Non-woven fabric, separation membrane support body and liquid separation composite membrane

Abstract

The invention provides a non-woven fabric, a separation membrane support body and a liquid separation composite membrane, the non-woven fabric comprises a first fiber layer and a second fiber layer which are laminated, and the surface layer of at least one side of the non-woven fabric is the first fiber layer; the first fiber layer and the second fiber layer respectively comprise trunk fibers, and the trunk fibers comprise trunk fibers with special-shaped sections and trunk fibers with circular sections; the mass fraction of the main fibers with the special-shaped sections in the main fibers of the first fiber layer is larger than that of the main fibers with the special-shaped sections in the main fibers of the second fiber layer, and the mass fraction of the main fibers with the special-shaped sections in the main fibers of the second fiber layer is 10%-60%. According to the invention, the binding force between the non-woven fabric and the membrane body such as the separation membrane can be improved, so that the structural stability of the composite membrane formed by the non-woven fabric and the membrane body is improved, and the phenomena of layering, stripping and the like are avoided.

Description

Technical Field

[0001] The present invention relates to the field of separation membrane support materials, and particularly to a non-woven fabric, a separation membrane support body, and a liquid separation composite membrane. Background Art

[0002] The non-woven fabric can be used as a carrier for membranes such as liquid separation membranes, providing support for these membranes to ensure their application. However, the bonding force between the existing non-woven fabric and the membrane is weak, resulting in poor structural stability of the composite membrane formed by the non-woven fabric and the membrane, and prone to phenomena such as delamination and peeling, thus limiting the function. Summary of the Invention

[0003] The present invention provides a non-woven fabric, a separation membrane support body, and a liquid separation composite membrane, which can improve the bonding force between the non-woven fabric and membranes such as separation membranes, thereby improving the structural stability of the composite membrane formed by the non-woven fabric and the membrane, avoiding phenomena such as delamination and peeling, and effectively overcoming the defects existing in the prior art.

[0004] On the one hand, the present invention provides a non-woven fabric, comprising a first fiber layer and a second fiber layer arranged in a stacked manner, and the surface layer on at least one side of the non-woven fabric is the first fiber layer; both the first fiber layer and the second fiber layer respectively include main fibers, the main fibers include main fibers with a special-shaped cross-section and main fibers with a circular cross-section, the mass fraction of the main fibers with a special-shaped cross-section in the main fibers of the first fiber layer is greater than the mass fraction of the main fibers with a special-shaped cross-section in the main fibers of the second fiber layer, and the mass fraction of the main fibers with a special-shaped cross-section in the main fibers of the second fiber layer is 10% - 60%.

[0005] On the other hand, the present invention provides a separation membrane support body, comprising the aforementioned non-woven fabric and a support membrane layer compounded with the non-woven fabric, and the support membrane layer is at least located on the first fiber layer of the surface layer of the non-woven fabric.

[0006] On still another hand, the present invention provides a liquid separation composite membrane, comprising a separation functional layer and the aforementioned separation membrane support body, and the support membrane layer in the separation membrane support body is located between the separation functional layer and the non-woven fabric.

[0007] The non-woven fabric, separation membrane support, and liquid separation composite membrane provided by the present invention have a mass fraction of the profiled-section main fibers in the first fiber layer of the non-woven fabric greater than that in the second fiber layer, and the mass fraction of the profiled-section main fibers in the second fiber layer is 10% to 60%. Through the fiber distribution and composition of this specific form in the non-woven fabric, not only can the strength of the non-woven fabric be improved, but also the bonding force between the non-woven fabric and the membrane body compounded with the non-woven fabric can be improved. Furthermore, the structural stability of the composite membrane (such as a separation membrane support and a liquid separation composite membrane, etc.) formed by the non-woven fabric and the membrane body can be improved, and phenomena such as delamination and peeling can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of the cross-sectional shape (T-shaped) of the profiled-section fiber according to another embodiment of the present invention;

[0009] Figure 2 Schematic diagram of the cross-sectional shape (seven-eighths circular) of the profiled-section fiber according to another embodiment of the present invention ( Figure 2 where A shows the central angle, Figure 2 and B shows the depth at the deepest part and the width at the widest part);

[0010] Figure 3 Schematic diagram of the cross-sectional shape (regular hexagram) of the profiled-section fiber according to another embodiment of the present invention;

[0011] Figure 4 Schematic diagram of the cross-sectional shape (semicircular ring) of the profiled-section fiber according to another embodiment of the present invention;

[0012] Figure 5 Schematic diagram of the cross-sectional shape (N-shaped) of the profiled-section fiber according to another embodiment of the present invention;

[0013] Figure 6 Schematic diagram of the cross-sectional shape (triangle) of the profiled-section fiber according to another embodiment of the present invention;

[0014] Figure 7 Schematic diagram of the cross-sectional shape (quadrilateral) of the profiled-section fiber according to another embodiment of the present invention;

[0015] Figure 8 Schematic diagram of the cross-sectional shape (sixteen-pointed star) of the profiled-section fiber according to another embodiment of the present invention;

[0016] Figure 9 Schematic diagram of the cross-sectional shape (octagonal star) of the profiled-section fiber according to another embodiment of the present invention;

[0017] Figure 10 Schematic diagram of the cross-sectional shape (star-shaped) of the profiled-section fiber according to another embodiment of the present invention;

[0018] Figure 11 Schematic diagram of the cross-sectional shape (four-corner star shape) of the profiled-section fiber in another embodiment of the present invention;

[0019] Figure 12 Schematic diagram of the cross-sectional shape (crescent shape) of the profiled-section fiber in another embodiment of the present invention;

[0020] Figure 13 Schematic diagram of the cross-sectional shape (W shape) of the profiled-section fiber in another embodiment of the present invention;

[0021] Figure 14 Schematic diagram of the cross-sectional shape (open circle shape) of the profiled-section fiber in another embodiment of the present invention;

[0022] Figure 15 Schematic diagram of the cross-sectional shape (crescent shape) of the profiled-section fiber in another embodiment of the present invention;

[0023] Figure 16 Schematic diagram of the cross-sectional shape (U shape) of the profiled-section fiber in another embodiment of the present invention;

[0024] Figure 17 Schematic diagram of the cross-sectional shape (cross shape) of the profiled-section fiber in another embodiment of the present invention;

[0025] Figure 18 Schematic diagram of the cross-sectional shape (cross shape) of the profiled-section fiber in another embodiment of the present invention;

[0026] Figure 19 Schematic diagram of the cross-sectional shape (five-eighths circular ring shape) of the profiled-section fiber in another embodiment of the present invention;

[0027] Figure 20 Schematic diagram of the cross-sectional shape (three-petal plum blossom shape) of the profiled-section fiber in another embodiment of the present invention;

[0028] Figure 21 Schematic diagram of the cross-sectional shape (open circle shape) of the profiled-section fiber in another embodiment of the present invention;

[0029] Figure 22 Schematic diagram of the cross-sectional shape (open circle shape) of the profiled-section fiber in another embodiment of the present invention;

[0030] Figure 23 Schematic diagram of the differential scanning calorimetry curve of the fiber.

[0031] Explanation of reference numerals: 1: Cross-section of the profiled-section fiber; 10: Groove; 100: Circumscribed circle; w: Width at the widest part of the groove; h: Depth at the deepest part of the groove. Detailed implementation manners

[0032] To enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below.

[0033] The non-woven fabric can be used as a support for membrane bodies such as liquid separation membranes, providing support for these membrane bodies to ensure their applications. However, the bonding force between the existing non-woven fabric and the membrane body is weak, resulting in poor structural stability of the composite membrane formed by the non-woven fabric and the membrane body, and easy occurrence of phenomena such as delamination and peeling, thus limiting the function.

[0034] For example, liquid separation membrane technology is currently mainly widely used in fields such as sewage treatment, water purification, seawater desalination, and pure water preparation. According to different manufacturing materials, liquid separation membranes can be divided into inorganic membranes and organic membranes. Inorganic membranes mainly include ceramic membranes, glass membranes, and metal membranes, with relatively low filtration accuracy and limited application scope. Organic membranes can usually select polymer materials such as cellulose resin, polyvinyl alcohol resin, polysulfone resin, polyamide resin, and polyimide resin as raw materials based on different separation purposes. They have advantages such as high filtration accuracy and large selectivity, and have a wider application prospect in the fields of water resource utilization and industrial special separation.

[0035] However, the mechanical strength of the liquid separation membrane is relatively low. When used alone, it cannot withstand the high hydraulic pressure during the separation process, or cannot be prepared into a membrane alone. Therefore, it usually needs to be compounded on a carrier with a certain structural strength.

[0036] For example, liquid separation composite membranes such as nanofiltration composite membranes and reverse osmosis composite membranes are usually thin-layer composite membranes composed of a separation functional layer (usually an ultra-thin separation layer), an intermediate support layer, and a non-woven fabric porous support layer. Among them, the separation functional layer is the functional layer that plays a separation role in the water treatment process, generally having properties such as high water flux, high salt rejection rate, and high chemical stability. Its composition can mainly be polyamide materials (for example, aromatic polyamide can be used as nanofiltration membrane and reverse osmosis membrane materials); the base membrane formed by the intermediate support layer and the non-woven fabric porous support layer serves as the carrier of the ultra-thin separation layer (liquid separation membrane). The materials of the intermediate support layer mainly include polysulfone, polyethersulfone, polyacrylonitrile, polypropylene, cellulose acetate, etc. The non-woven fabric mainly provides the support strength of the membrane structure. The base membrane formed by the composite of the non-woven fabric and the intermediate support layer with high porosity can resist densification under the operating conditions of the composite membrane. The structure and properties of the base membrane affect the interfacial polymerization process (the ultra-thin separation layer is generally prepared by the interfacial polymerization method), the morphology and structure of the ultra-thin separation layer, and the permeability and stability of the liquid material used to form the ultra-thin separation layer coated on the base membrane to a certain extent, thereby affecting the structure and performance of the formed composite membrane (such as the liquid passing capacity, filtration performance, and service life of the composite membrane).

