JP2019151963A - Laminated nonwoven fabric and sound absorption material - Google Patents

Abstract

To provide a nonwoven fabric having durability for practical use, excellent in sound absorption performance in use as sound absorption material, also having excellent moldability; and a sound absorption material made from the same.SOLUTION: A laminated nonwoven fabric includes a spun-bonded nonwoven fabric layer and a melt-blown nonwoven fabric layer which are laminated. The spun-bonded nonwoven fabric on at least one side has an average single fiber diameter of 6.5 to 11.9 μm, an apparent density of 0.05 to 0.4 g/cm, and a stress per unit basis weight when stretched 5% in longitudinal direction of 0.3 to 1 (N/5 cm)/(g/m). A sound absorption material is made from the laminated nonwoven fabric.SELECTED DRAWING: None

Description

  The present invention relates to a laminated nonwoven fabric composed of fibers made of a thermoplastic resin, excellent in durability, and excellent in sound absorbing performance as a sound absorbing material, and a sound absorbing material using the laminated nonwoven fabric.

  Conventionally, glass wool, rock wool, aluminum fibers, porous ceramics, scrap cotton, and the like have been used as sound absorbing materials in the interior of automobiles and houses. However, since these sound absorbing materials have problems in terms of workability, obstacles to the human body, recycling, environment and the like, various sound absorbing materials using nonwoven fabrics have been proposed in recent years.

In recent years, as the environment-consciousness and comfort-consciousness increase, the sound absorption performance required for sound absorbing materials used in automobiles and home appliances has been increasing year by year, especially in the mid-high sound range (800-2500 Hz).
There is a need for improved performance.

  Conventionally, as a sound-absorbing material using such a nonwoven fabric, a sound-absorbing material composed of a nonwoven fabric in which a melt blown nonwoven fabric and a spunbond nonwoven fabric made of polyolefin resin or biodegradable resin are laminated and integrated has been proposed (Patent Document 1). reference.).

  In addition, a sound-absorbing laminate is proposed in which a surface material having a dense structure obtained by laminating a long fiber nonwoven fabric and a melt blown nonwoven fabric and a back material having a rough structure composed of a short fiber nonwoven fabric are joined ( (See Patent Document 2).

JP 2004-143632 A JP 2006-28708 A

  However, in the methods disclosed in Patent Documents 1 and 2 and the like, sufficient sound absorbing performance is not obtained over the entire middle and high sound region (800 to 2500 Hz), and there is a partial unevenness in sound absorption. In order to improve, it is necessary to take measures such as raising the basis weight, and in automobiles and home appliances, there is a problem that the weight increases.

  Therefore, the object of the present invention has been made in view of the above circumstances, and the object is to provide durability that can withstand practical use, excellent sound absorption performance as a sound absorbing material, and formability to use shape. Another object is to provide an excellent nonwoven fabric.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have appropriately determined the structure and strength of the laminated nonwoven fabric when using a laminated nonwoven fabric in which a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer are laminated. It was found that the sound absorption performance of the laminated nonwoven fabric can be improved by controlling. Furthermore, it was also found that this laminated nonwoven fabric can have the desired high level of durability and workability.

  The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.

The laminated nonwoven fabric of the present invention is a laminated nonwoven fabric obtained by laminating a spunbond nonwoven fabric layer and a melt blown nonwoven fabric layer, and the average single fiber diameter of at least one side of the spunbond nonwoven fabric is 6.5 to 11.9 μm. The hanging density is 0.05 to 0.4 g / cm ³ , and the stress at the time of 5% elongation per unit basis weight is 0.3 to 1 (N / 5 cm) / (g / m ² ). It is a laminated nonwoven fabric.

  According to the preferable aspect of the laminated nonwoven fabric of this invention, the surface roughness SMD by the KES method of at least one side is 1.0-3.0 micrometers.

  According to the preferable aspect of the laminated nonwoven fabric of this invention, the average single fiber diameter of a melt blown nonwoven fabric is 0.1-6 micrometers.

  According to the preferable aspect of the laminated nonwoven fabric of this invention, a melt blown nonwoven fabric is comprised with the fiber which consists of polyolefin resin (B).

  According to a preferred embodiment of the laminated nonwoven fabric of the present invention, the spunbonded nonwoven fabric is composed of fibers made of polyolefin resin (A).

  According to the preferable aspect of the laminated nonwoven fabric of this invention, the melt flow rate of a laminated nonwoven fabric is 80-850 g / 10min.

  According to the preferable aspect of the laminated nonwoven fabric of this invention, it is a sound-absorbing material using the laminated nonwoven fabric in any one of Claims 1-8.

  According to the present invention, a laminated nonwoven fabric having durability that can withstand practical use, excellent sound absorbing performance as a sound absorbing material, and excellent moldability can be obtained.

The laminated nonwoven fabric of the present invention is a laminated nonwoven fabric obtained by laminating a spunbond nonwoven fabric layer and a melt blown nonwoven fabric layer, and the average single fiber diameter of at least one side of the spunbond nonwoven fabric is 6.5 to 11.9 μm. The hanging density is 0.05 to 0.4 g / cm ³ , and the stress at the time of 5% elongation per unit basis weight is 0.3 to 1 (N / 5 cm) / (g / m ² ). It is a laminated nonwoven fabric. The details will be described below.

[resin]
The thermoplastic resin constituting the melt blown nonwoven fabric and spunbonded nonwoven fabric used in the present invention is a polyolefin resin such as polyethylene resin or polypropylene resin, a polyester resin such as polyethylene terephthalate resin or copolymer polyester resin, a polylactic acid resin or polybutylene. Biodegradable resins such as succinate resin and polyethylene succinate resin can be used. Among these, the polyethylene resin includes a homopolymer of ethylene or a copolymer of ethylene and various α-olefins, and the polypropylene resin includes a homopolymer of propylene or propylene and various α-olefins. And a copolymer thereof. Among these, from the viewpoint of spinnability and strength characteristics, polyolefin resins are preferable, and polypropylene resins are particularly preferably used.

  When a polypropylene resin is used as the thermoplastic resin constituting the meltblown nonwoven fabric and spunbond nonwoven fabric used in the present invention, the proportion of the propylene homopolymer is preferably 60% by mass or more, more preferably 70% by mass or more. Yes, more preferably 80% by mass or more. By doing so, good spinnability can be maintained and the strength can be improved.

  Regarding the thermoplastic resin (A) of the fibers constituting the spunbond nonwoven fabric layer and the thermoplastic resin (B) of the fibers constituting the meltblown nonwoven fabric layer according to the present invention, the melt flow rate (MFR) The value measured by ASTM D1238 (Method A) is adopted.

  Note that, according to this standard, for example, polypropylene is measured at a load of 2.16 kg and a temperature of 230 ° C., and polyethylene is measured at a load of 2.16 kg and a temperature of 190 ° C.

