JP5317781B2 - Method for producing extruded polystyrene resin foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an extruded foam body of a polystyrene-based resin, from which body a physical foaming agent is restrained from being scattered and lost and which body has low thermoconductivity, and excellent heat resistance over a long period of time. <P>SOLUTION: The method for producing the extruded foam body of the polystyrene-based resin is characterized in that a polystyrene resin (A) and a polyamide resin (B) which contains a constituent unit derived from meta-xylylene diamine, is a semicrystalline resin having the semicrystallization time of a specific value or larger or an amorphous resin, and has the melt viscosity within a specific range, are used as base material resins. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is a method for producing a polystyrene resin extruded foam, for example, a heat insulating material such as a wall, floor or roof of a building, a tatami core material, a concrete mold, and the like, and has a particularly excellent heat insulating performance. The present invention relates to a method for producing a resin extruded foam.

  Since the polystyrene-based resin extruded foam has excellent heat insulating properties and mechanical strength, those molded into a plate shape are widely used as heat insulating materials and the like. Such a foam is generally a flat die attached to the end of an extruder by foaming a melt-kneaded product obtained by kneading a polystyrene resin in an extruder and kneading the melt with a physical foaming agent. For example, it is manufactured by extrusion foaming in a low pressure region.

  Conventionally, chlorofluorocarbons (hereinafter referred to as CFC) such as dichlorodifluoromethane have been widely used as physical foaming agents used in the production of polystyrene resin extruded foams as described above. In recent years, hydrogen atom-containing chlorofluorocarbons (hereinafter referred to as HCFCs) having a small ozone depletion coefficient have been used in place of CFCs because of the high risk of destroying the ozone layer. However, since HCFC does not have an ozone depletion coefficient of 0 (zero), there is no danger of destroying the ozone layer. Therefore, it has been studied to use a fluorinated hydrocarbon (hereinafter referred to as HFC) having an ozone depletion coefficient of 0 (zero) and having no chlorine atom in the molecule as a foaming agent.

However, since this HFC has a large global warming potential, there is still room for improvement from the viewpoint of protecting the global environment. For this reason, a method for producing a polystyrene resin extruded foam using an environment-friendly foaming agent having an ozone depletion coefficient of 0 (zero) and a low global warming potential has been studied. As physical foaming agents, propane, normal butane, isobutane, normal pentane, cyclopentane, isopentane, etc. (hereinafter sometimes referred to as HC) have an ozone depletion coefficient of 0 (zero), a low global warming coefficient, From the viewpoint of the environment, it is a preferred blowing agent. At present, HC is a promising substitute for the above-mentioned chlorofluorocarbons, and its permeation rate with respect to polystyrene resin is slower than that of air. However, since HC has a relatively high permeation rate with respect to polystyrene resin as compared with chlorofluorocarbons, the thermal conductivity of the foam also increases rapidly.
Therefore, it is a difficult problem to maintain heat insulation for a long period of time in a polystyrene resin extruded foam obtained using HC as a physical foaming agent.

  On the other hand, as a gas barrier resin to a foamed sheet (Patent Document 1) formed by extruding and foaming a mixture of a polystyrene resin and a polyamide resin using a butane foaming agent, or using a foaming agent containing isobutane, There have been proposed methods (Patent Documents 2 and 3) for producing an extruded foam heat insulating board by adding a nitrile resin and a vinyl alcohol resin.

However, the foam described in Patent Document 1 is only a foam sheet for thermoforming that is molded into a container or the like, and the foam has a thin thickness and a low foaming ratio. It is difficult to obtain a foamed molded article having a high thickness and a high expansion ratio by simply mixing a polystyrene resin and a polyamide resin. In other words, the permeation rate of the physical foaming agent remaining in the foam to the polystyrene resin cannot be suppressed.
In addition, the foams described in Patent Documents 2 and 3 can dissipate from a foam of a foaming agent having a low thermal conductivity such as isobutane by mixing a nitrile resin or a vinyl alcohol resin with a polystyrene resin. Although the effect of maintaining the heat insulating property of the extruded foam by suppressing it is described, there is no description about using a mixture of a polystyrene resin and a polyamide resin as a base resin of the foam. Even if a polyamide resin is kneaded with a polystyrene resin, as described above, there is difficulty in obtaining an extruded foam having a sufficient thickness and expansion ratio that can be used as a heat insulating material. It was also difficult to achieve sufficient gas barrier properties against the foaming agent by sufficiently dispersing in the resin.

JP-A-63-142043 JP 2006-131719 A JP 2006-131757 A

  In the present invention, even when a physical foaming agent such as HC having an ozone depletion coefficient of zero or extremely low and a small global warming potential is used, the dissipation of the foaming agent from the foam is suppressed, and the thermal conductivity is small. It aims at providing the manufacturing method of the polystyrene-type resin extrusion foam which is excellent in heat insulation over a long period of time.

As a result of various studies on the above problems, the present inventors have found that a polyamide containing a structural unit derived from metaxylylenediamine is relatively excellent in kneading with a polystyrene resin, and has a physical property such as HC from a foam. The knowledge that there is a possibility of suppressing the dissipation of the foaming agent, in the extrusion foaming technology using a mixture of polystyrene resin and polyamide resin as the base resin, the crystallization start temperature of the polyamide resin is higher than the foaming temperature of the polystyrene resin The fact that the crystallization of the polyamide resin starts before the base resin is cooled to the foaming temperature in the extruder because the high crystallization speed is high has led to the deterioration of extrusion foamability. obtained, further intensive result of extensive research, port comprising a polystyrene resin, a m-xylylenediamine constituting units and dicarboxylic acid constitutional units of a specific range Include an amide, the melt viscosity by a mixture base resin with the polyamide resin is within a specific range, excellent moldability, excellent heat insulating property over a long period of time without using a chlorofluorocarbon-based blowing agents The inventors have found that a polystyrene resin extruded foam can be obtained, and have completed the present invention.

That is, the gist of the present invention is the invention described in the following (1) to ( 3 ).
(1) A method for producing an extruded foam in which a foamable molten resin containing a physical foaming agent is extruded and foamed,
The resin constituting the foamable molten resin is a mixture of a polystyrene resin (A) and a polyamide resin (B) containing 20 to 100% by weight of a polyamide having a diamine structural unit derived from metaxylylenediamine, The mixture is blended in an amount of 1 to 100 parts by weight of the resin (B) with respect to 100 parts by weight of the resin (A).
The resin (A) has a melt viscosity of 500 to 10,000 Pa · s under conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ .
The resin (B) has a melt viscosity of 1000 to 10,000 Pa · s under conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ .
Polyamide having a diamine structural unit derived from metaxylylenediamine,
70 to 100 mol% of the diamine structural unit is derived from metaxylylenediamine, and 70 to 100 mol% of the dicarboxylic acid structural unit is an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid. A method for producing a polystyrene-based resin extruded foam, which is a polyamide derived from a dicarboxylic acid having an acid molar ratio of 50:50 to 98: 2 .
(2) The mixture according to (1), wherein the resin (B) is blended at a ratio of 3 to 50 parts by weight with respect to 100 parts by weight of the resin (A). Manufacturing method of polystyrene-based resin extruded foam. ( 3 ) The polyamide resin (B) is a polyamide (b-1) having a diamine structural unit derived from metaxylylenediamine, and one or more polyamides (b-2) selected from aliphatic polyamides and amorphous polyamides The component (b-1) is 30 to 98% by weight with respect to 100% by weight of the total weight of the component (b-1) and the component (b-2). ) Or a method for producing a polystyrene resin extruded foam according to (2) .

