JP6478860B2 - Production method of polystyrene resin foam board - Google Patents

Description

  The present invention relates to a method for producing a polystyrene-based fat foam plate, and in particular, a polystyrene-based fat foam plate that can be used as a foam heat-insulating plate that can be suitably used as a heat-insulating material such as a wall, floor, or roof of a building. The present invention relates to a method for producing a polystyrene-based foamed foam plate that can be stably produced over a wide apparent density range using a physical foaming agent having excellent environmental compatibility.

  A polystyrene-based fat foam board (hereinafter, also simply referred to as “foam board”) is widely used as a heat insulating material and the like because it has excellent heat insulation and mechanical strength. Such a plate-like foam plate is generally obtained by extruding a foamable molten resin kneaded product obtained by heat-melting a polystyrene resin in an extruder and then pressing and kneading a physical foaming agent into the obtained melt. It is manufactured by extruding and foaming from a flat die attached to the tip to a low pressure region and forming it into a plate shape with a forming tool.

  A chlorofluorocarbon (CFC) such as dichlorodifluoromethane has been used as a physical foaming agent used in the production of a polystyrene resin foam board. While CFC was excellent in foaming property, CFC used as a foaming agent remained in the foamed plate for a long time, and contributed to the reduction of the thermal conductivity of the foamed plate. However, since CFC has a high risk of destroying the ozone layer, saturated hydrocarbons with 3 to 6 carbon atoms represented by butane, which have an ozone depletion coefficient of 0 (zero) and a small global warming potential, are also present. , Instead of CFC.

  However, saturated hydrocarbons such as butane remain in the foamed plate and contribute to the reduction of thermal conductivity, but have the property of being easily combusted, so that the amount used as a foaming agent is limited.

  Therefore, in order to produce a foam plate with a high foaming ratio, it is easy to dissipate quickly from the foam plate, and as a physical foaming agent excellent in environmental compatibility, ether, aliphatic alcohol, water, carbon dioxide, etc. It has been proposed to use in combination with saturated hydrocarbons (for example, Patent Documents 1 to 6).

  Specifically, Patent Documents 1 and 2 describe the use of a specific ratio of a saturated hydrocarbon having 3 to 5 carbon atoms and an ether such as dimethyl ether as a foaming agent. Patent Document 3 describes that a specific ratio of a saturated hydrocarbon having 3 to 5 carbon atoms and an ether such as dimethyl ether are used as a foaming agent, and a specific amount of carbon dioxide is used as a foaming aid.

  Here, dimethyl ether is an easily dissipative physical foaming agent with excellent foaming properties, but because it is extremely flammable, there is a risk of causing static ignition to dimethyl ether dissipating from the foam plate during manufacturing. There was a problem in terms of safety.

  As a technique for reducing the amount of dimethyl ether used, Patent Document 4 describes that three types of blowing agents, isobutane, dimethyl ether and carbon dioxide, are used at a specific ratio as a blowing agent. Patent Document 5 describes that three types of foaming agents of isobutane, carbon dioxide, and ethanol are used as the foaming agent, and carbon dioxide and ethanol are in a specific ratio. Furthermore, in Patent Document 6, four types of blowing agents of saturated hydrocarbons having 3 to 5 carbon atoms, aliphatic alcohols having 1 to 4 carbon atoms, ethers, and carbon dioxide are used at a specific ratio as blowing agents. Is described.

Japanese Patent Laid-Open No. 11-158317 International Publication No. 99/054390 JP 2001-323097 A JP 2003-12848 A JP 2004-43681 A JP 2006-188654 A

  However, in the case of the production methods of Patent Documents 4 to 6, it is difficult to produce a foamed plate having a certain foaming ratio or more, and there is a problem that the production stability is particularly insufficient when producing a thick foamed plate. .

  The present invention has been made in view of the circumstances as described above, and by using a foaming agent having excellent environmental compatibility, it is possible to stably produce a foamed plate having excellent flame retardancy and good appearance. An object is to provide a method for producing a polystyrene-based resin foam plate.

