Meltblown nonwoven fabric laminate

Abstract

The present invention provides a polymethylpentene-based meltblown nonwoven fabric laminate in which surface fuzzing is suppressed and interlayer delamination does not occur or is unlikely to occur. [Solution] A laminate of meltblown nonwoven fabrics is formed by laminating a first meltblown nonwoven fabric made of polymethylpentene resin fibers and a second meltblown nonwoven fabric made of polymethylpentene resin fibers, wherein the basis weight of the entire laminate is 35 g / m². 2 More than 130g / m 2 The difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m². 2 The above describes a meltblown nonwoven fabric laminate having a peel strength of 0.10 N / 100 mm width or more.

Description

[Technical Field]

[0001] This disclosure relates to meltblown nonwoven fabric laminates. [Background technology]

[0002] As methods for improving the fluffiness of meltblown nonwoven fabrics, surface smoothing by calendering and fluff suppression techniques by lamination of rough surfaces are known.

[0003] Reference 1 discloses a meltblown nonwoven fabric laminate in which two or more layers of meltblown nonwoven fabrics having an average fiber diameter of 0.1 μm to 1.5 μm and having both a rough surface and a smooth surface are laminated, and a plurality of the meltblown nonwoven fabrics are laminated such that the smooth surface of the meltblown nonwoven fabric is located on both surfaces of the nonwoven fabric laminate. It is described that this configuration makes it difficult for the fabric to break.

[0004] Reference 2 describes a relatively low basis weight (basis weight of 50g / m²). 2 The following disclosure concerns a separator made of a heat-resistant melt-blown nonwoven fabric thin film formed by laminating at least two layers of heat-resistant melt-blown nonwoven fabric. It is described that this configuration results in high uniformity of physical properties, excellent surface smoothness, and reduced likelihood of internal short circuits.

[0005] Reference 3 discloses a method for producing a heat-resistant meltblown nonwoven thin film obtained by thinning a meltblown nonwoven base fabric made of a heat-resistant resin, comprising at least: (1) a high-temperature calendering step in which the meltblown nonwoven base fabric is sandwiched between at least two metal rolls and subjected to calendering under processing temperature conditions above the glass transition point of the heat-resistant resin and pressurized conditions adjusted to suppress crushing of the constituent fibers of the meltblown nonwoven base fabric and enable thinning; and (2) a special calendering step in which the calendered intermediate obtained in the high-temperature calendering step is subjected to calendering under processing temperature conditions of 130°C or lower and pressurized conditions adjusted to suppress crushing of the constituent fibers of the nonwoven base fabric and enable thinning. It has been described that by laminating a melt-blown nonwoven fabric base roll into at least two nonwoven fabric layers and bonding them by high-temperature calendering, the resulting nonwoven thin film achieves improved tensile strength and also improves the uneven appearance characteristic of nonwoven fabrics. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-165014 [Patent Document 2] WO2008 / 018584 [Patent Document 3] Japanese Patent Publication No. 2019-119946 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Meltblown nonwoven fabrics made from polyolefin resins, which offer excellent chemical resistance, are used as battery separators. While polypropylene meltblown nonwoven fabrics are the most commonly used, further heat resistance is required depending on the battery's application and operating environment.

[0008] Polymethylpentene, another polyolefin resin, has higher heat resistance than polypropylene, but it has the drawback of being prone to fraying on the surface of the nonwoven fabric because it solidifies quickly during molding and the fibers do not fuse together easily. In meltblown nonwoven fabrics, the surface condition differs between the side facing the nozzle and the side facing the collector during spinning, and this phenomenon is particularly likely to occur on the rough side of the nonwoven fabric (the side opposite to the side in contact with the collector net where the molten resin discharged from the nozzle is collected).

[0009] When using separators that are prone to fraying, the rate of defective products is high, as surface fraying can adhere to the rolls during the battery assembly process, or, in the case of coin-type batteries, fibers may protrude from the can due to improper punching, causing leakage.

[0010] Normally, calendering suppresses the fibers on the surface of meltblown nonwoven fabric, thus reducing fuzzing. There is also a technique that further suppresses fuzzing by bonding the rough surfaces of two meltblown nonwoven fabrics together. However, even after calendering polymethylpentene nonwoven fabric, it can still fuzz with light friction, and even after lamination calendering, it easily delaminates between layers.

[0011] As shown in Reference 1, simply overlapping the rough sides of nonwoven fabrics of the same basis weight will easily cause the nonwoven fabrics to peel apart, especially in the case of meltblown nonwoven fabrics made from polymethylpentene resin fibers.

[0012] In references 2 and 3, relatively low basis weight nonwoven fabrics are laminated at relatively high pressure to produce thin films with relatively high packing density, resulting in good surface smoothness. On the other hand, the processing temperature is 160°C in Patent Document 2 and 100-150°C in Patent Document 3. In this temperature range, delamination is likely to occur in meltblown nonwoven fabrics composed of polymethylpentene resin fibers, and the delamination becomes more pronounced as the basis weight increases and the packing density decreases.

[0013] The problem to be solved in this disclosure is to provide a polymethylpentene-based meltblown nonwoven fabric laminate in which surface fuzzing is suppressed and interlayer delamination does not occur or is unlikely to occur. [Means for solving the problem]

[0014] This disclosure includes, for example, the following subjects:

