JP7191431B1 - laminated structure - Google Patents

Abstract

An object of the present invention is to provide a laminated structure that is excellent in mechanical properties such as strength, is easy to be molded, and exhibits a good appearance. A laminated structure in which surface sheets made of a thermoplastic resin are attached to both surfaces of a hollow plate-like body core in which hollow plate-like bodies are arranged in a thickness direction, wherein the hollow plate-like body core has: It contains a polypropylene-based resin and/or a polyethylene-based resin and an inorganic substance powder, and the mass ratio of the polypropylene-based resin and/or the polyethylene-based resin to the inorganic substance powder is 10:90 to 50:50. and the surface sheet is made of a polypropylene-based resin and/or a polyethylene-based resin. [Selection drawing] Fig. 1

Description

The present invention relates to laminated structures.

Conventionally, laminated structures with cores of hollow plate-shaped bodies having shapes such as honeycombs, hollow columnar shapes, corrugated corrugated waves, and harmonica shapes have been used in consumer goods, industrial goods, and articles for transportation such as automobiles and aircraft. is used as

Hollow plate-like bodies typified by honeycomb cores have extremely high strength per mass. In particular, a resin-based hollow plate-like body can be formed from a lightweight and high-strength material, and is useful as an aircraft part or the like. The hollow plate-shaped body can also be used as a shock absorber because it absorbs energy by buckling the hollow cells even when it is damaged by a strong external force. A laminated structure in which sheets are bonded to both sides of a hollow plate core has a large number of air-filled cells, and therefore has low thermal conductivity and is useful as a heat insulating material. Such a laminated structure also has a sound absorbing effect by making small holes on the surface of the sheet-like material. Therefore, hollow plate-shaped bodies and laminated structures based on them are widely used as consumer products such as containers, shelves, pallets, panels, and bags, as well as industrial products such as heat insulating materials, sound absorbing materials, filters, and shock absorbing materials. (For example, Patent Documents 1 to 6).

JP 2010-247448 A JP 2013-233796 A JP 2018-108740 A JP 2017-65810 A JP-A-6-320652 Japanese Patent Application Laid-Open No. 2021-53899

However, laminated structures based on hollow plate-like bodies, especially laminated structures based on general-purpose resins such as those described in Patent Documents 1 to 4, may have insufficient mechanical strength due to the hollow core structure. There is Such problems can be avoided by using a resin having high mechanical strength for the hollow plate-like body as described in Patent Documents 5 and 6, but such resins have low versatility and are disadvantageous in terms of cost. In addition, non-general-purpose resins often have low moldability, which may adversely affect the appearance of the obtained hollow plate-like body and its laminated structure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminate structure which is excellent in mechanical properties such as strength, is easy to be molded, and has a good appearance.

The inventor of the present invention has provided surface sheets made of a polypropylene resin and/or a polyethylene resin composition on both sides of a hollow plate-shaped core made of a polypropylene resin and/or a polyethylene resin composition highly filled with an inorganic substance powder. The inventors have completed the present invention based on the knowledge that a bonded laminated structure has excellent mechanical properties and moldability and exhibits a good appearance. More specifically, the present invention provides:

(1) A laminated structure in which surface sheets made of a thermoplastic resin are attached to both surfaces of a hollow plate-like body core in which hollow plate-like bodies are arranged in the thickness direction,
The hollow plate core contains a polypropylene-based resin and/or a polyethylene-based resin and an inorganic substance powder, and the mass ratio of the polypropylene-based resin and/or the polyethylene-based resin to the inorganic substance powder is 10. : 90 to 50:50, and the surface sheet is made of a polypropylene-based resin and/or a polyethylene-based resin.

(2) The hollow plate-shaped core contains lauric acid diethanolamide, and the content of the lauric acid diethanolamide is 0.1% by mass or more and 1.0% by mass with respect to the total mass of the hollow plate-shaped core. % or less, the laminated structure of (1).

(3) The polyethylene resin is a high-density polyethylene having an MFR (190° C., 2.16 kg) according to JIS K 6922-1 (ISO 1133) of 5 g/10 minutes or more and 15 g/10 minutes or less, and JIS K 6922-1. (ISO1133) MFR (190 ° C., 2.16 kg) is 0.5 g / 10 minutes or more and 1.5 g / 10 minutes or less, and the high density polyethylene and the linear low density polyethylene The laminated structure of (1) or (2), wherein the mass ratio to density polyethylene is from 90:10 to 50:50.

(4) The laminated structure according to any one of (1) to (3), wherein the polypropylene-based resin of the hollow plate core is a polypropylene homopolymer and/or a propylene block polymer.

(5) The laminated structure according to any one of (1) to (4), wherein the hollow plate core contains both the polypropylene-based resin and the polyethylene-based resin.

(6) The laminate structure according to any one of (1) to (5), wherein the surface sheet is a polypropylene resin sheet.

(7) The laminated structure according to any one of (1) to (6), wherein the inorganic substance powder is ground calcium carbonate.

(8) The laminated structure according to (7), wherein the heavy calcium carbonate has an average particle size of 0.7 μm or more and 6.0 μm or less.

(9) The laminate structure according to any one of (1) to (8), wherein the hollow plate core and the surface sheet are bonded together via an adhesive layer.

(10) The laminated structure according to any one of (1) to (9), wherein the hollow plate core is selected from the group consisting of a honeycomb core, a hollow columnar core, a corrugated corrugated core, and a harmonica core. .

(11) A panel composed of the laminated structure according to any one of (1) to (10).

ADVANTAGE OF THE INVENTION According to this invention, the laminated structure which is excellent in mechanical properties, such as intensity|strength, is easy to mold, and exhibits a favorable appearance, and the panel comprised by it are provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows some of embodiment of the laminated structure of this invention.

Embodiments of the present invention will be described below, but the present invention is not limited thereto.

≪Laminated structure≫
The laminate structure of the present invention is a laminate structure in which surface sheets made of a thermoplastic resin are attached to both surfaces of a hollow plate-like body core in which hollow plate-like bodies are arranged in the thickness direction; The core contains polypropylene-based resin and/or polyethylene-based resin and inorganic substance powder in a specific mass ratio; and the surface sheet consists of polypropylene-based resin and/or polyethylene-based resin.

