Nonwoven fabric roll and method for producing the same

Abstract

The present invention provides a nonwoven fabric roll having sufficient mechanical strength and dimensional stability and excellent film coating processability in a wide-width die coating method. The nonwoven fabric roll of the present invention is a nonwoven fabric roll in which a long-fiber nonwoven fabric containing fibers mainly composed of a thermoplastic resin is wound into a roll, wherein the apparent density of the long-fiber nonwoven fabric is 0.70 g / cm 3 Above 0.90g / cm 3 Hereinafter, the nonwoven fabric roll has a winding hardness of 35.0 g to 50.0 g, and a hardness difference in a roll width direction of 7.0 g to 20.0 g.

Description

Technical Field

[0001] The present invention relates to a nonwoven fabric roll and a method for producing the same. Background Art

[0002] Membrane technology has been widely used in water treatment in recent years, and separation membranes are used in applications such as water treatment in water purification plants and desalination of seawater.

[0003] Semipermeable membranes, such as reverse osmosis membranes, used in seawater desalination, are typically flat membranes integrated with a support such as a nonwoven or woven fabric. Reverse osmosis membranes are manufactured by methods such as casting a polymer solution onto a support such as a nonwoven or woven fabric to form a support layer, and then forming a semipermeable membrane on this support layer.

[0004] The process for forming this support layer includes the following methods: a comma coating method, in which the resin solution cast between a roller with blades and the support is accumulated and the blades scrape off excess resin solution; and a die coating method, in which a die head, acting as a mold, is brought into contact with the support to apply the resin solution. In the comma coating method, the presence of foreign matter or protrusions between the blades and the support can cause the support to break, degrading process flow. Therefore, die coating is preferred for forming the support layer.

[0005] In addition, when forming the support layer, it is required that when the polymer solution is cast or coated on the non-woven fabric, woven fabric, etc. that serves as the support, excellent film-forming properties are required, such that the polymer solution does not penetrate the substrate due to over-permeation, the membrane material is not peeled off, and defects such as film unevenness and pinholes caused by the fuzzing of the support are not generated.

[0006] Reverse osmosis membranes used in seawater desalination are sometimes operated continuously at a constant operating pressure or at a varying operating pressure in response to changes in the quality and temperature of the supplied seawater, changes in the amount of fresh water produced, and the like.

[0007] Therefore, supports such as nonwoven fabrics and woven fabrics are required to have high mechanical strength, high dimensional stability, and high film peeling strength. Therefore, supports comprising long-fiber nonwoven fabrics composed of thermoplastic continuous filaments have been proposed (see Patent Document 1).

[0008] In addition, regarding a semipermeable membrane support body comprising a nonwoven fabric for forming a membrane by a comma coating method, it has been proposed that the nonwoven fabric has an air permeability of 5 to 50 cc / cm 2 / second low-density layer and air permeability of 0.1cc / cm 2 / second or more and less than 5cc / cm 2 / sec high-density layer laminated and integrated into a double-layer non-woven fabric, and the overall air permeability of the non-woven fabric is 0.1 ~ 4.5cc / cm 2 / sec semipermeable membrane supporting body (see Patent Document 2).

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: International Publication No. 2009 / 017086

[0012] Patent Document 2: Japanese Patent Publication No. 5-35009 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] However, the technology disclosed in Patent Document 1 is based on a support body of a long-fiber nonwoven fabric containing continuous filaments. Therefore, in the die coating method for coating a uniform film, defects caused by uneven thickness of the support body occur. This unevenness becomes more obvious when the nonwoven fabric is rolled, and there is a problem of poor film formation and wrinkles.

[0015] Furthermore, the technology disclosed in Patent Document 2 produces a nonwoven fabric composed of short fibers rather than continuous filaments, which may lead to film non-uniformity and defects due to fuzzing. Furthermore, the strength of the nonwoven fabric serving as a support is not improved, and sufficient mechanical strength and dimensional stability cannot be achieved as a support.

[0016] Therefore, an object of the present invention is to provide a nonwoven fabric roll comprising a long-fiber nonwoven fabric, having sufficient mechanical strength and dimensional stability, and also having excellent film coating processability in a wide-width die coating method.

[0017] Means for solving problems

[0018] The present invention aims to solve the above-mentioned problems, and according to the present invention, the following technical solutions can be provided.

[0019] [1] A nonwoven fabric roll comprising a long-fiber nonwoven fabric containing fibers mainly composed of a thermoplastic resin wound into a roll, wherein the apparent density of the long-fiber nonwoven fabric is 0.70 g / cm 3 Above 0.90g / cm 3 Hereinafter, the nonwoven fabric roll has a winding hardness of 35.0 g to 50.0 g, and a hardness difference in the roll width direction of 7.0 g to 20.0 g.

[0020] [2] The nonwoven fabric roll according to [1] above, wherein the winding length of the nonwoven fabric roll is not less than 100 m and not more than 20,500 m, and the difference between the thickness of the long-fiber nonwoven fabric in the outer layer of the roll and the thickness of the long-fiber nonwoven fabric in the inner layer of the roll is not more than 0.010 mm.

[0021] [3] The nonwoven fabric roll according to [1] or [2] above, wherein the roll width of the nonwoven fabric roll is not less than 0.5 m and not more than 1.5 m.

[0022] [4] The nonwoven fabric roll according to any one of [1] to [3] above, wherein the smoothness of the long-fiber nonwoven fabric is 10 seconds to 60 seconds on both sides.

[0023] [5] The nonwoven fabric roll according to any one of [1] to [4] above, wherein the thermoplastic resin is a polyester resin.

[0024] [6] A method for producing a nonwoven fabric roll, wherein the following steps (a) to (d) are carried out in sequence.

[0025] Step (a): After spinning a thermoplastic resin from a spinneret 1 having a discharge hole to obtain a long fiber,

[0026] The gas is passed through the cooling section 2 in a direction perpendicular to the direction of travel of the long fibers and contacts the long fibers.

[0027] Next, gas is passed from the gas supply unit 3 in a direction perpendicular to the direction of travel of the long fibers so as to contact the long fibers.

[0028] The long fiber is passed through an air intake and exhaust section 4 having a length of 1 mm to 150 mm and is disposed directly below the gas supply section 3, and is subjected to suction stretching at a spinning speed of 3000 m / min to 5500 m / min.

[0029] Step (b): The stretched long fibers are collected on a moving net conveyor 6 to form a fiber web 9;

[0030] Step (c): temporarily bonding the fiber web 9 with a pair of flat temporary pressing rollers 7 having a roller surface temperature 60°C to 120°C lower than the melting point of the thermoplastic resin at a linear pressure of 100 N / cm to 700 N / cm to obtain a nonwoven fabric sheet 10;

[0031] Step (d): Overlap two or more layers of the nonwoven fabric sheet, and heat-press them using a pair of flat rollers, at least one of which has a roller surface temperature that is 20°C or higher and 100°C or lower than the roller surface temperature of the step (c), at a linear pressure of 500N / cm or higher and 5000N / cm or lower to obtain a long-fiber nonwoven fabric, and then wind the long-fiber nonwoven fabric to obtain a nonwoven fabric roll.

[0032] [7] The method for producing a nonwoven fabric roll according to [6], wherein the step (a) is the following (a'), the melting point of the thermoplastic resin in the step (c) is the melting point of the low-melting-point polymer,

[0033] Step (a'): spinning a high melting point polymer and a low melting point polymer having a melting point 10°C or more and 110°C or less lower than the melting point of the high melting point polymer from a composite spinneret 1 having a discharge hole,

[0034] A long fiber is obtained in which the low melting point polymer covers the high melting point polymer in such a manner that the high melting point polymer is not exposed, and then,

[0035] The gas is passed through the cooling portion 2 in a direction perpendicular to the direction of travel of the long fibers and contacts the long fibers.

[0036] Next, gas is passed from the gas supply unit 3 in a direction perpendicular to the direction of travel of the long fibers so as to contact the long fibers.

[0037] The long fibers are passed through an air intake and exhaust portion 4 having a length of 1 mm to 150 mm and located just below the gas supply portion 3.

[0038] Suction stretching is performed at a spinning speed of 3000 m / min to 5500 m / min.

[0039] [8] The method for producing a nonwoven fabric roll according to [6] or [7] above, wherein the thermoplastic resin in step (a) is a polyester resin, or the high melting point polymer and / or low melting point polymer in step (a') is a polyester resin.

[0040] [9] The method for producing a nonwoven fabric roll according to any one of [6] to [8], wherein in the step (d), the nonwoven fabric sheets obtained by dividing the nonwoven fabric sheets in the width direction in the step (c) are overlapped and heat-compression-bonded in a manner satisfying the following formula (1) to obtain a long-fiber nonwoven fabric, and then the long-fiber nonwoven fabric is wound to obtain a nonwoven fabric roll.