The method for producing a polystyrene-based resin foam plate of the present invention includes a step of extruding a foamable molten resin composition obtained by kneading a polystyrene-based resin, a physical foaming agent, and a flame retardant, and forming it into a plate shape. A method for producing a 40 kg / m ³ polystyrene resin foam board,
As the physical foaming agent, a foaming agent containing a hydrocarbon compound having 3 to 6 carbon atoms, dimethyl ether, carbon dioxide and an ethanol aqueous solution is used, and the total blending amount of the physical foaming agent is 1.0 to 1 kg of polystyrene resin. 2.0 mol,
The compounding quantity of a C3-C6 hydrocarbon compound is 0.4-0.8 mol with respect to 1 kg of polystyrene-type resins,
The blending amount of dimethyl ether is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin,
The compounding amount of carbon dioxide is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin,
The blending amount of the ethanol aqueous solution is 0.1 to 0.5 mol with respect to 1 kg of the polystyrene resin, and the molar ratio of ethanol to water (ethanol: water) in the ethanol aqueous solution is 0.1: 1 to 0. .6: 1
It is characterized by that.

  In this method for producing a polystyrene-based resin foam plate, the molar ratio of the hydrocarbon compound having 3 to 6 carbon atoms and dimethyl ether (hydrocarbon compound: dimethyl ether) is preferably 1.5: 1 to 4: 1.

  In this method for producing a polystyrene resin foam plate, the flame retardant preferably contains a brominated butadiene-styrene copolymer.

In this method for producing a polystyrene resin foam plate, the polystyrene resin foam plate preferably has a width of 900 mm or more, a thickness of more than 80 mm, and a cross-sectional area of the vertical cross section in the extrusion direction of more than 800 cm ² .

The method for producing a polystyrene-based resin foam plate of the present invention is a foam plate having excellent flame retardancy and good appearance over a range of apparent density of 20 to 40 kg / m ³ using a foaming agent having excellent environmental compatibility. It can be manufactured stably.

  Hereinafter, the manufacturing method of the polystyrene-type resin foam board of this invention is demonstrated in detail.

The method for producing a polystyrene-based resin foam plate of the present invention includes a step of extruding a foamable molten resin composition obtained by kneading a polystyrene-based resin, a physical foaming agent and a flame retardant, and molding the foamed resin composition into a plate shape. A 40 kg / m ³ polystyrene resin foam board is produced.

  Specifically, in the method for producing a polystyrene-based resin foam plate of the present invention, for example, a polystyrene-based resin, a flame retardant, and an additive such as a bubble adjusting agent blended as necessary are supplied to an extruder. Then, the mixture is heated and kneaded, and a physical foaming agent is injected and kneaded, and then cooled to a suitable foaming temperature to obtain a foamable molten resin composition. Then, this foamable molten resin composition is extruded through a flat die into a low pressure region and foamed, and formed into a plate shape (shaped). The plate-shaped shaping can be performed, for example, by passing a molding tool that forms a pair of upper and lower plate-shaped foam molding spaces disposed downstream of the die and a molding tool such as a molding roll.

  Examples of polystyrene resins include polystyrene and styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers, styrene-methyl methacrylate copolymers, and styrene-methacrylic acid containing 50 mol% or more of styrene unit components. Ethyl copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-polyphenylene ether copolymer, styrene-acrylonitrile copolymer, styrene-methylstyrene copolymer One type or two or more types among polymers, styrene-dimethylstyrene copolymers, styrene-ethylstyrene copolymers, styrene-diethylstyrene copolymers, and the like can be exemplified. Of these, polystyrene is preferably used. In addition to the styrene unit component, the polystyrene may contain a unit component by a branching agent such as a polyfunctional monomer or a polyfunctional macromonomer.

