阅读说明：本技术 油水分离过滤器及其制造方法 (Oil-water separation filter and manufacturing method thereof ) 是由 白石真也 于 2021-05-26 设计创作，主要内容包括：本发明提供油水分离过滤器,其是包含在纤维间形成有多个气孔的无纺布的油水分离过滤器,所述多个气孔贯通包含水和油的液体流入的一面和与这一面相对且前述液体流出的另一面之间。形成包含平均粒径2～90nm的金属氧化物粒子(B)和含羧基的物质等(C)的拒水拒油性膜,所述平均粒径2～90nm的金属氧化物粒子(B)是在无纺布的纤维表面结合有包含式(1)的全氟醚结构的氟系官能团成分(A)的粒子。成分(A)以0.3～5.0质量%的比例包含于膜中,成分(A)和粒子(B)总计以30～90质量%的比例包含于膜中,质量比(A/B)在0.01～0.2的范围,过滤器透气度为0.05～14ml/cm～(2)/秒。(The present invention provides an oil-water separation filter including a nonwoven fabric having a plurality of pores formed between fibers, the plurality of pores penetrating between one surface into which a liquid including water and oil flows and the other surface opposite to the one surface and from which the liquid flows out. A water-and oil-repellent film is formed which comprises (C) metal oxide particles (B) having an average particle diameter of 2 to 90nm and a carboxyl group-containing substance, wherein the metal oxide particles (B) having an average particle diameter of 2 to 90nm are particles in which a fluorine-based functional group component (A) having a perfluoroether structure of the formula (1) is bonded to the fiber surface of a nonwoven fabric. The component (A) is contained in the film in a proportion of 0.3 to 5.0% by mass, and the total of the component (A) and the particles (B) is 30 to E90% by mass, a mass ratio (A/B) of 0.01 to 0.2, and a filter air permeability of 0.05 to 14ml/cm 2 In seconds.)

1. An oil-water separation filter comprising a nonwoven fabric having a plurality of pores formed between fibers, the pores communicating between one surface into which a liquid containing water and oil flows and the other surface opposite to the one surface through which the liquid flows out,

a water-and oil-repellent film is formed on the fiber surface of the nonwoven fabric,

the water-and oil-repellent film comprises metal oxide particles (B) having an average particle diameter of 2 to 90nm and a substance (C) containing a carboxyl group and/or an acetyl group, wherein the metal oxide particles (B) are bonded with a fluorine-based functional group component (A) having a perfluoroether structure represented by the following general formula (1) or formula (2),

the fluorine-based functional group component (A) is contained in the water-and oil-repellent film in a proportion of 0.3 to 5.0% by mass,

the fluorine-based functional group component (A) and the metal oxide particles (B) are contained in the water-and oil-repellent film in a total amount of 30 to 90 mass%, and

the mass ratio (A/B) of the fluorine-based functional group component (A) to the metal oxide particles (B) is in the range of 0.01 to 0.2,

the air permeability of the oil-water separation filter is 0.05ml/cm²Second to 14ml/cm²A/second;

[ solution 1]

In the formulae (1) and (2), p, q and r are each an integer of 1 to 6 which may be the same or different from each other, and the perfluoroether group may be linear or branched; in the formulas (1) and (2), X is a hydrocarbon group having 2 to 10 carbon atoms and may contain 1 or more bonds selected from an ether bond, a CO-NH bond, an O-CO-NH bond, and a sulfonamide bond; further, in the above formulae (1) and (2), Y is a hydrolysate of silane or a main component of silica sol gel.

2. The oil-water separator filter according to claim 1, wherein the metal oxide particles (B) are oxide particles of 1 metal selected from Si, Al, Mg, Ca, Ti, Zn, and Zr.

3. The oil-water separator according to claim 1, wherein the substance (C) containing a carboxyl group and/or an acetyl group is an aqueous dispersion of a polyolefin having a carboxyl group, a self-emulsion of an ethylene-vinyl acetate copolymer, or a self-emulsion of an ethylene-vinyl acetate-acrylic acid copolymer.

4. The oil-water separator filter according to claim 1, wherein the nonwoven fabric is formed of a single layer or a multilayer laminate.

5. The oil-water separator filter according to claim 1 or 4, wherein the fiber constituting the nonwoven fabric is selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), Polytetrafluoroethylene (PTFE)、1 or more than 2 kinds of glass, alumina, carbon, cellulose, pulp, nylon and metal.

6. A method for manufacturing an oil-water separation filter, comprising:

a step for preparing a liquid composition for forming a water-and oil-repellent film by mixing an aqueous dispersion of fluorine-containing metal oxide particles, a substance containing a carboxyl group and/or an acetyl group, and a solvent containing water and an alcohol having 1 to 4 carbon atoms, wherein the alcohol is obtained by mixing water and an alcohol having 1 to 4 carbon atoms, and the content ratio of the alcohol having 1 to 4 carbon atoms is 40% by mass or less,

a step of immersing a nonwoven fabric in a diluted liquid of the liquid composition for forming a water-and oil-repellent film, and

and a step of removing the liquid from the impregnated nonwoven fabric and drying the nonwoven fabric.

7. The method for manufacturing an oil-water separator filter according to claim 6, wherein the substance (C) containing a carboxyl group and/or an acetyl group is a polyolefin aqueous dispersion having a carboxyl group, a self-emulsion of an ethylene-vinyl acetate copolymer, or a self-emulsion of an ethylene-vinyl acetate-acrylic acid copolymer.

8. The method for manufacturing an oil-water separation filter according to claim 6, wherein the aqueous dispersion of the fluorine-containing metal oxide particles is prepared by adding a mixed fluorine compound to the aqueous dispersion of the metal oxide particles and adding a mixed catalyst to the mixed solution.

9. The method for manufacturing an oil-water separator filter according to claim 6, wherein the metal oxide particles are oxide particles of 1 metal selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn, and Zr.

Technical Field

The present invention relates to an oil-water separation filter capable of separating a liquid containing water and oil, such as emulsified oil or water-soluble oil in which oil and water are mixed and emulsified, into water and oil, and a method for manufacturing the same. More specifically, the present invention relates to an oil-water separation filter in which a water-and-oil-repellent film having water repellency and oil repellency (hereinafter, sometimes referred to as water-and-oil repellency) is formed on the fiber surface of a nonwoven fabric.

Background

Generally, a liquid containing water and oil (hereinafter, sometimes simply referred to as a liquid) is classified into a floating oil in which oil floats on a water surface, a dispersed oil in which particles of oil float in water, and an emulsified oil or a water-soluble oil in which oil is mixed with water and emulsified, depending on a state of mixing of the oil and the water.

The present applicant has proposed an oil-water separator filter comprising a nonwoven fabric having a plurality of pores formed between fibers, the pores communicating between one surface into which a liquid containing water and oil flows and the other surface opposite to the one surface, wherein the oil-water separator filter is characterized in that the fiber surface has pores of 1m per fiber surface²An oil-water separation film (corresponding to the water-and oil-repellent film of the present invention) is formed on the nonwoven fabric in a proportion of 0.1 to 30g, the oil-water separation film has a silica sol hydrolysate containing a fluorine-containing silane represented by the following formula (28) having both water-and oil-repellent functions, the fluorine-containing silane is contained in the silica sol hydrolysate in a proportion of 0.01 to 10 mass%, and the oil-water separation filter has an air permeability of 0.05 to 10ml/cm²Second, the fluorine-containing silane has a perfluoroamine structure (see patent document 1 (claims 1, [0016 ]) (see]Section)). In the formula (28), E is a hydrocarbon group having 2 to 10 carbon atoms and contains 1 or more bonds selected from an ether bond, a CO-NH bond and an O-CO-NH bond.

