Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
  • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
  • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H5/00—Non woven fabrics formed of mixtures of relatively short fibres and yarns or like filamentary material of substantial length
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/162—Selection of materials
  • G10K11/168—Plural layers of different materials, e.g. sandwiches

Definitions

• the present invention relates to a nonwoven fabric laminate for use as a sound-absorbing material and a sound-absorbing material comprising the nonwoven fabric laminate for use as a sound-absorbing material.
• Sound-absorbing materials are products that have the function of absorbing sound, and are widely used in the fields of architecture and automobiles. It is known to use nonwoven fabrics as materials that constitute sound-absorbing materials.
• Patent Document 1 discloses a laminated nonwoven fabric as a sound-absorbing material, which includes two or more ultrafine fiber layers made of fibers with an average fiber diameter of less than 10 ⁇ m, includes one or more thick fiber layers made of fibers with an average fiber diameter of 10 to 60 ⁇ m, and includes at least three layers of ultrafine fiber layers and thick fiber layers alternately laminated together.
• Patent Document 2 also discloses a laminated sound-absorbing material that includes at least three fiber layers made of fibers with a fiber diameter of 500 nm or more and less than 35 ⁇ m, and includes a base material layer interposed between the fiber layers.
• nonwoven laminates of various configurations are being considered as sound-absorbing materials, and it is also known to combine multiple layers with different fiber diameters and air permeability (density).
• quietness is becoming more important than ever as one of the commercial values of the product.
• engine noise low to medium frequency range
• road noise low frequency range
• the objective of the present invention is to provide a nonwoven fabric laminate for sound absorption that has excellent sound absorption properties in the low, medium and high frequency ranges, and also has excellent handling properties during molding processing.
• a nonwoven fabric laminate for use as a sound-absorbing material comprising a nonwoven fabric A and a nonwoven fabric B, the nonwoven fabric laminate for use as a sound-absorbing material is formed by alternately laminating at least eight layers of the nonwoven fabric A and the nonwoven fabric B, the nonwoven fabric laminate for use as a sound-absorbing material has a basis weight of 650 g/ m2 or less and a thickness of 50.0 mm or less, each layer of the nonwoven fabric A has a density of 0.050 to 0.200 g/ cm3 and an air permeability of 10.0 to 200.0 cm3 / cm2 /s, and each layer of the nonwoven fabric B has a density of 0.001 to 0.020 g/cm 3 , and a thickness of 1.0 to 10.0 mm, a density ratio of the nonwoven fabric A to the nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) is 5.0 or more and 20.0 or
• a sound-absorbing material comprising the nonwoven fabric laminate for sound-absorbing materials according to any one of (1) to (6).
• nonwoven fabric laminate for sound absorption that has excellent sound absorption performance in all frequency ranges, including low, medium and high frequencies, despite its low basis weight and thickness, and also has excellent handling properties such as three-dimensional conformability when molded with components.
• the nonwoven fabric laminate for sound-absorbing material of the present invention is a nonwoven fabric laminate for sound-absorbing material comprising nonwoven fabric A and nonwoven fabric B, wherein the nonwoven fabric laminate for sound-absorbing material is formed by alternately laminating at least eight layers of the nonwoven fabric A and the nonwoven fabric B, the nonwoven fabric laminate for sound-absorbing material has a basis weight of 650 g/ m2 or less and a thickness of 50 mm or less, the nonwoven fabric A has a density of 0.050 to 0.200 g/ cm3 and an air permeability of 10.0 to 200.0 cm3 / cm2 /s, and the nonwoven fabric B has a density of 0.001 to 0.020 g/cm 3 , and a thickness of 1.0 to 10.0 mm, a density ratio of the nonwoven fabric A to the nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 5.0 or more and 20.0 or less, and a thickness ratio of the nonwoven fabric A to the nonwoven fabric B (non
• the layer of nonwoven fabric A refers to a state in which the nonwoven fabric A is formed into a web shape, and may be simply called nonwoven fabric A.
• the layer of nonwoven fabric B refers to a state in which the nonwoven fabric B is formed into a web shape, and may be simply called nonwoven fabric B.
• the layer of nonwoven fabric A and the layer of nonwoven fabric B may be partially mixed.
• the nonwoven fabric laminate for sound-absorbing material of the present invention is a nonwoven fabric laminate for sound-absorbing material comprising nonwoven fabric A and nonwoven fabric B, and has a feature (feature point 1) in that at least eight layers of nonwoven fabric A and layers of nonwoven fabric B are alternately laminated together.
• the nonwoven fabric A has a density of 0.050 to 0.200 g/cm 3 and an air permeability of 10.0 to 200.0 cm 3 /cm 2 /s
• the nonwoven fabric B has a density of 0.001 to 0.020 g/cm 3 and a thickness of 1.0 to 10.0 mm
• the density ratio of the nonwoven fabrics A to B is 5.0 or more and 20.0 or less
• the thickness ratio of the nonwoven fabrics A to B is 0.25 or less (feature point 2).
• the basis weight of the entire nonwoven fabric laminate for sound absorbing material is 650 g/m 2 or less, and the thickness of the entire nonwoven fabric laminate for sound absorbing material is 50.0 mm or less, and even if the basis weight is low and the thickness is relatively thin, the sound absorbing performance is excellent in all frequency ranges including low frequency range, medium frequency range and high frequency range.
• the nonwoven fabric laminate for sound absorbing material of the present invention has excellent three-dimensional conformability and excellent handling properties when used as a component of an automobile, etc.
• the nonwoven fabric laminate for sound absorption of the present invention can achieve the above-mentioned effect by laminating 8 or more layers of nonwoven fabric A and nonwoven fabric B as a set of constituent units of the nonwoven fabric laminate for sound absorption.
• a set of constituent units of nonwoven fabric A and nonwoven fabric B by setting the density ratio and thickness ratio of nonwoven fabric A having the density and air permeability in the above-mentioned specific range and nonwoven fabric B having the density and thickness in the above-mentioned specific range as described above, the density difference and thickness difference make the reflection of sound when sound is propagated from the sound source complicated, making it difficult for sound to propagate, that is, the attenuation of sound is increased (hereinafter sometimes referred to as the "sound attenuation effect"), resulting in excellent sound absorption performance.
• Nonwoven fabric A and nonwoven fabric B are combined into a set.
• Nonwoven fabric A does not easily reflect external sound, but instead propagates it internally while maintaining sound absorption performance
• nonwoven fabric B which is the back surface as seen from the direction in which the sound is incident, has the effect of enabling sound absorption over a wide frequency range.
• the inventors have found that the sound attenuation effect is excellent by laminating at least 8 layers of nonwoven fabric A and nonwoven fabric B of the present invention. Furthermore, from the above viewpoint, it is more preferable to have 10 layers or more. On the other hand, the upper limit of the number of layers is not particularly limited, but from the viewpoint of making the overall thickness of the nonwoven fabric laminate for sound absorption material thin, it is preferable that it is 20 layers or less.
• nonwoven fabric A and nonwoven fabric B there are at least 4 or more pairs of nonwoven fabric A and nonwoven fabric B as a constituent unit, and the number of layers of nonwoven fabric A and nonwoven fabric B is at least 8 or more.
• the number of layers of nonwoven fabric A and nonwoven fabric B may be an odd number, in which case there will be more nonwoven fabric A or more than the other.
• the basis weight of the nonwoven fabric laminate for sound absorbing material is 650 g/m 2 or less.
• the basis weight of the nonwoven fabric laminate for sound absorbing material of the present invention which is a component of an automobile, is small (lightweight) at 650 g/m 2 or less, which is excellent from the viewpoint of reducing the weight of the entire automobile and improving fuel efficiency.
