JP2023059345A - Non-woven fabric face material and laminated sound absorber - Google Patents

Abstract

To provide a non-woven fabric face material capable of obtaining a laminated sound absorber indicating an excellent sound absorption characteristic.SOLUTION: In a non-woven fabric face material including 20 to 100 wt.% of thermoadhesive composite fiber, a basis weight of the non-woven fabric face material is 1 to 100 g/m2, a thickness is 0.01 to 0.15 mm and a maximum pore diameter/minimum pore diameter is 3.5 or more.SELECTED DRAWING: None

Description

The present invention relates to a nonwoven face material and a laminated sound absorbing material.

Sound absorbing materials made of fibers are used in automobile ceiling materials, door panels, floor mats, bonnets, luggage compartments, and building materials.
In sound absorbing materials made of fibers, it has been proposed to improve the sound absorbing performance by using a fiber structure or a non-woven fabric and applying heat or pressure to one side thereof.

For example, Patent Literature 1 proposes a sound absorbing material in which sound absorbing performance is improved by heat-treating the surface of a nonwoven fabric to form a film. Further, in Patent Document 2, a fiber structure in which inelastic crimped staple fibers and thermoadhesive composite staple fibers are arranged in the thickness direction of the fiber structure is subjected to heat treatment while being pressurized in the thickness direction of the fiber structure. discloses a method for manufacturing a fiber structure for a sound absorbing material having a film-like surface.
In these inventions, heat treatment can improve the sound absorption performance, but the performance is not sufficient and it is difficult to control the performance.

JP-A-2000-199161 Japanese Patent No. 5155016

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-woven fabric face material from which a laminated sound absorbing material exhibiting good sound absorbing properties can be obtained.

That is, the present invention provides a nonwoven fabric facing material containing 20 to 100% by weight of thermoadhesive conjugate fibers, wherein the nonwoven fabric facing material has a basis weight of 1 to 100 g/m ² , a thickness of 0.01 to 0.15 mm, and a maximum The nonwoven fabric face material is characterized by having a pore size/minimum pore size of 3.5 or more.

The present invention also provides a method for producing a nonwoven fabric face material, wherein a web containing 20 to 100% by weight of thermoadhesive conjugate fibers is produced by using thermoadhesive conjugate fibers having a fiber diameter of 7 to 20 μm containing a thermoadhesive component. and pressing the web at a temperature higher than the melting point of the thermobondable component of the thermobondable conjugate fiber to form the web to a thickness of 0.01 to 0.15 mm and a maximum pore size/ A method for producing a nonwoven fabric face material, including a heat pressing step to make the minimum pore size 3.5 or more.

ADVANTAGE OF THE INVENTION According to this invention, the nonwoven fabric surface material which can obtain the lamination|stacking sound absorption material which shows a favorable sound absorption characteristic can be provided.

1 is an electron micrograph (magnification: 300) of the surface of the nonwoven fabric face material of the present invention. 1 is an electron micrograph (magnification: 1000) of a cross section of a nonwoven fabric face material of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

[Nonwoven fabric face material]
The nonwoven facing material of the present invention is a nonwoven facing material containing thermobondable composite fibers. A thermobondable composite fiber includes a fiber-forming component and a thermobondable component. This thermoadhesive conjugate fiber preferably has a core-sheath structure. In this core-sheath structure, the sheath component consists of a heat-adhesive component, and the core component consists of a fiber-forming component.

Examples of fiber-forming components include polyesters such as polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate, and polyolefins, with polyethylene terephthalate being preferred. In the case of polyethylene terephthalate, its intrinsic viscosity is, for example, 0.30 to 0.80 dl/g, preferably 0.40 to 0.70 dl/g. If it is less than 0.30 dl/g, the fiber becomes too brittle, which is not suitable because it causes breakage or deterioration in the process of forming the nonwoven fabric. If it is more than 0.80 dl/g, it is not suitable because it is difficult to be crushed during press working, which will be described later.

A polymer having a melting point of 100 to 200° C. or a glass transition temperature of 50 to 110° C. is used as the heat adhesive component. Examples of such polymers include copolyester polymers, polyester elastomers, polyurethane elastomers, inelastic polyester polymers and their copolymers, polyolefin polymers and their copolymers, and polyvinyl alcohol polymers.

Copolyester polymers include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and naphthalenedicarboxylic acid, and/or alicyclic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid. Copolymerization containing formula dicarboxylic acids and a predetermined number of aliphatic or alicyclic diols such as diethylene glycol, polyethylene glycol, propylene glycol, and paraxylene glycol, and optionally adding oxyacids such as parahydroxybenzoic acid. Esters and the like can be mentioned, and for example, polyesters obtained by copolymerizing terephthalic acid and ethylene glycol with the addition of isophthalic acid and 1,6-hexanediol can be used.