[0015] Section 1. A laminate of meltblown nonwoven fabrics, comprising a first meltblown nonwoven fabric made of polymethylpentene resin fibers and a second meltblown nonwoven fabric made of polymethylpentene resin fibers, wherein the basis weight of the entire laminate is 35 g / m². 2 More than 130g / m 2 The difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m². 2 The above describes a meltblown nonwoven fabric laminate having a peel strength of 0.10 N / 100 mm width or more. Section 2. The basis weight of the second meltblown nonwoven fabric is 30 g / m². 2 More than 120g / m 2 The meltblown nonwoven fabric laminate described in item 1 below. Section 3. The first meltblown nonwoven fabric has a basis weight of 15 g / m². 2 A meltblown nonwoven laminate as described in item 1 or item 2 below. Section 4. The meltblown nonwoven fabric laminate according to claim 1, wherein the thickness of the meltblown nonwoven fabric laminate is 0.20 mm or more and 0.70 mm or less. Section 5. The meltblown nonwoven fabric laminate according to claim 1, wherein the lamination structure of the meltblown nonwoven fabric laminate is a two-layer structure. Section 6. It has a rough surface and a smooth surface, and the basis weight of the first meltblown nonwoven fabric is 15 g / m². 2 The following is a step for preparing a first meltblown nonwoven fabric made of polymethylpentene resin fibers: It has a rough surface and a smooth surface, and the basis weight of the second meltblown nonwoven fabric is 30 g / m².2 120 g / m or less 2 A step of preparing a second melt-blown nonwoven fabric made of a polymethylpentene-based resin fiber, which is ...... or less, and A step of laminating the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric so that the rough surfaces of the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric face each other, A method for manufacturing a melt-blown nonwoven fabric laminate including the above steps. Item 7. After the laminating step, the method further includes calendering the laminate of the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric at a temperature of 170 °C or higher under a pressure condition, The produced melt-blown nonwoven fabric laminate has a basis weight of the entire laminate of 35 g / m or more and 130 g / m or less, and the difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m or more, and the peel strength is 0.10 N / 100 mm width or more. The manufacturing method according to Item 6. 2 130 g / m or less 2 The difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m or more, and the peel strength is 0.10 N / 100 mm width or more. The manufacturing method according to Item 6. 2 The manufacturing method according to Item 6, wherein the produced melt-blown nonwoven fabric laminate has a basis weight of the entire laminate of 35 g / m or more and 130 g / m or less, and the difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m or more, and the peel strength is 0.10 N / 100 mm width or more.

Advantages of the Invention

[0016] According to the present disclosure, there is provided a polymethylpentene-based melt-blown nonwoven fabric laminate in which surface fluffing is suppressed and interlayer peeling does not occur or hardly occurs.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic diagram of an example of the process of the method for manufacturing a melt-blown nonwoven fabric of the present invention. [Figure 2] It is an exploded perspective view showing the internal structure of the collector 4a in FIG. 1.

Modes for Carrying Out the Invention

[0018] In this specification, "comprising" is a concept that also includes "consisting essentially of" and "consisting of only".

[0019] In the numerical ranges described stepwise in this specification, the upper or lower limit of a numerical range in one step can be arbitrarily combined with the upper or lower limit of a numerical range in another step. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of a numerical range may be replaced with values ​​shown in the examples or values ​​that can be uniquely derived from the examples. Moreover, in this specification, numbers connected by "~" mean a numerical range that includes the numbers before and after "~" as the lower and upper limits.

[0020] In this specification, "rough surface" refers to the surface with greater surface roughness located on the nozzle side during spinning, and "smooth surface" refers to the surface with less surface roughness located on the collector side. The "rough surface" may also be called the "fuzzy surface" because it is more prone to fuzzing due to friction from fingers than the "smooth surface," and the "smooth surface" may also be called the "net surface" because it comes into contact with the net of the collector. The net surface can be identified by the mesh structure left after pressure is applied while in contact with the net. In this specification, MD of a meltblown nonwoven fabric refers to the longitudinal direction of the meltblown nonwoven fabric, and CD refers to the width direction of the meltblown nonwoven fabric.

[0021] 1. Meltblown nonwoven fabric laminate This disclosure relates to a laminate of meltblown nonwoven fabrics, comprising a first meltblown nonwoven fabric made of polymethylpentene resin fibers and a second meltblown nonwoven fabric made of polymethylpentene resin fibers, wherein the basis weight of the entire laminate is 35 g / m². 2 More than 130g / m 2 The difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m². 2 The above provides a meltblown nonwoven fabric laminate having a peel strength of 0.10 N / 100 mm width or more.

[0022] The polymethylpentene-based resin fibers constituting the first meltblown nonwoven fabric are composed of polymethylpentene or a resin composition containing polymethylpentene. The polymethylpentene-based resin fibers constituting the first meltblown nonwoven fabric are fibers containing polymethylpentene. Polymethylpentene is, for example, a 4-methyl-1-pentene polymer, particularly poly-4-methyl-1-pentene.

[0023] The first meltblown nonwoven fabric preferably contains 50% by mass or more, more preferably 90% by mass or more, more preferably 95% by mass or more, for example 100% by mass, of polymethylpentene resin fibers relative to the total mass of the first meltblown nonwoven fabric.

[0024] In the resin composition constituting the polymethylpentene-based resin fibers of the first meltblown nonwoven fabric, preferably 95% by mass or more is polymethylpentene, for example, a 4-methyl-1-pentene polymer, and particularly poly4-methyl-1-pentene.

[0025] The basis weight of the first meltblown nonwoven fabric is not particularly limited, but is 15 g / m². 2 Under the following conditions, the heat applied under pressure to the first and second meltblown nonwoven fabrics reaches the interlayers of the meltblown nonwoven fabrics, resulting in adhesion and making delamination less likely.

[0026] The lower limit of the basis weight of the first meltblown nonwoven fabric is not particularly limited, but for example, 1 g / m² 2 More than 3g / m 2 More than 5g / m 2 or more, or 7g / m² 2 That's all.

[0027] A preferred upper limit for the basis weight of the first meltblown nonwoven fabric is, for example, 15 g / m². 2 Below, 13g / m 2 The following, or 12g / m² 2 The following applies:

[0028] The thickness of the first meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 0.1 to 1.00 mm in average thickness, more preferably 0.15 to 0.90 mm, and even more preferably 0.17 to 0.80 mm. The average thickness of the meltblown nonwoven fabric laminate can be measured by the measurement method described in the examples.

[0029] The polymethylpentene-based resin fibers constituting the second meltblown nonwoven fabric are composed of polymethylpentene or a resin composition containing polymethylpentene. The polymethylpentene-based resin fibers constituting the second meltblown nonwoven fabric are fibers containing polymethylpentene. Polymethylpentene is, for example, a 4-methyl-1-pentene polymer, particularly poly4-methyl-1-pentene.