[0037] According to the long-term research of the inventors of the present application, as a support for membranes such as liquid separation membranes, the non-woven fabric is required to have high mechanical strength while also having a strong bonding force with the membrane body, so that the two can be firmly bonded without phenomena such as delamination and peeling, to ensure the function of the membrane body (such as ensuring high liquid throughput and high filtration accuracy of the liquid separation membrane, etc.).

[0038] The inventors of the present application have found through long-term research that if the adhesion of the coated surface of the non-woven fabric is poor, the coating liquid (or casting solution) used to form the membrane body composite with the non-woven fabric cannot effectively wet the surface of the non-woven fabric, and air bubbles (usually air bubbles) are easily generated and remain in the pores of the non-woven fabric, causing the coating liquid to be suspended at the pores of the non-woven fabric, reducing the actual contact area between the coating liquid and the non-woven fabric. This will cause problems such as weakening the bonding force between the formed coating (membrane body composite with the non-woven fabric) and the non-woven fabric, the appearance of pinholes in the coating, a decrease in the structural stability of the composite membrane formed by the non-woven fabric and the membrane body, and a significant reduction in the performance of the composite membrane (such as the filtration performance of the composite membrane with a liquid separation membrane).

[0039] On the other hand, the diffusion and penetration efficiency of the casting solution in the non-woven fabric is an important factor restricting the casting efficiency. Specifically, when the diffusion and penetration efficiency of the casting solution in the non-woven fabric is low, to ensure the film-forming quality, a relatively long time is usually required to make the casting solution diffuse and penetrate sufficiently in the non-woven fabric. In specific production, the production line needs to be maintained at a low speed to ensure sufficient residence time for the casting solution to diffuse and penetrate sufficiently in the non-woven fabric, and the production efficiency is limited.

[0040] In view of this, an embodiment of the present invention provides a non-woven fabric, which includes a first fiber layer and a second fiber layer arranged in a stacked manner, and the surface layer on at least one side of the non-woven fabric is the first fiber layer; both the first fiber layer and the second fiber layer respectively include main fibers, the main fibers include profiled cross-section main fibers and circular cross-section main fibers, the mass fraction of the profiled cross-section main fibers in the main fibers of the first fiber layer (i.e., the mass ratio of the profiled cross-section main fibers to the main fibers) is greater than the mass fraction of the profiled cross-section main fibers in the main fibers of the second fiber layer, and the mass fraction of the profiled cross-section main fibers in the main fibers of the second fiber layer is 10% - 60%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or any range composed of any two of them.

[0041] According to the research and analysis of the inventor, in the non-woven fabric of the embodiment of the present invention, the mass fraction of the profiled-section main fibers in the first fiber layer is higher than that in the second fiber layer, and at least one side surface layer of the non-woven fabric is the first fiber layer. Thus, a high-strength non-woven fabric with a high specific surface area can be obtained. When the coating liquid for forming the film body compounded with the non-woven fabric is coated on the high specific surface area surface (coating surface) of the non-woven fabric, it can diffuse and penetrate more quickly and sufficiently. In this way, on the one hand, the compounding efficiency of the film body and the non-woven fabric (i.e., the casting film production efficiency) can be improved. On the other hand, a strong bonding between the film body and the non-woven fabric can be achieved, significantly improving the bonding strength between the two and avoiding phenomena such as delamination and peeling. At the same time, a highly dense coating layer (i.e., the film body compounded with the non-woven fabric) can be formed on the non-woven fabric without a large amount of coating. This can not only significantly reduce the amount of materials used for forming the film body, simplify the process and reduce costs, but also greatly reduce the thickness of the composite film formed by compounding the non-woven fabric and the film body, improving its use performance and scope of application.

[0042] Meanwhile, in the embodiment of the present invention, by providing a second fiber layer stacked with the first fiber layer, a gradient difference is formed between the content of the profiled-section main fibers in the second fiber layer and the first fiber layer, which is beneficial to forming a difference in the penetration speed of the coating liquid for forming the film body compounded with the non-woven fabric in the first fiber layer and the second fiber layer of the non-woven fabric, that is, the difference in the content of the profiled-section main fibers in the thickness direction of the non-woven fabric (substantially parallel to the stacking direction of the first fiber layer and the second fiber layer), so as to form a difference in liquid absorption in the thickness direction of the non-woven fabric. Specifically, after the coating liquid is coated on the first fiber layer on the surface layer of the non-woven fabric, it can penetrate relatively quickly. After penetrating into the second fiber layer, the penetration rate slows down, avoiding excessive penetration of the coating liquid inside the non-woven fabric and preventing it from penetrating to the back surface of the non-woven fabric (i.e., the surface opposite to the coating surface). Thus, while achieving a high penetration rate, it is ensured that the coating liquid will not penetrate excessively and will not penetrate to the back surface of the non-woven fabric. On the one hand, it is beneficial to form a uniform thin layer of coating liquid on the surface of the non-woven fabric, and when the coating liquid solidifies, the formed coating is strongly bonded to the non-woven fabric by using the anchoring effect. On the other hand, it can further ensure the improvement of the film-making efficiency.

[0043] In addition, according to the inventor's research, if the content of the profiled-section trunk fibers in the second fiber layer is too low (mass fraction less than 10%), it is not conducive to improving the strength of the second fiber layer, thus affecting the overall structural strength of the non-woven fabric. At the same time, it will also cause too much resistance to the diffusion and penetration of the coating liquid used to form the film body compounded with the non-woven fabric in the second fiber layer, which is not conducive to achieving a high bonding strength between the formed film body and the non-woven fabric. If the content of the profiled-section trunk fibers in the second fiber layer is too high (mass fraction greater than 60%), it is easy for the casting solution (coating liquid) to penetrate to the back of the non-woven fabric during the film casting process, affecting the film casting efficiency and the performance of the composite film. At the same time, too many profiled-section trunk fibers are prone to form stress concentration sources, which cause excessive local strain when the load reaches a certain level, resulting in a reduction in the strength of the non-woven fabric instead.

[0044] Therefore, in the embodiments of the present invention, through the specific fiber distribution and composition in the non-woven fabric, not only can the strength of the non-woven fabric be improved, but also the bonding force between the non-woven fabric and the film body (such as polysulfone layer, polyethersulfone layer, polyarylethersulfone layer, polyphenylene oxide layer, polyvinylidene fluoride layer, polyarylethersulfone ketone layer, polyacrylonitrile layer, polypropylene layer, cellulose acetate layer, etc.) compounded with the non-woven fabric can be improved. Furthermore, the structural stability of the composite film formed by the non-woven fabric and the film body can be improved, avoiding phenomena such as delamination and peeling. At the same time, it also has the advantages of reducing the amount of film body material used, lowering costs, simplifying the process, improving the film casting efficiency, reducing the thickness of the composite film, etc., which is of great significance for actual industrial application.

[0045] For further example, for a liquid separation composite film, the non-woven fabric of the embodiments of the present invention can be used as the non-woven fabric porous support layer of the liquid separation composite film. While providing a supporting effect for the film body, it can improve the bonding force between the non-woven fabric and the intermediate support layer in the liquid separation composite film, avoid phenomena such as delamination and peeling, and can greatly reduce the coating amount of the intermediate support layer, thereby reducing the overall thickness of the liquid separation film and improving its separation efficiency. In addition, it also has the advantages of simple process, low cost, high film casting efficiency, etc.

[0046] Specifically, the non-woven fabric of the embodiments of the present invention can be an integral structure composed of at least two fiber layers. The at least two fiber layers include the above-mentioned first fiber layer and second fiber layer, and at least one surface of the non-woven fabric is the first fiber layer to form a surface with a high specific surface area, which can be used as the coating surface of the coating liquid for forming the film body compounded with the non-woven fabric, improving the diffusion and penetration efficiency of the coating liquid. Among them, in the non-woven fabric, the number of the first fiber layer can be one or more layers, and the number of the second fiber layer can be one or more layers.

[0047] Specifically, the mass ratio of the first fiber layer to the non-woven fabric can be 10% - 30% (that is, relative to the whole non-woven fabric, the mass proportion of the first fiber layer can be 10% - 30%), for example, 10%, 15%, 20%, 25%, 30% or the range composed of any two of them. Among them, when the non-woven fabric includes at least two first fiber layers, the mass ratio of the first fiber layer to the non-woven fabric (10% - 30%) refers to the ratio of the sum of the masses of these first fiber layers to the total mass of the non-woven fabric.

[0048] In addition, the mass ratio of the second fiber layer to the non-woven fabric can be 70% - 90% (that is, relative to the whole non-woven fabric, the mass proportion of the second fiber layer can be 70% - 90%), for example, 70%, 75%, 80%, 85%, 90% or the range composed of any two of them. Among them, when the non-woven fabric includes at least two second fiber layers, the mass ratio of the second fiber layer to the non-woven fabric (70% - 90%) refers to the ratio of the sum of the masses of these second fiber layers to the total mass of the non-woven fabric.

[0049] In some embodiments, the main fibers in the first fiber layer are profiled cross-section main fibers, that is, substantially all of the main fibers in the first fiber layer are profiled cross-section main fibers, and there are no circular cross-section main fibers (that is, the mass fraction of the circular cross-section main fibers in the first fiber layer among all the main fibers in the first fiber layer is 0%). This is beneficial to further improve the diffusion and penetration efficiency of the coating liquid while ensuring the structural strength of the non-woven fabric, improve the bonding strength between the film body and the non-woven fabric, and the film-making efficiency.

