High-temperature-resistant laminated paper and preparation method thereof

Abstract

The invention discloses high-temperature-resistant laminated paper and a preparation method thereof. Relates to the technical field of laminated paper. The preparation method of the high-temperature-resistant laminated paper comprises the following steps: S1, pulping slurry to obtain paper pulp; s2, uniformly mixing the paper pulp with a high-temperature-resistant filler, a wet strength agent and a sizing agent in a batching tank, and stirring to obtain mixed pulp; s3, the mixed pulp is subjected to paper quantification, net feeding, wet paper web treatment, drying and heat setting treatment operation, and preliminary paper is obtained; s4, uniformly mixing a high-temperature-resistant coating and a flame retardant, coating the surface of the primary paper with the mixture to form a high-temperature-resistant isolating layer, and drying to obtain paper; and S5, carrying out calendaring treatment on paper, compounding the paper with a high-temperature-resistant material, bonding the compounded paper with kraft paper, slitting, and rewinding to obtain the high-temperature-resistant laminated paper.

Description

Technical Field

[0001] The present invention relates to the technical field of laminated paper, and in particular to high-temperature resistant laminated paper and a preparation method thereof. Background Art

[0002] In its early days, the laminated kraft paper industry relied on traditional manual processes, resulting in low efficiency and poor quality. However, with breakthroughs in papermaking technology and adhesive research and development, the laminated kraft paper industry experienced rapid growth in the 21st century. Manufacturers increased their R&D investment, shifting their products toward more environmentally friendly and functional products. The application of automated and intelligent production technologies has improved production efficiency, stabilized product quality, and reduced labor costs.

[0003] Ordinary kraft paper suffers from issues such as insufficient heat resistance, easy moisture absorption leading to adhesion, and a short service life during high-temperature lamination. Furthermore, some cushioning materials, such as asbestos fiber, while offering good heat resistance, carry a carcinogenic risk and have been banned in many countries. Aramid fiber and fluororubber lose their cushioning properties and thickness under prolonged vacuum and high pressure, and the fluororubber surface coating is prone to static electricity, impacting product quality.

[0004] In numerous industrial applications, such as electronics and automotive manufacturing, the demand for paper's high-temperature resistance is increasing. Existing ordinary paper is prone to strength loss, deformation, and even combustion in high-temperature environments, making it unable to meet the demands of specific processes. For example, during the lamination process of electronic circuit boards, which must withstand high temperatures and high pressures, ordinary paper is unable to withstand this.

[0005] Paper properties are improved by selecting appropriate raw materials, such as long-fiber wood pulp, adding heat-resistant inorganic or synthetic fibers, and using chemical additives such as heat-resistant additives, wet-strength agents, and fillers. Furthermore, the pulping and papermaking processes are optimized, and special post-processing steps are added, such as surface coating with heat-resistant coatings, heat-setting treatments, or compounding with heat-resistant materials, to enhance kraft paper's heat resistance, moisture resistance, anti-blocking, and high strength. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing an environmentally friendly laminated paper with high strength and high temperature resistance, so as to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for preparing high-temperature resistant pressed paper comprises the following steps: S1: beating the pulp to obtain paper pulp; S2: uniformly mixing the pulp, high temperature resistant filler, wet strength agent and sizing agent in a batching tank and stirring to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0008] Furthermore, the pulp component includes any one or two of kraft softwood pulp, bamboo pulp, and hemp pulp.

[0009] Furthermore, the pulp components include, by mass percentage, 60-80 wt% of kraft softwood pulp and 20-40 wt% of bamboo pulp or hemp pulp.

[0010] Furthermore, during the preparation of the mixed slurry, the components include, by mass percentage, 5-10 wt% of high-temperature resistant filler, 0.5-1.5 wt% of wet strength agent, 0.3-0.8 wt% of sizing agent, and the rest is pulp; the wet strength agent is polyamide epichlorohydrin; and the sizing agent is any one of alkyl ketene dimer and paraffin emulsion.

