CN109721868B

CN109721868B - Method for producing thermoplastic resin extruded foam sheet

Info

Publication number: CN109721868B
Application number: CN201811284906.5A
Authority: CN
Inventors: 关谷俊介; 桥爪祥辉; 友利格
Original assignee: JSP Corp
Current assignee: JSP Corp
Priority date: 2017-10-31
Filing date: 2018-10-31
Publication date: 2022-12-23
Anticipated expiration: 2038-10-31
Also published as: JP6898829B2; JP2019081855A; KR102671095B1; CN109721868A; KR20190049531A

Abstract

The present invention addresses the problem of providing a method for stably producing a thermoplastic resin extruded foam sheet having superior long-term heat insulation properties as compared with conventional extruded foam sheets. In the method for producing a thermoplastic resin extrusion-foamed sheet, a foamable resin melt obtained by kneading a thermoplastic resin and a physical foaming agent is extrusion-foamed, the thermoplastic resin comprises a polystyrene resin (a), a specific polyethylene terephthalate resin (b), and a mixed resin (c) obtained by kneading a polystyrene resin (c 1) and a specific polyethylene terephthalate resin (c 2), the polystyrene resin (a), the polyethylene terephthalate resin (b), and the mixed resin (c) are blended at a specific ratio, and the blending amount of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) is within a specific range relative to the total blending amount of the polystyrene resin (a) and the polystyrene resin (c 1).

Description

Method for producing thermoplastic resin extruded foam sheet

Technical Field

The present invention relates to a method for producing a thermoplastic resin extruded foam sheet, and more particularly, to a method for producing a thermoplastic resin extruded foam sheet which can be suitably used as a heat insulating material for walls, floors, roofs, and the like of buildings.

Background

A thermoplastic resin extruded foam sheet (hereinafter also referred to as an extruded foam sheet) having a polystyrene resin as a base resin has excellent heat insulating properties and mechanical strength, and therefore an object molded into a sheet shape is widely used as a heat insulating material or the like. Such extruded foam boards are typically manufactured by: the polystyrene resin is heated and melted in an extruder, and then a physical foaming agent is pressed into the obtained melt and kneaded to obtain a foamable molten kneaded product, and the foamable molten kneaded product is subjected to extrusion foaming in a low-pressure region by a die or the like provided at the tip of the extruder, and shaped into a sheet, thereby producing the polystyrene resin.

In the production of such an extruded foam sheet, a hydrocarbon or a hydrofluoroolefin (hereinafter also referred to as HFO) is used as a physical blowing agent. These foaming agents remain in the bubbles and contribute to the improvement of the heat insulation properties of the extruded foam sheet. On the other hand, since the foaming agent is slowly released from the extruded foam sheet, there is a problem that the thermal conductivity of the extruded foam sheet is slowly increased. A technique for preventing the dissipation of a physical blowing agent such as hydrocarbon is disclosed in patent document 1.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-94532.

Disclosure of Invention

Problems to be solved by the invention

Patent document 1 discloses a method for producing an extruded foam sheet, in which a mixed resin of a polystyrene resin and a specific polyethylene terephthalate resin is used as a thermoplastic resin, thereby effectively preventing a foaming agent from escaping from the extruded foam sheet and obtaining an extruded foam sheet capable of maintaining excellent heat insulation properties over a long period of time.

However, in recent years, further improvement in long-term heat insulation has been demanded for foamed sheets. The present invention addresses the problem of providing a method for stably producing a thermoplastic resin extruded foam sheet having superior long-term heat insulation properties as compared with conventional extruded foam sheets.

Means for solving the problems

According to the present invention, there is provided a method for producing a thermoplastic resin extruded foam sheet as described below.

[1]A process for producing an extruded thermoplastic resin foam sheet, which comprises extruding and foaming a molten foamable resin obtained by kneading a thermoplastic resin and a physical foaming agent, wherein the extruded foam sheet has a thickness of 10 to 150mm and an apparent density of 20 to 50kg/m ³ In the above-mentioned manufacturing method, the substrate is,

the thermoplastic resin comprises: a polystyrene-based resin (a); a polyethylene terephthalate resin (b) having a heat of fusion of less than 5J/g (including 0) according to JIS K7122-1987; and a mixed resin (c) obtained by kneading 50 to 95 wt% of a polystyrene resin (c 1) and 5 to 50 wt% of a polyethylene terephthalate resin (c 2) having a heat of fusion of less than 5J/g according to JIS K7122-1987, wherein the total amount of the polystyrene resin (c 1) and the polyethylene terephthalate resin (c 2) is 100 wt%;

the total amount of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) is 10 to 100 parts by weight per 100 parts by weight of the total amount of the polystyrene resin (a) and the polystyrene resin (c 1).

[2] The method for producing a thermoplastic resin extruded foam board according to the above 1, wherein a ratio of a blending amount of the polyethylene terephthalate resin (b) to a blending amount of the polyethylene terephthalate resin (c 2) is 0.5 to 4.

[3]The method for producing a thermoplastic resin extrusion-foamed sheet according to the above 1 or 2, wherein the polystyrene resin (a) has a shear rate of 100s at 200 ℃ and ^-1 under the conditions (c), the melt viscosity (eta a) is 500 to 2500Pa.s, and the shear rate of the polyethylene terephthalate resin (b) is 100s at 200 DEG C ^-1 The ratio (η b/η a) of the melt viscosity (η b) to the melt viscosity (η a) of the polystyrene resin (a) under the condition (1) is 0.4 to 2.

[4]According to the above 3The method for producing the thermoplastic resin extruded foam sheet, wherein the mixed resin (c) has a shear rate of 100s at 200 ℃ and ^-1 the ratio (η c/η a) of the melt viscosity (η c) under the condition (1) to the melt viscosity (η a) of the polystyrene resin (a) is 0.2 to 1.

[5] The method for producing a thermoplastic resin extrusion-foamed sheet according to claim 1 or 2, wherein the mixed resin (c) is a recycled raw material derived from chips and/or pulverized products of a polystyrene-based resin extrusion-foamed sheet containing a polyethylene terephthalate-based resin having a heat of fusion of less than 5J/g (including 0) according to JIS K7122-1987.

[6] The method for producing a thermoplastic resin extruded foam sheet according to the above 1 or 2, wherein the mixed resin (c) is processed into pellets.

Effects of the invention

According to the method for manufacturing a thermoplastic resin extruded foam sheet of the present invention, an extruded foam sheet can be stably manufactured, and an extruded foam heat-insulating panel having excellent long-term heat-insulating properties can be manufactured.

Drawings

FIG. 1 is a photograph of a cross section of pellets of the mixed resin (C) (C-1) used in example 1.

FIG. 2 is a photograph of a cross section of pellets of the mixed resin (C) (C-5) used in example 7.

FIG. 3 is a photograph of a cross section of pellets of the mixed resin (C) (C-7) used in example 9.

FIG. 4 is a photograph showing a cross section (MD cross section; 5000 times) of a bubble film of the extruded foam sheet obtained in example 1.

FIG. 5 is a photograph showing a cross section of a bubble film of the extruded foam sheet obtained in example 1 (TD cross section; 5000 times).

FIG. 6 is a photograph showing a cross section of a bubble film of the extruded foam sheet obtained in example 1 (MD cross section; 20000 times).

FIG. 7 is a photograph showing a cross section of a bubble film of the extruded foam sheet obtained in example 1 (TD cross section; 20000 times).

FIG. 8 is a photograph showing a cross section of a bubble film of the extruded foam sheet obtained in comparative example 1 (MD cross section; 5000 times).

FIG. 9 is a photograph showing a cross section (TD cross section; 5000 times) of a bubble film of the extruded foam sheet obtained in comparative example 1.

FIG. 10 is a photograph showing a cross section of a bubble film of the extruded foam sheet obtained in comparative example 1 (MD cross section; 20000 times).

FIG. 11 is a photograph showing a cross section of a bubble film of an extruded foam sheet obtained in comparative example 1 (TD cross section; 20000 times).

Detailed Description

The method for producing the thermoplastic resin extruded foam sheet of the present invention will be described in detail below.

In the method for producing a thermoplastic resin extruded foam sheet (hereinafter, also simply referred to as an extruded foam sheet) of the present invention, a foamable resin melt containing a specific thermoplastic resin and a physical foaming agent is extruded and foamed through a die provided at an outlet of an extruder, and shaped into a sheet, thereby producing an extruded foam sheet.

The thermoplastic resin used in the present invention comprises a polystyrene-based resin (a), a specific polyethylene terephthalate-based resin (b) (hereinafter also simply referred to as polyethylene terephthalate-based resin (b)), and a specific mixed resin (c). Further, the mixed resin (c) is obtained by kneading the polystyrene resin (c 1) and the specific polyethylene terephthalate resin (c 2) (hereinafter, also simply referred to as polyethylene terephthalate resin (c 2)).

Here, the polystyrene-based resin (a) and the polystyrene-based resin (c 1) are both polystyrene-based resins. The polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) are polyester resins having, as main component units, a terephthalic acid component unit as a dicarboxylic acid component unit and an ethylene glycol component unit as a glycol component unit. The resin (b) and the resin (c 2) are also collectively referred to as a polyethylene terephthalate resin (I).

Next, a description will be given of a polystyrene-based resin used as the polystyrene-based resin (a).

Examples of the polystyrene resin (a) include polystyrene (GPPS), styrene-acrylate copolymers containing styrene as a main component, styrene-methacrylate copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene acrylate copolymers, styrene-methylstyrene copolymers, styrene-dimethylstyrene copolymers, styrene-ethylstyrene copolymers, styrene-diethylstyrene copolymers, and mixed resins of polystyrene and polyphenylene ether. Further, they may be used alone or in combination of 2 or more. The styrene copolymer preferably has a styrene content of 50 mol% or more, and more preferably 80 mol% or more.

Among these polystyrene-based resins, polystyrene, styrene-methacrylate copolymer, styrene-acrylate copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and styrene-maleic anhydride copolymer are preferable.

