Meltblown nonwoven fabrics, laminates, and sound-absorbing materials for vehicles

Abstract

The present invention provides a meltblown (MB) nonwoven fabric, a laminate using the same, a method for manufacturing the meltblown nonwoven fabric, and a meltblowing device. The meltblowing device (100) comprises a die (10) for ejecting a resin melt (42) and an accompanying flow, a hollow cover (20), and a collecting member (60). The ejected filaments (50) from the die (10) are heated to a temperature above the crystallization temperature of the thermoplastic resin inside the hollow cover (20) and are collected by a collecting surface (62) of the collecting member (60). On a straight line perpendicularly downward from the nozzle hole (12), the hollow cover (20) and the collecting member (60) are separated by more than 5 cm in terms of the distance from the lower end (28) of the hollow cover (20) to the collecting surface (62).

Description

[0001] This application is a divisional application of an application with an application date of July 30, 2018, application number 201880051667.0, and invention name “Meltblown nonwoven fabric, laminate using the same, method for manufacturing meltblown nonwoven fabric, and meltblowing device”.

[0002] Related applications

[0003] This application claims the benefit of Japanese Patent Application No. 2017-155193, filed in Japan on August 10, 2017, which is hereby incorporated by reference in its entirety as a part of this application. Technical Field

[0004] The present invention relates to a melt-blown nonwoven fabric having excellent thermal stability and a soft feel, a laminate using the same, and a method for producing the melt-blown nonwoven fabric and a melt-blowing device. Existing technology

[0005] Polyethylene terephthalate (PET) resin is used in various nonwoven fabric forms due to its high versatility, but meltblown (MB) nonwoven fabrics have seen little development. This is due to the slower crystallization rate of PET compared to other crystalline polymers widely used in meltblown nonwoven fabrics. Specifically, the slow crystallization rate of PET resin prevents sufficient crystallinity from being achieved during meltblowing, resulting in reduced thermal stability of the resulting meltblown (MB) nonwoven fabric. MB nonwoven fabrics with such low thermal stability will shrink significantly when left to stand at temperatures exceeding PET's glass transition temperature (approximately 130°C), for example, 70 to 80°C, or 200°C.

[0006] For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 3-045768) describes a method for producing MB nonwoven fabric. The method includes subjecting a web formed by meltblowing PET resin to a dry heat treatment at a temperature of 180°C or lower, thereby crystallizing the PET resin without exceeding a crystallinity of 30%. The method also describes that the resulting MB nonwoven fabric has a hot water surface shrinkage of 20% or less.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 3-045768

[0010] Summary of the Invention

[0011] Problems to be solved by the invention

[0012] However, Patent Document 1 requires an additional heat treatment step for the web, and since the web itself is heated, the resulting nonwoven fabric has a harder feel. Furthermore, the thermal stability of this MB nonwoven fabric at temperatures above 100°C, for example, 200°C, is uncertain. Furthermore, this production method only yields a nonwoven fabric with lower strength than MB nonwoven fabrics made from conventional readily crystallizable polymers.

[0013] Therefore, an object of the present invention is to provide a PET-based MB nonwoven fabric that has a small area shrinkage under 200° C. conditions and can impart a soft feel, and a laminate using the same.

[0014] Another object of the present invention is to provide a melt-blowing method (or a method for producing MB nonwoven fabric) and a melt-blowing apparatus that can impart a soft feel to a thermoplastic resin MB nonwoven fabric and improve thermal stability.

[0015] Methods for solving problems

[0016] The inventors of the present invention conducted intensive research to achieve the above-mentioned objectives and discovered that (i) first, because the meltblowing method does not involve a post-spinning stretching step, when molecules are easily moved by heating, excessive thermal shrinkage may occur due to the inherent tendency of PET molecules to form curls. Further research revealed that (ii) by providing a heating zone after meltblowing, crystallization of the PET molecules is promoted while the accompanying flow exerts a pseudo-stretching effect, thereby suppressing thermal shrinkage even at high temperatures of 200°C for PET-based MB nonwoven fabrics. Furthermore, as a new challenge, the inventors discovered that this compromises the soft feel of the MB nonwoven fabric. To address this new challenge, further research revealed that (iii) by allowing the ejected filaments to travel together with the accompanying flow within a predetermined air-gap region following the heating zone, an MB nonwoven fabric exhibiting both thermal stability and a soft feel can be obtained, thereby completing the present invention.

[0017] That is, the present invention can be constructed as follows.

[0018] [Method 1]

[0019] A meltblown nonwoven fabric is composed of a resin composition containing a polyethylene terephthalate resin as a main component, has an area shrinkage of 20% or less at 200°C, and a 10% modulus in the longitudinal direction of 22 N / 5 cm or less at 30°C.

[0020] [Method 2]

[0021] According to the melt-blown nonwoven fabric described in embodiment 1, the tensile strength (TMD ) is more than 10N / 5cm, and the longitudinal tensile strength (T MD ) and transverse tensile strength (T CD ) ratio (T MD / T CD ) is 1.00~1.40.

[0022] [Method 3]

[0023] The melt-blown nonwoven fabric according to embodiment 1 or 2 has a longitudinal elongation (E MD ) is more than 25%, and the longitudinal elongation (E MD ) and transverse elongation (E CD ) ratio (E MD / E CD ) is 0.80~1.20.

[0024] [Method 4]

[0025] The meltblown nonwoven fabric according to any one of aspects 1 to 3, wherein the air permeability measured according to JIS L 1906 is 30 to 90 cm 3 / cm 2 ·s.