FIG. 1 is a schematic cross-sectional view showing some embodiments of the laminated structure of the present invention. In the laminated structure 1 of the present invention, "the hollow plate-shaped bodies are arranged in the thickness direction" means that the side surfaces of the hollow hexagonal column (honeycomb), hollow cylinder, etc. that constitute the hollow plate-shaped core 2 are aligned in the laminated structure 1 It means an arrangement in which both end open surfaces of hollow hexagonal columns, hollow cylinders, etc. are directed in a direction perpendicular to the side surfaces, that is, toward both main surfaces of the laminated structure. Therefore, in the laminated structure 1 of the present invention, each opening in the hollow plate core 2 is in contact with the surface sheets 3 and 4 at both ends.

In the laminated structure 1 shown in FIG. 1, the hollow plate core 2 is a hexagonal prism-based honeycomb core in FIG. 1a, a hollow cylindrical core in FIG. 1b, a corrugated corrugated core in FIG. 1c, and a square prism in FIG. It has a harmonica-like core of the bass. If the hollow plates are arranged in the thickness direction as shown in FIGS. 1a to 1d, the strength per mass is extremely high, and the laminated structure is suitable for aircraft parts and the like. The properties as a shock absorbing material and a heat insulating material are easily exhibited, and the sound absorbing effect is enhanced when small holes are made in the surface of the surface sheets 3 and/or 4 .

There are no particular restrictions on the shape and size of the laminated structure 1, and it can be any desired shape and size according to the purpose and application. For example, it may have a flat plate shape extending in length and width of several meters, or may have a flat plate shape with a width of several millimeters. Depending on the purpose, a non-flat shape having unevenness or curvature is also possible. The thickness of the laminated structure 1 is also not particularly limited, and can be set, for example, from several millimeters to several tens of centimeters. It is also possible to join or stack a plurality of laminated structures 1 .

When a laminated structure 1 with a large thickness is required, from the viewpoint of strength and ease of manufacture, a plurality of so-called preforms having a thickness of, for example, about 2 to 50 mm, particularly about 5 to 25 mm are manufactured, It is preferable to laminate them to the target thickness. In this case, it is also possible to laminate the laminated structures 1 in which the surface sheets 3 and 4 are laminated on both sides of each hollow plate-shaped core 2, so that the laminated portion has only one surface sheet, for example, the first sheet. A structure such as surface sheet 3 - first hollow plate core 2 - second surface sheet 3 - second hollow plate core 2 - second surface sheet 4 is also possible. Moreover, the structure of the hollow plate-shaped core 2 is different, such as laminating the laminated structure material of the honeycomb core as shown in FIG. 1a and the laminated structure material of the corrugated corrugated core as shown in FIG. 1c. Preforms may be laminated.

There is no particular limitation on the pitch (repeating interval) of the hexagonal columns, the cylinders, etc. that constitute the hollow plate core 2 . For example, it may be a honeycomb structure in which regular hexagonal columns with a side of about 0.2 to 10 mm (diagonal distance of 0.4 to 20 mm), particularly about 1 to 6 mm (diagonal distance of 2 to 12 mm) are in continuous contact, It may have a hollow cylindrical structure in which cylinders with a diameter of about 0.4 to 20 mm, particularly about 2 to 12 mm, are in contact with each other. The thickness (thickness of the non-void portion) of these hexagonal columns and cylinders can be, for example, about 50 to 2000 μm, particularly about 100 to 1000 μm.

The thickness of the topsheets 3 and 4 is also not particularly limited. For example, each can have a thickness of about 5 to 1000 μm, further 20 to 800 μm, particularly about 100 to 500 μm. Also, the top sheets 3 and 4 may have the same thickness or different thicknesses. If desired, these surface sheets may be attached to the hollow plate core 2 via an adhesive layer, but the thickness of the adhesive layer in that case is not particularly limited either. It is also possible to form a multi-layered structure by coating the surface of the topsheets 3 and/or 4 or attaching another sheet or film.

<Hollow plate core>
The hollow plate-shaped core in the laminated structure of the present invention has a structure in which the hollow plate-shaped bodies are arranged in the thickness direction as described above. Contained at a mass ratio of 10:90 to 50:50. As a result of intensive studies, the inventors of the present invention have found that, firstly, by making the hollow plate-shaped body core have such a structure and composition, it has excellent mechanical properties such as strength, despite being based on a low-cost general-purpose resin. It has been found that a laminated structure which is easy to mold and has a good appearance can be obtained. Raw materials for forming the hollow plate core will be described below.

[Polypropylene resin]
The polypropylene-based resin in the present invention is not particularly limited as long as it contains at least a portion of repeating units of propylene. For example, the polypropylene-based resin in the present invention includes resins having a propylene component unit of 50% by mass or more, particularly 60% by mass or more. Examples include propylene homopolymers (propylene homopolymers), copolymers of propylene with other copolymerizable monomers (propylene copolymers), and the like. These polypropylene-based resins can be used alone or in combination of two or more.

There is no particular restriction on the molecular weight of the polypropylene resin. For example, a resin having a mass average molecular weight of about 50,000 to 500,000, particularly about 100,000 to 400,000 can be used, but the present invention is not limited to these. In general, the higher the molecular weight, the better the mechanical properties such as strength, and the lower the molecular weight, the better the moldability. A compound having a mass average molecular weight of approximately 50,000 or more and less than 200,000 and a compound having a mass average molecular weight of approximately 200,000 or more and 500,000 or less can be used together. By using polypropylene resins with different molecular weights together, it is possible to improve the moldability and reduce the appearance defects of the molded product.

Polypropylene-based resins may also have any melting properties such as melt mass flow rate (MFR). For example, one having an MFR (230° C.) of about 0.3 to 3.0 g/10 minutes can be used. Also, MFR (230 ° C.) is 1.0 to 3.0 g / 10 minutes, melt tension (230 ° C.) is 5 to 30 g, and MFR (230 ° C.) is 0.3 to 1.0 g / 10 minutes can also be used together. Moldability can be improved by using polypropylene resins having different melting properties together.

Copolymers of propylene and other monomers may be random copolymers or block copolymers, and may be not only binary copolymers but also terpolymers. Copolymerization components (other monomers) include, but are not limited to, tetrafluoroethylene, vinyl acetate, and the like.