[ solution 9]

In this oil-water separation filter, when the oil particles of the liquid containing water and oil are larger than the pore diameter of the pores when the liquid flows into the oil-water separation filter, the oil particles of the liquid containing water and oil are physically blocked from passing through. Even when the oil particles of the liquid containing water and oil are slightly smaller than the pore diameter of the pores, the fiber surface of the nonwoven fabric chemically repels the oil particles of the water-soluble oil. On the other hand, materials exhibiting water and oil repellency, such as polytetrafluoroethylene, have no hydroxyl group and thus are difficult to impart water permeability to nonwoven fabrics, but the invention proposed by the applicant can impart water permeability to nonwoven fabrics because the oil-water separation membrane mainly contains a silica sol hydrolysate having hydroxyl groups. As a result, even if the liquid containing water and oil is emulsified oil or water-soluble oil, the oil is accumulated in the oil-water separation filter, and water passes through the oil-water separation filter, so that water and oil can be separated. Further, since the oil-water separation membrane contains a silica sol hydrolysate as a main component, the oil-water separation membrane is firmly adhered to the fiber surface of the nonwoven fabric and has durability.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2019-42707.

Disclosure of Invention

Technical problem to be solved by the invention

However, the fluorine-containing silane disclosed in patent document 1 has a perfluoroamine structure, and a perfluoro group is bonded around nitrogen, and therefore, a rigid structure is easily adopted. Therefore, if the fluorine content in the liquid composition is increased, the adhesion of the oil-water separation membrane to the fibers of the nonwoven fabric may be reduced, and there is still room for improvement from the viewpoint of durability. Further, since water repellency is more strongly exhibited than a fluorine-based compound having a perfluoroether structure, there is a problem that a long liquid passing time is required when a liquid containing water and oil is passed through an oil-water separation filter shown in patent document 1.

The purpose of the present invention is to provide an oil-water separation filter which has good filtration efficiency for removing oil from a liquid containing water and oil, such as emulsified oil or water-soluble oil, and which has a short liquid passage time and no problem. Another object of the present invention is to provide a method for easily manufacturing such an oil-water separation filter.

Means for solving the problems

The invention in view 1 is an oil-water separating filter which is a bagAn oil-water separating filter comprising a nonwoven fabric having a plurality of pores formed between fibers, the pores penetrating between one surface into which a liquid containing water and oil flows and the other surface opposite to the one surface through which the liquid flows out, the oil-water separating filter being characterized in that a water-and-oil repellent film is formed on the fiber surfaces of the nonwoven fabric, the water-and-oil repellent film comprising metal oxide particles (B) having an average particle diameter of 2 to 90nm and a substance (C) containing a carboxyl group and/or an acetyl group (hereinafter, simply referred to as "carboxyl group-containing substance or the like"), the metal oxide particles (B) being bonded with a fluorine-based functional group component (A) having a perfluoroether structure represented by the following general formula (1) or formula (2), the fluorine-based functional group component (A) being contained in the water-and-oil-repellent film in a proportion of 0.3 to 5.0 mass%, the fluorine-based functional group component (A) and the metal oxide particles (B) being present in total of 30 mass% > The water-and oil-repellent film contains 90% by mass of the fluorine-based functional group component (A) and the metal oxide particles (B) in a mass ratio (A/B) of 0.01 to 0.2, and the oil-water separation filter has an air permeability of 0.05ml/cm²Second to 14ml/cm²In seconds.

[ solution 1]

In the formulae (1) and (2), p, q and r are each an integer of 1 to 6 which may be the same or different from each other, and the perfluoroether group may be linear or branched. In the formulae (1) and (2), X is a hydrocarbon group having 2 to 10 carbon atoms and may contain 1 or more bonds selected from the group consisting of ether bonds, CO-NH bonds, O-CO-NH bonds, and sulfonamide bonds. Further, in the above formulae (1) and (2), Y is a hydrolysate of silane or a main component of silica sol gel.

Further, when Y is described, Y is a site bonded to the metal oxide particle (B). Specifically, in the formula (3) or (4) described below, Y is a structure in which Z is partially hydrolyzed. Further, Y may be a main component of a silica sol gel obtained by mixing the silane compound of the formula (3) or (4) with a silicon alkoxide such as tetraethoxysilane or tetramethoxysilane and subjecting the mixture to hydrolytic polymerization. Further, Y may be a main component of a silica sol gel obtained by mixing the silane compound of the formula (3) or (4) with a silicon alkoxide such as tetraethoxysilane or tetramethoxysilane, a silane containing an ethoxy group, a vinyl group, an ether group, or the like, and subjecting the mixture to hydrolytic polymerization. The carboxyl group-containing substance (C) is a binder for bonding the metal oxide particles (B) to which the fluorine-based functional group component (a) is bonded to a base material of a nonwoven fabric.

The invention according to claim 2 is the oil-water separator filter according to claim 1, wherein the metal oxide particles (B) are oxide particles of 1 metal selected from Si, Al, Mg, Ca, Ti, Zn, and Zr.

The 3 rd aspect of the present invention is the oil-water separator according to the 1 st aspect of the present invention, wherein the (C) carboxyl group-containing substance or the like is a polyolefin aqueous dispersion having a carboxyl group, a self-emulsion of an ethylene-vinyl acetate copolymer, or a self-emulsion of an ethylene-vinyl acetate-acrylic acid copolymer.

The invention according to claim 4 is the oil-water separator according to claim 1, wherein the nonwoven fabric is formed of a single layer or a multilayer laminate.

The 5 th aspect of the present invention is the oil-water separator according to any one of the 1 st or 4 th aspects, wherein the fibers constituting the nonwoven fabric are 1 or 2 or more fibers selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), Polytetrafluoroethylene (PTFE), glass, alumina, carbon, cellulose, pulp, nylon, and metal.

The 6 th aspect of the present invention is a method for manufacturing an oil-water separator 13, as shown in fig. 4, including: a step of mixing an aqueous dispersion 54 of fluorine-containing metal oxide particles, a carboxyl group-containing substance 55, and a solvent 56 in which the content of a C1-4 alcohol obtained by mixing water and a C1-4 alcohol is 40% by mass or less to prepare a liquid composition for forming a water-and oil-repellent film (hereinafter, sometimes simply referred to as a liquid composition) 60; a step of immersing the nonwoven fabric 20 in a diluted liquid of the liquid composition 60 for forming a water-and oil-repellent film; and a step of removing the liquid from the impregnated nonwoven fabric and drying the nonwoven fabric.

The 7 th aspect of the present invention is the method for producing an oil-water separator filter according to the 6 th aspect of the present invention, wherein the (C) carboxyl group-containing substance or the like is a polyolefin aqueous dispersion having a carboxyl group, a self-emulsion of an ethylene-vinyl acetate copolymer, or a self-emulsion of an ethylene-vinyl acetate-acrylic acid copolymer.

The 8 th aspect of the present invention is the method for producing an oil-water separator filter according to the 6 th aspect of the present invention, wherein the aqueous dispersion 54 of fluorine-containing metal oxide particles is prepared by adding the mixed fluorine compound 52 to the aqueous dispersion 51 of metal oxide particles and adding the mixed catalyst 53 to the mixed solution.

