JP6811565B2 - Laminated body and film structure including it - Google Patents

Description

The present invention relates to a laminate having a resin porous body and a fiber base material, and more particularly to a laminate suitable as a support for a separation membrane.

The separation membrane that separates a plurality of components contained in a liquid or gas is very thin in order to improve its permeation performance and separation performance. Therefore, the separation membrane alone has low mechanical strength, and a fiber base material is usually used as a support for the separation membrane. In this case, for example, a membrane structure supported by the fiber base material is formed by casting a solution of a polymer which is a raw material of the separation membrane on the fiber base material.

However, since the surface of the fiber base material is not smooth, it is difficult to form a thin and homogeneous separation film on the fiber base material. Therefore, a porous film is laminated on the fiber base material, and this laminated body is used as a support. At this time, the separation membrane is formed on the main surface of the porous membrane.

As a method of laminating a porous film on a fiber base material, a method of applying a solution of a resin which is a raw material of the porous film on the fiber base material (coating method), or a method of applying the porous membrane to the fiber base material with an adhesive. Examples thereof include a method of adhering and a method of heat-sealing a porous film to a fiber base material. Among them, the coating method is preferably used because the material is not limited and the air permeability of the fiber base material and the porous membrane is not easily impaired.

When a laminate of a fiber base material and a porous membrane is used as a support for a separation membrane, delamination is likely to occur between the fiber base material and the porous membrane due to the pressure applied during use. Therefore, there has been proposed a method of suppressing delamination by infiltrating at least a part of the resin, which is a raw material of the porous film, into the inside of the fiber base material at the time of coating (see Patent Documents 1 to 3). ).

Japanese Unexamined Patent Publication No. 2009-233666 Japanese Unexamined Patent Publication No. 09-313905 Japanese Unexamined Patent Publication No. 2014-094501

The smoothness of the porous membrane laminated on the fiber substrate is affected by the structure of the fiber substrate. For example, when a solution of a resin, which is a raw material for a porous film, is applied to a fiber base material having large voids, it is difficult to obtain a smooth porous film. This is because the solution permeates into the voids of the fiber base material, and dents are formed on the main surface of the solidified porous membrane so as to correspond to the voids. This dent is, for example, fine on the order of several microns to several tens of microns. However, since the separation membrane itself has a thickness on the order of several hundred microns, even fine irregularities can hinder the formation of the separation membrane thinly and uniformly.

The above dents can be reduced by applying the above solution in an amount sufficient to fill the voids in the fiber base material to the fiber base material. However, in this case, the air permeability of the obtained laminate is reduced. When this laminate is used as a support for the separation membrane, the permeation performance of the separation membrane deteriorates. It also increases costs.

When the resin, which is the raw material of the porous membrane, is sufficiently permeated into the fiber base material with an emphasis on suppressing delamination, the solution reaches the back surface of the fiber base material in the coating process of the solution. Back leakage is likely to occur. As a result, the manufacturing equipment is contaminated, resulting in deterioration of quality and productivity. Further, since the thickness of the porous film covering the main surface of the fiber base material tends to be non-uniform, it is difficult to obtain sufficient smoothness. As described above, it is difficult to simultaneously achieve the smoothness of the porous film, the suppression of delamination, and the air permeability of the laminate.

One aspect of the present invention includes a resin porous body and a fiber base material, and a part of the resin porous body forms a porous film covering one main surface of the fiber base material, and the resin. The other part of the porous body has entered the gaps of the fiber base material, the mass of the resin porous body is 1 to 35 g / m ² , and the thickness of the porous film is 1 to 100 μm. The present invention relates to a laminate in which the time from dropping dimethylformamide onto any main surface of a fiber substrate to being absorbed is 60 seconds or more.

The laminate according to the present invention has excellent smoothness of the porous film. Therefore, when this laminate is used as a support for the separation membrane, a thin and homogeneous separation membrane can be formed. Further, the laminate according to the present invention has excellent breathability and is less likely to cause delamination between the porous film and the fiber base material. Therefore, the separation membrane using this laminated body as a support is excellent in permeation performance and separation performance.

It is sectional drawing which shows typically the laminated body which concerns on one Embodiment of this invention. It is an image (magnification 1000 times) which took the main surface of the porous film of the laminated body obtained in Example 1 using a scanning electron microscope (SEM). It is an image (magnification 500 times) which took the cross section of the laminated body obtained in Example 1 using SEM. It is an image (magnification 1000 times) which took the main surface of the porous film of the laminated body obtained in the comparative example 2 using SEM.

The laminate of this embodiment includes a resin porous body and a fiber base material. As shown in FIG. 1, a part of the resin porous body 10 forms a porous film 11 covering one main surface (first main surface 20X) of the fiber base material 20, and the other part is a fiber group. It has entered the gap of the material 20. In other words, the laminate 100 includes a porous film 11 containing a part of the resin porous body 10 and a composite region 21 including the resin porous body 12 and the fiber base material 20 that have entered the gaps between the fiber base materials 20. ..

The gaps between the fiber base materials 20 include recesses formed on the first main surface 20X and gaps between the constituent fibers 20F constituting the fiber base material 20. Specifically, the gap between the fiber base materials 20 can be defined as follows, for example. First, the laminated body 100 is placed on a horizontal plane. Looking at the cross section of the laminated body 100 placed on the horizontal plane, the length of the constituent fibers 20F located on the most porous film 11 side of the fiber base material 20 in the normal direction of the horizontal plane is divided into four equal parts, and the first The region from the main surface 20X side to the length of 1/4 is referred to as the first region 20Fa, and the region other than the first region 20F is referred to as the second region 20Fb. Further, the boundary line between the first region 20Fa and the second region 20Fb is defined as the boundary line Lb. The gap between the fiber base materials 20 is located on the most porous film 11 side of the fiber base material 20, and is formed from a straight line L connecting the ends of the boundary lines Lb of the constituent fibers 20F adjacent to each other in the plane direction of the fiber base material 20. The area on the 20Y side of the second main surface. The porous film 11 is a resin porous body that contacts the outer edge of the first region 20F of the constituent fibers 20F located on the most porous film 11 side of the fiber base material 20.