• the basis weight of the nonwoven fabric laminate for sound absorbing material is preferably 550 g/m 2 or less, and more preferably 500 g/m 2 or less.
• the lower limit of the basis weight of the nonwoven fabric laminate for sound-absorbing material There is no particular restriction on the lower limit of the basis weight of the nonwoven fabric laminate for sound-absorbing material.
• a lower limit of 300 g/ m2 is preferable in order to ensure a certain level of sound absorption performance.
• the thickness of the nonwoven fabric laminate for sound-absorbing material is 50.0 mm or less.
• the thickness of the nonwoven fabric laminate for sound-absorbing material is 50.0 mm or less, preferably 40.0 mm or less, and more preferably 30.0 mm or less.
• the lower limit of the thickness of the nonwoven fabric laminate for sound absorption is not particularly limited, but if the thickness is too thin, the nonwoven fabric laminate of the present invention may be poor in handleability when attached to an automobile or the like. Also, it is preferable that the thickness is 10.0 mm or more in order to form a porous portion of sufficient size in the nonwoven fabric laminate for sound absorption of the present invention, and to make the conversion of sound into thermal energy by air friction when sound penetrates in the thickness direction of the nonwoven fabric for sound absorption more efficient and to ensure a certain level of sound absorption performance.
• the thickness of the nonwoven fabric laminate for sound absorption of the present invention is measured based on JIS L1913:1998 6.1.2 A method, by the thickness when a pressure of 0.36 kPa is applied to the nonwoven fabric.
• the nonwoven fabric laminate for sound absorption material of the present invention has excellent sound absorption performance over a wide frequency range from low to high frequencies, but the sound absorption performance is greatly affected by the air permeability of nonwoven fabric A and the density and thickness ratios of nonwoven fabric A and nonwoven fabric B.
• nonwoven fabric A In order to improve the sound absorption performance over a wide frequency range, sound reflection on the surface of nonwoven fabric A is suppressed and guided to the inside of the nonwoven fabric laminate, the difference in density and thickness between nonwoven fabric A and nonwoven fabric B is increased to complicate the sound reflection and absorption, and at least eight layers of nonwoven fabric A and nonwoven fabric B are laminated to further complicate the sound reflection and absorption by repeating them, thereby achieving excellent sound absorption performance over a wide frequency range even with a low basis weight and a relatively thin thickness.
• the density of the nonwoven fabric A is 0.050 to 0.200 g/cm 3.
• the nonwoven fabric A has a dense porous structure.
• the conversion of sound into thermal energy by air friction becomes efficient, and a minimum level of sound absorption performance can be maintained.
• the density of the nonwoven fabric 0.200 g/cm 3 or less sound reflection on the surface of the nonwoven fabric A can be minimized, and a decrease in sound absorption performance in the high frequency range can be suppressed.
• the nonwoven fabric laminate for sound absorption material using the nonwoven fabric A can be made to have excellent sound absorption performance in a wider frequency range.
• the density of the nonwoven fabric A is 0.050 to 0.200 g/cm 3 , and more preferably 0.070 to 0.190 g/cm 3 .
• the air permeability of the nonwoven fabric A is 10.0 to 200.0 cm 3 /cm 2 /s.
• the air permeability of the nonwoven fabric A is 200.0 cm 3 /cm 2 /s or less.
• High air permeability means that there are many air passages and air can pass through relatively without resistance. Generally, sound is transmitted by vibrations in the air and is attenuated by being converted into thermal energy due to friction between the air and sound-absorbing material. Therefore, having more air passages means that there are fewer opportunities for friction to occur, which makes it harder for sound to be converted into thermal energy, resulting in a lower sound absorption rate.
• the air permeability of the nonwoven fabric A is 10.0 to 200.0 cm 3 /cm 2 /s, more preferably 12.0 to 150.0 cm 3 /cm 2 /s, and even more preferably 12.0 to 100.0 cm 3 /cm 2 /s.
• the density of the nonwoven fabric B is 0.001 to 0.020 g/cm 3.
• the density difference when laminated with the nonwoven fabric A becomes large, and the reflection of sound inside the sound absorbing material becomes complex, so that the sound attenuation effect is efficiently exhibited and the sound absorption performance becomes excellent.
• the density of the nonwoven fabric B is 0.020 g/cm 3 or less, and more preferably 0.015 g/cm 3 or less.
• the density of the nonwoven fabric B is too low, the amount of air per unit space increases, and the sound attenuation effect decreases.
• the nonwoven fabric B needs to have a certain density or more, and from that viewpoint, the density of the nonwoven fabric B is 0.001 g/cm 3 or more, and preferably 0.005 g/cm 3 or more. Therefore, the density of the nonwoven fabric B is 0.001 to 0.020 g/cm 3 , and more preferably 0.005 to 0.015 g/cm 3 .
• the nonwoven fabric B has a thickness of 1.0 to 10.0 mm.
• the thickness of nonwoven fabric B 10.0 mm or less, the overall thickness of the nonwoven fabric laminate for sound absorbing material can be reduced, and the nonwoven fabric laminate for sound absorbing material of the present invention can be made easy to handle. From the above perspective, it is considered that the smaller the thickness of nonwoven fabric B, the better. However, if the thickness is too small, the thickness difference when nonwoven fabric A and nonwoven fabric B are laminated becomes small, making it difficult for the reflection of sound inside the sound absorbing material to become complex, and the sound attenuation effect becomes small, so the thickness of nonwoven fabric B is 1.0 mm or more. For the above reasons, the thickness of nonwoven fabric B is 1.0 to 10.0 mm, and more preferably 1.0 to 8.0 mm or less.
• the density ratio of the nonwoven fabric A to the nonwoven fabric B is 5.0 or more and 20.0 or less.
• the density ratio of the nonwoven fabric A to the nonwoven fabric B is 5.0 or more, it is possible to achieve a minimum sound attenuation effect, i.e., sound absorption.
• the density ratio of the nonwoven fabric A to the nonwoven fabric B is too large, the density of the nonwoven fabric A is too high, or the density of the nonwoven fabric B is too low, resulting in a nonwoven fabric laminate.
• the density ratio of the nonwoven fabric A to the nonwoven fabric B is 20.0 or less. From the above viewpoints, the density ratio of the nonwoven fabric A to the nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) is 5.0 or more and 20.0 or less, and preferably 6.0 or more and 19.0 or less.
• the thickness ratio of the nonwoven fabric A to the nonwoven fabric B is 0.25 or less.
• the lower limit of the thickness ratio of the nonwoven fabric A to the nonwoven fabric B is not particularly limited, but from the viewpoint that if the thickness ratio is too small, the thickness of the nonwoven fabric B will be large, and as a result, the thickness of the entire nonwoven fabric laminate for sound absorbing material will be large, it is preferable that it is 0.01 or more.
• nonwoven fabric A has a density of 0.050 to 0.200 g/ cm3 and an air permeability in the range of 10.0 to 200.0 cm3 / cm2 /s
• nonwoven fabric B has a density of 0.001 to 0.020 g/ cm3 and a thickness in the range of 1.0 to 10.0 mm
• the density ratio of nonwoven fabric A to nonwoven fabric B is 5.0 or more and 20.0 or less
• the thickness ratio of nonwoven fabric A to nonwoven fabric B is 0.25 or less.
• the effects of the present invention can be achieved by alternately laminating eight or more layers of nonwoven fabric A and nonwoven fabric B.
