Oil-water separation sheet and oil-water separation article

Abstract

The present invention addresses the problem of providing an oil-water separation sheet and an oil-water separation article with which oil and water can be separated without requiring suction. The solution involves an oil-water separation sheet characterized by containing fibers having a single fiber diameter of 15.0 μm or less, treated to be water-absorbing and oil-repellent, and having an air permeability of 50 cm3 / cm2 / sec or less. The oil-water separation sheet may be formed into a bag shape as necessary, with water-absorbing fibers enclosed therein to obtain the oil-water separation article.

Description

Oil-water separation sheet and oil-water separation product

[0001] The present invention relates to an oil-water separation sheet and an oil-water separation article that can separate oil and water.

[0002] Traditionally, wastewater from restaurant kitchens and homes has been contaminated with oil and other substances, causing problems such as clogged sewer pipes due to oil buildup and odors due to oxidation of the oil. For this reason, restaurant operators have taken measures such as installing interceptors to separate and collect oils and fats from oil-water mixtures. Furthermore, wastewater from food processing companies and factories can also contain various oils, such as soybean oil, and treatments are carried out to separate the oil from the water to prevent the oil from leaking into rivers, oceans, etc.

[0003] Known techniques for separating oil and water include separation using a flocculant, adsorption separation, centrifugation, pressure flotation separation, coarse particle separation by electrolytic flotation, and separation by microbial decomposition.

[0004] However, separation methods using flocculants have problems with costs, including the recovery of the flocs. Also, methods using centrifugation and pressure flotation, while useful for large public facilities, are not suitable for treating individual wastewater from factories or stores.

[0005] On the other hand, as an oil-water separation filter that can separate water and oil using small equipment at low cost, for example, Patent Document 1 proposes an oil-water separation filter that has both water-repellent and oil-repellent functions.

[0006] However, since such oil-water separation sheets use an oil-water separation membrane that has both water-repellent and oil-repellent properties, they have poor water permeability and require suction.

[0007] Japanese Patent Application Laid-Open No. 2020-138195

[0008] The present invention has been made in consideration of the above background, and its object is to provide an oil-water separation sheet and an oil-water separation product that can separate oil and water without the need for suction.

[0009] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. Thus, the present invention provides the following: 1. An oil-water separating sheet, which contains fibers having a single fiber diameter of 15.0 μm or less, is treated with a water-absorbent and oil-repellent finish, and has an air permeability of 50 cm ３ / cm ２ / sec or less. 2. The oil-water separating sheet according to item 1 above, having a water absorption rate of 60 seconds or less and an oil repellency of 180 seconds or more. 3. An oil-water separating article obtained by forming the oil-water separating sheet according to item 1 or 2 above into a bag shape and enclosing a water-absorbent fiber therein. 4. The oil-water separating article according to item 3 above, wherein the water-absorbent fiber is a crosslinked sodium polyacrylate-based fiber or an acrylate-based fiber obtained by hydrolyzing the surface of an acrylic fiber.

[0010] According to the present invention, it is possible to provide an oil-water separation sheet and an oil-water separation article that can separate oil and water without the need for suction.

[0011] The present invention will be described in detail below with reference to preferred embodiments. First, the oil-water separation sheet of the present invention contains fibers (hereinafter sometimes referred to as "ultrafine fibers") having a single fiber diameter of 15.0 μm or less (preferably 0.1 to 10.0 μm, more preferably 0.1 to 5.0 μm). If the single fiber diameter is greater than 15.0 μm, the oil removal effect may be reduced, which is undesirable.

[0012] The single fiber diameter can be measured by taking a photograph of the cross section of a single fiber at a magnification of 30,000 times using a transmission electron microscope (TEM). In a TEM with a length measurement function, the measurement can be performed using the length measurement function. In a TEM without a length measurement function, the photograph can be enlarged and copied, and the diameter can be measured with a ruler after taking the scale into consideration. When the cross section of a single fiber has a modified cross section other than a circular cross section, the fiber diameter is the diameter of the circumscribed circle of the cross section of the single fiber.

[0013] The ultrafine fibers may be long fibers, but short fibers having an aspect ratio (the ratio L / D of fiber length L to fiber diameter D) of 100 to 2,500 are preferred.

[0014] The type of the ultrafine fiber is not particularly limited, but polyester fiber, polyphenylene sulfide (PPS) fiber, polyolefin fiber, or nylon (Ny) fiber is preferred.

[0015] Preferred polyesters for forming the polyester fibers include polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and copolymers containing these as the main repeating units with aromatic dicarboxylic acids such as isophthalic acid and 5-sulfoisophthalic acid metal salt, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, hydroxycarboxylic acid condensates such as ε-caprolactone, and glycol components such as diethylene glycol, trimethylene glycol, tetramethylene glycol, and hexamethylene glycol. Material- or chemically recycled polyesters and polyethylene terephthalate obtained using monomer components derived from biomass, i.e., biologically derived materials, as described in JP-A-2009-091694, are also suitable. Furthermore, polyesters obtained using catalysts containing specific phosphorus compounds and titanium compounds, as described in JP-A-2004-270097 and JP-A-2004-211268, are also suitable.

[0016] The polyarylene sulfide resin forming the polyphenylene sulfide (PPS) fibers may be any resin that falls within the category known as a polyarylene sulfide resin. Examples of polyarylene sulfide resins include those composed of structural units such as p-phenylene sulfide units, m-phenylene sulfide units, o-phenylene sulfide units, phenylene sulfone units, phenylene sulfide ketone units, phenylene sulfide ether units, diphenylene sulfide units, substituted phenylene sulfide units, and branched phenylene sulfide units. Among these, those containing 70 mol % or more, particularly 90 mol % or more, of p-phenylene sulfide units are preferred, with poly(p-phenylene sulfide) being even more preferred.

[0017] Polyolefin fibers include polypropylene fibers and polyethylene fibers, and nylon fibers include nylon 6 fibers and nylon 66 fibers.

[0018] The method for producing the ultrafine fibers is not particularly limited, but the method disclosed in WO 2005 / 095686 is preferred. That is, in terms of fiber diameter and uniformity, it is preferred to use a composite fiber having island components made of a fiber-forming thermoplastic polymer and a sea component made of a polymer that is more easily soluble in an alkaline aqueous solution than the fiber-forming thermoplastic polymer (hereinafter, also referred to as "easily soluble polymer"), which is subjected to an alkali weight reduction process to dissolve and remove the sea component.

