JP6173038B2 - Method for producing extruded polystyrene resin foam - Google Patents

Description

  The present invention relates to a method for producing a polystyrene-based resin extruded foam, and more specifically, is a polystyrene-based resin extruded foam having excellent flame retardancy and excellent recyclability, and is used for heat insulation of building walls, floors, roofs, and the like. The present invention relates to a method for producing a polystyrene-based resin extruded foam that is suitably used for materials, tatami mats, and the like and is mainly formed in a plate shape.

  Conventionally, an air conditioner is added to a polystyrene resin material, heated and kneaded by an extruder, and then a physical foaming agent is pressed into the extruder and further kneaded. And is shaped into a plate shape by a shaping apparatus connected to the die outlet of the extruder, to obtain a high-thickness polystyrene-based extruded resin foam (hereinafter also referred to as extruded foam or foam). The method 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 (zero) (Hereinafter referred to as HFC) has been used instead of CFC. Furthermore, from the viewpoint of global warming, saturated hydrocarbons such as isobutane and isopentane having an ozone depletion coefficient of 0 (zero) and a small global warming coefficient have been used instead of HCFC and HFC. Also, water has come to be used as part of the environmentally friendly blowing agent.

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

  In the above situation, a polystyrene resin extruded foam using an excellent flame retardant other than HBCD has been studied. For example, a brominated butadiene polymer type such as a polystyrene-brominated butadiene copolymer represented by Patent Document 1 has been proposed.

  Also, a method of using a flame retardant in which a brominated butadiene homopolymer or a brominated styrene / butadiene block copolymer is blended with an alkyl phosphite and / or an epoxy compound in order to improve the thermal stability of the brominated butadiene polymer type flame retardant Has also been proposed (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. Although the thermal stability is slightly improved, when a mixed foaming agent of hydrocarbon and water is used as the foaming agent, there is a problem that foamability and moldability are poor and it is difficult to produce a desired foam.

  Therefore, even when a brominated butadiene polymer type flame retardant is used as the flame retardant and a mixed foaming agent of saturated aliphatic hydrocarbon and water is used as the foaming agent, the foamability and moldability are excellent, Although there has been a strong demand for development research on a method for producing a polystyrene-based resin extruded foam that is free from the occurrence of discoloration and discoloration and has excellent flame retardancy, no such proposal has yet been made.

  The present invention produces a polystyrene resin foam using a brominated butadiene polymer type flame retardant as a flame retardant and a mixed foaming agent of saturated hydrocarbon and water as a foaming agent in view of the state of the prior art. In addition, it has excellent foamability and moldability, prevents black spots from being generated during extrusion foaming, and suppresses discoloration due to decomposition of the flame retardant and polystyrene resin that is the base resin during extrusion, making it highly flame retardant. It is an object of the present invention to provide a method for producing a polystyrene-based resin extruded foam having properties.

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 and foaming a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant and a physical foaming agent, the physical foaming agent is saturated carbonization having 3 to 5 carbon atoms. and a hydrogen and water, the formulation of the flame retardant, a brominated butadiene polymer, the following (1) and (2) look-containing and one or more phosphite compound selected from the phosphite compound The amount is 2 to 20 parts by weight with respect to 100 parts by weight of the brominated butadiene-based polymer .
(1) Bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (2) 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite
<2> The method for producing a polystyrene resin extruded foam according to <1> , wherein the blending amount of water is 0.1 mol or more per 1 kg of the foamable molten resin composition.
<3> The polystyrene-based material according to <1> or <2> , wherein the flame retardant is a melt-kneaded material obtained by blending and kneading the phosphite-based compound with a brominated butadiene-based polymer. Manufacturing method of resin extrusion foam.

  In the present invention, when a polystyrene resin foam is produced using a foaming agent containing a saturated aliphatic hydrocarbon having 3 to 5 carbon atoms and water as a physical foaming agent, a brominated polybutadiene system is used as a flame retardant. Since a specific phosphite compound is used together with the polymer, a foam having high flame retardancy can be stably obtained in a wide density range, and the flame retardant is thermally stable during extrusion. Due to its excellent properties, it is possible to produce a polystyrene resin extruded foam that is free from discoloration due to decomposition of a flame retardant or a polystyrene resin that is a base resin, and has no appearance defects.