[0030] The second meltblown nonwoven fabric preferably contains 50% by mass or more, more preferably 90% by mass or more, more preferably 95% by mass or more, for example 100% by mass, of polymethylpentene resin fibers relative to the total mass of the second meltblown nonwoven fabric.

[0031] In the resin composition constituting the polymethylpentene-based resin fibers of the second meltblown nonwoven fabric, preferably 95% by mass or more is polymethylpentene, for example, a 4-methyl-1-pentene polymer, and particularly poly4-methyl-1-pentene.

[0032] The basis weight of the second meltblown nonwoven fabric is greater than that of the first meltblown nonwoven fabric. The basis weight of the second meltblown nonwoven fabric is 30 g / m². 2 The above ensures that the required thickness for the meltblown nonwoven fabric laminate of this disclosure can be secured. The basis weight of the second meltblown nonwoven fabric is 120 g / m². 2 The following conditions make it less likely for entanglement of broken polymer fibers and floating fibers to occur during the manufacturing of polymethylpentene-based meltblown nonwoven fabric, resulting in a good surface condition for the meltblown nonwoven fabric. The lower limit of the basis weight of the second meltblown nonwoven fabric is not particularly limited, but for example, 30 g / m² 2 More than 35g / m 2or more, or 40g / m² 2 That's all. The upper limit of the basis weight of the second meltblown nonwoven fabric is not particularly limited, but for example, 120 g / m² 2 Below 110g / m 2 The following, or 100g / m² 2 The following applies:

[0033] 15g / m 2 The first meltblown nonwoven fabric with a low basis weight of 30g / m² is as follows: 2 More than 120g / m 2 By using a meltblown nonwoven fabric laminate obtained by overlapping the rough surfaces of two meltblown nonwoven fabrics and laminating a second meltblown nonwoven fabric with a high basis weight as shown below, it is possible to provide a polymethylpentene-based meltblown nonwoven fabric laminate in which surface fuzzing is suppressed and interlayer delamination does not occur or is unlikely to occur.

[0034] The first meltblown nonwoven fabric and the second meltblown nonwoven fabric may be composed of different types of polymethylpentene resin fibers, or they may be composed of the same type of polymethylpentene resin fibers, preferably the same type of polymethylpentene resin fibers. For example, the polymethylpentene resin fibers constituting the first meltblown nonwoven fabric and the second meltblown nonwoven fabric are both composed of polymethylpentene or a resin composition containing polymethylpentene, where the polymethylpentene is, for example, a 4-methyl-1-pentene polymer, particularly poly4-methyl-1-pentene. The amount of polymethylpentene in the resin composition containing polymethylpentene is preferably 50% by mass or more, more preferably 90% by mass or more, and more preferably 95% by mass or more.

[0035] The basis weight of the meltblown nonwoven fabric of this disclosure can be set to a desired value, for example, by changing the collector speed. The average fiber diameter of the first meltblown nonwoven fabric and the second meltblown nonwoven fabric are not particularly limited, but are preferably 0.5 to 50 μm from the viewpoint of separator applications. In some embodiments, the average fiber diameter is preferably 1.0 to 8 μm, more preferably 1.5 to 6 μm. The average fiber diameter of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0036] The thickness of the second meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 0.20 to 1.50 mm in average thickness, more preferably 0.25 to 1.30 mm, and even more preferably 0.30 to 1.00 mm. The average thickness of the meltblown nonwoven fabric laminate can be measured by the measurement method described in the examples. The difference in basis weight between the first meltblown nonwoven fabric and the second meltblown nonwoven fabric is 15 g / m². 2 If the weight is less than 15 g / m², interlayer bonding becomes difficult. The difference between the basis weight of the first meltblown nonwoven fabric and the basis weight of the second meltblown nonwoven fabric is preferably 15 g / m². 2 In addition, a comfortable 17g / m² 2 More preferably 20 g / m² 2 That's all.

[0037] The basis weight of the meltblown nonwoven laminate of this disclosure is preferably 35 g / m². 2 More than 130g / m 2 The following is more preferable: 40 g / m² 2 More than 120g / m 2 More preferably 43 g / m² 2 More than 110g / m 2 The following applies: The basis weight of the meltblown nonwoven laminate is 35 g / m². 2 If the weight is less than 130 g / m², the required thickness cannot be achieved after the lamination calendering process. 2 Beyond this point, there is a concern that battery performance may decrease due to reduced breathability. The basis weight of a meltblown nonwoven fabric laminate can be measured by taking the mass (g) of 10 meltblown nonwoven fabric laminate test pieces measuring 100mm x 100mm at a temperature of 23°C and a humidity of 50%, and averaging the results.

[0038] The thickness of the meltblown nonwoven fabric laminate of this disclosure is not particularly limited, but is preferably 0.20 to 0.70 mm in average thickness, more preferably 0.22 to 0.65 mm, and even more preferably 0.24 to 0.60 mm. The average thickness of the meltblown nonwoven fabric laminate can be measured by the measurement method described in the examples. If the average thickness of the meltblown nonwoven fabric laminate is 0.20 mm or more, the required thickness can be secured, and if the average thickness of the meltblown nonwoven fabric laminate is 0.70 mm or less, it is easy to incorporate into a battery.

[0039] The air permeability of the meltblown nonwoven fabric laminate of this disclosure is not particularly limited, but is preferably 0.1 to 50 s / φ10 / 100 cc, and more preferably 0.3 to 30 s / φ10 / 100 cc. The air permeability of the meltblown nonwoven fabric laminate can be measured by the measurement method described in the examples.

[0040] The permeability of the first meltblown nonwoven fabric of this disclosure is not particularly limited, but is between 10 and 800 cm². 3 / cm 2 It is preferable that the value is / second, and it is between 20 and 700 cm. 3 / cm 2 / second is more preferable, 30-600cm 3 / cm 2 / second is even more preferable. The air permeability of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0041] The air permeability of the second meltblown nonwoven fabric of this disclosure is not particularly limited, but is between 3 and 500 cm. 3 / cm 2 It is preferable that the value is / second, and is between 5 and 400 cm. 3 / cm 2 / second is more preferable, 7-300cm 3 / cm 2 / second is even more preferable. The air permeability of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0042] The air permeability of the meltblown nonwoven laminates of this disclosure is not particularly limited, but is between 2 and 400 cm². 3 / cm 2 It is preferable that the value is / second, and 4-300cm 3 / cm 2 / second is more preferable, 6-200cm 3 / cm 2 / second is even more preferable. The air permeability of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0043] The air permeability of the meltblown nonwoven laminate is 2 cm. 3 / cm 2 If the interval is greater than / second, the internal resistance is properly maintained as a battery separator. The air permeability of the meltblown nonwoven laminate is 400 cm². 3 / cm 2 When the interval is less than [number] seconds, it can act as a battery separator to prevent internal short circuits.