The polystyrene resin (a) used in the present invention is preferably at a temperature of 200 ℃ and a shear rate of 100s ^-1 The melt viscosity (. Eta.a) under the conditions (1) is from 1500 to 3000Pa.s. The melt viscosity (η a) is more preferably 1600Pa · s or more, and further preferably 1700Pa · s or more. The melt viscosity (η a) is more preferably 2500Pa · s or less, further preferably 2300Pa · s or less, and particularly preferably 2000Pa · s or less. When the melt viscosity (. Eta.a) of the polystyrene resin (a) is within the above range, the polystyrene resin (a), the polyethylene terephthalate resin (b) and the mixed resin (c) are well mixed, and the extrusion moldability in the production of an extrusion-foamed sheet is improved.

Further, the polystyrene resin (a) used in the present invention preferably has a melt tension of 30cN or more at 200 ℃. When the melt tension is within the above range, the melt viscosity suitable for forming the polystyrene resin phase in the cell wall is maintained, and the cells are less likely to be broken during extrusion foaming, so that an extruded foam sheet having a low apparent density and excellent heat insulation properties can be obtained. From the above viewpoint, the melt tension is preferably 35cN or more, and more preferably 40cN or more. The upper limit of the melt tension is about 100cN, preferably 60cN. The Melt Tension (MT) was measured according to ASTM D1238. The Melt Tension (MT) can be measured, for example, by the methods of (donyo seiki) manufacture by (strain) \1246112515\1256412512512512512512521125011d.

Examples of the polystyrene having the specific melt tension include polystyrene resins obtained by polymerizing macromonomers having a branched structure, into which a specific branched structure is introduced in the molecule. Examples of the polystyrene resin include HP780 manufactured by DIC.

Next, the polyethylene terephthalate resin (b) which is a component constituting the thermoplastic resin will be described.

The polyethylene terephthalate resin (b) is a polyethylene terephthalate resin having a heat of fusion (Q) associated with the melting of the resin (hereinafter also simply referred to as heat of fusion (Q)) of less than 5J/g (including 0) as measured in accordance with JIS K7122-1987. The heat of fusion (Q) of the polyethylene terephthalate resin (b) is also referred to as heat of fusion (Qb), and the heat of fusion (Q) of the polyethylene terephthalate resin (c 2) described later is also referred to as heat of fusion (Qc).

The polyethylene terephthalate resin (b) in the present invention is a polyester resin having, as main component units, a terephthalic acid component unit as a dicarboxylic acid component unit and an ethylene glycol component unit as a glycol component unit. In order to control the crystallinity of the polyethylene terephthalate resin (b), other component units may be used.

As the other dicarboxylic acid component of the polyethylene terephthalate resin (b), dicarboxylic acids or ester-forming derivatives thereof can be used. Examples of the ester-forming derivative include ester derivatives such as alkyl esters having about 1 to 4 carbon atoms, salts such as diammonium salts, acid halides such as diacyl chlorides, and the like. Examples of the dicarboxylic acid component unit in the polyethylene terephthalate resin (b) include aromatic dicarboxylic acids such as isophthalic acid, 2, 6-naphthalenedicarboxylic acid, phthalic acid, 4 '-biphenyldicarboxylic acid, 3,4' -biphenyldicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid, 2, 5-naphthalenedicarboxylic acid, and 2, 7-naphthalenedicarboxylic acid, and derivatives thereof such as anhydrides, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, and dodecanedioic acid, and derivatives thereof, and alicyclic dicarboxylic acids such as 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, decahydronaphthalenedicarboxylic acid, and tetrahydronaphthalenedicarboxylic acid. These dicarboxylic acid components may be used alone, or 2 or more thereof may be used.

As the other diol component of the polyethylene terephthalate resin (b), an aliphatic diol, an aromatic diol (including a dihydric phenol), or an ester-forming derivative thereof can be used. Specific examples thereof include aliphatic diols such as propylene glycol, trimethylene glycol, diethylene glycol, 1, 4-butanediol and neopentyl glycol, alicyclic diols such as 1, 4-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol and 1, 6-cyclohexanediol, and aromatic diols such as bisphenol A; or a diol having a cyclic ether skeleton such as 3, 9-bis (1, 1-dimethyl-2-hydroxyethyl) 2,4,8, 10-tetraoxaspiro [5.5] undecane (hereinafter referred to as a spiroglycol) or (1, 1-dimethyl-2-hydroxyethyl) -5-ethyl-5-hydroxymethyl-1, 3-dioxane (hereinafter referred to as a dioxane glycol). These diol components may be used alone, or 2 or more thereof may be used.

Among the above, the polyethylene terephthalate resin (b) preferably contains a diol component unit having a cyclic ether skeleton as another diol component unit. The total amount of the diol component having a cyclic ether skeleton is preferably 10 mol% or more in the diol component, more preferably 15 to 60 mol%, and still more preferably 20 to 50 mol% in the diol component.

Further, the polyethylene terephthalate resin (b) more preferably contains a diol component unit having a cyclic acetal skeleton as another diol component unit. The diol component unit having a cyclic acetal skeleton is preferably spiroglycol or dioxane diol.

Further, the other diol component unit preferably contains at least one selected from the group consisting of a cyclohexanedimethanol component unit and a neopentyl glycol component unit. The content of the alicyclic diol component unit such as cyclohexanedimethanol is preferably 25 to 40 mol% in the diol component.

The degree of crystallinity of the polyethylene terephthalate resin (b) can be adjusted by the following method: a method of using isophthalic acid or the like other than terephthalic acid as a dicarboxylic acid component and changing the molar ratio of the units of these dicarboxylic acid components; and a method of using cyclohexanedimethanol or spiroglycol other than ethylene glycol as the diol component and changing the molar ratio of the units of the diol component.

The polyethylene terephthalate resin (b) can be terminated at the molecular end by a small amount of a constituent unit derived from a monofunctional compound such as benzoic acid, benzoylbenzoic acid, methoxypolyethylene glycol, or the like. Further, a constituent unit derived from a polyfunctional compound such as pyromellitic acid, trimellitic acid, trimesic acid, glycerol, pentaerythritol, or the like may be contained in a small amount.

When the degree of crystallization of the polyethylene terephthalate resin (b) is high and the heat of fusion (Qb) is too high, crystallization of the polyethylene terephthalate resin starts already before the thermoplastic resin is cooled to the foaming temperature in the extruder, and it is difficult to obtain a desired extruded foamed sheet. Herein, the polyethylene terephthalate resin having a heat of fusion of less than 5J/g (including 0) means an amorphous or low-crystalline polyethylene terephthalate resin. From the viewpoint described above, the heat of fusion (Qb) of the polyethylene terephthalate resin (b) is preferably less than 2J/g (inclusive of 0), and more preferably less than 1J/g (inclusive of 0).

The heat of fusion (Q) according to JIS K7122-1987 in the present specification was measured based on the obtained DSC curve by heating a test piece to 300 ℃ at a heating rate of 10 ℃/min using a heat flow type differential scanning calorimetry measuring apparatus (hereinafter referred to as a DSC apparatus), cooling the test piece to 30 ℃ at a cooling rate of 10 ℃/min, adjusting the state of the test piece, heating the test piece to 300 ℃ at a heating rate of 10 ℃/min, and measuring the heat of fusion (Q) based on the obtained DSC curve.

In the invention, the frontThe polyethylene terephthalate resin (b) has a temperature of 200 ℃ and a shear rate of 100s ^-1 The melt viscosity (. Eta.b) under the condition(s) is preferably 1500 to 4000Pa · s. Among the polyethylene terephthalate resins (b) having a melt viscosity within this range, the polystyrene resin (a) and the mixed resin (c) are well mixed, and a polyethylene terephthalate resin phase having excellent gas barrier effect can be easily formed in which the thermoplastic resin constituting the bubble film is oriented in a stripe pattern along the direction of the bubble film. If the melt viscosity (. Eta.b) is too high, the polyethylene terephthalate resin (b) may be dispersed in island-like form or may be formed in a block-like form. On the other hand, if the melt viscosity is too low, the pressure in the die may be reduced in the extruder, or it may be difficult to form a heat insulating plate. Therefore, the lower limit of the melt viscosity (η b) is more preferably 1700Pa · s, and still more preferably 1800Pa · s. The upper limit of the melt viscosity (η b) is more preferably 2500Pa · s, and still more preferably 2300Pa · s.

Next, the mixed resin (c) used in the present invention will be described.

The mixed resin (c) is obtained by kneading a polystyrene resin (c 1) and the polyethylene terephthalate resin (c 2) having a heat of fusion of less than 5J/g (inclusive of 0) according to JIS K7122-1987.

As the polystyrene resin (c 1), polystyrene resins exemplified as the polystyrene resin (a) can be used.

The polyethylene terephthalate resin (c 2) is a polyester resin having, as main component units, a terephthalic acid component unit as a dicarboxylic acid component unit and an ethylene glycol component unit as a glycol component unit. Other constituent units may be used.

For example, the polyethylene terephthalate resin (c 2) preferably contains a diol component unit having a cyclic acetal skeleton such as spiroglycol or dioxane glycol as a diol component unit other than ethylene glycol. From the viewpoint of recyclability, a polyester resin composed of the same dicarboxylic acid component units and the same diol component units as in the polyethylene terephthalate resin (b) is preferred.

In the polyethylene terephthalate resin (c 2), when the degree of crystallization of the polyethylene terephthalate resin (c 2) is also high and the heat of fusion (Qc) thereof is too high, crystallization of the polyethylene terephthalate resin already starts when the thermoplastic resin is cooled to the foaming temperature in the extruder at the time of extrusion, and it is difficult to obtain a desired extruded foamed sheet. From the above viewpoint, the heat of fusion (Qc) of the polyethylene terephthalate resin (c 2) is preferably less than 2J/g (including 0), more preferably less than 1J/g (including 0).