Polyurethane-based elastomers include low-melting point polyols having a molecular weight of about 500 to 6000, such as dihydroxypolyethers, dihydroxypolyesters, dihydroxypolycarbonates, and dihydroxypolyesteramides, and organic diisocyanates having a molecular weight of 500 or less, such as p,p'-diphenylmethane. Diisocyanate, tolylene diisocyanate, isophorone diisocyanate, hydrogenated diphenyl methane isocyanate, xylylene isocyanate, 2,6-diisocyanatomethylcaproate, hexamethylene diisocyanate, etc., and a chain extender with a molecular weight of 500 or less, such as glycol amino alcohol or triol It is a polymer obtained by the reaction of

Among these polymers, particularly preferred are polyurethanes using polytetramethylene glycol, poly-ε-caprolactam, or polybutylene adipate as polyols. Examples of organic diisocyanates in this case include p,p'-bishydroxyethoxybenzene and 1,4-butanediol.

As the polyester-based elastomer, a polyether ester copolymer obtained by copolymerizing a thermoplastic polyester as a hard segment and a poly(alkylene oxide) glycol as a soft segment, more specifically terephthalic acid, isophthalic acid, and phthalic acid. , naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, succinic acid, oxalic acid, At least one dicarboxylic acid selected from aliphatic dicarboxylic acids such as adipic acid, sebacic acid, dodecanedioic acid, dimer acid, or ester-forming derivatives thereof, 1,4-butanediol, ethylene glycol trimethylene glycol, Aliphatic diols such as tetramethylene glycol, pentamethylene glycol, hexamethylene glycol neopentyl glycol and decamethylene glycol, or alicyclic diols such as 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and tricyclodecanemethanol , or at least one diol component selected from ester-forming derivatives thereof, and polyethylene glycol, poly (1,2- and 1,3-polypropylene oxide) glycol, poly Terpolymers composed of at least one of poly(alkylene oxide) glycols such as (tetramethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, and copolymers of ethylene oxide and tetrahydrofuran. can be done.

In particular, block copolymer polyether esters having polybutylene terephthalate as a hard component and polyoxybutylene glycol as a soft segment are preferred from the viewpoint of adhesiveness, temperature characteristics and strength. In this case, the polyester portion that constitutes the hard segment is polybutylene terephthalate whose main acid component is terephthalic acid and whose main diol component is butylene glycol. Of course, part of this acid component (usually 30 mol% or less) may be substituted with another dicarboxylic acid component or oxycarboxylic acid component, and similarly, part of the glycol component (usually 30 mol% or less) may be substituted with butylene. It may be substituted with a dioxy component other than the glycol component. Also, the polyether portion constituting the soft segment may be a polyether substituted with a dioxy component other than butylene glycol.

Polyolefin polymers used as heat-adhesive components include polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and crystalline propylene copolymers composed of propylene and other α-olefins. Examples include coalescence, copolymerization of these with styrene, acrylic acid, methacrylic acid, maleic acid, and the like.

The heat-adhesive conjugate fiber is a conjugate fiber that is conjugated so that at least the heat-adhesive component is exposed on the surface of the conjugate fiber, and the heat-adhesive component is the sheath component and the fiber-forming component is the core component, Both components are combined in a core-sheath type or eccentric sheath-core type; Sea-island type conjugate fibers in which the adhesive component is the sea, and segmented pie type conjugate fibers in which the heat-adhesive component and the fiber-forming component are alternately arranged. preferable.

The proportion of the heat-adhesive component in the heat-adhesive conjugate fiber is preferably 40-95% by weight, more preferably 45-90% by weight, and particularly preferably 50-80% by weight, based on the weight of the heat-adhesive conjugate fiber. %. If it is less than 40% by weight, the amount of the polymer that forms a film by thermal melting is small, so the intended sound absorbing performance cannot be obtained, which is not preferable. On the other hand, if it exceeds 95% by weight, it is difficult to stably melt-spun the conjugate fiber, which is not preferable.

The fiber diameter of the heat-adhesive conjugate fiber used for producing the nonwoven fabric face material of the present invention is preferably 7-20 μm, more preferably 10-17 μm. This fiber diameter is the fiber diameter of the fibers before being subjected to the heat pressing step for producing the nonwoven fabric face material of the present invention. If the fiber diameter is less than 7 μm, the nonwoven fabric will be dense and likely to reflect high-frequency sound waves, which is undesirable. On the other hand, if it exceeds 20 μm, it is difficult to obtain a nonwoven fabric having a maximum pore size/minimum pore size, which will be described later, and the sound absorbing performance is inferior, which is not preferable.

