis (2,3-dibromo). Propyl ether), tetrabromobisphenol-F-bis (2,3-dibromopropyl ether), tris (2,3-dibromopropyl) isocyanurate and tris (2,3-dibromopropyl) cyanurate, And tetrabromobisphenol-A-bis (2,3-dibromopropyl ether).

  Examples of the brominated epoxy resin (3) include brominated epoxy resins mainly composed of brominated bisphenol A such as tetrabromobisphenol A and having an average molecular weight of 500 to 25000 and a bromine content of 45 to 65% by weight. preferable. Further, a brominated epoxy resin having a softening temperature of 200 ° C. or lower is preferable. Specific examples include flame retardants of the trade name SR-T series manufactured by Sakamoto Pharmaceutical Co., Ltd. and the trade name EPICLON series manufactured by DIC.

In this invention, the compounding quantity of the said flame retardant (1) is 0.5-4.5 weight part with respect to 100 weight part of said polystyrene-type resin, Preferably it is 1.0-4.0 weight part. is there. If the blending amount is too small, the flame retardancy decreases, and if it is too large, the thermal stability may decrease.
Moreover, the compounding quantity of the said flame retardant (2) is 0.5-4.5 weight part with respect to 100 weight part of said polystyrene-type resin, Preferably it is 1.0-4.0 weight part. If the blending amount is too small, the thermal stability is lowered, and if it is too large, the flame retardancy of the composite flame retardant may be relatively insufficient.
In addition, the blending ratio of the flame retardant (1) and the flame retardant (2) is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, based on weight. More preferably, it is 30/70 to 70/30. When the blending ratio is within the above range, a good balance between thermal stability and flame retardancy is achieved.

  The blending amount of the flame retardant (3) is 0.05 to 1 part by weight, preferably 0.1 to 0.5 part by weight, and more preferably 0.3 to 100 parts by weight of the polystyrene resin. -0.5 parts by weight. If the blending amount is too small, the desired effect of improving thermal stability will not be exhibited, and if it is too large, the flame retardancy of the composite flame retardant may be relatively insufficient.

  The total amount of the flame retardants (1) to (3) is preferably 0.5 to 10.0 parts by weight, more preferably 0.75 to 7 parts by weight with respect to 100 parts by weight of the polystyrene resin. 0.5 parts by weight, and more preferably 1.0 to 6.0 parts by weight. If the amount is too small, sufficient flame retardancy may not be exhibited. On the other hand, if the amount is too large, there is a risk of adverse effects in the extrusion foam molding of the styrene resin.

  In the present invention, a halogen-based flame retardant different from any of the flame retardants (1), (2) and (3) can be further blended. Examples of the flame retardant include halogenated aliphatic compounds such as tetrabromocyclooctane, hexabromobenzene, pentabromotoluene, ethylenebispentabromodiphenyl, decabromodiphenyl oxide, 2,3-dibromopropylpentabromophenyl oxide, polybromo Halogenated aromatic compounds or derivatives thereof such as phenylindane, polypentabromobenzyl acrylate, brominated styrene-butadiene-styrene, brominated polyphenylene oxide, brominated polystyrene, tetrabromobisphenol A, tetrabromobisphenol A bis (2-bromoethyl) ) Halogenated bisphenol A such as ether, tetrabromobisphenol A diallyl ether and derivatives thereof, tetrabromobisphenol S, tetrabromide Halogenated bisphenol Ss such as bisphenol S (2-bromoethyl) ether and derivatives thereof, tetrabromobisphenol A polycarbonate oligomers, halogenated bisphenol derivatives oligomers such as tetrabromobisphenol epoxy oligomers, ethylene bis (tetrabromophthal) imide, tris Halogen and nitrogen atom-containing compounds such as (tribromophenoxy) triazine and tris (2,3-dibromopropyl) isocyanurate, halogen-containing phosphorus compounds such as tris (tribromoneopentyl) phosphate and tris (bromophenyl) phosphate, etc. Other halogen flame retardants can be mentioned.

  In addition, in this invention, in the range which does not impair the effect of this invention, it can use together with another flame retardant as needed. Other flame retardants include diphenylalkanes such as 2,3-dimethyl-2,3-diphenylbutane, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, isocyanuric acid, triallyl isocyanurate, Examples include nitrogen-containing cyclic compounds such as melamine cyanurate, melamine, melam, and melem, silicone compounds, inorganic compounds such as boron oxide, zinc borate, and zinc sulfide, and phosphorus compounds such as red phosphorus, ammonium polyphosphate, and phosphazene. It is done.