[0050] In some embodiments, the surface layer on one side of the non-woven fabric is the first fiber layer, and the surface layer on the other side is the second fiber layer. In this way, the surface layers on the opposite two sides of the non-woven fabric are the first fiber layer and the second fiber layer respectively. The outer surface of the first fiber layer serves as the coating surface to improve the diffusion and penetration efficiency of the coating liquid. The outer surface of the second fiber layer is the back surface of the non-woven fabric, which avoids the penetration of the coating liquid to the back surface of the non-woven fabric, and further improves the composite efficiency between the film body and the non-woven fabric, as well as properties such as the bonding strength between the two.

[0051] In addition, the perimeter coefficient X of the cross-section of at least part (part or all) of the profiled cross-section main fibers in the first fiber layer L can satisfy 1 < X L ≤ 5, and the perimeter coefficient X of the cross-section of at least part (part or all) of the profiled cross-section main fibers in the second fiber layer L can satisfy 1 < X L ≤ 5. This can further improve the structural strength of the non-woven fabric and properties such as performance uniformity.

[0052] According to the research of the inventor, if the perimeter coefficient X of the cross-section of the above profiled cross-section main fibers LGreater than 5. Although the specific surface area of the fiber increases, excessive microstructures such as grooves and protrusions on the fiber surface are more likely to cause entanglement between the main fibers of the profiled cross-section, making it easy for the main fibers in the fiber layer to entangle into clusters and difficult to disperse evenly, which is not conducive to obtaining non-woven fabrics with high performance uniformity.

[0053] Specifically, for each layer of the first fiber layer or the second fiber layer, there may be one shape of profiled cross-section main fiber (i.e., the cross-section 1 of these profiled cross-section main fibers has the same shape), or there may be multiple different shapes of profiled cross-section main fibers (i.e., the cross-section 1 of at least some profiled cross-section main fibers has different shapes). When there are multiple different shapes of profiled cross-section main fibers, the perimeter coefficient X of the cross-section 1 of at least one shape of profiled cross-section main fiber L satisfies 1 < X L ≤ 5, that is, it can be the perimeter coefficient X of the cross-section 1 of one shape of profiled cross-section main fiber L satisfies 1 < X L ≤ 5, or the perimeter coefficients X of the cross-section 1 of at least two shapes of profiled cross-section main fibers L satisfy 1 < X L ≤ 5.

[0054] Exemplarily, the perimeter coefficient X of the cross-section 1 of at least some of the above profiled cross-section main fibers L is, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.8, 2, 2.3, 2.5, 2.8, 3, 3.5, 4, 4.5, 5 or the range composed of any two of them.

[0055] In the above non-woven fabric, the perimeter coefficients X of the cross-section 1 of the profiled cross-section main fibers in every two fiber layers L can be equal or unequal. For example, the perimeter coefficient X of the cross-section 1 of the profiled cross-section main fibers in the first fiber layer L can be equal to, greater than, or less than the perimeter coefficient X of the cross-section 1 of the profiled cross-section main fibers in the first fiber layer L , and there is no special restriction on this.

[0056] Specifically, the profiled cross-section main fiber is a non-circular cross-section main fiber, that is, its cross-section 1 is non-circular, and this cross-section 1 is perpendicular to the axial direction of the profiled cross-section main fiber (generally also the length direction of the profiled cross-section main fiber). The perimeter coefficient X of the cross-section 1 of the profiled cross-section main fiber L is equal to the perimeter C of the cross-section of this profiled cross-section main fiber 0 and the perimeter C of a circle with the same area as the cross-section 1 of this profiled cross-section main fiber 1 of the ratio (i.e., X L = C 0 / C1 ) and can be specifically measured by the perimeter coefficient measurement method in the Textile Industry Standard of the People's Republic of China FZ / T 50002-2013 (Test Method for Profileness of Chemical Fibers).

[0057] Specifically, the cross-section of the circular cross-section main fiber is basically circular, and this cross-section is perpendicular to the axial direction of the circular cross-section main fiber (generally also the length direction of the circular cross-section main fiber).

[0058] Generally, the non-woven fabric may further include binder fibers, that is, each fiber layer (such as the first fiber layer, the second fiber layer, etc.) respectively includes binder fibers, and the softening point of the main fibers (circular cross-section main fibers, profiled cross-section main fibers) is greater than that of the binder fibers. The binder fibers are mainly used to bond components such as the main fibers in the non-woven fabric and improve the structural strength of the non-woven fabric.

[0059] Specifically, in the process of preparing the non-woven fabric, the randomly dispersed fibers (including main fibers and binder fibers) are usually shaped through a hot calendering process. Among them, the main fibers serve as the skeleton of the non-woven fabric structure and basically do not melt, while part or all of the surface of the binder fibers melts, so as to diffuse and penetrate into the surface of the fibers, as well as the gaps, voids or uneven structures between the fibers. After cooling and solidification, a locking force is generated in the interface area, so that the fibers in the non-woven fabric are bonded to each other, realizing a firm combination between the fibers and endowing the non-woven fabric with structural strength.

[0060] Generally, under the conditions of the same fiber linear density, the same fiber length, and the same fiber cross-sectional area, the specific surface area of the profiled cross-section main fiber is significantly higher than that of the circular cross-section main fiber. By introducing the above-mentioned cross-section perimeter coefficient X into the non-woven fabric L satisfying 1 < X L ≤5 profiled cross-section main fibers, by utilizing the high specific surface area of the profiled cross-section main fibers and the pore structure that can form a capillary effect between the fibers, the melted part of the binder fibers can be wetted more fully and quickly, greatly increasing the bonding area between the fibers and significantly improving the structural strength of the non-woven fabric (the non-woven fabric using only circular cross-section main fibers usually mainly forms bonding points at the fiber intersections, while the non-woven fabric in the embodiments of the present invention introduces the cross-section perimeter coefficient X L satisfying 1 < X L ≤5 profiled cross-section main fibers, and its structural strength is significantly improved).

[0061] Through further research, grooves can be provided on the surfaces of at least some of the profiled cross-section main fibers in the first fiber layer, and grooves can be provided on the surfaces of at least some of the profiled cross-section main fibers in the second fiber layer.

[0062] In this way, on the one hand, the anchoring effect of fiber bonding can be further strengthened. The melted part of the bonded fiber penetrates into the fine grooves 10 on the surface of the main fiber with a special cross-section through capillary attraction. After cooling and solidification, the fibers cannot move relatively, thereby achieving a strong joint between the fibers and further improving the structural strength of the non-woven fabric.

[0063] On the other hand, the fibers are the framework of the non-woven fabric. The shape and arrangement of the fibers determine the pore structure inside the non-woven fabric. The irregular cross-sectional shape of the main fiber with a special cross-section significantly increases the specific surface area and capillary effect between the fibers and the fiber web, which is beneficial to enhancing the adsorption of the non-woven fabric to fluid components (such as the fluid formed by melting components such as the bonded fiber during the preparation of the non-woven fabric, the coating liquid used to form the film body composite with the non-woven fabric, etc.). The fluid components are embedded in the fine grooves of the surface fibers of the non-woven fabric and cannot move after the coating is cured, significantly improving the bonding strength between the coating and the non-woven fabric.

[0064] On the other hand again, the main fiber with a special cross-section in the non-woven fabric has a relatively high specific surface area, which is beneficial to improving the uniform adsorption of the fluid components of the non-woven fabric. When the surface of the main fiber with a special cross-section is provided with grooves, the capillary force generated by the fine grooves on the surface of the main fiber with a special cross-section can further facilitate the fluid components to quickly and fully infiltrate the fine grooves on the fiber surface through the wicking action. Therefore, by introducing the main fiber with a special cross-section having grooves into the non-woven fabric, it is beneficial to further improve the film-making efficiency (i.e., the composite efficiency of the film body and the non-woven fabric) and the bonding strength between the non-woven fabric and the film body and other properties.

[0065] Specifically, in the main fiber with a special cross-section, its groove 10 can extend along the axial direction of the main fiber with a special cross-section and penetrate the main fiber with a special cross-section in the axial direction of the main fiber with a special cross-section, that is, the length of the groove 10 on the main fiber with a special cross-section is equal to the length of the main fiber with a special cross-section.

[0066] In addition, in the main fiber with a special cross-section, the number of its grooves 10 can be one or more. When there are multiple grooves, these grooves 10 can be specifically distributed along the circumferential direction of the main fiber with a special cross-section.

[0067] Specifically, in the main fiber with a special cross-section, the number of its grooves 10 can be less than or equal to 20, that is, 1 to 20 grooves 10 can be provided on one main fiber with a special cross-section. The number of grooves 10 is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, etc. This is beneficial to further improving the structural strength of the non-woven fabric and the bonding strength between the non-woven fabric and the film body.

[0068] Among them, the number of grooves 10 of the profiled-section main fibers in every two fiber layers can be the same or different. For example, the number of grooves 10 of the profiled-section main fibers in the first fiber layer can be the same as or different from that in the second fiber layer. Specifically, the number of grooves 10 of the profiled-section main fibers in the first fiber layer can be greater than, equal to, or less than the number of grooves 10 of the profiled-section main fibers in the second fiber layer.

[0069] Generally, in each fiber layer (such as the first fiber layer, the second fiber layer, etc.), the number of profiled-section main fibers is multiple, and the number of grooves 10 on these profiled-section main fibers can be the same or different. For each first fiber layer or second fiber layer, there is at least one shape of profiled-section main fiber, that is, there can be one profiled-section main fiber or multiple profiled-section main fibers. When there are multiple profiled-section main fibers, the number of grooves 10 of any two profiled-section main fibers can be the same or different.