[0041] 0.90≤W Min / W Max ≤1.00 ··· (1)

[0042] Here, the maximum mass per unit area W is set in the width direction of the overlapped nonwoven fabric sheets. Max (g / m 2 ) and minimum unit area mass W Min (g / m 2 ).

[0043]

[10] The method for producing a nonwoven fabric roll according to any one of [6] to [9] above, wherein the apparent density of the long-fiber nonwoven fabric is 0.70 g / cm 3 Above 0.90g / cm3 Hereinafter, the nonwoven fabric roll has a winding hardness of 35.0 g to 50.0 g, and a hardness difference in the roll width direction of 7.0 g to 20.0 g.

[0044] Effects of the Invention

[0045] According to the present invention, it is possible to provide a nonwoven fabric roll which has sufficient mechanical strength and dimensional stability when used as a separation membrane support and is excellent in membrane coating processability in a wide-width die coating method. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] [ Figure 1 ] Figure 1 This is a schematic diagram of a production apparatus for spinning a thermoplastic resin from a spinneret to obtain a nonwoven fabric roll according to the method for producing a nonwoven fabric roll of the present invention. DETAILED DESCRIPTION

[0047] A nonwoven fabric roll according to one embodiment of the present invention is a nonwoven fabric roll in which a long-fiber nonwoven fabric containing fibers mainly composed of a thermoplastic resin is wound into a roll, wherein the apparent density of the long-fiber nonwoven fabric is 0.70 g / cm 3 Above 0.90g / cm 3 The nonwoven fabric roll has a winding hardness of 35.0 g to 50.0 g, and a hardness difference in the width direction of 7.0 g to 20.0 g. The components are described in detail below, but the present invention is not limited to the following description, and various modifications can be made without departing from the spirit of the present invention.

[0048] (thermoplastic resin)

[0049] A nonwoven fabric roll according to one embodiment of the present invention is a nonwoven fabric roll in which a long-fiber nonwoven fabric containing fibers mainly composed of a thermoplastic resin is wound into a roll.

[0050] Examples of the thermoplastic resin include polyester, polyamide, polyolefin, and mixtures and copolymers thereof, among which polyester is preferred due to its superior durability such as mechanical strength, heat resistance, water resistance, and chemical resistance.

[0051] Polyester is formed from an acid component and an alcohol component. Examples of the acid component include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid; aliphatic dicarboxylic acids such as adipic acid and sebacic acid; and alicyclic dicarboxylic acids such as cyclohexanecarboxylic acid. Examples of the alcohol component include ethylene glycol, diethylene glycol, and polyethylene glycol.

[0052] Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate, and copolymers thereof.

[0053] (Fibers mainly composed of thermoplastic resin)

[0054] The fibers primarily composed of thermoplastic resins may be supplemented with crystal nucleating agents, matting agents, lubricants, pigments, mildew inhibitors, antibacterial agents, flame retardants, and hydrophilic agents. In particular, when thermocompression molding long-fiber nonwoven fabrics, it is preferred to add metal oxides such as titanium oxide, which improve the adhesion of the long-fiber nonwoven fabric by increasing thermal conductivity; aliphatic bisamides such as ethylene bisstearamide, which improve the release properties between the thermocompression roller and the fiber web and enhance bonding stability; and / or alkyl-substituted aliphatic monoamides. These various additives may be present within the thermoplastic fibers or on their surfaces.

[0055] Examples of the cross-sectional shape of the fiber containing a thermoplastic resin as a main component include circular, flat, polygonal, multilobal (such as X-shaped and Y-shaped), and hollow shapes.

[0056] Furthermore, it is also preferable that the fibers containing a thermoplastic resin as a main component are composite fibers.

[0057] The conjugate fiber is preferably a conjugate fiber in which a low-melting-point polymer having a melting point lower than that of the high-melting-point polymer is blended around a high-melting-point polymer.

[0058] By making such a composite fiber, the thermoplastic continuous fibers can be firmly bonded in the nonwoven fabric during thermocompression bonding, thereby achieving surface smoothness. When used as a support, unevenness and film defects during casting of a polymer solution caused by fiber fuzz can be suppressed.

[0059] In addition, by making such composite fibers, in addition to the long fiber webs constituting the non-woven fabric being firmly bonded to each other, the number of bonding points in the non-woven fabric is also greater than that obtained by mixing fibers with different melting points. Therefore, the dimensional stability and durability of the support body, especially when used as a semipermeable membrane support body to which high pressure is applied during use, are improved.

[0060] Here, the main component refers to a component that accounts for 50% by mass or more of the components of the conjugate fiber.

[0061] The difference in melting points between the high-melting point polymer and the low-melting point polymer is preferably 10°C or higher and 110°C or lower. By setting the melting point difference to 10°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher, desired thermal adhesiveness can be achieved. Furthermore, by setting the melting point difference to 110°C or lower, more preferably 100°C or lower, and even more preferably 90°C or lower, it is possible to prevent a decrease in productivity due to fusion of the low-melting point polymer component with the thermocompression bonding rollers during thermocompression bonding.

[0062] The melting point of the high-melting-point polymer in the conjugated fiber is preferably 160°C or higher and 320°C or lower. By setting the melting point of the high-melting-point polymer to 160°C or higher, more preferably 170°C or higher, and even more preferably 180°C or higher, excellent morphological stability is achieved even during processing steps involving heat. Furthermore, by setting the melting point of the high-melting-point polymer to 320°C or lower, more preferably 300°C or lower, and even more preferably 280°C or lower, it is possible to suppress the reduction in productivity caused by the large amount of heat energy consumed for melting during the production of the long-fiber nonwoven fabric.

[0063] On the other hand, the melting point of the low-melting-point polymer in the conjugated fiber is preferably 150°C or higher and 310°C or lower, while ensuring a sufficient difference between the melting points of the high-melting-point polymer and the low-melting-point polymer. By setting the melting point of the low-melting-point polymer to 150°C or higher, more preferably 160°C or higher, and even more preferably 170°C or higher, excellent morphological stability is achieved even during processing steps involving heat. Furthermore, by setting the melting point of the low-melting-point polymer to 310°C or lower, more preferably 290°C or lower, and even more preferably 270°C or lower, it is possible to suppress the reduction in productivity caused by the excessive consumption of heat energy for melting during the production of the long-fiber nonwoven fabric.

[0064] Specific examples of the combination of the high melting point polymer and the low melting point polymer (high melting point polymer / low melting point polymer) include polyethylene terephthalate / polybutylene terephthalate, polyethylene terephthalate / polypropylene terephthalate, polyethylene terephthalate / polylactic acid, polyethylene terephthalate / copolyethylene terephthalate, etc. Preferred copolymer components of the copolyethylene terephthalate include isophthalic acid and the like.

[0065] In addition, in this invention, the melting point of a thermoplastic resin adopts the value measured as follows.

[0066] (1) Using a differential scanning calorimeter, one measurement is performed under the following conditions: As the differential scanning calorimeter, for example, "Q100" manufactured by TA Instruments can be used.

[0067] Measurement atmosphere: Nitrogen flow (150 mL / min)

[0068] Temperature range: 30~350℃

[0069] Heating rate: 20℃ / min

[0070] Sample size: 5 mg

[0071] (2) Calculate the average value of the endothermic peak apex temperature as the melting point of the measurement object. However, if there are multiple endothermic peaks in the resin before forming the fiber, the peak apex temperature on the highest temperature side is used. Alternatively, when the fiber is used as the measurement object, the measurement is performed in the same manner, and the melting points of each component are estimated based on the multiple endothermic peaks. In this case, the endothermic peak obtained from the composite fiber is a peak group consisting of an endothermic peak (A) on the highest temperature side and an endothermic peak (B) that appears on the side with the shorter elapsed time (the side where the peak appears first) and is the next highest peak after the endothermic peak on the highest temperature side. The endothermic peak (A) indicates the melting point of the high-melting-point polymer, while the endothermic peak (B) indicates the melting point of the low-melting-point polymer.

[0072] The proportion of the low-melting-point polymer in the conjugated fiber is preferably 10% to 70% by mass of the conjugated fiber. By setting the proportion of the low-melting-point polymer in the conjugated fiber to 10% by mass or greater, more preferably 15% by mass or greater, and even more preferably 20% by mass or greater, desired thermal adhesive properties can be achieved. Furthermore, by setting the proportion of the low-melting-point polymer in the conjugated fiber to 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, it is possible to prevent the low-melting-point polymer component from fusing to the hot-pressing rollers during hot-pressing, thereby reducing productivity.

[0073] Examples of the composite fiber's composite form include a concentric core-sheath type, an eccentric core-sheath type, and an island-in-the-sea type. Of these, a concentric core-sheath type, particularly one in which a low-melting-point polymer forms the sheath component, is preferred because it allows for strong bonding of the fibers by thermocompression bonding. When the composite fiber has a profiled cross-section, it is preferred that the low-melting-point polymer component be present near the outer periphery of the fiber cross-section to facilitate thermocompression bonding.