• nonwoven fabric A and nonwoven fabric B are alternately laminated to form a nonwoven fabric laminate for sound absorption material, and it is preferable that nonwoven fabric A is laminated as the outermost surface on at least one surface of the nonwoven fabric laminate, and further, when the nonwoven fabric laminate for sound absorption material is used as a sound absorbing material, it is preferable to place it so that nonwoven fabric A is on the sound source side.
• alternately laminated refers to a state in which nonwoven fabric B is laminated on at least one adjacent surface of nonwoven fabric A, and nonwoven fabric A is further laminated on at least one adjacent surface of nonwoven fabric B.
• a unit in which a layer of nonwoven fabric B is laminated on at least one surface of a layer of nonwoven fabric A is considered to be one constituent unit, and is denoted as "nonwoven fabric A/nonwoven fabric B.”
• nonwoven fabric A/nonwoven fabric B When multiple sets of one set of constituent units are laminated to form a sound-absorbing nonwoven fabric laminate, the constituent units adjacent to the constituent unit "nonwoven fabric A/nonwoven fabric B" may be laminated in the reverse order of "nonwoven fabric B/nonwoven fabric A".
• the lamination order of each nonwoven fabric A and nonwoven fabric B of the nonwoven fabric may be "nonwoven fabric A/nonwoven fabric B/nonwoven fabric A/nonwoven fabric B....nonwoven fabric A/nonwoven fabric B/nonwoven fabric A/nonwoven fabric B" or "nonwoven fabric A/nonwoven fabric B/nonwoven fabric B/nonwoven fabric A....nonwoven fabric A/nonwoven fabric B/nonwoven fabric B/nonwoven fabric A".
• the basis weight when a web is obtained using short fibers through a carding process, the basis weight can be adjusted by the input amount of short fibers, the cylinder rotation speed of the carding machine, and the doffer speed, and when a web is made from long fibers by the spunbond method or meltblown method, the basis weight and thickness can be adjusted by the distance between the nozzle and the collecting device, the collecting net conveyor, and the rotation speed of the collecting device.
• the thickness can also be adjusted during the entanglement process of the nonwoven fabric.
• the thickness can be adjusted by the needle density and the number of entanglement processes, and in the case of the water jet punch method, the thickness can be adjusted by the pressure of the water jet punch nozzle and the number of entanglement processes, i.e., the density can be adjusted.
• the air permeability of a nonwoven fabric is generally related to the density and the single fiber diameter and fineness of the constituent fibers. If the density is high, the air permeability is low, and if the density is low, the air permeability tends to be high.
• Nonwoven fabric A is preferably a nonwoven fabric with a single fiber diameter of 1.0 to 25.0 ⁇ m, and this nonwoven fabric with a single fiber diameter of 1.0 to 25.0 ⁇ m may be composed of short fibers or long fibers. As mentioned above, it is preferable that nonwoven fabric A is the outermost surface, so a nonwoven fabric made of long fibers is preferable because it is less likely to tear and has higher strength.
• Nonwoven fabric A is preferably a nonwoven fabric made of long fibers, and specifically, it is preferably a meltblown nonwoven fabric or a spunbond nonwoven fabric.
• Nonwoven fabric A is the layer that is thinner than nonwoven fabric B.
• thermoplastic resins such as polyester resins, polyamide resins, acrylic resins, and polyolefin resins can be used as the material for the fibers that make up nonwoven fabric A.
• nonwoven fabric A is preferably made of acrylic resins, polyester resins, and polyolefin resins, which have excellent heat resistance, that is, which can reduce deformation and discoloration of the nonwoven fabric for sound absorption in the high-temperature environment when used in the engine compartment of an automobile, etc., and more preferably made of acrylic resins, polyethylene terephthalate resins, and polypropylene resins, which have excellent heat resistance.
• nonwoven fabric B contains multiple types of short fibers with different fibers. It is preferable that nonwoven fabric B contains 10 to 30 mass% of short fiber A with a fineness of 0.4 to 0.9 dtex. By making the fineness of short fiber A 0.9 dtex or less, it is possible to form a porous part with many fine holes inside nonwoven fabric B by short fiber A. As a result, when sound passes through the gaps between the fibers (i.e., the porous part), the sound can be efficiently converted into heat by air friction with the fibers surrounding the gaps, and excellent sound absorption can be obtained when nonwoven fabric B is used as a nonwoven fabric laminate for sound absorption material.
• short fiber A is uniformly dispersed inside nonwoven fabric B in the carding process for preparing the nonwoven fabric, and the generation of short fiber A as fiber clumps is suppressed, thereby improving the quality of nonwoven fabric B. Furthermore, if the fineness of short fiber A is 0.9 dtex or less, the short fiber A that is uniformly dispersed inside nonwoven fabric B can form a porous portion with many fine holes, resulting in excellent sound absorption performance when used as a sound absorbing material.
• the fineness of the short fiber A is preferably 0.4 to 0.9 dtex, more preferably 0.5 to 0.8 dtex, and even more preferably 0.5 to 0.7 dtex.
• the short fiber A used in the nonwoven fabric B of the present invention has a fineness of 0.4 to 0.9 dtex. Therefore, this short fiber A can be produced by the melt spinning method or the wet spinning method.
• the productivity of the nonwoven fabric B of the present invention is superior to the productivity of the nonwoven fabric for sound absorbing material, which requires the method of removing the sea-island fiber or the electrospinning method in the manufacturing process.
• the short fibers A having a small fineness can form a porous portion having many fine holes inside the nonwoven fabric B, and when sound passes through the gaps between the fibers (i.e., the porous portion), the sound can be efficiently converted into heat by air friction with the fibers surrounding the gaps, and excellent sound absorption can be obtained when used as a sound absorbing material.
• the short fibers A having a fineness of 0.4 to 0.9 dtex are contained in 10 to 30% by mass with respect to the total mass of the nonwoven fabric B, and more preferably 15 to 25% by mass.
• the nonwoven fabric B is composed of a plurality of fibers having different finenesses, and the fiber having the smallest fineness among the fibers having different finenesses is called the short fiber A.
• the nonwoven fabric B further contains short fiber B, short fiber C, and short fiber D with different finenesses of 1.1 to 10.0 dtex, and that the short fiber B, short fiber C, and short fiber D together account for 70 to 90 mass%.
• the nonwoven fabric B may contain only short fiber B, or both short fiber B and short fiber C, and the total of these may account for 70 to 90 mass% of the total mass of the nonwoven fabric B, in which case short fiber C and/or short fiber D will be 0 mass%.
• nonwoven fabric B it is important that staple fiber A, staple fiber B, staple fiber C, and staple fiber D are dispersed.
• the upper limit of the fineness of staple fiber B, staple fiber C, and staple fiber D 10.0 dtex
• excellent sound absorption can be obtained when used as a sound absorbing material without inhibiting the formation of fine porous parts by staple fiber A with a small fineness.
• the lower limit of the fineness of staple fiber B, staple fiber C, and staple fiber D to 1.1 dtex, staple fiber A is uniformly dispersed inside nonwoven fabric B in the carding process, and the generation of fiber lumps of staple fiber A inside nonwoven fabric B is suppressed, improving the quality of nonwoven fabric B.
• nonwoven fabric B by uniformly dispersing staple fiber A, porous parts with many fine holes can be formed inside nonwoven fabric B, and this nonwoven fabric has excellent sound absorption performance when used as a sound absorbing material. Furthermore, it suppresses breakage of short fibers A during the carding process and winding around card cloth, thereby improving the productivity of nonwoven fabrics for sound absorption.
• the size of the microscopic holes formed inside nonwoven fabric B varies from large to small.
• the gaps between the fibers i.e., the porous parts
• air friction with the fibers surrounding the gaps occurs more randomly, allowing the sound to be converted into heat more efficiently, and excellent sound absorption can be obtained over a wide frequency range up to the high frequency range when used as a sound absorbing material.