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. The foamable molten resin 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, and the outlet of the die [Molded in parallel or with plates made of two upper and lower polytetrafluoroethylene resins or the like installed so as to expand gently from the inlet to the outlet (hereinafter also referred to as guider)] 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.

In this invention, the composite foaming agent containing (A) C3-C5 saturated hydrocarbon and (B) water is used as a foaming agent.
(A) Examples of the saturated hydrocarbon having 3 to 5 carbon atoms include propane, n-butane, i-butane, n-pentane, i-pentane, cyclopentane, neopentane and the like.
These saturated hydrocarbons can be used alone or in admixture of two or more.
(A) Among saturated hydrocarbons, propane, n-butane, i-butane or a mixture thereof is preferable from the viewpoint of foamability. Moreover, n-butane, i-butane or a mixture thereof is preferable from the viewpoint of the heat insulating performance of the foam, and i-butane is particularly preferable.

In addition to the saturated hydrocarbon and water, organic physical foaming agents and inorganic physical foaming agents can be used as other foaming agents.
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-butyl. Examples include alcohols such as 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.
Examples of the inorganic physical foaming agent include carbon dioxide and nitrogen.
The other foaming agents described above can be used alone or in combination of two or more.

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

  In the present invention, when a brominated butadiene polymer and a specific phosphite compound are used in combination as a flame retardant, when hydrocarbon and water are used as a foaming agent, the blending amount of water is particularly a foamable molten resin. Even when the amount is 0.1 mol or more per kg of the composition, the foam can be produced stably. The upper limit of the amount of water is about 1 mol.

  In the composite foaming agent, the blending ratio of the saturated hydrocarbon is preferably 10 to 80 mol%. By using a composite foaming agent with a blending ratio within this range, it becomes possible to stably produce an extruded foam having a high expansion ratio and produce an extruded foam having excellent heat insulation and flame retardancy. This is preferable. From this viewpoint, the blending ratio of the saturated hydrocarbon is more preferably 30 to 70 mol%.

  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, as described above, a brominated polybutadiene polymer and a specific phosphite compound are used as the flame retardant.
The brominated butadiene polymer exhibits an excellent flame retardancy imparting effect when used as a flame retardant for polystyrene resins. 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, when a carbon-carbon unsaturated bond is formed in the polymer by liberation of bromine, the polymer itself or the polystyrene-based 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 blending a heat stabilizer can be considered, and a phosphite compound is mentioned as a typical heat stabilizer. The present inventors use a foaming agent containing a saturated hydrocarbon and water, and manufacture a polystyrene resin extruded foam using a flame retardant in which various phosphite compounds are blended with a brominated butadiene polymer. As a result of the experiment, when using the specific phosphite compound described above, it was surprisingly found that the generation of black spots and discoloration of the extruded foam can be effectively suppressed without impairing foamability and moldability. .
The present invention has been made based on such findings.

  In the present invention, the brominated butadiene polymer itself used as a flame retardant is a conventionally known one. For example, those disclosed in Patent Documents 1 and 2 can be used as they are.

  Generally, the brominated butadiene polymer used as a flame retardant is a weight average molecular weight of about 1,000 to 200,000, preferably 2,000 to 100,000, more preferably 5,000 to 100,000, in terms of polybutadiene. More preferably, it is produced by brominating 50,000 to 100,000 butadiene-based polymers.

The brominated butadiene polymer is preferably a block copolymer, a random copolymer or a graft copolymer containing a styrene monomer component unit from the viewpoint of compatibility with a polystyrene resin (hereinafter, These are also referred to as a polystyrene-brominated polybutadiene copolymer.), And a block copolymer of a polystyrene polymer block and a brominated polybutadiene block is more preferable.
Examples of the styrene monomer include styrene, brominated styrene, chlorinated styrene, 2-methyl styrene, 4-methyl styrene, 2,4-dimethyl styrene, α-methyl styrene and the like. Among these, Styrene, 4-methylstyrene, α-methylstyrene or a mixture thereof is preferable, and styrene is more preferable.

  From the viewpoint of imparting flame retardancy, the bromine content in the brominated butadiene-based polymer is preferably 60% by weight or more, and more preferably 63% by weight or more. The bromine content is a value measured according to JIS K7392: 2009.

