JP5665129B2 - Method for producing extruded foam of thermoplastic resin - Google Patents

Description

  The present invention relates to a method for producing a thermoplastic resin extruded foam (hereinafter sometimes simply referred to as an extruded foam), and more specifically, a thermoplastic resin extruded foam useful as a heat insulating material for a wall, floor, roof, etc. of a building. It relates to the manufacturing method.

  Since polystyrene resin extruded foam has excellent heat insulating properties and mechanical strength, those molded into a plate shape are widely used as building materials including heat insulating materials. Such a polystyrene resin extruded foam is generally a foamable resin melt obtained by heating and melting a polystyrene resin in an extruder to obtain a resin melt, and then press-fitting a foaming agent into the melt and kneading. It is manufactured by extruding and foaming to a low pressure range from a flat die attached to the tip of the extruder and shaping it into a plate shape through a shaping device such as a guider.

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

  However, since this HFC has a large global warming potential, it is still a foaming agent that leaves room for improvement from the viewpoint of protecting the global environment. For this reason, the manufacturing method of the polystyrene resin extrusion foam which uses an eco-friendly foaming agent whose ozone depletion coefficient is 0 (zero) and whose global warming potential is small is examined. For example, propane, normal butane, isobutane, normal pentane, cyclopentane, isopentane, and other aliphatic hydrocarbons and alicyclic hydrocarbons (hereinafter referred to as HC) have been studied as physical foaming agents. It has come to be used as a blowing agent.

  HC has an ozone depletion coefficient of 0 (zero), a low global warming coefficient, is a preferred foaming agent from the viewpoint of protecting the global environment, and has a low thermal conductivity. However, although HC has a slower permeation rate with respect to polystyrene resin than air, it is relatively faster than chlorofluorocarbons. As a result, HC easily dissipates from the foam, and the thermal conductivity of the polystyrene resin extruded foam manufactured using HC increases faster than the extruded foam manufactured using the chlorofluorocarbons. As a result, a polystyrene resin extruded foam produced using HC has left room for improvement with respect to maintaining heat insulation for a long period of time.

  As a method for improving the long-term heat insulating property of the polystyrene resin extruded foam, a polystyrene resin extruded foam is formed by forming a non-halogen-based gas barrier coating on the surface of the polystyrene resin extruded foam within one month after production. A technique for suppressing the dissipation of the physical foaming agent from the body has been proposed (Patent Document 1).

Further, in the thermoplastic resin extruded foam insulation board containing an apparent density of 20 to 50 kg / m ³ , a closed cell ratio of 85% or more, a thickness of 10 to 150 mm, and a non-halogen organic physical foaming agent, the foam board is constituted. The thermoplastic resin is a mixture of a polystyrene resin and a polyester resin satisfying specific conditions, and the amount of the polyester resin is 5 to 150 parts by weight with respect to 100 parts by weight of the polystyrene resin. A thermoplastic resin extruded foam insulation board has been proposed (Patent Document 2).

JP 2002-144497 A Japanese Patent Application No. 2010-90555

  However, the method described in Patent Document 1 requires a special apparatus for coating the polystyrene resin extruded foam with a gas barrier coating, and also at the time of cutting the polystyrene resin extruded foam or during construction. When the coating is damaged, the heat insulating performance cannot be maintained, and thus there is a problem that the practicality is inferior.

  Moreover, in the foam of patent document 2, it has been calculated | required to further improve heat insulation.

  In view of the problems of the prior art, the present invention uses a foaming agent having a zero or very low ozone depletion coefficient and a small global warming coefficient, and has a low thermal conductivity and can maintain heat insulation over a long period of time. In addition, an object of the present invention is to provide a method for producing an extruded foam of a thermoplastic resin, which can produce an extruded foam having a good surface state.

According to this invention, the manufacturing method of the thermoplastic resin extrusion foam shown below is provided.
[1] A C3-C5 saturated hydrocarbon (a), carbon dioxide (b), water (c) and a thermoplastic resin are melt-kneaded to obtain a foamable thermoplastic resin melt. A method for producing a thermoplastic resin extruded foam for extruding and foaming a thermoplastic resin melt,
The thermoplastic resin comprises a polyester copolymer (B) of a diol component containing 10 to 50 mol% of a glycol having a cyclic ether skeleton and a dicarboxylic acid component, and a polystyrene resin (A), and the polyester copolymer The blending amount of (B) is 5 to 150 parts by weight with respect to 100 parts by weight of the polystyrene resin (A), and the blending amount of water (c) is 0.01 mol with respect to 1 kg of the thermoplastic resin. The manufacturing method of the thermoplastic resin extrusion foam characterized by being less than 1 mol above.

[2] The extruded thermoplastic resin foam according to [1], wherein the polyester copolymer (B) comprises a diol component containing 10 to 50 mol% of spiroglycol and a dicarboxylic acid component. Production method.

[3] The blending amount of the saturated hydrocarbon having 3 to 5 carbon atoms (a) is 0.01 to 2 mol with respect to 1 kg of the thermoplastic resin, and the saturated hydrocarbon having 3 to 5 carbon atoms (a). The total amount of carbon dioxide (b) and water (c) is 0.5 to 3 mol per 1 kg of the thermoplastic resin, as described in [1] or [2] above A method for producing an extruded foam of a thermoplastic resin.

  The production method of the present invention may be referred to as a polyester copolymer (B) (hereinafter referred to as a polyester copolymer (B)) of a diol component containing 10 to 50 mol% of a glycol having a cyclic ether skeleton and a dicarboxylic acid component. ) And a polystyrene resin (A), and the thermoplastic resin further contains a saturated hydrocarbon (a) having 3 to 5 carbon atoms, carbon dioxide (b) and water (c). The foamed thermoplastic resin melt is extruded and foamed, and the water contained in the foamable thermoplastic resin melt is converted into the polyester copolymer (B). Since it interacts, it is a method with excellent production stability during extrusion foaming. Furthermore, according to the production method of the present invention, a continuous phase of polystyrene resin (A) and a dispersed phase of the polyester copolymer (B) can be formed in the thermoplastic resin. It is possible to easily obtain a thermoplastic resin extruded foam (hereinafter simply referred to as an extruded foam).

In addition, the content of the glycol component having a cyclic ether skeleton of the polyester copolymer (B) is 10 to 50 mol% with respect to 100 mol% of all diol components, so that a phase with the polystyrene resin (A) is obtained. When the solubility is further improved, the foamability is not inhibited, the extrusion stability is further improved, and an extruded foam having excellent flame retardancy and thermal stability can be obtained stably.
Further, the thermoplastic resin constituting the extruded foam obtained easily forms a continuous phase of the polystyrene resin (A) and a dispersed phase of the polyester copolymer (B). Furthermore, the dispersed phase of the polyester copolymer (B) can form a layered structure.
Therefore, the extruded foam obtained by the production method of the present invention has an improved gas barrier property due to the dispersed phase structure of the polyester copolymer (B) in the cell membrane, so that the resulting extruded foam has 3 carbon atoms. It becomes possible to effectively suppress the dissipation of the saturated hydrocarbon (a) of ˜5 and the inflow of air into the foam. Therefore, the extruded foam obtained by the production method of the present invention maintains excellent heat insulation performance by maintaining a low thermal conductivity over a long period of time without using a blowing agent composed of chlorofluorocarbons. It is useful as a next-generation architectural and civil engineering heat insulating material.