The proportion of the thermally adhesive conjugate fiber contained in the nonwoven face material is 20 to 100% by weight, preferably 30 to 100% by weight, more preferably 50 to 100% by weight. If it is less than 20% by weight, the heat-adhesive component melts and flows due to heating and pressure, resulting in an insufficient film portion on the surface, and the size of the pores becomes small, so that sufficient sound absorption performance cannot be obtained. Can not.

The nonwoven fabric face material may contain fibers other than the thermoadhesive conjugate fibers as long as the physical properties described later are satisfied. Synthetic fibers are preferred as the fibers, and polyester fibers, nylon fibers, acrylic fibers, polyolefin fibers and the like can be mentioned, and polyester fibers are preferred. The fiber diameter is, for example, 5-25 μm, preferably 7-20 μm.

The nonwoven fabric face material may contain ultrafine fibers having a single fiber diameter of 10 μm or less. By containing such ultrafine fibers, when combined with a nonwoven fabric surface material, the nonwoven fabric that is the base material can attenuate sound waves, and the sound absorption performance can be further improved.

[Fabric weight, thickness, porosity of non-woven fabric face material]
The basis weight of the nonwoven fabric face material is 1 to 100 g/m ² , preferably 10 to 100 g/m ² , more preferably 20 to 60 g/m ² . If the basis weight is less than 1 g/m ² , there is a possibility that sufficient sound absorbing performance cannot be obtained. On the other hand, when the basis weight exceeds 100 g/m ² , the sound waves in the high frequency range are reflected, and the sound absorption performance in the same range tends to decrease.

The thickness of the nonwoven fabric face material of the present invention is 0.01 to 0.15 mm, preferably 0.03 to 0.12 mm, more preferably 0.05 to 0.10 mm. If the thickness is less than 0.01 mm, sound waves in the high frequency range will be reflected, making it impossible to obtain the desired sound absorption performance. If the thickness exceeds 0.15 mm, the desired sound absorption performance cannot be obtained.

The porosity of the nonwoven face material is preferably 30-70%, more preferably 40-65%. If it is less than 30%, the sound absorption coefficient for high frequency sound waves tends to decrease, which is not preferable. On the other hand, if it exceeds 70%, it becomes difficult to obtain the desired sound absorption performance.

[Maximum pore size/minimum pore size of nonwoven fabric face material]
The nonwoven fabric face material of the present invention must have a ratio of maximum pore size/minimum pore size of 3.5 or more, preferably 4 or more, more preferably 5 or more. This maximum pore diameter/minimum pore diameter is the ratio (maximum pore diameter/minimum pore diameter) of the maximum pore diameter (μm) and the minimum pore diameter (μm) in the pore diameter distribution measured with a perm porometer.

When the maximum pore diameter/minimum pore diameter is 3.5 or more, energy loss due to vortices and turbulence accompanying the expansion and contraction of the flow path increases due to the above-described presumed mechanism, and high sound absorption performance can be obtained.

The maximum pore diameter/minimum pore diameter is preferably 20 or less, more preferably 15 or less. It is preferable that it is 20 or less because it is possible to obtain sound absorption performance in which preferable low frequency range and high frequency range are well-balanced.

As described above, the maximum pore diameter and minimum pore diameter measured with a perm porometer are the ratio of the maximum pore diameter (μm) and the minimum pore diameter (μm) in the pore size distribution measured with a perm porometer (maximum Pore diameter/minimum pore diameter), which does not mean the maximum pore diameter and the minimum pore diameter in the same flow path, but in the study of the inventor, the maximum pore diameter in the pore diameter distribution measured with a perm porometer (μm) to the minimum pore diameter (μm) (maximum pore diameter/minimum pore diameter) is an effective index of the sound absorption performance of the nonwoven fabric face material.

The maximum pore size/minimum pore size can be increased by increasing the temperature and pressure during hot pressing and by lengthening the heat pressing time. In addition, by increasing the ratio of the heat-adhesive conjugate fibers contained in the nonwoven fabric face material, a sufficient film is formed on the surface of the nonwoven fabric face material. can be increased.

[Manufacturing method of nonwoven face material]
The nonwoven fabric face material of the present invention that satisfies the above conditions uses thermoadhesive conjugate fibers with a fiber diameter of 7 to 20 μm containing a thermoadhesive component to form a web containing 20 to 100% by weight of thermoadhesive conjugate fibers. and pressing the web at a temperature above the melting point of the heat-bondable component of the heat-bondable conjugate fiber to form the web to a thickness of 0.01-0.15 mm and a maximum pore size/minimum It can be produced by a heat pressing process that makes the pore size 3.5 or more.

