JP2004358928A - Modified polypropylene corrugated cardboard - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide plastic corrugated cardboard with a deep drawing shape and a complex shape formed exactly by molding a modified polypropylene sheet by vacuum forming. <P>SOLUTION: The corrugated cardboard 1 comprises a core material 2 and a coating material 3 applied on one side or both sides of the core material 2. At least the core material 2 is produced by vacuum-forming a sheet of the modified polypropylene prepared by compounding 5-30 mass% of polyethylene and/or an ethylene-propylene copolymer into polypropylene. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cardboard made of modified polypropylene.
[0002]
[Prior art]
Conventionally, paper corrugated cardboard has been used for various purposes such as packaging materials used for packaging, shock-absorbing materials for cushioning shocks, and sound-absorbing materials for absorbing noise. Corrugated cardboard is provided. In addition, a plastic cardboard made of a thermoplastic resin such as polypropylene or polyvinyl chloride is also provided (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-100021
[Problems to be solved by the invention]
Paper cardboard is lightweight, but it is difficult to process into a shape having a curved surface, and its use may be limited, which has been a problem.
On the other hand, the thermoplastic resin is generally excellent in moldability. However, when the cardboard is produced from a thermoplastic resin sheet by vacuum forming or the like, it has been difficult to accurately form a deep-drawn shape or a complex shape into the obtained molded product. In particular, it has been difficult to accurately form a deep-drawn shape or a complicated shape into a molded product by vacuum forming a thermoplastic resin sheet to which an inorganic filler has been added.
[0005]
[Means for Solving the Problems]
The present invention provides a corrugated cardboard comprising a core material (2) and a covering material (3) applied to one or both surfaces of the core material (2) as means for solving the above-mentioned problems, The core material (2) provides a modified polypropylene corrugated cardboard made of a modified polypropylene in which 5 to 30% by mass of polyethylene and / or ethylene-propylene copolymer is blended with polypropylene.
It is desirable that 20 to 50% by mass of an inorganic filler is added to the modified polypropylene.
Further, an unmodified polypropylene film may be formed on one side or both sides of the core made of the modified polypropylene.
The core material (2) of the modified polypropylene corrugated cardboard (1) according to the present invention has various structures such as a corrugated plate, a honeycomb structure, and a formed thin plate in which a large number of convex portions (4) are formed on a thin plate. Embodiments can be taken.
The covering material (2) of the modified polypropylene corrugated cardboard (1) is made of, for example, a porous material.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the contents of the present invention will be described in detail.
The modified polypropylene corrugated cardboard (1) of the present invention (hereinafter referred to as corrugated cardboard (1)) comprises a core material (2) and a covering material (2) applied to the core material (2) (FIG. 1). See FIG.
[0007]
The core material (2) of the corrugated cardboard (1) of the present invention comprises, for example, a cylindrical member (2A) in which a large number of cylindrical parts (6) are formed on a thin plate as shown in FIGS. The core material (2) of the corrugated cardboard (1) according to the present invention is not limited to the case where the core member (2A) is formed, and for example, when the corrugated board (2B) as shown in FIG. Various shapes such as a case of a honeycomb structure (2C) as shown in FIG.
In the present invention, the honeycomb structure (2C) includes a grid-like structure (2D) as shown in FIG.
[0008]
Moreover, although the said cylinder part member (2A) is obtained by excising the upper end part (5) of the convex part (4) of the precursor member (2E) shown by FIG. 8 and FIG. 9, this precursor member (2E) itself may be used as the core material (2) of the cardboard (1) of the present invention. The convex portion (4) in this case is not limited to the one having the upper end surface as shown in FIGS. 8 and 9 having a planar shape. For example, the convex portion (4A) having the V-shaped (5A) upper end portion (see FIG. ), U-shaped (5B) convex portion (4B) (see FIG. 11), and convex portion (4C) (see FIG. 12) having a circular opening (5C) on the upper end surface. A convex part (4) may be sufficient. Further, the protrusions (4) formed on the precursor member (2E) need not all have the same shape on the precursor member (2E). For example, as shown in FIG. 4) Precursor member (2E) in which (cylindrical portion (6)) is arranged around and the center is provided with a convex portion (4) having a planar shape at the upper end, and convex portions of various shapes as shown in FIG. The precursor member (2E) which arranged the part (4) may be sufficient. In the present invention, the cylindrical convex portion (4) is particularly referred to as a cylindrical portion (6).
