WO2009128440A2

WO2009128440A2 - Composite foamed-resin sheet

Info

Publication number: WO2009128440A2
Application number: PCT/JP2009/057489
Authority: WO
Inventors: 文剛永森
Original assignee: 積水化学工業株式会社
Priority date: 2008-04-18
Filing date: 2009-04-14
Publication date: 2009-10-22
Also published as: JPWO2009128440A1

Abstract

A composite foamed-resin sheet which suffers neither the cracking nor breakage of a surface metal foil upon bending which has been a problem for conventional metal-foil-laminated foams. The composite sheet is excellent in heat-insulating properties, suitability for environmental preservation, and processability and is usable as a material for air-conditioning ducts. The composite sheet is a polyolefin-based composite foamed-resin sheet characterized by comprising a polyolefin resin foam having cells with an aspect ratio, Dz/Dxy, of 1.1-5.0 on the average and having an expansion ratio of 4-20 and a compression strength of 0.05 MPa or higher and a metal foil having an average thickness of 5-200 µm laminated to at least one side of the foam, part or the whole of at least one side of the sheet having been embossed.

Description

Composite foam resin sheet

The present invention relates to an olefin-based composite foamed resin sheet that can be folded while maintaining a certain hardness and that can retain its shape.

In recent years, from the viewpoint of lightness and environment, a composite material obtained by laminating aluminum foil on corrugated paper as a metal substitute such as galvanized steel sheet generally used as a material for air conditioning ducts has attracted attention. For example, in Patent Document 1 and Patent Document 2, a non-combustible corrugated cardboard in which a core material made of corrugated paper is covered with an aluminum foil and a non-combustible layer is interposed between the core material and the aluminum foil is corrugated cardboard. Despite the use of paper, it has been reported that it can meet the requirements of non-combustible materials in the Building Standards Act, which is the required performance of air conditioning ducts. In addition, it is lighter than galvanized steel, so it is easy to install, and since it has heat insulation, there is no need to use a large amount of heat insulating material such as glass wool, and there is an advantage that the amount of industrial waste at the time of removal can be reduced. Is done.

However, since the non-combustible corrugated cardboard is made of corrugated paper, the aluminum foil can maintain a certain level of hermeticity, but it is highly likely to absorb moisture in the atmosphere depending on the conditions of construction and the surrounding environment. Issues remain from the viewpoint of durability. In addition, the non-combustible corrugated cardboard is also difficult to bend in a certain direction because of the anisotropy in strength due to the characteristics of the corrugated cardboard in terms of workability, and processing restrictions may occur.

For such points, heat insulation, better environmental properties than galvanized steel air conditioning duct, can include the advantages of corrugated cardboard ducts, and as a material that can overcome the problems of corrugated cardboard ducts, resin foams are preferred, especially bent, From the viewpoint of processability such as cutting, an olefin resin foam is preferred.

Generally, olefin-based resins can maintain appropriate heat insulation by foaming. This is also highly recyclable with respect to disposal.

However, in general, the olefin-based resin foam has a high expansion ratio and can be bent if it is soft and soft, but it is difficult to maintain the shape because of insufficient rigidity, and the compressive strength is kept low. At the time of construction, deformation of the material itself is likely to occur due to deformation such as dents due to local load generation. In the case of hard foaming, there is a possibility of cracking during bending. In addition, the olefin resin itself has a problem that it is difficult to maintain the flameproof property, which is a necessary requirement of the air conditioning duct, and it tends to burn.

In order to overcome such a problem, use of a polyolefin resin foam described in Patent Document 3 is conceivable. Since this polyolefin resin foam has flexibility for bending despite its high compressive strength, it can be bent or heat-shaped without cracking. Therefore, even if a certain amount of external force is applied during construction, the shape can be maintained without causing deformation such as a dent, and the durability after construction is excellent. From the viewpoint of flameproofness, Patent Document 4 and Patent Document 5 propose a composite foamed resin sheet obtained by laminating a metal foil on the surface. The composite foamed resin sheet having such a laminated structure can impart fire resistance to the resin foam from the performance of the metal foil.