  According to the method for producing an extruded foam of the present invention, there is no wave on the surface of the foam and the production stability at the time of extrusion foaming is made of a mixed resin in which a polyamide resin is mixed with a polystyrene resin And a polystyrene-based resin extruded foam having a sufficient thickness and good foaming ratio can be obtained. The extruded foam obtained by the production method of the present invention can suppress the dissipation of physical foaming agents such as HC from the foam because the polyamide resin is well dispersed in the polystyrene resin. Therefore, low heat conductivity is maintained over a long period of time and excellent heat insulating performance is maintained, and it is particularly useful as a heat insulating material for construction and civil engineering.

2 is a scanning transmission electron micrograph of a cross section of a bubble film of a polystyrene resin extruded foam obtained in Example 1. FIG. 3 is an enlarged cross-sectional photograph of a polystyrene resin extruded foam obtained in Comparative Example 2.

Below, the manufacturing method of a polystyrene-type resin extrusion foam is demonstrated.
In this specification, the polystyrene resin extruded foam is sometimes referred to as “extruded foam”.
[1] Method for Producing Polystyrene Resin Extruded Foam The method for producing a polystyrene resin extruded foam of the present invention is a method for producing a mixed resin extruded foam in which a foamable molten mixed resin containing a physical foaming agent is extruded and foamed. The mixed resin constituting the foamable molten mixed resin is
20 polyamides having a diamine structural unit derived from at least metaxylylenediamine per 100 parts by weight of a polystyrene resin (A) having a melt viscosity of 500 to 10,000 Pa · s under conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ 1 to 100 parts by weight of a polyamide resin (B) containing at least 100% by weight (including 100% by weight) is blended, and the polyamide resin (B) is subjected to a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ . The polyamide having a melt viscosity (η) of 1000 to 10000 Pa · s and having a diamine structural unit derived from the metaxylylenediamine has 70 to 100 mol% of the diamine structural unit derived from the metaxylylenediamine and a dicarboxylic acid. 70 to 100 mol% of the acid structural unit is an α, ω-direct carbon atom having 4 to 20 carbon atoms. The molar ratio of the aliphatic dicarboxylic acid and isophthalic acid is 50: 50 to 98: wherein the second polyamide derived from dicarboxylic acid,.

(1) About base resin The base resin of the polystyrene-based resin extruded foam includes a polystyrene-based resin (A) and a specific polyamide resin (described later) including a polyamide having a diamine structural unit derived from metaxylylenediamine ( B) is included. The total content of the polystyrene resin (A) and the polyamide resin (B) in the base resin is at least 50% by weight, preferably 70 to 100% by weight.
By using a base resin containing a polystyrene resin (A) and a polyamide resin (B), it is possible to suppress an adverse effect on the foaming of the polystyrene resin due to the crystallization of the polyamide resin (B). Since the polyamide resin (B) can be dispersed in A), the desired high gas barrier property can be achieved efficiently. The dispersion state of the polyamide resin (B) in the polystyrene resin (A) is preferably present in a stretched state in the foam film of the extruded foam, and further dispersed in layers in the foam film. It is preferable.

(I) Polystyrene resin (A)
Examples of the polystyrene resin (A) used in the present invention include a styrene homopolymer, a styrene-acrylic acid ester copolymer containing styrene as a main component, a styrene-methacrylic acid ester copolymer, and a styrene-acrylic acid copolymer. Polymer, Styrene-methacrylic acid copolymer, Styrene-maleic anhydride copolymer, Styrene-ponyphenylene ether copolymer, Styrene-butadiene copolymer, Styrene-acrylonitrile copolymer, Acrylonitrile-butadiene-styrene copolymer , Acrylonitrile-styrene acrylate copolymer, styrene-methylstyrene copolymer, styrene-dimethylstyrene copolymer, styrene-ethylstyrene copolymer, styrene-diethylstyrene copolymer, high impact polystyrene, etc. These may be used alone, or two or more thereof. In addition, the styrene component content in the styrene copolymer is preferably 50 mol% or more, and particularly preferably 80 mol% or more.
Among the polystyrene resins, styrene homopolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride. Copolymers, styrene-poniphenylene ether copolymers, styrene-acrylonitrile copolymers, and styrene-methylstyrene copolymers are preferred, and among them, styrene homopolymers, styrene-methacrylate copolymers, styrene-acrylic Acid ester copolymers are preferred.
The polystyrene resin (A) used in the present invention has a melt viscosity (η) in the range of 500 to 10000 Pa · s, more preferably 700 to 8000 Pa · s under the conditions of a temperature of 180 ° C. and a shear rate of 100 sec ^−1. It is preferable to use one having a viscosity of 1000 to 6000 Pa · s, since it is excellent in extrusion moldability when producing an extruded foam and the resulting extruded foam is excellent in mechanical strength.

(Ii) Polyamide resin (B)
The polyamide resin (B) is a polyamide resin containing at least 20% by weight (including 100% by weight) of a polyamide having a diamine structural unit derived from metaxylylenediamine, at a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ . A polyamide having a melt viscosity (η) in 1000 to 10000 Pa · s and having a diamine structural unit derived from the metaxylylenediamine,
70 to 100 mol% of the diamine structural unit is derived from metaxylylenediamine, and 70 to 100 mol% of the dicarboxylic acid structural unit is an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid. It is a polyamide derived from a dicarboxylic acid having an acid molar ratio of 50:50 to 98: 2 .
That is, since a polyamide component having a diamine structural unit derived from metaxylylenediamine having an aromatic ring is used as the polyamide resin (B), the affinity with the polystyrene resin (A) is improved. Dispersibility of (B) in the polystyrene resin (A) is improved. Furthermore, when the extrusion foaming molding the polystyrene resin (A) and the polyamide resin (B) contain a physical blowing agent, the polyamide resin (B)
70 to 100 mol% of the diamine structural unit is derived from metaxylylenediamine, and 70 to 100 mol% of the dicarboxylic acid structural unit is an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid. When 20 to 100% by weight of a polyamide having a diamine structural unit derived from metaxylylenediamine derived from a dicarboxylic acid having an acid molar ratio of 50:50 to 98: 2 is contained,
Since the degree of crystallinity of the polyamide resin (B) in the extruder and at the time of extrusion foam molding can be kept low, extrusion foam molding can be performed stably. From the above viewpoint, the polyamide resin (B) preferably has a semi-crystallization time of 1000 seconds or more, or is amorphous.
The semi-crystallization time of the polyamide resin (B) is measured at a temperature equal to or higher than the glass transition temperature of the polyamide resin (B) and lower than the melting point by constant temperature crystallization by a depolarizing intensity method.