[0009]
The shape of the core material (2) is determined by the intended use of the cardboard (1). For example, when the cardboard (1) of the present invention is used as a sound absorbing material for the purpose of sound absorption and sound insulation, an excellent shape such as sound absorption efficiency is selected.
[0010]
The material used for the core material (2) of the corrugated cardboard (1) of the present invention is made of polypropylene (hereinafter abbreviated as PP) by polyethylene (hereinafter abbreviated as PE) and / or ethylene-propylene copolymer (hereinafter abbreviated as EPR). It is a modified polypropylene (hereinafter abbreviated as modified PP). The PE is a high density PE with a density of 0.941 or more, a medium density PE with a density of 0.926 to 0.940, a low density PE with a density of 0.910 to 0.925, and a density of 0.909 or less. Although any of ultra-low density PE can be used, it is preferable to use a low-density PE having good miscibility with PP and a large effect of improving elongation.
The above EPR includes ethylene-propylene rubber-like copolymer (hereinafter abbreviated as EPM), ethylene, propylene, and ethylene-propylene copolymerized with diene components such as dicyclopentadiene, ethylidene norbornene, and 1,4-hexadiene. Any diene terpolymer (hereinafter abbreviated as EPDM) is used.
Said PE and / or EPR are mix | blended in PP in the range of 5-30 mass%. When the blending amount of PE and / or EPR is less than 5% by mass, the elongation of PP is not sufficiently improved, and good moldability cannot be obtained. On the other hand, if the blending amount of PE and / or EPR exceeds 30% by mass, the hardness of the resulting modified PP is insufficient, and the shape and dimensional stability and heat resistance deteriorate.
[0011]
The modified PP further includes calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, calcium sulfite, calcium phosphate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, magnesium oxide, titanium oxide, iron oxide, zinc oxide, alumina, Silica, diatomaceous earth, dolomite, gypsum, talc, clay, asbestos, mica, calcium silicate, bentonite, white carbon, carbon black, iron powder, aluminum powder, glass powder, stone powder, blast furnace slag, fly ash, cement, zirconia powder, etc. One kind or two or more kinds of inorganic fillers may be added. The said inorganic filler is normally added in 20-50 mass% with respect to the said modified PP. When the added amount of the inorganic filler is less than 20% by mass, the mechanical strength and heat resistance effect by the inorganic filler are not sufficiently exhibited, and when it exceeds 50% by mass, the moldability and chemical resistance are inferior. It becomes like this.
[0012]
Further, the modified PP further includes organic fillers such as linter, linen, sisal, wood flour, palm flour, walnut flour, den flour, wheat flour, cotton, hemp, bamboo fiber, palm fiber, wool, asbestos, kenaf fiber, etc. Synthetic fibers such as natural fiber, polyamide fiber, polyester fiber, polyolefin fiber, acrylic fiber, vinyl chloride fiber, vinylidene chloride fiber, semi-synthetic fiber such as viscose fiber, acetate fiber, asbestos fiber, glass fiber, carbon fiber, ceramic fiber In addition, one or more fillers such as metal fibers and inorganic fibers such as whiskers may be added to improve shape retention, dimensional stability, compression and tensile strength, and the like. The filler is usually added in an amount of about 0.05 to 200% by mass with respect to the modified PP.
[0013]
If necessary, the modified PP may be mixed with one or more thermoplastic plastics such as vinyl chloride resin, acrylic resin, methacrylate resin, vinylidene chloride resin, vinyl propionate resin, and polyester resin. May be.
[0014]
The modified PP may be colored with a pigment or a dye, and may be color-coded. Further, a plasticizer such as DOP and DBP, an antioxidant, an antistatic agent, a crystallization accelerator, a flame retardant, a flame retardant, an insect repellent, Antiseptics, waxes, lubricants, stabilizers, anti-aging agents, ultraviolet absorbers, chemical foaming agents or foaming agents such as capsule type foaming agents may be added. These components may be added singly or in combination of two or more.