That is, according to the present invention, there is provided a method for producing a non-woven fabric face material, in which heat-adhesive conjugate fibers having an average fiber diameter of 7 to 20 μm containing a heat-adhesive component are used, and 20 to 100% by weight of the heat-adhesive conjugate fiber is used. and pressing the web at a temperature above the melting point of the thermobondable component of the thermobondable conjugate fiber to form the web to a thickness of 0.01 to 0.15 mm and a maximum A method for producing a nonwoven fabric face material is provided, which includes a hot pressing step to achieve a pore size/minimum pore size of 3.5 or more.

In the web forming step, a conventionally known method can be used as a method of forming a web, preferably a card method, an airlaid method, or a wet papermaking method.
The content of the thermoadhesive conjugate fiber in the web formed in the web forming process is 20-100% by weight, preferably 30-100% by weight, more preferably 50-100% by weight.

[Heat pressing step]
In the heat-pressing step, the nonwoven fabric surface material of the present invention is obtained by subjecting the web obtained in the web-making step to heat-pressing. Examples of the hot-pressing method include a method of pressing with a heated flat plate and a calendering method of gripping both with a pair of heated rollers.

The processing temperature, pressure and time are appropriately adjusted so that the thickness and the maximum pore size/minimum pore size of the resulting nonwoven fabric surface material fall within a predetermined range, particularly 3.5 or more. adjust. After the web is produced, the obtained web may be directly subjected to the heat-pressing step, or may be subjected to the heat-pressing step after being heat-treated by an air-through dryer or the like.

In the heat-pressing step, it is essential to heat and press the web from both sides. By doing so, fine pores are formed on both surfaces of the nonwoven fabric surface material obtained from the web, and a sound wave attenuation effect can be sufficiently obtained by expanding or contracting the flow path, which will be described later.

Since the non-woven fabric face material of the present invention contains heat-adhesive conjugate fibers, it may adhere to the surface of the hot plate of the pressing machine or the calender roller in the heat-pressing process. For this reason, it is desirable to take a combination of countermeasures, such as applying a special coating or micro-roughness processing to the surface of the roller or flat plate to suppress adhesion, or using a mold release agent. When a calender roller is used, the non-woven fabric face material after heat-pressing can be taken off with an appropriate tension, and sticking to the roller can be suppressed.

In the non-woven fabric face material, it is preferable that 80% or more of the area of the non-woven fabric face material is heat-pressed in the heat-pressing step. That is, in the heat-pressing step, it is preferable that 80% or more of the area of the nonwoven fabric surface material is subjected to heat and pressure by a flat plate or a roller instead of partial pressure bonding such as embossing. By doing so, the area of the crimped portion that contributes to sound absorption can be increased, and high sound absorption performance can be obtained.

In the nonwoven fabric face material of the present invention, the heat-adhesive components in the heat-adhesive conjugate fibers are sufficiently melted by heat and pressure is applied. A web-like film derived from the heat-adhesive component is formed on the front and back surfaces of the material. This state can be observed, for example, with a scanning electron microscope (FIG. 1).

Conventionally, it is said that sound absorption performance is exhibited in fiber porous materials such as non-woven fabrics by attenuating sound waves in a boundary layer formed on the surface of fibers, in which air is difficult to move. For this reason, in the conventional technology, it is common to configure the nonwoven fabric surface material with ultrafine fibers having a large specific surface area and an average fiber diameter of less than 7 μm so that the total surface area of the fibers, which serves as a sound absorbing field, increases per unit weight. .

On the other hand, the nonwoven fabric face material of the present invention comprises a nonwoven fabric made of fibers having a larger fiber diameter, and has fine pores formed on its front and back surfaces by a coating of a thermoadhesive component. A large void is formed. The combination of these fine apertures and voids causes abrupt expansion and contraction of the sound wave flow path, which in turn induces eddies and turbulence, attenuating the energy of the sound wave.

Although the mechanism by which the nonwoven fabric face material of the present invention develops sound absorption performance has not been fully clarified, the inventor presumes as described above.

[Laminated sound absorbing material]
The present invention is also a laminated sound absorbing material comprising the above-described nonwoven fabric face material of the present invention and a porous substrate. In this laminated sound absorbing material, the nonwoven fabric surface material of the present invention may be directly laminated with the porous base material, or may be laminated with an air layer disposed therebetween. When providing an air layer, it is preferable to use a spacer as appropriate to maintain the air layer between the nonwoven fabric face material and the porous substrate. The nonwoven fabric face material may be laminated on one side or both sides of the porous substrate.

