JP6389591B2 - Method for producing polystyrene resin foam - Google Patents

Description

  The present invention relates to a method for producing a polystyrene resin foam, and more particularly to a method for producing a polystyrene resin foam having excellent thermal stability during production, excellent flame retardancy, and excellent recyclability.

  Conventionally, an air conditioner is added to a polystyrene-based resin material, heated and kneaded by an extruder, and then a physical foaming agent is pressed into the extruder and further kneaded, and the molten mixture is changed from a high pressure range to a low pressure range (usually atmospheric) And a method of obtaining a polystyrene resin foam (hereinafter also referred to as a foam) is known.

In order to use the 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 A9511: 2006R. 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, for HBCD, there is a movement of regulation under the Chemical Substances Examination Regulation Law and REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), and HBCD flame retardant is not used assuming that it is designated as a regulated substance Development of foam manufacturing technology is required.

  On the other hand, chlorofluorocarbons (hereinafter referred to as CFC) such as dichlorodifluoromethane have been widely used as a foaming agent in the foam production method. However, CFC, which is suspected to be related to the problem of ozone hole expansion, has been refrained from use, and hydrogen atom-containing fluorinated fluorinated hydrocarbons (hereinafter referred to as HCFC) with a low ozone destruction coefficient and ozone destruction coefficient of 0 ( Zero) hydrogen-containing fluorinated hydrocarbons (hereinafter referred to as HFCs) have come to be used in place of CFCs. 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 give sufficient flame retardancy to polystyrene-based resin foams, it is more than in the case of manufacturing using nonflammable foaming agents such as HFC. Of 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, studies have been made on polystyrene resin foams using excellent flame retardants other than HBCD. For example, a brominated butadiene polymer type such as a brominated styrene / butadiene copolymer represented by Patent Document 1 has been proposed.

  In order to improve the thermal stability of this brominated butadiene polymer type flame retardant, a flame retardant containing an alkyl phosphite and / or an epoxy compound in a brominated butadiene homopolymer or brominated styrene / butadiene block copolymer is provided. A method of using it has also been proposed (see, for example, Patent Document 2).

JP 2009-516019 A JP 2012-512942 A

  However, the brominated butadiene polymer type flame retardant disclosed in Patent Document 1 can impart excellent flame retardancy to the foam, but is inferior in thermal stability at the time of extrusion processing, resulting in foaming. There was a problem that black spots and discoloration occurred in the body.

  Moreover, in patent document 2, since the said brominated butadiene polymer type flame retardant and heat stabilizers, such as an alkyl phosphite and / or an epoxy compound, were used together, compared with the flame retardant of patent document 1, it is at the time of an extrusion process. The thermal stability is slightly improved.

  However, since the flame retardant of Patent Document 2 is prepared by dry blending a brominated butadiene polymer type flame retardant with an alkyl phosphite or epoxy compound as a heat stabilizer, extrusion foaming in a continuously stable state. It was difficult to manufacture the body.

  In addition, in this dry blend method, the above-mentioned components are not uniformly mixed, so the function of the added heat stabilizer is not sufficiently exhibited, so the thermal stability of the brominated butadiene polymer type flame retardant is not improved so much. In some cases, black spots or discoloration may occur due to heating. Therefore, when a polystyrene resin foam is produced using the flame retardant of Patent Document 2, although the thermal stability during extrusion is slightly improved, the generation of black spots during extrusion foaming and polystyrene as the base resin It was difficult to suppress the decrease in molecular weight and yellowing due to the decomposition of the resin.

  For this reason, there has been a strong demand for research and development of a method for producing extruded polystyrene-based foams that have brominated butadiene polymer type flame retardants and do not have black spots or discoloration and are excellent in flame retardancy. At present, no such proposal has been made.

  In the present invention, in view of the state of the prior art, when producing a polystyrene resin foam using a brominated butadiene polymer as a flame retardant, the occurrence of black spots during extrusion foaming is suppressed, and An object of the present invention is to provide a method for producing a polystyrene resin foam that can suppress a decrease in molecular weight and yellowing due to decomposition of a polystyrene resin that is a base resin and is excellent in flame retardancy.

According to this invention, the manufacturing method of the polystyrene-type resin foam shown below is provided.
<1> In a method for producing a foam by extruding a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant, a heat stabilizer and a foaming agent,
The heat stabilizer comprises a phenol-based heat stabilizer, a phosphite-based heat stabilizer, and an epoxy resin-based heat stabilizer, and the flame retardant crushes or crushes the particulate brominated butadiene-based polymer into small particles. was classified with a phased or sieve screen, the proportion passing through a sieve screen with a mesh opening 500μm is have a 95% or more by weight of particle size, the average diameter of 50 vol% is a brominated butadiene polymer 30~350μm A method for producing a polystyrene-based resin foam characterized by the above.
<2> The total amount of the heat stabilizer is 10 to 25 parts by weight with respect to 100 parts by weight of the brominated butadiene polymer, and the amount of the flame retardant containing the brominated butadiene polymer is extruded. The method for producing a polystyrene resin foam according to <1> , wherein the amount is 1.5 to 7 parts by weight with respect to 100 parts by weight of the polystyrene resin supplied to the machine .

