JP2005335279A - Easy-molding sound-absorbing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound-absorbing material excellent in sound absorption and moldability. <P>SOLUTION: In the sound-absorbing material wherein a skin material is laminated on at least one surface of an organic fiber nonwoven fabric consisting of a thermoplastic fiber or thermoplastic short fiber and a heat-resistant short fiber, the skin material is a wet-laid nonwoven fabric which contains a resin binder that has a glass transition temperature lower than the molding temperature of the deep drawing or shallow drawing and which has a bulk density of 0.1-0.8 g/cm<SP>3</SP>. The above nonwoven fabric suitably used has a Metsuke of 150-800 g/m<SP>2</SP>and a bulk density of 0.01-0.2 g/cm<SP>3</SP>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes interior materials for vehicles such as automobiles, trains and aircraft, air conditioners, electric refrigerators, electric appliances, interior materials for construction, civil engineering materials, railroads, airports, various stadiums, amusement facilities, etc. The present invention relates to an easily moldable sound-absorbing material used where noise countermeasures and moldability of a complicated uneven shape are required.

  Conventionally, sound absorbing materials have been used for electrical appliances, architectural interior materials, vehicles, and the like. In particular, specifications for covering the engine and transmission with a sound-absorbing material are being set for the purpose of preventing external acceleration noise and idle vehicle exterior noise caused by vehicles such as automobiles. The sound-absorbing material is required to have sound absorption and fire resistance (flame retardant) in order to prevent the flame from spreading to the driver's seat when a fire breaks out from the engine room due to an accident.

  In automobiles, in order to keep the interior space quiet, a sound absorbing material is affixed on the panels that make up the vehicle body, especially on the partition (dash panel) between the engine room and the cabin and between the floor panel and the carpet. Matching is done. However, when the sound-absorbing material cannot be sufficiently adhered to the vehicle body panel, a gap is generated and the soundproofing performance becomes insufficient.

  Therefore, as a sound-absorbing material, a urethane foam or felt compression molded body that matches the uneven shape of the vehicle body panel is used instead of a flat plate, and a synthetic resin such as a phenol resin or a melamine resin is used as a skin material on the surface of the base material. There has been provided a laminate-bonded fiber sheet impregnated with.

  However, the urethane foam mold foam has an insufficient sound insulation effect, and in the event of an accident fire, there is a problem in that toxic gas is generated when the sound absorbing material is burned. Further, in the felt molded body, a highly compressed portion is generated and becomes too hard locally, so that the soundproofing performance is deteriorated and it is contrary to the weight reduction of the automobile body.

  For this reason, for example, in Japanese Patent Laid-Open No. 2-95838, a web made of polyester short fibers is laid in a mold and subjected to heat compression molding to obtain a molded body that matches the shape of the dash panel. In addition, a method has been proposed in which a polyvinyl chloride sheet-like sound insulation layer is laminated and laminated in a mold to obtain a vehicle interior material (see Patent Document 1).

JP 2002-161465 discloses a flame-retardant polyester spunbond nonwoven fabric as a skin material on one side of a sound-absorbing material obtained by laminating and integrating a polyester elastomer meltblown nonwoven fabric and a polyester needle punch nonwoven fabric by a needle punch method. A flame-retardant sound-absorbing material with good moldability that has been laminated has been proposed (see Patent Document 2).
Japanese Patent Laid-Open No. 2-95838 JP 2002-161465 A

  However, in the method in which the sound insulation layer is bonded in the mold after being molded in the mold in order to match the uneven shape of the vehicle body panel, the processing method is complicated, so the productivity is reduced and the cost is increased. In addition, the sound-absorbing material bonded with the polyester elastomer melt-blown nonwoven fabric has good adhesion to the vehicle body panel, but the surface material is poorly stretchable, so the adhesive is sufficiently adhered to the uneven shape of the vehicle body panel. There is a problem that the sound insulation and sound absorption effect is inferior. Furthermore, when a flame retardant is contained in the polyester fiber, there is a possibility that a toxic gas is generated during combustion.

  The present invention has been made in view of the above-described conventional problems, and provides an easily moldable sound-absorbing material that is excellent in moldability in deep drawing or shallow drawing, has excellent soundproofing properties, and is excellent in safety. For the purpose. Furthermore, an object of the present invention is to provide an easily moldable sound-absorbing material having excellent flame retardancy and low shrinkage without containing a flame retardant.

  As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention have made a deep drawing of a sound-absorbing material as a resin binder used in the production of a skin material in a sound-absorbing material in which a skin material is laminated on at least one side of an organic fiber nonwoven fabric. Alternatively, by selecting a softened material at the temperature at the time of shallow drawing and setting the bulk density of the skin material before molding within a specific range, it is possible to obtain a sound-absorbing material with excellent moldability and sound-absorbing properties. The headline, the present invention has been reached.

