Molded bodies and sound-absorbing materials

Abstract

To provide a molding having adequate rigidity while holding sound absorption performance, and a sound absorption material using the molding.SOLUTION: A molding contains a pulp fiber and a synthetic resin, wherein density of the molding is 0.1 g / cm3 or more and 0.8 g / cm3 or less, and a bending elastic gradient of the molding is 0.5 N / cm or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a molded body and a sound-absorbing material using the same.

Background Art

[0002] Conventionally, in home appliances such as electric refrigerators, air conditioners, and electric vacuum cleaners, in order to absorb noise and vibration generated by motors, compressors, etc., for example, a sound-absorbing material (porous sound-absorbing material) made of a porous material is known to be used. In addition, sound-absorbing materials are also used for interior building materials, automobiles, etc. In automobiles, in order to maintain the quietness of the passenger compartment space, a sound-absorbing material is bonded to the panel constituting the vehicle body or between the floor panel and the carpet. Patent Document 1 aims to provide a sound-absorbing material having a high sound-absorbing effect even when thin, for sounds in a wide frequency band from low-frequency sounds to high-frequency sounds. The density is 0.04 to 0.20 g / cm 3 and a porous body having an Asker FP hardness of 15 to 95, a film provided on at least one surface of the porous body, having a basis weight of 10 to 100 g / m 2 and having a tensile elongation in the MD direction of 100 to 800%, and an adhesive layer provided between the porous body and the film, and a slit penetrating the film and the adhesive layer are provided. A sound-absorbing material is disclosed. In addition, Patent Document 2 aims to provide an easily moldable sound-absorbing material having good formability in deep drawing or shallow drawing molding, excellent sound insulation properties, and excellent safety, and further providing an easily moldable sound-absorbing material having excellent flame retardancy and low shrinkage without containing a flame retardant. In a sound-absorbing material in which a skin material is laminated on at least one side of an organic fiber non-woven fabric, the skin material contains a resin binder having a glass transition temperature below the deep drawing or shallow drawing molding temperature, and the bulk density is 0.1 to 0.8 g / cm 3 An easily moldable sound-absorbing material characterized by being as described is disclosed.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Patent No. 6769423 [Patent Document 2] Japanese Patent Publication No. 2005-335279 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] As disclosed in Patent Documents 1 and 2, nonwoven fabrics generally have a bulky, porous structure with a high void ratio, and therefore possess sound-absorbing properties. Based on these sound-absorbing properties, they are used as sound-absorbing materials. Sound-absorbing materials used in automotive interiors and construction require not only sound absorption performance but also appropriate rigidity. However, the sound-absorbing materials disclosed in Patent Documents 1 and 2 have not adequately considered this point.

[0005] The present invention aims to provide a molded body having appropriate rigidity while maintaining sound absorption performance, a method for manufacturing the same, and a sound-absorbing material using the molded body. [Means for solving the problem]

[0006] The inventors have discovered that in a molded article containing pulp fibers and synthetic resin, by setting the density within a specific range and the bending elastic gradient above a specific value, appropriate rigidity can be achieved while maintaining sound absorption performance, and have thus completed the present invention.

[0007] In other words, the present invention is as follows <1> ~ <9> Regarding. <1> A molded article containing pulp fibers and synthetic resin, wherein the density of the molded article is 0.1 g / cm³. 3 More than 0.8g / cm 3 A molded body wherein the bending elastic gradient of the molded body is 0.5 N / cm or more. <2> The thickness of the molded body is 2 mm or more and 20 mm or less. <1> The molded body described above. <3> The basis weight of the molded body is 500 g / m². 2 More than 4000g / m 2 The following is: <1> or <2> The molded body described above. <4> The sound absorption coefficient of the molded body at a frequency of 2 kHz is 5% or more. <1> ~ <3> A molded body as described in any one of the following. <5> The aforementioned synthetic resin is a polyolefin. <1> ~ <4> A molded body as described in any one of the following. <6> The aforementioned synthetic resin includes synthetic fibers, <1> ~ <5> A molded body as described in any one of the following. <7> The mass ratio of synthetic resin to pulp fibers in the molded article (synthetic resin / pulp fibers) is 10 / 90 or more and 95 / 5 or less. <1> ~ <6> A molded body as described in any one of the following. <8> <1> ~ <7> A sound-absorbing material made using a molded body described in any one of the following. <9> <1> ~ <7> A method for manufacturing a molded article as described in any one of the above, comprising the following steps 1 and 2 in this order. Step 1: Step to prepare a porous body containing pulp fibers and synthetic resin. Step 2: A step of heat-pressing the porous body. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a molded body having appropriate rigidity while maintaining sound absorption performance, a method for manufacturing the same, and a sound-absorbing material using the molded body. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing a web forming apparatus used in the manufacturing method for producing the molded article of this embodiment. [Modes for carrying out the invention]

[0010] [Molded body] The molded article of this embodiment is a molded article containing pulp fibers and synthetic resin, wherein the density of the molded article is 0.1 g / cm³.3 0.8 g / cm or more 3 and the bending elastic gradient of the molded body is 0.5 N / cm or more. The molded body of the present embodiment has appropriate rigidity while maintaining sound absorption performance. Although the detailed reason for obtaining the above effect is unknown, it is partly considered as follows. When the density of the molded body is 0.1 g / cm 3 0.8 g / cm or more 3 or less, it is considered that the sound absorption performance is maintained. Further, by setting the bending elastic gradient of the molded body to 0.5 N / cm or more, it is considered that appropriate rigidity is imparted. Hereinafter, the present invention will be described in detail.

[0011] [Pulp fiber] The pulp fiber applicable to the molded body of the present embodiment is not particularly limited in its production method and type. For example, chemical pulp such as kraft pulp of hardwood and / or softwood, mechanical pulp such as SGP, RGP, BCTMP and CTMP, waste paper pulp such as deinked pulp, and non-wood pulp such as kenaf, jute, bagasse, bamboo, straw, hemp, etc. may be used. Further, chlorine-free pulp such as ECF pulp and TCF pulp can be used.

[0012] Among the above pulp fibers, kraft pulp fibers, particularly softwood kraft pulp fibers (NBKP) with a long fiber length, are preferably used because they are more excellent in the rigidity of the molded body.