  According to the method for producing a polystyrene resin foam of the present invention, the flame retardant is excellent in flame retardancy by producing a polystyrene resin foam using a brominated butadiene polymer having a specific particle size. And the favorable foam by which the malfunction of the external appearance represented by the black spot and yellowing was suppressed can be obtained.

  In addition, when the foam obtained by the production method of the present invention, and its scraps and scraps are heated and melted and reused as a recycled material, the molecular weight and yellowing of the recycled material can be suppressed, and black spots are generated. Can be suppressed.

Hereinafter, the manufacturing method of the polystyrene-type resin foam of this invention is demonstrated in detail.
The method for producing a polystyrene resin foam of the present invention is a method for producing a foam by extruding a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant, a heat stabilizer and a foaming agent. A brominated butadiene polymer having a specific particle size of 95% by weight or more passing through a sieve screen having a mesh size of 500 μm is used.

  As described above, the brominated butadiene-based polymer exhibits an excellent effect of imparting flame retardancy when used as a flame retardant for thermoplastic resins such as polystyrene. However, because of poor thermal stability during melt processing, bromine tends to be liberated from the polymer depending on the melt processing conditions, and the liberation of bromine may reduce the effect of imparting flame retardancy and may cause decomposition of the thermoplastic resin. is there. Furthermore, since the brominated butadiene-based polymer is a polymer, if a carbon-carbon unsaturated bond is formed in the polymer by liberation of bromine, the polymer itself or the thermoplastic resin may be colored, There were various problems such as cross-linking of unsaturated bonds that could cause gelation of the brominated butadiene-based polymer and generation of black spots.

  In general, in order to suppress the liberation of bromine during melt processing, a method of adding a heat stabilizer can be considered, but the heat stabilizer is simply added to the brominated butadiene polymer by the dry blend method or the master batch method. However, it was not possible to sufficiently suppress the occurrence of discoloration and black spots.

The reason for this is not clear at this time, but is estimated as follows.
Commercially available brominated butadiene-based polymers are particulate, but exhibit a wide particle size distribution including particles of various particle sizes. When a polystyrene resin foam is produced, when a commercially available brominated butadiene polymer and a heat stabilizer are mixed by dry blending and blended with a polystyrene resin, a brominated butadiene type having a large particle size is obtained. Because of the large number of polymers, when the brominated butadiene polymer and thermal stabilizer are kneaded with polystyrene resin in the extruder, the thermal stabilizer is sufficiently close to the brominated butadiene polymer. As a result, it is difficult to effectively suppress the decomposition of the brominated butadiene-based polymer. As a result, black spots are generated during extrusion foaming, and there are many black spots in the resulting foam. The problem of yellowing occurs.

  Also, when the brominated butadiene polymer and the heat stabilizer are mixed by the master batch method, for the same reason, the brominated butadiene polymer dispersed in the base resin (for example, polystyrene resin) is mixed. , Because it is difficult for the heat stabilizer to exist in close proximity, and the decomposition of the brominated butadiene polymer cannot be effectively suppressed, or there are already many black spots in the obtained master batch. When a polystyrene resin foam is produced by blending such a masterbatch, black spots are further generated in the extruder, and a large number of black spots are present in the resulting foam, and the foam turns yellow. Such a problem occurs.

  On the other hand, when a brominated butadiene polymer having a small particle size having a specific particle size is used as a flame retardant as in the production method of the present invention, it may be kneaded with a polystyrene resin in an extruder. The thermal stabilizer is present in the vicinity of the brominated butadiene polymer, the thermal stabilizer effectively acts on the brominated butadiene polymer, and the decomposition of the brominated butadiene polymer is suppressed. For this reason, the polystyrene-type resin extrusion foam by which generation | occurrence | production of the black spot and yellowing was suppressed can be obtained. In addition, even when a polystyrene resin extruded foam in which the occurrence of black spots and discoloration is suppressed is heated and melted and reused as a recycled material, a polystyrene resin extruded foam having almost no black spots or yellowing is obtained. can get.

  The flame retardant used in the present invention is a brominated butadiene-based polymer having a small particle size, and specifically, a brominated butadiene-based polymer having a particle size of 95% by weight or more passing through a sieve screen having an opening of 500 μm. It is a polymer.