[0044] The filling density of the first meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 1 to 50%, more preferably 1.5 to 40%, and even more preferably 2 to 30%. The filling density of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0045] The filling density of the second meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 1 to 50%, more preferably 2 to 40%, and even more preferably 3 to 30%. The filling density of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0046] The filling density of the meltblown nonwoven fabric laminate of this disclosure is not particularly limited, but is preferably 5 to 50%, more preferably 10 to 45%, and even more preferably 15 to 40%. The filling density of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0047] The MD tensile strength of the first meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 1 to 50 N / 50 mm, more preferably 2 to 40 N / 50 mm, and even more preferably 3 to 30 N / 50 mm. The MD tensile strength of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0048] The MD tensile strength of the second meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 2 to 100 N / 50 mm, more preferably 4 to 80 N / 50 mm, and even more preferably 6 to 60 N / 50 mm. The MD tensile strength of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0049] The MD tensile strength of the meltblown nonwoven laminate of this disclosure is not particularly limited, but is preferably 2 to 50 N / 15 mm, more preferably 4 to 40 N / 15 mm, and even more preferably 5 to 30 N / 15 mm. The MD tensile strength of the meltblown nonwoven can be measured by the measurement method described in the examples.

[0050] If the MD tensile strength of the meltblown nonwoven fabric laminate described herein is less than 2N / 15mm, there is a concern that it may break during the calendering process. If the MD tensile strength of the meltblown nonwoven fabric laminate exceeds 50N / 15mm, the elongation will decrease drastically, which may lead to malfunctions in the battery assembly process.

[0051] The MD tensile elongation of the first meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 1 to 150%, more preferably 2 to 100%, and even more preferably 3 to 80%. The MD tensile elongation of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0052] The MD tensile elongation of the second meltblown nonwoven fabric of this disclosure is not particularly limited, but is preferably 1 to 150%, more preferably 2 to 100%, and even more preferably 3 to 80%. The MD tensile elongation of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0053] The MD tensile elongation of the meltblown nonwoven laminate of this disclosure is not particularly limited, but is preferably 1% to 150% or 2% to 100%. The MD tensile elongation of the meltblown nonwoven can be measured by the measurement method described in the examples.

[0054] If the tensile elongation is 1% or more, breakage is less likely to occur during battery assembly. On the other hand, if the tensile elongation is 150% or less, necking is less likely to occur, and the battery can be assembled stably.

[0055] The peel strength of the meltblown nonwoven fabric laminate of this disclosure is preferably 0.10 to 25 N / 100 mm width, more preferably 0.11 to 20 N / 100 mm width, and even more preferably 0.13 to 15 N / 100 mm width. The peel strength of the meltblown nonwoven fabric can be measured by the measurement method described in the examples.

[0056] If the peel strength of the meltblown nonwoven fabric laminate is less than 0.10 N / 100 mm width, it will easily peel off. If the peel strength of the meltblown nonwoven fabric laminate is 25 N / 100 mm width or less, breathability is maintained and the internal resistance is appropriately maintained for use as a battery separator.

[0057] The thermal shrinkage rate of the meltblown nonwoven fabric laminate of this disclosure at high temperatures is 1.0% or less, preferably 0.5% or less, under a heating environment of 120°C for 1 hour, and 1.2% or less, preferably 1.0% or less, under a heating environment of 150°C for 1 hour. It is desirable that this value satisfies at least one, more preferably both, of the MD direction or the CD direction. If the thermal shrinkage rate is high, the separator at the end may shrink due to internal temperature rise caused by a malfunction in the battery under high temperature conditions, and problems such as internal short circuits may occur due to contact between the positive and negative electrodes.

[0058] The meltblown nonwoven fabric laminate of this disclosure may be used in combination with other layers, and fluid filters, battery separators, and electrode supports comprising such a laminate including a combination of the meltblown nonwoven fabric laminate and other layers are also included in the fluid filters, battery separators, and electrode supports of the present invention. Other layers include, for example, knitted fabrics, nonwoven fabrics, and films.

[0059] When laminating other layers to the meltblown nonwoven fabric laminate of this disclosure, various known methods can be employed, including thermal fusion methods such as thermal embossing and ultrasonic fusion, mechanical entanglement methods such as needle punching and water jetting, adhesive methods such as hot melt adhesives and urethane adhesives, and extrusion lamination. Other nonwoven fabrics that can be laminated as layers include spunbond nonwovens, wet-laid nonwovens, dry-laid nonwovens, dry-laid pulp nonwovens, flash-spun nonwovens, and open-fiber nonwovens.

[0060] 2. Method for manufacturing meltblown nonwoven fabric laminates Next, a method for producing the meltblown nonwoven fabric laminate according to this disclosure will be described. The method for producing the meltblown nonwoven laminate described herein has a rough surface and a smooth surface and a basis weight of 15 g / m². 2 The following steps describe how to prepare a first meltblown nonwoven fabric made of polymethylpentene resin fibers, having a rough surface and a smooth surface, and a basis weight of 30 g / m². 2 More than 120g / m 2 The process includes the following steps: preparing a second meltblown nonwoven fabric made of polymethylpentene resin fibers, and laminating the first meltblown nonwoven fabric and the second meltblown nonwoven fabric so that the rough surface of the first meltblown nonwoven fabric and the rough surface of the second meltblown nonwoven fabric face each other (lamination step).

[0061] Furthermore, the method for manufacturing a meltblown nonwoven laminate according to the present disclosure may further include a step of pressing the first meltblown nonwoven and the second meltblown nonwoven against each other (pressing step) simultaneously with or after the lamination step. The method for manufacturing a meltblown nonwoven laminate according to this disclosure may further include a step of winding the prepared meltblown nonwoven laminate (winding step). Each step will be described below.

