JP2011025519A - Extrusion foam superior in heat insulation property - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extrusion foam for an insulator material having a remarkable improvement effect of heat insulation property without using chlorofluorocarbons as a foaming agent. <P>SOLUTION: The extrusion foam has a structure wherein a foam layer is laminated in the thickness direction through a non-foam layer. In the bubble wherein the density is 20-65 kg/m<SP>3</SP>, and the foam layer positioning at the central part in the thickness direction, the ratio (A/B) of an average bubble diameter (A) in the thickness direction to an average bubble diameter (B) in the extrusion direction satisfies 0.3-1.5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an extruded foam that is suitably used as a heat insulating material for buildings, cold storage, cold cars, and the like.

  Foams made of thermoplastic resins or thermosetting resins are widely used as heat insulating materials for buildings. From the viewpoint of reducing carbon dioxide emissions, demands for energy saving in housing and buildings are increasing, and further demand for heat insulating materials is expected.

  Among such heat insulating materials, hard polyurethane foams using chlorofluorocarbons as foaming agents have been widely used as foams having high heat insulating performance. However, from the viewpoint of protecting the global environment, development of foams that do not use chlorofluorocarbons as foaming agents has been advanced not only for rigid polyurethane foams but also for various foams.

  There has been proposed a foam using a thermosetting resin phenolic resin as a foam without using chlorofluorocarbons and having excellent heat insulation and little change with time (see, for example, Patent Document 1). It can be said that it is a foam having the most excellent heat insulating property among foams made of thermoplastic resin or thermosetting resin. However, from the viewpoint of further resource saving in addition to energy saving, its use is restricted from the viewpoint of so-called “recycling” that can be reused as a resin, and it cannot be said that it is widely used. is there.

  For this reason, it is desired to develop a technology for a foam that uses a recyclable thermoplastic resin and does not use chlorofluorocarbons and has a higher heat insulation than ever before.

Various techniques have been proposed as techniques for improving the heat insulation properties of a foam using a thermoplastic resin.
For example, a method of controlling the bubble shape and further the bubble diameter, such as a method of controlling the ratio of the bubble diameter in the extrusion direction (or the horizontal direction) to the bubble diameter in the thickness direction of the foam has been proposed (for example, Patent Documents). 2-4). In patent document 2 or 3, the technique regarding the foam which does not use CFCs is also disclosed. Patent Document 4 discloses that the heat insulation is further improved by controlling the shape of the bubbles in the surface layer portion and the bubble central portion, and the bubble diameter.
In addition, methods for adding additives such as carbon black, graphite, and titanium oxide have also been proposed (see, for example, Patent Documents 5 to 7). In particular, Patent Document 6 or 7 discloses a technique related to a foam that does not use chlorofluorocarbons, and discloses that heat insulation is improved by adding graphite or titanium oxide.

  As described above, various techniques for improving the heat insulation property of the foam using the thermoplastic resin have been disclosed. However, in the technique that does not use the chlorofluorocarbons, the heat insulation property deteriorated due to the conversion of the foaming agent from the chlorofluorocarbons. There are many technologies aimed at supplementing

  As a technique that may further improve the heat insulation, a coextruded foam composite in which a foam layer and a non-foam layer are alternately laminated by a co-extrusion method may be mentioned. For example, a method of adding an additive such as carbon black to a coextruded foam composite has been proposed (see, for example, Patent Document 8 or 9). However, only the effects of foams using chlorofluorocarbons are exemplified. Moreover, it is a co-extrusion foaming composite, Comprising: The method of controlling the ratio of the bubble diameter of the extrusion direction with respect to the bubble diameter of the thickness direction is proposed (for example, patent document 10). However, the technique of Patent Document 10 aims at improving strength, and does not suggest any improvement in heat insulation of the foam.

  In this way, in the co-extrusion foamed composite, high heat insulation foam without using chlorofluorocarbons, and high heat insulation foam such as foam using phenol resin and rigid polyurethane foam using chlorofluorocarbons. No technology aimed at gaining a body has been proposed yet.

WO2000 / 001761 JP 2005-528494 A JP 2004-59595 A JP 2008-13659 A Japanese Patent Publication No. 4-502173 JP 2004-196907 A JP 2002-194129 A Japanese National Patent Publication No. 6-510247 Japanese Patent Laid-Open No. 5-577779 WO2008 / 008875 publication

  The present invention solves the above-described problems, and provides a foam made of a thermoplastic resin, which has a remarkable effect of improving heat insulation performance without using chlorofluorocarbons as a foaming agent. With the goal.

As a result of intensive studies to solve the above-mentioned problems, the present inventor found the following matters and completed the present invention.
(1) The foam structure has an alternately laminated structure of a foam layer and a non-foam layer, and the foam layer located in the center in the thickness direction is formed in the bubbles of the foam layer constituting the extruded foam in a specific density range. By controlling the ratio (A / B) of the average bubble diameter (A) in the thickness direction and the average bubble diameter (B) in the extrusion direction, the heat insulation of the extruded foam is further improved.
(2) Furthermore, by manufacturing this using a coextrusion method, the non-foamed layer suppresses the intrusion of air into the foamed layer cell that occurs immediately after the production.

That is, the present invention
[1] An extruded foam having a structure in which a foam layer is laminated via a non-foam layer in the thickness direction,
The density is 20 to 65 kg / m ³ , and
In the bubbles constituting the foam layer located in the center in the thickness direction, the ratio (A / B) of the average bubble diameter (A) in the thickness direction to the average bubble diameter (B) in the extrusion direction is 0.3 to 1.5. Extruded foam, characterized by satisfying
[2] An extruded foam having a structure in which a foam layer is laminated via a non-foam layer in the thickness direction, and the density is 20 to 65 kg / m ³ .
The foam layer has a cell structure composed of small bubbles having a cell diameter less than 1.2 times the average cell diameter D2 and large cells having a cell diameter of 1.2 times or more the average cell diameter D2. The average cell diameter in the thickness direction (A) and the average cell diameter in the extrusion direction (B) in the bubbles constituting the foamed layer located in the central portion in the thickness direction are 0.25 mm or less in average cell diameter. Extruded foam, characterized in that the ratio (A / B) satisfies 0.3 to 1.5,
[3] The extruded foam according to [1] or [2], wherein an average cell diameter (A) in the thickness direction of the foam layer is 0.03 to 0.40 mm.
[4] The extruded foam according to any one of [1] to [3], wherein the density of the extruded foam is 20 to 40 kg / m ³ .
[5] The bubbles constituting the foam layer located at the center in the thickness direction have a ratio (A / B) of the average cell diameter (A) in the thickness direction to the average cell diameter (B) in the extrusion direction of 0.3. The extruded foam according to any one of claims [1] to [4], characterized by satisfying -1.0.
[6] The ratio of the total area of small bubbles having a bubble diameter of 0.25 mm or less in the cross-section of the foamed layer located in the central portion in the thickness direction of the extruded foam is 5 to 95%. 2] to [5], the extruded foam according to any one of
[7] The extruded foam according to any one of [1] to [6], wherein the extruded foam has a plurality of the structures in which a foam layer is laminated via a non-foam layer in a thickness direction. Extruded foam,
[8] The resin constituting the foam layer is at least one resin selected from the group consisting of polystyrene, styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, and modified polyphenylene ether resin. The extruded foam according to any one of [1] to [7],
[9] The bubbles constituting the foam layer contain at least one hydrocarbon selected from the group consisting of propane, n-butane, i-butane, and cyclopentane, [1] -Extruded foam according to any of [8],
[10] It has a structure in which a foamed layer is laminated through a non-foamed layer in the thickness direction, a density is 20 to 65 kg / m ³ , and
In the bubbles constituting the foam layer located in the center in the thickness direction, the ratio (A / B) of the average bubble diameter (A) in the thickness direction to the average bubble diameter (B) in the extrusion direction is 0.3 to 1.5. A method for producing an extruded foam that satisfies the above requirements, obtained by co-extrusion in which a molten resin containing a foaming agent and a molten resin not containing a foaming agent are merged in the thickness direction under high pressure and then released under atmospheric pressure. A method of producing an extruded foam, and [11] having a structure in which a foam layer is laminated via a non-foam layer in the thickness direction, and a density is 20 to 65 kg / m ³ ,
The foam layer has a cell structure composed of small bubbles having a cell diameter less than 1.2 times the average cell diameter D2 and large cells having a cell diameter of 1.2 times or more the average cell diameter D2. The average cell diameter in the thickness direction (A) and the average cell diameter in the extrusion direction (B) in the bubbles constituting the foamed layer located in the central portion in the thickness direction are 0.25 mm or less in average cell diameter. Is a method for producing an extruded foam satisfying a ratio (A / B) of 0.3 to 1.5, in which the extruded foam is a high-pressure liquid resin containing a foaming agent and a molten resin containing no foaming agent. The present invention relates to a method for producing an extruded foam, which is obtained by a coextrusion method in which the layers are joined together in the thickness direction and then released to atmospheric pressure.

The effects of the extruded foam of the present invention are as follows.
The foam layer has a laminate structure in which a foam layer is laminated via a non-foam layer as a foam structure, and the foam layer located in the center in the thickness direction of the foam layer constituting the extruded foam in a specific density range By controlling the ratio (A / B) of the average cell diameter (A) in the thickness direction and the average cell diameter (B) in the extrusion direction, the heat insulating property of the foam is further improved.
・ By using a foam with a laminated structure of foamed layer and non-foamed layer, and controlling the cell structure, heat insulation is achieved compared to the conventional foamed material that only controls the cell structure. This is an improvement that is not suggested by the prior art related to conventional foam composites.
-In the foam layer cell generated immediately after production by producing an extruded foam having a laminated structure in which a foam layer of a foam layer and a non-foam layer is laminated via the non-foam layer using a co-extrusion method Intrusion of air into the foam layer cell can be prevented by the non-foam layer, and in particular by adopting a structure in which both sides of the foam layer are covered with the non-foam layer in the thickness direction. Is suppressed, and the heat insulation performance of the obtained foam can be further improved.
Since the effect of the extruded foam can be combined with other conventional techniques aimed at improving the heat insulation of the foam, provision of a foam having an unprecedented heat insulation performance can be expected.

FIG. 1 is an example of an SEM photograph in an extruded cross section regarding a laminated structure of an extruded foam molded body according to the present invention. FIG. 2 is an SEM photograph showing the bubble structure in the foam layer according to the present invention. (A) A foam layer composed only of bubbles having a substantially uniform cell diameter. (B) A foam layer composed of small bubbles and large bubbles. FIG. 3 is an SEM photograph showing an operation procedure for explaining a method of measuring a bubble diameter in the thickness direction and the extrusion direction in a foam layer composed of small bubbles and large bubbles. FIG. 4 is a schematic view showing the measurement position of the thickness of the extruded foam molded body according to the present invention. FIG. 5 is a schematic diagram showing the measurement position of the width of the extruded foam molded body according to the present invention.

The extruded foam of the present invention has a structure in which a foamed layer is laminated via a non-foamed layer in the thickness direction, the density is 20 to 65 kg / m ³ , and the extruded foam in the thickness direction center portion. In the bubbles constituting the foam layer positioned, the ratio (A / B) of the average cell diameter (A) in the thickness direction and the average cell diameter (B) in the extrusion direction satisfies 0.3 to 1.5, It can be set as a highly heat-insulating foam rather than the conventional extrusion foam.

The foamed layer constituting the extruded foam of the present invention refers to a layer having a cell structure in which a plurality of cells are bonded by cell walls and wall wall struts. The shape is not particularly limited, and examples include a film shape, a sheet shape, and a board shape. Among these, a sheet shape and a board shape are more likely to exhibit heat insulation performance and can give light weight to the extruded foam. Is preferred. The density of the foam layer is preferably 500 kg / m ³ or less, although it depends on the density of the target extruded foam.

