Paper-based waterproof material and preparation method thereof

Abstract

The invention belongs to the technical field of material surface treatment, and discloses a paper-based waterproof material and a preparation method thereof. The paper-based waterproof material comprises a paper base and a waterproof coating attached to the surface of the paper base, the waterproof coating comprises a pre-coating layer, the pre-coating layer is formed by dispersing hollow glass beads with the surfaces modified by a silane coupling agent in a film-forming agent, the mass of the hollow glass beads accounts for 5%-100% of the solid content of the film-forming agent, and the pre-coating layer is of a micron-sized coarse structure; the surface modification layer is polydimethylsiloxane adsorbed on the surface of the pre-coating layer through a vapor deposition process, and the dosage of the polydimethylsiloxane is 10%-50% of the mass of the hollow glass beads. The silane modified hollow glass beads and the film-forming agent are compounded to form the pre-coating layer, then polydimethylsiloxane is adsorbed on the surface of the pre-coating layer through a vapor deposition process, the waterproof coating layer with a micro-nano graded coarse structure is constructed, and meanwhile the triple targets of high hydrophobicity, high waterproof grade and low cost are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material surface treatment, in particular to a paper-based waterproof material and a preparation method thereof. BACKGROUND

[0002] Paper-based materials are mainly composed of plant cellulose fibers. Due to the presence of a large number of hydrophilic hydroxyl groups on the cellulose molecular chain and the porous structure between the fibers, paper-based materials generally exhibit strong hydrophilicity. In the presence of water or a humid environment, paper-based materials are prone to water absorption, softening and strength reduction, which greatly limits their application in food packaging, outdoor paper, building templates and other fields.

[0003] To achieve the waterproof performance of paper-based materials, the industry usually adopts the following technical paths: (1) Nanoparticles construct super-hydrophobic surface: The existing technology discloses coating metal oxide nanoparticles (such as ZnO, Al2O3, Fe3O4, etc.) on the surface of paper-based materials to construct a micro-nano rough structure, and then obtaining a super-hydrophobic surface by chemical vapor deposition of polydimethylsiloxane (PDMS). However, the binding force between nanoparticles and paper-based fibers is weak, and the coating is prone to micro-cracks when subjected to water impact or mechanical bending, which makes it difficult to improve the actual waterproof level. In addition, nanoparticles (such as fumed SiO2, nano TiO2) are expensive (80-250 yuan / kg), which is not conducive to large-scale industrial application. (2) Hollow glass microspheres and waterborne polyurethane composite: Another technology uses silane coupling agent to modify hollow glass microspheres (HGM) and composite with waterborne polyurethane (WPU) to obtain a hydrophobic coating on the surface of the substrate. HGM, as a lightweight and low-cost (less than 40 yuan / kg) inorganic filler, has the advantages of good chemical stability. However, such coating can only achieve a hydrophobic level (contact angle usually < 120°), lacks effective low surface energy modification means, and has limited water pressure resistance, which is difficult to meet the high-level waterproof demand. (3) Another technology uses silane modified HGM and siloxane prepolymer containing reactive groups (such as vinyl or hydrogen-containing groups) to form a composite coating through chemical cross-linking reaction and curing. However, this technology must use active prepolymers that can participate in the reaction, and the coating is formed by chemical cross-linking curing, which is complex and has harsh curing conditions. At the same time, this system relies on the direct blending of siloxane and filler, and the compatibility of macromolecular PDMS and filler is poor, which is prone to phase separation and coating defects. In addition, the reactive prepolymers have high viscosity, and it is difficult to form a uniform and dense coating on the surface of paper-based materials.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The present application aims to at least solve any of the above technical problems, and provides a paper-based waterproof material and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the first technical solution adopted by the present application is: A paper-based waterproof material comprises a paper base and a waterproof coating attached to the surface of the paper base, wherein the waterproof coating comprises: a pre-coating layer formed by dispersing hollow glass microspheres with surface modified by a silane coupling agent in a film-forming agent, the mass of the hollow glass microspheres being 5%-100% of the solid content of the film-forming agent, the pre-coating layer having a micron-level rough structure; a surface modification layer of polydimethylsiloxane adsorbed on the surface of the pre-coating layer by a vapor deposition process, the amount of polydimethylsiloxane being 10%-50% of the mass of the hollow glass microspheres.