However, in this configuration, the surface layer of the composite foamed resin sheet is made of a metal foil, so that stress in the tensile direction is generated on the surface layer on one side during bending, and cracks and fractures occur if the metal foil cannot withstand the stress. It will occur. When cracks and breaks occur in the metal foil, it is impossible to maintain flameproofness and nonflammability against the spread of the surface layer portion of the composite foamed resin sheet. Therefore, the bending process range is limited so that the surface layer does not crack or break, making it difficult to use the composite foamed resin sheet in the air conditioning duct field. A method of increasing the strength by increasing the thickness of the metal foil is also conceivable, but in this case, it is difficult to bend, and workability and cost become problems.
JP 2006-1095 A JP 2007-147185 A Japanese Patent No. 312267 JP 2001-310432 A JP 2005-238573 A

Therefore, the present invention does not cause cracking or breaking of the surface metal foil at the time of bending, which was a problem of the above-mentioned metal foil laminated foam, and is excellent in heat insulation, environmental performance, workability, and air conditioning duct material It aims at providing the composite foaming resin sheet which can be used for.

The polyolefin-based composite resin foamed resin sheet according to the present invention has an average aspect ratio Dz / Dxy of internal bubbles of 1.1 to 5.0, a foaming ratio of 4 to 20 times, and a compressive strength of 0.05 MPa or more. The composite foamed resin sheet in which a metal foil having an average thickness of 5 μm to 200 μm is laminated on at least one surface of a polyolefin resin foam is characterized in that at least a part or the entire surface of the metal foil side is subjected to a textured process. To do.

In order to increase the flame retardancy of the polyolefin resin foam, the foam contains 5 to 30 parts by weight of a flame retardant with respect to 100 parts by weight of the polyolefin resin.

In the method for producing a polyolefin-based composite resin foamed resin sheet according to the present invention, the top and bottom of a foamable laminate formed by laminating metal foil on at least one surface of a polyolefin-based resin foamable sheet is sandwiched between two endless belts and heated. In this method, the foamed sheet is foamed and then cooled, and the endless belt on the metal foil side has a textured shape on the surface.

The processed product of the polyolefin-based composite resin foamed resin sheet according to the present invention can be manufactured into a desired shape by making a crease using a wedge-shaped metal fitting.

The polyolefin composite resin foamed resin sheet and processed product according to the present invention are useful as, for example, a duct material for air conditioning.

First, the polyolefin resin foam constituting the main body of the polyolefin composite resin foam resin sheet according to the present invention will be described.

The polyolefin resin foam has an average value of the aspect ratio Dz / Dxy [Dz (maximum diameter parallel to the foam thickness direction) / Dxy (maximum diameter parallel to the foam width or length direction)] of the internal bubbles. The foaming ratio is 1.1 to 5.0, the expansion ratio is 4 to 20 times, preferably 6 to 17 times, and the compressive strength is 0.05 MPa or more, preferably 0.1 to 1.5 MPa.

The resin component used for the resin foam sheet is a polyolefin resin because of its advantages of processability and recyclability. The polyolefin resin used may be a homopolymer or copolymer of an olefin monomer, and is not particularly limited. For example, low density polyethylene, high density polyethylene, linear low density Polyethylene such as polyethylene, polypropylene such as propylene homopolymer, propylene random polymer, propylene block polymer, polybutene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer A copolymer having ethylene as a main component, such as a polymer, is preferably used. Among them, polyethylene and polypropylene are particularly preferably used. These polyolefin resin may be used independently and 2 or more types may be used together.

Further, the polyolefin resin may be a polyolefin resin composition in which other resin of less than 30% by weight is added to the polyolefin resin. Although it does not specifically limit as said other resin, For example, a polystyrene, a styrene-type elastomer, etc. are mentioned. These other resins may be used alone or in combination of two or more.

If the amount of other resin added to the polyolefin resin is 30% by weight or more, the excellent properties of the polyolefin resin such as light weight, chemical resistance, flexibility, and elasticity may be hindered. Sometimes it may be difficult to ensure the necessary melt viscosity.