Considering dispersibility in polystyrene resin, the weight average molecular weight of the brominated butadiene polymer is preferably about 100,000 to 200,000 in terms of polystyrene, 200 ° C., shear rate 100 sec ^{− 1} has a melt viscosity of about 4000 to 8000.

  In general, a polystyrene-brominated polybutadiene 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 polystyrene-brominated polybutadiene copolymer is produced, for example, by brominating a polystyrene-polybutadiene 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.
The blending amount of the brominated polybutadiene polymer is appropriately determined depending on the desired flame retardancy, but is usually blended by about 1 to 10 parts by weight with respect to 100 parts by weight of the polystyrene resin, preferably 1.5 to 7 parts by weight.

In the present invention, one or more specific phosphite compounds selected from the following (1) and (2) are used as a heat stabilizer for the brominated butadiene-based polymer.
(1) Bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (2) 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite

  These phosphite compounds do not impair foamability and moldability even when a water-containing foaming agent is used, and realize the excellent flame retardancy imparting effect of brominated butadiene-based polymers. Generation | occurrence | production and discoloration of the black spot by the butadiene-type polymer can be suppressed effectively. Among these, (2) 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite is preferable.

  The blending ratio of the phosphite compound is preferably in the range of 2 to 20 parts by weight, and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the brominated butadiene polymer.

  In the present invention, the brominated butadiene polymer and the specific phosphite compound are supplied to an extruder as a melt-kneaded product obtained by blending and kneading the phosphite compound with the brominated butadiene polymer. It is preferable to produce a polystyrene resin extruded foam. By supplying the melted and kneaded product to the extruder, it is possible to more reliably suppress the generation of black spots and discoloration of the extruded foam.

The melt processing temperature during melt-kneading is preferably as low as the resin temperature during melt-kneading in order to effectively suppress the liberation of bromine from the brominated butadiene-based polymer, and is generally 190 ° C. or less, preferably 185 ° C. or less. And On the other hand, from the above viewpoint, the lower limit of the resin temperature at the time of melt-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 as 150 degreeC or more.
In addition, the flame retardant melt-kneaded product is preferably pelletized by extruding it into a strand form from an extruder and then cutting it from the viewpoint of meterability and ease of handling.

  In the present invention, a specific phosphite compound is used as the heat stabilizer, but the other heat stabilizer is selected from a bisphenol type epoxy compound, a novolac type epoxy compound, a hindered phenol compound, and a hindered amine compound. One or more heat stabilizers can be used.

  Examples of the bisphenol type epoxy compound and the novolak type epoxy compound include F2200HM manufactured by ICL-IP, EPICLON series manufactured by DIC, Araldite ECN1280 manufactured by HUNTUMAN, and the like.

Examples of the hindered phenol thermal compound 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-hexane And diol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate].
You may use these individually or in combination of 2 or more types. Among these, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] is preferable from the viewpoint of extrusion stability and flame retardancy.

Examples of the 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 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) -1,2,3,4-butanetetracarboxylate, or bis (from the viewpoint of extrusion stability and flame retardancy 2,2,6,6-tetramethyl-4-piperidinyl) sebacate is preferred.

  In order to obtain the above melt-kneaded material efficiently and stably, in addition to the brominated butadiene polymer and the specific phosphite compound, the brominated butadiene polymer has a high plasticizing effect on the brominated butadiene polymer. As the fluidity improver that improves the fluidity of the coalescence, it is preferable to use one or more phosphorus compounds selected from phosphate esters and phosphates. The phosphorus compound does not hinder the excellent flame retardancy of the brominated butadiene polymer, and is excellent in thermal stability at the time of melt processing or extrusion processing.

  The melt flow rate (MFR) in the condition H of JIS K7210: 1990 of the melt-kneaded material blended with the fluidity improver is preferably in the range of 2 to 30 g / 10 minutes, more preferably 5 to 20 g / 10 minutes. .

  The blending amount of the fluidity improver composed of a phosphorus compound with respect to the brominated butadiene polymer is particularly within the range where the function of improving the fluidity of the melt-kneaded product is exhibited and the flame retardancy imparting effect is not hindered. Although there is no restriction | limiting, it is preferable that 3-15 mass parts is mix | blended with respect to 100 mass parts of the said brominated butadiene type polymers, and it is more preferable that 5-10 mass parts is mix | blended further. .