The depolarized intensity method is a method for measuring the progress of crystallization of a resin by utilizing the phenomenon that light passing through the resin due to crystallization causes birefringence. When an amorphous or molten resin is crystallized between a pair of orthogonal polarizing plates, the amount of light transmitted through the polarizing plate increases in proportion to the degree of crystallization, so the amount of transmitted light (transmitted light intensity) is It is possible to measure with a light receiving element. The constant temperature crystallization means that an amorphous or molten resin is crystallized isothermally at an arbitrary temperature below the melting point and above the glass transition temperature (140 ° C. in the present invention). The semi-crystallization time is defined as the transmitted light intensity is (I _∞ −I ₀ ) / 2 (I ₀ is the transmitted light intensity in the amorphous state or molten state, I _∞ represents the time required to reach the transmitted light intensity when reaching a certain value, that is, the time required for crystallization to proceed halfway, and is a value that serves as an index of the crystallization speed.
The depolarization intensity method is, for example, polymer chemistry (Kobunshi Kagaku), Vol. 29, No. 323, pp. 139-143 (Mar., 1972) or polymer chemistry (Kobunshi Kagaku), Vol. 29, No. 325, pp. 336-341 (May, 1972).
The semi-crystallization time of the polyamide resin (B) in the present invention is measured by a depolarization photometric method under the conditions of a sample melting temperature: 260 ° C., a sample melting time: 5 minutes, and a crystallization bath temperature: 140 ° C. The polymer crystallization rate measuring apparatus is measured by Kotaki Seisakusho Co., Ltd., model: MK701. In the present invention, even if the time required for the transmitted light intensity to reach a certain value in the above-described method is 86400 seconds or more, it is assumed that the material is amorphous. In addition, since the foaming temperature of polystyrene-type resin is 125 to 143 degreeC, the value at the time of carrying out the constant temperature crystallization at 140 degreeC was employ | adopted for the semicrystallization time in this invention.
The measuring method of the glass transition temperature (Tg) and the melting point (Tm) in this specification is as follows.
According to JIS K7121-1987, 2-4 mg of polymer particles were used as test pieces according to the heat flux differential scanning calorimetry of JIS K7121-1987. After pre-treatment using the conditions described in Condition Adjustment (3) of the test piece (however, the cooling rate is 10 ° C./min), the sample is heated from 40 ° C. to 300 ° C. at a rate of 10 ° C./min. To obtain a DSC curve. The value obtained as the midpoint glass transition temperature of the obtained DSC curve is defined as the glass transition temperature. The peak temperature of the melting peak of the obtained DSC curve is taken as the melting point. When two or more melting peaks appear, the vertex temperature of the melting peak with the largest area is defined as the melting point.

In the polyamide (b-1) having a diamine structural unit derived from the metaxylylenediamine of the present invention, 70 mol% or more (including 100 mol%) of the diamine structural unit is derived from metaxylylenediamine, and dicarboxylic acid. 70 mol% or more (including 100 mol%) of the acid structural unit is a dicarboxylic acid having a molar ratio of α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid of 50:50 to 98: 2. It is a polyamide derived from an acid, and the molar ratio is preferably 75:25 to 97: 3, more preferably 80:20 to 96: 4.
When a structural unit derived from isophthalic acid is contained in the dicarboxylic acid structural unit, not only the barrier property of the foaming agent is improved, but also the kneading property with the polystyrene resin (A) is improved.
In addition, since the melting point of the resulting polyamide resin is lowered and the crystallization rate is delayed compared to the case of only an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, the polystyrene resin and the polyamide resin are delayed. When the extrusion foam molding is performed using the mixture as a base resin, the melt viscosity of the polyamide resin is too high, or the deterioration of the extrusion foam moldability due to the start of crystallization can be prevented.
In addition, when there are too many structural units derived from isophthalic acid in a dicarboxylic acid structural unit, there exists a possibility that the stable extrusion foaming may become difficult.

(Ii-1) Dicarboxylic acid component In the present invention, examples of the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms other than adipic acid and isophthalic acid include succinic acid, glutaric acid, pimelic acid, Examples thereof include aliphatic dicarboxylic acids such as suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid. Examples of dicarboxylic acid components other than these dicarboxylic acid components include phthalic acid compounds such as terephthalic acid and orthophthalic acid; 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1, 8-Naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarbo Acid, naphthalene dicarboxylic acid such as isomers such as 2,7-naphthalenedicarboxylic acid; monocarboxylic acid such as benzoic acid, propionic acid and butyric acid; polyvalent carboxylic acid such as trimellitic acid and pyromellitic acid; trimellitic anhydride Examples thereof include carboxylic acid anhydrides such as pyromellitic anhydride. You may use these in 30 mol% or less of the total dicarboxylic acid component.

(Ii-2) Diamine Component In the present invention, as a diamine component other than metaxylylenediamine used for the polyamide (b-1) having a diamine structural unit derived from metaxylylenediamine, tetramethylenediamine and pentamethylenediamine are used. 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethyl Aliphatic diamines such as hexamethylenediamine; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4- Minocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) decalin (including structural isomers), bis (aminomethyl) tricyclodecane (including structural isomers), etc. Examples of alicyclic diamines: diamines having an aromatic ring such as bis (4-aminophenyl) ether, paraphenylenediamine, paraxylylenediamine, and bis (aminomethyl) naphthalene (including structural isomers) be able to. These can be used in the range of 30 mol% or less in the total diamine component.

(Ii-3) Other monomer components When obtaining polyamide (b-1) having a diamine structural unit derived from metaxylylenediamine by polycondensation, ε-caprolactam, ω-lauro is added to the polycondensation reaction system. Performance of lactams such as lactam and ω-enantolactam, amino acids such as 6-aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 9-aminononanoic acid and paraaminomethylbenzoic acid You may add in the range which does not impair.

(Ii-4) Aliphatic polyamide and / or amorphous polyamide (b-2)
In the present invention, the aliphatic polyamide and / or the amorphous polyamide (b-2) includes nylon-4, nylon-6, nylon-12, nylon-66, nylon-46, nylon-610, nylon-612, It is preferable to use an aliphatic polyamide such as nylon 666 or an amorphous polyamide such as nylon-6I, nylon-6T, or nylon-6IT mixed with, for example, an extruder.
In this case, the polyamide resin (B) is preferably composed of 30 to 98% by weight of a metaxylylene group-containing polyamide and 2 to 70% by weight of an aliphatic polyamide and / or an amorphous polyamide (the total of both is 100% by weight). . More preferably, the metaxylylene group-containing polyamide 40 to 98% by weight and the aliphatic polyamide and / or the amorphous polyamide 2 to 60% by weight, and still more preferably, the metaxylylene group-containing polyamide 50 to 98% by weight and the aliphatic polyamide and / or It is 2 to 50% by weight of amorphous polyamide, particularly preferably 60 to 98% by weight of polyamide containing metaxylylene groups, and 2 to 40% by weight of aliphatic polyamide and / or amorphous polyamide. The mixing ratio of the aliphatic polyamide and the amorphous polyamide is arbitrary.

(Ii-5) Temperature 180 ° C. in the melt viscosity the polyamide resin of the polyamide resin (B) (B), the melt viscosity under the condition of shear rate of 100 sec ^-1 (eta) is a 1000~10000Pa · s, preferably 1500 to 6000 Pa · s.
When the melt viscosity of the polyamide resin (B) is too low compared to the melt viscosity of the polystyrene resin (A), the polyamide resin (B) cannot withstand the expansion force of the bubbles at the time of foaming, and the bubbles are destroyed and foamed. Stable extruded foam with high gas barrier properties, high foaming ratio and high closed cell ratio due to the formation of huge bubbles and large spaces inside the body and the loss of uniformity of the cell structure It may be difficult to obtain. On the other hand, when the melt viscosity of the polyamide resin (B) is too high compared with the melt viscosity of the polystyrene resin (A), the viscosity of the polyamide resin (B) at the time of melt kneading is compared with that of the polystyrene resin (A). Therefore, the dispersibility is lowered and the polyamide resin cannot be uniformly finely dispersed in the polystyrene resin, so that the gas barrier property of the polyamide resin is not sufficiently exhibited, and an extruded foam having high gas barrier property is obtained. It may be difficult to obtain.
In this specification, the melt viscosity is measured under the conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ , and is measured by a Capillograph 1D manufactured by Toyo Seiki Seisakusho. Specifically, a cylinder with a cylinder diameter of 9.55 mm and a length of 350 mm and an orifice with a nozzle diameter of 1.0 mm and a length of 10.0 mm were used. The polyamide resin (B) sufficiently dried at a temperature lower by 10 ° C. than the glass transition temperature is put into the cylinder and measured after standing for 4 minutes, and the melt viscosity (Pa · s) obtained there is adopted. . It is to be noted that bubbles are not mixed as much as possible into the strand extruded from the orifice during the measurement.