Furthermore, the polyolefin resin may be a polyolefin resin composition to which a modifying monomer is added. The modifying monomer is not particularly limited, and examples thereof include dioxime compounds, bismaleimide compounds, divinylbenzene, allyl polyfunctional monomers, (meth) acrylic polyfunctional monomers, and quinone compounds. These modifying monomers may be used alone or in combination of two or more.

Particularly in this case, the polyolefin resin foam has an aspect ratio [Dz (maximum diameter parallel to the foam thickness direction) / Dxy (maximum parallel to the foam width or length direction) of the inherent cell for improving the compression performance. The average value of (diameter)] is 1.1 to 5.0, and the expansion ratio is 4 to 20 times. If the expansion ratio of the foam is less than 4 times, the compression strength (compression modulus) becomes too high and it becomes hard to bend, and conversely, if the expansion ratio of the foam exceeds 20 times, The thickness becomes thin, the compression strength (compression modulus) becomes insufficient, and it is difficult to maintain the shape.

Regarding the foaming ratio, after cutting a plate-like sample from the foamed part with a cutter, the apparent density is measured according to JIS K-6767 “Testing method for polyethylene foam”, and the reciprocal number is taken as the foaming ratio.

Compressive strength is defined as the higher of the maximum stress value or the yield point stress measured when the sample is compressed to 10% of the thickness with reference to JIS K 7220.

The polyolefin resin foam has a compressive strength of 0.05 MPa or more, preferably 0.1 to 1.5 MPa. If the compressive strength of the foam is less than 0.05 MPa, dents are likely to be generated with respect to local loads, and the sheet is too soft to maintain the processed shape.

FIG. 1 (a) is a perspective view showing a foam, and FIG. 1 (b) is an enlarged view of portion A in FIG. 1 (a). The average value of the aspect ratio [Dz (maximum diameter parallel to the foam thickness direction) / Dxy (maximum diameter parallel to the foam width or length direction)] is the inside of the foam (1) shown in FIG. It means the number (arithmetic) average value of the ratio of the maximum directional diameter in the cell (3) and is measured by the following method.

Measuring method of average value of aspect ratio (Dz / Dxy): Take a 50 times magnified photograph of an arbitrary cross section (2) parallel to the thickness direction (referred to as z direction) of foam (1) and select at random The maximum diameter in the fixed direction of at least 50 cells (3) is measured in the following two directions, and the number (arithmetic) average value of each aspect ratio (Dz / Dxy) is calculated.

Dz: Maximum diameter parallel to the Z direction of the cell (3) in the foam (1) Dxy: In the foam width direction or the foam length direction of the cell (3) in the foam (1), that is, in the z direction The above aspect ratio [Dz (maximum diameter parallel to foam thickness direction) / Dxy (maximum diameter parallel to foam width or length direction)] which is the maximum diameter parallel to the vertical surface direction (referred to as xy direction)] By making the average value of 1.1 to 5.0 (preferably 1.2 to 2.2), the cell (3) in the foam (1) has a long axis in the thickness direction of the foam (1). A spindle-shaped cell (3) having Therefore, when the foam (1) receives a compressive force in the thickness direction, the compressive force is applied in the major axis direction of the spindle-shaped cell (3), so the foam (1) is high in the thickness direction. The compressive strength (compression elastic modulus) can be expressed. If the aspect ratio exceeds 5.0, the foam becomes too brittle and difficult to bend.

Further, the average value of Dxy of the cells (3) inside the foam (1) is not particularly limited, but is preferably 500 μm or more, more preferably 800 μm or more.

The method for producing a polyolefin resin foam in the present invention can be produced by foaming a polyolefin resin foam sheet prepared by the method of an example described in Japanese Patent No. 3766249, for example.