In the present invention, propylene homopolymers or resins copolymerized with small amounts of other monomers, eg less than 5% by weight, and/or propylene block polymers are preferably used. Even in propylene homopolymers, as a result of polymerization, there are cases where a structure that seems to be copolymerized with an α-olefin such as hexene is partly included. It is broadly included as a propylene homopolymer.

(propylene homopolymer)
Propylene homopolymer (hereinafter sometimes abbreviated as "PP") is a polymer obtained by polymerizing substantially only propylene, and is excellent in rigidity and heat resistance. Various products are commercially available, such as Wintec (registered trademark) and Novatec (registered trademark) of Japan Polypropylene Corporation, Noblen (registered trademark) of Sumitomo Chemical Co., Ltd., and Prime Polypro (registered trademark) of Prime Polymer Co., Ltd. ), TORAYCA (registered trademark) of Toray Industries, Inc., SABIC (registered trademark) PP of SABIC Petrochemicals, and SunAllomer (registered trademark) of SunAllomer Co., Ltd., but the present invention is not limited to these, and any Such PP may be included. A plurality of types of PP can also be used together.

Propylene homopolymers are classified into isotactic PP, syndiotactic PP, atactic PP, hemiisotactic PP, etc., depending on the difference in stereoregularity. The laminated sheet of the present invention may contain any of these, and may have a branched structure, for example, a long-chain branched structure. In addition, the isotactic triad fraction (mm) may be a structure with high stereoregularity, for example, 90% or more, a random structure, or a structure containing trace components that are by-produced during polymerization. can be It is also possible to use a plurality of these propylene homopolymers in combination.

(Propylene block copolymer/Propylene block polymer)
A propylene block copolymer is a copolymer composed of consecutive blocks of propylene monomer and consecutive blocks of other monomer components. Here, the monomer component to be copolymerized with propylene is not particularly limited, and the block copolymer is not limited to a binary system, and may be a ternary system, a quaternary system, or the like. There are no particular restrictions on the copolymerization ratio of each monomer, the length of each block, the overall molecular weight, and the like. In the present invention, block copolymers composed of propylene and other α-olefins are preferred. A block copolymer of propylene and α-olefin can constitute a laminated structure having excellent mechanical properties and moldability.

Block copolymers of propylene and α-olefins are known, and various varieties are commercially available. Examples include Novatec (registered trademark) of Japan Polypropylene Corporation, Prime Polypro (registered trademark) of Prime Polymer Co., Ltd., Umex (registered trademark) of Sanyo Chemical Industries, Ltd., SunAllomer (registered trademark) of SunAllomer Co., Ltd., and the like. However, the present invention is not limited to these, and any propylene block copolymer may be included. It is also possible to use two or more block copolymers in combination. Monomers for copolymerization with propylene are also not particularly limited, and may be, for example, one or more monomer components selected from ethylene and α-olefins having 4 to 10 carbon atoms. Examples include ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, 1 - including but not limited to octene;

Among these block copolymers, copolymers with ethylene, 1-butene, isobutylene, 1-hexene and/or 1-octene, especially ethylene, are preferred. There are no particular restrictions on the copolymerization ratio or molecular weight, but a copolymer containing a structural unit derived from an α-olefin as a copolymerization monomer is preferably 5% by mass or more, more preferably 7% by mass or more, and particularly preferably 8% by mass or more. A polymer, or a copolymer containing the same structural unit preferably at 35% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less, particularly preferably 18% by mass or less, can be used. . Since these block copolymers are highly flexible, they exhibit particularly excellent mechanical properties and moldability.

Block copolymers such as those described above have a wide range of properties, for example weight average molecular weights of 20,000 to 5,000,000, typically 50,000 to 1,000,000, especially 70,000 to 400,000. density in the range of 0.84-0.92 g/cm ³ , typically 0.85-0.91 g/cm ³ ; crystallinity in the range of 0.5-40%, typically in the range of about 5 to 25%; melt flow rate (2.16 kg according to ASTM D1238, MFR at 230 ° C.) of 0.1 to 90 g/10 min, typically 0.5 to 30 g/10 min melting temperature ranges from 120 to 180° C., typically from 150 to 170° C., particularly from 160 to 165° C., respectively, but is not limited thereto, and the present invention can propylene-α-olefin copolymers can also be used.

The block copolymer in the present invention is preferably a propylene-ethylene block copolymer consisting of a propylene block and an ethylene-propylene copolymer block. More preferably, a block copolymer having 80% by mass or more of propylene-derived structural units and 20% by mass or less of ethylene-derived structural units; particularly, 82 to 92% by mass of propylene-derived structural units and 8 to 8 to 18% by weight of block copolymers; above all block copolymers with 84-90% by weight of propylene-derived units and 10-16% by weight of ethylene-derived units are used.

Propylene-ethylene block copolymers such as those described above can be produced, for example, by polymerizing propylene alone and then copolymerizing ethylene, and are also called propylene block polymers or block polypropylenes. Generally, a propylene-ethylene block polymer develops a so-called sea-island structure in which phases of ethylene blocks or ethylene-propylene copolymer blocks are dispersed in a continuous phase in which propylene is polymerized exclusively. Since ethylene-propylene copolymers are generally flexible, they provide flexibility to the hollow plate core. Therefore, when used in the present invention, it is possible to provide a laminated structure having excellent moldability, appearance, and mechanical properties.

[Polyethylene resin]
The polyethylene-based resin in the present invention is not particularly limited as long as it contains at least a part of repeating units of ethylene. For example, the polyethylene-based resin in the present invention includes resins containing more than 50% by mass of ethylene component units, particularly 70% by mass or more. Polyethylene-based resins may be used singly or in combination of two or more. The origin of the polyethylene-based resin is not particularly limited, and it may be synthesized or manufactured from plant-derived raw materials.

Examples of polyethylene-based resins include the following.
・High density polyethylene (HDPE): polyethylene with a density of 0.942 g/cm ³ or more ・Medium density polyethylene: polyethylene with a density of 0.930 g/cm ^{3 or more and less than 0.942 g/cm 3 ・}Low density polyethylene (LDPE) ): polyethylene having a density of 0.910 g/cm ³ or more and less than 0.930 g/cm ³ Linear low-density polyethylene (LLDPE): having a density of 0.911 g/cm ³ or more and less than 0.940 g/cm ³ Linear Polyethylene/Ultra Low Density Polyethylene (ULDPE): polyethylene with a density less than 0.910 g/ ^cm3

The polyethylene resin in the present invention is a functional group-containing polyethylene resin (ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, metal salt of ethylene-methacrylic acid copolymer ( ionomers), ethylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate copolymers, maleic acid-modified polyethylene, etc.).