The non-foamed layer constituting the extruded foam molded body of the present invention is a layer having a thickness of 1.1 times or more than the thicker portion of the bubble wall or bubble wall bonding portion of the bubble constituting the foam layer. Thus, it refers to a layer having a higher density than the foamed layer constituting the periphery of the non-foamed layer. The density of the non-foamed layer depends on the density of the resin and additives used, but is preferably more than 500 kg / m ³ . The non-foamed layer may contain fewer bubbles than the foamed layer.

The density of the extruded foam of the present invention is preferably 20 to 65 kg / m ³ because a lightweight and highly heat-insulating foam can be obtained, and 20 to 50 kg / m ³ from the viewpoint of achieving both lightness and heat insulation. Is more preferable, and 20 to 40 kg / m ³ is more preferable.

  In the extruded foam of the present invention, the ratio of the average cell diameter (A) in the thickness direction to the average cell diameter (B) in the extrusion direction (A / When B) satisfies 0.3 to 1.5, high heat insulation can be realized. This is presumed to be due to the effect that by increasing the A / B ratio to 1.5 or less, the number of bubbles in the thickness direction per unit thickness can be increased as compared to a foam layer exceeding 1.5. Is done. By setting the A / B ratio to 0.3 or more, the average foam diameter (A) in the thickness direction and the extrusion can be maintained so that the compression strength of the obtained extruded foam can be maintained at the same level as the conventional foam. The ratio (A / B) of the average cell diameter (B) in the direction more preferably satisfies 0.3 to 1.0 from the viewpoint of achieving both compression strength and heat insulating properties of the extruded foam.

Below, the calculation method of the average bubble diameter (A) of a thickness direction, the average bubble diameter (B) of an extrusion direction, and its ratio (A / B) is described.
In the case of a foam layer composed only of bubbles having the same cell diameter, it is obtained by the following method. In this case, the average cell diameter (A) in the thickness direction and the average cell diameter (B) in the extrusion direction correspond to the average cell diameter (A1) in the thickness direction and the average cell size (B1) in the extrusion direction.
(1) A cross-sectional photograph of the foam layer located in the central portion is taken at a magnification of 20 to 200 times using a microscope, for example, a micro high scope or a scanning electron microscope. At this time, the thickness direction is taken in the vertical direction and the extrusion direction is taken in the horizontal direction. The magnification is appropriately selected depending on the bubble diameter.
(2) Three 2000 μm straight lines are arbitrarily drawn in the vertical direction, and the number of bubbles (X1) in contact with the straight lines is measured.
(3) The average cell diameter (A1) in the thickness direction is determined by the following formula.
A1 [unit: μm] = 2000 × 3 ÷ number of bubbles (X1)
(4) A 2000 μm straight line is arbitrarily drawn in the extrusion direction, and the number of bubbles (Y1) in contact with the straight line is measured.
(5) The average cell diameter (B1) in the extrusion direction is determined by the following equation.
B1 [unit: μm] = 2000 × 3 ÷ number of bubbles (Y1)
(6) The ratio (A1 / B1) of the average cell diameter (A1) in the thickness direction and the average cell diameter (B1) in the extrusion direction is determined by the following equation.
A1 / B1 = average cell diameter in thickness direction (A1) ÷ average cell diameter in extrusion direction (B1)
(7) The average bubble diameter (D1) is obtained by the following equation.
D1 [unit: μm] = {average cell diameter in thickness direction (A1) + average cell diameter in extrusion direction (B1)} / 2

On the other hand, it is composed of bubbles having a bubble diameter less than 1.2 times the average bubble diameter D2 (hereinafter referred to as small bubbles) and bubbles having a bubble diameter greater than 1.2 times the average bubble diameter D2 (hereinafter referred to as large bubbles). In the case of a foamed layer composed of a cellular structure, the following method is used.
In this case, the average cell diameter (A) in the thickness direction and the average cell diameter (B) in the extrusion direction correspond to the average cell diameter (A5) in the thickness direction and the average cell size (B5) in the extrusion direction.
(8) A cross-sectional photograph of the foam layer located in the center is taken at a magnification of 20 to 200 times using a microscope, for example, a micro high scope or a scanning electron microscope [see FIG. 3 (a)]. At this time, the thickness direction is taken in the vertical direction and the extrusion direction is taken in the horizontal direction. The magnification is appropriately selected depending on the bubble diameter.
(9) Draw three 2000 μm straight lines in the longitudinal direction of the cross-sectional photograph, and measure the number of bubbles (X2) in contact with the straight lines. The average bubble diameter (A2) in the bubble thickness direction is determined by the following equation.
A2 [unit: μm] = 2000 × 3 ÷ number of bubbles (X2)
As shown in FIG. 3 (b-2), three 2000 μm straight lines are arbitrarily drawn in the extrusion direction of the cross-sectional photograph, and the number of bubbles (Y2) in contact with the straight lines is measured. The average bubble diameter (B2) in the bubble extrusion direction is determined by the following equation.
B2 [unit: μm] = 2000 × 3 ÷ number of bubbles (Y2)
The average bubble diameter (D2) is obtained by the following formula.
D2 [unit: μm] = (A2 + B2) / 2
(10) As shown by the arrow in FIG. 3 (c), the bubble diameter [= (diameter in the thickness direction + diameter in the extrusion direction) / 2] which is not less than 1.2 times D2 in the image (however, All the bubbles having only the bubbles whose entire circumference can be discriminated are set as large bubbles, and the number (X3), the bubble diameter in the thickness direction of each bubble, and the bubble diameter in the extrusion direction of each bubble are measured. The bubble diameter was the maximum length in the thickness direction and extrusion direction of each bubble.
The average bubble diameter (A3) in the thickness direction of the large bubbles and the average bubble diameter (B3) in the extrusion direction of the large bubbles are determined by the following equations.
A3 [unit: μm] = total bubble diameter in the thickness direction of each large bubble ÷ number of large bubbles (X3)
B3 [unit: μm] = total bubble diameter in the extrusion direction of each large bubble ÷ number of large bubbles (X3)
The average large bubble diameter (D3) is obtained by the following formula.
D3 [unit: μm] = (A3 + B3) / 2
(11) Bubbles whose bubble diameter was not measured in (9) above are defined as small bubbles.
The dimensions in the thickness direction and the extrusion direction of the rectangular region [see FIG. 3 (d)] including all the large bubbles measured in (9) above are measured, and the area (S ₀ ) of the region is obtained.
From the following equation, the total area ratio (S) of the small bubbles is obtained by the following equation.
S [unit:%] = [S ₀ − {π × (D3 ÷ 2) ² } × X3] ÷ S ₀ × 100
(12) As shown in FIG. 3 (e-1), in the region where the small bubbles in the rectangular region in (10) are continuously present in the vertical direction of 500 μm or more, an arbitrary straight line of 500 μm in the vertical direction. Are drawn, and the number of bubbles (X4) in contact with the straight line is measured.
The average bubble diameter (A4) in the thickness direction of the small bubbles is obtained by the following equation.
A4 [unit: μm] = 500 × 3 ÷ number of bubbles (X4)
As shown in FIG. 3 (e-2), in a region where small bubbles continuously exist in the lateral direction of 500 μm or more, three arbitrary 500 μm straight lines are drawn in the lateral direction, and the number of bubbles in contact with the straight line (Y4 ).
The average bubble diameter (B4) in the extrusion direction of small bubbles is determined by the following equation.
B4 [unit: μm] = 500 × 3 ÷ number of bubbles (Y4)
The average small bubble diameter (D4) is obtained by the following formula.
D4 [unit: μm] = (A4 + B4) / 2
(13) above (9) the number (Z1) of small bubbles in the rectangular area _S in _0, the following equation, obtained approximately.
Z1 [unit: piece] = S ₀ × (S / 100) ÷ {π × (D4 ÷ 2) ² }
(14) The average cell diameter (A5) in the thickness direction is approximately determined by the following equation.
A5 [unit: μm] = (A3 × X3 + A4 × Z1) ÷ (X3 + Z1)
The average bubble diameter (B5) in the extrusion direction is approximately determined by the following equation.
B5 [unit: μm] = (B3 × X3 + B4 × Z1) ÷ (X3 + Z1)
(15) The ratio (A5 / B5) of the average cell diameter (A5) in the thickness direction and the average cell diameter (B5) in the extrusion direction is determined by the following equation.
A5 / B5 = average bubble diameter in the thickness direction (A5) ÷ average bubble diameter in the extrusion direction (B5)
(16) The average bubble diameter (D5) is determined by the following equation.
D5 [unit: μm] = [{average bubble diameter in thickness direction (A5) + average bubble diameter in extrusion direction (B5)} / 2]

  The resin constituting the foam layer of the extruded foam of the present invention (hereinafter sometimes referred to as “foam layer constituent resin”) is arbitrarily selected from thermoplastic resins that can be subjected to extrusion foam molding. The thermoplastic resin is not particularly limited. For example, styrene resins such as polystyrene, styrene-acrylonitrile copolymer, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid ester copolymer, Alternatively, vinyl resins such as polymethyl methacrylate, polyacrylonitrile resin, polyvinyl chloride resin; polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-propylene-butene terpolymer, cycloolefin (co) Polyolefin resins such as polymers and resins whose branched structures and cross-linked structures are introduced to control rheology; polyamide resins such as nylon 6, nylon 66, nylon 11, nylon 12, and MXD nylon; polyethylene terephthalate, polybutylene Polyester resins such as terephthalate and polyarylate; polycarbonate resins, polyphenylene ether resins, modified polyphenylene ether resins, polyoxymethylene resins, polyphenylene sulfide resins, polyphenylene sulfide resins, aromatic polyether resins, polyethers Examples include engineering plastics such as ether ketone resins and liquid crystal resins; aliphatic polyester resins such as polylactic acid, and these can be used alone or in admixture of two or more.

  When the styrene resin is used as the resin constituting the foamed layer of the extruded foam of the present invention, there is no particular limitation. For example, a styrene homopolymer obtained only from a styrene monomer, a styrene monomer and styrene Examples thereof include random, block or graft copolymers obtained from polymerizable monomers or derivatives thereof, post-brominated polystyrene, modified polystyrene such as rubber-reinforced polystyrene, ABS resin, and the like. These can be used alone or in admixture of two or more.

  Examples of monomers copolymerizable with styrene include methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene. Polyfunctional vinyl compounds such as divinylbenzene, (meth) acrylic compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, methacrylonitrile, α-chloroacrylonitrile, acrylonitrile , Diene compounds such as budadiene or derivatives thereof, unsaturated carboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, N-methylmaleimide, N-butylmaleimide N-alkyl-substituted maleimide compounds such as N-cyclohexylmaleimide, N-phenylmaleimide, N-4-diphenylmaleimide, N-2-chlorophenylmaleimide, N-4-bromophenylmaleimide, N-1-naphthylmaleimide; It is done. These can be used alone or in admixture of two or more.

  Among these, since extrusion foaming is easy, lightweight, and an extruded foam excellent in heat insulation is obtained, polystyrene, styrene-acrylonitrile copolymer, styrene- (meth) acrylic acid copolymer, styrene- ( (Meth) acrylic acid ester copolymer, maleic anhydride modified polystyrene, styrene-unsaturated dicarboxylic anhydride-N-alkyl substituted maleimide copolymer, styrene resin such as high impact polystyrene, or polymethyl methacrylate, Vinyl resins such as polyvinyl chloride resins; modified polyphenylene ether resins which are mixed resins of polystyrene resins and polyphenylene ether resins are preferred. Most preferred is a polystyrene homopolymer.