The mixed resin (c) comprises 50 to 95 wt% of the polystyrene resin (c 1) and 5 to 50 wt% of the polyethylene terephthalate resin (c 2) (wherein the total of the polystyrene resin (c 1) and the polyethylene terephthalate resin (c 2) is 100 wt%). If the content of the polyethylene terephthalate resin (c 2) is too small, it is difficult to obtain a desired gas barrier effect for a thermoplastic resin extruded foam sheet, and there is a possibility that the escape of the physical foaming agent from the inside of the cells into the atmosphere cannot be suppressed to a desired extent. On the other hand, if the content of the polyethylene terephthalate resin (c 2) is too large, the polyethylene terephthalate resin (c 2) may not be sufficiently dispersed in the polystyrene resin (c 1) when the mixed resin (c) described later is produced, and as a result, a desired phase structure may not be obtained in the cell film. From the above viewpoint, the lower limit of the content of the polyethylene terephthalate resin (c 2) is preferably 10% by weight, and more preferably 15% by weight. The upper limit of the content is preferably 40% by weight, more preferably 35% by weight. Wherein the total of the polystyrene resin (c 1) and the polyethylene terephthalate resin (c 2) is 100% by weight.

In the present invention, the temperature of the mixed resin (c) is 200 ℃ and the shear rate is 100s ^-1 The melt viscosity (. Eta.c) under the conditions (1) is preferably 400 to 2000Pa · s. When the melt viscosity of the mixed resin (c) is within this range, the polystyrene resin (a) and the polyethylene terephthalate resin (b) can be well mixed and easily formed in the constituent gasThe polystyrene resin of the bubble film is a polyethylene terephthalate resin phase which is oriented in a stripe shape along the direction of the bubble film and has excellent gas barrier effect. From the above-described viewpoint, the lower limit of the melt viscosity (η c) of the mixed resin (c) is more preferably 500Pa · s, still more preferably 550Pa · s, and particularly preferably 600Pa · s. The upper limit of the melt viscosity (η c) is more preferably 1500Pa · s, still more preferably 1200Pa · s, and particularly preferably 1000Pa · s.

In order to satisfy the viscosity range of the mixed resin (c), the temperature of the polystyrene resin (c 1) is 200 ℃ and the shear rate is 100s ^-1 The melt viscosity (. Eta.c 1) under the conditions (1) is preferably 1000 to 2000Pa · s. In addition, the temperature of the polyethylene terephthalate resin (c 2) was 200 ℃ and the shear rate was 100s in the same manner ^-1 The melt viscosity (. Eta.c 2) under the conditions (1) is preferably 1000 to 4000Pa · s.

In the present invention, as described above, a polystyrene resin (a), a polyethylene terephthalate resin (b), and a mixed resin (c) obtained by kneading a polystyrene resin (c 1) and a polyethylene terephthalate resin (c 2) are used. As a result, an extruded foam sheet that can maintain a low thermal conductivity over a longer period of time can be produced, as compared to a conventional extruded foam sheet obtained by merely kneading a polystyrene resin (a) and a polyethylene terephthalate resin (b) and extruding and foaming the kneaded materials. The reason for this can be considered as follows.

The mixed resin (c) can be obtained by kneading a polystyrene resin (c 1) and a polyethylene terephthalate resin (c 2) having a gas barrier property. The photographs of the cross-section of the mixed resin (c) obtained in this manner are shown in FIGS. 1 to 3. As is clear from fig. 1 to 3, in the mixed resin (c), the polyethylene terephthalate resin (c 2) is finely dispersed in the mixed resin (c).

The mixed resin (c) is supplied to an extruder together with the polystyrene resin (a) and the polyethylene terephthalate resin (b) to be heated, melted, kneaded, extruded and foamed, whereby the polyethylene terephthalate resin (I) composed of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) is finely dispersed in the bubble film, and the polyethylene terephthalate resin (I) phase formed in a stripe shape along the direction of the bubble film is easily formed. As a result, the gas barrier property is easily exhibited, and it is considered that a foam board excellent in long-term heat insulation properties is obtained.

Fig. 4 is a photograph showing a cross section of a cell film of an extrusion-foamed sheet obtained by heating, melting, kneading, extrusion-foaming a polystyrene resin (a), a polyethylene terephthalate resin (b), and a mixed resin (c). As is clear from fig. 4, the polyethylene terephthalate resin (I) formed a phase structure in which the polyethylene terephthalate resin (I) was dispersed in stripes along the direction of the cell film.

As shown in fig. 4, in the cross-sectional photograph of the bubble film of the extrusion insulation panel, if a morphology in which a large number of streaky phases formed by the polyethylene terephthalate resin (I) were observed along the longitudinal direction of the bubble film was formed, the physical foaming agent remaining in the bubbles after extrusion foaming was effectively prevented from escaping into the atmosphere. Thus, the physical foaming agent having low thermal conductivity remains in the cells over a long period of time, and the flow of oxygen and nitrogen from the atmosphere into the cells of the extruded foam sheet is suppressed. As a result, it is considered that the thermal conductivity of the extruded foam sheet can be kept low over a longer period of time.

In the following description, the striated phase formed by the polyethylene terephthalate resin (I) observed in the cross-sectional photograph of the bubble film of the extruded heat-insulating board is also simply referred to as "striated phase".

Next, a method for producing the mixed resin (c) will be described.

Examples of the method for producing the mixed resin (c) include the following methods: a method in which the polystyrene resin (c 1), the polyethylene terephthalate resin (c 2), and additives added as needed are supplied to a supply section of an extruder together and kneaded in the extruder; (2) A method of kneading the polystyrene resin (c 1) and the polyethylene terephthalate resin (c 2) with a kneader or the like.

Examples of the method for producing the mixed resin (c) include a method using chips of an extruded foam sheet produced during the production of an extruded foam sheet, and a pulverized product obtained by cutting, crushing, and pulverizing an extruded foam sheet containing the polyethylene terephthalate resin (c 2).

The chips of the extruded foam sheet are generated when the operation of cutting the foam formed into a sheet shape by extrusion foaming to obtain an extruded foam sheet having a desired size is performed in the step of producing the extruded foam sheet. The crushed product of the extruded foam sheet is produced by crushing an extruded foam sheet, a foam sheet piece produced when the extruded foam sheet is formed into a target size, or the like in the step of producing the extruded foam sheet. When the extruded foam board is produced using the polystyrene-based resin (a) and the polyethylene terephthalate-based resin (b) and/or the polyethylene terephthalate-based resin (c 2), chips and/or pulverized products of the extruded foam board and recycled resins obtained by kneading the same can be used as the mixed resin (c).

Specifically, a scrap and/or a pulverized material of an extruded foam sheet obtained through the steps of heating, melting, and kneading in an extruder; in a recycled material derived from the scrap and/or pulverized material of the extruded foam sheet, such as a recycled resin obtained by subjecting the scrap and/or pulverized material of the extruded foam sheet to a recycling step of heating, melting, and kneading, the melt viscosity of the polyethylene terephthalate resin (c 2) contained in the mixed resin tends to decrease. Accordingly, the polyethylene terephthalate resin (c 2) in the polystyrene resin is more likely to be finely dispersed. Therefore, when the recycled raw material is used as the mixed resin (c), the polyethylene terephthalate resin (c 2) is more finely dispersed and easily stretched at the time of extrusion foaming. Therefore, the use of the recycled raw material as the mixed resin (c) is a particularly preferable method for producing an extruded foam sheet.

In the above method, the mixed resin (c) is preferably processed into pellets from the viewpoint of easy handling as a raw material for producing an extruded foam sheet.

Next, the blending ratio of the polystyrene-based resin (a), the polyethylene terephthalate-based resin (b), and the mixed resin (c), the blending amount of the polyethylene terephthalate-based resin (c 2) in the mixed resin (c), and the blending amount of the polyethylene terephthalate-based resin (I) (i.e., the total of the polyethylene terephthalate-based resin (b) and the polyethylene terephthalate-based resin (c 2)) in the thermoplastic resin will be described.

In the present invention, the blending ratio of the polystyrene resin (a), the polyethylene terephthalate resin (b) and the mixed resin (c) constituting the thermoplastic resin is preferably 10 to 80 wt% of the polystyrene resin (a), 5 to 40 wt% of the polyethylene terephthalate resin (b) and 10 to 70 wt% of the mixed resin (c). Wherein the total of the blending proportions of the polystyrene resin (a), the polyethylene terephthalate resin (b) and the mixed resin (c) is 100% by weight. If the blending ratio of the polystyrene-based resin (a) is too low, the extruded foam sheet may not be stably produced, and if the blending ratio is too high, the desired gas barrier effect may not be exhibited. If the blending ratio of the polyethylene terephthalate resin (b) is too low, the desired gas barrier effect may not be exhibited, and if the blending ratio is too high, the extruded foam board may not be stably produced. If the blending ratio of the blend resin (c) is too low, the polyethylene terephthalate resin (I) cannot be finely dispersed in the polystyrene resin to form a phase structure having excellent long-term heat insulation properties, and the desired long-term heat insulation properties may not be exhibited, and it may be difficult to stably form an extruded foam sheet. On the other hand, if the blending ratio is too high, there is a possibility that the extruded foam sheet cannot be stably manufactured.

From the above viewpoint, the compounding ratio is preferably 20 to 70% by weight of the polystyrene resin (a), 7 to 20% by weight of the polyethylene terephthalate resin (b), and 15 to 65% by weight of the mixed resin (c), more preferably 30 to 65% by weight of the polystyrene resin (a), 8 to 18% by weight of the polyethylene terephthalate resin (b), and 25 to 60% by weight of the mixed resin (c), still more preferably 35 to 60% by weight of the polystyrene resin (a), 9 to 16% by weight of the polyethylene terephthalate resin (b), and 30 to 55% by weight of the mixed resin (c). Wherein the total of the polystyrene resin (a), the polyethylene terephthalate resin (b) and the mixed resin (c) is 100% by weight.

