Spunbond nonwoven fabric and separation membrane containing the same

Abstract

The present invention addresses the problem of providing a spunbonded nonwoven fabric in which bleed-through and membrane separation do not occur during membrane-formation processing and that has dimensional stability and mechanical strength, when said fabric is employed in a support body of a separation membrane, such as a reverse osmosis membrane.　The present invention provides a solution by means of a spunbonded nonwoven fabric containing core-sheath composite fibers that contain a polyester, serving as a core component, and a sheath component consisting of a copolymerized polyester, wherein: the melting point of the sheath component is [(the melting point of the core component)-45]°C to [(the melting point of the core component)-15]°C; a copolymer component of the sheath component is polyethylene glycol having a copolymerized amount of 2 to 15 mass% or / and a metal sulfonate group-containing isophthalic acid component having a copolymerized amount of 2.5 to 7.5 mol% with respect to the amount of all acid components; and the contact angle between a surface of the spunbonded nonwoven fabric and water is 0° to 80°.

Description

[Technical Field]

[0001] The present invention provides a spunbond nonwoven fabric that achieves both suppression of membrane peeling and mechanical strength when manufacturing filtration membranes used in water treatment, and is suitable as a support for filtration membranes. [Background technology]

[0002] Nonwoven fabrics are sheet-like materials made by intertwining fibers without weaving. They are broadly classified into spunbond nonwovens, dry-laid staple fiber nonwovens, and papermaking nonwovens, depending on the raw materials, web formation method, and sheet manufacturing method. Among nonwovens, spunbond nonwovens use long fibers as raw materials and can be obtained through integrated processing from spinning to winding of the nonwoven fabric. As a result, they offer excellent productivity and processability, and are used in a wide range of fields, including sanitary materials, civil engineering and construction materials, and industrial materials. In particular, they are well-suited for water treatment applications as a consumer material.

[0003] A common water treatment method involves removing impurities from water using filtration membranes with pores. For example, microfiltration membranes and ultrafiltration membranes are used in water treatment plants, while reverse osmosis membranes are used for seawater desalination.

[0004] Filtration membranes used in water treatment are sometimes operated under high pressure, so nonwoven fabric is used as a membrane support to reinforce their strength.

[0005] The method for forming filtration membranes (separation membranes) used in water treatment involves casting a polymer solution containing separation membrane-forming components onto a support. Therefore, the nonwoven fabric used as the support must be free from defects such as excessive penetration of the membrane-forming solution, peeling of membrane components, fuzzing, and pinholes. To achieve this, excellent uniformity of basis weight, membrane adhesion, and surface smoothness are key challenges.

[0006] Furthermore, in the case of supports for reverse osmosis membranes, which are often used under high pressure, high mechanical strength, dimensional stability, and membrane peel strength are required to withstand high pressure. Here, membrane peel strength refers to the degree to which the separation membrane support, which has membrane adhesion, is given mechanical strength so that the separation membrane does not easily peel off. Membrane adhesion refers to the degree of penetration of the separation membrane forming components into the separation membrane support.

[0007] Furthermore, to improve filtration performance, the separation membrane is used as a separation element unit with a multi-layered structure rather than a single layer. Since the improvement in filtration performance is proportional to the number of layers of separation membrane in the separation element unit, thinning the separation membrane support is also a challenge.

[0008] Conventionally, when coating a separation membrane component, a papermaking nonwoven fabric with excellent rigidity has been proposed to suppress the bending of the support (see Patent Document 1). Also, as a separation membrane support with minimal warping during film formation and excellent dimensional stability, a spunbond nonwoven fabric has been proposed, consisting of a composite fiber in which a low-melting-point polymer is arranged around a high-melting-point polymer, and the low-melting-point polymers are bonded to each other by heat compression during manufacturing (see Patent Document 2). On the other hand, as an environmentally friendly separation membrane support, a spunbond nonwoven fabric made of a composite fiber using raw materials derived from biomass resources has been proposed (see Patent Document 3). Furthermore, as a separation membrane support with less fluffing, excellent dimensional stability and durability, a tricot knit fabric made of a core-sheath type composite fiber in which a low-melting-point polymer is arranged around a high-melting-point polymer has been proposed (see Patent Document 4). In addition, a spunbond nonwoven fabric with high breathability and rigidity / softness, and excellent flexibility and tactile feel has been proposed (see Patent Document 5). In addition, papermaking nonwoven fabrics with excellent form and strength capable of withstanding high-pressure conditions have been proposed for use as separation membranes for seawater desalination and as support structures for separation membranes for concentration and other applications (see Patent Document 6). Furthermore, thermoplastic nonwoven fabrics with excellent water absorption and retention properties have been proposed for use as materials for sanitary materials and general lifestyle-related materials (see Patent Document 7). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2012-67409 [Patent Document 2] Japanese Patent Application Publication No. 2016-29221 [Patent Document 3] Japanese Patent Application Publication No. 2018-138704 [Patent Document 4] International Publication No. 2018 / 147251 [Patent Document 5] International Publication No. 2019 / 146660 [Patent Document 6] Japanese Patent Publication No. 2010-194478 [Patent Document 7] Japanese Patent Publication No. 2006-299424 [Overview of the project] [Problems that the invention aims to solve]

[0010] The technologies described in Patent Documents 1 and 6 use short fibers cut to a length of 5 mm as binder fibers that are heat-bonded to the main fibers in the composition of the papermaking nonwoven fabric. As a result, the generation of fluff increases, mechanical strength decreases, and the uniformity of basis weight and surface smoothness are poor.

[0011] Furthermore, the technologies described in Patent Documents 2 and 3 are spunbond nonwoven fabrics using core-sheath composite fibers with polyethylene terephthalate as the sheath, which has no copolymer components other than melting point control. These have problems such as low affinity with the separation membrane, insufficient permeability of the separation membrane, reduced adhesion, and increased likelihood of the separation membrane peeling off.

[0012] The technology described in Patent Document 4 is a tricot knitted fabric using a core-sheath type composite fiber in which the sheath is made of polyester with a low melting point 20 to 35°C lower than the melting point of the core, making it difficult to create a separation membrane support of a certain thickness or less. Furthermore, when a separation membrane is formed on the tricot knitted fabric, the penetration of the separation membrane into the support becomes insufficient, reducing adhesion and making the separation membrane prone to peeling.

[0013] The technology described in Patent Document 5 is a spunbond nonwoven fabric composed of single-component fibers made of a polyester resin copolymerized with polyethylene glycol, and has the problem of having inferior mechanical strength as a separation membrane support required for use under high pressure.

[0014] The technology described in Patent Document 7 is a nonwoven fabric composed of absorbent fibers containing a thermoplastic water-absorbent resin copolymerized with polyethylene glycol. However, it has problems such as poor basis weight uniformity, and when used as a separation membrane support, it suffers from excessive penetration of the film-forming solution, resulting in see-through and poor mechanical strength.

[0015] Therefore, the present invention aims to provide a separation membrane support, such as a reverse osmosis membrane, that uses a spunbond nonwoven fabric with adjustable mechanical strength and sheet thickness, has excellent adhesion to the separation membrane, and prevents the separation membrane from peeling off during film formation. [Means for solving the problem]

[0016] The present invention aims to solve the above-mentioned problems, and according to the present invention, the following invention is provided.

[0017] [1] A spunbond nonwoven fabric containing a core-sheath type composite fiber in which the core component is polyester and the sheath component is copolymerized polyester, The melting point of the sheath component is between [(melting point of core component)-45]°C and [(melting point of core component)-15]°C. The copolymer component of the aforementioned sheath component is polyethylene glycol copolymerization amount of 2% to 15% by mass, or / and An isophthalic acid component containing a metal sulfonate group, wherein the copolymerization amount is 2.5 mol% or more and 7.5 mol% or less relative to the total acid component, The contact angle between the surface of the spunbond nonwoven fabric and water is 5 It is between ° and 80°. Spunbond nonwoven fabric.

[0018] [2] The spunbond nonwoven fabric according to [1], wherein the sheath component is a copolymerized polyester obtained by copolymerizing polyethylene glycol in an amount of 2% by mass or more and 15% by mass or less, and the contact angle with water on the surface of the spunbond nonwoven fabric is 5° or more and 80° or less.

[0019] [3] The spunbond nonwoven fabric according to [1] or [2], wherein the molecular weight of the polyethylene glycol in the sheath component is 1,000 or more and 35,000 or less.

[0020] [4] The spunbond nonwoven fabric according to [1] to [3], wherein the arithmetic mean roughness of the surface of the spunbond nonwoven fabric is 0.1 μm or more and 10 μm or less.

[0021] [5] The spunbond nonwoven fabric according to [1] to [4], wherein the composite mass ratio of the core component and the sheath component of the core-sheath type composite fiber is 95:5 to 50:50.

[0022] [6] The sheath component is a copolymerized polyester obtained by copolymerizing a metal sulfonate group-containing isophthalic acid component in an amount of 2.5 mol% to 7.5 mol% relative to the total acid component, and the contact angle with water on the surface of the spunbond nonwoven fabric is 5 A spunbond nonwoven fabric as described in [1] above, having a degree greater than or equal to 70° and less than 70°.

[0023] [7] The density of the spunbond nonwoven fabric is 0.5 g / cm³ 3 ~1.8g / cm 3 The spunbond nonwoven fabric described in [1] or [6] above.

[0024] [8] The spunbond nonwoven fabric according to [6] or [7], wherein the composite mass ratio of the core component to the sheath component of the core-sheath composite fiber is 90:10 to 60:40.

[0025] [9] A separation membrane comprising a spunbond nonwoven fabric as described in any of [1] to [8] above and a polymer component as constituent elements, A separation membrane in which the polymer component is at least one selected from the group consisting of polysulfone, polyethersulfone, polyarylethersulfone, polyimide, polyvinylidene fluoride, and cellulose acetate, and the penetration rate of the polymer component into the spunbond nonwoven fabric is 5% or more and 70% or less. [Effects of the Invention]

[0026] According to the present invention, by using a spunbond nonwoven fabric with a reduced contact angle with water, the permeability of the separation membrane forming component is improved, high membrane peel strength is obtained, and a separation membrane support is obtained that prevents membrane peeling during the formation of the separation membrane. [Modes for carrying out the invention]

[0027] [Core-sheath type composite fiber] The core component of the core-sheath type composite fiber contained in the spunbond nonwoven fabric of the present invention is polyester, and examples include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, and polybutylene succinate, as well as copolymers thereof. Polyethylene terephthalate and polybutylene terephthalate are preferably used due to their excellent strength.

[0028] The sheath component of the core-sheath type composite fiber in the present invention is a copolymerized polyester obtained by copolymerizing polyethylene glycol at a concentration of 2% to 15% by mass, or / or by copolymerizing a metal sulfonate group-containing isophthalic acid component at a concentration of 2.5 mol% to 7.5 mol% relative to the total acid component. This copolymer is obtained by copolymerizing polyethylene glycol, metal sulfonate group-containing isophthalic acid, and / or its ester-forming derivative during a polycondensation reaction between dicarboxylic acid and / or its ester-forming derivative and alkylene glycol.