  First, it is preferable that MFR of the thermoplastic resin (A) of the fiber which comprises the said spun bond nonwoven fabric layer is 75-850 g / 10min. By making MFR preferably 75 to 850 g / 10 min, more preferably 120 to 600 g / 10 min, and further preferably 155 to 400 g / 10 min, the fibers are thinned when spinning the spunbond nonwoven fabric layer. Stable spinning is possible even when the spinning is performed at a high spinning speed in order to stabilize the behavior and increase the productivity. Further, by stabilizing the thinning behavior, the yarn swaying is suppressed, and unevenness when collecting in a sheet form is less likely to occur. Furthermore, since it becomes possible to draw stably at a high spinning speed, the fibers can be oriented and crystallized to obtain fibers having high mechanical strength.

  Further, it is important that the MFR of the thermoplastic resin (B) of the fibers constituting the melt blown nonwoven fabric layer is 200 to 2500 g / 10 minutes. By setting the MFR to 200 to 2500 g / 10 minutes, preferably 400 to 2000 g / 10 minutes, and more preferably 600 to 1500 g / 10 minutes, stable spinning can be easily performed and a fiber having a level of several μm can be obtained. be able to.

  As a thermoplastic resin used by this invention, 2 or more types of mixtures may be sufficient, and the resin composition containing other thermoplastic resins, thermoplastic elastomers, etc. can also be used. Naturally, two or more types of thermoplastic resins having different MFRs can be blended at an arbitrary ratio to adjust the MFR of the thermoplastic resin (A) and / or the thermoplastic resin (B).

  When adjusting the MFR of the thermoplastic resin (A) by blending, the MFR of the resin blended with respect to the main thermoplastic resin is preferably 10 to 1000 g / 10 min, more preferably 20 to 800 g / 10 minutes, more preferably 30 to 600 g / 10 minutes. By doing in this way, it can prevent that a viscosity spot arises partially in the blended polyolefin-type resin, and a fineness becomes non-uniform | heterogenous or spinnability deteriorates.

  Also, when spinning the fiber described later, in order to prevent the occurrence of partial viscosity spots, uniform the fineness of the fiber, and further reduce the fiber diameter as described later, this resin is decomposed against the resin used It is also conceivable to adjust the MFR. However, for example, it is preferable not to add peroxides, particularly free radical agents such as dialkyl peroxides. When this method is used, viscosity spots partially occur and the fineness becomes non-uniform, making it difficult to sufficiently reduce the fiber diameter, and when spinnability deteriorates due to viscosity spots and bubbles due to decomposition gas There is also.

In the laminated nonwoven fabric of the present invention, the ratio of MFR of thermoplastic resin (A) and thermoplastic resin (B) constituting each of the spunbond nonwoven fabric and the melt blown nonwoven fabric (MFR _B / MFR _A ) is in the range of 1-13. It is preferable that it is in the range of 1.5 to 12, more preferably. When the ratio of MFR (MFR _B / MFR _A ) is within the above range, adhesion is easily promoted when a melt blown nonwoven fabric is laminated on a spunbond nonwoven fabric, and an effect of improving physical properties such as peel strength can be obtained.

  In the thermoplastic resin used in the present invention, the antioxidant, weathering stabilizer, light stabilizer, antistatic agent, antifogging agent, antiblocking agent, lubricant, which are usually used, as long as the effects of the present invention are not impaired. Nucleating agents, additives such as pigments, or other polymers can be added as necessary.

  The melting point of the thermoplastic resin used in the present invention is preferably 80 to 200 ° C, more preferably 100 to 180 ° C, and further preferably 120 to 180 ° C. When the melting point is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 120 ° C. or higher, heat resistance that can withstand practical use can be easily obtained. Further, by setting the melting point to preferably 200 ° C. or less, more preferably 180 ° C. or less, it becomes easy to cool the yarn discharged from the die, and it becomes easy to perform stable spinning by suppressing the fusion of fibers.

  The laminated nonwoven fabric of the present invention contains a fatty acid amide compound having 23 to 50 carbon atoms in the thermoplastic resin (A) constituting the spunbonded nonwoven fabric in order to improve slipperiness and flexibility. It is a preferred embodiment.

  By setting the number of carbon atoms in the fatty acid amide compound to preferably 23 or more, and more preferably 30 or more, the fatty acid amide compound is suppressed from being excessively exposed on the fiber surface, and has excellent spinnability and processing stability. High productivity can be maintained. On the other hand, the number of carbon atoms of the fatty acid amide compound is preferably 50 or less, more preferably 42 or less, so that the fatty acid amide compound can easily move to the fiber surface, and can impart slipperiness and flexibility to the laminated nonwoven fabric. it can.

  Examples of the fatty acid amide compound having 23 to 50 carbon atoms used in the present invention include saturated fatty acid monoamide compounds, saturated fatty acid diamide compounds, unsaturated fatty acid monoamide compounds, and unsaturated fatty acid diamide compounds.

  Specifically, examples of the fatty acid amide compound having 23 to 50 carbon atoms include tetradocosanoic acid amide, hexadocosanoic acid amide, octadocosanoic acid amide, nervonic acid amide, tetracosaentapentic acid amide, nisic acid amide, and ethylenebislauric acid. Amides, methylene bis lauric acid amides, ethylene bis stearic acid amides, ethylene bis hydroxy stearic acid amides, ethylene bis behenic acid amides, hexamethylene bis stearic acid amides, hexamethylene bis behenic acid amides, hexamethylene hydroxy stearic acid amides, distearyl Such as adipic acid amide, distearyl sebacic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, and hexamethylene bisoleic acid amide. It can also be used in conjunction seen.

  In the present invention, among these fatty acid amide compounds, ethylene bis-stearic acid amide which is a saturated fatty acid diamide compound is particularly preferably used. Since ethylene bis-stearic acid amide is excellent in thermal stability, it can be melt-spun, and high productivity can be maintained by the thermoplastic resin (A) blended with this ethylene bis-stearic acid amide. Furthermore, since the slipperiness between fibers is improved, when a part of the energy of sound is consumed as thermal energy by vibration of the fibers, it is prevented that the fibers are less likely to vibrate due to friction between the fibers, and a sound absorbing effect is achieved. Can be increased.

  In this invention, it is preferable that the addition amount of the fatty acid amide compound with respect to this thermoplastic resin (A) is 0.01-5.0 mass%. The addition amount of the fatty acid amide compound is preferably 0.01 to 5.0% by mass, more preferably 0.1 to 3.0% by mass, and still more preferably 0.1 to 1.0% by mass. It is possible to impart moderate slipperiness and flexibility while maintaining spinnability.