[0007] Preferably, the film-forming agent is at least one selected from the group consisting of water-based polyurethane, acrylic emulsion, hydroxy-acrylic emulsion, and water-based epoxy resin.

[0008] Preferably, the silane coupling agent is at least one selected from the group consisting of amino-type, epoxy-type, vinyl-type, methacryloyloxy-type, sulfur-type, and phenyl-type silane coupling agents, and the amount is 0.5%-25% of the mass of the hollow glass microspheres.

[0009] Preferably, the hollow glass microspheres are soda-lime borosilicate glass microspheres with a particle size of 10-85 μm and at least one selected from the group consisting of low-density type, medium-density type, and high-density type.

[0010] Preferably, the paper base is selected from the group consisting of wood pulp paper, bamboo pulp paper, and recycled paper.

[0011] Preferably, the polydimethylsiloxane is at least one selected from the group consisting of trimethylsiloxy-terminated inert type, hydroxyl-terminated type, vinyl-terminated type, and amino-terminated type.

[0012] The second technical solution adopted by the present application is: The preparation method of any of the above paper-based waterproof materials comprises the following steps: After surface activation treatment, the hollow glass microspheres are modified using a silane coupling agent to obtain modified hollow glass microspheres; After mixing the modified hollow glass microspheres with a film-forming agent, the mixture is coated on the surface of the paper base and solidified to form a pre-coating layer having a micron-level rough structure; The pre-coating layer is placed above polydimethylsiloxane, and vapor deposition treatment is performed at 70-300°C for 15s or more to allow the polydimethylsiloxane to be adsorbed on the surface of the pre-coating layer.

[0013] Preferably, the vapor deposition treatment is performed at 100-200°C for 90s or more.

[0014] Preferably, the surface activation treatment is at least one selected from the group consisting of hydrothermal treatment, alkali treatment, plasma treatment, and ultraviolet treatment.

[0015] Preferably, the coating method is blade coating, spraying or casting, and the wet coating amount is 10-150 g / m2.

[0016] Compared with the prior art, the present application has the following beneficial effects: The present application builds a waterproof coating with micro-nano hierarchical rough structure by compounding silane-modified hollow glass microbeads with film-forming agent to form a pre-coating layer, and then adsorbing polydimethylsiloxane on the surface by gas deposition process. The present application realizes the three goals of high hydrophobicity, high waterproof grade and low cost at the same time through step-by-step compounding of specific proportions, breaking the technical limitation that high performance must be accompanied by high cost.

[0017] The present application adopts a two-step process of first coating a pre-coating layer to build a skeleton, and then modifying the surface by gas deposition, which has the following structural advantages compared with the method of directly blending PDMS with fillers in the prior art: (1) strong interfacial bonding: HGM forms chemical bonding with film-forming agent through silane coupling agent, and then firmly adheres to paper fibers through film-forming agent, avoiding the problem of easy falling off of nanoparticles; (2) dense and complete surface: PDMS is uniformly coated on the rough structure surface formed by HGM through gas deposition, filling possible micropores and forming a continuous low-surface-energy barrier; (3) uniform and controllable thickness: the coating structure can be accurately regulated by controlling the wet coating amount and gas deposition time.

[0018] The preparation method of the present application has simple process steps, only two processes of coating (which can adopt conventional methods such as blade coating, spraying, casting, etc.) and gas deposition, without the need for complex chemical reaction control or expensive equipment. The HGM / film-forming agent coating used in the present application has a fast curing rate, the gas deposition process is mature, and it is easy to combine with existing paper product processing production lines, having good industrialization prospects. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0020] The first embodiment of the present application provides a paper-based waterproof material, which comprises a paper base and a waterproof coating attached to the surface of the paper base, and the waterproof coating comprises: The pre-coating layer is formed by dispersing hollow glass microbeads modified by a silane coupling agent on a film-forming agent, and the mass of the hollow glass microbeads is 5%-100% of the solid content of the film-forming agent, and the pre-coating layer has a micron-level rough structure; A surface modification layer of polydimethylsiloxane (PDMS) is adsorbed on the surface of the pre-coating layer by a vapor deposition process, and the amount of the PDMS is 10%-50% of the mass of the hollow glass microspheres.

