JP2016079372A - Polystyrene resin foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polystyrene resin foam that still retains a high degree of flame retardancy and a sufficient oxygen index even when reducing a blending amount of a brominated butadiene polymer and reduces the occurrence of black specks and the degree of yellow discoloration in a recycled raw material pellet.SOLUTION: In the polystyrene resin foam, a composite flame retardant of (A) a brominated butadiene-styrene copolymer, (B) a tetrabromobisphenol A-bis(2,3-dibromopropyl ether) and (C) a tris(2,3-dibromopropyl)isocyanurate is blended in a specific amount.SELECTED DRAWING: None

Description

  The present invention relates to a polystyrene resin foam, and more specifically, is a polystyrene resin foam having excellent flame retardancy and high heat insulating properties and excellent recyclability, such as a building wall, floor, roof, etc. The present invention relates to a polystyrene-based resin foam which is suitably used for a heat insulating material, a tatami core material, and the like and is mainly formed in a plate shape.

  Conventionally, as a plate-like polystyrene resin foam, an air conditioner is added to a polystyrene resin material, heated and melt-kneaded with an extruder, and then a physical foaming agent is press-fitted into the extruder and further kneaded. A high-thickness polystyrene resin foam produced by extruding the mixture from a high-pressure region to a low-pressure region (usually in the atmosphere) and forming it into a plate shape by a shaping device connected to the die outlet of the extruder ( Hereinafter, it is also referred to as a foam.).

In order to use this 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 material described in JIS A9521: 2014. Therefore, a flame retardant is added to the 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, development of a flame retardant substitute foam manufacturing technology that does not use an HBCD flame retardant has been carried out due to the movement of the HBCD Chemical Examination Law and REACH regulations.

  On the other hand, chlorofluorocarbons (hereinafter referred to as CFC) such as dichlorodifluoromethane have been widely used as foaming agents used in the method for producing the plate-like foam. However, CFC has been refrained from being used because it is suspected to be related to the problem of ozone hole expansion, and instead of CFC, hydrogen atom-containing chlorofluorocarbon (hereinafter referred to as HCFC) having a small ozone destruction coefficient. ) And a hydrogen atom-containing fluorinated hydrocarbon (hereinafter referred to as HFC) having an ozone depletion coefficient of 0 (zero). Further, 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 give sufficient flame retardancy to polystyrene resin foam, it is more than in the case of producing using a nonflammable foaming agent such as HFC. It was necessary to add a flame retardant. As a result, the problem that the stability of extrusion foaming was remarkably impaired by the flame retardant added in a large amount and the physical properties of the obtained foam were newly generated.

In the above situation, studies have been made to impart high flame retardancy to polystyrene resin foams using a flame retardant other than HBCD.
For example, Patent Document 1 discloses the use of halides of halogenated aromatic alkyl aryl ethers such as tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) as flame retardants. ing.
However, although tetrabromobisphenol A- (2,3-dibromo-2-methylpropyl ether) can impart high flame retardancy to the foam, polystyrene resin is used in the process of recovering the foam and repelletizing it. When this recovered raw material is used as a part of the product, it may be easily decomposed, and there may be a problem that the pressure necessary for foaming cannot be maintained or the extrusion conditions are not stable.

Patent Document 2 discloses the use of brominated isocyanurate, brominated bisphenol, diphenylalkane and / or diphenylalkene.
However, brominated isocyanurate and tetrabromobisphenol A- (2,3-dibromopropyl ether) are foamed with polystyrene resin compared to HBCD or tetrabromobisphenol A- (2,3-dibromo-2-methylpropyl ether). Since the effect of imparting flame retardancy to the body is inferior, it is necessary to add a flame retardant aid such as diphenylalkane after increasing the amount added.

  Patent Documents 3 and 4 disclose polystyrene resin foams in which a brominated butadiene polymer type flame retardant such as a brominated butadiene-styrene copolymer is blended. This flame retardant has an advantage of high flame retardancy imparting effect.

JP 2005-139356 A JP 2003-292664 A Special table 2009-516019 Special table 2012-512942 gazette

However, in the case of the foams described in Patent Documents 3 and 4, if a large amount of saturated hydrocarbon such as butane is left in order to improve the heat insulating property, the high degree of clearing the flammability standard of JIS A9521: 2014 In order to impart such flame retardancy, the amount of the brominated butadiene-styrene copolymer added must be at least 3 parts by weight or more based on the base polystyrene resin.
Furthermore, if this brominated butadiene-styrene copolymer is added in a large amount, black spots are generated during extrusion foaming, black spots are generated in the recycled raw material pellets during recycling, and yellowing occurs. It was difficult to make a reusable foam as a raw material. However, problems such as the generation of black spots and yellow discoloration due to the addition of a large amount of this brominated butadiene-styrene copolymer can be reduced by making the addition amount small. However, in this case, it becomes difficult to obtain a foam having high flame retardancy and high oxygen index that satisfies the flammability standards of JIS A9521: 2014.

That is, the brominated butadiene-styrene copolymer has recently attracted attention as an alternative flame retardant for HBCD, but has the following problems.
(A) If a brominated butadiene-styrene copolymer is added in a large amount, it is possible to obtain a polystyrene resin foam that satisfies the flammability standard of JIS A9521. However, if it is added in a large amount, black spots and yellow discoloration are likely to occur during extrusion foaming, making it difficult to obtain a foam having an excellent appearance.
(B) When a foam containing a large amount of brominated butadiene-styrene copolymer or a milled end material is melted and re-pelletized, black spots and yellowing are likely to occur. Difficult to get. If the temperature at the time of re-pellet is lowered, it is possible to prevent the occurrence of black spots and yellow discoloration, but the productivity of re-pellet will be reduced.
(C) If the addition amount of brominated butadiene-styrene copolymer is made small, generation of black spots and yellowing can be suppressed, but a foam having high flame retardancy cannot be obtained.