(Fiber base material)
The fiber base material 20 functions as a support for the separation membrane and further as a support for the laminate 100. A porous film 11 is formed on the first main surface 20X of the fiber base material 20. The other main surface (second main surface 20Y) of the fiber base material 20 also has additional functions (eg, flexibility, adhesiveness, lubricity, anti-slip property, heat insulating property, hygroscopic property) in the laminate 100 or the separation membrane. Layers for imparting light-shielding properties, etc.) may be laminated.

Since the separation membrane is required to have high permeation performance, it is preferable that the fiber base material 20 as a support also has high air permeability and porosity. From these viewpoints, the fiber base material 20 is preferably a fiber structure such as a woven fabric, a knitted fabric, or a non-woven fabric. Of these, a non-woven fabric is preferable because a smooth porous film 11 is easily formed. In woven and knitted fabrics, the fibers are entwined and regularly arranged. Therefore, unevenness with a large head is likely to appear on the main surface, with the points where the fibers are entangled as convex portions and the gaps between the fibers as concave portions. When the raw material resin of the resin porous body 10 is applied to the main surface and solidified, the obtained porous film 11 is provided with a dent along the concave portion of the main surface of the fiber base material 20. On the other hand, in the non-woven fabric, since the fibers are randomly entangled with each other, the difference in unevenness of the main surface is smaller than that of the woven fabric or knitted fabric, and the non-woven fabric tends to be smooth. Therefore, the porous film 11 formed on the main surface thereof also tends to be smooth.

The method for producing the non-woven fabric is not particularly limited, but among them, the wet method and the electrospinning method are preferable in that a non-woven fabric having a main surface having a smooth and homogeneous structure can be easily obtained. The fiber base material 20 may have a single layer or a multi-layer structure. When the fiber base material 20 has a multilayer structure including a non-woven fabric, the non-woven fabric may be arranged in the outermost layer, and the porous film 11 may be formed on the non-woven fabric.

The thickness of the fiber base material 20 (when the fiber base material 20 has a multilayer structure, the total thickness) is not particularly limited. Considering the mechanical strength, the thicker the fiber base material 20, the more desirable it is. On the other hand, in consideration of lightness and miniaturization when the separation membrane is used, it is desirable that the fiber base material 20 is not excessively thick. From these viewpoints, the thickness of the fiber base material 20 is preferably 10 μm or more, and preferably 1000 μm or less. The thickness of the fiber base material 20 is more preferably 20 μm or more, and more preferably 400 μm or less. When the thickness of the fiber base material 20 is within this range, back leakage is easily suppressed when the raw material resin solution (raw material resin solution) is applied to the first main surface 20X of the fiber base material 20.

The material of the constituent fiber 20F constituting the fiber base material 20 is also not particularly limited, and examples thereof include a polyolefin resin, a polyester resin, and a polyamide resin. These may be used alone or in combination of two or more. Of these, polyester resin is preferable from the viewpoint of heat resistance. When the fiber base material 20 has a multi-layer structure, a plurality of fiber base materials 20 made of constituent fibers 20F made of different materials may be laminated. The fineness of the constituent fiber 20F is not particularly limited.

The separation membrane may be treated at a high temperature of about 75 to 125 ° C. for sterilization treatment or high temperature gas separation, for example. Therefore, the higher the melting point of the constituent fiber 20F, the more desirable it is. By using a fiber having a high melting point, deformation of the fiber base material 20 due to melting or softening of the constituent fiber 20F and clogging of the voids of the fiber base material 20 are suppressed, and the performance as a separation membrane is easily exhibited. The melting point of the constituent fiber 20F is preferably 150 ° C. or higher, more preferably 170 ° C. or higher, and particularly preferably 200 ° C. or higher. When the fiber base material 20 has a multilayer structure, it is preferable that the melting points of the constituent fibers 20F constituting each layer satisfy the above ranges.

The higher the air permeability (Frazil air permeability) measured by the Frazier method (JIS L 1913 Frazier method) of the fiber base material 20, the more desirable it is from the viewpoint of the permeation performance of the separation membrane. On the other hand, from the viewpoint of forming a homogeneous porous film 11 on the first main surface 20X of the fiber base material 20, it is desirable that the air permeability is not excessively high. From these viewpoints, it is preferable that the Frazier air permeability is 0.2~20cm ³ / cm ² / sec, more preferably 0.5~10cm ³ / cm ² / sec, 0.5 to 3 cm ³ It is particularly preferably / cm ² / sec. When the fiber base material 20 has a multilayer structure, it is preferable that the air permeability of the entire fiber base material 20 satisfies the above range. Further, when the Frazier air permeability is within this range, when the raw material resin solution is applied to the first main surface 20X of the fiber base material 20, back leakage of the raw material resin solution is likely to be suppressed.

The higher the porosity of the fiber base material 20, the more desirable it is from the viewpoint of the permeation performance of the separation membrane. On the other hand, it is desirable that the porosity of the fiber base material 20 is not excessively high in that a homogeneous porous film 11 is easily formed on the first main surface 20X of the fiber base material 20. From these viewpoints, the porosity of the fiber base material 20 is preferably 10 to 45%. The upper limit of the porosity is more preferably 40%, and the lower limit of the porosity is more preferably 25%. When the fiber base material 20 has a multilayer structure, it is preferable that each layer satisfies the above range.