[0019] The oil-water separation sheet of the present invention may contain binder fibers. Such binder fibers are preferably composite fibers or unstretched fibers. In the case of unstretched fibers, the birefringence Δn is usually 0.05 or less. Furthermore, the elongation of the unstretched fibers is usually 100% or more (preferably 100 to 800%).

[0020] Here, the composite fiber is preferably a core-sheath type composite fiber in which a polymer component (e.g., amorphous copolymer polyester) that fuses and exhibits an adhesive effect by heat treatment at 80 to 170°C after papermaking is arranged in the sheath, and another polymer (e.g., ordinary polyester such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate) whose melting point is 20°C or more higher than that of the polymer is arranged in the core.

[0021] The binder fiber may be a known binder fiber in which a binder component (low-melting point component) forms all or part of the surface of a single fiber, such as a core-sheath type composite fiber, an eccentric core-sheath type composite fiber, or a side-by-side type composite fiber.

[0022] The amorphous copolyesters are obtained as random or block copolymers of acid components such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, adipic acid, sebacic acid, azelaic acid, dodecanoic acid, and 1,4-cyclohexanedicarboxylic acid with diol components such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. Among these, the use of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol as the main components, which have been widely used in the past, is preferred from a cost perspective. Such copolyesters have glass transition temperatures in the range of 50 to 100°C and do not exhibit a clear crystalline melting point.

[0023] The undrawn fibers include undrawn fibers spun at a spinning speed of preferably 800 to 1500 m / min (more preferably 900 to 1150 m / min). Here, the undrawn fibers are preferably undrawn fibers using, as at least one component, the polyester used for the island or sea component of the islands-in-sea composite fiber. Particularly preferred are undrawn polyester fibers using, as at least one component, a polyester such as polyethylene terephthalate, polytrimethylene terephthalate, or polybutylene terephthalate; undrawn polyphenylene sulfide (PPS) binder fibers using, as at least one component, polyphenylene sulfide (PPS); undrawn nylon fibers using, as at least one component, nylon such as nylon 6 or nylon 66; and undrawn polyolefin fibers using, as at least one component, a polyolefin such as polypropylene or polyethylene. Undrawn yarns of islands-in-sea composite fibers may also be used.

[0024] The polyarylene sulfide resin forming the unstretched polyphenylene sulfide (PPS) binder fiber may be any polyarylene sulfide resin, as long as it belongs to the category known as a polyarylene sulfide resin. Examples of polyarylene sulfide resins include those composed of constituent units such as p-phenylene sulfide units, m-phenylene sulfide units, o-phenylene sulfide units, phenylene sulfone units, phenylene sulfide ketone units, phenylene sulfide ether units, diphenylene sulfide units, substituted phenylene sulfide units, and branched phenylene sulfide units. Among these, those containing 70 mol % or more, particularly 90 mol % or more, of p-phenylene sulfide units are preferred, and poly(p-phenylene sulfide) is even more preferred.

[0025] The oil-water separation sheet of the present invention may be a woven or knitted fabric, but a nonwoven fabric is preferred in terms of oil and water separation. Examples of such nonwoven fabrics include wet-laid nonwoven fabrics, spunlace, airlaid, needle-punched, thermally bonded, and chemically bonded nonwoven fabrics. The sheet may also have a multilayer structure in which two or more layers are laminated. Examples of bonding methods include thermal bonding, chemical bonding, and sewing.

[0026] Next, in the oil-water separating sheet of the present invention, the sheet (substrate) is subjected to a water-absorbing and oil-repellent treatment. In other words, a water-absorbing and oil-repellent agent is applied. As such a water-absorbing and oil-repellent treatment, the treatment described in WO 2012 / 147582 is preferred. That is, (a) a compound represented by the general formula: CH2=C(-X)-C(=O)-Y-[-(CH2) m -Z-] p -(CH2) n -Rf (I) [wherein X is a hydrogen atom, a methyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a CFX1X2 group (wherein X1 and X2 are a hydrogen atom, a fluorine atom, or a chlorine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group; Y is -O- or -NH-; Z is a direct bond, -S-, or -SO２ -, Rf is a fluoroalkyl group having 1 to 12 carbon atoms, m is 1 to 10, n is 0 to 10, and p is 0 or 1.], and (b) a fluorine-containing monomer represented by the general formula: CH2=C(X')-C(=O)-O-(RO) q -H (II) [wherein X' is a hydrogen atom or a methyl group, R is an alkylene group having 2 to 4 carbon atoms in which some or all of the hydrogen atoms may be substituted with hydroxyl groups, and q is an integer of 1 to 50] is preferred.

[0027] Such fluorine-containing polymers have excellent oil repellency and water absorbency, and can impart oil repellency and water absorbency to fabrics.

[0028] The fluorine-containing monomer (a) is represented by the general formula: CH2=C(-X)-C(=O)-Y-[-(CH2) m -Z-] p -(CH2) n -Rf (I) [wherein X is a hydrogen atom, a methyl group, a linear or branched alkyl group having 1 to 21 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a CFX1X2 group (wherein X1 and X2 are a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group; Y is -O- or -NH-; Z is a direct bond, -S-, or -SO ２ -, Rf is a fluoroalkyl group having 1 to 12 carbon atoms, m is 1 to 10, n is 0 to 10, and p is 0 or 1. In general formula (I), p is preferably 0. A preferred example of X is a hydrogen atom.

[0029] In the fluorine-containing monomer (a), the Rf group is generally a perfluoroalkyl group and / or a partially fluorinated fluoroalkyl group. The Rf group is preferably a perfluoroalkyl group. The Rf group has 1 to 12 carbon atoms (preferably 1 to 6 carbon atoms). Examples of the Rf group include -CF3, -CF2CF3, -CF2CF2CF3, -CF(CF3)2, -CF2CF2CF2CF3, -CF2CF(CF3)2, -C(CF ３ )3, -(CF2)4CF3, -(CF2)2CF(CF3)2, -CF2C(CF3)3, -CF(CF3)CF2CF2CF3, -(CF2)5CF3, etc.