1 is a cross-sectional photograph (magnification: 5000 times) of a cellular membrane of a thermoplastic resin extruded foam obtained in Example 2. FIG. FIG. 2 is a bubble film cross-sectional photograph (magnification: 5000 times) of the thermoplastic resin extruded foam obtained in Comparative Example 3. FIG. 3 is a bubble film cross-sectional photograph (magnification: 5000 times) of the thermoplastic resin extruded foam obtained in Reference Example 1.

  Below, the manufacturing method of the thermoplastic resin extrusion foam of this invention is demonstrated in detail.

The present invention provides a foamable thermoplastic resin melt by melting and kneading a saturated hydrocarbon having 3 to 5 carbon atoms (a), carbon dioxide (b) and water (c) and a thermoplastic resin, A method for producing a thermoplastic resin extruded foam for extruding and foaming a thermoplastic resin melt,
The thermoplastic resin comprises a polyester copolymer (B) of a diol component containing 10 to 50 mol% of a glycol having a cyclic ether skeleton and a dicarboxylic acid component, and a polystyrene resin (A).
The amount of the polyester copolymer (B) is 5 to 150 parts by weight with respect to 100 parts by weight of the polystyrene resin (A),
The amount of the water (c) is 0.01 mol or more and less than 1 mol with respect to 1 kg of the thermoplastic resin.

In the method for producing a thermoplastic resin extruded foam of the present invention, as described above, a foamable thermoplastic resin containing saturated hydrocarbon (a) having 3 to 5 carbon atoms, carbon dioxide (b), and water (c). An extruded foam is produced by extrusion foaming a resin melt.
The thermoplastic resin is composed of a polystyrene resin (A), a polyester copolymer (B) comprising a diol component containing 10 to 50 mol% of a glycol having a cyclic ether skeleton, and a dicarboxylic acid component. . By using the thermoplastic resin, a favorable thermoplastic resin extruded foam having stable, excellent long-term heat insulation, thick foam, and high foaming ratio is produced without causing deterioration of foamability. be able to.

  Examples of the polystyrene resin (A) used in the present invention include a styrene homopolymer, a styrene-acrylic acid ester copolymer, a styrene-methacrylic acid ester copolymer, and a styrene-acrylic acid copolymer mainly containing styrene. Polymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-polyphenylene ether copolymer, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer , Acrylonitrile-styrene-acrylic acid copolymer, styrene-methylstyrene copolymer, styrene-dimethylstyrene copolymer, styrene-ethylstyrene copolymer, styrene-diethylstyrene copolymer, high impact polystyrene, etc. This Al may be used alone, or two or more thereof. The styrene component content in the polystyrene resin is preferably 50 mol% or more, and more 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 A copolymer, a styrene-polyphenylene ether copolymer, a styrene-acrylonitrile copolymer, and a styrene-methylstyrene copolymer are preferable, and among them, a styrene homopolymer, a styrene-methacrylic acid ester copolymer, and a styrene-acrylic acid Ester copolymers and styrene-acrylic acid copolymers are preferred.

The polystyrene resin (A) preferably has a melt viscosity (η) of 500 to 10000 Pa · s, more preferably 700 to 8000 Pa · s under conditions of a temperature of 200 ° C. and a shear rate of 100 sec ^−1. 800 to 6000 Pa · s is more preferable. The melt viscosity is measured under the conditions of a temperature of 200 ° C. and a shear rate of 100 sec ⁻¹ , and can be measured with a Capillograph 1D manufactured by Toyo Seiki Seisakusho.

  The polyester copolymer (B) is composed of a diol component containing a specific amount of glycol having a cyclic ether skeleton and a dicarboxylic acid component, and a polycondensation method of a dicarboxylic acid component and a diol component or a polyester single polymer. The polymer and / or the polyester copolymer can be produced by transesterification or the like.

The polyester copolymer (B) contains a glycol having a cyclic ether skeleton. The glycol having a cyclic ether skeleton is specifically 3,9-bis (1,1-dimethyl-2-hydroxyethyl) 2,4,8,10-tetraoxaspiro [5.5] undecane (hereinafter referred to as “glycol”). , Sometimes referred to as spiroglycol).
The polyester copolymer (B) containing a specific amount of the glycol component having a cyclic ether skeleton can improve the gas barrier property of the thermoplastic resin, and can further improve the heat resistance.

In the polyester copolymer (B), the content of the glycol having a cyclic ether skeleton is 10 to 50 mol% with respect to 100 mol% of all glycol components.
When the content is within the above range, the polyester copolymer (B) has excellent compatibility with the polystyrene resin (A), and is amorphous or has a sufficient crystallization rate. By having a slow property, the foaming property is not inhibited and the extrusion stability is improved. Further, when the polyester copolymer (B) is used, the thermoplastic resin constituting the extruded foam has a cross-section of the cell membrane, the continuous phase of the polystyrene resin (A), and the dispersed phase of the polyester copolymer (B). It becomes easy to form. In addition, from the viewpoint that the polyester copolymer (B) can easily form a layered structure in the entire cell membrane, the content of the glycol component having the cyclic ether skeleton is 15 to 45 mol in all glycol components. %, More preferably 20 to 40 mol%, still more preferably 25 to 35 mol%.

  In addition to the glycol having the cyclic ether skeleton, the polyester copolymer (B) includes, as other diol components, aliphatic and aromatic diols (including divalent phenols), or ester-forming derivatives thereof. Can be contained. Specifically, aliphatic diols such as ethylene glycol, propylene glycol, trimethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, or 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, An alicyclic diol such as 1,6-cyclohexanediol and an aromatic diol such as bisphenol A can be contained. These diol components may be used as a mixture of two or more.

As the dicarboxylic acid component of the polyester copolymer (B), at least one selected from dicarboxylic acids or ester-forming derivatives thereof can be used.
Examples of the dicarboxylic acid component in the polyester copolymer (B) include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 3,4′-diphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, aromatic dicarboxylic acid such as 2,7-naphthalenedicarboxylic acid or derivatives thereof, such as oxalic acid, Aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, dodecanedioic acid or derivatives thereof, or alicyclic rings such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, decalindicarboxylic acid, tetralindicarboxylic acid Group dicarboxylic acid or a derivative thereof.
Examples of ester-forming derivatives include ester derivatives such as alkyl esters having about 1 to 4 carbon atoms, salts such as diammonium salts, and acid halides such as dichloride. These dicarboxylic acid components may be used alone or in combination of two or more.

