Low-basis-weight middle separation paper surface enhancement method based on nano coating

Abstract

The invention relates to a method for enhancing the surface of low-basis-weight middle separation paper based on a nano coating, and belongs to the technical field of pulping and papermaking. The core-shell structure nano-composite particles are prepared and added into the coating liquid, so that the surface performance of paper is remarkably improved; rigid support is provided through the mesoporous SiO2 core, the gamma-AlOOH nanosheet densifies the surface through hydrogen bonds, surface energy is reduced by combining zwitterionic modification, and the hardness, smoothness and wear resistance of the middle separation paper are improved. 3-aminopropyltriethoxysilane is combined with fiber hydroxyl, and the electrostatic adsorption effect of zwitterionic surface modification is matched, so that the combination between fibers is remarkably improved, and the powder falling amount is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of pulping and papermaking, and relates to a surface enhancement method for low-weight medium-septum paper based on nano-coating. Background Art

[0002] Low basis weight separator paper is a type of paper widely used in the modern papermaking industry, typically used to produce cartons, packaging materials, and other paper products. Due to its low basis weight, its strength and durability are generally poor, so it is necessary to improve its performance through surface treatment or reinforcement methods.

[0003] In traditional surface enhancement technologies for separator paper, oxidized starch or polyvinyl alcohol (PVA)-based surface sizing agents are commonly used, which form a thin film on the fiber surface through physical adsorption to improve paper performance. However, this method has significant limitations: first, the film-forming hardness of conventional sizing agents is insufficient, and the pencil hardness is usually less than 5H, which makes it difficult to meet the surface scratch resistance requirements of high-end packaging materials; second, the penetration depth of the sizing agent is difficult to control, and the penetration rate exceeds 40%, resulting in insufficient effective film formation on the surface, and excessive penetration will destroy the hydrogen bond network between fibers, resulting in a decrease in tensile strength. In addition, traditional processes often sacrifice air permeability when improving surface properties. For example, although increasing the coating amount can increase hardness, it will cause the air permeability to drop sharply to below 500mL / min, affecting the paper's suitability for applications such as cushioning packaging. These problems are particularly prominent in low-weight separator paper because its fiber structure is loose and the surface treatment window is narrower.

[0004] In recent years, nano-coating technology has been introduced into the papermaking field to break through traditional limitations, but it still faces multiple technical bottlenecks in practical applications. Existing nano-modification schemes mostly use the direct addition of single nanoparticles. Due to the large specific surface area and high surface energy of nanoparticles, they are prone to agglomeration in aqueous systems, resulting in uneven coating distribution and increased density of microscopic defects. In addition, traditional coating processes (such as doctor blade or air knife coating) are difficult to accurately control the penetration gradient of nano-coatings, and often destroy low-quantity paper base structures due to excessive mechanical shear force. Chemically modified fibers are used to enhance binding strength, but such methods require the transformation of the wet-end process of papermaking, have poor compatibility with existing production lines, and modifier residues may affect the food safety of paper. Summary of the Invention

[0005] The present invention aims to provide a method for enhancing the surface of low-weight median paper using a nanocoating. By applying a specific nanocoating to the median paper surface, the paper's surface hardness, smoothness, and abrasion resistance are improved. The nanocoating strengthens the connections between paper fibers, reducing linting and dusting. Furthermore, the coating should exhibit good water stability to prevent degradation of the paper's performance in humid environments.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for surface enhancement of low-weight medium-septum paper based on nano-coating, comprising core-shell structured nanocomposite particles, wherein the preparation method comprises the following steps:

[0008] A1, using hexadecyltrimethylammonium bromide as a template, a mesoporous SiO2 core was prepared by base-catalyzed hydrolysis of ethyl silicate;

[0009] A2. Preload the aminosilane coupling agent into the SiO2 mesopores using a vacuum pulse impregnation method;

[0010] A3, growing a γ-AlOOH shell on the SiO2 surface by pH control in a urea and aluminum nitrate system;

[0011] A4. Zwitterionic surface modification is achieved by alternately immersing in polydimethyldiallylammonium chloride solution and sodium polystyrene sulfonate solution 2-5 times.

[0012] As a preferred technical solution of the present invention, step A1 is specifically performed by dissolving hexadecyltrimethylammonium bromide in deionized water at 40-50°C, stirring to dissolve, and then adding ethyl silicate dropwise at a rate of 0.5-2 mL / min, while adding ammonia water to adjust the pH to 8-10, and continuously stirring at 40-50°C for 18-24 hours to form a white colloid.