[0074] When the composite fibers described above are used, a circular cross-sectional shape is particularly preferred, as this allows the fibers to be uniformly and firmly fused together to form a long-fiber nonwoven fabric having excellent mechanical strength.

[0075] The fibers primarily composed of thermoplastic resin preferably have an average single fiber diameter of 3 μm or more and 17 μm or less. By preferably having an average single fiber diameter of 3 μm or more, more preferably 7 μm or more, and even more preferably 10 μm or more, spinnability is minimized during the production of long-fiber nonwoven fabrics, and the air permeability of the support is maintained. Consequently, film peeling and other issues are minimized during casting of the polymer solution, resulting in excellent film-forming properties.

[0076] On the other hand, by making the average single fiber diameter preferably less than 17 μm, more preferably less than 15 μm, and further preferably less than 14 μm, a long-fiber non-woven fabric and a support body with excellent uniformity can be obtained, and the support body can be made high-density, so that the over-permeation of the high molecular polymer solution during casting is reduced, and good film-forming properties can be obtained.

[0077] In addition, the average single fiber diameter (μm) of the above-mentioned fibers mainly composed of a thermoplastic resin is a value calculated by the following procedure.

[0078] (1) Ten small samples (100 mm × 100 mm) were randomly collected from the long-fiber nonwoven fabric.

[0079] (2) Take a surface photograph at 500x to 3000x magnification using a microscope (e.g., "VHX-D500" manufactured by KEYENCE CORPORATION), and measure the diameters of 10 single fibers from each sample, for a total of 100 single fibers.

[0080] (3) The arithmetic mean of the values ​​of 100 fibers measured was rounded off to the first decimal place to calculate the average single fiber diameter (μm).

[0081] (Long fiber non-woven fabric)

[0082] The apparent density of the long fiber nonwoven fabric according to one embodiment of the present invention is 0.70 g / cm 3 Above 0.90g / cm 3 By making the apparent density of the long fiber nonwoven fabric 0.70 g / cm 3 Above, preferably 0.75g / cm 3 More preferably, 0.80 g / cm 3 As a result, the over-permeation during the casting of the polymer solution is small, and good membrane forming properties can be obtained, and a separation membrane with high membrane peel strength and mechanical strength and excellent durability can be obtained. On the other hand, by making the apparent density of the long fiber nonwoven fabric 0.90 g / cm 3 Below, preferably 0.88 / cm 3 Below, more preferably 0.85g / cm 3As a result, the polymer solution can quickly penetrate into the support and firmly adhere to the support during casting, thereby obtaining a separation membrane having excellent membrane peeling strength.

[0083] It should be noted that the apparent density (g / cm 3 ) is calculated by the following steps.

[0084] (1) The unit area mass of long fiber nonwoven fabric (g / m 2 ) divided by the value converted from the thickness of the long-fiber nonwoven fabric (mm), and the value calculated by rounding off to the third decimal place was adopted.

[0085] The basis weight and thickness of the long-fiber nonwoven fabric are calculated by the following procedure.

[0086] The mass per unit area of ​​the long fiber nonwoven fabric is preferably 20 g / m 2 Above 150g / m 2 By making the unit area mass preferably 20g / m 2 More than 30 g / m 2 More preferably, 40 g / m 2 The above values ​​can reduce the over-permeation during polymer solution casting and thus obtain good membrane forming properties, thereby obtaining a separation membrane having high membrane peeling strength and mechanical strength and excellent durability. 2 Below, more preferably 120g / m 2 Below, more preferably 90g / m 2 As a result, when used as a support, the thickness can be reduced, and the separation membrane area per fluid separation element unit can be increased.

[0087] It should be noted that the unit area mass (g / m 2 ) is calculated by the following steps.

[0088] (1) Collect three pieces of 30 cm × 50 cm long-fiber non-woven fabrics.

[0089] (2) The mass of each sample was measured, and the average of the obtained values ​​was converted into mass per unit area (g). The mass per unit area was calculated by rounding off to the first decimal place.

[0090] In addition, the thickness of the long fiber nonwoven fabric is preferably 0.030 mm or more and 0.200 mm or less. By making the thickness of the long fiber nonwoven fabric preferably 0.030 mm or more, more preferably 0.040 mm or more, and further preferably 0.050 mm or more, when used as a support, the over-permeation during the casting of the polymer solution is reduced, and good film forming properties can be obtained. In addition, due to its high dimensional stability, curling and bending after film formation are suppressed and excellent processability can be obtained during the manufacture of the fluid separation element, and a separation membrane with high membrane peel strength and mechanical strength and excellent durability can be obtained. On the other hand, by making the thickness of the long fiber nonwoven fabric preferably 0.200 mm or less, more preferably 0.160 mm or less, and further preferably 0.120 mm or less, the thickness of the separation membrane can be reduced, thereby increasing the separation membrane area per fluid separation element unit.

[0091] In addition, the thickness (mm) of the long-fiber nonwoven fabric was calculated by the following procedure.

[0092] (1) Using a pressure head having a diameter of 10 mm and a load of 10 kPa, the thickness of the long-fiber nonwoven fabric was measured at 10 locations per 1 m at equal intervals of 0.01 mm in units of 0.01 mm in the width direction.

[0093] (2) Round off the average of the above 10 values ​​to the fourth decimal place.

[0094] The smoothness of the long-fiber nonwoven fabric of one embodiment of the present invention is preferably 10 seconds or more and 60 seconds or less on both sides. By making the smoothness of the long-fiber nonwoven fabric preferably 10 seconds or more, more preferably 15 seconds or more, and even more preferably 20 seconds or more, it is possible to suppress excessive penetration of the coagulation liquid with water as the main component from the back of the support into the interior during the manufacture of the separation membrane, and to allow the polymer solution cast on the support to fully penetrate into the interior of the support and then coagulate, thereby improving the membrane peel strength of the formed separation membrane. In addition, it is possible to suppress damage to the separation membrane surface caused by friction between the membrane forming surface and the back during the winding process when manufacturing the separation membrane. On the other hand, by making the smoothness of the long-fiber nonwoven fabric preferably 60 seconds or less, more preferably 50 seconds or less, and even more preferably 45 seconds or less, the air inside the support is quickly discharged during the manufacture of the separation membrane, which can suppress the reduction of partial membrane peel strength and the generation of membrane defects such as pinholes.

[0095] The smoothness (seconds) of the long-fiber nonwoven fabric was calculated by the following procedure.

[0096] (1) Collect three pieces of long-fiber nonwoven fabric with a width of 10 cm in the longitudinal direction.

[0097] (2) Using a smoothness tester (e.g., "Oken Smoothness Tester EBO1-5" manufactured by Asahi Seiko Co., Ltd.), the smoothness (in Becquerel-seconds) is measured at intervals of 10 cm in the width direction on both sides of the long-fiber nonwoven fabric using a smoothness tester (e.g., "Oken Smoothness Tester EBO1-5" manufactured by Asahi Seiko Co., Ltd.) in accordance with JIS P8155:2010 "Paper and paperboard - Smoothness test method - Oken method"). For example, if the width of the nonwoven fabric is 105 cm, the smoothness is measured at 10 locations at equal intervals of 10 cm, excluding 7.5 cm at both ends.

[0098] (3) Calculate the arithmetic mean of the measured values ​​for both sides and round off to the nearest decimal place. Calculate the arithmetic mean of the measured values ​​for both sides of the three long-fiber nonwoven fabrics collected and round off to the nearest decimal place to obtain the smoothness (seconds).

[0099] In addition, in order to make the smoothness of the long-fiber nonwoven fabric within the above-mentioned range, this can be achieved by adjusting the surface temperature and linear pressure of the upper and lower flat temporary pressing rollers in the temporary bonding and thermal pressing steps of the nonwoven fabric sheet manufacturing method to the range described below.

[0100] (Non-woven fabric roll)

[0101] The nonwoven fabric roll according to one embodiment of the present invention has a winding hardness of 35.0 g or more and 50.0 g or less.

[0102] By setting the winding hardness of the nonwoven fabric roll to 35.0 g or more, preferably 37.0 g or more, and more preferably 40.0 g or more, a nonwoven fabric roll can be obtained that is free of winding deviation and wrinkles during relaxation. On the other hand, by setting the winding hardness of the nonwoven fabric roll to 50.0 g or less, preferably 48.0 g or less, and more preferably 47.0 g or less, excessive winding tension is not applied to the nonwoven fabric roll, and no load is applied to the winding core, thereby achieving a nonwoven fabric roll that does not wrinkle the long-fiber nonwoven fabric.

