JP6916009B2 - Composite sound absorbing material, its manufacturing method, and method for improving sound absorption - Google Patents

Description

The present invention is a composite sound absorbing material useful for use in vehicles (vehicles such as automobiles and trains, aircraft, ships, etc.), buildings (houses, apartment houses, high-rise buildings, etc.), manufacturing methods thereof, and sound absorbing properties. Regarding how to improve.

Foamed sheets, such as polyurethane and soft vinyl chloride resin foam, are used as sound absorbing materials used in vehicles and buildings, and these foamed sheets can absorb relatively high-frequency sounds well. Are known.

Japanese Unexamined Patent Publication No. 2015-199830 (Patent Document 1) has continuous bubbles having a continuous cell ratio of 50% or more, an apparent density of 600 kg / m ³ or less, and at least one surface of the continuous cells. A polyolefin resin foam sheet having a concavo-convex structure including a top having an opening is described, and it is described that it absorbs sound waves in a relatively high frequency range (for example, 4000 to 6000 Hz). However, the sound absorption coefficient is low for sound waves of medium frequencies (for example, 1500 to 4000 Hz).

Nichias Technology Time Signal No. 326 2001 No. 4 "Foam Rubber Sound Absorption Structure" (Non-Patent Document 1) describes that a rubber-based foam (EPDM, etc.) has excellent sound absorption at medium frequencies (for example, 1500 to 4000 Hz). ing. However, the sound absorption in the high frequency range (for example, 4000 to 6000 Hz) is not described.

Japanese Unexamined Patent Publication No. 2016-161844 (Patent Document 2) describes a sound absorbing material having a low-density layer (EPDM, non-woven fabric) and a high-density layer (metal such as SUS). This sound absorbing material can absorb about 60 to 80% of sound in the low to medium frequency range (for example, 100 to 1600 Hz). However, the sound absorption in the middle to high frequency range (for example, 2000 Hz or higher) is not described.

In Japanese Patent Application Laid-Open No. 2015-174398 (Patent Document 3), a short fiber non-woven fabric containing crimped hollow fibers and a sound absorbing film layer made of a synthetic resin film are laminated, and the thickness of the non-woven fabric is adjusted to less than 12 mm. A composite non-woven fabric for a sound absorbing material, which is excellent in sound absorbing performance and flame retardancy in a frequency range of 3000 to 5000 Hz, is described, for example, by setting the thickness of the sound absorbing film layer to 20 to 60 μm. However, the sound absorption effect in a wide frequency range (frequency range of 3000 Hz or less and 5000 Hz or more) is not described.

Japanese Patent Application Laid-Open No. 2016-186534 (Patent Document 4) describes a ceiling area component used in indoor stadiums, gymnasiums, etc., and the layer structure thereof is a thermoplastic resin layer / fiber cloth layer / thermoplastic resin. The layers are arranged in this order, and for example, a sound absorbing ceiling film that absorbs sound in the frequency range of 250 to 2000 Hz is described. However, the sound absorption in the middle to high frequency range (for example, 2000 Hz or higher) is not described.

Japanese Patent Application Laid-Open No. 2012-25916 (Patent Document 5) provides excellent softness and cushioning properties by forming needle holes shorter than the thickness of the foam in the thickness direction of the foam containing low-density polyethylene or the like. And a sheet-like foam having a large cushioning property is described, and it is also described that this sheet-like foam can be used as a sound absorbing material. This document also describes a flat sheet-like foam and can be used as a sound absorbing material. However, there is no specific description about sound absorption.

In recent years, with respect to sound absorbing materials used for vehicles, buildings and the like, further improvement in sound absorbing properties is desired in a wide frequency range (for example, 1000 to 7000 Hz) without increasing the thickness.

JP-A-2015-199830 (Claims, Effects of Invention, FIG. 2) Japanese Unexamined Patent Publication No. 2016-161844 (Claims, Effects of Invention, Table 1) JP-A-2015-174398 (Claims, Effects of Invention) JP-A-2016-186534 (Claims, Effects of Invention, Paragraph [0026]) Japanese Unexamined Patent Publication No. 2012-25916 (Claims, Industrial Applicability, Effects of Invention)

Nichias Technology Time Signal No. 326 2001 No. 4 "Foam rubber sound absorbing structure" (1. Introduction, Fig. 2)

Therefore, an object of the present invention is to provide a composite sound absorbing material capable of absorbing sound waves in a wide frequency range, a method for producing the same, and a method for improving sound absorbing properties.

Another object of the present invention is to provide a composite sound absorbing material having high sound absorbing property, a method for producing the same, and a method for improving the sound absorbing property.

Another object of the present invention is to provide a composite sound absorbing material capable of improving sound absorption in a wide frequency range even if the structure is simple and the thickness is small, a method for producing the same, and a method for improving sound absorption.

As a result of diligent studies to achieve the above problems, the present inventors, when the non-woven fabric, the plate-shaped resin foam, and the rubber-based foam are laminated or laminated in a predetermined order, generate sound waves in a wide frequency range. The present invention has been completed by finding that the sound absorption property can be effectively improved.

That is, the composite sound absorbing material of the present invention has a non-woven fabric, a plate-shaped resin foam, and a rubber-based foam. In such a composite sound absorbing material, the plate-shaped resin foam and the rubber-based foam have at least open cells, and the non-woven fabric or the plate-shaped resin foam is laminated or laminated on the rubber-based foam. Is formed.

The composite sound absorbing material may be arranged in the order of the non-woven fabric, the plate-shaped resin foam, and the rubber-based foam.

At least one surface of the plate-shaped resin foam forms an uneven surface, has closed cells together with open cells, penetrates halfway from the surface of the plate-shaped resin foam in the thickness direction, and at least a part of the above. It may have a needle hole that penetrates the closed cell.

The plate-shaped resin foam has an uneven surface on at least one surface, and the uneven surface satisfies at least one condition selected from the following (1), (2), (3) and (4). May be good.

(1) The average height difference between the top and the valley on the uneven surface is about 1 to 50 mm (2) The average distance between the tops on the uneven surface is about 1 to 60 mm (3) The uneven surface on the side where the sound wave is incident (4) It has a needle hole at least on the uneven surface.

The depth of the needle hole may be, for example, about 10 to 90% with respect to the entire thickness of the plate-shaped resin foam. The plate-shaped resin foam may contain at least one base component selected from an ethylene-based resin and a thermoplastic elastomer, and the foaming ratio of the plate-shaped resin foam may be about 10 to 100 times. ..

The uneven surface of the plate-shaped resin foam may be a corrugated surface formed by a ridge and a groove adjacent to the ridge. The plate-shaped resin foam may have a punched hole penetrating the plate-shaped resin foam, and the average diameter of the punched hole is larger than the average diameter of the needle hole, for example, about 1 to 20 mm. May be good.

The non-woven fabric may satisfy at least one condition selected from the following (5) and (6).

(5) The basis weight of the non-woven fabric ^{is about 5 to 3500 g / m 2} , and (6) the average density of the non-woven fabric is about ^{0.001 to 0.5 g / cm 3} .

The rubber-based foam may satisfy at least one condition selected from the following (7), (8) and (9).

(7) The average bubble diameter of the rubber-based foam is about 0.01 to 6 mm. (8) The average apparent density of the rubber-based foam is ^{about 0.01 to 0.9 g / cm 3.} (9) Rubber The system foam contains at least ethylene-propylene-diene rubber.

As for the composite sound absorbing material, when the average thickness of the plate-shaped resin foam is 1, the average thickness of the non-woven fabric may be about 0.1 to 5, and the average thickness of the rubber-based foam is about 0.1 to 5. There may be.

The present invention also includes a method of improving sound absorption by injecting sound waves into a composite sound absorbing material. In this method, the non-woven fabric, the plate-shaped resin foam, and the rubber-based foam may be arranged in this order to improve the sound absorption property.

The composite sound absorbing material of the present invention can be produced by a method of laminating or superimposing a non-woven fabric and a plate-shaped resin foam having an open cell structure on a rubber-based foam having an open cell structure. In this method, the non-woven fabric, the plate-shaped resin foam, and the rubber-based foam may be arranged in this order.

In the present invention, by arranging the non-woven fabric, the plate-shaped resin foam having open cells, and the rubber-based foam having open cells in a predetermined order, sound waves can be absorbed in a wide frequency range. Further, by arranging the members in a predetermined order, the sound absorption property can be further improved. Furthermore, with a simple structure, sound absorption can be greatly improved in a wide frequency range even if the overall thickness is small.

FIG. 1 is a schematic view of a plate-shaped resin foam used in the composite sound absorbing material of the present invention. FIG. 2 is a schematic view for explaining a manufacturing process of a plate-shaped resin foam used for the composite sound absorbing material of the present invention. FIG. 3 is a schematic view of the composite sound absorbing material of the present invention. FIG. 4 is a chart showing the sound absorbing characteristics of the composite sound absorbing material of Example 1. FIG. 5 is a chart showing the sound absorbing characteristics of the composite sound absorbing material of Reference Example 1. FIG. 6 is a chart showing the sound absorbing characteristics of the composite sound absorbing material of Reference Example 2. FIG. 7 is a chart showing the sound absorbing characteristics of the composite sound absorbing material of Example 2. FIG. 8 is a chart showing the sound absorbing characteristics of the composite sound absorbing material of Example 3. FIG. 9 is a chart showing the sound absorbing characteristics of the composite sound absorbing material of Example 4. FIG. 10 is a chart showing the sound absorbing characteristics of the composite sound absorbing material of Comparative Example 1.