[0070] After further research, relatively speaking, if the width of the groove 10 on the profiled-section main fiber is too small, the too-narrow groove 10 is not conducive to the discharge of the air inside it, making it difficult for the fluid (such as the fluid formed by melting components such as bonding fibers during the preparation of non-woven fabrics, and the coating liquid used to form the film body compounded with the non-woven fabric during the compounding process of the non-woven fabric and the film body) to infiltrate inside the groove 10. Therefore, it is preferred that the width w at the widest part of the groove 10 is not less than (greater than or equal to) 10% of the diameter D of the circumscribed circle 100 of the cross-section 1 of the profiled-section main fiber (i.e., w / D≥10%). Specifically, w / D can be 10% - 100%, for example, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% or the range composed of any two of them. This is more conducive to discharging the air inside the groove 10, so that the fluid can infiltrate more fully, faster and better inside the groove 10, and further improve the properties such as the strength of the non-woven fabric and its bonding strength with the film body.

[0071] Among them, the w / D of the profiled-section main fibers in the first fiber layer can be the same as or different from that in the second fiber layer. Specifically, the w / D of the profiled-section main fibers in the first fiber layer can be greater than, equal to, or less than the w / D of the profiled-section main fibers in the second fiber layer.

[0072] In addition, relatively speaking, if the groove 10 on the profiled-section main fiber is too deep, the bottom of the groove 10 is likely to become a weak part of its own structure, and is prone to tearing under stress, making it difficult to maintain the original shape of the groove 10, and affecting the structural strength of the non-woven fabric and its bonding strength with the film body and other properties. Therefore, it is preferable that the depth h of the deepest part of the groove 10 is not greater than (less than or equal to) 80% of the diameter D of the circumscribed circle of the cross-section of the profiled-section main fiber (i.e., h / D ≤ 80%), and h / D can specifically be 5% - 80%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or the range composed of any two of them. In this way, the bottom of the groove 10 is not likely to become a weak part of the structure itself, and is not prone to tearing under the relevant stress, so as to better maintain the original shape of the groove 10, and further improve the structural strength of the non-woven fabric and its bonding strength with the film body and other properties.

[0073] Among them, the h / D of the profiled-section main fiber in the first fiber layer and the h / D of the profiled-section main fiber in the second fiber layer can be the same or different, and the h / D of the profiled-section main fiber in the first fiber layer can specifically be greater than, equal to or less than the h / D of the profiled-section main fiber in the second fiber layer.

[0074] The width w of the widest part of the groove 10 refers to the distance between the two side wall surfaces of the widest part of the groove 10, that is, the width w of the widest part of the groove 10 refers to the maximum straight-line distance between the two side wall surfaces that form the groove 10. Specifically, the groove 10 has two side wall surfaces, which are respectively located on the opposite sides of the groove 10 (that is, one side wall surface is on one side of the groove 10 and the other side wall surface is on the other side of the groove 10), and the lengths of the two side wall surfaces in the length direction (axial direction) of the profiled-section main fiber are equal to the length of the profiled-section main fiber. Among them, the maximum distance between the two side wall surfaces in the direction perpendicular to the length direction of the profiled-section main fiber is the width w of the widest part of the groove 10.

[0075] For example, referring to Figures 1 to 18 、 Figures 20 to 22 , the widest part of the groove 10 is the opening of the groove 10. At this time, the width w of the widest part of the groove 10 can specifically refer to the straight-line distance between the two outermost endpoints of the cross-sectional contour lines of the two side wall surfaces that form the groove 10, that is, in the cross-section 1 of the profiled-section main fiber (this cross-section 1 is perpendicular to the axial direction of the profiled-section main fiber), the straight-line distance between the endpoints of the two side wall surfaces that enclose the groove 10 at the opening of the groove 10 is the width w of the widest part of the groove 10.

[0076] For example, referring to Figure 19, the widest part of the groove is located inside the groove 10. At this time, the width w of the widest part of the groove 10 is the distance between the two side wall surfaces of the groove 10 at this widest part.

[0077] In addition, continue to refer to Figures 1 to 22 , the depth of the deepest part of the groove 10 (i.e., the maximum depth of the groove 10) h refers to the maximum vertical distance between the bottom of the groove 10 (the bottom surface of the groove away from its opening) and the connecting line between the endpoints on the opposite sides of the opening of the groove 10. Among them, in the cross-section 1 of the profiled-section main fiber (this cross-section 1 is perpendicular to the axial direction of the profiled-section main fiber), the straight line between the endpoints of the two side wall surfaces enclosing the groove 10 at the opening of the groove 10 is the above-mentioned connecting line.

[0078] It can be understood that the above-mentioned straight line, connecting line, and outer contour line are used to illustrate the width w of the widest part of the groove 10 and the depth h of the deepest part of the groove 10, and they are all virtual lines and not structures that actually exist.

[0079] Specifically, the shape of the cross-section 1 of the above-mentioned profiled-section main fiber can include a heart shape, a dumbbell shape, a crescent shape (as shown in Figure 12 ), a new moon shape (as shown in Figure 15 ), an incomplete circular ring shape, an incomplete circular shape, a clover shape, a polygon, an incomplete polygon, a character shape, or a plum blossom shape, but it is not limited to this, and it can also be other regular or irregular shapes.

[0080] Among them, the central angle corresponding to the outer circular arc of the incomplete circular ring is less than the central angle corresponding to the outer circular arc of its complete concentric circular ring. For example, the incomplete circular ring includes a semi-circular ring (that is, the central angle corresponding to the outer circular arc of the incomplete circular ring is 1 / 2 of the central angle corresponding to the outer circular arc of its complete concentric circular ring, as shown in Figure 4 ), or the five-eighths circular ring as shown in Figure 19 (that is, the central angle corresponding to the outer circular arc of the incomplete circular ring is 5 / 8 of the central angle corresponding to the outer circular arc of its complete concentric circular ring).

[0081] Among them, the central angle α of the incomplete circular shape (including a sector, an arc, and an open circle) is less than 360°. For example, the incomplete circular shape includes a seven-eighths circular shape (that is, its central angle α accounts for seven-eighths of 360°, as shown in Figure 2 ), or an open circle as shown in Figure 14 , Figure 21 or Figure 22 .

[0082] Exemplarily, the clover shape includes a three-leaf shape or a four-leaf shape.

[0083] Exemplarily, the polygon includes a triangle (as shown in Figure 6 ), a quadrilateral (as shown inFigure 7 as shown), pentagon, hexagon, etc., and may also include a polygon, such as a triangular star, a quadrangular star (as Figure 11 shown), a pentagonal star, a hexagonal star (as Figure 3 shown), an octagonal star (as Figure 9 shown), or a hexadecagonal star (as Figure 8 shown), etc.

[0084] Exemplarily, the character shape includes a cross shape (as Figure 17 and Figure 18 shown), a double cross shape, an I shape, a rice shape (as Figure 10 shown), a wood shape, a C shape, an E shape, an F shape, a G shape, an H shape, a J shape, a K shape, an L shape, an M shape, an N shape (as Figure 5 shown), an S shape, a T shape (as Figure 1 shown), a U shape (as Figure 16 shown), a V shape, a W shape (as Figure 13 shown), an X shape, a Y shape, or a Z shape.

[0085] Exemplarily, the plum blossom shape includes a three - petal plum blossom shape (as Figure 20 shown), a four - petal plum blossom shape, a five - petal plum blossom shape, or a six - petal plum blossom shape, etc.

[0086] Generally, the shapes of the profiled cross - section trunk fibers in the first fiber layer and the profiled cross - section trunk fibers in the second fiber layer may be the same or different. In addition, the first fiber layer includes a plurality of profiled cross - section trunk fibers, and the shapes of these profiled cross - section trunk fibers may be the same or different. The second fiber layer includes a plurality of profiled cross - section trunk fibers, and the shapes of these profiled cross - section trunk fibers may be the same or different.

[0087] In addition, relatively speaking, if the linear density of the main fibers in the non-woven fabric is small, it will reduce the strength of the non-woven fabric, the diffusion and penetration rate of the coating liquid in the non-woven fabric, and the bonding strength between the non-woven fabric and the film body. If the linear density of the main fibers in the non-woven fabric is too large, it will also reduce the strength of the non-woven fabric and its bonding strength with the film body, and at the same time, it is easy to form large pores, resulting in the penetration of the coating liquid to the back of the non-woven fabric. Therefore, considering these factors comprehensively, it is preferred that the linear density of the main fibers (such as profiled cross-section main fibers) in the first fiber layer is 0.4 to 1.8 dtex, for example, 0.4 dtex, 0.5 dtex, 0.6 dtex, 0.7 dtex, 0.8 dtex, 0.9 dtex, 1 dtex, 1.3 dtex, 1.5 dtex, 1.8 dtex or the range composed of any two of them, and the linear density of the main fibers in the second fiber layer is 0.4 to 1.8 dtex, for example, 0.4 dtex, 0.5 dtex, 0.6 dtex, 0.7 dtex, 0.8 dtex, 0.9 dtex, 1 dtex, 1.3 dtex, 1.5 dtex, 1.8 dtex or the range composed of any two of them.

[0088] Specifically, when the main fibers in the above fiber layer (such as the second fiber layer) include both profiled cross-section main fibers and circular cross-section main fibers, the linear density of the circular cross-section main fibers and the linear density of the profiled cross-section main fibers can each be 0.4 to 1.8 dtex. The linear density of the circular cross-section main fibers and the linear density of the profiled cross-section main fibers can be the same or different. Specifically, the linear density of the circular cross-section main fibers can be greater than, equal to, or less than the linear density of the profiled cross-section main fibers.

[0089] Specifically, the linear density of the main fibers in every two fiber layers can be the same or different. For example, the linear density of the main fibers in the first fiber layer and the linear density of the main fibers in the second fiber layer can be the same or different. Specifically, the linear density of the main fibers in the first fiber layer can be greater than, equal to, or less than the linear density of the main fibers (profiled cross-section main fibers, circular cross-section main fibers) in the second fiber layer.