  In view of the above problems, the present invention uses a brominated butadiene-styrene copolymer as a flame retardant, has high flame retardancy and a sufficient oxygen index, and hardly causes black spots and yellowing of the foam. , A polystyrene resin foam that can be reused as a raw material for the production of foams. Even if re-pelleting is performed under high-temperature recovery conditions, black spots and yellowing of foams are unlikely to occur, and recovery is highly efficient. An object of the present invention is to provide a polystyrene resin foam capable of producing raw materials.

According to the present invention, the following polystyrene resin foam is provided.
[1] In a polystyrene resin foam containing a flame retardant, the flame retardant comprises (A) a brominated butadiene-styrene copolymer and (B) tetrabromobisphenol A-bis (2,3-dibromopropyl ether). ) And (C) tris (2,3-dibromopropyl) isocyanurate, and the blending ratio of (A) brominated butadiene-styrene copolymer in the composite flame retardant is 20 to 90 wt. (However, the sum of (A), (B) and (C) is 100% by weight.) (B) Tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and (C ) Polystyrene-based resin foam, wherein the blending weight ratio with tris (2,3-dibromopropyl) isocyanurate is 10:90 to 90:10.
[2] The foam further contains poly-1,4-diisopropylbenzene, and the amount of poly-1,4-diisopropylbenzene is 1 to 20 parts by weight with respect to 100 parts by weight of the composite flame retardant. The polystyrene resin foam according to claim 1, wherein the foam is a polystyrene resin foam.
[3] The blending amount of (A) brominated butadiene-styrene copolymer is 0.2 parts by weight or more and less than 1 part by weight with respect to 100 parts by weight of polystyrene resin constituting the foam. Item 3. The polystyrene resin foam according to Item 1 or 2.

In addition to (A) brominated butadiene-styrene copolymer, (B) tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and (C ) Since a composite flame retardant containing a specific amount of tris (2,3-dibromopropyl) isocyanurate is used, it has excellent flame retardancy, and (A) the amount of brominated butadiene-styrene copolymer Even if there is little, it can be set as the foam which satisfies the combustibility specification of JISA9521: 2014 and has sufficient oxygen index. Further, since the foam and its recycled raw material pellets are those in which the generation of black spots and yellowing are suppressed, they can be reused in the production of foams in the same manner as when a conventional flame retardant is blended.

Hereinafter, the polystyrene resin foam of the present invention will be described in detail.
Examples of the polystyrene resin constituting the polystyrene resin foam include polystyrene, rubber-modified polystyrene (HIPS), styrene-acrylic acid copolymer containing styrene as a main component, styrene-methyl acrylate copolymer, styrene- Ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-maleic anhydride copolymer, styrene-polyphenylene ether copolymer, Styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-methylstyrene copolymer, styrene-dimethylstyrene copolymer, styrene-ethylstyrene copolymer, styrene-diethylstyrene copolymer, etc. 2 or more types Mixtures thereof. The styrene unit component content in the styrene copolymer is preferably 50 mol% or more, and particularly preferably 80 mol% or more. The polystyrene resin may contain a polyfunctional monomer unit component such as divinylbenzene or a hyperbranched macromonomer. Among these polystyrene resins, polystyrene is preferable from the viewpoint of foamability.

  The polystyrene resin may be a mixture of other polymers within the range in which the object and effect of the present invention are achieved. Examples of other polymers include polyester resins such as amorphous modified polyethylene terephthalate, polyethylene resins (an ethylene homopolymer and an ethylene copolymer having an ethylene unit component content of 50 mol% or more. Seeds, or a mixture of two or more), polypropylene resins (one or a mixture of two or more selected from the group of propylene homopolymers and propylene copolymers having a propylene unit component content of 50 mol% or more) , Polyphenylene ether resin, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer hydrogenated product, styrene-isoprene-styrene block copolymer hydrogenated product Styrene-ethylene copolymer, etc. The other polymer is mixed according to the purpose so that it is less than 50% by weight in the polystyrene resin, preferably 30% by weight or less, and more preferably 10% by weight or less. be able to.

Next, the flame retardant contained in the polystyrene resin foam of the present invention will be described.
The flame retardant includes (A) brominated butadiene-styrene copolymer (hereinafter also referred to as flame retardant (A)) and (B) tetrabromobisphenol A-bis (2,3-dibromopropyl ether) (hereinafter referred to as “flame retardant”). And flame retardant (B)) and (C) tris (2,3-dibromopropyl) isocyanurate (hereinafter also referred to as flame retardant (C)).

  By using a composite flame retardant in which the flame retardant (B) and the flame retardant (C) are combined with the flame retardant (A), the blending amount of the (A) brominated butadiene-styrene copolymer is small. In addition, a foam having flame retardancy equal to or higher than that of the flame retardant (A) alone and a sufficient oxygen index can be obtained. As a result, the occurrence of yellow discoloration and black spots in the foam and recycled raw material pellets is effectively suppressed, and a polystyrene resin foam that can be recycled as a raw material is obtained, which has a brominated butadiene-styrene copolymer flame retardant. The above problems are solved all at once. This finding has been found for the first time by the present inventors.

  The (A) brominated butadiene-styrene copolymer used in the present invention is a conventionally known one. For example, those disclosed in Patent Document 3 and Patent Document 4 can be used as they are.

When the brominated butadiene-styrene copolymer is used as a flame retardant for a polystyrene resin, considering the compatibility with the polystyrene resin, the brominated butadiene-styrene copolymer is a block containing a styrene monomer component unit. It is preferably a copolymer, a random copolymer or a graft copolymer, and more preferably a block copolymer of a polystyrene polymer block and a brominated polybutadiene block. The brominated butadiene-styrene copolymer is produced by brominating a butadiene-styrene copolymer.
Examples of the styrene monomer include styrene, brominated styrene, chlorinated styrene, 2-methyl styrene, 4-methyl styrene, 2,4-dimethyl styrene, α-methyl styrene and the like. Among these, Styrene, 4-methylstyrene, α-methylstyrene or a mixture thereof is preferable, and styrene is more preferable.