<Non-woven fabric>
The non-woven fabric is not particularly limited as long as it is a cloth obtained by mechanically, chemically or heat-treating a fiber web and adhering or entwining it. The fibers used for the non-woven fabric may be, for example, glass fibers such as glass wool, silica fibers, alumina fibers, basalt fibers, carbon fibers and other inorganic fibers, polyolefin fibers (polyethylene fiber, polypropylene fiber, etc.), polyester. Fibers (polyethylene terephthalate (PET) fiber, polylactic acid fiber, polyarylate fiber, etc.), polyurethane fiber, semi-synthetic fiber (acetate fiber, triacetate fiber, etc.), acrylic fiber (polyacrylonitrile fiber, polyacrylonitrile-vinyl chloride copolymer fiber, etc.) , Polyamide fiber (6 nylon fiber, 66 nylon fiber, aramid fiber, etc.), polyimide fiber, polyvinyl alcohol fiber (vinylon, polyvinyl alcohol fiber, etc.), recycled fiber (rayon, cupra, etc.), natural fiber (cotton, hemp) , Silk, etc.) may be organic fibers.

These fibers may be used alone or in combination of two or more. The fibers used in the non-woven fabric preferably include organic fibers, and more preferably polyolefin fibers (for example, a combination of polyethylene fibers, polyimide fibers and polyurethane fibers).

The non-woven fabric may be formed of short fibers and / or long fibers, and may be produced by, for example, a spun bond method, a chemical bond method, or a needle punch method. The spunbond method, the chemical bond method, and more preferably the spunbond method are preferable.

The cross-sectional shape of the fiber used for the non-woven fabric is not particularly limited, and for example, a circular shape, an elliptical shape, a T-shape, an H-shape, a V-shape, a dogbone shape (I-shape), a multi-leaf shape, and a polygonal shape. The shape and the like can be mentioned. A preferable cross-sectional shape is a circular shape.

The structure of the fiber may be a single fiber or a composite fiber having two or more components. Further, it may be composed of a mixed fiber of single fibers having different raw material thermoplastic resins or a mixed fiber of a single fiber and a composite fiber. As the composite structure of the composite fiber, for example, a sheath core type, a parallel type, a sea island type and the like can be used, and from the viewpoint of adhesiveness, a sheath core type is preferable. In addition, composite fibers having a modified cross-sectional structure, a split type structure, and a hollow type structure can also be used.

The fineness of the fiber may be, for example, 0.1 to 20 dtex, preferably 0.5 to 18 dtex, and more preferably 1 to 15 dtex. If the fineness of the material is too small or too large, the sound absorption property will be reduced.

The texture of the non-woven fabric may be, for example, about 5 to 3500 g / m ² (for example, 10 to 3000 g / m ² ), preferably about 25 to 2000 g / m ² (for example, 50 to 1500 g / m ² ), for example. , 10 to 1000 g / m ² (for example, 15 to 800 g / m ² ), preferably about 20 to 600 g / m ² (for example, 25 to 500 g / m ² ), for example, 100 to 700 g / m. ² , preferably about 200 to 600 g / m ² , and more preferably about 300 to 500 g / m ^2. If the basis weight of the non-woven fabric is too small or too large, the sound absorption property of the non-woven fabric is lowered.

The average density of the non-woven fabric is, for example, ^{0.001 to 0.5 g / cm 3} , preferably 0.005 to ^{0.3 g / cm 3} , and more preferably 0.01 to 0.25 g / cm ³ (0.02-). It may be about 0.22 g / cm ³ ), for example, about 0.03 to 0.15 g / cm ³ , preferably about 0.05 to 0.1 g / cm ^3. If the average density of the non-woven fabric is too small or too large, the sound absorption property of the non-woven fabric is lowered.

The form of the non-woven fabric is not particularly limited, and may be, for example, a two-dimensional shape, and the thickness is not particularly limited, and is usually a sheet shape. Further, a plurality of sheets (for example, 2 to 20 sheets) of the non-woven fabric may be stacked. The average thickness of the entire non-woven fabric may be, for example, 1 to 50 mm (for example, 2 to 30 mm), preferably 3 to 25 mm (for example, 4 to 20 mm), and more preferably 5 to 15 mm (for example, 6 to 10 mm). good. If the thickness of the non-woven fabric is too small, the fluff of the non-woven fabric will be crushed and the sound absorption coefficient will be extremely lowered.

<Plate-shaped resin foam>
The plate-shaped resin foam can be formed of a foamable thermoplastic resin composition containing a soft thermoplastic resin.

The plate-shaped resin foam may be soft as a whole, and the thermoplastic resin used for the plate-shaped resin foam includes, for example, an olefin resin, a vinyl chloride resin, a vinyl ester resin, and a (meth) acrylic resin. Examples thereof include resins, styrene resins (for example, polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, etc.), thermoplastic elastomers, and the like.

The plate-shaped resin foam usually contains at least one selected from olefin-based resins (particularly ethylene-based resins) and thermoplastic elastomers.

Examples of the olefin resin include ethylene resins (polyethylene, ethylene copolymers, etc.), propylene resins (propylene copolymers such as polypropylene, propylene-ethylene copolymers, etc.), butene resins, and the like. These olefin resins can be used alone or in combination of two or more. Of these olefin-based resins (or soft thermoplastic resins), it is preferable to contain at least an ethylene-based resin.

Among the ethylene-based resins, polyethylene includes high-density polyethylene (HDPE), medium-density polyethylene, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and the like. High-density polyethylene (HDPE) and medium-density polyethylene have the same weight of ethylene and a small amount (for example, 0.01 to 5 mol%, particularly about 0.1 to 3 mol%) of copolymerizable α-olefin. Also includes coalescence. In addition, linear low density polyethylene (LLDPE) is copolymerized with ethylene in a small amount (for example, 0.01 to 10 mol%, preferably 1 to 8 mol%, particularly about 2 to 7 mol%). It also includes copolymers with olefins (α-olefins excluding ethylene). _{Examples of the copolymerizable α-olefin (α-olefin other than ethylene) include α-C 3-} such as propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1, and decene-1. ₁₀ olefins are preferred. These α-olefins can be used alone or in combination of two or more. LLDPE can be prepared using a metallocene catalyst. These polyethylenes may be used alone or in combination.

Among the ethylene-based resins, the ethylene copolymer (ethylene-containing copolymer) is composed of ethylene and a copolymerizable monomer other than ethylene (non-ethylene-based copolymerizable monomer or polar copolymerizable monomer). It may be a copolymer of. Examples of the copolymerizable monomer (or polar copolymerizable monomer) other than ethylene include organic acid vinyl esters such as vinyl acetate, vinyl propionate, and vinyl caproate; propylene, butene-1, and hexene-1. _{Α-C 3-10} olefins such as octene-1, decene-1, and acidic group-containing copolymeric monomers such as (meth) acrylic acid, maleic anhydride, and fumaric acid; methyl (meth) acrylic acid, ( _{(Meta) Acrylic Acid C 1-12} Alkylester, such as Ethyl Acrylic Acid (Meta), Isopropyl (Meta) Acrylic Acid, Butyl (Meta) Acrylic Acid, 2-Ethylhexyl (Meta) Acrylic Acid, Octyl (Meta) Acrylic Acid, ( (Meta) acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth) acrylic acid, 2-hydroxypropyl (meth) acrylic acid, (meth) acrylic acid esters such as (meth) glycidyl ester; vinyl chloride, vinylidene chloride Halogen-containing copolymerizable monomers such as; cyclic olefins and the like can be exemplified. These copolymerizable monomers (or polar copolymerizable monomers) other than ethylene can be used alone or in combination of two or more.

Cyclic olefins include, for example, monocyclic olefins [eg, cycloC _{3-10 alkens such as cyclopentene and cycloheptene, cycloC 3-10} alkazienes such as cyclopentadiene]; bicyclic olefins [eg, norbornenes (eg, norbornenes). , 2-Norbornene, 5-Methyl-2-Norbornene, 5,5- or 5,6-dimethyl-2-Norbornene, 5-Echilidene-2-Norbornene, 5-Cyano-2-Norbornene, 5-methoxycarbonyl-2 -Norbornene, 5-phenyl-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5,6-dimethoxycarbonyl-2-norbornene, 5,6-di (trifluoromethyl) -2-norbornene, _{C 4-20} bicycloalkenes such as 7-oxo-2-norbornene), norbornenes (eg, 2,5-norbornenes corresponding to the above-exemplified norbornenes), etc.], tricyclic olefins [eg, dihydrodi. Cyclopentadiene (dihydrodicyclopentadiene, etc.), dicyclopentadiene (dicyclopentadiene, methyldicyclopentadiene, etc.), tricyclo [4.4.0.1 ^2,5 ] undeca-3,7-diene, tricyclo [ 4.4.0.1 ^2,5 _{] C 6-25} tricycloalkadiene such as undeca-3,8-diene], tetracyclic olefins [eg, tetracyclo [4.4.0.1 ^2,5] .. ^{17 and 10} ] -3-dodecene, 8-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10] -3-like _{C 8-30} tetra cycloalkene such as dodecene, pentacyclic olefins [e.g., penta cycloalkadiene (e.g., _{C 10-35} penta cycloalkadiene such as tricyclopentadiene), etc. ], six cyclic olefins [e.g., hexa cycloalkenes (e.g., hexacyclo ^{[6.6.1.1 3,6 .0 2,7 .0 9,14]} -4- heptadecene _{C 12-40} hexacyclo such Alkene) etc.] and other polycyclic olefins.

These cyclic olefins can be used alone or in combination of two or more. Of these cyclic olefins, polycyclic olefins (particularly bicyclic olefins such as norbornenes) are preferable.

The proportion of ethylene units (ethylene content) of the ethylene copolymer is 50 mol% or more (for example, about 60 to 99 mol%), preferably 65 mol% or more (for example, 65 to 65 mol%) with respect to the entire copolymer. It may be about 98 mol%), more preferably 70 to 97 mol% (for example, about 80 to 95 mol%), or more preferably about 60 to 99 mol% (for example, about 75 to 98 mol%). .. When the ethylene copolymer is a copolymer of ethylene and α-olefin, the ethylene content is in a range different from the ethylene content of the polyethylene (HDPE, LDPE, LLDPE, etc.), for example, 50 to 90 mol% ( For example, it can be selected from the range of about 55 to 87 mol%), preferably about 60 to 85 mol% (for example, 65 to 80 mol%).

