JP2014208736A - Method for producing extruded foam body of polystyrene-based resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an extruded foam body of a polystyrene-based resin which can obtain a foamed body having high flame retardancy and sufficient oxygen index and suppresses the reduction in the molecular weight and yellowing due to the decomposition of a polystyrene-based resin which is a base material resin.SOLUTION: There is provided a method for producing an extruded foam body by supplying a polystyrene-based resin, a flame retardant and a foaming agent to an extruder and extruding a foamable molten resin composition obtained by kneading the polystyrene-based resin, the flame retardant and the foaming agent, where the flame retardant contains (1) a bromine-based flame retardant containing a polystyrene-bromated polybutadiene block copolymer and (2) a poly(1,4-diisopropylbenzene).

Description

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

  Conventionally, an air conditioner is added to a polystyrene-based resin material, heated and melt-kneaded by an extruder, and then a physical foaming agent is pressed into the extruder and further kneaded. Extruded in the atmosphere) and shaped into a plate shape by a shaping device connected to the die outlet of the extruder, and a high-thickness polystyrene resin extruded foam (hereinafter also referred to as extruded foam or foam) is used. The method of obtaining is known.

In order to use the extruded foam as a heat insulating material for construction, for example, it is required to satisfy the flammability standard of an extruded polystyrene foam heat insulating plate described in JIS A 9511 (2006R). For this purpose, a flame retardant is added to the extruded foam, and hexabromocyclododecane (hereinafter referred to as HBCD) has been widely used as the flame retardant. HBCD is an excellent flame retardant that is versatile and can provide a flame retardant effect with a relatively small amount of addition.
However, there is a movement of regulation by the Chemical Substances Control Law and REACH for HBCD, and it is required to develop a flame retardant alternative extrusion foam manufacturing technology that does not use HBCD flame retardant assuming that it is designated as a regulated substance. ing.

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

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

In the above situation, a polystyrene resin extruded foam using an excellent flame retardant other than HBCD has been studied.
For example, Patent Document 1 discloses 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 extruded foam, it is easily decomposed in the process of recovering the foam and re-pelletizing. When this recovered raw material is used as a part of a product, there may be a problem that the pressure required 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, since brominated isocyanurate is inferior in flame retardancy compared with HBCD or tetrabromobisphenol A- (2,3-dibromo-2-methylpropyl ether), the addition amount is increased and further diphenyl is added. Although it is necessary to add a flame retardant aid such as alkane, this diphenylalkane is insufficient in thermal stability under extrusion conditions, and leaves room for improvement in thermal stability.

  Patent Documents 3 and 4 propose a polystyrene brominated butadiene copolymer type flame retardant. This flame retardant has an advantage of high flame retardancy imparting effect.

JP 2005-139356 A JP 2003-292664 A JP 2009-516019 A JP 2012-512942 A

  However, in order to give the extruded foam high flame retardancy that satisfies the flame retardance standard of JIS A9511 (2006R), the amount added is at least 3 parts by weight or more with respect to the base polystyrene resin. There is a need to. Furthermore, even if the above alternative flame retardant is added in a large amount within a range not inhibiting the foaming, a foam having a sufficient oxygen index (specifically 26 or more) could not be obtained.

  In view of the above problems, the present invention is able to obtain a foam having high flame retardancy and a sufficient oxygen index, and further suppresses a decrease in molecular weight due to decomposition of a polystyrene resin as a base resin, An object of the present invention is to provide a method for producing a polystyrene resin extruded foam.