  From the viewpoint of imparting flame retardancy, the bromine content in the brominated butadiene-styrene copolymer is preferably 60% by weight or more, more preferably 63% by weight or more. The bromine content can be determined based on JIS K7392: 2009.

The weight average molecular weight of the brominated butadiene-styrene copolymer is preferably about 1.0 × 10 ^{5 to} 2.0 × 10 ^{5 in} terms of polystyrene, and its melt viscosity at 200 ° C. and a shear rate of 100 sec ⁻¹ is About 4000 to 8000 Pa · s.

  In general, a brominated butadiene-styrene block copolymer which is a typical brominated butadiene-styrene copolymer can be represented by the following general formula.

(In the formula, X, Y and Z are positive integers.)

  Examples of the brominated butadiene-styrene block copolymer preferably used in the present invention include commercially available products such as Emerald 3000 manufactured by Chemtura and FR122P manufactured by ICL.

(B) Tetrabromobisphenol A-bis (2,3-dibromopropyl ether) constituting the composite flame retardant used in the present invention alone is inferior in the effect of imparting flame retardancy to a polystyrene resin foam. However, the flame retardant of the foam can be remarkably improved by combining the flame retardant (B) with the flame retardant (A) and the flame retardant (C) described later.
In addition, when a flame retardant (B) is not mix | blended, there exists a possibility that a black spot may generate | occur | produce by having to increase the compounding quantity to the foam of a flame retardant (A). Moreover, when a flame retardant (B) is used for manufacture of a foam as a single flame retardant, although the obtained foam does not have a black spot or yellowing, it becomes inferior to a flame retardance.

(C) Tris (2,3-dibromopropyl) isocyanurate constituting the composite flame retardant has good compatibility with polystyrene resin, decomposition start temperature is 250 to 265 ° C., and melting point is 100 to 110 ° C. Therefore, the handling at the time of foam production is easy, and the possibility of decomposition at the time of kneading with the polystyrene resin is small. Although the flame retardant (C) alone is inferior in the effect of imparting flame retardancy to the polystyrene resin foam, it is used in combination with the flame retardant (A) and the flame retardant (B). The flame retardancy of the foam can be remarkably improved.
In addition, when a flame retardant (C) is not blended, sufficient flame retardancy cannot be obtained, or the blending amount of the flame retardant (A) must be increased to compensate for the lack of flame retardancy. May cause black spots. Further, when the flame retardant (C) is used as a single flame retardant in the production of a foam, the obtained foam does not exhibit black spots or yellowing, but does not exhibit sufficient flame retardancy. .

The blending ratio of the flame retardant (A) in the composite flame retardant is 20 to 90% by weight (however, the total of the flame retardant (A), the flame retardant (B), and the flame retardant (C) is 100% by weight. .)
When the blending ratio of the flame retardant (A) is within this range, a foam free from black spots or yellowing can be stably obtained by interaction with other flame retardants, and the obtained foam It is possible to impart a high degree of flame retardancy to the. If the blending ratio of the flame retardant (A) is too small, the desired flame retardancy may not be obtained. On the other hand, if the blending ratio is too large, the generation of black spots and the yellow discoloration of the resin may become severe.
From this viewpoint, the blending ratio of the flame retardant (A) is preferably 25 to 70% by weight, more preferably 30 to 50% by weight.

  In the present invention, when producing a foam or a recycled raw material, the generation of black spots is effectively suppressed, and the amount of black spots or yellowing is predicted from the blended amount of the flame retardant (A). The amount is reduced to the same extent as when using a conventional flame retardant such as HBCD. The reason why this effect is obtained is that the dispersibility of the brominated butadiene-styrene copolymer in the polystyrene resin by combining the flame retardant (A) with the flame retardant (B) and the flame retardant (C). May be improved.

  Furthermore, the weight ratio of the flame retardant (B) and the flame retardant (C) in the composite flame retardant needs to be 10:90 to 90:10. If the blending weight ratio of the flame retardant (B) is too small, black spots or yellowing may occur during extrusion foaming or recycling. If the blending weight ratio of the flame retardant (C) is too small, the flame retardant (C) is more excellent in flame retardancy than the flame retardant (B), so that the flame retardancy tends to decrease. From this viewpoint, the blending weight ratio of (B) :( C) is preferably 10:90 to 90:10, more preferably 20:80 to 70:30, and still more preferably 30:70 to 60:40.

  According to the present invention, as described above, conventionally, if the flame retardant (A) is not blended at least 3 parts by weight or more with respect to 100 parts by weight of the polystyrene resin, a high degree of flame retardancy can be imparted to the foam. In contrast, the amount of the flame retardant (A) can be reduced. Specifically, the amount is preferably less than 3 parts by weight, more preferably 2 parts by weight or less, still more preferably 1.5 parts by weight or less, and particularly preferably less than 1 part by weight. In addition, it is preferable that the minimum of the compounding quantity of a flame retardant (A) is 0.2 weight part with respect to 100 weight part of polystyrene resins, More preferably, it is 0.5 weight part.

  Further, the desired flame retardancy can be obtained even if the amount of the flame retardant (A) is small, and in addition to being able to suppress black spots and yellowing, a composite comprising the flame retardants (A), (B) and (C) The total amount of flame retardant can also be reduced. Specifically, the amount can be preferably 3.5 parts by weight or less, more preferably 3 parts by weight or less, and still more preferably 2.5 parts by weight or less with respect to 100 parts by weight of the polystyrene-based resin. In addition, it is preferable that the minimum of the total compounding quantity of this composite flame retardant is 1.5 weight part with respect to 100 weight part of polystyrene-type resin, More preferably, it is 2 weight part.