• the relatively small fineness of short fibers A and the relatively large fineness of short fibers B, C, and D cause short fibers A, B, C, and D to be uniformly dispersed inside the nonwoven fabric during the carding process, suppressing the generation of fiber agglomerates inside nonwoven fabric B, and the uniform dispersion of short fibers A allows a porous portion having many fine holes to be formed inside nonwoven fabric B, which results in excellent sound absorption performance when this nonwoven fabric B is used to form a nonwoven fabric laminate for sound absorption material.
• the fineness of short fiber B is smaller than that of short fiber C, and that the fineness of short fiber C is smaller than that of short fiber D.
• the fineness of short fiber A which has a relatively small fineness, does not become extremely small compared to the fineness of short fiber B among the relatively large short fibers B, short fiber C, and short fiber D, and the occurrence of short fiber A as a fiber mass inside nonwoven fabric B is suppressed, and short fiber A can be dispersed more uniformly.
• the fineness of short fiber B is smaller than that of short fiber C, and that the fineness of short fiber C is smaller than that of short fiber D. From the above viewpoint, it is more preferable that the fineness of short fiber B is 1.1 to 4.5 dtex, the fineness of short fiber C is more preferably 4.0 to 6.5 dtex, and the fineness of short fiber D is more preferably 6.0 to 10.0 dtex.
• nonwoven fabric B contains 10-30% by mass of staple fiber A, 25-35% by mass of staple fiber B, 20-30% by mass of said staple fiber C, and 20-30% by mass of said staple fiber D, and is a mixed fiber nonwoven fabric having staple fibers A, B, C, and D.
• staple fibers A, B, C, and D are as described above, the effect of the different finenesses of the staple fibers is synergistically exerted, and staple fibers A, B, C, and D are more uniformly dispersed inside nonwoven fabric B, resulting in a nonwoven fabric of excellent quality.
• thermoplastic resins such as polyester resins, polyamide resins, acrylic resins, and polyolefin resins can be used.
• the staple fibers A are preferably short fibers made of acrylic resins (acrylic short fibers) or polyester resins (polyester short fibers) because they have excellent heat resistance, that is, they can reduce deformation and discoloration of the sound-absorbing nonwoven fabric in a high-temperature environment when used in the engine room of an automobile, and among these, short fibers made of acrylic resins or short fibers made of polyethylene terephthalate resins, which have excellent heat resistance, are more preferable.
• these thermoplastic resins may be those obtained by polymerizing multiple types of monomers, or may contain additives such as stabilizers.
• the staple fibers B, C, and D is a thermally adhesive fiber.
• the thermally adhesive fiber used preferably contains a component whose melting point is 20°C or more lower than the melting point of the other staple fibers constituting nonwoven fabric B, and the thermally adhesive fiber may be a fiber made of a single component or a composite fiber made of multiple components.
• nonwoven fabric B is melt-bonded with a thermally adhesive fiber, not only can the strength and rigidity of nonwoven fabric B after thermal processing be increased, making it easier to maintain its thickness and preventing sagging, but also the interlayer peeling between nonwoven fabric A and nonwoven fabric B can be suppressed when nonwoven fabric A and nonwoven fabric B are laminated, and the dimensional stability of the nonwoven fabric laminate for sound absorption itself can be improved when used as a sound absorption material.
• nonwoven fabric B contains thermally adhesive fibers
• the proportion is preferably 20% by mass or more.
• a more preferable lower limit for the proportion of thermally adhesive fibers is 25% by mass. If the proportion of thermally adhesive fibers contained in nonwoven fabric B is less than 20% by mass, sufficient effects cannot be obtained in improving the strength of the nonwoven fabric or in maintaining its thickness and voids. Generally, if the proportion of thermally adhesive fibers contained exceeds 80% by mass, the effects of maintaining bulkiness and thickness may not be sufficient.
• the nonwoven fabric B provided in the nonwoven fabric laminate for sound absorbing material of the present invention contains staple fiber A, staple fiber B, staple fiber C, and staple fiber D.
• a preferred method for producing the nonwoven fabric of the present invention has the following steps. In addition, the steps (a), (b), and (c) described below do not have to be performed in this order, and for example, the step (c) and the steps (a) and (b) may be performed simultaneously.
• a layer of nonwoven fabric A is formed by the step (a) of obtaining nonwoven fabric A
• a layer of nonwoven fabric B is formed by the step (b) of obtaining nonwoven fabric B.
• the preferred manufacturing method for obtaining nonwoven fabric A is a method in which a nonwoven fabric is produced directly from the spinning process using a spunbond method or meltblown method that forms continuous long fibers.
• Nonwoven fabrics made of continuous long fibers such as those made by the spunbond method or meltblown method, are generally stronger and less likely to tear than short-fiber nonwoven fabrics made of short fibers, and are therefore preferred because they also provide excellent strength to the entire nonwoven fabric laminate for sound-absorbing materials using nonwoven fabric A.
• nonwoven fabric A is preferably a meltblown nonwoven fabric or a spunbond nonwoven fabric.
• meltblowing method specifically, a thermoplastic resin is fed into a heated extruder, melt extrusion is performed, and the molten resin is discharged from a nozzle using a meltblowing nozzle, and heated air is blown onto the discharged molten resin to thin it, and then the fibers are collected on a collection net to obtain nonwoven fabric A.
• spunbond method molten thermoplastic resin is spun from a spinneret as long fibers, the spun threads are cooled and solidified, and then sucked and stretched by compressed air using an ejector, and the fibers are collected on a moving net to obtain nonwoven fabric A.
• the process for obtaining nonwoven fabric B can be divided into (a) a process for opening staple fibers A, B, C, and D (opener process), (b) a process for forming staple fibers A, B, C, and D into a web (carding process), and (c) a process for entangling staple fibers A, B, C, and D with needles or water jets to obtain a nonwoven fabric (entanglement process), each of which is explained below.
• the process of opening up staple fibers A, B, C, and D generally and preferably involves weighing staple fibers A, B, C, and D (hereinafter also referred to as each staple fiber) so that the content of staple fibers A, B, C, and D in nonwoven fabric B is the desired amount, and then using air or the like to fully open up each staple fiber and mix them together.
• the process for forming staple fibers A, B, C, and D into a web is generally and preferably performed by drawing the mixed staple fibers obtained in the opener process together with clothed rollers to obtain a web.
• the needle density is preferably 200 fibers/ cm2 or more and the entanglement treatment is performed. More preferably, the needle density is 250 fibers/ cm2 or more, and particularly preferably, 300 fibers/ cm2 or more.
• the above needle density is preferable because it allows the nonwoven fabric B to be appropriately densified and improves the sound absorbing performance when the nonwoven fabric B is used to form a nonwoven fabric laminate for sound absorbing material.
• the nonwoven fabric When entangling the short fibers by the water jet punch method, it is preferable to pass the nonwoven fabric through the water nozzle three or more times at a water jet punch nozzle pressure of 12.0 MPa or more.
• the nonwoven fabric can be densified, which is preferable because it improves the sound absorption performance when the nonwoven fabric is used as a sound absorbing material.
• the nonwoven fabric can be densified, which is preferable because it improves the sound absorption performance when the nonwoven fabric is used as a sound absorbing material.
• a method of passing the nonwoven fabric through the water nozzle there is a method of passing the nonwoven fabric through the water nozzle once, winding it up, and then passing it through the water nozzle again, but in terms of improving productivity, a method of passing the nonwoven fabric through the water nozzle three or more times in succession is preferable.