[0062] (1) Steps for preparing the first meltblown nonwoven fabric and steps for preparing the second meltblown nonwoven fabric Figure 1 shows an example of a melt-blown nonwoven fabric manufacturing apparatus. This manufacturing apparatus consists of a hopper 1a for feeding raw materials, an extruder 1b for melting and kneading the raw materials, a metering pump 2 for sending the molten polymer extruded from the extruder 1b downstream, a die 3a for discharging fibrous material horizontally, a temperature-controlled heater 3b for high-temperature, high-speed air discharged from the die 3a together with the molten polymer, a spinning nozzle 3c attached to the tip of the die, a collector 4a for collecting fibers provided near the die 3a, a suction blower 4b for sucking up the collector 4a (and the fibrous molten polymer 5a collected by the collector 4a), the fibrous molten polymer 5a discharged from the die, a melt-blown nonwoven fabric 5b formed when the fibrous molten polymer 5a cools and solidifies on the collector 4a, and a winding machine 6 for winding up the melt-blown nonwoven fabric 5b. The diameter D of the hole 3d in the spinning nozzle 3c of the die 3a is, for example, 0.1 to 2.0 mm.

[0063] As shown in Figure 2, the collector 4a, which continuously collects the polymer fibers discharged and stretched from the spinning nozzle 3c, has a cylindrical member 41 that communicates with the suction blower 4b, a porous cylindrical member 42 provided on the outer circumferential surface of the cylindrical member 41, and a cylindrical mesh member 43 provided on the outer circumferential surface of the porous cylindrical member 42. The diameter of the collector 4a is preferably 30 to 150 cm, and more preferably 50 to 100 cm.

[0064] Meltblown nonwoven fabric can be manufactured by a method comprising (i) a step of melting and kneading a polymer, (ii) a step of extruding the molten polymer from a spinning nozzle and blowing heated air from another nozzle to form polymer fibers, and (iii) a step of collecting the obtained fibers with a collector 4a. Referring to the apparatus described above, when manufacturing meltblown nonwoven fabric, the fibrous molten polymer 5a extruded from the spinning nozzle 3c is stretched by heated air blown from an air nozzle, and the obtained polymer fibers are collected on the collector 4a.

[0065] (i) Melt-mixing process The melting and kneading temperature of the polymer is preferably between (melting point of the polymer + 30°C) and (melting point of the polymer + 150°C). The melting and kneading temperature of polymethylpentene is preferably between 260°C and 380°C. (ii) Fiber formation process Molten polymer is extruded from a number of spinning nozzles 3c, and heated air is ejected from the nozzles to form polymer fibers. The temperature of the die 3a and the heated air is preferably between (the melting point of the polymer) and (the melting point of the polymer + 200°C). This temperature range is preferred from the viewpoint of suppressing rapid solidification of the polymer immediately after extrusion from the spinning nozzles 3c and suppressing fusion of the formed polymer fibers, thereby suppressing variations in fiber diameter.

[0066] (iii) Collection process The suction volume of the collector 4a per unit width can be appropriately adjusted according to the desired physical properties of the meltblown nonwoven fabric 5b. Most of the heated air is drawn into the collector 4a through the suction holes 42a of the porous cylindrical member 42, thereby suppressing turbulence in the fiber flow. Specifically, the suction volume of the collector 4a per unit width is 10 to 100 m 3 / min is preferred, 20-80m 3 / minutes is preferable.

[0067] The rotational speed of collector 4a is preferably 1 to 110 m / min, and more preferably 3 to 100 m / min. Collector 4a may be at room temperature, but may be heated if necessary. The shortest distance (DCD) from nozzle 3c to collector 4a is preferably 30 to 600 mm. Furthermore, since the manufacturing apparatus and manufacturing methods for meltblown nonwoven fabrics are both publicly known, the first meltblown nonwoven fabric and the second meltblown nonwoven fabric can be prepared using manufacturing apparatus not limited to the manufacturing apparatus described with reference to Figures 1 and 2, and / or using methods not limited to those described above.

[0068] (2)Lamination process Next, a lamination process is performed in which the rough surface of the first meltblown nonwoven fabric and the rough surface of the second meltblown nonwoven fabric are laminated facing each other. In the lamination process, the first meltblown nonwoven fabric and the second meltblown nonwoven fabric prepared in the preparation process described above may be laminated as they are, without being wound onto rolls or the like. Alternatively, the first meltblown nonwoven fabric and the second meltblown nonwoven fabric may be wound onto rolls first, then unwound, and then laminated.

[0069] At this time, the first meltblown nonwoven fabric and the second meltblown nonwoven fabric each have a rough surface and a smooth surface, but they are arranged so that the rough surface of the first meltblown nonwoven fabric and the rough surface of the second meltblown nonwoven fabric face each other and are overlapped, i.e., laminated. The rough surfaces of the first meltblown nonwoven fabric and the second meltblown nonwoven fabric are laminated together, brought into close contact, and integrated.

[0070] Furthermore, if the meltblown nonwoven fabric laminate includes three or more layers of meltblown nonwoven fabric, a laminate may be prepared by first laminating the first meltblown nonwoven fabric and the second meltblown nonwoven fabric, and then further lamination of meltblown nonwoven fabric may be performed on this laminate. Alternatively, three or more meltblown nonwoven fabrics may be laminated at once. In either case, the meltblown nonwoven fabrics are laminated in such a orientation that both surfaces of the resulting meltblown nonwoven fabric laminate become the smooth surfaces of the meltblown nonwoven fabrics.

[0071] (3) Pressing process The pressing step may be performed simultaneously with the lamination of the first meltblown nonwoven fabric and the second meltblown nonwoven fabric in the lamination step described above, or it may be performed at a desired timing after the lamination of the first meltblown nonwoven fabric and the second meltblown nonwoven fabric.