  The flame retardant used in the present invention may contain a flame retardant other than the composite flame retardant as long as the intended purpose is achieved. Examples of other flame retardants include brominated bisphenols typified by tetrabromobisphenol S-bis (2,3-dibromopropyl ether) and tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether). Compounds, mono (2,3,4-tribromobutyl) isocyanurate, brominated isocyanurate compounds represented by di (2,3,4-tribromobutyl) isocyanurate, brominated epoxy resins, brominated Polystyrene, triphenyl phosphate, pentabromotoluene, cresyl di-2,6-xylenyl phosphate, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, Melamine, melam, melem Nitrogen-containing cyclic compounds, silicone-based compounds, boron oxide, zinc borate, inorganic compounds such as zinc sulfide, red phosphorus-based, ammonium polyphosphate, phosphazene, phosphorus-based compounds such as hypophosphorous acid salts and the like. These compounds can be used alone or in admixture of two or more. The blending amount is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and more preferably 10 parts by weight or less with respect to the total of 100 parts by weight of the flame retardants (A), (B), and (C). More preferably.

  Since the flame retardant in this invention can improve the flame retardance of a foam, it is preferable to contain poly-1, 4- diisopropylbenzene as a flame retardant adjuvant (D). The blending amount of the flame retardant aid (D) is preferably 1 part by weight with respect to the total blending amount of 100 parts by weight of the flame retardants (A), (B) and (C). More preferably, it is 3 parts by weight, and the upper limit thereof is preferably 20 parts by weight, more preferably 15 parts by weight, still more preferably 10 parts by weight.

  In the present invention, by combining the flame retardants (A), (B), (C), it is possible to impart flame retardancy satisfying the flammability standard of JIS A9521 to the foam obtained, The oxygen index (LOI) can also be 26 or more. Moreover, generation | occurrence | production of the black point and yellowing color at the time of manufacture of a foam can be prevented, and generation | occurrence | production of the black point and yellowing color at the time of manufacture of a recycled pellet can also be suppressed. Further, by combining the flame retardants (A), (B), and (C) with the flame retardant aid (D), the resulting foam has higher flame resistance in the flammability standard of JIS A9521. The oxygen index (LOI) can be improved. Further, by combining the flame retardants (A), (B), and (C) with the flame retardant aid (D), the amount of the flame retardant (A) can be further reduced. Further, prevention of yellowing and suppression of black spots and yellowing during the production of recycled pellets can be made more effective.

In the present invention, it is preferable to add a heat stabilizer to the flame retardant in order to suppress decomposition of the composite flame retardant during extrusion.
Examples of the thermal stabilizer include one or more selected from an epoxy resin stabilizer, a phosphite stabilizer, a phenol stabilizer, and a hindered amine stabilizer.
The total amount of these heat stabilizers is preferably 1 to 35 parts by weight, more preferably 2 to 25 parts by weight with respect to 100 parts by weight of the composite flame retardant.

  The epoxy resin stabilizer is preferably a novolak type or a bisphenol type. As the bisphenol type epoxy compound, a brominated bisphenol A type epoxy compound is particularly preferable.

  Examples of the phosphite stabilizer include tris (2,4-di-t-butylphenyl) phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tetra (tridecyl) -4,4′-butylidene-bis (2-t-butyl-5-methylphenyl) diphosphite, bis [2,4 -Bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphorous acid, bis (nonylphenyl) pentaerythritol diphosphite, bisstearyl pentaerythritol diphosphite, mono (dinonylphenyl) mono-p -Nonylphenyl phosphite, Tris (monononylphenyl) phosphite, Tet Alkyl (C = 12-16) -4,4′-isopropylidene- (bisphenyl) diphosphite, hexatridecyl-1,1,3-tris (3-tert-butyl-6-methyl-4-oxyphenyl) Examples include -3-methylpropane triphosphite, diphenylisodecyl phosphite, and tridecyl phosphite. 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) phosphite or bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite is used. preferable.

Examples of the phenol-based 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], pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like Is mentioned.
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 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-tetramethylpiperidine 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-4 Piperidinyl) -1,2,3,4-butane tetracarboxylate and the like. You may use these individually or in combination of 2 or more types. Among these, tetrakis (2,2,6,6-tetramethyl-4-piperidinyl) -1,2,3, from the effect of accelerating extinction with respect to flame retardancy and the point of not reducing the heat resistance of the foam. 4-Butanetetracarboxylate or bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate is preferred.
Examples of other heat stabilizers other than those described above include metal soaps, organotin compounds, lead compounds, hydrotalcite, polyhydric alcohols, β-ketones, and sulfur compounds.

Next, various physical properties of the polystyrene resin foam of the present invention will be described.
Apparent density of the foam of the present invention, from the viewpoint of excellent thermal insulation and mechanical strength, preferably 20~60kg / ^{m 3,} more preferably from 22~50kg / ^{m 3.} Moreover, it is preferable that the thickness of this foam is 10-150 mm, More preferably, it is 20-100 mm. The width of the foam is preferably 600 mm to 1500 mm. Further, the average cell diameter in the thickness direction is preferably 1.0 mm or less, and more preferably 0.75 mm or less in order to obtain a foam having higher heat insulating properties. When the bubble diameter is too small, it is difficult to obtain a plate-like extruded foam having a large thickness and a low apparent density. From this viewpoint, the average cell diameter in the thickness direction is preferably 0.05 mm or more, more preferably 0.06 mm or more, and particularly preferably 0.07 mm or more.

  The measuring method of the average cell diameter in the thickness direction is as follows. First, the extruded foam is divided into three equal parts in the width direction, and a microscopic enlarged photograph of the widthwise vertical cross section (vertical cross section perpendicular to the extrusion direction of the extruded foam) of each divided measurement sample is obtained. . Next, on the enlarged photograph, a straight line is drawn over the entire thickness of the extruded foam along the thickness direction of the foam, and the number of bubbles crossing the straight line is counted. The length is not the length of the straight line on the enlarged photo, but the length of the straight line taking into account the magnification of the photo.) Dividing by the number of bubbles counted, the average of the bubbles present on each straight line The diameter Tn (the length of the straight line / the number of bubbles intersecting with the straight line) is determined, and the arithmetic average value of the three average diameters Tn thus determined is defined as the average bubble diameter T (mm) in the thickness direction. In addition, what is necessary is just to divide | segment and image | photograph several sheets, when the whole thickness of an extrusion foam does not fit in one microscope enlarged photograph.