(Iii) Composition of base resin The blending amount of the polyamide resin (B) in the base resin of the polystyrene resin extruded foam of the present invention is 1 to 100 parts by weight with respect to 100 parts by weight of the polystyrene resin (A). The amount is preferably 3 to 50 parts by weight, particularly preferably 5 to 20 parts by weight.
If the blending amount of the polyamide resin (B) is too small, the effect of improving the gas barrier property of the foam becomes small. On the other hand, when the blending amount of the polyamide resin (B) is too large, the melt tension of the polystyrene-based resin mixture is lowered and foam molding becomes difficult, and a foam having both a high expansion ratio and a high closed cell ratio cannot be obtained. There is a fear.
In the present invention, other (co) polymers such as a polyolefin resin, a styrene elastomer, and a polyphenylene ether resin may be further mixed and used in the base resin within a range not impairing the object of the present invention. However, the amount of such other (co) polymer used is preferably 30% by weight, more preferably 0 to 20% by weight, more preferably 0 to 10% in the base resin. It is particularly preferred that it is wt%.

(2) Physical foaming agent (C)
In the present invention, the physical foaming agent (C) used when foaming the polystyrene resin extruded foam is not particularly limited, but the ozone depletion coefficient is zero or extremely low, and the warming coefficient is low. It is preferred to use a low physical blowing agent. On the other hand, considering the long-term thermal insulation properties of the extruded foam as the physical foaming agent, the physical foaming agent that easily remains in the extruded foam is 10 mol% or more (including 100 mol%), more preferably 20 mol% or more. It is preferably contained (including 100 mol%). As the physical foaming agent that tends to remain in the extruded foam, those having a relatively slow gas permeability with respect to the polystyrene resin can be suitably used. In addition, since the gas barrier property of the base resin in the present invention is improved by the polyamide resin (B), the gas permeability to the base resin is further delayed, and as a result, the heat insulating property is further improved.
Specific examples of the hydrocarbon blowing agent (C1) having a relatively slow gas permeability include aliphatic hydrocarbons having 3 to 5 carbon atoms such as propane, normal butane, isobutane, normal pentane, isopentane, neopentane, and the like; cyclobutane Alicyclic hydrocarbons having 3 to 6 carbon atoms such as cyclopentane and cyclohexane. Among these, normal butane, isobutane, normal pentane, isopentane, and cyclopentane, which have low gas permeability and are suitable as a blowing agent, are more preferable, and isobutane is particularly preferable.

On the other hand, examples of the foaming agent (C2) having a relatively fast gas permeability include alkyl chlorides, alcohols, ethers, ketones, methyl formate, carbon dioxide, and water. Among these blowing agents, physical foaming agents include alkyl chlorides having 1 to 3 carbon atoms, aliphatic alcohols having 1 to 4 carbon atoms, ethers having 1 to 3 carbon atoms in the alkyl chain, carbon dioxide, water, and the like. Is suitable. Examples of the alkyl chloride having 1 to 3 carbon atoms include methyl chloride and ethyl chloride. Examples of the aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, propyl alcohol, isopropyl alcohol, butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, aryl alcohol, crotyl alcohol, propargyl alcohol and the like. It is done. Examples of ethers having 1 to 3 carbon atoms in the alkyl chain include dimethyl ether, ethyl methyl ether, diethyl ether, and methylene dimethyl ether. In particular, methyl chloride, dimethyl ether, methanol, ethanol, carbon dioxide, and water can be cited as those that can be expected to improve the expansion ratio. These physical foaming agents can be used alone or in combination of two or more.
Since the above physical foaming agent is an excellent foaming agent, it has the effect of lowering the apparent density of the extruded foam plate obtained and has high gas permeability to polystyrene. It is effective to stabilize the heat insulation performance and flame retardancy of the plate at an early stage. Also, it is preferable to use carbon dioxide, since it has an effect of reducing the bubbles of the obtained foamed plate, and therefore an effect of reducing the amount of the bubble regulator added and an effect of improving the heat insulation performance can be expected.

Further, from the viewpoint of safety during production of the obtained extruded foam and flame retardancy of the extruded foam, as a physical foaming agent, the above-described hydrocarbon-based foaming agent (C1) having a relatively slow gas permeability and the above-mentioned It is preferable to use a mixed foaming agent in combination with a foaming agent (C2) having a relatively fast gas permeability. By using such a mixed foaming agent, the amount of the foaming agent (C1) added can be reduced, and the foaming agent (C2) is obtained because most of it is dissipated from the foam immediately after foaming. Extruded foam can secure a sufficient expansion ratio, and the amount of flammable gas (foaming agent (C1)) remaining in the foam can be reduced. Therefore, by adding a flame retardant into the base resin, polystyrene Desired flame retardancy can be imparted to the resin extruded foam. In addition, even if there is too little residual amount of the combustible gas (foaming agent (C1)) in a foam, it will lead to a heat insulation performance fall.
The amount of these physical foaming agents added to the base resin is appropriately selected in relation to the desired foaming ratio. In order to obtain a foam having an apparent density of 20 to 60 kg / cm ³ , it is usually mixed per 1 kg of base resin. 0.5-3 mol is added as a foaming agent, Preferably 0.6-2.5 mol is added.

(3) Flame Retardant Since the polystyrene-based resin foam obtained by the present invention is mainly used as a heat insulating board for construction, it is specified in “Measurement Method A” defined in JIS A9511 (2006) 5.13.1. It is assumed that a high degree of flame retardancy satisfying the flammability standard for the extruded polystyrene foam heat insulating plate described is required. Furthermore, it is desirable that the polystyrene resin foam obtained by the present invention satisfies the standard of thermal conductivity defined in JIS A9511 (2006) 4.2. Therefore, the addition of the hydrocarbon as a physical foaming agent in the present invention is performed so that the flame retardancy and the thermal conductivity are compatible, and the hydrocarbon has the flame retardancy and the thermal conductivity in the foam. It is preferable that the remaining amount is adjusted so as to satisfy both standards. Further, the foaming agent having a relatively fast gas permeability is appropriately determined according to the amount of the hydrocarbon in order to achieve a desired apparent density.

Polystyrene system that requires high thermal insulation performance that satisfies the flammability standard for the extruded polystyrene foam heat insulating plate described in “Measurement Method A” as defined in JIS A9511 (2006) 5.13.1. The resin extruded foam is achieved by adding a flame retardant in addition to the adjustment of the hydrocarbon content. A brominated flame retardant is preferably used as a flame retardant that can be used in the production of polystyrene resin extruded foam. Examples of brominated flame retardants include tetrabromobisphenol A, tetrabromobisphenol A bis (2,3-dibromopropyl ether), tetrabromobisphenol A bis (2-bromoethyl ether), tetrabromobisphenol A bis (allyl ether). ), 2,2-bis [4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl] propane, tetrabromobisphenol S, tetrabromobisphenol S-bis (2,3-dibromopropyl) Ether), hexabromocyclododecane, tetrabromocyclooctane, tris (2,3-dibromopropyl) isocyanurate, tribromophenol, decabromodiphenyl oxide, tris (tribromoneopentyl) phosphate, N, 2-3-di Romopuropiru 4,5-dibromo hexahydrophthalimide, and the like brominated bisphenol ether derivative. These compounds can be used alone or in admixture of two or more. Among the above brominated flame retardants, it has high thermal stability and a high flame retardant effect, so hexabromocyclododecane, tetrabromocyclooctane, tetrabromobisphenol A bis (2,3-dibromopropyl ether) 2,2-bis [4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl] propane and tris (2,3-dibromopropyl) isocyanurate are particularly preferred.
The content of the flame retardant in the polystyrene-based resin extruded foam improves the flame retardancy, and suppresses the decrease in foamability and mechanical properties, so that the content is 1 to 10 weight per 100 parts by weight of the base resin. Part is preferable, 1.5 to 7 parts by weight is more preferable, and 2 to 5 parts by weight is still more preferable.