The 9 th aspect of the present invention is the method for producing an oil-water separator filter according to the 6 th aspect of the present invention, wherein the metal oxide particles 51 are oxide particles of 1 metal selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn and Zr.

Effects of the invention

In the oil-water separation filter according to claim 1 of the present invention, when a liquid containing water and oil flows into the oil-water separation filter from one surface thereof, if oil particles in the liquid are larger than the pore diameter of the pores, the oil particles in the liquid are physically blocked from passing through. Even when the liquid oil particles are slightly smaller than the pore diameter of the pores, the fiber surface of the nonwoven fabric chemically repels the oil particles of the water-soluble oil. Further, the water-and oil-repellent film contains (B) metal oxide particles having an average particle diameter of 2 to 90nm, to which the fluorine-containing functional group component (a) is bonded, and (C) a carboxyl group-containing substance, and thus the water-and oil-repellent film formed is high in water repellency and oil repellency. In addition, since the metal oxide particles (B) having an average particle diameter of 2nm to 90nm are bonded to each other through the carboxyl group-containing substance (C) during film formation, the strength of the film and the adhesion of the film can be improved. The oil-water separation filter has the advantages of good filtering efficiency for removing oil from liquid containing water and oil, short liquid passing time and no problem.

In the oil-water separator according to claim 2 of the present invention, the metal oxide particles contained in the water-and oil-repellent film are 1 type of metal oxide particles selected from Si, Al, Mg, Ca, Ti, Zn, and Zr, and therefore, the metal oxide particles suitable for the use environment of the oil-water separator can be included among the plurality of types of metal oxide particles.

In the oil-water separator filter according to claim 3 of the present invention, since the carboxyl group-containing substance is a polyolefin aqueous dispersion having a carboxyl group, a self-emulsified liquid of an ethylene-vinyl acetate copolymer, or a self-emulsified liquid of an ethylene-vinyl acetate-acrylic acid copolymer, the aqueous dispersion or the self-emulsified liquid functions as a binder for the fluorine-containing metal oxide particles, and when the liquid composition is formed into a film on the surface of the substrate, the film can be firmly bonded to the surface of the substrate.

In the oil-water separator according to claim 4 of the present invention, when the nonwoven fabric is formed of a single layer, the oil-water separator is simple in structure, and when the nonwoven fabric is formed of a multilayer laminate, each layer can be formed according to the particle size of oil particles, the concentration of oil, and the like in the liquid containing water and oil that flows in.

In the oil-water separator filter according to claim 5 of the present invention, the material of the fibers constituting the nonwoven fabric may be selected from polyethylene terephthalate (PET), polypropylene (PP), Polytetrafluoroethylene (PTFE), glass, alumina, carbon, cellulose, pulp, nylon, and metal, depending on the particle size of oil particles, the concentration of oil, and the like in the liquid containing water and oil that flows in.

In the method according to the 6 th aspect of the present invention, the water-and oil-repellent film-forming liquid composition is prepared by mixing the aqueous dispersion of the fluorine-containing metal oxide particles, the carboxyl group-containing substance, and the like, and the solvent, and the water-and oil-repellent film-forming liquid composition is produced by immersing the nonwoven fabric in a diluted solution of the water-and oil-repellent film-forming liquid composition, removing the liquid from the nonwoven fabric, and drying the nonwoven fabric. Secondly, a water-and oil-repellent film can be uniformly formed on the fiber surface of the nonwoven fabric. Thirdly, since the metal oxide particles having the water-and oil-repellent particle surfaces are present in a substance having a carboxyl group or the like, the air permeability of the nonwoven fabric tends to be lowered while the water-and oil-repellent property is maintained.

In the method for producing an oil-water separator filter according to aspect 7 of the present invention, since the carboxyl group-containing substance is a polyolefin-based aqueous dispersion having a carboxyl group, a self-emulsified liquid of an ethylene-vinyl acetate copolymer, or a self-emulsified liquid of an ethylene-vinyl acetate-acrylic acid copolymer, the aqueous dispersion or the self-emulsified liquid functions as a binder for the fluorine-containing metal oxide particles, and when the liquid composition is formed into a film on the surface of the substrate, the film can be firmly adhered to the surface of the substrate.

In the method for producing an oil-water separator according to claim 8 of the present invention, since the mixed fluorine compound is added to the aqueous dispersion of metal oxide particles and the mixed catalyst is added to the mixed solution, an aqueous dispersion in which the fluorine-containing metal oxide particles are uniformly dispersed can be obtained.

In the method for producing an oil-water separator according to claim 9 of the present invention, since the metal oxide particles are 1 type of metal oxide particles selected from Si, Al, Mg, Ca, Ti, Zn, and Zr, an oil-water separator including metal oxide particles suitable for the environment in which the oil-water separator is used can be produced from a plurality of types of metal oxide particles.

In the method for producing an oil-water separator filter according to any one of aspects 6 to 9 of the present invention, the water-and oil-repellent film is bonded to the fiber surface of the nonwoven fabric while reducing the air permeability, and therefore, sufficient oil-repellent performance can be obtained. Further, the metal oxide particles can also provide an effect of improving the abrasion strength of the film.

Drawings

FIG. 1: the configuration of an oil-water separation device provided with an oil-water separation filter according to an embodiment of the present invention is shown.

FIG. 2: is a cross-sectional view of the single-layer nonwoven fabric of the present embodiment.

FIG. 3: is a cross-sectional view of the two-layer nonwoven fabric of the present embodiment.

FIG. 4: the flow chart is for manufacturing the oil-water separation filter according to the present embodiment.

FIG. 5: the structures of the apparatuses used in the filtration tests of the oil-water separation filters of the examples and comparative examples are shown.

Detailed Description

Next, a mode for carrying out the present invention will be described with reference to the drawings.

[ oil-water separator ]

As shown in fig. 1, an oil-water separator 10 of the present embodiment includes: a tubular liquid inflow portion 12 into which a liquid 11 containing water and oil flows; a sheet-like oil-water separation filter 13 for separating oil in the liquid 11 from water; a funnel-shaped water collecting unit 16 for collecting the water 14 separated by the oil-water separation filter 13; and a bottomed cylindrical water storage portion 17 for storing the water 14 flowing from the water collection portion 16. An inflow pipe 18 for liquid is provided above the liquid inflow portion 12, and a drain pipe 19 is provided at the bottom of the water storage portion 17.

In the case where the oil-water separation filter 13 is formed of only a nonwoven fabric, although not shown, a metal porous support plate for reinforcing the nonwoven fabric is provided on the entire lower surface of the oil-water separation filter 13 so that the filter 13 can withstand the pressure of the liquid in the liquid inflow portion 12, and the oil-water separation filter 13 and the support plate are sandwiched between the liquid inflow portion 12 and the water collection portion 16.

[ oil-water separating filter ]

As shown in fig. 2, the oil-water separator filter 13 of the present embodiment includes a nonwoven fabric 20 and a water-and oil-repellent film 21 formed on the fiber surface of the nonwoven fabric. The nonwoven fabric 20, which is a main component of the oil-water separation filter 13, has one surface 20a into which a liquid containing water and oil flows, and the other surface 20b, which faces the one surface 20a, from which the filtrate flows out, and is formed of a single layer. As shown in fig. 3, the oil-water separator 23 may be formed by a two-layer laminate of an upper nonwoven fabric 30 and a lower nonwoven fabric 40 made of nonwoven fabric. At this time, the upper surface of the nonwoven fabric 30 of the upper layer is a surface 30a into which a liquid containing water and oil flows, and the lower surface of the nonwoven fabric 40 of the lower layer is a surface 40b from which the filtrate flows out, the surface facing the surface 30 a. The lower surface 30b of the nonwoven fabric 30 is closely adhered to the upper surface 40a of the nonwoven fabric 40. The laminate is not limited to two layers, and may be composed of three or four layers.

