JP2018115295A - Method for producing polystyrene-based resin extrusion foam plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for stably obtaining a polystyrene-based resin extrusion foam plate which has a mechanical strength equivalent to or higher than that of a conventional polystyrene-based resin extrusion foam plate, even when hydrocarbon and an early dissipative foaming agent such as carbon dioxide and water are used together as foaming agents.SOLUTION: A method for producing an extrusion foam plate includes a step of extrusion-foaming a foamable molten resin composition obtained by kneading a polystyrene-based resin, a physical foaming agent and a bromine-based flame retardant, and shaping the resin composition into a plate shape, where the physical foaming agent contains one or more early dissipative foaming agents selected from the group consisting of carbon dioxide, water, dimethyl ether and ethanol and hydrocarbon having 3 or more and 5 or less carbon atoms, the polystyrene-based resin has a weight average absolute molecular weight of 100,000 or more and less than 300,000 as measured by GPC-MALS method and has a weight average value of a contraction factor of 0.90 or more and 1.0 or less, and a polystyrene-based resin B has a weight average absolute molecular weight of 300,000 or more and 450,000 or less as measured by GPC-MALS method and has a weight average value of a contraction factor of less than 0.90, when the total of the polystyrene-based resin A and the polystyrene-based resin B is 100 pts.wt., a blended amount of the polystyrene-based resin A contained in the polystyrene-based resin is 40 pts.wt. or more and 70 pts.wt. or less, and a blended amount of the polystyrene-based resin B is 30 pts.wt. or more and 60 pts.wt. or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polystyrene-based resin extruded foam plate.

  Polystyrene-based resin extruded foam plates are excellent in mechanical strength and heat insulating properties, and are used as building materials such as heat insulating materials. Moreover, in the polystyrene-type resin extrusion foamed board, the thing which provided the flame retardance by adding flame retardants, such as a bromine type flame retardant, has been proposed. As a result, a polystyrene-based resin extruded foam plate having excellent mechanical strength and heat insulating properties and excellent flame retardancy can be obtained, so that it can be used in a wider range of applications such as building materials. It has become.

  The polystyrene-based resin extruded foam plate is generally manufactured by the following manufacturing method. In the extruder, a polystyrene resin, a flame retardant and a physical foaming agent are heated and kneaded to form a foamable resin melt. Then, the foamable resin melt is extruded through a die attached to the tip of the extruder and shaped into a plate shape by a molding tool or the like to form a plate-like polystyrene resin foam. The foam shaped into this plate shape is cut into a predetermined shape and size, thereby forming a polystyrene resin extruded foam plate.

  In the method of manufacturing a polystyrene resin extruded foam plate, as a foaming agent, a fluorinated hydrocarbon having a chlorine atom such as dichlorofluoromethane, a chlorinated fluorinated hydrocarbon containing a hydrogen atom, and having a chlorine atom in the molecule. Specific fluorocarbons such as fluorinated hydrocarbons and alternative fluorocarbons have been used. However, the use of chlorofluorocarbons as a foaming agent has been a problem from an environmental point of view because these chlorofluorocarbons can cause destruction of the ozone layer and cause global warming. Therefore, in place of these chlorofluorocarbons, the use of aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, and isopentane, and alicyclic hydrocarbons such as cyclopentane as blowing agents has been studied. These hydrocarbons are suitable for extrusion foaming of polystyrene-based resins, have a permeation rate with respect to polystyrene-based resins much slower than air, and can maintain heat insulation during production over a long period of time.

  Conventionally, the use of an alkyl chloride such as methyl chloride as a foaming agent has been studied. Methyl chloride facilitates foaming of a polystyrene-based resin, and when used in combination with the above hydrocarbons, it is easy to obtain an extruded foam plate having a desired apparent density. Further, methyl chloride has a high permeation rate with respect to the polystyrene-based resin and dissipates early after the production of the foamed plate, so that the dimensions of the obtained extruded foamed plate can be stabilized at an early stage. However, methyl chloride is also desired to be replaced from the viewpoint of management.

  Based on this, as a foaming agent, instead of chlorofluorocarbons and methyl chloride, a polystyrene resin extruded foam board is manufactured by using together hydrocarbons and environmentally friendly foaming agents such as carbon dioxide and water. Was considered.

  For example, in Patent Document 1, a foaming agent such as isobutane, cyclopentane, carbon dioxide, or the like is used as a foaming agent instead of chlorofluorocarbons or alkyl chloride, and a mass average molecular weight (Mw) is 100,000 ≦ Mw ≦. A technique is disclosed in which an extruded foam plate is produced by mixing 5 mass% or more of a polystyrene resin having an Mw of 195,000 ≦ Mw ≦ 350,000 with a 180,000 polystyrene resin.

  Patent Document 2 discloses a polystyrene resin extruded foam plate by using a specific multi-branched polystyrene resin as a polystyrene resin while using hydrocarbons and water as described above as a foaming agent. A manufacturing method has been proposed.