[0013] As a preferred technical solution of the present invention, the white colloid generated in step A1 is centrifuged, washed with ethanol, and then heated to 500-600°C at a rate of 2°C / min and calcined for 2-4h to obtain a mesoporous SiO2 core.

[0014] As a preferred technical solution of the present invention, the specific operation of step A2 is to disperse the calcined SiO2 in 0.2-0.8 mol / L 3-aminopropyltriethoxysilane ethanol solution, adjust the pH to 4.5-5.5, vacuum treat at -0.05~-0.1MPa for 20-30min, let it stand for 2 hours and then centrifuge and dry it.

[0015] As a preferred technical solution of the present invention, step A3 is specifically performed as follows: adding 1-3 wt% preloaded SiO2 to deionized water, adding Al(NO3)3·9H2O to a concentration of 0.05-0.2 mol / L, heating to 100-180°C for 6-10 hours, and regulating the pH from 3.0-3.5 to 6.0-7.0 by urea to form a γ-AlOOH nanosheet shell with a thickness of 2-5 nm.

[0016] As a preferred technical solution of the present invention, the zwitterionic surface modification in step A4 includes cationization and anionization; the cationization is soaking in a 0.08-0.12wt% polydimethyldiallyl ammonium chloride solution for 25-35 minutes, and the anionization is treating in a 0.03-0.07wt% sodium polystyrene sulfonate solution for 15-25 minutes; the final Zeta potential is -5mV.

[0017] Furthermore, a method for surface enhancement of low-quantity separator paper based on nano-coating is provided, wherein the coating liquid contains 5.6-7.8% core-shell structure nanocomposite particles, 1.6-2.16% hydroxypropyl guar gum, 0.64-1.2% 3-aminopropyltriethoxysilane, 0.08-0.24% cerium oxide nanocrystals, and the balance is deionized water.

[0018] Furthermore, a method for surface enhancement of low-weight medium-septum paper based on nano-coating comprises the following steps:

[0019] (1) mixing core-shell structured nanocomposite particles, hydroxypropyl guar gum, 3-aminopropyl triethoxysilane, and cerium oxide nanocrystals to prepare a coating liquid with a solid content of 8-12%;

[0020] (2) The coating liquid and pulp raw material are mixed and beaten to form the separator paper.

[0021] As a preferred technical solution of the present invention, the coating liquid in step (1) contains 5.6-7.8% core-shell structured nanocomposite particles, 1.6-2.16% hydroxypropyl guar gum, 0.64-1.2% 3-aminopropyltriethoxysilane, 0.08-0.24% cerium oxide nanocrystals, and the balance is deionized water.

[0022] As a preferred technical solution of the present invention, in step (2), the pulp raw material is adjusted to a fiber concentration of 0.5-3%; and the amount of the coating liquid added is 0.5-2%.

[0023] Beneficial effects of the present invention:

[0024] (1) The present invention significantly improves the surface properties of paper by adding core-shell nanocomposite particles. The mesoporous SiO2 core provides rigid support, while the AlOOH nanosheets densify the surface through hydrogen bonding. Combined with zwitterionic modification, the surface energy is reduced, thereby improving the hardness, smoothness, and wear resistance of the medium-septum paper.

[0025] (2) Strengthening fiber connection based on chemical-physical synergy. The silane coupling agent forms Si-OC covalent bonds with the fiber hydroxyl groups, and the γ-AlOOH shell constructs a three-dimensional hydrogen bond network. Combined with the electrostatic adsorption effect of the PDADMAC / PSS alternating layers, the fiber bonding is significantly improved, and the hair loss rate and powder loss are reduced. DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0027] At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the process steps or preparation methods that are not mentioned in detail are all process steps or preparation methods known to those skilled in the art. Among them, the purchase of some reagents and raw materials is as follows:

[0028] Polydimethyldiallylammonium chloride was purchased from Feymiao Technology Co., Ltd.; sodium polystyrene sulfonate was purchased from Lingyan Biotechnology Co., Ltd.; hydroxypropyl guar gum was purchased from Weimao Biotechnology Co., Ltd.; and cerium oxide nanocrystals were purchased from Yumu (Ningbo) New Materials Co., Ltd.