According to this invention, the manufacturing method of the polystyrene-type resin extrusion foam shown below is provided.
<1> In a method for producing an extruded foam by extruding a foamable molten resin composition obtained by supplying a polystyrene-based resin, a flame retardant and a foaming agent to an extruder and kneading them with the extruder. (1) A bromine-based flame retardant containing a polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene), and the polystyrene-based resin according to <1> Method for producing extruded foam.
<2> (1) The weight ratio of the brominated flame retardant containing polystyrene-brominated polybutadiene block copolymer to (2) poly (1,4-diisopropylbenzene) is 100: 1 to 100: 20. <1> The manufacturing method of the polystyrene-type resin extrusion foam as described in <1> characterized by the above-mentioned.
<3> (1) The addition amount of the brominated flame retardant containing polystyrene-brominated polybutadiene block copolymer is 1 part by weight or more and less than 3 parts by weight with respect to 100 parts by weight of the polystyrene resin. The manufacturing method of the polystyrene-type resin extrusion foam as described in <1> or <2>.
<4> The flame retardant further contains (3) at least one heat stabilizer selected from an epoxy heat stabilizer, a phosphorus heat stabilizer, a hindered phenol heat stabilizer, and a hindered amine heat stabilizer. The manufacturing method of the polystyrene-type resin extrusion foam in any one of <1>-<3> characterized by the above-mentioned.
<5> (1) A melt-kneaded product obtained by blending and kneading (3) a thermal stabilizer with a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer is supplied to an extruder. The manufacturing method of the polystyrene-type resin extrusion foam as described in <4>.
<6> The blowing agent is (A) 10 to 80 mol% of a saturated aliphatic hydrocarbon having 3 to 5 carbon atoms, and (B) methyl chloride, ethyl chloride, dimethyl ether, diethyl ether, ethyl methyl ether, methanol, ethanol, It consists of 90-20 mol% [however, the total amount of (A) blowing agent and (B) blowing agent is 100 mol%] selected from water and carbon dioxide. The manufacturing method of the polystyrene-type resin extrusion foam in any one of <1>-<5> characterized by the above-mentioned.
<7> Obtained by heating and melting a polystyrene resin extruded foam containing a brominated flame retardant containing (1) polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene). The method for producing a polystyrene resin extruded foam according to any one of <1> to <6>, wherein the recycled polystyrene resin composition is further supplied to an extruder.

In the present invention, (1) a flame retardant containing (2) poly (1,4-diisopropylbenzene) as a flame retardant auxiliary to a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer Therefore, it is possible to obtain a foam having a high degree of flame retardancy and a sufficient oxygen index, and the flame retardant is excellent in thermal stability during extrusion. It is possible to produce a polystyrene-based resin extruded foam in which a decrease in molecular weight due to is suppressed and there is no defect in appearance.
Furthermore, (1) the polystyrene-brominated polybutadiene block copolymer is easy to color the resin near the processing temperature of the polystyrene-based resin, and when the foam after extrusion is discolored or when producing a recycled material, If the extrusion conditions such as the residence time change, the recycled raw material may turn brown, but by using this flame retardant, even if the amount of brominated flame retardant blended is reduced, it is highly flame retardant. In addition, it is possible to obtain an extruded foam having a sufficient oxygen index. Therefore, even when the extruded foam or its end materials and scrap are heated and melted and reused as a recycled material, reduction in molecular weight and discoloration of the recycled material are suppressed. It has an effect that can be done.

Hereinafter, the manufacturing method of the polystyrene-type resin extrusion foam of this invention is demonstrated in detail.
The manufacturing method of the polystyrene-type resin extrusion foam of this invention employ | adopts the manufacturing method of the extrusion foam which extrude-foams the foamable molten resin composition obtained by knead | mixing a polystyrene-type resin, a flame retardant, and a foaming agent. As specific examples, a polystyrene resin, a flame retardant, if necessary, a cell conditioner and other additives, a recycled polystyrene resin composition, etc. are supplied to an extruder, heated and kneaded, and further a foaming agent is added. A foamable polystyrene resin melt composition obtained by press-fitting into an extruder and kneaded is extruded through a flat die into a low pressure region (usually in the atmosphere) from the inside of the high pressure extruder and foamed. A molding die arranged at the outlet of the plate [comprising a plate made of two or more upper and lower polytetrafluoroethylene resins installed in parallel or gently so as to expand gradually from the inlet to the outlet (hereinafter also referred to as a guider). )] And a forming roll or the like, and a method of producing a polystyrene resin extruded foam (hereinafter also simply referred to as an extruded foam) by molding it into a plate shape by passing it through a molding tool such as a molding roll. . In the production method of the present invention, a conventionally known method for producing an extruded foam can be used as a basic production method other than using a specific flame retardant described later.