[0021] In the present embodiment, the pre-coating layer is formed by dispersing modified HGM in a film-forming agent, and the HGM forms a micron-level rough structure in the coating layer to endow the paper-based material with water resistance and a certain hydrophobicity basis. The surface modification layer is formed by adsorbing PDMS on the surface of the pre-coating layer by a vapor deposition process to further improve the surface hydrophobicity. This pre-coating layer constructs a rough skeleton combined with a surface modification layer to provide a layered structure with low surface energy, realizing the synergistic waterproof effect of the rough structure and low surface energy.

[0022] In the preferred embodiment, the film-forming agent is selected from at least one of water-based polyurethane, acrylic emulsion, hydroxy acrylic emulsion, or water-based epoxy resin. Among them, the water-based polyurethane (WPU) can be selected from one or more of non-ionic, anionic, cationic, aliphatic polyether, or aromatic polyether. The selection of these film-forming agent types belongs to the conventional technical means, and the person skilled in the art can select according to the specific application scene and performance requirements of the paper-based material. In some preferred embodiments, the mass of the hollow glass microspheres is 30%-65% of the solid content of the film-forming agent.

[0023] It should be noted that the solid content of the film-forming agent in the present application refers to the mass of the solid component actually forming the film in the film-forming agent product, rather than the total mass of the film-forming agent emulsion or solution. Since the solid content of different film-forming agents is different, the calculation should be based on the mass of the solid component. For example, when using a water-based polyurethane film-forming agent, the amount is converted according to the solid content.

[0024] In the preferred embodiment, the silane coupling agent is selected from at least one of amino type, epoxy type, vinyl type, methacryloyloxy type, sulfur type, or phenyl type silane coupling agent, and the amount is 0.5%-25% of the mass of the hollow glass microspheres, preferably 3%-15%. Among them, the amino type coupling agent such as γ-aminopropyl triethoxysilane (KH550), the epoxy type coupling agent such as γ-glycidyl ether propyl trimethoxysilane (KH560), are all commonly used industrial products. The process conditions such as temperature, pH, solvent, and time of the silane coupling agent are determined according to the type selected, and the process conditions are all referred to the conventional use process, and are not specially protected.

[0025] In the preferred embodiment, the hollow glass microspheres are soda lime borosilicate glass microspheres, and the particle size is 10-85 μm, selected from at least one of low density type, medium density type, or high density type.

[0026] In a preferred embodiment, the paper base is selected from wood pulp paper, bamboo pulp paper or recycled paper. The wood pulp paper can be selected from cultural paper and packaging paper, such as coniferous pulp (long fiber, high strength) or broadleaf pulp (short fiber, high smoothness); the non-wood pulp paper can be selected from cotton pulp paper, bamboo pulp paper, etc.; the recycled paper is generally waste pulp paper, which is made of recycled waste paper and is commonly used for packaging, newsprint, etc.

[0027] In a preferred embodiment, the polydimethylsiloxane (PDMS) is selected from at least one of trimethylsiloxy-terminated inert type, hydroxyl-terminated, vinyl-terminated or amino-terminated. Among them, the PDMS terminated by inert groups is also selected from one or more of low, medium and high viscosity, which endows the coating with low surface energy and hydrophobic properties. The amount of PDMS is generally 10%-200% of the mass of HGM, preferably 10%-50%.