Copolymerizable monomers other than ethylene are vinyl acetate, (meth) acrylic acid, (meth) acrylic acid C _1-2 alkyl ester (ethyl acrylate, etc.), and bi- or tricyclic olefins (norbornenes, etc.). There may be. Further, the ethylene copolymer (ethylene-containing copolymer) may be a random copolymer or an alternating copolymer.

Examples of the ethylene copolymer include an ethylene-α-olefin copolymer such as an ethylene-propylene copolymer, an ethylene-organic acid vinyl ester copolymer such as an ethylene-vinyl acetate copolymer, and an ethylene- (meth) acrylic acid. _{Selected from copolymers, ethylene- (meth) acrylate C 1-10} alkyl ester copolymers such as ethylene-ethyl acrylate copolymers, ethylene-cyclic olefin copolymers such as ethylene-norbornene copolymers, etc. At least one can be exemplified, preferably an organic acid vinyl ester copolymer, and more preferably an ethylene-vinyl acetate copolymer (EVA).

The number average molecular weight of the olefin resin (for example, ethylene resin) can be selected from the range of, for example, about 8,000 to 500,000, for example, 10,000 to 300,000, preferably 15,000 to 200, It may be about 000, more preferably about 20,000 to 150,000 (for example, 25,000 to 100,000). The number average molecular weight of the olefin resin can be measured in gel permeation chromatography (GPC method) at a measurement temperature of 140 ° C. using orthodichlorobenzene as a solvent in terms of standard polystyrene.

The melting point of the olefin resin (for example, ethylene resin) may be, for example, about 65 to 170 ° C., preferably 70 to 160 ° C., and more preferably 80 to 150 ° C. (for example, 90 to 120 ° C.). The melting point of polyethylene may be, for example, 90 to 135 ° C., preferably 95 to 132 ° C., and more preferably 100 to 130 ° C. (for example, 105 to 125 ° C.). The melting point of the ethylene copolymer may be, for example, 65 to 150 ° C., preferably 70 to 140 ° C., and more preferably 80 to 130 ° C., depending on the type and content of the α-olefin. .. The glass transition temperature can be used instead of the melting point, and the melting point and the glass transition temperature can be measured by a differential scanning calorimeter.

Under the conditions of a temperature of 190 ° C. and a load of 21.2 N, the melt flow rate of the olefin resin is, for example, 0.05 to 100 g / 10 minutes, preferably 0.08 to 70 g / 10 minutes, more preferably 0.1 to 1. It may be about 50 g / 10 minutes. The melt flow rate of the ethylene resin is, for example, 0.05 to 20 g / 10 minutes (for example, 0.08 to 15 g / 10 minutes) at a temperature of 190 ° C. and a load of 21.2 N, preferably 0.1 to 12. It may be about 5 g / 10 minutes (for example, 0.15 to 12 g / 10 minutes), more preferably about 0.2 to 10 g / 10 minutes (for example, 0.25 to 9 g / 10 minutes).

These olefin resins can be used alone or in combination of two or more. Among these olefin resins, polyethylene [low density polyethylene (LDPE), linear low density polyethylene (LLDPE), etc.] is preferable.

Examples of the thermoplastic elastomer include olefin-based elastomers (block copolymers having polypropylene, polyethylene, etc. as hard segments and ethylene-propylene rubber, ethylene-propylene-diene rubber, etc. as soft segments), styrene-based elastomers (styrene-). Butadiene block copolymer (SBS block copolymer), styrene-isoprene block copolymer (SIS block copolymer), styrene-ethylene / butylene block copolymer (SEBS block copolymer), styrene-ethylene / propylene Block copolymers (SEPS block copolymers, etc.), polyester-based elastomers (aromatic polyesters such as polybutylene terephthalate, etc.) are used as hard segments, and aliphatic polyesters (polyethylene adipate glycol, polybutylene adipate glycol, etc.) or aliphatic polyethers. (Block copolymers having polytetramethylene ether glycol as a soft segment, etc.), polyamide-based elastomers (polypolymers such as nylon 6 and nylon 12 as hard segments, and the aliphatic polyester or aliphatic polyether as soft segments. Block copolymers, etc.), polyurethane-based elastomers, etc. can be exemplified.

Examples of the styrene resin include polystyrene (polystyrene for general use (GPPS), impact resistant polystyrene (HIPS)), styrene-acrylonitrile copolymer (AS resin), acrylonitrile-butadiene-styrene resin (ABS resin), and acrylonitrile-. At least selected from acrylonitrile-styrene copolymer (AAS resin), acrylonitrile-polystyrene chloride-styrene resin (ACS resin), acrylonitrile-ethylene-styrene resin (AES resin), styrene-methyl methacrylate copolymer and the like. One type is mentioned, and these styrene-based resins can be used alone or in combination of two or more types. Polystyrene (polystyrene for general use (GPPS), impact resistant polystyrene (HIPS)) is preferable, and polystyrene for general use (GPPS) is more preferable.

Preferred resin compositions include, for example, at least one base component selected from ethylene resins and thermoplastic elastomers. In particular, it is preferable to contain a base component, an ethylene copolymer, and a styrene resin.

In the foamable thermoplastic resin composition, the ratio of the base component (for example, the low-density polyethylene) to the ethylene copolymer and / or the styrene resin is the former / the latter (weight ratio) = 40/60 to 100 /. It can be selected from a range of about 0 (for example, 50/50 to 100/0), and is usually 55/45 to 98/2, preferably 60/40 to 95/5 (for example, 65/35 to 95/5). More preferably, it may be about 70/30 to 95/5 (for example, 75/25 to 90/10), for example, 50/50 to 80/20, preferably 55/45 to 75/25, and even more preferably. May be about 60/40 to 70/30.

The ratio of the ethylene copolymer to the styrene resin can be selected from the range of the former / the latter (weight ratio) = 0/100 to 100/0 (for example, 10/90 to 90/10), and is usually used. , 20/80 to 80/20, preferably 25/75 to 75/25 (eg, 28/72 to 72/28), more preferably 30/70 to 70/30 (eg, 40/60 to 60/40). ) May be the case.

The foamable thermoplastic resin composition may contain a foaming agent (or foaming aid) and / or a foaming nucleating agent. Examples of the foaming agent include a volatile foaming agent used for physical foaming and a decomposable foaming agent used for chemical foaming. Volatile foaming agents include, for example, inert or non-flammable gases (nitrogen, carbon dioxide, freon, alternative freon, etc.), water, organic physical foaming agents [eg, aliphatic hydrocarbons (propane, butane (n-butane)). , Isobutane), pentane (n-pentane, isopentane, etc.), hexane (n-hexane, etc.), aromatic hydrocarbons (toluene, etc.), halogenated hydrocarbons (trichloromethane, etc.), ethers (dimethyl ether, petroleum ether, etc.) Etc.), ketones (acetone, etc.), etc.]. Examples of the degradable foaming agent include inorganic carbonates such as sodium bicarbonate and ammonium carbonate; organic acids such as citrate or salts thereof (sodium citrate and the like); 2,2'-azobisisobutyronitrile. , Azo compounds such as azodicarboxylic acid amide; sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide; nitroso compounds such as N, N'-dinitrosopentamethylenetetramine (DNPT); azide compounds such as terephthalazide. Of these foaming agents, aliphatic hydrocarbons such as butane and pentane, organic acids such as citric acid, or salts thereof (sodium citrate, etc.) are often used. These foaming agents may be used alone or in combination of two or more.

The ratio of the foaming agent is 0.1 to 40 parts by weight, preferably 0.3 to 35 parts by weight, more preferably 0.5 parts, based on 100 parts by weight of the total amount of the soft thermoplastic resin (or thermoplastic resin). It may be about 30 parts by weight.

Examples of the effervescent nucleating agent include inorganic carbonates such as sodium bicarbonate and ammonium carbonate exemplified in the section of effervescent agents; organic acids such as citric acid or salts thereof (sodium citrate, etc.), and silicic acid compounds (talc). , Silica, zeolite, etc.), metal hydroxides (aluminum hydroxide, etc.), metal oxides (zinc oxide, titanium oxide, alumina, etc.) and the like. These effervescent nucleating agents may be used alone or in combination of two or more. Among the effervescent nucleating agents, in particular, when a silicic acid compound such as talc is used, the bubble structure can be made uniform.

The ratio of the foam nucleating agent is, for example, 0.1 to 10 parts by weight, preferably 0.2 to 8 parts by weight, more preferably 0, based on 100 parts by weight of the total amount of the soft thermoplastic resin (or thermoplastic resin). It may be about 3 to 5 parts by weight.

The effervescent thermoplastic resin composition may contain a shrinkage inhibitor, for example, an ester of a fatty acid and a polyhydric alcohol, a fatty acid amide, and the like. More specifically, as an ester of a fatty acid (for example, lauric acid, myristic acid, palmitic acid, stearic acid, etc.) and a polyhydric alcohol (for example, glycerin, xylitol, sorbitol, mannitol, etc.), for example, palmitic acid mono to Examples thereof include triglyceride, mono-stearic acid to triglyceride. Examples of the fatty acid amide include palmitic acid amide and stearic acid amide. These shrinkage inhibitors may be used alone or in combination of two or more. The ratio of the shrinkage inhibitor is, for example, 0.01 to 30 parts by weight, preferably 0.05 to 20 parts by weight, and more preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the entire soft thermoplastic resin (total resin component). It may be about 15 parts by weight, particularly about 0.5 to 10 parts by weight (for example, 1 to 5 parts by weight). The ratio of the shrinkage inhibitor is, for example, 0.01 to 5 parts by weight, preferably 0.02 to 3 parts by weight, more preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the foaming agent. For example, it may be about 0.1 to 1 part by weight).