• the surface of the nonwoven fabric for sound absorption that contacts the nozzle surface does not need to be constant.
• the surface of the nonwoven fabric for sound absorption that faces upward and contacts the nozzle surface when passing through the water nozzle for the first time is called the “surface” and the opposite surface is called the "back surface"
• the surface from which the water flow from the nozzle i.e.
• the surface that contacts the nozzle surface can be arbitrarily set, for example, as “surface”/"back surface”/"surface” or “surface”/"back surface”/”back surface” when passing through the water nozzle three times, or as “surface”/"surface”/"back surface”/"surface”/”back surface” when passing through the water nozzle five times.
• water nozzles with a hole diameter of ⁇ 0.1 mm x pitch of 0.6 mm x 1 row or a hole diameter of ⁇ 0.08 mm x pitch of 0.6 mm x 2 rows are generally preferred.
• the needle punch method is preferable to water flow entanglement. This is because the needle punch method creates an appropriate distance between the entanglement points, making it possible to produce a nonwoven fabric with an appropriate density.
• this entanglement process may be carried out after the process of alternately stacking nonwoven fabrics A and B (c) described later.
• step (c) of alternately laminating layers of nonwoven fabric A and layers of nonwoven fabric B will be described.
• a method for alternately laminating layers of nonwoven fabric A and layers of nonwoven fabric B there is a method of laminating the nonwoven fabric A and nonwoven fabric B in the number of layers after the step of obtaining (a) nonwoven fabric A and (b) nonwoven fabric B, and setting the laminated sheets in a heat treatment machine, as well as a method of preparing a precursor (hereinafter also referred to as nonwoven fabric precursor) by overlapping nonwoven fabric A and nonwoven fabric B, and folding the nonwoven fabric precursor multiple times to finally laminate eight or more layers of nonwoven fabric A and nonwoven fabric B alternately.
• nonwoven fabric precursor hereinafter also referred to as nonwoven fabric precursor
• nonwoven fabric precursors As the latter method of preparing a nonwoven fabric precursor and folding it multiple times, specifically, the following method can be mentioned.
• the laminate of nonwoven fabric precursors By laminating nonwoven fabric A on the web of nonwoven fabric B after passing through the carding process and passing it through a cross wrapper or parallel wrapper, the laminate of nonwoven fabric precursors can be further laminated multiple times, and finally eight or more layers of nonwoven fabric A and nonwoven fabric B can be laminated alternately.
• nonwoven fabric A and nonwoven fabric B are alternately stacked in four or more layers, and the nonwoven fabric precursor is entangled by a needle punch method or the like, and then the web is folded in an accordion shape using a heat treatment machine to form pleats, and then the pleats are laid down with a roller and heat-treated at 130° C. to form a laminate structure, ultimately forming a laminate structure of eight or more layers.
• the former is preferred in that the lamination of nonwoven fabric A and nonwoven fabric B can be completed online, and is therefore highly productive.
• nonwoven fabric A and nonwoven fabric B are alternately laminated to form a nonwoven fabric laminate for sound absorption material, and it is preferable that they are laminated so that the outermost surface of the nonwoven fabric laminate for sound absorption material is nonwoven fabric A, and further, when the nonwoven fabric laminate for sound absorption material is used as a sound absorbing material, it is preferable to place it so that nonwoven fabric A faces the sound source. Therefore, in the manufacturing method using the nonwoven fabric precursor described above, one of the surfaces will ultimately be nonwoven fabric B, and in that case, a structure can be created in which nonwoven fabric A is further laminated on the outermost layer where nonwoven fabric B is exposed.
• the measurement method used in this example is shown below.
• ms m/S ms: mass per unit area (g/m 2 ) m: average mass (g) of the test piece of the nonwoven fabric for sound absorption S: area (m 2 ) of the test piece of the sound-absorbing nonwoven fabric.
• Ratio of density of nonwoven fabric A to density of nonwoven fabric B density of nonwoven fabric A (g/cm 3 )/density of nonwoven fabric B (g/cm 3 ) (5) Thickness ratio of nonwoven fabric A to nonwoven fabric B: Calculated from the thickness of nonwoven fabric A and the thickness of nonwoven fabric B calculated in (2) above according to the following formula.
• Ratio of thickness of nonwoven fabric A to thickness of nonwoven fabric B thickness of nonwoven fabric A (mm) / thickness of nonwoven fabric B (mm) (6) Air permeability of nonwoven fabric A Measured according to JIS L 1096-1999 8.27.1 A method (Fragile type method). Five test pieces of 200 mm x 200 mm were taken from a sample of nonwoven fabric for sound absorption. Using a Frazier type testing machine, the test pieces were attached to one end (air intake side) of a cylinder. When attaching the test pieces, the test pieces were placed on the cylinder, and a load of about 98 N (10 kgf) was evenly applied from above the test pieces so as not to block the air intake part, to prevent air leakage at the attachment part of the test pieces.
• the suction fan was adjusted using a rheostat so that the inclined barometer indicated a pressure of 125 Pa.
• the amount of air passing through the test specimens ( cm3 / cm2 /s) was calculated using the table attached to the testing machine from the pressure indicated by the vertical barometer at that time and the type of air hole used, and the average value for the five test specimens was calculated.
• Normal incidence sound absorption coefficient of nonwoven fabric laminate for sound absorbing material Measured according to the normal incidence sound absorption coefficient measurement method (transfer function method) of JIS A 1405-2 (2007). Three circular test pieces with diameters of 39.5 mm and 14.5 mm were taken from the sample of the nonwoven fabric laminate for sound absorbing material for low frequency region measurement and high frequency region measurement, respectively. As the test device, a normal incidence sound absorption coefficient measurement system WinZacMTX (manufactured by Nihon Onkyo Engineering Co., Ltd.) was used. The taken test pieces were attached to a predetermined position of the impedance tube for measurement. At this time, the test pieces were attached so that the thickness of the nonwoven fabric laminate for sound absorbing material was not crushed and became smaller than the original thickness.
• WinZacMTX manufactured by Nihon Onkyo Engineering Co., Ltd.
• the sound absorption coefficient for each frequency was adopted as a value obtained by multiplying the sound absorption coefficient obtained by measurement by 100.
• the average value of the obtained sound absorption coefficient at 1000 Hz was taken as the low frequency sound absorption coefficient (%).
• the results were judged according to the following rankings, with 40% or more being considered a pass. 60% or more: Excellent ⁇ 40% or more: Good ⁇ Less than 40%: Bad ⁇
• the normal incidence sound absorption coefficient (%) at 1000 Hz is a value that represents the sound absorption coefficient in the low frequency range.
• the normal incidence sound absorption coefficient (%) in the mid-frequency range of 1000 to 5000 Hz and the high-frequency range of 5000 to 12000 Hz is higher than the normal incidence sound absorption coefficient (%) at 1000 Hz. Therefore, the normal incidence sound absorption coefficient (%) at 1000 Hz was used as the evaluation index.
• Sound absorption performance total index of nonwoven fabric laminate for sound absorbing material The integral value of the sound absorption coefficient from 120 to 12000 Hz obtained in the measurement of (7) was taken as the sound absorption performance total index, which indicates the sound absorption performance of the nonwoven fabric laminate for sound absorbing material when the sound absorption performance in the entire frequency range is viewed from a bird's-eye view.
• a sound absorption performance total index exceeding 10000 was evaluated as passing, and one below 10000 was evaluated as failing.
• the cross-sectional shape of the fiber was an irregular cross-sectional shape
• the cross-sectional area of the fiber was measured from the cross-sectional photograph, and the cross-sectional area was converted to a perfect circular diameter to obtain the single fiber diameter of the fiber.