[0026] [Method 5]

[0027] The meltblown nonwoven fabric according to any one of aspects 1 to 4, which is used for a vehicle sound absorbing material.

[0028] [Method 6]

[0029] A laminate comprising a support and a meltblown nonwoven fabric bonded to at least one surface of the support by thermal compression, wherein the meltblown nonwoven fabric is the meltblown nonwoven fabric described in any one of Embodiments 1 to 5.

[0030] [Method 7]

[0031] According to the laminate according to embodiment 6, in the laminate, the peel strength (T-peel) measured in accordance with JIS K 6854-3 at the thermocompression-bonded surface between the meltblown nonwoven fabric and the support is 0.2 N / 5 cm or more.

[0032] [Method 8]

[0033] The laminate according to embodiment 6 or 7, wherein the support is composed of nonwoven fabric or felt.

[0034] [Method 9]

[0035] A sound absorbing material for vehicles, comprising the laminate according to any one of aspects 6 to 8.

[0036] [Method 10]

[0037] A method for manufacturing a meltblown nonwoven fabric comprises the following steps:

[0038] In the ejection step, a resin composition containing a crystalline thermoplastic resin is heated and melted, and the melt is ejected from a nozzle hole together with an accompanying flow (an air flow accompanying the molten ejected material);

[0039] The heating process makes the filaments ejected from the nozzle hole in the heating area

[0040] Medium heat;

[0041] a cooling step of exposing the heated ejected filament to external air in an air gap region for cooling; and

[0042] a collecting step of collecting the cooled ejected filaments on a collecting surface to obtain a web;

[0043] in,

[0044] In the heating region, at least a portion of the space is heated to a temperature equal to or higher than the crystallization temperature of the crystalline thermoplastic resin, and

[0045] The air gap area is the space between the lower end of the heating area and the collecting surface. On a straight line vertically downward from the nozzle hole, the distance L between the lower end of the heating area and the collecting surface is greater than 5 cm.

[0046] [Method 11]

[0047] According to the method for producing a meltblown nonwoven fabric according to embodiment 10, a distance H between the nozzle hole and the lower end of the heating region on a straight line perpendicularly downward from the nozzle hole is 10 cm or more.

[0048] [Method 12]

[0049] The method for producing a melt-blown nonwoven fabric according to embodiment 10 or 11, wherein the temperature of the ejected filaments at a position 10 cm vertically downward from the nozzle hole in the heating zone is not less than the crystallization temperature (Tc) - 25°C.

[0050] [Method 13]

[0051] The production method according to any one of aspects 10 to 12, wherein the crystalline thermoplastic resin is a polyethylene terephthalate-based resin.

[0052] [Method 14]

[0053] A melt-blowing device, comprising at least:

[0054] an extrusion section for heating and melting a resin composition containing a crystalline thermoplastic resin;

[0055] a die for ejecting the heated and molten resin melt together with an accompanying flow;

[0056] a hollow cover portion provided on the downstream side of the accompanying flow and configured to surround the ejected filament ejected from the die;

[0057] a heating device for heating the ejected filaments to a given temperature (for example, above the crystallization temperature of a crystalline thermoplastic resin); and

[0058] a collecting member having a collecting surface for collecting the ejected filaments flowing from the hollow cover toward the downstream direction of the accompanying flow,

[0059] in,

[0060] On a straight line vertically downward from the nozzle hole, the hollow cover is spaced at least 5 cm from the collecting member in terms of the distance from the lower end of the hollow cover to the collecting surface.

[0061] [Method 15]

[0062] The meltblowing device according to embodiment 14, wherein a distance from the nozzle hole to the lower end of the hollow cover portion on a straight line perpendicularly downward from the nozzle hole is 10 cm or more.

[0063] [Method 16]

[0064] The meltblowing device according to aspect 14 or 15, wherein a blowing port for allowing heated air to flow in is formed in the hollow cover.

[0065] Effects of the Invention

[0066] According to the MB nonwoven fabric of the present invention, a PET-based MB nonwoven fabric having a soft hand and excellent thermal stability even at a high temperature of 200° C. and a laminate using the same can be obtained.

[0067] In addition, in the present invention, by setting a specific heating area and air gap area after spinning, a melt blowing method and melt blowing device can be obtained that can impart a soft feel and improve thermal stability even when using a crystalline thermoplastic resin (especially a resin with a slow crystallization rate). BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and explanation purposes only and are not intended to limit the scope of the present invention. The scope of the present invention is determined by the appended claims.

[0069] Figure 1 This is a schematic cross-sectional view showing a meltblowing device in one embodiment of the present invention.

[0070] Figure 2 It shows Figure 1 A schematic enlarged cross-sectional view of the meltblowing device from the mold 10 to the collecting surface 62 of the collecting member 60.

[0071] Figure 3 This is a photograph of the MB nonwoven fabric obtained in Example 1 after the heating test.

[0072] Figure 4 This is a photograph of the MB nonwoven fabric obtained in Example 2 after the heating test.

[0073] Figure 5 This is a photograph of the MB nonwoven fabric obtained in Comparative Example 2 after the heating test.

[0074] Explanation of symbols

[0075] 100 Meltblown device

[0076] 10 mold

[0077] 12 nozzle holes

[0078] 14 Hot air injection slots

[0079] 20 Hollow cover

[0080] 22 Blowing into the mouth

[0081] 24 Heated air flow

[0082] 26 heating zones

[0083] 28 Lower end of the heating area (lower end of the hollow cover)

[0084] 30 Air gap area

[0085] 40 Extrusion Department

[0086] 50 Spraying filaments

[0087] 60 Collection Components

[0088] 62 Collection Surface DETAILED DESCRIPTION

[0089] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments shown in the drawings.