In the production process of the polyolefin resin foam, the foamable sheet is preferably foamed using a continuous foaming apparatus. The foaming method using the continuous foaming device is not particularly limited. For example, a take-up type foaming device that continuously foams the foamable sheet while taking the foam on the outlet side of the heating furnace. And a foaming method using a belt-type foaming apparatus, a vertical or horizontal foaming furnace, a hot air thermostat, and a foaming method in a hot bath such as an oil bath, a metal bath or a salt bath. A double belt type foaming method is preferable. This consists of sandwiching a foamable sheet between two upper and lower endless belts of a double belt type foaming apparatus and heating the foamable sheet in a heating furnace to foam the foamable sheet. A foamed sheet manufacturing method for obtaining a foam by cooling with a cooling device, wherein a heating blower connected to a heating source is disposed in a furnace covered with a heating element, and the endless belt is heated by the heating blower while the furnace is heated. It circulates inside. (See Japanese Patent No. 3766249, Japanese Patent Laid-Open No. 2005-059309)
Next, the metal foil laminated on at least one surface of the polyolefin resin foam will be described.

The metal foil laminated on the polyolefin resin foam has a thickness of 5 to 200 μm, preferably 7 to 150 μm, more preferably 20 to 120 μm. If the thickness is less than 5 μm, it is easy to break in terms of strength, and it is difficult to obtain a shape retention effect, so that it is difficult to process. On the other hand, if this thickness exceeds 200 μm, the rigidity of the metal foil as the face material becomes too large and it becomes difficult to bend. Therefore, the thickness of the metal foil is preferably 5 to 200 μm. In consideration of nonflammability, cost, and handleability, a thickness of 20 to 120 μm is most preferable. Although metal foil does not specifically limit, Aluminum foil, stainless steel foil, titanium alloy foil, nickel alloy foil, bronze foil, tin foil, zinc alloy foil, brass foil, etc. are mentioned. Aluminum foil is preferable from the viewpoint of economy and productivity.

For metal foil, immediately before the foamable sheet is put into the heating furnace of the continuous foaming apparatus when molding the foam, the metal foil is placed at the stacking position, and the foamable sheet and the metal foil are simultaneously fed into the heating furnace of the continuous foaming apparatus. . Then, the foamable sheet is melted, and the foamable sheet and the metal foil are laminated and integrated to foam.

The metal foil may be directly laminated on the foam, or may be laminated via an intermediate layer such as a thermoplastic resin film, a nonwoven fabric, inorganic fibers, or paper. In addition, the use of thermoplastic hot melt adhesives and surface modification effects such as primer treatment and corona discharge on the metal foil surface are effective means for improving the adhesive strength between the foam sheet and aluminum foil. is there.

A further feature of the present invention is that a texture is formed on at least one side of a laminate comprising a polyolefin resin foam and a metal foil laminated thereon. “Wrinkles” are originally irregularities that appear on the surface of the fabric due to the warp of the yarn (Ojizumi). In the present invention, “wrinkles” are the purpose of adding functionality and design to the surface of the molded product. It means uneven patterns such as leather, satin, wood, and cloth. The shape of the embossing is not particularly limited, but if the embossed recess is too deep, the foamability is impaired, and if it is too shallow, the above-described effects cannot be exhibited. Therefore, the depth of the embossed recess is preferably 0.01 to 1 mm.

The texture on the surface of the laminate may be formed in advance on the surface of the metal foil, or may be formed on the foamed laminate obtained by laminating the metal foil on the polyolefin resin foamable sheet or the foamed laminate after the foaming. However, the latter is preferable from an economic point of view.