[0029] Example 1

[0030] A method for surface enhancement of low-weight medium-septum paper based on nano-coating, comprising core-shell structured nanocomposite particles, wherein the preparation method comprises the following steps:

[0031] A1, using hexadecyltrimethylammonium bromide as a template, a mesoporous SiO2 core was prepared by base-catalyzed hydrolysis of ethyl silicate;

[0032] A2. Preload the aminosilane coupling agent into the SiO2 mesopores using a vacuum pulse impregnation method;

[0033] A3, growing a γ-AlOOH shell on the SiO2 surface by pH control in a urea and aluminum nitrate system;

[0034] A4. Zwitterionic surface modification was achieved by alternately immersing the sample in polydimethyldiallylammonium chloride solution and sodium polystyrene sulfonate solution three times.

[0035] The specific operation of step A1 is to dissolve hexadecyltrimethylammonium bromide in deionized water at 40°C, stir and dissolve, then add ethyl silicate dropwise at a rate of 2 mL / min, and simultaneously add ammonia water to adjust the pH to 9. Stir continuously at 40°C for 24 hours to form a white colloid.

[0036] The white colloid generated in step A1 was centrifuged, washed with ethanol, and then heated to 550°C at a rate of 2°C / min and calcined for 3 h to obtain a mesoporous SiO2 core.

[0037] The specific operation of step A2 is to disperse the calcined SiO2 in a 0.5 mol / L 3-aminopropyltriethoxysilane ethanol solution, adjust the pH to 5.0, vacuum treat at -0.08 MPa for 25 minutes, let it stand for 2 hours, and then centrifuge and dry it.

[0038] The specific operation of step A3 is to add 2wt% preloaded SiO2 to deionized water, add Al(NO3)3·9H2O to a concentration of 0.1 mol / L, heat to 140℃ for reaction for 8h, and adjust the pH from 3.0 to 6.8 by urea to form a γ-AlOOH nanosheet shell with a thickness of 3nm.

[0039] The zwitterionic surface modification in step A4 includes cationization and anionization; the cationization is performed by soaking in a 0.1 wt% polydimethyldiallylammonium chloride solution for 30 min, and the anionization is performed by treating in a 0.05 wt% sodium polystyrene sulfonate solution for 20 min; the final Zeta potential is -5 mV.

[0040] The method for surface enhancement of low-weight medium-septum paper based on nano-coating comprises the following steps:

[0041] (1) Hydroxypropyl guar gum was dissolved in 50°C deionized water, stirred and dissolved, and then core-shell particles, 3-aminopropyltriethoxysilane, and cerium oxide nanocrystals were added in sequence. Ultrasonic dispersion was performed for 30 minutes, and the pH was adjusted to 7.5.

[0042] (2) The coating liquid and pulp raw material are mixed and beaten to form the separator paper.

[0043] The coating liquid in step (1) contains 6.7% core-shell structure nanocomposite particles, 1.88% hydroxypropyl guar gum, 0.92% 3-aminopropyl triethoxysilane, 0.16% cerium oxide nanocrystals, and the balance is deionized water.

[0044] In step (2), the pulp raw material is adjusted to a fiber concentration of 1.6%; and the coating liquid is added in an amount of 1%.

[0045] Example 2

[0046] A method for surface enhancement of low-weight medium-septum paper based on nano-coating, comprising core-shell structured nanocomposite particles, wherein the preparation method comprises the following steps:

[0047] A1, using hexadecyltrimethylammonium bromide as a template, a mesoporous SiO2 core was prepared by base-catalyzed hydrolysis of ethyl silicate;

[0048] A2. Preload the aminosilane coupling agent into the SiO2 mesopores using a vacuum pulse impregnation method;

[0049] A3, growing a γ-AlOOH shell on the SiO2 surface by pH control in a urea and aluminum nitrate system;

[0050] A4. Zwitterionic surface modification is achieved by alternately immersing the sample in polydimethyldiallylammonium chloride solution and sodium polystyrene sulfonate solution twice.

[0051] The specific operation of step A1 is to dissolve hexadecyltrimethylammonium bromide in deionized water at 40°C, stir and dissolve, then add ethyl silicate dropwise at a rate of 0.5 mL / min, and simultaneously add ammonia water to adjust the pH to 8. Stir continuously at 40°C for 24 hours to form a white colloid.