[0090] (Meltblowing method and meltblowing device)

[0091] Figure 11 is a schematic cross-sectional view showing a meltblowing device in one embodiment of the present invention, Figure 2 It shows Figure 1 Schematic enlarged cross-sectional view of the meltblowing device from the mold 10 to the collecting surface 62 of the collecting member 60. Figure 1 As shown, in the meltblowing device 100, a resin composition containing at least a crystalline thermoplastic resin (e.g., polyethylene terephthalate) is heated and melted in the extrusion section 40, and the resin melt 42 is introduced into the die 10. Then, the ejected filaments 50 ejected from the die 10 advance toward the collecting surface 62 of the collecting member 60.

[0092] like Figure 2 As shown, the mold 10 has a nozzle hole 12 for ejecting a resin melt 42 and hot air injection slots 14, 14 provided on both sides of the nozzle hole 12. And, along with the accompanying flow ejected from the hot air injection slots 14, 14, the ejected filament (or molten resin fiber) 50 ejected from the nozzle hole 12 is first heated in the heating area 26 after being ejected. The heating area 26 is surrounded by a hollow cover 20 provided on the downstream side of the above-mentioned accompanying flow, and is heated by a heating device 23 such as a hot air jet. With such a structure, the temperature of at least a part of the space of the above-mentioned heating area 26 (for example, 5 cm below the nozzle hole) can be made higher than the crystallization temperature (Tc) of the above-mentioned thermoplastic resin. From the viewpoint of efficient heating, the heating device 23 preferably heats the ejected filament 50 from the side of the hollow cover 20. This

[0093] Here, the crystallization temperature is a temperature measured in accordance with JIS K 7121.

[0094] A hollow cover 20 is provided below the nozzle hole 12 of the die 10 on the downstream side of the accompanying flow, with a spacer (not shown) provided as needed. The upper and lower ends of the hollow cover 20 may be open or may have openings to allow the ejected filaments 50 to pass through.

[0095] The temperature of the ejected filament 50 ejected from the nozzle hole 12 typically drops rapidly after ejection, making it difficult to promote crystallization of a thermoplastic resin with a slow crystallization rate. However, since the heating area 26 contains a space heated to a temperature above the crystallization temperature (Tc) of the thermoplastic resin, crystallization of the ejected filament 50 can be promoted even for a thermoplastic resin with a slow crystallization rate.

[0096] Next, perhaps because the filaments 50 are subjected to pseudo-tensile force from the accompanying flow during the ejection stage and crystallization is promoted, the thermal stability of the MB nonwoven fabric can be improved, and for example, significant shrinkage of the nonwoven fabric can be suppressed when exposed to high temperatures.

[0097] The at least part of the space heated in the heating region 26 is not particularly limited as long as it can promote the crystallinity of the ejected filament 50 in the heating region 26, but is preferably located near the nozzle hole 12. Here, the area near the nozzle hole can be, for example, a hemispherical space with a radius of 5 cm centered on the nozzle hole.

[0098] The vertical length of the heated area can be represented by a distance H, which is the distance from the upper end to the lower end of the heated area 26 on a straight line extending vertically downward from the nozzle hole 12 provided in the mold 10. This distance H generally corresponds to the distance from the nozzle hole 12 to the lower end 28 of the hollow cover portion 20 on a straight line extending vertically downward from the nozzle hole. It should be noted that if the lower end of the hollow cover portion 20 has a non-uniform shape in the vertical direction, the lower end of the hollow cover portion 20 may be the uppermost portion of the lower end of the hollow cover portion 20 in a figure projected from the front side of the hollow cover portion 20, i.e., in a front view.

[0099] The distance H can be appropriately set depending on the temperature of the heating region 26. For example, it can be 10 cm or greater, preferably 10.5 cm or greater, and more preferably 11 cm or greater. The upper limit is not particularly limited unless it impairs the effects of the present invention. However, from the perspective of increasing the elongation of the MB nonwoven fabric, it can be approximately 18 cm.

[0100] When no heating zone is provided, the ejected filaments are exposed to the outside air after ejection and cool rapidly. However, in the present invention, since a heating zone adjusted to a specific temperature is provided, even after ejection, rapid cooling of the ejected filaments can be suppressed. For example, the temperature of the ejected filaments collected at a position 10 cm vertically downward from the nozzle hole 12 can be, for example, (Tc - 25)°C or higher, preferably (Tc - 20)°C or higher. The upper limit can be appropriately set within a range that promotes crystallization of the ejected filaments 50. For example, from the perspective of economic efficiency, it can be set to be Tc + 10°C or lower, preferably Tc° or lower.

[0101] For example, the temperature of the ejected filaments collected at a position 10 cm vertically downward from the nozzle hole 12 is, for example, 105° C. or higher, and preferably 110° C. or higher in the case of a polyethylene terephthalate resin composition.