Foaming thermoplastic resin compositions are additives such as compatibilizers, bubble conditioners, stabilizers [antioxidants (such as hindered phenolic antioxidants), UV absorbers, heat stabilizers, weather stabilizers. Etc.], Antistatic agents, Antiblocking agents, Antifogging agents, Organic or inorganic fillers (calcium carbonate, carbon fibers, etc.), Colorants (dye, pigment, etc.), Dispersants, Lubricants, Release agents, Lubricants, It may contain impact improvers, plastics, surface smoothers, flame retardants, biosides (bactericides, bacteriostatic agents, antifungal agents, preservatives, insect repellents, etc.), deodorants and the like. These additives may be used alone or in combination of two or more. The ratio of each additive is, for example, 0.1 to 30 parts by weight, preferably 0.15 to 20 parts by weight (for example, 0.15 to 20 parts by weight) with respect to 100 parts by weight of the total amount of the soft thermoplastic resin (or thermoplastic resin). , 0.2 to 15 parts by weight), more preferably about 0.5 to 10 parts by weight.

The foamable thermoplastic resin composition is prepared by preserving each component using a conventional method, for example, a mixer (tumbler, V-type blender, Henschel mixer, Nauta mixer, ribbon mixer, mechanochemical device, extrusion mixer, etc.). It may be mixed. Further, the foaming agent, the foam nucleating agent, the shrinkage inhibitor, and the additive component may be contained in the resin composition (including resin pellets and the like) in advance, and are added or press-fitted into the resin composition in the foam molding process. You may.

The foaming ratio of the plate-shaped resin foam may be, for example, 3 to 120 times (for example, 5 to 110 times), for example, 10 to 100 times (for example, 15 to 95 times), preferably 20 to 90 times. It may be about twice (for example, 25 to 85 times), more preferably about 30 to 80 times (for example, 40 to 75 times). If the foaming ratio is too high, the sound absorption property may be lowered and the strength of the plate-shaped resin foam may be lowered. If the foaming ratio is too low, the sound absorption property may be lowered and the heat insulating property may be lowered. The expansion ratio can be calculated by measuring the apparent density ρf (g / cm ^{3) of the plate-shaped resin foam.}

The apparent density of the plate-like resin foam can be selected according to the expansion ratio, for example, 0.005 to ^{0.05 g / cm 3} , preferably 0.007 to 0.03 g / cm ³ (0.008 to 0. 02 g / cm ³ ), more preferably 0.01 to ^{0.02 g / cm 3} (for example, 0.012 to 0.016 g / cm ³ ), for example 0.005 to 0.04 g / cm. It may be about ^{cm 3} , preferably 0.01 to 0.03 g / cm ³ , and more preferably ^{about 0.01 to 0.025 g / cm 3.} The apparent density can be measured by the underwater substitution method.

The average cell diameter of the plate-shaped resin foam may be, for example, 0.01 to 3 mm, preferably 0.05 to 2 mm, and more preferably 0.1 to 1 mm. If the average diameter of the bubbles in the plate-shaped resin foam is too large, the sound absorption property may be lowered and the strength of the plate-shaped resin foam may be lowered. If the average diameter of the bubbles in the plate-shaped resin foam is too small, the sound absorption property may be lowered and the heat insulating property may be lowered. For the average diameter of the bubbles in the plate-shaped resin foam, the minor axis and the major axis are measured for n bubbles, and the added average of the minor axis and the major axis [(minor axis + major axis) / 2] is calculated. And the average value can be calculated.

The plate-shaped resin foam is not particularly limited as long as it has at least an open cell structure, and the bubble structure may be formed of open cells and / or closed cells, for example, a needle is inserted into the closed cells. It may be an open cell. A skin layer may be formed on the surface of the plate-shaped resin foam. The thickness of the skin layer is not particularly limited as long as it is smaller than the height difference (average height difference) in the thickness direction between the top and valley of the uneven surface, and is usually 1 to 50 μm (for example, 5 to 30 μm). ) May be the case. Since the plate-shaped resin foam has closed cells, it also has heat insulating properties. Therefore, the plate-shaped resin foam can be used not only as a sound absorbing material but also as a soundproofing and heat insulating material in a room or the like.

The plate-shaped resin foam has a single-layer structure composed of one foam layer, may have a bubble structure as a whole, or may have a laminated structure in which a plurality of foam layers are laminated.

Regarding the form of the plate-shaped resin foam, the plate-like shape means a two-dimensional shape, and the thickness is not particularly limited, and may be a small-thickness shape such as a film shape or a sheet shape, for example, a block shape. It may have a large shape such as. The form of the plate-shaped resin foam may be, for example, flat or curved. Further, the thickness of the resin foam may be uniform, may be gradually increased / decreased toward a predetermined direction or portion (for example, a central portion or an intermediate portion), and at least one surface may be an inclined surface or an inclined surface. It may be formed as a curved surface.

The average thickness of the plate-shaped resin foam is 1 to 100 mm (for example, 2 to 50 mm), preferably 3 to 30 mm (for example, 4 to 20 mm), and more preferably 5 to 10 mm (for example, 4 to 20 mm) from the viewpoint of sound absorption and heat insulation. For example, it may be about 6 to 9 mm). If the thickness of the resin foam is too small or too large, the sound absorbing effect and the heat insulating effect may not be sufficiently exhibited.

At least one surface of the plate-shaped resin foam may be formed as an uneven surface (concave and convex portion), and the other surface may be a flat surface (for example, a smooth flat surface) or an uneven surface. ..

An uneven surface (concave and convex portion) is formed on at least one surface of the plate-shaped resin foam. The cross-sectional shape of the concave portion and the convex portion is not particularly limited, and for example, a polygonal shape (triangular shape; U-shaped or rectangular shape, quadrangular shape such as trapezoidal shape, etc.), semicircular shape (including semi-elliptical shape), etc. Examples of the preferred cross-sectional shape of the concave portion and the convex portion include a semicircular shape.

The uneven pattern of the uneven surface is not particularly limited, and the convex portions and concave portions in the concave-convex pattern may be randomly or regularly scattered, or may be adjacent to each other. From the viewpoint of sound absorption, it is preferable that the convex portions and the concave portions are alternately and repeatedly arranged on the uneven surface (concave and convex portions) of the plate-shaped resin foam. Examples thereof include a streak structure formed by adjacent and linearly extending grooves, and a lattice structure formed by intersecting a plurality of linearly extending ridges. A preferable structure of the plate-shaped resin foam is a streak structure, and more preferably a streak structure (corrugated surface) in which the shapes of the convex portion and the concave portion are curved.

The shape of the uneven portion may be minute or fine unevenness, or may be large unevenness (for example, mountain / valley shape or ridge shape). The height difference (average height difference) between the top and the valley in the thickness direction may be, for example, 0.01 to 60 mm (for example, 1 to 55 mm), for example, 3 to 50 mm (for example, 4 to 4 to 5 mm). 45 mm), preferably about 5 to 40 mm (for example, 8 to 35 mm), more preferably about 10 to 30 mm (for example, 12 to 25 mm), for example, 1 to 50 mm, preferably 1.5 to 40 mm. More preferably, it may be about 2 to 35 mm (for example, 2.5 to 25 mm). If the height difference (average height difference) between the valley and the top in the thickness direction is too small or too large, the sound absorbing effect may not be sufficiently exhibited. The difference in height (average height difference) between the valley and the top of the uneven portion in the thickness direction can be calculated by measuring using a three-dimensional surface structure analysis microscope.

On the uneven surface, the average spacing (average pitch) of the convex portions (or tops) may be, for example, 0.1 to 70 mm (for example, 1 to 65 mm), for example, 2 to 60 mm (for example, 5 to 55 mm). ), It may be preferably about 10 to 50 mm (for example, 12 to 45 mm), more preferably about 15 to 40 mm (for example, 20 to 35 mm), for example, 3 to 45 mm, preferably 6 to 40 mm, still more preferably. It may be about 8 to 35 mm. If the distance between the tops is too small or too large, the sound absorbing effect may not be sufficiently exhibited.

In the plate-shaped resin foam, the uneven surface and / or the flat surface may be the incident surface of the sound wave, but the uneven surface is preferably the incident surface of the sound wave. By using a concavo-convex surface having a large surface area as an incident surface, sound absorption is particularly improved in a high frequency region (for example, 5000 to 7000 Hz).

The plate-shaped resin foam has needle holes that penetrate in the thickness direction, and the needle holes may penetrate the plate-shaped resin foam, but they penetrate halfway in the thickness direction and the plate-shaped resin foams. It is preferably smaller than the body thickness. By forming the needle holes, the surface area of the plate-shaped resin foam is increased, the incident sound waves are easily dispersed and absorbed, and the sound absorption in a wide frequency range (for example, 3000 to 7000 Hz) is improved.

The depth of the needle hole is not particularly limited as long as the plate-shaped resin foam has a skin layer, penetrates the skin layer, and further penetrates at least a part of closed cells, and is plate-shaped depending on the application. 10 to 90% (for example, 20 to 80%), preferably 30 to 70% (for example, 35 to 65%), and more preferably 40 to 60% (for example, 45 to 55%) with respect to the total thickness of the resin foam. %). If the depth of the needle hole is too small, the sound absorbing effect may not be sufficiently exhibited, and if the depth of the needle hole is too large, the number of closed cells may be reduced and the heat insulating property and the mechanical strength may be lowered. When the uneven surface of the plate-shaped resin foam has needle holes, the depth of the needle holes can be calculated based on the average position of the top and valley of the uneven surface in the thickness direction.

Further, the needle hole penetrates from the surface of the resin foam, and it is not always necessary to penetrate the needle hole into the convex portion of the concave-convex surface. You may invade from.

The needle hole may enter from either an uneven surface or a flat surface, but it is preferable that the needle hole penetrates from at least an uneven surface. For example, it is preferable to invade from at least one side (for example, uneven surface) of the plate-shaped resin foam, and both sides (for example, one uneven surface and the other flat surface (and /)) of the plate-shaped resin foam or It is more preferable to invade from both surfaces of the uneven surface).

The average diameter of the needle holes may be, for example, 0.1 to 5 mm, preferably 0.2 to 3 mm, and more preferably 0.25 to 1.5 mm (for example, 0.3 to 1.2 mm). ..