JP-A-2005-23249 JP 2012-229276 A

  Patent Document 1 describes an extruded foam having excellent heat insulation performance by having a specific balance of compressive strength. However, in the technique of Patent Document 1, alkyl chloride is used as a conventional physical foaming agent. Compared to conventional extrusion foams, the extrusion stability of the manufactured extruded foams is low, and when the expansion ratio is increased (when the apparent density is reduced), the compressive strength tends to be low. It was difficult to obtain an extruded foam having the following mechanical strength.

  Moreover, the technique of Patent Document 2 enables production of an extruded foam plate having a low apparent density by using water, carbon dioxide, or dimethyl ether without using methyl chloride as an early dissipative foaming agent. However, the stability of extrusion is still inadequate compared to the case where conventional methyl chloride is used in combination, and the mechanical strength is lowered depending on the part even if compared with the conventional polystyrene resin extruded foam plate. The uniformity of mechanical strength tends to be inferior, and further improvements are required in these respects.

  The present invention relates to mechanical strength even when a combination of hydrocarbons and an early dissipative foaming agent such as carbon dioxide or water is used as a foaming agent, as compared with a conventional polystyrene resin extruded foam plate. It aims at providing the manufacturing method which can obtain stably the polystyrene-type resin extrusion foaming board more than equivalent.

The present invention relates to (1) a method for producing an extruded foam plate comprising a step of extrusion foaming a foamable molten resin composition obtained by kneading a polystyrene resin, a physical foaming agent and a bromine flame retardant, and forming into a plate shape. In
The physical foaming agent includes one or more kinds of early dissipative foaming agents selected from the group consisting of carbon dioxide, water, dimethyl ether and ethanol, and hydrocarbons having 3 to 5 carbon atoms,
Polystyrene resin having a weight average absolute molecular weight of 100,000 or more and less than 300,000 as measured by GPC-MALS method and a weight average value of shrinkage factor of 0.90 or more and 1.0 or less Resin A and polystyrene resin B having a weight average absolute molecular weight of 300,000 to 450,000 as measured by GPC-MALS method and a weight average value of shrinkage factor of less than 0.90 Including
When the total of the polystyrene resin A and the polystyrene resin B is 100 parts by weight, the blending amount of the polystyrene resin A contained in the polystyrene resin is 40 parts by weight or more and 70 parts by weight or less. The blending amount is 30 parts by weight or more and 60 parts by weight or less, and a method for producing a polystyrene resin extruded foam board,
(2) The addition amount of the physical foaming agent is 0.8 mol or more and 2.0 mol or less with respect to 1 kg of the polystyrene resin,
When the total amount of the physical foaming agent is 100 mol%, the physical foaming agent contains a hydrocarbon having 3 to 5 carbon atoms in a proportion of 30 to 60 mol%, as described in (1) above. Production method of polystyrene resin extruded foam plate,
(3) The polystyrene-based resin extruded foam plate has an apparent density of 20 kg / m ³ or more and 50 kg / m ³ or less and a width of 800 mm or more, and is described in (1) or (2) above. Manufacturing method of polystyrene-based resin extruded foam board,
Is the gist.

  According to the production method of the present invention, polystyrene can be used as a foaming agent in combination with hydrocarbons and one or more early dissipative foams selected from the group consisting of carbon dioxide, water, dimethyl ether and ethanol. By using a polystyrene resin having specific molecular weight characteristics as a resin, it is possible to stabilize a polystyrene resin extruded foam plate having the same or better mechanical strength as compared with a conventional polystyrene resin extruded foam plate. Can be manufactured.

  The manufacturing method of this invention is a manufacturing method of a polystyrene-type resin extrusion foamed board. This method for producing a polystyrene-based resin extruded foam plate includes a step of extrusion foaming a foamable molten resin composition and shaping it into a plate shape.

(Foaming molten resin composition)
The foamable molten resin composition is formed by kneading a polystyrene resin, a physical foaming agent and a flame retardant with an extruder. Hereinafter, in the present specification, the polystyrene resin contained in the foamable molten resin composition may be referred to as a polystyrene resin K for convenience of explanation.

(Polystyrene resin)
In the present invention, the polystyrene resin means a thermoplastic resin containing 50% by weight or more of a structural unit derived from styrene, such as polystyrene (general-purpose polystyrene: GPPS), styrene-methacrylic acid copolymer, styrene-methacrylic acid. Acid-methyl methacrylate copolymer, styrene-acrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer And impact resistant polystyrene (HIPS). In addition, the polystyrene resin may include a structural unit derived from a branching agent such as divinylbenzene or a polyfunctional macromonomer.

(Polystyrene resin K)
The polystyrene resin K is a mixture containing two types of polystyrene resins having specific molecular weights and shrinkage factors. In this specification, two types of polystyrene resins contained in the polystyrene resin K are referred to as a polystyrene resin A and a polystyrene resin B.

(Polystyrene resin A)
Polystyrene resin A has a weight average absolute molecular weight of 100,000 or more and less than 300,000 as measured by GPC-MALS method, and a weight average value of shrinkage factor of 0.90 or more and 1.0 or less. Have

  When the polystyrene-based resin A has a weight average absolute molecular weight in the range of 100,000 or more and 300,000 or less, the fluidity of the polystyrene-based resin K can be appropriately increased. In view of this effect, the polystyrene-based resin A preferably has a weight average absolute molecular weight of 150,000 to 290,000, and more preferably 180,000 to 280,000.