As a method for laminating the nonwoven fabric surface material and the porous base material and integrating the two, a conventionally known method can be used. For example, a method using a powdery binder and a spider web-like low-melting-point fiber sheet (Spunfab (registered trademark)) can be used.

[Porous substrate]
The porous base material used when the nonwoven fabric face material of the present invention is laminated on the porous base material will be described below. A porous substrate having air permeability is used as the porous substrate. Nonwoven fabrics, woven fabrics, and open-cell foams can be exemplified as the porous substrate, and nonwoven fabrics are preferred. These may be used in combination.

A nonwoven fabric used as a porous substrate can be produced by a conventionally known method. For example, it can be obtained by mixing fibers and heat-adhesive fibers, spinning a uniform web with a roller card, laminating the fibers in the horizontal direction, and then heat-treating.

Specifically, for example, using a heat treatment machine as shown in FIG. 1 of JP-A-2008-68799, the web is heated while being folded into an accordion shape, and a method of forming fixed points by thermal fusion is used. can be done. In this case, for example, it is preferable to use the apparatus shown in Japanese Patent Application Laid-Open No. 2002-516932 (commercially available, for example, Struto equipment manufactured by Struto).

The basis weight of the porous substrate is preferably 50-2000 g/m ² , more preferably 100-1500 g/m ² . If it is less than 50 g/m ² , it is not preferable because there is a possibility that sufficient sound absorbing performance cannot be obtained. If it is more than 2000 g/m ² , the weight of the sound absorbing material is unfavorably increased.

The thickness of the porous substrate is preferably 5 mm or more, preferably 5 to 50 mm, particularly preferably 8 to 20 mm. If the thickness is less than 5 mm, there is a possibility that sufficient sound absorption cannot be obtained, which is not preferable.

[Orientation of laminated sound absorbing material]
The laminated sound absorbing material of the present invention is used with the surface on which the nonwoven fabric surface material is laminated facing the sound source. By arranging the non-woven fabric surface material on the sound source side, the sound source is arranged at a position where the vibration velocity of the particles is high, that is, at a position where the sound energy is large, so that the incident sound can be more efficiently attenuated. .

When the non-woven fabric face materials are laminated on both sides of the porous base material, the non-woven fabric face materials are laminated on both the sound source side and the non-sound source side so as to sandwich the porous base material. In this case, since there is no distinction between the front and back sides of the laminated sound absorbing material, the handleability is improved, and even better sound absorbing properties can be obtained.
The laminated sound absorbing material may be subjected to known functional finishing such as dyeing, water-repellent, flame-retardant, and flame-retardant.

Examples of the present invention and comparative examples will be described in detail. Each measurement item in the examples was measured by the following method.

(1) Melt viscosity The polymer after drying is set in an orifice set to the Ruder melting temperature at the time of spinning and held melted for 5 minutes. plot. A shear rate-melt viscosity curve was created by gently connecting the plots, and the melt viscosity at a shear rate of 1000 sec ^-1 was observed.

(2) Melt flow rate (MFR)
It was measured at a temperature of 190° C. and a load of 2.169 kg according to JIS K7210.

(3) Melting point A TA-2200 differential scanning calorimeter DSC manufactured by TA Instruments was used. For the measurement, 10 mg of the sample was measured under a nitrogen atmosphere at a heating rate of 20° C./min.

(4) Fiber Diameter and Fiber Length The fiber diameter was measured using an image of a cross-section of the web test piece before hot-pressing, taken with a scanning electron microscope (JEOL JCM-5700) at a magnification of 1000 times. In the electron microscope cross-sectional photograph of each sample, 10 fibers cut in a direction generally perpendicular to the fiber axis direction are arbitrarily selected, the fiber diameter is measured, and the average value (μm) thereof is calculated. fiber diameter. It should be noted that whether the fiber was a composite fiber or another fiber was determined from the cross-sectional shape, and the diameter of each fiber was calculated separately.
The fiber length was measured by the method described in Japanese Industrial Standard JIS L 1015:2010 8.4.1 A method. In this measurement of the fiber length, unlike the above measurement of the fiber diameter, the fiber length of the fiber used as the raw material of the nonwoven fabric face material was measured.

(5) Basis weight and total basis weight According to JIS L 1096, basis weight (g/m ² ) and total basis weight (g/m ² ) were measured.

(6) Thickness The thickness (mm) of the nonwoven fabric face material was measured according to JIS P 8118. The thickness (mm) of the composite sound absorbing material was measured according to JIS L 1096. In each case, the average value was calculated with n number of 5.