[0029] The dicarboxylic acid and / or its ester-forming derivative is preferably an aromatic carboxylic acid such as terephthalic acid, isophthalic acid, and phthalic acid, an aliphatic dicarboxylic acid such as adipic acid and sebacic acid, and an alicyclic dicarboxylic acid such as cyclohexanecarboxylic acid. The alkylene glycol is preferably selected from 1,4-butanediol, 1,3-propanediol, ethylene glycol, or a combination thereof.

[0030] In the present invention, the copolymerization amount of polyethylene glycol, which is the copolymerization component of the sheath component of the core-sheath type composite fiber, is 2% by mass or more and 15% by mass or less relative to the copolymerized polyester. By setting the copolymerization amount to preferably 4% by mass or more, and more preferably 8% by mass or more, the permeability of the separation membrane forming component can be improved. On the other hand, by setting the copolymerization amount to preferably 14% by mass or less, yarn breakage due to thickness during spinning can be suppressed, and consequently the strength of the spunbond nonwoven fabric can be increased.

[0031] By setting the copolymerization amount of polyethylene glycol within the above range, hydrophilicity is improved and the contact angle of the spunbond nonwoven fabric with water is reduced. This improves the permeability with the separation membrane forming components. As the hydrophilicity of the nonwoven fabric surface improves, the polymer components constituting the separation membrane penetrate rapidly into the nonwoven fabric, resulting in stronger adhesion between the nonwoven fabric and the separation membrane.

[0032] Furthermore, the amount of polyethylene glycol copolymerized in spunbond nonwoven fabric, and the amount of polyethylene glycol copolymerized in the sheath component of the core-sheath composite fibers contained in spunbond nonwoven fabric, can be measured and calculated using nuclear magnetic resonance (NMR) spectroscopy. Specifically, the following applies: (1) Take 50 mg of the sample from the spunbond nonwoven fabric and dissolve it in 1 mL of deuterated hexafluoroisopropanol (HFIP). (2) As the measuring device, for example, use the "AL-400" manufactured by JEOL Ltd., and the measurement conditions are as follows: 1 NMR measurements were performed using H-NMR with 128 cumulative measurements. (3) The amount of polyethylene glycol copolymerization (mass%) in the spunbond nonwoven fabric is calculated from the integral value of the CH2 peak in polyethylene glycol obtained by NMR measurement and the integral value of (H) of the benzene ring in the polyethylene terephthalate structure. (4) A sample is taken again from the spunbond nonwoven fabric, treated with alkali to dissolve the sheath component, and the yarn is made up of only the core component. (5) Dissolve 50 mg of the sample obtained in (4) in 1 mL of deuterated hexafluoroisopropanol (HFIP). (6) NMR measurements are performed in the same manner as in (2) and (3), and the amount of polyethylene glycol copolymer (mass%) in the core component is calculated from the integral value of the CH2 peak in polyethylene glycol and the integral value of (H) of the benzene ring in the polyethylene terephthalate structure. (7) The amount of polyethylene glycol copolymer in the spunbond nonwoven fabric is calculated by subtracting the amount of polyethylene glycol copolymer in the core component (mass%) from the amount of polyethylene glycol copolymer in the spunbond nonwoven fabric (mass%), and then dividing by the sheath ratio. The sheath ratio is calculated by observing the cross-section of the spunbond nonwoven fabric yarn.

[0033] In the present invention, the molecular weight of polyethylene glycol, which is the copolymer component of the sheath component of the core-sheath type composite fiber, is preferably 1,000 to 35,000 as a number average molecular weight. The number average molecular weight of polyethylene glycol is 1,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, and particularly preferably 7,000 or more. This improves the hydrophilicity of the nonwoven fabric, improves permeability with the separation membrane forming component, and improves the adhesion between the nonwoven fabric and the separation membrane. On the other hand, by setting the number average molecular weight to 35,000 or less, more preferably 20,000 or less, it is possible to suppress the decrease in reactivity during copolymerization, and when the nonwoven fabric is used as a separation membrane support, it is possible to suppress the elution of internal substances of the support into water. Furthermore, it is possible to suppress yarn breakage due to thickness during spinning, and consequently, the strength of the spunbond nonwoven fabric can be increased.

[0034] Furthermore, the number-average molecular weight of polyethylene glycol in the sheath component of core-sheath composite fibers contained in spunbond nonwoven fabric can be measured and calculated using gel permeation chromatography (GPC). Specifically, a measuring instrument such as Waters' "Differential Refractive Index Detector 2410" is used, and the measurement conditions are as follows: 50 mg of the sample is placed in a sealable vial, 1 mL of 28% by mass aqueous ammonia is added, and the sample is dissolved by heating at 120°C for 5 hours. After cooling, 1.5 mL of 6 mol / L hydrochloric acid is added, and the volume is adjusted to 5 mL with purified water. After centrifugation, the solution is filtered through a 0.45 μm filter, and the filtrate can be analyzed by GPC. The number-average molecular weight of polyethylene glycol can be calculated using a molecular weight calibration curve created using standard data of known molecular weights.

[0035] Examples of metal sulfonate group-containing isophthalic acid components for the sheath component of the core-sheath type composite fiber in the present invention include sodium 4-sulfoisophthalate, potassium 4-sulfoisophthalate, sodium 5-sulfoisophthalate, potassium 5-sulfoisophthalate, and barium 5-sulfoisophthalate. Among these, sodium 5-sulfoisophthalate and potassium 5-sulfoisophthalate are preferred due to their excellent polycondensation properties, and sodium 5-sulfoisophthalate is particularly preferred. These metal sulfonate group-containing isophthalic acid components may be of a single chemical structure or a combination of two or more types.

[0036] Examples of ester-forming derivatives of the metal sulfonate group-containing isophthalic acid include alkyl esters such as methyl esters and ethyl esters, acid halides such as acid chlorides and acid bromides, and isophthalic anhydrides. For example, alkyl esters such as methyl esters and ethyl esters are preferred due to their excellent polycondensation reactivity, and methyl esters are particularly preferred.

[0037] Furthermore, the copolymerization amount of the metal sulfonate group-containing isophthalic acid component in the sheath component of the core-sheath type composite fiber in the present invention is 2.5 mol% or more and 7.5 mol% or less relative to the total acid component. By setting the copolymerization amount to 2.5 mol% or more, preferably 3.0 mol% or more, relative to the total acid component, the permeability with the separation membrane-forming component can be improved. On the other hand, by setting the copolymerization amount to 7.5 mol% or less, preferably 7.0 mol% or less, relative to the total acid component, yarn breakage due to the increase in the extensional viscosity of the sheath component during spinning can be suppressed, and consequently, the strength of the spunbond nonwoven fabric can be increased.

[0038] By setting the metal sulfonate group-containing isophthalic acid component within the above range, hydrophilicity is improved, and the contact angle of the spunbond nonwoven fabric with water is reduced. As a result, the polymer solution constituting the separation membrane penetrates rapidly into the nonwoven fabric, strengthening the adhesion between the nonwoven fabric and the separation membrane, and making it possible to obtain a spunbond nonwoven fabric that is excellent as a separation membrane support.

[0039] Furthermore, the amount of isophthalic acid component containing metal sulfonate groups in spunbond nonwoven fabrics, and the amount of isophthalic acid component containing metal sulfonate groups in the sheath component of the core-sheath composite fibers constituting the spunbond nonwoven fabrics, can be measured and calculated using nuclear magnetic resonance (NMR) spectroscopy. Specifically, the following applies: (1) Take 50 mg of the sample from the spunbon nonwoven fabric and dissolve it in 1 mL of deuterated hexafluoroisopropanol (HFIP). (2) As the measuring device, for example, JEOL Ltd.'s "AL-400" is used, and the measurement conditions are as follows: 13 NMR measurements were performed using 13C-NMR with 128 cumulative measurements. (3) The amount of isophthalic acid component containing metal sulfonate groups in the spunbond nonwoven fabric is calculated by comparing the integrated value of the carbon (C) peak bonded to the sulfonate group obtained by NMR measurement with the integrated value of carbon (C) in the polyethylene terephthalate structure. (4) A sample is taken again from the spunbond nonwoven fabric, treated with alkali to dissolve the sheath component, and the yarn is made up of only the core component. (5) Dissolve 50 mg of the sample obtained in (4) in 1 mL of deuterated hexafluoroisopropanol (HFIP). (6) NMR measurements are performed in the same manner as in (2) and (3), and the amount of isophthalic acid component containing metal sulfonate groups in the spunbond nonwoven fabric is calculated from the integral value of the carbon (C) peak bonded to the sulfonate group and the integral value of carbon (C) in the polyethylene terephthalate structure. (7) The amount of metal sulfonate group-containing isophthalic acid component in the core component is calculated by subtracting the amount of metal sulfonate group-containing isophthalic acid component in the spunbond nonwoven fabric from the amount of metal sulfonate group-containing isophthalic acid component in the core component, and then dividing by the sheath ratio. The sheath ratio is calculated by observing the cross-section of the yarn of the spunbond nonwoven fabric.

[0040] The fibers constituting the spunbond nonwoven fabric of the present invention may be so-called blended fibers, which are a mixture of multiple types of fibers.

[0041] The core and sheath components of the core-sheath composite fibers contained in the spunbond nonwoven fabric of the present invention may contain titanium dioxide (TiO2) particles for the purpose of reducing friction with contact objects such as various guides and rollers in the nonwoven fabric manufacturing process, thereby improving process passability and adjusting the color tone of the product, and for the purpose of improving adhesion with excellent thermal conductivity in the process of heat-pressing the spunbond nonwoven fabric. The titanium dioxide particles are manufactured by various wet and dry methods, and, if necessary, are pre-treated by crushing, classification, etc., before being added to the copolymer polyester reaction system. The particles may be added to the copolymer polyester reaction system at any stage, but it is preferable to add them after the esterification or transesterification reaction has been substantially completed, as this results in good dispersibility in the polymer. The amount of particles added to the polymer and the particle size can be changed depending on the application, but a range of 0.01% to 10% by mass relative to the copolymerized polyester, an average particle size of 0.05 μm to 5 μm, and 1000 or fewer coarse particles with a particle size of 4 μm or more per 0.4 mg is preferable as it results in particularly good process passability, color tone, and thermal conductivity.

[0042] The composite forms of core-sheath type composite fibers include concentric core-sheath type and eccentric core-sheath type composite forms, as these allow for efficient heat bonding between fibers as a nonwoven fabric. Furthermore, the cross-sectional shapes of the fibers can include circular, flattened, polygonal, multi-lobed, and hollow cross-sections.

[0043] In a concentric core-sheath type composite structure, the cross-sectional shape of the fibers is preferably circular or flattened, allowing for strong adhesion between fibers through heat-sealing and enabling the nonwoven fabric to be made thinner. By making the nonwoven fabric thinner, the number of separation membrane layers per separation element unit can be increased, improving filtration performance. By using core-sheath type composite fibers, the fibers in the nonwoven fabric can be strongly bonded together by heat-sealing during nonwoven fabric manufacturing. Compared to a blended fiber type in which fibers made only of high-melting-point polymers and fibers made only of low-melting-point polymers are mixed, this results in less variation in adhesion points on the sheet and a nonwoven fabric with a uniform basis weight.