[0015]
On one side or both sides of the modified PP, polyolefin such as PE, unmodified PP, EPR, ethylene-vinyl acetate copolymer, vinyl chloride resin, acrylic resin, methacrylate resin, vinylidene chloride resin, styrene resin A film of a thermoplastic plastic such as a vinyl propionate resin, a styrene-butadiene copolymer, or a polyester resin or a film of a foam of the thermoplastic plastic may be formed. Unmodified PP is a desirable film from the viewpoint of interlayer adhesion and heat resistance. In the case of the above-mentioned coating, when an inorganic filler is added to and mixed with the modified PP, the smoothness of the surface of the core material (2) is ensured and the chemical resistance is improved.
[0016]
The cardboard (1) of the present invention may be used as a laminate in which the cardboards (1) are laminated. The cardboard (1) may be used after being painted. The corrugated cardboard (1) is mutually bonded and painted by a known bonding method or coating method. A part or all of the surface of the corrugated cardboard (1) is subjected to treatment such as corona discharge treatment or primer treatment. The affinity for adhesives and paints may be further increased. Examples of the primer used for the primer treatment include chlorinated polypropylene, modified polyolefin or olefin copolymer such as ethylene-vinyl acetate copolymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, and polybutadiene. Synthetic rubber, acrylic synthetic resin, vinyl synthetic resin, acrylic synthetic resin containing amino group, amide group, etc., vinyl synthetic resin, synthetic rubber such as amino synthetic resin or epoxy resin, or synthetic resin primer, Alternatively, an aluminum alcoholate or aluminum chelate compound such as aluminum isopropylate or aluminum trisacetylacetonate, an alkyl metal such as 2-ethylhexyllead or hexadecyllithium, or dibutyltin diacetate. , Organic tin compounds such as di-n-butyltin dioxide, silane compounds such as methylvinyldichlorosilane, metal complex salts of 1,3-dicarbonyl such as acetylacetone lithium and acetylacetone beryllium, and organic titanium compounds such as tetrabutyl titanate Boric acid compounds such as tri-n-butyl borate and triphenyl borate, phosphate esters such as trioleyl phosphate and tridecyl phosphate, metal carboxylates such as magnesium stearate and cobalt naphthenate, n-dodecyl Metal thioalcolate such as mercapto potassium salt, dithiocarboxylate such as zinc 2-ethylhexanedithiocarboxylate, dithiocarbamate metal salt such as nickel dimethyldithiocarbamate and copper dimethyldithiocarbamate, sulfone such as nickel benzenesulfonate Metal salts, there are primers low molecular weight such as organic phosphoric acid metal salts such as dibutyl phosphate vanadium, the primer is used as one or a mixture of two or more. Particularly desirable as the primer is an acrylic synthetic resin or amino synthetic resin containing a quaternary ammonium salt.
[0017]
In order to perform primer treatment using one kind or a mixture of two or more kinds of the above various primers, a solution or emulsion (latex) of one kind or a mixture of two or more kinds of the above various primers is applied to the surface of the corrugated cardboard (1). Apply and dry.
Prior to the primer treatment, the surface of the cardboard (1) main body may be subjected to an affinity treatment. Examples of the affinity treatment include flame treatment or sulfuric acid treatment that slightly carbonizes the surface of the corrugated cardboard (1) to give affinity, corona discharge treatment that roughens and slightly carbonizes the surface.
[0018]
The core material (2) of the cardboard (1) of the present invention may be produced from the above-mentioned modified PP foam.
[0019]
The core material (2) of the cardboard (1) of the present invention may be coated with a porous layer (7) as shown in FIG. 2, for example. Examples of the porous material used as the material for the porous layer (7) include polyester fiber, polyethylene fiber, polyamide fiber, acrylic fiber, urethane fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, and acetate fiber. Synthetic fibers, pulp, cotton, palm fibers, hemp fibers, bamboo fibers, kenaf fibers and other natural fibers, glass fibers, carbon fibers, ceramic fibers, asbestos fibers and other inorganic fibers, or scraps of textile products using these fibers Fiber aggregates such as knitted fabrics, nonwoven fabrics, felts, and laminates thereof made of one or two or more kinds of recycled fibers obtained by defibration of polyurethane, polyurethane foam having open cells (soft polyurethane foam) Body, including rigid polyurethane foam), polyolefin foams such as polyethylene and polypropylene, polychlorinated Open cell structure such as vinyl foam, polystyrene foam, amino resin foam such as melamine resin, urea resin, epoxy resin foam, phenolic resin foam made of phenolic compound such as monohydric phenol, polyhydric phenol, etc. Known foams such as plastics and sintered plastic beads may be mentioned.