  Examples of the polystyrene-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-butadiene copolymer, Styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-methylstyrene copolymer, styrene-dimethylstyrene copolymer, styrene-ethylstyrene copolymer, styrene-diethylstyrene copolymer, etc. It is done. The styrene unit component content in the styrenic copolymer is preferably 50 mol% or more, particularly preferably 80 mol% or more.

  As said polystyrene-type resin, what mixed the other polymer may be 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. These other polymers are listed in polystyrene resins. As it will be less than an amount%, preferably such that 30 wt% or less, more preferably such that 10 wt% or less, can be mixed according to the purpose.

  As will be described later, in addition to the polystyrene resin, a recycled polystyrene resin composition may be blended within a range that does not impair the characteristics. As such a regenerated polystyrene resin composition, (1) a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene) produced by the method of the present invention. And a recycled polystyrene-based resin composition obtained by heating and melting a polystyrene-based extruded resin foam.

  In the present invention, it is preferable from the viewpoint described in the background art to use a mixed foaming agent containing (A) a saturated aliphatic hydrocarbon having 3 to 5 carbon atoms and (B) another foaming agent shown below. .

Examples of the saturated aliphatic hydrocarbon having 3 to 5 carbon atoms (A) include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, and cyclopentane.
Said (A) saturated aliphatic hydrocarbon can be used individually or in mixture of 2 or more types.
Among the (A) saturated aliphatic 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.

(B) As other foaming agents, 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 (B) other foaming agent 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 viewpoint of foamability and foam moldability. .

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

  In the present invention, the amount of the foaming agent added is preferably 0.5 to 2.5 mol, more preferably 0.8 to 2.0 mol, in 1 kg of the foamable molten resin composition.

  In the present invention, (1) a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene) are used as the flame retardant.

（式中、Ｘ，Ｙ及びＺは、正の整数である。）
このようなポリスチレン−臭素化ポリブタジエン共重合体は、たとえばポリスチレン−ポリブタジエンブロック共重合体を臭素化することにより製造される。 The polystyrene-brominated polybutadiene block copolymer (1) used as a brominated flame retardant in the present invention is a conventionally known one. For example, those disclosed in Patent Documents 3 and 4 can be used as they are.
The polystyrene-brominated polybutadiene block copolymer used in the present invention can be represented by the following general formula.

(In the formula, X, Y and Z are positive integers.)
Such a polystyrene-brominated polybutadiene copolymer is produced, for example, by brominating a polystyrene-polybutadiene block copolymer.

  Examples of the polystyrene-brominated polybutadiene copolymer preferably used in the present invention include commercially available products such as Emerald 3000 from Chemtura and FR122P from ICL-IP.

  In the present invention, (2) poly (1,4-diisopropylbenzene) is used as a flame retardant aid for the brominated flame retardant (1).

This poly (1,4-diisopropylbenzene) is represented by the following structural formula and is a known compound per se.