[0028] Due to the good enrichment and fixation of HGM on the film former, the amount of film former can be greatly reduced. At the same time, HGM itself has ultraviolet reflection performance, which is an inherent property of HGM as an inorganic filler, and can endow the paper base material with certain ultraviolet protection ability. In terms of cost, the price of HGM with a specification of 10-85 μm is generally below 40 yuan / kg, while the price of fumed nano-silicon dioxide is about 100 yuan / kg (hydrophobically modified above 250 yuan / kg), and the price of rutile type nano-titanium dioxide (30 nm) can reach about 200 yuan / kg. Therefore, the use of HGM to replace nano-materials can significantly reduce production costs.

[0029] The second embodiment of the present application provides a preparation method of a paper base waterproof material, comprising the following steps: After surface activation treatment of the hollow glass microbeads, modification is carried out using a silane coupling agent to obtain modified hollow glass microbeads; After mixing the modified hollow glass microbeads with the film former, the pre-coating layer with micron-level rough structure is formed by coating on the surface of the paper base and solidifying; The pre-coating layer is placed above the polydimethylsiloxane, and gas phase deposition treatment is carried out at 70-300℃ for more than 15s, so that the polydimethylsiloxane is adsorbed on the surface of the pre-coating layer.

[0030] In the present embodiment, the surface activation treatment is to destroy the inert silicon-oxygen network on the surface of HGM, so as to generate or expose active silicon hydroxyl (-Si-OH) and enhance the reactivity. The activation methods include hydrothermal treatment, alkali treatment, plasma treatment or ultraviolet treatment. In the hydrothermal treatment, attention should be paid to water isolation during the treatment, and only high-pressure water vapor is used for HGM activation. The temperature is generally controlled at 100-250°C, preferably 100-160°C, and the time is controlled at 1h-4h, preferably 1h-2.5h. After treatment, drying is performed to obtain hydrothermally activated HGM. In the alkali treatment, the concentration of the alkaline solution is generally 5%-20%, the stirring time is controlled at 1h-3h, and the temperature is 60-80°C. Subsequently, filtration and drying are performed to obtain alkali-activated HGM. However, the alkali treatment may have a great impact on the structure of HGM, and is generally not preferred. In the plasma treatment, oxygen plasma, nitrogen plasma, nitrogen radicals and the like are generally used to activate the surface of HGM, and the temperature is controlled at about 200°C.

[0031] In the silane coupling agent modification step, the activated HGM is mixed with a silane coupling agent solution for reaction. For example, 8% of silane coupling agent KH550 by mass of HGM can be dissolved in 1.6 times of 97% ethanol solution by mass of HGM, and stirred at room temperature for 30min; or other conventional silane modification processes can be used. After the reaction is completed, conventional drying means is used for drying, the solvent content for modifying HGM is controlled at 0%-15% by mass of HGM, and the drying time is controlled at 12-24h to obtain modified HGM.

[0032] In the coating step, the modified HGM is mixed with a film-forming agent to obtain a HGM / film-forming agent mixed emulsion. The emulsion can be coated on the surface of the paper-based material by means of scraping, spraying, spinning, brushing, casting and the like. The amount of the mixed emulsion on the paper per unit area is generally 10g / m 2 -150g / m 2 , preferably 20-60g / m 2 . After coating, solidification is performed to obtain a uniform HGM / film-forming agent pre-coating layer.

[0033] In the vapor deposition step, PDMS with a mass of 10%-200% (preferably 10%-50%) of the mass of HGM is placed at the bottom of a container, and the pre-coating layer is placed above the PDMS liquid (for example, at a distance of 5cm). The whole is heated at 70-300°C (preferably 100-200°C) for more than 15s (preferably more than 90s), and finally a waterproof coating layer after vapor deposition treatment is obtained. It should be noted that longer time does not bring better results, but causes waste of energy.

[0034] From the above, the application can be seen by uniformly mixing the activated modified HGM and the film forming agent, first forming a dense micron-sized rough surface on the paper base, giving the paper base good water resistance and certain hydrophobicity, then using gas deposition technology to adsorb PDMS on the rough structure surface of HGM, further improving the hydrophobicity of the paper base, so as to realize the waterproof function of the paper base material. The method realizes the synergistic improvement of high hydrophobicity and high waterproof grade while controlling the cost.