  The weight average value of the shrinkage factor of the polystyrene resin A is in the range of 0.90 to 1.0. A shrinkage factor of 0.90 or more and 1.0 or less means that the polystyrene resin A does not have a branched structure, or even if it has a branched structure, there are few branches. Examples of such polystyrene resin A include commercially available general-purpose polystyrene, recycled raw materials for polystyrene resin foam particles used in fish boxes, and recycled raw materials for polystyrene resin extruded foam plates. Can be used. The lower limit of the weight average value of the shrinkage factor of the polystyrene resin A is preferably 0.92, and more preferably 0.95. Recycled raw materials refer to products that have been processed so that used products and waste generated from the manufacturing process can be collected and used as raw materials for new products.

(Polystyrene resin B)
Polystyrene resin B has a weight average absolute molecular weight of 300,000 to 450,000 as measured by the GPC-MALS method and a weight average value of shrinkage factor of less than 0.90. The polystyrene resin B has a smaller shrinkage factor weight average value than the polystyrene resin A, and has a structure richer in the branched structure than the polystyrene resin A.

  In order to achieve the intended purpose of the present invention, the polystyrene-based resin B preferably has a weight average absolute molecular weight of 350,000 to 430,000.

  In addition, the weight average value of the shrinkage factor of the polystyrene resin B is preferably 0.89 or less, and more preferably 0.88 or less. The lower limit of the weight average value of the shrinkage factor is not particularly limited, but from the viewpoint of foamability, the lower limit is preferably 0.60, more preferably 0.70, and 0.80. More preferably it is.

  The polystyrene resin B satisfying the molecular weight and shrinkage factor is excellent in fluidity among the multi-branched polystyrene resins obtained by polymerizing a styrene monomer in the presence of a polyfunctional multi-branched macromonomer. Examples thereof include multi-branched polystyrene manufactured by DIC, product name “High Branch HP-600ANJ”, and the like.

(Weight average absolute molecular weight)
The weight average absolute molecular weight of the polystyrene resin A and the weight average value of the shrinkage factor are values measured by the GPC-MALS method. The GPC-MALS method is a method for specifying a molecular weight using GPC (Gel Permeation Chromatography) and MALS (Multi Angle Light Schattering). The GPC-MALS method can be carried out by a measurement system in which an apparatus for gel filtration chromatography and a multi-angle light scattering detector are combined.

  In this specification, the weight average absolute molecular weight is the true weight average molecular weight of the polymer. On the other hand, the weight average molecular weight measured by the GPC method using an ultraviolet spectrophotometer (UV) as a conventional detector is a relative weight average obtained using a linear polystyrene having a known molecular weight as a standard polymer. It is molecular weight, and is also referred to as linear PS-converted weight average molecular weight in this specification. The weight average molecular weight in terms of linear PS does not accurately represent the original molecular weight of the polymer, and if the polymer has a branched structure, the molecular weight (absolute molecular weight) is the same as long as the molecular weight is the same. The weight average molecular weight is a relatively small value compared to the weight average absolute molecular weight.

(Specification of weight average absolute molecular weight and weight average value of shrinkage factor)
The weight average absolute molecular weight Mw ′ of the polystyrene resin and the weight average value gw of the shrinkage factor are specified using GPC-MALS. The scattered light intensity generated by Rayleigh scattering by the laser beam irradiated to the sample liquid (sample liquid prepared using polystyrene resin) can be specified by MALS (multi-angle light scattering detector). Then, based on the relationship between the scattered light intensity and the scattering angle, the square value of the rotation radius (R _b ) and the absolute molecular weight of the polystyrene resin are specified. Therefore, at this time, the respective rotation radii and square values of the polystyrene resins A and B and the respective absolute molecular weights are specified. Further, the value of the square (R _l ² ) of the radius of rotation (R _l ) of the linear polystyrene used as the standard polymer is specified in the same manner as the polystyrene resins A and B using MALS.

As shown in the following formula (1), the shrinkage factor g is obtained as a ratio of the square of the rotation radius (R _b ) of polystyrene resin and the square of the rotation radius (R _l ) of linear polystyrene at the same absolute molecular weight. It is done.

The weight average value gw of the contraction factor can be specified as follows using the GPC-MALS method. An elution chromatogram of a sample solution of polystyrene resin is obtained by GPC. Then, in an arbitrary section i of the elution chromatogram, the absolute molecular weight M _i and the shrinkage factor gi of the polystyrene resin in the section _i are specified by MALS. The concentration c _i of the polystyrene resin in the section i is identified using commercially available concentration detector, or the like as appropriate.

  From these values, the weight average value gw of the shrinkage factor is obtained by the following formula (2).

  Further, the weight average absolute molecular weight Mw ′ of the polystyrene resin is determined by the following formula (3).

(Linear PS equivalent weight average molecular weight)
The linear PS-converted weight average molecular weight can be specified for each of the polystyrene resins A and B by, for example, a gel filtration chromatography method (GPC method) using linear polystyrene as a standard polymer.