The polystyrene-brominated polybutadiene block copolymer-based flame retardant (1), which has recently attracted attention as an alternative flame retardant for HBCD, has the following problems as described above.
(A) By adding a large amount, it is possible to obtain a polystyrene resin extruded foam that satisfies the flame retardant standard of JIS A9511, but a foam having a high oxygen index LOI (specifically, 26 or more). Is difficult to get.
(B) Due to the large amount of addition, the polystyrene-based resin is easily colored yellow or brown at the time of extrusion (at the time of extrusion foaming or at the time of re-pellet), and is difficult to use as a regenerated raw material.
(C) Although a coloring phenomenon can be suppressed by addition of a small amount, a foam excellent in flame retardancy cannot be obtained.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors, as a flame retardant aid for the flame retardant of (1) polystyrene-brominated polybutadiene block copolymer, (2) poly (1,4- Surprisingly, it has been found that when diisopropylbenzene) is selected and used, a foam having high flame retardancy and a sufficient oxygen index can be obtained. Furthermore, since a foam having high flame retardancy and a sufficient oxygen index can be obtained even if the amount of the flame retardant of (1) blended is small, in this case, it is a base resin. Polystyrene resin extruded foam that can be used as a raw material is obtained by suppressing the coloring of the polystyrene resin, and the above-mentioned problems of the flame retardant of polystyrene-brominated polybutadiene block copolymer (1) are all at once. I found out that it was resolved.

The reason for this is not clear at this time, but I think as follows.
In general, a flame retardant aid used for brominated flame retardants has a function of decomposing by heat to generate radicals and drawing out bromine brominated flame retardants at an early timing to improve the flame retardancy.

  Conventionally, 2,3-dimethyl-2,3-diphenylbutane (also referred to as dicumyl) is commonly used as this type of flame retardant aid, and its 50% heating weight loss temperature is about 200 ° C.

  On the other hand, poly (1,4-diisopropylbenzene) used in the present invention has a 50% heating weight loss temperature of 211 ° C., and its thermal decomposition temperature is higher than that of dicumyl, and has excellent thermal stability during extrusion. In addition, it has a characteristic that a large amount of radicals are generated when pyrolyzed, and this characteristic specifically acts on the polystyrene-brominated polybutadiene block copolymer of (1), which is a flame retardant, It is estimated that the flame retardancy of such a flame retardant and the thermal stability during extrusion are improved.

  (1) The blending ratio of the brominated flame retardant containing the polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene) is not particularly limited, but is obtained with thermal stability during extrusion. From the viewpoint of further improving the balance with the flame retardancy of the foam, the weight ratio of (1) :( 2) is preferably 100: 1 to 100: 20, more preferably 100: 2 to 100. : 15, more preferably 100: 3 to 100: 12.

  In the present invention, (2) poly (1,4-diisopropylbenzene) is added as a flame retardant aid to the brominated flame retardant containing the polystyrene-brominated polybutadiene block copolymer of (1). The amount of brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer can be greatly reduced as compared with the conventional one.

  The addition amount of the brominated flame retardant containing the polystyrene-brominated polybutadiene block copolymer of (1) is appropriately determined depending on the desired flame retardancy, but is usually based on 100 parts by weight of the polystyrene resin. About 1 to 10 parts by weight. In the present invention, for the reason described above, the addition amount of the brominated flame retardant containing the polystyrene-brominated polybutadiene block copolymer (1) is less than 3 parts by weight with respect to 100 parts by weight of the polystyrene resin. Even if it is a case where it is further 2.5 weight part or less, it is possible to obtain the polystyrene-type resin extrusion foam excellent in thermal stability, maintaining a flame retardance.

  In the present invention, the flame retardant (1) may be used by mixing other flame retardants. 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 represented by other brominated isocyanurates, cresyl di-2,6-xylenyl phosphate, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, Nitrogen-containing cyclic compounds such as pentabromotoluene, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam, melem, silicone compounds, inorganic compounds such as boron oxide, zinc borate, zinc sulfide, red phosphorus, Such as ammonium polyphosphate, phosphazene, hypophosphite, etc. Emissions-based compounds, and the like. These compounds can be used alone or in admixture of two or more. As this compounding quantity, it is 0.1-5 weight part, Preferably it is 0.2-3 weight part.