As shown in the enlarged view in the center of fig. 2, the nonwoven fabric 20 is formed by winding a plurality of fibers 20c around each other, and pores 20d are formed between the fibers. The air holes 20d penetrate between the one surface 20a and the other surface 20b of the nonwoven fabric 20. A water-and oil-repellent film 21 is formed on the surface of the fibers 20c of the nonwoven fabric. The weight per unit area of the nonwoven fabric is preferably 10g/m²～400g/m²More preferably 100g/m²～350g/m²The range of (1) is not limited to the above range. The water-and oil-repellent film 21 contains (B) metal oxide particles having an average particle diameter of 2 to 90nm and (C) a carboxyl group-containing substance. The fluorine-based functional group component (A) represented by the general formula (1) or the general formula (2) is bonded to the metal oxide particles (B). The fluorine-based functional group component (a) is contained in the water-and oil-repellent film 21 in a proportion of 0.3 to 5.0% by mass, preferably 0.4 to 4.0% by mass. The water-and oil-repellent film 21 contains (C) such as a carboxyl group-containing substance in an amount of 10 to 70 mass%, preferably 15 to 65 mass%. The fluorine-based functional group component (a) and the metal oxide particles (B) are contained in the water-and oil-repellent film 21 in a total amount of 30 to 90 mass%, preferably 35 to 85 mass%. Further, the mass ratio (A/B) of the fluorine-based functional group component (A) to the metal oxide particles (B) is in the range of 0.01 to 0.2, preferably 0.014 to 0.18.

As shown in a further enlarged view of the upper part of fig. 2, the water-and oil-repellent film 21 is formed by bonding a plurality of metal oxide particles 21a, the particle surfaces of which are covered with a fluorine-based functional group component, with a substance 21b containing a carboxyl group or the like as a binder. Since the water-and oil-repellent film 21 contains the metal oxide particles 21a, it is possible to form a thick film in appearance and narrow the pores 20d between the fibers. Further, the film thickness can be controlled by changing the particle diameter of the metal oxide particles and the content ratio of the metal oxide particles in the film component.

On the surface of the fiberThe nonwoven fabric 20 had a thickness of 0.05ml/cm in the state of the oil-water separator 13 having the water-and-oil repellent film 21²Second to 14ml/cm²Air permeability/sec. Air permeability of less than 0.05ml/cm²At/sec, or a weight per unit area of more than 400g/m²In the case of the method, the water permeability is poor, and it is difficult to obtain a filtrate. Air permeability of more than 14ml/cm²At/sec, or the weight per unit area of the nonwoven fabric is less than 10g/m²In this case, the size of the pores 20d of the nonwoven fabric becomes much larger than the size of the oil particles 22 in the mixed liquid, and the oil particles 22 pass through the pores of the nonwoven fabric together with water and are discharged from the oil-water separation filter 13Leak out ofWater and oil cannot be separated. The air permeability is preferably 0.1ml/cm²Second to 10ml/cm²In seconds. The air permeability was measured according to JIS-L1913: the measurement was performed by a Frazier type tester described in 2000.

When the content of the fluorine-based functional group component (a) in the water-and oil-repellent film 21 is less than 0.3% by mass, the effect of oil repellency is poor and the performance of oil-repellent particles is insufficient. When the content of the fluorine-based functional group component (a) exceeds 5.0 mass%, the film-forming property is poor, and the adhesion of the water-and oil-repellent film to the nonwoven fabric is poor.

The average particle diameter of the metal oxide particles (B) contained in the water-and oil-repellent film 21 is in the range of 2nm to 90nm, preferably 2nm to 85 nm. When the average particle diameter is less than 2nm, aggregation of the metal oxide particles is likely to occur, and dispersion in a medium is difficult. When the particle diameter exceeds 90nm, the metal oxide particles (B) are detached from the water-and oil-repellent film. When the content of (C) such as a substance containing a carboxyl group in the water-and oil-repellent film 21 is less than 10% by mass, the film strength and the film adhesion are liable to deteriorate. If the amount exceeds 70 mass%, it becomes difficult to impart oil repellency to the film. When the total of the fluorine-based functional group component (a) and the metal oxide particles (B) in the water-and oil-repellent film 21 is less than 30 mass%, the oil-repellent performance of the water-and oil-repellent film is lowered. When the total amount exceeds 90 mass%, the content of (C) such as a carboxyl group-containing substance is relatively low, and the water-and oil-repellent film cannot be firmly adhered to the surface of the nonwoven fabric. When the mass ratio (a/B) is less than 0.01, the oil repellency of the water-and oil-repellent film is poor, and when it exceeds 0.2, the adhesion of the water-and oil-repellent film to the fiber surface is lowered. In the present specification, the average particle diameter of the metal oxide particles refers to an average value of sizes obtained by measuring a particle size of 200 dots by image analysis in a particle shape observed by a Transmission Electron Microscope (TEM).

The operation of the oil-water separator 10 having such an oil-water separation filter 13 will be described. As shown in fig. 1, first, the oil-water separation filter 13 is sandwiched between the liquid inflow portion 12 and the water collection portion 16. Then, the liquid 11 containing water and oil is supplied from the inflow pipe 18 to the liquid inflow portion 12. The liquid of this embodiment is a water-soluble oil. The liquid 11 stored in the liquid inflow portion 12 contacts one surface 20a (fig. 2) of the nonwoven fabric 20 constituting the oil-water separation filter 13. Here, since the oil-water separation filter 13 has a predetermined air permeability and the oil-water separation membrane 21 exhibits water repellency and oil repellency, water (not shown) in the water-soluble oil is repelled by the oil-water separation membrane 21 and passes through the air holes 20d formed between the fibers 20c and the fibers 20c shown in the enlarged view of fig. 2 and reaches the other surface 20b due to the presence of hydroxyl groups such as carboxyl group-containing substances, passes through the nonwoven fabric 20, drips therefrom, and is collected in the water collection portion 16. The collected water 14 flows down from the water collection portion 16 to the water storage portion 17, and is stored in the water storage portion 17. When a certain amount of water 14 is stored in the water storage portion 17, a drain valve, not shown, is opened, and the water 14 separated from the oil is obtained from the drain pipe 19.

On the other hand, as shown in the enlarged view of fig. 2, since the oil-water separation membrane 21 formed on the fiber surface of the nonwoven fabric 20 is oil-repellent and has a predetermined air permeability of the oil-water separation filter, the oil particles 22 in the liquid cannot pass through the oil-water separation filter 13 and stay between the fibers 20c and the fibers 20c of the nonwoven fabric 20 even if the particle diameter is slightly smaller than the pore diameter of the pores 20 d. Since the water-and oil-repellent film 21 contains the metal oxide particles 21a, the film becomes uneven, and the degree of adhesion of the oil particles 22 to the film is low. Thereby, the oil particles 22 are trapped by the nonwoven fabric. The oil-water separation filter 13 is periodically detached from the oil-water separator 10, and the oil accumulated in the nonwoven fabric 20 is recovered.

[ method for producing oil-water separating Filter ]

The oil-water separation filter is manufactured by the following method.