  In the present invention, it is preferable to blend one or more stabilizers selected from a hindered phenol stabilizer, a phosphorus stabilizer, and a hindered amine stabilizer together with the flame retardant. The stabilizer can suppress the molecular weight reduction and coloring of the polystyrene resin by capturing halogen radicals and halogen ions generated by decomposition of the brominated flame retardant during processing.

Examples of the hindered phenol stabilizer include 2,6-di-t-butyl-p-cresol, triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate. ], Tetrakis- [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 2,2-methylenebis (4-methyl-6-tert-butylphenol), 1,6- Hexanediol-bis [3- (3,5-di-tert-butyl-4-droxyphenyl) propionate].
You may use these individually or in combination of 2 or more types. Among these, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] is preferable from the viewpoint of extrusion stability and flame retardancy.

  Examples of the phosphorus stabilizer include tris (2,4-di-t-butylphenyl) phosphate, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphate, Bis (2,4-di-t-butylphenyl) pentaerythritol diphosphate, tetra (tridecyl) -4,4′-butylidene-bis (2-t-butyl-5-methylphenyl) diphosphate, bis [ 2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphorous acid, tetrakis (2,4, -di-t-butylphenyl) [1,1-biphenyl] -4,4 '-Diylbisphosphonite, bis (nonylphenyl) pentaerythritol diphosphate, bisstearyl pentaerythritol diphosphate 2,2′-methylenebis (4,6-di-t-butyl-1-phenyloxy) (2-ethylhexyloxy) phosphorus, mono (dinonylphenyl) mono-p-nonylphenyl phosphate, tris (monononylphenyl) ) Phosphate, tetraalkyl (C = 12-16) -4,4′-isopropylidene- (bisphenyl) diphosphate, hexatridecyl-1,1,3-tris (3-t-butyl-6- Methyl-4oxyphenyl) -3-methylpropane triphosphate, diphenylisodecyl phosphate, trisdecyl phosphate and the like. You may use these individually or in combination of 2 or more types. Among these, from the viewpoint of extrusion stability, tris (2,4-di-t-butylphenyl) phosphate or bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphos is used. Fate is preferred.

  Examples of the hindered amine compound include 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, or 4-hydroxy-1- Octyloxy-2,2,6,6-tetramethylpyridine aliphatic or aromatic carboxylic acid ester, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) -2- (3,5 -Di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, tetrakis (2,2,6,6-tetramethyl- -Piperidinyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6-paytamethyl-4-piperidinyl) -1,2,3,4-butanetetracarboxylate, etc. can give. You may use these individually or in combination of 2 or more types. Of these, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2-1,2 are effective in accelerating extinction with respect to flame retardancy and do not reduce the heat resistance of the extruded foam. 2,6,6-Pentamethylpiperidine, or aliphatic or aromatic carboxylic acid esters of 4-hydroxy-1-octyloxy-2,2,6,6-tetramethylpyridine.

  The total blending amount of the stabilizer is preferably in the range of about 0.2 to 20 parts by weight, more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the polystyrene resin.

  When using a phosphorus stabilizer and a hindered phenol stabilizer or a phosphorus stabilizer and a hindered amine stabilizer in combination, the weight ratio of the phosphorus stabilizer to the hindered phenol stabilizer or the hindered amine stabilizer. Is preferably 1: 0.6 to 1: 1.7.

  In addition, in this invention, stabilizers, such as a metal soap, an organic tin compound, a lead compound, a hydrotalcite, a polyhydric alcohol, (beta) -ketone, a sulfur type compound other than the said stabilizer, can be added.

  In the production method of the present invention, in addition to the flame retardant, a foam adjusting agent can be added to the foamable molten resin composition in order to adjust the average cell diameter of the extruded foam. Examples of the air conditioner include inorganic substances such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, aluminum oxide, bentonite, and diatomaceous earth. Further, in the present invention, two or more kinds of the air bubble adjusting agents can be used in combination. Among the various bubble regulators, talc is preferably used because it is easy to adjust the bubble diameter of the foamed plate obtained and to easily reduce the bubble diameter. Talc having a 50% particle size (permeation centrifugal sedimentation method) of 0.5 to 75 μm is preferred.

  The amount of the air bubble regulator added is preferably 0.01 to 7.5 parts by weight and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the polystyrene resin.