[0013] From the viewpoint of improving the rigidity of the molded body and the ease of manufacturing the molded body, the average fiber length of the pulp fiber is preferably 0.1 mm or more, more preferably 0.5 mm or more, still more preferably 1 mm or more, and preferably 50 mm or less, more preferably 10 mm or less, still more preferably 5 mm or less, and still more preferably 2.5 mm or less. The average fiber length of the pulp fiber is measured by the method described in the examples.

[0014] The average fiber width of the pulp fibers is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 15 μm or more, and preferably 150 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, and even more preferably 50 μm or less, from the viewpoint of improving the rigidity of the molded article and the ease of manufacturing the molded article. The average fiber width of the pulp fibers is measured by the method described in the examples.

[0015] When the molded article of this embodiment is manufactured by hot press molding of a porous material (preferably a nonwoven fabric, more preferably a dry nonwoven fabric), the porous material is preferably a dry nonwoven fabric produced by the airlaid method. In this case, the pulp fibers can be in the form of, for example, defibrated dry pulp.

[0016] From the viewpoint of improving the rigidity of the molded article, it is preferable that the pulp fibers be unbeaten pulp fibers. Furthermore, from the above viewpoint, the ratio of fine fibers in the pulp fibers is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less, and there is no particular lower limit. The fine fiber ratio of the pulp fibers is measured by the method described in the examples.

[0017] The pulp fiber content in the molded article is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of sound absorption, productivity, and ease of manufacturing, and even more preferably 50% by mass or more, and particularly preferably 55% by mass or more, from the viewpoint of biomassification degree. Furthermore, from the viewpoint of obtaining a molded article with appropriate rigidity, it is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 75% by mass or less.

[0018] [Synthetic resin] The molded article of this embodiment contains a synthetic resin. Examples of synthetic resins include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polylactic acid (PLA), polyolefins such as polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymers and their modified products, and nylon (registered trademark). Among these, from the viewpoint of moldability, the synthetic resin is preferably polyolefin and its modified products, and more preferably polyolefin. The synthetic resin may be used alone or two or more types may be used in combination.

[0019] Examples of polyolefins include polyethylene, polypropylene, and ethylene-propylene copolymer, with polyethylene and polypropylene being preferred. Furthermore, in modified polyolefins, examples of methods for modifying polyolefins include acid modification and chlorination, and among these, acid modification is preferred from the viewpoint of improving affinity with pulp fibers. The acid-modifying component used for acid-modified polyolefins is preferably an unsaturated carboxylic acid component. The unsaturated carboxylic acid component is a component derived from an unsaturated carboxylic acid and its acid anhydride. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, and crotonic acid. Among these, the unsaturated carboxylic acid component is preferably at least one selected from acrylic acid, methacrylic acid, maleic acid, and maleic anhydride, and particularly preferably at least one selected from maleic acid and maleic anhydride. Polyolefins modified with at least one of maleic acid and maleic anhydride are also called maleic acid-modified polyolefins. The acid-modified polyolefin is preferably a maleic acid-modified polyolefin, and more preferably a maleic acid-modified polyethylene or a maleic acid-modified polypropylene. It is sufficient that at least a portion of the acid-modified polyolefin is acid-modified. The polyolefin is particularly preferably at least one selected from the group consisting of polyethylene, polypropylene, polyethylene that is at least partially maleic acid modified, and polypropylene that is at least partially maleic acid modified. Polyolefin fibers may be used individually or in combination of two or more types.

[0020] In the case of the molded article of this embodiment, when the porous material (preferably a nonwoven fabric, more preferably a dry nonwoven fabric) is manufactured by hot press molding, the porous material is preferably a dry nonwoven fabric produced by the airlaid method, and the porous material is preferably obtained from a synthetic resin in the form of synthetic fibers. Therefore, it is preferable that the molded article contains synthetic fibers as a synthetic resin. Furthermore, due to the hot press molding process, some or all of the synthetic fibers contained in the porous material may melt, and there is a possibility that parts of the molded product may not retain their fiber shape, or that the fiber shape may not be observable.

[0021] The synthetic fibers (fibers made of synthetic resin) used to obtain the porous body preferably have at least one of the following forms: hollow tubular and crimped. As will be described in more detail later, if the porous body is a nonwoven fabric, and especially if it is an airlaid nonwoven fabric, it is preferable that the fibers made of synthetic resin do not melt during the heat treatment in the manufacture of the airlaid nonwoven fabric. The melting point of the synthetic resin constituting the synthetic fiber is preferably 200°C or lower, more preferably 195°C or lower, even more preferably 180°C or lower, and preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of ease of molding and suppression of deterioration of pulp fibers.

[0022] The synthetic fiber may be a composite fiber made of two or more synthetic resins, and examples include split fibers, sea-island fibers, core-sheath fibers, and bonded fibers. Among these, core-sheath fibers are preferred from the viewpoint of increasing rigidity. When core-sheath fibers are used, fibers with a concentric cross-sectional structure or an eccentric cross-sectional structure are used, but fibers with a concentric cross-sectional structure are preferred. Using fibers with a concentric cross-sectional structure is preferable because it allows for a more uniform porous body and molded body.

[0023] From the viewpoint of obtaining a uniform porous body (preferably a nonwoven fabric, more preferably a dry nonwoven fabric) and a molded body, and from the viewpoint of ease of manufacturing the porous body, the fiber length of the synthetic fiber is preferably 0.1 mm or more, more preferably 1.0 mm or more, even more preferably 2.0 mm or more, even more preferably 3.0 mm or more, and preferably 50 mm or less, more preferably 20 mm or less, and even more preferably 10 mm or less. The fiber length of the synthetic fiber is measured by the method described in the examples.

[0024] From the viewpoint of obtaining a uniform porous body and molded body, and from the viewpoint of ease of manufacturing the porous body and molded body, the fiber diameter of the synthetic fiber is preferably 0.1 μm or more, more preferably 1 μm or more, even more preferably 10 μm or more, and preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less. The fiber diameter of the synthetic fiber is measured by the method described in the examples.

[0025] From the viewpoint of obtaining a uniform porous body and molded body, and from the viewpoint of ease of manufacturing the porous body and molded body, the fineness of the synthetic fiber is preferably 0.01 dtex or more, more preferably 0.1 dtex or more, even more preferably 1 dtex or more, and preferably 100 dtex or less, more preferably 50 dtex or less, and even more preferably 10 dtex or less.