  Furthermore, in the present invention, a flame retardant aid can be used in combination with the brominated flame retardant for the purpose of further improving the flame retardancy of the extruded foam. 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 -Polyalkylated aromatic compounds such as diisopropylbenzene, triphenyl phosphate, cresyl di 2,6-xylenyl phosphate, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, isocyanuric acid, triallyl isocyania Nitrogen-containing cyclic compounds such as nurate, melamine cyanurate, melamine, melam, melem Silicone compounds, boron oxide, zinc borate, inorganic compounds such as zinc sulfide, red phosphorus-based, ammonium polyphosphate, phosphazene, phosphorus-based compounds such as hypophosphorous acid salts and the like. These compounds can be used alone or in admixture of two or more.

(4) Heat insulation improver In this invention, a heat insulation improver can be further added to base resin, and heat insulation can be improved. Examples of the heat insulation improver include metal oxides such as titanium oxide, metals such as aluminum, fine powders such as ceramics, carbon black and graphite, infrared shielding pigments, hydrotalcite and the like. These can use 1 type (s) or 2 or more types. 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 base resin.

(5) Other additives In the present invention, various additives such as air conditioners, colorants such as pigments and dyes, heat stabilizers, and other fillers are appropriately added to the base resin as necessary. Can be added. Examples of the air conditioner include inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, aluminum oxide, clay, bentonite, and diatomaceous earth; conventionally known chemical foaming such as azodicarbodiamide An agent or the like can be used. Of these, talc is preferred because it does not impair flame retardancy and allows easy adjustment of the bubble diameter. In particular, fine talc having a particle size of 0.1 to 20 μm as defined in JIS Z8901 (2006) is preferable, and one having a size of 0.5 to 15 μm is preferable. The amount of the bubble regulator added varies depending on the type of the regulator, the target bubble diameter, etc., but when talc is used, it is preferably 0.01 to 8 parts by weight with respect to 100 parts by weight of the base resin. 0.01 to 5 parts by weight is more preferable, and 0.05 to 3 parts by weight is particularly preferable.
It is preferable from the viewpoint of the dispersibility of the additive that the air-conditioning agent is prepared and used in the same manner as other additives in a masterbatch using a polystyrene resin as a base resin. Preparation of the master batch of the foam preparation agent is preferably prepared so that the content of talc is 20 to 80% by weight with respect to the base resin when talc is used as the foam regulator, for example, 30 It is more preferable to adjust so that it may become -70weight%.

(6) Method for Producing Polystyrene Resin Extruded Foam A method for producing a polystyrene resin extruded foam uses the above base resin containing the polystyrene resin (A) and the polyamide resin (B). The main feature is that an additive such as a bubble adjusting agent is added to the base resin as necessary, melted and kneaded in the extruder, and then a physical foaming agent is pressed into the extruder to form a molten resin. Dissolve the foaming agent, adjust the temperature of the molten resin containing the physical foaming agent to obtain a foamable molten resin, and extrude the foamable molten resin from the flat die attached to the tip of the extruder to the low pressure region At the same time, a plate-like polystyrene resin extruded foam can be obtained by passing it through a shaping device attached downstream of the die.

The base resin, the flame retardant, the foaming agent, the heat insulation improver, other additives used in the foamable molten resin, and the blending amounts thereof are as described above.
In addition, when supplying a flame retardant to an extruder, a method of supplying a predetermined amount of a flame retardant dry blended with a base resin to the extruder, a flame retardant and a polystyrene resin (A), etc. Adopting a method of supplying a melt-kneaded material kneaded by a method to an extruder, a method of supplying a liquid flame retardant previously heated and melted into an extruder, or a method of preparing a flame retardant master batch and supplying it to an extruder Can do. In particular, it is preferable to adopt a method of preparing a flame retardant master batch and supplying it to an extruder from the viewpoint of dispersibility.
In addition, when supplying the heat insulation improver to an extruder, a predetermined amount of heat insulation improver is dry blended with a base resin or the like, and the blend is extruded from a supply unit provided upstream of the extruder. It can be fed into a machine, kneaded and blended into the molten polystyrene resin mixture. Moreover, the masterbatch which mix | blended the said heat insulation improvement agent of the high concentration with the polystyrene-type resin (A) etc. previously is produced, and the method of supplying this to an extruder is employable. In particular, it is preferable to adopt a master batch method from the viewpoint of dispersibility. Preparation of the master batch of the heat insulation improver is adjusted so that the heat insulation improver is contained in the polystyrene resin in an amount of 10 to 80% by weight, preferably 20 to 70% by weight, and further 30 to 60% by weight. It is preferable.

In the method of the present invention, after the melted resin in which the base resin, physical foaming agent, additive, etc. are melt-kneaded in the extruder is adjusted to a foaming suitable temperature, it is continuously extruded through a die lip from the high pressure region to the low pressure region and foamed. The foamable resin is shaped into a foam such as a plate while foaming. Specifically, the foamable molten resin mixture is first formed into a plate shape while passing through a shaping device while compressing the foamable molten resin mixture in the process of foaming by passing through a passage having a specific structure while foaming the foamable molten resin mixture. To do. As the shaping device, it is preferable to use a shaping tool composed of a pair of upper and lower polytetrafluoroethylene plates, for example.
The foaming temperature means a temperature within a range in which a molten resin containing a foaming agent exhibits a melt viscosity suitable for foaming, and the type of base resin used and the presence or absence of a fluidity improver (when added) , The type and amount thereof), and the amount of addition of the mixed foaming agent, the components of the mixed foaming agent, and the like.

[2] Polystyrene resin extruded foam obtained by the present invention The polystyrene resin extruded foam obtained by the method for producing a polystyrene resin extruded foam of the present invention comprises a polystyrene resin (A And a polyamide resin (B) containing 20 to 100% by weight of a polyamide having a diamine structural unit derived from metaxylylenediamine which is a discontinuous phase dispersed in the polystyrene resin (A), In order to achieve the intended purpose, it is desirable that the polyamide resin (B) phase is present in a state stretched in a direction perpendicular to the thickness direction of the cell membrane.
That is, it is preferable that the cell membrane constituting the polystyrene resin extruded foam has a sea-island structure with the polyamide resin (B) as an island, and the polyamide resin (B) is dispersed in a number of layers. Preferably it is. In FIG. 1, the sea portion is a continuous phase portion made of polystyrene resin (A), and the island portion has a sea-island structure that is a discontinuous phase portion made of polyamide resin (B).
As shown in the scanning transmission electron micrograph of the cross section of the bubble film of the polystyrene resin extruded foam of FIG. 1, the preferred polystyrene resin extruded foam formed in this way is a foam film of the foam, It is composed of a continuous phase composed of a polystyrene-based resin and a discontinuous phase in which a polyamide resin is dispersed in the continuous phase (a streaky phase extending from the upper right to the lower left in FIG. 1). The film is stretched in a direction perpendicular to the thickness direction of the bubble film.
As shown in FIG. 1, in order to disperse the polyamide resin composition (B) in a stretched state in the cell membrane, the polystyrene resin (A) and the polyamide resin composition (B) are melted during foam molding. It can be obtained by adjusting the viscosity. In the method for producing a polystyrene resin extruded foam of the present invention, the polyamide resin (B) is melted under conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ in relation to the melt viscosity of the polystyrene resin (A). The sea-island structure can be formed by satisfying the condition of the viscosity of 1000 to 10,000 Pa · s. As described above, the polystyrene resin (A) preferably has a melt viscosity of 500 to 10,000 Pa · s under the conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ . The melt viscosity ratio of the polystyrene resin (A) and the polyamide resin composition (B) (melt viscosity of the resin (A) / melt viscosity of the resin (B)) is preferably 0.1 to 10, and 0 It is preferably 25 to 5, more preferably 0.5 to 2.