  The foamed layer of the extruded foam of the present invention can be obtained by press-fitting a foaming agent into a melted foamed layer constituting resin under high pressure, melting and kneading, and then releasing into the atmosphere. For example, hydrocarbons such as methane, ethane, propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, cyclopentane; dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n -Ethers such as butyl ether, diisopropyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, tetrahydropyran; acetone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, methyl i-butyl ketone, methyl n- Amyl ketone, Ketones such as ru-n-hexyl ketone, ethyl n-propyl ketone and ethyl n-butyl ketone; alcohols such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol and t-butyl alcohol; Esters such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, methyl propionate and ethyl propionate; halogens such as methyl chloride and ethyl chloride Alkyl fluorides; inorganic foaming agents such as nitrogen, air, water and carbon dioxide; and chemical foaming agents such as azo compounds and tetrazole. Also, fluorinated hydrocarbons having zero ozone depletion coefficient and low global warming potential can be used. These foaming agents can be used alone or in admixture of two or more.

Among the foaming agents, hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, and cyclopentane are preferable because they can achieve both extrusion foam moldability and high heat insulation. Since the thermal conductivity is low as the characteristics of the gas itself and the permeability to the thermoplastic resin constituting the extruded foam is low, a highly heat-insulated extruded foam is obtained and its performance is maintained for a long time. -Butane, i-butane and cyclopentane are particularly preferred. Moreover, ethers such as dimethyl ether, diethyl ether and methyl ethyl ether; methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t- Alcohols such as butyl alcohol; alkyl halides such as methyl chloride and ethyl chloride are preferred. Further, inorganic foaming agents such as nitrogen, air, water and carbon dioxide are preferred from the viewpoint of nonflammability and excellent environmental compatibility.
From the standpoint of obtaining a lightweight and highly heat-insulating extruded foam molding, one or more hydrocarbons selected from n-butane, i-butane, and cyclopentane, and carbon dioxide, dimethyl ether, diethyl ether, and methyl ethyl ether A group consisting of ethers such as methanol, ethanol, propyl alcohol, i-propyl alcohol, alcohols such as butyl alcohol, i-butyl alcohol, and t-butyl alcohol, and halogenated alkyls such as water, methyl chloride, and ethyl chloride It is preferable to use a combination of one or more compounds selected from.

  The amount of the foaming agent that is press-fitted into the melted foam layer-constituting resin is appropriately selected according to the setting value of the foaming ratio, etc., but from the point of obtaining a lightweight and highly heat-insulating extruded foam, The total amount of the foaming agent is preferably 1 to 20 parts by weight and more preferably 3 to 8 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

  The pressure when the foaming agent is press-fitted is not particularly limited as long as it is higher than the internal pressure of an extruder or the like.

  In terms of obtaining a highly heat-insulating extruded foam, 0.5 to 5 parts by weight of hydrocarbons such as n-butane, i-butane, and cyclopentane are obtained with respect to 100 parts by weight of the obtained extruded foam. It is preferable to contain.

  The average cell diameter in the foamed layer made of the thermoplastic resin constituting the extruded foam of the present invention is preferably 0.03 to 1 mm, more preferably 0.03 to 0.4 mm, and particularly preferably 0.03 to 0.3 mm. 3 mm.

  Moreover, when using together at least 1 sort (s) from the group which consists of water, alcohol aqueous solution, and aqueous solution of inorganic salt as a foaming agent, it is less than 1.2 times of average bubble diameter D2 in a foam, and is 0.25 mm or less. A foam layer having a characteristic bubble structure in which bubbles having a bubble diameter (small bubbles) and bubbles having a bubble diameter of 1.2 times or more of the average bubble diameter D2 (large bubbles) are mixed in a sea-island shape is obtained, Since this cellular structure contributes to the improvement of the heat insulation performance of the obtained extruded foam, it is preferable to use water and / or an aqueous solution in combination as a foaming agent.

  Further, in the foam layer having a specific cell structure in which small bubbles and large cells having a bubble diameter of 0.25 mm or less are mixed, the ratio of the area of the small bubbles in the cross section of the foam layer located in the central portion in the thickness direction ( Occupied area ratio per unit cross-sectional area) (hereinafter referred to as small bubble area ratio) is preferably 5 to 98%, more preferably 10 to 90%, particularly preferably 20 to 80%, and most preferably 25 to 70%. It is. When the small bubble area ratio is in the range of 5 to 98%, an extruded foam having a low density and excellent heat insulating performance can be obtained.

  When water and / or an aqueous solution are used as the foaming agent, the content of water with respect to the total amount of the foaming agent is preferably 1 to 80% by weight, more preferably, from the viewpoint of ease of formation of small bubbles and large bubbles and processability. It is 2 to 70% by weight, particularly preferably 3 to 60% by weight.

  When water and / or an aqueous solution are used as the foaming agent, water-absorbing or water-swelling layered silicates such as smectite and swellable fluorinated mica or their organically treated products, water-absorbing polymers, Nippon Aerosil Co., Ltd. By adding one or more of anhydrous silica having a silanol group such as AEROSIL manufactured (in the present specification, these substances are collectively referred to as “water-absorbing substance”), The effect | action which a small bubble and a large bubble generate | occur | produce can be improved further, and the moldability of the obtained foam, productivity, and heat insulation performance can further be improved.

  Here, it is considered that the water-absorbing substance used can absorb water that is not compatible with the thermoplastic resin to form a gel, and can be uniformly dispersed in the thermoplastic resin in a gel state. Used from.

  The amount of the water-absorbing substance used in producing the foamed layer constituting the extruded foam of the present invention is appropriately adjusted depending on the amount of water added, etc., but generally 100 parts by weight of thermoplastic resin Is preferably 0.2 to 10 parts by weight, more preferably 0.3 to 8 parts by weight, and particularly preferably 0.5 to 7 parts by weight. When the added amount of the water-absorbing substance is 0.2 to 10 parts by weight, water is well dispersed in the extruder, and a foamed layer having a good cell structure free from bubble unevenness and voids is obtained, and there is no variation. An extruded foam having good heat insulation performance can be obtained.

  The layered silicate used in producing the foamed layer constituting the extruded foam of the present invention comprises a tetrahedral sheet mainly composed of silicon oxide and an octahedral sheet mainly composed of metal hydroxide. The tetrahedron sheet and the octahedron sheet form a unit layer, a unit layer single structure, or a plurality of unit layers laminated between layers through cations, etc., and primary particles It exists as an aggregate (secondary particle). Specific examples of the layered silicate include, for example, smectite clay and swellable mica.

The smectite clay is represented by the following general formula (I)
X _0.2-0.6 Y _2-3 Z ₄ O ₁₀ (OH) ₂ .nH ₂ O... General formula (I)
(However, X is at least one selected from the group consisting of K, Na, 1 / 2Ca, and 1 / 2Mg, and Y is a group consisting of Mg, Fe, Mn, Ni, Zn, Li, Al, and Cr. And Z is at least one selected from the group consisting of Si and Al, where H ₂ O represents a water molecule bonded to an interlayer ion, and n is an interlayer ion. And varies significantly depending on the relative humidity).

  Specific examples of the smectite group clay include, for example, montmorillonite, beidellite, nontronite, saponite, iron saponite, hectorite, soconite, stevensite, bentonite, and the like, or a substitution product, a derivative thereof, or a mixture thereof. .

The swellable mica is represented by the following general formula (II)
X _0.5-1.0 Y _2-3 (Z ₄ O ₁₀ ) (F, OH) ₂ ... General formula (II)
(However, X is at least one selected from the group consisting of Li, Na, K, Rb, Ca, Ba, and Sr, and Y is selected from the group consisting of Mg, Fe, Ni, Mn, Al, and Li) Z is one or more selected from the group consisting of Si, Ge, Al, Fe, and B), and is natural or synthesized.

  These are water, a polar organic compound that is compatible with water in an arbitrary ratio, and a substance that swells in a mixed solvent of water and the polar organic compound. For example, lithium teniolite, sodium Type teniolite, lithium type tetrasilicon mica, sodium type tetrasilicon mica and the like, or a substituted product, a derivative thereof, or a mixture thereof.

Some of the swellable mica have a structure similar to vermiculites, and such vermiculites and the like can also be used. The vermiculite-equivalent products include three octahedron type and two octahedron type, and the following general formula (III)
_{(Mg, Fe, Al) 2~3} (Si 4-x Al x) O 10 (OH) 2 · (M +, M 2 + 1/2) x · nH 2 O ······ formula (III)
(Wherein M is an exchangeable cation of an alkali or alkaline earth metal such as Na and Mg, x = 0.6 to 0.9, and n = 3.5 to 5). .

  Swellable layered silicates may be used alone or in combination of two or more. Among these, from the viewpoint of dispersibility in the obtained foam, smectite group clay and swellable mica are preferable, and have sodium ions between layers such as montmorillonite, bentonite, hectorite, synthetic smectite, and swellable fluorine mica. Swellable mica is more preferred.

  Typical examples of bentonite include natural bentonite and purified bentonite. Also, organic bentonite can be used. The smectite in the present invention includes montmorillonite-modified products such as anionic polymer-modified montmorillonite, silane-treated montmorillonite, and highly polar organic solvent composite montmorillonite.

The content of smectite such as bentonite is appropriately adjusted depending on the amount of water added, but is preferably 0.2 to 10 parts by weight, and 0.3 to 8 parts by weight with respect to 100 parts by weight of the thermoplastic resin. Part is more preferable, 0.5 to 7 parts by weight is particularly preferable, and 1 to 5 parts by weight is most preferable.
If the smectite content is less than 0.2 parts by weight, the amount of water adsorbed by the smectite is insufficient with respect to the amount of water injected, and pores due to poor dispersion of water tend to occur in the extruder, resulting in a defective molded body. . On the other hand, when the content of smectite exceeds 10 parts by weight, the amount of inorganic powder present in the thermoplastic resin becomes excessive, so that uniform dispersion in the thermoplastic resin becomes difficult, and bubble unevenness occurs. Furthermore, it tends to be difficult to maintain closed cells. Therefore, it becomes easy to produce deterioration and variation of the heat insulation performance of a foam.

  The mixing ratio of water / smectite (bentonite) is preferably 0.02 to 20, more preferably 0.1 to 10, particularly preferably 0.15 to 5, and most preferably in the range of 0.25 to 2, in terms of weight ratio. preferable.

The density of the foamed layer constituting the extruded foam of the present invention in order to impart light weight and excellent heat insulating properties, is preferably 10~60Kg / ^{m 3,} more to be 15~50Kg / ^{m 3} preferable.

  During the production of the foamed layer constituting the extruded foam of the present invention, a halogen-based flame retardant, a halogen-phosphorus flame retardant, a phosphorus flame retardant, a nitrogen flame retardant, a nitrogen-phosphorus flame retardant, if necessary, Flame retardants such as nitrogen-halogen flame retardants, phosphorus compounds, nitrogen compounds, boron compounds, metal oxides, iron-containing compounds, flame initiators such as radical initiators, silica, talc, calcium silicate, wax Inorganic compounds such as lastnite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate, sodium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin wax, stearylamide compound, epoxy compound, etc. Processing aid, phenolic antioxidant, phosphorus stabilizer, nitrogen stabilizer, sulfur stabilizer, benzotria Lumpur acids, light stabilizers such as hindered amines, antistatic agent, it is preferable to add an additive such as a colorant such as a pigment. Furthermore, you may add the heat ray radiation suppression material mentioned later.