That is, the present invention is as follows.
1) In a sound-absorbing material obtained by laminating a skin material on at least one surface of an organic fiber nonwoven fabric, the skin material contains a resin binder having a glass transition temperature equal to or lower than a deep drawing or shallow drawing temperature, and a bulk density of 0. 1 to 0.8 g / cm ³ , an easily moldable sound absorbing material,
2) The easily moldable sound-absorbing material according to 1), wherein the resin binder is contained in the skin material in an amount of 5 to 40% by mass,
3) The easily moldable sound absorbing material according to 1), wherein the molding temperature is in a range of 160 to 220 ° C.
4) The easily moldable sound absorbing material according to 1), wherein the skin material has a thickness of 0.01 to 1 mm,
5) The easily moldable sound-absorbing material according to 1) above, wherein the skin material has a bulk density of 0.1 to 0.3 g / cm ³ .
6) The easily moldable sound-absorbing material according to 1), wherein the skin material is a wet nonwoven fabric made of heat-resistant short fibers,
7) The easily moldable sound-absorbing material according to 6), wherein the heat-resistant short fibers are aramid short fibers,
8) In the organic fiber nonwoven fabric having a basis weight is 150 to 800 g / ^{m 2,} moldability sound-absorbing material according to the 1) Bulk density of 0.01~0.2g / cm ^3,
9) The organic fibers constituting the organic fiber nonwoven fabric are composed of thermoplastic short fibers and heat-resistant short fibers having a LOI value of 25 or more, and the ratio thereof is in the range of 95: 5 to 55:45. 1) an easily moldable sound absorbing material according to 1),
10) The heat-resistant short fibers are aramid fibers, polyphenylene sulfide fibers, polybenzoxazole fibers, polybenzthiazole fibers, polybenzimidazole fibers, polyether ether ketone fibers, polyarylate fibers, polyimide fibers, fluorine fibers, and flameproof fibers. The easily moldable sound absorbing material according to 9) above, which is one or more organic short fibers selected from:
11) The easily moldable sound-absorbing material according to 9), wherein the heat-resistant short fibers are para-aramid short fibers,
12) The easily moldable sound-absorbing material according to 1) above, wherein the organic fibers constituting the organic fiber nonwoven fabric are thermoplastic fibers,
13) The readily moldable sound absorbing material according to 12), wherein the thermoplastic fiber is one or more fibers selected from polyester fiber, polypropylene fiber, and nylon fiber,
14) The easily moldable sound-absorbing material according to 1) above, wherein the organic fiber nonwoven fabric is a nonwoven fabric obtained by subjecting an organic fiber web to needle punching or water jet punching.

  According to the present invention, it is possible to provide a sound-absorbing material that is excellent in moldability, particularly deep-drawn and shallow-drawn moldability, and excellent in sound absorption performance. When the skin material is a wet nonwoven fabric made of heat-resistant short fibers, it has low shrinkage and excellent heat resistance. When the heat-resistant short fiber is an aramid short fiber, a sound absorbing material having excellent flame retardancy can be obtained. Further, when the organic fiber nonwoven fabric is composed of thermoplastic short fibers and heat-resistant short fibers having a LOI value of 25 or more, the flame retardancy is further improved. It has superior flame retardancy and low shrinkage than when the heat-resistant short fiber is a para-aramid short fiber. When the organic fiber nonwoven fabric is made of thermoplastic fibers, it is economical and durable.

The sound absorbing material of the present invention is formed by laminating a skin material on at least one surface of an organic fiber nonwoven fabric. The organic fiber nonwoven fabric used in the present invention is a nonwoven fabric composed of short fibers or a nonwoven fabric composed of long fibers as long as the basis weight is 150 to 800 g / m ² and the bulk density is 0.01 to 0.2 g / cm ^3. There may be. For example, a needle punch nonwoven fabric, a water jet punch nonwoven fabric, a melt blown nonwoven fabric, a spunbond nonwoven fabric, a stitch bond nonwoven fabric, or the like is used. Among them, a needle punch or a water jet punch nonwoven fabric is desirable. Miscellaneous felts can also be used as the organic fiber nonwoven fabric.

  In this invention, the cross-sectional shape of the fiber which comprises a nonwoven fabric is not specifically limited, A perfect circular cross-sectional shape may be sufficient, and an irregular cross-sectional shape may be sufficient. For example, elliptical shape, hollow shape, X cross-sectional shape, Y cross-sectional shape, T cross-sectional shape, L cross-sectional shape, star-shaped cross-sectional shape, leaf-shaped cross-sectional shape (for example, three-leaf shape, four-leaf shape, five-leaf shape, etc.), other polygonal cross-sections It may be a modified cross-sectional shape such as a triangular shape, a square shape, a five-stroke shape, a hexagonal shape, or the like.

  The organic fibers constituting the nonwoven fabric may be natural fibers or synthetic fibers, but synthetic fibers are preferred from the viewpoint of durability. Examples of such fibers include thermoplastic fibers such as polyester fibers, polyamide fibers, acrylic fibers, polypropylene fibers, and polyethylene fibers. The fiber material is produced according to a known method such as wet spinning, dry spinning, or melt spinning. Can be used. Among these, polyester fiber, polypropylene fiber, and polyamide fiber are preferable from the viewpoint of excellent durability and wear resistance, and these fibers can be used alone or in admixture at any ratio. In particular, polyester fibers are most preferable because the raw material polyester can be easily recycled by heat melting of the used nonwoven fabric, is excellent in economy, has a good texture of the nonwoven fabric, and is excellent in moldability. Some or all of these thermoplastic fibers may be bristles (collected recycled fibers).