  As said dicarboxylic acid component, it is preferable that aromatic dicarboxylic acid or its acid anhydride, or its derivative (s), for example, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, 1 or more types of these dicarboxylic acids are included.

  The polyester copolymer (B) may have its molecular ends sealed with component units derived from a monofunctional compound such as a small amount of benzoic acid, benzoylbenzoic acid, methoxypolyethylene glycol, and the like. Moreover, a small amount of component units derived from a polyfunctional compound such as pyromellitic acid, trimellitic acid, trimesic acid, glycerin, pentaerythritol may be included.

  The polyester copolymer (B) is preferably an amorphous or low crystalline compound or a compound having a sufficiently low crystallization rate. If the polyester copolymer (B) has the above characteristics, it is excellent in kneadability with the polystyrene resin (A), and crystallization of the polyester copolymer (B) occurs during extrusion foaming. And extruding stability can be prevented from deteriorating.

  In addition, when extrusion foaming is performed using a mixed resin of polystyrene resin (A) and polyethylene terephthalate, which is a typical polyester resin, instead of the polyester copolymer (B), the polystyrene resin is used in the extruder. Since polyethylene terephthalate crystallizes before cooling the mixed resin of polyethylene terephthalate to the foaming temperature, it cannot be stably extruded and foamed, and the resulting foam also has mechanical properties and closed cell ratio. It becomes inferior to.

  The degree of crystallinity and crystallization rate of the polyester copolymer (B) is, for example, by using two or more kinds of diol components other than spiroglycol, such as ethylene glycol and cyclohexanedimethanol. It can be adjusted by a method of changing the molar ratio or a method of changing the molar ratio of these dicarboxylic acid component units by using two or more terephthalic acid and isophthalic acid as the dicarboxylic acid component.

  The degree of crystallinity of the polyester copolymer (B) can be measured based on the method described in JIS K7122 (1987). Specifically, based on the heat flux differential scanning calorimetry, the temperature is increased to 300 ° C. at a temperature increase rate of 10 ° C./min, then the temperature is decreased to 30 ° C. at a cooling rate of 10 ° C./min, and again 10 ° C. In the DSC curve obtained by raising the temperature from 30 ° C. to 300 ° C. at a rate of temperature rise / minute, the calorific value of the endothermic peak accompanying melting of the polyester copolymer (B) is less than 5 J / g (including 0) Are preferred. Furthermore, the endothermic peak heat quantity of the polyester copolymer (B) is less than 2 J / g (0 is also considered) from the viewpoint of extrusion foamability of the thermoplastic resin comprising the polystyrene resin (A) and the polyester copolymer (B). More preferably).

The melt viscosity of the polyester copolymer (B) is preferably closer to the melt viscosity (ηA) of the polystyrene resin (A) from the viewpoint of compatibility with the polystyrene resin (A). The melt viscosity (ηB) under the conditions of a temperature of 200 ° C. and a shear rate of 100 sec ⁻¹ is preferably 500 to 10000 Pa · s, more preferably 700 to 8000 Pa · s, and 1000 to 6000 Pa · s. Is more preferable, and particularly preferably within the range of 2000 to 5000 Pa · s.
The melt viscosity ratio (ηA / ηB) between the polystyrene resin (A) and the polyester copolymer (B) is preferably 0.15 to 0.50, more preferably 0.25 to 0.00. 4.

In the present invention, excellent compatibility is exhibited by using a polyester copolymer (B) having a melt viscosity close to that of the polystyrene resin (A), and the extruded foam has an apparent density of 20 When extruded and foamed so as to have a high expansion ratio of about 50 kg / m ³ , the foam film can be appropriately stretched, and the dispersed phase of the polyester copolymer (B) stretched in the foam film Is easy to form.

  The thermoplastic resin is one in which the polyester copolymer (B) is blended at a ratio of 5 to 150 parts by weight with respect to 100 parts by weight of the polystyrene resin (A). The amount of the polyester copolymer (B) is preferably 8 to 100 parts by weight, more preferably 10 to 70 parts by weight, with respect to 100 parts by weight of the polystyrene resin (A). More preferably, it is part by weight, and particularly preferably 20 to 45 parts by weight. When there are too few compounding quantities of a polyester copolymer (B), the effect of improving the gas barrier property of the extrusion foam obtained will become small. On the other hand, when the blending amount of the polyester copolymer (B) is too large, the compatibility with the polystyrene resin (A) is lowered, making extrusion foaming difficult, having a high expansion ratio, and further having a high closed cell ratio. There is a possibility that an extruded foam having a high molecular weight cannot be obtained, or that the polyester copolymer (B) cannot have a dispersed phase structure excellent in gas barrier properties.

  In the production method of the present invention, other polymers such as a polyolefin resin, a styrene-based elastomer, and a polyphenylene ether resin are mixed in a thermoplastic resin within a range that does not hinder the original purpose according to the blending purpose. Can also be used. However, the blending amount of such other polymer is preferably up to 30 parts by weight, more preferably 20 parts by weight or less, with respect to 100 parts by weight of the thermoplastic resin. It is particularly preferred that

Next, the meaning of using a thermoplastic resin comprising a polystyrene resin (A) and a specific polyester copolymer (B), which is one of the features of the present invention, will be described in detail.
The effects expected from the extruded foam by blending the polyester copolymer (B) include <1> a reduction effect of the thermal conductivity itself, and <2> a saturated hydrocarbon having 3 to 5 carbon atoms (a). There is a delay in the increase of the thermal conductivity by slowing the gas permeation rate due to the effect of improving the gas barrier property.

<1> Reduction of thermal conductivity Generally, when the thermal conductivity of a polystyrene resin and the thermal conductivity of a polyester copolymer are compared with each other in a non-foamed state, that is, between polymers, the thermal conductivity of a polyester copolymer compared to a polystyrene resin. Therefore, the thermal conductivity of a non-foamed mixed resin obtained by mixing a polyester copolymer with a polystyrene resin is higher than the thermal conductivity of the polystyrene resin alone.

  On the other hand, when the polystyrene resin single foam is compared with the thermoplastic resin foam obtained by mixing the polyester copolymer (B) with the polystyrene resin (A), the thermoplastic resin obtained by mixing the polyester copolymer (B). The thermal conductivity of the foam is lower than that of the polystyrene foam alone. Furthermore, there exists a tendency for thermal conductivity to fall as content of the polyester copolymer (B) in a foam increases. This fact has been found by the present inventors.

  The reason why the thermal conductivity of the thermoplastic resin foam containing the polyester copolymer (B) is lower than the thermal conductivity of the polystyrene resin single foam is the absorption band in the infrared region of the polystyrene resin (A). Further, the absorption band of the polyester copolymer (B) is further added to increase the absorption band in the infrared region, and it is assumed that the thermoplastic resin absorbs infrared rays.