[0102] The heating device (heat source) 23 for heating the heating area 26 is not particularly limited as long as it can heat the interior of the hollow cover 20, and examples thereof include a heater, a hot air jet, etc. From the viewpoint of heating efficiency, a hot air jet is preferred. For example, Figure 2As shown, the hollow cover 20 is formed with blowing ports 22, 22 for allowing the heated air flow 24 from the hot air jet 23 to flow in. In this case, the heated air flow 24, 24 is ejected toward the front and back of the ejected filament 50 through the blowing ports 22, 22. The heated air flow 24, 24 can be injected into the entire ejected filament 50, or can be injected toward a portion of the ejected filament 50 (for example, near the nozzle hole). The shape of the blowing port is not particularly limited as long as it can introduce hot air into the interior of the hollow cover 20. A single or multiple circular, polygonal, or other windows can be arranged in the hollow cover. For example, from the perspective of uniformly heating the ejected filament along the width direction, the blowing ports 22, 22 can have a width that is approximately the same as the width of the ejected filament (for example, the arrangement width of the multiple nozzle holes 12 formed in the mold 10).

[0103] The temperature of the heated air flow 24 ejected from the blowing ports 22, 22 is not particularly limited as long as it can keep the heating area at a given temperature. For example, it can be selected from a wide range of about (Tc+30)°C to (Tc+250)°C, preferably about (Tc+40)°C to (Tc+240)°C. In addition, the air volume per 1m of the nozzle width is preferably within a range that does not hinder the progress of the ejected filaments, for example, 0.5 to 5 Nm 3 / min, preferably 1 to 3 Nm 3 / minute or so.

[0104] After passing through the heating region 26 , the ejected filaments 50 are exposed to the outside air and cooled in the air gap region 30 . In the air gap region 30 , the ejected filaments 50 flow toward the collecting member 60 together with the accompanying flow, and are collected on the collecting surface 62 after traveling through a predetermined range of the air gap region 30 .

[0105] The length of the air gap area 30 in the vertical direction can be represented by a distance L, which is the distance from the lower end 28 of the heating area 26 (or the lower end 28 of the hollow cover 20) to the collecting surface 62 of the collecting member 60 on a straight line perpendicularly downward from the nozzle hole 12 provided in the mold 10. The distance L is usually equivalent to the height from the lower end 28 of the hollow cover 20 to the collecting surface 62. It should be noted that when the lower end 28 of the hollow cover 20 and the collecting surface 62 of the collecting member 60 have uneven shapes in the vertical direction, the distance L can be the distance from the uppermost part of the lower end of the hollow cover 20 to the collecting surface 62 of the collecting member 60 in the figure projected from the front side of the hollow cover 20 and the collecting member 60, that is, in the front view.

[0106] The length of the uppermost portion of surface 62.

[0107] To impart a soft feel to the ejected filaments 50 as they pass through the heated area 26 along with the accompanying flow, the distance L must be at least 5 cm. The ejected filaments 50, which undergo pseudo-stretching and accelerated crystallization in the heated area, then flow through the air gap area 30 along with the accompanying flow, maintaining their crystallized state while achieving a large web volume. This results in a soft feel for the resulting MB nonwoven fabric. The distance L is preferably at least 6 cm, more preferably at least 8 cm. While the upper limit of the distance L is not particularly limited, it can be approximately 15 cm to improve collection efficiency.

[0108] The sum of the distance H of the heating area and the distance L of the air gap area (H+L) can be, for example, about 13 cm to 30 cm, preferably about 15 cm to 28 cm, and more preferably about 18 cm to 25 cm. Furthermore, the distance H of the heating area and the distance L of the air gap area can be, for example, 1<H / L<3.5, or 1<H / L<2, and preferably 1<H / L<1.5.

[0109] In addition, regarding the accompanying flow ejected from the hot air ejection slots 14, 14, for example, the hot air temperature during ejection can be appropriately set according to the melting temperature of the resin composition used, for example, it can be set to the same level as the ejection temperature of the resin composition. In addition, the ejection speed can be appropriately set within a range that can exert a pseudo-stretching effect on the ejected filament 50 in the heating area and can untie the ejected filament 50 in the air gap area 30. For example, the air volume per 1m of the nozzle width can be 5 to 30Nm 3 / min, preferably 10 to 25 Nm 3 / minute or so.

[0110] The collecting member 60 is not particularly limited as long as it is a member commonly used as a collecting member when manufacturing MB nonwoven fabrics. It can be a rotating roller or a conveyor belt. Figure 1 As shown, the collecting member 60 may be a unidirectional circulating conveyor belt, which collects the ejected filaments 50 on the collecting surface 62 , and continuously forms the MB nonwoven fabric 52 as the conveyor belt rotates.

[0111] (Meltblown nonwoven fabric)

[0112] In the melt-blowing method, by performing specific treatment at the stage of ejecting the filaments together with the accompanying flow from the nozzle, it is possible to produce MB nonwoven fabrics having excellent thermal stability at high temperatures and a soft feel for crystalline thermoplastic resins.

[0113] For example, the MB nonwoven fabric is composed of a resin composition containing a crystalline thermoplastic resin as a main component. When the melting point of the crystalline thermoplastic resin is set to Tm, for example, the area shrinkage at (Tm×3 / 4)°C is 20% or less (preferably 17% or less, more preferably 16% or less), and the 10% modulus (M in the longitudinal direction (MD direction) at 30°C is MD ) is 22 N / 5 cm or less. Examples of the crystalline thermoplastic resin include thermoplastic resins such as polyolefins, polyamides, and polyesters. The resin composition preferably contains 50% by mass or more of the crystalline thermoplastic resin, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 98% by mass or more.

[0114] The resin composition may contain additives such as matting agents such as titanium oxide, barium sulfate, and zinc sulfide, heat stabilizers such as phosphoric acid and phosphorous acid, light stabilizers, antioxidants, and surface treatment agents such as silicon oxide. These additives may be added to the polymerization system before the crystalline thermoplastic resin is obtained by polymerization, or may be added after polymerization when the crystalline thermoplastic resin is heated and melted.