  The polyester fiber is a polyester fiber composed of a dicarboxylic acid and glycol having ethylene terephthalate as a main repeating unit. The dicarboxylic acid component includes terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, and 1,4-cyclohexane. And dicarboxylic acid. Examples of the glycol component include ethylene glycol, propylene glycol, tetramethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. A part of the dicarboxylic acid component may be replaced with adipic acid, sebacic acid, dimer acid, sulfonic acid metal-substituted isophthalic acid, etc., and a part of the glycol component may be diethylene glycol, neopentyl glycol, 1, 4-cyclohexanediol, 1,4-cyclohexanedimethanol, polyalkylene glycol, and the like may be substituted.

  The polyester fiber is usually produced from a polyester resin by a known spinning method such as melt spinning. Examples of the polyester fiber include polyethylene terephthalate (PET) fiber, polybutylene terephthalate (PBT) fiber, polyethylene naphthalate (PEN) fiber, polycyclohexylene dimethylene terephthalate (PCT) fiber, polytrimethylene terephthalate (PTT) fiber, poly Although a trimethylene naphthalate (PTN) fiber etc. are mentioned, Especially a polyethylene terephthalate (PET) fiber is preferable.

  This polyester includes various inorganic particles such as titanium oxide, silicon oxide, calcium carbonate, silicon nitride, clay, talc, kaolin, and zirconium acid, and particles such as crosslinked polymer particles and various metal particles. Antioxidants, sequestering agents, ion exchangers, anti-coloring agents, waxes, silicone oils, various surfactants and the like may be added.

The polypropylene fiber is not particularly limited as long as it is a fiber made of polypropylene resin. The polypropylene resin is not particularly limited as long as it is a polymer resin containing a structure of — (CH ₃ ) CH ₂ — in the repeating unit. Polymer resins and the like are included. The polypropylene fiber is produced from the polypropylene resin using a known spinning method such as melt spinning. Various additives that may be added to the above-described polyester fiber may be added to the polypropylene fiber.

  Nylon fibers include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polycaproamide / Examples thereof include fibers made of nylon resin such as polyhexamethylene terephthalamide copolymer (nylon 6 / 6T) and nylon copolymer resin. Nylon fibers are produced from these nylon resins by a known production method such as melt spinning. The nylon fiber may be added with additives that may be added to the above-described polyester fiber.

  The fiber length and fineness of the thermoplastic fiber are not particularly limited and can be appropriately determined depending on the compatibility with other synthetic fibers and the use of the nonwoven fabric, but the fiber length is preferably 10 mm or more. Filaments or staples may be used, but in the case of staples, the fiber length is preferably 10 to 100 mm, and particularly preferably 20 to 80 mm. By using short fibers having a fiber length of 10 mm or more, the tangled short fibers are less likely to fall off the nonwoven fabric. On the other hand, when the fiber length is long, the card passing property tends to be inferior. A fineness of 0.5 to 30 dtex, particularly 1.0 to 10 dtex is preferably used.

  The thermoplastic fibers can be used alone or in admixture of two or more. It is also possible to use a mixture of thermoplastic fibers of the same type or different types and different in fineness and fiber length. In this case, the mixing ratio of the fibers is arbitrary, and can be appropriately determined according to the use and purpose of the nonwoven fabric.

  In order to obtain a sound-absorbing material excellent in heat resistance or flame retardancy, it is preferable that the thermoplastic short fibers and the heat-resistant short fibers are entangled and integrated. This heat-resistant short fiber has a LOI value (limit oxygen index) of 25 or more, and includes a fiber made flame retardant by adding a flame retardant such as a flame retardant rayon fiber, a flame retardant vinylon fiber, or a modacrylic fiber. Absent. Here, the LOI value means the minimum oxygen concentration necessary to burn continuously for 5 cm or more, and the LOI value is a value measured by the JIS L-1091 method. If the LOI value of the heat-resistant short fiber is 25 or more, flame retardancy can be imparted to the nonwoven fabric. However, in order to obtain a nonwoven fabric with better flame retardancy, the LOI value is desirably 28 or more.

  The heat-resistant short fiber suitably used in the present invention is superior to the thermoplastic short fiber in that it is a low-shrinkable fiber that hardly melts and shrinks when the nonwoven fabric burns, but particularly at 280 ° C. Those having a dry heat shrinkage of 1% or less are preferred. Specific examples of heat-resistant short fibers include, for example, aramid fibers, polyphenylene sulfide fibers, polybenzoxazole fibers, polybenzthiazole fibers, polybenzimidazole fibers, polyether ether ketone fibers, polyarylate fibers, polyimide fibers, fluorine fibers, and The short fiber which cut | disconnected the 1 type, or 2 or more types of heat resistant organic fiber chosen from the flame resistant fiber to desired fiber length can be mentioned. As these heat-resistant short fibers, any conventionally known fibers, those manufactured according to a known method or a method analogous thereto can be used. Here, the flame-resistant fiber is mainly produced by baking acrylic fiber at 200 to 500 ° C. in an active atmosphere such as air, and is a precursor of carbon fiber. For example, the product name “Lastan” manufactured by Asahi Kasei Co., Ltd., the product name “Pyromex” manufactured by Toho Tenax Co., Ltd., and the like can be mentioned.