  The thickness of the foamed layer constituting the extruded foam of the present invention depends on the thickness of the extruded foam and the number of foamed layers in the extruded foam (number of units comprising foamed layer / non-foamed layer / foamed layer). Are appropriately selected.

  The resin or resin composition constituting the non-foamed layer in the present invention (hereinafter sometimes referred to as “non-foamed layer-constituting resin”) is an extruded material obtained in order to obtain the desired highly heat-insulating extruded foam. Since it is preferable that the foamed layer and the non-foamed layer of the foam are favorably bonded, it is preferable to select a resin that is compatible with the resin constituting the foamed layer. In addition, even if the resin does not have compatibility with the resin constituting the foam layer, the resin layer is laminated through a resin layer having adhesiveness and adhesiveness that exhibits an anchor effect with the foam layer. Is also possible.

  Examples of the non-foamed layer-constituting resin include the same styrenic resin, vinyl-based resin, polyester-based resin, polycarbonate-based resin, engineering plastic, and aliphatic polyester-based resin as those exemplified for the foamed layer-constituting resin. These can be used alone or in admixture of two or more. Among these, polystyrene, styrene-acrylonitrile copolymer, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid ester copolymer, maleic anhydride-modified polystyrene, which are preferably used as the foamed layer-constituting resin. Styrene-unsaturated dicarboxylic anhydride-N-alkyl substituted maleimide copolymers, styrene resins such as high impact polystyrene, or vinyl resins such as polymethyl methacrylate and polyvinyl chloride resins; polystyrene resins When using a modified polyphenylene ether resin, which is a mixed resin of polyphenylene ether resin, the molecular weight, copolymerization component, functional group, etc. may be different. -Acrylonitrile copolymer, styrene -(Meth) acrylic acid copolymer, styrene- (meth) acrylic ester copolymer, maleic anhydride modified polystyrene, styrene-unsaturated dicarboxylic anhydride-N-alkyl substituted maleimide copolymer, impact resistance It is preferable to use a styrene resin such as polystyrene, or a vinyl resin such as polymethyl methacrylate or polyvinyl chloride; a modified polyphenylene ether resin that is a mixed resin of a polystyrene resin and a polyphenylene ether resin. Further, it is particularly preferable to use the same resin as the foam layer constituent resin.

  In addition, when a styrene resin is used as the foam layer-constituting resin, the resin having adhesiveness and adhesiveness includes polyolefin resin, vinyl chloride resin, vinylidene chloride resin, vinyl alcohol resin, ethylene -Vinyl alcohol copolymer resins, acrylic resins, styrene-butadiene copolymer resins, natural rubber resins, chloroprene resins, and rosins, rosin derivatives, petroleum resins, terpene resins, phenol resins And a resin composition obtained by blending a tackifier resin such as rosin phenol resin and ketone resin.

  The structure of the non-foamed layer constituting the extruded foam of the present invention is not particularly limited, and any structure of a single layer or a multilayer can be adopted. The thickness of the non-foamed layer is appropriately selected according to the thickness of the extruded foam and the number of foamed layers in the extruded foam (number of units composed of foamed layer / non-foamed layer / foamed layer).

  The thickness of the non-foamed layer is not limited as long as it has a thickness that is 1.1 times or more larger than the thicker portion of the bubble walls or bubble wall joints of the bubbles constituting the foam layer, preferably 5 to 500 μm. Yes, 5 to 300 μm is more preferable, 5 to 200 μm is particularly preferable, and 5 to 100 μm is most preferable. When the thickness of the non-foamed layer is in the range of 5 to 500 μm, an extruded foam having lightness and heat insulation can be obtained.

  In addition, the foamed layer and the non-foamed layer in the obtained extruded foam are flat in the flow direction and the width direction, and the respective layers spread in a substantially parallel state. Preferred for obtaining a foam. For this reason, when the coextrusion method to be described later is adopted as a method for producing an extruded foam, the non-foamed layer constituent resin is composed of a foamed layer constituent resin, a foaming agent, and an optional additive in a molten state at a molding temperature. It is preferable that the melt viscosity is as close as possible to the molten resin composition. As this means, for example, a method of adjusting the molecular weight of the non-foamed layer constituent resin, a method of adding an additive having plasticizing ability to the non-foamed layer constituent resin, and a melt viscosity for the non-foamed layer constituent resin. And a method of adding an additive to be improved.

Examples of the additive that is added to adjust the melt viscosity of the non-foamed layer constituent resin include a plasticizer, a compound having a melt viscosity lower than that of the non-foamed layer constituent resin, and a compatible compound. The plasticizer is not particularly limited, and any compound generally used as a plasticizer can be used. For example, dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) , Di-2-ethylhexyl phthalate (DOP), dinormaloctyl phthalate (DNOP), diisononyl phthalate (DINP), dinonyl phthalate (DNP), diisodecyl phthalate (DIDP), butylbenzyl phthalate (BBP), phthalic acid esters such as phthalic acid混基ester _(C 6 _{~C 11);} dioctyl adipate (DOA), diisononyl adipate (DINA), dialkyl adipate (C6,8,10) (610A), dialkyl adipate _{(C 7, C 9) (} 79A) dioctyl azelate (DOZ) Se Dibutyl silicate (DBS), dioctyl sebacate (DOS), tricresyl phosphate (TCP), tributyl acetylcitrate (ATBC), epoxidized soybean oil (ESBO), trioctyl trimellitic acid (TOTM), chlorinated paraffin, etc. Non-phthalic acid esters and the like.

  The amount of plasticizer added to the non-foamed layer constituting resin is appropriately selected depending on the target melt viscosity, but is preferably 1 to 20 parts by weight, and 2 to 15 parts by weight with respect to 100 parts by weight of the non-foamed layer constituting resin. More preferably, 3 to 12 parts by weight is particularly preferable, and 4 to 10 parts by weight is preferable. When the addition amount of the plasticizer is in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the non-foamed layer constituting resin, a non-foamed layer with no discharge fluctuation during extrusion and no surface bleed-out after extrusion is obtained. .

  Compounds having a melt viscosity lower than that of the non-foamed layer-constituting resin and having compatibility are exemplified by phosphate esters such as triphenyl phosphate, but flame retardants, flame retardant aids, stabilizers, and other types Among the non-foamed layer constituting resins, there are compounds that can obtain the same effect.

  In the non-foamed layer constituting resin constituting the extruded foam of the present invention, a plasticizer, a flame retardant, a flame retardant aid, silica, talc, calcium silicate, wollastonite, kaolin, clay, mica are included as necessary. Inorganic compounds such as zinc oxide, titanium oxide, calcium carbonate, processing aids such as sodium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin wax, stearylamide compound, phenolic antioxidant, phosphorus Additives such as system stabilizers, nitrogen stabilizers, sulfur stabilizers, light-resistant stabilizers such as benzotriazoles and hindered amines, antistatic agents, colorants such as pigments, and heat ray radiation inhibitors it can.

  The heat ray radiation inhibitor added to the non-foamed layer constituting the extruded foam of the present invention reflects, scatters, and absorbs light in the near infrared or infrared region (for example, a wavelength region of about 800 to 3000 nm). This means a substance having a black body emissivity smaller than that of the resin constituting the foamed layer and the non-foamed layer. As a heat ray radiation inhibitor, the heat ray reflective agent and heat ray absorber which are described below are mentioned.

  The heat ray reflective agent is not particularly limited as long as it is a substance that reflects and scatters light in the near infrared or infrared region (for example, a wavelength range of about 800 to 3000 nm). Specifically, aluminum, aluminum oxide Aluminum compounds such as zinc aluminate; magnesium compounds such as hydrotalcite; silver compounds such as silver: titanium compounds such as titanium, titanium oxide, strontium titanate; stainless steel, nickel, tin Silver, copper, bronze, shirasu balloon, ceramic balloon, microballoon, pearl mica and the like. These may be used alone or in combination of two or more.

  As a heat ray reflective agent, from the viewpoints of great thermal conductivity reduction effect, cost advantage, environmental compatibility, good handling properties including safety, etc., aluminum compounds, magnesium compounds, Silver-based compounds or titanium-based compounds are preferable, and among these, aluminum paste and titanium oxide are more preferable because of the excellent balance between the thermal conductivity reduction effect and cost.

  The amount of heat ray reflective agent added to the non-foamed constituent resin is appropriately set according to the type of heat ray reflective agent and the thickness of the non-foamed layer, but as an indicator, a predetermined amount of heat ray reflective agent is added to the non-foamed constituent resin. After melt-kneading, a film having the same thickness as the non-foamed layer was prepared, and the absorbance obtained at 800 to 3000 nm in the spectrum obtained by infrared spectrophotometer (IR) measurement of the film hardly changed even when the addition amount was increased. It is preferable to set the minimum amount that reaches such a region as the amount of addition because the balance between the effect of reducing the thermal conductivity of the extruded foam and the cost is excellent.

  The said heat ray absorber means the substance which has the characteristic which absorbs the light of near infrared or infrared region (for example, wavelength range of about 800-3000 nm).

  The heat ray absorbent is not particularly limited as long as it is a substance that absorbs light in the near infrared or infrared region (for example, a wavelength range of about 800 to 3000 nm), and specifically, carbon black, carbon powder. Metal sulfates such as barium sulfate, strontium sulfate, calcium sulfate, mercalite, halotrilite, alumite, iron alumite; antimony compounds such as antimony trioxide, antimony oxide, anhydrous zinc antimonate; tin oxide, indium oxide Metal oxides such as zinc oxide, indonium tin oxide, etc .; ammonium, urea, imonium, aminium, cyanine, polymethine, anthraquinone, dithiol, copper ion, phenylenediamine, phthalocyanine, benzo Triazole, benzophenone, oxalic anilide, shear Acrylate, organic dyes and pigments benzotriazole and the like; and the like.

  As a heat ray absorbent, carbon graphite, carbon black, metal sulfate, etc. from the viewpoints of great thermal conductivity reduction effect, cost advantage, good handling properties including environmental compatibility and safety. Salts or antimony compounds are preferred, and among these, carbon graphite, carbon black, antimony oxide or barium sulfate is more preferred because of its excellent thermal conductivity reduction effect and cost balance.

  The amount of heat-ray absorbent added to the non-foamed constituent resin is appropriately set according to the type of heat-ray absorbent and the thickness of the non-foamed layer. As an indicator, a predetermined amount of heat-ray absorbent is added to the non-foamed constituent resin. After melt-kneading, a film having the same thickness as the non-foamed layer was prepared, and the absorbance obtained at 800 to 3000 nm in the spectrum obtained by infrared spectrophotometer (IR) measurement of the film hardly changed even when the addition amount was increased. It is preferable to set the minimum amount that reaches such a region as the amount of addition because the balance between the effect of reducing the thermal conductivity of the extruded foam and the cost is excellent.

  The method for producing the extruded foam of the present invention, particularly the method for laminating the foamed layer and the non-foamed layer, is not particularly limited. For example, the outermost surface (the surface to be adhered to the foamed layer) has adhesiveness / adhesiveness. A method in which a non-foamed layer (or that has been given tackiness / adhesiveness) is formed into a film or a sheet in advance, and this is sandwiched between the pre-formed foamed layers, followed by pressure bonding; A method of melt-kneading and using a non-foamed layer and a foamed layer, and sandwiching the non-foamed layer between the foamed layers. Thereafter, a method of thermocompression bonding; a method in which the constituent resins of the non-foamed layer and the foamed layer are melt-kneaded using different extruders, the melted resins are joined together in multiple layers and laminated, and then foam molding is performed. .