[0030] m is 1 to 10, for example, 2 to 5, and n is 0 to 10, for example, 1 to 6, particularly preferably 2 to 5.

[0031] The fluorine-containing monomer (a) may be used singly or in combination of two or more kinds.

[0032] Examples of the fluorine-containing monomer (a) include the following: CH2=C(-X)-C(=O)-O-(CH2) m -S-(CH2) n -Rf CH2=C(-X)-C(=O)-O-(CH2) m -SO2-(CH2) n -Rf CH2=C(-X)-C(=O)-O-(CH2) n -Rf CH2=C(-X)-C(=O)-NH-(CH2) n -Rf [In the above formula, X represents a hydrogen atom, a methyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a CFX1X2 group (wherein X1 and X2 represent a hydrogen atom, a fluorine atom or a chlorine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group; Rf represents a fluoroalkyl group having 1 to 6 carbon atoms; m represents 1 to 10; and n represents 0 to 10.] Specific examples of the fluorine-containing monomer (a) include, but are not limited to, the following:

[0033] CH2=C(-H)-C(=O)-O-(CH2)2-S-Rf CH2=C(-H)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-H)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-H)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-H)-C(=O)-O-(CH2)2-Rf CH2=C(-H)-C(=O)-NH-(CH2)2-Rf CH2=C(-H)-C(=O)-OCH2CH2N(C2H5)SO2-Rf CH2=C(-H)-C(=O)-OCH2CH2N(CH3)SO2-Rf CH2=C(-H)-C(=O)-OCH2CH(OCOCH3)CH2-Rf CH2=C(-CH3)-C(=O)-O-(CH2)2-S-Rf CH2=C(-CH3)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-CH3)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-CH3)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-CH3)-C(=O)-O-(CH2)2-Rf CH2=C(-CH3)-C(=O)-NH-(CH2)2-Rf CH2=C(-CH3)-C(=O)-OCH2CH2N(C2H5)SO2-Rf CH2=C(-CH3)-C(=O)-OCH2CH2N(CH3)SO2-Rf CH2=C(-CH3)-C(=O)-OCH2CH(OCOCH3)CH2-Rf CH2=C(-F)-C(=O)-O-(CH2)2-S-Rf CH2=C(-F)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-F)-C(=O)-O-(CH2)2-SO2-Rf CH2=C(-F)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-F)-C(=O)-O-(CH2)2-Rf CH2=C(-F)-C(=O)-NH-(CH2)2-Rf CH2=C(-Cl)-C(=O)-O-(CH2)2-S-Rf CH2=C(-Cl)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-Cl)-C(=O)-O-(CH2)2-SO2-RfCH2=C(-Cl)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-Cl)-C(=O)-O-(CH2)2-Rf CH2=C(-Cl)-C(=O)-NH-(CH2)2-Rf CH2=C(-CF3)-C(=O)-O-(CH2)2-S-Rf CH2=C(-CF3)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-CF3)-C(=O)-O-(CH2)2-SO2-Rf CH2=C(-CF3)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-CF3)-C(=O)-O-(CH2)2-Rf CH2=C(-CF3)-C(=O)-NH-(CH2)2-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)2-S-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)2-SO2-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)2-Rf CH2=C(-CF2H)-C(=O)-NH-(CH2)2-Rf CH2=C(-CN)-C(=O)-O-(CH2)2-S-Rf CH2=C(-CN)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-CN)-C(=O)-O-(CH2)2-SO2-Rf CH2=C(-CN)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-CN)-C(=O)-O-(CH2)2-Rf CH2=C(-CN)-C(=O)-NH-(CH2)2-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)2-S-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)2-S-(CH2)2-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)2-SO2-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)2-Rf CH2=C(-CF2CF3)-C(=O)-NH-(CH2)2-RfCH2=C(-F)-C(=O)-O-(CH2)3-S-Rf CH2=C(-F)-C(=O)-O-(CH2)3-S-(CH2)2-Rf CH2=C(-F)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-F)-C(=O)-O-(CH2)3-SO2-(CH2)2-Rf CH2=C(-F)-C(=O)-O-(CH2)3-Rf CH2=C(-F)-C(=O)-NH-(CH2)3-Rf CH2=C(-Cl)-C(=O)-O-(CH2)3-S-Rf CH2=C(-Cl)-C(=O)-O-(CH2)3-S-(CH2)2-Rf CH2=C(-Cl)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-Cl)-C(=O)-O-(CH2)3-SO2-(CH2)2-Rf CH2=C(-CF3)-C(=O)-O-(CH2)3-S-Rf CH2=C(-CF3)-C(=O)-O-(CH2)3-S-(CH2)2-Rf CH2=C(-CF3)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-CF3)-C(=O)-O-(CH2)3-SO2-(CH2)2-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)3-S-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)3-S-(CH2)2-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-CF2H)-C(=O)-O-(CH2)3-SO2-(CH2)2-Rf CH2=C(-CN)-C(=O)-O-(CH2)3-S-Rf CH2=C(-CN)-C(=O)-O-(CH2)3-S-(CH2)2-Rf CH2=C(-CN)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-CN)-C(=O)-O-(CH2)3-SO2-(CH2)2-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)3-S-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)3-S-(CH2)2-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)3-SO2-Rf CH2=C(-CF2CF3)-C(=O)-O-(CH2)2-SO2-(CH2)2-Rf[In the above formula, Rf is a fluoroalkyl group having a carbon number of 1 to 6.] The alkoxy group-containing monomer (b) is a non-fluorine-containing monomer and has the general formula: (b) General formula: CH2=C(X')-C(=O)-O-(RO) q -H (II) [wherein X' is a hydrogen atom or a methyl group, R is an alkylene group having 2 to 4 carbon atoms in which some or all of the hydrogen atoms may be substituted with hydroxyl groups, and q is an integer of 1 to 50].

[0034] In the alkoxy group-containing monomer (b), q is preferably 1 to 30, for example, 2 to 10, and particularly preferably 2 to 5.

[0035] In general formula (II), R is preferably ethylene or propylene, particularly ethylene. R in general formula (II) may be a combination of two or more alkylene groups. In this case, it is preferable that at least one of R is ethylene. Examples of combinations of R include a combination of an ethylene group / propylene group and a combination of an ethylene group / butylene group.