As described above, when the brominated butadiene-based polymer used as the flame retardant has a small particle size that passes through a sieve mesh having an opening of 500 μm, the thermal stabilizer is brominated butadiene. It has been found that it can effectively act on a polymer and suppress the generation of black spots.
Further, in order to effectively suppress the number of black spots in the obtained foam, it is not necessary that all of the brominated butadiene-based polymer used as a flame retardant has a small particle size, most of which is a small particle size I found that it would be good.

That is, normally, when producing a foam, black spots are generated in addition to the black spots derived from the brominated butadiene-based polymer. However, this black spot is not so much that the appearance of the foam is remarkably deteriorated. Here, even if a small amount of particles having a large particle size on a sieve screen having an opening of 500 μm is contained on a weight basis, the ratio is extremely small on a number basis. Further, even a brominated butadiene polymer having a large particle size does not all become black spots due to heat during extrusion.
As a result of further investigations, the majority of brominated butadiene polymers used as flame retardants have a small particle size, that is, the ratio of passing through a sieve screen having an opening of 500 μm is 95% by weight or more. For example, among the brominated butadiene polymers used as flame retardants, the probability of black spots becomes extremely low, and it is possible to obtain a foam having the same number of black spots as a foam not blended with brominated butadiene polymers. I found out that I can do it.

  However, from the viewpoint of suppressing the generation of sunspots, the ratio of the brominated butadiene polymer having a large particle size is preferably as small as possible, and the ratio of passing through a sieve screen having a mesh size of 500 μm is 97% by weight or more. Is preferable, more preferably 99% by weight or more, and still more preferably 100% by weight.

As a method for obtaining a brominated butadiene polymer having a particle size of 95% by weight or more passing through a sieve screen having an opening of 500 μm, for example, a brominated butadiene polymer described later is used as a raw material, and this is pulverized and crushed For example, a method of reducing the particle size by performing a process, a method of classifying using a sieve net, or the like.
In the present invention, the opening means a nominal opening based on JIS Z8801-1: 2006.

The raw material brominated butadiene-based polymer itself is known, and examples thereof include those disclosed in Patent Documents 1 and 2.
These brominated butadiene-based polymers have a weight average molecular weight of about 1.0 × 10 ^{3 to} 2.0 × 10 ⁵ , preferably 2.0 × 10 ^{3 to} 1.0 × 10 ⁵ , more preferably in terms of polybutadiene. Is produced by brominating a butadiene-based polymer of 5.0 × 10 ^{3 to} 1.0 × 10 ⁵ , more preferably 5.0 × 10 ^{4 to} 1.0 × 10 ⁵ .

  The brominated butadiene polymer is preferably a block copolymer, random copolymer or graft copolymer containing a styrene monomer component unit in consideration of compatibility with polystyrene resin. (Hereinafter, these are also collectively referred to as a brominated butadiene-styrene copolymer.) A block copolymer of a polystyrene polymer block and a brominated polybutadiene block is more preferable.

  Examples of styrenic monomers include styrene, brominated styrene, chlorinated styrene, 2-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, α-methylstyrene, and among these, styrene 4-methylstyrene, α-methylstyrene or a mixture thereof is preferred, and styrene is more preferred.

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

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

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

（式中、Ｘ、Ｙ及びＺは、正の整数である。）

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

  Such a brominated butadiene-styrene block copolymer is produced, for example, by brominating a butadiene-styrene block copolymer. Examples of the polybrominated butadiene-styrene copolymer include commercially available products such as Chemeral's Emerald 3000 and ICL-IP's FR122P.

Furthermore, the brominated butadiene polymer used in the method for producing a polystyrene resin foam according to the present invention preferably has a 50 volume% average diameter of 10 to 400 μm, more preferably 30 from the viewpoint of handleability. ˜350 μm.
The 50 volume% average diameter is obtained as the particle diameter when the brominated butadiene polymer particles are dispersed in water and the particle size distribution is measured by a laser diffraction scattering method, and the cumulative volume with respect to the volume of all particles is 50%. . As the measuring device, for example, Microtrack MT-3300EX manufactured by Nikkiso Co., Ltd. can be used.

In the method for producing a polystyrene resin foam of the present invention, a heat stabilizer is further blended.
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 5 to 30 parts by weight, more preferably 10 to 25 parts by weight, based on 100 parts by weight of the brominated butadiene polymer.