  In general, in the foam, in addition to the heat conduction of the resin itself, heat is transferred by the heat conduction by the gas (residual foaming agent and atmospheric components) in the foam and the convection thereof. Furthermore, since the bubbles constituting the foam are formed over and over, heat is transmitted also by infrared radiation between the bubble films. In the case of the extruded foam obtained in the present invention, it is presumed that the heat insulating property is improved by reducing the heat transfer due to radiation and reducing the heat transfer due to the infrared absorption of the polyester copolymer (B). . As will be described later, the effect of suppressing the radiant heat transfer becomes more remarkable when the polyester copolymer (B) is finely dispersed.

In the case of a thermoplastic resin comprising a polystyrene resin (A) and a polyester copolymer (B), the refractive index of the polystyrene resin (A) is different from the refractive index of the polyester copolymer (B). Since the thermoplastic resin composed of the polystyrene resin (A) and the polyester copolymer (B) does not exhibit a complete compatibility system, it becomes cloudy. This white turbidity affects the infrared region, diffusely reflects infrared rays, reduces the heat transfer by radiation, decreases the heat transfer, and improves the heat insulation of the extruded foam. Also guessed.
For any reason, in the present invention, the thermal conductivity of the obtained extruded foam is lowered by using a thermoplastic resin comprising a polystyrene resin (A) and a specific polyester copolymer (B).

<2> Improvement of gas barrier property with respect to foaming agent (a) The gas transmission rate of oxygen, nitrogen, hydrocarbon, etc. of the polyester copolymer (B) is several times higher than that of the crystalline polyester resin. The effect of improving the properties is hardly expected. Therefore, it is usually effective to mix the polyester copolymer (B) with the polystyrene resin (A) for the dissipation of the foaming agent from the extruded foam and the suppression of the inflow of air into the foam. Hard to think. However, since the combination of the polystyrene resin (A) and the polyester copolymer (B) is relatively excellent in compatibility, a finely dispersed phase is obtained with the polyester copolymer (B) oriented in the foam film. Can be formed. This dispersion structure is considered to exert a gas permeation shielding effect. This is because the polyester copolymer (B) is stretched to form a dispersed structure, and in particular, a gas-liquid cross-sectional photograph showing a layered structure is an excellent gas barrier performance. It is also supported by demonstrating. It is considered that the heat insulation performance is further improved by the combination of the improvement of gas barrier property <2> and the reduction of thermal conductivity <1>.

  Next, the C3-C5 saturated hydrocarbon (a), carbon dioxide (b), and water (c) that are blended in the thermoplastic resin in the present invention will be described.

  The saturated hydrocarbon having 3 to 5 carbon atoms (a) (hereinafter sometimes simply referred to as (a)) is blended in a thermoplastic resin and functions as a foaming agent. Propane, normal butane, isobutane, normal pentane, isopentane, neopentane, cyclopentane and the like. These may be used alone or in combination of two or more. Among these, isobutane is preferable because it has a low gas permeation rate and is suitable as a foaming agent.

  The saturated hydrocarbon (a) having 3 to 5 carbon atoms has a relatively slow gas permeation rate with respect to the polystyrene resin, and can remain in the extruded foam for a relatively long time. Moreover, since the said C3-C5 saturated hydrocarbon (a) has a thermal conductivity lower than air, when it remains in the bubble of a foam, it reduces the thermal conductivity of an extrusion foam. Can contribute. However, on the other hand, the C3-C5 saturated hydrocarbon (a) also inhibits the flame retardancy of the extruded foam. Therefore, the saturated hydrocarbon (a) having 3 to 5 carbon atoms must be added so as to achieve both flame retardancy and long-term heat insulation.

  Considering the compatibility between the long-term heat insulation and flame retardancy of the extruded foam, the blending amount of the saturated hydrocarbon having 3 to 5 carbon atoms (a) is 0.01 to 2 mol with respect to 1 kg of the thermoplastic resin. More preferably, it is 0.1-1.5 mol, More preferably, it is 0.2-1.2 mol, Most preferably, it is 0.3-1.0 mol. Furthermore, if it is in the said range, a foamable thermoplastic resin melt can also be plasticized and it can be made the state more suitable for foaming at the time of extrusion foaming.

The carbon dioxide (b) (hereinafter sometimes simply referred to as (b)) acts as a foaming agent, and in particular, the apparent density of the extruded foam can be further reduced.
Carbon dioxide (b) has a relatively high gas permeation rate with respect to polystyrene. Therefore, almost all of the extruded foam is dissipated immediately after foaming, so that it hardly remains in the extruded foam. By using such carbon dioxide that does not remain in the foam, it is possible to obtain an extruded foam having a higher expansion ratio. In the conventional method, when trying to obtain an extruded foam having a high expansion ratio, a large amount of the saturated hydrocarbon (a) having 3 to 5 carbon atoms, which is excellent in foamability, must be blended. As a result, it may be difficult to satisfy the flame retardancy of the extruded foam.

  According to the production method of the present invention, by adding the carbon dioxide (b), it becomes possible to obtain an extruded foam having a high expansion ratio, and the saturated hydrocarbon (a) having 3 to 5 carbon atoms. Can be reduced to such an extent that flame retardancy does not become a problem. As a result, it is possible to reduce the residual amount of the saturated hydrocarbon having 3 to 5 carbon atoms (a) in the obtained extruded foam within a range in which heat insulation and flame retardancy are compatible, The amount of flame retardant added to impart the desired flame retardancy can be reduced.

  Furthermore, when carbon dioxide (b) is used as a foaming agent, the bubbles in the resulting extruded foam can be reduced, so that it is also possible to reduce the amount of the air conditioning agent added conventionally. As the bubble regulator, an inorganic compound having a high thermal conductivity is often used. Therefore, if the amount of the bubble regulator can be reduced, the thermal conductivity of the resulting extruded foam can be lowered. The effect of improving the heat insulation performance can be expected.

  Considering the foamability and flame retardancy of the extruded foam, the blending amount of carbon dioxide (b) is preferably 0.1 to 3 mol per kg of the thermoplastic resin, and 0.2 to 2. It is more preferably 5 mol, further preferably 0.3 to 2 mol, and particularly preferably 0.3 to 1 mol.

  Furthermore, in the production method of the present invention, water (c) (hereinafter sometimes simply referred to as (c)) is blended with the thermoplastic resin melt in addition to (a) and (b). The Since water (c) also functions as a foaming agent, the apparent density of the obtained foam can be further reduced. Furthermore, water has a higher affinity for the polyester copolymer (B) than the polystyrene resin (A), and it is possible to reduce the melt viscosity of the polyester copolymer (B). Therefore, it is possible to improve the melt-kneading property of the polystyrene resin (A) and the polyester copolymer (B) in the extruder and improve the moldability at the time of extrusion foaming.

  Furthermore, since the water (c) has a high affinity with the polyester copolymer (B), the viscosity balance between the polystyrene resin (A) and the polyester copolymer (B) should be maintained well during extrusion foaming. When a foam film of an extruded foam is formed, the polyester copolymer (B) can be finely dispersed in a state of being stretched in a direction perpendicular to the thickness direction of the foam film. .