  The amount added here refers to the mass percentage of the fatty acid amide compound added to the entire thermoplastic resin (A) constituting the spunbond nonwoven fabric layer constituting the laminated nonwoven fabric of the present invention. For example, even when the fatty acid amide compound is added only to the sheath component constituting the core-sheath composite fiber as described later, the addition ratio relative to the total amount of the core-sheath component is calculated.

  As a method for measuring the amount of fatty acid amide compound added to a fiber made of polyolefin resin, for example, the additive is solvent extracted from the fiber, and quantitative analysis is performed using liquid chromatography mass spectrometry (LS / MS) or the like. A method is mentioned. At this time, the extraction solvent is appropriately selected according to the type of the fatty acid amide compound. For example, in the case of ethylenebisstearic acid amide, a method using a chloroform-methanol mixed solution or the like can be mentioned as an example.

[fiber]
It is important that the fibers constituting the spunbond nonwoven fabric layer according to the present invention have an average single fiber diameter of 6.5 to 11.9 μm. By setting the average single fiber diameter to 6.5 μm or more, preferably 7.5 μm or more, more preferably 8.4 μm or more, a decrease in spinnability is prevented, and a stable and high-quality nonwoven fabric layer is formed. Can do. On the other hand, by setting the average single fiber diameter to 11.9 μm or less, preferably 11.2 μm or less, more preferably 10.6 μm or less, uniformity and denseness can be improved. When used as a sound-absorbing material, the number of fibers per unit area increases and the flexibility of each one increases, so that part of the sound energy can be efficiently consumed as thermal energy by vibration of the fibers. it can. Moreover, since the difference with the average single fiber diameter of the fiber which comprises the below-mentioned melt blown nonwoven fabric becomes small, it can prevent that the frequency band which is hard to absorb a sound is made.

In addition, in this invention, the value calculated by the following procedures shall be employ | adopted for the average single fiber diameter (micrometer) of the fiber which comprises the said spun bond nonwoven fabric layer.
(1) The thermoplastic resin (A) is melt-spun, pulled and stretched by an ejector, and then a nonwoven fiber web is collected on the net.
(2) Ten small piece samples (100 × 100 mm) are collected from the nonwoven fiber web.
(3) Take a surface photograph of 500 to 1000 times with a microscope, and measure the width of 100 polyolefin fibers in total, 10 from each sample.
(4) The average single fiber diameter (μm) is calculated from the average value of the 100 measured values.

  On the other hand, the fibers constituting the meltblown nonwoven fabric according to the present invention preferably have an average single fiber diameter of 0.1 to 6 μm, more preferably 0.4 to 4 μm, and 0.8 to 3 μm. More preferably. By doing in this way, a melt blown nonwoven fabric layer can be densified and a uniformity and denseness can be improved. When used as a sound-absorbing material, the number of fibers per unit area increases and the flexibility of each one increases, so that part of the sound energy can be efficiently consumed as thermal energy by vibration of the fibers. it can.

In addition, in this invention, the value calculated by the following procedures shall be employ | adopted for the average single fiber diameter (micrometer) of the fiber which comprises a melt blown nonwoven fabric layer.
(1) After the thermoplastic resin (B) is melt-spun and thinned with hot air, the nonwoven fiber web is collected on the net.
(2) Ten small piece samples (100 × 100 mm) are collected from the nonwoven fiber web.
(3) Take a surface photograph of 500 to 2000 times with a microscope, and measure the width of 100 fibers, 10 from each sample.
(4) The average single fiber diameter (μm) is calculated from the average value of the 100 measured values.

  Moreover, in this invention, it can use also as a composite type fiber which combined said thermoplastic resin. Examples of the composite form of the composite fiber include composite forms such as a concentric core-sheath type, an eccentric core-sheath type, and a sea-island type. Especially, since it is excellent in spinnability and a fiber can be adhere | attached uniformly by thermal bonding by arrange | positioning a low melting-point component to a sheath component, it is a preferable aspect to set it as a concentric core sheath type composite form.

[Laminated nonwoven fabric]
It is important that the laminated nonwoven fabric of the present invention is formed by laminating a spunbond nonwoven fabric layer and a melt blown nonwoven fabric layer. By comprising in this way, the sound-absorbing performance and durability of the level requested | required as a sound-absorbing material can be reconciled.

  The laminated nonwoven fabric of the present invention preferably has a surface roughness SMD of at least one side by the KES method of 1.0 to 3.0 μm. The surface roughness SMD by the KES method is preferably 1.0 μm or more, more preferably 1.3 μm or more, and even more preferably 1.6 μm or more, so that the fibers are excessively densified and used as a sound absorbing material. In this case, it is possible to prevent the sound from being easily reflected on the fiber surface.

  On the other hand, the surface roughness SMD by the KES method is preferably 3.0 μm or less, more preferably 2.9 μm or less, and even more preferably 2.8 μm or less, so that the surface of the nonwoven fabric is moderately smooth and used as a sound absorbing material. When used, it is possible to prevent partial unevenness in sound absorption.

  The surface roughness SMD by the KES method can be controlled by appropriately adjusting the average single fiber diameter, the MFR of the laminated nonwoven fabric, and the like.

In the present invention, the surface roughness SMD by the KES method adopts a value measured as follows.
(1) Three test pieces having a width of 200 mm × 200 mm are collected from the laminated nonwoven fabric.
(2) Set the test piece on the sample stage.
(3) The surface of the test piece is scanned with a contact for measuring surface roughness (material: φ0.5 mm piano wire, contact length: 5 mm) applied with a load of 10 gf, and the average deviation of the uneven shape on the surface is measured. To do.
(4) The above measurement is carried out in the longitudinal direction (longitudinal direction of the nonwoven fabric) and the lateral direction (width direction of the nonwoven fabric) of all the test pieces, and the average deviation of these 6 points is averaged to obtain the second decimal place. Is rounded off to obtain the surface roughness SMD (μm).

The MFR of the laminated nonwoven fabric of the present invention is preferably 80 to 850 g / 10 minutes. The MFR is preferably 80 to 850 g / 10 minutes, more preferably 120 to 600 g / 10 minutes, and even more preferably 155 to 400 g / 10 minutes, so that the fiber is thinned when the spunbond nonwoven fabric layer is spun. Stable spinning is possible even when the spinning is performed at a high spinning speed in order to stabilize the behavior and increase the productivity. Moreover, by stabilizing the thinning behavior of the spunbond fibers, yarn swinging is suppressed, and unevenness when collecting in a sheet form is less likely to occur. When used as a sound absorbing material, it is possible to prevent partial unevenness in sound absorbing properties. Furthermore, the MFR ratio (MFR _B / MFR _A ) between the spunbonded nonwoven fabric and the meltblown nonwoven fabric is reduced, and adhesion is facilitated when the meltblown nonwoven fabric is laminated on the spunbonded nonwoven fabric, resulting in improved physical properties such as peel strength. It is done.