In more detail, the latter uses a belt having an embossed shape with an average unevenness depth of 0.01 to 1.00 mm on the surface of a foamed laminate obtained by laminating a metal foil on at least one side of a polyolefin resin foamable sheet. This is a method in which the embossed shape is pressure-transferred onto the surface of the laminate before or after foaming of the foamable laminate while being conveyed through the foaming apparatus. As described above, the composite foamed resin sheet according to the present invention can add flame resistance to the polyolefin resin foam by laminating a metal foil on the polyolefin resin foam. By including a flame retardant, the non-flammability can be increased without impairing the productivity of the foamed resin sheet itself, and if the specific conditions are met, meet the standards in the non-flammable material test stipulated in the Building Standards Act Is possible. The flame retardant used is not limited, but a halogen flame retardant is particularly effective. Examples include chlorine-based flame retardants such as decabromodiphenyl ether, tetrabromobisphenol-A, TBA-bis [2,3-dibromopropyl ether], TBA-bis [allyl ether], hexabromocyclodecane, tribromophenol. . In particular, a brominated flame retardant such as ethylene bispentabromobenzene is preferable from the viewpoint of safety. In addition, non-halogen flame retardants such as antimony trioxide, heat-expandable graphite, phosphorus, magnesium hydroxide, aluminum hydroxide, and various inorganic substances can be used. These flame retardants may be used alone or in combination of two or more. The combined use of antimony trioxide and a brominated flame retardant exhibits a flame retardant effect effectively. In particular, the combined use of ethylenebispentabromobenzene and antimony trioxide (ratio is around 2: 1) is preferable. The flame retardant is preferably added in an amount of 5 to 30 parts by weight with respect to 100 parts by weight of the polyolefin resin. If this proportion is less than 5 parts by weight, the effect of flame retardancy cannot be sufficiently exerted, and if it exceeds 30 parts by weight, the foamability tends to be inhibited.

Next, a method for producing a composite foamed resin sheet will be described.

The method for producing a composite foamed resin sheet according to the present invention comprises a foamed laminate formed by laminating a metal foil on at least one side of a polyolefin resin foamable sheet, sandwiched between two endless belts, and heated to be foamable. A method for producing a composite foamed resin sheet that is cooled after foaming the sheet, wherein the endless belt on the metal foil side has a textured shape on the surface.

In the production method of the present invention, the endless belt on the metal foil side has an embossed shape with an average unevenness height difference (average height difference between the highest point and the lowest point on the embossed surface) of 0.01 to 1 mm on the surface. preferable. By supplying such a belt into the foaming apparatus, the embossed surface is pressed on the surface of the laminate at any timing from the heating before foaming of the foamable laminate to the cooling after foaming. Transcribed.

In this method, the surface of the endless belt itself on the metal foil side for conveying the foamable laminate is subjected to graining in advance. In the heating and foaming process, particularly in the double belt type foaming process, the foamable sheet is very soft because the foamable sheet is close to or melted before and after foaming, and preferably after the foamable laminate is heated. A method is preferred in which the embossed shape of the belt is pressure-transferred onto the surface of the laminate before and after foaming. In addition, it is possible to use the pressure applied by a cooling roll or the like used to cool the foamed layered body provided at the rear of the foaming device. In the double belt type foaming method described above, By embossing at least one surface of two endless belts in advance, an embossed shape can be easily formed on the composite foamed resin sheet. For example, when a foamable laminate comprising a polyolefin resin foamable sheet and a metal foil is carried into a heating furnace of a double belt type foaming apparatus using two upper and lower endless belts, the foamable sheet foams and the metal foil becomes a foamed layer. And solidify after cooling. At that time, a textured shape can be formed on the surface layer of the composite resin foam sheet by the textured shape provided on at least one surface of the upper and lower two endless belts. Explaining the mechanism, although the timing from the start to the end of pressurization is not specified in detail, the outer surface of the conveying belt driven in the foaming heating furnace (the upper belt is the upper surface relative to the belt, the lower belt is the belt There are several heat transfer rolls on the lower surface) to control the thermal conductivity for the purpose of heating foaming and maintaining the shape after foaming. The weight of the heat transfer roll provided on the outer surface of the upper belt By applying forced pressure to the roll, the embossed shape processed on at least one surface of the upper belt and the lower belt can be pressure-transferred to the surface of the laminate while the foamable laminate is conveyed in the foaming apparatus. In addition, since the compressive strength of the foamable laminate and the foamed laminate after the foaming is reduced at the time of pressurization before and after foaming, the shape of the belt surface is transferred to the surface layer of the structure even at a relatively low pressure. Easy to be. Further, it is also possible to use pressure applied by a cooling roll or the like used for cooling the foamed laminated body provided at the rear in the foaming apparatus. This method is more advantageous in terms of energy consumption and cost than a method of forming a texture on the surface of the metal foil in advance.