[0036] The alkoxy group-containing monomer (b) may be a mixture of two or more types. Specific examples of the alkoxy group-containing monomer (b) include, but are not limited to, the following:

[0037] CH2=CHCOO-(CH2CH2O)9-H CH2=C(CH3)COO-(CH2CH2O)9-H CH2=C(CH3)COO-(CH2CH2O) 23 -H CH2=C(CH3)COO-(CH2CH2O) 50-H CH2=C(CH3)COO-(CH2CH(CH3)O)9-H CH2=CHCOO-(CH2CH(CH3)O)9-H CH2=C(CH3)COO-(CH2CH(CH3)O)9-H CH2=C(CH3)COO-(CH2CH(CH3)O)9-H CH2=C(CH3)COO-(CH2CHO)5-(CH2CH(CH3)O)2-H CH2=C(CH3)COO-(CH2CHO)8-(CH2CH(CH3)O)6-H The fluorine-based polymer may include (c) a crosslinkable monomer. The crosslinkable monomer (c) may be a compound having at least two reactive groups and / or carbon-carbon double bonds and not containing fluorine. The crosslinkable monomer (c) may be a compound having at least two carbon-carbon double bonds, or a compound having at least one carbon-carbon double bond and at least one reactive group. Examples of reactive groups include a hydroxyl group, an epoxy group, a chloromethyl group, a blocked isocyanate group, and a carboxyl group.

[0038] The crosslinkable monomer (c) is preferably a non-fluorine-containing crosslinkable monomer, and is particularly preferably a di(meth)acrylate.

[0039] The crosslinking monomer (c) has the general formula: CH2=C(X")-C(=O)-O-(R"O) q -C(=O)-C(X")=CH2 (III) [wherein each X" is a hydrogen atom or a methyl group; R" is an alkylene group having 2 to 10 carbon atoms in which some or all of the hydrogen atoms may be substituted with hydroxyl groups, and q is an integer of 1 to 50] is preferred. The number of carbon atoms in R" is 2 to 10, for example, 2 to 6, and particularly 2 to 4. R" is preferably an ethylene group.

[0040] Specific examples of the alkylene glycol di(meth)acrylate represented by formula (III) are as follows:

[0041] CH2=C(CH3)COO-(CH2CH2O)5-COC(CH3)=CH2 CH2=CHCOO-(CH2CH2O)9-COCH=CH2 CH2=C(CH3)COO-(CH2CH(CH3)O)12 -COCH=CH2 CH2=CHCOO-(CH2CH2O)5-(CH2CH(CH3)O)3-COCH=CH2 CH2=C(CH3)COO-(CH2CH2O) 23 -OOC(CH3)C=CH2 CH2=C(CH3)COO-(CH2CH2O) 20 -(CH2CH(CH3)O)5-COCH=CH2 Other examples of the crosslinkable monomer (c) include, but are not limited to, diacetone (meth)acrylamide, (meth)acrylamide, N-methylol (meth)acrylamide, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, butadiene, chloroprene, glycidyl (meth)acrylate, 1,6-hexanediol acrylate, and neopentyl glycol diacrylate.

[0042] Further examples of the crosslinkable monomer (c) include isocyanate group-containing (meth)acrylates such as glycerol (meth)acrylate, acetoacetoxyethyl (meth)acrylate, and 2-isocyanatoethyl methacrylate, or (meth)acrylates thereof in which the isocyanate group is blocked with a blocking agent such as methyl ethyl ketoxime, etc. The crosslinkable monomer (c) may be a mixture of two or more types.

[0043] The fluorine-based polymer may contain (d) a non-crosslinkable monomer. The non-crosslinkable monomer (d) is a monomer other than the alkoxy group-containing monomer (b), and is generally a non-fluorine-containing monomer. The non-crosslinkable monomer (d) is preferably a monomer that does not contain fluorine and has a carbon-carbon double bond. The non-crosslinkable monomer (d) is preferably a vinyl monomer that does not contain fluorine. The non-crosslinkable monomer is generally a compound that has one carbon-carbon double bond.

[0044] Examples of the non-crosslinkable monomer (d) include, but are not limited to, butadiene, chloroprene, maleic acid derivatives, vinyl halides such as vinyl chloride, ethylene, vinylidene halides such as vinylidene chloride, vinyl alkyl ether, styrene, alkyl (meth)acrylate, and vinylpyrrolidone.

[0045] The non-crosslinkable monomer (d) may be a (meth)acrylic acid ester containing an alkyl group. The number of carbon atoms in the alkyl group may be 1 to 30, for example, 6 to 30, for example, 10 to 30. For example, the non-crosslinkable monomer may be a (meth)acrylic acid ester having the general formula: CH ２ = CA １ COOA ２ [In the formula, A １ is a hydrogen atom or a methyl group, A ２ is C ｎ H ２ｎ＋１ (n=1 to 30) is an alkyl group.]

[0046] The fluorine-containing polymer contains 100 parts by weight of a fluorine-containing monomer (a). Preferably, relative to 100 parts by weight of the fluorine-containing monomer (a), the amount of the alkoxy group-containing monomer (b) is 10 to 400 parts by weight, for example, 25 to 150 parts by weight, and particularly 100 to 43 parts by weight, the amount of the crosslinkable monomer (c) is 30 parts by weight or less, for example, 0.1 to 20 parts by weight, and particularly 0.5 to 10 parts by weight, and the amount of the non-crosslinkable monomer (d) is 20 parts by weight or less, for example, 0.1 to 15 parts by weight, and particularly 0.5 to 10 parts by weight.

[0047] The weight average molecular weight of the fluorine-containing polymer may be 1,000 to 1,000,000, preferably 5,000 to 500,000. The weight average molecular weight is a value determined by gel permeation chromatography in terms of polystyrene.

[0048] The polymerization of the fluorine-containing polymer is not particularly limited, and various polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization, and radiation polymerization can be selected. For example, solution polymerization using an organic solvent or emulsion polymerization using water or a combination of an organic solvent and water is generally selected. After polymerization, the polymer is diluted with water or emulsified in water by adding an emulsifier to prepare a treatment liquid.