[0044] The core component of the aforementioned core-sheath composite fiber is a high-melting-point polymer, and the sheath component is a low-melting-point polymer, with a melting point difference of 15°C to 45°C. That is, the melting point of the sheath component is between [(melting point of core component)-45]°C and [(melting point of core component)-15]°C. By setting the melting point difference to 15°C or more (i.e., the melting point of the sheath component is between [(melting point of core component)-15]°C, and so on), preferably 20°C or more (the melting point of the sheath component is between [(melting point of core component)-20]°C), only the low-melting-point polymer of the sheath component can be bonded in the heat-sealing process, and the strength of the high-melting-point polymer placed in the core can be maintained. This improves the mechanical strength of the nonwoven fabric. Furthermore, the basis weight of the nonwoven fabric can be controlled by heat-sealing, improving permeability with the separation film-forming component and improving adhesion to the separation film. Furthermore, by combining improved adhesion with mechanical strength, the peel strength of the separation membrane can be enhanced, fuzz generation on the surface of the nonwoven fabric can be suppressed, and surface smoothness and dimensional stability can also be improved. In addition, since the thickness of the nonwoven fabric can be reduced, the number of separation membrane layers per separation element unit can be increased, thereby improving filtration performance.

[0045] On the other hand, by setting the melting point difference to 45°C or less (the melting point of the sheath component is [(melting point of the core component) - 45]°C or higher), preferably 40°C or less (the melting point of the sheath component is [(melting point of the core component) - 40]°C or higher), excessive adhesion of the low-melting-point polymer of the sheath component during heat-sealing can be suppressed. This allows for control of the basis weight of the nonwoven fabric and suppresses a decrease in the permeability of the separation film-forming component to the nonwoven fabric. Suppressing the decrease in the permeability of the separation film-forming component improves the adhesion between the nonwoven fabric and the separation film, thus suppressing a decrease in the peel strength of the separation film. Furthermore, during the manufacturing of the nonwoven fabric, the melting point difference with the high-melting-point polymer of the core component can be reduced, which suppresses the decomposition of the low-melting-point polymer of the sheath component during spinning and suppresses yarn breakage. As a result, the mechanical strength of the nonwoven fabric can be improved, and the generation of fluff can be suppressed, thus improving surface smoothness.

[0046] The melting point difference can be controlled to a desired range by the copolymerization amount of the polymer. As a melting point control substance in the low-melting-point polymer of the sheath component, dicarboxylic acid components are preferred considering copolymerization to polyester, with isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, adipic acid, and sebacic acid being more preferred, and isophthalic acid being even more preferred due to its good polymerizability during copolymerization. These dicarboxylic acid components are preferably 5 mol% to 25 mol% of the total acid components from the viewpoint of controlling the melting point. The dicarboxylic acid component is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 11 mol% or more. On the other hand, by setting the dicarboxylic acid component to 25 mol% or less, more preferably 22 mol% or less, the melting point difference between the high-melting-point polymer and the low-melting-point polymer can be controlled to a desired range.

[0047] The melting point of the core component high-melting-point polymer is preferably 160°C to 320°C, from the viewpoint of obtaining a separation membrane with good film-forming properties and excellent durability when the spunbond nonwoven fabric of the present invention is used as a separation membrane support. More preferably, the melting point of the high-melting-point polymer is 170°C or higher, and even more preferably 180°C or higher, to ensure excellent mechanical strength and dimensional stability even after passing through the heating process during the manufacture of the separation membrane or separation element unit. On the other hand, more preferably, the melting point of the high-melting-point polymer is 300°C or lower, and even more preferably 280°C or lower, to suppress the spinning temperature and inhibit the decomposition of the polymer. By suppressing the decomposition of the polymer, yarn breakage during spinning can be reduced, and the mechanical strength of the nonwoven fabric can be obtained.

[0048] The method for measuring and calculating the melting points of the core and sheath components from the spunbond nonwoven fabric shall be as follows. (1) Take a 5 mg sample from the spunbond nonwoven fabric and, as a pretreatment, melt it at 290°C for 5 minutes under a nitrogen atmosphere, then rapidly cool it to room temperature at 50°C / min. (2) Using a differential scanning calorimeter (DSC, for example, TA Instruments' "Q-2000"), measure the melting point under the following conditions. • Heating rate: 2°C / min • Measuring temperature: -20°C to 300°C (3) The melting points (°C) of the core and sheath components obtained in (2) are rounded to one decimal place. (4) A sample is taken again from the spunbond nonwoven fabric, treated with alkali to dissolve the sheath component, and the yarn is made up of only the core component. (5) Take a 5 mg sample obtained in (4) and pre-process it in the same manner as in (1). (6) Perform DSC measurements in the same manner as in (2) and (3) to determine the melting point of the core component. (7) Determine the melting point of the sheath component from the melting points obtained in (4) and (6).

[0049] In the present invention, the composite mass ratio (core:sheath) of the core-sheath type composite fiber is preferably such that the core component is 50% to 95% by mass (composite mass ratio (core:sheath) is 95:5 to 50:50). By setting the core component to 50% by mass or more (composite mass ratio (core:sheath) is ~50:50, and so on), more preferably 60% by mass or more (~60:40), and even more preferably 70% by mass or more (~70:30), excessive adhesion of the low-melting-point polymer of the sheath component can be suppressed during heat-sealing. Therefore, the basis weight of the nonwoven fabric can be controlled, and the decrease in the permeability of the separation film-forming component to the nonwoven fabric can be suppressed. Suppressing the decrease in the permeability of the separation film-forming component improves adhesion to the separation film, and thus suppresses the decrease in the peel strength of the separation film. On the other hand, by setting the composite mass ratio of the core component to 95% by mass or less (95:5~), more preferably 90% by mass or less (90:10~), and even more preferably 80% by mass or less (80:20~), the low-melting-point polymer of the sheath component adheres more easily, and the basis weight of the nonwoven fabric can be controlled. By controlling the basis weight of the nonwoven fabric, the permeability of the separation membrane-forming component is improved, and the adhesion of the separation membrane is improved. The improved adhesion also improves the peel strength of the separation membrane.

[0050] The single filament fineness of the core-sheath composite fibers constituting the spunbond nonwoven fabric is preferably 0.1 dtex to 3.0 dtex, more preferably 0.3 dtex to 2.5 dtex, and even more preferably 0.5 dtex to 2.0 dtex. If the single filament fineness of the filaments constituting the spunbond nonwoven fabric is 0.1 dtex or higher, the spinnability does not decrease significantly during the manufacturing of the spunbond nonwoven fabric, and when used as a separation membrane support, it maintains air permeability, allowing the polymer solution cast during film formation to quickly penetrate into the separation membrane support, resulting in a good spunbond nonwoven fabric with less film peeling. On the other hand, if the single filament fineness of the filaments constituting the spunbond nonwoven fabric is 3.0 dtex or lower, when used as a separation membrane support, it can be made denser, resulting in a good spunbond nonwoven fabric with less over-penetration during polymer solution casting. Note that core-sheath composite fibers with different finenesses may be blended.

[0051] The average single fiber diameter of the core-sheath composite fibers constituting the spunbond nonwoven fabric is preferably 3 μm to 30 μm, more preferably 5 μm to 25 μm, and even more preferably 7 μm to 20 μm. If the average single fiber diameter of the filaments constituting the spunbond nonwoven fabric is 3 μm or more, the spinnability is less likely to decrease during the manufacturing of the spunbond nonwoven fabric, and when used as a separation membrane support, the permeability is maintained, so the polymer solution cast during film formation penetrates quickly into the separation membrane support, resulting in a good spunbond nonwoven fabric with less peeling. On the other hand, if the average single fiber diameter of the filaments constituting the spunbond nonwoven fabric is 30 μm or less, when used as a separation membrane support, high density can be achieved, resulting in a good spunbond nonwoven fabric with less over-penetration during polymer solution casting. Note that core-sheath composite fibers with different average single fiber diameters may be blended.

[0052] [Spunbond nonwoven fabric] This invention relates to a spunbond nonwoven fabric manufactured by the spunbond method. Spunbond nonwoven fabrics, which are long-fiber nonwoven fabrics composed of thermoplastic filaments, can suppress non-uniformity and membrane defects during polymer solution casting due to fluffing, which are common when using short-fiber nonwoven fabrics, when used as a separation membrane support. Furthermore, spunbond nonwoven fabrics have excellent mechanical strength, and when used as a separation membrane support, they can produce separation membranes with superior durability.

[0053] The spunbond nonwoven fabric of the present invention may be used as a single layer or as a laminate of multiple nonwoven fabrics, but it is preferable to use it as a laminate because it is easier to adjust the uniformity of the basis weight, the density distribution in the thickness direction, and the smoothness of the front and back surfaces. The number of layers when laminating is preferably 2 to 5, and if the number of layers is 2 or more, sufficient uniformity of the basis weight can be obtained compared to when it is a single layer. Furthermore, by limiting the number of layers to 5 or less, it is possible to suppress wrinkles during lamination and delamination between layers. When the spunbond nonwoven fabric laminated in this way is used as a separation membrane support, the presence of interlayers suppresses excessive permeation during polymer solution casting and reduces see-through, making it suitable for use.

[0054] In the present invention, the copolymerization amount of polyethylene glycol in the spunbond nonwoven fabric is 2% by mass or more and 15% by mass or less relative to the copolymerized polyester. By setting the copolymerization amount to preferably 4% by mass or more, and more preferably 8% by mass or more, the permeability of the separation membrane forming component can be improved. On the other hand, by setting the copolymerization amount to preferably 14% by mass or less, yarn breakage due to thickness differences during spinning can be suppressed, and consequently the strength of the spunbond nonwoven fabric can be increased.

[0055] By setting the copolymerization amount of polyethylene glycol within the above range, hydrophilicity is improved and the contact angle of the spunbond nonwoven fabric with water is reduced. This improves the permeability with the separation membrane forming components. As the hydrophilicity of the nonwoven fabric surface improves, the polymer components constituting the separation membrane penetrate rapidly into the nonwoven fabric, resulting in stronger adhesion between the nonwoven fabric and the separation membrane.

[0056] Furthermore, the copolymerization amount of polyethylene glycol in spunbond nonwoven fabric refers to the value measured and calculated by the method described above.

[0057] In the present invention, the amount of isophthalic acid component containing metal sulfonate groups in the spunbond nonwoven fabric is 2.5 mol% to 7.5 mol% of the total acid component. By setting the amount to 2.5 mol% or more, preferably 3.0 mol% or more, relative to the total acid component, the permeability with the separation membrane forming component can be improved. On the other hand, by setting the copolymerization amount to 7.5 mol% or less, preferably 7.0 mol% or less, relative to the total acid component, yarn breakage due to the increase in the extensional viscosity of the sheath component during spinning can be suppressed, and consequently, the strength of the spunbond nonwoven fabric can be increased.