  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, that is, a so-called brominated 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-tert-butylphenyl) pentaerythritol diphosphite, tetra (tridecyl) -4,4′-butylidene-bis (2-tert-butyl-5-methylphenyl) diphosphite, bis [2,4- Bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphorous acid, tetrakis (2,4, -di-t-butylphenyl) [1,1-biphenyl] -4,4′-diylbis Phosphonite, bis (nonylphenyl) pentaerythritol diphosphite, bisstearyl pentaerythritol diphosphite, 2,2 -Methylenebis (4,6-di-t-butyl-1-phenyloxy) (2-ethylhexyloxy) phosphorus, mono (dinonylphenyl) mono-p-nonylphenyl phosphite, tris (monononylphenyl) phosphite, Tetraalkyl (C = 12-16) -4,4′-isopropylidene- (bisphenyl) diphosphite, hexatridecyl-1,1,3-tris (3-t-butyl-6-methyl-4oxyphenyl) -3-Methylpropane triphosphite, diphenylisodecyl phosphite, tridecyl phosphite and the like. You may use these individually or in combination of 2 or more types. Among these, tris (2,4-di-t-butylphenyl) phosphite or bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite is preferable from the viewpoint of extrusion stability. .

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-t-butyl-4-hydroxyphenyl) propionate] methane, 2,2-methylenebis (4-methyl-6-t-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 Can be 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 hindered amine compounds include 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, or 4-hydroxy-1-octyl. Aliphatic or aromatic carboxylic acid ester of oxy-2,2,6,6-tetramethylpiperidine, 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-pi Lysinyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) -1,2,3,4-butanetetracarboxylate and the like. It is done. 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 the extinction with respect to flame retardancy and not reducing the heat resistance of the extruded foam 4-Butanetetracarboxylate or bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate is preferred.

  In the present invention, in the production of a foam using a brominated butadiene polymer as a flame retardant, the blending method of the brominated butadiene polymer is not particularly limited. For example, (1) bromine having a specific particle size (2) A method in which a brominated butadiene polymer having a specific particle size and a heat stabilizer are dry-blended and supplied to an extruder ( 3) A method of melt-blending a brominated butadiene-based polymer having a specific particle size and a heat stabilizer and supplying them to an extruder can be employed.

  When the blending method (1) is adopted, the heat stabilizer may be blended in advance with a polystyrene resin. When the blending method (2) is adopted, even if the brominated butadiene polymer and the stabilizer are mixed by dry blending and supplied to the extruder, the brominated butadiene copolymer and the thermal stabilizer are further mixed. The dry blend mixture may be supplied as a granulated product hardened with a binder. This dry blend method is preferable from the viewpoint of more effectively suppressing the generation of black spots by a simple operation method.

  When the blending method (3) is adopted, a flame retardant composition obtained by melt blending a brominated butadiene polymer and a heat stabilizer is a flame retardant master batch using a polystyrene resin or the like as a base resin. Alternatively, it may be a flame retardant melt kneaded material produced substantially without using a base resin. Moreover, the recycling raw material obtained by heat-melting the foam obtained by the manufacturing method of this invention, its end material, and scrap may be sufficient. Moreover, a coloring agent may be mix | blended with the flame retardant melt-kneaded material. This melt blending method is preferable from the viewpoint that black spots can be effectively suppressed and discoloration can be remarkably suppressed.

  The concentration of the brominated butadiene polymer in the flame retardant masterbatch is usually about 10 to 80% by weight, and considering the addition efficiency of the flame retardant, the lower limit is preferably 20% by weight, more preferably Is 30% by weight.

The flame retardant composition is produced by introducing a brominated butadiene polymer, a heat stabilizer, and, if necessary, a base resin such as a polystyrene resin into an extruder or a mixer and kneading them. In order to effectively suppress the decomposition of the brominated butadiene-based polymer, the resin temperature at the time of kneading is preferably as low as possible, and is generally 190 ° C. or lower, preferably 185 ° C. or lower. On the other hand, from the above viewpoint, the lower limit of the resin temperature at the time of kneading is not particularly limited, but in order to stably melt knead the brominated butadiene-based polymer and the heat stabilizer, it is approximately 140 ° C. or higher. It is preferable to set it to 150 ° C. or higher.
In addition, the flame retardant composition is preferably cut into a pellet after being extruded in a strand form from an extruder from the standpoint of meterability and ease of handling.

  The flame retardant melt kneaded product used in the present invention preferably further contains an aromatic phosphate as a fluidity improver. By containing the aromatic phosphate ester, the fluidity of the flame retardant melt kneaded material containing the brominated butadiene flame retardant can be effectively improved, and as a result, foaming is performed using the flame retardant melt kneaded material. When the body is manufactured, the generation of black spots can be more effectively suppressed.