The average density of needle holes (pieces / cm ² ) can be selected according to the density of closed cells, for example, 1 to 200 pieces / cm ² (for example, 3 to 150 pieces / cm ² ), preferably 5 to 100 pieces. It may be about / cm ² (for example, 7 to 90 pieces / cm ² ), more preferably 8 to 50 pieces / cm ² (for example, 10 to 40 pieces / cm 2), and for example, 10 to 90 pieces / ^{cm 2.} It ^{may be about cm 2} (for example, 15 to 45 pieces / cm ² ), preferably about 20 to 40 pieces / cm ² (for example, 25 to 35 pieces / cm ² ), for example, 50 to 500 pieces / cm ² (For example, 60 to ^{250 pieces / cm 2} ), preferably about 70 to 150 pieces / cm ² (for example, 80 to 120 pieces / cm ² ). If the density of the needle holes is too small or too large, the sound absorbing effect may not be sufficiently exhibited.

In the plate-shaped resin foam, an open cell layer having an open cell structure (open cell area) is formed on at least one surface side, and a closed cell layer having a closed cell structure (closed cell area) is formed on the other surface side. May be formed. Further, the open cell layer and the closed cell layer may be formed adjacent to each other in the thickness direction of the plate-shaped resin foam. In the open cell layer, for example, a needle can be penetrated into the closed cell layer to pierce (or penetrate) the closed cell wall of the closed cell to form a needle hole.

The thickness ratio between the open cell layer and the closed cell layer can correspond to the depth of the needle hole, and is in the range of the former / the latter = 10/90 to 90/10 (for example, 20/80 to 80/20). The former / the latter = 25/75 to 75/25, preferably 30/70 to 70/30 (for example, 35/65 to 65/35), and more preferably 40/60 to 60/40 (for example). For example, it may be about 45/55 to 55/45). The boundary between the open cell layer and the closed cell layer is a mixture of closed cells and open cells and may not be clear, but it can be calculated as an approximate average thickness ratio by observing the cross section, and the degree of needle penetration can be calculated. The thickness ratio may be calculated based on. The thickness ratio between the open cell layer and the closed cell layer can be calculated based on the average position in the thickness direction of the top and valley of the uneven surface. Further, closed cells may be mixed in the open cell layer.

The plate-shaped resin foam may be formed with punched holes that penetrate the plate-shaped resin foam in the thickness direction. By forming the punched holes, the incident sound waves are easily dispersed, and the sound absorption in a wide frequency range (for example, 3000 to 7000 Hz) is improved.

The average diameter of the punched holes is larger than the average diameter of the needle holes, for example, about 1 to 30 mm (for example, 1.5 to 25 mm), preferably about 2 to 20 mm (for example, 2.5 to 15 mm). It is also good, for example, about 1 to 20 mm (for example, 3 to 12 mm), preferably 3 to 10 mm (for example, 3.5 to 8 mm), and more preferably about 4 to 8 mm (for example, 4.5 to 7.5 mm). There may be. If the average diameter of the punched holes is too small or too large, the sound absorbing effect may not be sufficiently exhibited. The average diameter of the punched holes is the average value obtained by measuring the minor axis and the major axis for n punched holes and calculating the added average [(minor axis + major axis) / 2] of the minor axis and the major axis. Can be sought. The average diameter of the punched holes can be measured using a three-dimensional surface structure analysis microscope.

The average density of the punching holes, for example, 0.1 to 50 pieces / 10 cm ² (e.g., 0.3 to 30 pieces / 10 cm ^2), preferably 0.5 to 20 pieces / 10 cm ² (e.g., 0.7 10 pieces / 10 cm ² ), more preferably 0.8 to 5 pieces / 10 cm ² (for example, 1 to 3 pieces / 10 cm ² ), for example, 1 to 4 pieces / 10 cm ² , preferably 2 pieces. It may be about 3.5 pieces / 10 cm ^2. If the number of punched holes is too small or too large, the sound absorbing effect may not be sufficiently exhibited.

FIG. 1 is a schematic view showing an example of a plate-shaped resin foam. The plate-shaped resin foam 1 is provided with ribs 2 having a corrugated structure in which a top portion 3 and a valley portion 4 are alternately repeated on one surface. Further, only one surface (rib surface) of the plate-shaped resin foam 1 is formed with a large number of needle holes 5 that penetrate to half of the plate-shaped resin foam 1 in the thickness direction. That is, of the plate-shaped resin foam 1, the open cell layer 6 having a continuous cell structure mainly is formed on one surface (rib surface) side on which the needle hole 5 is formed, and the other surface (flat surface) side. A closed cell layer 7 mainly having closed cells is formed. Further, the plate-shaped resin foam 1 is formed with a plurality of punched holes 8 penetrating in the thickness direction.

<Manufacturing method of plate-shaped resin foam>
The plate-shaped resin foam undergoes a foaming step of foaming a foamable resin composition containing a soft thermoplastic resin to form a foam having a closed cell structure, and a drilling step of forming closed cells into open cells. Can be manufactured.

[Foaming process]
A plate-shaped resin foam can be obtained by supplying the resin composition to a melt-kneader in the form of a mixture of each component or in the form of pellets and foam-molding the resin composition. For melt kneading, a conventional melt kneader, for example, a single-screw or bent twin-screw extruder can be used. As the foam molding method, a conventional method, for example, an extrusion molding method (for example, a T-die method, an inflation method, etc.), an injection molding method, or the like can be used. The foam having a concavo-convex shape on at least one surface may be embossed according to the concavo-convex shape. In many cases, the composition is produced by an extrusion foaming method in which the composition is extruded and foamed. The foam molding temperature may be, for example, 70 to 300 ° C., preferably 80 to 280 ° C., and more preferably 85 to 260 ° C.

In the foam having a closed cell structure in which closed cells are mainly formed, the melt extrusion temperature of the resin is determined based on the melting point of the resin component having a content of more than 50% in the resin composition or the glass transition temperature T. It can be prepared by adjusting the temperature within the range of T-20) to (T-5) ° C.

[Drilling process]
In the drilling step, a large number of needles having a length shorter than the thickness of the closed cell structure foam produced in the foaming step are penetrated (or pierced) in the thickness direction of the foam to make the closed cells open cells. This drilling step may be performed after the foam-molded foam has been cooled, but the process of foam-molding (or extruding the foam) and the foam being hot (or fluid or molten state, bubble forming process). , Bubble growth process), the needle is often penetrated (or pierced) into the foam. In particular, the needle is inserted into the foam immediately after or after foaming (for example, within 1 minute after ejection from the mouthpiece), that is, while foam molding (or extruding the foam). Or pierce) in many cases. At that time, the needle may be heated, but in order to efficiently form open cells, it is advantageous to invade (or pierce) the foam in the foaming step (the latter stage of the foaming step) without heating the needle. Is. A preferred method is a method in which a roll (needle roll or pin roll) having a large number of needles (or pins) on the surface is rotated while the needles are inserted (or pierced) in the thickness direction of the foam.

The length of the needle (or pin) can be selected according to the thickness ratio of the open cell layer (first cell layer), and is usually the thickness of the closed cell layer and the open cell layer of the foam when the needle enters. The length corresponds to the ratio. The foam may be compressed to allow the needle to penetrate. Further, the needle may be inserted into the foam multiple times. For example, the foam may be sequentially drilled with a plurality of needle rolls or pin rolls rotatably arranged at intervals in the traveling direction of the foam. The thickness of the needle (or pin) may be, for example, an average diameter of about 0.1 to 5 mm (for example, 0.2 to 3 mm, preferably 0.25 to 1.5 mm). The density of needles (or pins) (books / cm ² ) can be selected according to the density of closed cells, and is usually 1 to 60 needles / cm 2 (for example, ^{2 to} 55 needles / cm 2), preferably ^{2 to 55 needles / cm 2.} It may be about 3 to 50 lines / cm ² (for example, 4 to 45 lines / cm ² ), more preferably 5 to 40 lines / cm ² (for example, 6 to 35 lines / cm ² ), and 1 to 250. It may be about ² lines / cm 2 (for example, 2 to 200 lines / cm ² ), preferably 70 to 150 lines / cm ² (for example, 80 to 120 lines / cm ^2). The needle density (book / cm ^{2 ) is 0.1 to 1 needle / cm 2} (for example, 0.2 to 0.8 needle / cm) per closed cell (closed cell having an average cell diameter). ² , preferably about 0.25 to 0.6 lines / cm ² , and more preferably about 0.3 to 0.5 lines / cm ² ).

The roll diameter of the needle roll (or pin roll) is, for example, about 50 to 250 mmφ (for example, 70 to 200 mmφ, preferably 80 to 170 mmφ), and the pitch of the needle (or pin) is 0.5 to 20 mm (for example, for example). About 0.8 to 15 mm, preferably 1 to 12 mm, more preferably 1.5 to 10 mm, the rotation speed of the roll is 10 to 170 rpm (for example, 25 to 150 rpm, preferably 50 to 130 rpm, still more preferably 75 to 75 to It may be about 125 rpm).

FIG. 2 is a schematic view for explaining a manufacturing process of a plate-shaped resin foam. The resin foam (foam having a closed cell structure) 9 extruded from the mouthpiece of the extruder is guided to the support guide roll 10 while the bubbles are growing, and is placed on the surface of the roll (needle roll) 11 that can rotate on the surface. It is pierced by a large number of needles 12 having a predetermined length formed, and the closed cells on one surface side (surface layer portion) are made into open cells. That is, of the resin foam 9, the closed cell layer 6 having a closed cell structure mainly formed on one surface side in which the needle 12 has penetrated is formed, and the closed cell layer 7 mainly having closed cells is formed on the other surface side. Is forming.

By the above method, a plate-shaped resin foam having needle holes having an open cell layer can be continuously produced. Such a corrugated plate-shaped resin foam can be easily produced, mass-produced, and the production cost can be reduced.

<Rubber foam>
The rubber-based foam (such as a plate-shaped rubber-based foam) can be formed of at least a rubber-based polymer having an open cell structure.