  Among these production methods, for the extruded foam of the present invention, the constituent resin of the foamed layer and the non-foamed layer is melt-kneaded using different extruders, etc., and the molten resin containing the foaming agent and foamed Using a multi-layer laminating apparatus, each molten resin is joined in a multi-layer shape in a high-pressure region and laminated, and then extruded and foamed into a low-pressure region through a die to form a foam layer. It is preferable to manufacture by molding. By obtaining an extruded foam by the coextrusion method, the non-foamed layer can suppress the intrusion of air into the foamed layer cell that occurs immediately after production. By taking the coated structure, the intrusion of air from the outside air into the foam layer cell is suppressed, and the heat insulation performance of the resulting foam can be further improved.

  In the present invention, a method for laminating each molten resin in a multilayer shape by a multilayer laminating apparatus is not particularly limited, and examples thereof include a feed block method and a multi-manifold method generally used for coextruded films; A method of repeating division and lamination after creating a laminated flow composed of a plurality of layers as described in JP-A-54-23025, JP-A-4-278323, and the like; JP-T-2005-523831, JP-A-2004-249520 And a method of sequentially laminating a plurality of divided flows described in Japanese Patent Gazette.

  The temperature of the multilayer laminating apparatus when producing the extruded foam is preferably equal to or less than ± 10 ° C. even if it is equal to or different from the resin temperature of the foaming agent-containing molten resin supplied to the multilayer laminating apparatus. When the temperature difference is ± 10 ° C. or less, molding with a die can be performed at an appropriate foaming temperature, and an extruded foam having a foam layer with a high magnification and a low closed cell ratio can be obtained.

The pressure in the multilayer laminating apparatus when producing the extruded foam is set to a pressure at which the foaming agent-containing molten resin supplied to the multilayer laminating apparatus does not cause foaming in the multilayer laminating apparatus. However, the pressure that does not cause foaming in the multi-layer laminating apparatus cannot be generally set because it depends on the type of foaming agent, the amount of foaming agent, and the temperature of the foaming agent-containing molten resin.
In the present invention, the foam molding method is not particularly limited, but for example, using a molding die and a molding roll in which a foam obtained by releasing pressure from a slit die is placed in close contact with or in contact with the slit die, A general method for molding a plate-like foam having a large size can be used.

Regarding the melt kneading of the constituent resin of the foam layer,
(I) The thermoplastic resin is mixed with the additive as necessary, and then melted by heating.
(Ii) One or more selected from the above-mentioned additives are mixed with the thermoplastic resin, if necessary, and then melted by heating, and the remaining additive is added to the thermoplastic resin as it is, or liquefied or melted as necessary. Then heat and mix,
(Iii) One or more additives selected from the above-mentioned additives are mixed with a thermoplastic resin in advance, and then a heated and melted composition is prepared. Then, the composition and the remaining additive are prepared. , If necessary, mix the thermoplastic resin again, supply to the extruder and melt by heating,
Etc., thermoplastic resin, if necessary, supply the additive to a hot melt extruder,
Thereafter, in any stage, a foaming agent is added to the thermoplastic resin under high-pressure conditions to obtain a molten resin containing the foaming agent (hereinafter sometimes referred to as “flowing gel”). Thereafter, the fluid gel is cooled to a temperature suitable for extrusion foaming and then supplied to the multilayer laminating apparatus.

  There are no particular limitations on the heating temperature, melt kneading time, and melt kneading means when heating and kneading the thermoplastic resin and additives such as a foaming agent. Although the heating temperature should just be more than the temperature which the thermoplastic resin to be used melt | dissolves, the temperature which suppresses the molecular degradation of resin by the influence of a flame retardant etc. as much as possible, for example, about 150-280 degreeC is preferable. The melt-kneading time varies depending on the extrusion amount per unit time, the melt-kneading means, and the like, and thus cannot be determined unconditionally. However, the time required for uniformly dispersing and mixing the thermoplastic resin and the foaming agent is appropriately selected. Examples of the melt-kneading means include a screw type extruder, but there is no particular limitation as long as it is used for normal extrusion foaming. However, in order to suppress the molecular deterioration of the resin as much as possible, it is preferable to use a low shear type screw shape for the screw shape.

Further, regarding the melt kneading of the constituent resin of the non-foamed layer, for example,
(I) The thermoplastic resin is mixed with the additive as necessary, and then melted by heating.
(Ii) One or more selected from the above-mentioned additives are mixed with the thermoplastic resin, if necessary, and then melted by heating, and the remaining additive is added to the thermoplastic resin as it is, or liquefied or melted as necessary. Then heat and mix,
(Iii) One or more additives selected from the above-mentioned additives are mixed with a thermoplastic resin in advance, and then a heated and melted composition is prepared. Then, the composition and the remaining additive are prepared. , If necessary, mix the thermoplastic resin again, supply to the extruder and melt by heating,
For example, a thermoplastic resin, and if necessary, the additive is supplied to an extruder and heated and melt-kneaded. Thereafter, the melt-kneaded product is supplied to a multilayer laminating apparatus.

  There are no particular limitations on the heating temperature, melt kneading time, and melt kneading means when the thermoplastic resin and additive are heat melt kneaded. The heating temperature may be equal to or higher than the temperature at which the thermoplastic resin to be used melts, but the temperature difference is within ± 10 ° C even if it is equal to or different from the set temperature of the multilayer laminating apparatus to which the molten resin is supplied. Is preferred. When the temperature difference is ± 10 ° C. or less, it is possible to obtain a good extruded foam that does not have bubble breakage at the interface portion between the foamed layer and the non-foamed layer and does not have poor adhesion. The melt-kneading time varies depending on the amount of extrusion per unit time, the melt-kneading means, etc., and thus cannot be generally determined, but the time required for uniformly dispersing and mixing the thermoplastic resin and the additive is appropriately selected. . Examples of the melt-kneading means include a screw type extruder, but there is no particular limitation as long as it is used for ordinary resin extrusion. However, in order to suppress the molecular deterioration of the resin as much as possible, it is preferable to use a low shear type screw shape for the screw shape.

  As the structure of the extruded foam of the present invention, for example, a foamed layer / non-foamed layer / foamed layer may have a structure in which a foamed layer is laminated via a non-foamed layer in the thickness direction of the extruded foam. preferable. This is because, in a structure in which the foam layer is laminated on both surfaces of the non-foam layer, the effect of reducing the thermal conductivity by the heat ray radiation inhibitor contained in the non-foam layer is effective. In addition, in the structure in which the foam layer is laminated only on one side of the non-foam layer, such as non-foam layer / foam layer / non-foam layer, the effect of reducing the thermal conductivity by the heat ray radiation inhibitor contained in the non-foam layer is fully manifested. There is a tendency not to.

More preferably, there are a plurality of non-foamed layers such as foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer. By providing a plurality of non-foamed layers containing a heat ray radiation inhibitor in the thickness direction of the extruded foam, an excellent thermal conductivity that cannot be obtained with a single non-foamed layer (containing heat ray radiation suppression). This is because the reduction effect is manifested.
As a method for controlling the average cell diameter of the foam layer constituting the extruded foam of the present invention, silica, talc, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate, carbonate Examples thereof include a nucleating agent typified by an inorganic compound such as sodium hydride and the layered silicate added to the foamed layer-constituting resin and adjusting the amount of these additives. The average cell diameter is also adjusted by the type, composition and addition amount of the foaming agent. Also, depending on the screw shape of the extruder that is the melt kneading means, the heating temperature, the pressure, the amount of the melt-kneaded foam layer constituting resin composition discharged from the die lip, the die shape, the resin temperature at the time of discharge, etc. The average bubble diameter is adjusted.

In the foamed layer located at the center in the thickness direction of the extruded foam of the present invention, the bubbles constituting the ratio are the ratio of the average cell diameter (A) in the thickness direction to the average cell diameter (B) in the extrusion direction (A / B). ) Satisfies the range of 0.3 to 1.5, for example, a foam layer-constituting resin composition / non-foaming layer constituent resin or a composition thereof laminated in a multilayer form can be used as a die lip. When extruded into a low-pressure region and foamed, and shaped into a plate to produce an extruded foam, at any stage before being sufficiently cooled,
(I) A method of forming a plate by pressing to a thickness smaller than the thickness of the extruded foam,
(Ii) A method of drawing at a linear speed of 1.01 times or more with respect to the linear speed at the time of extrusion foaming and forming into a plate shape, and the like. At this time, the die lip opening height and the resin temperature, the take-up speed of the obtained foam, the type of foaming agent, the composition and amount used, the extrusion discharge amount, the resin temperature, the desired density and thickness of the extruded foam Conditions are set accordingly.

  As a pressing method of (i), for example, immediately after passing through a die lip and extruding to a low pressure region to reach a predetermined thickness, a method of sandwiching from above and below by a plate-shaped molding die, passing through the die lip, After the sheet is extruded to a predetermined thickness, it is passed between the rolls of the apparatus having the upper and lower rolls and sandwiched from above and below, and is passed between the conveyors of the apparatus having the upper and lower belt conveyors and sandwiched and pressed from above and below. The method etc. are mentioned.

  As a method of stretching (ii), for example, when passing through a die lip, extruding to a low pressure region and shaping to a predetermined thickness, it is sandwiched between an apparatus in which rolls are arranged up and down or an apparatus in which belt conveyors are arranged up and down And a method of drawing at a speed higher than the linear speed composed of the extrusion discharge amount, a method of passing between a die lip, extruding to a low pressure region and shaping to a predetermined thickness, and stretching between two or more take-up devices Etc. In addition, when extending | stretching, you may extend | stretch, heating in a heating apparatus.

  The thickness of the extruded foam of the present invention is not particularly limited, and is appropriately selected depending on the application. For example, in the case of a heat insulating material used for a building material or the like, in order to impart a preferable heat insulating property, bending strength and compressive strength, the thickness of a normal plate-like material is less than a thin material such as a sheet. Some are preferred, usually 10 to 150 mm, preferably 20 to 100 mm.

  The equivalent thermal conductivity at 20 ° C. of the extruded foam of the present invention is preferably 0.034 W / m · K (0.0292 kcal / m · hr · ° C.) or less, and 0.028 W / m · K (0.0275 kcal). / M · hr · ° C.) or less, more preferably 0.026 W / m · K (0.0258 kcal / m · hr · ° C.) or less.

  An extruded foam having an equivalent thermal conductivity of 0.034 W / m · K or less is suitably used as a building material application, and contributes to providing a comfortable living space.

  The extruded foam of the present invention has various uses, for example, building materials such as floor materials, wall materials, and roof materials, heat insulation materials for cold cars, vehicle bumpers, automobiles, etc. from the viewpoint of excellent light weight and heat insulation properties. It can be suitably used for automobile members such as ceiling materials and civil engineering members such as antifreezing agents for the ground.

  Next, the present invention will be described in detail based on examples, but the present invention is not limited to such examples. Unless otherwise specified, “%” represents wt%.

  Evaluation methods for Examples and Comparative Examples are as follows.

(1) Extruded foam dimensions (unit: mm)
Thickness: For three foamed molded products sampled at different times, as shown in FIG. 3, the thickness at the central portion (midpoint in the width direction) in the width direction (horizontal direction orthogonal to the extrusion direction) was measured, The average value was calculated.
Width: For three foamed molded products sampled at different times, as shown in FIG. 4, the width at the center in the thickness direction (the middle point in the thickness direction) was measured, and the average value was calculated.
Identification of the central portion in the thickness direction: A portion located at a value of 1/2 of the thickness from the upper surface and a value of 1/2 of the width from the left side was defined as the central portion.

(2) Density of extruded foam (unit: kg / m ³ )
For three extruded foams sampled at different times, the foam density was measured according to the method described in JIS K7222-1999 “Measurement of Foamed Plastic and Rubber—Apparent Density”, and the average value was calculated.