• the obtained single fiber diameter data was sharply divided into 0.1 ⁇ m intervals, and the average single fiber diameter for each interval and the number of fibers for each interval were tallied.
• the fineness (dtex) was calculated from the average single fiber diameter for each section and the specific gravity of each short fiber according to formula (1).
• Fineness (dtex) (average single fiber diameter ( ⁇ m)/2) 2 ⁇ 3.14 ⁇ specific gravity of short fiber/100 ... formula (1)
• the content (mass%) of fibers having a fineness of 0.4 to 0.9 dtex was calculated from the fineness of each section, the number of fibers in each section, and the specific gravity of the fiber material.
• the content of short fiber A in each section was calculated by the following formula (2).
• nonwoven fabric B contained a plurality of fibrous materials
• the above-mentioned measurements of fineness and content were carried out for each fibrous material using the residual nonwoven fabric in the dissolution method, and the fineness and content of the fibers constituting nonwoven fabric B were determined.
• Example 1 For nonwoven fabric A, polypropylene resin was fed to an extruder, melted at 260°C, and extruded from a melt-blowing die. Heated air at 300°C was blown toward the resin fluid discharged during this process, and the resin was layered on a wire mesh deposition device to produce a melt-blown nonwoven fabric made of polypropylene resin with an average fiber diameter of 1.3 ⁇ m, a basis weight of 10 g/ m2 , and an air permeability of 19.5 cm3 / cm2 /s.
• short fibers A made of polyethylene terephthalate resin with a fineness of 0.7 dtex and a fiber length of 51 mm
• short fibers B made of polyester resin with a fineness of 2.2 dtex and a fiber length of 51 mm
• short fibers C made of polyethylene terephthalate resin with a fineness of 4.4 dtex and a fiber length of 51 mm
• short fibers D made of polyethylene terephthalate resin with a fineness of 6.6 dtex and a fiber length of 51 mm were used, and each short fiber was subjected to an opener process.
• the short fibers A were mixed in a ratio of 20 mass% to the total mass of the nonwoven fabric B, 30 mass% to the short fibers B, 25 mass% to the short fibers C, and 25 mass% to the short fibers D.
• the short fibers B were thermally adhesive fibers.
• the nonwoven fabric B was subjected to a carding process (cylinder rotation speed 300 rpm, doffer speed 10 m/min).
• nonwoven fabric B having a basis weight of 40 g/ m2 , a thickness of 5.0 mm, and a density of 0.008 g/ cm3 .
• the obtained nonwoven fabrics A and B were alternately laminated in 12 layers to finally obtain a nonwoven fabric laminate having a basis weight of 300 g/ m2 , a thickness of 30.6 mm, a density ratio of nonwoven fabrics A to B (nonwoven fabric A/nonwoven fabric B) of 11.9, and a thickness ratio of nonwoven fabrics A to B of 0.02.
• the normal incidence sound absorption coefficient of the obtained nonwoven fabric laminate was measured, and the normal incidence sound absorption coefficient (%) at 1000 Hz and the total sound absorption performance index were calculated.
• An overall evaluation of the sound absorption performance and an evaluation of the handleability were also performed, and the results are shown in Table 1.
• Example 2 As nonwoven fabric A, a meltblown nonwoven fabric having an air permeability of 26.2 cm3 / cm2 /s was prepared from polypropylene resin having an average fiber diameter of 1.7 ⁇ m and a basis weight of 20 g/ m2 in the same manner as in Example 1.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabrics A and B were alternately laminated in 10 layers to finally obtain a nonwoven fabric laminate having a basis weight of 300 g/ m2 , a thickness of 26.2 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 10.7, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.05.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 1.
• Example 3 Nonwoven fabric A and nonwoven fabric B were prepared in the same manner as in Example 2, and the obtained nonwoven fabrics A and B were alternately laminated in 12 layers to finally obtain a nonwoven fabric laminate having a basis weight of 360 g/ m2 , a thickness of 31.4 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 10.7, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.05.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 1.
• Example 4 As nonwoven fabric A, a meltblown nonwoven fabric with an air permeability of 26.2 cm3 / cm2 /s was prepared from polypropylene resin with an average fiber diameter of 1.7 ⁇ m and a basis weight of 20 g/ m2 in the same manner as in Example 2.
• As nonwoven fabric B the same procedure as in Example 1 was carried out, but the conditions of the entanglement process after the carding process were changed as follows: After the entanglement process by needle punching (2 passes with 200 needles/ cm2 ), the fabric was set at 120°C in a heat treatment process to obtain nonwoven fabric B with a basis weight of 80 g/ m2 , a thickness of 10.0 mm, and a density of 0.008 g/ cm3 .
• the obtained nonwoven fabrics A and B were alternately laminated in eight layers to finally obtain a nonwoven fabric laminate having a basis weight of 400 g/ m2 , a thickness of 41.0 mm, a density ratio of nonwoven fabrics A to B (nonwoven fabric A/nonwoven fabric B) of 10.7, and a thickness ratio of nonwoven fabrics A to B of 0.10.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 1.
• Example 5 As the nonwoven fabric A, polypropylene resin was fed to an extruder, melted at a temperature of 260°C, and spun out from a die. After the spun yarn was cooled and solidified, it was pulled and stretched by compressed air in a rectangular ejector and collected on a moving net to produce a spunbond nonwoven fabric having an air permeability of 124.3 cm3 / cm2 / s , made of polypropylene resin with an average fiber diameter of 12.2 ⁇ m and a basis weight of 30 g/m2.
• Nonwoven fabric B was produced in the same manner as in Example 1, and the obtained nonwoven fabrics A and B were alternately laminated in 10 layers to finally obtain a nonwoven fabric laminate having a basis weight of 350 g/ m2 , a thickness of 26.6 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 11.7, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.06.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 1.
• Example 6 As nonwoven fabric A, a meltblown nonwoven fabric having an air permeability of 10.4 cm3 / cm2 /s was prepared from polypropylene resin having an average fiber diameter of 1.7 ⁇ m and a basis weight of 40 g/ m2 in the same manner as in Example 2.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabrics A and B were alternately laminated in 10 layers to finally obtain a nonwoven fabric laminate having a basis weight of 400 g/ m2 , a thickness of 27.4 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 10.7, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.10.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 1.
• Example 7 As nonwoven fabric A, a spunbond nonwoven fabric having an air permeability of 31.1 cm3 / cm2 /s and made of polypropylene resin having an average fiber diameter of 8.4 ⁇ m and a basis weight of 57 g/m2 was prepared in the same manner as in Example 5.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabrics A and B were alternately laminated in 10 layers to finally obtain a nonwoven fabric laminate having a basis weight of 485 g/ m2 , a thickness of 26.9 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 18.8, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.08.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 1.
• nonwoven fabric A a spunbond nonwoven fabric having an air permeability of 65.7 cm3 / cm2 /s was prepared from polypropylene resin having an average fiber diameter of 12.2 ⁇ m and a basis weight of 60 g/ m2 in the same manner as in Example 5.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabrics A and B were alternately laminated in 10 layers to finally obtain a nonwoven fabric laminate having a basis weight of 500 g/ m2 , a thickness of 28.4 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 11.7, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.13.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 2.
• Example 9 As the nonwoven fabric A, a meltblown nonwoven fabric with an air permeability of 19.5 cm 3 /cm 2 /s was prepared by the same method as in Example 1, which was made of polypropylene resin with an average fiber diameter of 1.3 ⁇ m and a basis weight of 10 g/m 2.