  In the production method of the present invention, in addition to the above-mentioned bubble regulator and flame retardant, a heat insulation improver such as graphite, hydrotalcite, carbon black and aluminum, and a colorant, as long as the object and effect of the present invention are not hindered. Various additives such as antioxidants, fillers and lubricants can be appropriately added. In addition, the addition method similar to the addition method of the said flame retardant can be employ | adopted as the addition method in an extrusion foaming process of various additives, such as the said bubble regulator and a coloring agent.

The density of the extruded foam obtained by the present invention is preferably 20 to 60 kg / m ³ , more preferably 22 to 50 kg / m ³ from the viewpoint of excellent heat insulation and mechanical strength, and the thickness is 5 to 150 mm. Furthermore, it is preferable that it is 15-100 mm.

  In the present invention, the recycled polystyrene resin composition obtained by heating and melting the extruded foam is heated and kneaded in an extruder together with the virgin raw material polystyrene resin and a flame retardant, and the foaming agent is further extruded. An extruded foam can be produced by extruding and foaming a foamable molten resin composition obtained by press-fitting into a machine and kneading. The extruded foam of the present invention is produced using the flame retardants (1) to (3), and is excellent in thermal stability. Therefore, its recycled raw material (recycled polystyrene resin composition) The product) has a low molecular weight reduction and yellowing at the time of recovery. Therefore, the extruded foam can be produced at low cost by using the recovered raw material.

  The polystyrene resin extruded foam obtained by the present invention is excellent in flame retardancy and mechanical properties by containing a specific amount of the specific flame retardant, and is mainly used as a heat insulating plate for building materials. It is preferable that the flammability standard for the extruded polystyrene foam heat insulating plate described in JIS A9511 (1995) is satisfied. That is, when the flammability was measured according to 4.13.1 “Measurement Method A” described in JIS A9511 (1995), the flame disappeared within 3 seconds, there was no residue, and the combustion limit support line was It is preferable that it does not burn over. Such an extruded foam has the safety required as an extruded polystyrene foam heat insulating plate for building materials because the possibility of fire spreading is small even when ignited.

  Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.

[Extruding equipment]
In Examples and Comparative Examples, a first extruder having an inner diameter of 65 mm and a second extruder having an inner diameter of 90 mm are connected in series, and a blowing agent injection port is provided near the end of the first extruder, A flat die having a resin discharge port (die lip) with a rectangular surface is connected to the outlet of the second extruder, and a pair of upper and lower polytetrafluoros installed so as to be parallel to the resin outlet of the second extruder. The apparatus provided with the shaping apparatus (guider) comprised with the board which consists of ethylene resin was used.

[Polystyrene resin]
(1) PS1: Styrene homopolymer, PS Japan “GX154 (200 ° C., 5 kgf), 1.5 g / 10 min.” 50 wt% and PS Japan “679 (MFR (200 ° C., 5 kgf) 18 g / 10 minutes) ”50% by weight of mixed resin (2) Recycled polystyrene resin: Recovered raw material of extruded foam obtained in Example 1 (MFR (200 ° C.) containing flame retardants (1) to (3) 5kgf) 15g / 10min)

[Flame retardants]
(1) Flame retardant (1): Tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), manufactured by Daiichi Kogyo Seiyaku, trade name “Pyroguard SR130”
(2) Flame retardant (2): Tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “Pyroguard SR720”
(3) Flame retardant (3): Brominated bisphenol A type epoxy compound (refers to a value determined at a softening point of 160 ° C. (ring ball method / ° C.)), average molecular weight 4000, bromine content 52%), Sakamoto Product name "SR-T2000" manufactured by Yakuhin Kogyo

[Stabilizer]
(1) Phosphorus stabilizer: bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, manufactured by ADEKA, trade name “PEP36”
(2) Hindered amine stabilizer: Tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, manufactured by ADEKA, trade name “ADK STAB LA57”

  Talc masterbatch: Masterbatch containing 60% by weight of talc (Matsumura Sangyo, high filler # 12)

Examples 1-3, Comparative Examples 1-3
A polystyrene resin, a flame retardant, and a talc master batch (talc MB) are supplied to the first extruder so as to have the blending amounts shown in Table 1, heated to 220 ° C., and melted and kneaded. The required amount of the foaming agent having the composition shown in the table is supplied to the melt from the foaming agent inlet provided near the tip of the extruder, and the foamable molten resin composition melt-kneaded is supplied to the subsequent second extruder. The resin temperature was adjusted to a foamed resin temperature as shown in Table 1 (this foaming temperature is the temperature of the foamable molten resin composition measured at the position of the joint between the extruder and the die), and then discharged. Extruded into the guider from the die lip at a rate of 70 kg / hour and passed through a guider arranged in parallel with a gap of 50 mm in the thickness direction of the extruded foam while foaming (molding). Polystyrene tree It was produced extruded foam.