[0049] The state of the fluorine-containing polymer before being applied to a fabric is preferably such that after polymerization (for example, solution polymerization or emulsion polymerization), the solvent is removed and water is added to disperse the polymer in water.

[0050] Examples of organic solvents include ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and methyl acetate, glycols such as propylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol, tripropylene glycol and low-molecular-weight polyethylene glycol, and alcohols such as ethyl alcohol and isopropanol.

[0051] When an emulsifier is added for emulsion polymerization or after polymerization to emulsify in water, various common anionic, cationic and nonionic emulsifiers can be used.

[0052] As the polymerization initiator, for example, peroxides, azo compounds or persulfate compounds can be used. The polymerization initiator is generally water-soluble and / or oil-soluble.

[0053] Specific preferred examples of the oil-soluble polymerization initiator include 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-isobutyronitrile), benzoyl peroxide, di-tert-butyl peroxide, lauryl peroxide, cumene hydroperoxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, and t-butyl perpivalate.

[0054] Specific preferred examples of the water-soluble polymerization initiator include 2,2'-azobisisobutylamidine dihydrochloride, 2,2'-azobis(2-methylpropionamidine) hydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane]hydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane]sulfate hydrate, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]hydrochloride, potassium persulfate, barium persulfate, ammonium persulfate, and hydrogen peroxide.

[0055] The polymerization initiator is preferably an organic peroxide having a 10-hour half-life temperature of 40° C. or higher. The polymerization initiator is particularly preferably t-butyl peroxypivalate.

[0056] The polymerization initiator is used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the monomer.

[0057] Furthermore, for the purpose of molecular weight control, a chain transfer agent such as a mercapto group-containing compound may be used, specific examples of which include 2-mercaptoethanol, thiopropionic acid, alkyl mercaptan, etc. The mercapto group-containing compound is used in an amount of 10 parts by weight or less, in the range of 0.01 to 5 parts by weight, per 100 parts by weight of the monomer.

[0058] Specifically, the fluorine-containing polymer can be produced as follows. In solution polymerization, a monomer is dissolved in an organic solvent, and after nitrogen substitution, a polymerization initiator is added and the mixture is heated and stirred at a temperature in the range of 40 to 120°C for 1 to 10 hours. The polymerization initiator may generally be an oil-soluble polymerization initiator.

[0059] The organic solvent is one that is inert to the monomers and dissolves them, and examples thereof include acetone, chloroform, HCHC225, isopropyl alcohol, pentane, hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, petroleum ether, tetrahydrofuran, 1,4-dioxane, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane, trichloroethylene, perchloroethylene, tetrachlorodifluoroethane, trichlorotrifluoroethane, etc. The organic solvent is used in an amount of 50 to 2000 parts by weight, for example, 50 to 1000 parts by weight, per 100 parts by weight of the total of the monomers.

[0060] Emulsion polymerization involves emulsifying the monomers in water in the presence of an emulsifier or the like, replacing the atmosphere with nitrogen, adding a polymerization initiator, and polymerizing the mixture at 40 to 80°C for 1 to 10 hours with stirring. Examples of polymerization initiators that can be used include water-soluble initiators such as benzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, 1-hydroxycyclohexyl hydroperoxide, 3-carboxypropionyl peroxide, acetyl peroxide, azobisisobutylamidine dihydrochloride, azobisisobutyronitrile, sodium peroxide, potassium persulfate, and ammonium persulfate, as well as oil-soluble initiators such as azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, lauryl peroxide, cumene hydroperoxide, t-butyl peroxypivalate, and diisopropyl peroxydicarbonate. The polymerization initiator is used in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the monomers.

[0061] To obtain a polymer aqueous dispersion with excellent shelf stability, it is desirable to atomize the monomer in water using an emulsifying device capable of applying powerful crushing energy, such as a high-pressure homogenizer or ultrasonic homogenizer, and then polymerize using an oil-soluble polymerization initiator. Furthermore, various anionic, cationic, or nonionic emulsifiers can be used as emulsifiers, and are used in a range of 0.5 to 20 parts by weight per 100 parts by weight of monomer. It is preferable to use anionic and / or nonionic and / or cationic emulsifiers. If the monomers are not completely compatible, it is preferable to add a compatibilizer, such as a water-soluble organic solvent or a low-molecular-weight monomer, that will fully compatibilize these monomers. Adding a compatibilizer can improve emulsifiability and copolymerizability.

[0062] Examples of water-soluble organic solvents include acetone, methyl ethyl ketone, ethyl acetate, propylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol, tripropylene glycol, and ethanol, which may be used in an amount of 1 to 50 parts by weight, for example, 10 to 40 parts by weight, per 100 parts by weight of water. Examples of low-molecular-weight monomers include methyl methacrylate, glycidyl methacrylate, and 2,2,2-trifluoroethyl methacrylate, which may be used in an amount of 1 to 50 parts by weight, for example, 10 to 40 parts by weight, per 100 parts by weight of the total amount of monomers.

[0063] The treatment liquid containing the fluorine-containing polymer is preferably in the form of a solution, emulsion, or aerosol. The treatment liquid contains the fluorine-containing polymer and a medium (e.g., a liquid medium such as an organic solvent or water). The concentration of the fluorine-containing polymer in the treatment liquid may be, for example, 0.01 to 50 wt %.

[0064] Here, when the treatment solution contains a quaternary ammonium salt and the fluorine-containing polymer is attached to the sheet together with the quaternary ammonium salt, the cationic nature of the fluorine-containing polymer increases due to the ionic effect of the quaternary ammonium salt. As a result, when the organic fiber constituting the sheet is polyester fiber, the fluorine-containing polymer easily adheres to the anionically charged polyester fiber, which is preferable because it further improves oil repellency and water absorbency. Furthermore, since quaternary ammonium salts usually have antibacterial properties, antibacterial properties are imparted to the fabric.

[0065] As such quaternary ammonium salts, the following are preferably used.

[0066]

[0067] Furthermore, when the treatment liquid contains a binder resin and the fluorine-containing polymer is adhered to the sheet together with the binder resin, the fluorine-containing polymer adheres firmly to the fibers, which is preferable because it improves durability of oil repellency, water absorbency, antibacterial properties, etc.