The void ratio (%) of the fiber base material 20 is the mass W (g / cm ² ) per unit area of the fiber base material 20, the thickness WT (cm) of the fiber base material 20, and the specific gravity d of the constituent fibers 20F ( From g / cm ³ ), it can be calculated by the following formula (1).
(Equation 1) Porosity = (1- (W / WT) / d) x 100

The porosity of the fiber base material 20 may be calculated after removing a material other than the fiber base material 20 (for example, the resin porous body 10) from the laminate 100. Examples of the method for removing the material other than the fiber base material 20 from the laminate 100 include peeling and a method of immersing the fiber base material 20 in a solvent in which the other materials are dissolved although the fiber base material 20 is not dissolved. When the specific gravity of the constituent fiber 20F is unknown, the fiber base material 20 may be formed into a flat plate by melting with heat, and then the volume and mass thereof may be measured to calculate the specific gravity.

A part of the raw material resin of the resin porous body 10 applied to the fiber base material 20 is arranged so as to cover the first main surface 20X of the fiber base material 20, and the other part is placed in the gap of the fiber base material 20. In order to arrange the fibers, it is desirable that the permeability of the raw material resin solution to the fiber base material 20 is not excessively high. The permeability of the raw material resin solution to the fiber base material 20 is evaluated as, for example, the time from dropping the solvent of the raw material resin solution (usually an organic solvent, for example, dimethylformamide) onto the fiber base material 20 until it is absorbed. it can. The longer the time, the lower the affinity between the fiber base material 20 and the raw material resin solution, and the lower the permeability of the raw material resin solution to the fiber base material 20.

In the present embodiment, the fiber base material 20 has a time from dropping dimethylformamide (DMF) onto any main surface of the fiber base material 20 until it is absorbed (hereinafter, DMF absorption time) for 60 seconds or more. Use. The fiber base material 20 works in a direction of suppressing the penetration of the raw material resin solution. Therefore, when the solvent is removed from the applied raw material resin solution, the resin porous body 10 is arranged in the gaps between the fiber base materials 20 and also covers one main surface of the fiber base material 20. Such a fiber base material 20 is particularly preferably used as a support for a separation membrane (for example, a gas separation membrane) in which the affinity between the fiber base material 20 and the organic solvent has little effect on the permeation performance.

For the DMF absorption time, a material other than the fiber base material 20 (for example, the resin porous body 10) was removed from the laminate 100 by the same method described as the method used when calculating the porosity of the fiber base material 20. Later, it may be calculated. In this case, the DMF absorption time may be measured by dropping DMF on the first main surface 20X of the fiber base material 20 or dropping DMF on the second main surface 20Y. When measuring the DMF absorption time in the state of the laminated body 100, DMF is dropped on the second main surface 20Y side. When the fiber base material 20 has a multilayer structure, the DMF absorption time may be measured by exposing the main surface of any of the intermediate layers (intermediate layer) by peeling or the like.

When the DMF absorption time of the first main surface 20X is 60 seconds or more, when the raw material resin solution is applied to the first main surface 20X of the fiber base material 20, a part of the raw material resin solution penetrates into the gaps of the fiber base material 20. However, the other part stays on the first main surface 20X. When the DMF absorption time of the second main surface 20Y (or the main surface of the intermediate layer in the case of a multilayer structure) is 60 seconds or more, when the raw material resin solution is applied to the first main surface 20X of the fiber base material 20, the raw material is obtained. Although a part of the resin solution penetrates into the gaps of the fiber base material 20, it is held back by the second main surface 20Y (or the main surface of the intermediate layer). Therefore, as a result, the other part stays on the first main surface 20X to form the porous film 11. It is preferable that the DMF absorption time of at least the first main surface 20X is 60 seconds or more in that the porous film 11 is more easily formed. From the viewpoint of increasing the peel strength, it is preferable that the DMF absorption time of the second main surface 20Y is 60 seconds or more. In either case, the DMF absorption time is preferably 300 seconds or longer.

In order to lengthen the DMF absorption time, the difference between the surface energy of the fiber base material 20 and the surface free energy of the organic solvent may be increased. Specific methods thereof include a method of applying a fluororesin (water and oil repellent) to the fiber base material 20, a method of forming the fiber base material 20 with fibers containing a fluororesin, and a method of applying a hydrophilic substance to the fiber base material 20. Examples thereof include a method of applying the fiber base material 20 and a method of applying a plasma treatment to the fiber base material 20. These methods may be appropriately selected depending on the intended use of the separation membrane. For example, when hydrophilicity is required as a separation membrane, it is preferable that the fiber base material 20 as a support thereof is also hydrophilic. Therefore, among the above methods, it is preferable to adopt a method of imparting a hydrophilic substance to the fiber base material 20 or a method of subjecting the fiber base material 20 to plasma treatment. Further, the fluorine-containing resin is preferable because it has a low surface free energy and a high effect of lowering the affinity with an organic solvent. When the above treatment is performed, the DMF absorption time is measured with respect to the fiber base material 20 after the above treatment.

(Resin porous body)
The resin porous body 10 has a large number of continuous pores. A part of the resin porous body 10 is arranged as a porous film 11 formed on the first main surface 20X of the fiber base material 20, and the other part enters the gap of the fiber base material 20 to form fibers. A composite region 21 with the base material 20 is formed.

The thickness of the porous membrane 11 is 1 μm or more. In other words, the minimum thickness of the porous membrane 11 is 1 μm. As a result, the unevenness caused by the structure of the fiber base material 20 is reduced, and the smoothness of one main surface of the laminate 100 is improved. On the other hand, the composite region 21 causes an anchor effect, the peel strength between the porous film 11 and the fiber base material 20 is physically increased, and delamination between the porous film 11 and the fiber base material 20 is suppressed. To. The minimum thickness of the porous film 11 is preferably 3 μm or more in that the main surface of the laminate 100 is easily smoothed. On the other hand, the minimum thickness of the porous membrane 11 is preferably 100 μm or less, and more preferably 50 μm or less, in that the air permeability of the fiber base material 20 (and thus the permeation performance of the separation membrane) is not easily impaired. preferable. The entire first main surface 20X of the fiber base material 20 is not limited to being covered with the porous film 11, and in the present embodiment, a part of the first main surface 20X of the fiber base material 20 is exposed. Including.