  Among the above heat-resistant short fibers, at least one kind selected from aramid fiber, polyphenylene sulfide fiber, polybenzoxazole fiber, polyether ether ketone fiber, polyarylate fiber and flame-resistant fiber from the viewpoint of low shrinkage and workability Organic fibers are preferred, and aramid fibers are particularly preferred.

  The aramid fibers include para-aramid fibers and meta-aramid fibers. Para-aramid fibers are particularly preferable from the viewpoint of less heat shrinkage. Examples of para-aramid fibers include polyparaphenylene terephthalamide fibers (US DuPont, manufactured by Toray DuPont, trade name “KEVLAR” (registered trademark)), copolyparaphenylene-3,4′-oxydi. Commercial products such as phenylene terephthalamide fiber (manufactured by Teijin Limited, trade name “Technola” (registered trademark)) can be used.

  The aramid fiber may be provided with a film former, a silane coupling agent and a surfactant on the fiber surface and inside the fiber. The solid content of these surface treatment agents on the aramid fibers is preferably in the range of 0.01 to 20% by mass.

  The fiber length and fineness of the heat-resistant short fiber are not particularly limited, and can be appropriately determined depending on the compatibility with the thermoplastic short fiber and the use of the sound absorbing material. The fineness is preferably 0.1 to 50 dtex, and particularly preferably 0.3 to 30 dtex. Although the flame-retardant mechanism in the nonwoven fabric of the present invention is not clear, it is considered that the heat-resistant short fibers entangled with the thermoplastic short fibers have a role of blocking the combustion of the thermoplastic short fibers. Accordingly, the fiber length is not particularly limited, but in view of flame retardancy, productivity, and the like, short fibers having a fiber length of 20 to 100 mm, particularly 40 to 80 mm are preferable.

  The heat-resistant short fibers can be used alone or in admixture of two or more. It is also possible to mix and use fibers of the same kind or different kinds and different in fineness and fiber length. In this case, the mixing ratio of the fibers is arbitrary and can be appropriately determined according to the use and purpose of the sound absorbing material.

  The thermoplastic short fibers and heat-resistant short fibers constituting the nonwoven fabric are preferably blended at a ratio of thermoplastic short fibers / heat-resistant short fibers = 95/5 to 55/45 (mass ratio). When the ratio exceeds 95/5, the flame retardancy of the nonwoven fabric becomes insufficient, and liquid dripping (drip) tends to occur. That is, by containing 5% by mass or more of heat-resistant short fibers in the web and entangled with the thermoplastic short fibers, the thermoplastic short fibers can be prevented from burning and melting. On the other hand, when the ratio is less than 55/45, the flame retardancy is good, but when the nonwoven fabric is processed into a desired size, it becomes difficult to cut, resulting in poor workability and poor economic efficiency. From the viewpoint of flame retardancy and processability, the ratio (mass ratio) of thermoplastic short fibers / heat resistant short fibers is more preferably 88/12 to 65/35, and still more preferably 85/15 to 65/35. It is desirable.

  In the present invention, in order to improve the abrasion resistance and sound absorption characteristics of the nonwoven fabric, it is preferable to contain fine denier thermoplastic short fibers in the thermoplastic short fibers. Examples of the fine denier thermoplastic short fibers include one or more fibers selected from the above-mentioned polyester fibers, polypropylene fibers, polyethylene fibers, linear low density polyethylene fibers, ethylene-vinyl acetate copolymer fibers, and the like. Can do.

  The fine denier thermoplastic short fibers usually have a fineness of 0.1 to 15 dtex, preferably 0.5 to 6.6 detex, particularly 1.1 to 3.3 dtex. If the fineness is too thin, the processability is deteriorated, and if it is too thick, the sound absorption characteristics are deteriorated. Moreover, fiber length is not specifically limited, Although it can determine suitably with compatibility with a heat resistant short fiber, and the use of a sound-absorbing material, Usually, it is preferable that it is a short fiber of 10-100 mm, especially 20-80 mm.

  When blending fine denier fibers in the web, if the amount is too small, the blending effect cannot be obtained. If the amount is too large, the flame retardancy of the nonwoven fabric may be impaired. Preferably it is 10-30 mass%.

In this invention, the fabric weight of a nonwoven fabric is 150-800 g / m < ² >. If the basis weight is too small, the handleability at the time of manufacture is deteriorated. For example, the form retainability of the web layer is poor.

  The web can be manufactured according to a conventional web forming method using a conventional web forming apparatus. For example, the blended thermoplastic short fibers and heat-resistant short fibers are opened using a card machine and then formed on a web.

  The nonwoven fabric preferably used in the present invention is an integral body obtained by interlacing a thermoplastic short fiber or a fiber web obtained by mixing a thermoplastic fiber and a heat-resistant short fiber by a needle punch or a water jet punch by a conventional method. Can be obtained. By performing the punching treatment, the web fibers can be entangled to improve the abrasion resistance of the nonwoven fabric. According to this method, since the webs in the fiber are not chemically bonded to each other, the sound absorbing material after use is collected, washed as necessary, and then easily recycled by simply untangling the entangled fibers. be able to.