[0020]
The porous layer (7) may be impregnated with a synthetic resin. As the synthetic resin, an initial condensate of a thermosetting resin such as a melamine resin, a urea resin, or a phenol resin, an emulsion or an aqueous solution of a thermoplastic resin, or the like is used.
[0021]
The covering material (3) used for the corrugated cardboard (1) of the present invention is applied to one or both sides of the core material (2). The covering material (3) includes the porous material described above. The fiber aggregate, the thermoplastic resin sheet or film exemplified as the porous material of the layer (7), the foam sheet or film of the thermoplastic resin, and the metal foil such as aluminum foil are used.
[0022]
When the covering material (3) is a fiber assembly, the covering material (3) may be impregnated with a synthetic resin. The synthetic resin is the same as the synthetic resin impregnated in the porous layer (7).
[0023]
A method for producing the cardboard (1) of the present invention will be described below. First, a method for manufacturing the core material (2) of the cardboard (1) will be described.
The core material (2) of the cardboard (1) of the present invention is formed into a predetermined shape. For example, the core material (2B) of the cardboard (1A) shown in FIG. 14 is shown in FIG. A core material (2B) made of a corrugated plate.
The corrugated plate is manufactured by a known molding method such as injection molding.
[0024]
For example, as shown in FIG. 15, the core material (2D) shown in FIG. 7 is a strip-shaped substrate (8A) with a notch (8A) cut from the upper side of a strip-shaped substrate (8) made of engineering plastics or the like. This is manufactured by assembling a substrate (9) having a notch (9A) from the lower side thereof by engaging the notches with each other.
[0025]
A method for manufacturing the core material (2) of the cardboard (1) shown in FIGS. As shown in FIGS. 8 and 9, the core material (2) is manufactured by first vacuum-forming a modified PP sheet to produce a precursor member (2E) in which a large number of convex portions (4) are arranged in a horizontal and vertical direction. Further, when the upper end portion of the convex portion (4) of the precursor member (2E) is cut away, a core in which a large number of cylindrical convex portions (cylindrical portion (6)) shown in FIGS. The cylinder part member (2A) which is a material can be manufactured.
In addition, generally the thickness of the sheet | seat of modified | denatured PP is about 300-600 micrometers, and when a film is formed in the sheet | seat surface, the thickness of this film is about 10-100 micrometers.
In this type of corrugated cardboard (1) core material (2) manufacturing method, vacuum forming can form deep drawing shapes and complex shapes accurately and is most suitable for mass production. , And can be produced by a known method such as vacuum / pressure forming, press molding, blow molding, injection molding or the like.
[0026]
The covering material (3) covering the core material (2) is bonded to the core material (2) by a known technique in consideration of the material, shape, etc. of each core material (2).
[0027]
Hereinafter, the present invention will be described by way of examples. However, this invention is not limited only to the Example shown below.
[Example 1]
The cardboard (1A) shown in FIG. 14 is used as a heat insulating material. The core material (2) and the covering material (3) made of corrugated board of the corrugated cardboard (1A) are blended with 25 mass% calcium carbonate mixed with PP modified with 20 mass% low density PE and 5 mass% polystyrene. It consists of things.
[0028]
[Example 2]
(Sound absorption test)
As shown in FIGS. 1 to 4, a cylinder obtained by vacuum forming a sheet (thickness: 340 μm) of a blend in which 30% by mass of talc is mixed with a modified PP in which 18% by mass of low-density PE is blended with PP. Modified polypropylene corrugated cardboard consisting of a part member (2A), a covering material (3) comprising a polyester fiber nonwoven fabric (40 g / m ² basis weight) and a porous layer (7) comprising a polyester fiber (thickness 10 mm, basis weight 60 g / m ² ) 1) was used as a sound absorbing material, and the sound absorbing efficiency of the sound absorbing material was measured.
The height h of the sound absorbing material is 15 mm, and the upper end surface L × L of the cylinder portion is 10 mm × 10 mm.
Waveforms having frequencies of 800 Hz, 1500 Hz, and 2000 Hz were irradiated from the upper surface of the sound absorbing material, and the sound absorption efficiency was measured on the lower surface of the sound absorbing material.