The minimum thickness of the porous film 11 is calculated from the cross section of the laminated body 100. Specifically, in an SEM image taken by magnifying a predetermined size of a cross section of the laminate 100 (for example, about 250 μm × about 180 μm) at a magnification of 500 times, the surface of the porous film 11 is transferred to the fiber base material 20. Toward, a point (minimum point) where the length from the surface of the porous film 11 to the boundary line Lb is minimized when a straight line parallel to the normal line of the porous film 11 is drawn is determined, and the length is determined. To measure. When there is a portion where the fiber base material 20 is exposed from the porous membrane 11, this portion is the minimum point, and the length thereof is 0. The minimum points are determined for each of the 10 different cut surfaces, the lengths thereof are measured, and the average value thereof is taken as the minimum thickness of the porous membrane 11.

In the composite region 21, the resin porous body 10 may not uniformly penetrate into the entire fiber base material 20, and a region that does not contain the resin porous body 10 may be formed. It is preferable that the resin porous body 10 is not exposed from the main surface (second main surface 20Y of the fiber base material 20) of the laminate 100 on the side opposite to the porous film 11. That is, it is preferable that a region (fiber region 22) that does not contain the resin porous body 10 is formed on the second main surface 20Y side of the fiber base material 20. This is because the air permeability of the laminated body 100 is enhanced.

The mass of the resin porous body 10 contained in the laminated body 100 is as small as ¹ to 35 g / m ² . Therefore, the air permeability of the fiber base material 20 is not easily impaired. Since the fiber base material 20 has low permeability of the raw material resin solution as described above, the porous film 11 is formed on the first main surface 20X of the fiber base material 20 even with such a small amount. .. The mass of the resin porous body 10 contained in the laminated body 100 is preferably 4 g / m ² or more in that a homogeneous porous film 11 is easily formed, and 25 g / m in that the air permeability is less likely to be impaired. It is preferably ² or less. Further, when the mass of the resin porous body 10 contained in the laminated body 100 is within the above range, the cost is suppressed and the stress generated by the aggregation of the raw material resin during the production of the laminated body 100 is reduced. Deformation (curl) of the laminated body 100 is suppressed.

The mass of the resin porous body 10 contained in the laminated body 100 may be measured after removing a material other than the resin porous body 10 (for example, the fiber base material 20) from the laminated body 100. Examples of the method for removing the material other than the resin porous body 10 from the laminate 100 include peeling or a method of immersing the resin porous body 10 in a solvent in which the other materials are dissolved although the resin porous body 10 is not dissolved. .. Alternatively, the mass of the resin porous body 10 contained in the laminated body 100 may be calculated by quantitatively analyzing the amount of the component of the resin porous body 10 in the solution after dissolving all the laminated body 100. Alternatively, after measuring the mass of the laminated body 100, the mass of the material other than the resin porous body 10 obtained by removing the resin porous body 10 from the laminated body 100 is measured, and the resin contained in the laminated body 100 is measured from the difference. The mass of the porous body 10 may be determined.

The raw material resin of the resin porous body 10 is not particularly limited as long as a film can be formed on the fiber base material 20, and for example, a polyimide resin, a polyamideimide resin, a polyethersulfone resin, a polyetherimide resin, a polycarbonate resin, a polyphenylene sulfide resin, etc. Examples thereof include liquid crystal polyester resin, aromatic polyamide resin, polyamide resin, polybenzoxazole resin, polybenzoimidazole resin, polybenzothiazole resin, polysulfone resin, cellulose resin, polyurethane resin, acrylic resin and the like. These resins may be used alone or in admixture of two or more. Further, the copolymers of the above resins (graft polymer, block copolymer, random copolymer, etc.) may be used alone or in combination of two or more. Further, a polymer containing the skeleton (polymer chain) of the resin in the main chain or the side chain may be used. Of these, polysulfone resins and polyethersulfone resins are preferable because they have excellent heat resistance and easily form the porous film 11.

As described above, since the separation membrane may be treated at a high temperature of about 75 to 125 ° C., it is desirable that the melting point of the resin porous body 10 is also high. By using the resin porous body 10 having a high melting point, deformation due to melting or softening of the resin porous body 10 and clogging of pores are suppressed, and the performance as a separation membrane is easily exhibited. The melting point of the resin porous body 10 is preferably 150 ° C. or higher, more preferably 170 ° C. or higher, and particularly preferably 200 ° C. or higher. When the raw material resin has a glass transition temperature, the glass transition temperature of the raw material resin is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, from the same viewpoint.

The arithmetic average roughness Ra of the main surface 100X on the porous film 11 side of the laminated body 100 is preferably 1.3 μm or less, and more preferably 1 μm or less. This makes it easy to form a thin separation film on the main surface 100X with a uniform thickness. Therefore, the separation performance and the permeation performance of the obtained separation membrane are improved. The arithmetic mean roughness Ra is an index showing the smoothness of the surface, and the smaller the value, the higher the smoothness. The arithmetic mean roughness Ra can be measured by a contact type surface roughness measuring machine according to JIS B 0601. When the porous film 11 is peeled off from the laminated body 100 and the arithmetic average roughness Ra of the main surface facing the laminated body 100 is measured, it greatly exceeds 1.3 μm. This indicates that a part of the resin porous body 10 has entered the gap of the fiber base material 20.