The needle punching process may be either single-sided or double-sided web processing. When the punching density is too small, the abrasion resistance of the nonwoven fabric becomes insufficient. When the punching density is too large, the bulk height decreases, and the heat insulation effect and the sound absorption effect are impaired due to the decrease in the air volume ratio in the nonwoven fabric. Times / cm ² , more preferably 50 to 100 times / cm ² .

  In the present invention, needle punching can be performed according to a conventional needle punching method using a needle punching apparatus similar to the conventional one.

Further, the water jet punching process is performed by using a device in which a plurality of injection holes having a hole diameter of 0.05 to 2.0 mm, for example, arranged in a row or a plurality of rows with a hole interval of 0.3 to 10 mm, and a spray pressure of 90 to 250 kg. Using a water jet punching apparatus that injects a high-pressure water flow as / cm ² G, the conventional water jet punching method can be used. The distance between the injection hole and the web is preferably about 1 to 10 cm.

  After needle punching and water jet punching, they may be dried in the same manner as in the prior art and heat set as necessary.

If the short fiber nonwoven fabric has a bulk density that is too small, the flame retardancy, heat insulating properties and sound absorption properties will decrease, and if it is too large, the wear resistance, workability and flame retardancy will decrease. It needs to be in the range of 2 g / cm ³ . Preferably 0.01 to 0.1 g / cm ^3, more preferably 0.02 to 0.08 g / cm ^3, still more preferably in the range of 0.02~0.05g / cm ^3. In this way, by controlling the bulk density of the nonwoven fabric, the ratio of air (oxygen) in the nonwoven fabric is controlled within a certain range, thereby imparting excellent flame retardancy, heat insulating properties, and sound absorption to the nonwoven fabric. The

  In the present invention, the thicker the nonwoven fabric, the better the sound absorption. However, from the viewpoints of economy, ease of handling, securing of space as a sound absorbing material, etc., preferably 2 to 100 mm, more preferably 3 to 50 mm, and still more preferably. Is 5 to 30 mm.

Next, in the easily moldable sound absorbing material of the present invention, a skin material is laminated on at least one surface of the nonwoven fabric. The skin material in the present invention contains a resin binder having a glass transition temperature equal to or lower than the molding temperature and needs to have a bulk density of 0.1 to 0.8 g / cm ³ .

  As the skin material, a wet nonwoven fabric composed of heat-resistant short fibers that are excellent in flame retardancy and capable of obtaining a sound absorbing material having good sound absorbing properties is preferably used. Examples of the wet nonwoven fabric made of short fibers include chopped fiber, paper made of pulp or staple, and felt. Examples of the heat-resistant short fibers include the short fibers described in the description of the non-woven fabric. Among them, the aramid short fibers are preferable because they are excellent in flame retardancy and sound absorption.

  First, the skin material constituting the easily moldable sound-absorbing material of the present invention needs to contain a resin binder having a glass transition temperature equal to or lower than the molding temperature of deep drawing or shallow drawing. By containing a resin binder having a glass transition temperature equal to or lower than the molding temperature, it can be easily adapted to a mold of a molding machine, can be easily molded into a desired shape, and is not cracked during molding. If the glass transition temperature of the resin binder is higher than the molding temperature, a desired shape cannot be obtained, the molded product is cut, and the molded product is wrinkled. In the present invention, molding refers to deep drawing and shallow drawing in the case where the laminated sound absorbing material is formed into a shape corresponding to the usage form of a vehicle interior material, electrical component, or the like. For example, when deep drawing is employed, the mold temperature is usually heated to 200 to 240 ° C. When the mold is heated to 200 ° C., the temperature of the molding material in the mold is heated to 160 to 180 ° C. When the resin binder is softened at this temperature, deep drawing molding becomes easy. Therefore, in this condition, it is preferable that the glass transition temperature of the resin binder is equal to or lower than this temperature. At the mold temperature, the temperature of the resin binder in the mold is about 160 to 220 ° C. More preferably, the glass transition temperature of the resin binder is 20 to 160 ° C. Care must be taken because the glass transition temperature is low, which easily induces contamination.

  In the present invention, examples of the resin binder that can be used include an epoxy resin and an acrylic resin. In general, epoxy resins as binders include polyamines such as diethylenetriamine, triethylenetetramine, dicyandiamide, benzyldimethylamine, and dimer acid-modified polyamide; acid anhydrides such as hexahydrophthalic anhydride and trimellitic anhydride; isocyanate prepolymers, Various curing agents such as isocyanates such as block polyisocyanates; polyphenols; polymercaptans; melamine resins are known, and these curing agents can also be used in the present invention.

  Especially, when using block polyisocyanate as a hardening | curing agent, it is preferable that the compounding mass ratio of an epoxy resin and block polyisocyanate shall be epoxy resin / block polyisocyanate = 10 / 0.5-10 / 5.

  The block polyisocyanate is one in which a part or most of the isocyanate group of the polyisocyanate composition is blocked with a heat dissociable blocking agent, and the isocyanate group is regenerated by heat treatment to advance the curing reaction of the epoxy resin.

  The polyisocyanate composition which is a precursor of block polyisocyanate is obtained by reaction of diisocyanate and polyhydric alcohol. Diisocyanates include aliphatic and alicyclic diisocyanates. For example, hexamethylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate and the like can be mentioned. Examples of the polyhydric alcohol include glycerin, trimethylolpropane, polyether polyols, and polyester polyols. Examples of the dissociable blocking agent include phenols, mercaptans, and imidazoles.