• As the nonwoven fabric B short fibers A made of polyethylene terephthalate resin with a fineness of 4.4 dtex and a fiber length of 51 mm, and short fibers B made of polyethylene terephthalate resin with a fineness of 14.4 dtex and a fiber length of 64 mm were used, and each short fiber was subjected to an opener process.
• the short fibers A were mixed so that the ratio of short fibers A to the total mass of the nonwoven fabric B was 25% by mass and short fibers B were 75% by mass.
• the nonwoven fabric was subjected to a carding process (cylinder rotation speed 300 rpm, doffer speed 10 m/min). Thereafter, the resultant was subjected to an entanglement process by needle punching under the following conditions (2 passes with 200 needles/ cm2 ), and then heat-treated at 120°C to obtain nonwoven fabric B having a basis weight of 40 g/ m2 , a thickness of 5.0 mm, and a density of 0.008 g/ cm3 .
• the obtained nonwoven fabrics A and B were alternately laminated in 14 layers to finally obtain a nonwoven fabric laminate having a basis weight of 350 g/ m2 , a thickness of 35.7 mm, a density ratio of nonwoven fabrics A to B (nonwoven fabric A/nonwoven fabric B) of 7.6, and a thickness ratio of nonwoven fabrics A to B of 0.02.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 2.
• Example 10 As the nonwoven fabric A, a meltblown nonwoven fabric having an air permeability of 26.2 cm 3 /cm 2 /s was prepared from polypropylene resin having an average fiber diameter of 1.7 ⁇ m and a basis weight of 20 g/m 2 in the same manner as in Example 1. As the nonwoven fabric B, a nonwoven fabric B having a basis weight of 30 g/m 2 , a thickness of 2.3 mm, and a density of 0.013 g/cm 3 was obtained in the same manner as in Example 9.
• the obtained nonwoven fabrics A and B were alternately laminated in 16 layers, and finally a nonwoven fabric laminate having a basis weight of 400 g/m 2 , a thickness of 20.3 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 6.5, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.21 was obtained.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 2.
• nonwoven fabric A a spunbond nonwoven fabric having an air permeability of 31.1 cm3 / cm2 /s was prepared from polypropylene resin having an average fiber diameter of 8.4 ⁇ m and a basis weight of 57 g/ m2 in the same manner as in Example 5.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabrics A and B were alternately laminated in 12 layers to finally obtain a nonwoven fabric laminate having a basis weight of 582 g/ m2 , a thickness of 32.3 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 18.8, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.08.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 2.
• Example 12 Nonwoven fabric A and nonwoven fabric B were prepared in the same manner as in Example 2, and the obtained nonwoven fabrics A and B were laminated alternately in 18 layers to finally obtain a nonwoven fabric laminate having a basis weight of 540 g/ m2 , a thickness of 47.2 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 10.7, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.05.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 2.
• Nonwoven fabric A was prepared in the same manner as in Example 9, and nonwoven fabric B was prepared in the same manner as in Example 1.
• the obtained nonwoven fabrics A and B were alternately laminated in 16 layers to finally obtain a nonwoven fabric laminate having a basis weight of 400 g/ m2 , a thickness of 40.8 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 11.9, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.02.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 2.
• nonwoven fabric A a meltblown nonwoven fabric having an air permeability of 26.2 cm3 / cm2 /s was prepared from polypropylene resin having an average fiber diameter of 1.7 ⁇ m and a basis weight of 20 g/ m2 in the same manner as in Example 2.
• nonwoven fabric B having a basis weight of 20 g/ m2 , a thickness of 2.5 mm, and a density of 0.008 g/cm3 was obtained in the same manner as in Example 1.
• the obtained nonwoven fabrics A and B were used to laminate nonwoven fabric A and nonwoven fabric B to prepare a nonwoven fabric precursor, which was then folded 8 times to laminate 32 layers of nonwoven fabric A and nonwoven fabric B, finally obtaining a nonwoven fabric laminate with a basis weight of 640 g/ m2 , a thickness of 40 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 13.1, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.08.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 2.
• Example 1 A laminated web containing the following mixed fiber web was used as nonwoven fabric A.
• the mixed fiber web was a sea-island composite fiber.
• Polyethylene terephthalate (PET melt viscosity: 160 Pa s) as an island component and polyethylene terephthalate copolymerized with 8.0 mol % of 5-sodium sulfoisophthalic acid (copolymerized PET melt viscosity: 95 Pa s) as a sea component were melted at 290°C separately, weighed, and fed into a spinning pack incorporating a known composite spinneret (for example, a composite spinneret having an arrangement as disclosed in FIG.
• a composite spinneret having an arrangement as disclosed in FIG.
• the mixed fiber web and the web were laminated to obtain a laminated web, which was then entangled five times by a water jet punching method under pressure conditions of 8.0 MPa on the upper surface, 10.0 MPa on the upper surface, 13.5 MPa on the lower surface, 16.0 MPa on the upper surface, and 13.5 MPa on the lower surface to obtain a laminated nonwoven fabric.
• the laminated nonwoven fabric was then immersed in a 0.5% by mass aqueous solution of sodium hydroxide heated to 95°C for 30 minutes to remove the sea component, and dried in a hot air dryer at 130°C for 10 minutes to obtain a nonwoven fabric A having a basis weight of 240 g/ m2 and an air permeability of 14.0 cm3 / cm2 /s.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabrics A and B were laminated alternately in eight layers to finally obtain a nonwoven fabric laminate having a basis weight of 1120 g/ m2 , a thickness of 26.4 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 18.8, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.32.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorbing material in Comparative Example 1 had good sound absorbing performance, but the basis weight of the nonwoven fabric laminate was large and it was poor in handleability.
• nonwoven fabric A a meltblown nonwoven fabric having an air permeability of 26.2 cm3 / cm2 /s and made of polypropylene resin having an average fiber diameter of 1.7 ⁇ m and a basis weight of 20 g/ m2 was prepared in the same manner as in Example 1.
• Nonwoven fabric B was prepared in the same manner as in Example 4, and the obtained nonwoven fabrics A and B were laminated alternately in six layers to finally obtain a nonwoven fabric laminate having a basis weight of 300 g/ m2 , a thickness of 30.7 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 10.7, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.10.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorption in Comparative Example 2 had a small number of layers of nonwoven fabric A and nonwoven fabric B, a low sound absorption coefficient in the low frequency range, and inferior sound absorption performance.
• Example 4 number of layers: 8
• the sound absorption coefficient in the low frequency range at 1000 Hz in Example 4 was 54
• Comparative Example 2 number of layers: 6
• the sound absorption coefficient was 39, a significant decrease.
• a mixed fiber web was obtained by subjecting the mixed fiber web to an opener process and a carding process after subjecting the short fibers to an opener process and a carding process, and then entanglement processing was performed on the mixed fiber web by a water jet punch method under pressure conditions of 8.0 MPa on the upper surface, 10.0 MPa on the upper surface, 13.5 MPa on the lower surface, 16.0 MPa on the upper surface, and 13.5 MPa on the lower surface, five passes, and then drying was performed at a temperature of 130°C for 10 minutes in a hot air dryer to obtain a nonwoven fabric A having a basis weight of 220 g/ m2 and an air permeability of 20.0 cm3 / cm2 /s.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and 10 layers of the obtained nonwoven fabrics A and B were laminated alternately to finally obtain a nonwoven fabric laminate having a basis weight of 1300 g/ m2 , a thickness of 31.0 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 22.9, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.24.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorbing material of Comparative Example 3 had good sound absorbing performance, but the basis weight of the nonwoven fabric laminate was large and the handleability was poor. It was not possible to achieve both sound absorbing performance and handleability.