  The value measured by ASTM D1238 (A method) is adopted as the MFR of the laminated nonwoven fabric of the present invention. Note that, according to this standard, for example, polypropylene is measured at a load of 2.16 kg and a temperature of 230 ° C., and polyethylene is measured at a load of 2.16 kg and a temperature of 190 ° C. In addition, when multiple types of resins are used, such as the thermoplastic resin that makes up the spunbond nonwoven fabric and the thermoplastic resin that makes up the melt blown nonwoven fabric, the highest temperature among the measured temperatures of each thermoplastic resin. Measured.

The product of the air flow rate and the basis weight of the laminated nonwoven fabric of the present invention is preferably 100 to 4000 (cc / (cm ² · sec)) · (g / m ² ). The product of the air flow rate and the basis weight is 100 (cc / (cm ² · sec)) · (g / m ² ) or more, preferably 200 (cc / (cm ² · sec)) · (g / m ² ) or more. More preferably, by setting it to 300 (cc / (cm ² · sec)) · (g / m ² ) or more, voids inside the nonwoven fabric are reduced, and when used as a sound-absorbing material, the sound-absorbing effect due to the porosity is reduced. It can be prevented from being damaged.

On the other hand, the product of the air flow rate and the basis weight is 4000 (cc / (cm ² · sec)) · (g / m ² ) or less, preferably 3500 (cc / (cm ² · sec)) · (g / m ² ). By setting the following, and more preferably 3000 (cc / (cm ² · sec)) · (g / m ² ) or less, the voids inside the laminated nonwoven fabric become excessively large and it becomes difficult to absorb high-frequency sound. Can be prevented. The product of air flow rate and basis weight is the average fiber diameter of the fibers constituting the spunbond nonwoven fabric layer, the average fiber diameter of the fibers constituting the meltblown nonwoven fabric layer, the mass ratio in the laminated nonwoven fabric, and the fusion of the fibers constituting the meltblown nonwoven fabric layer It can be adjusted by the degree, thermocompression bonding conditions (bonding rate, temperature and linear pressure) of the laminated nonwoven fabric.

In the present invention, as the product of the air flow rate and the basis weight, a value measured by the following procedure in accordance with “6.8.1 Frazier method” of JIS L1913 (2010) shall be adopted.
(1) Three test pieces having a width of 150 mm × 150 mm are collected from the laminated nonwoven fabric.
(2) The amount of air passing through each test piece (cc / (cm ² · sec)) is measured at a barometer pressure of 125 Pa.
(3) The average value of the above three points is calculated by rounding off the second decimal place.
(4) Multiply the calculated air flow rate (cc / (cm ² · sec)) by the basis weight (g / m ² ).

  In the laminated nonwoven fabric of the present invention, the content of the melt blown nonwoven fabric layer is preferably 1% by mass or more and 30% by mass or less with respect to the mass of the laminated nonwoven fabric. The content of the melt blown nonwoven fabric layer is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more, so that the structure inside the laminated nonwoven fabric is densified and the number of fibers per unit area Therefore, a part of sound energy can be efficiently consumed as thermal energy by vibration of the fiber. Moreover, when the content of the melt blown nonwoven fabric layer is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less, when productivity is lowered or heat bonding is performed. It is possible to prevent the inside from being excessively densified and the voids from being damaged.

  Moreover, it can prevent that the intensity | strength of a laminated nonwoven fabric falls by making content of the spun bond nonwoven fabric layer in a laminated nonwoven fabric preferably more than 70 mass% and less than 99 mass%.

In addition, in this invention, the value measured by the following procedures shall be employ | adopted for the content rate of a melt blown nonwoven fabric layer. In collecting the non-crimped part, only the crimped part may be punched and removed.
(1) Three test pieces having a width of 100 mm × 100 mm are collected from the laminated nonwoven fabric.
(2) Collect only the non-crimped part of the laminated nonwoven fabric.
(3) Measure the mass of the collected test piece and the melt blown nonwoven fabric collected from the test piece.
(4) The content ratio of the melt blown nonwoven fabric in the laminated nonwoven fabric is calculated.

The laminated nonwoven fabric of the present invention preferably has a longitudinal tensile strength per unit basis weight of 1.8 (N / 5 cm) / (g / m ² ) or more. The longitudinal tensile strength per unit weight is 1.8 (N / 5 cm) / (g / m ² ) or more, preferably 1.9 (N / 5 cm) / (g / m ² ) or more, more preferably 2 By setting it to 0.0 (N / 5 cm) / (g / m ² ) or more, a laminated nonwoven fabric excellent in durability can be obtained. The tensile strength in the longitudinal direction per unit weight depends on the spinning speed and average fiber diameter of the fibers constituting the spunbond nonwoven fabric layer, the mass ratio in the laminated nonwoven fabric, and the thermocompression bonding conditions (crimp rate, temperature and linear pressure) of the laminated nonwoven fabric. Can be adjusted.

In the present invention, the tensile strength in the longitudinal direction per unit weight is based on JIS L1913 (2010) 6.3.1, and the value measured as follows is adopted.
(1) Three test pieces having a width of 5 cm × 30 cm are collected from the laminated nonwoven fabric.
(2) A test piece is set on a tensile tester with a gripping interval of 20 cm.
(3) A tensile test is performed at a tensile rate of 10 cm / min, and the strength when the sample breaks is regarded as the tensile strength (N / 5 cm), and an average value of three points is calculated.
(4) The calculated tensile strength (N / 5 cm) is divided by the basis weight (g / m ² ), and the second decimal place is rounded off.

In the laminated nonwoven fabric of the present invention, it is important that the stress at 5% elongation in the longitudinal direction per unit weight is 0.3 to 1 (N / 5 cm) / (g / m ² ). The stress at 5% elongation in the vertical direction per unit weight is 0.3 (N / 5 cm) / (g / m ² ) or more, preferably 0.4 (N / 5 cm) / (g / m ² ) or more, Preferably, by setting it to 0.5 (N / 5 cm) / (g / m ² ) or more, it is possible to prevent the sound absorbing structure from being damaged due to the laminated nonwoven fabric stretching or crushing during molding. On the other hand, the 5% elongation stress in the vertical direction per unit weight is 1 (N / 5 cm) / (g / m ² ) or less, preferably 0.9 (N / 5 cm) / (g / m ² ) or less, Preferably, by setting it to 0.8 (N / 5 cm) / (g / m ² ) or less, it is possible to prevent the laminated nonwoven fabric from becoming hard and prevent the energy of sound from being easily consumed as thermal energy by vibration of the fiber. .

  The stress at 5% elongation in the vertical direction per unit weight is the spinning speed and average fiber diameter of the fibers constituting the spunbond nonwoven fabric layer, the mass ratio in the laminated nonwoven fabric, and the thermocompression bonding conditions of the laminated nonwoven fabric (compression rate, temperature and linear pressure). ) And the like.