  The resin binder is preferably contained in the skin material in a dry mass of 5 to 40%. The resin binder adheres to the crossing points of the overlapping fibers of the nonwoven fabric and binds the fibers together. When the content of the resin binder is less than 5% by mass, the fibers constituting the nonwoven fabric are not sufficiently settled. On the other hand, when the content exceeds 40% by mass, wrinkles appear in the molded product and the moldability is deteriorated.

  As will be described later, the resin binder is preferably applied to the wet nonwoven fabric in the form of an emulsion by spraying or the like, but can also be dispersed in a papermaking slurry.

Moreover, the skin material in this invention requires that a bulk density is 0.1-0.8 g / cm < ³ >. When the bulk density is less than 0.1 g / cm ^3, it is difficult to produce a wet nonwoven fabric. On the other hand, when the bulk density exceeds 0.8 g / cm ³ , wrinkles are generated in the molded product, which is not preferable. In particular, from the viewpoint of deep drawability, the bulk density is preferably 0.1 to 0.3 g / cm ³ . In addition, this bulk density is a bulk density of the skin material part in the sound-absorbing material in which the skin material is laminated on at least one surface of the nonwoven fabric.

  The thickness of the skin material is arbitrary, but it is preferably 0.01 to 1 mm, more preferably about 0.03 to 0.5 mm, considering the sound absorption characteristics and moldability of the obtained sound absorbing material.

  In the present invention, as a method for producing a wet nonwoven fabric preferably used as a skin material, the heat-resistant short fibers are uniformly dispersed in water to make paper, and the resulting web generally contains the curing agent in the form of an emulsion. The method of apply | coating a resin binder by means, such as a spray, and heating and drying can be mentioned. The fiber length of the short fiber is preferably 1 to 20 mm, the fineness is preferably about 0.1 to 10.0 dtex, and the fiber component concentration in water is preferably about 0.01 to 1.5% by mass. The wet nonwoven fabric after drying can be subjected to heat and pressure treatment using a calender roll, but if the bulk density is higher than the above range, the moldability is impaired. Therefore, this step can be omitted in consideration of the bulk density. .

  Although the non-adhered state may be sufficient as lamination | stacking of a skin material and a nonwoven fabric, what was couple | bonded by the normal coupling | bonding method is preferable. Examples of the bonding method include bonding by general methods such as fusion, stitching, needle punching, water jet punching, bonding with an adhesive, heat embossing, ultrasonic bonding, sinter bonding with an adhesive resin, and bonding with a welder. . Furthermore, it is also possible to employ a method in which a low-melting point material such as a low-melting point net, a low-melting point film, or a low-melting point fiber is interposed between the skin material and the nonwoven fabric and heat-treated to melt the low-melting point material. Here, the melting point of the low melting point material is preferably 20 ° C. or more lower than the melting point of other fibers used for the nonwoven fabric and the skin material.

  As a specific laminating method, the adhesive resin is spread on the nonwoven fabric and passed through an oven heated to about 105 to 150 ° C. to melt or soften the adhesive resin. There is a way to go through.

  The easily moldable sound absorbing material of the present invention may be colored with a dye or a pigment as necessary. As a coloring method, an original yarn obtained by spinning a dye or pigment mixed with a polymer before spinning may be used, or fibers colored by various methods may be used. The sound absorbing material may be colored with a dye or a pigment.

  In addition, in the easily moldable sound absorbing material of the present invention, an acrylic resin emulsion, a phosphate ester flame retardant, a halogen flame retardant, An acrylic resin emulsion or an acrylic resin solution containing a known flame retardant such as a hydrated metal compound may be coated or impregnated. Further, in order to improve the insulating properties, the skin material may contain a layered silicate such as mica such as muscovite, phlogopite, biotite, artificial mica, and the like.

  The easily moldable sound-absorbing material of the present invention is processed into an appropriate size, shape and the like by applying a known method or the like according to the purpose and application. For example, in deep drawing, the mold is heated to 200 to 240 ° C. and molded into a desired shape. At that time, if the resin binder contained in the skin material has a glass transition temperature equal to or lower than the above temperature, the resin binder is melted or softened at the molding temperature, and the bulk density of the skin material is within the scope of the present invention. Then, there is no cut or wrinkle on the surface, so that it can be formed into a desired shape. Further, by heating to the molding temperature, the resin binder penetrates into the short fibers constituting the skin material, the binder resin is cured, and the short fibers are bound to each other.

When the bulk density of the skin material is selected within the range specified by the present invention, and molding is performed by selecting the molding conditions of deep drawing or shallow drawing, the air permeability (based on JIS L-1096) of the skin material portion of the sound absorbing material is 50 cc / cm. ² · sec or less, and a sound absorbing material having excellent sound absorbing characteristics can be obtained.