As described above, the flame retardant according to the present invention contains (1) a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene). However, it is preferable to further contain (3) a heat stabilizer.
(3) Examples of the thermal stabilizer include one or more selected from an epoxy stabilizer, a phosphorus stabilizer, a hindered 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 polystyrene-brominated polybutadiene block copolymer.
In addition, (1) the flame stabilizer containing the polystyrene-brominated polybutadiene block copolymer is blended with the above (3) heat stabilizer and melt kneaded to obtain a flame retardant melt kneaded product. It is preferred to feed the product to an extruder.
By supplying to the extruder as a flame retardant melt-kneaded product, discoloration and black spots of the extruded foam during extrusion, or discoloration and black spots of the recycled raw material when the extruded foam is melted and regenerated are more effective. Can be suppressed. The resin temperature at the time of melt-kneading the brominated flame retardant and the heat stabilizer is approximately 200 ° C. or less, preferably 190 ° C. or less. The lower limit of the resin temperature at the time of melt kneading is not particularly limited, but in order to stably knead the brominated flame retardant and the heat stabilizer, it is preferably about 140 ° C. or higher, preferably 150 ° C. or higher. It is preferable that

  The epoxy 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 phosphorus 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'- Tylene bis (4,6-di-t-butyl-1-phenyloxy) (2-ethylhexyloxy) phosphorus, mono (dinonylphenyl) mono-p-nonylphenyl phosphite, tris (monononylphenyl) phosphite, tetra Alkyl (C = 12-16) -4,4′-isopropylidene- (bisphenyl) diphosphite, hexatridecyl-1,1,3-tris (3-tert-butyl-6-methyl-4oxyphenyl)- 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 hindered phenol stabilizer include 2,6-di-t-butyl-p-cresol, triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate. ], Tetrakis- [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 2,2-methylenebis (4-methyl-6-tert-butylphenol), 1,6- Hexanediol-bis [3- (3,5-di-tert-butyl-4-droxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ] Etc. are 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-butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) -1,2,3,4-butanetetracarboxylate 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 is effective because it accelerates the extinction of flame retardancy and does not decrease the heat resistance of the extruded foam. , 4-butanetetracarboxylate or bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate is preferred.

  In the production method of the present invention, in addition to the flame retardant, a foam adjusting agent can be added to the foamable molten resin composition in order to adjust the average cell diameter of the extruded foam. Examples of the air conditioner include inorganic substances such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, aluminum oxide, bentonite, and diatomaceous earth. Further, in the present invention, two or more kinds of the air bubble adjusting agents can be used in combination. Among the various bubble regulators, talc is preferably used because it is easy to adjust the bubble diameter of the 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 antioxidants, fillers and lubricants can be appropriately added. In addition, you may add various additives, such as the said flame retardant, a bubble regulator, and a coloring agent, as a masterbatch which uses thermoplastic resins, such as a polystyrene, as a base material.

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

  In the polystyrene resin extruded foam produced by the method of the present invention, the average cell diameter in the thickness direction is 0.8 mm or less, and more preferably 0.5 mm or less in order to obtain a foam having higher heat insulating properties. preferable. 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, particularly preferably 0.07 mm or more.

  The method for measuring 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.

  In the present invention, the recycled polystyrene resin composition obtained by heating and melting the extruded foam is heated and kneaded in an extruder together with the virgin raw material polystyrene resin and a flame retardant, and the foaming agent is further extruded. An extruded foam can be produced by extruding and foaming a foamable molten resin composition obtained by press-fitting into a machine and kneading. The extruded foam of the present invention is produced using the flame retardants (1) and (2), and has excellent thermal stability during extrusion. The resin composition) has a low molecular weight reduction and yellowing at the time of recovery. Therefore, the extruded foam can be produced at low cost by using the recovered raw material. The regenerated polystyrene-based resin composition can be obtained by crushing and pulverizing the extruded foam or by cutting and kneading cutting chips generated when producing the extruded foam by an extruder. From the viewpoint of properties, it is preferably pelletized. In addition, it is preferable that the resin temperature at the time of melt kneading is equal to or higher than a temperature at which the polystyrene resin constituting the foam can be extruded and does not cause deterioration of the resin molecules, for example, 200 to 230 ° C.