(Blend amount of polystyrene resin A and polystyrene resin B)
About the compounding quantity of the polystyrene-type resin A and the polystyrene-type resin B in the polystyrene-type resin K, when the sum total of the polystyrene-type resin A and the polystyrene-type resin B is 100 weight part, the polystyrene-type resin A contained in a polystyrene-type resin. Is 40 parts by weight or more and 70 parts by weight or less, and the amount of polystyrene resin B is 30 parts by weight or more and 60 parts by weight or less. When the blending amount of the polystyrene resin B in the polystyrene resin K is in such a range, a polystyrene resin extruded foam plate having excellent mechanical strength can be stably produced. From the viewpoint of further improving this effect, when the total amount of polystyrene resin A and polystyrene resin B is 100 parts by weight, the blending amount of polystyrene resin A contained in polystyrene resin K is 45 parts by weight or more and 65 parts by weight. It is preferable that it is 35 parts by weight or more and 55 parts by weight or less of the blend amount of the polystyrene resin B.

(Physical foaming agent)
The physical foaming agent contained in the foamable molten resin composition is one or more early dissipative foaming agents selected from the group consisting of carbon dioxide, water, dimethyl ether and ethanol, and hydrocarbons having 3 to 5 carbon atoms. Is included.

(Amount of physical foaming agent added)
The addition amount of the physical foaming agent contained in the foamable molten resin composition is preferably 0.8 mol or more and 2.0 mol or less with respect to 1 kg of the polystyrene resin K. More preferably, it is 0 mol or more and 1.7 mol or less. When the addition amount of the physical foaming agent is 0.8 mol or more, the foamable molten resin composition can be foamed to a desired apparent density required for a building heat insulating material. When the addition amount of the physical foaming agent is 2.0 mol or less, it is possible to reduce the possibility of causing the appearance defect of the foam.

(Early dissipative foaming agent)
The use of one or more early dissipative foaming agents selected from the group consisting of carbon dioxide, water, dimethyl ether and ethanol as a physical foaming agent makes it possible to reduce the environmental burden and to quickly Therefore, it is possible to obtain an extruded foam plate having a low apparent density and a good appearance without impairing properties such as flame retardancy.

(C3-C5 hydrocarbons)
Examples of the hydrocarbon having 3 to 5 carbon atoms contained in the physical blowing agent include propane having 3 carbon atoms, n-butane having 4 carbon atoms, isobutane (2-methylpropane), n-pentane having 5 carbon atoms, and isopentane ( Suitable examples include saturated hydrocarbons such as 2-methylbutane), neopentane (2,2-dimethylpropane), and cyclopentane. In addition, as hydrocarbons having 3 to 5 carbon atoms, even if halogen is contained in the molecule, the ozone depletion coefficient is 0 and the global temperature coefficient is very low. Examples also include fluorinated unsaturated hydrocarbons such as tetrafluoropropene, 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. These hydrocarbons having 3 to 5 carbon atoms can be used alone or in combination of two or more. Of the hydrocarbons having 3 to 5 carbon atoms, isobutane is particularly preferable. The hydrocarbon having 3 to 5 carbon atoms has a permeation rate with respect to the polystyrene resin that is slower than air and remains in the extruded foam plate over a long period of time, and has a lower thermal conductivity than air. It has good heat insulation. In addition, the saturated hydrocarbon having 3 to 5 carbon atoms plasticizes the polystyrene resin, so that the melt viscoelasticity of the foamable molten resin composition is related to the blending ratio of the polystyrene resin A and the polystyrene resin B. Can be adjusted to a range having good foamability. Therefore, when a hydrocarbon having 3 to 5 carbon atoms is included in the physical foaming agent, an extruded foam plate having a low apparent density can be obtained relatively easily.

(Blend ratio of physical foaming agent)
When the total amount of the physical foaming agent is 100 mol%, the physical foaming agent contains hydrocarbons having 3 to 5 carbon atoms in a proportion of 30 mol% to 60 mol%, and the early dissipative blowing agent is 40 mol% or more. It is preferably contained at a ratio of 70 mol% or less. By containing the early dissipative foaming agent and the hydrocarbon having 3 or more and 5 or less carbon atoms at this ratio, it is possible to obtain an extruded foam plate having excellent heat resistance and excellent flame retardancy.

(Flame retardants)
A brominated flame retardant is blended in the foamable molten resin composition.

  Examples of brominated flame retardants include hexabromocyclododecane, tetrabromobisphenol A, tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (2-bromoethyl ether), tetra Bromobisphenol A-bis (allyl ether), tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether) ), Tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol S, tetrabromobisphenol S-bis (2,3-dibromopropyl ether), tetrabromobisphenol- -Bis (2,3-dibromo-2-methylpropyl ether), tetrabromocyclooctane, tris (2,3-dibromopropyl) isocyanurate, tribromophenol, decabromodiphenyl oxide, tris (tribromoneopentyl) phosphate N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide, pentabromotoluene, brominated polystyrene, brominated epoxy resin, brominated product of styrene-butadiene copolymer, brominated bisphenol ether derivative, etc. It is done. These compounds can be used alone or in admixture of two or more.