Next, the manufacturing method of the polystyrene-type resin foam of this invention is demonstrated.
The foam of the present invention can be produced by various methods. The polystyrene resin and the composite flame retardant are heated and melted, and the foaming agent is press-fitted into the obtained molten resin composition and kneaded. A method of extrusion foaming the foamable molten resin composition obtained in this manner is preferably employed.

  Specifically, polystyrene resin, composite flame retardant, if necessary, flame retardant aid, heat stabilizer, bubble regulator and other additives are supplied to the extruder, heated and kneaded to obtain a molten resin composition Further, the foamable molten resin composition obtained by press-fitting a physical foaming agent into the extruder and kneading is extruded into a low pressure region (usually in the atmosphere) from the high pressure extruder through a flat die and foamed. And a molding die arranged at the outlet of the die [comprising a plate made of two or more upper and lower polytetrafluoroethylene resins or the like installed so as to be gently expanded from the inlet to the outlet (hereinafter, It is also referred to as a guider)]] and a method of producing a plate-like polystyrene resin foam by passing it through a forming tool such as a forming roll. These composite flame retardants, flame retardant aids, and heat stabilizers can be fed to the extruder as they are, or they can be extruded as a master batch containing a part or all of them, or as a molten mixture containing at least a flame retardant and a heat stabilizer. It can also be supplied to the machine.

  As the polystyrene-based resin supplied to the extruder, the polystyrene described as the polystyrene-based resin constituting the foam or the styrene-acrylic acid copolymer mainly containing styrene is used.

In order to increase the thermal stability, the composite flame retardant is preferably introduced into an extruder as a flame retardant melt mixture prepared by adding them together with a thermal stabilizer to an extruder or a mixer and melt-mixing them. .
The temperature at the time of melt kneading is preferably as low as the resin temperature at the time of melt mixing, in order to effectively suppress the liberation of bromine from the (A) brominated polybutadiene polymer, and is generally 190 ° C. or less, preferably 185 ° C. It is as follows.
Moreover, it is preferable that the flame retardant molten mixture is made into a pellet form by cutting it from the standpoint of meterability and ease of handling.

Although the said foaming agent is not specifically limited, It is preferable from a viewpoint of global warming prevention to use the composite foaming agent containing a C3-C5 saturated hydrocarbon and the other foaming agent shown below.
Examples of the saturated hydrocarbon having 3 to 5 carbon atoms include propane, n-butane, i-butane, n-pentane, i-pentane, cyclopentane, neopentane and the like. These saturated hydrocarbons can be used alone or in admixture of two or more. Among these saturated hydrocarbons, 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 other foaming agents, organic physical foaming agents other than the saturated hydrocarbons and inorganic physical foaming agents can be used.
Examples of organic physical foaming agents other than saturated hydrocarbons include ethers such as dimethyl ether, diethyl ether, ethyl methyl ether, di-n-butyl ether, diisopropyl ether, methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol Alcohols such as i-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. Moreover, trans-1,3,3,3-tetrafluoropropene, cis-1,3,3,3-tetrafluoropropene, 2,3,3,3 having a low ozone depletion coefficient and a low global warming potential -Fluorinated unsaturated hydrocarbons such as tetrafluoropropene and chlorofluorinated unsaturated hydrocarbons such as 1-chloro-3,3,3-trifluoropropene can also be used.

Examples of the inorganic physical foaming agent include water, carbon dioxide, nitrogen and the like.
Among the other foaming agents, methyl chloride, ethyl chloride, dimethyl ether, diethyl ether, ethyl methyl ether, methanol, ethanol, water, and carbon dioxide are preferable from the viewpoints of foamability and foam moldability.
These other foaming agents can be used alone or in admixture of two or more.

  In the composite foaming agent, the blending ratio of the saturated hydrocarbon is 10 to 80 mol%, and the blending ratio of the other foaming agent is 90 to 20 mol% (however, the total of the saturated hydrocarbon and the other foaming agent) The amount is preferably 100 mol%). By using a composite foaming agent having a blending ratio within this range, an extruded foam having a low apparent density can be produced safely and stably, and an extruded foam excellent in heat insulation and flame retardancy is produced. be able to. From this point of view, a composite foaming agent containing 30 to 70 mol% of saturated hydrocarbon and 70 to 30 mol% of other blowing agent (however, the total amount of the saturated hydrocarbon and other blowing agent is 100 mol%). Is more preferable.

  It is preferable to mix | blend the compounding quantity of this composite foaming agent so that it may become 0.5-2.5 mol in 1 kg of foamable molten resin compositions, and 0.8-2.0 mol is more preferable.

  A bubble regulator can be added to the foamable molten resin composition in order to adjust the average cell diameter of the 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 these air conditioners, talc is preferably used because it is easy to adjust the cell diameter of the foam obtained and it is easy to reduce the cell diameter. Talc having a 50% particle size by centrifugation 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 addition to the above-mentioned air conditioner and flame retardant, various additives such as a thermal insulation improver such as graphite, hydrotalcite, carbon black and aluminum, a colorant, a filler and a lubricant can be appropriately added. In addition, you may add various additives, such as the said bubble regulator, as a masterbatch which uses thermoplastic resins, such as a polystyrene-type resin, as a base material.