[0035] The following provides a plurality of specific embodiments to explain the paper base waterproof material, the preparation method and the performance in detail.

[0036] The information of some reagents used in the specific embodiments of the application is as follows: Hollow glass microspheres (HGM), HS42, HL42, industrial grade, Zhengzhou Shengleite Hollow Microsphere New Material Co., Ltd.; Anhydrous ethanol (CH3CH2OH), analytical pure, Chengdu Jinshan Chemical Reagent Co., Ltd.; Gamma-aminopropyl triethoxysilane (KH550), ≥98.0%, China Reagent Co., Ltd.; Gamma-glycidoxypropyltrimethoxysilane (KH560), 97%, Nanjing Chemical Reagent Co., Ltd.; Dimethyl silicone oil (PDMS), PMX-200, viscosity ~ 20 mPa.s, Shanghai Aladdin Biochemical Science and Technology Co., Ltd.; Anionic waterborne polyurethane (WPU), RU2301, solid content 37.0%-39.0%, Sichuan Dawei Technology Co., Ltd.; Non-ionic waterborne polyurethane (WPU), NU2580, solid content 14.0%-16.0%, Sichuan Dawei Technology Co., Ltd.; Bamboo pulp paper, Zhejiang Manerxi Paper Technology Co., Ltd.; Wood pulp paper, Dongguan Fangzhou Paper Trade Co., Ltd.

[0037] Example 1 Preparation of paper base waterproof material (1) Hydrothermal activation of HS42 type HGM in a high-temperature and high-pressure hydrothermal reactor at 120℃ for 120min, and then drying to obtain hydrothermal activated HGM; (2) Dissolve 8% of silane coupling agent KH550 equivalent to the mass of HGM in 1.6 times of 97% ethanol solution equivalent to the mass of HGM, and stir at room temperature for 30min; (3) Add the hydrothermal activated HGM obtained in (1) to the solution in (2) and stir uniformly, and dry to obtain KH550 modified HGM; (4) 15 parts of KH550 modified HGM were uniformly mixed with 100 parts of RU2301 anionic WPU to obtain an HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated on the surface of wood pulp paper by using a scraping process, and a uniform HGM / WPU coating was obtained by standing and curing, with a wet coating amount of about 30 g / m 2 ; (6) PDMS with a mass of 50% of HGM was placed at the bottom of the container, and the HGM / WPU coating was placed 5 cm above the PDMS liquid, and the whole was heated at 200°C for 90s, and finally a water-repellent coating after gas phase deposition treatment was obtained.

[0038] Example 2 Preparation of paper-based waterproof material (1) HS42 type HGM was hydrothermally activated in a high-temperature and high-pressure hydrothermal reactor at 140°C for 120 min, and then dried to obtain hydrothermally activated HGM; (2) The hydrothermally activated HGM, silane coupling agent KH560 equivalent to 5% of the mass of HGM, and ethanol solution equivalent to 1.5 times the mass of HGM were uniformly mixed, stirred at 130°C for 60 min, and dried to obtain KH550 modified HGM; (3) 5 parts of KH560 modified HGM were uniformly mixed with 100 parts of RU2301 anionic WPU to obtain an HGM / WPU mixed emulsion; (4) The HGM / WPU mixed emulsion was coated on the surface of bamboo pulp paper by using a spinning process, and a uniform HGM / WPU coating was obtained by standing and curing, with a wet coating amount of about 30 g / m 2 ; (5) PDMS with a mass of 50% of HGM was placed at the bottom of the container, and the HGM / WPU coating was placed 5 cm above the PDMS liquid, and the whole was heated at 180°C for 6 min, and finally a water-repellent coating after gas phase deposition treatment was obtained.