  The polystyrene resin may contain other polymers as long as the object and effect of the present invention are achieved. Other polymers include 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. Resin (one or a mixture of two or more selected from the group of propylene homopolymer and propylene copolymer having a propylene unit component content of 50 mol% or more), polyphenylene ether resin, polymethyl methacrylate Styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer hydrogenated product, styrene-isoprene-styrene block copolymer water Additives, thermoplastic elastomers such as styrene-ethylene copolymers, etc. It is below. These other polymers are mixed according to the purpose so as to be less than 50% by weight in the polystyrene resin, preferably 30% by weight or less, and more preferably 10% by weight or less. can do.

  Moreover, in order to improve the heat insulation of a foamed board, what contains an amorphous polyethylene terephthalate type-copolymer can be used as a polystyrene-type resin. In this case, the amorphous polyethylene terephthalate resin is preferably blended in the polystyrene resin so as to be 5% by mass or more and less than 50% by mass.

Further, from the viewpoint of foamability and moldability, it is preferable to use a polystyrene resin having a melt viscosity (under conditions of 200 ° C. and a shear rate of 100 sec ⁻¹ ) of about 500 to 2500 Pa · s, more preferably. 600 to 2000 Pa · s, more preferably 700 to 1500 Pa · s.

  As the physical foaming agent, those containing four kinds of hydrocarbon compounds having 3 to 6 carbon atoms, dimethyl ether, carbon dioxide and ethanol aqueous solution are used. These four types of physical foaming agents have an ozone depletion coefficient of 0, a low global warming coefficient, and are friendly to the global environment.

  In addition, the physical foaming agent does not need to be comprised only from said 4 types of physical foaming agents, and may contain a small amount of other physical foaming agents in the range which does not inhibit the objective of this invention. However, the proportion of the four types of physical foaming agents is preferably 90 mol% or more, more preferably 95 mol% or more, and still more preferably 100 mol% with respect to the entire physical foaming agent.

  In order to obtain a foamed plate having the apparent density, a total of 1.0 to 2.0 mol of physical foaming agent is used per 1 kg of polystyrene resin.

  Since the hydrocarbon compound having 3 to 6 carbon atoms is excellent in the balance between the solubility in the polystyrene resin and the diffusibility in the polystyrene resin, the extrusion foamability of the polystyrene resin is excellent.

  Examples of the hydrocarbon compound having 3 to 6 carbon atoms include those excluding chlorofluorocarbons as specified in JIS A9521: 2014, specifically, propane, normal butane, isobutane (2-methylpropane) , Normal pentane, isopentane (2-methylbutane), cyclobutane, neopentane (2,2-dimethylpropane), cyclopentane, normal hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3- C3-C6 saturated hydrocarbon compounds such as dimethylbutane and cyclohexane, 1-chloro-3,3,3-trifluoropropene, 1,3,3,3-tetrafluoropropene, 1,1,1 , 4,4,4-Hexafluoro-2-butene, etc., C3-C6 hydro (chloro) fluoroolefin These may be used in combination of two or more of these. In the present invention, normal butane and isobutane are collectively referred to as butane.

  And the compounding quantity of a C3-C6 hydrocarbon compound is 0.4-0.8 mol with respect to 1 kg of polystyrene-type resins. When the blending amount of the hydrocarbon compound having 3 to 6 carbon atoms is within this range, it is possible to stably ensure high flame retardancy that satisfies the flammability standard of JIS A9511: 2006R. From such a viewpoint, it is preferable that the compounding quantity of a C3-C6 hydrocarbon compound is 0.5-0.7 mol with respect to 1 kg of polystyrene resins.

  Moreover, in the manufacturing method of the polystyrene-type resin foam board of this invention, the compounding quantity of dimethyl ether is 0.1-0.5 mol with respect to 1 kg of polystyrene-type resins. And it is preferable that molar ratio (hydrocarbon compound: dimethyl ether) of dimethyl ether with respect to a C3-C6 hydrocarbon compound is 1.5: 1-4: 1. When the blending amount of dimethyl ether and the molar ratio of dimethyl ether to the hydrocarbon compound having 3 to 6 carbon atoms are within this range, the flame retardancy during production and the high flame retardance as a foamed plate are stably secured. can do. From such a viewpoint, the blending amount of dimethyl ether is preferably 0.1 to 0.4 mol with respect to 1 kg of polystyrene resin. The molar ratio of dimethyl ether to hydrocarbon compound having 3 to 6 carbon atoms (hydrocarbon compound: dimethyl ether) is more preferably 1.5: 1 to 3: 1.