In the present invention, the stress at 5% elongation in the longitudinal direction per unit weight is subjected to a tensile test according to 6.3.1 of JIS L1913 (2010), and adopts a value determined as follows. Shall.
(1) Three test pieces having a width of 5 cm × 30 cm are collected from the laminated nonwoven fabric.
(2) A test piece is set on a tensile tester with a gripping interval of 20 cm.
(3) A tensile test is performed at a tensile speed of 10 cm / min, the tensile strength (N / 5 cm) at 5% elongation (elongation at 5%) is measured, and the average value of the three points is calculated.
(4) The calculated tensile strength (N / 5 cm) at the time of 5% elongation (when the elongation is 5%) is divided by the basis weight (g / m ² ), and the second decimal place is rounded off.

The laminated nonwoven fabric of the present invention preferably has a longitudinal bending resistance per unit weight of 0.01 to 0.20 mN / (g / m ² ). By setting the bending resistance per basis weight to be preferably 0.01 mN / (g / m ² ) or more, it is possible to prevent the shape from being unable to be maintained when used as a sound absorbing material or when being molded. On the other hand, when the longitudinal bending resistance per unit basis weight is 0.20 mN / (g / m ² ) or less, it is possible to prevent the moldability from deteriorating.

  In the present invention, the value measured in accordance with “6.7.4 Gurley method” of JIS L1913 (2010 edition) is adopted as the longitudinal bending resistance per unit weight.

The basis weight of the laminated nonwoven fabric of the present invention is preferably 10 to ²⁰⁰ g / m ² . By making the basis weight preferably 10 g / m ² or more, more preferably 30 g / m ² or more, and further preferably 50 g / m ² or more, it is possible to obtain a laminated nonwoven fabric having mechanical strength and rigidity that can be put to practical use. it can.

On the other hand, when the basis weight is preferably 200 g / m ² or less, more preferably 150 g / m ² or less, and still more preferably 100 g / m ² or less, a laminated nonwoven fabric excellent in moldability can be obtained.

In addition, in this invention, the fabric weight of a laminated nonwoven fabric shall employ | adopt the value measured by the following procedures according to "6.2 Mass per unit area" of JISL1913 (2010).
(1) Three test pieces of 20 cm × 25 cm are collected from the laminated nonwoven fabric.
(2) Weigh each mass (g) in the standard state.
(3) The average value is expressed in terms of mass per 1 m ² (g / m ² ).

  The laminated nonwoven fabric of the present invention preferably has a thickness of 0.05 to 1.0 mm. The thickness is preferably 0.05 to 1.0 mm, more preferably 0.1 to 0.7 mm, and still more preferably 0.2 to 0.5 mm, thereby providing rigidity suitable for use as a sound absorbing material, A laminated nonwoven fabric having excellent moldability can be obtained.

In addition, in this invention, the thickness (mm) of a laminated nonwoven fabric shall employ | adopt the value measured by the following procedures according to 5.1 of JISL1906 (2000).
(1) A pressurizer having a diameter of 10 mm is used, and a thickness of 10 points per 1 m is measured in units of 0.01 mm at equal intervals in the width direction of the nonwoven fabric with a load of 10 kPa.
(2) Round off the third decimal place of the average of the above 10 points.

It is important that the apparent density of the laminated nonwoven fabric of the present invention is 0.05 to 0.4 g / cm ³ . By setting the apparent density to 0.4 g / cm ³ or less, preferably 0.36 g / cm ³ or less, and more preferably 0.32 g / cm ³ or less, the inside is excessively densified and voids are impaired. The sound absorption performance can be prevented from being lowered.

On the other hand, the apparent density was 0.05 g / cm ³ or more, preferably a 0.07 g / cm ³ or more, more preferably by a 0.1 g / cm ³ or more, suppressing the generation of fuzz or delamination, It can be set as the laminated nonwoven fabric provided with the strength and rigidity which can be practically used.

In the present invention, the apparent density (g / cm ³ ) is calculated based on the following formula from the basis weight and thickness before rounding, and rounded off to the third decimal place.
Apparent density (g / cm ³ ) = [weight per unit area (g / m ² )] / [thickness (mm)] × 10 ⁻³ .

[Method for producing laminated nonwoven fabric]
Next, the preferable aspect of the method of manufacturing the laminated nonwoven fabric of this invention is demonstrated concretely.

  The laminated nonwoven fabric of the present invention is a laminated nonwoven fabric composed of nonwoven fabrics produced by a spunbond (S) method and a melt blow (M) method. The production method of the laminated nonwoven fabric of the present invention can be carried out according to any method as long as the spunbond nonwoven fabric layer and the melt blown nonwoven fabric layer can be laminated. For example, a method in which fibers formed by a melt blown method are directly deposited on a nonwoven fabric layer obtained by a spunbond method to form a meltblown nonwoven fabric layer, and then the spunbond nonwoven fabric layer and the meltblown nonwoven fabric layer are fused. A method in which a bonded nonwoven fabric layer and a melt blown nonwoven fabric layer are overlapped and both nonwoven fabric layers are fused by heating and pressing, and a spunbond nonwoven fabric layer and a melt blown nonwoven fabric layer are bonded with an adhesive such as a hot melt adhesive or a solvent-based adhesive. A method of bonding can be employed. From the viewpoint of productivity, a method in which a melt blown nonwoven fabric layer is directly formed on a spunbond nonwoven fabric layer is a preferred embodiment.

  Moreover, according to the objective, it can be set as the structure which laminated | stacked the spun bond nonwoven fabric layer (S) and the melt blown nonwoven fabric layer (M) with SM, SMS, SMMS, SSMMS, and SMSMS.

  The spunbond nonwoven fabric layer is made by first spinning a molten thermoplastic resin as a long fiber from a spinneret, drawing it with compressed air by an ejector, and then collecting the fiber on a moving net to create a nonwoven fiber web. Turn into.

  As the shape of the spinneret and the ejector, various shapes such as a round shape and a rectangular shape can be adopted. In particular, the combination of a rectangular base and a rectangular ejector is used because the amount of compressed air used is relatively small, the energy cost is excellent, the yarns are not easily fused or scratched, and the yarn is easy to open. Preferably used.

  In the present invention, a thermoplastic resin is melted in an extruder, weighed and supplied to a spinneret, and is spun as a long fiber. When a polyolefin resin is used as the thermoplastic resin, the spinning temperature when melting and spinning the polyolefin resin is preferably 200 to 270 ° C, more preferably 210 to 260 ° C, and still more preferably 220 to 260 ° C. 250 ° C. By setting the spinning temperature within the above range, a stable molten state can be obtained, and excellent spinning stability can be obtained.