  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 extruded foam plates of Examples and Comparative Examples, 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 provided with an additional shaping device (guider) was used.

[Polystyrene resin]
(I) PS1: Polystyrene (weight average molecular weight 270,000)
(Ii) RPS1: Recycled polystyrene resin composition The polystyrene resin extruded foam plate obtained in Example 1 was crushed, and the crushed material was 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).

[Flame retardants]
As the brominated flame retardant, those shown in Table 1 below were used. The bromine content in the table is a value measured according to JIS K7392: 2009.

[Heat stabilizer]
(I) Novolac type epoxy stabilizer: manufactured by DIC, trade name “EPICLON N680” (ii) phosphorus stabilizer: manufactured by ADEKA, trade name “PEP36” (bis (2,6-di-t-butyl-4- Methylphenyl) pentaerythritol-diphosphite)
(Iii) Hindered phenol stabilizer: manufactured by BASF, trade name “Irganox 1010” (pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate])

[Flame retardant aid]
As the flame retardant aid, those shown in Table 2 below were used.

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

Example 1
(Manufacture of polystyrene resin extruded foam)
In the first extruder, the novolac-type epoxy stabilizer was added to 100 parts by weight of the polystyrene resin (PS1), the brominated flame retardant A, and the brominated flame retardant A described above so as to have the blending amounts shown in Table 3. 10 parts by weight, 5 parts by weight of a phosphorus stabilizer, 5 parts by weight of a hindered phenol stabilizer, a flame retardant comprising a flame retardant aid a, and a bubble regulator (talc) are supplied, and 220 ° C. in the first extruder. These were kneaded, and the required amount of the physical foaming agent having the composition shown in Table 3 was supplied from the physical foaming agent inlet provided near the tip of the first extruder.
The brominated flame retardant A, novolac epoxy stabilizer, phosphorus stabilizer, hindered phenol thermal stabilizer are supplied to a twin screw extruder (inner diameter 20 mm, L / D = 48), Flame retardant melt-kneaded material prepared by adjusting the temperature so that the maximum temperature of the melt-kneading part is 190 ° C. and the resin temperature during extrusion is 175 ° C., extruding into a strand at a discharge of 10 kg / hr, and cutting into a pellet 1 was supplied to the extruder.

  Then, the foamable molten resin composition further kneaded in the first extruder is supplied to the subsequent second extruder, and the resin temperature is expressed as the foaming suitable temperature as shown in Table 3 (in Table 3, the foamed resin temperature is indicated). (This foamed resin temperature is the temperature of the foamable molten resin composition measured at the position of the joint between the extruder and the die), and is parallel in a gap of 50 mm from the die lip at a discharge rate of 70 kg / hr. It was extruded into a placed guider and passed through the guider while being foamed to form (shape) into a plate shape to produce a polystyrene resin extruded foam.

  Table 3 shows the apparent density, thickness, closed cell ratio, thickness direction average cell diameter, flame retardancy, weight average molecular weight, weight average molecular weight of regenerated resin, and colorability of the polystyrene resin extruded foam obtained in Example 1. Shown in

(Examples 2 to 6)
Extruded polystyrene resin foams of Examples 2 to 6 were produced in the same manner as in Example 1 except that the brominated flame retardant and flame retardant aid were changed to the ratios shown in Table 3. The brominated flame retardant A was supplied to the extruder as the flame retardant melt kneaded material 1, and the brominated flame retardant B was supplied to the extruder as it was.
The apparent density, thickness, closed cell ratio, thickness direction average cell diameter, flame retardancy, weight average molecular weight, weight average molecular weight of recycled resin, and colorability of the polystyrene resin extruded foams obtained in Examples 2-6 Table 3 shows.