[0058] By setting the metal sulfonate group-containing isophthalic acid component within the above range, hydrophilicity is improved, and the contact angle of the spunbond nonwoven fabric with water is reduced. As a result, the polymer solution constituting the separation membrane penetrates rapidly into the nonwoven fabric, strengthening the adhesion between the nonwoven fabric and the separation membrane, and making it possible to obtain a spunbond nonwoven fabric that is excellent as a separation membrane support.

[0059] The amount of the metal sulfonate group-containing isophthalic acid component in the spunbonded nonwoven fabric refers to a value measured and calculated by the above method.

[0060] The basis weight of the spunbonded nonwoven fabric of the present invention is 20 g / m 2 to 150 g / m 2 , which is preferable. The basis weight is more preferably 30 g / m 2 or more, still more preferably 40 g / m 2 or more, whereby when the nonwoven fabric is used as a separation membrane support, it is excellent in high mechanical strength and dimensional stability. On the other hand, the basis weight is more preferably 120 g / m 2 or less, still more preferably 90 g / m 2 or less, whereby when the nonwoven fabric is used as a separation membrane support, the thickness of the separation membrane can be reduced, the number of laminated separation membranes per separation element unit can be increased, and the filtration performance can be improved.

[0061] Regarding the basis weight of each laminated spunbonded nonwoven fabric, there is no particular limitation as long as the basis weight of the final separation membrane support is within the range of 20 g / m 2 to 150 g / m 2 , for example, a lamination of three layers each having a basis weight of 10 g / m 2 or a lamination of two layers each having a basis weight of 30 g / m 2 , is appropriately determined according to the product design.

[0062] The thickness of the spunbond nonwoven fabric of the present invention is determined appropriately according to the application and product design, but is preferably 0.01 mm to 1.00 mm, and more preferably 0.03 mm to 0.80 mm. If the thickness of the spunbond nonwoven fabric is 0.01 mm or more, a spunbond nonwoven fabric with excellent mechanical strength and durability can be obtained. On the other hand, if the thickness of the spunbond nonwoven fabric is 1.00 mm or less, the rigidity will not be too high, and the handling will be excellent. Furthermore, when used as a separation membrane support, the thickness is preferably 0.03 mm to 0.20 mm, more preferably 0.04 mm to 0.16 mm, and even more preferably 0.05 mm to 0.12 mm. If the thickness is 0.03 mm or more, the mechanical strength and dimensional stability as a separation membrane support are excellent. On the other hand, if the thickness of the nonwoven fabric is 0.20 mm or less, the separation membrane forming component can penetrate into the inside of the nonwoven fabric, and the adhesion between the nonwoven fabric and the separation membrane is improved, so high membrane peel strength can be obtained.

[0063] The density of the spunbond nonwoven fabric of the present invention is 0.5 g / cm³. 3 ~1.8g / cm 3 Preferably, the density is 0.6 g / cm³. 3 More preferably 0.7 g / cm³ 3 As a result, when used as a separation membrane support, it exhibits high mechanical strength and excellent dimensional stability. On the other hand, the density is more preferably 1.4 g / cm³. 3 More preferably, 1.0 g / cm³ 3 By doing the following, when used as a separation membrane support, the thickness of the separation membrane can be reduced and the number of separation membrane layers per separation element unit can be increased, thereby improving filtration performance.

[0064] The spunbond nonwoven fabric of the present invention preferably has an arithmetic mean roughness of 0.1 μm or more and 10 μm or less on the surface of the nonwoven fabric. By setting the arithmetic mean roughness to 0.1 μm or more, more preferably 0.2 μm or more, when used as a separation membrane support, permeability is maintained, so that the polymer solution cast during film formation quickly penetrates into the interior of the separation membrane support, improving adhesion to the separation membrane and providing a separation membrane support with excellent film peel strength and less peeling from the separation membrane. On the other hand, by setting the arithmetic mean roughness to 10 μm or less, more preferably 8 μm or less, when used as a separation membrane support, surface smoothness is improved, allowing the polymer solution constituting the separation membrane to be uniformly formed on the surface of the membrane substrate, and providing a separation membrane support with excellent film peel strength and less peeling from the separation membrane.

[0065] The spunbond nonwoven fabric of the present invention has a water contact angle of 0° or more and 80° or less on the surface of the spunbond nonwoven fabric. By setting the water contact angle to 0° or more, preferably 5° or more, more preferably 10° or more, and particularly preferably 15° or more, when used as a separation membrane support, the leakage of the polymer solution constituting the separation membrane can be suppressed, and when forming a composite membrane, the separation membrane composed of polymer components can maintain a sufficient thickness as a support layer. On the other hand, by setting the water contact angle to 80° or less, preferably less than 70°, more preferably 50° or less, and even more preferably 40° or less, the hydrophilicity of the nonwoven fabric surface is improved, and when used as a separation membrane support, the polymer solution constituting the separation membrane penetrates quickly into the nonwoven fabric, improving adhesion to the separation membrane and providing a separation membrane support with excellent membrane peel strength that reduces peeling from the separation membrane.

[0066] The spunbond nonwoven fabric of the present invention is preferably capable of suppressing the leaching of internal substances into water for use in water treatment applications. The amount of leaching is defined by the total organic carbon (TOC) content in the Water Supply Act test (JIS S3200-7:2010 "Water supply equipment - Leaching performance test method"). The TOC content is an indicator of water pollution, and the specified value for tap water is 3 mg / L or less. Spunbond nonwoven fabrics used in water treatment applications must meet this standard. Therefore, by setting the TOC content of the spunbond nonwoven fabric of the present invention to preferably 3.0 mg / L or less, more preferably 2.5 mg / L or less, and even more preferably 1.5 mg / L or less, it is possible to demonstrate that there are few impurities in the separated liquid when the spunbond nonwoven fabric is used as a separation membrane support.

[0067] [Method for manufacturing spunbond nonwoven fabric] Next, the method for producing the spunbond nonwoven fabric of the present invention will be described in detail.

[0068] The spunbond method for manufacturing spunbond nonwoven fabrics involves melting a resin, spinning it through a spinneret, cooling and solidifying the resulting yarn, then using an ejector to stretch and collect it on a moving net to form a fiber web, followed by heat bonding. Various shapes of spinnerets and ejectors can be used, such as round or rectangular. Among these, a combination of a rectangular spinneret and a rectangular ejector is preferred from the viewpoint of using relatively little compressed air and minimizing fusion and friction between the yarns.

[0069] In this invention, a copolymer polyester containing a polyester core component, polyethylene glycol and / or a metal sulfonate group-containing isophthalic acid component as a sheath component is vacuum-dried, then melted and weighed in an extruder and supplied to a spinneret to be spun out as long fibers. The spun long fibers are cooled and solidified, then pulled and stretched by compressed air sprayed from an ejector.

[0070] To improve the strength of the long fibers, which contribute to the mechanical strength of the nonwoven sheet, the spinning speed is preferably 2000 m / min or more, more preferably 3000 m / min or more, and even more preferably 3500 m / min or more, allowing for a higher degree of orientation and crystallization of the long fibers. On the other hand, excessive orientation and crystallization of the long fibers inhibits thermal adhesion, so the spinning speed is preferably 5500 m / min or less, more preferably 5000 m / min or less, and even more preferably 4500 m / min or less. Furthermore, excessive orientation and crystallization causes fiber shrinkage, inducing deformation such as bending and curling of the spunbond nonwoven fabric, hence the aforementioned spinning speed is preferable. In the spunbond method, the spinning speed can be controlled by adjusting the suction pressure during suction stretching with high-speed suction gas.

[0071] Next, the obtained long fibers are collected on a moving net to form a fiber web, and then continuously heat-pressed and entangled to integrate them, thereby obtaining a spunbond nonwoven fabric.

[0072] Next, the obtained spunbond nonwoven fabrics are laminated and heat-pressed to obtain a separation membrane support. A preferred method is to laminate the spunbond nonwoven fabrics obtained by the spunbond method in a temporarily bonded state and then bond them by heat-press. Heat-press can be performed using methods such as heat bonding with a combination of flat rolls and engraving rolls, or entanglement using needle punching or water jet punching. However, it is preferable to have excellent uniformity of basis weight and surface smoothness so as not to cause non-uniformity of the membrane or pinhole defects due to fuzzing, etc. For this reason, it is preferable to integrate the nonwoven fabric sheets with a pair of upper and lower flat rolls. Furthermore, a heat-press method using heated metal rolls and unheated elastic rolls is also preferably used, as it suppresses the fusion and unevenness of the fibers on the surface of the spunbond nonwoven fabric and maintains its shape, allowing the separation membrane forming components to penetrate into the nonwoven fabric when used as a separation membrane support, thereby obtaining adhesion of the separation membrane. Examples of elastic rolls include so-called paper rolls such as paper, cotton, and aramid paper, as well as resin rolls such as urethane resin, silicone resin, and hard rubber.

[0073] [Uses of spunbond nonwoven fabrics] The separation membrane using spunbond nonwoven fabric of the present invention is a separation membrane formed on a spunbond nonwoven fabric, i.e., a separation membrane support, after heat compression bonding. Examples include semipermeable membranes such as microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, and reverse osmosis membranes.

[0074] A preferred method for manufacturing the separation membrane involves casting a polymer solution onto at least one surface of a separation membrane support to form a membrane with separation capabilities. Furthermore, if the separation membrane is a semipermeable membrane, it is also preferable to form a composite membrane containing a support layer and a semipermeable membrane layer (in this case, the support layer does not necessarily have separation capabilities).

[0075] The polymer component in the polymer solution cast onto the separation membrane support has separation function after film formation, and it is preferable that this polymer component be at least one selected from the group consisting of polysulfone, polyethersulfone, polyarylethersulfone, polyimide, polyvinylidene fluoride, and cellulose acetate. In particular, from the viewpoint of chemical, mechanical, and thermal stability, a solution of polysulfone or a solution of polyarylethersulfone is preferably used. The solvent can be appropriately selected depending on the film-forming material. Furthermore, in the case of a composite membrane that includes a support layer and a semipermeable membrane layer, a crosslinked polyamide membrane obtained by polycondensation of a polyfunctional acid halide and a polyfunctional amine is preferably used as the semipermeable membrane.

[0076] In the separation membrane made of spunbond nonwoven fabric of the present invention, the penetration rate of the polymer solution into the nonwoven fabric is preferably 5% to 70%, more preferably 10% to 60%, and even more preferably 15% to 50%. The penetration rate of the polymer solution is calculated by observing the cross-section after the separation membrane is formed and determining the area occupied by the polymer component per unit area of ​​the nonwoven fabric. ((Area occupied by polymer components) / (Area of ​​nonwoven fabric)) × 100 = Permeability (%) As the permeability improves, the adhesion between the separation membrane, composed of polymer components, and the spunbond nonwoven fabric, which serves as the separation membrane support, improves, resulting in high membrane peel strength. On the other hand, the permeability of the polymer solution is preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less. By setting it to 50% or less, the leakage of the polymer solution to the back can be suppressed, and when forming a composite membrane, the separation membrane composed of polymer components can maintain a sufficient thickness as a support layer.