  The spun long fiber yarn is then cooled. As a method for cooling the spun yarn, for example, a method for forcibly blowing cold air onto the yarn, a method for natural cooling at the ambient temperature around the yarn, and a method for adjusting the distance between the spinneret and the ejector Or a combination of these methods can be employed. The cooling conditions can be appropriately adjusted and adopted in consideration of the discharge amount per single hole of the spinneret, the spinning temperature, the atmospheric temperature, and the like.

  Next, the cooled and solidified yarn is pulled and compressed by compressed air injected from the ejector. The spinning speed is preferably 3,000 to 6,500 m / min, more preferably 3,500 to 6,500 m / min, and further preferably 4,000 to 6,500 m / min. By setting the spinning speed to 3,000 to 6,500 m / min, high productivity is obtained, and oriented crystallization of the fibers proceeds, and high strength long fibers can be obtained. Normally, if the spinning speed is increased, the spinnability deteriorates and the yarn cannot be stably produced. As described above, the intended fiber can be obtained by using a thermoplastic resin having a specific range of MFR. Can be stably spun.

  Subsequently, the obtained long fibers are collected on a moving net to form a nonwoven fiber web. In the present invention, it is also a preferable aspect that a non-woven fiber web is temporarily bonded by contacting a heat flat roll from one side of the net on the net. By doing in this way, it prevents the surface layer of the nonwoven fiber web from turning over or blowing while it is being transported on the net, and transporting from collecting the yarn to thermocompression bonding. Can improve sex.

  Next, a conventionally known method can be employed for the melt blown nonwoven fabric. First, a thermoplastic resin is melted in an extruder and supplied to the die part, and hot air is blown onto the yarn extruded from the die to make it thin, and then a nonwoven fiber web is formed on the collection net. In the melt blow method, a complicated process is not required, a fine fiber of several μm can be easily obtained, and high collection efficiency can be easily achieved.

  Subsequently, an intended laminated nonwoven fabric can be obtained by laminating the obtained spunbond nonwoven fiber web and the melt blown nonwoven fiber web and thermally bonding them.

  As a method of heat-bonding the nonwoven fiber web, a heat embossing roll with engraving (uneven portions) on the upper and lower pair of roll surfaces, a roll with a flat (smooth) one roll surface, and an engraving on the other roll surface Thermal bonding with various rolls, such as a heat embossing roll made up of a combination of rolls with unevenness and a heat calender roll made up of a pair of upper and lower flat (smooth) rolls, and ultrasonic vibration of the horn For example, a method such as ultrasonic bonding by heat welding is used. Above all, it is excellent in productivity, imparts strength at the partially heat-bonded part, and retains the texture and touch unique to nonwoven fabrics at the non-adhered part, so each of the upper and lower roll surfaces is engraved (uneven part) It is preferable to use a hot embossing roll made of a combination of a roll having a flat (smooth) roll surface and a roll having a sculpture (uneven portion) on the other roll surface. It is an aspect.

  As a surface material of the hot embossing roll, in order to obtain a sufficient thermocompression bonding effect and to prevent the engraving (uneven portion) of one embossing roll from being transferred to the other roll surface, a metal roll and a metal roll are used. Pairing is a preferred embodiment.

  It is preferable that the embossing adhesion area ratio by such a hot embossing roll is 5 to 30%. By making the adhesion area preferably 5% or more, more preferably 8% or more, and further preferably 10% or more, it is possible to obtain strength that can be practically used as a laminated nonwoven fabric. On the other hand, when the adhesion area is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less, it is possible to prevent a decrease in the fibers of the non-crimped part contributing to sound absorption.

  Here, the adhesion area refers to the ratio of the adhesion portion to the entire laminated nonwoven fabric. Specifically, when heat bonding is performed using a roll having a pair of irregularities, the convex portion of the upper roll and the convex portion of the lower roll overlap and occupy the entire laminated nonwoven fabric of the portion that contacts the nonwoven fabric layer (adhesive portion). Say percentage. Moreover, when heat-adhering with the roll which has an unevenness | corrugation, and the flat roll, it says the ratio which the convex part of the roll which has an unevenness | corrugation accounts for the whole laminated nonwoven fabric of the part (adhesion part) which contact | abuts a nonwoven fabric layer. In addition, in the case of ultrasonic bonding, it refers to the ratio of the portion (bonded portion) to be thermally welded by ultrasonic processing to the entire laminated nonwoven fabric.

  As the shape of the bonded portion by hot embossing roll or ultrasonic bonding, a circle, an ellipse, a square, a rectangle, a parallelogram, a rhombus, a regular hexagon, a regular octagon, and the like can be used. Moreover, it is preferable that an adhesion part exists uniformly with a fixed space | interval in the longitudinal direction (conveyance direction) and width direction of a laminated nonwoven fabric, respectively. By doing in this way, the dispersion | variation in the intensity | strength of a laminated nonwoven fabric can be reduced.

  It is a preferable aspect that the surface temperature of the hot embossing roll at the time of heat bonding is set to −50 to −15 ° C. with respect to the melting point of the thermoplastic resin (A) of the fibers constituting the spunbonded nonwoven fabric layer. The surface temperature of the heat roll is preferably −50 ° C. or higher, more preferably −45 ° C. or higher, with respect to the melting point of the thermoplastic resin (A). A nonwoven fabric can be obtained. The surface temperature of the hot embossing roll is preferably −15 ° C. or lower, more preferably −20 ° C. or lower, with respect to the melting point of the thermoplastic resin (A), thereby suppressing excessive thermal bonding and processing. While suppressing the occurrence of breakage due to tearing during or during use, it is possible to prevent the sound absorption effect from being impaired due to a decrease in voids in the laminated nonwoven fabric.

  The linear pressure of the hot embossing roll during thermal bonding is preferably 50 to 500 N / cm. By making the linear pressure of the roll preferably 50 N / cm or more, more preferably 100 N / cm or more, and even more preferably 150 N / cm or more, a laminated nonwoven fabric having a strength that can be appropriately heat-bonded and used for practical use can be obtained. Can do.

  On the other hand, when the linear pressure of the hot embossing roll is preferably 500 N / cm or less, more preferably 400 N / cm or less, and even more preferably 300 N / cm or less, the laminated nonwoven fabric becomes excessively dense and voids are reduced. The sound absorbing effect can be prevented from being impaired.

  Further, in the present invention, for the purpose of adjusting the thickness of the laminated nonwoven fabric, thermocompression bonding can be performed by a thermal calender roll comprising a pair of upper and lower flat rolls before and / or after thermal bonding with the hot embossing roll. it can. A pair of upper and lower flat rolls is a metal roll or elastic roll with no irregularities on the surface of the roll, and a pair of metal roll and metal roll, or a pair of metal roll and elastic roll Can be used.