The blending amount of the water (c) is 0.01 mol or more and less than 1 mol with respect to 1 kg of the thermoplastic resin.
When the blending amount of water (c) is too small, when the foam film of the extruded foam is formed, most of them form a dispersed phase of the polyester copolymer (B), but the polyester copolymer ( There is a possibility that a part of B) becomes granular, and there is a risk that the gas barrier property is lowered as compared with the case where the polyester copolymer (B) forms a dispersed phase over the entire cell membrane. On the other hand, when there are too many compounding quantities of water (c), it will become easy to generate | occur | produce an excessive bubble in the inside and surface of the extrusion foam obtained. This excessive bubble is not preferable because it leads to an increase in the thermal conductivity of the extruded foam and a decrease in gas barrier properties. Further, when excessive bubbles are generated on the surface of the extruded foam, surface irregularities are generated, and thus an extruded foam having a good appearance cannot be obtained. Due to the excessive addition of water, the excessively large bubbles have a melt viscosity of the polyester copolymer (B) that is lower than the viscosity of the polystyrene resin (A), and the polyester copolymer (B ) Cannot be tolerated, and it is assumed that the cause is bubble breakage.

  From the above viewpoint, the amount of water (c) is preferably 0.02 to 0.95 mol, more preferably 0.05 to 0.8 mol, relative to 1 kg of the thermoplastic resin. More preferably, it is 0.1-0.7 mol. If it is in the said range, a more favorable extrusion foam will be obtained, without producing the excessive bubble by water.

Although the compounding quantity with respect to the thermoplastic resin melt of said (a), (b), and (c) is suitably selected in relation to the foaming ratio desired, extrusion foaming whose apparent density is 20-50 kg / cm < ³ >. In order to obtain a body, it is usually preferable that the total amount of (a) to (c) is 0.5 to 3 mol, and further 0.6 to 2.5 mol per 1 kg of the thermoplastic resin. preferable.

  Further, the blending ratio of the saturated hydrocarbon having 3 to 5 carbon atoms (a), carbon dioxide (b) and water (c) is (a) :( b) :( c) = 20 to 70 mol%: 10. ˜50 mol%: It is preferably 10 to 50 mol% (provided that (a) + (b) + (c) = 100 mol%). If it is in the said range, the flame-retardant property and heat insulation property with favorable low-density plastic foam can be obtained. Moreover, it is possible to further improve the kneadability of the polyester copolymer (B) with the polystyrene resin (A). From the above viewpoint, (a) :( b) :( c) = 30-60 mol%: 20-40 mol%: 10-45 mol% (provided that (a) + (b) + (c) = 100 mol% It is more preferable that

In the present invention, as the physical foaming agent, a foaming agent other than the above (a) to (c) can be appropriately added within the range not impairing the intended purpose of the present invention.
Specifically, hydrofluoroolefins such as trans-1,3,3,3-tetrafluoropropene, cis-1,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoropropene, Examples include cyclohexane, alkyl chloride, alcohols, ethers, ketones, and methyl formate. Among these blowing agents, 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, and the like are suitable as physical blowing agents. is there. 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, dimethyl ether, methanol, and ethanol 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.

In the production method of the present invention, a flame retardant can be added to the thermoplastic resin in order to improve flame retardancy. As the flame retardant, a brominated flame retardant is preferably used.
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, brominated polystyrene, 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, the thermal stability is high and a high flame retardant effect can be obtained. Therefore, 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 amount of the flame retardant is preferably 1 to 10 parts by weight per 100 parts by weight of the thermoplastic resin in order to improve the flame retardancy and to suppress a decrease in extrusion foamability and a decrease in mechanical properties. 1.5-7 parts by weight is more preferable, and 2-5 parts by weight is still more preferable.

  Furthermore, in the production method of 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, antimony 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. The addition amount of the flame retardant aid is preferably 0.05 to 1 part by weight, preferably 0.1 to 0.5 part by weight in the case of diphenylalkane or diphenylalkene with respect to 100 parts by weight of the thermoplastic resin. More preferably it is. In the case of other flame retardant aids, 0.5 to 5 parts by weight is preferably added, and 1 to 4 parts by weight is more preferably added.

  Moreover, in the manufacturing method of this invention, a heat insulation improver can be added to an extrusion foam, and heat insulation can be improved further. Examples of the heat insulation improver include metal oxides such as titanium oxide, metals such as aluminum, ceramics, fine powders such as carbon black and graphite, infrared shielding pigments, hydrotalcite and the like. These can use 1 type (s) or 2 or more types. The blending amount of the heat insulation improver is preferably 0.5 to 5 parts by weight, more preferably 1 to 4 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

  Further, in the production method of the present invention, various additives such as a bubble adjusting agent, a colorant such as a pigment and a dye, a heat stabilizer and a filler can be added as necessary. Examples of the air conditioner include conventionally known chemical foaming such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, aluminum oxide, clay, bentonite, diatomaceous earth and the like, and 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, talc having a particle size of 0.1 to 20 μm, more preferably 0.5 to 15 μm as defined in JIS Z8901 (2006) is preferable. The blending amount of the air conditioner varies depending on the type of the air conditioner, the target cell diameter, etc., but is preferably 0.01 to 8 parts by weight with respect to 100 parts by weight of the thermoplastic resin. The amount is more preferably 0.01 to 5 parts by weight, and still more preferably 0.05 to 3 parts by weight.

  From the viewpoint of dispersibility, it is preferable to add a flame retardant, a bubble regulator and other additives after preparing a master batch. For example, when talc is used as the bubble adjusting agent, the preparation of the master batch of the bubble adjusting agent is preferably prepared such that the content of talc is 20 to 80% by weight with respect to the thermoplastic resin. It is more preferable to prepare so that it may become -70weight%.

In the method for producing a thermoplastic resin extruded foam according to the present invention, a polystyrene resin (A), a polyester copolymer (B), and, if necessary, additives such as a cell regulator are melted in an extruder. Kneading to make a thermoplastic resin melt, and then press the (a), (b), and (c) into the extruder to dissolve them to make a foamable resin melt, and cool the foamable resin melt. Then, after setting the foamed resin temperature, a thermoplastic resin extruded foam can be obtained by extruding and foaming from a flat die attached to the tip of the extruder into a low pressure region.
The foamed resin temperature means a temperature within a range in which the foamable resin melt exhibits a melt viscosity suitable for foaming, and the type of resin to be used, the presence or absence of addition of a fluidity improver (if added, the type And the amount), and further varies depending on the amount of foaming agent added and the components of the foaming agent.