  Since the foam of the present invention contains the above-mentioned composite flame retardant and a flame retardant aid blended as necessary, it has excellent thermal stability during processing during extrusion, and its recycled polystyrene resin has a reduced molecular weight during recovery. The degree of yellowing and the generation of black spots are small. Accordingly, the use of the recycled polystyrene resin can reduce the amount of new polystyrene resin and the amount of new composite flame retardant, so that the foam of the present invention can be produced at low cost. it can. The amount of the regenerated polystyrene resin added is preferably 300 parts by weight or less, more preferably 100 parts by weight or less with respect to 100 parts by weight of virgin polystyrene resin.

  The foam of the present invention, for example, a plate-like polystyrene resin foam, can be suitably used for heat insulating materials such as building walls, floors, roofs, and tatami cores, taking advantage of its high flame retardancy. It can be done.

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

  In order to obtain the plate-like foams of Examples and Comparative Examples, the following apparatuses and raw materials were used.

  A first extruder with an inner diameter of 65 mm and a second extruder with an inner diameter of 90 mm are connected in series, and a blowing agent inlet is provided near the end of the first extruder, and the horizontal section is 1 mm in length and 1 mm in width. A flat die having a 115 mm resin discharge port (die lip) is attached to the outlet of the second extruder, and the resin outlet of the second extruder is parallel to the extrusion direction of the foamable molten resin composition from the die. The apparatus provided with the shaping apparatus (guider) comprised by the board which consists of the installed upper and lower pair of polytetrafluoroethylene resin was used.

[Polystyrene resin]
Polystyrene (weight average molecular weight 273,000) was used as the polystyrene resin.
The weight average molecular weight of the polystyrene-based resin was determined by gel permeation chromatography (GPC) analysis. The measurement conditions are shown below.
<Measurement conditions for GPC analysis>
Equipment: GPC high performance liquid chromatograph column manufactured by GL Sciences Inc .: Showa Denko Co., Ltd., trade name ShodexGPC KF-806, KF-805, KF-803 are connected in series in this order, and column temperature used : 40 ° C
Solvent: THF
Flow rate: 1.0 mL / min Concentration: 0.15 w / v%
Injection volume: 0.2ml
Detector: UV-visible detector manufactured by GL Sciences Inc., trade name UV702 type (measurement wavelength 254 nm)
Molecular weight range of calibration curve used for calculation of molecular weight distribution: 1.2 × 10 ^{7 to} 5.2 × 10 ³

The following were used as flame retardants. The bromine content is a value measured according to JIS K7392: 2009.
(1) Flame retardant (A): Brominated styrene-butadiene copolymer, manufactured by Chemtura, trade name “Emerald 3000” (bromine content: 65% by weight)
(2) Flame retardant (B): Tetrabromobisphenol A-bis (2,3-dibromopropyl ether), manufactured by Daiichi Kogyo Seiyaku, trade name “Pyroguard SR720” (bromine content 67% by weight)
(3) Flame retardant (C): Tris (2,3-dibromopropyl) isocyanurate, manufactured by Suzuhiro Chemical Co., Ltd., trade name “FCP660” (bromine content 66 wt%)

  Flame retardant aid (D): Poly-1,4-diisopropylbenzene, manufactured by United Initiators, trade name “CCPIB”

As the heat stabilizer, the following (1) to (3) were mixed at a ratio of (1) 50% by weight, (2) 25% by weight, and (3) 25% by weight.
(1) Novolac type epoxy stabilizer: DIC, trade name “EPICLON N680” (2) Phosphorus stabilizer: ADEKA, trade name “PEP36” (bis (2,6-di-t-butyl-4- Methylphenyl) pentaerythritol-diphosphite)
(3) Hindered phenol stabilizer: manufactured by BASF, trade name “Irganox 1010” (pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate])

  Talc (manufactured by Matsumura Sangyo Co., Ltd., High Filler # 12) was used as a bubble regulator.

Example 1
In the first extruder, the polystyrene resin, the flame retardant (A), the flame retardant (B), the flame retardant (C), the flame retardant aid (D), which are described above so as to have the blending amounts shown in Table 1, A heat stabilizer and a bubble regulator (talc) are supplied, heated to 220 ° C. in the first extruder, kneaded, and from the physical foaming agent inlet provided near the tip of the first extruder, A physical foaming agent having the composition and amount shown in 1 was press-fitted.
In addition, a flame retardant (A), a flame retardant (B), a flame retardant (C), a flame retardant aid (D), and a heat stabilizer are converted into a twin-screw extruder (inner diameter 20 mm, L / D = 48). Supply the composite flame retardant to 2 parts by weight with respect to 100 parts by weight of the polystyrene resin, adjust the temperature so that the maximum temperature of the melt-kneading part is 190 ° C, and the resin temperature at the time of extrusion is 175 ° C. It was supplied to the extruder as a flame retardant melt kneaded material produced by extruding into a strand at 10 kg / hr and cutting into a pellet.

  Next, the foamable molten resin composition further kneaded in the first extruder is transferred to the subsequent second extruder, and the resin temperature is adjusted to the foaming suitability temperature (121 ° C .: this foamed resin temperature is determined between the extruder and the die. It is the temperature of the foamable molten resin composition measured at the position of the joint portion), and then extruded into a guider arranged in parallel with a gap of 25 mm from the die lip at a discharge rate of 70 kg / hr, and the guider while foaming. By passing through the inside, it was molded (shaped) into a plate shape to produce a plate-like foam.

  The foam obtained in Example 1 has an apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy (oxygen index, JIS A9521), occurrence of black spots, and occurrence of black spots on recycled resin. The situation is shown in Table 1.

Examples 2-5
A plate-like foam was produced in the same manner as in Example 1 except that the flame retardants (A), (B), and (C) were used in the amounts shown in Table 1. Table 1 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the obtained polystyrene resin foam.

Example 6
A plate-like foam was produced in the same manner as in Example 1 except that the flame retardants (A), (B), and (C) were used in the blending amounts shown in Table 1 and the flame retardant aid (D) was not used. . Table 1 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the obtained polystyrene resin foam.