(3) Thermal conductivity (unit: W / m · K)
The thermal conductivity of the extruded foam was measured using a thermal conductivity measuring device (Eihiro Seiki, HC-074-300). The thermal conductivity when the partial pressure of air in the extruded foam bubbles is 51 kPa is shown in the examples.

(4) Partial pressure of air in the foam of extruded foam After extruding the extruded foam and removing a 10 mm portion from the surface, the width in the width direction is 25 mm, the length direction is 25 mm, and the thickness direction remains foam. The amount of air in the extruded foam is analyzed and measured using a gas chromatograph (GC-14A, manufactured by Shimadzu Corporation), and the average value is calculated to calculate the partial pressure of the air in the extruded foam bubbles. Asked. The measurement was performed simultaneously with the measurement of thermal conductivity.

(5) Average bubble diameter (D), average bubble diameter in thickness direction (A), average bubble diameter in extrusion direction (B) and ratio (A / B), and total area ratio of small bubbles (S)
The center part in the thickness direction was observed at a magnification of 100 times using a microscope (Keyence Digital Microscope VHX-900), and the average bubble diameter (D) and thickness direction were measured by the method described in the specification. The average bubble diameter (A), the average bubble diameter (B) in the extrusion direction and the ratio (A / B), and the total area ratio (S) of small bubbles were determined.

Example 1
[Method for producing molten resin containing foaming agent]
For 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: G680, MFR = 7.0 g / 10 min), talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) 0.1 weight Parts, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Shin Nippon Oil Co., Ltd., trade name: Polybutene LV-50), 0.2 parts by weight, silicon oxide A mixture of 0.1 part by weight (manufactured by Nippon Aerosil Co., Ltd., AEROSIL) and 1.0 part by weight of bentonite (manufactured by Hojun Co., Ltd., Bengelbright 11) was dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at 58 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is heated to 200 ° C. and kneaded. As a foaming agent near the tip of the first extruder (side connected to the second extruder), a styrenic resin composition is used. For 100% by weight of the resin composition, 4.2% by weight of i-butane (manufactured by Mitsui Chemicals), 2.1% by weight of dimethyl ether (manufactured by Taiyo Liquefied Gas Co., Ltd.) and 0.6% by weight of water were melted. The resulting styrene resin composition was press-fitted. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 15.8 Mpa, on the other hand, the press injection pressure of the foaming agent was set to 18.2 Mpa.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 124 ° C., the two are divided into two, and the molten resin containing the foaming agent is provided at the tip of the second extruder. It supplied to the feed block for 3 layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
With respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 679, MFR = 18 g / 10 min), 8.0 weight of dimethyl phthalate (made by Daihachi Chemical Industry Co., Ltd., trade name: DMP) as a plasticizer. Part was added to prepare a master batch in advance.
The obtained resin was supplied to an extruder having a diameter of 50 mm at 8 kg / hour. The supplied resin was heated to 125 ° C., melted and kneaded, and supplied to the feed block for the two-kind / three-layer multilayer lamination without diverting.
[Method for Producing Extruded Foam by Merging Melting Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
In the feed block for the two-type, three-layer multi-layer lamination temperature-controlled at 125 ° C., the molten resin (one layer) containing no blowing agent is divided into two in the thickness direction under a pressure of 3.4 MPa. The melted resin containing the foaming agent thus formed was sandwiched between the melted resin, and each was joined at a thickness of 11 mm / 3 mm / 11 mm.
The combined multi-layer flow was supplied to a die (Pura Giken Co., Ltd.) having the same function as the function of dividing and laminating the multi-layer flow described in Japanese Patent Publication No. Sho 54-23025. After that, a multi-layer flow is extruded into the atmosphere from a die lip having a rectangular cross-section of 2.0 mm in thickness and 50 mm in width, and temperature-controlled at 70 ° C., and is sandwiched between pressing molds and pressed. A rectangular parallelepiped having a thickness of 26 mm and a width of 220 mm is stretched at a stretch rate of 25% by being sandwiched and pulled by a device (I) having a belt conveyor disposed above and below, and further being pulled by a device (II) having a roll disposed vertically. An extruded foam having a five-layer structure of foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer was obtained.

The density of the obtained extruded foam is 34 Kg / m ³ , and the foamed layer is less than 1.2 times the average bubble diameter D2 and less than 0.25 mm in bubble diameter, and 1.2 times the average bubble diameter D2. It has a bubble structure composed of bubbles with the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0257 W / m · K.
The evaluation results are shown in Table 1.

(Example 2)
In [Method of manufacturing extruded foam by joining melted resin containing foaming agent and melted resin not containing foaming agent in the thickness direction], the joined multi-layer flow is extruded into the atmosphere, and belt conveyors are placed above and below In the same manner as in Example 1 except that the operation is not performed by the apparatus (II) in which the rolls are arranged on the upper and lower sides, except for the operation of being sandwiched between the apparatus (I) and the operation of the apparatus (II). An extruded foam having a five-layer structure of foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer was obtained.
The density of the obtained extruded foam was 33 kg / m ³ , and the foamed layer had less than 1.2 times the average cell diameter D2 and less than 0.25 mm in cell diameter, and 1.2 times the average cell diameter D2. It has a bubble structure composed of bubbles having the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0266 W / m · K.

(Example 3)
[Method for producing molten resin containing foaming agent]
0.1 weight of talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) with respect to 100 parts by weight of polystyrene (manufactured by PS Japan Corporation, trade name: 680, MFR = 7.0 g / 10 min) Parts, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Shin Nippon Oil Co., Ltd., trade name: Polybutene LV-50), 0.2 parts by weight, silicon oxide A mixture of 0.1 part by weight (manufactured by Nippon Aerosil Co., Ltd., AEROSIL) and 1.0 part by weight of bentonite (manufactured by Hojun Co., Ltd., Bengelbright 11) was dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at 52 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is heated to 200 ° C. and kneaded. As a foaming agent near the tip of the first extruder (side connected to the second extruder), a styrenic resin composition is used. For 100% by weight of the resin composition, 4.2% by weight of i-butane (manufactured by Mitsui Chemicals), 2.1% by weight of dimethyl ether (manufactured by Taiyo Liquefied Gas Co., Ltd.) and 0.6% by weight of water were melted. The resulting styrene resin composition was press-fitted. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 15.6 MPa, and the press injection pressure of the foaming agent was set to 17.0 MPa with respect to this.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 122 ° C., it is divided into two, and two types of molten resin containing a foaming agent are provided at the tip of the second extruder It supplied to the feed block for 3 layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
With respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 679, MFR = 18 g / 10 min), 8.0 weight of dimethyl phthalate (made by Daihachi Chemical Industry Co., Ltd., trade name: DMP) as a plasticizer. Part was added to prepare a master batch in advance.
The obtained resin was supplied to an extruder having a diameter of 50 mm at 4 kg / hour. The supplied resin was heated to 125 ° C., melted and kneaded, and supplied to the feed block for the two-kind / three-layer multilayer lamination without diverting.
[Method for Producing Extruded Foam by Merging Melting Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
In the feed block for the two-type three-layer multi-layer lamination, the temperature of which is adjusted to 120 ° C., the molten resin (one layer) containing no foaming agent is divided into two in the thickness direction under a pressure of 4.1 MPa. The melted resin containing the foaming agent thus formed was sandwiched between the melted resin, and each was joined at a thickness of 11 mm / 3 mm / 11 mm.
The combined multi-layer flow was supplied to a die (Pura Giken Co., Ltd.) having the same function as the function of dividing and laminating the multi-layer flow described in Japanese Patent Publication No. Sho 54-23025. Later, a device having a rectangular cross-section with a thickness direction of 1.5 mm and a width direction of 50 mm, and extruding the merged multi-layer flow into the atmosphere from a die lip temperature-controlled at 70 ° C., and arranging belt conveyors above and below (I) sandwiched and taken up, and further taken up by an apparatus (II) in which rolls are arranged at the top and bottom, and stretched at a stretch ratio of 1%, in a rectangular parallelepiped shape with a thickness of 29 mm and a width of 230 mm, foam layer / non-foam layer / An extruded foam having a five-layer structure of foamed layer / non-foamed layer / foamed layer was obtained.
The density of the obtained extruded foam is 34 Kg / m ³ , and the foamed layer is less than 1.2 times the average bubble diameter D2 and less than 0.25 mm in bubble diameter, and 1.2 times the average bubble diameter D2. It has a bubble structure composed of bubbles with the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0274 W / m · K.
The evaluation results are shown in Table 1.

Example 4
[Method for producing molten resin containing foaming agent]
Talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) 0.1 weight with respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: G9401, MFR = 2.2 g / 10 min) Parts, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Shin Nippon Oil Co., Ltd., trade name: Polybutene LV-50), 0.2 parts by weight, silicon oxide A mixture of 0.1 part by weight (manufactured by Nippon Aerosil Co., Ltd., AEROSIL) and 1.0 part by weight of bentonite (manufactured by Hojun Co., Ltd., Bengelbright 11) was dry blended to obtain a styrene resin composition. The styrene-based resin composition was supplied at 40 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is heated to 200 ° C. and kneaded. As a foaming agent near the tip of the first extruder (side connected to the second extruder), a styrenic resin composition is used. For 100% by weight of the resin composition, 4.5% by weight of i-butane (manufactured by Mitsui Chemicals), 2.2% by weight of dimethyl ether (manufactured by Taiyo Liquefaction Gas Co., Ltd.) and 0.7% by weight of water were melted. The resulting styrene resin composition was press-fitted. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 14.0 Mpa, on the other hand, the press injection pressure of the foaming agent was set to 15.0 Mpa.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 131 ° C., it is divided into four, and two types of molten resin containing a blowing agent are provided at the tip of the second extruder It supplied to the feed block for 7-layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
With respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 679, MFR = 18 g / 10 min), 8.0 weight of dimethyl phthalate (made by Daihachi Chemical Industry Co., Ltd., trade name: DMP) as a plasticizer. Part was added to prepare a master batch in advance.
The obtained resin was supplied to an extruder having a diameter of 50 mm at 3 kg / hour. The supplied resin was heated to 128 ° C., melted and kneaded, divided into three, and supplied to the feed block for the two types of 7-layer multilayer stack.
[Method for Producing Extruded Foam by Merging Melting Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
Each of the molten resins not containing a blowing agent divided into three in the thickness direction under a pressure of 6.9 MPa in the feed block for the two types of seven-layer multi-layer laminated at a temperature of 128 ° C. Each of them is sandwiched with molten resin containing a foaming agent divided into two, and is 5.2 mm / 1.4 mm / 5.2 mm / 1.4 mm / 5.2 mm / 1.4 mm / 5.2 mm, respectively. Combined with thickness.
The combined multi-layer flow was supplied to a die (manufactured by Pla Giken Co., Ltd.) having the same function as the function of dividing and laminating the multi-layer flow described in Japanese Patent Publication No. 54-23025. Afterwards, a device having a rectangular cross-section of 2.5 mm in thickness and 50 mm in width and extruding the combined multi-layer flow into the atmosphere from a die lip temperature-controlled at 80 ° C. and arranging belt conveyors above and below (I) is sandwiched and taken, and further stretched at a stretch ratio of 14% by pressing with another apparatus (III) in which a belt conveyor is arranged above and below, and foamed in a rectangular parallelepiped shape with a thickness of 24 mm and a width of 230 mm. Extrusion consisting of 13 layers of layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer / foamed layer / non-foamed layer / foamed layer A foam was obtained.
The resulting extruded foam has a density of 41 Kg / m ³ , and the foam layer has bubbles less than 1.2 times the average bubble diameter D2 and less than 0.25 mm in bubble diameter, and 1.2 times the average bubble diameter D2. It has a bubble structure composed of bubbles having the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0267 W / m · K.
The evaluation results are shown in Table 1.