[0090] In addition, the length of the main fibers in the first fiber layer can be 3 to 7 mm, for example, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm or the range composed of any two of them.

[0091] In addition, the length of the main fibers in the second fiber layer can be 3 to 7 mm, for example, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm or the range composed of any two of them.

[0092] Specifically, when the main fibers in the above-mentioned fiber layer (such as the second fiber layer) include both profiled-section main fibers and round-section main fibers, the linear density of the round-section main fibers and the length of the profiled-section main fibers can each be 3 to 7 mm. The lengths of the round-section main fibers and the profiled-section main fibers can be the same or different. Specifically, the length of the round-section main fibers can be greater than, equal to, or less than the length of the profiled-section main fibers.

[0093] Specifically, the lengths of the main fibers in each two fiber layers can be the same or different. For example, the length of the main fibers in the first fiber layer can be the same or different from the length of the main fibers in the second fiber layer. Specifically, the length of the main fibers in the first fiber layer can be greater than, equal to, or less than the length of the main fibers (profiled-section main fibers, round-section main fibers) in the second fiber layer.

[0094] In addition, the length of the binder fibers in the first fiber layer can be 3 to 7 mm, such as 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, or a range composed of any two of them.

[0095] In addition, the diameter of the binder fibers in the first fiber layer can be 6 to 18 μm, such as 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or a range composed of any two of them.

[0096] In addition, the length of the binder fibers in the second fiber layer is 3 to 7 mm, such as 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, or a range composed of any two of them.

[0097] In addition, the diameter of the binder fibers in the second fiber layer can be 6 to 18 μm, such as 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or a range composed of any two of them.

[0098] In addition, the linear density of the binder fibers in the first fiber layer and the second fiber layer can be 0.6 to 2.5 dtex, such as 0.6 dtex, 0.9 dtex, 1 dtex, 1.2 dtex, 1.5 dtex, 1.7 dtex, 2 dtex, 2.3 dtex, 2.5 dtex, or a range composed of any two of them.

[0099] Specifically, in each fiber layer, the length of the binder fibers can be greater than, equal to, or less than the length of the main fibers, and the linear density of the binder fibers can be greater than, equal to, or less than the linear density of the main fibers.

[0100] Specifically, parameters such as the length or linear density of the bonding fibers in every two fiber layers can be the same or different. For example, the length of the bonding fibers in the first fiber layer can be the same as or different from that in the second fiber layer. Specifically, the length of the bonding fibers in the first fiber layer can be greater than, equal to, or less than that in the second fiber layer; the linear density of the bonding fibers in the first fiber layer can be the same as or different from that in the second fiber layer. Specifically, the linear density of the bonding fibers in the first fiber layer can be greater than, equal to, or less than that in the second fiber layer.

[0101] The linear density of the above-mentioned main fibers and the linear density of the bonding fibers both refer to the average linear density, which can be measured by conventional methods in the art. For example, it can be measured by the test method for linear density of chemical fiber staple fibers in GB / T 14335-2008. The length of the above-mentioned main fibers and the length of the bonding fibers both refer to the average length, which can be measured by conventional methods in the art. For example, it can be measured by the test method for length of chemical fiber staple fibers in GB / T14336-2008.

[0102] In addition, the mass fraction of the main fibers in the first fiber layer (i.e., the mass ratio of the main fibers to the first fiber layer) is greater than the mass fraction of the bonding fibers in the first fiber layer. The mass fraction of the main fibers in the first fiber layer can be greater than or equal to 65%, specifically, it can be 65% - 85%, such as 65%, 67%, 70%, 72%, 75%, 77%, 80%, 82%, 85%, or any range composed of any two of them.

[0103] In addition, the mass fraction of the bonding fibers in the first fiber layer (i.e., the mass ratio of the bonding fibers to the first fiber layer) can be 15% - 35%, such as 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, or any range composed of any two of them.

[0104] In addition, the mass fraction of the main fibers in the second fiber layer (i.e., the mass ratio of the main fibers to the second fiber layer) is greater than the mass fraction of the bonding fibers in the second fiber layer. The mass fraction of the main fibers in the second fiber layer can be greater than or equal to 60%, specifically, it can be 60% - 80%, such as 60%, 62%, 65%, 67%, 70%, 72%, 75%, 77%, 80%, or any range composed of any two of them.

[0105] In addition, the mass fraction of the bonding fibers in the second fiber layer is 20% - 40%, such as 20%, 23%, 25%, 28%, 30%, 33%, 35%, 38%, 40%, or any range composed of any two of them.

[0106] Specifically, the mass fraction of the main fibers in the first fiber layer and the mass fraction of the main fibers in the second fiber layer may be the same or different. Specifically, the mass fraction of the main fibers in the first fiber layer may be greater than, equal to, or less than the mass fraction of the main fibers in the second fiber layer; the mass fraction of the binder fibers in the first fiber layer and the mass fraction of the binder fibers in the second fiber layer may be the same or different. Specifically, the mass fraction of the binder fibers in the first fiber layer may be greater than, equal to, or less than the mass fraction of the binder fibers in the second fiber layer.

[0107] It should be noted that when there are multiple types of main fibers in the above-mentioned fiber layer, the mass fraction of the main fibers refers to the ratio of the sum of the masses of all the main fibers in the fiber layer to the mass of the fiber layer. For example, for each second fiber layer, its main fibers are composed of profiled cross-section main fibers and circular cross-section main fibers, then the mass fraction of the main fibers in the second fiber layer refers to the ratio of the sum of the masses of the profiled cross-section main fibers and the circular cross-section main fibers to the mass of the second fiber layer.

[0108] In addition, the content (mass fraction) of the profiled cross-section main fibers in the first fiber layer is greater than the content (mass fraction) of the profiled cross-section main fibers in the second fiber layer, and the difference between the mass fraction of the profiled cross-section main fibers in the first fiber layer (the mass ratio of the profiled cross-section main fibers to the first fiber layer) and the mass fraction of the profiled cross-section main fibers in the second fiber layer (the mass ratio of the profiled cross-section main fibers to the second fiber layer) may be not less than (greater than or equal to) 10%. The difference between the two is, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 79% or any range composed of any two of them.

[0109] Generally, the mass fraction of the profiled cross-section main fibers in the first fiber layer may be greater than or equal to 40%, specifically 40% - 85%, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or any range composed of any two of them.

[0110] In addition, the mass fraction of the circular cross-section main fibers in the first fiber layer (that is, the mass ratio of the circular cross-section main fibers to the first fiber layer) may be 0 - 40%, such as 0, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or any range composed of any two of them.

[0111] In addition, the mass fraction of the profiled cross-section main fibers in the second fiber layer may be 6% - 48%, such as 6%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 48% or any range composed of any two of them.

[0112] In addition, the mass fraction of the fibers with circular cross-sections in the second fiber layer (i.e., the mass ratio of the main fibers with circular cross-sections to the first fiber layer) can be 24% to 72%, such as 24%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 72%, or any range composed of any two of them.

[0113] In addition, in order to ensure that the main fibers will not or basically will not melt or soften during the processing due to the melting and softening of the bonding fibers, resulting in changes in the morphological structure, the softening point of the main fibers is greater than the softening point of the bonding fibers. Considering better maintaining the morphological structure of the main fibers, preferably, the difference between the softening point of the main fibers and the softening point of the bonding fibers can be greater than or equal to 20°C. That is, in each fiber layer (such as the first fiber layer and the second fiber layer), the difference between the softening point of the main fibers and the softening point of the bonding fibers can be greater than or equal to 20°C. When the main fibers in the fiber layer include main fibers with circular cross-sections and main fibers with profiled cross-sections, the softening point of the main fibers with circular cross-sections and the softening point of the main fibers with profiled cross-sections can be the same or different. Specifically, the softening point of the main fibers with circular cross-sections can be greater than, equal to, or less than the softening point of the main fibers with profiled cross-sections.

[0114] In some embodiments, the difference between the softening point of the main fibers (main fibers with circular cross-sections or main fibers with profiled cross-sections) and the softening point of the bonding fibers can be specifically 20 to 280°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 90°C, 95°C, 100°C, 110°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 160°C, 165°C, 170°C, 180°C, 190°C, 195°C, 200°C, 205°C, 210°C, 220°C, 230°C, 240°C, 250°C, 252°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, or any range composed of any two of them.

[0115] In some embodiments, the softening point of the main fibers (main fibers with circular cross-sections or main fibers with profiled cross-sections) can be 190°C to 400°C, such as 190°C, 200°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, or any range composed of any two of them.

[0116] Specifically, the softening point of the binder fibers can be greater than or equal to 120°C, specifically 120°C to 230°C, such as 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C or the range composed of any two of them.

[0117] Among them, the softening points of the binder fibers in the first fiber layer and the second fiber layer can be the same or different. Specifically, the softening point of the binder fibers in the first fiber layer can be greater than, equal to, or less than the softening point of the binder fibers in the second fiber layer; the softening points of the main fibers in the first fiber layer and the second fiber layer can be the same or different. Specifically, the softening point of the main fibers in the first fiber layer can be greater than, equal to, or less than the softening point of the main fibers in the second fiber layer.

[0118] In specific implementation, a differential scanning calorimeter (DSC) can be used to measure the softening points of the above-mentioned main fibers and binder fibers. Specifically, use a differential scanning calorimeter (DSC), and measure the differential scanning calorimetry curve of the fibers by means of programmed temperature rise. Use the starting temperature T i at which the melting endothermic peak in the obtained curve begins to deviate from the baseline Figure 23 to characterize the softening point of the fiber (as

[0119] shown). The specific test method can refer to GBT 19466.3-2004 (Plastics - Differential scanning calorimetry (DSC) - Part 3: Determination of melting and crystallization temperatures and enthalpies).