From the viewpoint that the effects of the present invention are likely to be exhibited, the polyethylene-based resin preferably contains both the following high-density polyethylene and linear low-density polyethylene. More preferably, the mass ratio of high density polyethylene to linear low density polyethylene is 90:10 to 50:50, more preferably 85:15 to 55:45, especially 80:20 to 60:40. "MFR" is an abbreviation for "melt mass flow rate".
・High-density polyethylene whose MFR (190°C, 2.16 kg) according to JIS K 6922-1 (ISO1133) is 5 g/10 minutes or more and 15 g/10 minutes or less ・MFR (190°C, 2.16 kg) is 0.5 g/10 min or more and 1.5 g/10 min or less of linear low density polyethylene

[Inorganic substance powder]
The inorganic substance powder in the present invention includes any component that can be blended with the resin, and for example, what is known as a filler can be preferably used. The inorganic powder may be used singly or in combination of two or more. Inorganic substance powders include both synthesized ones and those derived from natural minerals (pulverized materials such as minerals).

Examples of inorganic substance powders include salts (carbonates, sulfates, silicates, phosphates, borates), oxides, and hydrated metals (calcium, magnesium, aluminum, titanium, iron, zinc, etc.). powders of substances.

Specifically, for example, calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, sulfuric acid Aluminum, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, graphite and other powders.

The shape of the inorganic powder is not particularly limited, and may be particulate (spherical, irregular, etc.), flaky, granular, fibrous, or the like.

The lower limit of the particle size of the inorganic substance powder is not particularly limited, but the average particle size is preferably 0.7 μm or more, more preferably 1.0 μm or more. The upper limit of the particle size of the inorganic substance powder is not particularly limited, but the average particle size is preferably 6.0 μm or less, more preferably 5.0 μm or less. In the present invention, the "average particle size" means a value calculated from the measurement results of the specific surface area by the air permeation method according to JIS M-8511. As a device for measuring the average particle diameter, for example, a specific surface area measuring device “SS-100 type” manufactured by Shimadzu Corporation can be preferably used.

(heavy calcium carbonate)
The inorganic substance powder in the present invention preferably contains calcium carbonate, particularly ground calcium carbonate, and more preferably consists exclusively of ground calcium carbonate.

In the present invention, "heavy calcium carbonate" is obtained by mechanically pulverizing natural calcium carbonate. are distinct. Heavy calcium carbonate is obtained, for example, by pulverizing and classifying natural calcium carbonate such as calcite (limestone, chalk, marble, etc.), shells, and corals.

Heavy calcium carbonate contains particles with a wide range of particle sizes, and is generally known to be poor in moldability. However, according to the present invention, even a hollow plate-like body core containing heavy calcium carbonate has good moldability, and the appearance of the molded product can be excellent.

As the pulverization method in the method for producing heavy calcium carbonate, either wet pulverization or dry pulverization can be employed. Dry pulverization, which does not require a dehydration step, a drying step, or the like, is preferable from an economical point of view. The pulverizer used for pulverizing the heavy calcium carbonate is not particularly limited, and examples thereof include impact pulverizers, pulverizers using pulverizing media (such as ball mills), and roller mills. Classification in the method for producing heavy calcium carbonate can employ conventionally known means such as air classification, wet cyclone, and decanter.

The ground calcium carbonate may or may not be surface-treated. The surface treatment can be performed at any time (before pulverization, during pulverization, before classification, after classification, etc.) in the method for producing heavy calcium carbonate.

Examples of the surface treatment of heavy calcium carbonate include physical methods (plasma treatment, etc.) and chemical methods (methods using coupling agents, surfactants, etc.).

Examples of coupling agents used in chemical methods for surface treatment of heavy calcium carbonate include silane coupling agents and titanium coupling agents.

Surfactants used in chemical methods for surface treatment of heavy calcium carbonate include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. More specific examples include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

By applying the surface treatment as described above, the dispersibility and the like of heavy calcium carbonate can be enhanced. However, heavy calcium carbonate that has not been subjected to surface treatment is preferable in that the risk of odor generation due to thermal decomposition of the surface treatment agent during molding can be reduced.

The form of ground calcium carbonate is not particularly limited, but from the viewpoint of good dispersibility in the hollow plate core, it is preferably in the form of particles.

When the ground calcium carbonate is particulate, its average particle size is preferably 0.7 μm or more and 6.0 μm or less, more preferably 1.0 μm or more and 5.0 μm or less, still more preferably 1.5 μm or more and 3.0 μm. It is below. Moreover, it is preferable that the particle size distribution does not contain particles having a particle size of 45 μm or more.

When the average particle size of the heavy calcium carbonate is within the above range, the dispersibility in the core of the hollow plate is good, and an excessive increase in viscosity during production of the laminated structure can be prevented. Furthermore, the heavy calcium carbonate particles are less likely to protrude from the surface of the hollow plate-like body core or the laminated structure and fall off, or the surface properties, mechanical strength, etc. are less likely to be impaired, and the effects of the present invention are more likely to be achieved.

When ground calcium carbonate is particulate, its irregularity can be represented by the degree of spheroidization of the shape, ie, the degree of circularity. A lower roundness means a higher irregularity. When the ground calcium carbonate is particulate, its circularity is preferably 0.50 or more and 0.95 or less, more preferably 0.55 or more and 0.93 or less, and still more preferably 0.60 or more and 0.90. It is below.