Specific examples of the aromatic phosphate ester include triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylyl phosphate, octyl diphenyl phosphate, cresyl diphenyl phosphate, 1,3-phenylenebis (diphenyl phosphate), 1,3-phenylenebis (di-2,6-xylenyl phosphate) and the like.
Among these, aromatic phosphate esters such as triphenyl phosphate (TPP) are preferable because handleability and effect expression are more remarkable.

  The blending amount of the aromatic phosphate with respect to the brominated butadiene polymer is not particularly limited as long as the function of improving the fluidity of the flame retardant melt kneaded product is exhibited and the flame retardancy imparting effect is not hindered. However, the fluidity improver is preferably blended in an amount of 0.5 to 5 parts by weight, more preferably 1 to 4 parts by weight, based on 100 parts by weight of the brominated butadiene polymer. .

  In the present invention, poly-1,4-diisopropylbenzene can be used together with the brominated butadiene polymer and the heat stabilizer.

（ｎは繰り返し単位である） This poly-1,4-diisopropylbenzene is represented by the following structural formula and is a known compound per se.

(N is a repeating unit)

  Since poly-1,4-diisopropylbenzene functions as a flame retardant aid that further improves the excellent flame retardancy of the brominated butadiene polymer, the amount of the brominated butadiene polymer is small. Even in such a case, it is possible to obtain a foam having excellent flame retardancy and sufficient oxygen index, and further, coloring of the polystyrene resin as the base resin is suppressed, and the polystyrene resin extrusion that can be used as a regenerated raw material. A foam is obtained.

  The blending amount of poly-1,4-diisopropylbenzene is not particularly limited, but is preferably 2 to 15 parts by weight, more preferably 3 to 12 parts by weight with respect to 100 parts by weight of the brominated butadiene polymer. It is.

  In addition to the brominated butadiene-based polymer, other flame retardants can be mixed within a range that does not interfere with the object and effect of the present invention. Other flame retardants include, for example, tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S-bis (2,3-dibromo-2-methylpropyl ether), An organic compound having a 2,3-dibromo-2-methylpropyl group represented by tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether)), tetrabromobisphenol-A-bis (2 , 3-dibromopropyl ether), tetrabromobisphenol-S-bis (2,3-dibromopropyl ether), tetrabromobisphenol-F-bis (2,3-dibromopropyl ether), tris (2,3-dibromopropyl) ) Isocyanurate and tris (2,3-dibromopropyl) silane Organic compounds having a 2,3-dibromopropyl group typified by annulate, mono (2,3,4-tribromobutyl) isocyanurate, di (2,3,4-tribromobutyl) isocyanurate, tris (2 , 3,4-Tribromobutyl) isocyanurate, brominated isocyanurate, cresyl di 2,6-xylenyl phosphate, antimony trioxide, antimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, pentabromo Examples thereof include nitrogen-containing cyclic compounds such as toluene, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam, and melem, silicone compounds, inorganic compounds such as boron oxide, zinc borate, and zinc sulfide. These compounds can be used alone or in admixture of two or more.

Below, the manufacturing method of the polystyrene-type resin foam of this invention is demonstrated in detail.
The method for producing a polystyrene resin foam of the present invention employs a method of producing a foam by extruding a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant, a heat stabilizer and a foaming agent. .

  As specific examples, a polystyrene resin, a flame retardant or a flame retardant composition, and, if necessary, a heat stabilizer, a bubble regulator and other additives are supplied to an extruder, heated, kneaded, and further foamed. The foamable polystyrene resin melt composition obtained by press-fitting an agent into the extruder and kneading is extruded into a low pressure region (usually in the atmosphere) from the inside of the high pressure extruder through a flat die and foamed. In addition, a molding die arranged at the outlet of the die [shape forming apparatus (parallel or formed by two plates of upper and lower polytetrafluoroethylene resins and the like installed so as to expand gently from the inlet to the outlet) Hereinafter, it is also referred to as a guider)]] and a method for producing a plate-like polystyrene resin extruded foam (hereinafter also simply referred to as an extruded foam) by passing it through a molding tool such as a molding roll. And the like.

  The method for producing a polystyrene-based resin foam of the present invention is not limited to the above-described method for producing a plate-like extruded foam, and a cylindrical foam extruded from a circular die is cut into a sheet, or A method in which the inner surface of a cylindrical foam is fused to obtain a sheet-like extruded foam, a method in which a foam extruded in a strand is cut into particles, and a particulate extruded foam is obtained, and a foaming agent By extruding the foamable molten resin composition containing water into water and cutting it into particles (without foaming), and then heating the foamable resin particles containing the foaming agent with a heating medium such as steam. It can be applied to a method of foaming into a particulate foam.

  In the method for producing a polystyrene resin foam of the present invention, the basic production method other than using the brominated butadiene polymer having the specific particle size described above as a flame retardant is foaming using a conventionally known extruder. Body manufacturing methods are available.