Specific examples of the phosphate ester include triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixyl phosphate, octyl diphenyl phosphate, cresyl diphenyl phosphate, 1,3-phenylene bis (diphenyl phosphate), 1, Aromatic phosphate esters such as 3-phenylenebis (di-2,6-xylenyl phosphate), trioctyl phosphate, tributoxyethyl phosphate, trichloroethyl phosphate, tris (2-chloropropyl) phosphate, tris (2, 3-dichloropropyl) phosphate, tris (2,3-dibromopropyl) phosphate, tris (bromochloropropyl) phosphate, bis (2,3-dibromopropyl) -2,3-dichloropropyl phosphate , Bis aliphatic phosphate esters such as (chloropropyl) monooctyl phosphate, and the like.
Specific examples of the phosphate include diammonium hydrogen phosphate and ammonium dihydrogen phosphate.
Among these, aromatic phosphate esters such as triphenyl phosphate (TPP) are preferable because handleability and effect expression are more remarkable.

  In addition to the brominated butadiene-based polymer, other flame retardants can be mixed and used as long as the objects and effects of the present invention are not impaired. 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.

  Furthermore, a mixture of the above brominated butadiene polymer and a specific phosphite compound is blended with a thermoplastic resin such as a polystyrene resin, a polyethylene resin, or a polyester resin within a range not hindering the object and effect of the present invention. can do. The blending amount is preferably 20% by weight or less in the melt-kneaded product, more preferably 10% by weight, and still more preferably 5% by weight. Moreover, you may mix | blend a coloring agent.

  In addition to the above flame retardant, the oxygen index of the foam obtained can be improved by further blending at least one flame retardant aid selected from diphenylalkane, diphenylalkene and polyalkylbenzene. The additive is preferably added in an amount of 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, based on 100 parts by weight of the flame retardant.

  Specific examples of the diphenylenyl alkane include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, and 3,4-dimethyl-3,4-diphenylhexane. 3,4-diethyl-3,4-diphenylhexane. Specific examples of diphenylalkene include 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-ethyl-1-pentene, and polyalkylenebenzene. , 4-diisopropylbenzene (CCPIB). Among these, poly-1,4-diisopropylbenzene (CCPIB) is preferable.

  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 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 extruded foam obtained by the method of 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 It is preferable that it is -150mm, and also 15-100mm.

  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, 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 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-based resin composition obtained by heating and melting the extruded foam or its mill ends and scrap is heated in an extruder together with the virgin raw material polystyrene-based resin and the flame-retardant melt-kneaded product. An extruded foam can be produced by kneading, adding a foaming agent by press-fitting into the extruder, and extruding and foaming a foamable molten resin composition obtained by kneading. The extruded foam of the present invention is produced using the flame retardant melt-kneaded product as a flame retardant, and is excellent in thermal stability during processing during extrusion. The recycled polystyrene-based resin composition) has a reduced molecular weight, a degree of coloring, and generation of black spots at the time of recovery. Therefore, the extruded foam can be produced at low cost by using the recovered raw material.

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

Examples 1-5 Comparative Examples 1-2
(Manufacture of flame retardant melt-kneaded product)
As the brominated butadiene-based polymer, those shown in Table 1 below were used, and as the phosphite-based compound shown in Table 2 below, using a twin-screw extruder (inner diameter 47 mm, L / D = 41), bromine A flame retardant having the composition shown in Table 3 by blending a phosphite compound with a fluorinated butadiene polymer, melt kneading, extruding into a strand at a discharge temperature of 60 kg / hr at a resin temperature of 180 ° C., and further cutting into pellets A melt-kneaded product was produced. In addition to the brominated butadiene polymer and the phosphite compound, the flame retardant melt-kneaded product includes a novolac epoxy compound (product name EPICLON N680, manufactured by DIC) and phenolic as other heat stabilizers. The compound (pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]: product name Irganox 1010, manufactured by BASF) is each 10 weights per 100 weight parts brominated butadiene polymer. 5 parts by weight, and 6 parts by weight of triphenyl phosphate (product name TPP, manufactured by Daihachi Chemical) as a fluidity improver was added to 100 parts by weight of the brominated butadiene polymer.