[0039] Example 3 Preparation of paper-based waterproof material (1) HS42 type HGM was hydrothermally activated in a high-temperature and high-pressure hydrothermal reactor at 120°C for 90 min, and then dried to obtain hydrothermally activated HGM; (2) Silane coupling agent KH550 equivalent to 8% of the mass of HGM was dissolved in 97% ethanol solution equivalent to 1.6 times the mass of HGM, and stirred at room temperature for 30 min; (3) The hydrothermally activated HGM obtained in (1) was added to the solution in (2) and stirred uniformly, and then dried to obtain KH550 modified HGM; (4) Mix 10 parts of KH550 modified HGM with 100 parts of NU2580 nonionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a casting process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 220℃ for 4min to finally obtain the waterproof coating after vapor deposition treatment.

[0040] Example 4: Preparation of paper-based waterproof material (1) Mix 1 part of HS42 type HGM with 250 parts of 0.5 mol / L NaOH solution at 60℃ and stir for 60 min. Then filter and dry to obtain alkali-activated HGM. (2) The base-activated HGM, silane coupling agent KH560 (equivalent to 5% of the mass of HGM), and ethanol solution (equivalent to 1.5 times the mass of HGM) were uniformly mixed and stirred at 130℃ for 60 min. After drying, KH560 modified HGM was obtained. (3) Mix 5 parts of KH560 modified HGM with 100 parts of NU2580 nonionic WPU evenly to obtain HGM / WPU mixed emulsion; (4) The HGM / WPU mixed emulsion was coated onto the surface of bamboo pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (5) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 220℃ for 4min to finally obtain the waterproof coating after vapor deposition treatment.

[0041] Example 5: Preparation of paper-based waterproof material (1) Mix 1 part of HS42 type HGM with 250 parts of 0.5 mol / L NaOH solution at 60℃ and stir for 40 min. Then filter and dry to obtain alkali-activated HGM. (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the alkali-activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 5 parts of KH560 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a spin coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 6min to finally obtain the waterproof coating after vapor deposition treatment.

[0042] Example 6 Preparation of paper-based waterproof material (1) Mix 1 part of HS42 type HGM with 250 parts of 0.5 mol / L NaOH solution at 80℃ and stir for 60 min. Then filter and dry to obtain alkali-activated HGM. (2) The base-activated HGM, silane coupling agent KH560 (equivalent to 5% of the mass of HGM), and ethanol solution (equivalent to 1.5 times the mass of HGM) were uniformly mixed and stirred at 130℃ for 60 min. After drying, KH560 modified HGM was obtained. (3) Mix 25 parts of KH560 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (4) The HGM / WPU mixed emulsion was coated onto the surface of bamboo pulp paper using a casting process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (5) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 180℃ for 90s to finally obtain the waterproof coating after vapor deposition treatment.

[0043] Example 7: Preparation of Paper-Based Waterproof Material (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 25 parts of KH550 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a spin coating process, and then allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 180℃ for 6min to finally obtain the waterproof coating after vapor deposition treatment.

[0044] Example 8 Preparation of paper-based waterproof material (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 2 parts of KH550 modified HGM with 100 parts of NU2580 nonionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of bamboo pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 220℃ for 15s to finally obtain the waterproof coating after vapor deposition treatment.

[0045] Example 9 Preparation of paper-based waterproof material (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Hydraulically activated HGM, silane coupling agent KH560 equivalent to 5% of the mass of HGM, and ethanol solution equivalent to 1.5 times the mass of HGM are uniformly mixed and stirred at 130℃ for 60 min. After drying, KH560 modified HGM is obtained. (3) Mix 15 parts of KH560 modified HGM with 100 parts of RU2301 ionic WPU evenly to obtain HGM / WPU mixed emulsion; (4) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a casting process, and then allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (5) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 60s to finally obtain the waterproof coating after vapor deposition treatment.

[0046] Example 10 Preparation of paper-based waterproof material (1) HL42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM. (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 15 parts of KH550 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of bamboo pulp paper using a casting process, and then allowed to cure to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 10min to finally obtain the waterproof coating after vapor deposition treatment.

[0047] Comparative Example 1 Compared to Example 1, the main difference is that PDMS vapor deposition is replaced by blending, specifically as follows: (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 15 parts of KH550 modified HGM, 100 parts of RU2301 anionic WPU and 8 parts of PDMS evenly to obtain HGM / PDMS / WPU mixed emulsion; (5) The HGM / PDMS / WPU mixed emulsion was coated onto the surface of wood pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 After drying, a waterproof coating is obtained.