[0026] The molded article of this embodiment may contain the following other synthetic resins as the synthetic resin. If other synthetic resins are included, the content of these other synthetic resins is preferably 0.1% to 45% by mass, more preferably 0.3% to 30% by mass, even more preferably 0.4% to 20% by mass, and even more preferably 0.5% to 10% by mass, based on the total mass of the molded article. By keeping the content of other synthetic resins within the above range, handling properties and other factors during the manufacturing of the molded article can be improved. Other synthetic resins that can be used include sodium alginate, hydroxyethylcellulose, carboxymethylcellulose, acrylic resin, styrene-(meth)acrylic acid ester copolymer resin, urethane resin, polyvinyl alcohol (PVA) resin, various starches, cellulose derivatives, sodium polyacrylate, polyacrylamide, polyvinylpyrrolidone, acrylamide-acrylic acid ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer alkali salt, isobutylene-maleic anhydride copolymer alkali salt, polyvinyl acetate resin, styrene-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, styrene-butadiene-(meth)acrylic acid ester copolymer, etc.

[0027] The synthetic resin content in the molded article is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, from the viewpoint of improving sound absorption, productivity, and ease of manufacturing. From the viewpoint of biomassification, it is even more preferably 50% by mass or less, and particularly preferably 45% by mass or less. Furthermore, from the viewpoint of obtaining a molded article with appropriate rigidity, it is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 25% by mass or more. When using two or more types of synthetic resins, the above content refers to the total content of the synthetic resins.

[0028] The mass ratio of synthetic resin to pulp fibers in the molded article (synthetic resin / pulp fibers) is preferably 10 / 90 or more, more preferably 15 / 85 or more, even more preferably 25 / 75 or more, and preferably 95 / 5 or less, more preferably 90 / 10 or less, even more preferably 85 / 15 or less, and even more preferably 50 / 50 or less, and particularly preferably 45 / 55 or less, from the viewpoint of obtaining a molded article with appropriate rigidity, productivity and ease of manufacturing of the molded article, and sound absorption.

[0029] Furthermore, the total amount of pulp fibers and synthetic resin in the molded article is preferably 55% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and 100% by mass or less.

[0030] [Other ingredients] The molded article may contain other components in addition to the pulp fibers and synthetic resins mentioned above. Examples of other components include natural resins. Examples of natural resins include various starches and casein.

[0031] The molded article may further contain other components such as fillers and papermaking chemicals. Examples of fillers include mineral pigments such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, white carbon, bentonite, zeolite, sericite, and smectite, as well as organic pigments such as polystyrene resins, urea resins, melamine resins, acrylic resins, and vinylidene chloride resins. Examples of papermaking chemicals include paper strength enhancers, yield enhancers, water drainage enhancers, dyes, fluorescent whitening agents, pH adjusters, defoamers, pitch control agents, and slime control agents. Examples of paper strength enhancers include polyacrylamide. Furthermore, wet paper strength enhancers can also be used in combination, such as polyamide resins, melamine-formaldehyde resins, urea-formaldehyde resins, polyamide-polyamine-epichlorohydrin resins, and polyethyleneimine resins. If other components are present, the content of the other components, excluding pulp fibers and synthetic resins, is preferably 0.1% to 45% by mass, more preferably 0.3% to 30% by mass, even more preferably 0.4% to 20% by mass, and even more preferably 0.5% to 10% by mass, based on the total mass of the molded article.

[0032] As described above, the molded article of this embodiment is preferably manufactured by hot-press molding a porous material (preferably a nonwoven fabric, more preferably a dry nonwoven fabric). That is, the molded article of this embodiment is preferably manufactured by a manufacturing method that includes the following steps 1 and 2 in this order. Step 1: Step to prepare a porous body containing pulp fibers and synthetic resin. Step 2: A step of heat-pressing the porous body. The following describes porous materials suitable for the manufacture of molded products.

[0033] [Characteristics of porous materials] When the tensile strength of a porous material in a first direction is T, and the tensile strength in a second direction perpendicular to the first direction is Y, the ratio T / Y is preferably between 0.5 and 1.5. Setting T / Y within this range is preferable because it provides excellent rigidity and strength. T / Y is more preferably 0.60 or higher, even more preferably 0.70 or higher, even more preferably 0.80 or higher, particularly preferably 0.85 or higher, and more preferably 1.45 or lower, even more preferably 1.40 or lower, and even more preferably 1.35 or lower. The first direction of a porous material is any one direction in the planar direction of the porous material. However, if the fibers or other materials contained in the porous material are oriented in any direction in the planar direction, that orientation direction shall be considered the first direction. Furthermore, if the flow direction in the manufacturing process of the porous material is known, that flow direction shall be considered the first direction. When the flow direction in the manufacturing process of a porous material is known, the flow direction in the manufacturing process is sometimes called the first direction (MD direction), and the flow direction in the resulting porous material is sometimes called the T direction. The second direction of a porous material is one direction in the planar direction of the porous material and is perpendicular to the first direction. If the flow direction in the manufacturing process of the porous material is known, the direction perpendicular to the flow direction in the manufacturing process is called the second direction (CD direction), and the second direction in the obtained porous material is sometimes called the Y direction.

[0034] The tensile strength of the porous material in the first and second directions is measured in accordance with JIS P 8113:2006. The tensile strength in each direction was measured using a Tensilon tensile testing machine manufactured by A&D Co., Ltd., with a 15±0.1 mm × 180±1 mm strip at a speed of 20±5 mm / min.

[0035] In this embodiment, the porous material is preferably a dry-laid nonwoven fabric, which is made by dry-laid papermaking after mixing at least pulp fibers and synthetic fibers, and is preferably in the form of a sheet. It is also preferable that the nonwoven fabric is made by press-treating a cotton-like porous material (hereinafter also referred to as a cotton-like porous material) after dry-laid papermaking. The density of the porous material is preferably 0.04 g / cm³. 3 More precisely, 0.05 g / cm³ 3 More preferably 0.06 g / cm³ 3 The above applies, and preferably 0.1 g / cm³. 3 Less than, more preferably 0.08 g / cm³ 3 The following applies: The density of the porous material is measured by the method described in the examples.

[0036] [Method for manufacturing porous materials] In this embodiment, the method for producing the porous material (preferably nonwoven fabric) is not particularly limited, and from the viewpoint of obtaining the desired T / Y ratio and density, examples include the airlaid method, which is a dry manufacturing method, and the water entanglement method, which is a wet manufacturing method. Among these, the dry manufacturing method is preferred from the viewpoint of suppressing fiber orientation in order to obtain the desired T / Y ratio, and specifically, it is preferred to manufacture by the airlaid method. The manufacturing process for the porous material preferably includes a step of mixing pulp fibers and synthetic fibers in air and then depositing them. In other words, the porous material in this embodiment is preferably a dry nonwoven fabric.