The total amount of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) (i.e., the amount of the polyethylene terephthalate resin (I)) is 10 to 100 parts by weight, based on 100 parts by weight of the total amount of the polystyrene resin (a) and the polystyrene resin (c 1). If the amount is too small, the desired gas barrier effect may not be exhibited, and if the amount is too large, the extruded foam sheet may not be stably produced. From the above viewpoint, the lower limit of the amount is preferably 15 parts by weight, more preferably 20 parts by weight, and still more preferably 25 parts by weight. The upper limit of the amount is preferably 80 parts by weight, more preferably 70 parts by weight, still more preferably 60 parts by weight, and particularly preferably 50 parts by weight.

The amount of the polyethylene terephthalate resin (b) is preferably 10 to 40 parts by weight based on 100 parts by weight of the polystyrene resin (a). By setting the blending amount, an extruded foam sheet having excellent gas barrier properties can be produced more stably. From the above viewpoint, the lower limit of the amount is preferably 15 parts by weight, and more preferably 20 parts by weight. The upper limit of the amount is preferably 37 parts by weight, and more preferably 35 parts by weight.

Further, the ratio (b/c 2) of the amount of the polyethylene terephthalate resin (b) to the amount of the polyethylene terephthalate resin (c 2) is preferably 0.5 to 4. The ratio of the amounts to be blended is more preferably 0.7 or more, still more preferably 1.0 or more, and particularly preferably more than 1.0. The upper limit of the ratio of the amounts to be blended is more preferably 3.5, still more preferably 3.0, and particularly preferably 2.0.

When the ratio (b/c 2) of the amounts to be blended is within the above range, the polyethylene terephthalate resin (I) is well dispersed and is appropriately stretched, so that the gas barrier property of the extruded foam sheet can be further improved. Further, when the amount of the polyethylene terephthalate resin (b) is larger than the amount of the polyethylene terephthalate resin (c 2), the gas barrier property of the extruded foam sheet can be further improved, which is more preferable. The reason for this is not clear, but it is considered that the presence of the polyethylene terephthalate resin (c 2) makes it easy for the polyethylene terephthalate resin (b) to be appropriately stretched in the polystyrene-based resin, and a large amount of streaky phases of the polyethylene terephthalate resin (I) containing the polyethylene terephthalate resin (b) are easily formed.

Next, the relationship among the melt viscosities of the polystyrene resin (a), the polyethylene terephthalate resin (b), and the mixed resin (c) will be described. In the present invention, the ratio (η b/η a) of the melt viscosity (η b) of the polyethylene terephthalate resin (b) to the melt viscosity (η a) of the polystyrene resin (a) is preferably 0.4 to 2. The lower limit of the ratio (. Eta.b/. Eta.a) is more preferably 0.6. Further, the upper limit thereof is more preferably 1.5. When the ratio is within this range, the polystyrene resin (a) and the polyethylene terephthalate resin (b) are well mixed, and a striped phase derived from the polyethylene terephthalate resin (b) is easily formed in a cross-sectional photograph of a bubble film extruded from the heat insulating board.

Further, in the present invention, the ratio (η c/η a) of the melt viscosity (η c) of the mixed resin (c) to the melt viscosity (η a) of the polystyrene resin (a) is preferably 0.2 to 1. The lower limit of the ratio (η c/η a) is more preferably 0.25, and still more preferably 0.3. The upper limit of the ratio (η c/η a) is more preferably 0.9, and still more preferably 0.6.

When the ratio is within this range, the polystyrene resin (a), the polyethylene terephthalate resin (b) and the mixed resin (c) are well mixed. In particular, the polyethylene terephthalate resin (c 2) in the mixed resin (c) is well dispersed in the polystyrene resin, and the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) are easily stretched, and a striped phase of the polyethylene terephthalate resin (I) is easily formed in a cross-sectional photograph of a bubble film extruded from the heat insulating board.

In the present invention, by using the polystyrene-based resin (a), the polyethylene terephthalate-based resin (b), and the mixed resin (c) having the melt viscosity within the above-described range, it is possible to form a morphology in which the polyethylene terephthalate-based resin (I) phase capable of exhibiting the above-described gas barrier effect is present as a stripe phase in the polystyrene-based resin. As the morphology, it is preferable that a phase structure in which a plurality of stripe-like phases of the polyethylene terephthalate resin (I) are formed is confirmed in a cross-sectional photograph of a bubble film of the obtained extruded foam sheet, and it is more preferable that a co-continuous phase in which the continuity of the polyethylene terephthalate resin (I) phase is improved and the polyethylene terephthalate resin (I) phase and the polystyrene resin form a continuous phase in the same manner is formed. When the polyethylene terephthalate resin (I) is formed in such a shape, the physical blowing agent remaining in the cells after extrusion foaming is effectively prevented from escaping into the atmosphere. As a result, it is considered that the physical foaming agent having low thermal conductivity remains in the cells over a long period of time, and the flow of oxygen or nitrogen from the atmosphere into the cells of the extruded foam sheet is suppressed, whereby the thermal conductivity of the extruded foam sheet can be maintained in a low state over a long period of time.

In the present invention, other components than the polystyrene resin (a), the polyethylene terephthalate resin (b), the polystyrene resin (c 1) and the polyethylene terephthalate resin (c 2) may be mixed with the thermoplastic resin according to the intended purpose, within a range not to hinder the object of the present invention. Examples of the other components include polyethylene terephthalate resins other than the resin (b) and the resin (c 2), polyolefin resins, and styrene elastomers. The upper limit of the amount of the thermoplastic resin is preferably 30% by weight, more preferably 20% by weight, and particularly preferably 10% by weight, based on 100% by weight of the total amount of the thermoplastic resin constituting the extruded foam sheet.

Next, a physical blowing agent used in the present invention will be described.

As physical blowing agents, organic physical blowing agents and/or inorganic physical blowing agents can be used. Examples of the organic physical blowing agent include saturated hydrocarbons having 3 to 5 carbon atoms, aliphatic alcohols having 1 to 5 carbon atoms, hydrofluoroolefins (HFO), ethers, and alkyl chlorides. Examples of the inorganic physical blowing agent include water, carbon dioxide, and nitrogen. These blowing agents may be used alone or in admixture of 2 or more.

Examples of the saturated hydrocarbon having 3 to 5 carbon atoms include propane, n-butane, isobutane, n-pentane, isopentane, cyclopentane, neopentane, and the like.

As the aforementioned Hydrofluoroolefin (HFO), examples thereof include trans-1, 3-tetrafluoropropene (transHFO-1234 ze), cis-1, 3-tetrafluoropropene (cis HFO-1234 ze) fluorinated unsaturated hydrocarbons such as 1, 2-tetrafluoropropene (HFO-1234 yf) and 2, 3-tetrafluoropropene, and chlorofluorinated unsaturated hydrocarbons such as 1-chloro-3, 3-trifluoropropene. In the method of the present invention, it is preferable that the extruded foam sheet contains at least 1 selected from 1, 3-tetrafluoropropene, 2, 3-tetrafluoropropene, and 1-chloro-3, 3-trifluoropropene since long-term heat insulation is achieved.

Examples of the aliphatic alcohol having 1 to 5 carbon atoms include methyl alcohol (methanol), ethyl alcohol (ethanol), n-propanol, isopropanol, butanol, sec-butanol (isobutanol), tert-butanol, aryl alcohol, crotyl alcohol, propargyl alcohol, n-pentanol, sec-pentanol, isopentyl alcohol, tert-pentanol, neopentyl alcohol, 3-pentanol, 2-methyl-1-butanol, and 3-methyl-2-butanol. Among these, ethanol is preferable because it is excellent in safety to the environment and human body.

Examples of the ethers include dimethyl ether, diethyl ether, ethyl methyl ether, di-n-butyl ether, and diisopropyl ether.

Examples of the alkyl chlorides include methyl chloride and ethyl chloride.

The total amount of 1kg of the thermoplastic resin in the average amount of the physical blowing agent is appropriately selected in accordance with the desired apparent density, and the apparent density is 20 to 50kg/m ³ The amount of the (3) extruded foam sheet is preferably from 0.5 to 3 mol, more preferably from 0.6 to 2.5 mol.

In the present invention, among the above physical blowing agents, a physical blowing agent (α) obtained by combining a saturated hydrocarbon having 3 to 5 carbon atoms, a Hydrofluoroolefin (HFO), an aliphatic alcohol having 1 to 5 carbon atoms, and water is preferable, and the compounding ratio thereof is preferably 20 to 60 mol% of a saturated hydrocarbon having 3 to 5 carbon atoms, 3 to 50 mol% of HFO, 3 to 40 mol% of an aliphatic alcohol having 1 to 5 carbon atoms, and 5 to 50 mol% of water (the total of the compounding ratios of HFO, aliphatic alcohol having 1 to 5 carbon atoms, saturated hydrocarbon having 3 to 5 carbon atoms, and water is 100 mol%).

In the physical blowing agent (. Alpha.), if the blending ratio of the saturated hydrocarbon is in the above range, the apparent density can be reduced without lowering the extrusion stability. Further, an extruded foam sheet having excellent long-term heat insulation properties can be easily obtained without adding a large amount of a flame retardant. Further, the saturated hydrocarbon has high solubility in the polystyrene resin, and therefore can improve extrusion stability, and has a low gas permeation rate in the polystyrene resin, and therefore can keep the thermal conductivity of the extruded foam sheet low over a long period of time. From the above viewpoint, the blending ratio of the saturated hydrocarbon is preferably 25 to 60 mol%, more preferably 30 to 50 mol%.

The amount of the saturated hydrocarbon blended is preferably 0.1 to 3 mol, more preferably 0.2 to 2.5 mol, and still more preferably 0.3 to 2 mol, based on 1kg of the average thermoplastic resin. When the amount is within this range, extrusion foaming can be stably performed, and an extrusion foamed sheet having a desired apparent density can be easily obtained.

The hydrofluoroolefins described above are blowing agents that have zero ozone depletion potential, very low global warming potential, and little environmental impact. Further, since the gas-state heat conductivity is low and the gas-state heat conductivity is hard to burn, the amount of the saturated hydrocarbon used can be reduced and the amount of the flame retardant to be added can be reduced by using the gas-state heat conductivity reducing agent in combination with the saturated hydrocarbon.