(I) Thickness of polystyrene-based resin extruded foam The polystyrene-based resin extruded foam preferably has a thickness of 10 to 150 mm for the purpose of use. When the thickness is too thin, there is a possibility that the heat insulating property required when used as a heat insulating material will be insufficient. On the other hand, depending on the size of the extruder, foaming may be difficult if the thickness is too thick. The thickness is more preferably 15 mm to 120 mm.

(Ii) Apparent density of polystyrene resin extruded foam The apparent density of the polystyrene resin extruded foam is preferably 20 to 60 kg / cm ³ . If the apparent density is too low, it is quite difficult to produce an extruded foam itself, and depending on the application, the mechanical strength becomes insufficient. On the other hand, when the apparent density is too large, it is difficult to exhibit sufficient heat insulation unless the thickness of the extruded foam is considerably increased, and it is not preferable from the viewpoint of light weight.

(Iii) Average cell diameter The average cell diameter in the thickness direction of the polystyrene resin extruded foam is preferably 0.05 to 2 mm, more preferably 0.06 to 0.8 mm, and still more preferably 0.07 to 0.3 mm. When the average cell diameter is within the above range, an extruded foam plate having excellent mechanical strength and higher heat insulating properties can be obtained. If the bubble diameter is too small, it is difficult to obtain an extruded foam having a large thickness and a low apparent density, and the bubble film is too thin to easily transmit infrared rays, resulting in poor heat insulation of the foam. There is a risk of doing. On the other hand, if it is too large, there is a possibility that an extruded foam having the desired heat insulating property cannot be obtained.
The measurement method of the average bubble diameter in this specification is as follows.
The average cell diameter (D _T : mm) in the thickness direction of the extruded foam and the average cell diameter (D _W : mm) in the width direction of the extruded foam are perpendicular to the widthwise vertical cross section of the extruded foam (the direction of extrusion of the extruded foam plate). The average cell diameter (D _L : mm) in the extrusion foam extrusion direction was bisected at the center in the width direction in parallel to the extrusion direction of the extrusion foam plate (parallel to the extrusion direction). A microscopic magnified photograph of a vertical section) is obtained. Next, a straight line is drawn in the direction to be measured on the magnified photograph, the number of bubbles intersecting the straight line is counted, and the length of the straight line (naturally, this length is the length of the straight line on the magnified photograph). Rather than refer to the length of a straight line taking into account the magnification of the photograph), the average bubble diameter in each direction is determined by dividing by the number of counted bubbles.

The measurement method of the average bubble diameter will be described in detail. The measurement of the average bubble diameter (D _T : mm) in the thickness direction is obtained by taking three magnified microphotographs at the center and both ends of the vertical cross section in the width direction. In the above, a straight line over the entire thickness of the extruded foam is drawn in the thickness direction, and the average diameter of the bubbles existing on each straight line (the length of the straight line / the straight line) is calculated from the length of each straight line and the number of bubbles intersecting the straight line. The number of bubbles intersecting with each other) is determined, and the arithmetic average value of the average diameters of the three obtained locations is defined as the average bubble diameter (D _T : mm) in the thickness direction.
The average cell diameter in the width direction (D _W : mm) is a microscopic magnified photograph of a total of three locations at the center and both ends of the cross section in the width direction. On each photograph, the extruded foam is second-order in the thickness direction. At the position to be divided, a straight line having a length of 3 mm multiplied by the enlargement factor is drawn in the width direction, and the average diameter of the bubbles existing on each straight line is calculated from the number of bubbles intersecting the straight line by the formula (3 mm / The arithmetic average value of the average diameters of the three obtained locations is defined as (average number of bubbles in the width direction (D _W : mm)).

The average cell diameter in the extrusion direction (D _L : mm) is a position that bisects the width direction of the extruded foam, and the central portion of the vertical cross section in the extrusion direction obtained by cutting the extruded foam in the extrusion direction. Microscopic magnified photographs of a total of three locations at both ends, and on each photograph, a straight line having a length multiplied by 3 mm and an expansion ratio is drawn in the extrusion direction at a position where the extruded foam is equally divided in the thickness direction, From the straight line and the number of bubbles intersecting the straight line, the average diameter of the bubbles existing on each straight line is determined by the formula (3 mm / (number of bubbles intersecting the straight line −1)), and the obtained three locations Let the arithmetic mean value of the average diameter of be the average bubble diameter in the extrusion direction (D _L : mm). The average cell diameter in the horizontal direction of the extruded foam plate _(D H: mm) is the arithmetic mean value of _{D W} and _{D L.}

(Iv) Average cell deformation rate Further, in the polystyrene resin extruded foam, the cell deformation rate is preferably 0.7 to 2.0. The cell strain rate is a value calculated by dividing the D _T obtained by the measuring method in _{D H (D T / D H} ), bubbles as bubble deformation ratio is less than 1 flat The larger the value is, the longer the image is. If the bubble deformation rate is too small, the compression strength may decrease because the bubbles are flat, and the flat bubbles tend to return to a spherical shape, so the dimensional stability of the extruded foam may also decrease. . When the bubble deformation rate is too large, the number of bubbles in the thickness direction is reduced, so that the effect of improving heat insulation by the bubble shape is reduced. From such a viewpoint, the bubble deformation rate is preferably 0.8 to 1.5, and more preferably 0.8 to 1.2. When the bubble deformation rate is within the above range, a polystyrene resin extruded foam having excellent mechanical strength and further high heat insulating properties is obtained.

(V) Closed cell ratio The closed cell ratio of the polystyrene resin extruded foam is preferably 90% or more, and more preferably 93% or more. The higher the closed cell ratio, the higher the heat insulation performance can be maintained. The closed cell ratio S (%) is measured using an air comparison type hydrometer (for example, Toshiba Beckman Co., Ltd., air comparison type hydrometer, model: 930 type) according to the procedure C of ASTM-D2856-70. The true volume Vx of the extruded foam thus obtained is calculated by the following formula (1).
Measurement samples were cut out from a total of three locations near the center and both ends in the width direction of the extruded foam, and the closed cell ratio was measured for each cut sample, and the arithmetic average value of the three closed cell ratios was extruded. The closed cell ratio of the foam is used. The cut sample is a sample that is cut from the extruded foam to a size of 25 mm long × 25 mm wide × 20 mm thick and does not have an extruded foam skin. If the sample is thin and 20 mm in the thickness direction cannot be cut out, 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 extruded foam, and all the bubbles in the closed cell portion in the cut sample Equivalent to the sum of volume.)
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 resin constituting the extruded foam (g / cm ³ )

(Vi) Thermal conductivity of extruded polystyrene resin foam The thermal conductivity of the extruded polystyrene resin foam is preferably 0.029 W / m · K or less.
In the present invention, the thermal conductivity is obtained by cutting out a test piece having an extruded foam surface of 200 mm length × width 200 mm × thickness 25 mm from the extruded foam, and the flat plate heat flow described in JIS A 1412-2 (1999). It is measured based on a measurement method (two heat flow meter method, high temperature side 38 ° C., low temperature side 8 ° C., average temperature 23 ° C.). When a test piece having a thickness of 25 mm cannot be cut out, a plurality of (as few as possible) thin test pieces are stacked to obtain a test piece having a thickness of 25 mm.