The higher the porosity of the resin porous body 10 (particularly the porous membrane 11), the more desirable it is from the viewpoint of the permeation performance of the separation membrane. On the other hand, in terms of improving the smoothness of the porous membrane 11, it is desirable that the porosity of the porous membrane 11 is not excessively high. From these viewpoints, the porosity of the porous membrane 11 is preferably 50 to 95%. The upper limit of the porosity of the porous membrane 11 is more preferably 90%, and the lower limit is more preferably 60%.

The porosity of the porous film 11 is the mass W2 (g / cm ² ) per unit area of the porous film 11 after peeling the porous film 11 from the laminate 100, and the thickness WT2 (thickness WT2) of the porous film 11. It can be calculated by the above formula (1) using cm) and the specific gravity d2 (g / cm ³ ) of the raw material resin. When the specific gravity of the raw material resin is unknown, the raw material resin may be formed into a flat plate by melting with heat, and then the volume and mass thereof may be measured to calculate the specific gravity. The thickness WT2 of the porous film 11 can be measured by a thickness meter.

(Laminate)
The peel strength between the fiber base material 20 (strictly speaking, the composite region 21) and the porous film 11 of the laminate 100 having the above structure is, for example, 0.15 N / cm or more, and 0. 2N / cm or more is preferable, and 0.4N / cm or more is more preferable. When the peel strength is in this range, when the laminate 100 is used as a support for the separation membrane, interfacial peeling due to the pressure applied when the substance to be separated is permeated is suppressed. The peel strength can be measured as follows according to JIS L 1086. First, the hot melt tape is adhered to the main surface of the porous film 11 opposite to the fiber base material 20. When the hot melt tape and the fiber base material 20 are pulled at a constant speed with a tensile tester so that the hot melt tape and the fiber base material 20 are always at an angle of 180 °, and the porous film 11 and the fiber base material 20 are peeled off. Measure the load of. The peel strength is calculated by dividing this load by the width of the hot melt tape.

The air permeability (hereinafter referred to as “Gale air permeability”) measured by the Gale method (JIS L 1913 Gale method) of the laminate 100 is 1 to 1000 seconds / 100 ml from the viewpoint of the permeation performance of the separation membrane. preferable. The Gale air permeability is more preferably 5 seconds / 100 ml or more, and more preferably 800 seconds / 100 ml or less. When the Gale air permeability is within this range, the permeation performance of the separation film can be sufficiently exhibited without inhibiting the permeation of the substance to be separated, while the separation film is formed on the surface of the porous film 11 of the laminate 100. At that time, it is suppressed that the raw material of the separation film permeates the laminate 100, and a more homogeneous separation film is easily formed. The smaller the Gale air permeability, the higher the air permeability.

(Manufacturing method of laminated body)
The laminate 100 as described above includes, for example, a step of preparing the fiber base material 20, a step of preparing a raw material resin solution, and a step of applying the raw material resin solution to the first main surface 20X of the fiber base material 20. It is produced by a method including (coating step) and a step of removing the solvent of the applied raw material resin solution (solvent removing step).

In the solvent removing step, the raw material resin applied to the fiber base material 20 is solidified (or solidified), and a large number of pores are formed in the raw material resin. The method of forming pores in the raw material resin is roughly classified into a dry film forming method and a wet film forming method. The dry film-forming method is a method of removing the solvent by drying, and a large number of pores are formed as the solvent of the raw material resin solution evaporates. In the wet film forming method, the fiber base material 20 coated with the raw material resin solution is immersed in a coagulating solution containing a poor solvent of the raw material resin to replace the poor solvent with the solvent, thereby coagulating the raw material resin and at the same time. This is a method for removing a solvent. Finally, by removing the poor solvent, a resin porous body 10 having a large number of pores can be obtained.

The method of applying the raw material resin solution to the first main surface 20X of the fiber base material 20 is not particularly limited, and for example, a method of discharging the raw material resin solution from the die in a film form (die casting method), the first main surface 20X. A method of applying a resin solution and scraping off excess with a knife (knife coating method), a method of abutting the first main surface 20X on the roll while supplying the raw material resin solution onto the roll, and rolling the raw material resin solution. There is a method of transferring from to the first main surface 20X (roll coating method).

The solvent for dissolving the raw material resin of the resin porous body 10 may be appropriately selected depending on the compatibility with the raw material resin and the porosity. For example, when a polysulfone resin or a polyethersulfone resin is used as the raw material resin, DMF, dimethylacetamide, methylpyrrolidone and the like are preferably used as the solvent.

The concentration of the raw material resin is not particularly limited. Among them, the concentration of the raw material resin is preferably 35% by mass or less, more preferably 25% by mass or less, in that the porous film 11 having a porosity in the above range is easily formed. On the other hand, the concentration of the raw material resin is preferably 10% by mass or more, more preferably 12% by mass or more, in that the smoothness of the porous film 11 is improved.

The viscosity of the raw material resin solution is preferably high in that excessive penetration into the fiber base material 20 is suppressed and a homogeneous porous film 11 is easily formed on the first main surface 20X. On the other hand, it is desirable that the viscosity of the raw material resin solution is not excessively high in that the raw material resin easily enters the gaps between the fiber base materials 20. Considering these points, the viscosity of the raw material resin solution when measured at room temperature (20 to 25 ° C.) at a rotation speed of 12 rpm using a B-type viscometer is preferably 100 mPa · s or more and 20000 mPa · s or less. Among them, the viscosity of the raw material resin solution is more preferably 300 mPa · s or more, and particularly preferably 700 mPa · s or more. Further, the viscosity of the raw material resin solution is more preferably 10,000 mPa · s or less. If the viscosity of the raw material resin solution is too low, the raw material resin solution permeates to the surface (second main surface 20Y) opposite to the coating surface of the fiber base material 20 during the coating process and leaks back. In some cases. When the raw material resin solution leaks back, the coating apparatus is contaminated, and the raw material resin adhering to the fiber base material 20, particularly the raw material resin remaining on the first main surface 20X of the fiber base material 20, is reduced, so that the desired lamination is performed. It becomes difficult to obtain body 100. The viscosity of the raw material resin solution can be controlled by the concentration of the raw material resin and the addition of a thickener.