As shown in fig. 4, a fluorine compound 52 containing a fluorine-based functional group component (a) is mixed with an aqueous dispersion 51 of metal oxide particles, and a catalyst 53 is further mixed to prepare an aqueous dispersion 54 of fluorine-containing metal oxide particles. The water-and oil-repellent film-forming liquid composition 60 is prepared by mixing the aqueous dispersion 54, the carboxyl group-containing substance 55, and the solvent 56. An oil-water separation filter 13 is produced by preparing a liquid obtained by diluting a water-and oil-repellent film-forming liquid composition 60 with a solvent 61 obtained by mixing water and an alcohol having a boiling point in the range of 1 to 4 carbon atoms, immersing a nonwoven fabric 20 in the diluent 62, pulling out the nonwoven fabric from the diluent, stretching the nonwoven fabric on a horizontal wire mesh (gold-wire) or the like in the atmosphere at room temperature, draining the nonwoven fabric until a predetermined liquid content is reached, and drying the nonwoven fabric.

[ preparation of nonwoven Fabric ]

First, a sample having a density of 0.05ml/cm was prepared²Second to 18ml/cm²A nonwoven fabric with air permeability per second. Specifically, an oil-water separating filter having a water-and oil-repellent film formed on the fiber surface of a nonwoven fabric, which will be described later, was prepared to have a volume of 0.05ml/cm²Second to 14ml/cm²A nonwoven fabric with air permeability per second. When the water-and oil-repellent film is formed as a thick film, a nonwoven fabric having a high air permeability is selected, and when the water-and oil-repellent film is formed as a thin film, a nonwoven fabric having a low air permeability is selected.

Examples of the nonwoven fabric include a cellulose ester-mixed membrane filter, a glass fiber filter, and a nonwoven fabric in which polyethylene terephthalate fibers and glass fibers are mixed (trade name: 340, manufactured by andel filter). Thus, the nonwoven fabric is made of 1 or 2 or more kinds of fibers selected from polyethylene terephthalate (PET), polypropylene (PP), Polytetrafluoroethylene (PTFE), glass, alumina, carbon, cellulose, pulp, nylon, and metal. The fibers may be a mixture of 2 or more kinds of fibers. In order to obtain the above air permeability, the thickness of the fibers (fiber diameter) is preferably 0.01 to 10 μm, but is not limited to this range. The thickness of the nonwoven fabric is preferably 0.2mm to 0.8mm in the case of a single layer oil-water separation filter, and preferably 0.2mm to 1.6mm in the case of a multilayer laminate.

[ method for producing liquid composition for Forming Water-and oil-repellent film ]

[ preparation of an aqueous Dispersion of Metal oxide particles ]

First, an aqueous dispersion of metal oxide particles is prepared by dispersing metal oxide particles in an aqueous solvent. As the metal oxide particles, SiO can be exemplified₂、Al₂O₃、MgO、CaO、TiO₂、ZnO、ZrO₂And the like. Examples of the aqueous solvent include water and a mixed solvent of water and an alcohol having 1 to 4 carbon atoms. As the water, ion-exchanged water, pure water, or the like is preferably used in order to prevent impurities from being mixed therein.

[ preparation of an aqueous Dispersion of fluorine-containing Metal oxide particles ]

Next, a fluorine compound containing a fluorine-based functional group component represented by the above formula (1) or formula (2) is added to the prepared aqueous dispersion of the metal oxide particles to synthesize a composite material in which the metal oxide particles and the fluorine-based functional group component are nano-composited. To further accelerate the reaction, a catalyst is added. Thus, an aqueous dispersion of fluorine-containing metal oxide particles was prepared.

Examples of the catalyst include an organic acid, an inorganic acid, a base, and a titanium compound, examples of the organic acid include formic acid and oxalic acid, examples of the inorganic acid include hydrochloric acid, nitric acid, and phosphoric acid, examples of the base include sodium hydroxide, lithium hydroxide, magnesium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia, and examples of the titanium compound include titanium tetrapropoxide, titanium tetrabutoxide, titanium tetraisopropoxide, and titanium lactate. The catalyst is not limited to the above.

The fluorine-containing compound containing a fluorine-containing functional group component is represented by the following general formula (3) or (4). The perfluoroether group in the formula (3) or (4) is more specifically a perfluoroether structure represented by the following formulae (5) to (13).

[ solution 2]

[ solution 3]

[ solution 4]

In addition, X in the above formulae (3) and (4) is a structure represented by the following formulae (14) to (18). The following formula (14) shows an example containing an ether bond, the following formula (15) shows an example containing an ester bond, the following formula (16) shows an example containing an amide bond, the following formula (17) shows an example containing a urethane bond, and the following formula (18) shows an example containing a sulfonamide bond.

[ solution 5]

In the above formulae (14) to (18), R is²And R³Is a hydrocarbon group having 0 to 10 carbon atoms, R⁴Is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. R³Examples of the hydrocarbon group of (3) include alkylene groups such as methylene and ethylene, and R⁴Examples of the hydrocarbon group of (2) include alkyl groups such as methyl and ethyl, and phenyl groups.

In the above formulae (3) and (4), R is¹Examples thereof include methyl group and ethyl group.

In the above formulae (3) and (4), Z is not particularly limited as long as it is a hydrolyzable group which can be hydrolyzed to form an Si-O-Si bond. Specific examples of such a hydrolyzable group include alkoxy groups such as methoxy, ethoxy, propoxy and butoxy, aryloxy groups such as phenoxy and naphthoxy, aralkyloxy groups such as benzyloxy and phenethyloxy, and acyloxy groups such as acetoxy, propionyloxy, butyryloxy, valeryloxy, pivaloyloxy and benzoyloxy. Among them, methoxy group and ethoxy group are preferably used.

Specific examples of the fluorine-based compound containing a fluorine-based functional group component having a perfluoroether structure represented by the above formula (3) or (4) include structures represented by the following formulae (19) to (27). In the following formulae (19) to (27), R is a methyl group or an ethyl group.

[ solution 6]

[ solution 7]

As described above, the fluorine-based compound contained in the liquid composition for forming a water-and oil-repellent film of the present embodiment has a perfluoroether group in which a plurality of short-chain perfluoroalkyl groups having 6 or less carbon atoms and perfluoroalkylene groups are bonded to oxygen atoms in the molecule, and has a high fluorine content in the molecule, and therefore can impart excellent water-and oil-repellency to the formed film.

[ carboxyl group-containing substance, etc. ]

The carboxyl group-containing substance is a polyolefin aqueous dispersion having a carboxyl group, a self-emulsion of an ethylene-vinyl acetate copolymer, or a self-emulsion of an ethylene-vinyl acetate-acrylic acid copolymer. Commercially available products of ethylene-vinyl acetate series include SEPOLSION VA406N, SEPOLSION VA407N (both manufactured by SUMITOMO CHEMICAL Co., Ltd.), Sumikaflex S-201HQ, S-465HQ, S-408HQE (both manufactured by SUMITOMO CHEMICAL Co., Ltd.), AQUATEX EC-1800 and EC-1200 (both manufactured by ジャパンコーティングレジン Co., Ltd.). Further, examples of commercially available polyolefin-based products having a carboxyl group include ZAIKTHENE a, ZAIKTHENE L, and ZAIKTHENE N (all manufactured by sumitomo chemical corporation), and examples of commercially available products having an ethylene-vinyl acetate-acrylic acid-based product include Sumikaflex S-900HL (manufactured by sumitomo chemical corporation).