[0120] In some embodiments, the above-mentioned binder fibers can include one or more of unstretched polyester fibers, polyolefin fibers, copolyester fibers, copolyamide fibers, and composite fibers with a skin-core structure.

[0120] Optionally, the unstretched polyester fibers can include polyethylene terephthalate (PET) unstretched fibers and / or polybutylene terephthalate (PBT) unstretched fibers.

[0121] Optionally, the polyolefin fibers can include one or more of polyethylene (PE), polypropylene (PP), polyvinyl chloride, etc.

[0122] Specifically, the composite fiber with a skin-core structure (skin-core fiber) includes a core layer and a skin layer existing on the surface of the core layer. Specifically, the skin layer can wrap around the periphery of the core layer, thereby forming a skin-core structure.

[0123] Generally, a composite fiber with a skin-core structure includes at least two fibers, one of which forms the skin layer and the remaining fibers form the core layer. Exemplarily, the skin layer can include materials such as polyolefin, copolyester, copolyamide, etc. For example, a composite fiber with a skin-core structure can include a PE / PP bicomponent fiber, that is, the PE / PP bicomponent fiber includes a core layer and a skin layer present on the surface of the core layer. Specifically, the skin layer can wrap around the periphery of the core layer. The core layer includes PE and the skin layer includes PP.

[0124] Specifically, in the non-woven fabric, the binder fibers in every two fiber layers can be the same or different. For example, the materials of the binder fibers in the first fiber layer and the second fiber layer can be the same or different.

[0125] In some embodiments, the above-mentioned main fibers (circular cross-section main fibers, profiled cross-section main fibers) can include one or more of polyester fiber, polyolefin fiber, polyamide fiber, polyimide fiber (PI), polytetrafluoroethylene fiber (PTFE), polyvinyl alcohol fiber, polyvinylidene fluoride fiber (PVDF), polyphenylene sulfide fiber (PPS), polyether ether ketone fiber, polyacrylonitrile fiber (PAN), polycarbonate fiber, aramid fiber, glass fiber, ceramic fiber, oxide fiber, boride fiber, nitride fiber.

[0126] Optionally, the polyester fiber can include polyethylene terephthalate (PET) and / or polybutylene terephthalate (PBT).

[0127] Optionally, the polyolefin fiber can include one or more of polyethylene, polypropylene (PP), polyvinyl chloride, polyethylene / polypropylene skin-core fiber, polyethylene / polyethylene terephthalate skin-core fiber.

[0128] Optionally, the polyamide fiber can include polyamide 66 (PA66).

[0129] Specifically, in the non-woven fabric, the main fibers in every two fiber layers can be the same or different. For example, the materials of the main fibers in the first fiber layer and the second fiber layer can be the same or different. In addition, for each fiber layer, when the main fibers therein include profiled cross-section main fibers and circular cross-section main fibers, the materials of the profiled cross-section main fibers and the circular cross-section main fibers can be the same or different.

[0130] In addition, the areal density of the first fiber layer can be 3 - 30 g / m 2 , for example 4 g / m 2 , 5 g / m 2 , 6 g / m 2 , 7 g / m 2 , 8 g / m 2 , 9 g / m2 , 10 g / m 2 , 12 g / m 2 , 13 g / m 2 , 14 g / m 2 , 15 g / m 2 , 18 g / m 2 , 20 g / m 2 , 22 g / m 2 , 25 g / m 2 or the range composed of any two of them.

[0131] In addition, the areal density of the second fiber layer can be 21 - 90 g / m 2 , such as 22 g / m 2 , 25 g / m 2 , 28 g / m 2 , 30 g / m 2 , 32 g / m 2 , 34 g / m 2 , 36 g / m 2 , 38 g / m 2 , 40 g / m 2 , 42 g / m 2 , 45 g / m 2 , 48 g / m 2 , 50 g / m 2 , 53 g / m 2 , 55 g / m 2 , 58 g / m 2 , 60 g / m 2 , 63 g / m 2 , 65 g / m 2 , 67 g / m 2 , 70 g / m 2 , 72 g / m 2 , 75 g / m 2 , 78 g / m 2 , 80 g / m 2 , 83 g / m 2 , 84 g / m 2 , 86 g / m 2 , 88 g / m 2 , 90 g / m 2 or the range composed of any two of them.

[0132] Generally, the areal density of the second fiber layer can be greater than that of the first fiber layer, which is beneficial to improving the structural strength of the non-woven fabric and taking into account the performance such as improving the bonding strength between the non-woven fabric and the film body.

[0133] In addition, the areal density of the non-woven fabric can be 50 - 100 g / m 2 , such as 50 g / m2 , 60 g / m 2 , 70 g / m 2 , 80 g / m 2 , 90 g / m 2 , 100 g / m 2 or the range composed of any two of them.

[0134] In addition, the thickness of the non-woven fabric can be 50 - 110 μm, such as 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm or the range composed of any two of them.

[0135] The above non-woven fabric can be prepared by conventional methods in the art, and no special limitation is imposed thereon. For example, using raw materials for forming non-woven fabrics (such as the above-mentioned trunk fibers and binder fibers, etc.), the non-woven base paper is formed by a conventional device in the art such as an inclined wire paper machine, and then the formed fiber base paper obtained is subjected to hot calendering treatment by a hot press. The hot press is, for example, a combination of a steel roll / soft roll or a steel roll / steel roll. The temperature of the hot calendering treatment is, for example, 100°C - 300°C. After the hot calendering treatment, the non-woven fabric is prepared.

[0136] The separation membrane support provided by the embodiments of the present invention includes the above non-woven fabric and a support membrane layer compounded with the non-woven fabric. The support membrane layer is at least located on the first fiber layer on the surface layer of the non-woven fabric.

[0137] Generally, the support membrane layer is located on the surface (coating surface) of the non-woven fabric and extends to at least part of the area inside the non-woven fabric, that is, the support membrane layer is partially located on the coating surface of the non-woven fabric and partially located in at least part of the area inside the non-woven fabric.

[0138] Specifically, the above support membrane layer may include an organic membrane layer. Compounding the above non-woven fabric with the organic membrane layer can provide a support effect for the organic membrane layer, and at the same time is conducive to improving the bonding strength between the non-woven fabric and the support membrane layer, and avoiding phenomena such as delamination and peeling.

[0139] In some embodiments, the support membrane layer may include one or more of polysulfone (PSF), polyethersulfone, polyarylethersulfone, polyphenylene ether, polyvinylidene fluoride, polyarylethersulfone ketone, polyacrylonitrile, polypropylene, and cellulose acetate. For example, the support membrane layer may include a polysulfone layer mainly formed of polysulfone, a polyethersulfone layer mainly formed of polyethersulfone, a polyarylethersulfone layer mainly formed of polyarylethersulfone, a polyphenylene ether layer mainly formed of polyphenylene ether, a polyvinylidene fluoride layer mainly formed of polyvinylidene fluoride, a polyarylethersulfone ketone layer mainly formed of polyarylethersulfone ketone, a polyacrylonitrile layer mainly formed of polyacrylonitrile, a polypropylene layer mainly formed of polypropylene, and a cellulose acetate layer mainly formed of cellulose acetate.

[0140] In specific implementation, a material for forming a support film layer (such as PSF, etc.) can be mixed with a solvent to prepare a coating solution. The coating solution is coated on the coating surface of the non-woven fabric (i.e., the outer surface of the first fiber layer on its surface layer), and then the coating solution is cured to form a coating layer (i.e., the support film layer), thereby realizing the composite of the support film layer and the non-woven fabric. Among them, the solvent used may specifically include organic solvents, such as including N,N-dimethylformamide (DMF) and / or N-methylpyrrolidone (NMP), etc., but is not limited thereto.

[0141] For example, polysulfone can be dissolved in N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP) to prepare a polysulfone solution (i.e., the coating solution). The polysulfone solution is coated on the non-woven fabric, then placed in water for phase separation, and then taken out of the water and dried. Specifically, it can be dried at room temperature to cure and form a polysulfone layer (support film layer), thus obtaining a separation membrane support.

[0142] As described above, by using the above-mentioned composite of the non-woven fabric and the support film layer, strong bonding between the support film layer and the non-woven fabric can be achieved, avoiding phenomena such as delamination and peeling, and having advantages such as reducing the material consumption of the support film layer, reducing costs, simplifying the process, improving the film-making efficiency, and reducing the thickness of the separation membrane support.

[0143] The separation membrane support of the embodiment of the present invention uses the above-mentioned non-woven fabric and is composite with the support film layer. It has good structural strength and can be used as a support (carrier) for a liquid separation membrane (or called a filtration membrane). The liquid separation membrane is composite on the separation membrane support to provide a support effect for the liquid support membrane, ensure the exertion of functions such as filtration of the liquid separation membrane, and improve the service life and application range of the liquid separation membrane.

[0144] The liquid separation composite membrane provided by the embodiment of the present invention includes a separation membrane layer and the above-mentioned separation membrane support. The support film layer in the separation membrane support is located between the separation membrane layer and the non-woven fabric.

[0145] Specifically, the separation functional layer is provided on the side of the separation membrane support where the support film layer is provided. The separation functional layer may specifically be located on the surface of the separation membrane support (which is also the surface of the support film layer), or may at least partially extend to at least a partial area inside the separation membrane support (i.e., the separation functional layer is partially located on the surface of the separation membrane support and partially located in at least a partial area inside the separation membrane support).