[0048] Comparative Example 2 Compared with Example 1, the main difference is that HGM is not activated. The specific method is as follows: (1) Weigh a certain amount of HS42 type HGM and dry it directly without activation; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 15 parts of KH550 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 90s to finally obtain the waterproof coating after vapor deposition treatment.

[0049] Comparative Example 3 Compared with Example 1, the main difference is that silane modification is not performed. The specific method is as follows: (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Mix 15 parts of hydrothermally activated HGM with 100 parts of RU2301 anionic WPU to obtain an HGM / WPU mixed emulsion; (3) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m².2 ; (4) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 90s to finally obtain the waterproof coating after vapor deposition treatment.

[0050] Comparative Example 4 Compared to Example 1, the main difference is that HGM is not used. The specific method is as follows: (1) RU2301 type WPU emulsion was coated onto the surface of wood pulp paper using a blade coating process, and then allowed to cure statically to obtain a uniform WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (2) Place 50% of the mass of WPU in PDMS at the bottom of the container, place the WPU coating 5cm above the PDMS liquid, and heat the whole at 200℃ for 90s to finally obtain the waterproof coating after vapor deposition treatment.

[0051] Comparative Example 5 Compared to Example 1, the main difference is the absence of vapor deposition of PDMS; the specific method is as follows: (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 15 parts of KH550 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 After drying, a waterproof coating is obtained.

[0052] Comparative Example 6 Compared with Example 1, the main difference lies in the excessive use of HGM, specifically as follows: (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 60 parts of KH550 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 90s to finally obtain the waterproof coating after vapor deposition treatment.

[0053] Comparative Example 7 Compared with Example 1, the main difference lies in the excessively high HGM activation temperature. The specific method is as follows: (1) HS42 type HGM was hydrothermally activated at 200℃ for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 15 parts of KH550 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 90s to finally obtain the waterproof coating after vapor deposition treatment.

[0054] Comparative Example 8 Compared to Example 1, the main difference is that an excess of WPU is used instead of HGM. This comparative example aims to verify whether, without adding HGM, an excess of WPU alone can sufficiently fill the voids in the paper-based fibers to achieve water penetration resistance. The specific method is as follows: (1) The RU2301 anionic WPU solution was coated onto the surface of wood pulp paper using a blade coating process, and then allowed to cure statically to obtain a uniform WPU coating. The wet coating amount was approximately 120 g / m². 2 ; (2) Place 20% of the mass of WPU in PDMS at the bottom of the container, place the WPU coating 5cm above the PDMS liquid, and heat the whole at 200℃ for 90s to finally obtain the waterproof coating after vapor deposition treatment.

[0055] Comparative Example 9 Compared with Example 1, the main difference lies in the shorter vapor deposition time. The specific method is as follows: (1) HS42 type HGM was hydrothermally activated at 120°C for 120 min in a high temperature and high pressure hydrothermal reactor, and then dried to obtain hydrothermally activated HGM; (2) Dissolve 8% of the silane coupling agent KH550 (equivalent to 1.6 times the mass of HGM) in a 97% ethanol solution and stir at room temperature for 30 min. (3) Add the hydrothermally activated HGM obtained in (1) to the solution in (2) and stir until homogeneous. After drying, KH550 modified HGM is obtained. (4) Mix 15 parts of KH550 modified HGM with 100 parts of RU2301 anionic WPU evenly to obtain HGM / WPU mixed emulsion; (5) The HGM / WPU mixed emulsion was coated onto the surface of wood pulp paper using a blade coating process, and allowed to cure statically to obtain a uniform HGM / WPU coating. The wet coating amount was approximately 30 g / m². 2 ; (6) Place 50% of HGM in PDMS at the bottom of the container, place the HGM / WPU coating 5cm above the PDMS liquid, and heat the whole thing at 200℃ for 10s to finally obtain the waterproof coating after vapor deposition treatment.