[0011] Furthermore, the preparation process of the high temperature resistant filler comprises the following steps: a. Boron trioxide powder, ferric oxide powder and carbon powder were stirred and ball-milled for 15 to 18 hours to obtain a mixed powder; the metal oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve the silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4-5, and ultrasonicate to obtain a hydrolyzed KH560 solution; add spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonicate to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60-65°C, seal and stir for 12-13 hours, and obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5-6 mol / L sodium hydroxide solution, heating to 120-125°C for hydrolysis for 24 hours, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16-18 hours, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60-65°C to obtain hydroxylated boron nitride nanosheets. d. Add hydroxylated boron nitride nanosheets to a KH560-grafted spherical boron nitride dispersion, heat to 60-65°C for 12-13 hours, filter, alternately wash the product with deionized water and anhydrous ethanol, and vacuum dry at 70-75°C to obtain a high-temperature resistant filler.

[0012] Furthermore, in the preparation process of spherical boron nitride, the molar ratio of boron trioxide powder, iron trioxide powder and carbon powder in the mixture is 1:1:6; the amount of metal oxide added is 2.0~2.5wt% of the total mass of the mixture; the nitrogen atmosphere heat treatment process includes: heating to 1000℃ at a rate of 20℃ / min, and then heating to 2000℃ at a rate of 200℃ / h, and the heat treatment time is 5~6h; the metal oxide includes: any one of cerium oxide and calcium oxide.

[0013] Furthermore, during the preparation of the KH560 grafted spherical boron nitride dispersion, the mass ratio of spherical boron nitride to KH560 was 1:(0.8~1).

[0014] Furthermore, during the preparation of the high-temperature resistant filler, the mass ratio of hydroxylated boron nitride nanosheets to KH560 grafted spherical boron nitride is (1~2):(2~3).

[0015] Furthermore, in the preliminary paper preparation process, the drying operation is divided into two-stage drying, the front-stage drying temperature is 80~120℃, the rear-stage drying temperature is 130~160℃, the front-stage drying time is 4~8 minutes, and the rear-end drying time is 1~2 minutes, and the moisture content of the paper is controlled at 4%~6%; heat setting treatment: the paper is baked at 180~220℃ for 2~5 minutes; in the paper preparation process, the high-temperature resistant coating includes any one or more of silicone resin or silica sol, and the coating thickness is 5~15μm; the flame retardant includes any one or more of aluminum hydroxide and magnesium hydroxide; the high-temperature resistant material includes any one of aluminum foil and glass fiber cloth; in the preparation process of high-temperature resistant pressed paper, the bonding temperature is 120~150℃ and the pressure is 0.3~0.5MPa.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are: in order to improve the anisotropic thermal conductivity of boron nitride fillers, the present invention uses boron trioxide powder, ferric oxide powder and carbon powder as raw materials, and forms a solid solution by adding metal oxides during high-temperature heat treatment, thereby reducing the Fe-B x melting point and promote the spherical Fe–B x The boron nitride filler with a spherical structure is prepared by nitriding the sphere surface to achieve excellent grain growth and cleanliness. Unlike traditional spherical boron nitride fillers prepared by bonding boron nitride nanosheets to the surface of epoxy resin microspheres, the boron nitride filler prepared in this invention has higher thermal conductivity.

[0017] The present invention further modifies the spherical boron nitride with a KH560 silane coupling agent and compounds it with hydroxylated boron nitride nanosheets. The spherical boron nitride promotes the dispersion of the boron nitride nanosheets in the pulp. The interlaced distribution and arrangement of the spherical boron nitride and the two-dimensional boron nitride nanosheets greatly enhance the heat conduction path, improve the heat conduction efficiency, and impart high-temperature resistance to the laminated paper. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0019] In the following examples, the paper basis weight is 200 g / m², which can be adjusted according to the application; the web density is 0.2%; the paper basis weight error is ±3%; the average size of the hexagonal boron nitride is 1.5 μm; and the remaining raw materials are commercially available.

[0020] Example 1: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 93.5 wt% of paper pulp, 5 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0021] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0022] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 2.5 wt% of calcium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 1 g of hydroxylated boron nitride nanosheets to a dispersion containing 2 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in a vacuum at 70°C to obtain a high-temperature resistant filler.

[0023] Example 2: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 93.5 wt% of paper pulp, 5 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0024] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0025] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 2.5 wt% of cerium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 1 g of hydroxylated boron nitride nanosheets to a dispersion containing 2 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in a vacuum at 70°C to obtain a high-temperature resistant filler.

[0026] Example 3: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 93.5 wt% of paper pulp, 5 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0027] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0028] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 2.5 wt% of cerium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 2 g of hydroxylated boron nitride nanosheets to a dispersion containing 3 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in vacuum at 70°C to obtain a high-temperature resistant filler.