[0052] The white colloid generated in step A1 was centrifuged, washed with ethanol, and then heated to 500°C at a rate of 2°C / min and calcined for 4 hours to obtain a mesoporous SiO2 core.

[0053] The specific operation of step A2 is to disperse the calcined SiO2 in a 0.2 mol / L 3-aminopropyltriethoxysilane ethanol solution, adjust the pH to 4.5, vacuum treat at -0.05 MPa for 20 minutes, let it stand for 2 hours, and then centrifuge and dry it.

[0054] The specific operation of step A3 is to add 1wt% preloaded SiO2 to deionized water, add Al(NO3)3·9H2O to a concentration of 0.05mol / L, heat to 100℃ for 6h, and adjust the pH from 3.0 to 6.8 by urea to form a γ-AlOOH nanosheet shell with a thickness of 2nm.

[0055] The zwitterionic surface modification in step A4 includes cationization and anionization; the cationization is performed by soaking in a 0.08 wt % polydimethyldiallyl ammonium chloride solution for 25 min, and the anionization is performed by treating in a 0.03 wt % sodium polystyrene sulfonate solution for 15 min; the final Zeta potential is -5 mV.

[0056] The method for surface enhancement of low-weight medium-septum paper based on nano-coating comprises the following steps:

[0057] (1) Hydroxypropyl guar gum was dissolved in deionized water at 45°C. After stirring and dissolving, core-shell particles, 3-aminopropyltriethoxysilane, and cerium oxide nanocrystals were added in sequence. Ultrasonic dispersion was performed for 30 minutes, and the pH was adjusted to 7.3.

[0058] (2) The coating liquid and pulp raw material are mixed and beaten to form the separator paper.

[0059] The coating liquid in step (1) contains 5.6% core-shell structure nanocomposite particles, 1.6% hydroxypropyl guar gum, 0.64% 3-aminopropyl triethoxysilane, 0.08% cerium oxide nanocrystals, and the balance is deionized water.

[0060] In step (2), the pulp raw material is adjusted to a fiber concentration of 0.5%; and the coating liquid is added in an amount of 0.5%.

[0061] Example 3

[0062] A method for surface enhancement of low-weight medium-septum paper based on nano-coating, comprising core-shell structured nanocomposite particles, wherein the preparation method comprises the following steps:

[0063] A1, using hexadecyltrimethylammonium bromide as a template, a mesoporous SiO2 core was prepared by base-catalyzed hydrolysis of ethyl silicate;

[0064] A2. Preload the aminosilane coupling agent into the SiO2 mesopores using a vacuum pulse impregnation method;

[0065] A3, growing a γ-AlOOH shell on the SiO2 surface by pH control in a urea and aluminum nitrate system;

[0066] A4. Zwitterionic surface modification was achieved by alternately immersing the mixture in polydimethyldiallylammonium chloride solution and sodium polystyrene sulfonate solution for 5 times.

[0067] The specific operation of step A1 is to dissolve hexadecyltrimethylammonium bromide in deionized water at 40°C, stir and dissolve, then add ethyl silicate dropwise at a rate of 2 mL / min, and simultaneously add ammonia water to adjust the pH to 10. Stir continuously at 40°C for 24 hours to form a white colloid.

[0068] The white colloid generated in step A1 was centrifuged, washed with ethanol, and then heated to 600°C at a rate of 2°C / min and calcined for 4 h to obtain a mesoporous SiO2 core.

[0069] The specific operation of step A2 is to disperse the calcined SiO2 in 0.2-0.8 mol / L 3-aminopropyltriethoxysilane ethanol solution, adjust the pH to 5.5, vacuum treat at -0.1 MPa for 30 minutes, let it stand for 2 hours, and then centrifuge and dry it.

[0070] The specific operation of step A3 is to add 3wt% preloaded SiO2 to deionized water, add Al(NO3)3·9H2O to a concentration of 0.2mol / L, heat to 180℃ for 10h, and adjust the pH from 3.0 to 6.8 by urea to form a γ-AlOOH nanosheet shell with a thickness of 5nm.

[0071] The zwitterionic surface modification in step A4 includes cationization and anionization; the cationization is performed by soaking in a 0.12 wt% polydimethyldiallyl ammonium chloride solution for 35 min, and the anionization is performed by treating in a 0.07 wt% sodium polystyrene sulfonate solution for 25 min; the final Zeta potential is -5 mV.