[0037] When manufacturing porous materials using the dry papermaking method, it is preferable to employ the airlaid method. The airlaid method is a method of forming an airlaid web by discharging an airflow containing raw materials, such as synthetic fibers and pulp fibers uniformly mixed in an airflow after being defibrated in air, onto a mesh-like endless belt equipped with a suction box on the lower side. In other words, the airlaid method is a method that includes the step of mixing pulp fibers and synthetic fibers in air and depositing them. In the airlaid method, the above operation may be repeated multiple times as needed.

[0038] The web formed by the above method is sheeted by a fiber bonding process as described below. As a fiber bonding process, for example, there is a method of forming a sheet by intertwining synthetic fibers or pulp fibers with each other by passing a needle perpendicular to the web surface, such as the needle punch method. Such bonding processes are preferably used in combination with the web formation method by the carding method. In addition, the fiber bonding process can employ a process in which a heat-fusible adhesive formulated in the dry web is fused to bond the raw material fibers by heating (thermal bonding method), a process in which an adhesive is applied to the obtained dry web to bond the raw material fibers (chemical bonding method), or a method that combines the thermal bonding method and the chemical bonding method (multi-bonding method).

[0039] In the thermal bonding method, it is preferable to heat the heat-fusible adhesive at a temperature at least 20°C higher than its melting point. Heat treatments include hot air treatment and low-pressure hot pressure treatment after hot air treatment.

[0040] When thermal bonding or multi-bonding methods are employed, it is preferable to use a particulate or fibrous heat-fusible adhesive. The heat-fusible adhesive may be the synthetic fiber or binder component described above. As particulate heat-sealable adhesives, heat-sealable resin particles such as polyethylene, polypropylene, polyester low-melting-point polyethylene terephthalate, low-melting-point polyamide, low-melting-point polylactic acid, and polybutylene succinate are used. Fibrous heat-sealable adhesives include polyesters such as low-melting-point polyethylene terephthalate, low-melting-point polylactic acid, polybutylene succinate (PBS), and polyethylene terephthalate (PET), as well as resins such as low-melting-point polyamides, acrylic resins, and vinyl acetate (PVAc). Furthermore, as a heat-fusible synthetic fiber, a heat-fusible composite synthetic fiber with a core-sheath structure, obtained by compounding two types of resins with different melting points, in which only the surface of the fiber melts, can also be preferably used. A heat-fusible composite synthetic fiber with a core-sheath structure has a structure in which a sheath made of a resin with a lower melting point is formed on the outer circumference of a core made of a resin with a higher melting point. Specifically, examples include forms that combine two types of resins with different melting points (PET / PET composite fiber, PE / PET composite fiber, PP / PET composite fiber, PE / PP composite fiber, PVAc / PET composite resin).

[0041] Furthermore, when a chemical bonding method is used to bond fibers, it is preferable to add a binder component to fix the fibers together. The binder component can be appropriately selected as needed, and for example, solution-type binders such as starch, casein, sodium alginate, hydroxyethylcellulose, sodium carboxymethylcellulose salt, polyvinyl alcohol (PVA), and sodium polyacrylate can be used, as well as emulsion-type binders such as polyacrylic acid esters, acrylic styrene copolymers, polyvinyl acetate, ethylene vinyl acetate copolymers, acrylonitrile butadiene copolymers, methyl methacrylate butadiene copolymers, urea-melamine resins, and styrene-butadiene copolymer resins can be used. It is also preferable to use the binder components mentioned above. The binder can be used in various forms, such as fibers, powders, granules, solutions, or emulsions, and two or more types can be used in combination.

[0042] When manufacturing porous materials using the dry papermaking method, calendering may be performed after heat treatment as needed to improve smoothness and control density. Calendering allows for arbitrary control of the sheet density by applying pressure with metal or resin rolls. Furthermore, by setting the calendering rolls to an arbitrary temperature and heating and pressurizing the sheet, a highly smooth and high-density sheet can be obtained.

[0043] In the porous material produced by the dry papermaking method described above, each fiber constituting the porous material is randomly oriented in three dimensions in the longitudinal, width, and thickness directions. Therefore, in this embodiment, the tensile strength in the first direction and the tensile strength in the second direction of the porous material are approximately the same. In other words, in this embodiment, a porous material with excellent isotropy in the planar direction is obtained.

[0044] Furthermore, in the manufacturing process of porous materials, laminated sheets may be produced by laminating any sheet that does not hinder moldability onto the porous material. For example, any sheet can be laminated onto the surface of the porous material or between sheets when laminating porous materials. As the sheets to be laminated, sheets such as tissue or nonwoven fabric can be used. These sheets are laminated for the purpose of improving surface properties, improving interlayer strength, or imparting other functions.

[0045] Porous materials can be obtained by heat and pressure molding using a roll press. Roll pressing allows for arbitrary control of the sheet's density by applying pressure with metal or resin rolls. Furthermore, by setting the rolls used in the roll pressing process to arbitrary temperatures and clearances, and then heating and pressurizing the sheet, a porous material of any desired density can be obtained.

[0046] [Molded body] The molded article of this embodiment is preferably obtained by hot-press molding the porous material described above. The porous material can be hot-pressed at any pressure and temperature to match the desired density of the molded article. The porous material may be used individually or laminated to achieve the desired thickness of the molded article, and the thickness of the molded article can be adjusted by adjusting the number of laminated layers. In the molded article, the pulp fibers are retained as pulp fibers, and the molded article is a pulp fiber-containing molded article. Furthermore, during the molding process, by controlling the heating temperature and heating time, some or all of the synthetic resin contained in the porous material may be melted.

[0047] <Hot-pressed molded body> The molded article is preferably a hot-pressed article obtained by a process of hot-pressing a porous material. During hot-pressing, some of the synthetic resin contained in the porous material may be melted, and it is preferable to perform the hot-pressing to achieve the desired density. In hot-pressing, a uniform and unoriented mixed state of pulp fibers and synthetic fibers in the porous material is maintained, resulting in a molded article in which pulp fibers are extremely uniformly dispersed.