If the blending ratio of HFO in the physical blowing agent (α) is within the above range, a large amount of HFO can be left in the cells without causing a decrease in the independent cell ratio, the apparent density or a deterioration in the foamed state of the resulting extruded foam sheet, and thus an extruded foam sheet having excellent long-term heat insulation properties can be obtained. From the above viewpoint, the blending ratio of HFO is preferably 5 to 40 mol%, more preferably 10 to 30 mol%.

The amount of the HFO blended is preferably 0.05 to 0.5 mol/kg, based on 1kg of the average thermoplastic resin. If the amount is within this range, an effective amount of HFO remains in the extruded foam sheet after extrusion foaming, resulting in an extruded foam sheet having long-term thermal insulation properties. From the above viewpoint, the amount of HFO is more preferably 0.1 to 0.4 mol/kg, still more preferably 0.15 to 0.3 mol/kg.

In the physical blowing agent (. Alpha.), if the proportion of the aliphatic alcohol having 1 to 5 carbon atoms is within the above range, the polyethylene terephthalate resin (I) phase having an excellent gas barrier property can be formed while obtaining a desired apparent density.

The aliphatic alcohol having 1 to 5 carbon atoms has a characteristic of specifically improving the plasticity of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2). By this action, the viscosity of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) in the thermoplastic resin with respect to the polystyrene resin is relatively reduced, whereby the stripe-like phase of the polyethylene terephthalate resin (I) composed of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) can be easily formed. From the above viewpoint, the blending ratio of the aliphatic alcohol having 1 to 5 carbon atoms is more preferably 5 to 30 mol%, and still more preferably 8 to 20 mol%.

The amount of the aliphatic alcohol having 1 to 5 carbon atoms blended is preferably 0.05 to 0.3 mol, more preferably 0.07 to 0.28 mol, still more preferably 0.08 to 0.25 mol, and particularly preferably 0.10 to 0.23 mol, based on 1kg of the thermoplastic resin.

In the physical blowing agent (α), the molar ratio (γ/β) of the amount of the hydrofluoroolefin blended (γ) to the amount of the aliphatic alcohol having 1 to 5 carbon atoms blended (β) is preferably 0.3 to 4. When the molar ratio is within the above range, an extruded foam sheet having excellent long-term heat insulation properties can be obtained.

From the above viewpoint, the molar ratio is more preferably 0.5 to 3.5, and still more preferably 1 to 2.

In the case of an extruded foam sheet using a hydrocarbon or HFO as a blowing agent, the blowing agent permeates through a polystyrene resin at a relatively high rate as compared with conventional chlorofluorocarbons, and therefore, the blowing agent tends to escape from the foam at an early stage after extrusion foaming, and the long-term heat insulation properties of the extruded foam sheet tend to be lowered. In contrast, in the extruded foam board obtained by the present invention, by using the mixed resin (c) in which the polyethylene terephthalate resin (c 2) is present in a state of being finely dispersed in the polystyrene resin, the appearance that a large number of stripe-like phases are observed in the bubble film is easily formed in the cross-sectional photograph of the bubble film of the extruded foam board obtained. As a result, the extruded foam sheet obtained by the present invention effectively prevents the escape of the physical foaming agent, particularly HFO, and also prevents the inflow of air from the atmosphere into the cells, thereby forming a foam sheet having superior long-term heat insulation properties as compared with conventional extruded foam sheets.

In the physical blowing agent (α), by using water together with a saturated hydrocarbon, HFO and an aliphatic alcohol, the expansion ratio of the resulting extruded foam sheet is further increased, and the apparent density can be reduced. The mixing ratio of water is preferably 5 to 50 mol% (wherein the total amount of the mixing ratios of HFO, the aliphatic alcohol, the saturated hydrocarbon, and water is 100 mol%). However, an extruded foam sheet can be produced without using water.

When the mixing ratio of water is within this range, it is easy to obtain a desired apparent density and to prevent the extruded foam sheet from deteriorating in the shape of cells, and it is possible to easily obtain an extruded foam sheet excellent in long-term heat insulation properties. From the above viewpoint, the mixing ratio is 10 to 40 mol%, and more preferably 15 to 35 mol%.

Next, additives such as a flame retardant, a flame retardant aid, a heat insulation improving agent, and a bubble adjusting agent used in the present invention will be described.

The thermoplastic resin extrusion-foamed sheet obtained by the present invention is mainly used as a heat insulating sheet for buildings, and therefore preferably satisfies the flammability standard for an extrusion polystyrene foam heat insulating sheet as described in "measurement method a" prescribed in JIS a9511 (2006R) 5, 13, 1. The thermoplastic resin extruded foam sheet satisfying this criterion can be realized by adding a flame retardant in addition to the adjustment of the content of the aforementioned saturated hydrocarbon in the extruded foam sheet.

As the flame retardant which can be blended in the thermoplastic resin extruded foam sheet of the present invention, a bromine-based flame retardant is preferably used. Examples of the bromine-based flame retardant include a brominated bisphenol-based flame retardant, a brominated isocyanurate-based flame retardant, and a brominated butadiene-styrene copolymer-based flame retardant.

The brominated bisphenol flame retardant is a bromide of bisphenol A, bisphenol F, bisphenol S, or a derivative thereof, and includes tetrabromobisphenol A-bis (2, 3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis (2, 3-dibromopropyl ether), and the like.

The brominated isocyanurate-based flame retardant is isocyanuric acid or a bromide of an isocyanuric acid derivative, and includes, for example, isocyanuric acid mono (2, 3-dibromopropyl) ester.

As the brominated butadiene-styrene copolymer, conventionally known ones such as a block copolymer, a random copolymer, and a graft copolymer can be used as they are, and examples thereof include a polystyrene-brominated polybutadiene copolymer. Specifically, commercially available products such as Emerald3000 from Chemtura and FR122P from ICL-IP can be mentioned.

The total amount of the bromine-based flame retardant is appropriately determined in accordance with the desired flame retardancy, and is preferably 1 to 10 parts by weight, more preferably 2 to 8 parts by weight, per 100 parts by weight of the thermoplastic resin, in order to obtain an extruded polystyrene resin foam satisfying the flammability standard of an extruded polystyrene foam insulation board according to JIS a9511 (2006R). When the total amount of the components is within the above range, the flame retardant does not inhibit the foamability and an extruded foam having a good surface state is obtained.

The flame retardant may contain other flame retardants in addition to the brominated bisphenol flame retardant, the brominated isocyanurate flame retardant, and the brominated butadiene-styrene copolymer flame retardant. The amount of the other flame retardant to be added is preferably 20% by weight or less, more preferably 10% by weight or less, based on the total amount of the flame retardant to be added.

As a method for blending the flame retardant into the thermoplastic resin, a method of supplying a predetermined proportion of the flame retardant together with the thermoplastic resin to a supply part provided upstream of an extruder and kneading the mixture in the extruder can be employed. In addition, a method of supplying the flame retardant to the molten thermoplastic resin from a flame retardant supply section provided in the middle of the extruder may be employed. When the flame retardant is supplied to the extruder, a method of supplying the extruder with a mixture obtained by dry-blending the flame retardant and a polystyrene resin or the like constituting the thermoplastic resin; a method of producing a flame retardant master batch, melt-kneading the flame retardant, and feeding the melt-kneaded product to an extruder together with a thermoplastic resin. In particular, from the viewpoint of dispersibility, a method of preparing a flame retardant master batch and supplying it to an extruder is preferably employed.

In the extruded foam sheet of the present invention, stabilizers such as hindered phenol stabilizers, phosphorus stabilizers, and hindered amine stabilizers may be added to the thermoplastic resin. These stabilizers capture halogen radicals and halogen ions generated by decomposition of the brominated flame retardant during processing, and thereby can suppress the reduction in molecular weight and the coloration of the polystyrene resin.

Further, as the flame retardant auxiliary, a thermoplastic resin may be blended with a diphenylalkane such as 2, 3-dimethyl-2, 3-diphenylbutane or 2, 3-diethyl-2, 3-diphenylbutane, a diphenylolefin such as 2, 4-diphenyl-4-methyl-1-pentene or 2, 4-diphenyl-4-ethyl-1-pentene, a polyalkylbenzene such as poly-1, 4-diisopropylbenzene, a triphenyl phosphate, tolylbis (2, 6-xylyl) phosphate, antimony trioxide, antimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam (melam), a nitrogen-containing cyclic compound such as melem, a silicone compound, an inorganic compound such as boron oxide, zinc borate or zinc sulfide, a phosphorus compound such as a red phosphorus compound, a polyphosphate, a phosphazene, or a hypophosphite. These compounds may be used alone or in combination of 2 or more.

In the extruded foam sheet of the present invention, the heat insulating property can be further improved by adding a heat insulating property improving agent to the thermoplastic resin as the base resin. Examples of the heat-shielding property improving agent include metal oxides such as titanium oxide, metals such as aluminum, ceramics, carbon black, fine powders of graphite and the like, infrared shielding pigments, hydrotalcite and the like. These may be used in 1 or 2 or more. The amount of the heat insulation improver added is preferably from about 0.5 to 10 parts by weight, more preferably from 1 to 8 parts by weight, per 100 parts by weight of the thermoplastic resin.

In the present invention, various additives such as a bubble control agent, a colorant such as a pigment or a dye, a heat stabilizer, and a filler may be appropriately blended with the base resin as necessary.

Examples of the air-bubble controlling agent include inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, alumina, clay, bentonite and diatomaceous earth, and conventionally known chemical foaming agents such as azodicarboxylic acid diamide. Among them, talc is suitable because it does not inhibit flame retardancy and can easily adjust the bubble diameter. The amount of the bubble adjuster to be added varies depending on the type of the bubble adjuster, the target bubble diameter, and the like, and is preferably about 0.01 to 8 parts by weight, more preferably 0.01 to 5 parts by weight, and particularly preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the thermoplastic resin.