  Moreover, an elastic roll is a roll which consists of a material which has elasticity compared with a metal roll here. Examples of elastic rolls include so-called paper rolls such as paper, cotton and aramid paper, urethane-based resins, epoxy-based resins, silicone-based resins, polyester-based resins and hard rubbers, and resin-made rolls made of a mixture thereof. It is done.

  Next, based on an Example, the laminated nonwoven fabric of this invention is demonstrated concretely. In the measurement of each physical property, those not specifically described are those measured based on the above method. The test specimens used for each evaluation were collected at equal intervals in the sheet width direction.

(1) MFR of thermoplastic resin:
The MFR of the thermoplastic resin (A) and the thermoplastic resin (B) was measured under the conditions of a load of 2.16 kg and a temperature of 230 ° C.

(2) MFR of laminated fiber (g / 10 min):
The MFR of the laminated nonwoven fabric was measured under the conditions of a load of 2.16 kg and a temperature of 230 ° C.

(3) Spinning speed (m / min):
From the average single fiber diameter and the solid density of the thermoplastic resin (A) used, the mass per 10,000 m in length was calculated as the average single fiber fineness (dtex) by rounding off the second decimal place. . At this time, the solid density of the polypropylene resin made of a homopolymer was 0.91 g / cm ³ for all. Subsequently, from the average single fiber fineness and the discharge amount of the resin discharged from the spinneret single hole set under each condition (hereinafter abbreviated as single hole discharge amount) (g / min), based on the following formula: The spinning speed was calculated and rounded to the nearest tenth.
Spinning speed (m / min) = (10000 × [single hole discharge amount (g / min)]) / [average single fiber fineness (dtex)].

(4) Surface roughness SMD of laminated nonwoven fabric by KES method:
For the measurement, an automated surface tester “KES-FB4-AUTO-A” manufactured by Kato Tech was used. The surface roughness SMD was measured on both sides of the laminated nonwoven fabric, and Table 1 lists the smaller value of these.

(5) Sound absorption performance of laminated nonwoven fabric:
A card web is formed by blending polyester short fibers (melting point 260 ° C.) having a fiber diameter of 25 μm and a fiber length of 51 mm and copolymer polyester short fibers (melting point 135 ° C.) having a fiber diameter of 18 μm and a fiber length of 51 mm in a ratio of 7: 3. The substrate was entangled by needle punching to prepare a substrate having a basis weight of 150 g / m ² and a thickness of 12 mm. A hot melt powder (melting point: 130 ° C.) was applied to the base material and heat bonded to the laminated nonwoven fabric to prepare a measurement sample. About the sample for measurement produced in this way, the sound absorption coefficient by the normal incidence method was measured according to JIS A1405. Table 1 shows the average value of the sound absorption coefficient (%) at 1000 Hz and 2000 Hz as the representative value indicating the sound absorption coefficient in the middle and high sound range, and the value rounded off to the first decimal place. It was judged that it was excellent.

[Example 1]
(Spunbond nonwoven fabric layer (lower layer))
A polypropylene resin made of a homopolymer having an MFR of 200 g / 10 min and a melting point of 163 ° C. is melted by an extruder, and a spinning temperature is 235 ° C. and single hole discharge is performed from a rectangular die having a hole diameter φ of 0.30 mm and a hole depth of 2 mm. Spinning was carried out at a rate of 0.32 g / min. After spinning and solidifying the spun yarn, this was pulled and stretched by a compressed air with an ejector pressure of 0.35 MPa in a rectangular ejector and collected on a moving net. This formed a spunbond nonwoven fibrous web consisting of long polypropylene fibers and having a basis weight of 45 g / m ² . Regarding the properties of the fibers constituting the formed spunbond nonwoven fiber web, the average single fiber diameter was 10.1 μm, and the spinning speed calculated from this was 4,400 m / min. As for the spinnability, no yarn breakage was observed after spinning for 1 hour.

(Melt blown nonwoven layer)
Next, a polypropylene resin composed of a homopolymer having an MFR of 1100 g / min was melted with an extruder, and a spinning temperature of 260 ° C. and a single hole discharge rate of 0.10 g / min were spun from a die having a hole diameter φ of 0.25 mm. I put it out. Thereafter, air was sprayed onto the yarn under conditions of an air temperature of 290 ° C. and an air pressure of 0.10 MPa, and was collected on the spunbonded nonwoven fabric layer to form a meltblown nonwoven fabric layer. At this time, the basis weight of the melt blown nonwoven fiber web separately collected on the collection net under the same conditions was 10 g / m ² and the average fiber diameter was 1.5 μm.

(Spunbond nonwoven fabric layer (upper layer))
Furthermore, on this melt blown nonwoven fiber web, the polypropylene long fiber was collected on the same conditions as the conditions which formed the lower layer spunbond nonwoven fiber web, and the spunbond nonwoven fiber web was formed. As a result, a spunbond-meltblown-spunbond laminated fiber web having a total basis weight of 100 g / m ² was obtained.

(Laminated nonwoven fabric)
Subsequently, a pair of upper and lower hot embossing rolls, each comprising an obtained embossed roll having a bonding area ratio of 16% made of metal and engraved with a polka dot pattern on the upper roll, and a metal flat roll on the lower roll. Was used for thermal bonding under the conditions of a linear pressure of 300 N / cm and a thermal bonding temperature of 140 ° C. to obtain a laminated nonwoven fabric having a basis weight of 100 g / m ² . Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Example 2]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven fiber web was obtained in the same manner as in Example 1 except that the basis weight of each layer was 47.5 g / m ² .

(Melt blown nonwoven layer)
A melt blown nonwoven fiber web was obtained in the same manner as in Example 1 except that the basis weight was 5 g / m ² .

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Example 3]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven fibrous web was obtained in the same manner as in Example 1.

(Melt blown nonwoven layer)
A meltblown nonwoven fiber web was formed in the same manner as in Example 1 except that the air pressure was 0.05 MPa. The fiber constituting the melt blown nonwoven fiber web formed had an average fiber diameter of 3.5 μm.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Example 4]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven fiber web was obtained in the same manner as in Example 1 except that the basis weight of each layer was 35 g / m ² .

(Melt blown nonwoven layer)
A meltblown nonwoven fiber web was formed in the same manner as in Example 1 except that the air pressure was 0.05 MPa and the basis weight was 30 g / m ² . The fiber constituting the melt blown nonwoven fiber web formed had an average fiber diameter of 3.5 μm.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Example 5]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven fiber web was prepared in the same manner as in Example 1 except that the MFR of the homopolymer polypropylene resin was 800 g / 10 min, the melting point was 163 ° C., and the single-hole discharge rate was 0.21 g / min. Formed. Regarding the properties of the fibers constituting the spunbond nonwoven fiber web, the average single fiber diameter was 7.2 μm, and the spinning speed calculated from this was 5,700 m / min. As for the spinnability, no yarn breakage was observed after spinning for 1 hour.