[0072] The method for surface enhancement of low-weight medium-septum paper based on nano-coating comprises the following steps:

[0073] (1) Hydroxypropyl guar gum was dissolved in 55°C deionized water, stirred and dissolved, and then core-shell particles, 3-aminopropyltriethoxysilane, and cerium oxide nanocrystals were added in sequence. Ultrasonic dispersion was performed for 30 minutes, and the pH was adjusted to 7.8.

[0074] (2) The coating liquid and pulp raw material are mixed and beaten to form the separator paper.

[0075] The coating liquid in step (1) contains 7.8% core-shell structure nanocomposite particles, 2.16% hydroxypropyl guar gum, 1.2% 3-aminopropyl triethoxysilane, 0.24% cerium oxide nanocrystals, and the balance is deionized water.

[0076] In step (2), the pulp raw material is adjusted to a fiber concentration of 0.5-3%; and the coating liquid is added in an amount of 0.5-2%.

[0077] Comparative Example 1

[0078] On the basis of Example 1, the preparation of the mesoporous SiO2 core in step A1 was performed without calcining at 550°C for 3h and drying at 60°C for 12h, and the rest was consistent with Example 1.

[0079] Comparative Example 2

[0080] On the basis of Example 1, in step (2), the temperature of the sizing machine trough preheating, the sizing zone and the drying zone were all set to 55° C., and the rest were consistent with Example 1.

[0081] Comparative Example 3

[0082] On the basis of Example 1, in step (2), the sizing machine trough preheating, the sizing zone and the drying zone temperature were all set to 65° C., and the rest were consistent with Example 1.

[0083] Comparative Example 4

[0084] On the basis of Example 1, in step (2), the sizing machine trough preheating, the temperatures of the sizing zone and the drying zone were all set to 88° C., and the rest were consistent with Example 1.

[0085] Comparative Example 5

[0086] On the basis of Example 1, the preparation of core-shell structure was not performed, 6.7% SiO2 and AlOOH particles were added to the coating liquid to directly physically mix the nanoparticles, and the mass ratio of SiO2 and AlOOH was 7:3. The rest was consistent with the example.

[0087] Comparative Example 6

[0088] On the basis of Example 1, the surface modification was performed using a polydimethyldiallyl ammonium chloride solution as the first layer, and the rest was consistent with Example 1.

[0089] Comparative Example 7

[0090] On the basis of Example 1, in the impregnation of Step A2, 3-aminopropyltriethoxysilane was replaced with γ-glycidoxypropyltrimethoxysilane, and the rest was consistent with Example 1.

[0091] Performance testing:

[0092] Surface Hardness: Use a pencil hardness tester, according to standard GB / T6739-2020, to assess the surface hardness of paper. Hardness is typically determined by marking the surface with pencils of varying hardness and observing whether a mark remains.

[0093] Air permeability: Air permeability is tested according to GB / T 458-2008. The standard unit of measurement is mL / min, which is the volume of gas passing through the paper per unit time.

[0094] Wet Strength Retention: According to the standard GB / T 465.2-2008, wet strength retention is a test of the strength of paper in a wet state, which is evaluated by a wet tensile strength test.

[0095] Powder loss rate: Test the powder loss rate of samples according to GB / T20810.

[0096] Surface hardness (H) Air permeability (ml / min) Wet strength retention (%) Powder loss rate (%) Example 1 8 380 92 0.2 Example 2 7 420 89 0.4 Example 3 9 350 88 0.3 Comparative Example 1 4 580 53 2.5 Comparative Example 2 6 420 77 0.7 Comparative Example 3 7 360 82 0.5 Comparative Example 4 5 310 61 1.3 Comparative Example 5 5 520 58 1.1 Comparative Example 6 6 400 62 0.6 Comparative Example 7 6 390 68 1.2

[0097] Comparative Example 1 shows that the failure to remove hexadecyltrimethylammonium bromide by burning results in pore blockage, a decrease in specific surface area, insufficient silane loading, performance degradation, and a powder loss rate that surges to 2.5%.

[0098] By comparing the examples and comparative examples 2-4, it can be seen that low temperature leads to insufficient silane hydrolysis rate, insufficient pre-crosslinking degree, and incomplete coating curing; high temperature causes premature gelation of the coating liquid, which may lead to insufficient penetration depth and discontinuous surface film formation; revealing the importance of sizing gradient temperature control in improving coating performance.