[0146] Among them, the non-woven fabric has a porous structure and strong mechanical strength. As the non-woven fabric porous support layer of the liquid separation composite membrane, it ensures the structural strength of the liquid separation composite membrane. The support layer is the intermediate support layer of the liquid separation composite membrane. The separation membrane support body formed by its composite with the non-woven fabric serves as the carrier (or base membrane) of the separation functional layer (liquid separation membrane), improving the mechanical strength of the liquid separation composite membrane, taking into account the improvement of the structural stability and service life of the liquid separation composite membrane, etc., and improving the tolerance of the liquid separation composite membrane to high hydraulic pressure during the liquid separation process. At the same time, by using the above-mentioned separation membrane support body, the bonding strength between the membrane layer and the non-woven fabric in the liquid separation composite membrane can also be improved, avoiding phenomena such as delamination and peeling, and the overall thickness of the liquid separation composite membrane can be reduced, improving its separation efficiency. At the same time, it also has the advantages of simple process, low cost, high film-making efficiency, etc.

[0147] The liquid separation composite membrane of the embodiment of the present invention can be used for the treatment of filtration, separation, purification, etc. of liquids such as water bodies, for example, applied to fields such as sewage treatment, water body purification, seawater desalination, pure water preparation, etc. The liquid separation composite membrane of the embodiment of the present invention can realize the separation or purification of liquids based on the pressure-driven membrane separation process. Among them, the separation functional layer can specifically be a liquid separation membrane such as a nanofiltration membrane or a reverse osmosis membrane.

[0148] Generally, the above-mentioned separation functional layer includes an organic membrane layer, for example, includes polyamide materials, such as aromatic polyamide materials, etc. The separation functional layer is, for example, a polyamide layer mainly formed by polyamide materials, etc., but is not limited thereto.

[0149] The present invention will be further introduced through specific embodiments below. In the following examples and comparative examples, the main fiber and the bonding fiber are used, and the non-woven fabric base paper is made by an inclined wire paper machine, and then the obtained base paper is hot-pressed and compounded to obtain the non-woven fabric. In the following examples and comparative examples, the bonding fiber PE / PP represents a PE / PP bicomponent fiber, with PE forming the core layer and PP forming the skin layer.

[0150] In Examples 1 to 24 and Comparative Examples 1 to 5, the materials, fiber linear density, fiber length, each fiber content (i.e., the mass percentage of the fiber in the non-woven fabric) of the main fiber and the bonding fiber used in each fiber layer (the first fiber layer and the second fiber layer), as well as the shape of the profiled cross-section fiber and the perimeter coefficient X of the cross-section of the profiled cross-section fiber LFor parameters such as the number of grooves of the profiled cross-section fiber, the ratio of the width at the widest part of the groove to the diameter of the circumscribed circle of the cross-section of the profiled cross-section fiber (w / D), the ratio of the depth at the deepest part of the groove to the diameter of the circumscribed circle of the cross-section of the profiled cross-section fiber (h / D), and the areal density of each fiber layer, see Tables 1 to 15. For the thickness of the non-woven fabric, the areal density of the non-woven fabric, the longitudinal tensile strength and transverse tensile strength of the non-woven fabric, the droplet diffusion situation, the situation of the coating solution penetrating to the back of the non-woven fabric, and the peel strength of the coating layer (the film body compounded with the non-woven fabric), see Table 16. Among them, the areal density of the non-woven fabric is measured according to GB / T 451.2-2002; the thickness of the non-woven fabric is measured according to GB / T 451.3-2002; the tensile strength of the non-woven fabric (transverse tensile strength and longitudinal tensile strength) is measured according to GB / T 12914-2008; the peel strength of the coating layer (polysulfone layer) relative to the non-woven fabric is measured according to GB / T 2792-2014; the perimeter coefficient of the cross-section of the profiled cross-section fiber is measured according to FZ / T 50002-2013.

[0151] In addition, the diffusion situation of the coating solution on the non-woven fabric is evaluated according to the following process: Mix polysulfone (PSF) and N,N-dimethylformamide (DMF) in a mass ratio of 16:84 to prepare a polysulfone solution; Cut out 3 flat and non-creased non-woven fabric specimens of 10 cm × 10 cm, fix the specimens flat on the specimen holder, and keep the specimens from being deformed by external forces; Use a dropper to suck an appropriate amount of the polysulfone solution, drop 1 drop (about 0.05 mL) of the polysulfone solution on the specimen, and the distance between the dropper tip and the specimen surface does not exceed 1 cm, and the dropper angle is about 45°; Carefully observe the droplet diffusion and penetration situation, use a timer to measure the time required for the droplet to contact the specimen surface until it is completely diffused and penetrated (no longer showing specular reflection), calculate the average diffusion time of the 3 specimens, and evaluate the droplet diffusion situation according to the following criteria:

[0152] (1)◎ - The time for complete diffusion and penetration < 10 s, good level;

[0153] (2)○ - The time for complete diffusion and penetration is 10 to 30 s (inclusive), medium level;

[0154] (3)△ - The time for complete diffusion and penetration is 30 (exclusive) to 60 s, poor level;

[0155] (4)× - The time for complete diffusion and penetration > 60 s, unacceptable level.

[0156] In addition, for the case where the coating solution penetrates to the back surface of the non-woven fabric, during measurement, by visual observation of the human eye, the evaluation is carried out based on the percentage of the area of the region with the coating solution on the back surface (outer surface) of the non-woven fabric in the total area of the back surface (outer surface) of the non-woven fabric per square meter. The evaluation criteria are as follows: ◎ - the percentage of the area penetrating to the back surface < 5%, a good level; ○ - the percentage of the area penetrating to the back surface is 5 - 15% (inclusive), a medium level; △ - the percentage of the area penetrating to the back surface is 15 (exclusive) - 50%, a poor level; × - the percentage of the area penetrating to the back surface > 50%, a non-usable level.

[0157] Example 1

[0158] 1. Non-woven fabric

[0159] The non-woven fabric of this Example 1 is composed of a first fiber layer and a second fiber layer. The composition and fiber parameters of each fiber layer are shown in Table 1.

[0160] Table 1

[0161]

[0162] 2. Separation membrane support (composite membrane of non-woven fabric and polysulfone layer (support membrane layer))

[0163] The non-woven fabric was cut into samples with a size of 210 mm × 297 mm, and a coating solution for forming a polysulfone layer (the mass fraction of polysulfone in the coating solution was 7.5%, and the mass fraction of N-methylpyrrolidone was 92.5%) was manually coated on the outer surface of its first fiber layer using a coater or a wire bar, and then immersed in water for phase separation. After 10 minutes, it was taken out and dried at room temperature to form a polysulfone layer, thereby obtaining the separation membrane support.

[0164] Example 2

[0165] The non-woven fabric of this Example 2 is composed of a first fiber layer and a second fiber layer. The composition and fiber parameters of each fiber layer are shown in Table 2. Except for the differences shown in Table 2, the other conditions of the non-woven fabric and the separation membrane support in this Example 2 are the same as those in Example 1.

[0166] Table 2

[0167]

[0168] Example 3

[0169] The non-woven fabric of this Example 3 is composed of a first fiber layer and a second fiber layer. The composition and fiber parameters of each fiber layer are shown in Table 3. Except for the differences shown in Table 3, the other conditions of the non-woven fabric and the separation membrane support in this Example 3 are the same as those in Example 1.

[0170] Table 3

[0171]

[0172] Example 4

[0173] The non-woven fabric of this Example 4 is composed of a first fiber layer and a second fiber layer, and the composition and fiber parameters of each fiber layer are shown in Table 4. Except for the differences shown in Table 4, the other conditions of the non-woven fabric and the separation membrane support in this Example 4 are the same as those in Example 1.

[0174] Table 4

[0175]

[0176] Example 5

[0177] The non-woven fabric of this Example 5 is composed of a first fiber layer and a second fiber layer, and the composition and fiber parameters of each fiber layer are shown in Table 5. Except for the differences shown in Table 5, the other conditions of the non-woven fabric and the separation membrane support in this Example 5 are the same as those in Example 1.

[0178] Table 5

[0179]

[0180] Example 6

[0181] The non-woven fabric of this Example 6 is composed of a first fiber layer and a second fiber layer, and the composition and fiber parameters of each fiber layer are shown in Table 6. Except for the differences shown in Table 6, the other conditions of the non-woven fabric and the separation membrane support in this Example 6 are the same as those in Example 2.

[0182] Table 6

[0183]

[0184] Example 7

[0185] The non-woven fabric of this Example 7 is composed of a first fiber layer and a second fiber layer, and the composition and fiber parameters of each fiber layer are shown in Table 7. Except for the differences shown in Table 7, the other conditions of the non-woven fabric and the separation membrane support in this Example 7 are the same as those in Example 6.

[0186] Table 7

[0187]

[0188] Examples 8 to 23: Different from Example 2 in that the shapes of the profiled-section fibers in the first fiber layer and / or the second fiber layer are different, as specifically shown in Table 8. Except for the differences shown in Table 8, the remaining conditions are the same as those in Example 2.

[0189] Table 8

[0190]

[0191] Example 24

[0192] The non-woven fabric of this Example 24 is composed of a first fiber layer and a second fiber layer. The composition of each fiber layer and the fiber parameters are shown in Table 9. Except for the differences shown in Table 9, the other conditions of the non-woven fabric of this Example 24 and the separation membrane support are the same as those in Example 1.

[0193] Table 9

[0194]

[0195] Example 25

[0196] The non-woven fabric of this Example 25 is composed of a first fiber layer and a second fiber layer. The composition of each fiber layer and the fiber parameters are shown in Table 10. Except for the differences shown in Table 10, the other conditions of the non-woven fabric of this Example 25 and the separation membrane support are the same as those in Example 1.

[0197] Table 10

[0198]

[0199] Comparative Example 1

[0200] In the non-woven fabric of this Comparative Example 1, the main fibers in both the first fiber layer and the second fiber layer are respectively circular cross-section main fibers, as shown in Table 11 specifically. Except for the differences shown in Table 11, the other conditions of the non-woven fabric of this Comparative Example 1 and the separation membrane support are the same as those in Example 2.