[0029] Example 4: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 88.5 wt% of paper pulp, 10 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0030] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0031] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 2.5 wt% of cerium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 2 g of hydroxylated boron nitride nanosheets to a dispersion containing 3 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in vacuum at 70°C to obtain a high-temperature resistant filler.

[0032] Comparative Example 1: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 83.5 wt% of paper pulp, 15 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0033] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0034] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 2.5 wt% of cerium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 1 g of hydroxylated boron nitride nanosheets to a dispersion containing 2 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in a vacuum at 70°C to obtain a high-temperature resistant filler.

[0035] Comparative Example 2: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 93.5 wt% of paper pulp, 5 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0036] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0037] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 5 wt% of cerium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 1 g of hydroxylated boron nitride nanosheets to a dispersion containing 2 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in a vacuum at 70°C to obtain a high-temperature resistant filler.

[0038] Comparative Example 3: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 93.5 wt% of paper pulp, 5 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0039] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0040] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 2.5 wt% of cerium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 1 g of hydroxylated boron nitride nanosheets to a dispersion containing 4 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in a vacuum at 70°C to obtain a high-temperature resistant filler.

[0041] Comparative Example 4: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: S1: beating the pulp to obtain paper pulp; S2: 93.5 wt% of paper pulp, 5 wt% of high temperature resistant filler, 1 wt% of polyamide epichlorohydrin, and 0.5 wt% of alkyl ketene dimer are uniformly mixed in a batching tank and stirred to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

[0042] During the preliminary preparation of paper, the drying operation is divided into two stages, with the front drying temperature being 80°C and the rear drying temperature being 130°C. The front drying time is 4 minutes and the rear drying time is 1 minute, and the moisture content of the paper is controlled at 4%; heat setting treatment: the paper is baked at 180°C for 2 minutes; during the preparation of paper, the high-temperature resistant coating is silicone resin with a coating thickness of 5μm; the flame retardant is aluminum hydroxide; the high-temperature resistant material is glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120°C and the pressure is 0.3MPa.

[0043] The preparation process of the high temperature resistant filler comprises the following steps: a. 1 mol of boron trioxide powder, 1 mol of ferric oxide powder and 6 mol of carbon powder were stirred and ball-milled for 15 h to obtain a mixed powder; 2.5 wt% of calcium oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve 5 g of silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add 5 g of spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60 ° C, seal and stir the reaction for 12 hours to obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5 mol / L sodium hydroxide solution, heating to 120°C for hydrolysis for 24 h, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16 h, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60°C to obtain hydroxylated boron nitride nanosheets; d. Add 3 g of hydroxylated boron nitride nanosheets to a dispersion containing 1 g of KH560-grafted spherical boron nitride, heat to 60°C for 12 h, filter, wash the product alternately with deionized water and anhydrous ethanol, and dry it in a vacuum at 70°C to obtain a high-temperature resistant filler.

[0044] Comparative Example 5: A high-temperature resistant pressed paper and a preparation method thereof, comprising the following steps: The following is a spherical boron nitride filler prepared by bonding boron nitride nanosheets to the surface of traditional epoxy resin microspheres; The preparation method of the spherical boron nitride comprises the following steps: Self-assembled core-shell epoxy resin microspheres were prepared via environmentally friendly emulsion polymerization using distilled water as the solvent. 8g of bisphenol A epoxy resin was added to a stirred reactor containing 100mL of deionized water at 80°C. 5mg of sodium dodecyl sulfate was added and stirred for 24 hours. 8g of methylhexahydrophthalic anhydride and 0.16g of accelerator DMP-30 were added and stirred thoroughly. 3g of boron nitride nanosheets were then added. The mixture was heated to 120°C and stirred for 2 hours. The mixture was centrifuged for 10 minutes, washed, centrifuged, and freeze-dried to obtain spherical boron nitride nanosheets.

[0045] The remaining steps are the same as those in Example 1.