[ Water-and oil-repellent film-forming liquid composition ]

The liquid composition for forming a water-and oil-repellent film according to the present embodiment is produced by the above production method, and contains (B) metal oxide particles to which the fluorine-based functional group component (a) is bonded, (C) a carboxyl group-containing substance, and the like, and (D) a solvent. The fluorine-based functional group component (A) has a perfluoroether structure represented by the general formula (1) or (2), and is contained in an amount of 0.3 to 5.0% by mass in the liquid composition for forming a water-and oil-repellent film, excluding the solvent (D). When the total amount of components other than the solvent (D) is set to 100% by mass, the water-and oil-repellent film-forming liquid composition contains (C) a carboxyl group-containing substance or the like in an amount of 10 to 70% by mass. Further, the total content of the fluorine-based functional group component (a) and the metal oxide particles (B) is 30 to 90% by mass in the liquid composition, assuming that the total amount of the components other than the solvent (D) is 100% by mass. Further, the mass ratio (A/B) of the fluorine-based functional group component (A) to the metal oxide particles (B) is in the range of 0.01 to 0.2. The solvent (D) is a solvent in which the content of a C1-4 alcohol, which is obtained by mixing water and a C1-4 alcohol, is 40% by mass or less. The content of the alcohol having 1 to 4 carbon atoms is set to 40 mass% or less for the sake of operational safety and storage stability of the liquid composition. In addition, by forming a mixed solvent of water and an alcohol having 1 to 4 carbon atoms, the drying rate is increased and the film forming property is improved. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 2-methyl-2-propanol.

Specific examples of the perfluoroether structure represented by the general formula (1) or the general formula (2) include structures represented by the formulae (19) to (27).

The liquid composition for forming a water-and oil-repellent film according to the present embodiment contains a carboxyl group-containing substance or the like as a main component in addition to a solvent, and further contains metal oxide particles, and therefore the strength of the water-and oil-repellent film is improved, and a high-strength water-and oil-repellent film which is excellent in adhesion to fibers of a nonwoven fabric and is difficult to peel can be obtained. Further, the liquid composition for forming a water-and oil-repellent film has an oil-repellent effect because it contains a fluorine-based functional group component having a perfluoroether structure represented by the general formula (1) or (2).

[ method of Forming Water-and oil-repellent film on fiber surface of nonwoven Fabric ]

In order to form a water-and oil-repellent film on the fiber surface of the nonwoven fabric of the present embodiment, a liquid is prepared by diluting a water-and oil-repellent film-forming liquid composition with a solvent prepared by mixing water and an alcohol having a boiling point of less than 120 ℃ and having 1 to 4 carbon atoms. The mixing ratio of water and alcohol (water: alcohol) in the solvent is 1: 0-5 by mass ratio. The mass ratio of the solvent to the liquid composition (liquid composition: solvent) is 1: 0.1-10. The nonwoven fabric is immersed in the thus prepared diluted solution, pulled out of the diluted solution, and developed on a horizontal wire mesh or the like in the atmosphere at room temperature, and then drained to a predetermined liquid amount. As another method, the lifted nonwoven fabric is shaken to remove excess liquid, or the lifted nonwoven fabric is subjected to liquid removal by a mangle roll (press). The nonwoven fabric subjected to liquid removal is dried in the atmosphere at a temperature of 25 to 140 ℃ for 0.5 to 24 hours. Thereby, as shown in the enlarged view at the center of fig. 2, the water-and oil-repellent film 21 is formed on the surface of the fiber 20c constituting the nonwoven fabric 20. When the amount of liquid removed is small, the water-and oil-repellent film is formed as a thick film on the fiber surface of the nonwoven fabric, and when the amount of liquid removed is large, the water-and oil-repellent film is formed as a thin film on the fiber surface of the nonwoven fabric.

Examples

Next, examples of the present invention will be described in detail together with comparative examples. First, synthetic examples 1 to 6 and comparative synthetic examples 1 to 3 for preparing an aqueous dispersion of fluorine-containing metal oxide particles will be described, and next, examples 1 to 8 and comparative examples 1 to 4 relating to the preparation of a liquid composition for forming a water-and oil-repellent film and the production of an oil-water separation filter using these synthetic examples and comparative synthetic examples will be described.

[ Synthesis examples 1 to 6 for preparing an aqueous dispersion of fluorine-containing metal oxide particles, and comparative Synthesis examples 1 to 3]

< Synthesis example 1 >

Adding an aqueous dispersion of silica having an average particle diameter of 5nm (ST-OXS, manufactured by Nissan chemical Co., Ltd., SiO)₂10%) to a 50.0g beaker, 0.08g of the fluorine-based compound represented by the above formula (19) was added and mixed. Subsequently, 0.005g of nitric acid was added thereto, and the mixture was mixed at 40 ℃ for 2 hours to obtain an aqueous dispersion of silica (silica) particles in which silica particles were bonded to a fluorine-containing compound (aqueous dispersion of fluorine-containing silica particles). The mass ratio (a/B) of the fluorine-based functional group component (a) to the silica as the metal oxide particles (B) was 0.01.

< Synthesis example 2 >

Adding an aqueous dispersion (ST-XS, Nissan chemical Co., Ltd., SiO) of silica having an average particle diameter of 45nm₂30%) to a 50.0g beaker, 0.45g of the fluorine-based compound represented by the above formula (20) was added and mixed. Then, 0.005g of nitric acid was added, and then an aqueous dispersion of silica (silica) particles (an aqueous dispersion of fluorine-containing silica particles) was obtained in the same manner as in Synthesis example 1. The mass ratio (A/B) was 0.03.

< Synthesis example 3 >

Adding an aqueous dispersion of silica having an average particle diameter of 80nm (ST-ZL, manufactured by Nissan chemical Co., Ltd., SiO)₂30%) was added to a 50.0g beaker, 0.75g of the fluorine-based compound represented by the above formula (21) was added and mixed. Then, 0.005g of nitric acid was added, and then an aqueous dispersion of silica (silica) particles (an aqueous dispersion of fluorine-containing silica particles) was obtained in the same manner as in Synthesis example 1. The mass ratio (A/B) was 0.05.

< Synthesis example 4 >

An aqueous dispersion of zirconium dioxide (SZR-W made by Sakai chemical Co., Ltd., ZrO) having an average particle diameter of 3nm was added₂Concentration 30%) in a 50.0g beaker,3.00g of the fluorine-containing compound represented by the above formula (27) was added thereto and mixed. Then, 0.009g of nitric acid was added thereto, and then an aqueous dispersion of zirconium dioxide particles (an aqueous dispersion of fluorine-containing zirconium dioxide particles) was obtained in the same manner as in Synthesis example 1. The mass ratio (a/B) of the fluorine-based functional group component (a) to zirconium dioxide as the metal oxide particles (B) was 0.19.

< Synthesis example 5 >

An aqueous dispersion of titanium dioxide (TKS-203, テイカ, TiO) having an average particle diameter of 6nm was added₂Concentration 20%) 0.30g of the fluorine-based compound represented by the above formula (27) was added to a 50.0g beaker and mixed. Subsequently, 0.001g of nitric acid was added, and then an aqueous dispersion of titanium dioxide particles (aqueous dispersion of fluorine-containing titanium dioxide particles) was obtained in the same manner as in Synthesis example 1. The mass ratio (a/B) of the fluorine-based functional group component (a) to the titanium dioxide as the metal oxide particles (B) was 0.03.