[0077] The peel strength of the separation membrane from the separation membrane support of the present invention is preferably 0.30 N / 15 mm or higher at any point, more preferably 0.70 N / 15 mm or higher, and even more preferably 1.00 N / 15 mm or higher. The higher the membrane peel strength, the more effectively the peeling of the separation membrane from the spunbond nonwoven fabric can be suppressed, improving film formation performance. Furthermore, it is possible to provide a separation membrane that can prevent peeling under high pressure and fluctuations in operating pressure when used as a separation element unit.

[0078] While the spunbond nonwoven fabric of the present invention is intended for use as a support membrane for water treatment, it can also be suitably used for other purposes, such as industrial materials like filters, filter substrates, and wire winding materials; building materials like wallpaper, breathable waterproof sheets, roof underlayment, sound insulation materials, heat insulation materials, and sound absorbing materials; household materials like wrapping materials, bag materials, sign materials, and printing substrates; civil engineering materials like weed control sheets, drainage materials, ground reinforcement materials, sound insulation materials, and sound absorbing materials; agricultural materials like covering materials and light-shielding sheets; ceiling materials; and vehicle materials like spare tire covers. [Examples]

[0079] The spunbond nonwoven fabric of the present invention will be specifically described below based on examples. These are illustrative examples, and the present invention is not limited thereto. The physical properties of the separation membrane support, the spunbond nonwoven fabric constituting the separation membrane support, and the core-sheath type composite fibers constituting the spunbond nonwoven fabric, as well as the physical properties in the examples, were measured by the following method.

[0080] (1) Melting point of polymer (°C) The melting point of the polymer was measured using a differential scanning calorimeter (DSC). Equipment: TA Instruments "Q-2000" Heating rate: 2°C / min Measurement temperature range: -20°C to 300°C.

[0081] (2) Evaluation of spinnability Using copolymer polyester as the sheath component, the yarn was spun from the pores at a spinneret temperature of 300°C and a predetermined composite mass ratio. The spinnability was then evaluated on a three-point scale (S, A, B) based on the number of yarn breaks during spinning at a spinning speed of 4000 m / min using an ejector. Rating S: No thread breakage per hour Rating A: Number of thread breaks per hour is between 1 and 10. Rating B: More than 11 thread breaks per hour (3) Single yarn fineness (dtex) The single filament fineness was determined by randomly taking 10 small sample pieces from the spunbond nonwoven fabric, taking images at 500 to 3000x magnification using a scanning electron microscope (Keyence Corporation "VHX-2000"), measuring the diameter of 10 single fibers from each sample (a total of 100 fibers), and then correcting the average of these values ​​for polymer density and rounding to two decimal places.

[0082] (4) Average single fiber diameter (μm) The average single fiber diameter was calculated by randomly taking 10 small samples from spunbond nonwoven fabric, taking 500-3000x magnification images using a scanning electron microscope (Keyence Corporation "VHX-2000"), measuring the diameter of 10 single fibers from each sample (a total of 100 fibers), and rounding the average value of these measurements to the nearest tenth.

[0083] (5) Copolymerization amount of polyethylene glycol in spunbond nonwoven fabric (mass%), Copolymerization amount of polyethylene glycol in the sheath component of core-sheath type composite fibers contained in spunbond nonwoven fabric (mass%) The copolymerization amount of polyethylene glycol was measured and calculated using the method described above, with the "AL-400" measuring device manufactured by JEOL Ltd.

[0084] (6) Copolymerization amount (mol%) of metal sulfonate group-containing isophthalic acid component relative to the total acid component in the sheath component of core-sheath type composite fibers in spunbond nonwoven fabric, Copolymerization amount (mol%) of metal sulfonate group-containing isophthalic acid component relative to the total acid component in the sheath component of core-sheath type composite fibers contained in spunbond nonwoven fabric The copolymerization amount of metal sulfonate group-containing isophthalic acid component relative to the total acid component in the sheath component was measured and calculated using the method described above, with the "AL-400" measuring instrument manufactured by JEOL Ltd.

[0085] (7) Basis weight (g / m²) of spunbond nonwoven fabric 2 ) Three 30cm x 50cm spunbond nonwoven fabric samples were taken, and the weight of each sample was measured. The average of the obtained values ​​was converted to a value per unit area and rounded to the first decimal place.

[0086] (8) Thickness of spunbond nonwoven fabric (mm) The thickness of the spunbond nonwoven fabric was determined by randomly selecting 10 small sample pieces. Using a micrometer manufactured by Mitutoyo Corporation, the nonwoven fabric was clamped between a 6 mm diameter anvil and spindle, and two points within the sample were measured at equal intervals to the nearest 0.01 mm. The average of the 20 points was rounded to the third decimal place.

[0087] (9) Density of spunbond nonwoven fabric (g / cm³) 3 ) The basis weight of the spunbond nonwoven fabric was divided by the thickness of the spunbond nonwoven fabric, and the result was rounded to the third decimal place.

[0088] (10) Arithmetic surface roughness (μm) of spunbond nonwoven fabric The arithmetic surface roughness (Ra) of the spunbond nonwoven fabric was determined by the line roughness at 1000 μm using the light transmission method with a laser microscope. Ten measurements were taken for each level, changing the measurement position each time. The average value, excluding the maximum and minimum values, was rounded to the first decimal place to calculate the Ra. A smaller arithmetic surface roughness indicates improved surface smoothness of the nonwoven fabric and improved adhesion of the separation film to the nonwoven fabric. Equipment: VK-X200 manufactured by Keyence Corporation.

[0089] (11) Contact angle of spunbond nonwoven fabric with water (°) The contact angle (°) between the surface of the spunbond nonwoven fabric and water was determined by placing a 2 μL droplet of deionized water on the spunbond nonwoven fabric and taking an image 1 second after placement. Ten measurements were taken for each level, changing the measurement position. The maximum and minimum values ​​were removed, and the average value was calculated to determine the contact angle with water, which was rounded to the first decimal place. A lower contact angle indicates improved hydrophilicity of the nonwoven fabric surface. Higher hydrophilicity improves the penetration rate of the separation membrane components into the nonwoven fabric, and thus improves the adhesion of the separation membrane to the nonwoven fabric. In Tables 1 to 6, the measurement results of the contact angle (°) between the surface of the spunbond nonwoven fabric and water are simply abbreviated as "contact angle (°)".

[0090] (12) TOC content of spunbond nonwoven fabric (mg / L) The TOC content of spunbond nonwoven fabric was determined according to JIS S3200-7:2010 "Water supply fixtures - Leaching performance test method". The nonwoven fabric was immersed in deionized water at 25°C for 1 hour with a bath ratio of 100 to the spunbond nonwoven fabric. After immersion, the nonwoven fabric was washed 6 times with 50 mL of deionized water and then immersed again at 25°C for 16 hours. 0.5 mL of 2 mol / L hydrochloric acid was added dropwise to 20 mL of the immersed solution, and after bubbling for 15 minutes, TOC analysis was performed. A lower TOC content indicates less leaching of internal substances into water, and suggests fewer impurities in the filtered solution. Equipment: Desktop TOC measuring instrument (TNC-6000, manufactured by Toray Engineering Co., Ltd.) In Tables 1 to 6, the measurement results for the TOC content (mg / L) of spunbond nonwoven fabrics are simply abbreviated as "TOC content (mg / L)".

[0091] (13) Percentage of polymer components into spunbond nonwoven fabric The penetration rate of the polymer components constituting the separation membrane into the spunbond nonwoven fabric was calculated by observing a cross-section after forming the separation membrane on the surface of the spunbond nonwoven fabric, and determining the area occupied by the polymer components per unit area of ​​the spunbond nonwoven fabric. A higher penetration rate indicates better adhesion between the spunbond nonwoven fabric and the separation membrane, preventing the separation membrane from peeling off the spunbond nonwoven fabric and improving film formation. ((Area occupied by polymer components) / (Area of ​​nonwoven fabric)) × 100 = Permeability (%) In Tables 1 to 6, the measurement results for the penetration rate (%) of polymer components into spunbond nonwoven fabrics are abbreviated as "PSf penetration rate (%)".

[0092] (14) Peel strength of the separation membrane (N / 15mm) The prepared polysulfone separation membrane (PSf membrane) was cut to a width of 15 mm and a length of 13 cm. Kikusui Tape Co., Ltd.'s Kikraft tape was attached to the PSf membrane surface, and an 8 cm section of the PSf layer at one end was peeled from the separation membrane support. The PSf layer was fixed to one side of the grip of a constant-speed stretching tensile testing machine, and the spunbond nonwoven fabric, which served as the separation membrane support, was fixed to the other side. The strength was measured under the conditions of a gripping distance of 15 mm and a tensile speed of 15 mm / min. The average strength was calculated from the gripping distance of 15 mm to 75 mm, and the value was rounded to the third decimal place to determine the membrane peel strength. The average value (N / 15 mm) was taken as the peel strength of the separation membrane (average value for N=5). In Tables 1 to 6, the measurement results of the peel strength of the separation membrane (N / 15 mm) are referred to as "Peel strength of PSf membrane (N / 15 mm)".

[0093] [Example 1] Polyethylene terephthalate (PET) with a melting point of 255°C and containing 0.3% by mass of titanium dioxide was used as the core component. 11.5 mol% of isophthalic acid and 2% by mass of polyethylene glycol (PEG) (PEG20000, manufactured by Sanyo Chemical Industries, Ltd.) with a number average molecular weight of 20000 were copolymerized to form a copolymerized polyethylene terephthalate (PET / I-PEG) with a melting point of 230°C and containing 0.2% by mass of titanium dioxide, which was used as the sheath component. The core and sheath components were melted at temperatures of 295°C and 270°C, respectively. After spinning from the pores at a spinneret temperature of 300°C and a core:sheath mass ratio of 80:20, the fibers were spun at a spinning speed of 4000 m / min using an ejector to form concentric core-sheath type filaments (circular cross-section) with the entire surface covered by polyethylene terephthalate containing polyethylene glycol. These filaments were then collected as a fiber web on a moving net conveyor. The collected fiber web was heat-bonded using a pair of embossing rolls at a heat bonding temperature of 120°C. The resulting filament single-fiber fineness was 1.9 dtex, the average single-fiber diameter was 14 μm, and the basis weight was 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0094] Two layers of the resulting spunbond nonwoven fabric were layered and heat-pressed together, resulting in a fabric weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 A spunbond nonwoven fabric with an arithmetic mean surface roughness of 10 μm was manufactured, and a spunbond nonwoven laminate was obtained. The contact angle of the obtained spunbond nonwoven laminate was 70°, and the TOC content was 0.9 mg / L.