The belt for transporting the laminate is not particularly limited as long as the heat resistance during heating and foaming can be maintained, but a steel belt, a fluorine processing belt, or the like is preferable. In particular, fluororesin, especially polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, for fiber layers such as long glass fibers, from the viewpoint of ease of surface texture processing, releasability, and strength A belt made of a sheet coated with (PFA) or the like is preferable. Other fluororesins include tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / ethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), A chlorotrifluoroethylene / ethylene copolymer (ECTFE) is exemplified, but since a resin having a foaming heating temperature exceeding the melting point of the resin cannot be used, the resin is selected in consideration of the foaming start temperature.

Next, a method for processing the composite foamed resin sheet according to the present invention will be described.

It is not necessary to use a special instrument when performing the bending process, but it is preferable from the viewpoint of easy folding that a crease is provided in advance at the folding part. The crease treatment includes a method of pressing using a wedge-shaped metal fitting and a method of performing groove processing such as V-shaped on a bent portion. Besides that, U-shaped pressing and groove processing It is possible to make the sheet easier to bend by a method in which the thickness of the bending position is locally thinner than other portions, such as a local linear press at the same position on the front and back sides. Of these, the method of performing a press treatment using a wedge-shaped metal fitting is most preferable. In this method, by heating the metal fitting, the resin foam layer is heated and melted, causing a decrease in compressive strength, so that press working can be performed without increasing the pressure. It becomes easy to do. This method is also preferable from the viewpoint that the composite foamed resin sheet is solidified by cooling after heating, the strength is restored, and the crease shape can be maintained.

In addition, as an application example of crease processing by press processing, it is possible to make a crease at a predetermined position at the same time as punching processing by performing press processing using a specific metal fitting simultaneously with punching processing such as Thomson processing.

The composite foamed resin sheet according to the present invention is a polyolefin resin foam having a specific cell structure in which the average aspect ratio Dz / Dxy of the internal bubbles is 1.1 to 5.0 and the expansion ratio is 4 to 20 times. Because it is a laminate of metal foil, the cell structure can ensure flexibility against bending action while maintaining a compressive strength of 0.05 MPa or more, and can be bent while maintaining a certain hardness. is there.

In addition, since at least one surface of the composite resin foam sheet has been subjected to graining, when the sheet is bent, the surface layer to which the grain shape is given against the tensile stress generated on the surface on the tension side is Can stretch compared to no flat surface condition. Therefore, it is possible to greatly obtain the dimensional followability of the metal foil with respect to the surface displacement at the time of sheet bending, and by this effect, it becomes possible to suppress cracks and breaks caused by the tensile stress on the metal foil within a certain curvature as much as possible, It becomes easier to bend the composite foam resin sheet than the one without the crimped shape. This effect is prominent when using a metal foil having a smaller elongation characteristic than a foam.

In addition, when the polyolefin resin foam contains a flame retardant in a predetermined ratio, the flameproofness is improved in combination with the effect of laminating the metal foil on the resin foam. Under certain conditions, the requirements for non-combustible materials specified in the Building Standards Act are required. It becomes possible to satisfy.

The method for producing a composite foamed resin sheet according to the present invention comprises a foamed laminate formed by laminating a metal foil on at least one side of a polyolefin resin foamable sheet, sandwiched between two endless belts, and heated to be foamable. A method for producing a composite foamed resin sheet that is cooled after foaming the sheet, wherein the endless belt on the metal foil side has a textured shape on the surface. In these cases, there is no need to apply a texture to the metal foil or the resin foam layer before and after the foaming step, so that a special texture processing device is unnecessary, which is economically advantageous.

In order to process the composite foamed resin sheet according to the present invention, a crease is made in advance by performing a press treatment using a wedge-shaped metal fitting on the folded portion of the composite resin foamed sheet. As a result, the bending process can be easily performed. Further, when the metal fitting is heated to a temperature higher than the temperature at which the resin foam layer melts, for example, 130 to 150 ° C. or higher for polypropylene resin, the metal foil on the surface of the sheet is cracked or broken by a relatively low-pressure press treatment. It is possible to make a crease without any.