[0048] The hot press molding process is a process of heating and pressurizing a porous body. It is preferable to heat the porous body to 100°C or higher and pressurize it to 2 MPa or higher. The heating temperature in the hot press molding process is preferably 100°C or higher, but it is preferable to adjust it appropriately depending on the type of synthetic resin contained in the porous material. Specifically, it is preferable to heat within a range of ±20°C of the melting point of the synthetic resin contained in the porous material. By heating within such a temperature range, the thermal decomposition of the pulp fibers contained in the porous material (decomposition of hemicellulose) can be suppressed, and a molded article with superior flexural elasticity gradient and strength can be obtained. The pressure conditions in the hot press molding process are preferably 2 MPa or higher, more preferably 3 MPa or higher, preferably 25 MPa or lower, more preferably 15 MPa or lower, and even more preferably 10 MPa or lower, from the viewpoint of obtaining a molded body with excellent bending elastic gradient and strength, and from the viewpoint of reducing energy load. Furthermore, the heating rate until the desired holding temperature is reached is preferably 3°C / min or more and 30°C / min or less, the holding time under the desired heating and pressurizing conditions is preferably 1 minute or more and 30 minutes or less, and thereafter, the pressure is maintained until the temperature at which the molded body is removed, while the cooling rate is preferably 3°C / min or more and 20°C / min or less. Furthermore, a preliminary pressing step may be performed before obtaining the above heating and pressing conditions. It is also preferable to perform a preliminary pressing at a lower pressure under the desired heating conditions, and then increase the pressure to perform the hot pressing step.

[0049] Among the various methods of hot press forming, the autoclave method, which is often used when manufacturing molded parts for large aircraft and other applications, and the die press method, which has a relatively simple process, are preferred. From the viewpoint of obtaining high-quality molded parts with few voids, the autoclave method is preferred.

[0050] In the hot press molding process, multiple hot press molding operations may be performed to prevent defects such as tearing due to insufficient elongation of pulp fibers and synthetic fibers. This makes it possible to obtain a molded body with superior bending elasticity gradient and strength.

[0051] [Characteristics of the molded product] The density of the molded article in this embodiment is 0.1 g / cm³. 3 More than 0.8g / cm 3 The following is preferable: By keeping the density of the molded body within the above range, it is possible to obtain appropriate rigidity while maintaining sound absorption performance. The density of the molded body is preferably 0.10 g / cm³. 3 More preferably 0.13 g / cm³ 3 More preferably 0.15 g / cm³ 3 The above is true, and preferably 0.60 g / cm³. 3 More preferably, 0.50 g / cm³ 3 More preferably, 0.40 g / cm³ 3 The following applies: The density of the molded article is measured by the method described in the examples.

[0052] The thickness of the molded body is not particularly limited, but from the viewpoint of sound absorption performance and rigidity, it is preferably 1 mm or more, more preferably 1.5 mm or more, even more preferably 2 mm or more, and preferably 50 mm or less, more preferably 20 mm or less, and even more preferably 10 mm or less. The thickness of the molded body is measured by the method described in the examples.

[0053] The basis weight of the molded body is not particularly limited, but from the viewpoint of sound absorption performance and rigidity, it is preferably 100 g / m². 2 Above, a comfortable 300g / m 2 More preferably 500 g / m² 2 The above applies, and preferably 6000 g / m². 2 More preferably, 4000 g / m² 2 More preferably, 3000 g / m² 2More preferably, 1500 g / m² 2 The following applies: When the basis weight is within the above range, it is preferable because it results in a molded body that is lightweight, has excellent sound absorption, and possesses appropriate rigidity. The basis weight of the molded article is measured by the method described in the examples.

[0054] From the viewpoint of preferring to have appropriate rigidity, the male molded body of this embodiment has a bending elasticity gradient of 0.5 N / cm or more. The bending elastic gradient is preferably 1.0 N / cm or more, more preferably 5.0 N / cm or more, even more preferably 20 N / cm or more, even more preferably 50 N / cm or more, particularly preferably 100 N / cm or more, and most preferably 300 N / cm or more. From the viewpoint of maintaining sound absorption performance, it is preferably 5000 N / cm or less, more preferably 3000 N / cm or less, and even more preferably 1000 N / cm or less. When the bending elasticity gradient is within the above range, bending is suppressed when fixing or assembling the molded body, improving handling and workability. The bending elasticity gradient is measured by the method described in the examples.

[0055] The molded article of this embodiment preferably has an appropriate flexural modulus, as having an appropriate flexural modulus results in a molded article that maintains sound absorption performance while having excellent rigidity against bending. The flexural modulus of the molded article is preferably 0.001 GPa or higher, more preferably 0.003 GPa or higher, even more preferably 0.01 GPa or higher, and even more preferably 0.1 GPa or higher. There is no particular upper limit, but from the viewpoint of maintaining sound absorption performance, it is preferably 1.5 GPa or lower, more preferably 1.0 GPa or lower. The flexural modulus of the molded article is measured in accordance with JIS K 7171:2016.

[0056] The molded body of this embodiment preferably has sound-absorbing properties, and the normal incidence sound absorption coefficient at a frequency of 2 kHz is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, and even more preferably 30% or more. There is no particular upper limit, but from the viewpoint of imparting appropriate rigidity to the molded body, it is preferably 80% or less, more preferably 70% or less, and even more preferably 65% ​​or less.

[0057] (Application) The molded body of this embodiment is suitably used as a sound-absorbing material. That is, the sound-absorbing material of this embodiment is made using the molded body of this embodiment. While sound-absorbing materials can be used in a variety of applications where conventional sound-absorbing materials have been used, the molded body of this embodiment has appropriate rigidity and is therefore particularly suitable for automotive interior materials and building interior materials. [Examples]

[0058] The features of the present invention will be further described below with reference to examples and comparative examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following specific examples.

[0059] (Example 1) <Manufacturing of nonwoven fabric> NBKP was treated with a swirling-flow jet defibration apparatus to obtain defibrated dry pulp. The processing air velocity in the defibration apparatus was 45 m / min, and turbulence was created by baffles installed in the apparatus. The average fiber length of the obtained defibrated dry pulp (pulp fibers) was 2.38 mm, the average fiber width was 34.3 μm, and the fine fiber ratio was 11.4%.

[0060] Next, the obtained defibrated dry pulp, polypropylene fibers (melting point 160°C, fineness 6.6 dtex, fiber length 5 mm, fiber diameter 30 μm), and polyethylene / polypropylene composite core-sheath fibers (core melting point 160°C, sheath melting point 110°C, fineness 1.7 dtex, fiber length 5 mm, fiber diameter 15 μm) were uniformly mixed with airflow in a ratio of 70 / 15 / 15 (mass ratio) to obtain a fiber mixture.