The thermoplastic resin constituting the foamable resin melt, the above (a) to (c), the flame retardant, the heat insulation improver, other additives, and the blending amounts thereof are as described above.
In addition, when supplying a flame retardant to an extruder, a method in which a predetermined amount of a flame retardant is dry blended with a thermoplastic resin, polystyrene resin (A) or the like is supplied to the extruder, a flame retardant and a thermoplastic resin, A method of supplying a melt-kneaded material kneaded with a polystyrene resin (A) or the like to a extruder, a method of supplying a liquid flame retardant previously heated and melted into the extruder, or a flame retardant master batch A method of supplying to the extruder can be adopted. 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 the production method of the present invention, the foamable thermoplastic resin melt in which the thermoplastic resin, the above-mentioned (a) to (c), additives and the like are melt-kneaded in the extruder is adjusted to the foamed resin temperature, and then passed through the die lip. It is formed into a foam such as a plate while continuously extruding from a high pressure region to a low pressure region and foaming. Specifically, first, the foamable resin melt is foamed and compressed while passing through a shaping device, and shaped into a plate shape. As the shaping device, for example, a shaping tool composed of a pair of upper and lower polytetrafluoroethylene plates is preferably used.

  Hereinafter, various physical properties of the extruded foam of a thermoplastic resin obtained by the production method of the present invention, methods for measuring physical properties, evaluation, and the like will be described in detail.

  The thermoplastic resin extruded foam obtained by the production method of the present invention is an extruded foam obtained by using a thermoplastic resin comprising a polystyrene resin (A) and a polyester copolymer (B) as a base resin. Dissipation of saturated C3-C5 hydrocarbons (a) and the inflow of air into the foam can be suppressed. Therefore, even if it does not use the foaming agent which consists of fluorocarbons, it is the outstanding extrusion foam by which a low heat conductivity is maintained over a long term. In addition, the extruded foam is useful as a next-generation architectural and civil engineering heat insulating material as an energy-saving and environmentally friendly technology.

In the production method of the present invention, the apparent density of the obtained extruded foam is preferably 20 to 50 kg / cm ³ . If it is in the said range, it will become possible to exhibit sufficient heat insulation, and it will become a preferable extrusion foam from the point of light weight as a heat insulating material use.

  The apparent density of the extruded foam is measured in accordance with JIS K 6767 (1999). Samples were cut out from a total of three locations in the width direction center of the extruded foam and near both ends in the width direction, and the apparent density of each sample was measured and the apparent density of each sample was measured. The average value is the apparent density.

  The thickness of the extruded foam is preferably 10 to 150 mm. If it is in the said range, it will shape | mold in plate shape, will become an extrusion foam suitable for using as a heat insulating material for buildings, and will have sufficient heat insulation. From this viewpoint, the thickness of the extruded foam is more preferably 15 to 120 mm. In addition, the thickness of the extruded foam is determined by measuring the measurement points at five locations excluding both ends by dividing the width from one end to the other end in the width direction of the extruded foam in the width direction into six equal parts, The thickness of the extruded foam at the five measurement points can be measured and calculated as an arithmetic average value of the measurement values at the five locations.

  The average cell diameter in the thickness direction of the extruded foam is preferably 0.05 to 2 mm. When the average cell diameter in the thickness direction is within the above range, the cell membrane can suppress infrared transmission, and an extruded foam having even higher heat insulation can be obtained. The average cell diameter in the thickness direction is more preferably 0.06 to 0.8 mm, and further preferably 0.06 to 0.3 mm.

  The bubble deformation rate of the extruded foam is preferably 0.7 to 2.0. If the bubble deformation rate is within the above range, the foam is flattened and the compression strength of the extruded foam is not lowered, and an extruded foam that is excellent in dimensional stability and excellent in the effect of improving heat insulation due to the foam shape is obtained. From the above viewpoint, the bubble deformation rate is more preferably 0.8 to 1.5, and still more preferably 0.8 to 1.2.

The measurement method of the average bubble diameter in this specification is as follows.
The average cell diameter (DT: mm) in the thickness direction of the extruded foam and the average cell size (DW: mm) in the width direction of the extruded foam are vertical cross sections in the width direction of the extruded foam (vertical cross sections perpendicular to the extrusion direction of the extruded foam). ), The average cell diameter in the extrusion direction of the extruded foam (DL: mm) is the vertical cross section in the extrusion direction of the extruded foam (vertical cross section parallel to the extrusion direction of the extruded foam and bisected at the center in the width direction) A microscopic enlarged photograph of is obtained. Next, a straight line is drawn in the direction to be measured on the enlarged photograph, the number of bubbles intersecting the straight line is counted, and the length of the straight line (which is naturally the length of the straight line on the enlarged photograph) Rather than refer to the true 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.

  In addition, the measurement of the average cell diameter (DT: mm) in the thickness direction was obtained with three microscopic magnified photographs in the center and both ends of the vertical cross section in the width direction, and the extruded foam in the thickness direction on each photograph. From the length of each straight line and the number of bubbles intersecting the straight line, the average diameter of the bubbles existing on each straight line (length of straight line / number of bubbles intersecting the straight line) is obtained. The arithmetic average value of the obtained average diameters at the three locations is defined as the average cell diameter in the thickness direction (DT: mm).

  The average bubble diameter (DW: mm) in the width direction is obtained by taking a microscopic magnified photograph of a total of three locations in the center and both ends of the vertical cross section in the width 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 (DW: mm)).

  The average cell diameter in the extrusion direction (DL: mm) is a position that bisects the width direction of the extruded foam, and the central part 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 (DL: mm) in the extrusion direction. Moreover, let the average bubble diameter (DH: mm) of the horizontal direction of an extrusion foam be an arithmetic mean value of DW and DL.

  The bubble deformation rate of the extruded foam is a value (DT / DH) calculated by dividing DT obtained by the above measurement method by DH. The smaller the bubble deformation rate is, the flatter the bubble, and the larger the value, the longer the bubble.

  The closed cell ratio of the extruded foam is preferably 85% or more, more preferably 90% or more, and further preferably 93% or more. The higher the closed cell ratio, the higher the heat insulation performance can be maintained.

  The closed cell ratio S (%) of the extruded foam is determined according to ASTM-D2856-70 Procedure C using an air-comparing hydrometer (for example, Toshiba Beckman Co., Ltd., air-comparing hydrometer, model: model 930). Using the true volume Vx of the extruded foam measured by the following method, it can be obtained by the following equation (1).

  In the measurement of the closed cell ratio of the extruded foam, cut 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 each cut sample was used as a measurement sample. The rate was measured, and the arithmetic average value of the closed cell rate at three locations was adopted. 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 )

  The thermoplastic resin constituting the extruded foam plate obtained by the present invention preferably has a dispersed phase structure in which the polystyrene resin (A) forms a continuous phase and the polyester copolymer (B) forms a dispersed phase. Furthermore, from the viewpoint that it is possible to effectively prevent the dissipation of the foaming agent in the foam and the inflow of air into the foam, and it is possible to obtain excellent long-term heat insulation properties, the polyester copolymer (B) is preferably present in a stretched state in the foam film of the extruded foam, and more preferably, a layered dispersion structure is formed.