[0068] In this case, a melamine binder resin is preferably used as the binder resin. When a melamine binder resin is used as the binder resin, the solubility parameter SP value of the melamine binder resin is close to that of polyester fiber. Therefore, when the fibers constituting the sheet are polyester fiber, the fluorine-containing polymer adheres to the polyester fiber filament in the form of a film. As a result, not only are durability such as oil repellency, water absorbency, and antibacterial properties improved, but the softness of the sheet is also improved, which is preferable.

[0069] Here, when a silicone binder resin is used as the binder resin, the water absorbency of the fabric may be impaired due to the hydrophobicity of the silicone binder resin. Furthermore, when an isocyanate binder resin is used as the binder resin, durability such as oil repellency, stain removal by washing, water absorbency, and antibacterial properties may be reduced, and cyan gas may be generated. Furthermore, when an acrylic binder resin is used as the binder resin, durability such as oil repellency, water absorbency, and antibacterial properties may be reduced due to the lack of crosslinking properties of the acrylic binder resin.

[0070] The treatment solution can be applied to a sheet by a conventionally known method. Typically, the treatment solution is dispersed and diluted in an organic solvent or water, and then applied to the surface of the object to be treated by a known method such as dip coating, spray coating, or foam coating, followed by drying (surface treatment). In the case of surface treatment, the proportion of the fluorine-containing polymer relative to the weight of the fabric may be 0.01 to 3.0 wt % (more preferably 0.5 to 2.0 wt %).

[0071] Furthermore, as described above, when the fluorine-containing polymer having a concentration of perfluorooctanoic acid and / or perfluorooctanesulfonic acid of 5 ng / g or less is attached to the sheet, it is environmentally friendly.

[0072] Furthermore, when a fluorine-containing polymer is attached to the sheet together with a quaternary ammonium salt, not only is the oil repellency and water absorbency further improved, but the sheet also has antibacterial properties.

[0073] The oil-water separation sheet thus obtained has the above-mentioned structure, and therefore can separate oil and water without the need for suction. ３ / cm ２ / sec or less (more preferably 0.1 to 40 cm ３ / cm ２ / sec). ３ / cm ２ If the time exceeds 1 / sec, the performance of separating oil and water may be reduced.

[0074] The water absorption of the oil-water separation sheet is preferably measured by the JIS L1907 water absorption rate method (drop method) and is 60 seconds or less. As for oil repellency, 40 μL of n-hexadecane is dropped from a height of 5 cm from the sheet, and the sheet is visually inspected for permeability. It is preferable that the sheet does not permeate for 180 seconds or more.

[0075] The oil-water separation sheet thus obtained may have a multi-layer structure of, for example, two or more layers, and the single fiber diameters of the constituent fibers of each layer may be different from each other. The layer with the smaller single fiber diameter (ultrafine fiber layer) may be arranged on the inlet side in the discharge path through which the oil-water mixture liquid is discharged, thereby effectively separating the water and oil from the oil-water mixture liquid.

[0076] Here, in the case of oil-water separation, solids are mixed in the oil-water mixture, and there is a concern that the solids will be captured in the ultrafine fiber layer, resulting in an increase in filtration pressure. In such a case, it is preferable to place a sheet for capturing solids in front of the inflow side of the oil-water separation sheet.

[0077] The shape of the oil-water separation sheet is not limited to a flat plate, and may be any shape, such as a corrugated one. Furthermore, it may be treated with known functional finishes, such as water repellency, flame retardancy, flame retardancy, dyeing, or negative ion generation. Such an oil-water separation sheet is useful as a filter sheet for separating water and oil in oily water containing up to 10% (more preferably up to 5%) of water, or conversely, in oily water containing up to a few percent of oil. Specifically, it is particularly suitable for applications such as removing water from oil tanks.

[0078] The oil-water separation article of the present invention is formed by forming the oil-water separation sheet into a bag shape and enclosing a water-absorbent fiber therein. This oil-water separation article is useful when a large amount of water is mixed with oil, for example, when the water / oil mixture ratio is 30 / 70 by weight.

[0079] Here, the absorbent fiber is a fiber with water absorption and swelling properties that combines the functions of a fiber and a superabsorbent polymer, and preferably has a water absorption capacity of 20 times or more (more preferably 40 to 100 times) its own weight. If the water absorption capacity is less than 20 times, the water absorption capacity will be low and the degree of swelling will be reduced, which may reduce the effectiveness of preventing leakage to the outside. Absorbent fibers with a water absorption capacity of 20 times or more their own weight are not particularly limited, but examples include superabsorbent polymers obtained by crosslinking polymers such as starch grafts, polyacrylic acid, and polyvinyl alcohol, as well as absorbent fibers spun from superabsorbent polymers such as thermoplastic absorbent polymers containing polyalkylene oxide units. Crosslinked sodium polyacrylate fibers or acrylate fibers obtained by hydrolyzing the surface of acrylic fibers are particularly preferred. Superabsorbent polymers can absorb and retain water from several hundred to approximately 1,000 times their own weight. In particular, acrylic acid polymers have a high hydrophilicity due to their large number of carboxyl groups, and when crosslinked into a network structure and converted into the sodium salt form, they become a highly absorbent gel, which is known to exhibit excellent properties.

[0080] Such an oil-water separation product can separate oil and water without the need for suction. For example, by immersing a sample of the product in oil containing water, it is possible to selectively remove only the water.