(Vii) Residual physical foaming agent In the present invention, as the physical foaming agent (C) remaining in the foam, the ozone depletion coefficient is zero or extremely low, and the gas permeability to the styrene resin is relatively slow. From the viewpoint, a hydrocarbon-based blowing agent is preferable. Since the base resin in the present invention contains the polyamide resin (B), the gas barrier property is improved, so that the gas permeability to the base resin is further delayed, and as a result, the heat insulating property can be further improved. .

Examples of the hydrocarbon blowing agent (C1) having a relatively slow gas permeability include aliphatic hydrocarbons having 3 to 5 carbon atoms, specifically, propane, normal butane, isobutane, normal pentane, isopentane, neopentane, and the like. And alicyclic hydrocarbons having 3 to 6 carbon atoms, specifically, cyclobutane, cyclopentane, cyclohexane and the like. Among these, normal butane, isobutane, normal pentane, isopentane, and cyclopentane are more preferable, and isobutane is particularly preferable because of low gas permeability and excellent foaming agent suitability. The said foaming agent can be used individually or in combination of 2 or more types.
In the polystyrene resin extruded foam of the present invention, in order to obtain excellent heat insulation and flame retardancy, the residual amount of the hydrocarbon foaming agent having 3 to 5 carbon atoms in the foam is 1 kg of the extruded foam. It is preferably 0.1 to 0.9 mole per mole, and more preferably 0.4 to 0.9 mole. The residual amount of the foaming agent in the foam in the present specification can be measured using a gas chromatograph.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these Examples.
(1) The raw materials used for the base resin in Examples and Comparative Examples are shown below.
(I) Base resin The commercially available resins constituting the base resin are shown in Table 1, and the polyamide resin is shown in Table 2.

The resins shown in Table 1 below are as shown in (i) to (d) below.
(A) MS has a structural unit (styrene / methyl methacrylate) weight ratio of styrene and methyl methacrylate in the resin of 40/60.
(B) The heat-resistant PS has a styrene / methacrylic acid constituent unit (styrene / methacrylic acid) weight ratio of 93/7 in the resin.
(C) MXD5 is polymetaxylylene adipamide obtained by a condensation reaction of metaxylylenediamine and adipic acid.
(D) Amorphous nylon is a semi-aromatic polyamide obtained by a 6I / 6T condensation reaction. In addition, said "I" shows an isophthalic acid component and "T" shows a terephthalic acid component.

The polyamides shown in Table 2 below are as shown in (a) to (e) below.
(I) MXD1
Weigh 14.2 kg (97.1 mol) of adipic acid and 1.0 kg (6.2 mol) of isophthalic acid in a 50 L reactor equipped with a stirrer, a condenser, a cooler, a dripping tank, and a nitrogen gas introduction tube. The mixture was sufficiently purged with nitrogen and further made into a uniform slurry of molten adipic acid and isophthalic acid at 160 ° C. under a small amount of nitrogen stream. To this, 14.0 kg (102.6 mol) of metaxylylenediamine was added dropwise over 1 hour with stirring. During this time, the internal temperature was continuously increased to 247 ° C. Water distilled with the addition of metaxylylenediamine was removed out of the system through a condenser and a condenser. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was raised to 260 ° C. and the reaction was continued for 1 hour. The obtained polymer was taken out as a strand from the nozzle at the bottom of the reaction can, cooled with water and then cut into pellets to obtain polyamide 1.
Next, 40% by weight of the polyamide 1 and 40% by weight of amorphous nylon (manufactured by Mitsubishi Engineering Plastics Co., Ltd., amorphous nylon, trade name: Novamid X21) and nylon 6 (manufactured by Ube Industries, Ltd.) , Trade name: UBE nylon 1015B) After mixing 20% by weight, it was supplied to a 37 mm twin screw extruder having a staying part. Melt kneading was performed at a cylinder temperature of 310 ° C., a screw rotation speed of 100 rotations, and a discharge rate of 6 kg / hr. The melt strand was cooled and solidified with cooling air, and pelletized to obtain MXD1.
(B) MXD2
30% by weight of the polyamide 1, 30% by weight of amorphous nylon (manufactured by Mitsubishi Engineering Plastics Co., Ltd., amorphous nylon, trade name: Novamid X21), and nylon 666 (manufactured by Ube Industries, Ltd., product) Name: UBE nylon 5013B) 40% by weight was mixed and pelletized in the same manner as MXD1 to obtain MXD2.

(C) MXD3
Adipic acid 11.9 kg (81.65 mol) and isophthalic acid 3.4 kg (20.73 mol) were weighed and charged, sufficiently purged with nitrogen, and made into a uniform slurry at 160 ° C. under a small amount of nitrogen stream. To this, 13.7 kg (100.039 mol) of metaxylylenediamine was added dropwise over 160 minutes with stirring to obtain MXD3 by cutting into pellets in the same manner as in polyamide 1.
(D) MXD4
40% by weight of the polyamide 1, amorphous nylon (manufactured by Mitsubishi Engineering Plastics Co., Ltd., amorphous nylon, trade name: Novamid X21), and nylon 6 (manufactured by Ube Industries, Ltd., product) Name: UBE nylon 1015B) After mixing 30% by weight, it was pelletized in the same manner as MXD1 to obtain polyamide 2.
Next, 95% by weight of the polyamide 2 and 5% by weight of modified polyethylene (manufactured by Sanyo Chemical Industries, Ltd., modified polyethylene, trade name: Umex 2000) were mixed with MXD1 except that the cylinder temperature was 220 ° C. Similarly, pelletized to obtain MXD4.
(E) MXD5 and amorphous nylon MXD5 and amorphous nylon are as described in Table 1.

(Ii) Masterbatch Air bubble modifier masterbatch: A talc masterbatch containing 60% by weight of talc (manufactured by Matsumura Sangyo Co., Ltd., trade name: High Filler # 12) using polystyrene resin as a base resin was used.
Flame retardant masterbatch: A flame retardant masterbatch containing 93% by weight of hexabromocyclododecane was used.

(2) The evaluation method is described below.
In addition, the closed cell diameter, the thickness direction average cell diameter, the average cell deformation rate, and the thermal conductivity employ the evaluation method described in the above-mentioned section “[2] Polystyrene resin extruded foam obtained by the present invention”. did.
(I) Foam moldability The foam moldability in Tables 3 to 5 was evaluated according to the following evaluation criteria.
◯: A good plate-like extruded foam having a good foamed state and having no waviness on the surface can be stably obtained.
X: The foamed state is poor, the surface is wavy, and a good plate-like extruded foam cannot be obtained.
(Ii) Apparent density The apparent density is measured according to JIS K 6767 (1999). The sample was cut out from a total of three locations in the widthwise center of the extruded foam and in the vicinity of both ends in the widthwise direction, and the apparent density was measured for each sample. The average value is the apparent density.
(Iii) Cross-sectional area The cross-sectional area of the polystyrene resin extruded foam is the cross-sectional area of the vertical cross section (width direction vertical cross section) orthogonal to the extrusion direction of the extruded foam plate.
(Iv) Thickness The thickness of the polystyrene resin extruded foam is determined at 5 points excluding both ends by dividing the width from the widthwise end of the extruded foamed plate to the other end into 6 parts. Then, the thicknesses of the extruded foam plates at the five measurement points are respectively measured, and the arithmetic average value of the measurement values at the five points is obtained.