(Example 5)
[Method for producing molten resin containing foaming agent]
0.1 weight of talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) with respect to 100 parts by weight of polystyrene (manufactured by PS Japan Corporation, trade name: 680, MFR = 7.0 g / 10 min) Parts, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Shin Nippon Oil Co., Ltd., trade name: Polybutene LV-50), 0.2 parts by weight, silicon oxide A mixture of 0.1 part by weight (manufactured by Nippon Aerosil Co., Ltd., AEROSIL) and 1.0 part by weight of bentonite (manufactured by Hojun Co., Ltd., Bengelbright 11) was dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at 46 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is heated to 200 ° C. and kneaded. As a foaming agent near the tip of the first extruder (side connected to the second extruder), a styrenic resin composition is used. For 100% by weight of the resin composition, 4.4% by weight of i-butane (manufactured by Mitsui Chemicals), 2.2% by weight of dimethyl ether (manufactured by Taiyo Liquefied Gas) and 0.7% by weight of water were melted. The resulting styrene resin composition was press-fitted. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 14.0 Mpa, on the other hand, the press injection pressure of the foaming agent was set to 15.5 Mpa.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 124 ° C., the two are divided into two, and the molten resin containing the foaming agent is provided at the tip of the second extruder. It supplied to the feed block for 3 layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
With respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 679, MFR = 18 g / 10 min), 8.0 weight of dimethyl phthalate (made by Daihachi Chemical Industry Co., Ltd., trade name: DMP) as a plasticizer. And 10.0 parts by weight of graphite (product name: X-10, manufactured by Ito Graphite Mining Co., Ltd.) were added as a heat ray radiation inhibitor to prepare a master batch.

The obtained resin was supplied to an extruder having a diameter of 50 mm at 3 kg / hour. The supplied resin was heated to 125 ° C., melted and kneaded, and supplied to the feed block for the two-kind / three-layer multilayer lamination without diverting.
[Method for Producing Extruded Foam by Merging Melting Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
In the feed block for the two-type, three-layer multi-layer lamination temperature-controlled at 125 ° C., the molten resin (one layer) containing no blowing agent is divided into two in the thickness direction under a pressure of 3.0 MPa. The melted resin containing the foaming agent thus formed was sandwiched between the melted resin, and each was joined at a thickness of 11 mm / 3 mm / 11 mm.
The combined multilayer flow was supplied to a die (manufactured by Pla Giken Co., Ltd.) having the same function as the function of dividing and laminating the multilayer flow described in Japanese Patent Publication No. 54-23025. After that, a multi-layered flow is extruded into the atmosphere from a die lip having a rectangular cross section of 2.0 mm in the thickness direction and 50 mm in the width direction and temperature-controlled at 80 ° C., and sandwiched and pressed by a molding die. Extrusion foaming is sandwiched between the apparatus (I) having a belt conveyor disposed on the upper and lower sides and taken up, and is a rectangular parallelepiped shape having a thickness of 30 mm and a width of 230 mm and having a five-layer structure of foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer. Got the body.
The density of the obtained extruded foam is 36 Kg / m ³ , and the foamed layer is less than 1.2 times the average bubble diameter D2 and less than 0.25 mm in bubble diameter, and 1.2 times the average bubble diameter D2. It has a bubble structure composed of bubbles having the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0259 W / m · K.
The evaluation results are shown in Table 1.

(Example 6)
[Method for producing molten resin containing foaming agent]
Talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) 0.1 weight with respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: G9401, MFR = 2.2 g / 10 min) Parts, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Shin Nippon Oil Co., Ltd., trade name: Polybutene LV-50), 0.2 parts by weight, silicon oxide A mixture of 0.1 part by weight (manufactured by Nippon Aerosil Co., Ltd., AEROSIL) and 1.0 part by weight of bentonite (manufactured by Hojun Co., Ltd., Bengelbright 11) was dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at 42 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is heated to 200 ° C. and kneaded. As a foaming agent near the tip of the first extruder (side connected to the second extruder), a styrenic resin composition is used. With respect to 100% by weight of the resin composition, 4.1% by weight of i-butane (manufactured by Mitsui Chemicals), 2.1% by weight of dimethyl ether (manufactured by Taiyo Liquefaction Gas Co., Ltd.) and 0.7% by weight of water were melted. The resulting styrene resin composition was press-fitted. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 13.0 Mpa, on the other hand, the press injection pressure of the foaming agent was set to 14.5 Mpa.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 131 ° C., it is divided into four, and two types of molten resin containing a blowing agent are provided at the tip of the second extruder It supplied to the feed block for 7-layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
To 85 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 679, MFR = 18 g / 10 min), dimethyl phthalate (made by Daihachi Chemical Industry Co., Ltd., trade name: DMP) 6.0 wt. In addition, 25.0 parts by weight of carbon black / PS masterbatch (manufactured by Sumika Color Co., Ltd., trade name: black (carbon black ratio 40 wt%)) was added as a heat ray radiation inhibitor to prepare a masterbatch in advance. .
The obtained resin was supplied to an extruder having a diameter of 50 mm at 3 kg / hour. The supplied resin was heated to 135 ° C., melted and kneaded, divided into three, and supplied to the feed block for the two types of 7-layer multilayer stack.
[Method for Producing Extruded Foam by Merging Melting Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
Each of the molten resins not containing a blowing agent divided into three in the thickness direction under a pressure of 7.0 MPa in the feed block for two kinds of seven-layer multilayer laminated at 135 ° C. In the thickness of 5.2 mm / 1.4 mm / 5.2 mm / 1.4 mm / 5.2 mm / 1.4 mm / 5.2 mm, respectively, so as to be sandwiched between the molten resin containing the blowing agent divided into the two Merged. The combined multilayer flow was supplied to a die (manufactured by Pla Giken Co., Ltd.) having the same function as the function of dividing and laminating the multilayer flow described in Japanese Patent Publication No. 54-23025. After that, the multi-layered flow is extruded into the atmosphere from a die lip having a rectangular cross section of 2.5 mm in the thickness direction and 50 mm in the width direction, and temperature-controlled at 80 ° C., and sandwiched and pressed by a molding die. , Sandwiched and taken up by a device (I) having a belt conveyor disposed above and below, and in the form of a rectangular parallelepiped having a thickness of 24 mm and a width of 230 mm, foam layer / non-foam layer / foam layer / non-foam layer / foam layer / non-foam layer / foam layer / An extruded foam having a 13-layer structure of non-foamed layer / foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer was obtained.
The density of the obtained extruded foam is 40 Kg / m ³ , and the foamed layer is less than 1.2 times the average bubble diameter D2 and less than 0.25 mm in bubble diameter, and 1.2 times the average bubble diameter D2. It has a bubble structure composed of bubbles having the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0273 W / m · K.
The evaluation results are shown in Table 1.

(Example 7)
[Method for producing molten resin containing foaming agent]
For 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 680, MFR = 7.0 g / 10 min), talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) 0.5 weight Part, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Nippon Oil Corporation, trade name: polybutene LV-50) 0.1 parts by weight Were dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at 60 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is kneaded by heating to 180 ° C., and as a foaming agent near the tip of the first extruder (the side connected to the second extruder) Styrenic resin composition obtained by melting 4.0% by weight of i-butane (manufactured by Mitsui Chemicals) and 4.0% by weight of dimethyl ether (manufactured by Taiyo Liquefaction Gas Co., Ltd.) with respect to 100% by weight of the resin composition. Press-fitted into. At this time, the resin pressure at the tip of the first extruder was 15.2 MPa, while the press-fitting pressure of the foaming agent was 13.3 MPa.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 121 ° C., it is divided into two, and the molten resin containing the foaming agent is provided at the tip of the second extruder. It supplied to the feed block for 3 layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
With respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 679, MFR = 18 g / 10 min), 8.0 weight of dimethyl phthalate (made by Daihachi Chemical Industry Co., Ltd., trade name: DMP) as a plasticizer. Part was added to prepare a master batch in advance.
The obtained resin was supplied to an extruder having a diameter of 50 mm at 2 kg / hour. The supplied resin was heated to 125 ° C., melted and kneaded, and supplied to the feed block for the two-kind / three-layer multilayer lamination without diverting.
[Method for Producing Extruded Foamed Molded Body by Melting Melted Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
In the feed block for the two-type three-layer multi-layer lamination controlled at 120 ° C., the molten resin (one layer) containing no blowing agent is divided into two in the thickness direction under a pressure of 3.1 MPa. The melted resin containing the foaming agent thus formed was sandwiched between the melted resin, and each was joined at a thickness of 11 mm / 3 mm / 11 mm.
The merged multilayer flow was supplied to a die (manufactured by Pla Giken Co., Ltd.) having the same function as the function of dividing and laminating the multilayer flow described in Japanese Patent Publication No. Sho 54-23025. After that, a multi-layered flow is extruded into the atmosphere from a die lip having a rectangular cross section of 1.6 mm in thickness direction and 50 mm in width direction, and temperature-controlled at 80 ° C., and sandwiched and pressed by a molding die. Extrusion foaming is sandwiched between the apparatus (I) having a belt conveyor arranged on the upper and lower sides and taken up, and is a rectangular parallelepiped shape having a thickness of 29 mm and a width of 230 mm and having a five-layer structure of foam layer / non-foam layer / foam layer / non-foam layer / foam layer. A molded body was obtained.
The density of the obtained extruded foamed product is 33 kg / m ³ , and the foamed layer has bubbles having a bubble diameter of less than 1.2 times the average bubble diameter D2 and a bubble diameter of 0.25 mm or less, and a mean bubble diameter D2 of 1.2. It did not have a bubble structure composed of bubbles having a bubble diameter more than double, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0298 W / m · K.
The evaluation results are shown in Table 1.

(Example 8)
[Method for producing molten resin containing foaming agent]
Talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) 0.1 weight with respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: G9401, MFR = 2.2 g / 10 min) Parts, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Shin Nippon Oil Co., Ltd., trade name: Polybutene LV-50), 0.2 parts by weight, silicon oxide A mixture of 0.1 part by weight (manufactured by Nippon Aerosil Co., Ltd., AEROSIL) and 1.0 part by weight of bentonite (manufactured by Hojun Co., Ltd., Bengelbright 11) was dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at a rate of 64 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is heated to 200 ° C. and kneaded. As a foaming agent near the tip of the first extruder (side connected to the second extruder), a styrenic resin composition is used. With respect to 100% by weight of the resin composition, 3.8% by weight of i-butane (manufactured by Mitsui Chemicals), 1.9% by weight of dimethyl ether (manufactured by Taiyo Liquefied Gas Co., Ltd.) and 0.7% by weight of water were melted. The resulting styrene resin composition was press-fitted. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 14.5 Mpa, on the other hand, the press injection pressure of the foaming agent was set to 16 Mpa.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 130 ° C., it is divided into four, and two types of molten resin containing a foaming agent are provided at the tip of the second extruder It supplied to the feed block for 7-layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
A polystyrene-acrylic copolymer (manufactured by PS Japan Co., Ltd., trade name: SC004) was supplied to an extruder having a diameter of 50 mm at 4.5 kg / hour. The supplied resin was heated to 135 ° C., melted and kneaded, divided into three, and supplied to the feed block for the two types of 7-layer multilayer stack.
[Method for Producing Extruded Foam by Merging Melting Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
Within each of the two types of 7-layer multi-layer feed block temperature-controlled at 130 ° C., each of the four molten resin containing no blowing agent divided into three in the thickness direction under a pressure of 8 MPa. The molten resin containing the divergent foaming agent is sandwiched between the melted resin so that the thicknesses are 5.2 mm / 1.4 mm / 5.2 mm / 1.4 mm / 5.2 mm / 1.4 mm / 5.2 mm. After that, it has a rectangular cross-section with a thickness of 2.5 mm and a width of 50 mm, and from the die lip temperature-controlled at 80 ° C., the combined multi-layer flow is pushed out into the atmosphere and sandwiched between molding dies and pressed. Then, it is sandwiched and taken up by the apparatus (I) in which the belt conveyor is arranged on the upper and lower sides, and has a rectangular parallelepiped shape having a thickness of 24 mm and a width of 230 mm, and a foam layer / non-foam layer / foam layer / non-foam layer / foam layer / non-foam layer / foam layer From the seven-layer structure It was obtained extruded foam.
The density of the obtained extruded foam was 37 kg / m ³ , and the foamed layer had less than 1.2 times the average cell diameter D2 and less than 0.25 mm in cell diameter, and 1.2 times the average cell diameter D2. It has a bubble structure composed of bubbles having the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0273 W / m · K.
The evaluation results are shown in Table 1.