(7) Porosity From basis weight, thickness and resin density, a value was obtained by the following formula, and the obtained value was rounded off to the first decimal place to obtain the porosity.
Porosity (%) = 100-{basis weight (g/m ² ) × 100/resin density (g/cm ³ )/thickness (mm)/1000}

(8) Maximum pore diameter / minimum pore diameter As a measuring device, PMI Perm Porometer (model: CFP-1200-AEXL) is used, and PMI GALWICK immersion liquid (surface tension: 15.9 dynes /cm) was used to obtain a wet flow rate curve based on the bubble point method specified in ASTM F316-86. At this time, the maximum pore diameter was determined by substituting the bubble point pressure into the bubble point formula.
Next, a dry flow rate curve was obtained for the same sample, and the minimum pore size was obtained by substituting the pressure at which the flow rate on the dry flow rate curve and the flow rate on the previously obtained wet flow rate curve coincided with the bubble point equation.
A value of maximum pore diameter/minimum pore diameter was calculated from the obtained maximum pore diameter and minimum pore diameter, and the value was rounded off to the second decimal place. The measurement was performed with n number of 5, the value was calculated, and the average value was calculated.

(9) Sound Absorption Characteristics Based on JISA1405, normal incidence sound absorption coefficients of building materials were measured by the in-pipe method at 1/3 octave center frequencies of 1000 Hz and 2000 Hz, and the average value was calculated with n number of 5.
Furthermore, the average sound absorption coefficient was obtained by arithmetically averaging the sound absorption coefficients at 1000 Hz and 2000 Hz, and used as an index of the sound absorption performance.
Next, the method for producing the nonwoven fabric surface material and the porous substrate used in Examples and Comparative Examples will be described. These were manufactured by the following method.

(10) Fineness Measured by the method described in Japanese Industrial Standard JIS L 1015:2010 8.5.1 A method.

(Preparation of Nonwoven Fabric Face Material A)
Polyethylene terephthalate (melting point: 256°C) having a single fiber fineness of 1.7 dtex (fiber diameter of 12.5 µm) and a fiber length of 5 mm is placed in the core, and terephthalic acid and isophthalic acid are mixed at 80/20 (mol%). A copolymerized polyethylene terephthalate (melting point: 155°C) consisting of a diol component obtained by mixing ethylene glycol and tetraethylene glycol at a ratio of 35/65 (mol%) was placed in the sheath, and the sheath/core weight ratio was 50/50. A web was obtained by a known air-laid nonwoven fabric manufacturing apparatus using 100% by weight of core-sheath type heat-adhesive conjugate short fibers obtained by spinning by a conventional method so as to have a weight of 50%. Then, the web was heat-treated at 180° C. for 1 minute using a hot air circulating dryer to obtain a nonwoven fabric.

A 15 cm × 15 cm square piece was taken from the obtained nonwoven fabric, held with a polyimide film, and then pressed evenly over the entire nonwoven fabric surface with a flat plate press at a hot plate temperature of 150°C and a press pressure of 10 kg/cm ² for 10 seconds. It was cooled to obtain a nonwoven fabric surface material A (basis weight: 40 g/m ² ). The basis weight, thickness and maximum pore size/minimum pore size of the obtained nonwoven fabric face material were measured.

(Preparation of Nonwoven Fabric Face Material B)
Polyethylene terephthalate (melting point: 256°C) with a single fiber fineness of 1.7 dtex (fiber diameter: 13.6 μm) and a fiber length of 5 mm is placed in the core, and high-density polyethylene (melting point: 130°C, melt flow rate: 20 g/min) is used in the sheath. and using 100% by weight of core-sheath type heat-adhesive conjugate short fibers obtained by spinning by a conventional method so that the weight ratio of sheath/core is 50/50, using a known air-laid nonwoven fabric manufacturing apparatus got the web. Then, the web was heat-treated at 180° C. for 1 minute using a hot air circulating dryer to obtain a nonwoven fabric.

A 15 cm x 15 cm square piece was taken from the obtained nonwoven fabric, held with a polyimide film, and then pressed evenly over the entire surface of the nonwoven fabric with a hot press at a hot plate temperature of 130°C and a pressure of 10 kg/cm ² for 10 seconds, and then cooled. to obtain a nonwoven fabric face material B (basis weight: 40 g/m ² ). The basis weight, thickness and maximum pore size/minimum pore size of the obtained nonwoven fabric face material were measured.