[0061] Next, an airlaid web was formed from the fiber mixture using the web forming apparatus 1 shown in Figure 1. Specifically, the first carrier sheet 41 was fed onto a permeable endless belt 20 mounted on a conveyor 10 by the first carrier sheet supply means 40. In Example 1, tissue paper (basis weight 14 g / m²) was used as the first carrier sheet 41. 2 ) was used. Note that "basis weight" was measured according to "Paper and cardboard - Method for measuring basis weight" as described in JIS P8124:2011.

[0062] While the permeable endless belt 20 is sucked by the suction box 60, the fiber mixture is dropped and deposited onto the first carrier sheet 41 from the fiber mixture supply means 30 along with the airflow, thereby obtaining a cotton-like nonwoven fabric. At this time, the basis weight of the airlaid web portion was 600 g / m². 2 The fiber mixture was supplied in such a manner.

[0063] Next, the second carrier sheet 51 was laminated on the cotton-like fiber aggregate on the first carrier sheet 41 by the second carrier sheet supply means 50 to obtain an airlaid web-containing laminated sheet. In Example 1, tissue paper (basis weight 14 g / m²) was used as the second carrier sheet 51. 2 ) was used. In other words, in Example 1, the same sheet was used for the first carrier sheet 41 and the second carrier sheet 51.

[0064] The resulting airlaid web-containing laminated sheet was passed through a box-type dryer using a hot air circulation conveyor oven system and treated with hot air at a temperature of 140°C. Subsequently, a roll press treatment was performed to reduce the density to 0.06 g / cm³. 3The density is adjusted to achieve this, and the first and second carrier sheets are peeled off, resulting in a basis weight of 600 g / m². 2 A nonwoven fabric was obtained. The T / Y ratio of the nonwoven fabric was 1.18, and the density was 0.062 g / cm³. 3 The thickness was 10 mm.

[0065] <Fabrication of molded products> The nonwoven fabric was cut into 20cm x 20cm pieces, thereby obtaining two cut pieces. The obtained cut pieces were stacked to create a two-layer laminated structure. Next, the laminated structure was placed in a stainless steel mold having an opening of 20cm x 20cm and a depth of 2.5mm. Then, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5MPa for 5 minutes, and then pressed again at a pressure of 5MPa for 15 minutes. After that, it was cooled while maintaining 5MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 1130g / m². 2 The density is 0.45 g / cm³. 3 Furthermore, due to the heat press molding process, the nonwoven fabric may expand or contract slightly in the longitudinal and transverse directions, and the basis weight of the molded product may differ from that of the nonwoven fabric.

[0066] (Example 2) In the <Preparation of the Molded Body> of Example 1, four cut pieces were obtained, and these cut pieces were stacked to create a four-layer laminated structure. Next, the laminated structure was placed in a stainless steel mold having an opening of 20 cm × 20 cm and a depth of 5.0 mm. Then, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed again at a pressure of 5 MPa for 15 minutes. After that, it was cooled while maintaining 5 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 2200 g / m². 2 The density is 0.44 g / cm³. 3 That was the case.

[0067] (Example 3) In the <Preparation of the Molded Body> of Example 1, six cut pieces were obtained, and these cut pieces were stacked to create a six-layer laminated structure. Next, the laminated structure was placed in a stainless steel mold having an opening of 20 cm × 20 cm and a depth of 8 mm. Then, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed again at a pressure of 5 MPa for 15 minutes. After that, it was cooled while maintaining 5 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 3600 g / m². 2 The density is 0.44 g / cm³. 3 That was the case.

[0068] (Example 4) In the <Preparation of Molded Body> of Example 1, a single piece of fabric was obtained, and a molded body was prepared in a single layer. The nonwoven fabric was placed in a stainless steel mold having an opening of 20 cm x 20 cm and a depth of 2.5 mm. Next, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed again at a pressure of 5 MPa for 15 minutes. After that, it was cooled while maintaining 5 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 660 g / m². 2 The density is 0.26 g / cm³. 3 That was the case.

[0069] (Example 5) In the <Preparation of the Molded Body> of Example 1, a laminated structure was placed in a stainless steel mold having an opening of 20 cm x 20 cm and a depth of 5.0 mm. Next, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed again at a pressure of 5 MPa for 15 minutes. After that, it was cooled while maintaining the pressure of 5 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 1200 g / m². 2 The density is 0.25 g / cm³. 3 That was the case.

[0070] (Example 6) In Example 1, in the <Preparation of the Molded Body>, three cut pieces were obtained, and a molded body was prepared using a three-layer laminated structure. The nonwoven fabric was placed in a stainless steel mold with an opening of 20 cm x 20 cm and a depth of 8.0 mm. Next, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed again at a pressure of 5 MPa for 15 minutes. After that, it was cooled while maintaining the 5 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 2000 g / m². 2 The density is 0.25 g / cm³. 3 That was the case.

[0071] (Example 7) In Example 1, the nonwoven fabric was obtained in the same manner as described above, except that defibrated dry pulp, polypropylene fibers (melting point 160°C, fineness 6.6 dtex, fiber length 5 mm, fiber diameter 30 μm), and polyethylene / polypropylene composite core-sheath fibers (core melting point 160°C, sheath melting point 110°C, fineness 1.7 dtex, fiber length 5 mm, fiber diameter 15 μm) were uniformly mixed with an airflow in a ratio of 60 / 20 / 20 (mass ratio) to obtain a fiber mixture. Subsequently, in the <Preparation of the Molded Body>, six cut pieces were obtained, and these cut pieces were stacked to create a six-layer laminated structure. Next, the laminated structure was placed in a stainless steel mold having an opening of 20 cm × 20 cm and a depth of 8.0 mm. Then, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed again at a pressure of 5 MPa for 15 minutes. After that, it was cooled while maintaining the pressure of 5 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 3400 g / m². 2 The density is 0.42 g / cm³. 3 That was the case.

[0072] (Example 8) In Example 7, <Preparation of Nonwoven Fabric>, a nonwoven fabric was obtained in the same manner as above, except that defibrated dry pulp, polypropylene fibers (melting point 160°C, fineness 6.6 dtex, fiber length 5 mm, fiber diameter 30 μm), and polyethylene / polypropylene composite core-sheath fibers (core melting point 160°C, sheath melting point 110°C, fineness 1.7 dtex, fiber length 5 mm, fiber diameter 15 μm) were uniformly mixed with an airflow in a ratio of 50 / 25 / 25 (mass ratio) to obtain a fiber mixture. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 7. The basis weight of the pulp fiber-containing molded article was 3600 g / m². 2 The density is 0.44 g / cm³. 3 That was the case.