[0056] Blank example 1 Wood pulp paper that retains its original state without any coating treatment.

[0057] Blank example 2 Bamboo pulp paper that retains its original state without any coating treatment.

[0058] The instantaneous contact angle, water droplet penetration time, and waterproof rating of the products prepared in the above embodiments, comparative examples, and blank examples were tested. The results are shown in Table 1.

[0059] Table 1 .

[0060] As shown in Table 1, Examples 1-10 all achieved IPX5 or IPX6 waterproof ratings, with water droplet penetration times ≥330 seconds (significantly longer than the comparative examples). The contact angles ranged from 102.8° to 138.5°, demonstrating that the present invention achieves excellent waterproof performance across a wide range of process parameters. Experimental data confirms that the contact angle reflects surface hydrophobicity, while the IPX rating reflects structural density; these are different dimensions. The present invention achieves a synergistic improvement in both dimensions by simultaneously optimizing both dimensions through a step-by-step strategy of first constructing a dense HGM / film-forming agent framework (structural waterproofing) and then vapor-depositing PDMS (surface hydrophobicity). While Comparative Example 8 achieved a high IPX5 waterproof rating, its contact angle was significantly lower than the examples, and the coating amount needed to be increased fourfold, resulting in a significant increase in cost.

[0061] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A paper-based waterproof material, characterized in that, Includes a paper base and a waterproof coating adhered to the surface of the paper base, the waterproof coating comprising: The pre-coating is formed by dispersing hollow glass microspheres with a surface modified by a silane coupling agent in a film-forming agent. The mass of the hollow glass microspheres is 5%-100% of the solid content of the film-forming agent. The pre-coating has a micron-level rough structure. The surface modification layer consists of polydimethylsiloxane adsorbed onto the surface of the pre-coated layer via a vapor deposition process, wherein the amount of polydimethylsiloxane is 10%-50% of the mass of the hollow glass microspheres.

2. The paper-based waterproof material as described in claim 1, characterized in that, The film-forming agent is selected from at least one of waterborne polyurethane, acrylic emulsion, hydroxyl acrylic emulsion, or waterborne epoxy resin.

3. The paper-based waterproof material as described in claim 1, characterized in that, The silane coupling agent is selected from at least one of amino, epoxy, vinyl, methacryloyloxy, thio, or phenyl silane coupling agents, and the amount used is 0.5%-25% of the mass of the hollow glass microspheres.

4. The paper-based waterproof material as described in claim 1, characterized in that, The hollow glass microspheres are soda lime borosilicate glass microspheres with a particle size of 10-85 μm, selected from at least one of low-density, medium-density or high-density types.

5. The paper-based waterproof material as described in claim 1, characterized in that, The paper base is selected from wood pulp paper, bamboo pulp paper, or recycled paper.

6. The paper-based waterproof material as described in claim 1, characterized in that, The polydimethylsiloxane is selected from at least one of trimethylsiloxy-terminated inert type, hydroxy-terminated, vinyl-terminated or amino-terminated.

7. The method for preparing the paper-based waterproof material according to any one of claims 1-6, characterized in that, Includes the following steps: After surface activation treatment, hollow glass microspheres are modified with silane coupling agents to obtain modified hollow glass microspheres. After mixing modified hollow glass microspheres with a film-forming agent, the mixture is coated onto the surface of a paper substrate and cured to form a pre-coating with a micron-level rough structure. The pre-coating is placed above polydimethylsiloxane and subjected to vapor deposition at 70-300°C for more than 15 seconds, so that the polydimethylsiloxane is adsorbed onto the surface of the pre-coating.

8. The preparation method according to claim 7, characterized in that, Vapor deposition was performed at 100-200℃ for more than 90 seconds.

9. The preparation method according to claim 7, characterized in that, The surface activation treatment is selected from at least one of hydrothermal treatment, alkaline treatment, plasma treatment, or ultraviolet treatment.

10. The preparation method according to claim 7, characterized in that, The coating method is scraping, spraying, or casting, and the wet coating amount is 10-150 g / m².