(Preparation of Nonwoven Fabric Face Material C)
Polyethylene terephthalate (melting point: 256°C) having a single fiber fineness of 2.2 dtex (fiber diameter of 14.4 μm) and a fiber length of 51 mm is placed in the core, and terephthalic acid and isophthalic acid are mixed at a ratio of 60/40 (mol%). A copolymerized polyethylene terephthalate (softening point: 110°C) consisting of a component, ethylene glycol and a diol component is arranged in the sheath and spun by a conventional method so that the weight ratio of the sheath/core is 50/50. 70% by weight of a core-sheath type heat-adhesive conjugate staple fiber, 30% by weight of polyethylene terephthalate (PET) crimped staple fiber having a single fiber fineness of 0.6 dtex (fiber diameter 7.4 μm) and a fiber length of 32 mm, and a known A web was obtained on a carded nonwoven fabric manufacturing apparatus. Then, the web was heat-treated at 180° C. for 1 minute using a hot air circulating dryer to obtain a nonwoven fabric.

A 15 cm × 15 cm square was taken from the obtained nonwoven fabric, held with a polyimide film, and then pressed evenly over the entire surface of the nonwoven fabric with a hot press at a hot plate temperature of 150°C and a pressure of 10 kg/cm ² for 10 seconds, and then cooled. to obtain a nonwoven fabric surface material C (basis weight: 40 g/m ² ). The basis weight, thickness and maximum pore size/minimum pore size of the obtained nonwoven fabric face material were measured.

(Preparation of nonwoven fabric face material D)
In the nonwoven fabric surface material C, 50% by weight of the core-sheath type thermoadhesive conjugate short fibers and 50% by weight of the single fiber fineness of 0.6 dtex are mixed, and the rest is produced in the same manner as the nonwoven fabric surface material C, to prepare the nonwoven fabric surface. A material D (basis weight: 40 g/m ² ) was obtained. The basis weight, thickness and maximum pore size/minimum pore size of the obtained nonwoven fabric face material were measured.

(Preparation of nonwoven fabric face material E)
In the nonwoven fabric face material D, the nonwoven fabric before being pressed with a hot press was used as the nonwoven fabric face material E (basis weight: 40 g/m ² ). The basis weight and thickness of the obtained nonwoven fabric face material were measured. The maximum pore size/minimum pore size could not be obtained because the flow rate in the dry flow curve and the flow rate in the wet flow curve did not match and the minimum pore size could not be measured.

(Preparation of nonwoven fabric face material F)
A nonwoven fabric face material F (basis weight: 40 g/m ² ) was produced by setting the pressure of the hot press to 1 kg/cm ² in the nonwoven fabric face material D. The basis weight, thickness and maximum pore size/minimum pore size of the obtained nonwoven fabric face material were measured.

(Preparation of Nonwoven Fabric Face Material G)
In the nonwoven fabric face material F, 30% by weight of the core-sheath type heat-adhesive composite staple fiber and 70% by weight of the single fiber fineness of 0.6 dtex are mixed, and the rest is produced in the same manner as the nonwoven fabric face material F. Face material G (weight per unit area: 40 g/m ² ) was used. The basis weight, thickness and maximum pore size/minimum pore size of the obtained nonwoven fabric face material G were measured.

(Preparation of porous substrate a)
Crimped staple fiber A (fineness 2.2 dtex, single fiber diameter 14 μm, fiber length 51 mm) made of polyethylene terephthalate (PET), core-sheath composite type thermal adhesive staple fiber (fineness 2 .2 dtex, single fiber diameter 14 µm, fiber length 51 mm, core/sheath = 50/50 (% by weight), core: polyethylene terephthalate with a melting point of 256°C, sheath: terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol as main ingredients Using a copolyester with a softening point of 110 ° C.), crimped staple fibers and heat-adhesive composite staple fibers are blended at a blend ratio of 80/20 (% by weight), passed through a carding machine, and a nonwoven fabric web with a basis weight of 110 g / m ² formed.

The obtained non-woven fabric web was sandwiched between metal meshes together with spacers of 16 mm in thickness, and heat-treated in a hot air dryer at 140°C for 15 minutes to obtain a porous substrate a having a thickness of 16 mm and a basis weight of 110 g/m ² . rice field.

(Preparation of porous substrate b)
A porous substrate b having a thickness of 16 mm and a basis weight of 150 g/m ² was obtained by the same composition and method as those for the porous substrate a.

(Preparation of porous substrate c)
Crimped staple fiber A (fineness 2.2 dtex, single fiber diameter 14 μm, fiber length 51 mm) made of polyethylene terephthalate (PET), crimped staple fiber B (fineness 0.11 dtex, single fiber diameter 3.2 μm, fiber length 32 mm), heat As an adhesive composite staple fiber (binder fiber), a core-sheath composite type thermoadhesive staple fiber (fineness 2.2 dtex, single fiber diameter 14 μm, fiber length 51 mm, core/sheath = 50/50 (% by weight), core: melting point 256 ℃ of polyethylene terephthalate, sheath: copolyester with a softening point of 110 ℃ mainly composed of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol), crimped staple fiber A, crimped staple fiber B, thermoadhesive composite staple fiber were blended at a mixing ratio of 40/40/20 (% by weight) and passed through a carding machine to form a nonwoven fabric web having a basis weight of 110 g/m ² .