[0103] In addition, the hardness difference in the width direction of the non-woven fabric roll is 7.0 g or more and 20.0 g or less. By making the hardness difference in the width direction of the non-woven fabric roll 7.0 g or more, preferably 8.0 g or more, and more preferably 9.0 g or more, the support film has excellent processability when it is coated using a die coating method as a wide support. On the other hand, by making the hardness difference in the width direction of the non-woven fabric roll 20.0 g or less, preferably 19.0 g or less, and more preferably 18.0 g or less, deformation caused by uneven width direction when the support is lengthened can be suppressed, and the occurrence of poor coating during the manufacture of the separation membrane can be suppressed.

[0104] The winding hardness (g) and the hardness difference (g) in the width direction of the nonwoven fabric roll were calculated by the following procedure.

[0105] (1) Using a roll hardness meter (e.g., the "RoQ Roll Hardness Tester" manufactured by ACA System), a total of three measurements are made in the same direction from the 3 o'clock or 9 o'clock angle from the end in the width direction to the other end when the non-woven fabric roll is left to stand. The arithmetic mean of the values ​​obtained at intervals of 0.2 cm in the width direction is rounded to the second decimal place to calculate the roll hardness (g) of the non-woven fabric roll. It should be noted that the "RoQ Roll Hardness Tester" manufactured by ACA System has a hammer on the bottom surface of the tester, which has a negative gravity acceleration when the hammer hits the roll surface and the hammer contacts the roll surface and decelerates until it stops, which is used as the hardness (unit: g, 1g = 9.81m / s 2 ) The mechanism by which measurements are made.

[0106] (2) Calculate the difference between the maximum and minimum values ​​of the hardness data obtained by the above method at intervals of 0.2 cm in the width direction, excluding the 7.5 cm at both ends, and round off to the second decimal place to calculate the hardness difference (g) in the roll width direction.

[0107] The winding hardness of the nonwoven fabric roll can be adjusted to the above range by adjusting the surface temperature and linear pressure of the upper and lower flat temporary pressing rollers in the temporary bonding and thermocompression bonding steps of the nonwoven fabric sheet production method to the ranges described below.

[0108] In order to make the hardness difference in the width direction of the nonwoven fabric roll within the above range, the maximum unit area weight W of the overlapped nonwoven fabric sheet in the manufacturing method can be set to Max (g / m 2 ) and minimum unit area mass W Min (g / m 2 ) is adjusted to the range described below.

[0109] The nonwoven fabric roll according to one embodiment of the present invention preferably has a winding length of 100 m to 20,500 m. By preferably setting the winding length of the nonwoven fabric roll to 100 m or more, more preferably 1000 m or more, and even more preferably 3000 m or more, a nonwoven fabric roll with excellent handleability during separation membrane production can be obtained. On the other hand, by preferably setting the winding length of the nonwoven fabric roll to 20,500 m or less, more preferably 15,500 m or less, and even more preferably 11,500 m or less, excessive winding tension can be prevented, deformation of the winding core can be suppressed, and a nonwoven fabric roll with excellent handleability during transport can be obtained.

[0110] In one embodiment of the nonwoven fabric roll of the present invention, the difference in thickness between the outer nonwoven fabric layer and the inner nonwoven fabric layer is preferably 0.010 mm or less. By setting the difference in thickness between the outer nonwoven fabric layer and the inner nonwoven fabric layer to preferably 0.010 mm or less, more preferably 0.005 mm or less, and even more preferably 0.003 mm or less, the inner nonwoven fabric layer can be wound while suppressing winding deviation when the roll length is increased.

[0111] Regarding the inner layer non-woven fabric and outer layer non-woven fabric described here, the distance within 10% of the winding core side after subtracting the radius of the winding core from the radius of the non-woven fabric roll is set as the inner layer non-woven fabric, and the distance within 10% of the outermost side of the non-woven fabric roll is set as the outer layer non-woven fabric, indicating the thickness of a piece of non-woven fabric located in the above-mentioned ranges.

[0112] The thickness (mm) and the difference in thickness (mm) of the long-fiber nonwoven fabric were calculated by the following procedure.

[0113] (1) Collect the non-woven fabric from the inner layer and outer layer of the roll at random at three locations.

[0114] (2) Using a 10 mm diameter pressure probe (e.g., Dial gauge 2109S-10 (surface measuring instrument: 101117) manufactured by Mitutoyo Co., Ltd.), measure the thickness of any nonwoven fabric sampled at equal intervals of 10 cm along the width direction in 0.001 mm increments at a load of 10 kPa. For example, if the nonwoven fabric is 105 cm wide, measure the thickness at 10 locations at equal intervals of 10 cm, excluding the 7.5 cm at both ends.

[0115] (3) For each of the three inner and outer nonwoven fabrics, the average value of the values ​​measured at the above-mentioned equal intervals is calculated, and the arithmetic average of the three average values ​​of each of the inner and outer nonwoven fabrics is rounded off to the fourth decimal place to obtain the thickness of the inner and outer nonwoven fabrics.

[0116] (4) Calculate the difference between the thickness of the inner layer nonwoven fabric of the roll and the thickness of the outer layer nonwoven fabric of the roll.

[0117] The core used in the nonwoven fabric roll of the present invention can be made of a standard paper tube, polyethylene, polypropylene, or ABS resin. However, a paper tube with metal reinforcement or a fiber-reinforced plastic core is preferred to prevent the core from flattening during long rolls. The outer diameter of the core of the nonwoven fabric roll is not critical, but wrinkles are more likely to form during initial winding. To facilitate winding, it is preferably 50 mm or larger, and preferably 200 mm or smaller for logistical loading efficiency.

[0118] The nonwoven fabric roll according to one embodiment of the present invention preferably has a roll width of 0.5 m or more and 1.5 m or less. By setting the roll width to preferably 0.5 m or more, more preferably 0.6 m or more, and even more preferably 0.7 m or more, a nonwoven fabric roll with excellent productivity during support manufacturing can be obtained. On the other hand, by setting the roll width to 1.5 m or less, more preferably 1.4 m or less, and even more preferably 1.3 m or less, a nonwoven fabric roll with excellent processability during support manufacturing can be obtained without compromising the effects of unevenness in the width direction of the nonwoven fabric roll.

[0119] Furthermore, in the present invention, the winding offset of the nonwoven fabric roll is preferably between 0 mm and 8 mm. The winding offset refers to the distance between the roll end and the portion of the nonwoven fabric that protrudes outward. The winding offset of the nonwoven fabric roll is further preferably 5 mm or less. This allows for processing without causing wrinkles due to meandering during support processing.

[0120] (Method for manufacturing nonwoven fabric roll)

[0121] Next, the method for producing a nonwoven fabric roll of the present invention is characterized in that the following steps (a) to (d) are carried out in sequence. Figure 1 Provide detailed explanation.

[0122] Step (a): After spinning a thermoplastic resin from a spinneret 1 having discharge holes to obtain long fibers, gas is passed from a cooling section 2 in a direction perpendicular to the direction of travel of the long fibers so as to contact the long fibers. Subsequently, gas is passed from a gas supply section 3 in a direction perpendicular to the direction of travel of the long fibers so as to contact the long fibers. The long fibers are then passed through an intake and exhaust section 4 having a length of 1 mm to 150 mm and disposed directly below the gas supply section 3, and suction-stretched at a spinning speed of 3000 m / min to 5500 m / min.

[0123] Step (b): The stretched long fibers are collected on a moving net conveyor 6 to form a fiber web 9;

[0124] Step (c): temporarily bonding the fiber web 9 with a pair of flat temporary pressing rollers 7 having a roller surface temperature 60°C to 120°C lower than the melting point of the thermoplastic resin at a linear pressure of 100 N / cm to 700 N / cm to obtain a nonwoven fabric sheet 10;

[0125] Step (d): Overlap two or more layers of the nonwoven fabric sheet, and heat-press them using a pair of flat rollers, at least one of which has a roller surface temperature that is 20°C or higher and 100°C or lower than the roller surface temperature of the step (c), at a linear pressure of 500N / cm or higher and 5000N / cm or lower to obtain a long-fiber nonwoven fabric, and then wind the long-fiber nonwoven fabric to obtain a nonwoven fabric roll.

[0126] When core-sheath type composite fibers are used as the fibers constituting the long fiber nonwoven fabric, it is preferable to carry out the following operation: That is, the step (a) is the following (a'), and the melting point of the thermoplastic resin in the step (c) is the melting point of the low-melting-point polymer.

[0127] Step (a'): spinning a high melting point polymer and a low melting point polymer having a melting point 10°C or more and 110°C or less lower than the melting point of the high melting point polymer from a composite spinneret 1 having a discharge hole,

[0128] A long fiber is obtained in which the low melting point polymer covers the high melting point polymer in such a manner that the high melting point polymer is not exposed, and then,

[0129] The gas is passed through the cooling portion 2 in a direction perpendicular to the direction of travel of the long fibers and contacts the long fibers.