  The molded sound-absorbing material obtained as described above can be used in various applications where sound-absorbing properties are required. For example, interior materials and walls of vehicles such as automobiles and freight cars, transportation equipment such as ships or aircraft It can be suitably used for civil engineering and building materials such as wood and ceiling materials. In particular, the sound-absorbing material using heat-resistant short fibers as a material is excellent in flame retardancy, and can be used as an interior material in the engine room of an automobile, so that it can prevent burning when ignited from the engine room. Leakage of noise generated from the engine room can be prevented. In addition, automobile ceiling materials, floor materials, rear packages, door trims; insulators in dashboards for automobiles, trains, aircraft, etc .; vacuum cleaners, ventilation fans, electric washing machines, electric refrigerators, freezers, electric clothes dryers, electric mixers Electrical products such as juicers, air conditioners, hair dryers, electric razors, air purifiers, electric dehumidifiers, and electric lawn mowers; speaker diaphragms; civil engineering and construction machinery such as breakers (casing linings, etc.) It can use for various uses, such as.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited only to a following example. In addition, the measuring method and evaluation method of each characteristic value in the following examples and comparative examples are as follows.

[Aeration rate] Measured based on the fragile method of JIS L-1096.

[Sound absorption characteristics]
Using an automatic normal incidence sound absorption rate measuring device (Sotec Co., Ltd.), attach the skin material part to the sound source side, measure the sound absorption rate (%), and create a sound absorption rate curve (frequency on the horizontal axis). Evaluation was performed as follows in a state where the sound absorption rate was lowered on the high frequency side from the frequency range showing the highest value of the rate (%).
○: Within 20% (less decrease in sound absorption rate even in high frequency range)
×: 21% or more

[Formability]
○: No wrinkles or cuts △: Fine wrinkles are scattered in the aperture (wrinkles)
Cracks are scattered around the aperture (cut)
×: Cuts or large wrinkles occur

(Example 1)
Para-aramid fiber “Kevlar (registered trademark)” staples (1.7 dtex × 51 mm) manufactured by Toray DuPont Co., Ltd., polyester staples (1.7 dtex × 44 mm) manufactured by Toray Industries, Inc., polyester staples manufactured by the same company (3.3 dtex) × 51mm) and low melting yarn ("Safmet" (registered trademark), 4.4dtex x 51mm) manufactured by the same company at a mass ratio of 30: 30: 20: 20, with a needle punch method, thickness of 10mm, basis weight A 400 g / m ² Kevlar mixed nonwoven fabric was prepared (bulk density: 0.04 g / cm ³ ).

Meanwhile, para-aramid short fibers (manufactured by DuPont, “Kevlar (registered trademark)” fibers) were dispersed in water to form a slurry. The short fiber used had a fiber diameter of 1.7 dtex and a fiber length of 5 mm. An epoxy resin (manufactured by Dainippon Ink and Chemicals, "EN-002L") and a curing agent (block polyisocyanate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., "BN" -31 ") was mixed at 10: 2 (mass ratio), and a resin binder diluted with water to a concentration of 5% by mass was applied and dried by heating to produce a wet nonwoven fabric. The mass (unit mass, basis weight) per unit area of the obtained wet nonwoven fabric was 55.3 g / m ² . The thickness was 411.5 μm and the bulk density was 0.134 g / cm ³ . The glass transition temperature of the resin binder is 120 ° C.

  After spraying adhesive resin on the surface of the Kevlar mixed nonwoven fabric and heating, a wet nonwoven fabric (skin material) was superposed to obtain a laminated sound absorbing material.

Next, the moldability and sound absorption characteristics of the obtained sound absorbing material were tested. That is, LTD Shinto Metal Industries, Ltd., using single-acting compressor (NS-50), a mold temperature of 200 ° C., pressing time 60 seconds, at a press pressure 0 kg / cm ² square of the plate-like body (40 × 40 cm), and cuts and wrinkles of the molded product were observed. The sound absorption characteristics of the molded sound absorbing material were evaluated, and the air flow rate was measured. As a result, no cuts or wrinkles were observed in the molded product, the sound absorption characteristics were good, and the air flow rate was 35.8 cc / cm ² · sec.

(Example 2)
Polyester staples manufactured by Toray Industries, Inc. (1.7 dtex × 44 mm), polyester staples manufactured by the same company (6.6 dtex × 51 mm) and “Safmet” (4.4 dtex × 51 mm) 60:20:20 (mass ratio) are mixed. A nonwoven fabric having a thickness of 10 mm, a basis weight of 400 g / m ² , and a bulk density of 0.04 g / cm ³ was manufactured by a needle punch method. A sound absorbing material was produced and tested in the same manner as in Example 1 except that the obtained polyester nonwoven fabric was used in place of Kevlar mixed nonwoven fabric, and the unit mass (weight per unit area) of the wet nonwoven fabric was changed as shown in Table 1. The results are shown in Table 1.

(Example 3)
Except for changing the unit mass (weight per unit area) of the wet nonwoven fabric as shown in Table 1, a sound-absorbing material was produced in the same formulation as in Example 1, the moldability and sound-absorbing characteristics were tested, and the air flow rate was measured. The results are shown in Table 1.

Example 4
A sound-absorbing material was produced and tested in the same formulation as in Example 1 except that the composition of the resin binder was changed to an acrylic resin (manufactured by Clariant Polymer Co., Ltd., “Movinyl 767”) to produce a wet nonwoven fabric. The results are shown in Table 1. The glass transition temperature of the resin binder is 30 ° C.