(Example 7)
In addition to the polystyrene resin PS1, a recycled polystyrene resin RPS1 was used, and the polystyrene series of Example 7 was used in the same manner as in Example 1 except that the brominated flame retardant and flame retardant aid were changed to the ratios shown in Table 3. A resin extruded foam was produced. In addition, the addition amount of a brominated flame retardant, a flame retardant adjuvant, and a bubble regulator is a value with respect to 100 weight part of polystyrene resin "PS1".
Table 3 shows the apparent density, thickness, closed cell ratio, thickness direction average cell diameter, flame retardancy, weight average molecular weight, weight average molecular weight of regenerated resin, and colorability of the polystyrene resin extruded foam obtained in Example 7. Shown in

(Comparative Example 1)
A polystyrene resin extruded foam of Comparative Example 1 was produced in the same manner as in Example 1 except that the flame retardant aid a was not used.
Table 4 shows the apparent density, thickness, closed cell ratio, thickness direction average cell diameter, flame retardancy, weight average molecular weight, weight average molecular weight of regenerated resin, and colorability of the polystyrene resin extruded foam obtained in Comparative Example 1. Shown in

(Comparative Example 2)
A polystyrene resin extruded foam of Comparative Example 2 was produced in the same manner as Comparative Example 1, except that the amount of brominated flame retardant A added was changed to the ratio shown in Table 4.
Table 4 shows the apparent density, thickness, closed cell ratio, thickness direction average cell diameter, flame retardancy, weight average molecular weight, weight average molecular weight of recycled resin, and colorability of the polystyrene resin extruded foam obtained in Comparative Example 2. Shown in

(Comparative Example 3)
In Comparative Example 3, a polystyrene resin extruded foam of Comparative Example 3 was produced in the same manner as Comparative Example 1 except that the flame retardant aid b in the ratio shown in Table 4 was added.
Table 4 shows the apparent density, thickness, closed cell ratio, thickness direction average cell diameter, flame retardancy, weight average molecular weight, weight average molecular weight of recycled resin, and colorability of the polystyrene resin extruded foam obtained in Comparative Example 3. Shown in

(Comparative Example 4)
In Comparative Example 4, a polystyrene resin extruded foam of Comparative Example 4 was produced in the same manner as Comparative Example 1, except that the flame retardant aid b in the ratio shown in Table 4 was added.
Table 4 shows the apparent density, thickness, closed cell ratio, thickness direction average cell diameter, flame retardancy, weight average molecular weight, weight average molecular weight of recycled resin, and colorability of the polystyrene resin extruded foam obtained in Comparative Example 4. Shown in

The measurement methods and evaluation methods for various physical properties of the extruded foams shown in Tables 3 to 4 are as follows.

(Apparent density)
The apparent density of the extruded foam was determined as follows. A 50 × 50 × 40 mm rectangular parallelepiped sample was cut from the widthwise central portion and both end portions of the obtained extruded foam, and the weight was measured. By dividing the weight by the volume, the appearance of each sample was obtained. The density was determined, 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 )

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

(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%.

(Weight average molecular weight of extruded foam, weight average molecular weight of recycled resin)
The weight average molecular weights of the foams obtained in the respective examples and those obtained by melting and re-pelletizing the foams with a recycle extruder 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.

(Colorability)
The yellowing degree of the recycled resin was evaluated according to the following criteria. First, using a heat press machine heated to 180 ° C., the recycled resin was pressed to prepare a plate-shaped test piece of length × width × thickness = 40 × 40 × 2 mm. Evaluation was performed by measuring the YI value (yellow index) of the test piece by a reflection method based on ASTM D1925 using a spectroscopic color difference meter (SE-2000 manufactured by Nippon Denshoku Industries Co., Ltd.) (n = 3).
A: YI value is less than 10 B: YI value is 10-15
X: YI value exceeds 15

  The results of Examples 1 to 7 show that according to the method of the present invention, even if a small amount of the brominated flame retardant is blended, the combustion test according to the standard of JIS A9511 is very good and a sufficient oxygen index ( Specifically, a foam having a LOI value of 26.5 to 27.0%) can be obtained, and this foam is excellent in thermal stability during extrusion processing, and is a polystyrene resin as a base resin. This indicates that this is a polystyrene resin extruded foam with excellent recycling characteristics, in which molecular weight reduction and discoloration due to decomposition are suppressed.