  Table 3 shows the density, closed cell ratio, flame retardancy, thermal stability, foaming agent residual amount, and thermal conductivity of the obtained extruded foam.

Examples 4-6, Comparative Examples 4-6
A polystyrene resin extruded foam was produced in the same manner as in Example 1 except that the recycled polystyrene resin was blended so as to have the blending amounts shown in Table 2.

  Table 4 shows the density, closed cell rate, flame retardancy, thermal stability, residual amount of foaming agent, and thermal conductivity of the obtained extruded foam.

The measurement methods and evaluation methods for various physical properties of the extruded foams shown in Tables 3 and 4 are as follows.
[density]
It is an apparent density measured based on JIS K7222 (1985).

[Closed cell ratio]
It is the value measured by the procedure C of ASTM-D2856-70 using a cut sample without a molded skin cut to a size of 25 mm × 25 mm × 20 mm from the extruded foam.

[Remaining foaming agent]
The residual amount of foaming agent in the extruded foam was measured using a gas chromatograph. Specifically, a test piece having no molded skin of 200 mm × 200 mm × 10 mm cut out from the extruded foam immediately after production of the extruded foam was stored in an atmosphere of 23 ° C. and 50% humidity. 15 days after production (corresponding to 375 days after the 50 mm-thick extruded foam), the width of the test piece was 2.5 cm, and the sample was cut into a length such that the weight of the sample was 1 g. This sample was placed in a sample bottle with a lid containing toluene containing cyclopentane as an internal standard substance, and the lid was closed. Then, the sample was thoroughly stirred and a solution in which the blowing agent in the extruded foam was dissolved in toluene was used for measurement. As a sample, gas chromatographic analysis was performed to determine the remaining amount.

[Flame retardance]
The extruded foam immediately after production was transferred to a room with an air temperature of 23 ° C. and a relative humidity of 50%, left in that room for 4 weeks, and then measured according to JIS A9511 (1995) 4.13.1 “Measurement Method A”. . In addition, the measurement cut out five test pieces from one foamed board (N = 5), and evaluated it with the following evaluation criteria.
A: All specimens disappeared within 3 seconds, and the average burning time of 5 specimens is within 2 seconds.
○: All specimens disappear within 3 seconds, and the average burning time of 5 specimens exceeds 2 seconds and is within 3 seconds.
X: The average burning time of 5 test pieces exceeds 3 seconds.

[Yellowness]
Extruded foams obtained in Examples and Comparative Examples were regenerated and attached to the regenerated raw materials obtained and evaluated visually according to the following criteria.
◎: Transparent, ○: Slightly yellowish △: Yellow or brown

[Weight average molecular weight]
The molecular weight of the foam obtained in each example was melted and repelleted by a recycle extruder and measured under the measurement conditions of gas chromatographic analysis shown below.
Column: Shinwa Kogyo Co., Ltd. carrier: chromosorb W, 60-80 mesh, AW-DMCS treated liquid phase: Silicone DC550 (liquid phase amount 20%)
Column dimensions: Column length 4.1m, column inner diameter 3.2mm
Column material: Glass column temperature: 40 ° C
Inlet temperature: 200 ° C
Carrier gas: nitrogen carrier gas speed: 50 ml / min.
Detector: FID
Detector temperature: 200 ° C
Quantification: Internal standard method

  The weight average molecular weight is a value obtained by dissolving 10 mg of a styrene resin in 10 mL of THF (tetrahydrofuran), measuring by a GPC (gel permeation chromatography) method, and calibrating with standard polystyrene. The above GPC analysis was performed using equipment: Tosoh Corporation, SC-8020 type, column: Showa Denko Co., Ltd., Shodex AC-80M connected in series, column temperature: 40 ° C., flow rate: 1.0 ml. / Min. Detector: Tosoh Co., Ltd., UV-visible light detector UV-8020 type can be used for measurement.