[0115] In particular, according to the above-mentioned meltblowing method, even when a polyethylene terephthalate (PET) resin with a slow crystallization rate is used, the thermal shrinkage of the PET-based MB non-woven fabric can be effectively suppressed, and a PET-based MB non-woven fabric with good thermal stability at high temperatures and a soft feel can be manufactured.

[0116] For example, such a PET-based MB nonwoven fabric is composed of a resin composition containing a PET-based resin as a main component. Here, "PET-based resin as a main component" means that the resin components constituting the resin composition contain 50% or more of a PET-based resin, preferably 80% or more, more preferably 90% or more, and particularly preferably 98% or more. It should be noted that the term "MB nonwoven fabric" is not limited to PET-based MB nonwoven fabrics. In particular, when referring to MB nonwoven fabrics specifically made of PET-based resin, it may be referred to as a PET-based MB nonwoven fabric.

[0117] The PET-based resin is composed of units derived from ethylene glycol and units derived from terephthalic acid, and may contain less than 2.0 mol% of a copolymer component depending on the intended use.

[0118] The MB nonwoven fabric of the present invention (particularly PET-based MB nonwoven fabric) can achieve improved thermal stability around 200°C, which is unattainable with conventional PET-based MB nonwoven fabrics, and can also achieve an area shrinkage of 20% or less at 200°C. This area shrinkage is preferably 17% or less, and more preferably 16% or less. The area shrinkage is measured using the method described in the Examples below. By reducing this area shrinkage at high temperatures, processing at high temperatures is possible, for example, shortening molding time.

[0119] In addition, the MB nonwoven fabric of the present invention can not only improve thermal stability but also achieve a soft feel. The 10% modulus (M MD ) is 22N / 5cm or less. The 10% modulus (M MD ) is preferably 21N / 5cm or less. In addition, the 10% modulus (M CD ) is preferably 18N / 5cm or less, more preferably 16N / 5cm or less. Here, 10% modulus is the tensile stress at 10% strain, specifically, the value measured by the method described in the Examples described below. In addition, from the viewpoint of maintaining a soft feel, it is preferable that the 10% modulus in the longitudinal direction (MD direction) and the transverse direction (CD direction) have the same degree of 10%, and the longitudinal 10% modulus (M MD ) and transverse 10% modulus (M CD ) ratio (M MD / M CD ) For example, it can be about 1.00 to 1.50, or about 1.05 to 1.45, or about 1.10 to 1.40.

[0120] The MB nonwoven fabric of the present invention can have strength and elongation that pose no practical problems in terms of handling. For example, the tensile strength in the longitudinal direction (machine direction or MD) can be 10 N / 5 cm or greater, preferably 14 N / 5 cm or greater, and more preferably 18 N / 5 cm or greater. The tensile strength is a value measured by the method described in the Examples below.

[0121] In addition, the MB nonwoven fabric of the present invention has the same degree of tensile strength in the longitudinal direction (MD direction) and the transverse direction (CD direction). For example, the longitudinal tensile strength (T MD ) and transverse tensile strength (T CD ) ratio (T MD / T CD ) can be about 1.00 to 1.40, can be about 1.00 to 1.20, can be about 1.10 to 1.35, or can be about 1.10 to 1.20.

[0122] The MB nonwoven fabric of the present invention may have an elongation of 25% or more, preferably 30% or more, in the longitudinal direction (or MD direction), for example. The elongation is a value measured by the method described in the Examples below.

[0123] In addition, the MB nonwoven fabric of the present invention has the same degree of elongation in the longitudinal direction (MD direction) and the transverse direction (CD direction). For example, the longitudinal elongation (E MD ) and transverse elongation (E CD ) ratio (E MD / E CD ) can be about 0.80 to 1.20, or about 0.80 to 1.15, or about 0.90 to 1.20, or about 0.95 to 1.15.

[0124] The average fiber diameter of the MB nonwoven fabric of the present invention can be appropriately determined depending on the intended use. There are no particular limitations on the average fiber diameter. For example, from the perspective of sound absorption and nonwoven fabric strength, the average fiber diameter can be, for example, approximately 0.5 to 10 μm, preferably approximately 1 to 8 μm, and more preferably approximately 1 to 5 μm. The average fiber diameter is a value measured using the method described in the Examples below.

[0125] The density of the MB nonwoven fabric of the present invention can be appropriately determined according to the application, and there is no particular limitation on the density. For example, from the perspective of sound absorption, the density can be 0.1 to 0.4 g / cm 3 About 0.1 to 0.3 g / cm 3 More preferably, it can be 0.1 to 0.2 g / cm 3 about.

[0126] The thickness of the MB nonwoven fabric of the present invention can be appropriately determined depending on the intended use and is not particularly limited. For example, from the perspective of handleability and sound absorption, the thickness can be, for example, about 50 to 500 μm, preferably about 80 to 400 μm, and more preferably about 100 to 300 μm.

[0127] The MB nonwoven fabric of the present invention can be appropriately weighted according to the intended use. There is no particular limitation on the weight per unit area. For example, from the perspective of sound absorption and productivity, the weight per unit area can be 10 to 100 g / m 2 About 20 to 70 g / m 2 More preferably, it can be 20 to 50 g / m 2 about.