  Moreover, in this invention, the compounding quantity of the carbon dioxide as a physical foaming agent is 0.1-0.5 mol with respect to 1 kg of polystyrene resins. When the blending amount of carbon dioxide is within this range, it is possible to stably ensure a high degree of flame retardancy and to improve the appearance and production stability of the foamed plate. If the amount of carbon dioxide exceeds 0.5 mol, the bubble diameter may become excessively fine during foaming, foaming may start in the die, and extrusion stability may be lost. Since there exists a possibility that it may become impossible to shape | mold in plate shape, it is difficult to manufacture a foamed board stably. From such a viewpoint, it is preferable that the compounding quantity of a carbon dioxide is 0.1-0.3 mol with respect to 1 kg of polystyrene resins.

  Furthermore, in the method for producing a polystyrene resin foam plate of the present invention, the blending amount of the ethanol aqueous solution is 0.1 to 0.5 mol with respect to 1 kg of the polystyrene resin, and the ethanol and water in the ethanol aqueous solution are mixed. The molar ratio is 0.1: 1 to 0.6: 1. Ethanol is easily available industrially and has excellent extrusion foamability. If the ethanol ratio in the aqueous ethanol solution is too high, the pressure in the die tends to decrease, and bubbles are easily destroyed when molded into a plate shape, making it difficult to stably obtain a foamed plate. . Water is excellent in foaming efficiency, but its solubility in polystyrene resin is low, so if the amount is too large, dissolution in polystyrene resin in the extruder or die becomes supersaturated, and in the foam plate Excessive bubbles are formed, resulting in poor surface smoothness. When ethanol and water are used as an aqueous ethanol solution, and the blending amount of the aqueous ethanol solution and the ratio of ethanol and water are within the above ranges, the dispersibility of water in the polystyrene resin can be further improved. It is done. Moreover, it is thought that the solubility of the carbon dioxide to a polystyrene-type resin can also be improved. Therefore, even when a foamed plate having a high expansion ratio (low apparent density) and a large cross-sectional area is obtained, the production stability is improved and a foamed plate having a good appearance can be obtained. From such a viewpoint, the blending amount of the ethanol aqueous solution is preferably 0.1 to 0.4 mol with respect to 1 kg of the polystyrene resin, and the molar ratio of ethanol to water in the ethanol aqueous solution is 0.3. : 1 to 0.6: 1 is preferable.

  The flame retardant is not particularly limited, but a brominated flame retardant can be preferably used. Brominated flame retardants include brominated butadiene polymers such as brominated butadiene-styrene copolymers, tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol- S-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-A-bis (2,3- Brominated bisphenol compounds typified by dibromopropyl ether), tetrabromobisphenol-S-bis (2,3-dibromopropyl ether), tetrabromobisphenol-F-bis (2,3-dibromopropyl ether), tris (2 , 3-Dibromopropyl) isocyanurate, mono (2 3,4-tribromobutyl) isocyanurate, di (2,3,4-tribromobutyl) isocyanurate, brominated isocyanurate represented by tris (2,3,4-tribromobutyl) isocyanurate, etc. Can be mentioned. These brominated flame retardants can be used alone or in admixture of two or more.