(Comparative Example 1)
[Method for producing molten resin containing foaming agent]
For 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 680, MFR = 7.0 g / 10 min), talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) 0.5 weight Part, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Nippon Oil Corporation, trade name: polybutene LV-50) 0.1 parts by weight Were dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at 49 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is kneaded by heating to 180 ° C., and as a foaming agent near the tip of the first extruder (the side connected to the second extruder) Styrenic resin composition obtained by melting 4.0% by weight of i-butane (manufactured by Mitsui Chemicals) and 4.0% by weight of dimethyl ether (manufactured by Taiyo Liquefaction Gas Co., Ltd.) with respect to 100% by weight of the resin composition. Press-fitted into. At this time, the resin pressure at the tip of the first extruder was 10.0 MPa, while the press-fitting pressure of the foaming agent was 12.0 MPa.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 130 ° C., it is divided into two, and two types of molten resin containing a foaming agent are provided at the tip of the second extruder It supplied to the feed block for 3 layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for Producing an Extrusion Foam Molded Product by Merging Molten Resin Containing Foaming Agent in the Thickness Direction]
In the feed block for the two kinds of 7-layer multi-layer lamination, the temperature of which is adjusted to 128 ° C., a molten resin containing a foaming agent divided into two in the thickness direction under a pressure of 2.9 MPa, It merged with the thickness of 11 mm / 11 mm. The combined multilayer flow was supplied to a die (manufactured by Pla Giken Co., Ltd.) having the same function as the function of dividing and stacking the multilayer flow described in Japanese Patent Publication No. Sho 54-23025. After that, a multi-layered flow is extruded into the atmosphere from a die lip having a rectangular cross section of 1.6 mm in thickness direction and 50 mm in width direction, and temperature-controlled at 80 ° C., and sandwiched and pressed by a molding die. Then, it was sandwiched and taken up by the apparatus (I) in which the belt conveyors were arranged on the upper and lower sides to obtain an extrusion foamed molded article having a rectangular parallelepiped shape having a thickness of 22 mm and a width of 230 mm and having a single layer structure of only a foam layer.
The density of the obtained extruded foamed product is 30 kg / m ³ , and the foam layer has bubbles having a bubble diameter of less than 1.2 times the average bubble diameter D2 and a bubble diameter of 0.25 mm or less, and an average bubble diameter D2 of 1.2. It did not have a bubble structure composed of bubbles having a bubble diameter more than double, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0311 W / m · K.
The evaluation results are shown in Table 1.

(Comparative Example 2)
[Method for producing molten resin containing foaming agent]
For 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: G680, MFR = 7.0 g / 10 min), talc (manufactured by Hayashi Kasei Co., Ltd., trade name: TALCAN PAWDER PK-Z) 0.1 weight Parts, calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: calcium stearate) 0.3 parts by weight, liquid paraffin (manufactured by Shin Nippon Oil Co., Ltd., trade name: Polybutene LV-50), 0.2 parts by weight, silicon oxide A mixture of 0.1 part by weight (manufactured by Nippon Aerosil Co., Ltd., AEROSIL) and 1.0 part by weight of bentonite (manufactured by Hojun Co., Ltd., Bengelbright 11) was dry blended to obtain a styrene resin composition. The styrenic resin composition was supplied at 46 kg / hour to a two-stage extruder in which a first extruder having a diameter of 65 mm and a second extruder having a diameter of 90 mm were connected in series.
The styrenic resin composition supplied to the first extruder is heated to 200 ° C. and kneaded. As a foaming agent near the tip of the first extruder (side connected to the second extruder), a styrenic resin composition is used. For 100% by weight of the resin composition, 4.4% by weight of i-butane (manufactured by Mitsui Chemicals), 2.2% by weight of dimethyl ether (manufactured by Taiyo Liquefied Gas Co., Ltd.) and 0.6% by weight of water were melted. The resulting styrene resin composition was press-fitted. Under the present circumstances, the resin pressure in the front-end | tip of a 1st extruder was 16.0 MPa, and the press injection pressure of the foaming agent was set to 17.2 MPa with respect to this.
In the second extruder connected to the first extruder, after the resin temperature is cooled to 128 ° C., the two are divided into two, and the molten resin containing the foaming agent is provided at the tip of the second extruder. It supplied to the feed block for 3 layer multilayer lamination (made by Pla Giken Co., Ltd.).
[Method for producing molten resin containing no foaming agent]
With respect to 100 parts by weight of polystyrene (manufactured by PS Japan Co., Ltd., trade name: 679, MFR = 18 g / 10 min), 8.0 weight of dimethyl phthalate (made by Daihachi Chemical Industry Co., Ltd., trade name: DMP) as a plasticizer. Part was added to prepare a master batch in advance.
The obtained resin was supplied to an extruder having a diameter of 50 mm at 4 kg / hour. The supplied resin was heated to 130 ° C., melted and kneaded, and supplied to the feed block for the two-kind / three-layer multi-layer lamination without diversion.
[Method for Producing Extruded Foam by Merging Melting Resin Containing Foaming Agent and Molten Resin Not Containing Foaming Agent in Thickness Direction]
In the feed block for the two-type, three-layer multi-layer lamination temperature-controlled at 130 ° C., the molten resin (one layer) containing no blowing agent is divided into two in the thickness direction under a pressure of 5.0 MPa. The melted resin containing the foaming agent thus formed was sandwiched between the melted resin, and each was joined at a thickness of 11 mm / 3 mm / 11 mm.
The combined multilayer flow was supplied to a die (manufactured by Pla Giken Co., Ltd.) having the same function as the function of dividing and stacking the multilayer flow described in Japanese Patent Publication No. Sho 54-23025. After that, a device having a rectangular cross section with a thickness direction of 1.4 mm and a width direction of 50 mm, and extruding the merged multilayer flow into the atmosphere from a die lip temperature-controlled at 80 ° C., and arranging belt conveyors above and below The extruded foam was sandwiched and pulled to the extent that it was not pressed into (I), and was a rectangular parallelepiped having a thickness of 28 mm and a width of 240 mm and having a five-layer structure of foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer.
The density of the obtained extruded foam is 36 Kg / m ³ , and the foamed layer is less than 1.2 times the average bubble diameter D2 and less than 0.25 mm in bubble diameter, and 1.2 times the average bubble diameter D2. It has a bubble structure composed of bubbles with the above bubble diameter, and the thermal conductivity at an air partial pressure of 51 kPa was 0.0288 W / m · K.
The evaluation results are shown in Table 1.
The air contents after 8 days of trial production of Example 7 which is an example of the present invention and Comparative Example 1 which is a comparative example are 55 kPa and 83 kPa, respectively. In the example of the present invention, the ingress of air is suppressed. It was confirmed that

1. 1. Thickness measurement position of extruded foam molding Width measurement position of extruded foam

Claims (11)

An extruded foam having a structure in which a foam layer is laminated via a non-foam layer in the thickness direction,
In the cells having a density of 20 to 65 kg / m ³ and the extruded foam constituting the foamed layer located in the center in the thickness direction, the average cell diameter (A) in the thickness direction and the average cell diameter in the extrusion direction An extruded foam characterized in that the ratio (A / B) of (B) satisfies 0.3 to 1.5. An extruded foam having a structure in which a foam layer is laminated via a non-foam layer in the thickness direction,
The foam layer has a density of 20 to 65 kg / m ³ , and the foam layer has a small bubble having a bubble diameter less than 1.2 times the average bubble diameter D2, and a bubble diameter of 1.2 times or more the average bubble diameter D2. The bubbles constituting the foamed layer located in the central part in the thickness direction have a bubble structure composed of large bubbles, the average bubble diameter of small bubbles is 0.25 mm or less, and the average bubble diameter in the thickness direction ( An extruded foam characterized by satisfying a ratio (A / B) of 0.3 to 1.5 of A) and an average cell diameter (B) in the extrusion direction.   The extruded foam according to claim 1 or 2, wherein an average cell diameter (A) in the thickness direction of the foam layer is 0.03 to 0.40 mm. The extruded foam according to claim 1, wherein the density of the extruded foam is 20 to 40 kg / m ³ .   The bubbles constituting the foam layer located in the central part in the thickness direction have a ratio (A / B) of the average cell diameter (A) in the thickness direction to the average cell diameter (B) in the extrusion direction of 0.3 to 1.0. The extruded foam according to claim 1, wherein:   The ratio of the total area of bubbles having a bubble diameter of 0.25 mm or less occupying the cross section of the foamed layer located in the central portion in the thickness direction of the extruded foam is 5 to 95%. The extruded foam according to any one of the above.   The extruded foam according to any one of claims 1 to 6, wherein the extruded foam has a plurality of structures in which a foamed layer is laminated via a non-foamed layer in the thickness direction.   The resin constituting the foam layer is at least one resin selected from the group consisting of polystyrene, styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, and modified polyphenylene ether resin. The extruded foam according to any one of claims 1 to 7.   The one or more types of hydrocarbons selected from the group consisting of propane, n-butane, i-butane and cyclopentane are contained in the bubbles constituting the foam layer. The extruded foam according to any one of the above. Having a structure in which the foamed layer is laminated through the non-foamed layer in the thickness direction, the density is 20 to 65 kg / m ³ , and
In the bubbles constituting the foam layer located in the center in the thickness direction, the ratio (A / B) of the average bubble diameter (A) in the thickness direction to the average bubble diameter (B) in the extrusion direction is 0.3 to 1.5. A method for producing an extruded foam satisfying
A method for producing an extruded foam, which is obtained by a coextrusion method in which a molten resin containing a foaming agent and a molten resin not containing a foaming agent are joined together in a thickness direction under high pressure and then released under atmospheric pressure. . Having a structure in which the foamed layer is laminated through the non-foamed layer in the thickness direction, the density is 20 to 65 kg / m ³ , and
The foam layer has a cell structure composed of small bubbles having a cell diameter less than 1.2 times the average cell diameter D2 and large cells having a cell diameter of 1.2 times or more the average cell diameter D2. The average cell diameter in the thickness direction (A) and the average cell diameter in the extrusion direction (B) in the bubbles constituting the foamed layer located in the central portion in the thickness direction are 0.25 mm or less in average cell diameter. The ratio (A / B) of the extruded foam satisfying 0.3 to 1.5,
The extruded foam is obtained by a co-extrusion method in which a molten resin containing a blowing agent and a molten resin not containing a blowing agent are merged in a thickness direction under high pressure and then released under atmospheric pressure, Method for producing extruded foam.

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