＊臭素化ＳＢＳ：ポリスチレン−臭素化ポリブタジエンブロック共重合体

* Brominated SBS: Polystyrene-brominated polybutadiene block copolymer

＊ＰＥＰ３６：ビス（２，６−ジ−ｔ−ブチル−４−メチルフェニル）ペンタエリスリトール−ジホスファイト
＊ＨＰ−１０：２，２−メチレンビス（４，６−ジ−ｔ−ブチルフェニル）オクチルホスファイト
＊Ｕｌｔｒａｎｏｘ６２６：ビス（２，４−ジ−ｔ−ブチルフェニル）ペンタエリスリトールジホスファイト
＊Ｉｒｇａｆｏｓ１６８：トリス（２，４−ジ−ｔｅｒｔ−ブチルフェニル）ホスファイト

* PEP36: bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite * HP-10: 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite * Ultranox 626: bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite * Irgafos 168: tris (2,4-di-tert-butylphenyl) phosphite

(Manufacture of polystyrene resin extruded foam)
In order to obtain the extruded foams of Examples 1 to 5 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 provided with an additional shaping device (guider) was used.

[Polystyrene resin]
Polystyrene (PS1) having a weight average molecular weight of 270,000 was used.

[Flame retardants]
As the flame retardant, the flame retardant melt kneaded material described in Table 3 above was used.

[Flame retardant aid]
As the flame retardant aid, CCPIB (poly-1,4-diisopropylbenzene) was used.

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

Example 1
In the first extruder, the above-described polystyrene resin (PS1), flame retardant (bromine butadiene polymer, phosphite heat stabilizer (PEP36)), and bubbles so as to have the blending amounts shown in Table 4 A regulator (talc) is supplied, heated to 220 ° C. in the first extruder, kneaded, and blended as shown in Table 4 from the physical foaming agent inlet provided near the tip of the first extruder. The required amount of physical blowing agent was supplied.

  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 a foaming suitable temperature as shown in Table 4 (in Table 4, 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.

Example 2
In Example 1, a polystyrene resin extruded foam was produced in the same manner as in Example 1 except that the phosphite heat stabilizer (PEP36) was replaced with the phosphite heat stabilizer (HP-10).

Example 3
In Example 2, a polystyrene resin extruded foam was produced in the same manner as in Example 2 except that the amount of the phosphite heat stabilizer (HP-10) was 0.2 parts by weight.

Example 4
In Example 2, the blending amount of brominated butadiene polymer and phosphite heat stabilizer (HP-10) was changed to that described in Table 4, and CCPIB was added as a flame retardant aid. In the same manner, a polystyrene resin extruded foam was produced.

Example 5
In Example 4, a polystyrene resin extruded foam was produced in the same manner as in Example 4 except that the amount of the phosphite heat stabilizer (HP-10) was 0.05 parts by weight.

Comparative Example 1
In Example 1, a polystyrene resin extruded foam was produced in the same manner as in Example 1 except that the phosphite heat stabilizer (PEP36) was replaced with a phosphite heat stabilizer (Ultranox 626).

Comparative Example 2
In Example 1, a polystyrene resin extruded foam was produced in the same manner as in Example 1 except that the phosphite heat stabilizer (PEP36) was replaced with a phosphite heat stabilizer (Irgafos 168).

  Production stability of Examples 1 to 5 and Comparative Examples 1 and 2, and the resin extruded foams obtained in the Examples and Comparative Examples, apparent density, thickness, closed cell ratio, thermal conductivity, flame retardancy, Table 4 shows the appearance, the occurrence of black spots, and the color tone evaluation of the foam.

  In addition, the evaluation method of manufacturing stability shown in Table 4, and the measuring method and evaluation method of various physical properties of an extruded foam are as follows.

(Manufacturing stability)
○: Extruded foam can be produced stably without problems ×: The width of the extruded foam varies, and an extruded foam cannot be obtained stably

(Apparent density)
The apparent density of the extruded foam was determined as follows. A 40.times.50.times.50 mm rectangular parallelepiped sample was cut out from the vicinity of the center in the width direction of the obtained extruded foam, the weight was measured, and the apparent density was determined by dividing the weight by the volume.