  In addition to these brominated flame retardants, cresyl di 2,6-xylenyl phosphate, antimony trioxide, antimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, pentabromotoluene, isocyanuric acid, triallyl isocyanurate , Nitrogen-containing cyclic compounds such as melamine cyanurate, melamine, melam, melem, silicone compounds, inorganic compounds such as boron oxide, zinc borate, zinc sulfide, phosphate esters represented by triphenyl phosphate, red phosphorus Phosphorus compounds such as ammonium polyphosphate, phosphazene, hypophosphite and the like can be used in combination. Among these flame retardants, since high flame retardancy can be imparted to the foamed plate, brominated butadiene-styrene copolymer, tetrabromobisphenol A-bis (2,3-dibromopropyl ether) (2,2-bis [ 4- (2,3-dibromopropoxy) -3,5-dibromophenyl] propane), tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether) (2,2-bis [4- ( 2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl] propane), tris (2,3-dibromopropyl) isocyanurate alone or preferably using a flame retardant containing two or more kinds, High flame retardancy can be imparted, polystyrene resin is difficult to decompose during extrusion, and stable with high expansion ratio (low apparent density). Since it is easy to obtain a foam board of the cross-sectional area, brominated butadiene - it is more preferable to use a flame retardant that includes a styrene copolymer.

  The amount of the flame retardant added is 0.1 to 10 parts by weight per 100 parts by weight of the polystyrene-based resin, in order to impart high flame retardancy to the foamed plate and to suppress a decrease in foamability and a decrease in mechanical properties. It is preferably 0.5 to 7 parts by weight, more preferably 1 to 6 parts by weight.

  In the method for producing a polystyrene resin foam plate of the present invention, a flame retardant aid may be used in combination with the brominated flame retardant for the purpose of further improving the flame retardancy of the foam plate. it can. Examples of the flame retardant aid include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3,4 -Diphenylalkanes such as diethyl-3,4-diphenylhexane, 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-ethyl-1-pentene, diphenylalkenes, poly-1,4 -One or more of polyalkylated aromatic compounds such as diisopropylbenzene can be exemplified.

  The flame retardant aid can be used in an amount of 0.01 to 1 part by weight, preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of the polystyrene resin.

  In the method for producing a polystyrene resin foam plate of the present invention, the heat insulation can be further improved by adding a heat insulation improver to the polystyrene resin foam plate. Examples of the heat insulation improver include fine powders having a radiation suppressing effect. Specifically, metal oxides such as titanium oxide, metals such as aluminum, ceramics, carbon black, graphite, infrared shielding One or more of pigments and hydrotalcites can be exemplified. The addition amount of the heat insulation improver is 0.5 to 5 parts by weight, preferably 1 to 4 parts by weight with respect to 100 parts by weight of the polystyrene resin.

  Further, in the method for producing a polystyrene resin foam plate of the present invention, a known bubble diameter expanding agent, a bubble adjusting agent, a colorant such as a pigment and a dye, a heat stabilizer, and a filling are added to the polystyrene resin as necessary. Various additives such as an agent can be appropriately blended.

  As described above, in the method for producing a polystyrene resin foam board of the present invention, the physical foaming agent blended in the foamable molten resin composition is a hydrocarbon compound having 3 to 6 carbon atoms, dimethyl ether, carbon dioxide, and an ethanol aqueous solution. And the total amount of the physical foaming agent is 1.0 to 2.0 mol with respect to 1 kg of the polystyrene resin. And the compounding quantity of a C3-C6 hydrocarbon compound is 0.4-0.8 mol with respect to 1 kg of polystyrene resins, and the compounding quantity of dimethyl ether is 0.1-0 with respect to 1 kg of polystyrene resins. The amount of carbon dioxide is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin, and the amount of aqueous ethanol solution is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin. The molar ratio of ethanol and water in the ethanol aqueous solution is 0.1: 1 to 0.6: 1.

  When the foamed plate obtained by the method for producing a polystyrene-based resin foamed plate of the present invention is used as a heat insulating plate for construction, “Measurement Method A” defined in JIS A9511 (2006R) 5 · 13 · 1. It has high flame resistance satisfying the flammability standard for the extruded polystyrene foam heat insulating plate described in 1. and can satisfy the standard of thermal conductivity defined in JIS A9511 (2006R) 4.2. .

  And since the physical foaming agent used with the manufacturing method of the polystyrene-type resin foam board of this invention is a C3-C6 hydrocarbon compound, dimethyl ether, a carbon dioxide, and ethanol aqueous solution, it is excellent in environmental compatibility. In addition, it is possible to stably produce a foam plate having a low appearance density and a good appearance even with a large cross-sectional area and excellent surface smoothness.