The air-conditioning duct made of the composite foamed resin sheet according to the present invention is better than the galvanized steel duct in terms of heat insulation and light weight, and has a performance superior to that of the corrugated cardboard duct in terms of water resistance and workability. In addition, by blending a flame retardant with a resin, it can have the performance of a non-flammable material certified level stipulated in the Building Standard Law, which is a necessary requirement for air conditioning ducts. Therefore, the composite foamed resin sheet according to the present invention is a material suitable for an air conditioning duct.

It is a perspective view which shows a foam. It is an enlarged view of the A section in Fig.1 (a). It is the schematic which shows a shape maintenance evaluation test.

Next, in order to specifically explain the present invention, some examples of the present invention and comparative examples for showing comparison with the examples will be given.

Example 1 (no flame retardant formulation)
A foamable laminate is prepared by sandwiching a foamable sheet made of a polypropylene resin composition produced by the method described in Patent Document 6 from above and below with aluminum foil (thickness: 40 μm). It was carried into a heating furnace (set temperature 220 to 229 ° C.) of a continuous foaming apparatus using an endless belt for conveyance (texture shape: fluorine-based resin coating belt having an average unevenness height difference 0.2 mm on the surface). In that process, the conveying belt is pressurized by the weight of the roll using the heat transfer roll from the upper part of the conveying upper belt, and the embossed shape processed on the belt surface is applied to the surface of the laminate before and after the foaming laminate is foamed. Pressurized and transferred. In addition, a linear roll pressure of 1 kgf / m or higher was applied from the upper part of the upper belt using a cooling roll for cooling the foamed laminate provided in the foaming apparatus. In addition, the fluororesin processing belt for transport used at this time was made of a fluororesin on a fiber layer knitted perpendicularly on a sheet plane with strands (glass fiber bundles) having a diameter of about 1.2 mm using long glass fibers. Some PTFE and PFA coated were used. In this case, when the glass fiber bundle is knitted orthogonally, a textured shape (fine irregularities) is generated. In addition, in a state where the concave portion is not filled with the fluorine-based resin, the convex portion generated by knitting the fiber remains on the surface, and the wrinkle shape is maintained on the surface. Since the embossed shape is formed without applying to the belt surface, this can be used as it is. Thus, a composite foamed resin sheet (average aspect ratio Dz / Dxy: 1.6, foaming ratio: 7 times, compressive strength: 0.61 MPa, thickness: 5 mm) having wrinkles on the entire upper and lower surfaces was produced.

Example 2 (flame retardant formulation 1)
The same operation as in Example 1 except that the polypropylene resin composition of Example 1 is obtained by blending 6 parts by weight of ethylenebispentabromobenzene and 3 parts by weight of antimony trioxide with respect to 100 parts by weight of polypropylene. A composite foamed resin sheet (average aspect ratio Dz / Dxy: 1.7, foaming ratio: 7 times, compressive strength: 0.55 MPa, thickness: 5 mm) having wrinkles on the entire upper and lower surfaces was prepared.

Example 3 (flame retardant compounding 2)
The same operation as in Example 1 except that the polypropylene resin composition of Example 1 is obtained by blending 10 parts by weight of ethylenebispentabromobenzene and 5 parts by weight of antimony trioxide with respect to 100 parts by weight of polypropylene. Then, a composite foamed resin sheet (average aspect ratio Dz / Dxy: 1.5, foaming ratio: 7 times, compressive strength: 0.54 MPa, thickness: 5 mm) having wrinkles on both upper and lower surfaces was prepared.

Comparative Example 1 (no wrinkles)
The foam was produced using the same foaming sheet as in Example 1 except that flat belts having no embossed shapes were used for the upper and lower endless belts of the double belt type foaming apparatus, and the entire upper and lower surfaces were made. A composite foamed resin sheet having an embossed surface (average aspect ratio Dz / Dxy: 1.6, foaming ratio: 7 times, compressive strength: 0.75 MPa, thickness: 5 mm) was produced.

Comparative Example 2 (without wrinkles)
Composite foam resin sheet (aspect ratio) with no wrinkles by bonding aluminum foil (thickness 40μm) to the front and back of both sides of soft polyethylene foam (product name "Soft Ron" manufactured by Sekisui Chemical Co., Ltd.) Dz / Dxy average value: 1 or less, foaming ratio: 30 times, compression strength: less than 0.05 MPa, thickness: 5 mm).