[0095] A polymer solution of polysulfone (PSf) dissolved in N,N-dimethylformamide (DMF) was cast onto the obtained spunbond nonwoven fabric laminate to form a separation film. The penetration rate of polysulfone into the nonwoven fabric laminate was 12%, and the peel strength of the polysulfone film from the nonwoven fabric laminate was 0.88 N / 15 mm. The results are shown in Table 1.

[0096] [Examples 2-4] The same procedure as in Example 1 was followed, except that PEG (PEG20000, manufactured by Sanyo Chemical Industries, Ltd.) with a number average molecular weight of 20000 was copolymerized at 4% by mass, 8% by mass, and 14% by mass. The resulting constituent filaments, whose entire surface was covered with polyethylene terephthalate containing polyethylene glycol, had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0097] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The obtained spunbond nonwoven fabric laminate in Example 2 had a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 9 μm, a contact angle of 60°, and a TOC content of 1.1 mg / L. Furthermore, the polysulfone penetration rate was 13%, and the film peel strength was 1.03 N / 15 mm.

[0098] Example 3 has a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 8 μm, a contact angle of 40°, and a TOC content of 1.4 mg / L. Furthermore, the polysulfone penetration rate was 15%, and the film peel strength was 1.47 N / 15 mm.

[0099] Example 4 has a basis weight of 70 g / m². 2 Thickness 0.10 mm, density 0.70 g / cm³ 3 The surface had an arithmetic mean roughness of 6 μm, a contact angle of 15°, and a TOC content of 2.5 mg / L. The polysulfone penetration rate was 25%, and the film peel strength was 2.35 N / 15 mm. The results are shown in Table 1.

[0100] [Examples 5-7] The same procedure as in Example 1 was followed, except that PEG (PEG6000S, manufactured by Sanyo Chemical Industries, Ltd.) with a number average molecular weight of 7000 was copolymerized at 2% by mass, 8% by mass, and 14% by mass. The resulting constituent filaments, whose entire surface was covered with polyethylene terephthalate containing polyethylene glycol, had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0101] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The obtained spunbond nonwoven fabric laminate in Example 5 had a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 11 μm, a contact angle of 65°, and a TOC content of 0.7 mg / L. Furthermore, the polysulfone penetration rate was 10%, and the film peel strength was 0.71 N / 15 mm.

[0102] Example 6 has a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 9 μm, a contact angle of 60°, and a TOC content of 1.2 mg / L. The polysulfone penetration rate was 13%, and the film peel strength was 0.98 N / 15 mm.

[0103] Example 7 has a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 8 μm, a contact angle of 20°, and a TOC content of 1.9 mg / L. The polysulfone penetration rate was 21%, and the film peel strength was 1.96 N / 15 mm. The results are shown in Table 1.

[0104] [Example 8] The procedure was carried out in the same manner as in Example 1, except that a copolymerized polyester was used in which 22 mol% isophthalic acid and 8% by mass of PEG (PEG20000, manufactured by Sanyo Chemical Industries, Ltd.) with a number average molecular weight of 20000 were copolymerized as the sheath component relative to the total acid component, and a melting point of 210°C and 0.2% by mass of titanium dioxide was used. The entire surface of the resulting filament, covered with polyethylene terephthalate containing polyethylene glycol, had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0105] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The basis weight of the obtained spunbond nonwoven fabric laminate was 70 g / m². 2 The thickness is 0.07 mm and the density is 1.00 g / cm³. 3 The surface had an arithmetic mean roughness of 5 μm, a contact angle of 41°, and a TOC content of 2.3 mg / L.

[0106] A polymer solution of polysulfone dissolved in DMF was cast onto the obtained spunbond nonwoven fabric laminate to form a separation film. The penetration rate of polysulfone into the nonwoven fabric laminate was 11%, and the peel strength of the polysulfone film from the nonwoven fabric laminate was 0.74 N / 15 mm. The results are shown in Table 1.

[0107] [Example 9] The same procedure as in Example 1 was used, except that a copolymerized polyester was used in which 8.0 mol% isophthalic acid and 8% by mass of PEG (PEG20000, manufactured by Sanyo Chemical Industries, Ltd.) with a number average molecular weight of 20000 were copolymerized as the sheath component relative to the total acid component, with a melting point of 240°C and containing 0.2% by mass of titanium dioxide. The entire surface of the resulting filament, covered with polyethylene terephthalate containing polyethylene glycol, had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0108] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The basis weight of the obtained spunbond nonwoven fabric laminate was 70 g / m². 2 The thickness is 0.14 mm and the density is 0.50 g / cm³. 3 The surface had an arithmetic mean roughness of 11 μm, a contact angle of 42°, and a TOC content of 1.5 mg / L.

[0109] A polymer solution of polysulfone dissolved in DMF was cast onto the obtained spunbond nonwoven fabric laminate to form a separation film. The penetration rate of polysulfone into the nonwoven fabric laminate was 12%, and the peel strength of the polysulfone film from the nonwoven fabric laminate was 0.93 N / 15 mm. The results are shown in Table 1.

[0110] [Table 1]

[0111] [Examples 10-12] The same procedure as in Example 1 was followed, except that 14% by mass of PEG with a number average molecular weight of 1000 (PEG1000, manufactured by Sanyo Chemical Industries, Ltd.), PEG with a number average molecular weight of 3400 (PEG4000S, manufactured by Sanyo Chemical Industries, Ltd.), and 8% by mass of PEG with a number average molecular weight of 35000 (PEG35000, manufactured by Sigma-Aldrich) were copolymerized. The resulting filament, whose entire surface was covered with polyethylene terephthalate containing polyethylene glycol, had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0112] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The obtained spunbond nonwoven fabric laminate in Example 10 had a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 11 μm, a contact angle of 80°, and a TOC content of 0.9 mg / L. Furthermore, the polysulfone penetration rate was 5%, and the film peel strength was 0.31 N / 20 mm.

[0113] Example 11 had a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 11 μm, a contact angle of 77°, and a TOC content of 0.9 mg / L. Furthermore, the polysulfone penetration rate was 6%, and the film peel strength was 0.34 N / 15 mm.

[0114] Example 12 has a basis weight of 70 g / m². 2 The thickness is 0.06 mm and the density is 1.17 g / cm³. 3 The surface had an arithmetic mean roughness of 8 μm, a contact angle of 20°, and a TOC content of 3.5 mg / L. The polysulfone penetration rate was 8%, and the film peel strength was 0.41 N / 20 mm. The results are shown in Table 2.

[0115] [Examples 13-17] The procedure was carried out in the same manner as in Example 3, except that the mass ratio of the core component to the sheath component was set to 95:5, 90:10, 70:30, 60:40, and 50:50. The resulting filament, whose entire surface was covered with polyethylene terephthalate containing polyethylene glycol, had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0116] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The obtained spunbond nonwoven fabric laminate in Example 13 had a basis weight of 70 g / m². 2 It has a thickness of 0.13 mm and a density of 0.54 g / cm³. 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 41°, and a TOC content of 0.9 mg / L. Furthermore, the polysulfone penetration rate was 8%, and the film peel strength was 0.39 N / 15 mm.

[0117] Example 14 had a basis weight of 70 g / m². 2 The thickness is 0.12 mm and the density is 0.58 g / cm³. 3The surface had an arithmetic mean roughness of 9 μm, a contact angle of 40°, and a TOC content of 1.1 mg / L. The polysulfone penetration rate was 11%, and the film peel strength was 0.76 N / 15 mm.

[0118] Example 15 has a basis weight of 70 g / m². 2 The thickness is 0.08 mm and the density is 0.86 g / cm³. 3 The surface had an arithmetic mean roughness of 7 μm, a contact angle of 41°, and a TOC content of 1.8 mg / L. Furthermore, the polysulfone penetration rate was 14%, and the film peel strength was 1.08 N / 15 mm.

[0119] Example 16 has a basis weight of 70 g / m². 2 The thickness is 0.05 mm and the density is 1.40 g / cm³. 3 The surface had an arithmetic mean roughness of 6 μm, a contact angle of 39°, and a TOC content of 2.2 mg / L. The polysulfone penetration rate was 12%, and the film peel strength was 0.83 N / 15 mm.

[0120] Example 17 has a basis weight of 70 g / m². 2 It has a thickness of 0.04 mm and a density of 1.75 g / cm³. 3 The surface had an arithmetic mean roughness of 5 μm, a contact angle of 40°, and a TOC content of 2.7 mg / L. The polysulfone penetration rate was 7%, and the film peel strength was 0.34 N / 15 mm. The results are shown in Table 2.

[0121] [Table 2]

[0122] [Example 18] Polyethylene terephthalate (PET) with a melting point of 255°C and containing 0.3% by mass of titanium dioxide was used as the core component. A copolymerized polyester (PET / I-SSIA) with a melting point of 230°C and containing 0.2% by weight of titanium dioxide was copolymerized with 9.5 mol% isophthalic acid and 2.5 mol% sodium 5-sulfoisophthalate (SSIA) relative to the total acid component, and this copolymerized polyester contained 0.2% by weight of titanium dioxide was used as the sheath component. The core component and sheath component were melted at temperatures of 295°C and 270°C, respectively. After spinning from the pores at a spinneret temperature of 300°C and a core:sheath mass ratio of 80:20, the fibers were spun at a spinning speed of 4000 m / min using an ejector to form concentric core-sheath type filaments (circular cross-section) with the entire surface covered with polyethylene terephthalate containing components derived from sodium 5-sulfoisophthalate, and these were collected as a fiber web on a moving net conveyor. The collected fiber web is heat-pressed using a pair of embossing rolls, resulting in a single filament fineness of 1.4 dtex, an average single fiber diameter of 12 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0123] Two layers of the resulting spunbond nonwoven fabric were layered and heat-pressed together, resulting in a fabric weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 A spunbond nonwoven fabric with an arithmetic mean surface roughness of 12 μm was manufactured, and a spunbond nonwoven laminate was obtained. The contact angle of the obtained spunbond nonwoven laminate was 66°, and the TOC content was 1.2 mg / L.

[0124] A polymer solution of polysulfone (PSf) dissolved in N,N-dimethylformamide (DMF) was cast onto the obtained spunbond nonwoven laminate to form a separation film. The penetration rate of polysulfone into the nonwoven laminate was 13%, and the peel strength of the polysulfone film from the nonwoven laminate was 0.54 N / 15 mm. The results are shown in Table 3.

[0125] [Example 19] The procedure was carried out in the same manner as in Example 18, except that a copolymerized polyester was used in which 9.5 mol% isophthalic acid and 5.0 mol% sodium 5-sulfoisophthalate were copolymerized relative to the total acid component as the sheath component, with a melting point of 230°C and containing 0.2% by weight of titanium dioxide. The entire surface of the resulting filament, covered with polyethylene terephthalate containing a component derived from sodium 5-sulfoisophthalate, had a single filament fineness of 1.4 dtex, an average single fiber diameter of 12 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0126] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 18 to obtain a spunbond nonwoven fabric laminate. The basis weight of the obtained spunbond nonwoven fabric laminate was 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 64°, and a TOC content of 1.4 mg / L.