• Example 4 As the nonwoven fabric A, a meltblown nonwoven fabric with an air permeability of 7.1 cm 3 /cm 2 /s was prepared from polypropylene resin with an average fiber diameter of 1.3 ⁇ m and a basis weight of 30 g/m 2 in the same manner as in Example 1.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabric A and nonwoven fabric B were alternately laminated in 10 layers, and finally a nonwoven fabric laminate with a basis weight of 350 g/m 2 , a thickness of 26.5 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 11.9, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.06 was obtained.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorbing material of Comparative Example 4 had poor sound absorbing performance, and it was presumed that this was because the air permeability of nonwoven fabric A was small and the reflection of sound on the surface, especially in the high frequency range, was large.
• Example 5 a spunbonded nonwoven fabric with an air permeability of 201.3 cm 3 /cm 2 /s was prepared from polypropylene resin with an average fiber diameter of 22.2 ⁇ m and a basis weight of 42 g/m 2 in the same manner as in Example 5.
• the nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabric A and nonwoven fabric B were alternately laminated in 10 layers, finally obtaining a nonwoven fabric laminate with a basis weight of 410 g/m 2 , a thickness of 27.0 mm, a density ratio (nonwoven fabric A/nonwoven fabric B) of 13.5 between the nonwoven fabric A and the nonwoven fabric B, and a thickness ratio of 0.08 between the nonwoven fabric A and the nonwoven fabric B.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorbing material of Comparative Example 5 had poor sound absorbing performance, and it was presumed that this was because the air permeability of the nonwoven fabric A was too high, making it difficult to exhibit the sound attenuation effect inside the sound absorbing material.
• Example 6 a meltblown nonwoven fabric with an air permeability of 5.4 cm 3 /cm 2 /s was prepared by the same method as in Example 1 , which was made of a polypropylene resin with an average fiber diameter of 1.3 ⁇ m and a basis weight of 40 g/m 2.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabric A and nonwoven fabric B were alternately laminated in 10 layers, and finally a nonwoven fabric laminate with a basis weight of 400 g/m 2 , a thickness of 27.0 mm, a density ratio (nonwoven fabric A/nonwoven fabric B) of 11.9 between nonwoven fabric A and nonwoven fabric B, and a thickness ratio of 0.08 between nonwoven fabric A and nonwoven fabric B was obtained.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorbing material of Comparative Example 6 had poor total sound absorption performance, which was presumed to be due to the small air permeability of nonwoven fabric A, which increased the reflection of sound on the surface, especially in the high frequency range.
• Example 7 a meltblown nonwoven fabric with an air permeability of 6.8 cm 3 /cm 2 /s was prepared by the same method as in Example 1 , which was made of a polypropylene resin with an average fiber diameter of 1.7 ⁇ m and a basis weight of 60 g/m 2.
• Nonwoven fabric B was prepared in the same manner as in Example 1, and the obtained nonwoven fabric A and nonwoven fabric B were alternately laminated in 10 layers, and finally a nonwoven fabric laminate with a basis weight of 500 g/m 2 , a thickness of 28.6 mm, a density ratio (nonwoven fabric A/nonwoven fabric B) of 10.7 between nonwoven fabric A and nonwoven fabric B, and a thickness ratio of 0.01 between nonwoven fabric A and nonwoven fabric B was obtained.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorbing material of Comparative Example 7 had poor total sound absorption performance, which was presumed to be due to the small air permeability of nonwoven fabric A, which increased the reflection of sound on the surface, especially in the high frequency range.
• Example 8 As the nonwoven fabric A, a meltblown nonwoven fabric with an air permeability of 26.2 cm 3 /cm 2 /s was prepared by the same method as in Example 1, which was made of polypropylene resin with an average fiber diameter of 1.7 ⁇ m and a basis weight of 20 g/m 2.
• As the nonwoven fabric B short fibers A made of polyethylene terephthalate resin with a fineness of 4.4 dtex and a fiber length of 64 mm, and short fibers B made of polyethylene terephthalate resin with a fineness of 6.6 dtex and a fiber length of 51 mm were used, and each short fiber was subjected to an opener process.
• the short fibers A were mixed so that the ratio of the short fibers A to the total mass of the nonwoven fabric B was 20% by mass and the short fibers B were 80% by mass. Then, the fibers were subjected to a carding process (cylinder rotation speed 300 rpm, doffer speed 10 m/min). Thereafter, the resultant was subjected to an entanglement process by needle punching under the following conditions (2 passes with 60 needles/ cm2 ), and then heat-treated at 140°C to obtain nonwoven fabric B having a basis weight of 30 g/ m2 , a thickness of 2.3 mm and a density of 0.013 g/ cm3 .
• the obtained nonwoven fabrics A and B were alternately laminated in six layers to finally obtain a nonwoven fabric laminate having a basis weight of 150 g/ m2 , a thickness of 7.5 mm, a density ratio of nonwoven fabrics A to B (nonwoven fabric A/nonwoven fabric B) of 6.5, and a thickness ratio of nonwoven fabrics A to B of 0.21.
• the evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorption material in Comparative Example 8 was poor in handleability due to its too small basis weight and thickness, and also had a small number of layers, so it did not exhibit a sufficient sound attenuation effect and was poor in sound absorption performance.
• Nonwoven fabric A was prepared in the same manner as in Comparative Example 2, and nonwoven fabric B was prepared in the same manner as in Example 1. Five layers of nonwoven fabric A were laminated from the sound source side of each of the obtained nonwoven fabrics, and then five layers of nonwoven fabric B were laminated, totaling 10 layers. Finally, a nonwoven fabric laminate was obtained with a basis weight of 300 g/ m2 , a thickness of 26.2 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 18.8, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.08. The evaluation results of the obtained nonwoven fabric laminate are shown in Table 3. In the nonwoven fabric laminate for sound absorbing material of Comparative Example 9, since nonwoven fabric A and nonwoven fabric B were not alternately laminated, sufficient sound attenuation effect was not exhibited, and the sound absorbing performance was also inferior.
• Nonwoven fabric A and nonwoven fabric B were prepared in the same manner as in Comparative Example 9, and 5 layers of nonwoven fabric B were laminated on each of the obtained nonwoven fabrics from the sound source side, and then 5 layers of nonwoven fabric A were laminated, for a total of 10 layers. Finally, a nonwoven fabric laminate was obtained with a basis weight of 300 g/m 2 , a thickness of 26.2 mm, a density ratio of nonwoven fabric A to nonwoven fabric B (nonwoven fabric A/nonwoven fabric B) of 18.8, and a thickness ratio of nonwoven fabric A to nonwoven fabric B of 0.08. The evaluation results of the obtained nonwoven fabric laminate are shown in Table 3.
• the nonwoven fabric laminate for sound absorbing material of Comparative Example 10 did not exhibit sufficient sound attenuation effect because nonwoven fabric A and nonwoven fabric B were not alternately laminated, and the sound absorbing performance was also inferior. Furthermore, since nonwoven fabric A was not arranged on the sound source side, the sound absorbing performance was inferior to that of Comparative Example 9.
• the nonwoven fabric laminate for sound absorption of the present invention has excellent sound absorption performance in all frequency ranges from low to high, and has a small basis weight and thickness, making it easy to handle, making it particularly suitable for use as a sound absorption material for automobiles, etc.

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• Engineering & Computer Science (AREA)
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• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Textile Engineering (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Nonwoven Fabrics (AREA)

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• 2023
  • 2023-12-13 JP JP2023577876A patent/JPWO2024135484A1/ja active Pending
  • 2023-12-13 WO PCT/JP2023/044569 patent/WO2024135484A1/ja not_active Ceased

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