In the present invention, the term “roundness” refers to a value obtained by dividing the projected area of a particle by the area of a circle having the same perimeter as the projected perimeter of the particle ((projected area of the particle)/(projected perimeter of the particle). means the area of a circle with the same perimeter)). The method of measuring the roundness is not particularly limited, but for example, the roundness can be specified by analyzing a projected image of particles obtained with a scanning microscope, a stereomicroscope, or the like, using commercially available image analysis software. Specifically, the projected area of the particle (A), the area of the circle having the same perimeter as the projected perimeter of the particle (B), the radius of the circle having the same perimeter as the projected perimeter of the particle (r), the particle can be calculated by the following formula based on the measurement results of the projection perimeter (PM) of the .
"Roundness" = A/B = A/πr ² = A x 4π/(PM) ²

[Material of Hollow Plate Core]
The hollow plate core in the present invention contains the polypropylene-based resin and/or polyethylene-based resin and the inorganic powder as described above, and the mass ratio of the polypropylene-based resin and/or polyethylene-based resin to the inorganic powder is 10:90 to 50:50. Here, the hollow plate-shaped body core may contain both polypropylene-based resin and polyethylene-based resin as resin components. When the hollow plate core contains a polypropylene-based resin and a polyethylene-based resin, the mass ratio of the polypropylene-based resin to the polyethylene-based resin is about 50:50 to 95:5, particularly about 55:45 to 90:10. is preferred.

More preferably, about 5.0 to 47.5% by mass, particularly about 5.5 to 45.0% by mass of polypropylene-based resin with respect to the total mass of the hollow plate core; and/or 0.5 to about 25.0% by mass, particularly about 1.0 to 22.5% by mass of polyethylene resin; and about 50.0 to 90.0% by mass, particularly about 55.0 to 80.0% by mass of inorganic substance Contains powder, especially ground calcium carbonate. If desired, components other than these may be contained, for example, in an amount of about 0.1 to 5.0% by weight, particularly about 3.0% by weight, based on the total weight of the hollow plate core.

[Lauric acid diethanolamide]
The hollow plate-shaped core in the present invention preferably further contains lauric acid diethanolamide in addition to the raw materials described above. Lauric acid diethanolamide functions as a surfactant and an antistatic agent, and is blended in various cosmetics and resin products. Also in the hollow plate-shaped body core constituting the present invention, the inclusion of lauric acid diethanolamide makes it easier to prevent electrification during molding and improves the miscibility of each component, so that the moldability and mechanical properties can be further improved. . Also, the effect of improving moldability and mechanical properties by lauric acid diethanolamide is generally greater than other antistatic agents and surfactants such as quaternary ammonium salts and polyoxyethylene alkylamines. The content of lauric acid diethanolamide is about 0.1% by mass or more and 1.0% by mass or less, especially 0.2% by mass or more and less than 1.0% by mass, particularly 0 0.8% by mass or less is preferable.

The hollow plate core in the present invention contains, for example, a polypropylene resin, a polyethylene resin, an inorganic substance powder, and lauric acid diethanolamide. Even with a composition in which the ratio is 10:90 to 50:50 and the content of lauric acid diethanolamide is 0.1% by mass or more and 1.0% by mass or less with respect to the total mass of the hollow plate core good.

[Other Components in the Hollow Plate Core]
In addition to the above components, the hollow plate core in the laminated structure of the present invention may further contain optional components within a range that does not impair the effects of the present invention. Such ingredients can be used singly or in combination of two or more. Further, the type and blending amount of such components can be appropriately set according to the effect to be obtained.

Components that can be contained in the core of the hollow plate include lubricants, dispersants, plasticizers and softeners, resins other than polypropylene-based resins and polyethylene-based resins, antistatic agents and surfactants other than dilauric acid diethanolamide, and colorants. agents, anti-degradation agents such as antioxidants, flame retardants, foaming agents, and the like.

(Lubricant)
Any lubricating agent that can be incorporated into a general-purpose resin composition can be used, and examples thereof include paraffin wax, sorbitan ester, glycerin ester, zinc stearate, magnesium stearate, and stearamide.

(dispersant)
Dispersants include long-chain fatty acids such as stearic acid, sodium polyacrylate, polyglycerin fatty acid esters, sorbitan fatty acid esters, and the like.

(Plasticizer)
Examples of plasticizers include acetyltributyl citrate, triethyl citrate, acetyltriethyl citrate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, di-2-methoxyethyl phthalate, dibutyl tartrate, o - Benzoyl benzoic acid ester, diacetin, epoxidized soybean oil, polyethylene wax, and the like.

(Softener)
Examples of softening agents include hydrocarbon oils such as paraffin oil, naphthenic oil, and aromatic oils; vegetable oils such as castor oil, linseed oil, and epoxidized soybean oil; and silicone oils and polyethylene waxes. but not limited to these. By blending these softeners in an amount of, for example, about 0.5 to 5% by mass, particularly about 1 to 2% by mass, with respect to the entire hollow plate core, flexibility is imparted to the hollow plate core and laminated. It is possible to further improve the moldability and mechanical strength of the entire structure.

(Resins other than polypropylene-based resins and polyethylene-based resins)
As resins other than polypropylene-based resins and polyethylene-based resins,
Polyolefin resins such as polypropylene resins, polymethyl-1-pentene, and ethylene-cyclic olefin copolymers;
Polyamide resins such as nylon-6, nylon-6,6, nylon-6,10, nylon-6,12;
Aromatic polyester resins such as polyethylene terephthalate and its copolymers, polyethylene naphthalate, and polybutylene terephthalate;
Polystyrene resins such as atactic polystyrene, syndiotactic polystyrene, acrylonitrile-styrene (AS) copolymer, acrylonitrile-butadiene-styrene (ABS) copolymer;
Polyvinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride;
polyphenylene sulfide;
Polyether-based resins such as polyether sulfone, polyether ketone, polyether ether ketone, and the like are included.
However, from the viewpoint that the effect of the present invention is easily exhibited, the hollow plate core in the laminated structure of the present invention does not contain resins other than polypropylene-based resins and polyethylene-based resins, or even if it contains a small amount (for example, 1.0% by mass or less with respect to the entire hollow plate core).

Any conventionally known organic pigment, inorganic pigment or dye can be used as the colorant. Examples of organic pigments include azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, diosazine-based, perinone-based, quinophthalone-based, and perylene-based pigments. Examples of inorganic pigments include ultramarine blue, titanium oxide, titanium yellow, iron oxide (rouge), chromium oxide, zinc white, and carbon black.

Examples of antioxidants include phosphorus antioxidants, phenolic antioxidants, pentaerythritol antioxidants, and the like.

Examples of flame retardants include halogen-based flame retardants, phosphorus-based flame retardants, and non-phosphorus-based non-halogen flame retardants such as metal hydrates.