[0073] (Example 9) In Example 8, the nonwoven fabric was obtained in the same manner as described above, except that defibrated dry pulp, polypropylene fibers (melting point 160°C, fineness 6.6 dtex, fiber length 5 mm, fiber diameter 30 μm), and polyethylene / polypropylene composite core-sheath fibers (core melting point 160°C, sheath melting point 110°C, fineness 1.7 dtex, fiber length 5 mm, fiber diameter 15 μm) were uniformly mixed with an airflow in a ratio of 30 / 35 / 35 (mass ratio) to obtain a fiber mixture. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 8. The basis weight of the pulp fiber-containing molded article was 4100 g / m². 2 The density is 0.51 g / cm³. 3 That was the case.

[0074] (Example 10) A nonwoven fabric was obtained in the same manner as in Example 9. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 1. The basis weight of the pulp fiber-containing molded article was 1320 g / m². 2 The density is 0.53 g / cm³. 3 That was the case.

[0075] (Example 11) A nonwoven fabric was obtained in the same manner as in Example 9. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 5. The basis weight of the pulp fiber-containing molded article was 1630 g / m². 2The density is 0.33 g / cm³. 3 That was the case.

[0076] (Example 12) A nonwoven fabric was obtained in the same manner as in Example 9. Subsequently, in the <Preparation of the Molded Body>, two cut pieces were obtained, and a molded body was prepared using a two-layer laminated structure. The nonwoven fabric was placed in a stainless steel mold with an opening of 20 cm x 20 cm and a depth of 8.0 mm. Next, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed again at a pressure of 5 MPa for 15 minutes. After that, it was cooled while maintaining the pressure of 5 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 1900 g / m². 2 The density is 0.24 g / cm³. 3 That was the case.

[0077] (Example 13) A nonwoven fabric was obtained in the same manner as in Example 9. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 4. The basis weight of the pulp fiber-containing molded article was 550 g / m². 2 The density is 0.21 g / cm³. 3 That was the case.

[0078] (Example 14) A nonwoven fabric was obtained in the same manner as in Example 8. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 11. The basis weight of the pulp fiber-containing molded article was 1250 g / m². 2 The density is 0.25 g / cm³. 3 That was the case.

[0079] (Example 15) A nonwoven fabric was obtained in the same manner as in Example 8. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 12. The basis weight of the pulp fiber-containing molded article was 1360 g / m². 2 The density is 0.17 g / cm³. 3 That was the case.

[0080] (Example 16) In Example 8, <Preparation of Nonwoven Fabric>, a nonwoven fabric was obtained in the same manner as above, except that defibrated dry pulp, polypropylene fibers (melting point 160°C, fineness 6.6 dtex, fiber length 5 mm, fiber diameter 30 μm), and polyethylene / polypropylene composite core-sheath fibers (core melting point 160°C, sheath melting point 110°C, fineness 1.7 dtex, fiber length 5 mm, fiber diameter 15 μm) were uniformly mixed with an airflow in a ratio of 20 / 40 / 40 (mass ratio) to obtain a fiber mixture. Subsequently, a pulp fiber-containing molded article was obtained in the same manner as in Example 14. The basis weight of the pulp fiber-containing molded article was 1600 g / m². 2 The density is 0.32 g / cm³. 3 That was the case.

[0081] (Comparative Example 1) A nonwoven fabric was obtained in the same manner as in Example 1. Subsequently, in the <Preparation of the Molded Body>, five cut pieces were obtained, and these cut pieces were stacked to create a six-layer laminated structure. Next, the laminated structure was placed in a stainless steel mold having an opening of 20 cm × 20 cm and a depth of 3.0 mm. Then, the mold was set in a hot press machine and pre-pressed at a temperature of 180°C and a pressure of 1.5 MPa for 5 minutes, and then pressed further at 10 MPa for 15 minutes. After that, it was cooled while maintaining 10 MPa to obtain a pulp fiber-containing molded body. The basis weight of the pulp fiber-containing molded body was 3600 g / m². 2 The density is 1.2 g / cm³. 3 That was the case.

[0082] (Comparative Example 2) In the <Preparation of Nonwoven Fabric> of Example 1, the obtained airlaid web-containing laminated sheet was passed through a box-type dryer using a hot air circulation conveyor oven system, treated with hot air at a temperature of 140°C, and then roll-pressed to a density of 0.06 g / cm³. 3 The density is adjusted to achieve this, and the first and second carrier sheets are peeled off, resulting in a basis weight of 600 g / m². 2 A nonwoven fabric was obtained. The T / Y ratio of the nonwoven fabric was 1.18, and the density was 0.06 g / cm³. 3 The thickness was 10.0 mm.

[0083] (Comparative Example 3) <Manufacturing of porous materials> A porous body comprising a middle layer made of pulp fibers as the raw material fiber, and surface layers on both sides of the middle layer, was manufactured as follows. Spunbond nonwoven fabric (basis weight 40g / m²) is used as surface layer A on a mesh conveyor with a suction box. 2 ) is dispensed, and 5 g / m² is applied to the surface layer A. 2 Polyethylene powder (powder adhesive) was sprayed using a spray device. Then, NBKP and polyethylene / polypropylene composite core-sheath fibers (core melting point 160°C, sheath melting point 110°C, fineness 1.7 dtex, fiber length 5 mm, fiber diameter 15 μm) were uniformly mixed and defibrated by airflow in a ratio of 70 / 30 (mass ratio). An airlaid web (middle layer, basis weight 910 g / m²) was formed on the surface layer A using a dry airlaid web forming device. 2 ) was formed. Next, the same powder adhesive used previously is applied to the airlaid web at a rate of 5 g / m² using a layering device. 2 After spraying, a rayon PET spunlace (basis weight 40g / m²) is applied on top as surface layer B. 2 The layers were fed out in a stacking manner and guided into a hot air dryer, where they were heated above the melting point of the heat-fusible fiber sheaths so that the sheaths would melt. This bonded the surface layers to both sides of the airlaid web, forming a laminate S. Subsequently, the laminate S was passed through a press roll to obtain a porous body.