The rubber-based polymer is, for example, an olefin-based elastomer (ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), etc.), a styrene-based elastomer (styrene-butadiene copolymer rubber (SBR), styrene-butadiene block copolymer). Rubber (SBS), styrene-isoprene block copolymer (SIS block copolymer rubber), styrene-ethylene-butylene block copolymer (SEBS block copolymer rubber), etc.), butyl elastomer (butyl rubber, isoprene rubber (IR)) , Isobutylene rubber, etc.), vinyl chloride-based elastomer (polyvinyl chloride (PVC), etc.), butadiene rubber (BR), chloroprene rubber (CR), polyurethane-based rubber, polyamide-based rubber, acrylic rubber, silicone rubber, natural rubber (NR) ), Fluorine rubber and the like are exemplified.

These rubber-based polymers can be used alone or in combination of two or more. Preferred are olefin elastomers, and more preferably ethylene-propylene-diene rubber (EPDM) and ethylene-propylene rubber (EPM).

The rubber-based foam may contain a foaming agent (or foaming aid), a foaming nucleating agent, an anti-shrinkage agent, or an additive, similarly to the plate-shaped resin foam. As the foaming agent (foaming aid, shrinkage inhibitor or additive) used for the rubber-based foam, the same foaming agent as that used for the plate-shaped resin foam can be used. The amount of the foaming agent, foaming nucleating agent, shrinkage inhibitor or additive can be appropriately selected within a range that does not impair the formation of bubbles, and the amount of the foaming agent, the foaming nucleating agent, the shrinkage inhibitor or the additive used for ordinary rubber foams can be adopted.

As a method for forming the bubble structure in the rubber-based foam, it can be formed by the same method as the method for producing the bubble structure of the plate-shaped resin foam. The rubber-based foam may have a skin layer, and usually does not have a skin layer in many cases.

The average apparent density of the rubber foam, for example, 0.01~0.9g / cm ³ (e.g., 0.03~0.7g / ^cm 3), preferably 0.04~0.5g / ^cm 3 ( For example, it may be about 0.05 to 0.3 g / cm ^3). If the density of the rubber-based foam is too small or too large, the sound absorption property of the rubber-based foam is lowered.

The average cell diameter of the rubber-based foam is, for example, 0.01 to 6 mm (for example, 0.05 to 6 mm), preferably 0.1 to 5 mm (for example, 0.2 to 4.5 mm), and more preferably 0. It may be about 3 to 4 mm (for example, 0.5 to 3.5 mm). If the average cell diameter of the rubber-based foam is too small, the sound absorption property is lowered, and if the average cell diameter of the rubber-based foam is too large, the sound absorption property is lowered and the strength of the rubber-based foam is lowered.

The rubber-based foam is not particularly limited as long as it has at least an open cell structure, and the entire rubber-based foam may have an open cell structure, or a closed cell and an open cell may be mixed. good.

The rubber-based foam has a single-layer structure composed of one foam layer, may have a bubble structure over the entire surface, or may have a laminated structure in which a plurality of layers are laminated.

The form of the rubber-based foam is not particularly limited, and may be, for example, a two-dimensional shape, the thickness is not particularly limited, and may be a flat plate. The average thickness of the rubber-based foam is, for example, about 1 to 50 mm (for example, 2 to 25 mm), preferably about 3 to 20 mm (for example, 4 to 18 mm), and more preferably about 5 to 15 mm (for example, 6 to 12 mm). There may be. If the thickness of the rubber-based foam is too small or too large, the sound absorption property of the rubber-based foam is lowered.

When the average thickness of the plate-shaped resin foam is 1, the average thickness of the non-woven fabric and the rubber-based foam is, for example, 0.1 to 5 (for example, 0.2 to 3), preferably 0. It may be about 25 to 2 (for example, 0.3 to 2), more preferably about 0.5 to 1.5 (for example, 0.8 to 1.2).

When the average thickness of the non-woven fabric is 1, the average thickness of the rubber-based foam is, for example, 0.1 to 10 (for example, 0.2 to 5), preferably 0.5 to 2 (for example, 0. 7 to 1.5), more preferably about 0.8 to 1.2 (for example, 0.9 to 1.1).

The composite sound absorbing material (soundproofing material or sound deadening material) of the present invention can be formed by laminating or layering a non-woven fabric, a plate-shaped resin foam, and a rubber-based foam in a predetermined order.

The average thickness of the composite sound absorbing material is not particularly limited and can be selected according to the application, and may be, for example, about 5 to 100 mm (for example, 10 to 100 mm), preferably about 15 to 75 mm (for example, 25 to 60 mm). It may be about 15 to 50 mm (for example, 20 to 40 mm), more preferably about 25 to 35 mm (for example, 25 to 30 mm).

<Laminate structure and sound absorption characteristics of composite sound absorbing material>
Based on the vertical incident method according to JIS A 1405, the composite sound absorbing material exhibits the following sound absorbing characteristics when measured in the frequency range of 0 to 6500 Hz using a thin tube.

In the composite sound absorbing material, when the rubber-based foam is arranged on the most upstream side with respect to the incident direction of the sound wave, the sound-absorbing effect of the non-woven fabric and the plate-shaped resin foam disappears, and the sound-absorbing effect of the rubber-based foam is strongly exhibited. Alternatively, although the sound absorption coefficient shows a high peak in the frequency range of 800 to 1500 Hz, the sound absorption property in other frequency ranges cannot be improved. The sound absorption characteristics of such a rubber-based foam (particularly, the peak of the sound absorption coefficient in the frequency range) are exhibited regardless of the laminated structure of the composite sound absorbing material, even if the peak shifts to the high frequency side. Seems to do.

More specifically, for example, when a rubber-based foam, a non-woven fabric, and a plate-shaped resin foam are arranged in this order from the incident surface side of the sound wave and the sound wave is incident, the sound absorption coefficient rises sharply from, for example, around 500 Hz. It peaks in the vicinity of 800 to 1500 Hz, for example, about 0.85 to 1 (for example, 0.9 to 1), and then when the frequency increases, the sound absorption coefficient suddenly increases to the vicinity of 2500 Hz, 0.3 to 0. It decreases to about .5 (for example, 0.35 to 0.45), gradually increases when it exceeds around 2500 to 3000 Hz, and increases, for example, when it exceeds around 5500 Hz, for example, 0.45 to 0.65 (for example, 0). .5-0.6) is often maintained. Therefore, if the rubber-based foam is located on the most upstream side of the sound wave, the sound absorption in the frequency region of 1500 Hz or higher cannot be improved.

Therefore, in the present invention, the rubber-based foam is arranged on the downstream side with respect to the incident direction of the sound wave, and the non-woven fabric or the plate-shaped resin foam is arranged on the most upstream side. That is, the composite sound absorbing material of the present invention has a mode in which the rubber-based foam is arranged in the middle of the composite sound absorbing material (aspect A), and a mode in which the rubber-based foam is arranged most downstream with respect to the incident direction of sound waves (aspect). B) is included. Such a composite sound absorbing material can absorb sound waves in a wide frequency range and can improve the sound absorbing coefficient. The uneven surface (recess) of the plate-shaped resin foam and the adjacent member (for example, non-woven fabric) may be in close contact with each other, and a gap may be formed between the two members.

More specifically, in the aspect A, the sound absorption frequency range can be expanded to 1500 Hz or higher (for example, 1500 to 6500 Hz), and the sound absorption coefficient can be improved. For example, in the embodiment in which the plate-shaped resin foam is arranged on the most upstream side with respect to the incident surface direction of the sound wave (Aspect A-1), the sound absorption coefficient peaks in the frequency range 3000 to 4500 Hz (for example, the peak height is 0.75). (Sound absorption coefficient of about 1) can be shown, and sound absorption in a frequency range higher than 4500 Hz can be improved. On the other hand, in the embodiment in which the non-woven fabric is arranged on the most upstream side with respect to the incident surface direction of the sound wave (Aspect A-2), high sound absorption is exhibited even at a frequency of 1500 Hz, and as the frequency increases from a predetermined frequency of 2000 to 2500 Hz, In many cases, the sound absorption coefficient is also improved (for example, improved from 0.55 to 0.75 to about 0.75 to 1). In the aspect A-1, the sound absorption in the frequency range of about 1500 to 2500 Hz and the sound absorption in the high frequency range (for example, the frequency range of 5500 Hz or more) may not be sufficient. Further, in the aspect A-2, the sound absorption property may decrease in the frequency range of about 1800 to 2500 Hz. Therefore, the laminated form of the composite sound absorbing material can be selected from either A-1 or A-2 depending on the application.

In the aspect A-1, the uneven surface of the plate-shaped resin foam may be arranged toward the rubber-based foam, but in many cases, it is arranged toward the outside. Further, in the aspect A-2, the uneven surface of the plate-shaped resin foam may be arranged toward the outside, but in many cases, it is arranged toward the rubber-based foam.

More specifically, in the aspect A-1, the sound absorption coefficient of the composite sound absorbing material rises from, for example, around 2000 Hz and peaks around 3000 to 4000 Hz (for example, 0.75 to 1, preferably 0.8 to 1). , More preferably a peak of about 0.85 to 0.95), after which, as the frequency increases, the sound absorption coefficient of the composite sound absorbing material gradually decreases, and at around 5500 to 6500 Hz, for example, It may be about 0.55 to 0.75 (for example, 0.6 to 0.7).

On the other hand, the sound absorption coefficient of the composite sound absorbing material of the aspect A-2 decreases to about 0.55 to 0.75 (for example, 0.6 to 0.7) in the vicinity of 2000 to 2500 Hz, and exceeds around 2500 Hz. As the frequency increases, the frequency gradually increases, and in the vicinity of 5000 to 6500 Hz, for example, it gradually improves to about 0.75 to 1, preferably 0.8 to 1, and more preferably about 0.85 to 0.95. May be done.