The sound absorption efficiency (%) at each frequency was 85% (800 Hz), 98% (1500 Hz), and 95% (2000 Hz), respectively, and it was confirmed that the sound absorption efficiency of the sound absorbing material was good.
(Heat resistance test)
The operation of leaving the sound absorbing material (1) at 150 ° C. for 30 minutes and then leaving at room temperature (20 ° C.) for 30 minutes was repeated 10 times, and the state of the sound absorbing material thereafter was observed. As a result of observation, no abnormalities in appearance such as deformation and warping were found in the sound absorbing material.
The sound absorbing material was examined for sound absorption efficiency under the same conditions as in the sound absorption test, but no change was found in the sound absorption efficiency.
[0029]
[Comparative Example 1]
A cylindrical member was obtained by vacuum forming in the same manner as in Example 2 except that a sheet (thickness: 340 μm) in which 30% by mass of talc was mixed with PP was used. The cylindrical member was warped and deformed, and a normal-shaped cylindrical member could not be obtained. Moreover, when the said heat test was done using this cylinder part member, heat resistance was bad and the shape of this cylinder part member was deform | transforming.
[0030]
Example 3
Instead of the core material (2A) of the sound-absorbing material of Example 2, the core material (2F) shown in FIG. 16 was used to manufacture a sound-absorbing material (see FIG. 17) made of cardboard (1B). The core material (2F) is obtained by covering the top and bottom of the cylindrical member (2A) with a porous layer (7).
The cylindrical member (2A) of the core material (2F) is a sheet of a blend (thickness 320 μm) obtained by blending 35% by mass of calcium carbonate and 3% by mass of carbon black with modified PP in which 15% by mass of EPDM is blended with PP. ) Was formed by vacuum-pressure forming a multilayer sheet having an unmodified PP film (thickness 30 μm) formed on both sides. The porous layer is made of polyurethane foam. In addition, the polyester fiber nonwoven fabric similar to the said Example 2 was used for the coating | covering material (3) which coat | covers this core material (2).
The sound absorbing material of this example also had good sound absorbing efficiency and heat resistance, like the sound absorbing material of Example 2 above.
[0031]
Example 4
As another sound absorbing material, a sound absorbing material made of corrugated cardboard (1C) shown in FIG. 18 was manufactured.
The core material (2G) of the sound absorbing material is a member (2E) having a convex portion (4) having a flat upper end surface as shown in FIGS. 8 and 9, and the member (2E). A core material (2G) coated with a porous layer (7) was used.
The core material (2G) is a blended sheet in which 20% by mass of low-density PE blended with PP is mixed with 20% by mass of talc, 5% by mass of calcium carbonate, and some antistatic agent and antioxidant. It was produced by vacuum forming a multilayer sheet having an unmodified PP film (thickness 30 μm) formed on both sides (thickness 350 μm).
A polyester fiber nonwoven fabric was used as the covering material (3) for covering the core material (2G).
The sound absorption efficiency and heat resistance of the sound absorbing material of this example were good as in Example 2 and Example 3.
[0032]
Example 5
A honeycomb structure shown in FIG. 6 was used as a core material (2C), and the core material (2C) was coated with a coating material (3) to produce a cardboard (1D) (see FIG. 19). The core material (2C) is made of a blend in which 27% by mass of talc is mixed with a modified PP in which 30% by mass of low-density PE is blended with PP, and a covering material (2C) for covering the core material (2C) 3) consists of a polyester fiber nonwoven fabric.
The corrugated cardboard (1D) of this example was used as a cushioning material for mitigating the impact during transportation of the article.
[0033]
Example 6
The core material (2D) shown in FIG. 7 is composed of a blend in which 20% by mass of talc and 10% by mass of carbon black are mixed with modified PP in which 10% by mass of medium density PE and 12% by mass of EPM are blended with PP. As shown, a cardboard (1E) in which the core material (2D) was coated with a carbon fiber nonwoven fabric (3) was produced.
The cardboard (1E) is excellent in heat resistance for both the core material and the covering material. For example, an insulator hood stuck inside an engine hood of a car, a dash outer silencer set between a car engine room and a guest room. It is useful as a sound-absorbing material or cushioning material for parts exposed to high temperatures such as dash silencers.