  Hereinafter, the physical property of the polystyrene resin foam board obtained by the manufacturing method of the polystyrene resin foam board of this invention is explained in full detail.

The apparent density of the foamed plate obtained by the production method of the present invention is 20 to 40 kg / cm ³ .

Moreover, as a foam board, a width | variety is 900 mm or more depending on a use, thickness is larger than 80 mm, and the cross-sectional area of a vertical cross section of an extrusion direction may require a size larger than 800 cm < ² >. Usually, a foam board is manufactured by producing an original plate having a size one or more times larger than a desired size, cutting the original plate, and adjusting the width and length, and sometimes the thickness. Here, if the width of the original plate largely fluctuates during manufacture and the width becomes narrower than the specified width, a foamed plate having a specified size cannot be obtained, resulting in a poor yield. In the production of the foam plate, as described above, the foaming ratio tends to be difficult as the foaming ratio is higher and the cross-sectional area is larger. According to the method for producing a polystyrene-based resin foam plate of the present invention, even when producing a foam plate having such a large thickness and a large cross-sectional area, a foam plate having a good appearance can be stably produced.

  The closed cell ratio of the foamed plate is preferably 85% or more, more preferably 90% or more, and further preferably 93% or more. The higher the closed cell ratio, the longer the hydrocarbon compound such as butane can stay in the bubbles, and the high thermal insulation performance can be maintained over a long period of time, and the foam plate has excellent mechanical strength. .

In addition, the closed cell ratio of a foam board uses the air comparison type hydrometer (for example, Toshiba Beckman Co., Ltd. make, air comparison type hydrometer, model: 930 type) according to the procedure C of ASTM-D2856-70. It can obtain | require from following formula (1) using the true volume Vx of the foam board measured. Cut samples from a total of three locations near the center of the foam plate and both ends in the width direction, using each cut sample as a measurement sample, measuring the closed cell rate for each measured sample, and calculating the 3 closed cell rate Use the average value. The cut sample is a sample that is cut from the foam plate to a size of 25 mm long × 25 mm wide × 20 mm thick and does not have a foam cover, and when the sample is thin and 20 mm in the thickness direction cannot be cut, for example, Two samples (cut samples) cut into a size of 25 mm long × 25 mm wide × 10 mm thick are stacked and measured.
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 type hydrometer (the volume of the resin constituting the cut sample of the foam plate and the total bubble volume of the closed cell portion in the cut sample Equivalent to the sum of
VA: apparent volume (cm ³ ) of the cut sample calculated from the outer dimensions of the cut sample used for measurement
W: Total weight of cut sample used for measurement (g)
ρ: Density of base resin constituting the foamed plate (g / cm ³ )
The present invention is not limited to the above embodiment.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by the Example.
<1> Apparatus and material In the Example and the comparative example, in order to obtain a foamed board, the apparatus and material shown below were used.

(Extruder)
A first extruder having an inner diameter of 150 mm and a second extruder having an inner diameter of 200 mm are connected in series, a physical foaming agent injection port is provided near the end of the first extruder, and a resin discharge having a rectangular cross section with a gap of 4 mm and a width of 400 mm is provided. The extrusion apparatus which connected the flat die | dye provided with the exit (die lip) to the exit of the 2nd extruder was used. Further, a molding apparatus (guider) constituted by a plate made of a pair of upper and lower polytetrafluoroethylene resins installed parallel to the resin outlet of the second extruder was attached.

(Polystyrene resin)
Polystyrene (GPPS, Mw = 27 × 10 ⁴ ) was used.

(Flame retardants)
Tetrabromobisphenol A-bis (2,3-dibromopropyl ether) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 40% by mass of the product name “Pyroguard SR-720”, tetrabromobisphenol A-bis (2, 3-dibromo-2-methylpropyl ether), a mixed flame retardant (Br-BPA) with a product name “Pyroguard SR-130” of 60% by mass, or a brominated butadiene-styrene block copolymer manufactured by Chemtura, product name “ "Emerald Innovation 3000" (Br-SBS) was used.