Examples of blowing agents include aliphatic hydrocarbons (propane, butane, pentane, hexane, heptane, etc.), alicyclic hydrocarbons (cyclobutane, cyclopentane, cyclohexane, etc.), halogenated hydrocarbons (chlorodifluoromethane , difluoromethane, trifluoromethane, trichlorofluoromethane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichloro tetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, perfluorocyclobutane, etc.), inorganic gases (carbon dioxide, nitrogen, air, etc.), water and the like.

[Manufacturing method of hollow plate core]
For the hollow plate core in the laminated structure of the present invention, for example, a sheet-like material is once manufactured using the above-mentioned components, and after the sheet-like material is processed by bending, etc., it can be bonded, fused, or mechanically sewn. It can manufacture by joining by methods, such as.

A general-purpose sheet manufacturing method can be used to manufacture the sheet-like material. For example, it can be produced through mixing and melt-kneading of components, molding into a sheet-like article or film-like article, and the like. The timing of mixing and melt-kneading can be appropriately set according to the molding method to be adopted (extrusion molding, injection molding, vacuum molding, etc.). For example, mixing may be performed before charging from the hopper of the molding machine or at the same time as molding. Melt-kneading may be performed by, for example, a twin-screw kneader or the like. Further, by a manufacturing method such as co-extrusion, it is possible to simultaneously manufacture the sheet for the hollow plate core and form the adhesive layer, which will be described later.

The produced sheet is then processed into a concave-convex shape or corrugated shape. For example, a hollow columnar core can be produced by forming semicircular cylindrical unevenness on a sheet and joining it with a similarly processed sheet. Alternatively, the sheet may be cut into a desired size, formed into a shape such as a hexagonal column or a cylinder, and joined together. From the viewpoint of simplicity, the bonding is preferably performed by adhesion or fusion, and particularly preferably via an adhesive or an adhesive layer.

(glue)
Adhesives that can be used to manufacture the hollow plate core are not particularly limited, and can be selected from various general-purpose adhesives. Examples include polyester-based adhesives such as polyvinyl acetate and poly(meth)acrylic acid (ester), ethylene-vinyl acetate copolymer (EVA)-based adhesives, modified polyolefin-based adhesives such as maleic anhydride-modified polypropylene, and polyamides. adhesives, epoxy adhesives, polyurethane adhesives, polyolefin adhesives, polyvinyl chloride adhesives, terpene adhesives, phenol resin adhesives, elastomer adhesives such as styrene-butadiene copolymers, Examples include, but are not limited to, hydrides such as SEBS, natural rubber, chloroprene rubber, nitrile-butadiene copolymers, and the like. A plurality of adhesives can also be used together. It is also possible to form these adhesives into sheets or ribbons and use them, for example, as adhesive layers for heat sealing.

<Surface sheet>
The laminated structure of the present invention has a structure in which surface sheets made of a thermoplastic resin are attached to both surfaces of the hollow plate core. Here, the thermoplastic resin is a polypropylene-based resin and/or a polyethylene-based resin. That is, the surface sheet in the present invention is made of polypropylene-based resin and/or polyethylene-based resin. By providing such surface sheets on both sides of the hollow plate-shaped core, the laminated structure of the present invention is excellent in physical properties such as light weight, mechanical strength and heat insulation, and has a good appearance.

Here, "consisting of a polypropylene resin and/or a polyethylene resin" means that, for example, 95% by mass or more, further 97% by mass or more, particularly 99% by mass or more of the surface sheet is a polypropylene resin and/or a polyethylene resin. It means that it does not substantially contain other resins or inorganic powder fillers. This does not mean that the inclusion of a small amount of additives is excluded, and the above-described additives blended into the hollow plate core can also be blended into the surface sheet. For example, the surface sheet contains 0.1 to 2.0 parts by mass of processing aids such as lubricants, plasticizers and antistatic agents, anti-deterioration agents such as antioxidants, coloring agents such as carbon black and pigments, and the like. , in particular about 0.2 to 1.0 parts by mass.

(Polypropylene-based resin and polyethylene-based resin for surface sheet)
The polypropylene-based resin and polyethylene-based resin that constitute the surface sheet are not limited, and the same polypropylene-based resin and polyethylene-based resin as described above can be used as the components of the hollow plate core. For example, the same polypropylene-based resin or polyethylene-based resin selected as the component of the hollow plate core may be used, or a different type of polypropylene-based resin or polyethylene-based resin may be used. A plurality of types of polypropylene-based resins and/or polyethylene-based resins can be used in combination, and the two topsheets can be made of different materials.

In the laminated structure of the present invention, the thermoplastic resin forming the surface sheet is preferably a polypropylene-based resin. That is, the surface sheet in the present invention is preferably a polypropylene resin sheet. Since polypropylene-based resins generally have a low specific gravity, the advantage of the laminated structure of the present invention, which is light weight and high strength, can be further enhanced. In particular, a surface sheet made of polypropylene homopolymer is preferred.

The polypropylene resin constituting the surface sheet also has an MFR (230°C) of about 0.3 to 5.0 g/10 minutes, particularly an MFR (230°C) of 0.3 to 3.0 g/10 minutes. It is preferable that the melt tension (230° C.) is about 5 to 30 g. If the resin constituting the surface sheet has such a melting property, it is excellent in bondability with the hollow plate-shaped core, and the laminate structure of the present invention can be produced more easily.

<<Method for manufacturing laminated structure>>
The laminated structure of the present invention can be produced by any known method from the above-described hollow plate core and surface sheet. For example, surface sheets may be fused to both surfaces of the hollow plate core, or they may be attached using an adhesive. The adhesive used here is also not particularly limited, and various known ones can be used. For example, those exemplified in the description of manufacturing the hollow plate core can be used. Alternatively, surface sheets may be attached to both sides of the hollow plate core via a commercially available double-sided pressure-sensitive adhesive sheet, double-sided adhesive sheet, or the like. It is also possible to attach an adhesive layer to one side or both sides of the surface sheet in advance and heat-seal them. The adhesive layer can be obtained, for example, by two-layer extrusion of a heat-fusible adhesive and a surface sheet raw material.