[0130] Next, gas is passed from the gas supply unit 3 in a direction perpendicular to the direction of travel of the long fibers so as to contact the long fibers.

[0131] The long fibers are passed through an air intake and exhaust portion 4 having a length of 1 mm to 150 mm and located just below the gas supply portion 3.

[0132] Suction stretching is performed at a spinning speed of 3000 m / min to 5500 m / min.

[0133] (a) Process of obtaining long fibers and then performing suction stretching

[0134] Examples of methods for producing the long-fiber nonwoven fabric constituting the nonwoven fabric roll of the present invention include spunbonding, flash spinning, wet spinning, carding, and air-laying.

[0135] Among these, spunbond nonwoven fabrics produced by the spunbond method are a preferred embodiment. Spunbond nonwoven fabrics, which are long-fiber nonwoven fabrics composed of thermoplastic filaments, not only offer excellent productivity but also, when used as a support, can suppress the fuzzing that can easily occur with short-fiber nonwoven fabrics. Furthermore, spunbond nonwoven fabrics are also preferred because they offer superior mechanical strength and dimensional stability, and can produce durable processed products when used as a support.

[0136] In the present invention, when the above-mentioned conjugated fibers are used as fibers constituting the nonwoven fabric, the conjugated fibers can be produced by a conventional conjugation method.

[0137] After the thermoplastic resin is melt-extruded from the spinneret 1, gas is passed from the cooling section 2 in a direction perpendicular to the direction of travel of the spun long fibers 8 and contacts the long fibers. Subsequently, gas is passed from the gas supply section 3 in a direction perpendicular to the direction of travel of the long fibers and contacts the long fibers. Then, the long fibers are passed from the suction and exhaust section 4 having a length of not less than 1 mm and not more than 150 mm and provided directly below the gas supply section 3, and are suction-stretched.

[0138] By implementing as described above, the spun long fibers can be cooled and a fiber web can be formed without affecting the airflow caused by suction stretching or deteriorating the unit area mass distribution in the width direction due to broken or wobbled fibers while suppressing the inflow of external air.

[0139] The gas supply unit 3 is further installed below the cooling unit to minimize yarn swing. To minimize yarn swing, the width of the gas supply unit is preferably greater than that of the cooling unit. It should be noted that the width of the cooling unit here refers to the shortest distance between the walls of the path through which the yarn travels in the cooling unit 2, while the width of the gas supply unit refers to the shortest distance between the walls of the path through which the yarn travels in the gas supply unit 3.

[0140] Furthermore, the structure is not particularly limited as long as the gas is passed through the gas supply unit and contacts the gas in a direction perpendicular to the direction of travel of the filaments. However, in order to suppress swaying of the filaments, it is preferred to incorporate a mesh into the gas supply unit for straightening. The size of the mesh is preferably 20 mesh or larger, more preferably 40 mesh or larger, and even more preferably 100 mesh or larger.

[0141] The air intake and exhaust portion 4 is preferably provided with a grid structure or a plate having holes regularly arranged in a staggered pattern or the like in order to take in the gas required for suction.

[0142] Regarding the length of the air intake and exhaust section, the length is preferably not less than 1 mm and not more than 150 mm. If the length of the air intake and exhaust section is not less than 1 mm, more preferably not less than 5 mm, and even more preferably not less than 10 mm, the inflow of the gas required for suction can be suppressed at a high wind speed in the air intake and exhaust section, and the breakage of long fibers can be reduced. In addition, if the length of the air intake and exhaust section is not more than 150 mm, more preferably not more than 100 mm, and even more preferably not more than 75 mm, the swing of long fibers caused by the inflow of external gas can be suppressed, and a fiber web with excellent unit area mass distribution in the width direction can be obtained. It should be noted that the so-called "length of the air intake and exhaust section" refers to the distance in the vertical direction of the portion of the passage facing the yarn in the air intake and exhaust section 4 ( Figure 1 distance in the up and down directions).

[0143] Suction stretching is generally performed using air using an ejector 5. In this case, it is preferable to achieve a higher degree of orientation and crystallization of the long fibers constituting the resulting fiber web to prevent wrinkles caused by fiber shrinkage during subsequent temporary bonding and thermal compression bonding, and to prevent the low-melting-point polymer component from fusing to the heated roller, which would otherwise reduce productivity. The spinning speed is preferably 3000 m / min or higher, more preferably 3500 m / min or higher, and even more preferably 4000 m / min or higher. Furthermore, by suppressing excessive fiber orientation and crystallization, thermal bonding properties can be achieved, which contributes to improved mechanical strength of the spunbond nonwoven fabric. From this perspective, the spinning speed is preferably 5500 m / min or lower, more preferably 5000 m / min or lower, and even more preferably 4500 m / min or lower.

[0144] (b) Process of forming a fiber web

[0145] The long fibers obtained by the above-mentioned step (a) are captured on a moving mesh conveyor 6 to obtain a fiber web 9. The so-called capture refers to the accumulation of the long fibers ejected from the ejector 5 on the rotating mesh conveyor 6 in sequence. The so-called mesh conveyor refers to a conveyor in which the belt portion of the belt conveyor becomes a mesh such as a perforated plate, a mesh or a porous body. In order to prevent the captured long fibers from falling from the through-part of the mesh, or the hole portion of the perforated plate or the porous body (hereinafter referred to as "hole portion, etc.") into the inside of the mesh conveyor and clogging in the hole portion, etc., it is preferred to appropriately set the size of the hole portion, etc., taking into account the resin constituting the long fibers, the fiber diameter of the long fibers, etc. It should be noted that the mesh portion can be made of metal or synthetic resin.

[0146] (c) Step of obtaining a nonwoven fabric sheet

[0147] For the fiber web 9 captured on the net conveyor 6, in order to suppress fuzzing, it only needs to be in contact with a pair of flat temporary pressing rollers 7 without any restrictions, but it is preferred to perform a heat treatment process in which the flat temporary pressing rollers 7 heated to a specified temperature are in contact with the fiber web 9. The so-called flat temporary pressing rollers are rollers whose surface does not have bumps.

[0148] Regarding the heat treatment process in the temporary pressing, the surface temperature of the flat temporary pressing roller is preferably 60°C or higher and 120°C or lower than the melting point of the lowest melting point polymer constituting the fiber web present on the fiber web surface. m ), the surface temperature of the flat temporary pressure roller is preferably (T m -60)℃ or above (T m -120)℃ or less, more preferably (T m -70)℃ or above (T m -110)℃ or less, the most preferred is (T m -80)℃ or above (T m -100)℃ or less. The surface temperature of the flat temporary pressing roller is lower than (T m If the temperature is higher than (T -120)°C, the heat pressing of the fiber web will be insufficient, resulting in poor fiber web conveying. m At -60)°C, the heat treatment becomes too strong, the constituent fibers of the surface layer are fused, and sufficient mechanical strength cannot be obtained, and the adhesiveness during thermocompression bonding in post-processing deteriorates.

[0149] The linear pressure applied by the pair of flat temporary pressure rollers 7 during temporary bonding of the fiber web 9 is preferably in the range of 100 N / cm to 700 N / cm, more preferably in the range of 200 N / cm to 600 N / cm. A linear pressure of 200 N / cm or greater provides sufficient linear pressure for forming the fiber web. A linear pressure of 600 N / cm or less prevents excessive bonding between the fibers, achieving sufficient mechanical strength.

[0150] (d) Step of obtaining a long-fiber nonwoven fabric and a nonwoven fabric roll

[0151] The temporarily bonded nonwoven fabric sheet 10 may be directly subjected to further thermocompression bonding by a pair of upper and lower flat rolls. However, in order to improve uniformity of weight per unit area in the width direction, it is preferably divided into 2 to 5 parts in the width direction and overlapped.

[0152] When laminating, it is preferred that the nonwoven fabric sheets be overlapped and thermocompression-bonded so as to satisfy the following formula (1).

[0153] 0.90≤W Min / WMax ≤1.00 ··· (1)

[0154] Here, the maximum mass per unit area W is set in the width direction of the overlapped nonwoven fabric sheets. Max (g / m 2 ) and minimum unit area mass W Min (g / m 2 ). Thus, the lowest unit area weight portions at the end portions are stacked in the same direction, and the uniformity of the unit area weight in the width direction does not deteriorate. When used as a support, a nonwoven fabric with excellent processability can be obtained.

[0155] In order to improve the uniformity of the mass per unit area, meltblown nonwoven fabrics may be placed between the layers of the nonwoven fabric sheet and overlapped.

[0156] It should be noted that, in the present invention, the W of the non-woven fabric sheet Min 、W Max Use the value calculated by the following steps.

[0157] (1) The average value of the mass distribution at 5 mm intervals is calculated by measuring 40 or more scans using an X-ray mass meter (for example, "AccureX3" manufactured by Futec Corporation).