< Synthesis example 6 >

0.45g of the fluorine compound represented by the above formula (27) was added to a beaker to which 50.0g of an aqueous dispersion of zinc oxide having an average particle size of 25nm (30% ZnO, manufactured by MZ-500, テイカ) was added and mixed. Subsequently, 0.005g of nitric acid was added, and then an aqueous dispersion of zinc oxide particles (aqueous dispersion of fluorine-containing zinc oxide particles) was obtained in the same manner as in Synthesis example 1. The mass ratio (a/B) of the fluorine-based functional group component (a) to the zinc oxide as the metal oxide particles (B) was 0.03.

Comparative Synthesis example 1

An aqueous dispersion (R32 made by Sakai chemical Co., Ltd., made by Sakai chemical Co., Ltd.) containing titanium dioxide having an average particle diameter of 230nm was added₂30%) was added to a 50.0g beaker, 0.45g of the fluorine-based compound represented by the above formula (27) was added and mixed. Subsequently, 0.005g of nitric acid was added, and then an aqueous dispersion of titania particles (aqueous dispersion of fluorine-containing titania particles) was obtained in the same manner as in Synthesis example 1. The mass ratio (a/B) of the fluorine-based functional group component (a) to the titanium dioxide as the metal oxide particles (B) was 0.03.

Comparative Synthesis example 2

0.08g of the fluorine-containing compound represented by the above formula (27) was added to a beaker to which 50.0g of the same aqueous dispersion of silica as in Synthesis example 2 was added and mixed. Then, 0.005g of nitric acid was added, and then an aqueous dispersion of silica (silica) particles (an aqueous dispersion of fluorine-containing silica particles) was obtained in the same manner as in Synthesis example 1. The mass ratio (A/B) was 0.005.

Comparative Synthesis example 3

3.45g of the fluorine-containing compound represented by the above formula (27) was added to a beaker to which 50.0g of the same aqueous dispersion of silica as in Synthesis example 2 was added and mixed. Subsequently, 0.011g of nitric acid was added, and then an aqueous dispersion of silica (silica) particles (an aqueous dispersion of fluorine-containing silica particles) was obtained in the same manner as in synthesis example 1. The mass ratio (A/B) was 0.22.

The following table 1 shows the contents of the aqueous dispersions of the fluorine-containing metal oxide particles of synthesis examples 1 to 6 and comparative synthesis examples 1 to 3. In table 1, R in the fluorine-containing silanes represented by formulae (19) to (21) and (27) as the fluorine-containing compounds is ethyl.

[ examples 1 to 8 and comparative examples 1 to 4 for preparation of liquid composition for Forming Water-and oil-repellent film and production of oil-water separating Filter ]

< example 1 >

A liquid composition for forming a water-and oil-repellent film was prepared by mixing 10.57g of the aqueous dispersion of fluorine-containing silica particles obtained in Synthesis example 1, 5.00g of SEPOLSION VA406N (manufactured by Sumitomo Seiko Co., Ltd.) which is a self-emulsified liquid of 1 kind of ethylene-vinyl acetate copolymer such as a carboxyl group-containing substance, 513.13g of mixed water, and 789.43g of a solvent (AP-7, manufactured by Alcohol Co., Ltd., Japan) 276.30 g. The obtained water-and oil-repellent film-forming liquid composition (250.00 g) was diluted with 50.00g of a mixed solvent of water and an industrial alcohol (water: industrial alcohol: 1 by mass ratio) to prepare a diluted solution.

As a substrate of the oil-water separation filter, a laminate (two-layer nonwoven fabric) of a nonwoven fabric composed of glass fibers as an upper layer and a nonwoven fabric composed of PET fibers as a lower layer was used. The laminate had an air permeability of 2.1ml/m²In seconds. Immersing the two-layer nonwoven fabric in the above diluent, shaking off the excess liquid, drying at room temperature for 24 hours to obtain a nonwoven fabric having an air permeability of 2.00ml/cm²A second oil-water separation filter.

The contents are shown in tables 2 and 3 below.

Table 2 also shows "the content ratio of the fluorine-containing functional group component (a) in the liquid composition excluding the solvent", "the content ratio of the carboxyl group-containing substance or the like (C) in the liquid composition excluding the solvent", and "the content ratio of the fluorine-containing functional group component (a) and the metal oxide particles (B) in total in the liquid composition excluding the solvent". The content ratio (%) of the fluorine-containing functional group component (A) in the liquid composition other than the solvent is a percentage of { (A)/[ (A) + (B) + (C) ], when the content ratio of the carboxyl-containing substance (C) in the liquid composition other than the solvent is taken into consideration, the content ratio (%) of the carboxyl-containing substance (C) in the liquid composition other than the solvent is a percentage of { (C)/[ (A) + (B) + (C) ], and the content ratio (%) of the total of the fluorine-containing functional group component (A) and the metal oxide particles (B) in the liquid composition other than the solvent is a percentage of { [ (A) + (B) ]/[ (A) + (B) + (C) ], when the content ratio of the carboxyl-containing substance (C) in the liquid composition other than the solvent is taken into consideration.

< examples 2 to 8 and comparative examples 1 to 3 >

As shown in Table 2, in examples 2 to 6, the aqueous dispersions of the fluorine-containing metal oxide particles obtained in Synthesis examples 1 to 6 shown in Table 1 were used and the respective weights were determined. In example 7, the aqueous dispersion of the fluorine-containing metal oxide particles obtained in synthetic example 1 shown in table 1 was used, and the weight thereof was determined. In example 8, the aqueous dispersion of the fluorine-containing metal oxide particles obtained in synthetic example 2 shown in Table 1 was used, and the weight thereof was determined. In comparative examples 1 to 3, the aqueous dispersions of the fluorine-containing metal oxide particles obtained in comparative synthesis examples 1 to 3 shown in Table 1 were used, and the weights thereof were determined.

Sumikaflex S-408HQE (manufactured by Sumitomo chemical Co., Ltd.) as a self-emulsified liquid of an ethylene-vinyl acetate copolymer was used in examples 2 and 8, and SEPOLSION VA406N (manufactured by Sumitomo refining Co., Ltd.) as a self-emulsified liquid of an ethylene-vinyl acetate copolymer was used in examples 3 to 6 and comparative examples 1 to 3, and the respective weights were determined. In example 7, ZAIKTHENE a (manufactured by sumitomo chemical corporation) of a polyolefin aqueous dispersion having a carboxyl group was used, and the weight thereof was determined.

As the solvent, in examples 2 to 8 and comparative examples 1 to 3, a solvent obtained by mixing water and an industrial Alcohol (AP-7, manufactured by Alcohol industries, Japan) in the blending amount shown in Table 2 was used.

Thus, liquid compositions for forming water-and oil-repellent films of examples 2 to 8 and comparative examples 1 to 3 were prepared.

As shown in table 3, the air permeability of the nonwoven fabric before impregnation, the type of the base material of the oil-water separation filter, and the air permeability of the oil-water separation filter (after impregnation) were selected.

The nonwoven fabrics used in example 7 and comparative examples 2 and 3 were each a single-layer nonwoven fabric composed of a blend of PET fibers and glass fibers (PET: glass: 80:20 in terms of mass ratio) and had an air permeability of 9.5ml/cm before impregnation, unlike the nonwoven fabric of example 1²Second (example 7 and comparative example 2), 15.0ml/cm²Second (comparative example 3). The nonwoven fabric used in example 8 was a single-layer nonwoven fabric composed of polypropylene (PP) fibers, and had an air permeability of 14.0ml/cm before impregnation²In seconds.