The obtained nonwoven fabric web was sandwiched between metal meshes together with spacers of 16 mm in thickness, and heat-treated in a hot air dryer at 140°C for 15 minutes to obtain a porous substrate c having a thickness of 16 mm and a basis weight of 110 g/m ² . rice field.

(Preparation of porous substrate d)
A porous substrate c having a thickness of 16 mm and a basis weight of 150 g/m ² was obtained by the same composition and method as those of the porous substrate c.

[Example 1]
Nonwoven fabric face material A ^was used as the nonwoven fabric face material, and porous base material a was used as the porous base material. Adhesion was performed by spraying an adhesive onto the bonding surfaces of both with a spray and bringing the surfaces to be bonded together into contact with each other. The perpendicular incident sound absorption coefficient of the obtained laminated sound absorbing material was measured, and the respective sound absorption coefficients at frequencies of 1000 Hz and 2000 Hz and their arithmetic mean values were obtained.

[Examples 2 to 5]
As shown in Table 1, a laminated sound absorbing material having a total basis weight of 150 g/m ² was obtained in the same manner as in Example 1, except that the combination of the nonwoven fabric face material and the porous substrate was changed. The perpendicular incident sound absorption coefficient of the obtained laminated sound absorbing material was measured, and the respective sound absorption coefficients at frequencies of 1000 Hz and 2000 Hz and their arithmetic mean values were obtained.

[Comparative Examples 1 to 3]
As shown in Table 2, a laminated sound absorbing material having a total basis weight of 150 g/m ² was obtained in the same manner as in Example 1, except that the combination of the nonwoven fabric face material and the porous substrate was changed. The perpendicular incident sound absorption coefficient of the obtained laminated sound absorbing material was measured, and the respective sound absorption coefficients at frequencies of 1000 Hz and 2000 Hz and their arithmetic mean values were obtained. In addition, in Comparative Example 1, the minimum pore size could not be measured.

[Comparative Example 4]
The normal incident sound absorption coefficient of the sound absorbing material consisting of a single-layer nonwoven fabric of the porous base material b was measured, and the respective sound absorption coefficients at frequencies of 1000 Hz and 2000 Hz and their arithmetic mean values were obtained.

[Comparative Example 5]
The normal incident sound absorption coefficient of the sound absorbing material consisting of a single-layer nonwoven fabric of the porous substrate d was measured, and the respective sound absorption coefficients at frequencies of 1000 Hz and 2000 Hz and their arithmetic mean values were obtained.

It can be suitably used as a sound absorbing material for automobiles, electronic devices, buildings, houses, and the like.

Claims (8)

A nonwoven fabric facing material containing 20 to 100% by weight of thermoadhesive conjugate fibers, the nonwoven fabric facing material having a basis weight of 1 to 100 g/m ² , a thickness of 0.01 to 0.15 mm, and a maximum pore size/minimum fineness. A nonwoven fabric face material characterized by having a pore size of 3.5 or more. 2. The nonwoven facing material according to claim 1, wherein the weight ratio of the thermoadhesive composite fibers in the nonwoven facing material is 50 to 100% by weight. The nonwoven facing material according to claim 1 or 2, having a thickness of 0.03 to 0.12 mm. The nonwoven fabric facing material according to any one of claims 1 to 3, which has a porosity of 30 to 70%. The nonwoven fabric facing material according to any one of claims 1 to 4, wherein the heat-adhesive conjugate fiber has a core-sheath structure, and the sheath component is the heat-adhesive component. A laminated sound absorbing material comprising the nonwoven fabric face material according to any one of claims 1 to 5 and a porous substrate. 7. The laminated sound absorbing material according to claim 6, wherein the porous substrate is a nonwoven fabric. A method for producing a non-woven fabric face material, comprising: a web forming step of forming a web containing 20 to 100% by weight of thermoadhesive conjugate fibers by using thermoadhesive conjugate fibers containing a thermoadhesive component and having a fiber diameter of 7 to 20 μm. , and pressing the web at a temperature higher than the melting point of the heat-adhesive component of the heat-adhesive conjugate fiber, the web to a thickness of 0.01 to 0.15 mm, and a maximum pore size/minimum pore size of 3 .A method for producing a nonwoven fabric face material, which includes a heat pressing step to a value of 5 or higher.

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