(Physical foaming agent)
Isobutane, dimethyl ether, carbon dioxide and aqueous ethanol were used.

(Other)
Talc (manufactured by Matsumura Sangyo Co., Ltd., product name “High Filler # 12”) was used as the air conditioner. Poly-1,4-diisopropylbenzene (manufactured by United Initiators, product name “CCPIB”) was used as a flame retardant aid.

<2> Examples and Comparative Examples (Examples 1 to 3)
Polystyrene, flame retardant, talc as a foam regulator, and flame retardant are supplied to the first extruder in the formulation shown in Table 1, heated to 200 ° C., kneaded, and a physical foaming agent provided in the first extruder. From the inlet, a physical foaming agent having the composition and amount shown in Table 1 was supplied. Next, the foaming agent-containing molten resin composition further kneaded in the first extruder is transferred to the subsequent second extruder, and the resin temperature is adjusted to the appropriate foaming temperature (extruded resin temperature) shown in Table 1. The foamed molten resin composition is extruded into a guider arranged in parallel at a discharge rate of 800 kg / hr, and molded into a plate shape (shaped) by passing through the guider while foaming. An original plate was prepared, and further, the width and length were adjusted by cutting the original plate to produce a rectangular parallelepiped polystyrene resin foam plate (width: 1000 mm, length: 2000 mm, thickness: 100 mm).

(Comparative Example 1)
As a physical foaming agent, an ethanol aqueous solution was not blended and ethanol (not including water) was used, and production of a foamed plate was attempted in the same manner as in Examples 1 to 3.

(Comparative Example 2)
As the physical foaming agent, an attempt was made to produce a foamed plate by the same production method as in Examples 1 to 3, except that water was not used but an aqueous ethanol solution was used.

(Comparative Example 3)
About the ethanol aqueous solution of a physical foaming agent, manufacture of the foam board was tried with the manufacturing method similar to Examples 1-3 except having raised the molar ratio of ethanol with respect to water.

(Comparative Example 4)
About the ethanol aqueous solution of a physical foaming agent, manufacture of the foam board was tried with the manufacturing method similar to Examples 1-3 except having made low the molar ratio of ethanol with respect to water.

<3> Measurement method and evaluation method (apparent density) of foamed plate
The apparent density of the foamed plate was determined as follows. Each of the obtained foamed plates is cut out of a 50 × 50 × 50 mm rectangular parallelepiped sample from the center in the width direction and the vicinity of both ends, the weight is measured, and the apparent density of each sample is calculated by dividing the weight by the volume. And the arithmetic average value thereof was regarded as the apparent density.

(Thickness)
The foamed plate was divided into five equal parts in the width direction, and the thickness of the central part in the width direction was measured. The arithmetic average value of each thickness was taken as the thickness of the foamed plate.

(Cross sectional area)
As the product of the thickness of the foam plate and the width of the foam plate, the cross-sectional area of the vertical cross section in the extrusion direction was determined. In addition, the width | variety of the foam board was calculated | required as an arithmetic average value of the width | variety of 5 places selected at random from the foam board.

(Independent bubble diameter)
The true volume Vx of the foam plate measured using an air-comparing hydrometer (for example, Toshiba Beckman Co., Ltd., air-comparing hydrometer, model: model 930) according to ASTM-D2856-70, Procedure C Was obtained from the above equation (1).

(Thermal conductivity)
The obtained foamed plate is stored in a constant temperature and humidity chamber at a temperature of 23 ° C. and a relative humidity of 50% immediately after manufacture, and after 7 days of manufacture, it conforms to the standard of thermal conductivity defined in JIS A9511 (2006R) 4.2. Measured along.

(Flame retardance evaluation)
The obtained foamed plate is stored in a constant temperature and humidity chamber immediately after manufacture at a temperature of 23 ° C. and a relative humidity of 50%, and after 7 days of manufacture, it conforms to the flammability standard defined in JIS A9511 (2006R) 5.13.1. Measured along.