Example 7
After the extruded foam plate obtained in Example 1 was pulverized, it was supplied to a single screw extruder having an inner diameter of 90 mm and L / D = 50 and kneaded at a maximum temperature of 230 ° C., and the molten resin was discharged at a discharge rate of 250 kg / hr. Extruded into a strand and cut into a pellet to obtain a recycled polystyrene resin (weight average molecular weight 268,000). A plate-like foam was produced in the same manner as in Example 1 except that 50 parts by weight of this recycled polystyrene resin was added to 100 parts by weight of the polystyrene resin. In addition, the compounding quantity of a flame retardant, a flame retardant adjuvant, a heat stabilizer, and a bubble regulator is a value with respect to 100 weight part of polystyrene resins. Table 1 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the obtained polystyrene resin foam.
In Example 7, when the foam was manufactured using the reproduction | regeneration polystyrene type resin obtained by setting the maximum temperature of the extruder at the time of collection to 230 degreeC, generation | occurrence | production of the black spot was suppressed. Furthermore, there was almost no black spot in the recovered material, and re-pelletization with high efficiency was possible.

  The polystyrene resin foams obtained in Examples 1 to 7 were extinguished in a short time in a combustion test according to the standard of JIS A9521 and had a sufficient oxygen index. Further, the foam had no black spots, was excellent in thermal stability during extrusion, and was excellent in recycling characteristics.

Comparative Example 1
Polystyrene as in Example 1 except that only the flame retardant (A) is used as the flame retardant in the amount shown in Table 2, and the flame retardants (B), (C), and the flame retardant aid (D) are not used. -Based resin foam was produced. The foam obtained in Comparative Example 1 was excellent in flame retardancy, but black spots were easily generated in the recycled material.

Table 2 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the foam obtained in Comparative Example 1.
From the comparison between Comparative Example 1 and the entire example, it can be seen that when only the flame retardant (A) is used, the same flame retardancy as in the example can be obtained, but the occurrence of black spots in the recycled material cannot be prevented.

Comparative Example 2
As a flame retardant, only the flame retardant (B) was used in the blending amount shown in Table 1, and the flame retardant aid (D) was added thereto in the blending amount shown in Table 2. A resin foam was produced. The obtained foam had no oxygen spots, but had a low oxygen index and a long time until the flame disappeared in the candle test, and was inferior in flame retardancy compared to the examples.

Table 2 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the foam obtained in Comparative Example 2.
From the comparison between Comparative Example 2 and the whole example, if the flame retardant (A) is not used, the generation of black spots on the recycled material can be prevented, but the flame retardancy is inferior even when the flame retardant aid (D) is used in combination. I understand that.

Comparative Example 3
As a flame retardant, only the flame retardant (C) was used in the blending amount shown in Table 1, and the flame retardant aid (D) was added in the blending amount shown in Table 2 to this. A resin foam was produced.

Table 2 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the foam obtained in Comparative Example 3.
From the comparison between Comparative Example 3 and Examples, if the flame retardant (A) is not used, generation of black spots on the recycled material can be prevented, but only the flame retardant (C) is used, and the flame retardant aid (D) is used for this. It turns out that it is inferior to a flame retardance even if it uses together.

Comparative Example 4
As a flame retardant, a combination of a flame retardant (A) and a flame retardant (B) is used in the blending amounts shown in Table 2, and a flame retardant aid (D) is not used. The body was manufactured. The foam obtained in Comparative Example 4 was inferior in flame retardancy and easily generated black spots in the recycled material.

Table 2 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the foam obtained in Comparative Example 4.
From Comparative Example 4, if the flame retardant (C) is not used, even if the amount of the flame retardant (A) is increased, the same level of flame retardancy as in the examples cannot be obtained. The amount of the flame retardant (A) It can be seen that the increase in the number of black spots on the recycled material cannot be prevented.

Comparative Example 5
As a flame retardant, a combination of a flame retardant (A) and a flame retardant (C) is used in the blending amounts shown in Table 2, and the flame retardant auxiliary (D) is not used. The body was manufactured. Although the foam obtained in Comparative Example 5 is superior to the flame retardancy of the foam of Comparative Example 4, the foam obtained in Examples is inferior in flame retardancy, and black spots are generated in the recycled material. It was easy to do.

Table 2 shows the apparent density, thickness, average cell diameter in the thickness direction, closed cell ratio, flame retardancy, occurrence of black spots, and occurrence of black spots in the recycled resin of the foam obtained in Comparative Example 5.
From Comparative Example 5, the flame retardancy of the flame retardant (C) is superior to that of the flame retardant (B), but if the flame retardant (C) is not used, the blending amount of the flame retardant (A) is increased. However, it can be seen that the incombustibility as in the examples cannot be obtained, and the generation of black spots in the recycled material cannot be prevented by increasing the blending amount of the flame retardant (A).

  From the comparison of the above Examples and Comparative Examples, the polystyrene resin foam of the present invention is flame retardant when the flame retardant (A), the flame retardant (B), and the flame retardant (C) are combined. Even if a small amount of the flame retardant (A) is blended, it will exhibit excellent flame retardancy in a combustion test according to the standard of JIS A9521 and have a sufficient oxygen index. I understand. Furthermore, it can be seen that there are no black spots, excellent thermal stability during extrusion, and excellent recycling characteristics.

  In the comparative examples in which the flame retardants are used alone or when these components are simply combined in two types, high flame retardancy, sufficient oxygen index, generation of black spots and yellow discoloration in the recycled raw material pellets are observed. Since a sufficiently suppressed foam cannot be obtained, the effect of the present invention is manifested for the first time by using a combination of the flame retardant (A), the flame retardant (B), and the flame retardant (C). It can be seen that the addition of the flame retardant aid (D) makes it even larger.

  The measurement methods and evaluation methods for various physical properties of the foams shown in Tables 1 and 2 are as follows.