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

  As said polystyrene-type resin, what mixed the other polymer may be sufficient in the range in which the objective of this invention and an effect are achieved. Other polymers include polyester resins and polyethylene resins (one or a mixture of two or more selected from the group consisting of ethylene homopolymers and ethylene copolymers having an ethylene unit component content of 50 mol% 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 resins, 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. And these other polymers are 50 weights in polystyrene resin To be less than, 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 composite 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, cyclopentane, 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 other foaming agents (B), organic physical foaming agents and inorganic physical foaming agents can be used.
Examples of the organic physical foaming agent 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, i- Examples include 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 unsaturated hydrocarbons such as tetrafluoropropene can also be used.
Examples of the inorganic physical foaming agent include water, carbon dioxide, nitrogen and the like.
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, ethyl methyl ether, methanol, ethanol, water, and carbon dioxide are preferable from the viewpoints of foamability and foam moldability.

  In the composite 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 with a blending ratio within this range, it is possible to safely and stably produce an extruded foam with a high expansion ratio, and to produce an extruded foam excellent in heat insulation and flame retardancy. preferable. 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 composite foaming agent containing

  The addition amount of the brominated butadiene-based polymer is appropriately adjusted depending on the desired flame retardancy, but the viewpoint of imparting high flame retardancy to the extruded foam to satisfy the combustion standard of JIS A9511. Is preferably 1 to 10 parts by weight, more preferably 1.5 to 7 parts by weight based on 100 parts by weight of the polystyrene-based resin supplied to the extruder. Parts by weight. Furthermore, if it is in the said range, while being excellent in a flame retardance, the foam which has favorable recyclability can be manufactured more easily.

  In the production method of the present invention, a foam regulator can be added to the foamable molten resin composition in order to adjust the average foam 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 the various bubble regulators, talc is preferably used because it is easy to adjust the bubble diameter of the foam obtained and to easily reduce the bubble diameter. In particular, the average particle diameter (light 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 fillers and lubricants 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.

The density of the 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 polystyrene resin foam produced by the method of the present invention, the average cell diameter in the thickness direction is preferably 0.8 mm or less, and more preferably 0.5 mm or less in order to obtain a foam having higher heat insulation properties. . If the cell 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 method for measuring the average cell diameter in the thickness direction is as follows. First, the foam is divided into three equal parts in the width direction, and a microscopic enlarged photograph of a width-direction vertical section (vertical section perpendicular to the extrusion direction of the extruded foam) in the vicinity of the center in the width direction of each divided measurement sample is obtained. Then, on the enlarged photograph, along the thickness direction of the foam, draw a straight line over the entire thickness, count the number of bubbles intersecting the straight line, and the length of the straight line (which is naturally This is not the length of the straight line on the enlarged photo, but the length of the straight line considering the enlargement ratio of the photo.) Is divided by the number of counted bubbles to obtain the average diameter Tn of the bubbles existing on each straight line ( The length of the straight line / the number of bubbles intersecting the straight line) is calculated, and the arithmetic average value of the three average diameters Tn thus obtained is defined as the average bubble diameter T (mm) in the thickness direction. Note that if the total thickness of the foam does not fit in one microscopic magnified photograph, it may be taken separately in several sheets. Moreover, when the foam has a shape such as a columnar shape, an arbitrary direction can be set as the thickness direction.

  In the present invention, the recycled polystyrene resin composition obtained by heating and melting the foam is heated in an extruder together with the virgin raw material polystyrene resin and, if necessary, a flame retardant or a flame retardant composition. A foam can be produced by kneading, adding a foaming agent by press-fitting into the extruder, and extruding the foamable molten resin composition obtained by kneading. The foam of the present invention is produced using the flame retardant melt-kneaded material as a flame retardant, and is excellent in thermal stability during processing during extrusion. Polystyrene-based resin composition) has a low molecular weight at the time of recovery, a degree of yellowing, and a small amount of black spots. Therefore, the foam can be produced at low cost by using the recovered raw material.

  The polystyrene resin foam obtained by the production method of the present invention can be suitably used for heat insulating materials such as walls, floors and roofs of buildings, tatami core materials, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

Examples 1-6, Comparative Examples 1-2
(Manufacture of polystyrene resin foam)
In order to obtain the extruded foams of Examples 1 to 6 and Comparative Examples 1 and 2, the following apparatuses and materials were used.

[Extruding equipment]
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, a foaming agent inlet is provided near the end of the first extruder, and a resin outlet having a rectangular cross section ( A flat die having a die lip) is connected to the outlet of the second extruder, and the resin outlet of the second extruder is constituted by a plate made of a pair of upper and lower polytetrafluoroethylene resins installed so as to be parallel thereto. A device with an attached guider was used.