[0072] The step of pressing the first meltblown nonwoven fabric and the second meltblown nonwoven fabric together is not particularly limited and may include passing the laminate of the first meltblown nonwoven fabric and the second meltblown nonwoven fabric between, for example, two rolls. Preferably, after passing between the two rolls, the process further includes calendering under pressurized conditions. The calendering temperature is not particularly limited, but is preferably 170 to 200°C, and more preferably 180 to 195°C. If the calendering temperature is below 170°C, adhesion between the meltblown nonwoven fabric laminates becomes difficult, and if it exceeds 200°C, the fibers melt and the air permeability deteriorates. Low basis weight (15 g / m²) 2 The following are examples of first melt-blown nonwoven fabrics and high-weight (30g / m²) nonwoven fabrics. 2 More than 120g / m 2 The thermal conductivity of the meltblown nonwoven laminate can be increased by overlapping the rough surfaces of the second meltblown nonwoven fabrics (described below) and performing a calendering process. The thermal conductivity can be appropriately modified by those skilled in the art by optimizing the roll temperature, unwinding and winding tensions, and line speed.

[0073] Furthermore, in the winding process described later, tension may be applied to wind the meltblown nonwoven laminate, pressing the first meltblown nonwoven and the second meltblown nonwoven against each other. Pressing multiple meltblown nonwovens against each other makes them easier to integrate.

[0074] (4) Winding process If the melt-blown nonwoven fabric laminate is in the form of a long length, a process of winding the melt-blown nonwoven fabric laminate onto a roll or the like may be performed after the lamination process or after the pressing process.

[0075] (5) Others In addition to the processes described above, further processing steps for the meltblown nonwoven fabric laminate may be performed as needed. Examples of processing methods for meltblown nonwoven fabric laminates include lamination of the meltblown nonwoven fabric laminate with other nonwoven fabrics or films, and methods of performing hydrophilization treatment, water-repellent treatment, plasma treatment, or electret treatment by corona charging or water-flow charging on the meltblown nonwoven fabric laminate. These methods are the same as conventional processing methods for nonwoven fabrics.

[0076] 3. Applications of meltblown nonwoven laminates The polymethylpentene-based nonwoven fabric laminates disclosed herein can be widely used in fluid filters, battery separators, electrode supports, and the like. The melting point of polymethylpentene resin is approximately 230°C, which is higher heat resistance than commonly used PP resins. The polymethylpentene-based nonwoven fabric laminate of this disclosure can be manufactured by a process involving high-temperature treatment. Furthermore, the nonwoven fabric separator composed of the polymethylpentene-based nonwoven fabric laminate of this disclosure can be used in batteries requiring higher heat resistance than conventional batteries, and its high basis weight allows for greater safety. In addition, fluffing is suppressed, interlayer bonding is possible, and an improvement in yield during the battery assembly process can be expected.

[0077] The following examples are for illustrative purposes only and are not intended to limit the technical scope of the present invention in any way. [Examples]

[0078] 1. Manufacturing of meltblown nonwoven fabrics 1. Raw material resin for the manufacture of meltblown nonwoven fabric rolls The following raw materials, such as resins, were used in the manufacture of meltblown nonwoven fabric rolls. Polymethylpentene (PMP); melting point 232°C Polymethylpentene resin was used in the raw material hopper of the melt-blown manufacturing apparatus, and the melt-mixing temperature was set to 370°C. The distance between the die and collector was 120 mm, and 30 Nm of heated compressed air at 370°C was used. 3Along with a flow rate of / min / m, resin is discharged into the atmosphere from a single-hole nozzle with a diameter of 0.38 mm, and the suction volume is 60 Nm. 3 Fibrous resin is continuously collected on a collector at a rate of / min, and the rotation speed of the collector is adjusted to determine the basis weight (8~92g / m²) for each sample. 2 A melt-blown nonwoven fabric was obtained.

[0079] Example 1 Weight: 8g / m 2 Weight: 67g / m 2 A melt-blown nonwoven fabric made of polymethylpentene was prepared. The laminate consisting of the two layers was configured so that the rough surfaces faced each other, and was sandwiched between two metal / metal rolls heated to 180°C. The laminate was subjected to calendering under pressure conditions where the roll pressure was set to 130 N / mm as the linear pressure of the rolls. A clearance was provided between the metal rolls so that the thickness of the polymethylpentene melt-blown nonwoven fabric laminate was approximately 0.46 to 0.49 mm. Steel was used as the material for the metal rolls.

[0080] Example 2 Weight: 8g / m 2 Weight: 67g / m 2 A melt-blown nonwoven fabric made of polymethylpentene was prepared. The laminate consisting of the two layers was configured so that the rough surfaces faced each other, and was sandwiched between two metal rolls heated to 195°C. The laminate was subjected to calendering under pressure conditions of 130 N / mm, with the roll pressure being the linear pressure of the rolls. A clearance was provided between the metal rolls so that the thickness of the polymethylpentene melt-blown nonwoven fabric laminate was approximately 0.46 to 0.49 mm. Steel was used as the material for the metal rolls.

[0081] Example 3 Weight: 13g / m 2 Weight: 62g / m 2A melt-blown nonwoven fabric made of polymethylpentene was prepared. The two-layer laminate was configured such that the rough surfaces faced each other and was sandwiched between two metal rolls / metal rolls heated to 180 °C each, and among the pressing conditions, it was subjected to calendering under a pressure condition of 130 N / mm as the linear pressure of the rolls. A clearance adjusted so that the thickness of the melt-blown nonwoven fabric laminate made of polymethylpentene was about 0.46 to 0.49 mm was provided between the metal rolls. Steel was used as the material of the metal rolls.

[0082] Example 4 Areal density 8 g / m 2 and areal density 37 g / m 2 A melt-blown nonwoven fabric made of polymethylpentene was prepared. The two-layer laminate was configured such that the rough surfaces faced each other and was sandwiched between two metal rolls / metal rolls heated to 180 °C each, and among the pressing conditions, it was subjected to calendering under a pressure condition of 130 N / mm as the linear pressure of the rolls. A clearance adjusted so that the thickness of the melt-blown nonwoven fabric laminate made of polymethylpentene was about 0.24 to 0.26 mm was provided between the metal rolls. Steel was used as the material of the metal rolls.