(Examples 5 to 8)
A sound-absorbing material was produced and tested with the same formulation as in Example 1 except that a wet nonwoven fabric was produced by changing the component composition of mass% of para-aramid short fibers and mass% of the resin binder to the composition shown in Table 1. . The results are shown in Table 1.

Example 9
In Example 1, after producing a wet nonwoven fabric, a sound-absorbing material was produced and tested with the same formulation as Example 1 except that it was heated and compressed through a pair of hot rolls having a linear pressure of 200 kg / cm and a temperature of 300 ° C. The results are shown in Table 1.

(Examples 10 to 16)
After manufacturing the wet nonwoven fabric in Examples 2 to 8, the linear density and temperature of the hot roll were adjusted so that the bulk density of the wet nonwoven fabric was 0.65 g / cm ^3. A sound-absorbing material was manufactured according to the prescription and tested. The results are shown in Table 1.

(Examples 17 to 20)
In Example 9, a sound-absorbing material was produced and tested using the same formulation as Example 9 except that the linear pressure and temperature of the hot roll were adjusted so that the wet nonwoven fabric had the bulk density shown in Table 1. The results are shown in Table 1.

(Examples 21 to 22)
In Example 9, the sound absorbing material was formulated in the same manner as in Example 9 except that the wet composition was manufactured by changing the component composition of mass% of para-aramid short fibers and mass% of the resin binder to the composition shown in Table 1. Manufactured and tested. The results are shown in Table 1.

(Comparative Example 1)
A para-aramid short fiber (manufactured by DuPont, "Kevlar (registered trademark)" fiber) and a meta-aramid fiber (manufactured by DuPont, "Nomex (registered trademark)") are dispersed in water, A slurry was obtained. The fiber mass ratio was mixed at a ratio of 90/10. The para-aramid fiber had a fiber diameter of 1.7 dtex and a fiber length of 5 mm. A slurry was made, and a wet nonwoven fabric was obtained with the same formulation as in Example 9 except that the epoxy resin binder was applied so that the ratio of the binder to the para-aramid short fibers was as shown in Table 1. After the hot roll treatment, Kevlar was obtained. A sound-absorbing material was manufactured and tested by laminating with a non-woven fabric. The results are also shown in Table 1.

(Comparative Example 2)
In Comparative Example 1, except that no epoxy resin binder was applied, a wet nonwoven fabric was obtained with the same formulation as Comparative Example 1, and then a sound absorbing material was manufactured and tested. The results are also shown in Table 1.

(Comparative Example 3)
In Example 17, a sound-absorbing material was produced and tested using the same formulation as Example 17 except that the bulk density of the wet nonwoven fabric was changed to 0.9. The results are also shown in Table 1.

Claims (14)

In a sound absorbing material in which a skin material is laminated on at least one surface of an organic fiber nonwoven fabric, the skin material contains a resin binder having a glass transition temperature equal to or lower than a deep drawing or shallow drawing temperature, and a bulk density of 0.1 to 0.1. An easily moldable sound-absorbing material, characterized in that it is 0.8 g / cm ³ . The easily moldable sound-absorbing material according to claim 1, wherein the resin binder is contained in an outer skin material in an amount of 5 to 40% by mass. The easily moldable sound-absorbing material according to claim 1, wherein the molding temperature is in the range of 160 to 220 ° C. The easily moldable sound-absorbing material according to claim 1, wherein the skin material has a thickness of 0.01 to 1 mm. The easily moldable sound-absorbing material according to claim 1, wherein the skin material has a bulk density of 0.1 to 0.3 g / cm ³ . The easily moldable sound-absorbing material according to claim 1, wherein the skin material is a wet nonwoven fabric made of heat-resistant short fibers. The easily moldable sound-absorbing material according to claim 6, wherein the heat-resistant short fibers are aramid short fibers. The organic fiber nonwoven fabric having a basis weight is at 150 to 800 g / ^{m 2,} moldability sound-absorbing material according to claim 1 bulk density of 0.01~0.2g / cm ^3. 2. The organic fiber constituting the organic fiber nonwoven fabric is composed of a thermoplastic short fiber and a heat-resistant short fiber having a LOI value of 25 or more, and the ratio thereof is in the range of 95: 5 to 55:45. The easily moldable sound absorbing material described in 1. The heat-resistant short fiber is selected from aramid fiber, polyphenylene sulfide fiber, polybenzoxazole fiber, polybenzthiazole fiber, polybenzimidazole fiber, polyetheretherketone fiber, polyarylate fiber, polyimide fiber, fluorine fiber and flameproof fiber. The easily moldable sound-absorbing material according to claim 9, which is one or more organic short fibers. The easily moldable sound-absorbing material according to claim 9, wherein the heat-resistant short fibers are para-aramid short fibers. The easily moldable sound-absorbing material according to claim 1, wherein the organic fiber constituting the organic fiber nonwoven fabric is a thermoplastic fiber. The easily moldable sound-absorbing material according to claim 12, wherein the thermoplastic fibers are one or more fibers selected from polyester fibers, polypropylene fibers, and nylon fibers. The easily moldable sound-absorbing material according to claim 1, wherein the organic fiber nonwoven fabric is a nonwoven fabric obtained by performing needle punching or water jet punching on an organic fiber web.