(appearance)
The smoothness of the foamed plate surface was evaluated visually.
◎: Smooth surface without unevenness ○: Some unevenness is observed during long time operation ×: Surface is not smooth due to separation of foaming agent in the die

(Manufacturing stability)
The production stability at the time of extrusion was evaluated according to the following criteria based on the variation in the width of the obtained original plate (maximum value−minimum value).
(Double-circle): The fluctuation | variation of the width | variety of an original plate is 10 mm or less.
A: The fluctuation of the width of the original plate is more than 10 mm and 30 mm or less.
X: The fluctuation | variation of the width | variety of an original plate may exceed 30 mm, and may fall below a regulation width (1000 mm).

<4> Results Table 1 shows production conditions, measurement results, and evaluation results in Examples 1 to 3 and Comparative Examples 1 to 4.

  As shown in Table 1, in the foamed plates of Examples 1 to 3, the total amount of the physical foaming agent is 1.0 to 2.0 mol with respect to 1 kg of the polystyrene-based resin, and the physical foaming agent has a carbon number. The compounding amount of 3-6 hydrocarbon compounds is 0.4-0.8 mol with respect to 1 kg of polystyrene resin, and the compounding amount of dimethyl ether is 0.1-0.5 mol with respect to 1 kg of polystyrene resin. The amount of carbon dioxide is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin, the amount of ethanol aqueous solution is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin, and ethanol. The molar ratio of ethanol and water in the aqueous solution is 0.1: 1 to 0.6: 1.

  In Examples 1 to 3, it was confirmed that a foam plate having a low apparent density and a large cross-sectional area can be stably produced. The obtained foamed board was confirmed to have excellent flame retardancy, excellent surface smoothness, and good appearance.

In contrast, in Comparative Examples 1 to 4, it was confirmed that it was difficult to stably produce a foam plate having a low apparent density and a large cross-sectional area. Moreover, although the flame retardant property was ensured, the foamed board of Comparative Examples 1-4 was confirmed by the unevenness | corrugation on the surface and the external appearance was not preferable.

Claims (4)

A process for producing a polystyrene-based resin foam plate having an apparent density of 20 to 40 kg / m ³ , comprising a step of extruding a foamable molten resin composition obtained by kneading a polystyrene-based resin, a physical foaming agent and a flame retardant to form a plate shape Because
As the physical foaming agent, a foaming agent containing a hydrocarbon compound having 3 to 6 carbon atoms, dimethyl ether, carbon dioxide and an ethanol aqueous solution is used, and the total blending amount of the physical foaming agent is 1.0 to 1 kg of polystyrene resin. 2.0 mol,
The compounding quantity of a C3-C6 hydrocarbon compound is 0.4-0.8 mol with respect to 1 kg of polystyrene-type resins,
The blending amount of dimethyl ether is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin,
The compounding amount of carbon dioxide is 0.1 to 0.5 mol with respect to 1 kg of polystyrene resin,
The blending amount of the ethanol aqueous solution is 0.1 to 0.5 mol with respect to 1 kg of the polystyrene resin, and the molar ratio of ethanol to water (ethanol: water) in the ethanol aqueous solution is 0.1: 1 to 0. .6: 1
A method for producing a polystyrene-based resin foam board, wherein   2. The polystyrene-based resin foam according to claim 1, wherein a molar ratio of the hydrocarbon compound having 3 to 6 carbon atoms and dimethyl ether (hydrocarbon compound: dimethyl ether) is 1.5: 1 to 4: 1. A manufacturing method of a board.   The method for producing a polystyrene resin foam board according to claim 1 or 2, wherein the flame retardant contains a brominated butadiene-styrene copolymer. The polystyrene-based resin according to any one of claims 1 to 3, wherein the width of the polystyrene-based resin foam plate is 900 mm or more, the thickness is larger than 80 mm, and the cross-sectional area of the vertical cross section in the extrusion direction is larger than 800 cm ^2. A manufacturing method of a foam board.