As described above, when a fluorine-containing resin or a hydrophilic substance (hereinafter collectively referred to as an absorption time extending material) is applied to the fiber base material 20, and / or when plasma treatment is applied to the fiber base material 20, the absorption time is extended. A material application step or a plasma treatment step (hereinafter collectively referred to as an absorption time extension step) is performed before the coating step. The method of applying the absorption time extending material to the fiber base material 20 is not particularly limited, and examples thereof include a method of immersing the fiber base material 20 in an aqueous solution of the absorption time extending material, drying and heating the fiber base material 20.

(Membrane structure)
The membrane structure includes the laminated body 100 and a separation membrane having a separation function. The laminate 100 functions as a support for the separation membrane. The material of the separation membrane is not particularly limited, and conventionally known materials may be used depending on the intended purpose.

Specific examples of the separation membrane include a dust collection filter, an air conditioning filter, a nanofiltration membrane, a reverse osmosis membrane, a forward osmosis membrane, a permeation vaporization membrane and a gas separation membrane (for example, a carbon dioxide separation membrane, a hydrogen separation membrane, and an oxygen enrichment membrane). , Oxygen permeable membrane, etc.) can be exemplified. Among them, it is preferable that the substance to be separated does not contain the organic solvent because the laminate 100 of the present embodiment has a reduced affinity with the organic solvent. In addition, when a fluorine-containing resin is used as the absorption time extending material, the affinity for water is also reduced. Therefore, the laminated body 100 is particularly suitable as a support for a gas separation membrane such as a dust collecting filter and an air conditioning filter.

[Example]
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. The performance in the examples was evaluated according to the following methods (1) to (8).

(1) DMF absorption time DMF was placed in the burette, and the tip of the burette was adjusted to a height of 1 cm from the first main surface of the fiber base material. A drop of DMF was dropped from the burette, and the time from the drop until the drop was absorbed by the fiber substrate, the specular reflection disappeared, and only the wetness remained was measured. When the measurement time exceeded 300 seconds, the measurement was stopped and the measurement time was set to 300 seconds or more. The same test was performed 5 times by changing the location of the fiber base material, and the average value of the measurement times was calculated. In the examples, the fiber base material before the resin porous body was applied was used. The same applies to the evaluations (2) and (7) described later.

(2) Porosity of the fiber base material The fiber base material was cut into a size of 20 cm × 20 cm and used as a sample. The thickness of any 10 points of the sample was measured with a thickness gauge and averaged to obtain the thickness of the sample. Further, the mass of the sample was measured with an electronic balance, the mass per area was calculated, and the porosity was calculated by the above formula 1. In the examples, since a non-woven fabric made of polyethylene terephthalate was used as the fiber base material, a specific gravity of 1.36 g / cm ³ was used.

(3) Arithmetic mean roughness Ra of the main surface of the laminate on the porous film side
The arithmetic surface roughness Ra of the main surface of the laminated body on the porous film side was measured using a surface roughness measuring machine (Surftest Extreme SV-3000CNC, manufactured by Mitutoyo Co., Ltd.). The measurement was performed on any 5 points, and the average value was calculated. When the arithmetic surface roughness Ra was 0.1 μm or more and 2 μm or less, the measurement was performed with a cutoff length of 0.8 mm, a measurement length of 5 mm, and a bandwidth of 2.67 μm. When the arithmetic surface roughness Ra was larger than 2 μm and 10 μm or less, the measurement was performed with a cutoff length of 2.5 mm, a measurement length of 15 mm, and a bandwidth of 8.33 μm.

(4) Peeling strength The laminate was cut into 30 mm × 100 mm, and five samples were prepared. A hot melt tape having a width of 25 mm and a length of 90 mm was attached to the main surface of the sample porous membrane opposite to the fiber base material, and heated at 120 ° C. for 24 seconds for adhesion. One end of the porous film was peeled off together with the hot melt tape by 50 mm, and the short side of the hot melt tape and the fiber base material were sandwiched between the clamps of the tensile tester (grasping interval 50 mm). The clamps were separated at a tensile speed of 100 mm / min until the hot melt tape and the fiber substrate were separated by 50 mm. The load applied from the start of peeling to the peeling of 50 mm was measured, and the average value was calculated. The average value was calculated by calculating the average value of a total of 6 points, 3 points sequentially from the point where the maximum value of the load was large, and 3 points sequentially from the point where the maximum value of the load was small. The same measurement was performed on 5 samples, and the average value of these was taken as the peel strength. If the porous membrane and the hot melt tape were peeled off before the porous membrane and the fiber base material were peeled off, the peeling strength was considered to be at least the upper limit of measurement.

(5) Gale Air Permeability The air permeability of the laminated body was measured by the Gale method according to JIS L 1913.

(6) Mass of resin porous body The fiber base material was cut into 20 cm × 20 cm, and three samples were prepared. The mass of each sample was measured and the average value was calculated. Separately, a laminate was prepared using the same fiber base material, and the laminate was cut into a size of 20 cm × 20 cm to obtain three samples. Each mass was measured and each average value was calculated. Dividing the difference between the average mass of the laminate and the average mass of the fiber substrate by the area of the laminate (0.04 m ² ), the average mass of the resin porous body per unit area (g / m ² ) Was calculated.

(7) Frazier air permeability The air permeability of the fiber base material was measured by the Frazier method according to JIS L 1913.

(8) Viscosity measurement The viscosity of the raw material resin solution was measured at a rotation speed of 12 rpm using a B-type viscometer (model number BM type, manufactured by Tokyo Keiki Seisakusho Co., Ltd.). The measurement temperature was 22 ° C.