  The blending amount of the flame retardant is preferably at least 0.5 parts by weight per 100 parts by weight of the polystyrene resin K. The upper limit of the blending amount of the flame retardant is approximately 10 parts by weight from the viewpoint of not inhibiting the formation of bubbles during extrusion foaming and suppressing the deterioration of mechanical properties. In addition, the blending amount of the flame retardant is more preferably 1 to 9 parts by weight, and further preferably 2 to 8 parts by weight.

(Additive)
The foamable molten resin composition may contain additives in addition to the polystyrene resin K, the physical foaming agent, and the flame retardant. Examples of the additive include a bubble regulator, a heat stabilizer, a flame retardant aid, a radiation inhibitor, and a colorant.

  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. Moreover, two or more types of bubble regulators can be used in combination. In addition, it is preferable that it is 0.01-7.5 mass parts with respect to 100 mass parts of polystyrene resin K, and, as for the compounding quantity of a bubble regulator, it is more preferable that it is 0.1-5 mass parts.

  Examples of the heat stabilizer include one or more heat stabilizers selected from an epoxy compound, a phenol compound, a hindered amine compound, and a phosphite compound. In addition, it is preferable that the total compounding quantity of a heat stabilizer is 0.01-30 mass parts with respect to 100 mass parts of flame retardants.

  Examples of the flame retardant aid include at least one flame retardant aid selected from diphenylalkane, diphenylalkene, and polyalkylbenzene. By blending these, the oxygen index (minimum concentration of oxygen necessary for maintaining the combustion of the material) of the foam obtained can be improved. In addition, it is preferable that it is 1-20 mass parts with respect to 100 mass parts of flame retardants, and, as for the compounding quantity of a flame retardant adjuvant, it is more preferable that it is 2-10 mass parts.

  Examples of the radiation inhibitor include fine powders having a radiation suppression effect, specifically, metal oxides such as titanium oxide, metal powders such as aluminum powder, carbon such as carbon black and graphite, A ceramic etc. can be illustrated. These can be used alone or in combination of two or more. The addition amount of the radiation inhibitor is preferably 0.5 to 5 parts by weight, and more preferably 1 to 4 parts by weight with respect to 100 parts by weight of the polystyrene-based K resin.

(Method for producing polystyrene resin extruded foam plate)
The manufacturing method of the polystyrene-type resin extrusion foam board of this invention is implemented as follows.

  Supply polystyrene resin and flame retardant and additives such as bubble regulator, heat stabilizer, flame retardant aid, etc. to the extruder as necessary, heat and knead, and further add physical foaming agent into the extruder The foamed molten resin composition obtained by press-fitting and kneading is extruded through a die such as a flat die into a low-pressure region (usually in the atmosphere) from the inside of a high-pressure extruder and foamed, and is also placed at the die outlet Passing the mold (molding device such as a shaping device or a molding roll composed of two upper and lower polytetrafluoroethylene resins, etc. installed so as to expand gently in parallel or from the entrance to the exit) To produce a plate-shaped polystyrene resin foam (original plate), and then adjust the width and length by cutting the original plate to produce a polystyrene resin extruded foam plate To do Kill.

  Normally, cutting waste of the original plate, scrap of the original plate, etc. are pelletized and used as a raw material (recycled raw material) for manufacturing a polystyrene resin extruded foam plate.

(Polystyrene resin extruded foam plate)
Up to now, when using hydrocarbons and early dissipative foaming agents such as carbon dioxide and water without using alkyl chloride as a foaming agent, compared with conventional polystyrene resin extruded foam plates A polystyrene resin extruded foam plate having the same or better mechanical strength, heat insulation and flame retardancy has not been stably obtained. This is particularly remarkable when trying to obtain a polystyrene resin extruded foam plate having an apparent density of 20 kg / m ³ or more and 50 kg / m ³ or less and a width of 800 mm or more. Met. In this regard, according to the production method of the present invention, the following foamed polystyrene resin extruded foam plate is obtained by carrying out the extrusion foam molding method using the foamable molten resin composition configured as described above. Is formed.

That is, according to the production method of the present invention, a polystyrene resin extruded foam plate having an apparent density of 20 kg / m ³ or more and 50 kg / m ³ or less and a width of 800 mm or more is stable. Thus, it can be suitably obtained.

According to the production method of the present invention, the apparent density of the polystyrene resin extruded foam plate is 20 kg / m ³ or more and 50 kg / m ³ or less, and the width is 800 mm or more. The effect that the thing which can be used conveniently for heat insulation uses, such as a heat insulating material, and civil engineering uses, such as lightweight embankment, is acquired. In consideration of suitability for such use, it is preferable that the apparent density of the polystyrene resin extruded foam plate is 22 kg / m ³ or more and 40 kg / m ³ or less. It is preferable that the width | variety of a polystyrene-type resin extrusion foaming board is 800 mm or more and 1200 mm or less.

(Apparent density identification method)
The apparent density of the polystyrene resin extruded foam plate can be measured based on “5.6 density” described in JIS A9511: 2006R.