[0201] Table 11

[0202]

[0203] Comparative Example 2

[0204] In the non-woven fabric of this Comparative Example 2, the content of the profiled cross-section main fibers in the second fiber layer is too large, as shown in Table 12 specifically. Except for the differences shown in Table 12, the other conditions of the non-woven fabric of this Comparative Example 2 and the separation membrane support are the same as those in Example 2.

[0205] Table 12

[0206]

[0207] Comparative Example 3

[0208] In the non-woven fabric of this Comparative Example 3, the content of the profiled cross-section main fibers in the second fiber layer is too small, as shown in Table 13 specifically. Except for the differences shown in Table 13, the other conditions of the non-woven fabric of this Comparative Example 3 and the separation membrane support are the same as those in Example 2.

[0209] Table 13

[0210]

[0211] Comparative Example 4

[0212] In the non-woven fabric of Comparative Example 4, the second fiber layer does not contain profiled-section trunk fibers, as shown in Table 14 specifically. Except for the differences shown in Table 14, the other conditions of the non-woven fabric and the separation membrane support in Comparative Example 4 are the same as those in Example 1.

[0213] Table 14

[0214]

[0215] Comparative Example 5

[0216] In the non-woven fabric of Comparative Example 5, the second fiber layer does not contain profiled-section trunk fibers, as shown in Table 15 specifically. Except for the differences shown in Table 15, the other conditions of the non-woven fabric and the separation membrane support in Comparative Example 5 are the same as those in Example 2.

[0217] Table 15

[0218]

[0219] Table 16

[0220]

[0221] Compared with Comparative Example 1, in Examples 2, 6 to 23, profiled-section trunk fibers are introduced into the first fiber layer and the second fiber layer of the non-woven fabric, which can significantly improve the strength of the non-woven fabric and its peel strength from the polysulfone layer, and is beneficial to the adsorption of the coating liquid by the non-woven fabric, significantly improving the spreading, diffusion and penetration performance of the coating liquid on the coating surface of the non-woven fabric, and can avoid the situation of penetration to the back surface of the non-woven fabric.

[0222] Compared with Comparative Examples 2, 3, and 5, in Examples 2, 6 to 23, profiled-section trunk fibers are introduced into the second fiber layer, and the mass fraction of the profiled-section trunk fibers in the trunk fibers of the second fiber layer is in the range of 10% to 60%, which can take into account improving the strength of the non-woven fabric and its peel strength from the polysulfone layer, while improving the spreading, diffusion and penetration performance of the coating liquid on the coating surface of the non-woven fabric, and can avoid the situation of penetration to the back surface of the non-woven fabric.

[0223] It can be seen from Example 1 and Comparative Example 4, and Example 2 and Comparative Example 5 that introducing profiled-section trunk fibers into the second fiber layer of the non-woven fabric can significantly improve the strength of the non-woven fabric and its peel strength from the polysulfone layer, and is beneficial to the adsorption of the coating liquid by the non-woven fabric, improving the diffusion and penetration performance of the coating liquid on the coating surface of the non-woven fabric, and can avoid the situation of penetration to the back surface of the non-woven fabric.

[0224] As can be seen from Example 1 and Example 5, and Example 2 and Example 6, relatively speaking, all the main fibers in the first fiber layer are profiled-section main fibers (Example 1 and Example 2), which can further improve the strength of the non-woven fabric and its peel strength from the polysulfone layer. At the same time, it is beneficial for the non-woven fabric to adsorb the coating liquid, making the coating liquid have better diffusion and penetration properties on the coating surface of the non-woven fabric, and can avoid the situation of penetrating to the back surface of the non-woven fabric.

[0225] Compared with Example 7, in Example 6, the difference in the mass fraction of the profiled-section fibers in the first fiber layer and the second fiber layer is greater than 10%, which can further improve the strength of the non-woven fabric and its peel strength from the polysulfone layer.

[0226] Compared with Example 4, in Example 1, profiled-section fibers with grooves on the surface are introduced into the first fiber layer and the second fiber layer, which can further improve the strength of the non-woven fabric and its peel strength from the polysulfone layer. At the same time, it is beneficial for the non-woven fabric to adsorb the coating liquid, making the coating liquid have better diffusion and penetration properties on the coating surface of the non-woven fabric, and can avoid the situation of penetrating to the back surface of the non-woven fabric.

[0227] Compared with Example 20 and Example 22, in Example 2, the h / D of the profiled-section main fibers in the first fiber layer and the second fiber layer is not greater than 80%, which can further improve the strength of the non-woven fabric and its peel strength from the polysulfone layer.

[0228] Compared with Example 21 and Example 23, in Example 2, the w / D of the profiled-section main fibers in the first fiber layer and the second fiber layer is not less than 10%, which can further improve the strength of the non-woven fabric and its peel strength from the polysulfone layer.

[0229] Compared with Example 24 (the linear density of the main fiber is relatively large) and Example 25 (the linear density of the main fiber is relatively small), in Example 1, the linear density of the main fibers in the first fiber layer and the second fiber layer is in the range of 0.4 - 1.8 dtex, which can further improve the strength of the non-woven fabric and its peel strength from the polysulfone layer. At the same time, it can also take into account maintaining good diffusion and penetration properties of the coating liquid on the coating surface of the non-woven fabric, and can avoid the situation of penetrating to the back surface of the non-woven fabric.

[0230] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-woven fabric, characterized in that, it comprises a first fiber layer and a second fiber layer which are stacked, and the surface layer on at least one side of the non-woven fabric is the first fiber layer; both the first fiber layer and the second fiber layer respectively comprise main fibers, the main fibers comprise profiled cross-section main fibers and circular cross-section main fibers, the mass fraction of the profiled cross-section main fibers in the main fibers of the first fiber layer is greater than the mass fraction of the profiled cross-section main fibers in the main fibers of the second fiber layer, and the mass fraction of the profiled cross-section main fibers in the main fibers of the second fiber layer is 10% to 60%.

2. The non-woven fabric according to claim 1, characterized in that, the content of the profiled cross-section main fibers in the first fiber layer is greater than the content of the profiled cross-section main fibers in the second fiber layer, and the difference between the mass fraction of the profiled cross-section main fibers in the first fiber layer and the mass fraction of the profiled cross-section main fibers in the second fiber layer is not less than 10%.

3. The non-woven fabric according to claim 1, characterized in that, the surface layer on one side of the non-woven fabric is the first fiber layer, and the surface layer on the other side is the second fiber layer.

4. The non-woven fabric according to claim 1, characterized in that, In at least one of the first fiber layer and the second fiber layer, the perimeter coefficient X of the cross-section of at least a part of the profiled-section trunk fibers L satisfies 1 < X L ≤ 5.

5. The non-woven fabric according to any one of claims 1-4, characterized in that, at least part of the profiled cross-section main fibers in at least one of the first fiber layer and the second fiber layer are provided with grooves on the surface; Preferably, the width at the widest part of the groove is not less than 10% of the diameter of the circumscribed circle of the cross-section of the profiled cross-section main fiber; Preferably, the depth at the deepest part of the groove is not greater than 80% of the diameter of the circumscribed circle of the cross-section of the profiled cross-section main fiber; Preferably, the number of the grooves on the surface of the profiled cross-section main fiber is one or more, and when there are multiple grooves, the multiple grooves are distributed circumferentially along the profiled cross-section main fiber; Preferably, the groove extends axially along the profiled cross-section main fiber and penetrates the profiled cross-section main fiber; Preferably, the number of the grooves is less than or equal to 20.

6. The non-woven fabric according to any one of claims 1-4, characterized in that, at least one of the following conditions is satisfied: a. The linear density of the main fibers of the first fiber layer is 0.4 to 1.8 dtex; b. The linear density of the main fibers of the second fiber layer is 0.4 to 1.8 dtex; c. The length of the main fibers in the first fiber layer is 3 to 7 mm; d. The length of the main fibers in the second fiber layer is 3 to 7 mm.

7. The non-woven fabric according to any one of claims 1-4, characterized in that, both the first fiber layer and the second fiber layer respectively comprise binder fibers, and the softening point of the main fibers is greater than the softening point of the binder fibers; Preferably, the length of the binder fibers in the first fiber layer is 3 to 7 mm; Preferably, the diameter of the binder fibers in the first fiber layer is 6 to 18 μm; Preferably, the mass fraction of the binder fibers in the first fiber layer is 15% to 35%; Preferably, the length of the binder fibers in the second fiber layer is 3 to 7 mm; Preferably, the diameter of the binder fibers in the second fiber layer is 6 to 18 μm; Preferably, the mass fraction of the binder fibers in the second fiber layer is 20% to 40%.

8. The non-woven fabric according to any one of claims 1-4, characterized in that the mass ratio of the first fiber layer to the non-woven fabric is 10% to 30%; Preferably, the thickness of the non-woven fabric is 50 to 110 μm; Preferably, the areal density of the non-woven fabric is 50 to 100 g / m 2 .

9. A separation membrane support, characterized in that it comprises the non-woven fabric according to any one of claims 1-8, and a support membrane layer composite with the non-woven fabric, and the support membrane layer is at least located on the first fiber layer on the surface layer of the non-woven fabric; Preferably, the support membrane layer comprises an organic membrane layer; Preferably, the support membrane layer comprises one or more of polysulfone, polyethersulfone, polyarylethersulfone, polyphenylene oxide, polyvinylidene fluoride, polyarylethersulfone ketone, polyacrylonitrile, polypropylene, and cellulose acetate.

10. A liquid separation composite membrane, characterized in that it comprises a separation functional layer and the separation membrane support according to claim 9, and the support membrane layer in the separation membrane support is located between the separation functional layer and the non-woven fabric.

Images