  In the present invention, the term “layered” means that the polyester copolymer (B) dispersed in the polystyrene resin (A) as shown in FIG. The most of the above is in a state where they are present so as to overlap in a finely stretched state in a direction perpendicular to the thickness direction of the bubble film.

The greater the number of phases of the polyester copolymer (B) in the cell membrane, the greater the effect of reducing the thermal conductivity of the extruded foam. From this viewpoint, specifically, the average number of phases of the polyester copolymer (B) is preferably 3 or more, more preferably 5 or more, and still more preferably with respect to the thickness direction of the cell membrane. 7 or more, particularly preferably 10 or more, and most preferably 20 or more. The upper limit is approximately 50 or less.

  In the extruded foam obtained by the present invention, the polyester copolymer (B) suppresses the inflow of air into the foam, the dissipation of the foaming agent gas from the foam, and the increase in thermal conductivity. Is. For example, it is possible to develop a high degree of heat insulation that satisfies the standards of three types of extruded polystyrene foam heat insulating plates defined in JIS A9511.

The extruded foam preferably has a thermal conductivity of 0.0250 (W / m · K) or less, more preferably 0.0240 (W / m · K) or less after 10 days from manufacture. It is preferable.
From the viewpoint of long-term heat insulation, the thermal conductivity after 100 days of production is preferably 0.0280 (W / m · K) or less, and more preferably 0.0270 (W / m · K) or less. It is preferable that

  In addition, the thermal conductivity of the foam, particularly when a saturated hydrocarbon having 3 to 5 carbon atoms is used as the foaming agent, due to the inflow of air into the foam, the dissipation of the foaming agent gas from the foam, It is known that the thermal conductivity increases immediately after the production of the foam. This increase in thermal conductivity becomes a substantially stable value after 100 days have passed since the foam was produced. Therefore, when judging long-term thermal insulation, it is important not only the initial thermal conductivity immediately after production (or several days later) but also the small increase in thermal conductivity from immediately after production to 100 days after production. Yes, it is necessary to evaluate the thermal conductivity after 100 days from the manufacture.

The thermal conductivity of the extruded foam obtained by the production method of the present invention is measured as follows.
The extruded foam immediately after the production was stored in an atmosphere of 23 ° C. and 50% humidity, and then measured by the following method using the foam after 10 days or 100 days after production. A test piece without an extruded foam skin having a length of 200 mm, a width of 200 mm, and a thickness of 25 mm was cut out from the extruded foam stored by the storage method described above, and the flat plate heat flow described in JIS A 1412-2 (1999) was used for the test specimen. Measurement was performed 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.

  The extruded foam obtained by the production method of the present invention preferably has an air partial pressure of 0.2 atm or less in the bubbles after 10 days of production. Due to the polyester copolymer (B) and its dispersion structure, the extruded foam prevents the C3-C5 saturated hydrocarbon (a) having a lower thermal conductivity than air from escaping into the atmosphere. In addition, it is possible to delay the inflow of air, which becomes a factor for increasing the thermal conductivity of the foam, into the bubbles. Therefore, it is presumed that the air partial pressure in the bubbles is kept low for a longer period than the conventional extruded foam. From the above viewpoint, the air partial pressure after 10 days of production is preferably 0.15 atm or less.

  The thermoplastic resin extruded foam obtained by the production method of the present invention is obtained from the viewpoint of obtaining excellent long-term heat insulation in a category that does not impair flame retardancy. The residual amount of the saturated hydrocarbon having 3 to 5 carbon atoms (a) is preferably 0.01 to 0.95 mol, more preferably 0.1 to 0.9 mol, per 1 kg of the extruded foam. More preferably, it is 0.4-0.9 mol. When the blending amount of the saturated hydrocarbon having 3 to 5 carbon atoms (a) is 0.01 mol or more and less than 1 mol with respect to 1 kg of the thermoplastic resin, the carbon number of the extruded foam obtained is The residual amount of 3 to 5 saturated hydrocarbons (a) is in the above range, the decrease in thermal conductivity is prevented, and long-term heat insulation is easily maintained.

The residual amount of the saturated hydrocarbon (a) having 3 to 5 carbon atoms in the extruded foam obtained by the present invention is such that the extruded foam immediately after production is stored in an atmosphere of 23 ° C. and 50% humidity and 100% after production. It measured with the following method using the extrusion foam after a lapse of days.
The residual amount of the saturated hydrocarbon (a) having 3 to 5 carbon atoms was measured by an internal standard method using a gas chromatograph. Specifically, an appropriate amount of sample was cut out from the extruded foam stored by the above storage method, and this sample was placed in a sample bottle with a lid containing an appropriate amount of toluene and an internal standard substance (cyclopentane), and the lid was closed. Then, gas chromatographic analysis was performed using a solution obtained by sufficiently stirring and dissolving the foaming agent in the extruded foam in toluene as a measurement sample, and the saturated hydrocarbon (a) having 3 to 5 carbon atoms in the extruded foam. The remaining amount can be determined.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the scope of rights of the present invention is not limited to these examples.

Table 1 shows the polystyrene resin (A) used in Examples and Comparative Examples, and Table 2 shows the polyester copolymer (B). Furthermore, the compounding ratio of the thermoplastic resin which consists of a polystyrene resin (A) and a polyester copolymer (B) is shown to Tables 3-5. In Examples and Comparative Examples, the polystyrene resin (A) used was a mixture of PS1 and PS2 shown in Table 2 at the same weight ratio. The melt viscosity (200 ° C., 100 s ⁻¹ ) of this mixed resin (PS1 + PS2) was 1070 Pa · s. Tables 3 to 5 show the ratios of the melt viscosity (ηA) of the polystyrene resin (A) and the melt viscosity (ηB) of the polyester copolymer (B).

  A talc masterbatch containing polystyrene resin (A) as a base resin and 60% by weight of talc (manufactured by Matsumura Sangyo Co., Ltd., trade name: High Filler # 12) was used as the air conditioner.

  A flame retardant masterbatch containing 93% by weight of hexabromocyclododecane was used as the flame retardant.

Examples 1 to 10, Comparative Examples 1 to 3, Reference Examples 1 to 4
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 flat die provided with a resin discharge port (die lip) having a rectangular cross section in the width direction of 1 mm × 90 mm in width is connected to the outlet of the third extruder, and is installed at the resin outlet of the flat die so as to be parallel thereto. The manufacturing apparatus to which the shaping apparatus (guider) comprised with the board which consists of a pair of upper and lower polytetrafluoroethylene was attached was used.

  A thermoplastic resin, a flame retardant, and an air conditioner are supplied to the first extruder so as to have the blending amounts shown in Tables 3 to 5, and heated to 220 ° C. to melt and knead them to obtain a thermoplastic resin. From the blowing agent inlet provided near the tip of the first extruder as a melt, saturated hydrocarbons (a), carbon dioxide (b), and water (c) are shown in Tables 3 to 5, and the composition, ratio As such, the resin melt was supplied and melt-kneaded to obtain a foamable resin melt. The foamable resin melt is supplied to the subsequent second and third extruders, and the resin temperature is shown in the table. The foamed resin temperature is the position of the joint between the extruder and the die. The temperature of the foamable resin melt measured in step 3), and then extruded from the die lip into the guider with the discharge amount shown in Tables 3 to 5 and parallel to the thickness direction of the extruded foam while foaming. The plate-shaped thermoplastic resin extrusion foam was manufactured by shape | molding (shaped) by allowing the inside of the guider arrange | positioned to pass.