[0128] The MB nonwoven fabric of the present invention can appropriately determine the air permeability according to the application, and the air permeability is not particularly limited. For example, from the viewpoint of sound absorption, the air permeability can be, for example, 30 to 90 cm 3 / cm 2 ·s, preferably 35 to 85 cm 3 / cm 2 ·s, more preferably 40 to 80 cm 3 / cm 2 ·s or so.

[0129] The MB nonwoven fabric of the present invention can be used in various applications, including medical and sanitary materials, industrial materials, daily necessities, and clothing. In particular, due to its excellent high-frequency sound absorption properties, it is suitable for use in sound-absorbing materials for vehicles (particularly automotive sound-absorbing materials), outdoor high-frequency sound-absorbing panels, and noise suppression sheets for electronic devices.

[0130] Furthermore, the MB nonwoven fabric of the present invention has excellent thermal stability and can be used in combination with various supports (e.g., sheet-like resin members, fabrics, etc.) to form a laminate. For example, such a laminate may be composed of a support and an MB nonwoven fabric heat-compression-bonded to at least one side of the support, wherein the MB nonwoven fabric is the nonwoven fabric of the present invention.

[0131] In addition, the MB nonwoven fabric of the present invention has a soft feel and good adhesion to the support. For example, the peel strength (T-peel method) measured at the thermocompression bonded surface between the nonwoven fabric and the support according to JIS K 6854-3 can be 0.2 N / 5 cm or more, preferably 0.25 N / 5 cm or more, and more preferably 0.3 N / 5 cm or more.

[0132] The support can be appropriately selected from various materials according to the application, and can be various resin sheets, cloths (woven fabrics, knitted fabrics, non-woven fabrics, felts), etc. In addition, the cloth can be formed by any one of natural fibers, regenerated fibers, semi-synthetic fibers, and synthetic fibers. As a non-woven fabric, for example, it can be any one of wet non-woven fabrics, dry non-woven fabrics (for example, chemical bonding, thermal bonding, needle punching, spunlace, stitching, air-laid, etc.), and spinning-direct non-woven fabrics (for example, spunbond, etc.). From the viewpoint of being able to adjust the density and thickness to improve the sound absorption, the support is preferably felt or non-woven fabric (for example, needle punched non-woven fabric).

[0133] The laminate can be used in the various applications mentioned above for MB nonwoven fabrics. In particular, the laminate has excellent high-frequency sound absorption and is therefore suitable for use as a sound-absorbing material for vehicles (particularly automobiles), a high-frequency sound-absorbing panel for outdoor use, and a noise suppression sheet for electronic devices.

[0134] Example

[0135] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. In the following Examples and Comparative Examples, various physical properties were measured by the following methods.

[0136] [Average fiber diameter]

[0137] The fiber structure of the MB nonwoven fabric was observed using a scanning electron microscope. 100 fibers were randomly selected from the electron microscope photograph, and their fiber diameters were measured to determine the number average fiber diameter, which was used as the average fiber diameter of the fibers.

[0138] [Weight per unit area]

[0139] The weight per unit area (g / m2) of MB nonwoven fabric was measured according to 6.1 of JIS L 1913 “Test methods for general nonwoven fabrics”. 2 ).

[0140] [thickness]

[0141] The thickness of the MB nonwoven fabric was measured in accordance with 6.2 of JIS L 1913 "Test methods for general nonwoven fabrics".

[0142] [density]

[0143] The volume of the nonwoven fabric was measured based on the weight per unit area and thickness of the nonwoven fabric, and the density of the MB nonwoven fabric was calculated from these results.

[0144] [Breathability]

[0145] The air permeability (cm2) was measured by the Frazier method according to 8.26 of JIS L 1096 “Test methods for materials of woven and knitted fabrics”. 3 / cm 2 ·s).

[0146] [Strength / Elongation / 10% Modulus]

[0147] Samples were cut into 5 cm widths in both the longitudinal and transverse directions. Each sample was stretched at a rate of 10 cm / min using an Autograph manufactured by Shimadzu Corporation in accordance with JIS L 1906. The load at break was taken as the tensile strength, and the elongation at that point was taken as the elongation. Furthermore, the tensile stress at 10% elongation was measured as the 10% modulus. These measurements were performed at 30°C.

[0148] [Area shrinkage at 200°C]

[0149] A 20cm square specimen was marked 5cm inward from each side, and a 10cm square was marked inside the specimen. This specimen was placed in an oven heated to 200°C and heat treated for 1 minute in a free state. The dimensions of the marked areas were measured before and after heat treatment, and the area shrinkage was calculated using the following formula.

[0150] (Area shrinkage ratio) = {(Area before heat treatment) - (Area after heat treatment)} / (Area before heat treatment) × 100

[0151] [Molding processability at 200°C]

[0152] A 20cm square sample and a 20cm square substrate (weight per unit area of ​​about 600g / m 2 The laminated fabric was then laminated with two sheets of MB nonwoven fabric (a felt) and then sandwiched between iron plates. The laminated fabric was heated at 200°C and 200 Pa for 1 minute, and then removed. The laminated fabric was rated A if there were no problems with appearance abnormalities such as wrinkles or the soft feel derived from the MB nonwoven fabric after heating. The laminated fabric was rated B if there were any problems with appearance abnormalities such as wrinkles or the soft feel derived from the MB nonwoven fabric after heating. The moldability at 200°C was evaluated.

[0153] [Peel Strength of Laminated Body]

[0154] For the laminate obtained to evaluate the molding processability at 200° C., the peel strength between the sample and the substrate was measured by the T-type peeling method in accordance with JIS K6854-3.