[0046] Experiment: Samples of the laminated paper prepared in the above examples and comparative examples were taken and the following tests were performed: 1: Thermal stability and appearance change test Sample pretreatment: Kraft paper samples were cut into 50 mm × 50 mm squares. Three replicates were taken for each test. The samples were equilibrated in a standard environment (23°C ± 2°C, 50% RH ± 5%) for 24 hours. High-temperature baking test: Set the oven temperature gradient (e.g., 80°C, 160°C, 200°C), place samples at each temperature point, and set the baking time to 2 hours (simulating a short-term high-temperature scenario) and 24 hours (simulating a long-term high-temperature scenario). Observe the appearance of the samples every 30 minutes and record: color changes (e.g., yellowing, carbonization), surface conditions (e.g., brittleness, delamination, melting), and whether a pungent odor is generated (a sign of thermal decomposition). Calculation of mass loss rate: Weigh the sample before and after baking, and calculate the mass loss rate: Mass loss rate (%) = (mass before baking − mass after baking) / mass before baking × 100%.

[0047] 2: High temperature tensile strength test Sample preparation: dumbbell-shaped tensile specimens were prepared according to GB / T 12914, with 3 parallel specimens in each group.

[0048] High-temperature mechanical properties test: Place the sample in an oven, set the target temperature (e.g., 150°C, 200°C), keep warm for 30 minutes (to allow the sample to be heated evenly), quickly remove the sample, and immediately test the tensile strength using an electronic universal testing machine at a tensile speed of 50 mm / min. Record the breaking load and calculate the tensile strength: Tensile strength (MPa) = breaking load (N) / sample cross-sectional area (mm 2 ) Compare the tensile strength at room temperature and calculate the strength retention rate: Strength retention rate (%) = high temperature strength / room temperature strength × 100%.

[0049] The experimental results are shown in Tables 1 and 2 below.

[0050] Table 1 Thermal stability and appearance change test of high temperature resistant laminated paper

[0051] Table 2 High temperature tensile strength test of high temperature resistant laminated paper

[0052] Conclusion: The laminated paper prepared by the present invention has excellent high temperature resistance.

[0053] In Comparative Example 1, excessive high-temperature resistant filler was added to the pulp, resulting in reduced dispersion of boron nitride nanosheets in the pulp. The paper easily turned yellow, or even carbonized and brittle under high-temperature testing, and its strength was greatly reduced under high-temperature testing.

[0054] In Comparative Example 2, excessive cerium oxide was added, resulting in decreased thermal conductivity of the prepared boron nitride filler. The paper easily turned yellow, or even carbonized and brittle under high-temperature testing, and its strength was significantly reduced under high-temperature testing.

[0055] In Comparative Example 3, excessive spherical boron nitride and a small amount of boron nitride nanosheets were added, which resulted in reduced dispersion of the boron nitride nanosheets in the pulp. The paper easily turned yellow, or even carbonized and brittle under high temperature testing, and its strength was greatly reduced under high temperature.

[0056] In Comparative Example 4, a small amount of spherical boron nitride and an excessive amount of boron nitride nanosheets were added, which resulted in a decrease in the dispersion of the boron nitride nanosheets in the pulp. The paper tended to turn yellow, or even carbonize and become brittle under high temperature testing, and its strength was greatly reduced under high temperature.

[0057] Comparative Example 5 is a spherical boron nitride filler prepared by laminating boron nitride nanosheets on the surface of traditional epoxy resin microspheres. This causes the paper to easily turn yellow, or even carbonize and become brittle under high temperature testing, and its strength is greatly reduced at high temperatures.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing high temperature resistant pressed paper, characterized in that: The steps include: S1: beating the pulp to obtain paper pulp; S2: uniformly mixing the pulp, high temperature resistant filler, wet strength agent and sizing agent in a batching tank and stirring to obtain a mixed slurry; S3: The mixed pulp is subjected to paper quantification, screen printing, wet paper web treatment, drying, and heat setting operations to obtain preliminary paper; S4: mixing the high-temperature resistant coating and the flame retardant evenly and applying the mixture to the surface of the preliminary paper to form a high-temperature resistant isolation layer, and drying the mixture to obtain the paper; S5: calendering the paper, laminating it with a high-temperature resistant material, and then gluing it with kraft paper, slitting it, and rewinding it to obtain high-temperature resistant laminated paper.

2. The method for preparing high temperature resistant pressed paper according to claim 1, characterized in that: The pulp components include any one or two of sulfate softwood pulp, bamboo pulp and hemp pulp.

3. The method for preparing high temperature resistant pressed paper according to claim 2, characterized in that: The pulp components include, by mass percentage, 60-80 wt% of kraft softwood pulp and 20-40 wt% of bamboo pulp or hemp pulp.