[Flame retardant: Brominated butadiene polymer]
Table 1 shows the proportion of the brominated butadiene polymer used in Examples and Comparative Examples that passed through a sieve screen having a mesh size of 500 μm, and 50 volume% average diameter (D ₅₀ ).
D ₅₀ and D ₉₀ are values measured using Nikkiso Co., Ltd. Microtrac MT-3300EX.
FR1 in Table 1 is a brominated butadiene-styrene copolymer (Br-SBC, product name: Emerald 3000, bromine content 65% by weight, PS-converted weight average molecular weight 128,000, 200 ° C., shear rate 100 sec. The melt viscosity at ^-1 is 6000 Pa · s). FR2 and FR3 are obtained by classifying FR1 using a sieve screen. Specifically, FR2 is a sieve mesh pass having a mesh opening of 500 μm to a sieve mesh having a mesh opening of 212 μm, and FR3 is a sieve mesh having a mesh opening of 212 μm. FR4 is obtained by pulverizing FR1 with a Dalton pulverizer into small particles.

[Thermal stabilizer]
(1) Novolac type epoxy resin compound: manufactured by DIC, trade name “EPICLON N680”
(2) Phosphite compound: Product name “PEP36” (bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite) manufactured by ADEKA
(3) Phenol compound: manufactured by BASF, trade name “Irganox 1010” (pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate])

(Flame retardant additive form)
[Dry blend]
Using a mixer, the brominated butadiene polymer and the heat stabilizer were mixed (dry blended) under the blending conditions shown in Table 2.

[Flame retardant masterbatch (Flame retardant MB)]
Using a twin-screw extruder (inner diameter 47 mm, L / D = 41), the brominated butadiene polymer, heat stabilizer and base resin are melt-kneaded under the compounding conditions shown in Table 2, and extruded into a strand to form a pellet The flame retardant masterbatch (Flame retardant MB) was produced by cutting into 2 parts. As the base resin, polystyrene (PS) having a weight average molecular weight of 180,000 was used.

[Flame retardant melt-kneaded product]
Using a twin-screw extruder (inner diameter 47 mm, L / D = 41), the brominated butadiene polymer, heat stabilizer and fluidity improver are melt-kneaded under the compounding conditions shown in Table 2 and extruded into a strand. The melt-kneaded material was manufactured by cutting into a pellet form. In addition, triphenyl phosphate (TPP; manufactured by Daihachi Chemical Co., Ltd.) was used as a fluidity improver.

[Polystyrene resin]
(1) PS1: polystyrene (weight average molecular weight 270,000)
(2) RPS1: Recycled polystyrene resin composition The polystyrene resin extruded foam plate obtained in Example 1 is crushed, and the crushed material is supplied to a single screw extruder having an inner diameter of 90 mm and L / D = 50. Kneaded at a temperature of 220 ° C., the molten resin was extruded into a strand at a discharge rate of 250 kg / hr, and cut into a pellet to obtain a recycled PS resin composition pellet (RPS1).

[Bubble conditioner]
Talc (Matsumura Sangyo, high filler # 12)

  A polystyrene resin, a flame retardant, a heat stabilizer and a bubble regulator are mixed in the extruder so as to have the respective compounding amounts shown in Table 3, and supplied to the first extruder and heated to 220 ° C. These are kneaded, and the foamable resin melted is kneaded by supplying the physical foaming agent of the blending composition shown in the table to the melt at the ratio shown in the table from the blowing agent injection port provided near the tip of the first extruder. The product is supplied to the subsequent second extruder and the resin temperature is expressed as a foaming suitable temperature as shown in the table (in the table, it is expressed as a foamed resin temperature. This foaming temperature is the position of the junction between the extruder and the die. The measured temperature of the foamable resin melt was adjusted) and extruded from the die lip into the guider at a discharge rate of 70 kg / hr to produce a plate-like extruded foam.

  The apparent density, thickness, closed cell ratio, flame retardancy, number of sunspots, colorability, weight average molecular weight, regenerated resin of the polystyrene resin extruded foams obtained in Examples 1 to 6 and Comparative Examples 1 and 2 The weight average molecular weight is shown in Table 3.

  The measurement method and evaluation method of various physical properties of the extruded foam shown in Table 3 are as follows.

(Apparent density)
The apparent density of the extruded foam was determined as follows. A sample of a 50 × 50 × 40 mm rectangular parallelepiped is cut from the widthwise central portion and both end portions of the obtained extruded foam, and the weight is measured. The apparent density of each sample is obtained 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 extruded foam, thicknesses at five points were measured at equal intervals, and the arithmetic average value of these measured values was defined as the thickness (mm) of the extruded foam.