(Apparent density)
The apparent density of the foam was determined as follows. Each sample of a rectangular parallelepiped of 50 × 50 × 20 mm is cut out from the center and both ends in the width direction of the obtained foam, the weight is measured, and the apparent density of each sample is calculated by dividing the weight by the volume. And the arithmetic average value thereof was taken as the apparent density.

(Thickness)
In the vicinity of the central portion in the width direction of the foam, the thicknesses of five points were measured at equal intervals, and the arithmetic average value of these measured values was taken as the thickness (mm) of the foam.

(Closed cell rate)
The closed cell ratio of the foam was determined as follows. First, the foam was divided into five equal parts in the width direction, and cut samples (total of 5 pieces) having no molded skin were cut out in the size of 25 mm × 25 mm × 20 mm from the vicinity of the center. Next, according to the procedure C of ASTM-D2856-70, the true volume Vx of each cut sample is measured, the closed cell ratio S (%) is calculated by the following formula (1), and the arithmetic average value of these calculated values is calculated. The closed cell ratio of the foam was used. In addition, Toshiba Beckman Co., Ltd. air comparison type hydrometer 930 type | mold was used as a measuring apparatus.

S (%) = (Vx−W / ρ) × 100 / (Va−W / ρ) (1)
However, Vx: the true volume (cm ³ ) of the cut sample obtained by measurement with the above air comparison hydrometer (the volume of the resin composition constituting the cut sample of the foam, and the bubbles in the closed cell portion in the cut sample Equivalent to the sum of the total volume.)
Va: Apparent volume of the cut sample calculated from the outer dimensions of the cut sample used for measurement (cm ³ )
W: Total weight of cut sample used for measurement (g)
ρ: Density of resin composition constituting foam (g / cm ³ )

(Average cell diameter in the thickness direction)
By the above method, the average cell diameter in the thickness direction of each part was measured from the foam, and the arithmetic average value of these measured values was taken as the average cell diameter (mm) of the foam.

(Remaining amount of isobutane)
The 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. Then, a test piece of about 1 g was cut out from the center of the foam and subjected to gas chromatographic analysis. The amount of foaming agent (isobutane) remaining in the foam was determined.
<Measurement conditions for gas chromatographic analysis>
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

(Flame retardant evaluation: LOI (oxygen index))
The 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. Then, a test piece was cut out from the foam and measured according to JIS K7201-2: 2007. Flammability was evaluated. The type of the heat source of the igniter was liquefied petroleum gas (LPG), the ignition procedure was method A, and the test piece was performed independently at a predetermined position in the tester. The test place temperature was 23 ° C. and humidity 50%.

(Flame retardant evaluation: candle test)
The 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 five test pieces were randomly cut out from the foam (N = 5). JIS A9521: 2014 B.I. 2.1 Flammability was measured based on “Measurement Method A”, and the flame retardancy of the foam was evaluated based on the average burning time of five test pieces.

(Spot of foam)
The foam was visually observed at five cross sections cut perpendicular to the extrusion direction.
○: 0 to 1 △: 2 to 5 ×: 6 or more

(Recycled resin black point: first playback)
After the foam is pulverized, it is supplied to a single-screw extruder having an inner diameter of 90 mm and L / D = 50 and kneaded at a maximum temperature of 220 ° C. or 230 ° C. shown in Table 1, and the molten resin is discharged at a discharge rate of 50 kg. Extruded into a strand at / hr and cut into a pellet to produce a polystyrene resin composition pellet. A resin plate was prepared using a hydraulic press machine and a mold having a thickness of 1 mm and a shape of 100 × 100 mm heated to 180 ° C., and the number of black spots contained in the plate was visually measured.
○: 0 to 1 △: 2 to 5 ×: 6 or more

(Recycled resin black point: second playback)
The pellets obtained at the first regeneration (with a maximum temperature of 220 ° C.) were further fed to a single screw extruder having an inner diameter of 90 mm and L / D = 50, and the maximum temperature shown in Table 1 was 220 ° C. or 230 ° C. Kneaded, and the molten resin was extruded into a strand at a discharge rate of 50 kg / hr and cut into a pellet to produce a pellet of a polystyrene-based resin composition. A resin plate was prepared using a hydraulic press machine and a mold having a thickness of 1 mm and a shape of 100 × 100 mm heated to 180 ° C., and the number of black spots contained in the plate was visually measured.
○: 0 to 1 △: 2 to 5 ×: 6 or more

(Yellowing of recycled resin: first playback)
Black point of regenerated resin: The color of the resin plate produced in the first recycle was confirmed visually.
○: Transparent and the color tone does not change △: Slightly yellowish ×: Yellowish remarkably strong

(Yellow color of recycled resin: 2nd playback)
Black point of regenerated resin: The color of the resin plate produced in the second regeneration was visually confirmed.
○: Transparent and the color tone does not change △: Slightly yellowish ×: Yellowish remarkably strong

Claims (3)

In the polystyrene resin foam containing a flame retardant, the flame retardant comprises (A) a brominated butadiene-styrene copolymer, (B) tetrabromobisphenol A-bis (2,3-dibromopropyl ether), (C) a composite flame retardant with tris (2,3-dibromopropyl) isocyanurate, and the blending ratio of (A) brominated butadiene-styrene copolymer in the composite flame retardant is 20 to 90% by weight (However, the sum of (A), (B) and (C) is 100% by weight.), (B) tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and (C) tris ( A blended weight ratio with 2,3-dibromopropyl) isocyanurate is 10:90 to 90:10.
The foam further contains poly-1,4-diisopropylbenzene, and the amount of poly-1,4-diisopropylbenzene is 1 to 20 parts by weight with respect to 100 parts by weight of the composite flame retardant. The polystyrene resin foam according to claim 1, wherein the foam is a polystyrene resin foam.
(A) The blended amount of brominated butadiene-styrene copolymer is 0.2 parts by weight or more and less than 1 part by weight with respect to 100 parts by weight of polystyrene resin constituting the foam. The polystyrene resin foam according to 2.