[0034]
Example 7
A cylindrical member used in the sound-absorbing material shown in Example 2 above is a sheet (thickness 350 μm) of a blend in which 27% by mass of talc is mixed with modified PP in which 30% by mass of low-density PE is blended with PP. A multilayer sheet having an unmodified PP coating (thickness 50 μm) formed on both sides was produced by vacuum-pressure forming.
[0035]
Example 8
The cylinder part member used for the sound-absorbing material shown in the above Example 2 is a mixture of PP mixed with 10% by mass of medium density PE and 12% by mass of EPM, and 20% by mass of talc and 10% by mass of carbon black. A multilayer sheet in which an unmodified PP film (thickness 20 μm) was formed on the front side of the sheet (thickness 350 μm) was manufactured by vacuum forming.
[0036]
Example 9
Both sides of a modified PP sheet (thickness 320 μm) in which the cylindrical member used in the sound absorbing material shown in Example 2 above is blended with PP 15% by mass of low density PE and 5% by mass of polystyrene / ethyl acrylate copolymer. A multilayer sheet having an unmodified PP film (thickness 30 μm) formed thereon was manufactured by vacuum forming.
[0037]
Example 10
The cylindrical member used for the sound-absorbing material shown in Example 2 above is obtained by applying an EPM film (thickness) on both sides of a modified PP sheet (thickness 340 μm) in which PP is blended with 20% by mass of low density PE and 10% by mass of high density PE 27 μm) was produced by vacuum forming a multilayer sheet.
[0038]
【The invention's effect】
According to the present invention, a corrugated cardboard having a core material having a deep drawing shape or a complicated shape can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view of a sound absorbing material made of modified polypropylene corrugated cardboard. FIG. 2 is a cross-sectional view taken along line AA of the sound absorbing material shown in FIG. 1. FIG. 3 is a perspective view of a cylindrical member. FIG. 5 is a perspective view of a core material made of a corrugated plate. FIG. 6 is a perspective view of a core material made of a honeycomb structure. FIG. 7 is a core made of a grid-like honeycomb structure. FIG. 8 is a perspective view of the precursor member. FIG. 9 is a cross-sectional view of the precursor member shown in FIG. 8C. FIG. 10 is a partial sectional view of another precursor member. FIG. 12 is a perspective view of another precursor member. FIG. 13 is a perspective view of another precursor member. FIG. 14 is a partial sectional view of a cardboard having a core made of corrugated plates. FIG. 16 is a partial cross-sectional view of a core material whose upper and lower sides are covered with a porous layer. FIG. 17 shows the core material shown in FIG. FIG. 18 is a partial cross-sectional view of a cardboard (sound-absorbing material) having a core material having a convex portion with a flat top surface. FIG. 19 has a core material of a honeycomb structure. FIG. 20 is a partially cutaway perspective view of a cardboard having a core shown in FIG. 7. FIG.
1, 1A, 1B, 1C, 1D Modified polypropylene corrugated cardboard 2 Core material 2A Tube member (core material)
2B Corrugated plate-like core material 2C Honeycomb structure-like core material 2D Grid-like core material 2E Precursor member (core material)
3 Cover material 4 Convex part 5 Upper end part 6 Cylindrical part 7 Porous layer 8, 9 Substrate 8A, 9A Cut

Claims (7)

A corrugated cardboard comprising a core material and a coating material applied to one or both sides of the core material, and at least the core material contains 5 to 30% by mass of polyethylene and / or ethylene-propylene copolymer in polypropylene. Modified polypropylene corrugated cardboard characterized by using modified polypropylene as a material The modified polypropylene corrugated cardboard according to claim 1, wherein 20-50% by mass of an inorganic filler is added to the modified polypropylene. The modified polypropylene corrugated cardboard according to claim 2, wherein an unmodified polypropylene film is formed on one side or both sides of a core made of the modified polypropylene. The modified polypropylene corrugated cardboard according to claim 1, wherein the core material is a corrugated plate. 5. The modified polypropylene corrugated cardboard according to claim 1, wherein the core material has a honeycomb structure. The modified polypropylene corrugated cardboard according to any one of claims 1 to 5, wherein the core material comprises a molded thin plate in which a plurality of convex portions are formed on a thin plate. The modified polypropylene corrugated cardboard according to claim 1, wherein the covering material is made of a porous material.

Images