Further, in the same manner as in example 1, the nonwoven fabric was immersed in the diluted liquid of the water-and oil-repellent film-forming liquid compositions obtained in examples 2 to 8 and comparative examples 1 to 3, respectively, and subjected to deliquoring and seeding, thereby obtaining oil-water separation filters of examples 2 to 8 and comparative examples 1 to 3 having the air permeabilities shown in table 3.

< comparative example 4 >

In comparative example 4, a liquid composition for forming a water-and oil-repellent film was obtained in the same manner as in example 1 described in patent document 1. Specifically, 8.52g of 3-to 5-mer (trade name: MKC シリケート MS51, manufactured by Mitsubishi chemical corporation) of Tetramethoxysilane (TMOS) as a silicon alkoxide, 0.48g of 3-glycidoxypropyltrimethoxysilane (GPTMS, manufactured by shin-Etsu chemical industries, trade name: KBM-403, manufactured by shin-Etsu chemical Co., Ltd.) as an ethoxysilane, 0.24g of a fluorine-containing silane (R: ethyl) represented by the following formula (29) as a fluorine-based compound, and 17.58g of ethanol (EtOH) (boiling point: 78.3 ℃ C.) as an organic solvent were mixed, 3.37g of ion exchange water was added thereto, and the mixture was stirred in a separable flask at 25 ℃ for 5 minutes to prepare a mixture. 0.05g of hydrochloric acid having a concentration of 35% by mass as a catalyst was added to the mixed solution, and the mixture was stirred at 40 ℃ for 2 hours. Thereby, a liquid composition for forming an oil-water separation film containing a silica sol hydrolysate was prepared. In the same manner as in example 1, the same nonwoven fabric as in example 1 was immersed in a dilution liquid of the water/oil repellent film-forming liquid composition to carry out deliquoring and seeding, thereby obtaining an oil-water separator having the characteristics shown in table 3.

[ solution 8]

< comparative test and evaluation >

The 11 types of oil-water separation filters obtained in examples 1 to 8 and comparative examples 1 to 4 were individually attached to the oil-water separation test apparatus 100 shown in fig. 5. In the test apparatus 100, 100 is added to each reference numeral of the element corresponding to the oil-water separator 10 shown in fig. 1, and each reference numeral of the test apparatus 100 is indicated. In the OIL-water separation test apparatus 100, as the emulsified OIL, 5 liters of ion-exchanged water was mixed with 0.25g of HISCREW OIL NEXT for hitachi machine screw compressor OIL at 9000rpm for 3 minutes, and the cloudy OIL concentration was 50ppm (a liquid containing water and OIL). The emulsified oil is supplied to the liquid inflow portion 112 and filtered by the oil-water separation filter 113. The filtrate 114 passed through the oil-water separation filter 113 and stored in the water reservoir (branched flask) 117 was collected, and the "(a) oil concentration of the filtrate", "(b) turbidity of the filtrate", and "(c) passage time of the filtrate" were evaluated by the following methods. The results are shown in Table 3. The oil-water separation filter 113 is supported by a metal sieve plate (mesh plate) 120. In addition, when filtering the emulsified oil, 12 types of oil-water separation filters obtained in examples 1 to 8 and comparative examples 1 to 4 were adjusted to a predetermined degree of vacuum (-10 kPa) by a suction pump, not shown, connected to a branch pipe 121 of a flask 117, and the inside of the flask was depressurized to suction-filter the oil-water separation filter 113. Reference numeral 122 is a vacuum gauge.

(a) Oil concentration of the filtrate

The oil concentration of the filtrate was measured by an oil content meter (OCMA-555, manufactured by horiba, Ltd.) to obtain the residual oil content of the filtrate. The detection limit of the oil content meter varied depending on the type of oil, and the emulsified oil used was 1 ppm. In table 3 and table 4 below, "oil concentration in filtrate" of "< 1" indicates that the detection limit of the oil content meter is not more than the detection limit.

(b) Turbidity of the filtrate

The turbidity of the filtrate was measured by using a Lacom Tester TN-100 (manufactured by アズワン). The smaller the turbidity, the better the oil-water separation, and the acceptable level was 1.5 or less.

(c) Passage time of filtrate

The time taken for the filtrate to pass through was measured from the time when the suction pump started to operate until the total amount of the emulsified oil passed through the oil-water separation filter 113 and reached the water reservoir (flask with branch) 117.

As is clear from table 3, the oil-water separator filter of comparative example 1 was produced by preparing a liquid composition for forming a water-and oil-repellent film from comparative synthesis example 1 containing metal oxide (titanium dioxide) particles having an average particle diameter of 230nm, immersing a nonwoven fabric in the liquid composition, and removing and drying the liquid composition, and therefore, the average particle diameter of the metal oxide particles was too large to bond the metal oxide particles to the fiber surface of the nonwoven fabric as a carboxyl group-containing substance or the like as a binder component. As a result, the oil concentration of the filtrate was not more than the detection limit of 1ppm, the turbidity of the filtrate was high and was 4.0, and the passing time of the filtrate was long and was 96 seconds, resulting in poor filtration efficiency.

In the oil-water separation filter of comparative example 2, the fluorine-based functional group component (a) in the water-and oil-repellent film was too small to be 0.005% by mass, and therefore, the oil repellency was poor, the passing time of the filtrate was as short as 40 seconds, the oil concentration of the filtrate was as high as 7.0ppm, and the turbidity of the filtrate was also as high as 2.0.

The oil-water separation filter of comparative example 3 had an excessively high air permeability, and therefore it was 15.0ml/cm²The water-and oil-repellent film had an excessively large amount of the fluorine-based functional group component (a) of 17.8 mass% and thus had poor adhesion to the nonwoven fabric, an extremely high oil concentration of 42.0ppm in the filtrate, and an extremely high turbidity of 5.0.

The oil-water separation filter of comparative example 4 had an appropriate air permeability of 2.1ml/cm²The oil concentration of the filtrate was below the detection limit of 1ppm, and the turbidity of the filtrate was 0.5. On the other hand, since the fluorine-based compound having the perfluoroamine structure of formula (29) was used, the fluorine-based compound of the oil-water separation filter of comparative example 4 had a rigid structure and was likely to exhibit strong water repellency, and therefore, compared to the oil-water separation filters of examples 1 to 8 containing the fluorine-based compound having the perfluoroether structure, the passage time of the filtrate was longer, 120 seconds, and the filtration efficiency was poor.

On the other hand, the oil-water separation filters of examples 1 to 8 satisfy the concept of the invention according to claim 1Therefore, the oil concentration of the filtrate was 1.3ppm (example 7) or 1.4ppm (example 8) or less, the turbidity of the filtrate was 0.5 or 1.1 (example 7) or 1.2 (example 8), and the passing time of the filtrate was 33 to 95 seconds, and the filtration efficiency was good. In example 8, the reason why the oil concentration of the filtrate was 1.4ppm and the turbidity of the filtrate was 1.2 was that the air permeability of the oil-water separation filter was large, and it was 13.1ml/cm²For the reason of/second.

Industrial applicability

The oil-water separation filter of the invention can be used in the field of separating oil from emulsified oil or water-soluble oil which is formed by emulsifying oil and recovering water.

Description of the symbols

13. 23 oil-water separation filter

20 nonwoven fabric

20a one side of nonwoven Fabric

20b other side of the nonwoven Fabric

20c fibers of nonwoven Fabric

Air holes of 20d non-woven fabric

21 Water-and oil-repellent film

21a fluorine-containing metal oxide particle

21b carboxyl group-containing substance and the like

22 oil particles.