In the aspect B, the sound absorption characteristic in the low frequency range of the sound absorption property can be improved and complemented in the aspect A, and the sound absorption coefficient can be further greatly improved in the wide frequency range (for example, 1500 to 6500 Hz) as compared with the aspect A. For example, in the embodiment in which the plate-shaped resin foam is arranged in the uppermost stream with respect to the incident surface side of the sound wave (aspect B-1), the frequency range in which the sound absorption coefficient is low (for example, 1500 to 2500 Hz and 5500 Hz) in the aspect A-1. The sound absorption coefficient in the above frequency range) can also be improved, and in many cases, the sound absorption coefficient in the frequency range where the sound absorption coefficient is low (for example, about 1800 to 2500 Hz) can be greatly improved in the above aspect A-2. On the other hand, in the embodiment in which the non-woven fabric is arranged in the most upstream direction with respect to the incident surface side of the sound wave (Aspect B-2), the frequency region having a low sound absorption coefficient in the Aspect A while exhibiting the same sound absorption characteristics as the Aspect B-1 (Aspect B-2). For example, the sound absorption property at 1500 to 2500 Hz) can be greatly improved and complemented, and the sound absorption characteristic may be higher than that of the aspect B-1. Therefore, the composite sound absorbing material in the laminated form of the aspect B-1 or the aspect B-2 (particularly, the aspect B-2) can greatly improve the high sound absorption coefficient in a wide frequency range.

In the aspect B-1, the uneven surface of the plate-shaped resin foam may be arranged toward the non-woven fabric, but in many cases, it is arranged toward the outside. Further, in the aspect B-2, the uneven surface of the plate-shaped resin foam may be arranged toward the rubber-based foam, but in many cases, it is arranged toward the non-woven fabric.

More specifically, the sound absorption coefficient of the composite sound absorbing material of the aspect B-1 is at a high level (for example, 0.65 to 0.95, preferably 0.7 to 0.) Even in the frequency range of about 1500 to 3000 Hz, for example. 9. While maintaining a sound absorption coefficient of about 0.75 to 0.85, even in a high frequency range (for example, 3500 Hz or higher), a high level (for example, 0.8 to 1, preferably 0.85 to 0.85) is maintained. 1. More preferably, the sound absorption coefficient (sound absorption coefficient of about 0.9 to 1) is often maintained.

In particular, the sound absorption coefficient of the composite sound absorbing material of the aspect B-2 shows almost the same behavior as that of the aspect B-1, but is even higher level (for example, 0.7 to 1, preferably 0.7 to 1) even in the frequency range of about 1500 to 3000 Hz. While maintaining a sound absorption coefficient of 0.75 to 0.95, more preferably about 0.8 to 0.9), in a high frequency range (for example, 3500 Hz or higher), a high sound absorption level of 0.9 or higher is achieved. Can be maintained.

In the aspect A or the aspect B, any surface (for example, a flat surface or an uneven surface) of the plate-shaped resin foam may be arranged toward the incident side of the sound wave, and the plate-shaped resin foam may be flat. Compared to arranging the surface toward the incident side of the sound wave, when the uneven surface of the plate-shaped resin foam is positioned toward the incident side of the sound wave, the frequency range is about 0.75-1 in the frequency range of 3500 to 6500 Hz. In some cases, the existing sound absorption coefficient can be improved to about 0.8 to 1.

Further, in the aspect A or the aspect B, both one side (for example, uneven surface) or both sides (for example, one uneven surface and the other flat surface (and /) or uneven surface) of the plate-shaped resin foam. A sound wave may be incident from a surface (needle hole forming surface) in which a needle hole is formed and a needle hole is formed. In such an embodiment, the sound absorption coefficient in the frequency range of 1500 Hz or higher can be improved. When a needle hole is formed on one surface (for example, an uneven surface) of the plate-shaped resin foam and sound waves are incident from the needle hole forming surface, for example, sound absorption is about 0.75 to 1 in the frequency range of 3500 to 6500 Hz. In some cases, the rate can be improved to about 0.8 to 1. Further, when needle holes are formed on both sides of the plate-shaped resin foam (for example, both the uneven surface of one surface and the flat surface or the uneven surface of the other surface), for example, 0.7 to 0.7 in the frequency range of 1500 to 3000 Hz. In some cases, the sound absorption coefficient, which was about 0.99, can be further improved to about 0.75 to 1.

Further, in the aspect A or the aspect B, a punching hole may be formed in the plate-shaped resin foam to inject sound waves. In such an embodiment, for example, in the frequency range of 1500 to 3000 Hz, the sound absorption coefficient, which was about 0.65 to 0.95, may be improved to about 0.7 to 1.

From these facts, the composite sound absorbing material can improve the sound absorbing property at a high level in a wide frequency range (for example, 1000 to 6500 Hz) by arranging the rubber-based foam most downstream with respect to the incident direction of the sound wave. In particular, the sound absorption is improved by arranging the non-woven fabric in the uppermost stream.

Further, by injecting sound waves from the uneven surface of the plate-shaped resin foam, forming needle holes on one or both sides of the plate-shaped resin foam, and forming punch holes in the plate-shaped resin foam, the sound waves are further further formed. Sound absorption can be improved.

FIG. 3 is a schematic view showing an example of the composite sound absorbing material of the present invention. In this example, the composite sound absorbing material 13 is arranged in layers in the order of the non-woven fabric 14, the plate-shaped resin foam 1, and the rubber-based foam 15. Further, at least one surface of the plate-shaped resin foam 1 is formed as an uneven surface, and the uneven surface is arranged as an incident surface of sound waves. Further, a needle hole 5 is formed on the uneven surface, and a punched hole (not shown) penetrating the plate-shaped resin foam 1 is formed.

In the present invention, the non-woven fabric, the plate-shaped resin foam, and the rubber-based foam may be provided, and the non-woven fabric other than the non-woven fabric and / Alternatively, a woven fabric (for example, a non-woven fabric of fibers such as organic fibers and inorganic fibers such as glass and / or a woven fabric), a porous material (for example, a soft resin such as a urethane resin or an olefin resin; Foam; resin foam other than the plate-shaped resin foam, etc.), sheet and / or thin film (for example, metal such as aluminum, plastic, etc.), net or mesh (for example, net such as fiber or foam), etc. May be laminated.

<Manufacturing method of composite sound absorbing material>
As described above, the composite sound absorbing material of the present invention can be produced by laminating or layering a non-woven fabric or a plate-shaped resin foam on a rubber-based foam, and the composite sound absorbing material is a non-woven fabric, a plate-shaped resin foam, or the like. The rubber-based foam may be arranged in this order. The members do not necessarily have to be joined to each other, and can be installed according to the application location and its shape, and the members may be joined or joined to each other, for example, double-sided tape, an adhesive, etc. It may be sutured and fastened. Even if they are bonded and joined, they do not seem to affect the sound absorption of the composite sound absorbing material.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

For the sound absorption coefficient, the vertically incident sound absorption coefficient based on JIS A 1405 was measured. The sound absorption coefficient was measured with a vertical incident transmission loss measurement unit (transmission loss tube kit, Type 4206-T (manufactured by Bruel Care Co., Ltd.)) in a frequency range from 0 Hz to 6500 Hz using a thin tube.

The following non-woven fabrics, plate-shaped resin foams and rubber-based foams were used.

(A) Non-woven fabric A non-woven fabric made of polyolefin fiber having a fineness of 6.66 dtex, having a grain size of 400 g / m ² , a density of 0.08 g / cm ^3, and an average thickness of 4 mm, which are laminated (thickness 8 mm).

(B) Plate-shaped resin foam Polyolefin foam (manufactured by DM Novafoam Co., Ltd.) was used. This foam has an average thickness of 8 cm, a foaming magnification of 40 times, and an apparent density of 0.021 g / cm ³ . It has a rib surface (curved uneven surface; pitch 10 mm, height 3 mm) on one surface, needle ^{holes (needle hole density 12 pieces / cm 2} ) are formed only on the rib surface, and punched holes (average diameter: 5 mmΦ). , Average density: 1.5 pieces / 10 cm ² ).

In addition, the plate-shaped resin foam is produced by extruding the foamable resin composition into a sheet shape from a mouthpiece in which one of the inner walls facing each other is formed in an uneven shape, according to Example 7 of Patent Document 5. It was prepared according to the same procedure. The foamable resin composition contains 65 parts of polyethylene, 20 parts of polystyrene, 15 parts of an ethylene-vinyl acetate copolymer, 2 parts of talc and 12.5 parts of a foam.

(C) The rubber-based foam EPDM has an apparent density of 0.196 g / cm ³ and a thickness of 8 mm, and no skin layer is formed.

Example 1
A composite sound absorbing material was obtained by stacking a non-woven fabric, a plate-shaped resin foam, and a rubber-based foam in the following order and adhering each of them with double-sided tape. The plate-shaped resin foam was arranged with the rib surface (concave and convex surface) facing the non-woven fabric side. The thickness of the obtained composite sound absorbing material was 28 mm (measured with a thickness gauge). Sound waves were incident on the obtained composite sound absorbing material from the non-woven fabric side, and the sound absorbing coefficient was measured. The results are shown in FIG.

(A) Non-woven fabric / (B) Plate-shaped resin foam / (C) Rubber-based foam
As is clear from FIG. 4, in Example 1, the sound absorption coefficient sharply increases up to around 1500 Hz (sound absorption coefficient 0.8 to 0.9), and above 3000 Hz, the sound absorption coefficient is a relatively high and stable value. (Sound absorption rate 0.9 to 1) was shown.

Reference example 1
A composite sound absorbing material was obtained from the incident surface of the sound wave by the same method as in Example 1 except that the sound waves were overlapped in the following order. The rib surface of the plate-shaped resin foam was arranged toward the rubber-based foam.

(A) Non-woven fabric / (C) Rubber-based foam / (B) Plate-like resin foam The thickness of the obtained composite sound absorbing material was 28.6 mm (measured with a thickness gauge). Sound waves were incident on the obtained composite sound absorbing material from the non-woven fabric side, and the sound absorbing coefficient was measured. The results are shown in FIG.

As is clear from FIG. 5, in Reference Example 1 , the sound absorption coefficient rapidly increased to around 1000 Hz and peaked at around 1200 Hz (sound absorption coefficient 0.8 to 0.9). After that, it gradually decreases to around 2500 Hz (sound absorption coefficient from 0.6 to 0.7), gradually increases when it exceeds 2500 Hz, and relatively high and stable value when it exceeds 4500 Hz (sound absorption coefficient 0). 9.9 to 1) are shown.