≪Use of laminated structure≫
The laminated structure of the present invention has high strength despite being based on a general-purpose resin, and is lightweight as a structural material as a whole. Therefore, it is useful as a building material and a material for transport equipment such as aircraft. Since the laminate structure of the present invention is based on a general-purpose resin, it is low in cost and excellent in moldability. Therefore, it can be used as various consumer products and industrial products such as various containers, daily necessities, consumables, electric and electronic parts, and the like.

≪Panel≫
The laminate structure of the present invention is also particularly suitable for use as a panel as it presents a good appearance. Since the panel of the present invention is lightweight, has high strength, and has a good appearance, it is useful as an interior panel for houses and shops, an exhibition panel at an event venue, an advertising panel installed on the outer wall of a building, and the like. Since the panel of the present invention is also excellent in heat insulation, it is also suitable as a building material panel to be installed on a ceiling or a wall surface. Since the core portion is made of a hollow plate, it is possible to easily attach posters or the like using thumbtacks or the like. It is also possible to make small holes in a part of the surface sheet and use it as a sound absorbing panel. The panel of the present invention also has the advantage that it is difficult to burn because the hollow plate core contains a large amount of inorganic powder. From these points, the panel of the present invention is suitable for building materials, display boards, and the like.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
<Fabrication of hollow plate core>
Using an HTM50 counter-rotating twin-screw extruder (manufactured by CTC Co., Ltd.), 40.0 parts by mass of polypropylene resin-1, 60.0 parts by mass of heavy calcium carbonate-1, and 1.0 Parts by mass of lauric acid diethanolamide (LEDA) were kneaded to prepare raw material pellets for hollow plate cores. The obtained raw material pellets were then co-extruded together with an adhesive resin from an extruder equipped with a feed block type T-die and quenched on a chill roll to form an inner layer thickness of about 0.36 mm and each outer layer (adhesion Layers) A 3-layer sheet with a thickness of about 0.02 mm was obtained. The properties of the raw materials used are as follows.
・ Polypropylene resin-1 (PP): propylene homopolymer, MFR (230 ° C.): 0.5 g / 10 minutes ・ Heavy calcium carbonate-1 (CC-1): average particle size: average particle size 1.5 μm, Specific surface area 1.5 m ² /g, no surface treatment Adhesive resin: Mersen (registered trademark) M (EVA base) manufactured by Tosoh Corporation

Ten sheets of the obtained three-layered sheet were laminated with a jig made of a regular hexagonal prismatic PTFE rod of 4 mm on each side sandwiched therebetween, and pressed at about 110°C. This jig had a structure in which 20 PTFE rods were joined at one end in a comb shape, and each PTFE rod was sprayed with low-viscosity silicone oil prior to lamination. . After extracting the PTFE rod from the press-formed body, it was cut to a width of 20 mm to prepare a honeycomb core having a size of approximately 160×35×20 mm and a pitch of approximately 8 mm.

<Production of surface sheet>
Polypropylene-based resin-1 and the adhesive resin are melted using a screw extruder, co-extruded from a feed block type T-die, and then quenched on a cooling roll to obtain a polypropylene layer with a thickness of about 0.40 mm. , a two-layer sheet having an adhesive layer thickness of about 0.02 mm was obtained.

<Production of laminated structure>
On both sides of the hollow plate-shaped core obtained above, two surface sheets were laminated so that the adhesive layer faced the hollow plate-shaped core, and pressed at about 100° C. to obtain the shape shown in FIG. 1a. A laminated structure having a similar shape was produced.

<Evaluation of physical properties of laminated structure>
The laminate structure produced above was evaluated for moldability and appearance according to the following criteria, and the bending strength was measured under the following conditions. Those results are shown in Table 1 below.
Formability A: The hollow plate-like body core could be formed into the intended shape, cutting into the honeycomb core was easy, and the honeycomb core was not deformed even when the surface sheets were laminated.
B: Although the honeycomb core was not conspicuously deformed, it was not easy to manufacture a hollow plate-like body core from the three-layer sheet or to cut it into honeycomb cores.
C: Flow of the three-layer sheet and deformation of the hollow plate-like core occurred during the production of the hollow plate-like core and the pressing during the lamination of the top sheet.
- Appearance A: No chipping or deformation was observed in the core of the hollow plate.
B: Part of the hollow plate core was chipped or deformed.
C: Remarkable deformation of the core portion of the hollow plate.
Bending strength According to JIS K7171:2016, it was measured at a speed of 2 mm/min under the conditions of 23° C. and 50% RH using Autograph AG-100kNXplus (Shimadzu Corporation).

[Comparative Example 1]
A three-layer sheet for a hollow plate-shaped body core was produced using only 100.0 parts by mass of polypropylene resin-1 and 1.0 parts by mass of lauric acid diethanolamide without using heavy calcium carbonate-1. The same operation as in Example 1 was performed except that Evaluation results are shown in Table 1 below.

[Comparative Example 2]
The procedure of Example 1 was repeated except that the mass ratio of polypropylene resin-1:heavy calcium carbonate-1 was set to 60:40 to prepare a three-layer sheet for hollow plate cores. Evaluation results are shown in Table 1 below.

[Comparative Example 3]
7.0 parts by mass of polypropylene resin-1, 93.0 parts by mass of ground calcium carbonate-1, and 1.0 parts by mass of lauric acid diethanolamide were used to prepare a three-layer sheet for the hollow plate core. However, kneading/extrusion was not possible, and the three-layer sheet itself for the hollow plate core could not be produced.

[Comparative Example 4]
The same as in Example 1, except that the surface sheets were laminated in parallel with the arrangement direction of the honeycomb structure to produce a laminated structure in which the hollow plate-like bodies were arranged in the lateral direction (direction of about 35 mm in size). operation was performed. Evaluation results are shown in Table 1 below.

[Example 2]
The same operation as in Example 1 was performed except that 1.0 parts by mass of polyoxyethylene alkylamine (POEA) was used instead of lauric acid diethanolamide. Evaluation results are shown in Table 1 below.