Comparative Example 3 (no wrinkles)
Composite foamed resin sheet having an average ratio of aspect ratio Dz / Dxy with aluminum foil <thickness 40 μm> bonded to the front and back with an adhesive on both sides of a polystyrene foam having a foaming ratio of 12 times and a thickness of 6 mm. 1 or less, foaming ratio: 12 times, compressive strength: 0.97 MPa, thickness: 7 mm).

Comparative Example 4 (excessive flame retardant)
Except that the polypropylene resin composition is obtained by blending 40 parts by weight of ethylenebispentabromobenzene with respect to 100 parts by weight of polypropylene, the composite foam having the texture on both the upper and lower surfaces is the same as in Example 1. A resin sheet (average value of aspect ratio Dz / Dxy: measurement not possible due to coarse bubbles), foaming ratio: foamed layer coarsened and measurement not possible, compressive strength: 0.12 MPa, thickness: 5 mm was prepared.

Comparative Example 5 (corrugated cardboard)
An aluminum foil (thickness 40 μm) was laminated on a corrugated paper having a thickness of 5 mm with an adhesive.

Performance evaluation test
a) Compressive strength: Based on JIS K 7220, a higher value was measured by comparing the maximum stress value up to 10% thickness deformation and the yield point stress at a crosshead speed of 1 mm / min.

b) Thermal conductivity Measured according to JIS A 1412.

c) Folding evaluation: When a sample having a composite foamed resin sheet width of 20 mm and a length of 200 mm was bent at an angle of 60 °, no crack was generated.

d) Shape retention evaluation ・ As shown in FIG. 2, the base end of the sample (s) having a width of 20 mm and a length of 200 mm is fixed to a horizontal surface with double-sided tape, and the tip is started from the center in the longitudinal direction. The part was bent to a height of 40 mm, and the height after 30 minutes, 60 minutes and 1 day was measured. At that time, the sample (s) was bent along a special triangular jig in order to maintain the processing accuracy at the time of bending.

e) After foaming and cutting out a plate-like sample from the foamed portion with a cutter, the cell state of the cut surface was confirmed visually. When coarse cells or open cells were remarkable, it was marked as x.

f> Nonflammability: Nonflammability was evaluated according to the exothermic test method <corn calorie test> in the nonflammability evaluation prescribed in the Building Standards Law. Test items: total calorific value and maximum burning rate during 20-minute evaluation.

Table 1 summarizes the results of the performance evaluation test.

As is clear from Table 1, the composite foamed resin sheets of the examples showed good performance for all items.

Explanation of sign

(1) Foam (2) Arbitrary cross section (3) Cell

Claims

An average thickness of at least one surface of a polyolefin resin foam having an average aspect ratio Dz / Dxy of the internal bubbles of 1.1 to 5.0, an expansion ratio of 4 to 20 times, and a compressive strength of 0.05 MPa or more. A composite foamed resin sheet, wherein at least a part or the entire surface of the metal foam side of the composite foamed resin sheet in which metal foils having a thickness of 5 μm to 200 μm are laminated is formed.
The composite foam resin sheet according to claim 1, wherein the polyolefin resin foam contains 5 to 30 parts by weight of a flame retardant with respect to 100 parts by weight of the polyolefin resin.
Composite foamed resin sheet for cooling after foaming a foamable sheet by sandwiching the top and bottom of a foamable laminate formed by laminating metal foil on at least one side of a polyolefin resin foamable sheet and heating it between two endless belts 3. The method for producing a composite foamed resin sheet according to claim 1, wherein the endless belt on the metal foil side has a textured shape on the surface.
A method for producing a composite foam resin sheet processed product, wherein the composite foam resin sheet according to claim 1 or 2 is creased using a wedge-shaped metal fitting.
An air conditioning duct material comprising the composite foamed resin sheet according to claim 1 or 2.
An air-conditioning duct material manufactured by the manufacturing method according to claim 4 in a predetermined shape.