(Melt blown nonwoven layer)
A meltblown nonwoven fibrous web was formed as in Example 1.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Example 6]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven fiber web was prepared in the same manner as in Example 1 except that the MFR of the homopolymer polypropylene resin was 300 g / 10 min, the melting point was 163 ° C., and the single-hole discharge rate was 0.28 g / min. Formed. Regarding the properties of the fibers constituting the formed spunbond nonwoven fiber web, the average single fiber diameter was 8.9 μm, and the spinning speed calculated from this was 5,000 m / min. As for the spinnability, no yarn breakage was observed after spinning for 1 hour.

(Melt blown nonwoven layer)
A meltblown nonwoven fibrous web was formed as in Example 1.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Example 7]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven fiber web was formed in the same manner as in Example 1 except that the MFR of the polypropylene resin made of a homopolymer was 100 g / 10 min and the melting point was 163 ° C. Regarding the properties of the fibers constituting the spunbond nonwoven fiber web, the average single fiber diameter was 10.2 μm, and the spinning speed calculated from this was 4,300 m / min. As for the spinnability, no yarn breakage was observed after spinning for 1 hour.

(Melt blown nonwoven layer)
A meltblown nonwoven fibrous web was formed as in Example 1.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Example 8]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven fiber web was obtained in the same manner as in Example 1 except that 1.0% by mass of ethylenebisstearic acid amide was added as a fatty acid amide compound to a polypropylene resin composed of a homopolymer. Regarding the properties of the fibers constituting the formed spunbond nonwoven fiber web, the average single fiber diameter was 10.1 μm, and the spinning speed calculated from this was 4,400 m / min. As for the spinnability, no yarn breakage was observed after spinning for 1 hour.

(Melt blown nonwoven layer)
A meltblown nonwoven fibrous web was formed as in Example 1.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Comparative Example 1]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
A spunbond nonwoven web was formed in the same manner as in Example 1 except that a polypropylene resin composed of a homopolymer having an MFR of 60 g / 10 min and a melting point of 163 ° C. was used, and the ejector pressure was 0.20 MPa. Regarding the properties of the fibers constituting the formed spunbond nonwoven fiber web, the average single fiber diameter was 11.8 μm, and the spinning speed calculated from this was 3,200 m / min. As for the spinnability, no yarn breakage was observed after spinning for 1 hour. When the ejector pressure was 0.35 MPa under the same conditions, yarn breakage occurred frequently and spinning was impossible.

(Melt blown nonwoven layer)
A meltblown nonwoven fibrous web was obtained in the same manner as in Example 1.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

[Comparative Example 2]
(Spunbond nonwoven fabric layer (lower layer) / (upper layer))
Example 1 except that a polypropylene resin made of a homopolymer having an MFR of 35 g / 10 min, a melting point of 163 ° C., a single hole discharge rate of 0.50 g / min, and an ejector pressure of 0.20 MPa. A spunbond nonwoven fibrous web was formed. Regarding the properties of the fibers constituting the spunbond nonwoven fiber web, the average single fiber diameter was 14.5 μm, and the spinning speed calculated from this was 3,300 m / min.

(Melt blown nonwoven layer)
In the same manner as in Example 2, a melt blown nonwoven fabric layer was obtained.

(Laminated nonwoven fabric)
In the same manner as in Example 1, a laminated nonwoven fabric was obtained. Table 1 shows the results of evaluation of the obtained laminated nonwoven fabric.

The average single fiber diameter of the spunbonded nonwoven fabric is 6.5 to 11.9 μm, the apparent density is 0.05 to 0.4 g / cm ³ , and the longitudinal stress per unit basis weight is 5% when stretched. The laminated nonwoven fabrics of Examples 1 to 8, which are 0.3 to 1.0 (N / 5 cm) / (g / m ² ), have high tensile strength and excellent sound absorption in the mid-high range. Furthermore, the laminated nonwoven fabric of Example 8 in which ethylenebisstearic acid amide is added to the fibers constituting the spunbond nonwoven fabric layer is particularly suitable as a sound absorbing material because of improved slipperiness between fibers and improved sound absorption performance. Met.

On the other hand, the average single fiber diameter of the laminated nonwoven fabric of Comparative Example 1 or the spunbonded nonwoven fabric in which the stress at 5% elongation in the longitudinal direction per unit basis weight is larger than 1.0 (N / 5 cm) / (g / m ² ). The laminated nonwoven fabric of Comparative Example 2 which is larger than 11.9 μm and has a 5% elongation stress in the longitudinal direction per unit weight larger than 1.0 (N / 5 cm) / (g / m ² ) has a tensile strength. It was low and inferior in sound absorption in the mid-high range.

  Since the laminated nonwoven fabric of the present invention has durability that can withstand practical use, is excellent in sound absorbing performance, and is also excellent in moldability, it can be suitably used as a sound absorbing material.

  The laminated nonwoven fabric or the sound absorbing material of the present invention can be processed into a sound insulating sheet, a sound absorbing sheet, etc., and can be used in a wide range of fields including architectural uses, civil engineering uses, transportation uses such as vehicles and airplanes. .

Claims (8)

A laminated nonwoven fabric obtained by laminating a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer, wherein the average single fiber diameter of at least one side of the spunbond nonwoven fabric is 6.5 to 11.9 μm, and the apparent density is 0.05 to The laminated nonwoven fabric which is 0.4 g / cm ³ and has a stress at the time of 5% elongation in the longitudinal direction per unit weight of 0.3 to 1 (N / 5 cm) / (g / m ² ).   The laminated nonwoven fabric according to claim 1, wherein at least one surface has a surface roughness SMD by KES method of 1.0 to 3.0 μm.   The laminated nonwoven fabric according to claim 1 or 2, wherein the content of the meltblown nonwoven fabric layer is 1% by mass or more and 30% by mass or less with respect to the mass of the laminated nonwoven fabric.   The laminated nonwoven fabric according to any one of claims 1 to 3, wherein the melt blown nonwoven has an average single fiber diameter of 0.1 to 6 µm.   The laminated nonwoven fabric according to any one of claims 1 to 4, wherein the meltblown nonwoven fabric is composed of fibers made of a polyolefin resin (B).   The laminated nonwoven fabric according to any one of claims 1 to 5, wherein the spunbonded nonwoven fabric is composed of fibers made of a polyolefin resin (A).   The laminated nonwoven fabric according to any one of claims 1 to 6, wherein the melt flow rate of the laminated nonwoven fabric is 80 to 850 g / 10 minutes.   A sound-absorbing material comprising the laminated nonwoven fabric according to any one of claims 1 to 7.