The cell regulator is preferably used in the form of a master batch from the viewpoint of dispersibility. Preparation of the master batch for the air bubble controlling agent, for example, when talc is used as the air bubble controlling agent, the master batch is preferably prepared so that the content of the talc is 20 to 80% by weight, more preferably 30 to 70% by weight, based on the base resin.

Hereinafter, various physical properties of the thermoplastic resin extruded foam sheet obtained by the present invention will be described in detail.

In the extruded foam sheet obtained by the present invention, the thermoplastic resin constituting the cell film is composed of a polystyrene resin and a polyethylene terephthalate resin having, as main component units, a terephthalic acid component unit as a dicarboxylic acid component unit and an ethylene glycol component unit as a glycol component unit. Further, according to the present invention, the polyethylene terephthalate resin (I) phase composed of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) is inhibited from dispersing in island-like and/or block-like shapes, and the polyethylene terephthalate resin (I) phase can be dispersed by stretching the bubble film in stripe-like shapes, so that the polyethylene terephthalate resin (I) phase capable of exhibiting a gas barrier effect can be formed in the cross section of the bubble film of the polystyrene resin. The polyethylene terephthalate resin (I) phase was confirmed as a plurality of striped phases in a cross-sectional photograph of a bubble film of an extruded foam board. The polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) were difficult to distinguish after melt kneading, and were observed as a polyethylene terephthalate resin (I) phase in the extruded foam sheet.

In the present specification, the phrase "polyethylene terephthalate resin (I)" in the form of stripes observed in the cross-sectional photograph of the bubble film means that the polyethylene terephthalate resin (I) is present in the form of a line or a band in the direction along the bubble film (the longitudinal direction of the bubble film, the direction perpendicular to the thickness direction of the bubble film) in the cross-sectional photograph.

The polyethylene terephthalate resin (I) phase suppresses the intrusion of air into the bubble film, and suppresses the escape of a physical blowing agent such as hydrofluoroolefin into the atmosphere. Therefore, the increase in thermal conductivity of the extruded foam sheet can be suppressed, and the thermal conductivity can be suppressed to be low over a long period of time. Further, in the extruded foam sheet obtained by the present invention, by forming the specific polyethylene terephthalate resin (I) phase, the inflow of air into the cells is effectively suppressed.

The apparent density of the extruded foam board obtained by the invention is 20 to 50kg/m ³ . When the apparent density is too small, it becomes difficult to produce the extruded foam sheet itself, and the extruded foam sheet having insufficient mechanical strength is formed depending on the use. On the other hand, when the apparent density is too high, it is difficult to exert sufficient heat-insulating properties, and further, the lightweight property is exhibitedIs also not preferable from the viewpoint of (b). From the viewpoint described above, the lower limit of the apparent density is preferably 25kg/m ³ The upper limit is preferably 45kg/m ³ 。

The thickness of the extruded foam board is 10 to 150mm. If the thickness is too thin, the thermal insulation required particularly for use as a thermal insulation material may become insufficient. On the other hand, the thickness of the extruder varies depending on the size of the extruder, but if the thickness is too large, foaming extrusion molding may become difficult. The lower limit of the thickness is more preferably 15mm, and the upper limit thereof is more preferably 120mm.

The average diameter of the cells in the thickness direction of the extruded foam sheet is preferably 0.05 to 2mm. The lower limit thereof is more preferably 0.06mm. The upper limit is more preferably 0.7mm, and still more preferably 0.3mm. By setting the average cell diameter in the thickness direction within the above range, infrared transmission can be suppressed in cooperation with the configuration within the apparent density range, and an extruded foam sheet having more excellent heat insulation properties can be easily obtained.

The method for measuring the average bubble diameter in the present specification is as follows.

In the measurement of the average cell diameter in the thickness direction (DTav) and the average cell diameter in the width direction (DWav), first, at a total of 3 locations in the vicinity of the central portion and both end portions of the transverse cross section of the extruded foam sheet, the magnification was adjusted in a range of about 50 to 200 times so that the number of cells in the photograph was about 200 to 500, and an enlarged photograph was obtained. Next, on each photograph, using image processing software NS2K-pro manufactured by\1249094124718612512m, the fisher diameter in the thickness direction and the fisher diameter in the width direction of each bubble were measured. Then, these values are arithmetically averaged to obtain the average bubble diameter in the thickness direction (DTav) and the average bubble diameter in the width direction (DWav).

The average bubble diameter (DLav) in the extrusion direction was measured as follows. First, the extruded foam sheet was cut along the extrusion direction at a position bisecting the width direction of the extruded foam sheet to obtain an extrusion direction vertical section, and 3 portions of the extrusion direction vertical section were randomly obtained from a microscope micrograph. Then, on each photograph, fisher's diameter of the extrusion direction of each bubble was measured using image processing software NS2K-pro manufactured by \1249094 \\12471124861252. Next, by arithmetically averaging these values, the average bubble diameter (DLav) in the extrusion direction can be obtained.

The average cell diameter DH in the horizontal direction of the extruded foam sheet was set to the arithmetic average of DWav and DLav.

In the extruded foam sheet obtained by the present invention, the bubble deformation ratio is preferably 0.7 to 2.0. The bubble deformation ratio is a value (DT/DH) calculated by dividing DT obtained by the above-described measurement method by DH, and the smaller the bubble deformation ratio is compared with 1, the flatter the bubble (horizontally long shape), and the larger the bubble deformation ratio is compared with 1, the longer the bubble is. When the cell deformation ratio is too small, the cells are flattened, and therefore the compressive strength may be lowered, and the flattened cells have a strong tendency to return to a spherical shape, and therefore the dimensional stability of the extruded foam sheet may be lowered. If the cell deformation rate is too large, the number of cells in the thickness direction decreases, and therefore the effect of improving the heat insulation performance due to the shape of the cells decreases. From such a viewpoint, the lower limit of the bubble deformation ratio is more preferably 0.8. The upper limit is preferably 1.5, more preferably 1.2. When the cell deformation ratio is in the above range, a thermoplastic resin extruded foam sheet having excellent mechanical strength and higher heat insulation properties is formed.

The isolated cell ratio of the extruded foam sheet obtained by the present invention is preferably 85% or more, more preferably 90% or more, further preferably 92% or more, and particularly preferably 93% or more. As the independent bubble ratio is higher, a physical blowing agent such as HFO can stay in the bubbles for a longer period of time, and a high heat insulating performance can be maintained over a long period of time. The independent bubble rate S (%) was measured according to procedure C of ASTM-D2856-70 using an air comparison type densitometer (e.g., toshiba, model 125051248312463, model 1251031310, manufactured by Toshiba, inc.; model 930).

Further, the thermoplastic resin extruded foam sheet obtained by the present invention is expected to satisfy the standard of thermal conductivity specified in JIS a9511 (2006R) 4.2.

Further, the thermal conductivity of the extruded foam sheet obtained by the present invention after 1 day from the production is preferably 0.0270W/(m · K) or less, more preferably 0.0260W/(m · K) or less, and further preferably 0.0250W/(m · K) or less. When the thermal conductivity is within this range, an extruded foam sheet having excellent heat insulation properties and suitable for building material applications is formed. Further, the extruded foam sheet is excellent in heat insulating properties over a long period of time, and the thermal conductivity after 100 days has elapsed after the production is preferably 0.0265W/(m · K) or less, and more preferably 0.0260W/(m · K) or less. In the extrusion foamed sheet obtained by the present invention, the polystyrene-based resin (a), the polyethylene terephthalate-based resin (b), and the mixed resin (c) are used as thermoplastic resins at specific ratios to perform extrusion foaming, and therefore, the polyethylene terephthalate-based resin (I) phase having the morphology that exhibits the gas barrier effect is formed in the bubble film. Therefore, the aforementioned HFO is effectively prevented from escaping from the extruded foam sheet and flowing into the air bubbles, and the thermal conductivity is maintained low even after 100 days have passed after the manufacture.

Examples

The present invention is specifically described below by way of examples and comparative examples. However, the present invention is not limited to these examples.

The polystyrene-based resins used in examples and comparative examples are shown below.

As the polystyrene resin (a) and the polystyrene resin (c 1), resins 1 and 2 were used, which were prepared by blending polystyrene 1 (PS 1), polystyrene 2 (PS 2) and polystyrene 3 (PS 3) shown below in the weight ratios shown below.

Polystyrene resin

Resin 1: polystyrene 1

Resin 2: polystyrene obtained by mixing polystyrene 1 and polystyrene 2 in a weight ratio of 26

The melt viscosity of pellets obtained by melt-kneading the resin 2 at 200 ℃ was determined (200 ℃ C., 100 s) ^-1 ) Is 1000 pas.

Resin 3: polystyrene 3

(1) Polystyrene 1 (PS 1): DIC having the name HP780, melt viscosity (temperature 200 ℃ C., shear)Speed 100s ^-1 ) =1946Pa · s, melt tension (200 ℃) =45cN

(2) Polystyrene 2 (PS 2): PS\1247212515\ 1253197, manufactured by Kogyo corporation under the brand name 679, melt viscosity (temperature 200 ℃, shear rate 100 s) ^-1 ) =673Pa · s, melt tension (200 ℃) =3cN

(3) Polystyrene 3 (PS 3): grade name HP600ANJ, manufactured by DIC corporation, melt viscosity (temperature 200 ℃, shear rate 100 s) ^-1 ) =1424Pa · s, melt tension (200 ℃) =18cN.

As the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2), SPET1, SPET2, and PETG1 shown below were used.

SPET1: mitsubishi gas chemical company, grade name S3002, melt viscosity (temperature 200 ℃ C., shear rate 100S) ^-1 ) =3500Pa · s, melt tension (200 ℃) =3cN, heat of fusion =0J/g

SPET2: mitsubishi gas chemical, grade name S3012, melt viscosity (temperature 200 ℃ C., shear rate 100S) ^-1 ) =2000Pa · s, melt tension (200 ℃) =3cN, heat of fusion =0J/g

PETG1: polyethylene terephthalate resin heat-treated and thermally modified by an extruder under a rating name GN001 manufactured by 1251112459, a melt viscosity (temperature 200 ℃, shear speed 100 s) ^-1 ) =1800Pa · s, heat of fusion =0J/g.