[0084] <Adhesion of film layers to porous materials> Polyethylene film (basis weight 20g / m²) 2 Tensile elongation in the MD direction: 250%, air permeability: 440 seconds / 100cc, thickness: 20 μm, density: 1 g / cm³ 3 On one side of the surface, a hot melt adhesive with a basis weight of 5g / m² is applied. 2The film was applied in such a manner to form an adhesive layer. The film and the porous body were bonded together so that the adhesive layer and the porous body were in contact, and the film and the porous body were bonded by the hot melt method. Next, slits 100 mm in length and 0.5 mm in width were formed on the film surface so that they penetrate to the adhesive layer, and the ratio of the total slit area to the area of ​​the film surface, i.e., the ratio of the opening area per unit area of ​​the film surface (hereinafter also referred to as the "slit ratio") was 0.8%, and all the slits were aligned in direction, thereby obtaining a molded body.

[0085] [Measurement and Evaluation Methods] (Method for measuring fiber length and fiber diameter of synthetic fibers) Twenty randomly selected synthetic fibers were observed under an optical microscope, and their fiber length and diameter were measured.

[0086] (Method for measuring average fiber length, average fiber diameter, and fine fiber ratio of pulp fibers) In accordance with ISO 16065-2, the average fiber length and average fiber diameter of pulp fibers were measured using a fiber image analysis device (Valmet FS5, manufactured by Valmet Co., Ltd.). The proportion of fine fibers 0.1 mm or less in the measured length-weighted average fiber length distribution was defined as the fine fiber ratio.

[0087] (Method for measuring the melting point of synthetic fibers) A 5 mg sample of synthetic fiber is cut out, and its melting point is measured using a differential scanning calorimeter (DSC). The melting point is measured using a PerkinElmer Diamond DSC under a nitrogen atmosphere, with the temperature increased from 30°C to 280°C at a rate of 20°C / min. If catalog values ​​are available for synthetic fibers, those values ​​may be used.

[0088] (Method for measuring the basis weight of nonwoven fabrics, and the thickness, basis weight, and density of molded articles) The basis weight of the nonwoven fabric was measured according to "Paper and cardboard - Method for measuring basis weight" as described in JIS P8124:2011. The density of the molded body was calculated by measuring the thickness and mass of a 50 mm square molded body after conditioned for 24 hours at 23°C and 50% RH. The thickness of the molded body was measured using a digital thickness gauge (DG-127, manufactured by Ozaki Seisakusho Co., Ltd.).

[0089] (Method for measuring T / Y) The tensile strength (in N / m) was measured in accordance with JIS P 8113:2006, with the flow direction in the manufacturing process of the obtained nonwoven fabric (the direction in which the conveyor 10 travels) designated as the first direction, and the direction perpendicular to the first direction designated as the second direction. The tensile strength in each direction was calculated by dividing this tensile strength by the thickness of the test piece to obtain the tensile strength (in MPa). A Tensilon tensile testing machine manufactured by A&D Co., Ltd. was used to measure a 15 mm x 180 mm strip at a speed of 20 mm / min. Let T be the tensile strength in the first direction, and Y be the tensile strength in the second direction, which is perpendicular to the first direction. Then, T / Y was calculated.

[0090] <Rating> The flexural modulus, flexural gradient, and sound absorption coefficient of the obtained molded products were measured using the method described below. The results are shown in Table 1.

[0091] (Method for measuring the flexural modulus and flexural gradient of molded products) The obtained molded product was cut into strip-shaped test pieces measuring 80 mm in length and 10 mm in width, and a three-point bending test was performed in accordance with JIS K 7171:2016. The obtained bending modulus and bending gradient were evaluated as having superior rigidity against bending, with larger values ​​indicating better rigidity.

[0092] (Method for measuring the sound absorption coefficient of a molded body when the sound is incident on the perpendicular side) The obtained molded body was cut into circular test pieces with a diameter of 29 mm, and the normal incidence sound absorption coefficient in the high-frequency range (500-6300 Hz) was measured in accordance with JIS A 1405-2:2007. Table 1 shows the normal incidence sound absorption coefficient at 2000 Hz. A higher normal incidence sound absorption coefficient was evaluated as indicating better sound absorption performance.

[0093] [Table 1-1]

[0094] [Table 1-2]

[0095] As shown in Examples 1 to 16, the molded articles of the present invention had appropriate rigidity while maintaining sound absorption performance. On the other hand, the density of the molded body is 0.8 g / cm³. 3 In Comparative Example 1, the molded body with a density exceeding 0.1 g / cm³ did not achieve sufficient sound absorption performance. 3 In Comparative Example 2, the molded article had a density of less than 0.5 N / cm and a bending elastic gradient of less than 0.5 N / cm, insufficient rigidity was obtained. Furthermore, the density of the molded article was 0.1 g / m³ 2 In the molded article of Comparative Example 3, which was less than [amount missing], sufficient rigidity could not be obtained. [Explanation of Symbols]

[0096] 1 Web forming apparatus 10 Conveyor 20 Breathable endless belt 30 Fiber mixture supply means 40 First carrier sheet supply means 41. First Career Sheet 50 Second carrier sheet supply means 51. Second Career Sheet A Air Raid Web

Claims

1. A molded article obtained by heat-press molding a nonwoven fabric made using pulp fibers and polyolefin resin fibers, The density of the molded body is 0.13 g / cm³. ３ 0.8g / cm or more ３ The following: The bending elastic gradient of the molded body is 0.5 N / cm or more. Molded body.

2. The molded body according to claim 1, wherein the thickness of the molded body is 2 mm or more and 20 mm or less.

3. The basis weight of the molded body is 500 g / m². ２ More than 4000g / m ２ The molded article according to claim 1 or 2, which is as follows:

4. The molded body according to any one of claims 1 to 3, wherein the normal incidence sound absorption coefficient of the molded body at a frequency of 2 kHz is 5% or more.

5. The molded article according to any one of claims 1 to 4, wherein the mass ratio of polyolefin resin fibers to pulp fibers in the molded article (polyolefin resin fibers / pulp fibers) is 10 / 90 or more and 95 / 5 or less.

6. A sound-absorbing material comprising a molded body according to any one of claims 1 to 5.

7. A method for manufacturing a molded article according to any one of claims 1 to 5, comprising the following steps 1 and 2 in this order. Step 1: A process for preparing a nonwoven fabric containing pulp fibers and polyolefin resin fibers. Step 2: A process of heat-pressing the nonwoven fabric.

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