[0083] Example 5 Areal density 8 g / m 2 and areal density 92 g / m 2 A melt-blown nonwoven fabric made of polymethylpentene was prepared. The two-layer laminate was configured such that the rough surfaces faced each other and was sandwiched between two metal rolls / metal rolls heated to 180 °C each, and among the pressing conditions, it was subjected to calendering under a pressure condition of 130 N / mm as the linear pressure of the rolls. A clearance adjusted so that the thickness of the melt-blown nonwoven fabric laminate made of polymethylpentene was about 0.46 to 0.49 mm was provided between the metal rolls. Steel was used as the material of the metal rolls.

[0084] Example 6 Areal density 8 g / m 2 and areal density 67 g / m 2A melt-blown nonwoven fabric made of polymethylpentene was prepared. The two-layer laminate was configured such that the rough surfaces faced each other and was sandwiched between two metal rolls / metal rolls heated to 180 °C each. Among the pressing conditions, the roll pressure was used as the linear pressure of the roll, and it was subjected to calendering under a pressure condition of 130 N / mm. A clearance was provided between the metal rolls so that the melt-blown nonwoven fabric laminate made of polymethylpentene had a thickness adjusted to about 0.30 to 0.33 mm. Steel was used as the material of the metal rolls.

[0085] Comparative Example 1 Areal density 8 g / m 2 and areal density 67 g / m 2 of melt-blown nonwoven fabric made of polymethylpentene were prepared. The two-layer laminate was configured such that the rough surface of areal density 8 g / m 2 and the smooth surface of areal density 67 g / m 2 faced each other and was sandwiched between two metal rolls / metal rolls heated to 180 °C each. Among the pressing conditions, the roll pressure was used as the linear pressure of the roll, and it was subjected to calendering under a pressure condition of 130 N / mm. A clearance was provided between the metal rolls so that the melt-blown nonwoven fabric laminate made of polymethylpentene had a thickness adjusted to about 0.46 to 0.49 mm. Steel was used as the material of the metal rolls.

[0086] Comparative Example 2 Areal density 15 g / m 2 of melt-blown nonwoven fabric made of polymethylpentene were prepared in two layers. The two-layer laminate was configured such that the rough surfaces faced each other and was sandwiched between two metal rolls / metal rolls heated to 180 °C each. Among the pressing conditions, the roll pressure was used as the linear pressure of the roll, and it was subjected to calendering under a pressure condition of 130 N / mm. The clearance was adjusted between the metal rolls until the melt-blown nonwoven fabrics made of polymethylpentene adhered to each other. Steel was used as the material of the metal rolls.

[0087] Comparative Example 3 Areal density 60 g / m 2Two layers of polymethylpentene meltblown nonwoven fabric were prepared. The laminate consisting of these two layers was configured so that the rough surfaces faced each other, and was sandwiched between two metal rolls heated to 180°C. The laminate was subjected to calendering under pressure conditions of 130 N / mm, with the roll pressure being the linear pressure of the rolls. The clearance between the metal rolls was adjusted to bond the two polymethylpentene meltblown nonwoven fabrics together. Steel was used as the material for the metal rolls.

[0088] Comparative Example 4 Weight: 13g / m 2 Weight: 27g / m 2 Meltblown polypropylene nonwoven fabrics were prepared. The laminate consisting of the two layers was configured so that the rough surfaces faced each other, and sandwiched between two metal rolls heated to 120°C. The laminate was subjected to calendering under pressure conditions of 130 N / mm, with the roll pressure being the linear pressure of the rolls. The clearance between the metal rolls was adjusted so that the polypropylene meltblown nonwoven fabric laminate had a thickness of approximately 0.27 to 0.30 mm. Steel was used as the material for the metal rolls.

[0089] Comparative Example 5 Weight: 8g / m 2 Weight: 67g / m 2 A melt-blown nonwoven fabric made of polymethylpentene was prepared. The laminate consisting of the two layers was configured so that the rough surfaces faced each other, and was sandwiched between two metal rolls heated to 160°C. The laminate was subjected to calendering under pressure conditions of 130 N / mm, with the roll pressure being the linear pressure of the rolls. A clearance was provided between the metal rolls so that the thickness of the polymethylpentene melt-blown nonwoven fabric laminate was approximately 0.46 to 0.49 mm. Steel was used as the material for the metal rolls.

[0090] Comparative Example 6 Weight: 45g / m 2A single layer of polymethylpentene meltblown nonwoven fabric was prepared. This single layer of nonwoven fabric was sandwiched between two metal rolls heated to 180°C and subjected to calendering under pressure conditions of 130 N / mm, with the roll pressure being the linear pressure of the rolls. The clearance between the metal rolls was adjusted so that the thickness of the polymethylpentene meltblown nonwoven fabric was approximately 0.24 to 0.26 mm. Steel was used as the material for the metal rolls.

[0091] 2. Measurement methods for various physical properties The following items were measured for each meltblown nonwoven fabric and the meltblown nonwoven laminate after calendering (for Comparative Example 6, it was a single layer of meltblown nonwoven fabric). (1) Average fiber diameter The average fiber diameter was determined by measuring the fiber diameter to the order of 0.1 μm at 20 fibers from five arbitrary locations in electron microscope images of each meltblown nonwoven fabric, and then averaging these measurements. (2) Inspection The moisture content was determined by measuring the mass (g) of each of the 100mm x 100mm meltblown nonwoven fabrics and the calendered meltblown nonwoven fabric laminates in their moisture equilibrium state at a temperature of 23°C and a humidity of 50%, and averaging the results.

[0092] (3) Thickness The thickness of the calendered sample was determined by taking 100mm x 100mm test pieces from the length of the calendered sample, measuring them with a dial thickness gauge KK547-321 (Mitutoyo Corporation), and averaging the measurements of 10 pieces. (4) Filling rate The packing density of the meltblown nonwoven fabric laminate was determined using the following formula. Filling rate (%) = [Balance (g / m²)] 2 ) / (Thickness (mm) × Resin specific gravity (g / cm) 3 The formula is ) × 10).