[Example 3]
30.0 parts by mass of polypropylene resin-2, 70.0 parts by mass of ground calcium carbonate-2, and 0.5 parts by mass of lauric acid diethanolamide were used to prepare a three-layer sheet for the hollow plate core. The same operation as in Example 1 was performed, except that it was performed using Evaluation results are shown in Table 1 below. The properties of the raw materials used in this example are as follows.
· Polypropylene resin-2 (b-PP): block polypropylene (structure in which polyethylene and ethylene-propylene copolymer block phases are dispersed in homopolypropylene), MFR (230 ° C.): 0.5 g / 10 minutes · weight Quality calcium carbonate-2 (CC-2): average particle size: 2.2 μm, BET specific surface area: 1.0 m ² /g, no surface treatment

[Comparative Example 5]
A three-layer sheet for a hollow plate-shaped body core was produced using only 100.0 parts by mass of polypropylene-based resin-2 and 0.5 parts by mass of lauric acid diethanolamide without using heavy calcium carbonate-2. The same operation as in Example 2 was attempted, except that it was carried out. Although a three-layer sheet could be produced, a part of the sheet flowed when these sheets were laminated and pressed, and it was not possible to produce a hollow plate-shaped core of the desired shape.

[Example 4]
20.0 parts by mass of polypropylene-based resin-1, 6.7 parts by mass of polyethylene-based resin-1, 3.3 parts by mass of polyethylene-based resin-2, 70 The same operation as in Example 1 was performed except that 0.0 parts by mass of ground calcium carbonate-1 and 0.5 parts by mass of lauric acid diethanolamide were used. Evaluation results are shown in Table 1 below. The characteristics of the polyethylene-based resin used in this example are as follows.
・Polyethylene resin-1 (PE-1): high density polyethylene, density: 0.950 g/cm ³ , MFR (190°C, 2.16 kg): 7.5 g/10 minutes ・Polyethylene resin-2 (PE- 2): Linear low-density polyethylene, density: 0.918 g/cm ³ , MFR (190°C, 2.16 kg): 1.0 g/10 minutes

[Example 5]
20.0 parts by mass of polyethylene-based resin-1, 10.0 parts by mass of polyethylene-based resin-2, 70.0 parts by mass of ground calcium carbonate-1, and 0.5 parts by mass of lauric acid diethanolamide were used. Evaluation results are shown in Table 1 below.

[Comparative Example 6]
66.7 parts by mass of polyethylene-based resin-1, 33.3 parts by mass of polyethylene-based resin-2, and 0 The same operation as in Example 3 was attempted, except that only 5 parts by mass of lauric acid diethanolamide was used. Although a three-layer sheet could be produced, a part of the sheet flowed when these sheets were laminated and pressed, and it was not possible to produce a hollow plate-shaped core of the desired shape.

[Comparative Example 7]
The same operation as in Comparative Example 1 was performed using polyethylene terephthalate (PET) instead of polypropylene resin-1. However, press molding of the hollow plate core from the three-layer sheet was performed at about 160°C. Although the molding temperature was set to be higher than in Example 1 and Comparative Example 1, it was difficult to obtain a hollow plate-shaped body core having the desired shape, and cutting into honeycomb cores was not easy. Table 1 shows the evaluation results.

As shown in Table 1, the laminate structures of Examples 1 to 5 according to the present invention were all excellent in moldability and had a good appearance. In particular, in Examples 1 and 3 to 5, in which lauric acid diethanolamide was blended, it was easy to prepare a hollow plate-shaped core. On the other hand, the laminate structures of Comparative Examples 1, 5, and 6, which did not contain the inorganic filler, were generally poor in moldability and poor in appearance. The same tendency was observed in the laminated structure of Comparative Example 2 in which the mass ratio of resin to inorganic substance powder was 60:40. In addition, in Comparative Example 3 in which the amount of inorganic substance powder in the core of the hollow plate-shaped body exceeded 90% by mass, it was impossible to mold the sample itself (not shown in Table 1, but as described above). rice field.

The laminate structure of Comparative Example 1, etc., in which the composition of the core portion of the hollow plate-shaped body did not satisfy the requirements of the present invention, had a small strength even when a sample having a relatively good appearance was obtained. Moreover, even if the composition of the core portion of the hollow plate body was the same, the flexural strength was considerably lowered when the laminated structure was not arranged in the thickness direction as in Comparative Example 4.

The decrease in bending strength as described above could be prevented by using PET as the resin component of the core portion of the hollow plate as in Comparative Example 7. became difficult to say. On the other hand, the laminated structure of Examples 1 to 5 according to the present invention, particularly the laminated structure of Example 4 containing polypropylene-based resin, polyethylene-based resin, ground calcium carbonate, and lauric acid diethanolamide, was molded. It not only had good properties and appearance, but also had high flexural strength. It was shown that the present invention has remarkable effects.

REFERENCE SIGNS LIST 1 laminated structure 2 hollow plate core 3 surface sheet 4 surface sheet

Claims (10)

A laminated structure in which a surface sheet made of a thermoplastic resin is attached to both surfaces of a hollow plate-shaped body core in which hollow plate-shaped bodies are arranged in the thickness direction,
The hollow plate core contains a polypropylene-based resin and/or a polyethylene-based resin and an inorganic substance powder, and the mass ratio of the polypropylene-based resin and/or the polyethylene-based resin to the inorganic substance powder is 10. : 90 to 50:50, and the surface sheet is made of a polypropylene-based resin and/or a polyethylene-based resin. The hollow plate-shaped core contains lauric acid diethanolamide, and the content of the lauric acid diethanolamide is 0.1% by mass or more and 1.0% by mass or less with respect to the total mass of the hollow plate-shaped core. 2. The laminate structure of claim 1, wherein a. 3. The laminated structure according to claim 2, wherein said polypropylene-based resin of said hollow plate core is a polypropylene homopolymer and/or a propylene block polymer. 2. The laminated structure of claim 1, wherein said hollow plate-shaped core comprises both said polypropylene-based resin and said polyethylene-based resin. 2. The laminate structure according to claim 1, wherein said surface sheet is a polypropylene resin sheet. 2. The laminate structure of claim 1, wherein said inorganic powder is ground calcium carbonate. 7. The laminate structure according to claim 6 , wherein said ground calcium carbonate has an average particle size of 0.7 [mu]m or more and 6.0 [mu]m or less. 2. The laminate structure according to claim 1, wherein said hollow plate core and said surface sheet are bonded together via an adhesive layer. 2. The laminated structure of claim 1, wherein said hollow plate core is selected from the group consisting of a honeycomb core, a hollow cylindrical core, a corrugated corrugated core, and a harmonica core. A panel composed of the laminated structure according to any one of claims 1 to 9 .

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