(Closed cell rate)
The closed cell ratio of the extruded foam was determined as follows. First, the extruded foam was divided into 5 equal parts in the width direction, and cut samples (total of 5 pieces) having no molded skin with a size of 25 mm × 25 mm × 20 mm were cut out from the vicinity of the central part thereof. 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 extruded 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 extruded foam and the closed cell portion in the cut sample (This corresponds to the sum of the total volume of bubbles.)
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 the resin composition constituting the extruded foam (g / cm ³ )

(Flame retardancy evaluation-JIS A9511)
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 five test pieces were randomly cut out from the extruded foam (N = 5). Combustibility was measured based on 5.13.1 “Measurement method A” of A9511 (2006R), and the flame retardancy of the extruded foam was evaluated based on the average burning time of five test pieces.

(Flame retardant evaluation-LOI-Oxygen index)
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 a test piece was cut out from the extruded foam and measured according to JIS K7201-2: 2007. The flame retardancy 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%.

(Number of sunspots)
The number of black spots was counted in a cross section cut perpendicular to the flow direction of the obtained plate-like foam. Observation of the cross section was arbitrarily measured at five locations, and the total number was taken as the number of black spots.

(Colorability)
The degree of yellowing of the extruded foam was evaluated by appearance.
○: Not colored ×: Colored

(Weight average molecular weight of extruded foam, weight average molecular weight of recycled resin)
The weight average molecular weight of the extruded foam obtained in each example and the extruded foam obtained by melting and re-pelletizing with an extruder for recycling were measured. The re-pellet is crushed into a size that can be supplied to an extruder, and the crushed material is supplied to a single-screw extruder having an inner diameter of 90 mm and L / D = 50, and melt kneaded at a maximum temperature of 220 ° C. The molten resin was extruded into strands at a discharge rate of 250 kg / hr and cut into pellets.
The weight average molecular weight is a value obtained by dissolving 10 mg of foam or 10 mg of styrene resin in 10 mL of THF (tetrahydrofuran), measuring by 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 KK, Shodex AC-80M, connected in series, column temperature: 40 ° C., flow rate: 1.0 ml. / Min. Detector: Measured using an ultraviolet-visible light detector UV-8020 manufactured by Tosoh Corporation.

In Examples 1 to 6 using a brominated butadiene-based polymer having a particle size of 95% by weight or more passing through a sieve screen having an opening of 500 μm as a flame retardant, this was dry blended with a stabilizer and an extruder. The combustion test according to JIS standards, either by the method of supplying to the reactor (Examples 1 and 2), by the method of supplying as a masterbatch (Example 3), or by the method of supplying by blending with the heat stabilizer. It was confirmed that a foam having a high flame retardancy having a very good oxygen index (specifically, LOI value: 26.0 to 26.5) can be obtained.
In addition, the foams of Examples 1 to 6 are excellent in thermal stability during extrusion, have no black spots or discoloration, and suppress molecular weight reduction or yellowing due to decomposition of the polystyrene resin as the base resin. It was confirmed that this was a polystyrene-based resin extruded foam excellent in recycling characteristics.

  In contrast, as a flame retardant, a brominated butadiene polymer (FR1) having a particle size of 67% by weight passing through a sieve screen having an opening of 500 μm was dry blended with a stabilizer and supplied to an extruder. Although the foam No. 1 exhibited a high degree of flame retardancy, the black spots were remarkably generated, the discoloration was remarkable, the recyclability was inferior, and it could not withstand actual use.

  Further, the foam of Comparative Example 2 in which the flame retardant FR1 was used as a master batch and supplied to the extruder also had black spots, and significant discoloration was confirmed.

Claims (2)

In the method for producing a foam by extruding a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant, a heat stabilizer and a foaming agent, the heat stabilizer is a phenol heat stabilizer, a phosphite system. The flame retardant comprises a heat stabilizer and an epoxy resin heat stabilizer, and the particle brominated butadiene polymer is pulverized or crushed into small particles or classified using a sieve screen, and has an opening of 500 μm. rate passing through the sieve screen is perforated over 95% by weight of the particle size, method of manufacturing polystyrene resin foam, wherein the average diameter of 50 vol% is brominated butadiene polymer 30～350Myuemu. The total amount of the heat stabilizer is 10 to 25 parts by weight with respect to 100 parts by weight of the brominated butadiene polymer, and the amount of the flame retardant containing the brominated butadiene polymer is supplied to the extruder. It is 1.5-7 weight part with respect to 100 weight part of said polystyrene-type resin made , The manufacturing method of the polystyrene-type resin foam of Claim 1 characterized by the above-mentioned.