  Comparative Example 1 is contrasted with Examples 1-7 and is an example in which flame retardant aid a is not used. In Comparative Example 1, the color of the recycled resin is as small as ◯, the combustion test according to JIS standards is extremely poor (specifically 5.7), and the oxygen index is low (specifically 24.5%). And cannot have high flame retardancy.

  The comparative example 2 is contrasted with Examples 1-7, Comprising: It is the example which increased the usage-amount of the brominated flame retardant of the comparative example 1. FIG. In Comparative Example 2, the combustion test according to the JIS standard is improved (specifically, 2.0 seconds), the oxygen index is insufficient (specifically 25.5%), and the color of the recycled resin is further increased. The property is extremely poor as x and cannot have high thermal stability.

  Comparative Example 3 is to be compared with Examples 1 to 7, and instead of the flame retardant aid a (poly (1,4-diisopropylbenzene)) used in Examples 1 to 7, the flame retardant aid. This is an example using b (2,3-dimethyl-2,3-diphenylbutane). In Comparative Example 3, although the colorability of the recycled resin is as small as ◯, the combustion test according to JIS standards is extremely poor (specifically 3.5 seconds) and the oxygen index is low (specifically 25.0). %) And cannot have high flame retardancy.

Comparative Example 4 is contrasted with Examples 1-7, and is replaced with flame retardant aid a (poly (1,4-diisopropylbenzene)) used in Examples 1-7. This is an example using b (2,3-dimethyl-2,3-diphenylbutane). In Comparative Example 4, the combustion test according to the standard of JIS A9511 is good and has a sufficient oxygen index, but the colorability of the recycled resin is very poor as x, and it has high thermal stability. Can not.

Claims (7)

In a method for producing an extruded foam by extruding a foamable molten resin composition obtained by supplying a polystyrene-based resin, a flame retardant and a foaming agent to an extruder, and kneading these with an extruder.
A flame retardant contains (1) a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene), a polystyrene resin extruded foam, Manufacturing method.   (1) The weight ratio of a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene) is 100: 1 to 100: 20. The manufacturing method of the polystyrene-type resin extrusion foam of Claim 1.   (1) The addition amount of a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer is 1 part by weight or more and less than 3 parts by weight with respect to 100 parts by weight of a polystyrene resin. Or the manufacturing method of the polystyrene-type resin extrusion foam of 2.   The flame retardant further comprises (3) at least one heat stabilizer selected from an epoxy heat stabilizer, a phosphorus heat stabilizer, a hindered phenol heat stabilizer, and a hindered amine heat stabilizer. The manufacturing method of the polystyrene-type resin extrusion foam in any one of Claims 1-3.   5. A melt-kneaded product obtained by blending (3) a thermal stabilizer with a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer is supplied to an extruder. The manufacturing method of the polystyrene-type resin extrusion foam as described in 1 above.   The blowing agent is (A) 10 to 80 mol% of a saturated aliphatic hydrocarbon having 3 to 5 carbon atoms, and (B) methyl chloride, ethyl chloride, dimethyl ether, diethyl ether, ethyl methyl ether, methanol, ethanol, water, and 90 to 20 mol% of one or more blowing agents selected from carbon dioxide (however, the total amount of the blowing agent (A) and the blowing agent (B) is 100 mol%). The manufacturing method of the polystyrene-type resin extrusion foam in any one of Claims 1-5. (1) Recycled polystyrene obtained by heating and melting a polystyrene resin extruded foam containing a brominated flame retardant containing a polystyrene-brominated polybutadiene block copolymer and (2) poly (1,4-diisopropylbenzene) The method for producing a polystyrene-based resin extruded foam according to any one of claims 1 to 6, wherein the resin-based resin composition is further supplied to an extruder.