Reference example 2
A composite sound absorbing material was obtained from the incident surface of the sound wave by the same method as in Example 1 except that the sound waves were overlapped in the following order. The plate-shaped resin foam was arranged with the rib surface facing outward.

(B) Plate-shaped resin foam / (C) Rubber-based foam / (A) Non-woven fabric The thickness of the obtained composite sound absorbing material was 28.6 mm (measured with a thickness gauge). Sound waves were incident on the obtained composite sound absorbing material from the plate-shaped resin foam side, and the sound absorbing coefficient was measured. The results are shown in FIG.

As is clear from FIG. 6, in Reference Example 2 , after the sound absorption coefficient changed from around 0.5 to 0.8 at 500 to 2000 Hz, the sound absorption coefficient increased from around 0.5 at around 2000 Hz and peaked at around 3500 Hz. (Sound absorption coefficient 0.8 to 0.9), then gradually decreased, and when the frequency exceeded 6000 Hz, the sound absorption coefficient decreased to around 0.7.

Example 2
(B) As the plate-shaped resin foam, a composite sound absorbing material is used in the same manner as in Example 1 except that needle holes are formed on both sides (rib surface and flat surface) of the polyolefin foam (manufactured by DM Novafoam). The plate-shaped resin foam was arranged with the rib surface facing the non-woven fabric side.

The thickness of the obtained composite sound absorbing material was 28 mm (measured with a thickness gauge). Sound waves were incident on the obtained composite sound absorbing material from the non-woven fabric side, and the sound absorbing coefficient was measured. The results are shown in FIG.

As is clear from FIG. 7, in Example 2 , the sound absorption coefficient rapidly rises to around 1500 Hz (sound absorption coefficient 0.85 to 0.9), and above 3000 Hz, the sound absorption coefficient is a relatively high and stable value. (Sound absorption rate 0.9 to 1) was shown.

Example 3
A composite sound absorbing material was obtained in the same manner as in Example 1 except that the plate-shaped resin foam was prepared so that the incident surface direction of sound waves was a flat surface. The plate-shaped resin foam was arranged with the rib surface facing the non-woven fabric side.

The thickness of the obtained composite sound absorbing material was 28 mm (measured with a thickness gauge). Sound waves were incident on the obtained composite sound absorbing material from the non-woven fabric side, and the sound absorbing coefficient was measured. The results are shown in FIG.

As is clear from FIG. 8, in Example 3 , the sound absorption coefficient sharply increases up to around 1500 Hz (sound absorption coefficient 0.80 to 0.9), and above 3000 Hz, the sound absorption coefficient is a relatively high and stable value. (Sound absorption rate 0.9 to 1) was shown.

Example 4
A composite sound absorbing material was obtained in the same manner as in Example 1 except that no punching holes were formed in the plate-shaped resin foam. The plate-shaped resin foam was arranged with the rib surface facing the non-woven fabric side.

The thickness of the obtained composite sound absorbing material was 28 mm (measured with a thickness gauge). Sound waves were incident on the obtained composite sound absorbing material from the non-woven fabric side, and the sound absorbing coefficient was measured. The results are shown in FIG.

As is clear from FIG. 9, in Example 4 , the sound absorption coefficient sharply increases up to around 1500 Hz (sound absorption coefficient 0.75 to 0.9), and above 3000 Hz, the sound absorption coefficient is a relatively high and stable value. (Sound absorption rate 0.85-1) was shown.

Comparative Example 1
A composite sound absorbing material was obtained from the incident surface of the sound wave by the same method as in Example 1 except that the sound waves were overlapped in the following order. The plate-shaped resin foam was arranged with the rib surface facing the non-woven fabric side.

(C) Rubber-based foam / (A) Non-woven fabric / (B) Plate-shaped resin foam The thickness of the obtained composite sound absorbing material was 28.6 mm (measured with a thickness gauge). Sound waves were incident on the obtained composite sound absorbing material from the rubber-based foam side, and the sound absorbing coefficient was measured. The results are shown in FIG.

As is clear from FIG. 10, in Comparative Example 1, it rapidly rises from 500 Hz, shows a peak near 1000 Hz (sound absorption coefficient 0.9 to 1.0), and then sharply decreases to around 2500 Hz (sound absorption coefficient). (From 0.4 to 0.5), the sound absorption coefficient gradually increased above 2500 Hz, and showed a sound absorption coefficient of 0.5 to 0.6 around 6000 Hz.

Comparing the above test results from the above results, in Examples 1 to 4 and Reference Examples 1 and 2 (FIGS. 4 to 9), the non-woven fabric, the plate-shaped resin foam, and the rubber-based foam are formed from the direction in which the sound waves are incident. The sound absorbing materials arranged in this order obtained an excellent sound absorbing effect in a wide frequency range, and in particular, in Example 2 (FIG. 7), the most excellent sound absorbing effect was obtained.

On the other hand, in Comparative Example 1 (FIG. 10), the sound absorbing material produced by arranging the rubber-based foam, the non-woven fabric, and the plate-shaped resin foam in this order from the direction in which the sound waves are incident has high sound absorption at around 1000 Hz. Although it shows the rate, the result was that the sound absorption effect was not sufficiently obtained in other frequency ranges.

The composite sound absorbing material of the present invention is a composite sound absorbing material having a non-woven fabric, a plate-shaped resin foam, and a rubber-based foam, and the plate-shaped resin foam and the rubber-based foam have at least open cells. Since the non-woven fabric or the plate-shaped resin foam is laminated on the rubber-based foam, it has high sound absorption in a wide frequency range of medium to high frequency range (for example, 1000 to 7000 Hz). The material can be obtained. Therefore, the present invention relates to vehicles (vehicles such as automobiles and trains, aircraft, ships, etc.), buildings (houses, apartment buildings, condominiums, factories, libraries, hospitals, school buildings, gymnasiums, auditoriums, movie theaters, concert venues, etc. For parking lots, high-rise buildings such as buildings), electrical appliances (toys, home appliances, etc.), industrial machinery (construction machinery, agricultural machinery, etc.), piping (exhaust pipes, air supply pipes, drain pipes, water absorption pipes, etc.) It is useful as a sound absorbing material and a sound absorbing heat insulating material to be used. It can be used for the bodies of automobiles and trains, which require particularly sound absorption, and for the walls, floors, and ceilings of buildings.

1 ... Plate-shaped resin foam 2 ... Ribs 3 ... Top (convex)
4 ... Valley (concave)
5 ... Needle hole 6 ... Open cell layer 7 ... Closed cell layer 8 ... Punched hole 9 ... Resin foam 10 ... Support guide roll 11 ... Roll 12 ... Needle 13 ... Composite sound absorbing material 14 ... Nonwoven fabric 15 ... Rubber foam

Claims (13)

A composite sound absorbing material having a non-woven fabric, a plate-shaped resin foam, and a rubber-based foam.
The plate-shaped resin foam and the rubber-based foam have at least open cells.
A composite sound absorbing material in which the non-woven fabric, the plate-shaped resin foam, and the rubber-based foam are arranged or laminated in this order with respect to the incident direction of sound waves. The plate-shaped resin foam forms an uneven surface on at least one surface and has closed cells as well as open cells.
The plate from the surface of the resin foam to the middle of the thickness direction invaded, and composite sound absorbing material according to claim 1 Symbol mounting having a needle hole penetrating at least a portion of said closed cell. A claim in which the plate-shaped resin foam has an uneven surface on at least one surface, and the uneven surface satisfies at least one condition selected from the following (1), (2), (3) and (4). Item 2. The composite sound absorbing material according to Item 1 or 2.
(1) The average height difference between the top and the valley on the uneven surface is 1 to 50 mm (2) The average distance between the tops on the uneven surface is 1 to 60 mm (3) The uneven surface is provided on the side where the sound wave is incident. (4) Have needle holes at least on the uneven surface The composite sound absorbing material according to claim 2 or 3 , wherein the depth of the needle hole is 10 to 90% with respect to the total thickness of the plate-shaped resin foam. Any of claims 1 to 4 , wherein the plate-shaped resin foam contains at least one base component selected from an ethylene-based resin and a thermoplastic elastomer, and the foaming ratio of the plate-shaped resin foam is 10 to 120 times. The composite sound absorbing material described in. The composite sound absorbing material according to any one of claims 2 to 5 , wherein the uneven surface is a corrugated surface formed by a ridge and a groove adjacent to the ridge. The composite sound absorbing material according to any one of claims 2 to 6 , wherein the plate-shaped resin foam has a foaming ratio of 25 to 120 times, and needle holes penetrate over the entire uneven surface. The composite sound absorbing material according to any one of claims 1 to 7 , which has a punched hole penetrating the plate-shaped resin foam. The composite sound absorbing material according to claim 8 , wherein the average diameter of the punched holes is larger than the average diameter of the needle holes, and is 1 to 20 mm. The composite sound absorbing material according to any one of claims 1 to 9 , which satisfies at least one condition selected from the following (5), (6), (7), (8) and (9).
(5) The texture of the non-woven fabric is 5 to 3500 g / m ² , (6) the average density of the non-woven fabric ^{is 0.001 to 0.5 g / cm 3} , and (7) the average cell diameter of the rubber-based foam is 0. 01 to 6 mm (8) The average apparent density of the rubber-based foam is 0.01 to 0.9 g / cm ³ (9) The rubber-based foam contains at least ethylene-propylene-diene rubber. According to any one of claims 1 to 10 , when the average thickness of the plate-shaped resin foam is 1, the average thickness of the non-woven fabric is 0.1 to 5 and the average thickness of the rubber-based foam is 0.1 to 5. The composite sound absorbing material described. The method for improving the sound absorbing property of the composite sound absorbing material according to any one of claims 1 to 11 , wherein sound waves are incident from the non-woven fabric side of the composite sound absorbing material to improve the sound absorbing property. The method for producing a composite sound absorbing material according to any one of claims 1 to 11 by arranging or laminating a non-woven fabric, a plate-shaped resin foam having an open cell structure, and a rubber foam having an open cell structure in this order.

Images