  According to the production method of the present invention, it is possible to obtain a polystyrene resin extruded foam plate having a closed cell ratio of 80% or more. Since the closed cell ratio of the polystyrene resin extruded foam plate is 80% or more, the polystyrene resin extruded foam plate is particularly excellent in mechanical strength and heat insulating properties, and is suitable for architectural heat insulating materials and civil engineering applications. Can be used for From this viewpoint, it is preferable that the closed cell ratio of the polystyrene-based resin extruded foam plate is 90% or more.

(Identification method of closed cell ratio)
The closed cell ratio of the extruded foam plate can be specified according to Procedure C of ASTM-D2856-70. Extrusion measured using an air comparison type hydrometer 930 type manufactured by Toshiba Beckman Co., Ltd. (measured by accommodating a cut sample cut into a size of 25 mm × 25 mm × 20 mm from the extruded foam plate in a sample cup). Using the true volume Vx of the foamed plate (cut sample), the closed cell ratio S (%) was calculated by the following formula (4). By calculating the closed cell ratio S (%) for a plurality of samples, a plurality of values can be measured as the closed cell ratio S (%) of each sample. And the closed cell rate of an extrusion foaming board can be calculated | required as an average value of those values.

However, in said Formula (4), Vx is the true volume of the extrusion foaming board (cut sample) measured by the said method, ie, the volume of the resin which comprises an extrusion foaming board (cut sample), and an extrusion foaming board The sum (cm ³ ) of the total cell volume of the closed cell portion in (cut sample), Va is the apparent volume of the extruded foam plate (cut sample) obtained from the external dimensions of the extruded foam plate (cut sample) ( cm ³ ), W is the weight (g) of the extruded foam plate (cut sample), and ρ is the density of the resin composition constituting the extruded foam plate obtained by degassing the extruded foam plate (cut sample). (G / cm ³ ).

(Properties of polystyrene resin extruded foam board)
The polystyrene-based resin extruded foam plate obtained by the production method of the present invention is mechanical strength, heat insulating properties and flame retardancy even when compared with conventional polystyrene-based resin extruded foam plates obtained using alkyl chloride as a foaming agent. Same or better. Furthermore, the polystyrene-based resin extruded foam plate obtained by the production method of the present invention has an excellent appearance.

(Mechanical strength)
The mechanical strength of the polystyrene resin extruded foam plate can be specified by compressive strength and bending strength.

(Compressive strength)
The compressive strength of the polystyrene resin extruded foam plate can be measured based on “5.9 compressive strength” described in JIS A9511: 2006R.

The polystyrene-based resin extruded foam plate obtained by the production method of the present invention preferably has a compressive strength of 10 N / cm ² or more.

(Bending strength)
The bending strength of the polystyrene resin extruded foam plate can be specified based on “5.10 bending strength” described in JIS A9511: 2006R.

The polystyrene resin extruded foam plate obtained by the production method of the present invention preferably has a bending strength of 17 N / cm ² or more.

(Thermal insulation properties)
In addition, the heat insulation of a polystyrene-type resin extrusion foamed board can be specified by thermal conductivity.

(Thermal conductivity)
The thermal conductivity can be measured according to JIS A1412-2 based on “5.7 Thermal conductivity” described in JIS A9511: 2006R.

  The polystyrene resin extruded foam plate obtained by the production method of the present invention preferably has a thermal conductivity of 0.040 W / (m · K) or less, more preferably 0.034 W / (m · K). Preferably, it is 0.028 W / (m · K).

(Flame retardance)
In the polystyrene resin extruded foam plate obtained by the production method of the present invention, the flame disappears within 3 seconds in the flammability measurement based on “5.13.1 Measurement Method A” described in JIS A9511: 2006R. It is preferable to satisfy the three conditions that there is no dust and combustion does not exceed the combustion limit indicator line.

  When the polystyrene-based resin extruded foam board satisfies the conditions of compressive strength, bending strength, flame retardancy and flame retardancy as described above, it can be used more suitably for architectural insulation materials and civil engineering applications. Become.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 and Example 2
As an apparatus for producing a polystyrene-based resin extruded foam plate, a tandem type extruder in which a second extruder (extruder having a diameter of 200 mm) is connected in series to the extrusion port side of a first extruder (extruder having a diameter of 150 mm); A shaping device formed by forming a plate made of polytetrafluoroethylene resin in parallel at a predetermined interval in the top and bottom at the tip of the die lip formed on the die attached to the extrusion port of the second extruder; A manufacturing apparatus equipped with was prepared. A die having a die lip having a discharge port width of 440 mm and a gap of 3 mm (rectangular cross section) was prepared.

  As the polystyrene resin, those shown in Table 1 (PS1 to PS6) were prepared. Polystyrene resins corresponding to the abbreviations in Table 1 are also shown in Tables 2 and 3 using the same abbreviations. In addition, brominated flame retardants and physical foaming agents shown in Tables 2 and 3 were prepared as brominated flame retardants and physical foaming agents. As the physical foaming agent, a hydrocarbon having 3 to 5 carbon atoms and an early dissipative physical foaming agent having a faster dissipation rate from the foam plate were prepared. As brominated flame retardants, 40% by weight of tetrabromobisphenol A-bis (2,3-dibromopropyl ether), 60% by weight of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), Composite flame retardant (abbreviated as BrBPA in Tables 2 and 3). In Tables 2 and 3, the numbers in the column of brominated flame retardant and bubble regulator are parts by weight with respect to 100 parts by weight of polystyrene resin K, and indicate the amount added.