Air bubble regulator

Talc master batch MB6S containing 60 wt% of talc (manufactured by songwar industries, ltd.: 1245295125011241255112.

Flame retardant

A flame retardant in which (i) tetrabromobisphenol-a-bis (2, 3-dibromo-2-methylpropyl ether) (SR 130 manufactured by first industrial pharmaceutical preparation) and (ii) tetrabromobisphenol-a-bis (2, 3-dibromopropyl ether) (SR 720 manufactured by first industrial pharmaceutical preparation) were mixed in a weight ratio of 3.

Graphite

V. using (v) manufactured by (v) 125247212494124591252140: SBF-T-6526.

Titanium oxide

Manufactured by Nippon hong, 12412499, 124831246373: PS-ET2813.

Physical foaming agent

The following (1) to (4) were used as physical blowing agents.

(1) Saturated hydrocarbons having 3 to 5 carbon atoms: isobutane (abbreviated as "i-Bu")

(2) HFO: trans-1, 3-tetrafluoropropene (HFO-1234 ze)

(3) An aliphatic alcohol having 1 to 5 carbon atoms: ethanol

(4) And (3) water.

Production of Mixed resin (c)

(1) Resin pellets "C-1", "C-2", "C-3" and "C-4"

Polystyrene resin (c 1) of the type and composition shown in table 1, polyethylene terephthalate resin (c 2) of the type and composition shown in table 1, and graphite, titanium oxide, a flame retardant and a cell regulator of the type and composition shown in table 1 were supplied to an extruder described later, and each physical foaming agent was further supplied from a physical foaming agent supply port, and heated, melted, kneaded, extruded and foamed to produce a polystyrene resin extruded foam sheet. The conditions for extrusion are the same as those for producing an extruded foam sheet of example 1 described later. The extruded foam sheet was pulverized, supplied to an extruder, heated, melted, kneaded, and extruded into a strand shape at the heating and melting temperature shown in table 1. The extruded strand was water-cooled and cut with a pelletizer to obtain resin pellets "C-1", "C-2", "C-3" and "C-4" of the mixed resin (C).

[ TABLE 1 ]

。

(2) Resin pellets "C-5", "C-6" and "C-7"

Polystyrene resin (c 1) of the type and composition shown in table 1 and polyethylene terephthalate resin (c 2) of the type and composition shown in table 1 were fed to an extruder, heated, melted, kneaded, and extruded into a strand shape at the heating and melting temperature shown in table 1. The extruded strand was water-cooled and cut with a pelletizer, thereby obtaining resin pellets "C-5". Next, the resin pellet "C-5" was again (second time) supplied to the extruder, heated, melted, kneaded, and extruded into a strand shape at the heating and melting temperature shown in table 1. The extruded strand was water-cooled and cut with a pelletizer, thereby obtaining resin pellets "C-6". Next, the resin pellet "C-6" was supplied to the extruder again (third time), heated, melted, kneaded, and extruded into a strand shape at the heating and melting temperature shown in table 1. The extruded strand was water-cooled and cut with a pelletizer, thereby obtaining resin pellets "C-7".

Device for measuring the position of a moving object

A manufacturing apparatus was prepared in which a1 st extruder having an inner diameter of 65mm and a 2 nd extruder having an inner diameter of 90mm were connected in series, a blowing agent injection port was provided near the end of the 1 st extruder, a flat die having a resin discharge port (die lip) with a rectangular cross section (gap 1 mm. Times. Width 115 mm) in the width direction was connected to the outlet of the 2 nd extruder, and a shaping device (guide) provided with a pair of upper and lower plates made of polytetrafluoroethylene resin was additionally provided to the resin discharge port of the flat die. In the guide, a pair of upper and lower polytetrafluoroethylene resin plates are arranged in parallel with a gap of 25mm in the thickness direction of the foam board, thereby forming a passage with a gap of 25mm in the upper and lower directions.

Examples 1 to 9 and comparative examples 1 to 3

The resin, the flame retardant, the cell regulator, graphite, and titanium oxide were fed to the first extruder 1 so as to attain the respective blending amounts shown in table 2. Then, they were heated to 220 ℃ and melted and kneaded to prepare a resin melt, and a physical blowing agent having a composition shown in table 2 was supplied to the melt at a ratio shown in the table from a blowing agent injection port provided near the tip of the 1 st extruder, and melted and kneaded to prepare a foamable resin melt. The foamable resin melt was then transferred to the 2 nd extruder and the 3 rd extruder, the resin temperature was adjusted to a temperature suitable for foaming as shown in the table (expressed as an extruded resin temperature in the table; the foaming temperature is a temperature of the foamable resin melt measured at a position of a joint portion of the extruder and the die), and the foamable resin melt was extruded from the die lip into the guide at a discharge rate of 70kg/hr, and molded (shaped) into a plate shape by passing the foam through the passage of the guide. Thus, a thermoplastic resin extruded foam sheet having a thickness of 28mm was obtained. The physical properties and evaluation of the resulting extruded foam sheet are shown in Table 2.

[ TABLE 2]

。

In example 1, a thermoplastic resin containing 43 wt% of a polystyrene-based resin shown in table 2, 13 wt% of a polyethylene terephthalate-based resin (b) shown in table 2, and a mixed resin (C) "C-1" shown in table 1 was used, and isobutane, HFO, ethanol, and water were mixed and used as a physical blowing agent in the formulation shown in table 2. When a cross-sectional photograph of the resulting extruded foam sheet was taken with an electron microscope, it was confirmed that the polyethylene terephthalate resin (I) formed a plurality of striped phases in the polystyrene resin and further the polystyrene resin and the polyethylene terephthalate resin (I) formed a co-continuous phase in the cross-section of the bubble film as shown in fig. 4.

As is clear from the values of the thermal conductivity in table 2, the obtained extruded foam sheet has a small change in thermal conductivity with time, and is excellent in long-term heat insulation properties.

An extrusion foam board was obtained in the same manner as in example 1 except that in example 2, a mixed resin (C) "C-2" was used instead of the mixed resin (C) "C-1". As is clear from table 2, the obtained extruded foam sheet has a small change in thermal conductivity with time, and is excellent in long-term heat insulation properties.

An extrusion foam board was obtained in the same manner as in example 1 except that in example 3, a mixed resin (C) "C-3" was used in place of the mixed resin (C) "C-1". As is clear from table 2, the obtained extruded foam sheet has a small change in thermal conductivity with time, and is excellent in long-term heat insulation properties.

Example 4 is an example in which the blending ratio of the polystyrene resin (a), the polyethylene terephthalate resin (b), and the mixed resin (c) was changed. Since the blending ratio of the mixed resin (c) is small, the effect of forming the polyethylene terephthalate resin (I) phase is small, and the thermal conductivity after 1 day and 100 days after the production becomes large as compared with example 1.

Example 5 is an example in which the blending ratio of the polystyrene resin (a), the polyethylene terephthalate resin (b), and the mixed resin (c) was changed. The mixed resin (c) is blended in a large proportion, and the thermal conductivity after 1 day and 100 days after the production becomes large as compared with example 1.

Example 6 is an example in which PET-G was used as the polyethylene terephthalate resin (b). It is found that when PET-G is used, the change of the thermal conductivity with time is small and the long-term heat insulation property is improved as compared with comparative example 3 in which the mixed resin (c) is not used.

On the other hand, in comparative example 1, as shown in Table 2, an extrusion foamed sheet was produced using a thermoplastic resin containing 77 wt% of a polystyrene-based resin "resin 2" and 23 wt% of a polyethylene terephthalate-based resin (b) but not containing a mixed resin (c). When only the polyethylene terephthalate resin (b) as a virgin raw material is used and the mixed resin (c) is not used, the dispersion state of the polyethylene terephthalate resin (I) is deteriorated, and the polyethylene terephthalate resin (I) is less likely to be stretched, and the linear structure of the polyethylene terephthalate resin (I) tends to be reduced (fig. 8 to 11). In addition, comparing the difference in thermal conductivity between 1 day after manufacture and 100 days after manufacture with the examples, it is clear that the thermal conductivity of the extruded foam sheet of the comparative example greatly changes with time.

Comparative example 2 is an example in which the mixed resin (C) "C-1" was not used in comparison with example 1. When a thermoplastic resin not blended with the mixed resin (c) is used, it is difficult to stably produce a good extruded foam sheet.

Comparative example 3 is an example in which PET-G was used as the polyethylene terephthalate resin (b) and the mixed resin (c) was not used. As compared with example 6, the change in thermal conductivity with time was large, and the long-term heat insulation property was lowered.

Example 7 is an example in which, as the mixed resin (C), a mixed resin (C) "C-5" obtained by heating, melting, and kneading virgin raw materials by the method shown in table 1 was used instead of the recycled raw material (recycled resin) of the foam board. In the photograph of the cross section of the pellet of the mixed resin (C) "C-5" subjected to 1 heat-melting treatment, as shown in FIG. 2, the polyethylene terephthalate resin (C2) was already finely dispersed in the polystyrene-based resin and formed a striped phase. Therefore, the change of thermal conductivity with time is small, and the long-term heat insulation property is most excellent.

Examples 8 and 9 are examples in which the mixed resins (C) "C-6" and "C-7" obtained by increasing the number of heat treatments were used in comparison with example 7. At this time, as shown in fig. 3, a photograph of a cross section of the pellets of the mixed resin (c) was taken, and although the pellets were finely dispersed by the heat treatment, the streak-like phase was gradually interrupted, and therefore the long-term heat insulation property was lowered as compared with example 7. Therefore, it is found that the number of heat treatments is preferably small in the production of the recycled resin.

The physical properties in the table were measured as follows.