[0081] The oil-water separation sheet of the present invention will be described in detail below with reference to examples. The following evaluations were carried out for the examples and comparative examples. (1) Single fiber diameter: Cross-sectional photographs of single fibers were taken and measured using a transmission electron microscope (TEM) at a magnification of 30,000 times, and the average was calculated for five samples. (2) Porosity: The value was calculated using the following formula from the basis weight, thickness, and resin density, and the obtained value was rounded to the nearest tenth to determine the porosity. Porosity (%) = 100 - (basis weight (g / m ２ ) x 100 / resin density (g / cm ３) / thickness (mm) / 1000) (3) Breathability Breathability was measured using the JIS L1096A method (Fragile method). (4) Water absorption (hydrophilicity) The water absorption of the oil-water separation sheet was measured using the JIS L1907 water absorption rate method (drop method). The evaluation results were defined as follows. A: After dripping droplets onto the oil-water separation filter material, they penetrated within 60 seconds. B: After dripping droplets onto the oil-water separation filter material, they penetrated between 60 and 180 seconds. C: After dripping droplets onto the oil-water separation filter material, they did not penetrate for 180 seconds or more. (5) Oil repellency 40 μL of n-hexadecane was dropped onto the oil-water separation sheet from a height of 5 cm from the sheet, and the permeability was visually determined based on the following definition to evaluate the oil repellency. A: After dripping droplets onto the oil-water separation filter material, they did not penetrate for 180 seconds or more. B: After dripping droplets onto the oil-water separation filter material, penetration occurred within 60 seconds but not more than 180 seconds. C: After dripping droplets onto the oil-water separation filter material, penetration occurred within 60 seconds. (6) Adaptability for removing water from oil The adaptability for removing water from oil was evaluated based on the water absorbency and oil repellency. When both water absorbency and oil repellency were rated as A, it was rated as "○" (good), when only one of water absorbency and oil repellency was rated as A, it was rated as "△" (fair), and when both water absorbency and oil repellency were B or C, it was rated as "×" (poor). (7) Penetration of emulsified solution On the prepared oil-water separation sheet, n-hexadecane and water were mixed in a weight ratio of 6:1 from a height of 5 cm from the sheet, thoroughly stirred, and after confirming that the solution was in a suspended state, 40 μL of the solution was dropped, and the penetration was visually observed, and the water absorbency and oil repellency were evaluated in the same manner as above. When both the water absorbency and oil repellency were rated as A, it was rated as "○" (good), when either the water absorbency or oil repellency was rated as C, it was rated as "×" (bad), and otherwise it was rated as B (fair). (8) Basis Weight and Thickness Measured according to JIS L1096.

[0082] Example 1 A 100 ml four-neck flask equipped with a reflux condenser, a nitrogen inlet tube, a thermometer, and a stirrer was charged with a fluorine-containing monomer CH2=CHC(=O)O-CH2CH2C6F 13A mixture of 18.6 g of the above, 11.4 g of polyethylene glycol acrylate CH2=CHC(=O)O-(CH2CHO)n-H (BLEMMER AE90, NOF Corporation, where the average value of n is 2, hereinafter referred to as AE90(b)), 0.3 g of 2-mercaptoethanol, and 45 g of methyl ethyl ketone (hereinafter referred to as MEK) was added and subjected to nitrogen bubbling for 30 minutes. After the internal temperature was raised from room temperature to 50-65°C under a nitrogen stream, 0.4 g of Perbutyl PV (hereinafter referred to as PV) was added and the reaction was carried out at 60-65°C for 6 hours. The MEK was distilled off from the resulting solution at approximately 70°C under reduced pressure to obtain a pale yellow polymer residue. 122.4 g of water was added, the internal temperature was maintained at approximately 80°C for at least 1 hour, and then the mixture was cooled to prepare an aqueous dispersion of fluorine-based compounds with a solids concentration of approximately 20% by weight.

[0083] Next, a treatment liquid was obtained containing 5 wt % (based on the weight of the treatment liquid) of the aqueous dispersion, 0.5 wt % (based on the weight of the treatment liquid) of melamine binder resin, 0.1 wt % (based on the weight of the treatment liquid) of catalyst, and 94.4 wt % (based on the weight of the treatment liquid) of ion-exchanged water.

[0084] On the other hand, crimped staple fibers (single fiber fineness 2.2 dtex, single fiber diameter 14 μm, fiber length 51 mm) made of polyethylene terephthalate (PET) and core-sheath composite thermal adhesive staple fibers (core / sheath = 50 / 50, core: polyethylene terephthalate with a melting point of 256°C, sheath: copolymer polyester with a softening point of 110°C and mainly composed of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol) were blended in a blending ratio of 80 / 20 (wt%) and passed through a carding machine, then heat-treated for 5 minutes in a hot air circulation dryer at 140°C to obtain a fabric with a basis weight of 50 g / m. ２In addition, nanofiber fiber A (polyester fiber) having a fiber diameter of 700 nm and a length of 0.5 mm, binder fiber B (core / sheath = 50 / 50, core: polyethylene terephthalate with a melting point of 256°C, sheath: amorphous copolymer polyester mainly composed of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol) which is a core-sheath composite type heat-fusible fiber having a single fiber fineness of 2.2 dtex (single fiber diameter of 14.3 μm) and a length of 5 mm, and fiber C (polyester fiber) having a single fiber fineness of 0.6 dtex (single fiber diameter of 7.5 μm) and a length of 5 mm were blended in a ratio of A:B:C = 30:30:40 and dispersed in water to form a slurry, which was then subjected to a wet papermaking process to prepare a nonwoven fabric having a basis weight of 20 g / m. ２ A wet-laid nonwoven fabric of this size was obtained.

[0085] The two resulting nonwoven fabrics were bonded together with spray adhesive to obtain the substrates shown in Table 1. The bonded substrates were then immersed in the treatment liquid, wrung out to a wringing rate of 100%, and then dried at 130°C for 5 minutes and then at 180°C for 1 minute to obtain oil-water separation sheets. The proportion of the fluorine-containing polymer in the oil-water separation sheet was 1% by weight.

[0086] Water and oil were dropped onto the oil-water separation sheet to evaluate its water absorbency and oil repellency, as well as the permeability of the emulsion of water and oil. The evaluation results are shown in Table 1. The oil-water separation sheet was then formed into a bag, and water-absorbent fibers were enclosed within to obtain an oil-water separation product. The absorbent fibers used were "Belloasis" (trade name) manufactured by Teijin Frontier Co., Ltd. (crosslinked sodium polyacrylate fiber, water absorption rate (50 times its own weight), single fiber fineness 10 dtex, fiber length 5 mm). It was confirmed that the oil-water separation product selectively removed only water by immersing it in oil mixed with water. Furthermore, it was confirmed that the product selectively removed only water even when the water and oil were thoroughly stirred and emulsified.