[0127] A polymer solution, in which polysulfone was dissolved in DMF, was cast onto the obtained spunbond nonwoven fabric laminate to form a separation film. The penetration rate of polysulfone into the nonwoven fabric laminate was 16%, and the peel strength of the polysulfone film from the nonwoven fabric laminate was 0.62 N / 15 mm. The results are shown in Table 3.

[0128] [Example 20] The procedure was carried out in the same manner as in Example 18, except that a copolymerized polyester was used in which 9.5 mol% isophthalic acid and 7.5 mol% sodium 5-sulfoisophthalate were copolymerized relative to the total acid component as the sheath component, with a melting point of 230°C and containing 0.2% by weight of titanium dioxide. The entire surface of the resulting filament, covered with polyethylene terephthalate containing a component derived from sodium 5-sulfoisophthalate, had a single filament fineness of 1.4 dtex, an average single fiber diameter of 12 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0129] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 18 to obtain a spunbond nonwoven fabric laminate. The basis weight of the obtained spunbond nonwoven fabric laminate was 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 59°, and a TOC content of 1.6 mg / L.

[0130] A polymer solution, in which polysulfone was dissolved in DMF, was cast onto the obtained spunbond nonwoven fabric laminate to form a separation film. The penetration rate of polysulfone into the nonwoven fabric laminate was 25%, and the peel strength of the polysulfone film from the nonwoven fabric laminate was 0.67 N / 15 mm. The results are shown in Table 3.

[0131] [Example 21] The procedure was carried out in the same manner as in Example 18, except that a copolymerized polyester was used in which 20 mol% isophthalic acid and 5.0 mol% sodium 5-sulfoisophthalate were copolymerized relative to the total acid component as the sheath component, with a melting point of 210°C and containing 0.2% by weight of titanium dioxide. The entire surface of the resulting filament, covered with polyethylene terephthalate containing a component derived from sodium 5-sulfoisophthalate, had a single filament fineness of 1.4 dtex, an average single fiber diameter of 12 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0132] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The basis weight of the obtained spunbond nonwoven fabric laminate was 70 g / m². 2 It has a thickness of 0.04 mm and a density of 1.75 g / cm³. 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 62°, and a TOC content of 25 mg / L.

[0133] A polymer solution of polysulfone dissolved in DMF was cast onto the obtained spunbond nonwoven fabric laminate to form a separation film. The penetration rate of polysulfone into the nonwoven fabric laminate was 11%, and the peel strength of the polysulfone film from the nonwoven fabric laminate was 0.51 N / 15 mm. The results are shown in Table 3.

[0134] [Example 22] The procedure was carried out in the same manner as in Example 18, except that a copolymerized polyester was used in which 5.0 mol% isophthalic acid and 5.0 mol% sodium 5-sulfoisophthalate were copolymerized relative to the total acid component as the sheath component, with a melting point of 240°C and containing 0.2% by weight of titanium dioxide. The entire surface of the resulting filament, covered with polyethylene terephthalate containing a component derived from sodium 5-sulfoisophthalate, had a single filament fineness of 1.4 dtex, an average single fiber diameter of 12 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0135] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The basis weight of the obtained spunbond nonwoven fabric laminate was 70 g / m². 2 The thickness is 0.12 mm and the density is 0.58 g / cm³. 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 65°, and a TOC content of 1.8 mg / L.

[0136] A polymer solution of polysulfone dissolved in DMF was cast onto the obtained spunbond nonwoven fabric laminate to form a separation film. The penetration rate of polysulfone into the nonwoven fabric laminate was 19%, and the peel strength of the polysulfone film from the nonwoven fabric laminate was 0.53 N / 15 mm. The results are shown in Table 3.

[0137] [Examples 23-26] The procedure was carried out in the same manner as in Example 19, except that the mass ratio of the core component to the sheath component was set to 95:5, 90:10, 60:40, and 50:50. The resulting filament, whose entire surface was covered with polyethylene terephthalate containing a component derived from sodium 5-sulfoisophthalate, had a single filament fineness of 1.4 dtex, an average single fiber diameter of 12 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0138] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 19 to obtain a spunbond nonwoven fabric laminate. When the core:sheath ratio of the obtained spunbond nonwoven fabric laminate was 95:5, the basis weight was 70 g / m². 2 The thickness is 0.11 mm and the density is 0.64 g / cm³. 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 65°, and a TOC content of 1.0 mg / L. Furthermore, the polysulfone penetration rate was 20%, and the film peel strength was 0.51 N / 15 mm.

[0139] When the core:sheath ratio is 90:10, the weight is 70g / m². 2 Thickness 0.10 mm, density 0.70 g / cm³ 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 62°, and a TOC content of 1.2 mg / L. The polysulfone penetration rate was 17%, and the film peel strength was 0.56 N / 15 mm.

[0140] When the core:sheath ratio is 60:40, the weight is 70g / m². 2 It has a thickness of 0.04 mm and a density of 1.75 g / cm³. 3 The surface had an arithmetic mean roughness of 12 μm, a contact angle of 63°, and a TOC content of 2.5 mg / L. Furthermore, the polysulfone penetration rate was 12%, and the film peel strength was 0.53 N / 15 mm.

[0141] When the core:sheath ratio is 50:50, the weight is 70g / m². 2 It has a thickness of 0.03 mm and a density of 2.33 g / cm³. 3The arithmetic average roughness of the surface was 12 µm, the contact angle was 62°, and the TOC content was 3.0 mg / L. Further, the permeability of polysulfone was 8%, and the film peel strength was 0.42 N / 15 mm. The results are shown in Table 3.

[0142] [Table 3]

[0143] [Example 27] Polyethylene terephthalate (PET) having a melting point of 255°C and containing 0.3 mass% of titanium oxide was used as the core component. Except for using, as the sheath component, a copolymerized polyethylene terephthalate (PET / I-PEG-SSIA) obtained by copolymerizing 9.5 mol% of an isophthalic acid component relative to the total acid components, 8 mass% of PEG with a number average molecular weight of 7000 (PEG6000S manufactured by Sanyo Chemical Industries, Ltd.), and 5 mol% of sodium 5-sulfoisophthalate (SSIA), and having a melting point of 230°C and containing 0.2 mass% of titanium oxide, the procedure was carried out in the same manner as in Example 1. The single filament fineness of the constituent filaments, the entire surface of which is covered with polyethylene terephthalate containing components derived from polyethylene glycol and sodium 5-sulfoisophthalate, was 1.9 dtex, the average single fiber diameter was 14 µm, and the basis weight was 35 g / m 2 spunbonded nonwoven fabric was produced.

[0144] Two sheets of the obtained spunbonded nonwoven fabric were superimposed, lamination processing was carried out by the same method as in Example 1, and a spunbonded nonwoven fabric laminate was obtained. The obtained spunbonded nonwoven fabric laminate had a basis weight of 70 g / m 2 , a thickness of 0.09 mm, and a density of 0.78 g / cm 3 A spunbonded nonwoven fabric having an arithmetic average surface roughness of 12 µm was produced to obtain a spunbonded nonwoven fabric laminate. The contact angle of the obtained spunbonded nonwoven fabric laminate was 56°, and the TOC content was 2.2 mg / L. Further, the permeability of polysulfone was 8%, and the film peel strength was 0.68 N / 15 mm. The results are shown in Table 4.

[0145] [Example 28] The same procedure as in Example 1 was used, except that polyethylene terephthalate (PET) with a melting point of 255°C and containing 0.3% by mass of titanium dioxide was used as the core component, and 9.5 mol% of isophthalic acid, 8% by mass of PEG (PEG20000 manufactured by Sanyo Chemical Industries, Ltd.) with a number average molecular weight of 20000, and 5 mol% of sodium 5-sulfoisophthalate (SSIA) were copolymerized relative to the total acid component, and copolymerized polyethylene terephthalate (PET / I-PEG-SSIA) with a melting point of 230°C and containing 0.2% by mass of titanium dioxide was used as the sheath component. The entire surface of the resulting filament, covered with polyethylene terephthalate containing polyethylene glycol and sodium 5-sulfoisophthalate (SSIA), had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0146] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The obtained spunbond nonwoven fabric laminate had a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 11 μm, a contact angle of 35°, and a TOC content of 2.5 mg / L. The polysulfone penetration rate was 11%, and the film peel strength was 1.15 N / 15 mm. The results are shown in Table 4.

[0147] [Examples 29-31] Polyethylene terephthalate (PET) having a melting point of 255°C and containing 0.3% by mass of titanium oxide was used as the core component. A copolymerized polybutylene terephthalate containing 50% by mass of PEG with a number average molecular weight of 7000 (PEG6000S manufactured by Sanyo Chemical Industries, Ltd.), having a melting point of 220°C and containing 0.2% by mass of titanium oxide (PBT-PEG) was mixed with polybutylene terephthalate (PBT) having a melting point of 220°C and containing 0.2% by mass of titanium oxide, and copolymerized polybutylene terephthalate (PBT-PEG) copolymerized with 2% by mass, 8% by mass, and 14% by mass of PEG was used as the sheath component. The procedure was carried out in the same manner as in Example 1 except for the above, to obtain a filament entirely covered on the surface with polyethylene glycol-containing polybutylene terephthalate, which had a single filament fineness of 1.9 dtex, an average single fiber diameter of 14 μm, and a basis weight of 35 g / m 2 spunbonded nonwoven fabric was produced.

[0148] Two sheets of the obtained spunbonded nonwoven fabric were stacked, and lamination processing was carried out by the same method as in Example 1 to obtain a spunbonded nonwoven fabric laminate. For the obtained spunbonded nonwoven fabric laminate of Example 29, the basis weight was 70 g / m 2 , the thickness was 0.10 mm, the density was 0.70 g / cm 3 , the arithmetic average roughness of the surface was 11 μm, the contact angle was 65°, and the TOC content was 0.5 mg / L. Further, the polysulfone permeation rate was 9%, and the membrane peel strength was 0.69 N / 15 mm.

[0149] In Example 30, the basis weight was 70 g / m 2 , the thickness was 0.10 mm, the density was 0.70 g / cm 3 , the arithmetic average roughness of the surface was 9 μm, the contact angle was 60°, and the TOC content was 1.0 mg / L. Further, the polysulfone permeation rate was 11%, and the membrane peel strength was 0.90 N / 15 mm.

[0150] In Example 31, the basis weight was 70 g / m 2 , the thickness was 0.10 mm, the density was 0.70 g / cm 3The surface had an arithmetic mean roughness of 8 μm, a contact angle of 20°, and a TOC content of 1.7 mg / L. The polysulfone penetration rate was 20%, and the film peel strength was 1.80 N / 15 mm. The results are shown in Table 4.