The evaluation results such as physical properties of the obtained extruded foam are summarized in Tables 3 to 5.
In the table, i-B represents isobutane and CO2 represents carbon dioxide. In Table 8, in Example 8 and Reference Example 4, since the blending amount of the polyester copolymer (B) was large, the bubble partial pressure and the residual amount of (a) could not be measured.

From the comparison between Examples 1 to 5 and Comparative Example 1, it is understood that excessive bubbles are generated when the amount of water is too large.
In addition, from the comparison between Examples 1 to 5 and Comparative Examples 2 and 3 and the comparison between FIG. 1 (Example 2) and FIG. 2 (Comparative Example 2), a diol component containing a glycol having a cyclic ether skeleton is included. It can be seen that when a polyester copolymer is used, the polyester copolymer is unevenly distributed in the foam film of the extruded foam and excessive bubbles are generated.
From the comparison between Examples 1 to 5 and Reference Examples 1 to 4 and the comparison between FIG. 1 (Example 2) and FIG. 3 (Reference Example 1), a polyester copolymer is obtained when water is not blended. It can be seen that part of (B) tends to be granular.

  The physical properties and evaluation in Tables 1 to 5 were performed as follows.

<Melt viscosity>
The melt viscosity is measured under conditions of a temperature of 200 ° 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 resin sufficiently dried at a temperature lower by 10 ° C. than the glass transition temperature is put in the cylinder and measured after standing for 4 minutes, and the melt viscosity (Pa · s) obtained there is adopted. In the measurement, measurement was performed so that bubbles were not mixed in the strand extruded from the orifice as much as possible.

<Cross sectional area>
The cross-sectional area of the thermoplastic resin extruded foam was a cross-sectional area of a vertical cross section (width direction vertical cross section) orthogonal to the extrusion direction of the extruded foam.

<Air partial pressure>
The partial pressure of air in the foam of the extruded foam is as follows using the extruded foam immediately after production in an atmosphere of 23 ° C. and 50% humidity and using the extruded foam after 10 days from production. It was measured.
From the central part of the extruded foam stored by the above-described storage method, a sample of 90 mm in length, 25 mm in width, and 15 mm in thickness is collected by punching. Next, the sample is put in a container filled with ethanol, and the air in the container is discharged. Next, put toluene in the container so that air is not mixed, dissolve the sample in toluene, measure the volume of air in the bubbles, calculate the volume of bubbles from the volume and weight of the extruded foam, The air partial pressure in the bubbles was determined by dividing the volume by the volume of the bubbles.

<Excessive bubbles>
The presence or absence of excessive bubbles in the extruded thermoplastic resin foam was visually evaluated according to the following evaluation criteria.
(Double-circle): The excessive bubble of 5 mm or more is not seen.
O: One or two excessive bubbles of 5 mm or more exist per 0.3 m ^{3 of} extruded foam (for example, extruded foam of 100 m in the extrusion direction, 200 mm in the width direction and 15 mm in the thickness direction).
X: Three or more excessive bubbles of 5 mm or more exist per extruded foam 0.3 m ³ (for example, extruded foam 100 m × width direction 200 mm × thickness direction 15 mm).

<Morphology>
An ultrathin section was prepared from the extruded foam of a thermoplastic resin, and after dyeing, the morphology in the cross section of the bubble membrane part was visually confirmed with a transmission electron microscope.
Specifically, first, an extruded foam cut out to an appropriate size was placed in an epoxy resin and embedded. After embedding, a surface perpendicular to the thickness direction was cut out with a glass knife or the like, and an ultrathin section of a foam having a thickness of about 0.1 μm was cut out from the cross section with a diamond knife or the like. The cut section (sample) was placed on a Cu mesh and placed in a petri dish with several ml of 2% OsO ₄ aqueous solution, sealed at room temperature, exposed to OsO ₄ vapor, and stained for 30 minutes. Next, the sample was placed in a petri dish together with a solution prepared by mixing several ml of NaClO aqueous solution and a small spatula of RuCl ₃ crystals just before use in a petri dish, exposed to the generated RuO ₄ vapor, and stained for 30 minutes. An ultra-thin section of the stained foam was photographed using a transmission electron microscope. In the photographed electron micrograph, the polystyrene resin (A) portion is observed to be white, and the polyester copolymer (B) portion is observed to be black. As the transmission electron microscope, for example, a transmission electron microscope “JEM-1010” manufactured by JEOL Ltd. can be used.

[Observation conditions]
Transmission electron microscope: Transmission electron microscope “JEM-1010” manufactured by JEOL Ltd.
Acceleration voltage: 100 kV
Dyeing: Ruthenium tetroxide Magnification: 5000 times A: The polyester copolymer (B) forms a dispersed phase throughout the cell membrane.
◯: The polyester copolymer (B) forms a dispersed phase in most of the cell membrane, but a granular part is seen in part.
X: The polyester copolymer (B) is unevenly distributed in a granular form.

1 Cell membrane 2 Polyester copolymer (B)
3 Polystyrene resin (A)

Claims (3)

C 3-5 saturated hydrocarbon (a), carbon dioxide (b), water (c) and a thermoplastic resin are melt-kneaded to obtain a foamable thermoplastic resin melt, and the foamable thermoplastic resin A process for producing a thermoplastic resin extruded foam for extruding and foaming a melt,
The thermoplastic resin comprises a polyester copolymer (B) of a diol component containing 10 to 50 mol% of a glycol having a cyclic ether skeleton and a dicarboxylic acid component, and a polystyrene resin (A), and the polyester copolymer The blending amount of (B) is 5 to 150 parts by weight with respect to 100 parts by weight of the polystyrene resin (A), and the blending amount of water (c) is 0.01 mol with respect to 1 kg of the thermoplastic resin. The manufacturing method of the thermoplastic resin extrusion foam characterized by being less than 1 mol above.
The method for producing an extruded foam of a thermoplastic resin according to claim 1, wherein the polyester copolymer (B) comprises a diol component containing 10 to 50 mol% of spiroglycol and a dicarboxylic acid component.
  The compounding quantity of the said C3-C5 saturated hydrocarbon (a) is 0.01-2 mol with respect to 1 kg of the said thermoplastic resins, The said C3-C5 saturated hydrocarbon (a), carbon dioxide The thermoplastic resin extruded foam according to claim 1 or 2, wherein the total amount of (b) and water (c) is 0.5 to 3 moles relative to 1 kg of the thermoplastic resin. Manufacturing method.