[Evaluation of thermal stability]
The following criteria were evaluated based on the yellowing degree and the weight average molecular weight.
A: Yellowing degree is A and the weight average molecular weight exceeds Comparative Example 1. B: Yellowing degree is B and the weight average molecular weight exceeds Comparative Example 1. X: Yellowing degree is Δ. And / or a weight average molecular weight of Comparative Example 1 or less

[Thermal conductivity]
The extruded foam immediately after production was transferred to a room with an air temperature of 23 ° C. and a relative humidity of 50% and left in that room for 4 weeks, and then a test piece was cut out from the extruded foam to a length of 20 cm, a width of 20 cm, and an extruded foam thickness. According to the description of JIS A 9511 (1995) 4.7, a plate heat flowmeter method described in JIS A 1412 (1994) using a thermal conductivity measuring device “Auto Λ HC-73 type” manufactured by Eihiro Seiki Co., Ltd. ( Measurement was performed based on a two-heat flow meter system, a hot plate temperature high temperature side of 35 ° C., a hot plate temperature low temperature side of 5 ° C., and an average temperature of 20 ° C.

From the comparison of the thermal stability of Example 2 and Comparative Example 2 and the thermal stability of Example 5 and Comparative Example 5, if the brominated epoxy resin of flame retardant (3) is not added, the recycled raw material is yellow. Since it changes and molecular weight falls, it turns out that the reproduction | regeneration raw material of the extrusion foam to which the flame retardant (3) is not added has low practicality.
From the comparison of the flame retardancy of Example 3 and Comparative Example 3 and the comparison of the flame retardancy of Example 6 and Comparative Example 6, the organic compound having a 2,3-dibromopropyl group of the flame retardant (2) and the flame retardant ( In addition to the brominated epoxy resin of 3), if the organic compound having 2,3-dibromo-2-methylpropyl group of flame retardant (1) is not added, even if the blending amount as a whole flame retardant is the same, It can be seen that the flame retardancy decreases.
From the comparison of the thermal stability of Example 1 and Comparative Example 1, and the comparison of the thermal stability of Example 4 and Comparative Example 4, the organic compound having a 2,3-dibromo-2-methylpropyl group of the flame retardant (1) It can be seen that if the organic compound having a 2,3-dibromopropyl group of the flame retardant (2) is not blended in addition to the brominated epoxy resin of the flame retardant (3), the thermal stability is lowered.

Claims (5)

In a method for producing an extruded foam in which a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant and a foaming agent is extruded and foamed,
The flame retardant comprises (1) an organic compound having a 2,3-dibromo-2-methylpropyl group, (2) an organic compound having a 2,3-dibromopropyl group, and (3) a brominated epoxy resin,
(1) 0.5 to 4.5 parts by weight of an organic compound having 2,3-dibromo-2-methylpropyl group, and (2) 2,3-dibromopropyl group, relative to 100 parts by weight of the polystyrene resin The manufacturing method of the polystyrene-type resin extrusion foam characterized by mix | blending the organic compound which has 0.05-4.5 weight part, and (3) brominated epoxy resin in the ratio of 0.05-1 weight part.
The one or more thermal stabilizer selected from a hindered phenol stabilizer, a phosphorus stabilizer, and a hindered amine stabilizer is blended with the polystyrene resin together with the flame retardant. The manufacturing method of the polystyrene-type resin extrusion foam of description.
A halogen-based flame retardant different from any of (1) an organic compound having a 2,3-dibromo-2-methylpropyl group, (2) an organic compound having a 2,3-dibromopropyl group, and (3) a brominated epoxy resin The method for producing an extruded foam of polystyrene-based resin according to claim 1 or 2, further comprising:
The blowing agent comprises (A) 10 to 80 mol% of a saturated hydrocarbon having 3 to 5 carbon atoms, and (B) methyl chloride, ethyl chloride, dimethyl ether, diethyl ether, methyl ethyl ether, methanol, ethanol, water, and dioxide. One or two or more types of foaming agents selected from carbon are 90 to 20 mol% (however, the total amount of the foaming agent (A) and the foaming agent (B) is 100 mol%). The manufacturing method of the polystyrene-type resin extrusion foam in any one of Claims 1-3 to do.
The polystyrene resin includes (1) an organic compound having a 2,3-dibromo-2-methylpropyl group, (2) an organic compound having a 2,3-dibromopropyl group, and (3) a brominated epoxy resin. The method for producing a polystyrene resin extruded foam according to claim 1, comprising a recycled polystyrene resin composition obtained by heating and melting a polystyrene resin extruded foam.