[0158] (2) Average the mass per unit area data for the areas 0 to 20 cm from the width division position of the fiber web, round off to the second decimal place, and calculate the minimum mass per unit area W. Min and the maximum value of W Max It should be noted that W Min One side is W Max , the next highest value is used.

[0159] For thermocompression bonding, it is more preferable to use a pair of upper and lower flat rollers for thermocompression bonding and integration. Flat rollers used in thermocompression bonding can be metal rollers or elastic rollers. Examples of elastic rollers include so-called paper rollers made of paper, cotton, or aramid paper, and rollers made of resins such as urethane resins, epoxy resins, silicone resins, and hard rubber. A pair of flat rollers can be used, such as a metal roller and a metal roller, or a metal roller and an elastic roller.

[0160] Furthermore, by suppressing fusion of fibers on the surface of the long-fiber nonwoven fabric and maintaining its morphology, an anchoring effect can be achieved, which prevents separation membrane peeling when used as a support. From this perspective, it is preferable to provide a temperature difference between the pair of flat rollers. In particular, from the perspective of this anchoring effect, a method of thermocompression bonding the nonwoven fabric sheet using a heated metal roller and an unheated elastic roller is preferred.

[0161] Thermocompression bonding of the long-fiber nonwoven fabric used to form the nonwoven fabric roll is preferably performed using a pair of flat rollers, at least one of which has a surface temperature 20°C to 100°C higher than the surface temperature of the roller used for temporary bonding. Specifically, the surface temperature of the high-temperature side of the flat roller is preferably 20°C to 100°C, more preferably 30°C to 90°C, and most preferably 40°C to 80°C. By keeping the roller surface temperature below 100°C, excessive density and partial film formation are prevented, thereby preventing film peeling due to insufficient penetration of the support film when used as a support. Furthermore, by keeping the roller surface temperature above 20°C, the nonwoven fabric sheet can be fully thermocompressed, resulting in a sufficiently smooth surface and uniform application of the support film when used as a support.

[0162] The temperature of the other (low-temperature side) flat roll in the pair of flat rolls is preferably 40°C or higher and 120°C or lower than the temperature of the high-temperature flat roll. By setting the temperature difference between the low-temperature and high-temperature flat rolls to 40°C or higher, more preferably 60°C or higher, the formation of extremely high-density areas on the surface of the long-fiber nonwoven fabric can be suppressed, minimizing film peeling caused by insufficient penetration of the support film solution during support coating, and achieving excellent film forming properties. On the other hand, by setting the temperature difference between the low-temperature and high-temperature flat rolls to 120°C or lower, more preferably 100°C or lower, sufficient thermocompression bonding is achieved, minimizing overpenetration during support coating, and achieving excellent processability.

[0163] The temperature of the upper and lower rollers during thermal compression bonding is preferably within a range of ±15°C or less, more preferably ±10°C or less, and even more preferably ±5°C or less, based on the temperature at the start of processing. While it is generally difficult to strictly control the temperature of an unheated elastic roller, it can be controlled by performing a pre-run in contact with a heated metal roller before processing. If the temperature of the elastic roller becomes too high during processing, air blowing, spraying, or contact with a cooling roller can be used. If the temperature becomes too low, heating with an infrared heater, circulating a heat medium inside the roller, or contact with a heated roller can be used.

[0164] The linear pressure for hot pressing the long-fiber nonwoven fabric used to form the nonwoven fabric roll is preferably in the range of 500 N / cm to 5000 N / cm. It is preferably in the range of 500 N / cm to 5000 N / cm, more preferably 750 N / cm to 4000 N / cm, and even more preferably 1000 N / cm to 3000 N / cm. If the linear pressure is 500 N / cm or more, the fiber web is fully hot-pressed, the surface is smoothed, and thus the film-forming properties when used as a support are excellent. In addition, by setting the linear pressure to 5000 N / cm or less, the formation of extremely high-density areas on the surface of the long-fiber nonwoven fabric can be suppressed. When used as a support, the film peeling caused by insufficient penetration of the supporting film solution during casting is reduced, and good film-forming properties can be achieved.

[0165] Winding machines for hot-pressed long-fiber nonwoven fabrics can be either center-winding, where the web is wound on the surface of a winding roll by rotating the central axis of the core, or surface-winding, where a roll core is placed on one or more support rolls and at least one of the support rolls is rotated to wind the web around the roll core. Furthermore, it is preferred that the pressing pressure and winding tension be adjustable to achieve more stable winding.

[0166] Regarding the nonwoven fabric roll formed by winding the long-fiber nonwoven fabric that has been heat-pressed, it is preferred to trim the two ends when winding the nonwoven fabric roll due to the shrinkage difference between the ends and the center of the sheet. The trimming width is preferably 1 cm to 10 cm. It is preferably in the range of 1 cm to 10 cm, more preferably 2 cm to 9 cm, and even more preferably 3 cm to 8 cm. If the trimming width is 1 cm or more, it can be wound without breaking when the trimming portion is serpentine, resulting in poor trimming. In addition, if it is 10 cm or less, the loss of the nonwoven fabric roll is reduced, and the productivity is also excellent.

[0167] Furthermore, the winding tension when winding the heat-pressed long-fiber nonwoven fabric is preferably between 40 N / m and 170 N / m. It is preferably between 40 N / m and 160 N / m, more preferably between 50 N / m and 150 N / m, and even more preferably between 60 N / m and 150 N / m. A winding tension of 40 N / m or greater allows for winding without causing the long-fiber nonwoven fabric to sag and wrinkle in the roll. Furthermore, a winding tension of 170 N / m or less allows for winding without causing excessive tension and wrinkle in the roll.

[0168] Example

[0169] The nonwoven fabric roll and the method for producing the same according to the present invention will be described in detail below based on examples. However, the present invention is not limited to these examples.

[0170] [Measurement method]

[0171] The evaluation methods and measurement conditions used in the examples are described below. Unless otherwise specified, the physical properties were measured according to the above-mentioned methods.

[0172] (1) Intrinsic viscosity (IV):

[0173] The intrinsic viscosity (IV) of polyethylene terephthalate resin is measured by the following method: 8 g of a sample is dissolved in 100 ml of o-chlorophenol, and the relative viscosity η is determined using an Ostwald viscometer at 25°C according to the following formula. r .

[0174] ·η r =η / η0=(t×d) / (t0×d0)

[0175] (Here, η represents the viscosity of the polymer solution, η0 represents the viscosity of o-chlorophenol, t represents the falling time of the solution (seconds), and d represents the density of the solution (g / cm 3 ), t0 represents the falling time of o-chlorophenol (seconds), d0 represents the density of o-chlorophenol (g / cm 3 ). )

[0176] Next, according to the above relative viscosity η r , the intrinsic viscosity (IV) was calculated by the following formula.

[0177] Intrinsic viscosity (IV) = 0.0242η r +0.2634.

[0178] (2) Melting point (℃):

[0179] The melting point of the thermoplastic resin used was measured using a differential scanning calorimeter (Q100 manufactured by TA Instruments) under the above-mentioned conditions, and the average value of the endothermic peak top temperatures was calculated as the melting point of the measurement object.

[0180] (3) Maximum mass per unit area W in the width direction of the nonwoven fabric sheet Max (g / m 2 ), minimum unit area mass W Min (g / m 2 ):

[0181] Maximum mass W per unit area in the width direction of the nonwoven fabric sheet Max , minimum unit area mass W MinThe measurement was performed by the above-mentioned method using "AccureX3" manufactured by Futec Co., Ltd. as an X-ray mass per unit area meter.

[0182] (4) Smoothness of long fiber non-woven fabric (seconds):

[0183] The smoothness of the long-fiber nonwoven fabric was measured using the "Oken Smoothness Tester EBO1-5" manufactured by Asahi Seiko Co., Ltd., using the above-mentioned method. It should be noted that in Table 1, smoothness (1) is the abbreviation for the smoothness of the surface subjected to the higher temperature during thermocompression bonding, and smoothness (2) is the abbreviation for the smoothness of the surface subjected to the lower temperature during thermocompression bonding. Generally, the values ​​are such that smoothness (1) > smoothness (2).

[0184] (5) Winding hardness of non-woven fabric roll (g), hardness difference in width direction (g):

[0185] The roll hardness and the hardness difference in the width direction of the nonwoven fabric roll were measured by the above-mentioned method using "RoQ Roll Hardness Tester" manufactured by ACA System Co., Ltd. as a roll hardness meter.

[0186] [Example 1]

[0187] (Fiber Web)

[0188] As the fiber containing a thermoplastic resin as a main component, a composite fiber comprising the following high melting point polymer as a core component and the following low melting point polymer as a sheath component was used. The thermoplastic resins used are shown below.

[0189] High melting point polymer: A polymer obtained by drying a polyethylene terephthalate resin having an intrinsic viscosity (IV) of 0.65, a melting point of 260° C., and containing 0.3% by mass of titanium oxide to a moisture content of 10 ppm or less.