(melt viscosity)

The melt viscosity was measured using a 125615 manufactured by toyoyo seiko corporation, 1256412512521125011D at a temperature of 200 ℃ and a shear rate of 100s ^-1 Under the conditions of (1). Specifically, a cylinder having a cylinder diameter of 9.55mm and a length of 350mm and an orifice having a nozzle diameter of 1.0mm and a length of 10.0mm were prepared. Next, the resin which was sufficiently dried by a hot air circulation dryer at a temperature 10 ℃ lower than the glass transition temperature was charged into the cylinder with the set temperature of the cylinder and the orifice set at 200 ℃, and the melt viscosity was measured after leaving for 4 minutes, and the value obtained here was used as the melt viscosity (Pa · s). The measurement is performed so that as few as possible air bubbles are mixed in the resin strand extruded from the orifice at the time of measurement.

When the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) were measured, it took 12 hours to dry the resins in a vacuum oven at 80 ℃.

(apparent Density)

Measurement of apparent density in accordance with JIS K7222: 1999.

(independent bubble ratio)

In the present specification, the isolated cell percentage of the extruded foam sheet is determined by measuring the isolated cell percentage of each sample by the procedure C of ASTM-D2856-70 and calculating the arithmetic average value (5 points or more) of the measured values by the following formula (1). Cut samples were cut from a total of 3 portions in the vicinity of the central portion and both ends in the width direction of the extruded foam sheet, each cut sample was used as a measurement sample, the independent cell ratio was measured for each measurement sample, and the arithmetic average of the independent cell ratios of the 3 portions was used. The cut sample was a sample which was cut from an extruded foam board to a size of 25mm in length × 25mm in width × 20mm in thickness and had no skin of the extruded foam board.

S(%)=(Vx-W/ρ)×100/(VA-W/ρ) (1)

Wherein, vx: the true volume (cm) of the cut sample determined by the measurement with the air comparison type densitometer ³ ) (corresponding to the sum of the volume of the resin constituting the cut sample of the extruded foam board and the total volume of the cells in the isolated cell portions in the cut sample.)

VA: apparent volume (cm) of cut sample calculated from outer size of cut sample used in measurement ³ )

W: total weight of cut sample used in the determination (g)

ρ: density (g/cm) of base resin constituting extruded foam sheet ³ )。

(average bubble diameter in thickness direction)

The average cell diameter (DTav) in the thickness direction was measured by the aforementioned method. First, a magnified photograph of the extruded foam was obtained at a magnification of 50 times for the total of three portions in the vicinity of the center and both ends of the cross section perpendicular to the width direction. On each photograph, using image processing software NS2K-pro manufactured by\1249012494124718612512K, the thickness direction and the width direction of each bubble were measured, and the values were arithmetically averaged to thereby obtain the average bubble diameter (DTav) in the thickness direction. The cell deformation ratio of the foam sheet was calculated by dividing the cell diameter in the width direction obtained by the method described above by the cell diameter in the thickness direction.

(photographs of the cross-sections of the cell films of the extruded foam sheet in the MD and TD directions, and of the pellets of the mixed resin (c))

First, a foam cut out in an appropriate size from the central portion of the extruded foam sheet is embedded in an epoxy resin. After the embedding, a plane perpendicular to the thickness direction (MD section) or a plane perpendicular to the extrusion direction (TD section) was cut out of the foam with a glass knife, and an ultra-thin section of the foam having a thickness of about 0.1 μm was cut out from the section with a diamond knife. The cut sections (samples) were placed on a Cu mesh, and then placed in a petri dish together with 2% by volume of an oso4 aqueous solution of several ml, sealed at room temperature, exposed to OsO4 vapor, and stained for 30 minutes. Next, the sample was added to a petri dish together with a solution obtained by mixing several ml of a NaClO aqueous solution and a small spoon of 1 spoon of RuCl3 crystals just before use, sealed at room temperature, exposed to the generated RuO4 vapor, and subjected to staining for 30 minutes. Ultra-thin sections of the dyed foam were photographed using a transmission electron microscope. In the electron micrograph taken, the white portion was a polystyrene-based resin, and the black portion was a polyethylene terephthalate-based resin (I). The transmission electron microscope used herein is a transmission electron microscope "JEM-1010" manufactured by Nippon Electron Co., ltd.

Further, the central part of the pellet of the mixed resin (c) was cut out in an appropriate size and embedded in the epoxy resin. After the embedding, a photograph (magnification: 5000 times) of a cross section of a plane (MD cross section) parallel to the extrusion direction of the pellet of the mixed resin (c) was taken in the same manner as in the extrusion of the foam.

[ photographing conditions ]

Transmission electron microscope: transmission Electron microscope "JEM-1010" manufactured by Japan Electron Ltd "

Acceleration voltage: 100kV

Dyeing: ruthenium tetroxide

Multiplying power: 5000 times and 20000 times.

(phase State of polyethylene terephthalate resin (I))

The morphology of the polyethylene terephthalate resin (I) was visually observed using a cross-sectional photograph of the bubble film of the extruded foam board, and evaluated according to the following criteria.

Very good: in the cross section of the bubble film, the polyethylene terephthalate resin (I) forms a plurality of striped phases, and the polyethylene terephthalate resin (I) is well stretched.

O: in the cross section of the bubble film, the polyethylene terephthalate resin (I) forms a plurality of striped phases, but a part of the polyethylene terephthalate resin (I) is not sufficiently stretched and a thick phase exists.

X: in the cross section of the cell membrane, the polyethylene terephthalate resin (I) forms a block phase.

(thermal conductivity, difference in thermal conductivity)

The thermal conductivity of the extruded foam sheet immediately after the production was measured by the following method after the sheet was stored in an atmosphere of 23 ℃ and a humidity of 50% for 1 day and further 100 days, and the thermal conductivity 1 day after the production and the thermal conductivity 100 days after the production were determined.

A test piece having no skin was cut out from the extruded foam sheet in a length of 200mm × thickness of 10mm, and the thermal conductivity was measured on the test piece by a flat heat flow meter method (heat flow meter 2-piece method, high temperature side 38 ℃, low temperature side 8 ℃, average temperature 23 ℃) described in JIS A1412-2 (1999).

The difference in thermal conductivity was determined by subtracting the thermal conductivity after 1 day from the thermal conductivity after 100 days from the production.

(production stability)

The foamed state of the extruded foam sheet was evaluated according to the following criteria.

Very good: the extrusion foaming state was extremely good, and no unevenness was observed on the surface of the foam sheet

O: the extrusion foaming state was good, and irregularities were present in a part of the surface of the foam board

X: the extrusion foaming state was poor, and a large number of irregularities were present on the surface of the foam board.

(flammability)

The obtained extruded foam sheet was subjected to a flammability test of measurement method A of 5.13.1 in accordance with JIS A9511 (2006R) 5.13.1. The measurement was performed by cutting 5 test pieces out of one extruded foam sheet, and the case where "the flame was small for 3 seconds or less in all the test pieces, no dust remained, and combustion did not exceed the combustion limit line" was evaluated as "o", and the case other than this was evaluated as "x".

Claims

1. A process for producing an extruded thermoplastic resin foam sheet, characterized by extruding and foaming a molten foamable resin obtained by kneading a thermoplastic resin and a physical blowing agent, wherein the extruded foam sheet has a thickness of 10 to 150mm and an apparent density of 20 to 50kg/m ³ In the above-mentioned manufacturing method, the substrate is,

the thermoplastic resin comprises:

polystyrene resin (a),

A polyethylene terephthalate-series resin (b) having a heat of fusion of less than 5J/g based on JIS K7122-1987 but including 0, and

a mixed resin (c) obtained by kneading 50 to 95 wt% of a polystyrene resin (c 1) and 5 to 50 wt% of a polyethylene terephthalate resin (c 2) having a heat of fusion of less than 5J/g according to JIS K7122-1987 and including 0, wherein the total of the polystyrene resin (c 1) and the polyethylene terephthalate resin (c 2) is 100 wt%;

the total amount of the polyethylene terephthalate resin (b) and the polyethylene terephthalate resin (c 2) is 10 to 100 parts by weight, based on 100 parts by weight of the total amount of the polystyrene resin (a) and the polystyrene resin (c 1),

the blending ratio of the polystyrene resin (a), the polyethylene terephthalate resin (b) and the mixed resin (c) is 10 to 80 wt% of the polystyrene resin (a), 5 to 40 wt% of the polyethylene terephthalate resin (b), 20 to 62 wt% of the mixed resin (c), and the total of the blending ratio of the polystyrene resin (a), the polyethylene terephthalate resin (b) and the mixed resin (c) is 100 wt%.

2. The method of claim 1, wherein the ratio of the amount of the polyethylene terephthalate resin (b) to the amount of the polyethylene terephthalate resin (c 2) is 0.5 to 4.

3. The method for producing a thermoplastic resin extruded foam sheet according to claim 1 or 2, wherein the polystyrene resin (a) has a shear rate of 100s at 200 ℃ ^-1 Under the condition (2), the melt viscosity (. Eta.a) is 500 to 2500 Pa.s, and the shear rate of the polyethylene terephthalate resin (b) is 100s at 200 DEG C ^-1 The ratio (η b/η a) of the melt viscosity (η b) to the melt viscosity (η a) of the polystyrene resin (a) under the condition (1) is 0.4 to 2.

4. The method for producing a thermoplastic resin extruded foam sheet according to claim 3, wherein the mixed resin (c) has a shear rate of 100s at 200 ℃ and ^-1 the ratio (η c/η a) of the melt viscosity (η c) under the condition (1) to the melt viscosity (η a) of the polystyrene resin (a) is 0.2 to 1.

5. The method of producing a thermoplastic resin extrusion-foamed sheet according to claim 1 or 2, wherein the mixed resin (c) is a recycled raw material derived from chips and/or pulverized products of a polystyrene-based resin extrusion-foamed sheet containing a polyethylene terephthalate-based resin having a heat of fusion of less than 5J/g and including 0 according to JIS K7122-1987.

6. The method of producing a thermoplastic resin extruded foam sheet according to claim 1 or 2, wherein the mixed resin (c) is processed into pellets.