(V) Ratio of thermal conductivity The thermal conductivity reduction rate is the value of the thermal conductivity of the extruded foam obtained in Examples and Comparative Examples, and the thermal conductivity of the extruded foam obtained in Comparative Example 1. It is the value divided by the value of rate.
(Vi) Partial pressure of air in the bubbles The pressure in the bubbles was determined by cutting out a test piece having a foam formed body skin of length 200 mm × width 200 mm × thickness 25 mm from the extruded foam immediately after production, and subjecting the test piece to 23 ° C. and humidity. Measurement is performed by the following method using the test piece 100 days after production, which is stored in an atmosphere of 50%. First, a sample having a length of 90 mm, a width of 25 mm, and a thickness of 15 mm is taken from the center of the extruded foam by punching. Next, the sample is put in a container filled with ethanol, and the air in the container is discharged. Next, toluene is put in the container so that air is not mixed, the sample is dissolved in toluene, the volume of air in the bubbles is measured, and the partial pressure of air in the bubbles is obtained.
The methods for measuring the closed cell ratio, thickness direction average cell diameter, average cell deformation rate, and thermal conductivity are as described above.

[Examples 1 to 5]
A first extruder with an inner diameter of 65 mm, a second extruder with an inner diameter of 90 mm, and a third extruder with an inner diameter of 150 mm are connected in series, and a blowing agent inlet is provided near the end of the first extruder, A production apparatus was used in which a flat die provided with a resin discharge port (die lip) having a 1 mm × 90 mm wide cross section in the width direction was connected to the outlet of the third extruder.
Further, a shaping device (guider) composed of a plate made of a pair of upper and lower polytetrafluoroethylene resins installed parallel to the resin outlet of the flat die is attached. In Examples 1 to 5, the resin, the flame retardant, and the air conditioner were supplied to the first extruder so as to have the blending amounts shown in Table 3, heated to 220 ° C., and melted and kneaded. A molten resin composition obtained by supplying a physical foaming agent having a composition shown in Table 3 to a melt at a ratio shown in Table 3 from a foaming agent injection port provided near the tip of one extruder and melt-kneading the second extrusion The resin temperature is supplied to the machine and the third extruder, and the foaming temperature shown in Table 3 is shown as foaming resin temperature in Table 3. This foaming temperature is measured at the position of the junction between the extruder and the die. The temperature of the foamable molten resin composition), and then extruded from the die lip into the guider at a discharge rate of 50 kg / hr and foamed while being foamed and arranged in parallel with a gap of 28 mm in the thickness direction of the extruded foam. Molded into a plate by passing through the inside ( Form) and to produce a plate-shaped extruded polystyrene resin foam. The evaluation results are summarized in Table 3.
In addition, the scanning transmission electron microscope photograph (magnification: 15000 times) of the bubble film | membrane cross section of the polystyrene-type resin extrusion foam in Example 1 is shown in FIG. The dispersibility of MXD1 in the polystyrene resin is good, and it is observed that the polyamide phase exists in a state stretched in a direction perpendicular to the thickness direction of the cell membrane.

[Comparative Examples 1-5]
As shown in Table 4, the same plate as described in Example 1 except that the polyamide was not blended as a base resin in Comparative Example 1 and the polyamides and addition amounts thereof shown in Table 4 were used in Comparative Examples 2 to 5. A polystyrene-based resin extruded foam was produced.
In addition, the cross-sectional microscope picture (magnification: 1000 times) by the microscope of the polystyrene-type resin extrusion foam in the comparative example 2 is shown in FIG. The dispersibility of MXD4 in the polystyrene resin is low, and it is observed that the polyamide resin exists in a massive state.

[Examples 6 to 9, Comparative Examples 6 and 7]
In Examples 6 to 9 and Comparative Examples 6 and 7, as a base resin, PS and MXD1 were blended at a ratio shown in Table 5, and the same as described in Example 1, extruding and foaming a plate-like polystyrene resin The body was manufactured.
The evaluation results are summarized in Table 5.

[Evaluation results]
Examples 1 to 3 are experiments conducted by changing the type of polyamide corresponding to the polyamide resin (B) of the present invention. All of the thermal conductivities were low and had excellent heat insulating properties.
In Example 4, as the base resin, only the polystyrene resin in Example 1 was changed to PS / MS = 7/3 (weight ratio). A polystyrene resin extruded foam with the lowest thermal conductivity was obtained due to the additive effect with the heat insulation improvement effect of MS.
In Example 5, only the polystyrene resin in Example 1 was changed to heat-resistant PS. The thermal conductivity was almost the same as in Example 1.
Comparative Example 1 is an example in which the base resin does not contain the polyamide resin (B). Comparative Examples 2 to 5 are examples in which a polyamide other than the polyamide resin (B) of the present invention is used as the base resin. Each was a polystyrene resin extruded foam having a higher thermal conductivity than that of the examples of the present invention.
Examples 6 to 9 are examples in which the same kind of polystyrene resin (A) and polyamide resin (B) as in Example 1 were used, and the blending ratios of the two were changed. A polystyrene resin extruded foam having the lowest thermal conductivity when the blending amount of the polyamide resin (B) was 30% by weight was obtained.
Comparative Examples 6 and 7 are examples in which the compounding amount of the polyamide resin (B) in the base resin was changed with respect to Example 1 and was outside the scope of the present invention. When the blending amount of MXD1 was 60% by weight, the moldability deteriorated. On the other hand, when the blending amount of MXD1 was 0.5% by weight, the effect of addition was hardly seen.

Claims (3)

A method for producing an extruded foam in which a foamable molten resin containing a physical foaming agent is extruded and foamed,
The resin constituting the foamable molten resin is a mixture of a polystyrene resin (A) and a polyamide resin (B) containing 20 to 100% by weight of a polyamide having a diamine structural unit derived from metaxylylenediamine, The mixture is blended in an amount of 1 to 100 parts by weight of the resin (B) with respect to 100 parts by weight of the resin (A).
The resin (A) has a melt viscosity of 500 to 10,000 Pa · s under conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ .
The resin (B) has a melt viscosity of 1000 to 10,000 Pa · s under conditions of a temperature of 180 ° C. and a shear rate of 100 sec ⁻¹ .
Polyamide having a diamine structural unit derived from metaxylylenediamine,
70 to 100 mol% of the diamine structural unit is derived from metaxylylenediamine, and 70 to 100 mol% of the dicarboxylic acid structural unit is an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and isophthalic acid. A method for producing a polystyrene-based resin extruded foam, which is a polyamide derived from a dicarboxylic acid having an acid molar ratio of 50:50 to 98: 2 . 2. The polystyrene resin according to claim 1, wherein the mixture is a blend of 3 to 50 parts by weight of the resin (B) with respect to 100 parts by weight of the resin (A). Method for producing extruded foam. From the polyamide (b-1) in which the polyamide resin (B) has a diamine structural unit derived from metaxylylenediamine, and one or more polyamides (b-2) selected from aliphatic polyamides and amorphous polyamides becomes, (b-1) component and (b-2) total weight with respect to 100 wt% (b-1) component component is characterized by a 30 to 98 wt%, to claim 1 or 2 The manufacturing method of the polystyrene-type resin extrusion foam of description.