[0190] Low melting point polymer: A copolymerized polyethylene terephthalate resin having an intrinsic viscosity (IV) of 0.66, an isophthalic acid copolymerization ratio of 11 mol %, a melting point of 230° C., and containing 0.2 mass % of titanium oxide, dried to a moisture content of 10 ppm or less.

[0191] The core component was melted at 295°C, and the sheath component was melted at 280°C, with a core / sheath ratio of 80 / 20 by mass. This was combined into a concentric core-sheath type with a circular cross-section, and then spun from a fine orifice at a spinneret temperature of 300°C to produce long fibers. Gas was passed through a cooling section 2 perpendicular to the direction of travel of the spun long fibers 8, contacting the long fibers. Subsequently, gas was passed through a 100 mm long gas supply section 3 perpendicular to the direction of travel of the long fibers, contacting the long fibers. The gas supply section 3 was 50 mm wider than the width of the cooling section and contained a 100-mesh metal mesh. After passing through the gas supply section and contacting the long fibers, the gas passed through a 20 mm long suction and exhaust section 4 located directly below the gas supply section. Compressed air was then drawn by ejector 5 at a spinning speed of 4300 m / min, and collected on a moving mesh conveyor 6 to produce a fiber web 9. The fiber web collected as described above was passed through a pair of upper and lower metal flat temporary pressing rollers 7, and the surface temperature of each roller of the temporary pressing roller was set at 135°C and the linear pressure was set at 490N / cm to perform temporary bonding. The average single fiber diameter was 11.4μm and the unit area weight was 34.5g / m 2 A temporarily bonded nonwoven fabric sheet 10 with a width of 2.3 m.

[0192] (Non-woven fabric roll)

[0193] The nonwoven fabric sheet was divided into two 1.15 m sections, and the two layers were overlapped and heat-pressed. The overlap was performed by checking the unit area mass of the area 0 to 20 cm from the position where the nonwoven fabric sheet was divided into two sections, and the weight of the area was calculated by taking the W of one end as the weight. min 34.2g / m 2 W with the end divided into two parts MAX 35.8g / m 2 Implemented in an overlapping manner.

[0194] The stacked sheets were thermocompression bonded by passing them through a set of three flat rolls. The upper flat roll was a resin elastic roll with a hardness (Shore D) of 91 and an average surface roughness (Ra) of 4μm, maintained at a surface temperature of 130°C; the middle flat roll was a metal roll with a surface temperature of 195°C; and the lower flat roll was a resin elastic roll with a hardness (Shore D) of 75 and an average surface roughness (Ra) of 4μm, maintained at a surface temperature of 130°C. The sheets were thermocompressed by passing them between the middle and lower sections of the flat rolls, and then between the top and middle sections at a linear pressure of 1850N / cm.

[0195] Then, the surface of the hot-pressed sheet that contacts the metal roller of the middle flat roller is brought into contact with a metal cooling roller with a roller surface temperature of 45°C for 1 second, and then 2.5 cm at both ends are trimmed. At the same time, 5000 m is wound on a fiber-reinforced plastic core with an inner diameter of 17.5 cm and a wall thickness of 10 mm using a biaxial surface winder with a sheet winding tension of 120 N / m to obtain a non-woven fabric roll with a width of 1.1 m.

[0196] The obtained nonwoven fabric had a mass per unit area of ​​70 g / m 2 , the apparent density is 0.82g / cm 3 The smoothness was 45 seconds on the metal roller bonding surface and 14 seconds on the elastic roller bonding surface during thermal compression bonding.

[0197] The wound nonwoven fabric roll had no wrinkles, a winding offset of 0 mm, a winding hardness of 40.5 g, a hardness difference of 8.2 g, a thickness of the outer nonwoven fabric of the roll of 0.086 mm, and a thickness of the inner nonwoven fabric of the roll of 0.086 mm.

[0198] [Example 2]

[0199] In Example 1, the same method was used except that the winding length of the nonwoven fabric roll was 12000 m.

[0200] The wound nonwoven fabric roll had no wrinkles, a winding offset of 0 mm, a winding hardness of 42.3 g, a hardness difference of 8.4 g, a thickness of the outer nonwoven fabric of the roll of 0.086 mm, and a thickness of the inner nonwoven fabric of the roll of 0.086 mm.

[0201] [Example 3]

[0202] In Example 2, the same method was used to obtain the fiber web except that the length of the gas supply portion was set to 20 mm and the length of the air intake and exhaust portion was set to 100 mm. min 33.4g / m 2 , W MAX 36.6g / m 2 The unit area mass of the obtained nonwoven fabric is 70 g / m 2 , the apparent density is 0.81g / cm 3 The smoothness was 43 seconds on the metal roller bonding surface and 12 seconds on the elastic roller bonding surface during thermal compression bonding.

[0203] The wound nonwoven fabric roll had no wrinkles, a winding offset of 0 mm, a winding hardness of 43.1 g, a hardness difference of 19.6 g, a thickness of the outer nonwoven fabric of the roll of 0.085 mm, and a thickness of the inner nonwoven fabric of the roll of 0.087 mm.

[0204] [Example 4]

[0205] In Example 2, the same method was used except that the length of the air intake and exhaust portion was set to 5 mm when obtaining the fiber web. min 34.4g / m 2 , W MAX 35.6g / m 2 The unit area mass of the obtained nonwoven fabric is 70 g / m 2 , the apparent density is 0.82g / cm 3 The smoothness was 44 seconds on the metal roller bonding surface and 13 seconds on the elastic roller bonding surface during thermal compression bonding.

[0206] The wound nonwoven fabric roll had no wrinkles, a winding offset of 0 mm, a winding hardness of 42.1 g, a hardness difference of 17.2 g, a thickness of the outer layer of the roll nonwoven fabric of 0.085 mm, and a thickness of the inner layer of the roll nonwoven fabric of 0.086 mm.

[0207] [Example 5]

[0208] In Example 2, the same method was used except that the fiber web was divided into three parts in the width direction, overlapped and heat-pressed, and the 3.0 cm edges of both ends were trimmed to produce a nonwoven fabric roll with a width of 0.7 m. The resulting nonwoven fabric had a unit area mass of 70 g / m 2 , the apparent density is 0.78g / cm 3 The smoothness was 42 seconds on the metal roller bonding surface and 12 seconds on the elastic roller bonding surface during thermal compression bonding.

[0209] The wound nonwoven fabric roll had no wrinkles, a winding offset of 0 mm, a winding hardness of 41.7 g, a hardness difference of 7.5 g, a thickness of the outer nonwoven fabric of the roll of 0.088 mm, and a thickness of the inner nonwoven fabric of the roll of 0.089 mm.

[0210] [Example 6]

[0211] In Example 2, the same method was used except that the fiber web was divided into four parts in the width direction, overlapped and heat-pressed, and the two ends were trimmed 3.2 cm to produce a nonwoven fabric roll with a width of 0.5 m. The resulting nonwoven fabric had a unit area mass of 70 g / m 2 , the apparent density is 0.77g / cm 3 The smoothness was 41 seconds on the metal roller bonding surface and 11 seconds on the elastic roller bonding surface during thermal compression bonding.

[0212] The wound nonwoven fabric roll had no wrinkles, a winding offset of 0 mm, a winding hardness of 41.5 g, a hardness difference of 7.1 g, a thickness of the outer nonwoven fabric of the roll of 0.089 mm, and a thickness of the inner nonwoven fabric of the roll of 0.089 mm.

[0213] [Comparative Example 1]

[0214] In Example 2, the same method was used to obtain the fiber web, except that the gas supply section was set to 0 mm and the air intake and exhaust section was set to 150 mm. When the fiber web was obtained, it was confirmed that the long fibers at both ends had larger swaying fibers. The resulting nonwoven fabric had a mass per unit area of ​​70 g / m 2 , the apparent density is 0.81g / cm 3 The smoothness was 45 seconds on the metal roller bonding surface and 14 seconds on the elastic roller bonding surface during thermal compression bonding.

[0215] The wound nonwoven fabric roll had no wrinkles and the winding offset was 0 mm, but the surface of the nonwoven fabric roll was observed to be uneven. The winding hardness was 41.6 g, the hardness difference was 24.6 g, the thickness of the outer layer of the roll was 0.086 mm, and the thickness of the inner layer of the roll was 0.086 mm.

[0216] [Comparative Example 2]

[0217] In Example 2, the same method was used except that the suction and exhaust section was set to 150 mm when the fiber web was obtained. When the fiber web was obtained, it was confirmed that the long fibers had increased in size over the entire width. The mass per unit area of ​​the obtained nonwoven fabric was 70 g / m 2 , the apparent density is 0.82g / cm 3 The smoothness was 44 seconds on the metal roller bonding surface and 14 seconds on the elastic roller bonding surface during thermal compression bonding.