[0151] [Examples 32-34] Polybutylene terephthalate (PBT), with a melting point of 220°C and containing 0.3% by mass of titanium dioxide, is used as the core component. 50% by mass of PEG (PEG6000S, manufactured by Sanyo Chemical Industries, Ltd.), with a number average molecular weight of 7000, is copolymerized. Copolymerized polybutylene terephthalate (PBT-PEG), with a melting point of 220°C and containing 0.2% by mass of titanium dioxide, is copolymerized with isophthalate components to form copolymerized polybutylene terephthalate (PBT / I). The procedure was carried out in the same manner as in Example 1, except that copolymerized polybutylene terephthalate (PBT / I-PEG), which was copolymerized with 11.5 mol%, a melting point of 200°C, 0.2 mass% titanium dioxide, and 2 mass%, 8 mass%, and 14 mass% PEG, was used as the sheath component. The entire surface of the resulting filament, covered with polyethylene glycol-containing polybutylene terephthalate, had a single filament fineness of 1.9 dtex, an average single filament diameter of 14 μm, and a basis weight of 35 g / m². 2 We manufactured spunbond nonwoven fabric.

[0152] Two layers of the obtained spunbond nonwoven fabric were stacked and laminated using the same method as in Example 1 to obtain a spunbond nonwoven fabric laminate. The obtained spunbond nonwoven fabric laminate in Example 32 had a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 10 μm, a contact angle of 64°, and a TOC content of 0.6 mg / L. Furthermore, the polysulfone penetration rate was 10%, and the film peel strength was 0.73 N / 15 mm.

[0153] Example 33 has a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3The surface had an arithmetic mean roughness of 8 μm, a contact angle of 59°, and a TOC content of 1.1 mg / L. Furthermore, the polysulfone penetration rate was 13%, and the film peel strength was 1.00 N / 15 mm.

[0154] Example 34 has a basis weight of 70 g / m². 2 It has a thickness of 0.09 mm and a density of 0.78 g / cm³. 3 The surface had an arithmetic mean roughness of 7 μm, a contact angle of 21°, and a TOC content of 1.7 mg / L. The polysulfone penetration rate was 21%, and the film peel strength was 1.98 N / 15 mm. The results are shown in Table 4.

[0155] [Table 4]

[0156] [Comparative Examples 1-3] Except for changing the copolymerization amount of polyethylene glycol with a number-average molecular weight of 20,000 used in Example 1 as shown in Table 5, the procedure was carried out in the same manner as in Example 1 to obtain a spunbond nonwoven fabric.

[0157] The spunbond nonwoven fabric obtained in Comparative Example 1 had a rough surface and low contact angle because polyethylene glycol was not copolymerized, resulting in almost no penetration of polysulfone into the nonwoven fabric. Similarly, the spunbond nonwoven fabric obtained in Comparative Example 2 had a low copolymerization amount of polyethylene glycol, resulting in lower surface roughness and contact angle than Comparative Example 1, but the penetration rate of polysulfone was insufficient. Furthermore, the spunbond nonwoven fabric obtained in Comparative Example 3 had poor melt-molding properties due to an excessive copolymerization amount of polyethylene glycol, leading to frequent yarn breakage due to differences in thickness during composite spinning with the core component, and insufficient penetration of polysulfone due to increased density, resulting in a failure to obtain high film peel strength. In addition, the generation of decomposition products and an increase in unreacted PEG led to an increase in low molecular weight components and an increase in TOC content.

[0158] [Comparative Examples 4 and 5] Except for changing the copolymerization amount of the isophthalic acid component used in Example 3 as shown in Table 5, the procedure was carried out in the same manner as in Example 3 to obtain a spunbond nonwoven fabric.

[0159] In Comparative Example 4, the spunbond nonwoven fabric had a reduced melting point of the sheath component due to an excessive copolymerization of isophthalic acid, leading to a melting point divergence with the core component and subsequent decomposition of the sheath component, resulting in decreased spinnability. The decrease in spinnability led to an increase in low-molecular-weight components due to the generation of decomposition products, and consequently, an increase in TOC. Furthermore, the reduced melting point of the sheath component caused excessive fusion of fibers during heat bonding, increasing density and resulting in insufficient polysulfone penetration. This reduced the adhesion of the separation membrane, preventing the achievement of high membrane peel strength.

[0160] The spunbond nonwoven fabric obtained in Comparative Example 5 had a low copolymerization amount of isophthalic acid and a high melting point of the sheath component, resulting in insufficient fusion during heat compression bonding, increased surface roughness, and decreased surface smoothness. Furthermore, although polysulfone permeability was achieved due to its low density, its strength as a separation membrane support was low, and the high membrane peel strength of polysulfone could not be obtained. In addition, the thickness of the nonwoven fabric increased, leading to a decrease in filtration performance.

[0161] [Comparative Example 6] A spunbond nonwoven fabric was obtained by following the same procedure as in Example 3, except that the core component used was polybutylene terephthalate (PBT) with a melting point of 220°C and containing 0.3% by mass of titanium dioxide.

[0162] In Comparative Example 6, the spunbond nonwoven fabric had a core component whose melting point was lower than that of the sheath component. As a result, both the core and sheath components fused together during heat bonding, leading to insufficient strength as a separation membrane support. Furthermore, the increased density resulted in insufficient penetration of polysulfone, making it impossible to obtain high membrane peel strength.

[0163] [Comparative Example 7] A spunbond nonwoven fabric was obtained by carrying out the same procedure as in Example 3, except that a copolymer polyester similar to the sheath component used in Example 3 was used to obtain a fiber web of single-component fibers using a single-component nozzle.

[0164] The spunbond nonwoven fabric obtained in Comparative Example 7, being a single-component fiber, lacked sufficient mechanical strength to withstand high pressure as a separation membrane support. Furthermore, the density increased due to fusion during heat sealing, resulting in insufficient polysulfone penetration and preventing the acquisition of high membrane peel strength. In addition, the amount of TOC increased due to the increase in unreacted PEG.

[0165] [Table 5]

[0166] [Comparative Example 8-10] Except for changing the copolymerization amount of sodium 5-sulfoisophthalate used in Example 18 as shown in Table 6, the procedure was carried out in the same manner as in Example 18 to obtain a spunbond nonwoven fabric.

[0167] The spunbond nonwoven fabric obtained in Comparative Example 8 did not copolymerize sodium 5-sulfoisophthalate, resulting in a low contact angle and insufficient penetration of polysulfone into the nonwoven fabric. Similarly, the spunbond nonwoven fabric obtained in Comparative Example 9 had a lower sodium 5-sulfoisophthalate content, resulting in a lower contact angle than in Comparative Example 8, but insufficient polysulfone penetration. Furthermore, the spunbond nonwoven fabric obtained in Comparative Example 10 suffered from poor melt-molding properties due to an excessive copolymerization of sodium 5-sulfoisophthalate, leading to frequent yarn breakage during composite spinning with the core component. Increased density resulted in insufficient polysulfone penetration, preventing the acquisition of high film peel strength. Additionally, the generation of decomposition products increased the amount of low-molecular-weight components and thus the TOC content.

[0168] [Comparative Examples 11, 12] Except for changing the copolymerization amount of isophthalic acid used in Example 19 as shown in Table 6, the procedure was carried out in the same manner as in Example 19 to obtain a spunbond nonwoven fabric.

[0169] In Comparative Example 11, the spunbond nonwoven fabric had a low melting point of the sheath component due to an excessive copolymerization of isophthalic acid. This led to a melting point divergence with the core component, causing decomposition of the sheath component and reduced spinnability. The decrease in spinnability resulted in an increase in low-molecular-weight components due to the generation of decomposition products, and thus an increase in TOC. Furthermore, the low melting point of the sheath component caused excessive fusion of fibers during heat sealing, increasing density and resulting in insufficient polysulfone penetration. This reduced the adhesion of the separation membrane and prevented the achievement of high membrane peel strength. In Comparative Example 12, the spunbond nonwoven fabric had a low copolymerization of isophthalic acid and a high melting point of the sheath component, resulting in insufficient fusion during heat sealing. Although polysulfone penetration was achieved due to the low density, the strength as a separation membrane support was low, and high polysulfone membrane peel strength could not be obtained. In addition, the thickness of the nonwoven fabric increased, resulting in a decrease in filtration performance.

[0170] [Comparative Example 13] A spunbond nonwoven fabric was obtained by following the same procedure as in Example 19, except that the core component used was polybutylene terephthalate with a melting point of 220°C and containing 0.3% by weight of titanium dioxide.

[0171] In Comparative Example 13, the spunbond nonwoven fabric had a core component whose melting point was lower than that of the sheath component. As a result, both the core and sheath components fused together during heat sealing, leading to insufficient strength as a separation membrane support. Furthermore, the increased density resulted in insufficient penetration of polysulfone, making it impossible to obtain high membrane peel strength.

[0172] [Table 6]

Claims

1. A spunbond nonwoven fabric containing a core-sheath type composite fiber, the core component being polyester and the sheath component being copolymerized polyester, The melting point of the sheath component is between [(melting point of core component) - 45]°C and [(melting point of core component) - 15]°C. The copolymer component of the aforementioned sheath component is polyethylene glycol copolymerization amount of 2% by mass or more and 15% by mass or less, or / and An isophthalic acid component containing a metal sulfonate group, wherein the copolymerization amount is 2.5 mol% or more and 7.5 mol% or less relative to the total acid component, The contact angle between the surface of the spunbond nonwoven fabric and water is 5° or more and 80° or less. Spunbond nonwoven fabric.

2. The spunbond nonwoven fabric according to claim 1, wherein the sheath component is a copolymerized polyester obtained by copolymerizing polyethylene glycol in an amount of 2% by mass or more and 15% by mass or less, and the contact angle with water on the surface of the spunbond nonwoven fabric is 5° or more and 80° or less.

3. The spunbond nonwoven fabric according to claim 1 or 2, wherein the molecular weight of the polyethylene glycol in the sheath component is 1,000 or more and 35,000 or less.

4. The spunbond nonwoven fabric according to claim 1 or 2, wherein the arithmetic mean roughness of the surface of the spunbond nonwoven fabric is 0.1 μm or more and 10 μm or less.

5. The spunbond nonwoven fabric according to claim 1 or 2, wherein the composite mass ratio of the core component and the sheath component of the core-sheath type composite fiber is 95:5 to 50:

50.

6. The spunbond nonwoven fabric according to claim 1, wherein the sheath component is a copolymerized polyester obtained by copolymerizing a metal sulfonate group-containing isophthalic acid component in an amount of 2.5 mol% to 7.5 mol% or less relative to the total acid component, and the contact angle with water on the surface of the spunbond nonwoven fabric is 5° or more and less than 70°.

7. The density of the spunbond nonwoven fabric is 0.5 g / cm³. ３ ~1.8 g / cm ３ The spunbond nonwoven fabric according to claim 1 or 6.

8. The spunbond nonwoven fabric according to claim 6, wherein the composite mass ratio of the core component and the sheath component of the core-sheath type composite fiber is 90:10 to 60:

40.

9. A separation membrane comprising a spunbond nonwoven fabric according to claim 1 or 2 and a polymer component as constituent elements, A separation membrane in which the polymer component is at least one selected from the group consisting of polysulfone, polyethersulfone, polyarylethersulfone, polyimide, polyvinylidene fluoride, and cellulose acetate, and the penetration rate of the polymer component into the spunbond nonwoven fabric is 5% or more and 70% or less.

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