(9) Thickness of Porous Membrane The laminated body was cut in the direction perpendicular to the surface to prepare a cross-section observation sample. Cross-section observation The cross section (about 250 μm × about 180 μm) of the sample was photographed with a scanning electron microscope (trade name “S-3000N”, manufactured by Hitachi High-Technologies Corporation) at a magnification of 500 times, and the obtained SEM image was obtained. I imported it to my computer. The point where the length from the surface of the porous membrane to the fiber substrate is minimized (minimum point) when a straight line parallel to the normal of the porous membrane is drawn from the surface of the porous membrane toward the fiber substrate. ) Was determined and its length was measured. When there was a part where the fiber base material was exposed from the porous membrane, the measured value was set to 0. For each of the 10 different cut surfaces, the minimum point was determined, the length was measured, and the average value of these was calculated.

[Example 1]
(1) Preparation of Fiber Base Material As the fiber base material, a non-woven fabric made of polyethylene terephthalate (melting point 260 ° C.) manufactured by a wet method was used. The porosity of the non-woven fabric was 39%, the thickness was 90 μm, and the Frazier air permeability was 1.09 cm ³ / cm ² / sec.

(2) Addition of absorption time extension material (absorption time extension step)
Next, the fiber base material was immersed in an aqueous solution adjusted to 2% by mass of a fluorine-containing water and oil repellent (NK Guard S-07, manufactured by NICCA CHEMICAL CO., LTD.), 4% by mass of isopropanol, and 94% of water, and then the mangle was added. Squeezed using. Subsequently, it was heated at 120 ° C. for 30 seconds to dry, and then heat-treated at 170 ° C. for 1 minute to attach a water-repellent oil-repellent agent to the inside of the fiber base material.

(3) Preparation of Raw Material Resin Solution Polyether sulfone (glass transition temperature 225 ° C.) was dissolved in DMF to prepare a raw material resin solution having a raw material resin concentration of 22% by mass. The viscosity of the raw material resin solution at 22 ° C. and 12 rpm was 2250 mPa · s.

(4) Coating Step The obtained raw material resin solution was coated on the fiber base material with an applicator having a gap of 50 μm. Next, this fiber base material was immersed in a coagulation bath using water as a coagulation liquid to solidify the raw material resin to obtain a laminate.

The physical characteristic values of the prepared fiber base material, the raw material resin solution, and the obtained laminate were evaluated according to the above evaluation method. The results are summarized in Table 1. An SEM photograph (magnification of 1000 times) of the surface of the porous film is shown in FIG. Further, an SEM photograph (magnification of 500 times) of a cross section of the laminated body is shown in FIG. The porous membrane is visible above FIG.

Although the amount of the raw material resin solution applied was small, the fiber base material having a long DMF absorption time was used, so that a homogeneous and sufficiently thick porous film was formed on the first main surface of the fiber base material. Since the peel strength is also sufficiently high, it can be seen that a composite layer of the resin porous body and the base fiber is formed. In addition, the composite layer could be confirmed from the cross-sectional photograph. This laminated body had a small value of Gale air permeability and high surface smoothness. Further, since polyethylene terephthalate is used as the material of the non-woven fabric and polyether sulfone is used as the raw material of the resin porous body, this laminate can be used even under high temperature conditions of about 200 ° C.

[Example 2]
Same as Example 1 except that a non-woven fabric having a porosity of 33%, a thickness of 90 μm, and a Frazier air permeability of 0.73 cm ³ / cm ² / sec (a polyethylene terephthalate non-woven fabric manufactured by a wet method) was used as the fiber base material. The laminate was obtained and evaluated. The results are summarized in Table 1.

Although the amount of the raw material resin solution applied was small, the fiber base material having a long DMF absorption time was used, so that a homogeneous and sufficiently thick porous film was formed on the first main surface of the fiber base material. Since the peel strength is also sufficiently high, it can be seen that a composite layer of the resin porous body and the base fiber is formed. In addition, the composite layer could be confirmed from the cross-sectional photograph. This laminated body had a small value of Gale air permeability and high surface smoothness. In Example 2, the porosity of the fiber base material is smaller than that in Example 1, but the formed porous film is thin. This is considered to be due to the difference in the structure of the fiber base material.

[Example 3]
A laminate was obtained and evaluated in the same manner as in Example 1 except that the concentration of the raw material resin in the raw material resin solution was 18% by mass. The results are summarized in Table 1. Since the concentration of the raw material resin in the raw material resin solution was low, the value of Gale air permeability was smaller than that of Example 1. A homogeneous and sufficiently thick porous film was formed on the first main surface of the fiber base material. On the other hand, from the peel strength, it can be seen that a composite layer of the resin porous body and the base fiber is formed. In addition, the composite layer could be confirmed from the cross-sectional photograph.

[Example 4]
A laminate was obtained and evaluated in the same manner as in Example 2 except that the concentration of the raw material resin in the raw material resin solution was 18% by mass. The results are summarized in Table 1. Since the concentration of the raw material resin in the raw material resin solution was low, the value of Gale air permeability was smaller than that of Example 2. A homogeneous and sufficiently thick porous film was formed on the first main surface of the fiber base material. On the other hand, from the peel strength, it can be seen that a composite layer of the resin porous body and the base fiber is formed. In addition, the composite layer could be confirmed from the cross-sectional photograph.

[Example 5]
A laminate was obtained and evaluated in the same manner as in Example 2 except that the concentration of the raw material resin in the raw material resin solution was 20% by mass. The results are summarized in Table 1. Since the concentration of the raw material resin in the raw material resin solution was low, the value of Gale air permeability was smaller than that of Example 2. A homogeneous and sufficiently thick porous film was formed on the first main surface of the fiber base material. On the other hand, from the peel strength, it can be seen that a composite layer of the resin porous body and the base fiber is formed. In addition, the composite layer could be confirmed from the cross-sectional photograph.