(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 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 )

(Thermal conductivity)
The thermal conductivity was measured by the following method based on the accelerated test described in ISO 11561.
A test piece having no molded skin of 200 mm × 200 mm × 10 mm was cut out from the center of the extruded foam immediately after production, and the test piece was stored in an atmosphere of 23 ° C. and 50% humidity. Ten days after production, using the test piece, based on the heat flow method described in JIS A1412-2: 1999 (one specimen, symmetrical configuration method, high temperature side 38 ° C., low temperature side 8 ° C., average temperature 23 ° C.) The thermal conductivity was measured.

(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.

(appearance)
The smoothness of the product surface was evaluated visually.
○: smooth surface without unevenness ×: surface is not smooth due to separation of foaming agent, etc.

(With or without sunspots)
In the cross section cut perpendicular to the extrusion direction of the foam obtained, the number of black spots was counted. Observation of the cross section was arbitrarily measured at five locations, and the total number was taken as the number of black spots.
○: 0 to 2 black spots x: 3 or more black spots

(Color tone of foam and color tone of recycled resin)
The color tone of the extruded foam and the color tone of the foam (recycled resin) obtained by melting and re-pelletizing the foam using a recycling extruder were evaluated.
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 color tone of the foam was visually evaluated. The color tone of the recycled resin was obtained by pressing the recycled resin using a heat press machine heated to 180 ° C. to produce a plate-like 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 color difference meter (SE-2000 manufactured by Nippon Denshoku Industries Co., Ltd.).
A: The foam is not colored (white) or slightly yellowish, but at a level that does not cause a problem in the product, and the YI value of the recycled resin is less than 10. B: The foam is Although it is not colored (white) or slightly yellowish, it is a level that does not cause a problem in the product, but the YI value of the recycled resin is 10 or more x: The foam is yellow

  The results of Examples 1 to 5 show that according to the method of the present invention, when a blowing agent containing a hydrocarbon compound having 3 to 5 carbon atoms and water is used as a physical blowing agent, a brominated polybutadiene system as a flame retardant Along with the polymer, (1) bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (PEP36) and (2) 2,2-methylenebis (4,6-di-t- From the combined use of at least one phosphite compound selected from (butylphenyl) octyl phosphite (HP-10), it can be seen that a highly flame-retardant foam can be produced stably. In addition, since the flame retardant is excellent in thermal stability during extrusion, it is possible to obtain a polystyrene resin extruded foam in which the foam coloring and black spots are suppressed, the closed cell ratio is high, and the appearance is not defective. I understand.

  In Comparative Example 1, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite (Ultranox 626) specifically disclosed in Patent Document 2 is used as the phosphite compound. In Comparative Example 1, the width of the extruded foam varies, and the extruded foam cannot be obtained stably. Moreover, although there are few black spots, the product surface was uneven, surface smoothness was lowered, and the resulting foam was discolored.

  In Comparative Example 2, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite (Irgafos 168) specifically disclosed in Patent Document 2 is used as the phosphite compound. In Comparative Example 2, although the production stability is good and a foam having an excellent appearance is obtained, black spots are generated at the time of extrusion, and the resulting foam has many black spots, and the resulting foam is obtained. The problem that the body discolored occurred.

Claims (3)

In a method for producing an extruded foam by extrusion foaming a foamable molten resin composition obtained by kneading a polystyrene resin, a flame retardant and a physical foaming agent,
The physical foaming agent contains a C3-C5 saturated hydrocarbon and water,
Flame retardant, a brominated butadiene polymer, seen including a following (1) and (2) one or more phosphite compound selected from, the amount of the phosphite compound is a brominated The manufacturing method of the polystyrene-type resin extrusion foam characterized by being 2-20 weight part with respect to 100 weight part of butadiene-type polymers .
(1) Bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (2) 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite The method for producing a polystyrene-based resin extruded foam according to claim 1, wherein the blending amount of water is 0.1 mol or more per 1 kg of the foamable molten resin composition. The polystyrene-based resin extruded foam according to claim 1 or 2, wherein the flame retardant is a melt-kneaded product obtained by blending and kneading the phosphite compound with a brominated butadiene polymer. Production method.