  Polystyrene resin A, polystyrene resin B, brominated flame retardant and talc (manufactured by Matsumura Sangyo Co., Ltd., trade name: High Filler (trademark) # 12) shown in Table 2 are listed in Table 2. It is supplied to one extruder, heated and kneaded at a preset temperature of 220 ° C., and the physical foaming agent shown in Table 2 is press-fitted and further kneaded at the front end side of the first extruder to form a foamable resin melt. It was. The obtained foamable resin melt was gradually cooled to the foamed resin temperature shown in Table 2 in the second extruder. The foamed resin temperature was measured between the extrusion port of the second Oshida machine and the die. The foamable resin melt was extruded from the die into the atmospheric pressure, and formed into a plate shape by passing through a shaping device while advancing foaming to obtain an extruded foam plate. And the width | variety and length were adjusted by cutting a raw material, and the rectangular parallelepiped polystyrene-type resin extrusion foamed board (50 mm in thickness, width 910 mm, length 1820 mm) was obtained. Various properties were measured and evaluated for the obtained extruded foam plate. The obtained extruded foamed plate was stored in a constant temperature and humidity chamber at a temperature of 23 ° C. and a relative humidity of 50% immediately after production, and various measurements and evaluations were performed three days after the production date. Table 2 shows the results of various physical property measurements and evaluations.

  Moreover, the extruded foamed board obtained in Example 1 and the cutting scraps of the original board were melted and repelletized with an extruder for recycling to obtain a polystyrene resin (PS5 in Table 1). The re-pellet is crushed into a size that can be supplied to the extruder, and the crushed material and cutting waste of the original plate are supplied to a single-screw extruder having an inner diameter of 90 mm and L / D = 50 to a maximum temperature of 220. The melt resin was melt kneaded at 0 ° C., and the molten resin was extruded into a strand shape at a discharge rate of 250 kg / hr and cut into a pellet shape.

Example 3 to Example 8
As a combination of the polystyrene resin A and the polystyrene resin B forming the polystyrene resin K, the combinations shown in Table 2 were selected from the polystyrene resins shown in Table 1. Furthermore, extrusion foaming was performed under the conditions shown in Table 2 using a physical foaming agent, a brominated flame retardant and the like as shown in Table 2. Except for these points, a polystyrene-based resin extruded foam plate was obtained in the same manner as in Example 1. About the extrusion foaming board obtained in each Example (Examples 3 to 8), like Example 1, the extrusion foaming board obtained was manufactured at a temperature and humidity chamber of 23 ° C. and 50% relative humidity immediately after production. Various measurements and evaluations were made 3 days after the production date. Table 2 shows the results of various physical property measurements and evaluations in Examples 3 to 8.

Comparative Example 1 to Comparative Example 8 and Reference Example Instead of polystyrene resin K, polystyrene resin L shown in Table 3 was employed. As the polystyrene resin L, combinations of polystyrene resin A and polystyrene resin C shown in Table 3 in each of Comparative Examples 1 to 8 and Reference Example were selected. Here, the polystyrene resin C indicates a polystyrene resin other than the polystyrene resin A and the polystyrene resin B. In addition to the polystyrene resin L shown in Table 3, a physical foaming agent and a brominated flame retardant as shown in Table 3 were used, and extrusion foaming was performed under the conditions shown in Table 3. Except for these points, a polystyrene-based resin extruded foam plate was obtained in the same manner as in Example 1. In the reference example, methyl chloride was used as an early dissipative foaming agent. About the extrusion foam board obtained in Comparative Examples 1-8 and each of the reference examples, in the same manner as in Example 1, the extrusion foam board obtained was immediately after production in a constant temperature and humidity chamber at a temperature of 23 ° C. and a relative humidity of 50%. Various measurements and evaluations were made after 3 days of storage. Table 3 shows the results of various physical property measurements and evaluations in Comparative Examples 1 to 8 and Reference Example.

(Various physical properties measurement and evaluation methods)
With respect to the polystyrene resins in Table 1, Examples 1 to 8, Comparative Examples 1 to 8, and Reference Examples, the various physical property measurement and evaluation methods described above were performed as follows.

(Molecular weight in terms of polystyrene)
The weight average molecular weight (Mw) of the polystyrene resin was measured by gel permeation chromatography (GPC) using linear polystyrene as a standard substance. Measurement was carried out using HLC-8320GPC EcoSEC manufactured by Tosoh Corporation under the conditions of eluent: tetrahydrofuran (THF), flow rate: 0.6 ml / min, and sample concentration: 0.1 wt%. About the column, TSKguardcolumn SuperH-H * 1 and TSK-GEL SuperHM-H * 2 were connected in series and used for the measurement. Then, the styrene resin was dissolved in tetrahydrofuran (THF), and the molecular weight was measured by gel permeation chromatography (GPC). The measured value was calibrated with standard polystyrene (straight chain) to determine the weight average molecular weight (Mw) of the polystyrene resin.