[0218] The wound nonwoven fabric roll had no wrinkles and the winding offset was 0 mm, but the surface of the nonwoven fabric roll was observed to be uneven. The winding hardness was 41.8 g, the hardness difference was 23.2 g, the thickness of the outer layer of the roll was 0.086 mm, and the thickness of the inner layer of the roll was 0.087 mm.

[0219] [Comparative Example 3]

[0220] In Example 2, the same method was used to obtain the fiber web, except that the suction and exhaust section was set to 0 mm. However, the long fibers across the entire width of the fiber web were significantly swung, resulting in frequent fiber breakage. During temporary bonding, the fiber web became entangled with the flat temporary pressure rollers, making it impossible to collect the fiber web.

[0221] [Comparative Example 4]

[0222] In Example 2, when obtaining the fiber web, the moving speed of the net conveyor was adjusted so that the mass per unit area became 69 g / m 2The obtained nonwoven fabric was divided into two 1.15 m nonwoven fabric sheets, and only one side was used to perform heat pressing in the same manner as in Example 2. The unit area mass of the obtained nonwoven fabric was 70 g / m 2 , the apparent density is 0.82g / cm 3 The smoothness was 45 seconds on the metal roller bonding surface and 14 seconds on the elastic roller bonding surface during thermal compression bonding.

[0223] The winding deviation of the wound nonwoven fabric roll was 0 mm, but some winding wrinkles were generated. The winding hardness was 43.2 g, the hardness difference was 25.3 g, the thickness of the outer layer nonwoven fabric of the roll was 0.087 mm, and the thickness of the inner layer nonwoven fabric of the roll was 0.088 mm.

[0224] [Table 1]

[0225]

[0226] Summary

[0227] The nonwoven fabric rolls of Examples 1 to 6 and Comparative Examples 1, 2, and 4 were formed into separation membranes by the following die coating method.

[0228] (Separation membrane formation)

[0229] The obtained nonwoven fabric roll was unwound at a speed of 12 m / min, and a 16% by mass dimethylformamide solution (casting liquid) of polysulfone ("Udel" (registered trademark) -P3500 manufactured by Solvay Advanced Polymers) with a thickness of 35 μm was coated thereon by die coating at room temperature (20°C) with the smoother side as the coating side. The roll was immediately immersed in pure water at room temperature (20°C) for 10 seconds, then immersed in pure water at a temperature of 75°C for 120 seconds, and then immersed in pure water at a temperature of 90°C for 120 seconds. The roll was wound at a tension of 120 N / m to form a polysulfone membrane to produce a separation membrane.

[0230] As a result, when the nonwoven fabric rolls of Examples 1 to 6 were used, wrinkles and coating defects did not occur during coating, resulting in good processability. On the other hand, in Comparative Examples 1 and 2, wrinkles occurred after coating the separation membrane, and in Comparative Example 4, wrinkles began to form during unwinding, and coating defects also occurred during processing, resulting in poor processability.

[0231] From these results, it can be seen that, as shown in Table 1, a nonwoven fabric roll formed by winding a long-fiber nonwoven fabric containing fibers mainly composed of a thermoplastic resin into a roll, wherein the apparent density of the long-fiber nonwoven fabric is 0.70 g / cm 3 Above 0.90g / cm 3The following, the winding hardness of the non-woven fabric roll is greater than 35.0g and less than 50.0g, and the hardness difference in the roll width direction is greater than 7.0g and less than 20.0g, so that a non-woven fabric roll can be obtained that has sufficient mechanical strength and dimensional stability when used as a separation membrane support body and has excellent supporting membrane coating processability in a wide-width die coating method.

[0232] Industrial applicability

[0233] The nonwoven fabric roll of the present invention has sufficient mechanical strength and dimensional stability and is excellent in membrane coating processability in a wide-width die coating method. Therefore, it is particularly suitable for a wide range of fields including separation membrane supports (typically water treatment).

[0234] Description of Reference Numerals

[0235] 1: Spinneret

[0236] 2: Cooling section

[0237] 3: Gas supply unit

[0238] 4: Intake and exhaust part

[0239] 5: Injector

[0240] 6: Net conveyor

[0241] 7: Temporary crimping roller

[0242] 8: Spun long fibers

[0243] 9: Fiber mesh

[0244] 10: Non-woven sheet

[0245] 11: Arrow showing the direction of travel of long fibers

Claims

1. A nonwoven fabric roll, wherein a long-fiber nonwoven fabric containing fibers having a thermoplastic resin as a main component is wound into a roll, wherein: The apparent density of the long fiber nonwoven fabric is 0.70 g / cm 3 Above 0.90g / cm 3 Hereinafter, the nonwoven fabric roll has a winding hardness of 35.0 g to 50.0 g, and a hardness difference in a roll width direction of 7.0 g to 20.0 g.

2. The nonwoven fabric roll according to claim 1, wherein: The nonwoven fabric roll has a winding length of 100 m to 20500 m, and a difference between the thickness of the long-fiber nonwoven fabric in the outer layer of the roll and the thickness of the long-fiber nonwoven fabric in the inner layer of the roll is 0.010 mm or less.

3. The nonwoven fabric roll according to claim 1 or 2, wherein: The nonwoven fabric roll has a roll width of 0.5 m to 1.5 m.

4. The nonwoven fabric roll according to claim 1 or 2, wherein: The long-fiber nonwoven fabric has a smoothness of 10 seconds to 60 seconds on both sides.

5. The nonwoven fabric roll according to claim 1 or 2, wherein: The thermoplastic resin is a polyester resin.

6. The method for producing a nonwoven fabric roll according to any one of claims 1 to 5, wherein: The following steps a to d are carried out in sequence. Step a: After spinning a thermoplastic resin from a spinneret (1) having a discharge hole to obtain a long fiber, The gas is passed through the cooling section (2) in a direction perpendicular to the running direction of the long fibers so as to contact the long fibers. Next, a gas is passed from a gas supply unit (3) in a direction perpendicular to the running direction of the long fibers so as to contact the long fibers, and then, The long fibers are passed through an air intake and exhaust section (4) having a length of 1 mm to 100 mm and arranged directly below the gas supply section (3), and are subjected to suction stretching at a spinning speed of 3000 m / min to 5500 m / min; Step b: collecting the stretched long fibers onto a moving net conveyor (6) to form a fiber web (9); Step c: temporarily bonding the fiber web (9) with a linear pressure of 100 N / cm to 700 N / cm using a pair of flat temporary pressure-bonding rollers (7) whose roller surface temperature is 60° C. to 120° C. lower than the melting point of the thermoplastic resin to obtain a nonwoven fabric sheet (10); Step d: Overlap the nonwoven fabric sheets in two or more layers, and perform heat pressing using a pair of flat rollers at least one of which has a roller surface temperature that is 20°C to 100°C higher than the roller surface temperature in step c, at a linear pressure of 500N / cm to 5000N / cm to obtain a long-fiber nonwoven fabric, and then wind the long-fiber nonwoven fabric to obtain a nonwoven fabric roll.

7. The method for producing a nonwoven fabric roll according to claim 6, wherein: The step a is the following step a', the melting point of the thermoplastic resin in the step c is the melting point of the low melting point polymer, Step a': spinning a high melting point polymer and a low melting point polymer having a melting point that is 10°C or more and 110°C or less lower than the melting point of the high melting point polymer from a composite spinneret (1) having a discharge hole, A long fiber is obtained in which the low melting point polymer covers the high melting point polymer in such a manner that the high melting point polymer is not exposed, and then, Passing gas from the cooling section (2) in a direction perpendicular to the traveling direction of the long fibers so as to contact the long fibers, Next, a gas is passed from a gas supply unit (3) in a direction perpendicular to the running direction of the long fibers so as to contact the long fibers, and then, The long fibers are passed through an air intake and exhaust section (4) having a length of 1 mm to 100 mm and disposed directly below the gas supply section (3). Suction stretching is performed at a spinning speed of 3000 m / min to 5500 m / min.

8. The method for producing a nonwoven fabric roll according to claim 6 or 7, wherein: The thermoplastic resin in the step a is a polyester resin, or the high melting point polymer and / or the low melting point polymer in the step a' is a polyester resin.

9. The method for producing a nonwoven fabric roll according to claim 6 or 7, wherein: In the step d, the nonwoven fabric sheets obtained in the step c are overlapped and thermocompression-bonded in a manner satisfying the following formula 1 to obtain a long-fiber nonwoven fabric, and then the long-fiber nonwoven fabric is wound to obtain a nonwoven fabric roll. 0.90≤W Min / IN Max ≤1.00 ··· (1) Here, the maximum mass per unit area W is set in the width direction of the overlapped nonwoven fabric sheets. Max (g / m 2 ) and minimum unit area mass W Min (g / m 2 ).

Images