[0087] [Example 2] Instead of the wetlaid nonwoven fabric in Example 1, crimped staple fibers (single fiber fineness 2.2 dtex, single fiber diameter 14 μm, fiber length 51 mm) made of polyethylene terephthalate (PET) and core-sheath composite thermal adhesive staple fibers (core / sheath = 50 / 50, core: polyethylene terephthalate with a melting point of 256°C, sheath: copolymer polyester with a softening point of 110°C and mainly composed of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol) were blended in a blending ratio of 80 / 20 (wt%), passed through a carding machine, and then heat-treated for 5 minutes in a hot air circulation dryer at 140°C to obtain a fabric with a basis weight of 100 g / m. ２ An oil-water separating sheet was obtained in the same manner as in Example 1, except that the nonwoven fabric of Example 1 was used. The evaluation results are shown in Table 1.

[0088] Next, the oil-water separation sheet was formed into a bag shape, and water-absorbent fibers were enclosed inside to obtain an oil-water separation article. The water-absorbent fibers used were "Belloasis" (a cross-linked sodium polyacrylate fiber, water absorption rate (50 times its own weight), single fiber fineness 10 dtex, fiber length 5 mm) manufactured by Teijin Frontier Co., Ltd. It was confirmed that the oil-water separation article selectively removed only water by immersing it in oil mixed with water. Furthermore, it was confirmed that the article selectively removed only water even in a liquid in which water and oil were thoroughly stirred and emulsified.

[0089] [Comparative Example 1] Instead of the wetlaid nonwoven fabric in Example 1, crimped staple fibers (fineness 2.2 dtex, single fiber diameter 14 μm, fiber length 51 mm) made of polyethylene terephthalate (PET) and core-sheath composite thermal adhesive staple fibers (core / sheath = 50 / 50, core: polyethylene terephthalate with a melting point of 256°C, sheath: copolymer polyester with a softening point of 110°C and mainly composed of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol) were blended in a blending ratio of 80 / 20 (wt%), passed through a carding machine, and then heat-treated for 5 minutes in a hot air circulation dryer at 140°C to produce a fabric with a basis weight of 20 g / m. ２ An oil-water separating sheet was obtained in the same manner as in Example 1, except that the nonwoven fabric of Example 1 was used. The evaluation results are shown in Table 1.

[0090] Next, the oil-water separation sheet was formed into a bag shape, and water-absorbent fibers were enclosed in the bag to obtain an oil-water separation article. The water-absorbent fibers used were "Belloasis" (a cross-linked sodium polyacrylate fiber, water absorption rate (50 times its own weight), single fiber fineness 10 dtex, and fiber length 5 mm) manufactured by Teijin Frontier Co., Ltd. The oil-water separation article was immersed in oil mixed with water, but it was not possible to selectively remove only the water.

[0091] [Comparative Example 2] Instead of the wetlaid nonwoven fabric in Example 1, crimped staple fibers (fineness 2.2 dtex, single fiber diameter 14 μm, fiber length 51 mm) made of polyethylene terephthalate (PET) and core-sheath composite thermal adhesive staple fibers (core / sheath = 50 / 50, core: polyethylene terephthalate with a melting point of 256°C, sheath: copolymer polyester with a softening point of 110°C and mainly composed of terephthalic acid, isophthalic acid, ethylene glycol, and diethylene glycol) were blended in a blending ratio of 80 / 20 (wt%), passed through a carding machine, and then heat-treated for 5 minutes in a hot air circulation dryer at 140°C to produce a fabric with a basis weight of 50 g / m. ２ An oil-water separating sheet was obtained in the same manner as in Example 1, except that the nonwoven fabric of Example 1 was used. The evaluation results are shown in Table 1.

[0092] Next, the oil-water separation sheet was formed into a bag shape, and water-absorbent fibers were enclosed inside to obtain an oil-water separation article. The water-absorbent fibers used were "Belloasis" (a cross-linked sodium polyacrylate fiber, water absorption rate (50 times its own weight), single fiber fineness 10 dtex, fiber length 5 mm) manufactured by Teijin Frontier Co., Ltd. It was confirmed that the oil-water separation article selectively removed only water by immersing it in oil mixed with water. However, it was not possible to selectively remove only water from a liquid in which the water and oil were sufficiently stirred and emulsified.

[0093] Comparative Example 3 An oil-water separating sheet was obtained in the same manner as in Example 1, except that the wetlaid nonwoven fabric was not used. The evaluation results are shown in Table 1.

[0094] Next, the oil-water separation sheet was formed into a bag shape, and water-absorbent fibers were enclosed in the bag to obtain an oil-water separation article. The water-absorbent fibers used were "Belloasis" (a cross-linked sodium polyacrylate fiber, water absorption rate (50 times its own weight), single fiber fineness 10 dtex, and fiber length 5 mm) manufactured by Teijin Frontier Co., Ltd. The oil-water separation article was immersed in oil mixed with water, but it was not possible to selectively remove only the water.

[0095] Comparative Example 4 An oil-water separating sheet was obtained in the same manner as in Example 1, except that the water-absorbing and oil-repellent treatment was not performed. The evaluation results are shown in Table 1.

[0096] Next, the oil-water separation sheet was formed into a bag shape, and water-absorbent fibers were enclosed in the bag to obtain an oil-water separation article. The water-absorbent fibers used were "Belloasis" (a cross-linked sodium polyacrylate fiber, water absorption rate (50 times its own weight), single fiber fineness 10 dtex, and fiber length 5 mm) manufactured by Teijin Frontier Co., Ltd. The oil-water separation article was immersed in oil mixed with water, but it was not possible to selectively remove only the water.

[0097]

[0098] According to the present invention, an oil-water separation sheet and an oil-water separation article are provided that can separate oil and water without the need for suction, and are of great industrial value.

Claims

1. An oil-water separation sheet, comprising fibers having a single fiber diameter of 15.0 μm or less, subjected to water-absorbing and oil-repellent treatment, and having an air permeability of 50 cm ３ / cm ２ / sec or less. The oil-water separation sheet is characterized by this.

2. The oil-water separation sheet according to claim 1, having a water absorption of 60 seconds or less and an oil repellency of 180 seconds or more.

3. An oil-water separation article, which is formed by making the oil-water separation sheet according to claim 1 or 2 into a bag shape and enclosing water-absorbing fibers therein.

4. The oil-water separation article according to claim 3, wherein the water-absorbing fibers are crosslinked sodium polyacrylate-based fibers or acrylate-based fibers obtained by hydrolyzing the surface of acrylic fibers.

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