(Absolute molecular weight and shrinkage factor)
The weight average absolute molecular weight (Mw ′) of the polystyrene resin was measured by GPC-MALS (multi-angle light scattering detector) method. Using a Prominence LC-20AD (2HGE) / WS system manufactured by Shimadzu Corporation, a multi-angle light scattering detector DAWN HELEOS II manufactured by Wyatt Technology, eluent: tetrahydrofuran (THF), with a flow rate of 1.0 ml / min. Measurements were performed. For the column, TSKgel HHR-H × 1 and TSKgel GMHHR × 2 manufactured by Tosoh Corporation were connected in series and used for measurement. Analysis of the measurement was performed by analysis software ASTRA of Wyatt, and thereby the weight absolute average molecular weight (Mw ′) of the polystyrene resin and the weight average value of the shrinkage factor were obtained.

(Thickness and apparent density)
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.

  The apparent density of the foamed plate was determined based on “5.6 density” described in JIS A9511: 2006R. In addition, the thickness was left as it was from a total of three places near the center and both ends in the width direction of the obtained foamed plate, and 100 mm × 100 mm rectangular parallelepiped samples were cut out to make test pieces.

(Closed cell rate)
The closed cell ratio of the extruded foam plate was measured according to the procedure C of ASTM-D2856-70 as described above.

(Thermal conductivity)
The thermal conductivity [W / (m · K)] of the extruded foamed plate was measured according to JIS A1412-2 based on “5.7 Thermal conductivity” described in JIS A9511: 2006R.

(Flame retardance)
A flammability test is performed based on “5.11 Measurement method A” described in JIS A9511: 2006R. Based on the evaluation criteria for the combustion time, residual dust, and combustion limit indicator line as shown below. The flame retardancy of the extruded foam board was evaluated.

-Combustion time ○: Within 3 seconds.
X: Over 3 seconds.

・ Residual ○: None.
X: Yes.

・ Combustion limit indication line ○: Not exceeded.
X: Exceeds

(Compressive strength and bending strength)
Three different locations in the width direction of the extruded foam plate were selected, and samples were cut from each location. As the sample cut-out position, the central portion and both end portions in the width direction of the extruded foam plate were selected. Samples cut from the center and both ends in the width direction were designated as “medium”, “end (1)”, and “end (2)”, respectively. In addition, the samples of “end (1)” and “end (2)” were cut out at a position (position according to the central portion) facing 125 mm inward with respect to the end face in the width direction of the extruded foam plate.

Using each sample, the compressive strength (N / cm ² ) was measured based on “5.9 compressive strength” described in JIS A9511: 2006R, and “5.10 bending strength described in JIS A9511: 2006R was measured. The bending strength (N / cm ² ) was measured on the basis of “S”. The compression strength is also calculated for the average value of “medium”, “end (1)”, and “end (2)” and the contrast of “medium” with respect to the average value (“medium” / average). It was.

(Appearance quality)
Ten extruded foam plates were randomly selected from the manufactured extruded foam plates. These 10 extruded foam plates were visually observed, and the number of extruded foam plates having a spot having a depth of 3 mm or more from the surface was counted. Tables 2 and 3 show the number of sheets. In addition, the appearance was evaluated based on the following criteria according to the number of sheets.

○: The number of samples having spots of 3 mm or more is 0 to 1.
Δ: The number of samples having spots of 3 mm or more is 2-3.
X: The number of samples having 3 mm or more spots is 4 to 10.

Claims (3)

In a method for producing an extruded foam plate comprising a step of extrusion foaming a foamable molten resin composition obtained by kneading a polystyrene resin, a physical foaming agent and a brominated flame retardant, and forming into a plate shape,
The physical foaming agent includes one or more kinds of early dissipative foaming agents selected from the group consisting of carbon dioxide, water, dimethyl ether and ethanol, and hydrocarbons having 3 to 5 carbon atoms,
Polystyrene resin having a weight average absolute molecular weight of 100,000 or more and less than 300,000 as measured by GPC-MALS method and a weight average value of shrinkage factor of 0.90 or more and 1.0 or less Resin A and polystyrene resin B having a weight average absolute molecular weight of 300,000 to 450,000 as measured by GPC-MALS method and a weight average value of shrinkage factor of less than 0.90 Including
When the total of the polystyrene resin A and the polystyrene resin B is 100 parts by weight, the blending amount of the polystyrene resin A contained in the polystyrene resin is 40 parts by weight or more and 70 parts by weight or less. A method for producing a polystyrene resin extruded foam board, wherein the blending amount is 30 parts by weight or more and 60 parts by weight or less. The amount of the physical foaming agent added is 0.8 mol or more and 2.0 mol or less with respect to 1 kg of the polystyrene resin,
The polystyrene according to claim 1, wherein when the total amount of the physical foaming agent is 100 mol%, the physical foaming agent contains a hydrocarbon having 3 to 5 carbon atoms in a proportion of 30 to 60 mol%. Of manufacturing a resin-based extruded foam board. The polystyrene-based resin extruded foam plate according to claim 1 or 2, wherein the polystyrene-based resin extruded foam plate has an apparent density of 20 kg / m ³ or more and 50 kg / m ³ or less and a width of 800 mm or more. A manufacturing method of a board.