[0155] (Example 1)

[0156] A PET resin (crystallization temperature (Tc) 130°C) with a melt viscosity of 80 Pa·s at a temperature of 300°C was melted and supplied to a die having a nozzle with a single hole diameter (diameter) of 0.3 mm, a single hole length / nozzle single hole diameter (L / D) = 10, and a nozzle hole pitch of 0.75 mm. The air flow rate was 15 Nm per 1 m of nozzle width. 3 The melt was discharged from the nozzle at a spinning temperature of 320°C and a single-hole discharge rate of 0.13 g / min while blowing hot air at a temperature of 340°C as a companion stream. The ambient temperature at 5 cm vertically downward from the nozzle hole (hereinafter referred to as the temperature 5 cm below the nozzle) was 165.0°C.

[0157] Below the nozzle, such as Figure 1 As shown, the lower side of the nozzle is insulated with an insulation cover of 11.0 cm in length, and air is blown from the blowing port on the side of the insulation cover at a rate of 2 Nm per 1 m of nozzle width. 3 / min. Hot air at 350°C was blown from both sides of the nozzle toward the nozzle hole as a heated air flow to heat the filaments discharged from the nozzle. The temperature of the discharged filaments measured 10 cm below the spinning nozzle was 138.9°C.

[0158] After leaving the heat-insulating cover, the ejected filaments passed through a 9.0 cm air gap area and were collected on a collection net. Without post-processing, the unit area weight was 30 g / cm 2 PET MB nonwoven fabric. Figure 2 As shown in FIG. 1 , the length of the heating area H is 11.0 cm, and the length of the air gap area L is 9.0 cm. The MB nonwoven fabric obtained after heat treatment at 200° C. is shown in FIG. Figure 3 .

[0159] (Example 2)

[0160] The same procedure as in Example 1 was followed except that the blowing temperature of the heated air flow was set to 180°C. At this time, the temperature at 5 cm below the nozzle was 141.1°C, and the temperature of the ejected filaments measured at 10 cm below the spinning nozzle was 110.3°C. The MB nonwoven fabric obtained after heat treatment at 200°C is shown in FIG. Figure 4 .

[0161] (Example 3)

[0162] The same procedures as in Example 1 were followed, except that the length of the heat-insulating cover provided below the nozzle was changed to 15.0 cm, the length of the air gap region was changed to 5.0 cm, and the temperature of the heated air flow was changed to 300°C. At this point, the temperature 5 cm below the nozzle was 142.0°C, and the temperature of the ejected filaments measured 10 cm below the spinning nozzle was 130.7°C.

[0163] (Example 4)

[0164] The same procedures as in Example 1 were followed, except that the length of the heat-insulating cover provided below the nozzle was changed to 15.0 cm and the length of the air gap region was changed to 8.0 cm. The temperature 5 cm below the nozzle was 145.2°C, and the temperature of the ejected filaments measured 10 cm below the spinning nozzle was 137.6°C.

[0165] (Example 5)

[0166] The same procedures as in Example 1 were followed, except that the length of the heat-insulating cover provided below the nozzle was changed to 17.5 cm, the length of the air gap region was changed to 5.5 cm, and the temperature of the heated air flow was changed to 180°C. The temperature at 5 cm below the nozzle was 138.9°C, and the temperature of the ejected filaments measured 10 cm below the spinning nozzle was 123.6°C.

[0167] (Comparative Example 1)

[0168] The same procedures as in Example 1 were followed except that heated air was not blown in through the inlet of the heat-insulating cover. Specifically, in Comparative Example 1, the interior of the cover was not heated, and the space below the spinning nozzle was not heated to a temperature above the crystallization temperature of the PET resin. Therefore, the distance H was 0 cm and the distance L was 9.0 cm. Furthermore, the temperature 5 cm below the nozzle was 119.1°C, and the resin temperature measured 10 cm below the spinning nozzle was 100.8°C.

[0169] (Comparative Example 2)

[0170] After the melt was ejected from the nozzle, the melt was collected directly on a collection net set 13 cm below the nozzle hole without installing a heat-insulating cover and without injecting heated air. The same procedure as in Example 1 was followed except that the heat-insulating cover was not installed and the heated air flow was not injected. That is, in Comparative Example 2, the space below the spinning nozzle was not heated to a temperature above the crystallization temperature of the PET resin. Therefore, the distance H was 0 cm and the distance L was 13.0 cm. In addition, the temperature 5 cm below the nozzle was 82.6°C, and the temperature of the resin measured 10 cm below the spinning nozzle was 54.6°C. The state of the MB nonwoven fabric obtained after heat treatment at 200°C is shown in FIG. Figure 5 .

[0171] (Comparative Example 3)

[0172] The same procedures as in Example 1 were followed, except that the length of the heated area H was set to 10.5 cm and the length of the air gap area L was set to 2.0 cm. Specifically, in Comparative Example 3, the distance H was set to 10.5 cm and the distance L was set to 2 cm. Furthermore, at this point, the temperature 5 cm below the nozzle was 148.0°C, and the temperature of the discharged filaments measured 10 cm below the spinning nozzle was 119.3°C.

[0173]

[0174] As shown in Table 1, despite the installation of a heat-insulating cover in Comparative Example 1, heating was not applied. Therefore, the resin temperature measured 10 cm below the spinning nozzle was lower than that in the Examples. Furthermore, perhaps because the lack of a heated area failed to promote crystallization, the resulting sample exhibited an area shrinkage of over 30% at 200°C. Furthermore, the strength of the MB nonwoven fabric was lower than that in the Examples. Furthermore, in the laminate formed by thermocompression bonding the support and MB nonwoven fabric, the MB nonwoven fabric significantly shrank due to heating, resulting in wrinkles in the appearance and insufficient moldability.