4. The method for preparing high temperature resistant pressed paper according to claim 1, characterized in that: During the preparation of the mixed slurry, the components include, by mass percentage, 5-10 wt% of high-temperature resistant filler, 0.5-1.5 wt% of wet strength agent, 0.3-0.8 wt% of sizing agent, and the rest is pulp; the wet strength agent is polyamide epichlorohydrin; the sizing agent is any one of alkyl ketene dimer and paraffin emulsion.

5. The method for preparing high temperature resistant pressed paper according to claim 4, characterized in that: The preparation process of the high temperature resistant filler comprises the following steps: a. Boron trioxide powder, ferric oxide powder and carbon powder were stirred and ball-milled for 15 to 18 hours to obtain a mixed powder; the metal oxide was added to the mixed powder, stirred uniformly, heat-treated in a nitrogen atmosphere, and the product was washed with 6N hydrochloric acid to obtain spherical boron nitride; b. Dissolve the silane coupling agent KH560 in a mixture of anhydrous ethanol and water, add glacial acetic acid and stir, adjust the pH to 4-5, and ultrasonically treat to obtain a hydrolyzed KH560 solution; add spherical boron nitride to the mixture of anhydrous ethanol and water, stir, and ultrasonically treat to obtain a boron nitride solution; add the boron nitride solution to the hydrolyzed KH560 solution, heat to 60-65°C, seal and stir for 12-13 hours, and obtain a KH560-grafted spherical boron nitride dispersion; c. ultrasonically dispersing hexagonal boron nitride in a 5-6 mol / L sodium hydroxide solution, heating to 120-125°C for hydrolysis for 24 hours, centrifuging, washing, and ultrasonically dispersing the product in deionized water for 16-18 hours, centrifuging, and filtering the supernatant. The supernatant was then dried under vacuum at 60-65°C to obtain hydroxylated boron nitride nanosheets. d. Add hydroxylated boron nitride nanosheets to a KH560-grafted spherical boron nitride dispersion, heat to 60-65°C for 12-13 hours, filter, alternately wash the product with deionized water and anhydrous ethanol, and vacuum dry at 70-75°C to obtain a high-temperature resistant filler.

6. The method for preparing high temperature resistant pressed paper according to claim 5, characterized in that: During the preparation of spherical boron nitride, the molar ratio of boron trioxide powder, ferric oxide powder, and carbon powder in the mixture is 1:1:6; the amount of metal oxide added is 2.0-2.5wt% of the total mass of the mixture; the nitrogen atmosphere heat treatment process includes: heating to 1000°C at a rate of 20°C / min, then heating to 2000°C at a rate of 200°C / h, and the heat treatment time is 5-6 hours; the metal oxide includes: any one of cerium oxide and calcium oxide.

7. The method for preparing high temperature resistant pressed paper according to claim 5, characterized in that: During the preparation of the KH560 grafted spherical boron nitride dispersion, the mass ratio of spherical boron nitride to KH560 is 1:(0.8~1).

8. The method for preparing high temperature resistant pressed paper according to claim 5, characterized in that: During the preparation of high-temperature resistant fillers, the mass ratio of hydroxylated boron nitride nanosheets to KH560 grafted spherical boron nitride is (1~2):(2~3).

9. The method for preparing high temperature resistant pressed paper according to claim 1, characterized in that: During the preliminary preparation of paper, the drying operation is divided into two stages, with the front-stage drying temperature being 80~120°C and the rear-stage drying temperature being 130~160°C. The front-stage drying time is 4~8 minutes, and the rear-stage drying time is 1~2 minutes, and the moisture content of the paper is controlled at 4%~6%; heat setting treatment: the paper is baked at 180~220°C for 2~5 minutes; during the preparation of paper, the high-temperature resistant coating includes any one or more of silicone resin or silica sol, and the coating thickness is 5~15μm; the flame retardant includes any one or more of aluminum hydroxide and magnesium hydroxide; the high-temperature resistant material includes any one of aluminum foil and glass fiber cloth; during the preparation of high-temperature resistant pressed paper, the bonding temperature is 120~150°C and the pressure is 0.3~0.5MPa.

10. High temperature resistant pressed paper prepared according to the method for preparing high temperature resistant pressed paper according to any one of claims 1 to 9.

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