[0099] It can be seen from Comparative Example 5 that the physical mixing of nanoparticles without core-shell interface bonding causes excessive penetration, resulting in deterioration of surface performance; from the comparative examples and Comparative Example 6, it can be seen that the single-layer cationic modification has poor particle dispersibility, and the surface hardness and wet strength retention rate are significantly reduced; from Comparative Example 7, it can be seen that 3-aminopropyltriethoxysilane may form a covalent bond with the fiber hydroxyl group through the amino group, while the epoxy group of γ-glycidyloxypropyltrimethoxysilane needs a ring-opening reaction to generate -OH before binding to the fiber, the reaction energy barrier is high, and the powder loss rate is increased.

[0100] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any indirect modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A nano coating liquid for enhancing the surface of separator paper, characterized by: The nano coating solution contains core-shell structured nanocomposite particles. The preparation method of the core-shell structured nanocomposite particles comprises the following steps: A1, using hexadecyltrimethylammonium bromide as a template, a mesoporous SiO2 core was prepared by base-catalyzed hydrolysis of ethyl silicate; A2, using vacuum pulse impregnation method to preload aminosilane coupling agent into the mesopores of SiO2 core; A3, in a liquid phase containing urea and aluminum nitrate, growing a γ-AlOOH shell on the surface of the SiO2 core treated in step A2 by controlling the pH; A4. After the treatment in step A3, the SiO2 core is alternately immersed in a polydimethyldiallyl ammonium chloride solution and then a sodium polystyrene sulfonate solution at least once to achieve zwitterionic surface modification.

2. The nano coating liquid for enhancing the surface of separator paper according to claim 1, characterized in that: In step A1, the base-catalyzed hydrolysis is to produce ammonia water, and the molar ratio of hexadecyltrimethylammonium bromide, ethyl silicate, ammonia water and deionized water is 1:0.1-0.2:2-3:150-250.

3. The nano coating liquid for enhancing the surface of separator paper according to claim 1, characterized in that: In the impregnation step A2, the concentration of the aminosilane coupling agent is 0.2-0.8 mol / L, and the pH of the impregnation solution is 4.5-5.

5.

4. The nano coating liquid for enhancing the surface of separator paper according to claim 1, characterized in that: In step A3, the concentration of aluminum nitrate is 0.05-0.2 mol / L, the concentration of urea is 0.2-0.4 mol / L, the amount of pre-loaded SiO2 added is 1-3 wt%; and the thickness of the γ-AlOOH shell is 2-5 nm.

5. The nano coating liquid for enhancing the surface of separator paper according to claim 1, characterized in that: The zwitterionic surface modification in step A4 includes cationization and anionization; the cationization is performed by soaking in a 0.08-0.12 wt% polydimethyldiallylammonium chloride solution for 25-35 min, and the anionization is performed by treating in a 0.03-0.07 wt% sodium polystyrene sulfonate solution for 15-25 min.

6. A method for surface enhancement of low-weight medium-septum paper based on nano-coating, characterized by: The nano coating solution as claimed in claim 1 is used for treatment.

7. The method for surface enhancement of low-weight medium-septum paper based on nano-coating according to claim 6, characterized in that: The processing process includes the following steps: (1) mixing core-shell structured nanocomposite particles, hydroxypropyl guar gum, 3-aminopropyl triethoxysilane, and cerium oxide nanocrystals to prepare a coating liquid with a solid content of 8-12%; (2) The coating liquid and pulp raw material are mixed and beaten to form the separator paper.

8. The method for surface enhancement of low-weight medium-septum paper based on nano-coating according to claim 7, characterized in that: The coating liquid in step (1) contains 5.6-7.8% core-shell structure nanocomposite particles, 1.6-2.16% hydroxypropyl guar gum, 0.64-1.2% 3-aminopropyltriethoxysilane, 0.08-0.24% cerium oxide nanocrystals, and the balance is deionized water.

9. The method for surface enhancement of low-basis-weight medium-septum paper based on nano-coating according to claim 7, characterized in that: In step (2), the pulp raw material is adjusted to a fiber concentration of 0.5-3%; and the coating liquid is added in an amount of 0.5-2%.

10. A separator paper, characterized in that: Obtained by the surface enhancement method of low-weight medium-spacing paper based on nano-coating as described in claim 7.