[0175] In Comparative Example 2, since no heat-insulating cover was installed, the resin temperature measured 10 cm below the spinning nozzle was less than half that of the Example. Consequently, the resulting sample exhibited an area shrinkage of over 30% at 200°C. Furthermore, the laminate formed by thermocompression bonding the support and MB nonwoven fabric exhibited wrinkles in appearance due to the significant shrinkage of the MB nonwoven fabric during heating, resulting in insufficient moldability.

[0176] Furthermore, despite the presence of a heated area in Comparative Example 3, the length of the air gap region, i.e., the distance L, was only 2.0 cm. Therefore, the resulting ejected filaments could not be unwound to a large volume within the heated area, resulting in a nonwoven fabric with a stiff feel at a 10% modulus in the machine direction (MD) exceeding 30 N / 5 cm. Furthermore, the air permeability of the resulting nonwoven fabric was approximately half that of the Examples. Furthermore, the laminate formed by thermocompression bonding the support and MB nonwoven fabric was stiff, failing to achieve the soft feel of the nonwoven fabric, resulting in insufficient moldability.

[0177] On the other hand, the samples obtained in Examples 1 to 5 all exhibited reduced area shrinkage at 200°C. Furthermore, their 10% modulus in the machine direction (MD) was approximately 20 N / 5 cm or less, resulting in nonwoven fabrics with a soft hand. These nonwoven fabrics exhibited higher strength than that of Comparative Example 1. Furthermore, not only were their strength and elongation high, but they also exhibited high isotropy between the machine and transverse directions, resulting in nonwoven fabrics with excellent longitudinal and transverse balance.

[0178] In addition, compared with Comparative Examples 2 and 3, Examples 1 to 5 can all improve air permeability.

[0179] Furthermore, in the laminates formed by thermocompression bonding the support and the MB nonwoven fabrics obtained in Examples 1 to 5, wrinkles were not generated in the appearance after heating, indicating excellent moldability.

[0180] [Table 2]

[0181]

[0182] Table 2 shows the peel strength of laminates formed by thermocompression bonding a support and the MB nonwoven fabrics obtained in Examples 1 to 5. As shown in Table 2, the peel strength of the laminates using the MB nonwoven fabrics obtained in Examples 1 to 5 was 0.3 N / 5 cm or greater.

[0183] Industrial Applicability

[0184] As described above, the MB nonwoven fabric of the present invention and the laminate using the same can be used in various applications such as medical and sanitary materials, industrial materials, daily necessities, and clothing. In particular, due to its excellent high-frequency sound absorption properties, it can be suitably used in vehicle sound absorbing materials (especially automotive sound absorbing materials), outdoor high-frequency sound absorbing panels, and noise suppression sheets for electronic devices.

[0185] Although the preferred embodiments of the present invention have been described above, various additions, changes, and deletions may be made without departing from the spirit of the present invention, and these are also included in the scope of the present invention.

Claims

1. A meltblown nonwoven fabric comprising a resin composition containing a crystalline thermoplastic resin as a main component, wherein the crystalline thermoplastic resin is selected from a polyolefin resin, a polyamide resin, and a polyester resin, wherein, when the melting point of the crystalline thermoplastic resin is set to Tm, the area shrinkage at (Tm×3 / 4)°C is 20% or less, and the 10% modulus (M) in the longitudinal direction at 30°C is 20% or less. MD ) is less than 22N / 5cm, and the elongation in the MD direction (E MD ) is 25-45%, and the elongation in the MD direction (E MD ) and the elongation in CD direction (E CD ) ratio (E MD / E CD ) is 0.80~1.20, the tensile strength in MD direction (T MD ) is 20.3N / 5cm or more.

2. The meltblown nonwoven fabric according to claim 1, wherein The crystalline thermoplastic resin is selected from polyamide resins and polyester resins.

3. The meltblown nonwoven fabric according to claim 2, wherein The crystalline thermoplastic resin is selected from polyester resins.

4. The meltblown nonwoven fabric according to any one of claims 1 to 3, wherein the longitudinal tensile strength (T MD ) and transverse tensile strength (T CD ) ratio (T MD / T CD ) is 1.00~1.

40. The meltblown nonwoven fabric according to claim 1 , wherein the longitudinal elongation thereof is 27% or more.

6. The meltblown nonwoven fabric according to any one of claims 1 to 3, wherein the air permeability thereof is 30 to 90 cm as measured in accordance with JIS L 1906. 3 / cm 2 ·s.

7. The melt-blown nonwoven fabric according to any one of claims 1 to 3, which is used as a sound-absorbing material for vehicles.

8. A laminate comprising a support and a meltblown nonwoven fabric thermally pressed onto at least one surface of the support, wherein: The melt-blown nonwoven fabric is the melt-blown nonwoven fabric according to any one of claims 1 to 7. 9 . The laminate according to claim 8 , wherein the peel strength measured by a T-peel method according to JIS K 6854-3 at the thermally pressed surface between the meltblown nonwoven fabric and the support is 0.2 N / 5 cm or more.

10. The laminate according to claim 8 or 9, wherein The support body is made of non-woven fabric or felt.

11. A sound absorbing material for vehicles, comprising the laminate according to any one of claims 8 to 10.

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