[0093] (5) Air permeability The air permeability of meltblown nonwoven laminates was measured in accordance with JIS P8117 (2009). A Gurley someter (manufactured by Toyo Seiki Co., Ltd.) was used as the measuring device, and the test specimen was clamped into a circular hole with a diameter of 10 mm and an area of ​​78.5 mm². An inner cylinder mass of 567 g was used to allow air inside the cylinder to pass from the test cylinder to the outside. The time it took for 100 cc of air to pass through was measured and defined as the Gurley value.

[0094] (6) Air permeability Test specimens of 100mm x 100mm meltblown nonwoven fabric laminates were measured using a Frazier type testing machine in accordance with JIS L1096.

[0095] (7) Tensile strength and tensile elongation in the MD direction In accordance with JIS L1085 "Test Method for Nonwoven Fabric Cores," the tensile strength and elongation were measured when a 200mm length of nonwoven fabric was cut parallel to the MD direction and a 15mm width perpendicular to it, and both ends of the nonwoven fabric were clamped with chucks spaced 100mm apart, and the strength (N) and elongation (%) at the maximum load were measured when the fabric was pulled at a speed of 300mm / min.

[0096] (8) Peel Strength A test piece of meltblown nonwoven fabric laminate measuring 100 mm x 100 mm was prepared, and one side of the interlayer in the opposite direction to the direction in which the meltblown nonwoven fabric is wound into the winder during manufacturing was peeled off by 10 mm. One piece of the peeled high-weight nonwoven fabric was clamped with a clip approximately 100 mm wide and fixed so that the clip itself did not move. After attaching a similar clip to an IMADA Push-Pull Scale, the low-weight nonwoven fabric side was clamped, and the scale was pulled so that the nonwoven fabric peeled off at a rate of 20 mm per second, and the maximum value of the peel strength was measured.

[0097] (9) Fuzziness A glass rod with a diameter of 8 mm and a length of 40 cm was placed on the high-weight side and the rough side of the single layer of melt-blown nonwoven fabric of an A4-sized melt-blown nonwoven laminate test specimen. The glass rod was rolled without sliding, applying its own weight, so that it moved 5 cm per second on the nonwoven fabric. The point where the glass rod was initially placed was defined as the zero point. If the glass rod stopped rolling due to fibers becoming entangled in it during the rolling process, that point was defined as the final point, and the distance between the zero point and the final point was measured.

[0098] The distance a glass rod rolled on a high-basis-weight meltblown nonwoven laminate was evaluated. The direction of the glass rod's movement was reversed from the direction in which the meltblown nonwoven laminate was wound into the winder during manufacturing, and it was rolled parallel to the MD direction. A rolling distance of less than 5 cm was marked with ×, 5 cm to less than 15 cm was marked with ○, and rolling distance of 15 cm or more was marked with ◎.

[0099] (10) Thermal shrinkage A 200mm square meltblown nonwoven fabric laminate sample was prepared by drawing 100mm lines in the MD and CD directions at the center and edges. After heating in an oven set to 120°C and 150°C, respectively, for 1 hour, the line length was measured, and the dimensional change rate was determined.

[0100] 3.Results As shown in Table 1, in the polymethylpentene-based nonwoven fabric laminates of Examples 1-6, the rough surfaces of polymethylpentene meltblown nonwoven fabrics with different basis weights faced each other, which suppressed surface fuzzing of the nonwoven fabric and made it possible to produce meltblown nonwoven fabric laminates that are less prone to delamination. Furthermore, the polymethylpentene-based nonwoven fabric laminates of Examples 1-6 showed almost no dimensional change in the MD and CD directions after heat treatment under heating conditions of 120°C and 150°C for 1 hour each (1.2% or less, respectively). This nonwoven laminate has a suitable thickness, high breathability, and high heat resistance, making it suitable for use as a fluid filter, battery separator, and electrode support.

[0101] [Table 1]

Claims

1. A laminate of meltblown nonwoven fabrics is formed by laminating a first meltblown nonwoven fabric made of polymethylpentene resin fibers and a second meltblown nonwoven fabric made of polymethylpentene resin fibers, wherein the basis weight of the entire laminate is 35 g / m². ２ More than 130g / m ２ The difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m². ２ The above describes a meltblown nonwoven fabric laminate having a peel strength of 0.10 N / 100 mm width or more.

2. The basis weight of the second meltblown nonwoven fabric is 30 g / m². ２ 120g / m or more ２ The meltblown nonwoven fabric laminate according to claim 1, which is as follows:

3. The first meltblown nonwoven fabric has a basis weight of 15 g / m². ２ The meltblown nonwoven fabric laminate according to claim 1 or claim 2, which is as follows:

4. The meltblown nonwoven fabric laminate according to claim 1, wherein the thickness of the meltblown nonwoven fabric laminate is 0.20 mm or more and 0.70 mm or less.

5. The meltblown nonwoven fabric laminate according to claim 1, wherein the lamination structure of the meltblown nonwoven fabric laminate is a two-layer structure.

6. Having both a rough and a smooth surface, the first meltblown nonwoven fabric has a basis weight of 15 g / m². ２ The following is a step for preparing a first meltblown nonwoven fabric made of polymethylpentene resin fibers: Having a rough surface and a smooth surface, and the basis weight of the second melt-blown nonwoven fabric is 30 g / m ２ or more and 120 g / m ２ or less, a step of preparing a second melt-blown nonwoven fabric made of polymethylpentene-based resin fibers, and A process of laminating a first meltblown nonwoven fabric and a second meltblown nonwoven fabric such that the rough surface of the first meltblown nonwoven fabric and the rough surface of the second meltblown nonwoven fabric face each other. A method for producing a meltblown nonwoven fabric laminate containing [the specified substance].

7. The process further includes, after the lamination step, calendering the laminate of the first meltblown nonwoven fabric and the second meltblown nonwoven fabric at a temperature of 170°C or higher under pressurized conditions. The manufactured meltblown nonwoven laminate has a basis weight of 35 g / m² for the entire laminate. ２ More than 130g / m ２ The difference in basis weight between the first melt-blown nonwoven fabric and the second melt-blown nonwoven fabric before lamination is 15 g / m². ２ The manufacturing method according to claim 6, wherein the peel strength is 0.10 N / 100 mm width or more.

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