[Example 6]
In the coating step, a laminate was obtained and evaluated in the same manner as in Example 5 except that the gap of the applicator was changed to 150 μm. The results are summarized in Table 1. Since the amount of the raw material resin solution applied was large, the porous film became thicker as compared with Example 5. Therefore, the surface smoothness of the laminated body on the porous film side is improved. From the peel strength, it can be seen that a composite layer of the resin porous body and the base fiber is formed. In addition, the composite layer could be confirmed from the cross-sectional photograph.

[Comparative Example 1]
Same as Example 1 except that a non-woven fabric having a porosity of 66%, a thickness of 130 μm, and a Frazier air permeability of 28.96 cm ³ / cm ² / sec (a polyethylene terephthalate non-woven fabric manufactured by a wet method) was used as the fiber base material. The laminate was obtained and evaluated. The results are summarized in Table 1. Although a porous film was formed on the first main surface of the fiber base material, the first main surface was highly exposed and the surface smoothness of the laminate on the porous film side was low. It is considered that this is because the porosity of the fiber base material was excessively high.

[Comparative Example 2]
Same as Example 1 except that a non-woven fabric having a porosity of 48%, a thickness of 85 μm, and a Frazier air permeability of 5.06 cm ³ / cm ² / sec (a polyethylene terephthalate non-woven fabric manufactured by a wet method) was used as the fiber base material. The laminate was obtained and evaluated. The results are summarized in Table 1. An SEM photograph (magnification of 1000 times) of the surface of the porous film is shown in FIG. In this case as well, although a porous film was formed on the first main surface of the fiber base material on the first main surface of the fiber base material, the first main surface was often exposed and the porous film side of the laminate was formed. The surface smoothness of the was low.

[Comparative Example 3]
A laminate was obtained and evaluated in the same manner as in Example 3 except that the absorption time extension step was not performed. The results are summarized in Table 1. Since the DMF absorption time of the fiber base material is very short, most of the raw material resin solution permeates into the fiber base material, and the first main surface is formed from the porous membrane formed on the first main surface of the fiber base material. Was exposed a lot. Therefore, the surface smoothness of the laminated body on the porous film side was low.

[Comparative Example 4]
In the coating step, a laminate was obtained and evaluated in the same manner as in Comparative Example 3 except that the gap of the applicator was changed to 250 μm. The results are summarized in Table 1. Since the amount of the raw material resin solution applied was excessive, the porous film became thicker as compared with Comparative Example 3. Therefore, the surface smoothness of the porous membrane was improved, but the value of Gale air permeability became very large. In addition, the obtained laminate had curls due to the aggregation of the raw material resin.

[Comparative Example 5]
A laminate was obtained and evaluated in the same manner as in Example 1 except that the concentration of the raw material resin in the raw material resin solution was 10% by mass. The results are summarized in Table 1. Although a porous film was formed on the first main surface of the fiber base material on the first main surface of the fiber base material, the first main surface was often exposed and the surface smoothness of the laminated body on the porous film side was large. Was low. In addition, back leakage occurred. It is considered that this is because the viscosity of the raw material resin solution is low and most of the raw material resin solution has passed through the fiber base material during the coating process.

The laminate according to the present invention has excellent surface smoothness on the porous film side, is also excellent in air permeability, and is less likely to cause delamination between the porous film and the fiber base material. Therefore, this laminate can be used as a support for various separation membranes.

100: Laminated body 100X: Main surface on the porous film side 10: Resin porous body 11: Porous film 12: Resin porous body that has entered the gap between the fiber base materials 20: Fiber base material 20X: First main surface 20Y: First 2 Main surface 20F: Constituent fiber 20Fa: First region 20Fb: Second region 21: Composite region 22: Fiber region

Claims (13)

It is provided with a resin porous body and a fiber base material.
A part of the resin porous body forms a porous film covering one main surface of the fiber base material, and the other part of the resin porous body has entered the gap of the fiber base material.
The mass of the resin porous body is 1 to 35 g / m ² .
The thickness of the porous membrane is 1 to 100 μm.
Ri der time more than 60 seconds until absorbed from dropwise dimethylformamide to any of the major surface of the fibrous base material,
The fiber base material is a laminated body which is a fiber base material to which a fluororesin is applied, or is a fiber base material composed of fibers containing a fluororesin . The laminate according to claim 1, wherein the air permeability measured by the Gale method is 1 to 1000 seconds / 100 ml. The laminate according to claim 1 or 2, wherein the fiber base material has a porosity of 10 to 45%. The laminate according to any one of claims 1 to 3, wherein the air permeability of the fiber base material measured by the Frazier method is 0.2 to 20 cm ³ / cm ² / sec. The laminate according to any one of claims 1 to 4, wherein the fiber base material is a non-woven fabric. The laminate according to any one of claims 1 to 5, wherein the fiber base material has a melting point of 170 ° C. or higher. The laminate according to any one of claims 1 to 6, wherein the fibers constituting the fiber base material contain a polyester resin. The laminate according to any one of claims 1 to 6, wherein the fiber base material is a polyester resin to which a fluorine-containing water-repellent oil-repellent agent is applied. The laminate according to any one of claims 1 to 8 , wherein the arithmetic average roughness Ra of the main surface of the laminate on the porous film side is 1.30 μm or less. The laminate according to any one of claims 1 to 9 , wherein the porous membrane contains at least one of a polysulfone resin and a polyethersulfone resin. The laminate according to any one of claims 1 to 10 , which is a support for a separation membrane. The laminate according to any one of claims 1 to 11 , which is a support for a gas separation membrane. The laminate according to any one of claims 1 to 12 , and the laminate.
A membrane structure comprising a separation membrane having a separation function.